1457c8996SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 41da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 51da177e4SLinus Torvalds * interface as the means of communication with the user level. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 81da177e4SLinus Torvalds * 902c30a84SJesper Juhl * Authors: Ross Biro 101da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 111da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 121da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 131da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 141da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 151da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 161da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 171da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 181da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 191da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 201da177e4SLinus Torvalds */ 211da177e4SLinus Torvalds 221da177e4SLinus Torvalds /* 231da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 241da177e4SLinus Torvalds * : Fragmentation on mtu decrease 251da177e4SLinus Torvalds * : Segment collapse on retransmit 261da177e4SLinus Torvalds * : AF independence 271da177e4SLinus Torvalds * 281da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 291da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 301da177e4SLinus Torvalds * during syn/ack processing. 311da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 321da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 331da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 341da177e4SLinus Torvalds * J Hadi Salim : ECN support 351da177e4SLinus Torvalds * 361da177e4SLinus Torvalds */ 371da177e4SLinus Torvalds 3891df42beSJoe Perches #define pr_fmt(fmt) "TCP: " fmt 3991df42beSJoe Perches 401da177e4SLinus Torvalds #include <net/tcp.h> 41eda7acddSPeter Krystad #include <net/mptcp.h> 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds #include <linux/compiler.h> 445a0e3ad6STejun Heo #include <linux/gfp.h> 451da177e4SLinus Torvalds #include <linux/module.h> 4660e2a778SUrsula Braun #include <linux/static_key.h> 471da177e4SLinus Torvalds 48e086101bSCong Wang #include <trace/events/tcp.h> 4935089bb2SDavid S. Miller 509799ccb0SEric Dumazet /* Refresh clocks of a TCP socket, 519799ccb0SEric Dumazet * ensuring monotically increasing values. 529799ccb0SEric Dumazet */ 539799ccb0SEric Dumazet void tcp_mstamp_refresh(struct tcp_sock *tp) 549799ccb0SEric Dumazet { 559799ccb0SEric Dumazet u64 val = tcp_clock_ns(); 569799ccb0SEric Dumazet 575f6188a8SEric Dumazet tp->tcp_clock_cache = val; 58e6d14070SEric Dumazet tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC); 599799ccb0SEric Dumazet } 609799ccb0SEric Dumazet 6146d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6246d3ceabSEric Dumazet int push_one, gfp_t gfp); 63519855c5SWilliam Allen Simpson 6467edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 6575c119afSEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) 666ff03ac3SIlpo Järvinen { 676ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 686ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 6966f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 709e412ba7SIlpo Järvinen 71e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(skb)->end_seq); 728512430eSIlpo Järvinen 7375c119afSEric Dumazet __skb_unlink(skb, &sk->sk_write_queue); 7475c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); 7575c119afSEric Dumazet 7685369750SCambda Zhu if (tp->highest_sack == NULL) 7785369750SCambda Zhu tp->highest_sack = skb; 7885369750SCambda Zhu 7966f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 80bec41a11SYuchung Cheng if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) 81750ea2baSYuchung Cheng tcp_rearm_rto(sk); 82f19c29e3SYuchung Cheng 83f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 84f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 856a5dc9e5SEric Dumazet } 861da177e4SLinus Torvalds 87a4ecb15aSCui, Cheng /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one 88a4ecb15aSCui, Cheng * window scaling factor due to loss of precision. 891da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 901da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 911da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 921da177e4SLinus Torvalds * invalid. OK, let's make this for now: 931da177e4SLinus Torvalds */ 94cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 951da177e4SLinus Torvalds { 96cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 979e412ba7SIlpo Järvinen 98a4ecb15aSCui, Cheng if (!before(tcp_wnd_end(tp), tp->snd_nxt) || 99a4ecb15aSCui, Cheng (tp->rx_opt.wscale_ok && 100a4ecb15aSCui, Cheng ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) 1011da177e4SLinus Torvalds return tp->snd_nxt; 1021da177e4SLinus Torvalds else 10390840defSIlpo Järvinen return tcp_wnd_end(tp); 1041da177e4SLinus Torvalds } 1051da177e4SLinus Torvalds 1061da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1071da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1081da177e4SLinus Torvalds * 1091da177e4SLinus Torvalds * 1. It is independent of path mtu. 1101da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1111da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1121da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1131da177e4SLinus Torvalds * large MSS. 1141da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1151da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1161da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1171da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1181da177e4SLinus Torvalds * probably even Jumbo". 1191da177e4SLinus Torvalds */ 1201da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1211da177e4SLinus Torvalds { 1221da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 123cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1241da177e4SLinus Torvalds int mss = tp->advmss; 1251da177e4SLinus Torvalds 1260dbaee3bSDavid S. Miller if (dst) { 1270dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1280dbaee3bSDavid S. Miller 1290dbaee3bSDavid S. Miller if (metric < mss) { 1300dbaee3bSDavid S. Miller mss = metric; 1311da177e4SLinus Torvalds tp->advmss = mss; 1321da177e4SLinus Torvalds } 1330dbaee3bSDavid S. Miller } 1341da177e4SLinus Torvalds 1351da177e4SLinus Torvalds return (__u16)mss; 1361da177e4SLinus Torvalds } 1371da177e4SLinus Torvalds 1381da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1396f021c62SEric Dumazet * This is the first part of cwnd validation mechanism. 1406f021c62SEric Dumazet */ 1416f021c62SEric Dumazet void tcp_cwnd_restart(struct sock *sk, s32 delta) 1421da177e4SLinus Torvalds { 143463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1446f021c62SEric Dumazet u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); 1451da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1461da177e4SLinus Torvalds 1476687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1481da177e4SLinus Torvalds 1496687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1501da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1511da177e4SLinus Torvalds 152463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1531da177e4SLinus Torvalds cwnd >>= 1; 1541da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 155c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1561da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1571da177e4SLinus Torvalds } 1581da177e4SLinus Torvalds 15967edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 16040efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 161cf533ea5SEric Dumazet struct sock *sk) 1621da177e4SLinus Torvalds { 163463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 164d635fbe2SEric Dumazet const u32 now = tcp_jiffies32; 1651da177e4SLinus Torvalds 16605c5a46dSNeal Cardwell if (tcp_packets_in_flight(tp) == 0) 16705c5a46dSNeal Cardwell tcp_ca_event(sk, CA_EVENT_TX_START); 16805c5a46dSNeal Cardwell 1694a41f453SWei Wang /* If this is the first data packet sent in response to the 1704a41f453SWei Wang * previous received data, 1714a41f453SWei Wang * and it is a reply for ato after last received packet, 1724a41f453SWei Wang * increase pingpong count. 1731da177e4SLinus Torvalds */ 1744a41f453SWei Wang if (before(tp->lsndtime, icsk->icsk_ack.lrcvtime) && 1754a41f453SWei Wang (u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 1764a41f453SWei Wang inet_csk_inc_pingpong_cnt(sk); 1774a41f453SWei Wang 1784a41f453SWei Wang tp->lsndtime = now; 1791da177e4SLinus Torvalds } 1801da177e4SLinus Torvalds 18167edfef7SAndi Kleen /* Account for an ACK we sent. */ 18227cde44aSYuchung Cheng static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, 18327cde44aSYuchung Cheng u32 rcv_nxt) 1841da177e4SLinus Torvalds { 1855d9f4262SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1865d9f4262SEric Dumazet 1872b195850SEric Dumazet if (unlikely(tp->compressed_ack)) { 188200d95f4SEric Dumazet NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, 1892b195850SEric Dumazet tp->compressed_ack); 1902b195850SEric Dumazet tp->compressed_ack = 0; 1915d9f4262SEric Dumazet if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) 1925d9f4262SEric Dumazet __sock_put(sk); 1935d9f4262SEric Dumazet } 19427cde44aSYuchung Cheng 19527cde44aSYuchung Cheng if (unlikely(rcv_nxt != tp->rcv_nxt)) 19627cde44aSYuchung Cheng return; /* Special ACK sent by DCTCP to reflect ECN */ 197463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 198463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1991da177e4SLinus Torvalds } 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2021da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2031da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2041da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2051da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2061da177e4SLinus Torvalds * This MUST be enforced by all callers. 2071da177e4SLinus Torvalds */ 208ceef9ab6SEric Dumazet void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, 2091da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 21031d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 21131d12926Slaurent chavey __u32 init_rcv_wnd) 2121da177e4SLinus Torvalds { 2131da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2141da177e4SLinus Torvalds 2151da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2161da177e4SLinus Torvalds if (*window_clamp == 0) 217589c49cbSGao Feng (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); 2181da177e4SLinus Torvalds space = min(*window_clamp, space); 2191da177e4SLinus Torvalds 2201da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2211da177e4SLinus Torvalds if (space > mss) 222589c49cbSGao Feng space = rounddown(space, mss); 2231da177e4SLinus Torvalds 2241da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22515d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22615d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 22715d99e02SRick Jones * we will truncate our initial window offering to 32K-1 22815d99e02SRick Jones * unless the remote has sent us a window scaling option, 22915d99e02SRick Jones * which we interpret as a sign the remote TCP is not 23015d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2311da177e4SLinus Torvalds */ 232ceef9ab6SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) 2331da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23415d99e02SRick Jones else 235a337531bSYuchung Cheng (*rcv_wnd) = min_t(u32, space, U16_MAX); 236a337531bSYuchung Cheng 237a337531bSYuchung Cheng if (init_rcv_wnd) 238a337531bSYuchung Cheng *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 23915d99e02SRick Jones 24019bf6261SEric Dumazet *rcv_wscale = 0; 2411da177e4SLinus Torvalds if (wscale_ok) { 242589c49cbSGao Feng /* Set window scaling on max possible window */ 243356d1833SEric Dumazet space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]); 244f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_rmem_max); 245316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 24619bf6261SEric Dumazet *rcv_wscale = clamp_t(int, ilog2(space) - 15, 24719bf6261SEric Dumazet 0, TCP_MAX_WSCALE); 2481da177e4SLinus Torvalds } 2491da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 250589c49cbSGao Feng (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); 2511da177e4SLinus Torvalds } 2524bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2551da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2561da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2571da177e4SLinus Torvalds * frame. 2581da177e4SLinus Torvalds */ 25940efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2601da177e4SLinus Torvalds { 2611da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2628e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2631da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2641da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2651da177e4SLinus Torvalds 2661da177e4SLinus Torvalds /* Never shrink the offered window */ 2671da177e4SLinus Torvalds if (new_win < cur_win) { 2681da177e4SLinus Torvalds /* Danger Will Robinson! 2691da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2701da177e4SLinus Torvalds * we will not be able to advertise a zero 2711da177e4SLinus Torvalds * window in time. --DaveM 2721da177e4SLinus Torvalds * 2731da177e4SLinus Torvalds * Relax Will Robinson. 2741da177e4SLinus Torvalds */ 2758e165e20SFlorian Westphal if (new_win == 0) 2768e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2778e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 278607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2791da177e4SLinus Torvalds } 2801da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2811da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2841da177e4SLinus Torvalds * scaled window. 2851da177e4SLinus Torvalds */ 286ceef9ab6SEric Dumazet if (!tp->rx_opt.rcv_wscale && 287ceef9ab6SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) 2881da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2891da177e4SLinus Torvalds else 2901da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2911da177e4SLinus Torvalds 2921da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2931da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2941da177e4SLinus Torvalds 29531770e34SFlorian Westphal /* If we advertise zero window, disable fast path. */ 2968e165e20SFlorian Westphal if (new_win == 0) { 29731770e34SFlorian Westphal tp->pred_flags = 0; 2988e165e20SFlorian Westphal if (old_win) 2998e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3008e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3018e165e20SFlorian Westphal } else if (old_win == 0) { 3028e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3038e165e20SFlorian Westphal } 3041da177e4SLinus Torvalds 3051da177e4SLinus Torvalds return new_win; 3061da177e4SLinus Torvalds } 3071da177e4SLinus Torvalds 30867edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 309735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 310bdf1ee5dSIlpo Järvinen { 31130e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 31230e502a3SDaniel Borkmann 3134de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 314bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3154de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 31691b5b21cSLawrence Brakmo else if (tcp_ca_needs_ecn(sk) || 31791b5b21cSLawrence Brakmo tcp_bpf_ca_needs_ecn(sk)) 31830e502a3SDaniel Borkmann INET_ECN_xmit(sk); 319bdf1ee5dSIlpo Järvinen } 320bdf1ee5dSIlpo Järvinen 32167edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 322735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 323bdf1ee5dSIlpo Järvinen { 324bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 32591b5b21cSLawrence Brakmo bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); 326f7b3bec6SFlorian Westphal bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || 32791b5b21cSLawrence Brakmo tcp_ca_needs_ecn(sk) || bpf_needs_ecn; 328f7b3bec6SFlorian Westphal 329f7b3bec6SFlorian Westphal if (!use_ecn) { 330f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 331f7b3bec6SFlorian Westphal 332f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 333f7b3bec6SFlorian Westphal use_ecn = true; 334f7b3bec6SFlorian Westphal } 335bdf1ee5dSIlpo Järvinen 336bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 337f7b3bec6SFlorian Westphal 338f7b3bec6SFlorian Westphal if (use_ecn) { 3394de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 340bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 34191b5b21cSLawrence Brakmo if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) 34230e502a3SDaniel Borkmann INET_ECN_xmit(sk); 343bdf1ee5dSIlpo Järvinen } 344bdf1ee5dSIlpo Järvinen } 345bdf1ee5dSIlpo Järvinen 34649213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 34749213555SDaniel Borkmann { 34849213555SDaniel Borkmann if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) 34949213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 35049213555SDaniel Borkmann * SYN ACK is ultimatively being received. 35149213555SDaniel Borkmann */ 35249213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 35349213555SDaniel Borkmann } 35449213555SDaniel Borkmann 355735d3831SFlorian Westphal static void 3566ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 357bdf1ee5dSIlpo Järvinen { 3586ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 359bdf1ee5dSIlpo Järvinen th->ece = 1; 360bdf1ee5dSIlpo Järvinen } 361bdf1ee5dSIlpo Järvinen 36267edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 36367edfef7SAndi Kleen * be sent. 36467edfef7SAndi Kleen */ 365735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 366ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 367bdf1ee5dSIlpo Järvinen { 368bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 369bdf1ee5dSIlpo Järvinen 370bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 371bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 372bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 373bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 374bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 375bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 376bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 377ea1627c2SEric Dumazet th->cwr = 1; 378bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 379bdf1ee5dSIlpo Järvinen } 38030e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 381bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 382bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 383bdf1ee5dSIlpo Järvinen } 384bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 385ea1627c2SEric Dumazet th->ece = 1; 386bdf1ee5dSIlpo Järvinen } 387bdf1ee5dSIlpo Järvinen } 388bdf1ee5dSIlpo Järvinen 389e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 390e870a8efSIlpo Järvinen * auto increment end seqno. 391e870a8efSIlpo Järvinen */ 392e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 393e870a8efSIlpo Järvinen { 3942e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 395e870a8efSIlpo Järvinen 3964de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 397e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 398e870a8efSIlpo Järvinen 399cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 400e870a8efSIlpo Järvinen 401e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 402a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 403e870a8efSIlpo Järvinen seq++; 404e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 405e870a8efSIlpo Järvinen } 406e870a8efSIlpo Järvinen 407a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 40833f5f57eSIlpo Järvinen { 40933f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41033f5f57eSIlpo Järvinen } 41133f5f57eSIlpo Järvinen 41233ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 41333ad798cSAdam Langley #define OPTION_TS (1 << 1) 41433ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 41589e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4162100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 41760e2a778SUrsula Braun #define OPTION_SMC (1 << 9) 418eda7acddSPeter Krystad #define OPTION_MPTCP (1 << 10) 41960e2a778SUrsula Braun 42060e2a778SUrsula Braun static void smc_options_write(__be32 *ptr, u16 *options) 42160e2a778SUrsula Braun { 42260e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 42360e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 42460e2a778SUrsula Braun if (unlikely(OPTION_SMC & *options)) { 42560e2a778SUrsula Braun *ptr++ = htonl((TCPOPT_NOP << 24) | 42660e2a778SUrsula Braun (TCPOPT_NOP << 16) | 42760e2a778SUrsula Braun (TCPOPT_EXP << 8) | 42860e2a778SUrsula Braun (TCPOLEN_EXP_SMC_BASE)); 42960e2a778SUrsula Braun *ptr++ = htonl(TCPOPT_SMC_MAGIC); 43060e2a778SUrsula Braun } 43160e2a778SUrsula Braun } 43260e2a778SUrsula Braun #endif 43360e2a778SUrsula Braun } 43433ad798cSAdam Langley 43533ad798cSAdam Langley struct tcp_out_options { 4362100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4372100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 43833ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 43933ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 440bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 441bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4422100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4432100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 444eda7acddSPeter Krystad struct mptcp_out_options mptcp; 44533ad798cSAdam Langley }; 44633ad798cSAdam Langley 447eda7acddSPeter Krystad static void mptcp_options_write(__be32 *ptr, struct tcp_out_options *opts) 448eda7acddSPeter Krystad { 449eda7acddSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP) 450eda7acddSPeter Krystad if (unlikely(OPTION_MPTCP & opts->options)) 451eda7acddSPeter Krystad mptcp_write_options(ptr, &opts->mptcp); 452eda7acddSPeter Krystad #endif 453eda7acddSPeter Krystad } 454eda7acddSPeter Krystad 45567edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 45667edfef7SAndi Kleen * 45767edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 458fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 459fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4608e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 461fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 462fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 463fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 464fd6149d3SIlpo Järvinen * 465fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 466fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 467fd6149d3SIlpo Järvinen */ 46833ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 469bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 470bd0388aeSWilliam Allen Simpson { 4712100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 472bd0388aeSWilliam Allen Simpson 473bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4741a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4751a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 476bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 477bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 47833ad798cSAdam Langley ptr += 4; 47933ad798cSAdam Langley } 48033ad798cSAdam Langley 481fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 482fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 483fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 484fd6149d3SIlpo Järvinen opts->mss); 485fd6149d3SIlpo Järvinen } 486fd6149d3SIlpo Järvinen 487bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 488bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 48933ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 49033ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 49133ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 49233ad798cSAdam Langley TCPOLEN_TIMESTAMP); 493bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 49433ad798cSAdam Langley } else { 495496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 49640efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 49740efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 49840efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 49940efc6faSStephen Hemminger } 50033ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 50133ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 50233ad798cSAdam Langley } 50333ad798cSAdam Langley 504bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 50533ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 50633ad798cSAdam Langley (TCPOPT_NOP << 16) | 50733ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 50833ad798cSAdam Langley TCPOLEN_SACK_PERM); 50933ad798cSAdam Langley } 51033ad798cSAdam Langley 511bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 51233ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 51333ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 51433ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 51533ad798cSAdam Langley opts->ws); 51633ad798cSAdam Langley } 51733ad798cSAdam Langley 51833ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 51933ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 52033ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 52140efc6faSStephen Hemminger int this_sack; 52240efc6faSStephen Hemminger 52340efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 52440efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 52540efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 52633ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 52740efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5282de979bdSStephen Hemminger 52933ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 53033ad798cSAdam Langley ++this_sack) { 53140efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 53240efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 53340efc6faSStephen Hemminger } 5342de979bdSStephen Hemminger 53540efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 53640efc6faSStephen Hemminger } 5372100c8d2SYuchung Cheng 5382100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5392100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 5407f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 5417f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 5422100c8d2SYuchung Cheng 5437f9b838bSDaniel Lee if (foc->exp) { 5447f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 5457f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 5462100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 5477f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 5487f9b838bSDaniel Lee } else { 5497f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 5507f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 5517f9b838bSDaniel Lee *p++ = len; 5522100c8d2SYuchung Cheng } 5537f9b838bSDaniel Lee 5547f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 5557f9b838bSDaniel Lee if ((len & 3) == 2) { 5567f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 5577f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 5587f9b838bSDaniel Lee } 5597f9b838bSDaniel Lee ptr += (len + 3) >> 2; 5602100c8d2SYuchung Cheng } 56160e2a778SUrsula Braun 56260e2a778SUrsula Braun smc_options_write(ptr, &options); 563eda7acddSPeter Krystad 564eda7acddSPeter Krystad mptcp_options_write(ptr, opts); 56560e2a778SUrsula Braun } 56660e2a778SUrsula Braun 56760e2a778SUrsula Braun static void smc_set_option(const struct tcp_sock *tp, 56860e2a778SUrsula Braun struct tcp_out_options *opts, 56960e2a778SUrsula Braun unsigned int *remaining) 57060e2a778SUrsula Braun { 57160e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 57260e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 57360e2a778SUrsula Braun if (tp->syn_smc) { 57460e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 57560e2a778SUrsula Braun opts->options |= OPTION_SMC; 57660e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 57760e2a778SUrsula Braun } 57860e2a778SUrsula Braun } 57960e2a778SUrsula Braun } 58060e2a778SUrsula Braun #endif 58160e2a778SUrsula Braun } 58260e2a778SUrsula Braun 58360e2a778SUrsula Braun static void smc_set_option_cond(const struct tcp_sock *tp, 58460e2a778SUrsula Braun const struct inet_request_sock *ireq, 58560e2a778SUrsula Braun struct tcp_out_options *opts, 58660e2a778SUrsula Braun unsigned int *remaining) 58760e2a778SUrsula Braun { 58860e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 58960e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 59060e2a778SUrsula Braun if (tp->syn_smc && ireq->smc_ok) { 59160e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 59260e2a778SUrsula Braun opts->options |= OPTION_SMC; 59360e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 59460e2a778SUrsula Braun } 59560e2a778SUrsula Braun } 59660e2a778SUrsula Braun } 59760e2a778SUrsula Braun #endif 59840efc6faSStephen Hemminger } 59940efc6faSStephen Hemminger 600cec37a6eSPeter Krystad static void mptcp_set_option_cond(const struct request_sock *req, 601cec37a6eSPeter Krystad struct tcp_out_options *opts, 602cec37a6eSPeter Krystad unsigned int *remaining) 603cec37a6eSPeter Krystad { 604cec37a6eSPeter Krystad if (rsk_is_mptcp(req)) { 605cec37a6eSPeter Krystad unsigned int size; 606cec37a6eSPeter Krystad 607cec37a6eSPeter Krystad if (mptcp_synack_options(req, &size, &opts->mptcp)) { 608cec37a6eSPeter Krystad if (*remaining >= size) { 609cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 610cec37a6eSPeter Krystad *remaining -= size; 611cec37a6eSPeter Krystad } 612cec37a6eSPeter Krystad } 613cec37a6eSPeter Krystad } 614cec37a6eSPeter Krystad } 615cec37a6eSPeter Krystad 61667edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 61767edfef7SAndi Kleen * network wire format yet. 61867edfef7SAndi Kleen */ 61995c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 62033ad798cSAdam Langley struct tcp_out_options *opts, 621cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 622cf533ea5SEric Dumazet { 62333ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 62495c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 625783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 62633ad798cSAdam Langley 6278c2320e8SEric Dumazet *md5 = NULL; 628cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 629921f9a0fSEric Dumazet if (static_branch_unlikely(&tcp_md5_needed) && 6306015c71eSEric Dumazet rcu_access_pointer(tp->md5sig_info)) { 63133ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 63233ad798cSAdam Langley if (*md5) { 63333ad798cSAdam Langley opts->options |= OPTION_MD5; 634bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 635cfb6eeb4SYOSHIFUJI Hideaki } 6368c2320e8SEric Dumazet } 637cfb6eeb4SYOSHIFUJI Hideaki #endif 63833ad798cSAdam Langley 63933ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 64033ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 64133ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 64233ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 64333ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 64433ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 64533ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 64633ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 64733ad798cSAdam Langley * going out. */ 64833ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 649bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 65033ad798cSAdam Langley 6515d2ed052SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) { 65233ad798cSAdam Langley opts->options |= OPTION_TS; 6537faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 65433ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 655bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 65633ad798cSAdam Langley } 6579bb37ef0SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) { 65833ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 65989e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 660bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 66133ad798cSAdam Langley } 662f9301034SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) { 66333ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 664b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 665bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 66633ad798cSAdam Langley } 66733ad798cSAdam Langley 668783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 6692646c831SDaniel Lee u32 need = fastopen->cookie.len; 6702646c831SDaniel Lee 6712646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 6722646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 673783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 674783237e8SYuchung Cheng if (remaining >= need) { 675783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 676783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 677783237e8SYuchung Cheng remaining -= need; 678783237e8SYuchung Cheng tp->syn_fastopen = 1; 6792646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 680783237e8SYuchung Cheng } 681783237e8SYuchung Cheng } 682bd0388aeSWilliam Allen Simpson 68360e2a778SUrsula Braun smc_set_option(tp, opts, &remaining); 68460e2a778SUrsula Braun 685cec37a6eSPeter Krystad if (sk_is_mptcp(sk)) { 686cec37a6eSPeter Krystad unsigned int size; 687cec37a6eSPeter Krystad 688cc7972eaSChristoph Paasch if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) { 689cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 690cec37a6eSPeter Krystad remaining -= size; 691cec37a6eSPeter Krystad } 692cec37a6eSPeter Krystad } 693cec37a6eSPeter Krystad 694bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 69533ad798cSAdam Langley } 69633ad798cSAdam Langley 69767edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 69860e2a778SUrsula Braun static unsigned int tcp_synack_options(const struct sock *sk, 69960e2a778SUrsula Braun struct request_sock *req, 70095c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 70133ad798cSAdam Langley struct tcp_out_options *opts, 70280f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 703e114e1e8SEric Dumazet struct tcp_fastopen_cookie *foc, 704e114e1e8SEric Dumazet enum tcp_synack_type synack_type) 7054957faadSWilliam Allen Simpson { 70633ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 70795c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 70833ad798cSAdam Langley 70933ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 71080f03e27SEric Dumazet if (md5) { 71133ad798cSAdam Langley opts->options |= OPTION_MD5; 7124957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 7134957faadSWilliam Allen Simpson 7144957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 7154957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 7164957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 7174957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 7184957faadSWilliam Allen Simpson */ 719e114e1e8SEric Dumazet if (synack_type != TCP_SYNACK_COOKIE) 720de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 72133ad798cSAdam Langley } 72233ad798cSAdam Langley #endif 72333ad798cSAdam Langley 7244957faadSWilliam Allen Simpson /* We always send an MSS option. */ 72533ad798cSAdam Langley opts->mss = mss; 7264957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 72733ad798cSAdam Langley 72833ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 72933ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 73089e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 7314957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 73233ad798cSAdam Langley } 733de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 73433ad798cSAdam Langley opts->options |= OPTION_TS; 73595a22caeSFlorian Westphal opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; 73633ad798cSAdam Langley opts->tsecr = req->ts_recent; 7374957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 73833ad798cSAdam Langley } 73933ad798cSAdam Langley if (likely(ireq->sack_ok)) { 74033ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 741de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 7424957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 74333ad798cSAdam Langley } 7447f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 7457f9b838bSDaniel Lee u32 need = foc->len; 7467f9b838bSDaniel Lee 7477f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 7487f9b838bSDaniel Lee TCPOLEN_FASTOPEN_BASE; 7498336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 7508336886fSJerry Chu if (remaining >= need) { 7518336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 7528336886fSJerry Chu opts->fastopen_cookie = foc; 7538336886fSJerry Chu remaining -= need; 7548336886fSJerry Chu } 7558336886fSJerry Chu } 7564957faadSWilliam Allen Simpson 757cec37a6eSPeter Krystad mptcp_set_option_cond(req, opts, &remaining); 758cec37a6eSPeter Krystad 75960e2a778SUrsula Braun smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); 76060e2a778SUrsula Braun 7614957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 76233ad798cSAdam Langley } 76333ad798cSAdam Langley 76467edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 76567edfef7SAndi Kleen * final wire format yet. 76667edfef7SAndi Kleen */ 76795c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 76833ad798cSAdam Langley struct tcp_out_options *opts, 769cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 770cf533ea5SEric Dumazet { 77133ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 77295c96174SEric Dumazet unsigned int size = 0; 773cabeccbdSIlpo Järvinen unsigned int eff_sacks; 77433ad798cSAdam Langley 7755843ef42SAndi Kleen opts->options = 0; 7765843ef42SAndi Kleen 7778c2320e8SEric Dumazet *md5 = NULL; 77833ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 779921f9a0fSEric Dumazet if (static_branch_unlikely(&tcp_md5_needed) && 7806015c71eSEric Dumazet rcu_access_pointer(tp->md5sig_info)) { 78133ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 7828c2320e8SEric Dumazet if (*md5) { 78333ad798cSAdam Langley opts->options |= OPTION_MD5; 78433ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 78533ad798cSAdam Langley } 7868c2320e8SEric Dumazet } 78733ad798cSAdam Langley #endif 78833ad798cSAdam Langley 78933ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 79033ad798cSAdam Langley opts->options |= OPTION_TS; 7917faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 79233ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 79333ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 79433ad798cSAdam Langley } 79533ad798cSAdam Langley 796cec37a6eSPeter Krystad /* MPTCP options have precedence over SACK for the limited TCP 797cec37a6eSPeter Krystad * option space because a MPTCP connection would be forced to 798cec37a6eSPeter Krystad * fall back to regular TCP if a required multipath option is 799cec37a6eSPeter Krystad * missing. SACK still gets a chance to use whatever space is 800cec37a6eSPeter Krystad * left. 801cec37a6eSPeter Krystad */ 802cec37a6eSPeter Krystad if (sk_is_mptcp(sk)) { 803cec37a6eSPeter Krystad unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 804cec37a6eSPeter Krystad unsigned int opt_size = 0; 805cec37a6eSPeter Krystad 806cec37a6eSPeter Krystad if (mptcp_established_options(sk, skb, &opt_size, remaining, 807cec37a6eSPeter Krystad &opts->mptcp)) { 808cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 809cec37a6eSPeter Krystad size += opt_size; 810cec37a6eSPeter Krystad } 811cec37a6eSPeter Krystad } 812cec37a6eSPeter Krystad 813cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 814cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 81595c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 8169cfcca23SMat Martineau if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED + 8179cfcca23SMat Martineau TCPOLEN_SACK_PERBLOCK)) 8189cfcca23SMat Martineau return size; 8199cfcca23SMat Martineau 82033ad798cSAdam Langley opts->num_sack_blocks = 82195c96174SEric Dumazet min_t(unsigned int, eff_sacks, 82233ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 82333ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 8249cfcca23SMat Martineau 82533ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 82633ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 82733ad798cSAdam Langley } 82833ad798cSAdam Langley 82933ad798cSAdam Langley return size; 83040efc6faSStephen Hemminger } 8311da177e4SLinus Torvalds 83246d3ceabSEric Dumazet 83346d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 83446d3ceabSEric Dumazet * 83546d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 83646d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 83746d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 83846d3ceabSEric Dumazet * 83946d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 84046d3ceabSEric Dumazet * needs to be reallocated in a driver. 8418e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 84246d3ceabSEric Dumazet * 84346d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 84446d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 84546d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 84646d3ceabSEric Dumazet */ 84746d3ceabSEric Dumazet struct tsq_tasklet { 84846d3ceabSEric Dumazet struct tasklet_struct tasklet; 84946d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 85046d3ceabSEric Dumazet }; 85146d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 85246d3ceabSEric Dumazet 85373a6bab5SEric Dumazet static void tcp_tsq_write(struct sock *sk) 8546f458dfbSEric Dumazet { 8556f458dfbSEric Dumazet if ((1 << sk->sk_state) & 8566f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 857f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 858f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 859f9616c35SEric Dumazet 860f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 8613a91d29fSKoichiro Den tp->snd_cwnd > tcp_packets_in_flight(tp)) { 8623a91d29fSKoichiro Den tcp_mstamp_refresh(tp); 863f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 8643a91d29fSKoichiro Den } 865f9616c35SEric Dumazet 866f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 867bf06200eSJohn Ogness 0, GFP_ATOMIC); 8686f458dfbSEric Dumazet } 869f9616c35SEric Dumazet } 87073a6bab5SEric Dumazet 87173a6bab5SEric Dumazet static void tcp_tsq_handler(struct sock *sk) 87273a6bab5SEric Dumazet { 87373a6bab5SEric Dumazet bh_lock_sock(sk); 87473a6bab5SEric Dumazet if (!sock_owned_by_user(sk)) 87573a6bab5SEric Dumazet tcp_tsq_write(sk); 87673a6bab5SEric Dumazet else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) 87773a6bab5SEric Dumazet sock_hold(sk); 87873a6bab5SEric Dumazet bh_unlock_sock(sk); 87973a6bab5SEric Dumazet } 88046d3ceabSEric Dumazet /* 8818e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 88246d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 8838e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 88446d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 88546d3ceabSEric Dumazet */ 88646d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 88746d3ceabSEric Dumazet { 88846d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 88946d3ceabSEric Dumazet LIST_HEAD(list); 89046d3ceabSEric Dumazet unsigned long flags; 89146d3ceabSEric Dumazet struct list_head *q, *n; 89246d3ceabSEric Dumazet struct tcp_sock *tp; 89346d3ceabSEric Dumazet struct sock *sk; 89446d3ceabSEric Dumazet 89546d3ceabSEric Dumazet local_irq_save(flags); 89646d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 89746d3ceabSEric Dumazet local_irq_restore(flags); 89846d3ceabSEric Dumazet 89946d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 90046d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 90146d3ceabSEric Dumazet list_del(&tp->tsq_node); 90246d3ceabSEric Dumazet 90346d3ceabSEric Dumazet sk = (struct sock *)tp; 9040a9648f1SEric Dumazet smp_mb__before_atomic(); 9057aa5470cSEric Dumazet clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); 9067aa5470cSEric Dumazet 9076f458dfbSEric Dumazet tcp_tsq_handler(sk); 90846d3ceabSEric Dumazet sk_free(sk); 90946d3ceabSEric Dumazet } 91046d3ceabSEric Dumazet } 91146d3ceabSEric Dumazet 91240fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 91340fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 91440fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 91540fc3423SEric Dumazet TCPF_MTU_REDUCED_DEFERRED) 91646d3ceabSEric Dumazet /** 91746d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 91846d3ceabSEric Dumazet * @sk: socket 91946d3ceabSEric Dumazet * 92046d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 92146d3ceabSEric Dumazet * actions before socket release. 92246d3ceabSEric Dumazet */ 92346d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 92446d3ceabSEric Dumazet { 9256f458dfbSEric Dumazet unsigned long flags, nflags; 92646d3ceabSEric Dumazet 9276f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 9286f458dfbSEric Dumazet do { 9297aa5470cSEric Dumazet flags = sk->sk_tsq_flags; 9306f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 9316f458dfbSEric Dumazet return; 9326f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 9337aa5470cSEric Dumazet } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); 9346f458dfbSEric Dumazet 93573a6bab5SEric Dumazet if (flags & TCPF_TSQ_DEFERRED) { 93673a6bab5SEric Dumazet tcp_tsq_write(sk); 93773a6bab5SEric Dumazet __sock_put(sk); 93873a6bab5SEric Dumazet } 939c3f9b018SEric Dumazet /* Here begins the tricky part : 940c3f9b018SEric Dumazet * We are called from release_sock() with : 941c3f9b018SEric Dumazet * 1) BH disabled 942c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 943c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 944c3f9b018SEric Dumazet * 945c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 946c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 947c3f9b018SEric Dumazet */ 948c3f9b018SEric Dumazet sock_release_ownership(sk); 949c3f9b018SEric Dumazet 95040fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 9516f458dfbSEric Dumazet tcp_write_timer_handler(sk); 952144d56e9SEric Dumazet __sock_put(sk); 953144d56e9SEric Dumazet } 95440fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 9556f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 956144d56e9SEric Dumazet __sock_put(sk); 957144d56e9SEric Dumazet } 95840fc3423SEric Dumazet if (flags & TCPF_MTU_REDUCED_DEFERRED) { 9594fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 960144d56e9SEric Dumazet __sock_put(sk); 961144d56e9SEric Dumazet } 96246d3ceabSEric Dumazet } 96346d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 96446d3ceabSEric Dumazet 96546d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 96646d3ceabSEric Dumazet { 96746d3ceabSEric Dumazet int i; 96846d3ceabSEric Dumazet 96946d3ceabSEric Dumazet for_each_possible_cpu(i) { 97046d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 97146d3ceabSEric Dumazet 97246d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 97346d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 97446d3ceabSEric Dumazet tcp_tasklet_func, 97546d3ceabSEric Dumazet (unsigned long)tsq); 97646d3ceabSEric Dumazet } 97746d3ceabSEric Dumazet } 97846d3ceabSEric Dumazet 97946d3ceabSEric Dumazet /* 98046d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 9818e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 98246d3ceabSEric Dumazet * hold qdisc lock. 98346d3ceabSEric Dumazet */ 984d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 98546d3ceabSEric Dumazet { 98646d3ceabSEric Dumazet struct sock *sk = skb->sk; 98746d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 988408f0a6cSEric Dumazet unsigned long flags, nval, oval; 9899b462d02SEric Dumazet 9909b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 9919b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 9929b462d02SEric Dumazet */ 99314afee4bSReshetova, Elena WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); 9949b462d02SEric Dumazet 9959b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 9969b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 9979b462d02SEric Dumazet * This gives : 9989b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 9999b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 10009b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 10019b462d02SEric Dumazet */ 100214afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 10039b462d02SEric Dumazet goto out; 100446d3ceabSEric Dumazet 10057aa5470cSEric Dumazet for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { 100646d3ceabSEric Dumazet struct tsq_tasklet *tsq; 1007a9b204d1SEric Dumazet bool empty; 100846d3ceabSEric Dumazet 1009408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 1010408f0a6cSEric Dumazet goto out; 1011408f0a6cSEric Dumazet 101273a6bab5SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; 10137aa5470cSEric Dumazet nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); 1014408f0a6cSEric Dumazet if (nval != oval) 1015408f0a6cSEric Dumazet continue; 1016408f0a6cSEric Dumazet 101746d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 101846d3ceabSEric Dumazet local_irq_save(flags); 1019903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 1020a9b204d1SEric Dumazet empty = list_empty(&tsq->head); 102146d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 1022a9b204d1SEric Dumazet if (empty) 102346d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 102446d3ceabSEric Dumazet local_irq_restore(flags); 10259b462d02SEric Dumazet return; 102646d3ceabSEric Dumazet } 10279b462d02SEric Dumazet out: 10289b462d02SEric Dumazet sk_free(sk); 102946d3ceabSEric Dumazet } 103046d3ceabSEric Dumazet 103173a6bab5SEric Dumazet /* Note: Called under soft irq. 103273a6bab5SEric Dumazet * We can call TCP stack right away, unless socket is owned by user. 1033218af599SEric Dumazet */ 1034218af599SEric Dumazet enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 1035218af599SEric Dumazet { 1036218af599SEric Dumazet struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); 1037218af599SEric Dumazet struct sock *sk = (struct sock *)tp; 1038218af599SEric Dumazet 103973a6bab5SEric Dumazet tcp_tsq_handler(sk); 104073a6bab5SEric Dumazet sock_put(sk); 1041218af599SEric Dumazet 1042218af599SEric Dumazet return HRTIMER_NORESTART; 1043218af599SEric Dumazet } 1044218af599SEric Dumazet 1045a7a25630SEric Dumazet static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb, 1046a7a25630SEric Dumazet u64 prior_wstamp) 1047e2080072SEric Dumazet { 1048ab408b6dSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1049ab408b6dSEric Dumazet 1050ab408b6dSEric Dumazet if (sk->sk_pacing_status != SK_PACING_NONE) { 105176a9ebe8SEric Dumazet unsigned long rate = sk->sk_pacing_rate; 1052ab408b6dSEric Dumazet 1053ab408b6dSEric Dumazet /* Original sch_fq does not pace first 10 MSS 1054ab408b6dSEric Dumazet * Note that tp->data_segs_out overflows after 2^32 packets, 1055ab408b6dSEric Dumazet * this is a minor annoyance. 1056ab408b6dSEric Dumazet */ 105776a9ebe8SEric Dumazet if (rate != ~0UL && rate && tp->data_segs_out >= 10) { 1058a7a25630SEric Dumazet u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate); 1059a7a25630SEric Dumazet u64 credit = tp->tcp_wstamp_ns - prior_wstamp; 1060a7a25630SEric Dumazet 1061a7a25630SEric Dumazet /* take into account OS jitter */ 1062a7a25630SEric Dumazet len_ns -= min_t(u64, len_ns / 2, credit); 1063a7a25630SEric Dumazet tp->tcp_wstamp_ns += len_ns; 1064ab408b6dSEric Dumazet } 1065ab408b6dSEric Dumazet } 1066e2080072SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 1067e2080072SEric Dumazet } 1068e2080072SEric Dumazet 10691da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 10701da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 10711da177e4SLinus Torvalds * transmission and possible later retransmissions. 10721da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 10731da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 10741da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 10751da177e4SLinus Torvalds * device. 10761da177e4SLinus Torvalds * 10771da177e4SLinus Torvalds * We are working here with either a clone of the original 10781da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 10791da177e4SLinus Torvalds */ 10802987babbSYuchung Cheng static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, 10812987babbSYuchung Cheng int clone_it, gfp_t gfp_mask, u32 rcv_nxt) 10821da177e4SLinus Torvalds { 10836687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1084dfb4b9dcSDavid S. Miller struct inet_sock *inet; 1085dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 1086dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 108733ad798cSAdam Langley struct tcp_out_options opts; 108895c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 10898c72c65bSEric Dumazet struct sk_buff *oskb = NULL; 1090cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 10911da177e4SLinus Torvalds struct tcphdr *th; 1092a7a25630SEric Dumazet u64 prior_wstamp; 10931da177e4SLinus Torvalds int err; 10941da177e4SLinus Torvalds 1095dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 10966f094b9eSLawrence Brakmo tp = tcp_sk(sk); 10977f12422cSYuchung Cheng prior_wstamp = tp->tcp_wstamp_ns; 10987f12422cSYuchung Cheng tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); 10997f12422cSYuchung Cheng skb->skb_mstamp_ns = tp->tcp_wstamp_ns; 1100ccdbb6e9SEric Dumazet if (clone_it) { 11016f094b9eSLawrence Brakmo TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq 11026f094b9eSLawrence Brakmo - tp->snd_una; 11038c72c65bSEric Dumazet oskb = skb; 1104e2080072SEric Dumazet 1105e2080072SEric Dumazet tcp_skb_tsorted_save(oskb) { 1106e2080072SEric Dumazet if (unlikely(skb_cloned(oskb))) 1107e2080072SEric Dumazet skb = pskb_copy(oskb, gfp_mask); 1108dfb4b9dcSDavid S. Miller else 1109e2080072SEric Dumazet skb = skb_clone(oskb, gfp_mask); 1110e2080072SEric Dumazet } tcp_skb_tsorted_restore(oskb); 1111e2080072SEric Dumazet 1112dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 1113dfb4b9dcSDavid S. Miller return -ENOBUFS; 1114b738a185SEric Dumazet /* retransmit skbs might have a non zero value in skb->dev 1115b738a185SEric Dumazet * because skb->dev is aliased with skb->rbnode.rb_left 1116b738a185SEric Dumazet */ 1117b738a185SEric Dumazet skb->dev = NULL; 1118dfb4b9dcSDavid S. Miller } 11195f6188a8SEric Dumazet 1120dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 1121dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 112233ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 11231da177e4SLinus Torvalds 1124051ba674SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 112533ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 1126051ba674SEric Dumazet } else { 112733ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 112833ad798cSAdam Langley &md5); 1129051ba674SEric Dumazet /* Force a PSH flag on all (GSO) packets to expedite GRO flush 1130051ba674SEric Dumazet * at receiver : This slightly improve GRO performance. 1131051ba674SEric Dumazet * Note that we do not force the PSH flag for non GSO packets, 1132051ba674SEric Dumazet * because they might be sent under high congestion events, 1133051ba674SEric Dumazet * and in this case it is better to delay the delivery of 1-MSS 1134051ba674SEric Dumazet * packets and thus the corresponding ACK packet that would 1135051ba674SEric Dumazet * release the following packet. 1136051ba674SEric Dumazet */ 1137051ba674SEric Dumazet if (tcp_skb_pcount(skb) > 1) 1138051ba674SEric Dumazet tcb->tcp_flags |= TCPHDR_PSH; 1139051ba674SEric Dumazet } 114033ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 11411da177e4SLinus Torvalds 1142547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 1143b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 114473a6bab5SEric Dumazet * which holds one reference to sk. 1145b2532eb9SEric Dumazet * 1146b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 1147b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 1148547669d4SEric Dumazet */ 1149b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 11501da177e4SLinus Torvalds 115138ab52e8SEric Dumazet /* If we had to use memory reserve to allocate this skb, 115238ab52e8SEric Dumazet * this might cause drops if packet is looped back : 115338ab52e8SEric Dumazet * Other socket might not have SOCK_MEMALLOC. 115438ab52e8SEric Dumazet * Packets not looped back do not care about pfmemalloc. 115538ab52e8SEric Dumazet */ 115638ab52e8SEric Dumazet skb->pfmemalloc = 0; 115738ab52e8SEric Dumazet 1158aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 1159aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 116046d3ceabSEric Dumazet 116146d3ceabSEric Dumazet skb_orphan(skb); 116246d3ceabSEric Dumazet skb->sk = sk; 11631d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 1164b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 116514afee4bSReshetova, Elena refcount_add(skb->truesize, &sk->sk_wmem_alloc); 11661da177e4SLinus Torvalds 1167c3a2e837SJulian Anastasov skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); 1168c3a2e837SJulian Anastasov 11691da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 1170ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 1171c720c7e8SEric Dumazet th->source = inet->inet_sport; 1172c720c7e8SEric Dumazet th->dest = inet->inet_dport; 11731da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 11742987babbSYuchung Cheng th->ack_seq = htonl(rcv_nxt); 1175df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 11764de075e0SEric Dumazet tcb->tcp_flags); 1177dfb4b9dcSDavid S. Miller 11781da177e4SLinus Torvalds th->check = 0; 11791da177e4SLinus Torvalds th->urg_ptr = 0; 11801da177e4SLinus Torvalds 118133f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 11827691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 11837691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 11841da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 11851da177e4SLinus Torvalds th->urg = 1; 11867691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 11870eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 11887691367dSHerbert Xu th->urg = 1; 11897691367dSHerbert Xu } 11901da177e4SLinus Torvalds } 11911da177e4SLinus Torvalds 1192bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 119351466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 1194ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1195ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1196ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1197ea1627c2SEric Dumazet } else { 1198ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1199ea1627c2SEric Dumazet * is never scaled. 1200ea1627c2SEric Dumazet */ 1201ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1202ea1627c2SEric Dumazet } 1203cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1204cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1205cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1206a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1207bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 120839f8e58eSEric Dumazet md5, sk, skb); 1209cfb6eeb4SYOSHIFUJI Hideaki } 1210cfb6eeb4SYOSHIFUJI Hideaki #endif 1211cfb6eeb4SYOSHIFUJI Hideaki 1212bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 12131da177e4SLinus Torvalds 12144de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 121527cde44aSYuchung Cheng tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt); 12161da177e4SLinus Torvalds 1217a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1218cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1219a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1220ba113c3aSWei Wang tp->bytes_sent += skb->len - tcp_header_size; 1221a44d6eacSMartin KaFai Lau } 12221da177e4SLinus Torvalds 1223bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1224aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1225aa2ea058STom Herbert tcp_skb_pcount(skb)); 12261da177e4SLinus Torvalds 12272efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 1228f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1229cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1230f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1231cd7d8498SEric Dumazet 1232d3edd06eSEric Dumazet /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ 1233971f10ecSEric Dumazet 1234971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1235971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1236971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1237971f10ecSEric Dumazet 1238a842fe14SEric Dumazet tcp_add_tx_delay(skb, tp); 1239a842fe14SEric Dumazet 1240b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 12417faee5c0SEric Dumazet 12428c72c65bSEric Dumazet if (unlikely(err > 0)) { 12435ee2c941SChristoph Paasch tcp_enter_cwr(sk); 12448c72c65bSEric Dumazet err = net_xmit_eval(err); 12458c72c65bSEric Dumazet } 1246fc225799SEric Dumazet if (!err && oskb) { 1247a7a25630SEric Dumazet tcp_update_skb_after_send(sk, oskb, prior_wstamp); 1248fc225799SEric Dumazet tcp_rate_skb_sent(sk, oskb); 1249fc225799SEric Dumazet } 12508c72c65bSEric Dumazet return err; 12511da177e4SLinus Torvalds } 12521da177e4SLinus Torvalds 12532987babbSYuchung Cheng static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 12542987babbSYuchung Cheng gfp_t gfp_mask) 12552987babbSYuchung Cheng { 12562987babbSYuchung Cheng return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, 12572987babbSYuchung Cheng tcp_sk(sk)->rcv_nxt); 12582987babbSYuchung Cheng } 12592987babbSYuchung Cheng 126067edfef7SAndi Kleen /* This routine just queues the buffer for sending. 12611da177e4SLinus Torvalds * 12621da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 12631da177e4SLinus Torvalds * otherwise socket can stall. 12641da177e4SLinus Torvalds */ 12651da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 12661da177e4SLinus Torvalds { 12671da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12681da177e4SLinus Torvalds 12691da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 12700f317464SEric Dumazet WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq); 1271f4a775d1SEric Dumazet __skb_header_release(skb); 1272fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 1273ab4e846aSEric Dumazet sk_wmem_queued_add(sk, skb->truesize); 12743ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 12751da177e4SLinus Torvalds } 12761da177e4SLinus Torvalds 127767edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 12785bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1279f6302d1dSDavid S. Miller { 12804a64fd6cSEric Dumazet if (skb->len <= mss_now) { 1281f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1282f6302d1dSDavid S. Miller * non-TSO case. 1283f6302d1dSDavid S. Miller */ 1284cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1285f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1286f6302d1dSDavid S. Miller } else { 1287cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1288f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 12891da177e4SLinus Torvalds } 12901da177e4SLinus Torvalds } 12911da177e4SLinus Torvalds 1292797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1293797108d1SIlpo Järvinen * tweaks to fix counters 1294797108d1SIlpo Järvinen */ 1295cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1296797108d1SIlpo Järvinen { 1297797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1298797108d1SIlpo Järvinen 1299797108d1SIlpo Järvinen tp->packets_out -= decr; 1300797108d1SIlpo Järvinen 1301797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1302797108d1SIlpo Järvinen tp->sacked_out -= decr; 1303797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1304797108d1SIlpo Järvinen tp->retrans_out -= decr; 1305797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1306797108d1SIlpo Järvinen tp->lost_out -= decr; 1307797108d1SIlpo Järvinen 1308797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1309797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1310797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1311797108d1SIlpo Järvinen 1312797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1313797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 1314713bafeaSYuchung Cheng (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) 1315797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1316797108d1SIlpo Järvinen 1317797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1318797108d1SIlpo Järvinen } 1319797108d1SIlpo Järvinen 13200a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 13210a2cf20cSSoheil Hassas Yeganeh { 13220a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 13230a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 13240a2cf20cSSoheil Hassas Yeganeh } 13250a2cf20cSSoheil Hassas Yeganeh 1326490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1327490cc7d0SWillem de Bruijn { 1328490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1329490cc7d0SWillem de Bruijn 13300a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1331490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1332490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1333490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1334490cc7d0SWillem de Bruijn 1335490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1336490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1337490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1338b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1339b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1340490cc7d0SWillem de Bruijn } 1341490cc7d0SWillem de Bruijn } 1342490cc7d0SWillem de Bruijn 1343a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1344a166140eSMartin KaFai Lau { 1345a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1346a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1347a166140eSMartin KaFai Lau } 1348a166140eSMartin KaFai Lau 134975c119afSEric Dumazet /* Insert buff after skb on the write or rtx queue of sk. */ 135075c119afSEric Dumazet static void tcp_insert_write_queue_after(struct sk_buff *skb, 135175c119afSEric Dumazet struct sk_buff *buff, 135275c119afSEric Dumazet struct sock *sk, 135375c119afSEric Dumazet enum tcp_queue tcp_queue) 135475c119afSEric Dumazet { 135575c119afSEric Dumazet if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) 135675c119afSEric Dumazet __skb_queue_after(&sk->sk_write_queue, skb, buff); 135775c119afSEric Dumazet else 135875c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 135975c119afSEric Dumazet } 136075c119afSEric Dumazet 13611da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 13621da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 13631da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 13641da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 13651da177e4SLinus Torvalds */ 136675c119afSEric Dumazet int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 136775c119afSEric Dumazet struct sk_buff *skb, u32 len, 13686cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 13691da177e4SLinus Torvalds { 13701da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 13711da177e4SLinus Torvalds struct sk_buff *buff; 13726475be16SDavid S. Miller int nsize, old_factor; 1373b617158dSEric Dumazet long limit; 1374b60b49eaSHerbert Xu int nlen; 13759ce01461SIlpo Järvinen u8 flags; 13761da177e4SLinus Torvalds 13772fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 13782fceec13SIlpo Järvinen return -EINVAL; 13796a438bbeSStephen Hemminger 13801da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 13811da177e4SLinus Torvalds if (nsize < 0) 13821da177e4SLinus Torvalds nsize = 0; 13831da177e4SLinus Torvalds 1384b617158dSEric Dumazet /* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb. 1385b617158dSEric Dumazet * We need some allowance to not penalize applications setting small 1386b617158dSEric Dumazet * SO_SNDBUF values. 1387b617158dSEric Dumazet * Also allow first and last skb in retransmit queue to be split. 1388b617158dSEric Dumazet */ 1389b617158dSEric Dumazet limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_MAX_SIZE); 1390b617158dSEric Dumazet if (unlikely((sk->sk_wmem_queued >> 1) > limit && 1391b617158dSEric Dumazet tcp_queue != TCP_FRAG_IN_WRITE_QUEUE && 1392b617158dSEric Dumazet skb != tcp_rtx_queue_head(sk) && 1393b617158dSEric Dumazet skb != tcp_rtx_queue_tail(sk))) { 1394f070ef2aSEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); 1395f070ef2aSEric Dumazet return -ENOMEM; 1396f070ef2aSEric Dumazet } 1397f070ef2aSEric Dumazet 13986cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 13991da177e4SLinus Torvalds return -ENOMEM; 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 1402eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, nsize, gfp, true); 140351456b29SIan Morris if (!buff) 14041da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 140541477662SJakub Kicinski skb_copy_decrypted(buff, skb); 1406ef5cb973SHerbert Xu 1407ab4e846aSEric Dumazet sk_wmem_queued_add(sk, buff->truesize); 14083ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1409b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1410b60b49eaSHerbert Xu buff->truesize += nlen; 1411b60b49eaSHerbert Xu skb->truesize -= nlen; 14121da177e4SLinus Torvalds 14131da177e4SLinus Torvalds /* Correct the sequence numbers. */ 14141da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 14151da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 14161da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 14171da177e4SLinus Torvalds 14181da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 14194de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 14204de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 14214de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1422e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1423a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds skb_split(skb, buff, len); 14261da177e4SLinus Torvalds 142798be9b12SEric Dumazet buff->ip_summed = CHECKSUM_PARTIAL; 14281da177e4SLinus Torvalds 1429a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1430490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 14311da177e4SLinus Torvalds 14326475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 14336475be16SDavid S. Miller 14341da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 14355bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 14365bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 14371da177e4SLinus Torvalds 1438b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1439b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1440b9f64820SYuchung Cheng 14416475be16SDavid S. Miller /* If this packet has been sent out already, we must 14426475be16SDavid S. Miller * adjust the various packet counters. 14436475be16SDavid S. Miller */ 1444cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 14456475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 14466475be16SDavid S. Miller tcp_skb_pcount(buff); 14471da177e4SLinus Torvalds 1448797108d1SIlpo Järvinen if (diff) 1449797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 14501da177e4SLinus Torvalds } 14511da177e4SLinus Torvalds 14521da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1453f4a775d1SEric Dumazet __skb_header_release(buff); 145475c119afSEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); 1455f67971e6SEric Dumazet if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) 1456e2080072SEric Dumazet list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds return 0; 14591da177e4SLinus Torvalds } 14601da177e4SLinus Torvalds 1461f4d01666SEric Dumazet /* This is similar to __pskb_pull_tail(). The difference is that pulled 1462f4d01666SEric Dumazet * data is not copied, but immediately discarded. 14631da177e4SLinus Torvalds */ 14647162fb24SEric Dumazet static int __pskb_trim_head(struct sk_buff *skb, int len) 14651da177e4SLinus Torvalds { 14667b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 14671da177e4SLinus Torvalds int i, k, eat; 14681da177e4SLinus Torvalds 14694fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 14704fa48bf3SEric Dumazet if (eat) { 14714fa48bf3SEric Dumazet __skb_pull(skb, eat); 14724fa48bf3SEric Dumazet len -= eat; 14734fa48bf3SEric Dumazet if (!len) 14747162fb24SEric Dumazet return 0; 14754fa48bf3SEric Dumazet } 14761da177e4SLinus Torvalds eat = len; 14771da177e4SLinus Torvalds k = 0; 14787b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 14797b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 14807b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 14819e903e08SEric Dumazet 14829e903e08SEric Dumazet if (size <= eat) { 1483aff65da0SIan Campbell skb_frag_unref(skb, i); 14849e903e08SEric Dumazet eat -= size; 14851da177e4SLinus Torvalds } else { 14867b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 14871da177e4SLinus Torvalds if (eat) { 1488b54c9d5bSJonathan Lemon skb_frag_off_add(&shinfo->frags[k], eat); 14897b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 14901da177e4SLinus Torvalds eat = 0; 14911da177e4SLinus Torvalds } 14921da177e4SLinus Torvalds k++; 14931da177e4SLinus Torvalds } 14941da177e4SLinus Torvalds } 14957b7fc97aSEric Dumazet shinfo->nr_frags = k; 14961da177e4SLinus Torvalds 14971da177e4SLinus Torvalds skb->data_len -= len; 14981da177e4SLinus Torvalds skb->len = skb->data_len; 14997162fb24SEric Dumazet return len; 15001da177e4SLinus Torvalds } 15011da177e4SLinus Torvalds 150267edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 15031da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 15041da177e4SLinus Torvalds { 15057162fb24SEric Dumazet u32 delta_truesize; 15067162fb24SEric Dumazet 150714bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 15081da177e4SLinus Torvalds return -ENOMEM; 15091da177e4SLinus Torvalds 15107162fb24SEric Dumazet delta_truesize = __pskb_trim_head(skb, len); 15111da177e4SLinus Torvalds 15121da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 151384fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 15141da177e4SLinus Torvalds 15157162fb24SEric Dumazet if (delta_truesize) { 15167162fb24SEric Dumazet skb->truesize -= delta_truesize; 1517ab4e846aSEric Dumazet sk_wmem_queued_add(sk, -delta_truesize); 15187162fb24SEric Dumazet sk_mem_uncharge(sk, delta_truesize); 15191da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 15207162fb24SEric Dumazet } 15211da177e4SLinus Torvalds 15225b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 15231da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 15245bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 15251da177e4SLinus Torvalds 15261da177e4SLinus Torvalds return 0; 15271da177e4SLinus Torvalds } 15281da177e4SLinus Torvalds 15291b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 15301b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 15315d424d5aSJohn Heffner { 1532cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1533cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 15345d424d5aSJohn Heffner int mss_now; 15355d424d5aSJohn Heffner 15365d424d5aSJohn Heffner /* Calculate base mss without TCP options: 15375d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 15385d424d5aSJohn Heffner */ 15395d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 15405d424d5aSJohn Heffner 154167469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 154267469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 154367469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 154467469601SEric Dumazet 154567469601SEric Dumazet if (dst && dst_allfrag(dst)) 154667469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 154767469601SEric Dumazet } 154867469601SEric Dumazet 15495d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 15505d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 15515d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 15525d424d5aSJohn Heffner 15535d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 15545d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 15555d424d5aSJohn Heffner 15565d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 15575f3e2bf0SEric Dumazet mss_now = max(mss_now, sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss); 15585d424d5aSJohn Heffner return mss_now; 15595d424d5aSJohn Heffner } 15605d424d5aSJohn Heffner 15611b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 15621b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 15631b63edd6SYuchung Cheng { 15641b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 15651b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 15661b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 15671b63edd6SYuchung Cheng } 15681b63edd6SYuchung Cheng 15695d424d5aSJohn Heffner /* Inverse of above */ 157067469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 15715d424d5aSJohn Heffner { 1572cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1573cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 15745d424d5aSJohn Heffner int mtu; 15755d424d5aSJohn Heffner 15765d424d5aSJohn Heffner mtu = mss + 15775d424d5aSJohn Heffner tp->tcp_header_len + 15785d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 15795d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 15805d424d5aSJohn Heffner 158167469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 158267469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 158367469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 158467469601SEric Dumazet 158567469601SEric Dumazet if (dst && dst_allfrag(dst)) 158667469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 158767469601SEric Dumazet } 15885d424d5aSJohn Heffner return mtu; 15895d424d5aSJohn Heffner } 1590556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 15915d424d5aSJohn Heffner 159267edfef7SAndi Kleen /* MTU probing init per socket */ 15935d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 15945d424d5aSJohn Heffner { 15955d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 15965d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1597b0f9ca53SFan Du struct net *net = sock_net(sk); 15985d424d5aSJohn Heffner 1599b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 16005d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 16015d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1602b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 16035d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 160405cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 1605c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 16065d424d5aSJohn Heffner } 16074bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 16085d424d5aSJohn Heffner 16091da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 16101da177e4SLinus Torvalds 16111da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 16121da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 16131da177e4SLinus Torvalds 16141da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1615caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 16161da177e4SLinus Torvalds It also does not include TCP options. 16171da177e4SLinus Torvalds 1618d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 16191da177e4SLinus Torvalds 16201da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 16211da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 16221da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 16231da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 16241da177e4SLinus Torvalds 16251da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 16261da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 16271da177e4SLinus Torvalds 1628d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1629d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 16301da177e4SLinus Torvalds */ 16311da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 16321da177e4SLinus Torvalds { 16331da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1634d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 16355d424d5aSJohn Heffner int mss_now; 16361da177e4SLinus Torvalds 16375d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 16385d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 16391da177e4SLinus Torvalds 16405d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1641409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 16421da177e4SLinus Torvalds 16431da177e4SLinus Torvalds /* And store cached results */ 1644d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 16455d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 16465d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1647c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 16481da177e4SLinus Torvalds 16491da177e4SLinus Torvalds return mss_now; 16501da177e4SLinus Torvalds } 16514bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 16521da177e4SLinus Torvalds 16531da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 16541da177e4SLinus Torvalds * and even PMTU discovery events into account. 16551da177e4SLinus Torvalds */ 16560c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 16571da177e4SLinus Torvalds { 1658cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1659cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1660c1b4a7e6SDavid S. Miller u32 mss_now; 166195c96174SEric Dumazet unsigned int header_len; 166233ad798cSAdam Langley struct tcp_out_options opts; 166333ad798cSAdam Langley struct tcp_md5sig_key *md5; 16641da177e4SLinus Torvalds 1665c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1666c1b4a7e6SDavid S. Miller 16671da177e4SLinus Torvalds if (dst) { 16681da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1669d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 16701da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 16711da177e4SLinus Torvalds } 16721da177e4SLinus Torvalds 167333ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 167433ad798cSAdam Langley sizeof(struct tcphdr); 167533ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 167633ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 167733ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 167833ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 167933ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 168033ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 168133ad798cSAdam Langley mss_now -= delta; 168233ad798cSAdam Langley } 1683cfb6eeb4SYOSHIFUJI Hideaki 16841da177e4SLinus Torvalds return mss_now; 16851da177e4SLinus Torvalds } 16861da177e4SLinus Torvalds 168786fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 168886fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 168986fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 169086fd14adSWeiping Pan */ 169186fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1692a762a980SDavid S. Miller { 16939e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1694a762a980SDavid S. Miller 169586fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 169686fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 169786fd14adSWeiping Pan /* Limited by application or receiver window. */ 169886fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 169986fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 170086fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 170186fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 170286fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 170386fd14adSWeiping Pan } 170486fd14adSWeiping Pan tp->snd_cwnd_used = 0; 170586fd14adSWeiping Pan } 1706c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 170786fd14adSWeiping Pan } 170886fd14adSWeiping Pan 1709ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1710a762a980SDavid S. Miller { 17111b1fc3fdSWei Wang const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1712a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1713a762a980SDavid S. Miller 1714ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1715ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1716ca8a2263SNeal Cardwell */ 1717ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1718ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1719ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1720ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1721ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1722ca8a2263SNeal Cardwell } 1723e114a710SEric Dumazet 172424901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1725a762a980SDavid S. Miller /* Network is feed fully. */ 1726a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1727c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1728a762a980SDavid S. Miller } else { 1729a762a980SDavid S. Miller /* Network starves. */ 1730a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1731a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1732a762a980SDavid S. Miller 1733b510f0d2SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle && 1734c2203cf7SEric Dumazet (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && 17351b1fc3fdSWei Wang !ca_ops->cong_control) 1736a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1737b0f71bd3SFrancis Yan 1738b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1739b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1740b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1741b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 174275c119afSEric Dumazet * 3) no more data to send (tcp_write_queue_empty()) 1743b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1744b0f71bd3SFrancis Yan */ 174575c119afSEric Dumazet if (tcp_write_queue_empty(sk) && sk->sk_socket && 1746b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1747b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1748b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1749a762a980SDavid S. Miller } 1750a762a980SDavid S. Miller } 1751a762a980SDavid S. Miller 1752d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1753d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1754d4589926SEric Dumazet { 1755d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1756d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1757d4589926SEric Dumazet } 1758d4589926SEric Dumazet 1759d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1760d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1761d4589926SEric Dumazet * The test is really : 1762d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1763d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1764d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1765d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 17660e3a4803SIlpo Järvinen */ 1767d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1768d4589926SEric Dumazet const struct sk_buff *skb) 1769d4589926SEric Dumazet { 1770d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1771d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1772d4589926SEric Dumazet } 1773d4589926SEric Dumazet 1774d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1775d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1776d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1777d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1778d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1779d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1780d4589926SEric Dumazet */ 1781d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1782cc93fc51SPeter Pan(潘卫平) int nonagle) 1783d4589926SEric Dumazet { 1784d4589926SEric Dumazet return partial && 1785d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1786d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1787d4589926SEric Dumazet } 1788605ad7f1SEric Dumazet 1789605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1790605ad7f1SEric Dumazet * to send one TSO packet per ms 1791605ad7f1SEric Dumazet */ 1792dcb8c9b4SEric Dumazet static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 17931b3878caSNeal Cardwell int min_tso_segs) 1794605ad7f1SEric Dumazet { 1795605ad7f1SEric Dumazet u32 bytes, segs; 1796605ad7f1SEric Dumazet 179776a9ebe8SEric Dumazet bytes = min_t(unsigned long, 17987c68fa2bSEric Dumazet sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift), 1799605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1800605ad7f1SEric Dumazet 1801605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1802605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1803605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1804605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1805605ad7f1SEric Dumazet */ 18061b3878caSNeal Cardwell segs = max_t(u32, bytes / mss_now, min_tso_segs); 1807605ad7f1SEric Dumazet 1808350c9f48SEric Dumazet return segs; 1809605ad7f1SEric Dumazet } 1810605ad7f1SEric Dumazet 1811ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1812ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1813ed6e7268SNeal Cardwell */ 1814ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1815ed6e7268SNeal Cardwell { 1816ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1817dcb8c9b4SEric Dumazet u32 min_tso, tso_segs; 1818ed6e7268SNeal Cardwell 1819dcb8c9b4SEric Dumazet min_tso = ca_ops->min_tso_segs ? 1820dcb8c9b4SEric Dumazet ca_ops->min_tso_segs(sk) : 1821dcb8c9b4SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs; 1822dcb8c9b4SEric Dumazet 1823dcb8c9b4SEric Dumazet tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); 1824350c9f48SEric Dumazet return min_t(u32, tso_segs, sk->sk_gso_max_segs); 1825ed6e7268SNeal Cardwell } 1826ed6e7268SNeal Cardwell 1827d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1828d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1829d4589926SEric Dumazet const struct sk_buff *skb, 1830d4589926SEric Dumazet unsigned int mss_now, 1831d4589926SEric Dumazet unsigned int max_segs, 1832d4589926SEric Dumazet int nonagle) 1833c1b4a7e6SDavid S. Miller { 1834cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1835d4589926SEric Dumazet u32 partial, needed, window, max_len; 1836c1b4a7e6SDavid S. Miller 183790840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 18381485348dSBen Hutchings max_len = mss_now * max_segs; 18390e3a4803SIlpo Järvinen 18401485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 18411485348dSBen Hutchings return max_len; 18420e3a4803SIlpo Järvinen 18435ea3a748SIlpo Järvinen needed = min(skb->len, window); 18445ea3a748SIlpo Järvinen 18451485348dSBen Hutchings if (max_len <= needed) 18461485348dSBen Hutchings return max_len; 18470e3a4803SIlpo Järvinen 1848d4589926SEric Dumazet partial = needed % mss_now; 1849d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1850d4589926SEric Dumazet * to include this last segment in this skb. 1851d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1852d4589926SEric Dumazet */ 1853cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1854d4589926SEric Dumazet return needed - partial; 1855d4589926SEric Dumazet 1856d4589926SEric Dumazet return needed; 1857c1b4a7e6SDavid S. Miller } 1858c1b4a7e6SDavid S. Miller 1859c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1860c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1861c1b4a7e6SDavid S. Miller */ 1862cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1863cf533ea5SEric Dumazet const struct sk_buff *skb) 1864c1b4a7e6SDavid S. Miller { 1865d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1866c1b4a7e6SDavid S. Miller 1867c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 18684de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 18694de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1870c1b4a7e6SDavid S. Miller return 1; 1871c1b4a7e6SDavid S. Miller 1872c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1873c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1874d649a7a8SEric Dumazet if (in_flight >= cwnd) 1875c1b4a7e6SDavid S. Miller return 0; 1876d649a7a8SEric Dumazet 1877d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1878d649a7a8SEric Dumazet * 2 GSO packets in flight. 1879d649a7a8SEric Dumazet */ 1880d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1881d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1882c1b4a7e6SDavid S. Miller } 1883c1b4a7e6SDavid S. Miller 1884b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 188567edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1886c1b4a7e6SDavid S. Miller * SKB onto the wire. 1887c1b4a7e6SDavid S. Miller */ 18885bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1889c1b4a7e6SDavid S. Miller { 1890c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1891c1b4a7e6SDavid S. Miller 1892f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 18935bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 1894c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1895c1b4a7e6SDavid S. Miller } 1896c1b4a7e6SDavid S. Miller return tso_segs; 1897c1b4a7e6SDavid S. Miller } 1898c1b4a7e6SDavid S. Miller 1899c1b4a7e6SDavid S. Miller 1900a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1901c1b4a7e6SDavid S. Miller * sent now. 1902c1b4a7e6SDavid S. Miller */ 1903a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1904c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1905c1b4a7e6SDavid S. Miller { 1906c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1907c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1908c1b4a7e6SDavid S. Miller * 1909c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1910c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1911c1b4a7e6SDavid S. Miller */ 1912c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1913a2a385d6SEric Dumazet return true; 1914c1b4a7e6SDavid S. Miller 19159b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 19169b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1917a2a385d6SEric Dumazet return true; 1918c1b4a7e6SDavid S. Miller 1919cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1920a2a385d6SEric Dumazet return true; 1921c1b4a7e6SDavid S. Miller 1922a2a385d6SEric Dumazet return false; 1923c1b4a7e6SDavid S. Miller } 1924c1b4a7e6SDavid S. Miller 1925c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1926a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1927a2a385d6SEric Dumazet const struct sk_buff *skb, 1928056834d9SIlpo Järvinen unsigned int cur_mss) 1929c1b4a7e6SDavid S. Miller { 1930c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1931c1b4a7e6SDavid S. Miller 1932c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1933c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1934c1b4a7e6SDavid S. Miller 193590840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1936c1b4a7e6SDavid S. Miller } 1937c1b4a7e6SDavid S. Miller 1938c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1939c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1940c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1941c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1942c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1943c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1944c1b4a7e6SDavid S. Miller */ 194556483341SEric Dumazet static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1946c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1947c1b4a7e6SDavid S. Miller { 1948c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 194956483341SEric Dumazet struct sk_buff *buff; 19509ce01461SIlpo Järvinen u8 flags; 1951c1b4a7e6SDavid S. Miller 1952c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1953c8ac3774SHerbert Xu if (skb->len != skb->data_len) 195456483341SEric Dumazet return tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, 195556483341SEric Dumazet skb, len, mss_now, gfp); 1956c1b4a7e6SDavid S. Miller 1957eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp, true); 195851456b29SIan Morris if (unlikely(!buff)) 1959c1b4a7e6SDavid S. Miller return -ENOMEM; 196041477662SJakub Kicinski skb_copy_decrypted(buff, skb); 1961c1b4a7e6SDavid S. Miller 1962ab4e846aSEric Dumazet sk_wmem_queued_add(sk, buff->truesize); 19633ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1964b60b49eaSHerbert Xu buff->truesize += nlen; 1965c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1966c1b4a7e6SDavid S. Miller 1967c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1968c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1969c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1970c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1971c1b4a7e6SDavid S. Miller 1972c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 19734de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 19744de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 19754de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1976c1b4a7e6SDavid S. Miller 1977c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1978c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1979c1b4a7e6SDavid S. Miller 1980a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 1981a166140eSMartin KaFai Lau 198298be9b12SEric Dumazet buff->ip_summed = CHECKSUM_PARTIAL; 1983c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1984490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1985c1b4a7e6SDavid S. Miller 1986c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 19875bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 19885bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 1989c1b4a7e6SDavid S. Miller 1990c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1991f4a775d1SEric Dumazet __skb_header_release(buff); 199256483341SEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE); 1993c1b4a7e6SDavid S. Miller 1994c1b4a7e6SDavid S. Miller return 0; 1995c1b4a7e6SDavid S. Miller } 1996c1b4a7e6SDavid S. Miller 1997c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1998c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1999c1b4a7e6SDavid S. Miller * 2000c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 2001c1b4a7e6SDavid S. Miller */ 2002ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 2003f9bfe4e6SEric Dumazet bool *is_cwnd_limited, 2004f9bfe4e6SEric Dumazet bool *is_rwnd_limited, 2005f9bfe4e6SEric Dumazet u32 max_segs) 2006c1b4a7e6SDavid S. Miller { 20076687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 2008f1c6ea38SEric Dumazet u32 send_win, cong_win, limit, in_flight; 200950c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 201050c8339eSEric Dumazet struct sk_buff *head; 2011ad9f4f50SEric Dumazet int win_divisor; 2012f1c6ea38SEric Dumazet s64 delta; 2013c1b4a7e6SDavid S. Miller 201499d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 2015ae8064acSJohn Heffner goto send_now; 2016ae8064acSJohn Heffner 20175f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 2018a682850aSEric Dumazet * only if the last write was recent (1 ms). 2019a682850aSEric Dumazet * Note that tp->tcp_wstamp_ns can be in the future if we have 2020a682850aSEric Dumazet * packets waiting in a qdisc or device for EDT delivery. 20215f852eb5SEric Dumazet */ 2022a682850aSEric Dumazet delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC; 2023a682850aSEric Dumazet if (delta > 0) 2024ae8064acSJohn Heffner goto send_now; 2025908a75c1SDavid S. Miller 2026c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 2027c1b4a7e6SDavid S. Miller 2028c8c9aeb5SStefano Brivio BUG_ON(tcp_skb_pcount(skb) <= 1); 2029c8c9aeb5SStefano Brivio BUG_ON(tp->snd_cwnd <= in_flight); 2030c1b4a7e6SDavid S. Miller 203190840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 2032c1b4a7e6SDavid S. Miller 2033c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 2034c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 2035c1b4a7e6SDavid S. Miller 2036c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 2037c1b4a7e6SDavid S. Miller 2038ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 2039605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 2040ae8064acSJohn Heffner goto send_now; 2041ba244fe9SDavid S. Miller 204262ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 204362ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 204462ad2761SIlpo Järvinen goto send_now; 204562ad2761SIlpo Järvinen 20465bbcc0f5SLinus Torvalds win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); 2047ad9f4f50SEric Dumazet if (win_divisor) { 2048c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 2049c1b4a7e6SDavid S. Miller 2050c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 2051c1b4a7e6SDavid S. Miller * just use it. 2052c1b4a7e6SDavid S. Miller */ 2053ad9f4f50SEric Dumazet chunk /= win_divisor; 2054c1b4a7e6SDavid S. Miller if (limit >= chunk) 2055ae8064acSJohn Heffner goto send_now; 2056c1b4a7e6SDavid S. Miller } else { 2057c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 2058c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 2059c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 2060c1b4a7e6SDavid S. Miller * then send now. 2061c1b4a7e6SDavid S. Miller */ 20626b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 2063ae8064acSJohn Heffner goto send_now; 2064c1b4a7e6SDavid S. Miller } 2065c1b4a7e6SDavid S. Miller 206675c119afSEric Dumazet /* TODO : use tsorted_sent_queue ? */ 206775c119afSEric Dumazet head = tcp_rtx_queue_head(sk); 206875c119afSEric Dumazet if (!head) 206975c119afSEric Dumazet goto send_now; 2070f1c6ea38SEric Dumazet delta = tp->tcp_clock_cache - head->tstamp; 207150c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 2072f1c6ea38SEric Dumazet if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0) 207350c8339eSEric Dumazet goto send_now; 207450c8339eSEric Dumazet 2075f9bfe4e6SEric Dumazet /* Ok, it looks like it is advisable to defer. 2076f9bfe4e6SEric Dumazet * Three cases are tracked : 2077f9bfe4e6SEric Dumazet * 1) We are cwnd-limited 2078f9bfe4e6SEric Dumazet * 2) We are rwnd-limited 2079f9bfe4e6SEric Dumazet * 3) We are application limited. 2080f9bfe4e6SEric Dumazet */ 2081f9bfe4e6SEric Dumazet if (cong_win < send_win) { 2082f9bfe4e6SEric Dumazet if (cong_win <= skb->len) { 2083ca8a2263SNeal Cardwell *is_cwnd_limited = true; 2084f9bfe4e6SEric Dumazet return true; 2085f9bfe4e6SEric Dumazet } 2086f9bfe4e6SEric Dumazet } else { 2087f9bfe4e6SEric Dumazet if (send_win <= skb->len) { 2088f9bfe4e6SEric Dumazet *is_rwnd_limited = true; 2089f9bfe4e6SEric Dumazet return true; 2090f9bfe4e6SEric Dumazet } 2091f9bfe4e6SEric Dumazet } 2092f9bfe4e6SEric Dumazet 2093f9bfe4e6SEric Dumazet /* If this packet won't get more data, do not wait. */ 2094d8ed257fSEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || 2095d8ed257fSEric Dumazet TCP_SKB_CB(skb)->eor) 2096f9bfe4e6SEric Dumazet goto send_now; 2097ca8a2263SNeal Cardwell 2098a2a385d6SEric Dumazet return true; 2099ae8064acSJohn Heffner 2100ae8064acSJohn Heffner send_now: 2101a2a385d6SEric Dumazet return false; 2102c1b4a7e6SDavid S. Miller } 2103c1b4a7e6SDavid S. Miller 210405cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 210505cbc0dbSFan Du { 210605cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 210705cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 210805cbc0dbSFan Du struct net *net = sock_net(sk); 210905cbc0dbSFan Du u32 interval; 211005cbc0dbSFan Du s32 delta; 211105cbc0dbSFan Du 211205cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 2113c74df29aSEric Dumazet delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; 211405cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 211505cbc0dbSFan Du int mss = tcp_current_mss(sk); 211605cbc0dbSFan Du 211705cbc0dbSFan Du /* Update current search range */ 211805cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 211905cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 212005cbc0dbSFan Du sizeof(struct tcphdr) + 212105cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 212205cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 212305cbc0dbSFan Du 212405cbc0dbSFan Du /* Update probe time stamp */ 2125c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 212605cbc0dbSFan Du } 212705cbc0dbSFan Du } 212805cbc0dbSFan Du 2129808cf9e3SIlya Lesokhin static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) 2130808cf9e3SIlya Lesokhin { 2131808cf9e3SIlya Lesokhin struct sk_buff *skb, *next; 2132808cf9e3SIlya Lesokhin 2133808cf9e3SIlya Lesokhin skb = tcp_send_head(sk); 2134808cf9e3SIlya Lesokhin tcp_for_write_queue_from_safe(skb, next, sk) { 2135808cf9e3SIlya Lesokhin if (len <= skb->len) 2136808cf9e3SIlya Lesokhin break; 2137808cf9e3SIlya Lesokhin 2138888a5c53SWillem de Bruijn if (unlikely(TCP_SKB_CB(skb)->eor) || tcp_has_tx_tstamp(skb)) 2139808cf9e3SIlya Lesokhin return false; 2140808cf9e3SIlya Lesokhin 2141808cf9e3SIlya Lesokhin len -= skb->len; 2142808cf9e3SIlya Lesokhin } 2143808cf9e3SIlya Lesokhin 2144808cf9e3SIlya Lesokhin return true; 2145808cf9e3SIlya Lesokhin } 2146808cf9e3SIlya Lesokhin 21475d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 214867edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 214967edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 215067edfef7SAndi Kleen * changes resulting in larger path MTUs. 215167edfef7SAndi Kleen * 21525d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 21535d424d5aSJohn Heffner * 1 if a probe was sent, 2154056834d9SIlpo Järvinen * -1 otherwise 2155056834d9SIlpo Järvinen */ 21565d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 21575d424d5aSJohn Heffner { 21585d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 215912a59abcSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 21605d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 21616b58e0a5SFan Du struct net *net = sock_net(sk); 21625d424d5aSJohn Heffner int probe_size; 216391cc17c0SIlpo Järvinen int size_needed; 216412a59abcSEric Dumazet int copy, len; 21655d424d5aSJohn Heffner int mss_now; 21666b58e0a5SFan Du int interval; 21675d424d5aSJohn Heffner 21685d424d5aSJohn Heffner /* Not currently probing/verifying, 21695d424d5aSJohn Heffner * not in recovery, 21705d424d5aSJohn Heffner * have enough cwnd, and 217112a59abcSEric Dumazet * not SACKing (the variable headers throw things off) 217212a59abcSEric Dumazet */ 217312a59abcSEric Dumazet if (likely(!icsk->icsk_mtup.enabled || 21745d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 21755d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 21765d424d5aSJohn Heffner tp->snd_cwnd < 11 || 217712a59abcSEric Dumazet tp->rx_opt.num_sacks || tp->rx_opt.dsack)) 21785d424d5aSJohn Heffner return -1; 21795d424d5aSJohn Heffner 21806b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 21816b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 21826b58e0a5SFan Du * smaller than a threshold, backoff from probing. 21836b58e0a5SFan Du */ 21840c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 21856b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 21866b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 218791cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 21886b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 218905cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 219005cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 219105cbc0dbSFan Du * probing process by not resetting search range to its orignal. 219205cbc0dbSFan Du */ 21936b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 219405cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 219505cbc0dbSFan Du /* Check whether enough time has elaplased for 219605cbc0dbSFan Du * another round of probing. 219705cbc0dbSFan Du */ 219805cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 21995d424d5aSJohn Heffner return -1; 22005d424d5aSJohn Heffner } 22015d424d5aSJohn Heffner 22025d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 22037f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 22045d424d5aSJohn Heffner return -1; 22055d424d5aSJohn Heffner 220691cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 22075d424d5aSJohn Heffner return -1; 220890840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 22095d424d5aSJohn Heffner return 0; 22105d424d5aSJohn Heffner 2211d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 2212d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 2213d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 22145d424d5aSJohn Heffner return -1; 22155d424d5aSJohn Heffner else 22165d424d5aSJohn Heffner return 0; 22175d424d5aSJohn Heffner } 22185d424d5aSJohn Heffner 2219808cf9e3SIlya Lesokhin if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) 2220808cf9e3SIlya Lesokhin return -1; 2221808cf9e3SIlya Lesokhin 22225d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 2223eb934478SEric Dumazet nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); 222451456b29SIan Morris if (!nskb) 22255d424d5aSJohn Heffner return -1; 2226ab4e846aSEric Dumazet sk_wmem_queued_add(sk, nskb->truesize); 22273ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 22285d424d5aSJohn Heffner 2229fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 223041477662SJakub Kicinski skb_copy_decrypted(nskb, skb); 22315d424d5aSJohn Heffner 22325d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 22335d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 22344de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 22355d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 22365d424d5aSJohn Heffner nskb->csum = 0; 223798be9b12SEric Dumazet nskb->ip_summed = CHECKSUM_PARTIAL; 22385d424d5aSJohn Heffner 223950c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 22402b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 224150c4817eSIlpo Järvinen 22425d424d5aSJohn Heffner len = 0; 2243234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 22445d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 22455d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 22465d424d5aSJohn Heffner 22475d424d5aSJohn Heffner if (skb->len <= copy) { 22485d424d5aSJohn Heffner /* We've eaten all the data from this skb. 22495d424d5aSJohn Heffner * Throw it away. */ 22504de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2251808cf9e3SIlya Lesokhin /* If this is the last SKB we copy and eor is set 2252808cf9e3SIlya Lesokhin * we need to propagate it to the new skb. 2253808cf9e3SIlya Lesokhin */ 2254808cf9e3SIlya Lesokhin TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; 2255888a5c53SWillem de Bruijn tcp_skb_collapse_tstamp(nskb, skb); 2256fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 22573ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 22585d424d5aSJohn Heffner } else { 22594de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2260a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 22615d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 22625d424d5aSJohn Heffner skb_pull(skb, copy); 22635d424d5aSJohn Heffner } else { 22645d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 22655bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 22665d424d5aSJohn Heffner } 22675d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 22685d424d5aSJohn Heffner } 22695d424d5aSJohn Heffner 22705d424d5aSJohn Heffner len += copy; 2271234b6860SIlpo Järvinen 2272234b6860SIlpo Järvinen if (len >= probe_size) 2273234b6860SIlpo Järvinen break; 22745d424d5aSJohn Heffner } 22755bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 22765d424d5aSJohn Heffner 22775d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 22787faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 22797faee5c0SEric Dumazet */ 22805d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 22815d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 22825d424d5aSJohn Heffner * effectively two packets. */ 22835d424d5aSJohn Heffner tp->snd_cwnd--; 228466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 22855d424d5aSJohn Heffner 22865d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 22870e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 22880e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 22895d424d5aSJohn Heffner 22905d424d5aSJohn Heffner return 1; 22915d424d5aSJohn Heffner } 22925d424d5aSJohn Heffner 22935d424d5aSJohn Heffner return -1; 22945d424d5aSJohn Heffner } 22955d424d5aSJohn Heffner 2296864e5c09SEric Dumazet static bool tcp_pacing_check(struct sock *sk) 2297218af599SEric Dumazet { 2298864e5c09SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 2299864e5c09SEric Dumazet 2300864e5c09SEric Dumazet if (!tcp_needs_internal_pacing(sk)) 2301864e5c09SEric Dumazet return false; 2302864e5c09SEric Dumazet 2303864e5c09SEric Dumazet if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache) 2304864e5c09SEric Dumazet return false; 2305864e5c09SEric Dumazet 2306864e5c09SEric Dumazet if (!hrtimer_is_queued(&tp->pacing_timer)) { 2307864e5c09SEric Dumazet hrtimer_start(&tp->pacing_timer, 2308864e5c09SEric Dumazet ns_to_ktime(tp->tcp_wstamp_ns), 2309864e5c09SEric Dumazet HRTIMER_MODE_ABS_PINNED_SOFT); 2310864e5c09SEric Dumazet sock_hold(sk); 2311864e5c09SEric Dumazet } 2312864e5c09SEric Dumazet return true; 2313218af599SEric Dumazet } 2314218af599SEric Dumazet 2315f9616c35SEric Dumazet /* TCP Small Queues : 2316f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2317f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2318f9616c35SEric Dumazet * This allows for : 2319f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2320f9616c35SEric Dumazet * - faster recovery 2321f9616c35SEric Dumazet * - high rates 2322f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2323f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2324f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2325f9616c35SEric Dumazet */ 2326f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2327f9616c35SEric Dumazet unsigned int factor) 2328f9616c35SEric Dumazet { 232976a9ebe8SEric Dumazet unsigned long limit; 2330f9616c35SEric Dumazet 233176a9ebe8SEric Dumazet limit = max_t(unsigned long, 233276a9ebe8SEric Dumazet 2 * skb->truesize, 23337c68fa2bSEric Dumazet sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift)); 2334c73e5807SEric Dumazet if (sk->sk_pacing_status == SK_PACING_NONE) 233576a9ebe8SEric Dumazet limit = min_t(unsigned long, limit, 23369184d8bbSEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes); 2337f9616c35SEric Dumazet limit <<= factor; 2338f9616c35SEric Dumazet 2339a842fe14SEric Dumazet if (static_branch_unlikely(&tcp_tx_delay_enabled) && 2340a842fe14SEric Dumazet tcp_sk(sk)->tcp_tx_delay) { 2341a842fe14SEric Dumazet u64 extra_bytes = (u64)sk->sk_pacing_rate * tcp_sk(sk)->tcp_tx_delay; 2342a842fe14SEric Dumazet 2343a842fe14SEric Dumazet /* TSQ is based on skb truesize sum (sk_wmem_alloc), so we 2344a842fe14SEric Dumazet * approximate our needs assuming an ~100% skb->truesize overhead. 2345a842fe14SEric Dumazet * USEC_PER_SEC is approximated by 2^20. 2346a842fe14SEric Dumazet * do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift. 2347a842fe14SEric Dumazet */ 2348a842fe14SEric Dumazet extra_bytes >>= (20 - 1); 2349a842fe14SEric Dumazet limit += extra_bytes; 2350a842fe14SEric Dumazet } 235114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) { 235275c119afSEric Dumazet /* Always send skb if rtx queue is empty. 235375eefc6cSEric Dumazet * No need to wait for TX completion to call us back, 235475eefc6cSEric Dumazet * after softirq/tasklet schedule. 235575eefc6cSEric Dumazet * This helps when TX completions are delayed too much. 235675eefc6cSEric Dumazet */ 235775c119afSEric Dumazet if (tcp_rtx_queue_empty(sk)) 235875eefc6cSEric Dumazet return false; 235975eefc6cSEric Dumazet 23607aa5470cSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2361f9616c35SEric Dumazet /* It is possible TX completion already happened 2362f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2363f9616c35SEric Dumazet * test again the condition. 2364f9616c35SEric Dumazet */ 2365f9616c35SEric Dumazet smp_mb__after_atomic(); 236614afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) 2367f9616c35SEric Dumazet return true; 2368f9616c35SEric Dumazet } 2369f9616c35SEric Dumazet return false; 2370f9616c35SEric Dumazet } 2371f9616c35SEric Dumazet 237205b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 237305b055e8SFrancis Yan { 2374628174ccSEric Dumazet const u32 now = tcp_jiffies32; 2375efe967cdSArnd Bergmann enum tcp_chrono old = tp->chrono_type; 237605b055e8SFrancis Yan 2377efe967cdSArnd Bergmann if (old > TCP_CHRONO_UNSPEC) 2378efe967cdSArnd Bergmann tp->chrono_stat[old - 1] += now - tp->chrono_start; 237905b055e8SFrancis Yan tp->chrono_start = now; 238005b055e8SFrancis Yan tp->chrono_type = new; 238105b055e8SFrancis Yan } 238205b055e8SFrancis Yan 238305b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 238405b055e8SFrancis Yan { 238505b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 238605b055e8SFrancis Yan 238705b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 23880f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 23890f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 239005b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 239105b055e8SFrancis Yan */ 239205b055e8SFrancis Yan if (type > tp->chrono_type) 239305b055e8SFrancis Yan tcp_chrono_set(tp, type); 239405b055e8SFrancis Yan } 239505b055e8SFrancis Yan 239605b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 239705b055e8SFrancis Yan { 239805b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 239905b055e8SFrancis Yan 24000f87230dSFrancis Yan 24010f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 24020f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 24030f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 24040f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 24050f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 24060f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 24070f87230dSFrancis Yan */ 240875c119afSEric Dumazet if (tcp_rtx_and_write_queues_empty(sk)) 240905b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 24100f87230dSFrancis Yan else if (type == tp->chrono_type) 24110f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 241205b055e8SFrancis Yan } 241305b055e8SFrancis Yan 24141da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 24151da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 24161da177e4SLinus Torvalds * window for us. 24171da177e4SLinus Torvalds * 2418f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2419f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2420f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2421f8269a49SIlpo Järvinen * 24226ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 24236ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 24246ba8a3b1SNandita Dukkipati 2425a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2426a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 24271da177e4SLinus Torvalds */ 2428a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2429d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 24301da177e4SLinus Torvalds { 24311da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 243292df7b51SDavid S. Miller struct sk_buff *skb; 2433c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2434c1b4a7e6SDavid S. Miller int cwnd_quota; 24355d424d5aSJohn Heffner int result; 24365615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2437605ad7f1SEric Dumazet u32 max_segs; 24381da177e4SLinus Torvalds 2439c1b4a7e6SDavid S. Miller sent_pkts = 0; 24405d424d5aSJohn Heffner 2441ee1836aeSEric Dumazet tcp_mstamp_refresh(tp); 2442d5dd9175SIlpo Järvinen if (!push_one) { 24435d424d5aSJohn Heffner /* Do MTU probing. */ 2444d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2445d5dd9175SIlpo Järvinen if (!result) { 2446a2a385d6SEric Dumazet return false; 24475d424d5aSJohn Heffner } else if (result > 0) { 24485d424d5aSJohn Heffner sent_pkts = 1; 24495d424d5aSJohn Heffner } 2450d5dd9175SIlpo Järvinen } 24515d424d5aSJohn Heffner 2452ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2453fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2454c8ac3774SHerbert Xu unsigned int limit; 2455c8ac3774SHerbert Xu 245679861919SEric Dumazet if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 245779861919SEric Dumazet /* "skb_mstamp_ns" is used as a start point for the retransmit timer */ 245879861919SEric Dumazet skb->skb_mstamp_ns = tp->tcp_wstamp_ns = tp->tcp_clock_cache; 245979861919SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 2460bf50b606SEric Dumazet tcp_init_tso_segs(skb, mss_now); 246179861919SEric Dumazet goto repair; /* Skip network transmission */ 246279861919SEric Dumazet } 246379861919SEric Dumazet 2464218af599SEric Dumazet if (tcp_pacing_check(sk)) 2465218af599SEric Dumazet break; 2466218af599SEric Dumazet 24675bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2468c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2469c1b4a7e6SDavid S. Miller 2470b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 24716ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 24726ba8a3b1SNandita Dukkipati if (push_one == 2) 24736ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 24746ba8a3b1SNandita Dukkipati cwnd_quota = 1; 24756ba8a3b1SNandita Dukkipati else 2476b68e9f85SHerbert Xu break; 24776ba8a3b1SNandita Dukkipati } 2478b68e9f85SHerbert Xu 24795615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 24805615f886SFrancis Yan is_rwnd_limited = true; 2481b68e9f85SHerbert Xu break; 24825615f886SFrancis Yan } 2483b68e9f85SHerbert Xu 2484d6a4e26aSEric Dumazet if (tso_segs == 1) { 2485aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2486aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2487aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2488aa93466bSDavid S. Miller break; 2489c1b4a7e6SDavid S. Miller } else { 2490ca8a2263SNeal Cardwell if (!push_one && 2491605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2492f9bfe4e6SEric Dumazet &is_rwnd_limited, max_segs)) 2493aa93466bSDavid S. Miller break; 2494c1b4a7e6SDavid S. Miller } 2495aa93466bSDavid S. Miller 2496605ad7f1SEric Dumazet limit = mss_now; 2497d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2498605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2499605ad7f1SEric Dumazet min_t(unsigned int, 2500605ad7f1SEric Dumazet cwnd_quota, 2501605ad7f1SEric Dumazet max_segs), 2502605ad7f1SEric Dumazet nonagle); 2503605ad7f1SEric Dumazet 2504605ad7f1SEric Dumazet if (skb->len > limit && 250556483341SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2506605ad7f1SEric Dumazet break; 2507605ad7f1SEric Dumazet 2508f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 250946d3ceabSEric Dumazet break; 2510c9eeec26SEric Dumazet 25111f85e626SEric Dumazet /* Argh, we hit an empty skb(), presumably a thread 25121f85e626SEric Dumazet * is sleeping in sendmsg()/sk_stream_wait_memory(). 25131f85e626SEric Dumazet * We do not want to send a pure-ack packet and have 25141f85e626SEric Dumazet * a strange looking rtx queue with empty packet(s). 25151f85e626SEric Dumazet */ 25161f85e626SEric Dumazet if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) 25171f85e626SEric Dumazet break; 25181f85e626SEric Dumazet 2519d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 25201da177e4SLinus Torvalds break; 25211da177e4SLinus Torvalds 2522ec342325SAndrew Vagin repair: 25231da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 25241da177e4SLinus Torvalds * This call will increment packets_out. 25251da177e4SLinus Torvalds */ 252666f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 25271da177e4SLinus Torvalds 25281da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2529a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2530d5dd9175SIlpo Järvinen 2531d5dd9175SIlpo Järvinen if (push_one) 2532d5dd9175SIlpo Järvinen break; 25331da177e4SLinus Torvalds } 25341da177e4SLinus Torvalds 25355615f886SFrancis Yan if (is_rwnd_limited) 25365615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 25375615f886SFrancis Yan else 25385615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 25395615f886SFrancis Yan 2540aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2541684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2542684bad11SYuchung Cheng tp->prr_out += sent_pkts; 25436ba8a3b1SNandita Dukkipati 25446ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 25456ba8a3b1SNandita Dukkipati if (push_one != 2) 2546ed66dfafSNeal Cardwell tcp_schedule_loss_probe(sk, false); 2547d2e1339fSBendik Rønning Opstad is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); 2548ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2549a2a385d6SEric Dumazet return false; 25501da177e4SLinus Torvalds } 255175c119afSEric Dumazet return !tp->packets_out && !tcp_write_queue_empty(sk); 25526ba8a3b1SNandita Dukkipati } 25536ba8a3b1SNandita Dukkipati 2554ed66dfafSNeal Cardwell bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) 25556ba8a3b1SNandita Dukkipati { 25566ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 25576ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 2558a2815817SNeal Cardwell u32 timeout, rto_delta_us; 25592ae21cf5SEric Dumazet int early_retrans; 25606ba8a3b1SNandita Dukkipati 25616ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 25626ba8a3b1SNandita Dukkipati * finishes. 25636ba8a3b1SNandita Dukkipati */ 2564d983ea6fSEric Dumazet if (rcu_access_pointer(tp->fastopen_rsk)) 25656ba8a3b1SNandita Dukkipati return false; 25666ba8a3b1SNandita Dukkipati 25672ae21cf5SEric Dumazet early_retrans = sock_net(sk)->ipv4.sysctl_tcp_early_retrans; 25686ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 2569b4f70c3dSNeal Cardwell * not in loss recovery, that are either limited by cwnd or application. 25706ba8a3b1SNandita Dukkipati */ 25712ae21cf5SEric Dumazet if ((early_retrans != 3 && early_retrans != 4) || 2572bec41a11SYuchung Cheng !tp->packets_out || !tcp_is_sack(tp) || 2573b4f70c3dSNeal Cardwell (icsk->icsk_ca_state != TCP_CA_Open && 2574b4f70c3dSNeal Cardwell icsk->icsk_ca_state != TCP_CA_CWR)) 25756ba8a3b1SNandita Dukkipati return false; 25766ba8a3b1SNandita Dukkipati 2577bb4d991aSYuchung Cheng /* Probe timeout is 2*rtt. Add minimum RTO to account 2578f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2579f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 25806ba8a3b1SNandita Dukkipati */ 2581bb4d991aSYuchung Cheng if (tp->srtt_us) { 2582bb4d991aSYuchung Cheng timeout = usecs_to_jiffies(tp->srtt_us >> 2); 25836ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 2584bb4d991aSYuchung Cheng timeout += TCP_RTO_MIN; 2585bb4d991aSYuchung Cheng else 2586bb4d991aSYuchung Cheng timeout += TCP_TIMEOUT_MIN; 2587bb4d991aSYuchung Cheng } else { 2588bb4d991aSYuchung Cheng timeout = TCP_TIMEOUT_INIT; 2589bb4d991aSYuchung Cheng } 25906ba8a3b1SNandita Dukkipati 2591a2815817SNeal Cardwell /* If the RTO formula yields an earlier time, then use that time. */ 2592ed66dfafSNeal Cardwell rto_delta_us = advancing_rto ? 2593ed66dfafSNeal Cardwell jiffies_to_usecs(inet_csk(sk)->icsk_rto) : 2594ed66dfafSNeal Cardwell tcp_rto_delta_us(sk); /* How far in future is RTO? */ 2595a2815817SNeal Cardwell if (rto_delta_us > 0) 2596a2815817SNeal Cardwell timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); 25976ba8a3b1SNandita Dukkipati 25988dc242adSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX); 25996ba8a3b1SNandita Dukkipati return true; 26006ba8a3b1SNandita Dukkipati } 26016ba8a3b1SNandita Dukkipati 26021f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 26031f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 26041f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 26051f3279aeSEric Dumazet */ 26061f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 26071f3279aeSEric Dumazet const struct sk_buff *skb) 26081f3279aeSEric Dumazet { 260939bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2610c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 26111f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 26121f3279aeSEric Dumazet return true; 26131f3279aeSEric Dumazet } 26141f3279aeSEric Dumazet return false; 26151f3279aeSEric Dumazet } 26161f3279aeSEric Dumazet 2617b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 26186ba8a3b1SNandita Dukkipati * retransmit the last segment. 26196ba8a3b1SNandita Dukkipati */ 26206ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 26216ba8a3b1SNandita Dukkipati { 26229b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 26236ba8a3b1SNandita Dukkipati struct sk_buff *skb; 26246ba8a3b1SNandita Dukkipati int pcount; 26256ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 26266ba8a3b1SNandita Dukkipati 2627*76be93fcSYuchung Cheng /* At most one outstanding TLP */ 2628*76be93fcSYuchung Cheng if (tp->tlp_high_seq) 2629*76be93fcSYuchung Cheng goto rearm_timer; 2630*76be93fcSYuchung Cheng 2631*76be93fcSYuchung Cheng tp->tlp_retrans = 0; 2632b340b264SYuchung Cheng skb = tcp_send_head(sk); 263375c119afSEric Dumazet if (skb && tcp_snd_wnd_test(tp, skb, mss)) { 2634b340b264SYuchung Cheng pcount = tp->packets_out; 2635b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2636b340b264SYuchung Cheng if (tp->packets_out > pcount) 2637b340b264SYuchung Cheng goto probe_sent; 26386ba8a3b1SNandita Dukkipati goto rearm_timer; 26396ba8a3b1SNandita Dukkipati } 264075c119afSEric Dumazet skb = skb_rb_last(&sk->tcp_rtx_queue); 2641b2b7af86SYuchung Cheng if (unlikely(!skb)) { 2642b2b7af86SYuchung Cheng WARN_ONCE(tp->packets_out, 2643b2b7af86SYuchung Cheng "invalid inflight: %u state %u cwnd %u mss %d\n", 2644b2b7af86SYuchung Cheng tp->packets_out, sk->sk_state, tp->snd_cwnd, mss); 2645b2b7af86SYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2646b2b7af86SYuchung Cheng return; 2647b2b7af86SYuchung Cheng } 26486ba8a3b1SNandita Dukkipati 26491f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 26501f3279aeSEric Dumazet goto rearm_timer; 26511f3279aeSEric Dumazet 26526ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 26536ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 26546ba8a3b1SNandita Dukkipati goto rearm_timer; 26556ba8a3b1SNandita Dukkipati 26566ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 265775c119afSEric Dumazet if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, 265875c119afSEric Dumazet (pcount - 1) * mss, mss, 26596cc55e09SOctavian Purdila GFP_ATOMIC))) 26606ba8a3b1SNandita Dukkipati goto rearm_timer; 266175c119afSEric Dumazet skb = skb_rb_next(skb); 26626ba8a3b1SNandita Dukkipati } 26636ba8a3b1SNandita Dukkipati 26646ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 26656ba8a3b1SNandita Dukkipati goto rearm_timer; 26666ba8a3b1SNandita Dukkipati 266710d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2668b340b264SYuchung Cheng goto rearm_timer; 26696ba8a3b1SNandita Dukkipati 2670*76be93fcSYuchung Cheng tp->tlp_retrans = 1; 2671*76be93fcSYuchung Cheng 2672*76be93fcSYuchung Cheng probe_sent: 26739b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 26749b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 26759b717a8dSNandita Dukkipati 2676c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2677fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2678fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2679b340b264SYuchung Cheng rearm_timer: 2680fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 26811da177e4SLinus Torvalds } 26821da177e4SLinus Torvalds 2683a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2684a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2685a762a980SDavid S. Miller * The socket must be locked by the caller. 2686a762a980SDavid S. Miller */ 26879e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 26889e412ba7SIlpo Järvinen int nonagle) 2689a762a980SDavid S. Miller { 2690726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2691726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2692726e07a8SIlpo Järvinen * all will be happy. 2693726e07a8SIlpo Järvinen */ 2694726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2695726e07a8SIlpo Järvinen return; 2696726e07a8SIlpo Järvinen 269799a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 26987450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 26999e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2700a762a980SDavid S. Miller } 2701a762a980SDavid S. Miller 2702c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2703c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2704c1b4a7e6SDavid S. Miller */ 2705c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2706c1b4a7e6SDavid S. Miller { 2707fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2708c1b4a7e6SDavid S. Miller 2709c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2710c1b4a7e6SDavid S. Miller 2711d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2712c1b4a7e6SDavid S. Miller } 2713c1b4a7e6SDavid S. Miller 27141da177e4SLinus Torvalds /* This function returns the amount that we can raise the 27151da177e4SLinus Torvalds * usable window based on the following constraints 27161da177e4SLinus Torvalds * 27171da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 27181da177e4SLinus Torvalds * 2. We limit memory per socket 27191da177e4SLinus Torvalds * 27201da177e4SLinus Torvalds * RFC 1122: 27211da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 27221da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 27231da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 27241da177e4SLinus Torvalds * 27251da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 27261da177e4SLinus Torvalds * it at least MSS bytes. 27271da177e4SLinus Torvalds * 27281da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 27291da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 27301da177e4SLinus Torvalds * 27311da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 27321da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 27331da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 27341da177e4SLinus Torvalds * window to always advance by a single byte. 27351da177e4SLinus Torvalds * 27361da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 27371da177e4SLinus Torvalds * then this will not be a problem. 27381da177e4SLinus Torvalds * 27391da177e4SLinus Torvalds * BSD seems to make the following compromise: 27401da177e4SLinus Torvalds * 27411da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 27421da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 27431da177e4SLinus Torvalds * then set the window to 0. 27441da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 27451da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 27461da177e4SLinus Torvalds * and from being larger than the largest representable value. 27471da177e4SLinus Torvalds * 27481da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 27491da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 27501da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 27511da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 27521da177e4SLinus Torvalds * because the pipeline is full. 27531da177e4SLinus Torvalds * 27541da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 27551da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 27561da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 27571da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 27581da177e4SLinus Torvalds * of having a fixed window size at almost all times. 27591da177e4SLinus Torvalds * 27601da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 27611da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 27621da177e4SLinus Torvalds * 27631da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 27641da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 27651da177e4SLinus Torvalds */ 27661da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 27671da177e4SLinus Torvalds { 2768463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 27691da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2770caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 27711da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 27721da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 27731da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 27741da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 27751da177e4SLinus Torvalds */ 2776463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 27771da177e4SLinus Torvalds int free_space = tcp_space(sk); 277886c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 2779071c8ed6SFlorian Westphal int full_space, window; 2780071c8ed6SFlorian Westphal 2781071c8ed6SFlorian Westphal if (sk_is_mptcp(sk)) 2782071c8ed6SFlorian Westphal mptcp_space(sk, &free_space, &allowed_space); 2783071c8ed6SFlorian Westphal 2784071c8ed6SFlorian Westphal full_space = min_t(int, tp->window_clamp, allowed_space); 27851da177e4SLinus Torvalds 278606425c30SEric Dumazet if (unlikely(mss > full_space)) { 27871da177e4SLinus Torvalds mss = full_space; 278806425c30SEric Dumazet if (mss <= 0) 278906425c30SEric Dumazet return 0; 279006425c30SEric Dumazet } 2791b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2792463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 27931da177e4SLinus Torvalds 2794b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 2795056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2796056834d9SIlpo Järvinen 4U * tp->advmss); 27971da177e4SLinus Torvalds 279886c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 279986c1a045SFlorian Westphal * increase it due to wscale. 280086c1a045SFlorian Westphal */ 280186c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 280286c1a045SFlorian Westphal 280386c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 280486c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 280586c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 280686c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 280786c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 280886c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 280986c1a045SFlorian Westphal */ 281086c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 28111da177e4SLinus Torvalds return 0; 28121da177e4SLinus Torvalds } 28131da177e4SLinus Torvalds 28141da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 28151da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 28161da177e4SLinus Torvalds 28171da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 28181da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 28191da177e4SLinus Torvalds */ 28201da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 28211da177e4SLinus Torvalds window = free_space; 28221da177e4SLinus Torvalds 28231da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 28241da177e4SLinus Torvalds * Import case: prevent zero window announcement if 28251da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 28261da177e4SLinus Torvalds */ 28271935299dSGao Feng window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); 28281da177e4SLinus Torvalds } else { 28291935299dSGao Feng window = tp->rcv_wnd; 28301da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 28311da177e4SLinus Torvalds * Window clamp already applied above. 28321da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 28331da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 28341da177e4SLinus Torvalds * and multiply from happening most of the time. 28351da177e4SLinus Torvalds * We also don't do any window rounding when the free space 28361da177e4SLinus Torvalds * is too small. 28371da177e4SLinus Torvalds */ 28381da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 28391935299dSGao Feng window = rounddown(free_space, mss); 284084565070SJohn Heffner else if (mss == full_space && 2841b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 284284565070SJohn Heffner window = free_space; 28431da177e4SLinus Torvalds } 28441da177e4SLinus Torvalds 28451da177e4SLinus Torvalds return window; 28461da177e4SLinus Torvalds } 28471da177e4SLinus Torvalds 2848cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 2849082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 2850082ac2d5SMartin KaFai Lau { 28510a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 28520a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 28530a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 2854082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 2855082ac2d5SMartin KaFai Lau 28560a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 2857082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 28582de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 28592de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 2860082ac2d5SMartin KaFai Lau } 2861082ac2d5SMartin KaFai Lau } 2862082ac2d5SMartin KaFai Lau 28634a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 2864f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 28651da177e4SLinus Torvalds { 28661da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 286775c119afSEric Dumazet struct sk_buff *next_skb = skb_rb_next(skb); 286813dde04fSWei Yongjun int next_skb_size; 28691da177e4SLinus Torvalds 2870058dc334SIlpo Järvinen next_skb_size = next_skb->len; 28711da177e4SLinus Torvalds 2872058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 28731da177e4SLinus Torvalds 2874f8071cdeSEric Dumazet if (next_skb_size) { 2875f8071cdeSEric Dumazet if (next_skb_size <= skb_availroom(skb)) 2876f8071cdeSEric Dumazet skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), 2877f8071cdeSEric Dumazet next_skb_size); 28783b4929f6SEric Dumazet else if (!tcp_skb_shift(skb, next_skb, 1, next_skb_size)) 2879f8071cdeSEric Dumazet return false; 2880f8071cdeSEric Dumazet } 28812b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, next_skb, skb); 2882a6963a6bSIlpo Järvinen 28831da177e4SLinus Torvalds /* Update sequence range on original skb. */ 28841da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 28851da177e4SLinus Torvalds 2886e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 28874de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 28881da177e4SLinus Torvalds 28891da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 28901da177e4SLinus Torvalds * packet counting does not break. 28911da177e4SLinus Torvalds */ 28924828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2893a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 2894b7689205SIlpo Järvinen 2895b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2896ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2897ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2898ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2899b7689205SIlpo Järvinen 2900797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2901797108d1SIlpo Järvinen 2902082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 2903082ac2d5SMartin KaFai Lau 290475c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(next_skb, sk); 2905f8071cdeSEric Dumazet return true; 29061da177e4SLinus Torvalds } 29071da177e4SLinus Torvalds 290867edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2909a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 29104a17fc3aSIlpo Järvinen { 29114a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2912a2a385d6SEric Dumazet return false; 29134a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2914a2a385d6SEric Dumazet return false; 29152331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 29164a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2917a2a385d6SEric Dumazet return false; 29184a17fc3aSIlpo Järvinen 2919a2a385d6SEric Dumazet return true; 29204a17fc3aSIlpo Järvinen } 29214a17fc3aSIlpo Järvinen 292267edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 292367edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 292467edfef7SAndi Kleen */ 29254a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 29264a17fc3aSIlpo Järvinen int space) 29274a17fc3aSIlpo Järvinen { 29284a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 29294a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2930a2a385d6SEric Dumazet bool first = true; 29314a17fc3aSIlpo Järvinen 2932e0a1e5b5SEric Dumazet if (!sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse) 29334a17fc3aSIlpo Järvinen return; 29344de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 29354a17fc3aSIlpo Järvinen return; 29364a17fc3aSIlpo Järvinen 293775c119afSEric Dumazet skb_rbtree_walk_from_safe(skb, tmp) { 29384a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 29394a17fc3aSIlpo Järvinen break; 29404a17fc3aSIlpo Järvinen 294185712484SMat Martineau if (!tcp_skb_can_collapse(to, skb)) 2942a643b5d4SMartin KaFai Lau break; 2943a643b5d4SMartin KaFai Lau 29444a17fc3aSIlpo Järvinen space -= skb->len; 29454a17fc3aSIlpo Järvinen 29464a17fc3aSIlpo Järvinen if (first) { 2947a2a385d6SEric Dumazet first = false; 29484a17fc3aSIlpo Järvinen continue; 29494a17fc3aSIlpo Järvinen } 29504a17fc3aSIlpo Järvinen 29514a17fc3aSIlpo Järvinen if (space < 0) 29524a17fc3aSIlpo Järvinen break; 29534a17fc3aSIlpo Järvinen 29544a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 29554a17fc3aSIlpo Järvinen break; 29564a17fc3aSIlpo Järvinen 2957f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 2958f8071cdeSEric Dumazet break; 29594a17fc3aSIlpo Järvinen } 29604a17fc3aSIlpo Järvinen } 29614a17fc3aSIlpo Järvinen 29621da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 29631da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 29641da177e4SLinus Torvalds * error occurred which prevented the send. 29651da177e4SLinus Torvalds */ 296610d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 29671da177e4SLinus Torvalds { 29685d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 296910d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 29707d227cd2SSridhar Samudrala unsigned int cur_mss; 297110d3be56SEric Dumazet int diff, len, err; 29721da177e4SLinus Torvalds 297310d3be56SEric Dumazet 297410d3be56SEric Dumazet /* Inconclusive MTU probe */ 297510d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 29765d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 29775d424d5aSJohn Heffner 29781da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2979caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 29801da177e4SLinus Torvalds */ 298114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > 2982ffb4d6c8SEric Dumazet min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), 2983ffb4d6c8SEric Dumazet sk->sk_sndbuf)) 29841da177e4SLinus Torvalds return -EAGAIN; 29851da177e4SLinus Torvalds 29861f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 29871f3279aeSEric Dumazet return -EBUSY; 29881f3279aeSEric Dumazet 29891da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 29907f582b24SEric Dumazet if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { 29917f582b24SEric Dumazet WARN_ON_ONCE(1); 29927f582b24SEric Dumazet return -EINVAL; 29937f582b24SEric Dumazet } 29941da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 29951da177e4SLinus Torvalds return -ENOMEM; 29961da177e4SLinus Torvalds } 29971da177e4SLinus Torvalds 29987d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 29997d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 30007d227cd2SSridhar Samudrala 30010c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 30027d227cd2SSridhar Samudrala 30031da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 30041da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 30051da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 30061da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 30071da177e4SLinus Torvalds */ 30089d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 30099d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 30101da177e4SLinus Torvalds return -EAGAIN; 30111da177e4SLinus Torvalds 301210d3be56SEric Dumazet len = cur_mss * segs; 301310d3be56SEric Dumazet if (skb->len > len) { 301475c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, 301575c119afSEric Dumazet cur_mss, GFP_ATOMIC)) 30161da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 301702276f3cSIlpo Järvinen } else { 3018c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 3019c52e2421SEric Dumazet return -ENOMEM; 302010d3be56SEric Dumazet 302110d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 302210d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 302310d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 302410d3be56SEric Dumazet if (diff) 302510d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 302610d3be56SEric Dumazet if (skb->len < cur_mss) 302710d3be56SEric Dumazet tcp_retrans_try_collapse(sk, skb, cur_mss); 30281da177e4SLinus Torvalds } 30291da177e4SLinus Torvalds 303049213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 303149213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 303249213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 303349213555SDaniel Borkmann 3034678550c6SYuchung Cheng /* Update global and local TCP statistics. */ 3035678550c6SYuchung Cheng segs = tcp_skb_pcount(skb); 3036678550c6SYuchung Cheng TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 3037678550c6SYuchung Cheng if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 3038678550c6SYuchung Cheng __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 3039678550c6SYuchung Cheng tp->total_retrans += segs; 3040fb31c9b9SWei Wang tp->bytes_retrans += skb->len; 3041678550c6SYuchung Cheng 304250bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 304350bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 304450bceae9SThomas Graf * beyond what csum_start can cover. 304550bceae9SThomas Graf */ 304650bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 304750bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 304810a81980SEric Dumazet struct sk_buff *nskb; 304910a81980SEric Dumazet 3050e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 305110a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 305207f8e4d0SFlorian Westphal if (nskb) { 305307f8e4d0SFlorian Westphal nskb->dev = NULL; 305407f8e4d0SFlorian Westphal err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC); 305507f8e4d0SFlorian Westphal } else { 305607f8e4d0SFlorian Westphal err = -ENOBUFS; 305707f8e4d0SFlorian Westphal } 3058e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 3059e2080072SEric Dumazet 30605889e2c0SYousuk Seung if (!err) { 3061a7a25630SEric Dumazet tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns); 30625889e2c0SYousuk Seung tcp_rate_skb_sent(sk, skb); 30635889e2c0SYousuk Seung } 3064117632e6SEric Dumazet } else { 3065c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 3066117632e6SEric Dumazet } 3067c84a5711SYuchung Cheng 30687f12422cSYuchung Cheng /* To avoid taking spuriously low RTT samples based on a timestamp 30697f12422cSYuchung Cheng * for a transmit that never happened, always mark EVER_RETRANS 30707f12422cSYuchung Cheng */ 30717f12422cSYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 30727f12422cSYuchung Cheng 3073a31ad29eSLawrence Brakmo if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) 3074a31ad29eSLawrence Brakmo tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, 3075a31ad29eSLawrence Brakmo TCP_SKB_CB(skb)->seq, segs, err); 3076a31ad29eSLawrence Brakmo 3077fc9f3501SEric Dumazet if (likely(!err)) { 3078e086101bSCong Wang trace_tcp_retransmit_skb(sk, skb); 3079678550c6SYuchung Cheng } else if (err != -EBUSY) { 3080ec641b39SYuchung Cheng NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs); 3081fc9f3501SEric Dumazet } 3082c84a5711SYuchung Cheng return err; 308393b174adSYuchung Cheng } 308493b174adSYuchung Cheng 308510d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 308693b174adSYuchung Cheng { 308793b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 308810d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 30891da177e4SLinus Torvalds 30901da177e4SLinus Torvalds if (err == 0) { 30911da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 30921da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 3093e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 30941da177e4SLinus Torvalds } 30951da177e4SLinus Torvalds #endif 30961da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 30971da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 30987ae18975SYuchung Cheng } 30991da177e4SLinus Torvalds 31007ae18975SYuchung Cheng /* Save stamp of the first (attempted) retransmit. */ 31011da177e4SLinus Torvalds if (!tp->retrans_stamp) 31027faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 31031da177e4SLinus Torvalds 31046e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 31056e08d5e3SYuchung Cheng tp->undo_retrans = 0; 31066e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 31071da177e4SLinus Torvalds return err; 31081da177e4SLinus Torvalds } 31091da177e4SLinus Torvalds 31101da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 31111da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 31121da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 31131da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 31141da177e4SLinus Torvalds */ 31151da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 31161da177e4SLinus Torvalds { 31176687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 3118b9f1f1ceSEric Dumazet struct sk_buff *skb, *rtx_head, *hole = NULL; 31191da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3120916e6d1aSEric Dumazet bool rearm_timer = false; 3121840a3cbeSYuchung Cheng u32 max_segs; 312261eb55f4SIlpo Järvinen int mib_idx; 31236a438bbeSStephen Hemminger 312445e77d31SIlpo Järvinen if (!tp->packets_out) 312545e77d31SIlpo Järvinen return; 312645e77d31SIlpo Järvinen 312775c119afSEric Dumazet rtx_head = tcp_rtx_queue_head(sk); 3128b9f1f1ceSEric Dumazet skb = tp->retransmit_skb_hint ?: rtx_head; 3129ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 313075c119afSEric Dumazet skb_rbtree_walk_from(skb) { 3131dca0aaf8SEric Dumazet __u8 sacked; 313210d3be56SEric Dumazet int segs; 31331da177e4SLinus Torvalds 3134218af599SEric Dumazet if (tcp_pacing_check(sk)) 3135218af599SEric Dumazet break; 3136218af599SEric Dumazet 31376a438bbeSStephen Hemminger /* we could do better than to assign each time */ 313851456b29SIan Morris if (!hole) 31396a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 31406a438bbeSStephen Hemminger 314110d3be56SEric Dumazet segs = tp->snd_cwnd - tcp_packets_in_flight(tp); 314210d3be56SEric Dumazet if (segs <= 0) 3143916e6d1aSEric Dumazet break; 3144dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 3145a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 3146a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 3147a3d2e9f8SEric Dumazet */ 3148a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 31490e1c54c2SIlpo Järvinen 3150840a3cbeSYuchung Cheng if (tp->retrans_out >= tp->lost_out) { 3151006f582cSIlpo Järvinen break; 31520e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 315351456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 31540e1c54c2SIlpo Järvinen hole = skb; 315561eb55f4SIlpo Järvinen continue; 31561da177e4SLinus Torvalds 31570e1c54c2SIlpo Järvinen } else { 31580e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 31590e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 31600e1c54c2SIlpo Järvinen else 31610e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 31620e1c54c2SIlpo Järvinen } 31630e1c54c2SIlpo Järvinen 31640e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 316561eb55f4SIlpo Järvinen continue; 316640b215e5SPavel Emelyanov 3167f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 3168916e6d1aSEric Dumazet break; 3169f9616c35SEric Dumazet 317010d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 3171916e6d1aSEric Dumazet break; 317224ab6becSYuchung Cheng 3173de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 31741da177e4SLinus Torvalds 3175684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 3176a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 3177a262f0cdSNandita Dukkipati 317875c119afSEric Dumazet if (skb == rtx_head && 317957dde7f7SYuchung Cheng icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) 3180916e6d1aSEric Dumazet rearm_timer = true; 3181916e6d1aSEric Dumazet 3182916e6d1aSEric Dumazet } 3183916e6d1aSEric Dumazet if (rearm_timer) 31843f80e08fSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 31853f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 31868dc242adSEric Dumazet TCP_RTO_MAX); 31871da177e4SLinus Torvalds } 31881da177e4SLinus Torvalds 3189d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 3190d83769a5SEric Dumazet * connection tear down and (memory) recovery. 3191845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 3192845704a5SEric Dumazet * or even be forced to close flow without any FIN. 3193a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 3194a6c5ea4cSEric Dumazet * with edge trigger epoll() 3195d83769a5SEric Dumazet */ 3196a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 3197d83769a5SEric Dumazet { 3198e805605cSJohannes Weiner int amt; 3199d83769a5SEric Dumazet 3200d83769a5SEric Dumazet if (size <= sk->sk_forward_alloc) 3201d83769a5SEric Dumazet return; 3202d83769a5SEric Dumazet amt = sk_mem_pages(size); 3203d83769a5SEric Dumazet sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; 3204e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 3205e805605cSJohannes Weiner 3206baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 3207baac50bbSJohannes Weiner mem_cgroup_charge_skmem(sk->sk_memcg, amt); 3208d83769a5SEric Dumazet } 3209d83769a5SEric Dumazet 3210845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 3211845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 32121da177e4SLinus Torvalds */ 32131da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 32141da177e4SLinus Torvalds { 3215ee2aabd3SEric Dumazet struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk); 32161da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32171da177e4SLinus Torvalds 3218845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 3219845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 3220845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 3221845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 32221da177e4SLinus Torvalds */ 3223ee2aabd3SEric Dumazet tskb = tail; 322475c119afSEric Dumazet if (!tskb && tcp_under_memory_pressure(sk)) 322575c119afSEric Dumazet tskb = skb_rb_last(&sk->tcp_rtx_queue); 322675c119afSEric Dumazet 322775c119afSEric Dumazet if (tskb) { 3228845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 3229845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 32301da177e4SLinus Torvalds tp->write_seq++; 3231ee2aabd3SEric Dumazet if (!tail) { 3232845704a5SEric Dumazet /* This means tskb was already sent. 3233845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 3234845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 3235845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 3236845704a5SEric Dumazet * does not change tp->snd_nxt. 3237845704a5SEric Dumazet */ 3238e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->snd_nxt + 1); 3239845704a5SEric Dumazet return; 3240845704a5SEric Dumazet } 32411da177e4SLinus Torvalds } else { 3242845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3243d1edc085SColin Ian King if (unlikely(!skb)) 3244845704a5SEric Dumazet return; 3245d1edc085SColin Ian King 3246e2080072SEric Dumazet INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); 3247d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3248a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 32491da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3250e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3251a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 32521da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 32531da177e4SLinus Torvalds } 3254845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 32551da177e4SLinus Torvalds } 32561da177e4SLinus Torvalds 32571da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 32581da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 32591da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 326065bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 32611da177e4SLinus Torvalds */ 3262dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 32631da177e4SLinus Torvalds { 32641da177e4SLinus Torvalds struct sk_buff *skb; 32651da177e4SLinus Torvalds 32667cc2b043SGao Feng TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 32677cc2b043SGao Feng 32681da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 32691da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 32701da177e4SLinus Torvalds if (!skb) { 32714e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 32721da177e4SLinus Torvalds return; 32731da177e4SLinus Torvalds } 32741da177e4SLinus Torvalds 32751da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 32761da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3277e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3278a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 32799a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 32801da177e4SLinus Torvalds /* Send it off. */ 3281dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 32824e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 3283c24b14c4SSong Liu 3284c24b14c4SSong Liu /* skb of trace_tcp_send_reset() keeps the skb that caused RST, 3285c24b14c4SSong Liu * skb here is different to the troublesome skb, so use NULL 3286c24b14c4SSong Liu */ 3287c24b14c4SSong Liu trace_tcp_send_reset(sk, NULL); 32881da177e4SLinus Torvalds } 32891da177e4SLinus Torvalds 329067edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 329167edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 32921da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 32931da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 32941da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 32951da177e4SLinus Torvalds */ 32961da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 32971da177e4SLinus Torvalds { 32981da177e4SLinus Torvalds struct sk_buff *skb; 32991da177e4SLinus Torvalds 330075c119afSEric Dumazet skb = tcp_rtx_queue_head(sk); 330151456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 330275c119afSEric Dumazet pr_err("%s: wrong queue state\n", __func__); 33031da177e4SLinus Torvalds return -EFAULT; 33041da177e4SLinus Torvalds } 33054de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 33061da177e4SLinus Torvalds if (skb_cloned(skb)) { 3307e2080072SEric Dumazet struct sk_buff *nskb; 3308e2080072SEric Dumazet 3309e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 3310e2080072SEric Dumazet nskb = skb_copy(skb, GFP_ATOMIC); 3311e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 331251456b29SIan Morris if (!nskb) 33131da177e4SLinus Torvalds return -ENOMEM; 3314e2080072SEric Dumazet INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); 33152bec445fSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 331675c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(skb, sk); 3317f4a775d1SEric Dumazet __skb_header_release(nskb); 331875c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); 3319ab4e846aSEric Dumazet sk_wmem_queued_add(sk, nskb->truesize); 33203ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 33211da177e4SLinus Torvalds skb = nskb; 33221da177e4SLinus Torvalds } 33231da177e4SLinus Torvalds 33244de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3325735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 33261da177e4SLinus Torvalds } 3327dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 33281da177e4SLinus Torvalds } 33291da177e4SLinus Torvalds 33304aea39c1SEric Dumazet /** 33314aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 33324aea39c1SEric Dumazet * sk: listener socket 33334aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 33344aea39c1SEric Dumazet * req: request_sock pointer 33354aea39c1SEric Dumazet * 33364aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 33374aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 33384aea39c1SEric Dumazet */ 33395d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3340e6b4d113SWilliam Allen Simpson struct request_sock *req, 3341ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3342b3d05147SEric Dumazet enum tcp_synack_type synack_type) 33431da177e4SLinus Torvalds { 33442e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 33455d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 334680f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 33475d062de7SEric Dumazet struct tcp_out_options opts; 33485d062de7SEric Dumazet struct sk_buff *skb; 3349bd0388aeSWilliam Allen Simpson int tcp_header_size; 33505d062de7SEric Dumazet struct tcphdr *th; 3351f5fff5dcSTom Quetchenbach int mss; 3352a842fe14SEric Dumazet u64 now; 33531da177e4SLinus Torvalds 3354ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 33554aea39c1SEric Dumazet if (unlikely(!skb)) { 33564aea39c1SEric Dumazet dst_release(dst); 33571da177e4SLinus Torvalds return NULL; 33584aea39c1SEric Dumazet } 33591da177e4SLinus Torvalds /* Reserve space for headers. */ 33601da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 33611da177e4SLinus Torvalds 3362b3d05147SEric Dumazet switch (synack_type) { 3363b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 33649e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3365b3d05147SEric Dumazet break; 3366b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3367b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3368b3d05147SEric Dumazet * to avoid false sharing. 3369b3d05147SEric Dumazet */ 3370b3d05147SEric Dumazet break; 3371b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3372ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3373ca6fb065SEric Dumazet * cpu might call us concurrently. 3374ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3375ca6fb065SEric Dumazet */ 3376ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3377b3d05147SEric Dumazet break; 3378ca6fb065SEric Dumazet } 33794aea39c1SEric Dumazet skb_dst_set(skb, dst); 33801da177e4SLinus Torvalds 33813541f9e8SEric Dumazet mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3382f5fff5dcSTom Quetchenbach 338333ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 3384a842fe14SEric Dumazet now = tcp_clock_ns(); 33858b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 33868b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 3387200ecef6SEric Dumazet skb->skb_mstamp_ns = cookie_init_timestamp(req, now); 33888b5f12d0SFlorian Westphal else 33898b5f12d0SFlorian Westphal #endif 33909e450c1eSYuchung Cheng { 3391a842fe14SEric Dumazet skb->skb_mstamp_ns = now; 33929e450c1eSYuchung Cheng if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */ 33939e450c1eSYuchung Cheng tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb); 33949e450c1eSYuchung Cheng } 339580f03e27SEric Dumazet 339680f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 339780f03e27SEric Dumazet rcu_read_lock(); 3398fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 339980f03e27SEric Dumazet #endif 340058d607d3SEric Dumazet skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); 340160e2a778SUrsula Braun tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, 3402e114e1e8SEric Dumazet foc, synack_type) + sizeof(*th); 340333ad798cSAdam Langley 3404aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3405aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 34061da177e4SLinus Torvalds 3407ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 34081da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 34091da177e4SLinus Torvalds th->syn = 1; 34101da177e4SLinus Torvalds th->ack = 1; 34116ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3412b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3413634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3414e05a90ecSJamal Hadi Salim skb->mark = ireq->ir_mark; 34153b117750SEric Dumazet skb->ip_summed = CHECKSUM_PARTIAL; 34163b117750SEric Dumazet th->seq = htonl(tcp_rsk(req)->snt_isn); 34178336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 34188336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 34191da177e4SLinus Torvalds 34201da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3421ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 34225d062de7SEric Dumazet tcp_options_write((__be32 *)(th + 1), NULL, &opts); 34231da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 342490bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3425cfb6eeb4SYOSHIFUJI Hideaki 3426cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3427cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 342880f03e27SEric Dumazet if (md5) 3429bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 343039f8e58eSEric Dumazet md5, req_to_sk(req), skb); 343180f03e27SEric Dumazet rcu_read_unlock(); 3432cfb6eeb4SYOSHIFUJI Hideaki #endif 3433cfb6eeb4SYOSHIFUJI Hideaki 3434a842fe14SEric Dumazet skb->skb_mstamp_ns = now; 3435a842fe14SEric Dumazet tcp_add_tx_delay(skb, tp); 3436a842fe14SEric Dumazet 34371da177e4SLinus Torvalds return skb; 34381da177e4SLinus Torvalds } 34394bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 34401da177e4SLinus Torvalds 344181164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 344281164413SDaniel Borkmann { 344381164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 344481164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 344581164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 344681164413SDaniel Borkmann 344781164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 344881164413SDaniel Borkmann return; 344981164413SDaniel Borkmann 345081164413SDaniel Borkmann rcu_read_lock(); 345181164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 34520baf26b0SMartin KaFai Lau if (likely(ca && bpf_try_module_get(ca, ca->owner))) { 34530baf26b0SMartin KaFai Lau bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner); 345481164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 345581164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 345681164413SDaniel Borkmann } 345781164413SDaniel Borkmann rcu_read_unlock(); 345881164413SDaniel Borkmann } 345981164413SDaniel Borkmann 346067edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3461f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 34621da177e4SLinus Torvalds { 3463cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 34641da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34651da177e4SLinus Torvalds __u8 rcv_wscale; 346613d3b1ebSLawrence Brakmo u32 rcv_wnd; 34671da177e4SLinus Torvalds 34681da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 34691da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 34701da177e4SLinus Torvalds */ 34715d2ed052SEric Dumazet tp->tcp_header_len = sizeof(struct tcphdr); 34725d2ed052SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_timestamps) 34735d2ed052SEric Dumazet tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; 34741da177e4SLinus Torvalds 3475cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 347600db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3477cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3478cfb6eeb4SYOSHIFUJI Hideaki #endif 3479cfb6eeb4SYOSHIFUJI Hideaki 34801da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 34811da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 34821da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 34831da177e4SLinus Torvalds tp->max_window = 0; 34845d424d5aSJohn Heffner tcp_mtup_init(sk); 34851da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 34861da177e4SLinus Torvalds 348781164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 348881164413SDaniel Borkmann 34891da177e4SLinus Torvalds if (!tp->window_clamp) 34901da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 34913541f9e8SEric Dumazet tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3492f5fff5dcSTom Quetchenbach 34931da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 34941da177e4SLinus Torvalds 3495e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3496e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3497e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3498e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3499e88c64f0SHagen Paul Pfeifer 350013d3b1ebSLawrence Brakmo rcv_wnd = tcp_rwnd_init_bpf(sk); 350113d3b1ebSLawrence Brakmo if (rcv_wnd == 0) 350213d3b1ebSLawrence Brakmo rcv_wnd = dst_metric(dst, RTAX_INITRWND); 350313d3b1ebSLawrence Brakmo 3504ceef9ab6SEric Dumazet tcp_select_initial_window(sk, tcp_full_space(sk), 35051da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 35061da177e4SLinus Torvalds &tp->rcv_wnd, 35071da177e4SLinus Torvalds &tp->window_clamp, 35089bb37ef0SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_window_scaling, 350931d12926Slaurent chavey &rcv_wscale, 351013d3b1ebSLawrence Brakmo rcv_wnd); 35111da177e4SLinus Torvalds 35121da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 35131da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 35141da177e4SLinus Torvalds 35151da177e4SLinus Torvalds sk->sk_err = 0; 35161da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 35171da177e4SLinus Torvalds tp->snd_wnd = 0; 3518ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 35197f582b24SEric Dumazet tcp_write_queue_purge(sk); 35201da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 35211da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 352233f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3523e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->write_seq); 3524ee995283SPavel Emelyanov 3525ee995283SPavel Emelyanov if (likely(!tp->repair)) 35261da177e4SLinus Torvalds tp->rcv_nxt = 0; 3527c7781a6eSAndrew Vagin else 352870eabf0eSEric Dumazet tp->rcv_tstamp = tcp_jiffies32; 3529ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 35307db48e98SEric Dumazet WRITE_ONCE(tp->copied_seq, tp->rcv_nxt); 35311da177e4SLinus Torvalds 35328550f328SLawrence Brakmo inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); 3533463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 35341da177e4SLinus Torvalds tcp_clear_retrans(tp); 35351da177e4SLinus Torvalds } 35361da177e4SLinus Torvalds 3537783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3538783237e8SYuchung Cheng { 3539783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3540783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3541783237e8SYuchung Cheng 3542783237e8SYuchung Cheng tcb->end_seq += skb->len; 3543f4a775d1SEric Dumazet __skb_header_release(skb); 3544ab4e846aSEric Dumazet sk_wmem_queued_add(sk, skb->truesize); 3545783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 35460f317464SEric Dumazet WRITE_ONCE(tp->write_seq, tcb->end_seq); 3547783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3548783237e8SYuchung Cheng } 3549783237e8SYuchung Cheng 3550783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3551783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3552783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3553783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3554783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3555783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3556783237e8SYuchung Cheng */ 3557783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3558783237e8SYuchung Cheng { 3559783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3560783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 3561065263f4SWei Wang int space, err = 0; 3562355a901eSEric Dumazet struct sk_buff *syn_data; 3563783237e8SYuchung Cheng 356467da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3565065263f4SWei Wang if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) 3566783237e8SYuchung Cheng goto fallback; 3567783237e8SYuchung Cheng 3568783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3569783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3570783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3571783237e8SYuchung Cheng */ 35723541f9e8SEric Dumazet tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); 35733541f9e8SEric Dumazet 35741b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3575783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3576783237e8SYuchung Cheng 3577f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3578f5ddcbbbSEric Dumazet 3579f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3580f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3581f5ddcbbbSEric Dumazet 3582eb934478SEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); 3583355a901eSEric Dumazet if (!syn_data) 3584783237e8SYuchung Cheng goto fallback; 3585355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3586355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 358707e100f9SEric Dumazet if (space) { 358807e100f9SEric Dumazet int copied = copy_from_iter(skb_put(syn_data, space), space, 358957be5bdaSAl Viro &fo->data->msg_iter); 359057be5bdaSAl Viro if (unlikely(!copied)) { 3591ba233b34SEric Dumazet tcp_skb_tsorted_anchor_cleanup(syn_data); 3592355a901eSEric Dumazet kfree_skb(syn_data); 3593783237e8SYuchung Cheng goto fallback; 3594783237e8SYuchung Cheng } 359557be5bdaSAl Viro if (copied != space) { 359657be5bdaSAl Viro skb_trim(syn_data, copied); 359757be5bdaSAl Viro space = copied; 359857be5bdaSAl Viro } 3599f859a448SWillem de Bruijn skb_zcopy_set(syn_data, fo->uarg, NULL); 360007e100f9SEric Dumazet } 3601355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3602355a901eSEric Dumazet if (space == fo->size) 3603355a901eSEric Dumazet fo->data = NULL; 3604355a901eSEric Dumazet fo->copied = space; 3605783237e8SYuchung Cheng 3606355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 36070f87230dSFrancis Yan if (syn_data->len) 36080f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3609355a901eSEric Dumazet 3610355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3611355a901eSEric Dumazet 3612d3edd06eSEric Dumazet syn->skb_mstamp_ns = syn_data->skb_mstamp_ns; 3613355a901eSEric Dumazet 3614355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3615355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3616355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3617355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3618431a9124SEric Dumazet */ 3619355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3620355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3621355a901eSEric Dumazet if (!err) { 362267da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 362375c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); 3624f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3625783237e8SYuchung Cheng goto done; 3626783237e8SYuchung Cheng } 3627783237e8SYuchung Cheng 362875c119afSEric Dumazet /* data was not sent, put it in write_queue */ 362975c119afSEric Dumazet __skb_queue_tail(&sk->sk_write_queue, syn_data); 3630b5b7db8dSEric Dumazet tp->packets_out -= tcp_skb_pcount(syn_data); 3631b5b7db8dSEric Dumazet 3632783237e8SYuchung Cheng fallback: 3633783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3634783237e8SYuchung Cheng if (fo->cookie.len > 0) 3635783237e8SYuchung Cheng fo->cookie.len = 0; 3636783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3637783237e8SYuchung Cheng if (err) 3638783237e8SYuchung Cheng tp->syn_fastopen = 0; 3639783237e8SYuchung Cheng done: 3640783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3641783237e8SYuchung Cheng return err; 3642783237e8SYuchung Cheng } 3643783237e8SYuchung Cheng 364467edfef7SAndi Kleen /* Build a SYN and send it off. */ 36451da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 36461da177e4SLinus Torvalds { 36471da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 36481da177e4SLinus Torvalds struct sk_buff *buff; 3649ee586811SEric Paris int err; 36501da177e4SLinus Torvalds 3651de525be2SLawrence Brakmo tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); 36528ba60924SEric Dumazet 36538ba60924SEric Dumazet if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 36548ba60924SEric Dumazet return -EHOSTUNREACH; /* Routing failure or similar. */ 36558ba60924SEric Dumazet 36561da177e4SLinus Torvalds tcp_connect_init(sk); 36571da177e4SLinus Torvalds 36582b916477SAndrey Vagin if (unlikely(tp->repair)) { 36592b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 36602b916477SAndrey Vagin return 0; 36612b916477SAndrey Vagin } 36622b916477SAndrey Vagin 3663eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); 3664355a901eSEric Dumazet if (unlikely(!buff)) 36651da177e4SLinus Torvalds return -ENOBUFS; 36661da177e4SLinus Torvalds 3667a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 36689a568de4SEric Dumazet tcp_mstamp_refresh(tp); 36699a568de4SEric Dumazet tp->retrans_stamp = tcp_time_stamp(tp); 3670783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3671735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 367275c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 36731da177e4SLinus Torvalds 3674783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3675783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3676783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3677ee586811SEric Paris if (err == -ECONNREFUSED) 3678ee586811SEric Paris return err; 3679bd37a088SWei Yongjun 3680bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3681bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3682bd37a088SWei Yongjun */ 3683e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->write_seq); 3684bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 3685b5b7db8dSEric Dumazet buff = tcp_send_head(sk); 3686b5b7db8dSEric Dumazet if (unlikely(buff)) { 3687e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(buff)->seq); 3688b5b7db8dSEric Dumazet tp->pushed_seq = TCP_SKB_CB(buff)->seq; 3689b5b7db8dSEric Dumazet } 369081cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 36911da177e4SLinus Torvalds 36921da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 36933f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 36943f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 36951da177e4SLinus Torvalds return 0; 36961da177e4SLinus Torvalds } 36974bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 36981da177e4SLinus Torvalds 36991da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 37001da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 37011da177e4SLinus Torvalds * for details. 37021da177e4SLinus Torvalds */ 37031da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 37041da177e4SLinus Torvalds { 3705463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3706463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 37071da177e4SLinus Torvalds unsigned long timeout; 37081da177e4SLinus Torvalds 37091da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3710463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 37111da177e4SLinus Torvalds int max_ato = HZ / 2; 37121da177e4SLinus Torvalds 371331954cd8SWei Wang if (inet_csk_in_pingpong_mode(sk) || 3714056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 37151da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 37161da177e4SLinus Torvalds 37171da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 37181da177e4SLinus Torvalds 37191da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3720463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 37211da177e4SLinus Torvalds * directly. 37221da177e4SLinus Torvalds */ 3723740b0f18SEric Dumazet if (tp->srtt_us) { 3724740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3725740b0f18SEric Dumazet TCP_DELACK_MIN); 37261da177e4SLinus Torvalds 37271da177e4SLinus Torvalds if (rtt < max_ato) 37281da177e4SLinus Torvalds max_ato = rtt; 37291da177e4SLinus Torvalds } 37301da177e4SLinus Torvalds 37311da177e4SLinus Torvalds ato = min(ato, max_ato); 37321da177e4SLinus Torvalds } 37331da177e4SLinus Torvalds 37341da177e4SLinus Torvalds /* Stay within the limit we were given */ 37351da177e4SLinus Torvalds timeout = jiffies + ato; 37361da177e4SLinus Torvalds 37371da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3738463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 37391da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 37401da177e4SLinus Torvalds * send ACK now. 37411da177e4SLinus Torvalds */ 3742463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3743463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 37441da177e4SLinus Torvalds tcp_send_ack(sk); 37451da177e4SLinus Torvalds return; 37461da177e4SLinus Torvalds } 37471da177e4SLinus Torvalds 3748463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3749463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 37501da177e4SLinus Torvalds } 3751463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3752463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3753463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 37541da177e4SLinus Torvalds } 37551da177e4SLinus Torvalds 37561da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 37572987babbSYuchung Cheng void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) 37581da177e4SLinus Torvalds { 37591da177e4SLinus Torvalds struct sk_buff *buff; 37601da177e4SLinus Torvalds 3761058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3762058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3763058dc334SIlpo Järvinen return; 3764058dc334SIlpo Järvinen 37651da177e4SLinus Torvalds /* We are not putting this on the write queue, so 37661da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 37671da177e4SLinus Torvalds * sock. 37681da177e4SLinus Torvalds */ 37697450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 37707450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 37717450aaf6SEric Dumazet if (unlikely(!buff)) { 3772463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3773463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 37743f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 37753f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 37761da177e4SLinus Torvalds return; 37771da177e4SLinus Torvalds } 37781da177e4SLinus Torvalds 37791da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 37801da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3781a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 37821da177e4SLinus Torvalds 378398781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 378498781965SEric Dumazet * too much. 378598781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 378698781965SEric Dumazet */ 378798781965SEric Dumazet skb_set_tcp_pure_ack(buff); 378898781965SEric Dumazet 37891da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 37902987babbSYuchung Cheng __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); 37911da177e4SLinus Torvalds } 379227cde44aSYuchung Cheng EXPORT_SYMBOL_GPL(__tcp_send_ack); 37932987babbSYuchung Cheng 37942987babbSYuchung Cheng void tcp_send_ack(struct sock *sk) 37952987babbSYuchung Cheng { 37962987babbSYuchung Cheng __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); 37971da177e4SLinus Torvalds } 37981da177e4SLinus Torvalds 37991da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 38001da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 38011da177e4SLinus Torvalds * 38021da177e4SLinus Torvalds * Question: what should we make while urgent mode? 38031da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 38041da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 38051da177e4SLinus Torvalds * 38061da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 38071da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 38081da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 38091da177e4SLinus Torvalds */ 3810e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 38111da177e4SLinus Torvalds { 38121da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 38131da177e4SLinus Torvalds struct sk_buff *skb; 38141da177e4SLinus Torvalds 38151da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 38167450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 38177450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 381851456b29SIan Morris if (!skb) 38191da177e4SLinus Torvalds return -1; 38201da177e4SLinus Torvalds 38211da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 38221da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 38231da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 38241da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 38251da177e4SLinus Torvalds * send it. 38261da177e4SLinus Torvalds */ 3827a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 3828e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 38297450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 38301da177e4SLinus Torvalds } 38311da177e4SLinus Torvalds 3832385e2070SEric Dumazet /* Called from setsockopt( ... TCP_REPAIR ) */ 3833ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3834ee995283SPavel Emelyanov { 3835ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3836ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 38379a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 3838e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 3839ee995283SPavel Emelyanov } 3840ee995283SPavel Emelyanov } 3841ee995283SPavel Emelyanov 384267edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 3843e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 38441da177e4SLinus Torvalds { 38451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 38461da177e4SLinus Torvalds struct sk_buff *skb; 38471da177e4SLinus Torvalds 3848058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3849058dc334SIlpo Järvinen return -1; 3850058dc334SIlpo Järvinen 385100db4124SIan Morris skb = tcp_send_head(sk); 385200db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 38531da177e4SLinus Torvalds int err; 38540c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 385590840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 38561da177e4SLinus Torvalds 38571da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 38581da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 38591da177e4SLinus Torvalds 38601da177e4SLinus Torvalds /* We are probing the opening of a window 38611da177e4SLinus Torvalds * but the window size is != 0 38621da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 38631da177e4SLinus Torvalds */ 38641da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 38651da177e4SLinus Torvalds skb->len > mss) { 38661da177e4SLinus Torvalds seg_size = min(seg_size, mss); 38674de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 386875c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, 386975c119afSEric Dumazet skb, seg_size, mss, GFP_ATOMIC)) 38701da177e4SLinus Torvalds return -1; 38711da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 38725bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 38731da177e4SLinus Torvalds 38744de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3875dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 387666f5fe62SIlpo Järvinen if (!err) 387766f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 38781da177e4SLinus Torvalds return err; 38791da177e4SLinus Torvalds } else { 388033f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 3881e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 3882e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 38831da177e4SLinus Torvalds } 38841da177e4SLinus Torvalds } 38851da177e4SLinus Torvalds 38861da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 38871da177e4SLinus Torvalds * a partial packet else a zero probe. 38881da177e4SLinus Torvalds */ 38891da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 38901da177e4SLinus Torvalds { 3891463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 38921da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3893c6214a97SNikolay Borisov struct net *net = sock_net(sk); 3894c1d5674fSYuchung Cheng unsigned long timeout; 38951da177e4SLinus Torvalds int err; 38961da177e4SLinus Torvalds 3897e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 38981da177e4SLinus Torvalds 389975c119afSEric Dumazet if (tp->packets_out || tcp_write_queue_empty(sk)) { 39001da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 39016687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3902463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 39031da177e4SLinus Torvalds return; 39041da177e4SLinus Torvalds } 39051da177e4SLinus Torvalds 3906c1d5674fSYuchung Cheng icsk->icsk_probes_out++; 39071da177e4SLinus Torvalds if (err <= 0) { 3908c6214a97SNikolay Borisov if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) 3909463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 3910c1d5674fSYuchung Cheng timeout = tcp_probe0_when(sk, TCP_RTO_MAX); 39111da177e4SLinus Torvalds } else { 39121da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 3913c1d5674fSYuchung Cheng * Let senders fight for local resources conservatively. 39141da177e4SLinus Torvalds */ 3915c1d5674fSYuchung Cheng timeout = TCP_RESOURCE_PROBE_INTERVAL; 39161da177e4SLinus Torvalds } 39178dc242adSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX); 39181da177e4SLinus Torvalds } 39195db92c99SOctavian Purdila 3920ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 39215db92c99SOctavian Purdila { 39225db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 39235db92c99SOctavian Purdila struct flowi fl; 39245db92c99SOctavian Purdila int res; 39255db92c99SOctavian Purdila 392658d607d3SEric Dumazet tcp_rsk(req)->txhash = net_tx_rndhash(); 3927b3d05147SEric Dumazet res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); 39285db92c99SOctavian Purdila if (!res) { 392990bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 393002a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 39317e32b443SYuchung Cheng if (unlikely(tcp_passive_fastopen(sk))) 39327e32b443SYuchung Cheng tcp_sk(sk)->total_retrans++; 3933cf34ce3dSSong Liu trace_tcp_retransmit_synack(sk, req); 39345db92c99SOctavian Purdila } 39355db92c99SOctavian Purdila return res; 39365db92c99SOctavian Purdila } 39375db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3938