11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 31da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 41da177e4SLinus Torvalds * interface as the means of communication with the user level. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 71da177e4SLinus Torvalds * 802c30a84SJesper Juhl * Authors: Ross Biro 91da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 101da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 111da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 121da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 131da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 141da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 151da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 161da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 171da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 181da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds /* 221da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 231da177e4SLinus Torvalds * : Fragmentation on mtu decrease 241da177e4SLinus Torvalds * : Segment collapse on retransmit 251da177e4SLinus Torvalds * : AF independence 261da177e4SLinus Torvalds * 271da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 281da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 291da177e4SLinus Torvalds * during syn/ack processing. 301da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 311da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 321da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 331da177e4SLinus Torvalds * J Hadi Salim : ECN support 341da177e4SLinus Torvalds * 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds 3791df42beSJoe Perches #define pr_fmt(fmt) "TCP: " fmt 3891df42beSJoe Perches 391da177e4SLinus Torvalds #include <net/tcp.h> 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds #include <linux/compiler.h> 425a0e3ad6STejun Heo #include <linux/gfp.h> 431da177e4SLinus Torvalds #include <linux/module.h> 4460e2a778SUrsula Braun #include <linux/static_key.h> 451da177e4SLinus Torvalds 46e086101bSCong Wang #include <trace/events/tcp.h> 4735089bb2SDavid S. Miller 489799ccb0SEric Dumazet /* Refresh clocks of a TCP socket, 499799ccb0SEric Dumazet * ensuring monotically increasing values. 509799ccb0SEric Dumazet */ 519799ccb0SEric Dumazet void tcp_mstamp_refresh(struct tcp_sock *tp) 529799ccb0SEric Dumazet { 539799ccb0SEric Dumazet u64 val = tcp_clock_ns(); 549799ccb0SEric Dumazet 559799ccb0SEric Dumazet /* departure time for next data packet */ 569799ccb0SEric Dumazet if (val > tp->tcp_wstamp_ns) 579799ccb0SEric Dumazet tp->tcp_wstamp_ns = val; 589799ccb0SEric Dumazet 599799ccb0SEric Dumazet val = div_u64(val, NSEC_PER_USEC); 609799ccb0SEric Dumazet if (val > tp->tcp_mstamp) 619799ccb0SEric Dumazet tp->tcp_mstamp = val; 629799ccb0SEric Dumazet } 639799ccb0SEric Dumazet 6446d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6546d3ceabSEric Dumazet int push_one, gfp_t gfp); 66519855c5SWilliam Allen Simpson 6767edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 6875c119afSEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) 696ff03ac3SIlpo Järvinen { 706ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 716ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7266f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 739e412ba7SIlpo Järvinen 741da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 758512430eSIlpo Järvinen 7675c119afSEric Dumazet __skb_unlink(skb, &sk->sk_write_queue); 7775c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); 7875c119afSEric Dumazet 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 1691da177e4SLinus Torvalds tp->lsndtime = now; 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /* If it is a reply for ato after last received 1721da177e4SLinus Torvalds * packet, enter pingpong mode. 1731da177e4SLinus Torvalds */ 1742251ae46SJon Maxwell if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 175463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1761da177e4SLinus Torvalds } 1771da177e4SLinus Torvalds 17867edfef7SAndi Kleen /* Account for an ACK we sent. */ 17927cde44aSYuchung Cheng static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, 18027cde44aSYuchung Cheng u32 rcv_nxt) 1811da177e4SLinus Torvalds { 1825d9f4262SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1835d9f4262SEric Dumazet 1845d9f4262SEric Dumazet if (unlikely(tp->compressed_ack)) { 185200d95f4SEric Dumazet NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, 186200d95f4SEric Dumazet tp->compressed_ack); 1875d9f4262SEric Dumazet tp->compressed_ack = 0; 1885d9f4262SEric Dumazet if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) 1895d9f4262SEric Dumazet __sock_put(sk); 1905d9f4262SEric Dumazet } 19127cde44aSYuchung Cheng 19227cde44aSYuchung Cheng if (unlikely(rcv_nxt != tp->rcv_nxt)) 19327cde44aSYuchung Cheng return; /* Special ACK sent by DCTCP to reflect ECN */ 194463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 195463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1961da177e4SLinus Torvalds } 1971da177e4SLinus Torvalds 19885f16525SYuchung Cheng 19985f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 20085f16525SYuchung Cheng { 20185f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 2029ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 20385f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 20485f16525SYuchung Cheng * limit when mss is larger than 1460. 20585f16525SYuchung Cheng */ 20685f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 20785f16525SYuchung Cheng 20885f16525SYuchung Cheng if (mss > 1460) 20985f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 21085f16525SYuchung Cheng return init_rwnd; 21185f16525SYuchung Cheng } 21285f16525SYuchung Cheng 2131da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2141da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2151da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2161da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2171da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2181da177e4SLinus Torvalds * This MUST be enforced by all callers. 2191da177e4SLinus Torvalds */ 220ceef9ab6SEric Dumazet void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, 2211da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 22231d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 22331d12926Slaurent chavey __u32 init_rcv_wnd) 2241da177e4SLinus Torvalds { 2251da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2281da177e4SLinus Torvalds if (*window_clamp == 0) 229589c49cbSGao Feng (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); 2301da177e4SLinus Torvalds space = min(*window_clamp, space); 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2331da177e4SLinus Torvalds if (space > mss) 234589c49cbSGao Feng space = rounddown(space, mss); 2351da177e4SLinus Torvalds 2361da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 23715d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 23815d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 23915d99e02SRick Jones * we will truncate our initial window offering to 32K-1 24015d99e02SRick Jones * unless the remote has sent us a window scaling option, 24115d99e02SRick Jones * which we interpret as a sign the remote TCP is not 24215d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2431da177e4SLinus Torvalds */ 244ceef9ab6SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) 2451da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 24615d99e02SRick Jones else 24715d99e02SRick Jones (*rcv_wnd) = space; 24815d99e02SRick Jones 2491da177e4SLinus Torvalds (*rcv_wscale) = 0; 2501da177e4SLinus Torvalds if (wscale_ok) { 251589c49cbSGao Feng /* Set window scaling on max possible window */ 252356d1833SEric Dumazet space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]); 253f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_rmem_max); 254316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 255589c49cbSGao Feng while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) { 2561da177e4SLinus Torvalds space >>= 1; 2571da177e4SLinus Torvalds (*rcv_wscale)++; 2581da177e4SLinus Torvalds } 2591da177e4SLinus Torvalds } 2601da177e4SLinus Torvalds 26185f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 26285f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 263b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2641da177e4SLinus Torvalds 2651da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 266589c49cbSGao Feng (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); 2671da177e4SLinus Torvalds } 2684bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2691da177e4SLinus Torvalds 2701da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2711da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2721da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2731da177e4SLinus Torvalds * frame. 2741da177e4SLinus Torvalds */ 27540efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2761da177e4SLinus Torvalds { 2771da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2788e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2791da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2801da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2811da177e4SLinus Torvalds 2821da177e4SLinus Torvalds /* Never shrink the offered window */ 2831da177e4SLinus Torvalds if (new_win < cur_win) { 2841da177e4SLinus Torvalds /* Danger Will Robinson! 2851da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2861da177e4SLinus Torvalds * we will not be able to advertise a zero 2871da177e4SLinus Torvalds * window in time. --DaveM 2881da177e4SLinus Torvalds * 2891da177e4SLinus Torvalds * Relax Will Robinson. 2901da177e4SLinus Torvalds */ 2918e165e20SFlorian Westphal if (new_win == 0) 2928e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2938e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 294607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2971da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 3001da177e4SLinus Torvalds * scaled window. 3011da177e4SLinus Torvalds */ 302ceef9ab6SEric Dumazet if (!tp->rx_opt.rcv_wscale && 303ceef9ab6SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) 3041da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 3051da177e4SLinus Torvalds else 3061da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds /* RFC1323 scaling applied */ 3091da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 3101da177e4SLinus Torvalds 31131770e34SFlorian Westphal /* If we advertise zero window, disable fast path. */ 3128e165e20SFlorian Westphal if (new_win == 0) { 31331770e34SFlorian Westphal tp->pred_flags = 0; 3148e165e20SFlorian Westphal if (old_win) 3158e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3168e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3178e165e20SFlorian Westphal } else if (old_win == 0) { 3188e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3198e165e20SFlorian Westphal } 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds return new_win; 3221da177e4SLinus Torvalds } 3231da177e4SLinus Torvalds 32467edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 325735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 326bdf1ee5dSIlpo Järvinen { 32730e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 32830e502a3SDaniel Borkmann 3294de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 330bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3314de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 33291b5b21cSLawrence Brakmo else if (tcp_ca_needs_ecn(sk) || 33391b5b21cSLawrence Brakmo tcp_bpf_ca_needs_ecn(sk)) 33430e502a3SDaniel Borkmann INET_ECN_xmit(sk); 335bdf1ee5dSIlpo Järvinen } 336bdf1ee5dSIlpo Järvinen 33767edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 338735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 339bdf1ee5dSIlpo Järvinen { 340bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 34191b5b21cSLawrence Brakmo bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); 342f7b3bec6SFlorian Westphal bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || 34391b5b21cSLawrence Brakmo tcp_ca_needs_ecn(sk) || bpf_needs_ecn; 344f7b3bec6SFlorian Westphal 345f7b3bec6SFlorian Westphal if (!use_ecn) { 346f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 347f7b3bec6SFlorian Westphal 348f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 349f7b3bec6SFlorian Westphal use_ecn = true; 350f7b3bec6SFlorian Westphal } 351bdf1ee5dSIlpo Järvinen 352bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 353f7b3bec6SFlorian Westphal 354f7b3bec6SFlorian Westphal if (use_ecn) { 3554de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 356bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 35791b5b21cSLawrence Brakmo if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) 35830e502a3SDaniel Borkmann INET_ECN_xmit(sk); 359bdf1ee5dSIlpo Järvinen } 360bdf1ee5dSIlpo Järvinen } 361bdf1ee5dSIlpo Järvinen 36249213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 36349213555SDaniel Borkmann { 36449213555SDaniel Borkmann if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) 36549213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 36649213555SDaniel Borkmann * SYN ACK is ultimatively being received. 36749213555SDaniel Borkmann */ 36849213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 36949213555SDaniel Borkmann } 37049213555SDaniel Borkmann 371735d3831SFlorian Westphal static void 3726ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 373bdf1ee5dSIlpo Järvinen { 3746ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 375bdf1ee5dSIlpo Järvinen th->ece = 1; 376bdf1ee5dSIlpo Järvinen } 377bdf1ee5dSIlpo Järvinen 37867edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 37967edfef7SAndi Kleen * be sent. 38067edfef7SAndi Kleen */ 381735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 382ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 383bdf1ee5dSIlpo Järvinen { 384bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 385bdf1ee5dSIlpo Järvinen 386bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 387bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 388bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 389bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 390bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 391bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 392bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 393ea1627c2SEric Dumazet th->cwr = 1; 394bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 395bdf1ee5dSIlpo Järvinen } 39630e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 397bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 398bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 399bdf1ee5dSIlpo Järvinen } 400bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 401ea1627c2SEric Dumazet th->ece = 1; 402bdf1ee5dSIlpo Järvinen } 403bdf1ee5dSIlpo Järvinen } 404bdf1ee5dSIlpo Järvinen 405e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 406e870a8efSIlpo Järvinen * auto increment end seqno. 407e870a8efSIlpo Järvinen */ 408e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 409e870a8efSIlpo Järvinen { 4102e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 411e870a8efSIlpo Järvinen 4124de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 413e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 414e870a8efSIlpo Järvinen 415cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 416e870a8efSIlpo Järvinen 417e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 418a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 419e870a8efSIlpo Järvinen seq++; 420e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 421e870a8efSIlpo Järvinen } 422e870a8efSIlpo Järvinen 423a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 42433f5f57eSIlpo Järvinen { 42533f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 42633f5f57eSIlpo Järvinen } 42733f5f57eSIlpo Järvinen 42833ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 42933ad798cSAdam Langley #define OPTION_TS (1 << 1) 43033ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 43189e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4322100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 43360e2a778SUrsula Braun #define OPTION_SMC (1 << 9) 43460e2a778SUrsula Braun 43560e2a778SUrsula Braun static void smc_options_write(__be32 *ptr, u16 *options) 43660e2a778SUrsula Braun { 43760e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 43860e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 43960e2a778SUrsula Braun if (unlikely(OPTION_SMC & *options)) { 44060e2a778SUrsula Braun *ptr++ = htonl((TCPOPT_NOP << 24) | 44160e2a778SUrsula Braun (TCPOPT_NOP << 16) | 44260e2a778SUrsula Braun (TCPOPT_EXP << 8) | 44360e2a778SUrsula Braun (TCPOLEN_EXP_SMC_BASE)); 44460e2a778SUrsula Braun *ptr++ = htonl(TCPOPT_SMC_MAGIC); 44560e2a778SUrsula Braun } 44660e2a778SUrsula Braun } 44760e2a778SUrsula Braun #endif 44860e2a778SUrsula Braun } 44933ad798cSAdam Langley 45033ad798cSAdam Langley struct tcp_out_options { 4512100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4522100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 45333ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 45433ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 455bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 456bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4572100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4582100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 45933ad798cSAdam Langley }; 46033ad798cSAdam Langley 46167edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 46267edfef7SAndi Kleen * 46367edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 464fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 465fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4668e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 467fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 468fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 469fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 470fd6149d3SIlpo Järvinen * 471fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 472fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 473fd6149d3SIlpo Järvinen */ 47433ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 475bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 476bd0388aeSWilliam Allen Simpson { 4772100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 478bd0388aeSWilliam Allen Simpson 479bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4801a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4811a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 482bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 483bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 48433ad798cSAdam Langley ptr += 4; 48533ad798cSAdam Langley } 48633ad798cSAdam Langley 487fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 488fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 489fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 490fd6149d3SIlpo Järvinen opts->mss); 491fd6149d3SIlpo Järvinen } 492fd6149d3SIlpo Järvinen 493bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 494bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 49533ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 49633ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 49733ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 49833ad798cSAdam Langley TCPOLEN_TIMESTAMP); 499bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 50033ad798cSAdam Langley } else { 501496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 50240efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 50340efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 50440efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 50540efc6faSStephen Hemminger } 50633ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 50733ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 50833ad798cSAdam Langley } 50933ad798cSAdam Langley 510bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 51133ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 51233ad798cSAdam Langley (TCPOPT_NOP << 16) | 51333ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 51433ad798cSAdam Langley TCPOLEN_SACK_PERM); 51533ad798cSAdam Langley } 51633ad798cSAdam Langley 517bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 51833ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 51933ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 52033ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 52133ad798cSAdam Langley opts->ws); 52233ad798cSAdam Langley } 52333ad798cSAdam Langley 52433ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 52533ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 52633ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 52740efc6faSStephen Hemminger int this_sack; 52840efc6faSStephen Hemminger 52940efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 53040efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 53140efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 53233ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 53340efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5342de979bdSStephen Hemminger 53533ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 53633ad798cSAdam Langley ++this_sack) { 53740efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 53840efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 53940efc6faSStephen Hemminger } 5402de979bdSStephen Hemminger 54140efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 54240efc6faSStephen Hemminger } 5432100c8d2SYuchung Cheng 5442100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5452100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 5467f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 5477f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 5482100c8d2SYuchung Cheng 5497f9b838bSDaniel Lee if (foc->exp) { 5507f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 5517f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 5522100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 5537f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 5547f9b838bSDaniel Lee } else { 5557f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 5567f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 5577f9b838bSDaniel Lee *p++ = len; 5582100c8d2SYuchung Cheng } 5597f9b838bSDaniel Lee 5607f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 5617f9b838bSDaniel Lee if ((len & 3) == 2) { 5627f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 5637f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 5647f9b838bSDaniel Lee } 5657f9b838bSDaniel Lee ptr += (len + 3) >> 2; 5662100c8d2SYuchung Cheng } 56760e2a778SUrsula Braun 56860e2a778SUrsula Braun smc_options_write(ptr, &options); 56960e2a778SUrsula Braun } 57060e2a778SUrsula Braun 57160e2a778SUrsula Braun static void smc_set_option(const struct tcp_sock *tp, 57260e2a778SUrsula Braun struct tcp_out_options *opts, 57360e2a778SUrsula Braun unsigned int *remaining) 57460e2a778SUrsula Braun { 57560e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 57660e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 57760e2a778SUrsula Braun if (tp->syn_smc) { 57860e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 57960e2a778SUrsula Braun opts->options |= OPTION_SMC; 58060e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 58160e2a778SUrsula Braun } 58260e2a778SUrsula Braun } 58360e2a778SUrsula Braun } 58460e2a778SUrsula Braun #endif 58560e2a778SUrsula Braun } 58660e2a778SUrsula Braun 58760e2a778SUrsula Braun static void smc_set_option_cond(const struct tcp_sock *tp, 58860e2a778SUrsula Braun const struct inet_request_sock *ireq, 58960e2a778SUrsula Braun struct tcp_out_options *opts, 59060e2a778SUrsula Braun unsigned int *remaining) 59160e2a778SUrsula Braun { 59260e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 59360e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 59460e2a778SUrsula Braun if (tp->syn_smc && ireq->smc_ok) { 59560e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 59660e2a778SUrsula Braun opts->options |= OPTION_SMC; 59760e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 59860e2a778SUrsula Braun } 59960e2a778SUrsula Braun } 60060e2a778SUrsula Braun } 60160e2a778SUrsula Braun #endif 60240efc6faSStephen Hemminger } 60340efc6faSStephen Hemminger 60467edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 60567edfef7SAndi Kleen * network wire format yet. 60667edfef7SAndi Kleen */ 60795c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 60833ad798cSAdam Langley struct tcp_out_options *opts, 609cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 610cf533ea5SEric Dumazet { 61133ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 61295c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 613783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 61433ad798cSAdam Langley 6158c2320e8SEric Dumazet *md5 = NULL; 616cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 6178c2320e8SEric Dumazet if (unlikely(rcu_access_pointer(tp->md5sig_info))) { 61833ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 61933ad798cSAdam Langley if (*md5) { 62033ad798cSAdam Langley opts->options |= OPTION_MD5; 621bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 622cfb6eeb4SYOSHIFUJI Hideaki } 6238c2320e8SEric Dumazet } 624cfb6eeb4SYOSHIFUJI Hideaki #endif 62533ad798cSAdam Langley 62633ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 62733ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 62833ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 62933ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 63033ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 63133ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 63233ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 63333ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 63433ad798cSAdam Langley * going out. */ 63533ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 636bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 63733ad798cSAdam Langley 6385d2ed052SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) { 63933ad798cSAdam Langley opts->options |= OPTION_TS; 6407faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 64133ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 642bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 64333ad798cSAdam Langley } 6449bb37ef0SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) { 64533ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 64689e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 647bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 64833ad798cSAdam Langley } 649f9301034SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) { 65033ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 651b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 652bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 65333ad798cSAdam Langley } 65433ad798cSAdam Langley 655783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 6562646c831SDaniel Lee u32 need = fastopen->cookie.len; 6572646c831SDaniel Lee 6582646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 6592646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 660783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 661783237e8SYuchung Cheng if (remaining >= need) { 662783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 663783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 664783237e8SYuchung Cheng remaining -= need; 665783237e8SYuchung Cheng tp->syn_fastopen = 1; 6662646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 667783237e8SYuchung Cheng } 668783237e8SYuchung Cheng } 669bd0388aeSWilliam Allen Simpson 67060e2a778SUrsula Braun smc_set_option(tp, opts, &remaining); 67160e2a778SUrsula Braun 672bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 67333ad798cSAdam Langley } 67433ad798cSAdam Langley 67567edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 67660e2a778SUrsula Braun static unsigned int tcp_synack_options(const struct sock *sk, 67760e2a778SUrsula Braun struct request_sock *req, 67895c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 67933ad798cSAdam Langley struct tcp_out_options *opts, 68080f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 6818336886fSJerry Chu struct tcp_fastopen_cookie *foc) 6824957faadSWilliam Allen Simpson { 68333ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 68495c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 68533ad798cSAdam Langley 68633ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 68780f03e27SEric Dumazet if (md5) { 68833ad798cSAdam Langley opts->options |= OPTION_MD5; 6894957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6904957faadSWilliam Allen Simpson 6914957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6924957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6934957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6944957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6954957faadSWilliam Allen Simpson */ 696de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 69733ad798cSAdam Langley } 69833ad798cSAdam Langley #endif 69933ad798cSAdam Langley 7004957faadSWilliam Allen Simpson /* We always send an MSS option. */ 70133ad798cSAdam Langley opts->mss = mss; 7024957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 70333ad798cSAdam Langley 70433ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 70533ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 70689e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 7074957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 70833ad798cSAdam Langley } 709de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 71033ad798cSAdam Langley opts->options |= OPTION_TS; 71195a22caeSFlorian Westphal opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; 71233ad798cSAdam Langley opts->tsecr = req->ts_recent; 7134957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 71433ad798cSAdam Langley } 71533ad798cSAdam Langley if (likely(ireq->sack_ok)) { 71633ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 717de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 7184957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 71933ad798cSAdam Langley } 7207f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 7217f9b838bSDaniel Lee u32 need = foc->len; 7227f9b838bSDaniel Lee 7237f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 7247f9b838bSDaniel Lee TCPOLEN_FASTOPEN_BASE; 7258336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 7268336886fSJerry Chu if (remaining >= need) { 7278336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 7288336886fSJerry Chu opts->fastopen_cookie = foc; 7298336886fSJerry Chu remaining -= need; 7308336886fSJerry Chu } 7318336886fSJerry Chu } 7324957faadSWilliam Allen Simpson 73360e2a778SUrsula Braun smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); 73460e2a778SUrsula Braun 7354957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 73633ad798cSAdam Langley } 73733ad798cSAdam Langley 73867edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 73967edfef7SAndi Kleen * final wire format yet. 74067edfef7SAndi Kleen */ 74195c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 74233ad798cSAdam Langley struct tcp_out_options *opts, 743cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 744cf533ea5SEric Dumazet { 74533ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 74695c96174SEric Dumazet unsigned int size = 0; 747cabeccbdSIlpo Järvinen unsigned int eff_sacks; 74833ad798cSAdam Langley 7495843ef42SAndi Kleen opts->options = 0; 7505843ef42SAndi Kleen 7518c2320e8SEric Dumazet *md5 = NULL; 75233ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 7538c2320e8SEric Dumazet if (unlikely(rcu_access_pointer(tp->md5sig_info))) { 75433ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 7558c2320e8SEric Dumazet if (*md5) { 75633ad798cSAdam Langley opts->options |= OPTION_MD5; 75733ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 75833ad798cSAdam Langley } 7598c2320e8SEric Dumazet } 76033ad798cSAdam Langley #endif 76133ad798cSAdam Langley 76233ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 76333ad798cSAdam Langley opts->options |= OPTION_TS; 7647faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 76533ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 76633ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 76733ad798cSAdam Langley } 76833ad798cSAdam Langley 769cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 770cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 77195c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 77233ad798cSAdam Langley opts->num_sack_blocks = 77395c96174SEric Dumazet min_t(unsigned int, eff_sacks, 77433ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 77533ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 77633ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 77733ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 77833ad798cSAdam Langley } 77933ad798cSAdam Langley 78033ad798cSAdam Langley return size; 78140efc6faSStephen Hemminger } 7821da177e4SLinus Torvalds 78346d3ceabSEric Dumazet 78446d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 78546d3ceabSEric Dumazet * 78646d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 78746d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 78846d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 78946d3ceabSEric Dumazet * 79046d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 79146d3ceabSEric Dumazet * needs to be reallocated in a driver. 7928e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 79346d3ceabSEric Dumazet * 79446d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 79546d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 79646d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 79746d3ceabSEric Dumazet */ 79846d3ceabSEric Dumazet struct tsq_tasklet { 79946d3ceabSEric Dumazet struct tasklet_struct tasklet; 80046d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 80146d3ceabSEric Dumazet }; 80246d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 80346d3ceabSEric Dumazet 80473a6bab5SEric Dumazet static void tcp_tsq_write(struct sock *sk) 8056f458dfbSEric Dumazet { 8066f458dfbSEric Dumazet if ((1 << sk->sk_state) & 8076f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 808f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 809f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 810f9616c35SEric Dumazet 811f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 8123a91d29fSKoichiro Den tp->snd_cwnd > tcp_packets_in_flight(tp)) { 8133a91d29fSKoichiro Den tcp_mstamp_refresh(tp); 814f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 8153a91d29fSKoichiro Den } 816f9616c35SEric Dumazet 817f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 818bf06200eSJohn Ogness 0, GFP_ATOMIC); 8196f458dfbSEric Dumazet } 820f9616c35SEric Dumazet } 82173a6bab5SEric Dumazet 82273a6bab5SEric Dumazet static void tcp_tsq_handler(struct sock *sk) 82373a6bab5SEric Dumazet { 82473a6bab5SEric Dumazet bh_lock_sock(sk); 82573a6bab5SEric Dumazet if (!sock_owned_by_user(sk)) 82673a6bab5SEric Dumazet tcp_tsq_write(sk); 82773a6bab5SEric Dumazet else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) 82873a6bab5SEric Dumazet sock_hold(sk); 82973a6bab5SEric Dumazet bh_unlock_sock(sk); 83073a6bab5SEric Dumazet } 83146d3ceabSEric Dumazet /* 8328e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 83346d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 8348e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 83546d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 83646d3ceabSEric Dumazet */ 83746d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 83846d3ceabSEric Dumazet { 83946d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 84046d3ceabSEric Dumazet LIST_HEAD(list); 84146d3ceabSEric Dumazet unsigned long flags; 84246d3ceabSEric Dumazet struct list_head *q, *n; 84346d3ceabSEric Dumazet struct tcp_sock *tp; 84446d3ceabSEric Dumazet struct sock *sk; 84546d3ceabSEric Dumazet 84646d3ceabSEric Dumazet local_irq_save(flags); 84746d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 84846d3ceabSEric Dumazet local_irq_restore(flags); 84946d3ceabSEric Dumazet 85046d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 85146d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 85246d3ceabSEric Dumazet list_del(&tp->tsq_node); 85346d3ceabSEric Dumazet 85446d3ceabSEric Dumazet sk = (struct sock *)tp; 8550a9648f1SEric Dumazet smp_mb__before_atomic(); 8567aa5470cSEric Dumazet clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); 8577aa5470cSEric Dumazet 8586f458dfbSEric Dumazet tcp_tsq_handler(sk); 85946d3ceabSEric Dumazet sk_free(sk); 86046d3ceabSEric Dumazet } 86146d3ceabSEric Dumazet } 86246d3ceabSEric Dumazet 86340fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 86440fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 86540fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 86640fc3423SEric Dumazet TCPF_MTU_REDUCED_DEFERRED) 86746d3ceabSEric Dumazet /** 86846d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 86946d3ceabSEric Dumazet * @sk: socket 87046d3ceabSEric Dumazet * 87146d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 87246d3ceabSEric Dumazet * actions before socket release. 87346d3ceabSEric Dumazet */ 87446d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 87546d3ceabSEric Dumazet { 8766f458dfbSEric Dumazet unsigned long flags, nflags; 87746d3ceabSEric Dumazet 8786f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 8796f458dfbSEric Dumazet do { 8807aa5470cSEric Dumazet flags = sk->sk_tsq_flags; 8816f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 8826f458dfbSEric Dumazet return; 8836f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 8847aa5470cSEric Dumazet } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); 8856f458dfbSEric Dumazet 88673a6bab5SEric Dumazet if (flags & TCPF_TSQ_DEFERRED) { 88773a6bab5SEric Dumazet tcp_tsq_write(sk); 88873a6bab5SEric Dumazet __sock_put(sk); 88973a6bab5SEric Dumazet } 890c3f9b018SEric Dumazet /* Here begins the tricky part : 891c3f9b018SEric Dumazet * We are called from release_sock() with : 892c3f9b018SEric Dumazet * 1) BH disabled 893c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 894c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 895c3f9b018SEric Dumazet * 896c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 897c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 898c3f9b018SEric Dumazet */ 899c3f9b018SEric Dumazet sock_release_ownership(sk); 900c3f9b018SEric Dumazet 90140fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 9026f458dfbSEric Dumazet tcp_write_timer_handler(sk); 903144d56e9SEric Dumazet __sock_put(sk); 904144d56e9SEric Dumazet } 90540fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 9066f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 907144d56e9SEric Dumazet __sock_put(sk); 908144d56e9SEric Dumazet } 90940fc3423SEric Dumazet if (flags & TCPF_MTU_REDUCED_DEFERRED) { 9104fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 911144d56e9SEric Dumazet __sock_put(sk); 912144d56e9SEric Dumazet } 91346d3ceabSEric Dumazet } 91446d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 91546d3ceabSEric Dumazet 91646d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 91746d3ceabSEric Dumazet { 91846d3ceabSEric Dumazet int i; 91946d3ceabSEric Dumazet 92046d3ceabSEric Dumazet for_each_possible_cpu(i) { 92146d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 92246d3ceabSEric Dumazet 92346d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 92446d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 92546d3ceabSEric Dumazet tcp_tasklet_func, 92646d3ceabSEric Dumazet (unsigned long)tsq); 92746d3ceabSEric Dumazet } 92846d3ceabSEric Dumazet } 92946d3ceabSEric Dumazet 93046d3ceabSEric Dumazet /* 93146d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 9328e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 93346d3ceabSEric Dumazet * hold qdisc lock. 93446d3ceabSEric Dumazet */ 935d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 93646d3ceabSEric Dumazet { 93746d3ceabSEric Dumazet struct sock *sk = skb->sk; 93846d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 939408f0a6cSEric Dumazet unsigned long flags, nval, oval; 9409b462d02SEric Dumazet 9419b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 9429b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 9439b462d02SEric Dumazet */ 94414afee4bSReshetova, Elena WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); 9459b462d02SEric Dumazet 9469b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 9479b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 9489b462d02SEric Dumazet * This gives : 9499b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 9509b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 9519b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 9529b462d02SEric Dumazet */ 95314afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 9549b462d02SEric Dumazet goto out; 95546d3ceabSEric Dumazet 9567aa5470cSEric Dumazet for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { 95746d3ceabSEric Dumazet struct tsq_tasklet *tsq; 958a9b204d1SEric Dumazet bool empty; 95946d3ceabSEric Dumazet 960408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 961408f0a6cSEric Dumazet goto out; 962408f0a6cSEric Dumazet 96373a6bab5SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; 9647aa5470cSEric Dumazet nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); 965408f0a6cSEric Dumazet if (nval != oval) 966408f0a6cSEric Dumazet continue; 967408f0a6cSEric Dumazet 96846d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 96946d3ceabSEric Dumazet local_irq_save(flags); 970903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 971a9b204d1SEric Dumazet empty = list_empty(&tsq->head); 97246d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 973a9b204d1SEric Dumazet if (empty) 97446d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 97546d3ceabSEric Dumazet local_irq_restore(flags); 9769b462d02SEric Dumazet return; 97746d3ceabSEric Dumazet } 9789b462d02SEric Dumazet out: 9799b462d02SEric Dumazet sk_free(sk); 98046d3ceabSEric Dumazet } 98146d3ceabSEric Dumazet 98273a6bab5SEric Dumazet /* Note: Called under soft irq. 98373a6bab5SEric Dumazet * We can call TCP stack right away, unless socket is owned by user. 984218af599SEric Dumazet */ 985218af599SEric Dumazet enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 986218af599SEric Dumazet { 987218af599SEric Dumazet struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); 988218af599SEric Dumazet struct sock *sk = (struct sock *)tp; 989218af599SEric Dumazet 99073a6bab5SEric Dumazet tcp_tsq_handler(sk); 99173a6bab5SEric Dumazet sock_put(sk); 992218af599SEric Dumazet 993218af599SEric Dumazet return HRTIMER_NORESTART; 994218af599SEric Dumazet } 995218af599SEric Dumazet 996218af599SEric Dumazet static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) 997218af599SEric Dumazet { 998218af599SEric Dumazet u64 len_ns; 999218af599SEric Dumazet u32 rate; 1000218af599SEric Dumazet 1001218af599SEric Dumazet if (!tcp_needs_internal_pacing(sk)) 1002218af599SEric Dumazet return; 1003218af599SEric Dumazet rate = sk->sk_pacing_rate; 1004218af599SEric Dumazet if (!rate || rate == ~0U) 1005218af599SEric Dumazet return; 1006218af599SEric Dumazet 1007218af599SEric Dumazet len_ns = (u64)skb->len * NSEC_PER_SEC; 1008218af599SEric Dumazet do_div(len_ns, rate); 1009218af599SEric Dumazet hrtimer_start(&tcp_sk(sk)->pacing_timer, 1010fd2bca2aSEric Dumazet ktime_add_ns(ktime_get_tai_ns(), len_ns), 101173a6bab5SEric Dumazet HRTIMER_MODE_ABS_PINNED_SOFT); 101273a6bab5SEric Dumazet sock_hold(sk); 1013218af599SEric Dumazet } 1014218af599SEric Dumazet 1015*ab408b6dSEric Dumazet static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb) 1016e2080072SEric Dumazet { 1017*ab408b6dSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1018*ab408b6dSEric Dumazet 1019d3edd06eSEric Dumazet skb->skb_mstamp_ns = tp->tcp_wstamp_ns; 1020*ab408b6dSEric Dumazet if (sk->sk_pacing_status != SK_PACING_NONE) { 1021*ab408b6dSEric Dumazet u32 rate = sk->sk_pacing_rate; 1022*ab408b6dSEric Dumazet 1023*ab408b6dSEric Dumazet /* Original sch_fq does not pace first 10 MSS 1024*ab408b6dSEric Dumazet * Note that tp->data_segs_out overflows after 2^32 packets, 1025*ab408b6dSEric Dumazet * this is a minor annoyance. 1026*ab408b6dSEric Dumazet */ 1027*ab408b6dSEric Dumazet if (rate != ~0U && rate && tp->data_segs_out >= 10) { 1028*ab408b6dSEric Dumazet tp->tcp_wstamp_ns += div_u64((u64)skb->len * NSEC_PER_SEC, rate); 1029*ab408b6dSEric Dumazet /* TODO: update internal pacing here */ 1030*ab408b6dSEric Dumazet } 1031*ab408b6dSEric Dumazet } 1032e2080072SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 1033e2080072SEric Dumazet } 1034e2080072SEric Dumazet 10351da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 10361da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 10371da177e4SLinus Torvalds * transmission and possible later retransmissions. 10381da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 10391da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 10401da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 10411da177e4SLinus Torvalds * device. 10421da177e4SLinus Torvalds * 10431da177e4SLinus Torvalds * We are working here with either a clone of the original 10441da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 10451da177e4SLinus Torvalds */ 10462987babbSYuchung Cheng static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, 10472987babbSYuchung Cheng int clone_it, gfp_t gfp_mask, u32 rcv_nxt) 10481da177e4SLinus Torvalds { 10496687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1050dfb4b9dcSDavid S. Miller struct inet_sock *inet; 1051dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 1052dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 105333ad798cSAdam Langley struct tcp_out_options opts; 105495c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 10558c72c65bSEric Dumazet struct sk_buff *oskb = NULL; 1056cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 10571da177e4SLinus Torvalds struct tcphdr *th; 10581da177e4SLinus Torvalds int err; 10591da177e4SLinus Torvalds 1060dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 10616f094b9eSLawrence Brakmo tp = tcp_sk(sk); 1062dfb4b9dcSDavid S. Miller 1063ccdbb6e9SEric Dumazet if (clone_it) { 10646f094b9eSLawrence Brakmo TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq 10656f094b9eSLawrence Brakmo - tp->snd_una; 10668c72c65bSEric Dumazet oskb = skb; 1067e2080072SEric Dumazet 1068e2080072SEric Dumazet tcp_skb_tsorted_save(oskb) { 1069e2080072SEric Dumazet if (unlikely(skb_cloned(oskb))) 1070e2080072SEric Dumazet skb = pskb_copy(oskb, gfp_mask); 1071dfb4b9dcSDavid S. Miller else 1072e2080072SEric Dumazet skb = skb_clone(oskb, gfp_mask); 1073e2080072SEric Dumazet } tcp_skb_tsorted_restore(oskb); 1074e2080072SEric Dumazet 1075dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 1076dfb4b9dcSDavid S. Miller return -ENOBUFS; 1077dfb4b9dcSDavid S. Miller } 1078d3edd06eSEric Dumazet skb->skb_mstamp_ns = tp->tcp_wstamp_ns; 1079dfb4b9dcSDavid S. Miller 1080dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 1081dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 108233ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 10831da177e4SLinus Torvalds 10844de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 108533ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 108633ad798cSAdam Langley else 108733ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 108833ad798cSAdam Langley &md5); 108933ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 10901da177e4SLinus Torvalds 1091547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 1092b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 109373a6bab5SEric Dumazet * which holds one reference to sk. 1094b2532eb9SEric Dumazet * 1095b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 1096b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 1097547669d4SEric Dumazet */ 1098b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 10991da177e4SLinus Torvalds 110038ab52e8SEric Dumazet /* If we had to use memory reserve to allocate this skb, 110138ab52e8SEric Dumazet * this might cause drops if packet is looped back : 110238ab52e8SEric Dumazet * Other socket might not have SOCK_MEMALLOC. 110338ab52e8SEric Dumazet * Packets not looped back do not care about pfmemalloc. 110438ab52e8SEric Dumazet */ 110538ab52e8SEric Dumazet skb->pfmemalloc = 0; 110638ab52e8SEric Dumazet 1107aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 1108aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 110946d3ceabSEric Dumazet 111046d3ceabSEric Dumazet skb_orphan(skb); 111146d3ceabSEric Dumazet skb->sk = sk; 11121d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 1113b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 111414afee4bSReshetova, Elena refcount_add(skb->truesize, &sk->sk_wmem_alloc); 11151da177e4SLinus Torvalds 1116c3a2e837SJulian Anastasov skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); 1117c3a2e837SJulian Anastasov 11181da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 1119ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 1120c720c7e8SEric Dumazet th->source = inet->inet_sport; 1121c720c7e8SEric Dumazet th->dest = inet->inet_dport; 11221da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 11232987babbSYuchung Cheng th->ack_seq = htonl(rcv_nxt); 1124df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 11254de075e0SEric Dumazet tcb->tcp_flags); 1126dfb4b9dcSDavid S. Miller 11271da177e4SLinus Torvalds th->check = 0; 11281da177e4SLinus Torvalds th->urg_ptr = 0; 11291da177e4SLinus Torvalds 113033f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 11317691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 11327691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 11331da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 11341da177e4SLinus Torvalds th->urg = 1; 11357691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 11360eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 11377691367dSHerbert Xu th->urg = 1; 11387691367dSHerbert Xu } 11391da177e4SLinus Torvalds } 11401da177e4SLinus Torvalds 1141bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 114251466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 1143ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1144ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1145ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1146ea1627c2SEric Dumazet } else { 1147ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1148ea1627c2SEric Dumazet * is never scaled. 1149ea1627c2SEric Dumazet */ 1150ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1151ea1627c2SEric Dumazet } 1152cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1153cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1154cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1155a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1156bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 115739f8e58eSEric Dumazet md5, sk, skb); 1158cfb6eeb4SYOSHIFUJI Hideaki } 1159cfb6eeb4SYOSHIFUJI Hideaki #endif 1160cfb6eeb4SYOSHIFUJI Hideaki 1161bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 11621da177e4SLinus Torvalds 11634de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 116427cde44aSYuchung Cheng tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt); 11651da177e4SLinus Torvalds 1166a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1167cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1168a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1169ba113c3aSWei Wang tp->bytes_sent += skb->len - tcp_header_size; 1170218af599SEric Dumazet tcp_internal_pacing(sk, skb); 1171a44d6eacSMartin KaFai Lau } 11721da177e4SLinus Torvalds 1173bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1174aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1175aa2ea058STom Herbert tcp_skb_pcount(skb)); 11761da177e4SLinus Torvalds 11772efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 1178f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1179cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1180f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1181cd7d8498SEric Dumazet 1182d3edd06eSEric Dumazet /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ 1183971f10ecSEric Dumazet 1184971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1185971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1186971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1187971f10ecSEric Dumazet 1188b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 11897faee5c0SEric Dumazet 11908c72c65bSEric Dumazet if (unlikely(err > 0)) { 11915ee2c941SChristoph Paasch tcp_enter_cwr(sk); 11928c72c65bSEric Dumazet err = net_xmit_eval(err); 11938c72c65bSEric Dumazet } 1194fc225799SEric Dumazet if (!err && oskb) { 1195*ab408b6dSEric Dumazet tcp_update_skb_after_send(sk, oskb); 1196fc225799SEric Dumazet tcp_rate_skb_sent(sk, oskb); 1197fc225799SEric Dumazet } 11988c72c65bSEric Dumazet return err; 11991da177e4SLinus Torvalds } 12001da177e4SLinus Torvalds 12012987babbSYuchung Cheng static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 12022987babbSYuchung Cheng gfp_t gfp_mask) 12032987babbSYuchung Cheng { 12042987babbSYuchung Cheng return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, 12052987babbSYuchung Cheng tcp_sk(sk)->rcv_nxt); 12062987babbSYuchung Cheng } 12072987babbSYuchung Cheng 120867edfef7SAndi Kleen /* This routine just queues the buffer for sending. 12091da177e4SLinus Torvalds * 12101da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 12111da177e4SLinus Torvalds * otherwise socket can stall. 12121da177e4SLinus Torvalds */ 12131da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 12141da177e4SLinus Torvalds { 12151da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12161da177e4SLinus Torvalds 12171da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 12181da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1219f4a775d1SEric Dumazet __skb_header_release(skb); 1220fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 12213ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 12223ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 12231da177e4SLinus Torvalds } 12241da177e4SLinus Torvalds 122567edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 12265bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1227f6302d1dSDavid S. Miller { 12284a64fd6cSEric Dumazet if (skb->len <= mss_now) { 1229f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1230f6302d1dSDavid S. Miller * non-TSO case. 1231f6302d1dSDavid S. Miller */ 1232cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1233f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1234f6302d1dSDavid S. Miller } else { 1235cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1236f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 12371da177e4SLinus Torvalds } 12381da177e4SLinus Torvalds } 12391da177e4SLinus Torvalds 1240797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1241797108d1SIlpo Järvinen * tweaks to fix counters 1242797108d1SIlpo Järvinen */ 1243cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1244797108d1SIlpo Järvinen { 1245797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1246797108d1SIlpo Järvinen 1247797108d1SIlpo Järvinen tp->packets_out -= decr; 1248797108d1SIlpo Järvinen 1249797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1250797108d1SIlpo Järvinen tp->sacked_out -= decr; 1251797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1252797108d1SIlpo Järvinen tp->retrans_out -= decr; 1253797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1254797108d1SIlpo Järvinen tp->lost_out -= decr; 1255797108d1SIlpo Järvinen 1256797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1257797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1258797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1259797108d1SIlpo Järvinen 1260797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1261797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 1262713bafeaSYuchung Cheng (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) 1263797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1264797108d1SIlpo Järvinen 1265797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1266797108d1SIlpo Järvinen } 1267797108d1SIlpo Järvinen 12680a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 12690a2cf20cSSoheil Hassas Yeganeh { 12700a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 12710a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 12720a2cf20cSSoheil Hassas Yeganeh } 12730a2cf20cSSoheil Hassas Yeganeh 1274490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1275490cc7d0SWillem de Bruijn { 1276490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1277490cc7d0SWillem de Bruijn 12780a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1279490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1280490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1281490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1282490cc7d0SWillem de Bruijn 1283490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1284490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1285490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1286b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1287b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1288490cc7d0SWillem de Bruijn } 1289490cc7d0SWillem de Bruijn } 1290490cc7d0SWillem de Bruijn 1291a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1292a166140eSMartin KaFai Lau { 1293a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1294a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1295a166140eSMartin KaFai Lau } 1296a166140eSMartin KaFai Lau 129775c119afSEric Dumazet /* Insert buff after skb on the write or rtx queue of sk. */ 129875c119afSEric Dumazet static void tcp_insert_write_queue_after(struct sk_buff *skb, 129975c119afSEric Dumazet struct sk_buff *buff, 130075c119afSEric Dumazet struct sock *sk, 130175c119afSEric Dumazet enum tcp_queue tcp_queue) 130275c119afSEric Dumazet { 130375c119afSEric Dumazet if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) 130475c119afSEric Dumazet __skb_queue_after(&sk->sk_write_queue, skb, buff); 130575c119afSEric Dumazet else 130675c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 130775c119afSEric Dumazet } 130875c119afSEric Dumazet 13091da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 13101da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 13111da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 13121da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 13131da177e4SLinus Torvalds */ 131475c119afSEric Dumazet int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 131575c119afSEric Dumazet struct sk_buff *skb, u32 len, 13166cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 13171da177e4SLinus Torvalds { 13181da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 13191da177e4SLinus Torvalds struct sk_buff *buff; 13206475be16SDavid S. Miller int nsize, old_factor; 1321b60b49eaSHerbert Xu int nlen; 13229ce01461SIlpo Järvinen u8 flags; 13231da177e4SLinus Torvalds 13242fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 13252fceec13SIlpo Järvinen return -EINVAL; 13266a438bbeSStephen Hemminger 13271da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 13281da177e4SLinus Torvalds if (nsize < 0) 13291da177e4SLinus Torvalds nsize = 0; 13301da177e4SLinus Torvalds 13316cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 13321da177e4SLinus Torvalds return -ENOMEM; 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 1335eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, nsize, gfp, true); 133651456b29SIan Morris if (!buff) 13371da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1338ef5cb973SHerbert Xu 13393ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 13403ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1341b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1342b60b49eaSHerbert Xu buff->truesize += nlen; 1343b60b49eaSHerbert Xu skb->truesize -= nlen; 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds /* Correct the sequence numbers. */ 13461da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 13471da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 13481da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 13491da177e4SLinus Torvalds 13501da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 13514de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 13524de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 13534de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1354e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1355a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 13561da177e4SLinus Torvalds 13571da177e4SLinus Torvalds skb_split(skb, buff, len); 13581da177e4SLinus Torvalds 135998be9b12SEric Dumazet buff->ip_summed = CHECKSUM_PARTIAL; 13601da177e4SLinus Torvalds 1361a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1362490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 13631da177e4SLinus Torvalds 13646475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 13656475be16SDavid S. Miller 13661da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 13675bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 13685bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 13691da177e4SLinus Torvalds 1370b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1371b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1372b9f64820SYuchung Cheng 13736475be16SDavid S. Miller /* If this packet has been sent out already, we must 13746475be16SDavid S. Miller * adjust the various packet counters. 13756475be16SDavid S. Miller */ 1376cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 13776475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 13786475be16SDavid S. Miller tcp_skb_pcount(buff); 13791da177e4SLinus Torvalds 1380797108d1SIlpo Järvinen if (diff) 1381797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 13821da177e4SLinus Torvalds } 13831da177e4SLinus Torvalds 13841da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1385f4a775d1SEric Dumazet __skb_header_release(buff); 138675c119afSEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); 1387f67971e6SEric Dumazet if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) 1388e2080072SEric Dumazet list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); 13891da177e4SLinus Torvalds 13901da177e4SLinus Torvalds return 0; 13911da177e4SLinus Torvalds } 13921da177e4SLinus Torvalds 1393f4d01666SEric Dumazet /* This is similar to __pskb_pull_tail(). The difference is that pulled 1394f4d01666SEric Dumazet * data is not copied, but immediately discarded. 13951da177e4SLinus Torvalds */ 13967162fb24SEric Dumazet static int __pskb_trim_head(struct sk_buff *skb, int len) 13971da177e4SLinus Torvalds { 13987b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 13991da177e4SLinus Torvalds int i, k, eat; 14001da177e4SLinus Torvalds 14014fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 14024fa48bf3SEric Dumazet if (eat) { 14034fa48bf3SEric Dumazet __skb_pull(skb, eat); 14044fa48bf3SEric Dumazet len -= eat; 14054fa48bf3SEric Dumazet if (!len) 14067162fb24SEric Dumazet return 0; 14074fa48bf3SEric Dumazet } 14081da177e4SLinus Torvalds eat = len; 14091da177e4SLinus Torvalds k = 0; 14107b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 14117b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 14127b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 14139e903e08SEric Dumazet 14149e903e08SEric Dumazet if (size <= eat) { 1415aff65da0SIan Campbell skb_frag_unref(skb, i); 14169e903e08SEric Dumazet eat -= size; 14171da177e4SLinus Torvalds } else { 14187b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 14191da177e4SLinus Torvalds if (eat) { 14207b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 14217b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 14221da177e4SLinus Torvalds eat = 0; 14231da177e4SLinus Torvalds } 14241da177e4SLinus Torvalds k++; 14251da177e4SLinus Torvalds } 14261da177e4SLinus Torvalds } 14277b7fc97aSEric Dumazet shinfo->nr_frags = k; 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds skb->data_len -= len; 14301da177e4SLinus Torvalds skb->len = skb->data_len; 14317162fb24SEric Dumazet return len; 14321da177e4SLinus Torvalds } 14331da177e4SLinus Torvalds 143467edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 14351da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 14361da177e4SLinus Torvalds { 14377162fb24SEric Dumazet u32 delta_truesize; 14387162fb24SEric Dumazet 143914bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 14401da177e4SLinus Torvalds return -ENOMEM; 14411da177e4SLinus Torvalds 14427162fb24SEric Dumazet delta_truesize = __pskb_trim_head(skb, len); 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 144584fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 14461da177e4SLinus Torvalds 14477162fb24SEric Dumazet if (delta_truesize) { 14487162fb24SEric Dumazet skb->truesize -= delta_truesize; 14497162fb24SEric Dumazet sk->sk_wmem_queued -= delta_truesize; 14507162fb24SEric Dumazet sk_mem_uncharge(sk, delta_truesize); 14511da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 14527162fb24SEric Dumazet } 14531da177e4SLinus Torvalds 14545b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 14551da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 14565bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds return 0; 14591da177e4SLinus Torvalds } 14601da177e4SLinus Torvalds 14611b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 14621b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 14635d424d5aSJohn Heffner { 1464cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1465cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 14665d424d5aSJohn Heffner int mss_now; 14675d424d5aSJohn Heffner 14685d424d5aSJohn Heffner /* Calculate base mss without TCP options: 14695d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 14705d424d5aSJohn Heffner */ 14715d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 14725d424d5aSJohn Heffner 147367469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 147467469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 147567469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 147667469601SEric Dumazet 147767469601SEric Dumazet if (dst && dst_allfrag(dst)) 147867469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 147967469601SEric Dumazet } 148067469601SEric Dumazet 14815d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 14825d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 14835d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 14845d424d5aSJohn Heffner 14855d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 14865d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 14875d424d5aSJohn Heffner 14885d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 14895d424d5aSJohn Heffner if (mss_now < 48) 14905d424d5aSJohn Heffner mss_now = 48; 14915d424d5aSJohn Heffner return mss_now; 14925d424d5aSJohn Heffner } 14935d424d5aSJohn Heffner 14941b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 14951b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 14961b63edd6SYuchung Cheng { 14971b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 14981b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 14991b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 15001b63edd6SYuchung Cheng } 15011b63edd6SYuchung Cheng 15025d424d5aSJohn Heffner /* Inverse of above */ 150367469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 15045d424d5aSJohn Heffner { 1505cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1506cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 15075d424d5aSJohn Heffner int mtu; 15085d424d5aSJohn Heffner 15095d424d5aSJohn Heffner mtu = mss + 15105d424d5aSJohn Heffner tp->tcp_header_len + 15115d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 15125d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 15135d424d5aSJohn Heffner 151467469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 151567469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 151667469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 151767469601SEric Dumazet 151867469601SEric Dumazet if (dst && dst_allfrag(dst)) 151967469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 152067469601SEric Dumazet } 15215d424d5aSJohn Heffner return mtu; 15225d424d5aSJohn Heffner } 1523556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 15245d424d5aSJohn Heffner 152567edfef7SAndi Kleen /* MTU probing init per socket */ 15265d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 15275d424d5aSJohn Heffner { 15285d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 15295d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1530b0f9ca53SFan Du struct net *net = sock_net(sk); 15315d424d5aSJohn Heffner 1532b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 15335d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 15345d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1535b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 15365d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 153705cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 1538c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 15395d424d5aSJohn Heffner } 15404bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 15415d424d5aSJohn Heffner 15421da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 15431da177e4SLinus Torvalds 15441da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 15451da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 15461da177e4SLinus Torvalds 15471da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1548caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 15491da177e4SLinus Torvalds It also does not include TCP options. 15501da177e4SLinus Torvalds 1551d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 15521da177e4SLinus Torvalds 15531da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 15541da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 15551da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 15561da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 15571da177e4SLinus Torvalds 15581da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 15591da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 15601da177e4SLinus Torvalds 1561d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1562d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 15631da177e4SLinus Torvalds */ 15641da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 15651da177e4SLinus Torvalds { 15661da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1567d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 15685d424d5aSJohn Heffner int mss_now; 15691da177e4SLinus Torvalds 15705d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 15715d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 15721da177e4SLinus Torvalds 15735d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1574409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds /* And store cached results */ 1577d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 15785d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 15795d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1580c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 15811da177e4SLinus Torvalds 15821da177e4SLinus Torvalds return mss_now; 15831da177e4SLinus Torvalds } 15844bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 15851da177e4SLinus Torvalds 15861da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 15871da177e4SLinus Torvalds * and even PMTU discovery events into account. 15881da177e4SLinus Torvalds */ 15890c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 15901da177e4SLinus Torvalds { 1591cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1592cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1593c1b4a7e6SDavid S. Miller u32 mss_now; 159495c96174SEric Dumazet unsigned int header_len; 159533ad798cSAdam Langley struct tcp_out_options opts; 159633ad798cSAdam Langley struct tcp_md5sig_key *md5; 15971da177e4SLinus Torvalds 1598c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1599c1b4a7e6SDavid S. Miller 16001da177e4SLinus Torvalds if (dst) { 16011da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1602d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 16031da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 16041da177e4SLinus Torvalds } 16051da177e4SLinus Torvalds 160633ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 160733ad798cSAdam Langley sizeof(struct tcphdr); 160833ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 160933ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 161033ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 161133ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 161233ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 161333ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 161433ad798cSAdam Langley mss_now -= delta; 161533ad798cSAdam Langley } 1616cfb6eeb4SYOSHIFUJI Hideaki 16171da177e4SLinus Torvalds return mss_now; 16181da177e4SLinus Torvalds } 16191da177e4SLinus Torvalds 162086fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 162186fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 162286fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 162386fd14adSWeiping Pan */ 162486fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1625a762a980SDavid S. Miller { 16269e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1627a762a980SDavid S. Miller 162886fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 162986fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 163086fd14adSWeiping Pan /* Limited by application or receiver window. */ 163186fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 163286fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 163386fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 163486fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 163586fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 163686fd14adSWeiping Pan } 163786fd14adSWeiping Pan tp->snd_cwnd_used = 0; 163886fd14adSWeiping Pan } 1639c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 164086fd14adSWeiping Pan } 164186fd14adSWeiping Pan 1642ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1643a762a980SDavid S. Miller { 16441b1fc3fdSWei Wang const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1645a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1646a762a980SDavid S. Miller 1647ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1648ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1649ca8a2263SNeal Cardwell */ 1650ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1651ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1652ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1653ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1654ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1655ca8a2263SNeal Cardwell } 1656e114a710SEric Dumazet 165724901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1658a762a980SDavid S. Miller /* Network is feed fully. */ 1659a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1660c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1661a762a980SDavid S. Miller } else { 1662a762a980SDavid S. Miller /* Network starves. */ 1663a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1664a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1665a762a980SDavid S. Miller 1666b510f0d2SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle && 1667c2203cf7SEric Dumazet (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && 16681b1fc3fdSWei Wang !ca_ops->cong_control) 1669a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1670b0f71bd3SFrancis Yan 1671b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1672b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1673b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1674b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 167575c119afSEric Dumazet * 3) no more data to send (tcp_write_queue_empty()) 1676b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1677b0f71bd3SFrancis Yan */ 167875c119afSEric Dumazet if (tcp_write_queue_empty(sk) && sk->sk_socket && 1679b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1680b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1681b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1682a762a980SDavid S. Miller } 1683a762a980SDavid S. Miller } 1684a762a980SDavid S. Miller 1685d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1686d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1687d4589926SEric Dumazet { 1688d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1689d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1690d4589926SEric Dumazet } 1691d4589926SEric Dumazet 1692d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1693d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1694d4589926SEric Dumazet * The test is really : 1695d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1696d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1697d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1698d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 16990e3a4803SIlpo Järvinen */ 1700d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1701d4589926SEric Dumazet const struct sk_buff *skb) 1702d4589926SEric Dumazet { 1703d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1704d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1705d4589926SEric Dumazet } 1706d4589926SEric Dumazet 1707d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1708d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1709d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1710d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1711d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1712d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1713d4589926SEric Dumazet */ 1714d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1715cc93fc51SPeter Pan(潘卫平) int nonagle) 1716d4589926SEric Dumazet { 1717d4589926SEric Dumazet return partial && 1718d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1719d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1720d4589926SEric Dumazet } 1721605ad7f1SEric Dumazet 1722605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1723605ad7f1SEric Dumazet * to send one TSO packet per ms 1724605ad7f1SEric Dumazet */ 1725dcb8c9b4SEric Dumazet static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 17261b3878caSNeal Cardwell int min_tso_segs) 1727605ad7f1SEric Dumazet { 1728605ad7f1SEric Dumazet u32 bytes, segs; 1729605ad7f1SEric Dumazet 17303a9b76fdSEric Dumazet bytes = min(sk->sk_pacing_rate >> sk->sk_pacing_shift, 1731605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1732605ad7f1SEric Dumazet 1733605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1734605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1735605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1736605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1737605ad7f1SEric Dumazet */ 17381b3878caSNeal Cardwell segs = max_t(u32, bytes / mss_now, min_tso_segs); 1739605ad7f1SEric Dumazet 1740350c9f48SEric Dumazet return segs; 1741605ad7f1SEric Dumazet } 1742605ad7f1SEric Dumazet 1743ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1744ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1745ed6e7268SNeal Cardwell */ 1746ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1747ed6e7268SNeal Cardwell { 1748ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1749dcb8c9b4SEric Dumazet u32 min_tso, tso_segs; 1750ed6e7268SNeal Cardwell 1751dcb8c9b4SEric Dumazet min_tso = ca_ops->min_tso_segs ? 1752dcb8c9b4SEric Dumazet ca_ops->min_tso_segs(sk) : 1753dcb8c9b4SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs; 1754dcb8c9b4SEric Dumazet 1755dcb8c9b4SEric Dumazet tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); 1756350c9f48SEric Dumazet return min_t(u32, tso_segs, sk->sk_gso_max_segs); 1757ed6e7268SNeal Cardwell } 1758ed6e7268SNeal Cardwell 1759d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1760d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1761d4589926SEric Dumazet const struct sk_buff *skb, 1762d4589926SEric Dumazet unsigned int mss_now, 1763d4589926SEric Dumazet unsigned int max_segs, 1764d4589926SEric Dumazet int nonagle) 1765c1b4a7e6SDavid S. Miller { 1766cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1767d4589926SEric Dumazet u32 partial, needed, window, max_len; 1768c1b4a7e6SDavid S. Miller 176990840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 17701485348dSBen Hutchings max_len = mss_now * max_segs; 17710e3a4803SIlpo Järvinen 17721485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 17731485348dSBen Hutchings return max_len; 17740e3a4803SIlpo Järvinen 17755ea3a748SIlpo Järvinen needed = min(skb->len, window); 17765ea3a748SIlpo Järvinen 17771485348dSBen Hutchings if (max_len <= needed) 17781485348dSBen Hutchings return max_len; 17790e3a4803SIlpo Järvinen 1780d4589926SEric Dumazet partial = needed % mss_now; 1781d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1782d4589926SEric Dumazet * to include this last segment in this skb. 1783d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1784d4589926SEric Dumazet */ 1785cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1786d4589926SEric Dumazet return needed - partial; 1787d4589926SEric Dumazet 1788d4589926SEric Dumazet return needed; 1789c1b4a7e6SDavid S. Miller } 1790c1b4a7e6SDavid S. Miller 1791c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1792c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1793c1b4a7e6SDavid S. Miller */ 1794cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1795cf533ea5SEric Dumazet const struct sk_buff *skb) 1796c1b4a7e6SDavid S. Miller { 1797d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1798c1b4a7e6SDavid S. Miller 1799c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 18004de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 18014de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1802c1b4a7e6SDavid S. Miller return 1; 1803c1b4a7e6SDavid S. Miller 1804c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1805c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1806d649a7a8SEric Dumazet if (in_flight >= cwnd) 1807c1b4a7e6SDavid S. Miller return 0; 1808d649a7a8SEric Dumazet 1809d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1810d649a7a8SEric Dumazet * 2 GSO packets in flight. 1811d649a7a8SEric Dumazet */ 1812d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1813d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1814c1b4a7e6SDavid S. Miller } 1815c1b4a7e6SDavid S. Miller 1816b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 181767edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1818c1b4a7e6SDavid S. Miller * SKB onto the wire. 1819c1b4a7e6SDavid S. Miller */ 18205bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1821c1b4a7e6SDavid S. Miller { 1822c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1823c1b4a7e6SDavid S. Miller 1824f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 18255bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 1826c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1827c1b4a7e6SDavid S. Miller } 1828c1b4a7e6SDavid S. Miller return tso_segs; 1829c1b4a7e6SDavid S. Miller } 1830c1b4a7e6SDavid S. Miller 1831c1b4a7e6SDavid S. Miller 1832a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1833c1b4a7e6SDavid S. Miller * sent now. 1834c1b4a7e6SDavid S. Miller */ 1835a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1836c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1837c1b4a7e6SDavid S. Miller { 1838c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1839c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1840c1b4a7e6SDavid S. Miller * 1841c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1842c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1843c1b4a7e6SDavid S. Miller */ 1844c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1845a2a385d6SEric Dumazet return true; 1846c1b4a7e6SDavid S. Miller 18479b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 18489b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1849a2a385d6SEric Dumazet return true; 1850c1b4a7e6SDavid S. Miller 1851cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1852a2a385d6SEric Dumazet return true; 1853c1b4a7e6SDavid S. Miller 1854a2a385d6SEric Dumazet return false; 1855c1b4a7e6SDavid S. Miller } 1856c1b4a7e6SDavid S. Miller 1857c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1858a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1859a2a385d6SEric Dumazet const struct sk_buff *skb, 1860056834d9SIlpo Järvinen unsigned int cur_mss) 1861c1b4a7e6SDavid S. Miller { 1862c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1863c1b4a7e6SDavid S. Miller 1864c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1865c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1866c1b4a7e6SDavid S. Miller 186790840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1868c1b4a7e6SDavid S. Miller } 1869c1b4a7e6SDavid S. Miller 1870c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1871c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1872c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1873c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1874c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1875c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1876c1b4a7e6SDavid S. Miller */ 187775c119afSEric Dumazet static int tso_fragment(struct sock *sk, enum tcp_queue tcp_queue, 187875c119afSEric Dumazet struct sk_buff *skb, unsigned int len, 1879c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1880c1b4a7e6SDavid S. Miller { 1881c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1882c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 18839ce01461SIlpo Järvinen u8 flags; 1884c1b4a7e6SDavid S. Miller 1885c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1886c8ac3774SHerbert Xu if (skb->len != skb->data_len) 188775c119afSEric Dumazet return tcp_fragment(sk, tcp_queue, skb, len, mss_now, gfp); 1888c1b4a7e6SDavid S. Miller 1889eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp, true); 189051456b29SIan Morris if (unlikely(!buff)) 1891c1b4a7e6SDavid S. Miller return -ENOMEM; 1892c1b4a7e6SDavid S. Miller 18933ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 18943ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1895b60b49eaSHerbert Xu buff->truesize += nlen; 1896c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1897c1b4a7e6SDavid S. Miller 1898c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1899c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1900c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1901c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1902c1b4a7e6SDavid S. Miller 1903c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 19044de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 19054de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 19064de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1907c1b4a7e6SDavid S. Miller 1908c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1909c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1910c1b4a7e6SDavid S. Miller 1911a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 1912a166140eSMartin KaFai Lau 191398be9b12SEric Dumazet buff->ip_summed = CHECKSUM_PARTIAL; 1914c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1915490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1916c1b4a7e6SDavid S. Miller 1917c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 19185bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 19195bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 1920c1b4a7e6SDavid S. Miller 1921c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1922f4a775d1SEric Dumazet __skb_header_release(buff); 192375c119afSEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); 1924c1b4a7e6SDavid S. Miller 1925c1b4a7e6SDavid S. Miller return 0; 1926c1b4a7e6SDavid S. Miller } 1927c1b4a7e6SDavid S. Miller 1928c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1929c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1930c1b4a7e6SDavid S. Miller * 1931c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1932c1b4a7e6SDavid S. Miller */ 1933ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1934605ad7f1SEric Dumazet bool *is_cwnd_limited, u32 max_segs) 1935c1b4a7e6SDavid S. Miller { 19366687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 193750c8339eSEric Dumazet u32 age, send_win, cong_win, limit, in_flight; 193850c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 193950c8339eSEric Dumazet struct sk_buff *head; 1940ad9f4f50SEric Dumazet int win_divisor; 1941c1b4a7e6SDavid S. Miller 19424de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1943ae8064acSJohn Heffner goto send_now; 1944c1b4a7e6SDavid S. Miller 194599d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 1946ae8064acSJohn Heffner goto send_now; 1947ae8064acSJohn Heffner 19485f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 19495f852eb5SEric Dumazet * only if the last write was recent. 19505f852eb5SEric Dumazet */ 1951d635fbe2SEric Dumazet if ((s32)(tcp_jiffies32 - tp->lsndtime) > 0) 1952ae8064acSJohn Heffner goto send_now; 1953908a75c1SDavid S. Miller 1954c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1955c1b4a7e6SDavid S. Miller 1956c8c9aeb5SStefano Brivio BUG_ON(tcp_skb_pcount(skb) <= 1); 1957c8c9aeb5SStefano Brivio BUG_ON(tp->snd_cwnd <= in_flight); 1958c1b4a7e6SDavid S. Miller 195990840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1960c1b4a7e6SDavid S. Miller 1961c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1962c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1963c1b4a7e6SDavid S. Miller 1964c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1965c1b4a7e6SDavid S. Miller 1966ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 1967605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 1968ae8064acSJohn Heffner goto send_now; 1969ba244fe9SDavid S. Miller 197062ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 197162ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 197262ad2761SIlpo Järvinen goto send_now; 197362ad2761SIlpo Järvinen 19745bbcc0f5SLinus Torvalds win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); 1975ad9f4f50SEric Dumazet if (win_divisor) { 1976c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1977c1b4a7e6SDavid S. Miller 1978c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1979c1b4a7e6SDavid S. Miller * just use it. 1980c1b4a7e6SDavid S. Miller */ 1981ad9f4f50SEric Dumazet chunk /= win_divisor; 1982c1b4a7e6SDavid S. Miller if (limit >= chunk) 1983ae8064acSJohn Heffner goto send_now; 1984c1b4a7e6SDavid S. Miller } else { 1985c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1986c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1987c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1988c1b4a7e6SDavid S. Miller * then send now. 1989c1b4a7e6SDavid S. Miller */ 19906b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1991ae8064acSJohn Heffner goto send_now; 1992c1b4a7e6SDavid S. Miller } 1993c1b4a7e6SDavid S. Miller 199475c119afSEric Dumazet /* TODO : use tsorted_sent_queue ? */ 199575c119afSEric Dumazet head = tcp_rtx_queue_head(sk); 199675c119afSEric Dumazet if (!head) 199775c119afSEric Dumazet goto send_now; 19982fd66ffbSEric Dumazet age = tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(head)); 199950c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 200050c8339eSEric Dumazet if (age < (tp->srtt_us >> 4)) 200150c8339eSEric Dumazet goto send_now; 200250c8339eSEric Dumazet 20035f852eb5SEric Dumazet /* Ok, it looks like it is advisable to defer. */ 2004ae8064acSJohn Heffner 2005d2e1339fSBendik Rønning Opstad if (cong_win < send_win && cong_win <= skb->len) 2006ca8a2263SNeal Cardwell *is_cwnd_limited = true; 2007ca8a2263SNeal Cardwell 2008a2a385d6SEric Dumazet return true; 2009ae8064acSJohn Heffner 2010ae8064acSJohn Heffner send_now: 2011a2a385d6SEric Dumazet return false; 2012c1b4a7e6SDavid S. Miller } 2013c1b4a7e6SDavid S. Miller 201405cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 201505cbc0dbSFan Du { 201605cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 201705cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 201805cbc0dbSFan Du struct net *net = sock_net(sk); 201905cbc0dbSFan Du u32 interval; 202005cbc0dbSFan Du s32 delta; 202105cbc0dbSFan Du 202205cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 2023c74df29aSEric Dumazet delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; 202405cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 202505cbc0dbSFan Du int mss = tcp_current_mss(sk); 202605cbc0dbSFan Du 202705cbc0dbSFan Du /* Update current search range */ 202805cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 202905cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 203005cbc0dbSFan Du sizeof(struct tcphdr) + 203105cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 203205cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 203305cbc0dbSFan Du 203405cbc0dbSFan Du /* Update probe time stamp */ 2035c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 203605cbc0dbSFan Du } 203705cbc0dbSFan Du } 203805cbc0dbSFan Du 2039808cf9e3SIlya Lesokhin static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) 2040808cf9e3SIlya Lesokhin { 2041808cf9e3SIlya Lesokhin struct sk_buff *skb, *next; 2042808cf9e3SIlya Lesokhin 2043808cf9e3SIlya Lesokhin skb = tcp_send_head(sk); 2044808cf9e3SIlya Lesokhin tcp_for_write_queue_from_safe(skb, next, sk) { 2045808cf9e3SIlya Lesokhin if (len <= skb->len) 2046808cf9e3SIlya Lesokhin break; 2047808cf9e3SIlya Lesokhin 2048808cf9e3SIlya Lesokhin if (unlikely(TCP_SKB_CB(skb)->eor)) 2049808cf9e3SIlya Lesokhin return false; 2050808cf9e3SIlya Lesokhin 2051808cf9e3SIlya Lesokhin len -= skb->len; 2052808cf9e3SIlya Lesokhin } 2053808cf9e3SIlya Lesokhin 2054808cf9e3SIlya Lesokhin return true; 2055808cf9e3SIlya Lesokhin } 2056808cf9e3SIlya Lesokhin 20575d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 205867edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 205967edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 206067edfef7SAndi Kleen * changes resulting in larger path MTUs. 206167edfef7SAndi Kleen * 20625d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 20635d424d5aSJohn Heffner * 1 if a probe was sent, 2064056834d9SIlpo Järvinen * -1 otherwise 2065056834d9SIlpo Järvinen */ 20665d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 20675d424d5aSJohn Heffner { 20685d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 206912a59abcSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 20705d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 20716b58e0a5SFan Du struct net *net = sock_net(sk); 20725d424d5aSJohn Heffner int probe_size; 207391cc17c0SIlpo Järvinen int size_needed; 207412a59abcSEric Dumazet int copy, len; 20755d424d5aSJohn Heffner int mss_now; 20766b58e0a5SFan Du int interval; 20775d424d5aSJohn Heffner 20785d424d5aSJohn Heffner /* Not currently probing/verifying, 20795d424d5aSJohn Heffner * not in recovery, 20805d424d5aSJohn Heffner * have enough cwnd, and 208112a59abcSEric Dumazet * not SACKing (the variable headers throw things off) 208212a59abcSEric Dumazet */ 208312a59abcSEric Dumazet if (likely(!icsk->icsk_mtup.enabled || 20845d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 20855d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 20865d424d5aSJohn Heffner tp->snd_cwnd < 11 || 208712a59abcSEric Dumazet tp->rx_opt.num_sacks || tp->rx_opt.dsack)) 20885d424d5aSJohn Heffner return -1; 20895d424d5aSJohn Heffner 20906b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 20916b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 20926b58e0a5SFan Du * smaller than a threshold, backoff from probing. 20936b58e0a5SFan Du */ 20940c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 20956b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 20966b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 209791cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 20986b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 209905cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 210005cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 210105cbc0dbSFan Du * probing process by not resetting search range to its orignal. 210205cbc0dbSFan Du */ 21036b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 210405cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 210505cbc0dbSFan Du /* Check whether enough time has elaplased for 210605cbc0dbSFan Du * another round of probing. 210705cbc0dbSFan Du */ 210805cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 21095d424d5aSJohn Heffner return -1; 21105d424d5aSJohn Heffner } 21115d424d5aSJohn Heffner 21125d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 21137f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 21145d424d5aSJohn Heffner return -1; 21155d424d5aSJohn Heffner 211691cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 21175d424d5aSJohn Heffner return -1; 211890840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 21195d424d5aSJohn Heffner return 0; 21205d424d5aSJohn Heffner 2121d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 2122d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 2123d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 21245d424d5aSJohn Heffner return -1; 21255d424d5aSJohn Heffner else 21265d424d5aSJohn Heffner return 0; 21275d424d5aSJohn Heffner } 21285d424d5aSJohn Heffner 2129808cf9e3SIlya Lesokhin if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) 2130808cf9e3SIlya Lesokhin return -1; 2131808cf9e3SIlya Lesokhin 21325d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 2133eb934478SEric Dumazet nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); 213451456b29SIan Morris if (!nskb) 21355d424d5aSJohn Heffner return -1; 21363ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 21373ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 21385d424d5aSJohn Heffner 2139fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 21405d424d5aSJohn Heffner 21415d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 21425d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 21434de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 21445d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 21455d424d5aSJohn Heffner nskb->csum = 0; 214698be9b12SEric Dumazet nskb->ip_summed = CHECKSUM_PARTIAL; 21475d424d5aSJohn Heffner 214850c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 21492b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 215050c4817eSIlpo Järvinen 21515d424d5aSJohn Heffner len = 0; 2152234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 21535d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 21545d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 21555d424d5aSJohn Heffner 21565d424d5aSJohn Heffner if (skb->len <= copy) { 21575d424d5aSJohn Heffner /* We've eaten all the data from this skb. 21585d424d5aSJohn Heffner * Throw it away. */ 21594de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2160808cf9e3SIlya Lesokhin /* If this is the last SKB we copy and eor is set 2161808cf9e3SIlya Lesokhin * we need to propagate it to the new skb. 2162808cf9e3SIlya Lesokhin */ 2163808cf9e3SIlya Lesokhin TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; 2164fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 21653ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 21665d424d5aSJohn Heffner } else { 21674de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2168a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 21695d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 21705d424d5aSJohn Heffner skb_pull(skb, copy); 21715d424d5aSJohn Heffner } else { 21725d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 21735bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 21745d424d5aSJohn Heffner } 21755d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 21765d424d5aSJohn Heffner } 21775d424d5aSJohn Heffner 21785d424d5aSJohn Heffner len += copy; 2179234b6860SIlpo Järvinen 2180234b6860SIlpo Järvinen if (len >= probe_size) 2181234b6860SIlpo Järvinen break; 21825d424d5aSJohn Heffner } 21835bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 21845d424d5aSJohn Heffner 21855d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 21867faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 21877faee5c0SEric Dumazet */ 21885d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 21895d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 21905d424d5aSJohn Heffner * effectively two packets. */ 21915d424d5aSJohn Heffner tp->snd_cwnd--; 219266f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 21935d424d5aSJohn Heffner 21945d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 21950e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 21960e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 21975d424d5aSJohn Heffner 21985d424d5aSJohn Heffner return 1; 21995d424d5aSJohn Heffner } 22005d424d5aSJohn Heffner 22015d424d5aSJohn Heffner return -1; 22025d424d5aSJohn Heffner } 22035d424d5aSJohn Heffner 2204218af599SEric Dumazet static bool tcp_pacing_check(const struct sock *sk) 2205218af599SEric Dumazet { 2206218af599SEric Dumazet return tcp_needs_internal_pacing(sk) && 220773a6bab5SEric Dumazet hrtimer_is_queued(&tcp_sk(sk)->pacing_timer); 2208218af599SEric Dumazet } 2209218af599SEric Dumazet 2210f9616c35SEric Dumazet /* TCP Small Queues : 2211f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2212f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2213f9616c35SEric Dumazet * This allows for : 2214f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2215f9616c35SEric Dumazet * - faster recovery 2216f9616c35SEric Dumazet * - high rates 2217f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2218f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2219f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2220f9616c35SEric Dumazet */ 2221f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2222f9616c35SEric Dumazet unsigned int factor) 2223f9616c35SEric Dumazet { 2224f9616c35SEric Dumazet unsigned int limit; 2225f9616c35SEric Dumazet 22263a9b76fdSEric Dumazet limit = max(2 * skb->truesize, sk->sk_pacing_rate >> sk->sk_pacing_shift); 22279184d8bbSEric Dumazet limit = min_t(u32, limit, 22289184d8bbSEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes); 2229f9616c35SEric Dumazet limit <<= factor; 2230f9616c35SEric Dumazet 223114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) { 223275c119afSEric Dumazet /* Always send skb if rtx queue is empty. 223375eefc6cSEric Dumazet * No need to wait for TX completion to call us back, 223475eefc6cSEric Dumazet * after softirq/tasklet schedule. 223575eefc6cSEric Dumazet * This helps when TX completions are delayed too much. 223675eefc6cSEric Dumazet */ 223775c119afSEric Dumazet if (tcp_rtx_queue_empty(sk)) 223875eefc6cSEric Dumazet return false; 223975eefc6cSEric Dumazet 22407aa5470cSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2241f9616c35SEric Dumazet /* It is possible TX completion already happened 2242f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2243f9616c35SEric Dumazet * test again the condition. 2244f9616c35SEric Dumazet */ 2245f9616c35SEric Dumazet smp_mb__after_atomic(); 224614afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) 2247f9616c35SEric Dumazet return true; 2248f9616c35SEric Dumazet } 2249f9616c35SEric Dumazet return false; 2250f9616c35SEric Dumazet } 2251f9616c35SEric Dumazet 225205b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 225305b055e8SFrancis Yan { 2254628174ccSEric Dumazet const u32 now = tcp_jiffies32; 2255efe967cdSArnd Bergmann enum tcp_chrono old = tp->chrono_type; 225605b055e8SFrancis Yan 2257efe967cdSArnd Bergmann if (old > TCP_CHRONO_UNSPEC) 2258efe967cdSArnd Bergmann tp->chrono_stat[old - 1] += now - tp->chrono_start; 225905b055e8SFrancis Yan tp->chrono_start = now; 226005b055e8SFrancis Yan tp->chrono_type = new; 226105b055e8SFrancis Yan } 226205b055e8SFrancis Yan 226305b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 226405b055e8SFrancis Yan { 226505b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 226605b055e8SFrancis Yan 226705b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 22680f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 22690f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 227005b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 227105b055e8SFrancis Yan */ 227205b055e8SFrancis Yan if (type > tp->chrono_type) 227305b055e8SFrancis Yan tcp_chrono_set(tp, type); 227405b055e8SFrancis Yan } 227505b055e8SFrancis Yan 227605b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 227705b055e8SFrancis Yan { 227805b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 227905b055e8SFrancis Yan 22800f87230dSFrancis Yan 22810f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 22820f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 22830f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 22840f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 22850f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 22860f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 22870f87230dSFrancis Yan */ 228875c119afSEric Dumazet if (tcp_rtx_and_write_queues_empty(sk)) 228905b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 22900f87230dSFrancis Yan else if (type == tp->chrono_type) 22910f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 229205b055e8SFrancis Yan } 229305b055e8SFrancis Yan 22941da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 22951da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 22961da177e4SLinus Torvalds * window for us. 22971da177e4SLinus Torvalds * 2298f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2299f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2300f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2301f8269a49SIlpo Järvinen * 23026ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 23036ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 23046ba8a3b1SNandita Dukkipati 2305a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2306a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 23071da177e4SLinus Torvalds */ 2308a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2309d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 23101da177e4SLinus Torvalds { 23111da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 231292df7b51SDavid S. Miller struct sk_buff *skb; 2313c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2314c1b4a7e6SDavid S. Miller int cwnd_quota; 23155d424d5aSJohn Heffner int result; 23165615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2317605ad7f1SEric Dumazet u32 max_segs; 23181da177e4SLinus Torvalds 2319c1b4a7e6SDavid S. Miller sent_pkts = 0; 23205d424d5aSJohn Heffner 2321ee1836aeSEric Dumazet tcp_mstamp_refresh(tp); 2322d5dd9175SIlpo Järvinen if (!push_one) { 23235d424d5aSJohn Heffner /* Do MTU probing. */ 2324d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2325d5dd9175SIlpo Järvinen if (!result) { 2326a2a385d6SEric Dumazet return false; 23275d424d5aSJohn Heffner } else if (result > 0) { 23285d424d5aSJohn Heffner sent_pkts = 1; 23295d424d5aSJohn Heffner } 2330d5dd9175SIlpo Järvinen } 23315d424d5aSJohn Heffner 2332ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2333fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2334c8ac3774SHerbert Xu unsigned int limit; 2335c8ac3774SHerbert Xu 2336218af599SEric Dumazet if (tcp_pacing_check(sk)) 2337218af599SEric Dumazet break; 2338218af599SEric Dumazet 23395bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2340c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2341c1b4a7e6SDavid S. Miller 23429d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 23437faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 2344*ab408b6dSEric Dumazet tcp_update_skb_after_send(sk, skb); 2345ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 23469d186cacSAndrey Vagin } 2347ec342325SAndrew Vagin 2348b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 23496ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 23506ba8a3b1SNandita Dukkipati if (push_one == 2) 23516ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 23526ba8a3b1SNandita Dukkipati cwnd_quota = 1; 23536ba8a3b1SNandita Dukkipati else 2354b68e9f85SHerbert Xu break; 23556ba8a3b1SNandita Dukkipati } 2356b68e9f85SHerbert Xu 23575615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 23585615f886SFrancis Yan is_rwnd_limited = true; 2359b68e9f85SHerbert Xu break; 23605615f886SFrancis Yan } 2361b68e9f85SHerbert Xu 2362d6a4e26aSEric Dumazet if (tso_segs == 1) { 2363aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2364aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2365aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2366aa93466bSDavid S. Miller break; 2367c1b4a7e6SDavid S. Miller } else { 2368ca8a2263SNeal Cardwell if (!push_one && 2369605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2370605ad7f1SEric Dumazet max_segs)) 2371aa93466bSDavid S. Miller break; 2372c1b4a7e6SDavid S. Miller } 2373aa93466bSDavid S. Miller 2374605ad7f1SEric Dumazet limit = mss_now; 2375d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2376605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2377605ad7f1SEric Dumazet min_t(unsigned int, 2378605ad7f1SEric Dumazet cwnd_quota, 2379605ad7f1SEric Dumazet max_segs), 2380605ad7f1SEric Dumazet nonagle); 2381605ad7f1SEric Dumazet 2382605ad7f1SEric Dumazet if (skb->len > limit && 238375c119afSEric Dumazet unlikely(tso_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, 238475c119afSEric Dumazet skb, limit, mss_now, gfp))) 2385605ad7f1SEric Dumazet break; 2386605ad7f1SEric Dumazet 2387f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 238846d3ceabSEric Dumazet break; 2389c9eeec26SEric Dumazet 2390d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 23911da177e4SLinus Torvalds break; 23921da177e4SLinus Torvalds 2393ec342325SAndrew Vagin repair: 23941da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 23951da177e4SLinus Torvalds * This call will increment packets_out. 23961da177e4SLinus Torvalds */ 239766f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 23981da177e4SLinus Torvalds 23991da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2400a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2401d5dd9175SIlpo Järvinen 2402d5dd9175SIlpo Järvinen if (push_one) 2403d5dd9175SIlpo Järvinen break; 24041da177e4SLinus Torvalds } 24051da177e4SLinus Torvalds 24065615f886SFrancis Yan if (is_rwnd_limited) 24075615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 24085615f886SFrancis Yan else 24095615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 24105615f886SFrancis Yan 2411aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2412684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2413684bad11SYuchung Cheng tp->prr_out += sent_pkts; 24146ba8a3b1SNandita Dukkipati 24156ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 24166ba8a3b1SNandita Dukkipati if (push_one != 2) 2417ed66dfafSNeal Cardwell tcp_schedule_loss_probe(sk, false); 2418d2e1339fSBendik Rønning Opstad is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); 2419ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2420a2a385d6SEric Dumazet return false; 24211da177e4SLinus Torvalds } 242275c119afSEric Dumazet return !tp->packets_out && !tcp_write_queue_empty(sk); 24236ba8a3b1SNandita Dukkipati } 24246ba8a3b1SNandita Dukkipati 2425ed66dfafSNeal Cardwell bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) 24266ba8a3b1SNandita Dukkipati { 24276ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 24286ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 2429a2815817SNeal Cardwell u32 timeout, rto_delta_us; 24302ae21cf5SEric Dumazet int early_retrans; 24316ba8a3b1SNandita Dukkipati 24326ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 24336ba8a3b1SNandita Dukkipati * finishes. 24346ba8a3b1SNandita Dukkipati */ 2435f9b99582SYuchung Cheng if (tp->fastopen_rsk) 24366ba8a3b1SNandita Dukkipati return false; 24376ba8a3b1SNandita Dukkipati 24382ae21cf5SEric Dumazet early_retrans = sock_net(sk)->ipv4.sysctl_tcp_early_retrans; 24396ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 2440b4f70c3dSNeal Cardwell * not in loss recovery, that are either limited by cwnd or application. 24416ba8a3b1SNandita Dukkipati */ 24422ae21cf5SEric Dumazet if ((early_retrans != 3 && early_retrans != 4) || 2443bec41a11SYuchung Cheng !tp->packets_out || !tcp_is_sack(tp) || 2444b4f70c3dSNeal Cardwell (icsk->icsk_ca_state != TCP_CA_Open && 2445b4f70c3dSNeal Cardwell icsk->icsk_ca_state != TCP_CA_CWR)) 24466ba8a3b1SNandita Dukkipati return false; 24476ba8a3b1SNandita Dukkipati 2448bb4d991aSYuchung Cheng /* Probe timeout is 2*rtt. Add minimum RTO to account 2449f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2450f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 24516ba8a3b1SNandita Dukkipati */ 2452bb4d991aSYuchung Cheng if (tp->srtt_us) { 2453bb4d991aSYuchung Cheng timeout = usecs_to_jiffies(tp->srtt_us >> 2); 24546ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 2455bb4d991aSYuchung Cheng timeout += TCP_RTO_MIN; 2456bb4d991aSYuchung Cheng else 2457bb4d991aSYuchung Cheng timeout += TCP_TIMEOUT_MIN; 2458bb4d991aSYuchung Cheng } else { 2459bb4d991aSYuchung Cheng timeout = TCP_TIMEOUT_INIT; 2460bb4d991aSYuchung Cheng } 24616ba8a3b1SNandita Dukkipati 2462a2815817SNeal Cardwell /* If the RTO formula yields an earlier time, then use that time. */ 2463ed66dfafSNeal Cardwell rto_delta_us = advancing_rto ? 2464ed66dfafSNeal Cardwell jiffies_to_usecs(inet_csk(sk)->icsk_rto) : 2465ed66dfafSNeal Cardwell tcp_rto_delta_us(sk); /* How far in future is RTO? */ 2466a2815817SNeal Cardwell if (rto_delta_us > 0) 2467a2815817SNeal Cardwell timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); 24686ba8a3b1SNandita Dukkipati 24696ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 24706ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 24716ba8a3b1SNandita Dukkipati return true; 24726ba8a3b1SNandita Dukkipati } 24736ba8a3b1SNandita Dukkipati 24741f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 24751f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 24761f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 24771f3279aeSEric Dumazet */ 24781f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 24791f3279aeSEric Dumazet const struct sk_buff *skb) 24801f3279aeSEric Dumazet { 248139bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2482c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 24831f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 24841f3279aeSEric Dumazet return true; 24851f3279aeSEric Dumazet } 24861f3279aeSEric Dumazet return false; 24871f3279aeSEric Dumazet } 24881f3279aeSEric Dumazet 2489b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 24906ba8a3b1SNandita Dukkipati * retransmit the last segment. 24916ba8a3b1SNandita Dukkipati */ 24926ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 24936ba8a3b1SNandita Dukkipati { 24949b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 24956ba8a3b1SNandita Dukkipati struct sk_buff *skb; 24966ba8a3b1SNandita Dukkipati int pcount; 24976ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 24986ba8a3b1SNandita Dukkipati 2499b340b264SYuchung Cheng skb = tcp_send_head(sk); 250075c119afSEric Dumazet if (skb && tcp_snd_wnd_test(tp, skb, mss)) { 2501b340b264SYuchung Cheng pcount = tp->packets_out; 2502b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2503b340b264SYuchung Cheng if (tp->packets_out > pcount) 2504b340b264SYuchung Cheng goto probe_sent; 25056ba8a3b1SNandita Dukkipati goto rearm_timer; 25066ba8a3b1SNandita Dukkipati } 250775c119afSEric Dumazet skb = skb_rb_last(&sk->tcp_rtx_queue); 25086ba8a3b1SNandita Dukkipati 25099b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 25109b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 25119b717a8dSNandita Dukkipati goto rearm_timer; 25129b717a8dSNandita Dukkipati 25136ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 25146ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 25156ba8a3b1SNandita Dukkipati goto rearm_timer; 25166ba8a3b1SNandita Dukkipati 25171f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 25181f3279aeSEric Dumazet goto rearm_timer; 25191f3279aeSEric Dumazet 25206ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 25216ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 25226ba8a3b1SNandita Dukkipati goto rearm_timer; 25236ba8a3b1SNandita Dukkipati 25246ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 252575c119afSEric Dumazet if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, 252675c119afSEric Dumazet (pcount - 1) * mss, mss, 25276cc55e09SOctavian Purdila GFP_ATOMIC))) 25286ba8a3b1SNandita Dukkipati goto rearm_timer; 252975c119afSEric Dumazet skb = skb_rb_next(skb); 25306ba8a3b1SNandita Dukkipati } 25316ba8a3b1SNandita Dukkipati 25326ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 25336ba8a3b1SNandita Dukkipati goto rearm_timer; 25346ba8a3b1SNandita Dukkipati 253510d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2536b340b264SYuchung Cheng goto rearm_timer; 25376ba8a3b1SNandita Dukkipati 25389b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 25399b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 25409b717a8dSNandita Dukkipati 2541b340b264SYuchung Cheng probe_sent: 2542c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2543fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2544fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2545b340b264SYuchung Cheng rearm_timer: 2546fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 25471da177e4SLinus Torvalds } 25481da177e4SLinus Torvalds 2549a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2550a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2551a762a980SDavid S. Miller * The socket must be locked by the caller. 2552a762a980SDavid S. Miller */ 25539e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 25549e412ba7SIlpo Järvinen int nonagle) 2555a762a980SDavid S. Miller { 2556726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2557726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2558726e07a8SIlpo Järvinen * all will be happy. 2559726e07a8SIlpo Järvinen */ 2560726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2561726e07a8SIlpo Järvinen return; 2562726e07a8SIlpo Järvinen 256399a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 25647450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 25659e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2566a762a980SDavid S. Miller } 2567a762a980SDavid S. Miller 2568c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2569c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2570c1b4a7e6SDavid S. Miller */ 2571c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2572c1b4a7e6SDavid S. Miller { 2573fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2574c1b4a7e6SDavid S. Miller 2575c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2576c1b4a7e6SDavid S. Miller 2577d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2578c1b4a7e6SDavid S. Miller } 2579c1b4a7e6SDavid S. Miller 25801da177e4SLinus Torvalds /* This function returns the amount that we can raise the 25811da177e4SLinus Torvalds * usable window based on the following constraints 25821da177e4SLinus Torvalds * 25831da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 25841da177e4SLinus Torvalds * 2. We limit memory per socket 25851da177e4SLinus Torvalds * 25861da177e4SLinus Torvalds * RFC 1122: 25871da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 25881da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 25891da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 25901da177e4SLinus Torvalds * 25911da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 25921da177e4SLinus Torvalds * it at least MSS bytes. 25931da177e4SLinus Torvalds * 25941da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 25951da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 25961da177e4SLinus Torvalds * 25971da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 25981da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 25991da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 26001da177e4SLinus Torvalds * window to always advance by a single byte. 26011da177e4SLinus Torvalds * 26021da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 26031da177e4SLinus Torvalds * then this will not be a problem. 26041da177e4SLinus Torvalds * 26051da177e4SLinus Torvalds * BSD seems to make the following compromise: 26061da177e4SLinus Torvalds * 26071da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 26081da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 26091da177e4SLinus Torvalds * then set the window to 0. 26101da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 26111da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 26121da177e4SLinus Torvalds * and from being larger than the largest representable value. 26131da177e4SLinus Torvalds * 26141da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 26151da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 26161da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 26171da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 26181da177e4SLinus Torvalds * because the pipeline is full. 26191da177e4SLinus Torvalds * 26201da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 26211da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 26221da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 26231da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 26241da177e4SLinus Torvalds * of having a fixed window size at almost all times. 26251da177e4SLinus Torvalds * 26261da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 26271da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 26281da177e4SLinus Torvalds * 26291da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 26301da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 26311da177e4SLinus Torvalds */ 26321da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 26331da177e4SLinus Torvalds { 2634463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 26351da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2636caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 26371da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 26381da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 26391da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 26401da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 26411da177e4SLinus Torvalds */ 2642463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 26431da177e4SLinus Torvalds int free_space = tcp_space(sk); 264486c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 264586c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 26461da177e4SLinus Torvalds int window; 26471da177e4SLinus Torvalds 264806425c30SEric Dumazet if (unlikely(mss > full_space)) { 26491da177e4SLinus Torvalds mss = full_space; 265006425c30SEric Dumazet if (mss <= 0) 265106425c30SEric Dumazet return 0; 265206425c30SEric Dumazet } 2653b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2654463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 26551da177e4SLinus Torvalds 2656b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 2657056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2658056834d9SIlpo Järvinen 4U * tp->advmss); 26591da177e4SLinus Torvalds 266086c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 266186c1a045SFlorian Westphal * increase it due to wscale. 266286c1a045SFlorian Westphal */ 266386c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 266486c1a045SFlorian Westphal 266586c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 266686c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 266786c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 266886c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 266986c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 267086c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 267186c1a045SFlorian Westphal */ 267286c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 26731da177e4SLinus Torvalds return 0; 26741da177e4SLinus Torvalds } 26751da177e4SLinus Torvalds 26761da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 26771da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 26781da177e4SLinus Torvalds 26791da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 26801da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 26811da177e4SLinus Torvalds */ 26821da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 26831da177e4SLinus Torvalds window = free_space; 26841da177e4SLinus Torvalds 26851da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 26861da177e4SLinus Torvalds * Import case: prevent zero window announcement if 26871da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 26881da177e4SLinus Torvalds */ 26891935299dSGao Feng window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); 26901da177e4SLinus Torvalds } else { 26911935299dSGao Feng window = tp->rcv_wnd; 26921da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 26931da177e4SLinus Torvalds * Window clamp already applied above. 26941da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 26951da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 26961da177e4SLinus Torvalds * and multiply from happening most of the time. 26971da177e4SLinus Torvalds * We also don't do any window rounding when the free space 26981da177e4SLinus Torvalds * is too small. 26991da177e4SLinus Torvalds */ 27001da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 27011935299dSGao Feng window = rounddown(free_space, mss); 270284565070SJohn Heffner else if (mss == full_space && 2703b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 270484565070SJohn Heffner window = free_space; 27051da177e4SLinus Torvalds } 27061da177e4SLinus Torvalds 27071da177e4SLinus Torvalds return window; 27081da177e4SLinus Torvalds } 27091da177e4SLinus Torvalds 2710cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 2711082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 2712082ac2d5SMartin KaFai Lau { 27130a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 27140a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 27150a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 2716082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 2717082ac2d5SMartin KaFai Lau 27180a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 2719082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 27202de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 27212de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 2722082ac2d5SMartin KaFai Lau } 2723082ac2d5SMartin KaFai Lau } 2724082ac2d5SMartin KaFai Lau 27254a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 2726f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 27271da177e4SLinus Torvalds { 27281da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 272975c119afSEric Dumazet struct sk_buff *next_skb = skb_rb_next(skb); 273013dde04fSWei Yongjun int next_skb_size; 27311da177e4SLinus Torvalds 2732058dc334SIlpo Järvinen next_skb_size = next_skb->len; 27331da177e4SLinus Torvalds 2734058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 27351da177e4SLinus Torvalds 2736f8071cdeSEric Dumazet if (next_skb_size) { 2737f8071cdeSEric Dumazet if (next_skb_size <= skb_availroom(skb)) 2738f8071cdeSEric Dumazet skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), 2739f8071cdeSEric Dumazet next_skb_size); 2740f8071cdeSEric Dumazet else if (!skb_shift(skb, next_skb, next_skb_size)) 2741f8071cdeSEric Dumazet return false; 2742f8071cdeSEric Dumazet } 27432b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, next_skb, skb); 2744a6963a6bSIlpo Järvinen 27451da177e4SLinus Torvalds /* Update sequence range on original skb. */ 27461da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 27471da177e4SLinus Torvalds 2748e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 27494de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 27501da177e4SLinus Torvalds 27511da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 27521da177e4SLinus Torvalds * packet counting does not break. 27531da177e4SLinus Torvalds */ 27544828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2755a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 2756b7689205SIlpo Järvinen 2757b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2758ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2759ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2760ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2761b7689205SIlpo Järvinen 2762797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2763797108d1SIlpo Järvinen 2764082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 2765082ac2d5SMartin KaFai Lau 276675c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(next_skb, sk); 2767f8071cdeSEric Dumazet return true; 27681da177e4SLinus Torvalds } 27691da177e4SLinus Torvalds 277067edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2771a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 27724a17fc3aSIlpo Järvinen { 27734a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2774a2a385d6SEric Dumazet return false; 27754a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2776a2a385d6SEric Dumazet return false; 27772331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 27784a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2779a2a385d6SEric Dumazet return false; 27804a17fc3aSIlpo Järvinen 2781a2a385d6SEric Dumazet return true; 27824a17fc3aSIlpo Järvinen } 27834a17fc3aSIlpo Järvinen 278467edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 278567edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 278667edfef7SAndi Kleen */ 27874a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 27884a17fc3aSIlpo Järvinen int space) 27894a17fc3aSIlpo Järvinen { 27904a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 27914a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2792a2a385d6SEric Dumazet bool first = true; 27934a17fc3aSIlpo Järvinen 2794e0a1e5b5SEric Dumazet if (!sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse) 27954a17fc3aSIlpo Järvinen return; 27964de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 27974a17fc3aSIlpo Järvinen return; 27984a17fc3aSIlpo Järvinen 279975c119afSEric Dumazet skb_rbtree_walk_from_safe(skb, tmp) { 28004a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 28014a17fc3aSIlpo Järvinen break; 28024a17fc3aSIlpo Järvinen 2803a643b5d4SMartin KaFai Lau if (!tcp_skb_can_collapse_to(to)) 2804a643b5d4SMartin KaFai Lau break; 2805a643b5d4SMartin KaFai Lau 28064a17fc3aSIlpo Järvinen space -= skb->len; 28074a17fc3aSIlpo Järvinen 28084a17fc3aSIlpo Järvinen if (first) { 2809a2a385d6SEric Dumazet first = false; 28104a17fc3aSIlpo Järvinen continue; 28114a17fc3aSIlpo Järvinen } 28124a17fc3aSIlpo Järvinen 28134a17fc3aSIlpo Järvinen if (space < 0) 28144a17fc3aSIlpo Järvinen break; 28154a17fc3aSIlpo Järvinen 28164a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 28174a17fc3aSIlpo Järvinen break; 28184a17fc3aSIlpo Järvinen 2819f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 2820f8071cdeSEric Dumazet break; 28214a17fc3aSIlpo Järvinen } 28224a17fc3aSIlpo Järvinen } 28234a17fc3aSIlpo Järvinen 28241da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 28251da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 28261da177e4SLinus Torvalds * error occurred which prevented the send. 28271da177e4SLinus Torvalds */ 282810d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 28291da177e4SLinus Torvalds { 28305d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 283110d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 28327d227cd2SSridhar Samudrala unsigned int cur_mss; 283310d3be56SEric Dumazet int diff, len, err; 28341da177e4SLinus Torvalds 283510d3be56SEric Dumazet 283610d3be56SEric Dumazet /* Inconclusive MTU probe */ 283710d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 28385d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 28395d424d5aSJohn Heffner 28401da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2841caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 28421da177e4SLinus Torvalds */ 284314afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > 2844ffb4d6c8SEric Dumazet min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), 2845ffb4d6c8SEric Dumazet sk->sk_sndbuf)) 28461da177e4SLinus Torvalds return -EAGAIN; 28471da177e4SLinus Torvalds 28481f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 28491f3279aeSEric Dumazet return -EBUSY; 28501f3279aeSEric Dumazet 28511da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 28527f582b24SEric Dumazet if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { 28537f582b24SEric Dumazet WARN_ON_ONCE(1); 28547f582b24SEric Dumazet return -EINVAL; 28557f582b24SEric Dumazet } 28561da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 28571da177e4SLinus Torvalds return -ENOMEM; 28581da177e4SLinus Torvalds } 28591da177e4SLinus Torvalds 28607d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 28617d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 28627d227cd2SSridhar Samudrala 28630c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 28647d227cd2SSridhar Samudrala 28651da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 28661da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 28671da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 28681da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 28691da177e4SLinus Torvalds */ 28709d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 28719d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 28721da177e4SLinus Torvalds return -EAGAIN; 28731da177e4SLinus Torvalds 287410d3be56SEric Dumazet len = cur_mss * segs; 287510d3be56SEric Dumazet if (skb->len > len) { 287675c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, 287775c119afSEric Dumazet cur_mss, GFP_ATOMIC)) 28781da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 287902276f3cSIlpo Järvinen } else { 2880c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2881c52e2421SEric Dumazet return -ENOMEM; 288210d3be56SEric Dumazet 288310d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 288410d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 288510d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 288610d3be56SEric Dumazet if (diff) 288710d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 288810d3be56SEric Dumazet if (skb->len < cur_mss) 288910d3be56SEric Dumazet tcp_retrans_try_collapse(sk, skb, cur_mss); 28901da177e4SLinus Torvalds } 28911da177e4SLinus Torvalds 289249213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 289349213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 289449213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 289549213555SDaniel Borkmann 2896678550c6SYuchung Cheng /* Update global and local TCP statistics. */ 2897678550c6SYuchung Cheng segs = tcp_skb_pcount(skb); 2898678550c6SYuchung Cheng TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 2899678550c6SYuchung Cheng if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 2900678550c6SYuchung Cheng __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 2901678550c6SYuchung Cheng tp->total_retrans += segs; 2902fb31c9b9SWei Wang tp->bytes_retrans += skb->len; 2903678550c6SYuchung Cheng 290450bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 290550bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 290650bceae9SThomas Graf * beyond what csum_start can cover. 290750bceae9SThomas Graf */ 290850bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 290950bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 291010a81980SEric Dumazet struct sk_buff *nskb; 291110a81980SEric Dumazet 2912e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 291310a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 2914c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2915117632e6SEric Dumazet -ENOBUFS; 2916e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 2917e2080072SEric Dumazet 29185889e2c0SYousuk Seung if (!err) { 2919*ab408b6dSEric Dumazet tcp_update_skb_after_send(sk, skb); 29205889e2c0SYousuk Seung tcp_rate_skb_sent(sk, skb); 29215889e2c0SYousuk Seung } 2922117632e6SEric Dumazet } else { 2923c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2924117632e6SEric Dumazet } 2925c84a5711SYuchung Cheng 2926a31ad29eSLawrence Brakmo if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) 2927a31ad29eSLawrence Brakmo tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, 2928a31ad29eSLawrence Brakmo TCP_SKB_CB(skb)->seq, segs, err); 2929a31ad29eSLawrence Brakmo 2930fc9f3501SEric Dumazet if (likely(!err)) { 2931c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2932e086101bSCong Wang trace_tcp_retransmit_skb(sk, skb); 2933678550c6SYuchung Cheng } else if (err != -EBUSY) { 2934678550c6SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 2935fc9f3501SEric Dumazet } 2936c84a5711SYuchung Cheng return err; 293793b174adSYuchung Cheng } 293893b174adSYuchung Cheng 293910d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 294093b174adSYuchung Cheng { 294193b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 294210d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 29431da177e4SLinus Torvalds 29441da177e4SLinus Torvalds if (err == 0) { 29451da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 29461da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2947e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 29481da177e4SLinus Torvalds } 29491da177e4SLinus Torvalds #endif 29501da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 29511da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 29521da177e4SLinus Torvalds 29531da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 29541da177e4SLinus Torvalds if (!tp->retrans_stamp) 29557faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 29561da177e4SLinus Torvalds 29571da177e4SLinus Torvalds } 29586e08d5e3SYuchung Cheng 29596e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 29606e08d5e3SYuchung Cheng tp->undo_retrans = 0; 29616e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 29621da177e4SLinus Torvalds return err; 29631da177e4SLinus Torvalds } 29641da177e4SLinus Torvalds 29651da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 29661da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 29671da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 29681da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 29691da177e4SLinus Torvalds */ 29701da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 29711da177e4SLinus Torvalds { 29726687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 2973b9f1f1ceSEric Dumazet struct sk_buff *skb, *rtx_head, *hole = NULL; 29741da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2975840a3cbeSYuchung Cheng u32 max_segs; 297661eb55f4SIlpo Järvinen int mib_idx; 29776a438bbeSStephen Hemminger 297845e77d31SIlpo Järvinen if (!tp->packets_out) 297945e77d31SIlpo Järvinen return; 298045e77d31SIlpo Järvinen 298175c119afSEric Dumazet rtx_head = tcp_rtx_queue_head(sk); 2982b9f1f1ceSEric Dumazet skb = tp->retransmit_skb_hint ?: rtx_head; 2983ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 298475c119afSEric Dumazet skb_rbtree_walk_from(skb) { 2985dca0aaf8SEric Dumazet __u8 sacked; 298610d3be56SEric Dumazet int segs; 29871da177e4SLinus Torvalds 2988218af599SEric Dumazet if (tcp_pacing_check(sk)) 2989218af599SEric Dumazet break; 2990218af599SEric Dumazet 29916a438bbeSStephen Hemminger /* we could do better than to assign each time */ 299251456b29SIan Morris if (!hole) 29936a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 29946a438bbeSStephen Hemminger 299510d3be56SEric Dumazet segs = tp->snd_cwnd - tcp_packets_in_flight(tp); 299610d3be56SEric Dumazet if (segs <= 0) 29971da177e4SLinus Torvalds return; 2998dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 2999a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 3000a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 3001a3d2e9f8SEric Dumazet */ 3002a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 30030e1c54c2SIlpo Järvinen 3004840a3cbeSYuchung Cheng if (tp->retrans_out >= tp->lost_out) { 3005006f582cSIlpo Järvinen break; 30060e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 300751456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 30080e1c54c2SIlpo Järvinen hole = skb; 300961eb55f4SIlpo Järvinen continue; 30101da177e4SLinus Torvalds 30110e1c54c2SIlpo Järvinen } else { 30120e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 30130e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 30140e1c54c2SIlpo Järvinen else 30150e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 30160e1c54c2SIlpo Järvinen } 30170e1c54c2SIlpo Järvinen 30180e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 301961eb55f4SIlpo Järvinen continue; 302040b215e5SPavel Emelyanov 3021f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 3022f9616c35SEric Dumazet return; 3023f9616c35SEric Dumazet 302410d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 30251da177e4SLinus Torvalds return; 302624ab6becSYuchung Cheng 3027de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 30281da177e4SLinus Torvalds 3029684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 3030a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 3031a262f0cdSNandita Dukkipati 303275c119afSEric Dumazet if (skb == rtx_head && 303357dde7f7SYuchung Cheng icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) 3034463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 30353f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 30363f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 30371da177e4SLinus Torvalds } 30381da177e4SLinus Torvalds } 30391da177e4SLinus Torvalds 3040d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 3041d83769a5SEric Dumazet * connection tear down and (memory) recovery. 3042845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 3043845704a5SEric Dumazet * or even be forced to close flow without any FIN. 3044a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 3045a6c5ea4cSEric Dumazet * with edge trigger epoll() 3046d83769a5SEric Dumazet */ 3047a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 3048d83769a5SEric Dumazet { 3049e805605cSJohannes Weiner int amt; 3050d83769a5SEric Dumazet 3051d83769a5SEric Dumazet if (size <= sk->sk_forward_alloc) 3052d83769a5SEric Dumazet return; 3053d83769a5SEric Dumazet amt = sk_mem_pages(size); 3054d83769a5SEric Dumazet sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; 3055e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 3056e805605cSJohannes Weiner 3057baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 3058baac50bbSJohannes Weiner mem_cgroup_charge_skmem(sk->sk_memcg, amt); 3059d83769a5SEric Dumazet } 3060d83769a5SEric Dumazet 3061845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 3062845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 30631da177e4SLinus Torvalds */ 30641da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 30651da177e4SLinus Torvalds { 3066845704a5SEric Dumazet struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); 30671da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 30681da177e4SLinus Torvalds 3069845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 3070845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 3071845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 3072845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 30731da177e4SLinus Torvalds */ 307475c119afSEric Dumazet if (!tskb && tcp_under_memory_pressure(sk)) 307575c119afSEric Dumazet tskb = skb_rb_last(&sk->tcp_rtx_queue); 307675c119afSEric Dumazet 307775c119afSEric Dumazet if (tskb) { 3078845704a5SEric Dumazet coalesce: 3079845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 3080845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 30811da177e4SLinus Torvalds tp->write_seq++; 308275c119afSEric Dumazet if (tcp_write_queue_empty(sk)) { 3083845704a5SEric Dumazet /* This means tskb was already sent. 3084845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 3085845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 3086845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 3087845704a5SEric Dumazet * does not change tp->snd_nxt. 3088845704a5SEric Dumazet */ 3089845704a5SEric Dumazet tp->snd_nxt++; 3090845704a5SEric Dumazet return; 3091845704a5SEric Dumazet } 30921da177e4SLinus Torvalds } else { 3093845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3094845704a5SEric Dumazet if (unlikely(!skb)) { 3095845704a5SEric Dumazet if (tskb) 3096845704a5SEric Dumazet goto coalesce; 3097845704a5SEric Dumazet return; 30981da177e4SLinus Torvalds } 3099e2080072SEric Dumazet INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); 3100d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3101a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 31021da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3103e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3104a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 31051da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 31061da177e4SLinus Torvalds } 3107845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 31081da177e4SLinus Torvalds } 31091da177e4SLinus Torvalds 31101da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 31111da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 31121da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 311365bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 31141da177e4SLinus Torvalds */ 3115dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 31161da177e4SLinus Torvalds { 31171da177e4SLinus Torvalds struct sk_buff *skb; 31181da177e4SLinus Torvalds 31197cc2b043SGao Feng TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 31207cc2b043SGao Feng 31211da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 31221da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 31231da177e4SLinus Torvalds if (!skb) { 31244e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 31251da177e4SLinus Torvalds return; 31261da177e4SLinus Torvalds } 31271da177e4SLinus Torvalds 31281da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 31291da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3130e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3131a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 31329a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 31331da177e4SLinus Torvalds /* Send it off. */ 3134dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 31354e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 3136c24b14c4SSong Liu 3137c24b14c4SSong Liu /* skb of trace_tcp_send_reset() keeps the skb that caused RST, 3138c24b14c4SSong Liu * skb here is different to the troublesome skb, so use NULL 3139c24b14c4SSong Liu */ 3140c24b14c4SSong Liu trace_tcp_send_reset(sk, NULL); 31411da177e4SLinus Torvalds } 31421da177e4SLinus Torvalds 314367edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 314467edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 31451da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 31461da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 31471da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 31481da177e4SLinus Torvalds */ 31491da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 31501da177e4SLinus Torvalds { 31511da177e4SLinus Torvalds struct sk_buff *skb; 31521da177e4SLinus Torvalds 315375c119afSEric Dumazet skb = tcp_rtx_queue_head(sk); 315451456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 315575c119afSEric Dumazet pr_err("%s: wrong queue state\n", __func__); 31561da177e4SLinus Torvalds return -EFAULT; 31571da177e4SLinus Torvalds } 31584de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 31591da177e4SLinus Torvalds if (skb_cloned(skb)) { 3160e2080072SEric Dumazet struct sk_buff *nskb; 3161e2080072SEric Dumazet 3162e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 3163e2080072SEric Dumazet nskb = skb_copy(skb, GFP_ATOMIC); 3164e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 316551456b29SIan Morris if (!nskb) 31661da177e4SLinus Torvalds return -ENOMEM; 3167e2080072SEric Dumazet INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); 316875c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(skb, sk); 3169f4a775d1SEric Dumazet __skb_header_release(nskb); 317075c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); 31713ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 31723ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 31731da177e4SLinus Torvalds skb = nskb; 31741da177e4SLinus Torvalds } 31751da177e4SLinus Torvalds 31764de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3177735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 31781da177e4SLinus Torvalds } 3179dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 31801da177e4SLinus Torvalds } 31811da177e4SLinus Torvalds 31824aea39c1SEric Dumazet /** 31834aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 31844aea39c1SEric Dumazet * sk: listener socket 31854aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 31864aea39c1SEric Dumazet * req: request_sock pointer 31874aea39c1SEric Dumazet * 31884aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 31894aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 31904aea39c1SEric Dumazet */ 31915d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3192e6b4d113SWilliam Allen Simpson struct request_sock *req, 3193ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3194b3d05147SEric Dumazet enum tcp_synack_type synack_type) 31951da177e4SLinus Torvalds { 31962e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 31975d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 319880f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 31995d062de7SEric Dumazet struct tcp_out_options opts; 32005d062de7SEric Dumazet struct sk_buff *skb; 3201bd0388aeSWilliam Allen Simpson int tcp_header_size; 32025d062de7SEric Dumazet struct tcphdr *th; 3203f5fff5dcSTom Quetchenbach int mss; 32041da177e4SLinus Torvalds 3205ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 32064aea39c1SEric Dumazet if (unlikely(!skb)) { 32074aea39c1SEric Dumazet dst_release(dst); 32081da177e4SLinus Torvalds return NULL; 32094aea39c1SEric Dumazet } 32101da177e4SLinus Torvalds /* Reserve space for headers. */ 32111da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 32121da177e4SLinus Torvalds 3213b3d05147SEric Dumazet switch (synack_type) { 3214b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 32159e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3216b3d05147SEric Dumazet break; 3217b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3218b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3219b3d05147SEric Dumazet * to avoid false sharing. 3220b3d05147SEric Dumazet */ 3221b3d05147SEric Dumazet break; 3222b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3223ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3224ca6fb065SEric Dumazet * cpu might call us concurrently. 3225ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3226ca6fb065SEric Dumazet */ 3227ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3228b3d05147SEric Dumazet break; 3229ca6fb065SEric Dumazet } 32304aea39c1SEric Dumazet skb_dst_set(skb, dst); 32311da177e4SLinus Torvalds 32323541f9e8SEric Dumazet mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3233f5fff5dcSTom Quetchenbach 323433ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 32358b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 32368b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 3237d3edd06eSEric Dumazet skb->skb_mstamp_ns = cookie_init_timestamp(req); 32388b5f12d0SFlorian Westphal else 32398b5f12d0SFlorian Westphal #endif 3240d3edd06eSEric Dumazet skb->skb_mstamp_ns = tcp_clock_ns(); 324180f03e27SEric Dumazet 324280f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 324380f03e27SEric Dumazet rcu_read_lock(); 3244fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 324580f03e27SEric Dumazet #endif 324658d607d3SEric Dumazet skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); 324760e2a778SUrsula Braun tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, 324860e2a778SUrsula Braun foc) + sizeof(*th); 324933ad798cSAdam Langley 3250aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3251aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 32521da177e4SLinus Torvalds 3253ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 32541da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 32551da177e4SLinus Torvalds th->syn = 1; 32561da177e4SLinus Torvalds th->ack = 1; 32576ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3258b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3259634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3260e05a90ecSJamal Hadi Salim skb->mark = ireq->ir_mark; 32613b117750SEric Dumazet skb->ip_summed = CHECKSUM_PARTIAL; 32623b117750SEric Dumazet th->seq = htonl(tcp_rsk(req)->snt_isn); 32638336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 32648336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 32651da177e4SLinus Torvalds 32661da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3267ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 32685d062de7SEric Dumazet tcp_options_write((__be32 *)(th + 1), NULL, &opts); 32691da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 327090bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3271cfb6eeb4SYOSHIFUJI Hideaki 3272cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3273cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 327480f03e27SEric Dumazet if (md5) 3275bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 327639f8e58eSEric Dumazet md5, req_to_sk(req), skb); 327780f03e27SEric Dumazet rcu_read_unlock(); 3278cfb6eeb4SYOSHIFUJI Hideaki #endif 3279cfb6eeb4SYOSHIFUJI Hideaki 3280b50edd78SEric Dumazet /* Do not fool tcpdump (if any), clean our debris */ 32812456e855SThomas Gleixner skb->tstamp = 0; 32821da177e4SLinus Torvalds return skb; 32831da177e4SLinus Torvalds } 32844bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 32851da177e4SLinus Torvalds 328681164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 328781164413SDaniel Borkmann { 328881164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 328981164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 329081164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 329181164413SDaniel Borkmann 329281164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 329381164413SDaniel Borkmann return; 329481164413SDaniel Borkmann 329581164413SDaniel Borkmann rcu_read_lock(); 329681164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 329781164413SDaniel Borkmann if (likely(ca && try_module_get(ca->owner))) { 329881164413SDaniel Borkmann module_put(icsk->icsk_ca_ops->owner); 329981164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 330081164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 330181164413SDaniel Borkmann } 330281164413SDaniel Borkmann rcu_read_unlock(); 330381164413SDaniel Borkmann } 330481164413SDaniel Borkmann 330567edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3306f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 33071da177e4SLinus Torvalds { 3308cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 33091da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 33101da177e4SLinus Torvalds __u8 rcv_wscale; 331113d3b1ebSLawrence Brakmo u32 rcv_wnd; 33121da177e4SLinus Torvalds 33131da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 33141da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 33151da177e4SLinus Torvalds */ 33165d2ed052SEric Dumazet tp->tcp_header_len = sizeof(struct tcphdr); 33175d2ed052SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_timestamps) 33185d2ed052SEric Dumazet tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; 33191da177e4SLinus Torvalds 3320cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 332100db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3322cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3323cfb6eeb4SYOSHIFUJI Hideaki #endif 3324cfb6eeb4SYOSHIFUJI Hideaki 33251da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 33261da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 33271da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 33281da177e4SLinus Torvalds tp->max_window = 0; 33295d424d5aSJohn Heffner tcp_mtup_init(sk); 33301da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 33311da177e4SLinus Torvalds 333281164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 333381164413SDaniel Borkmann 33341da177e4SLinus Torvalds if (!tp->window_clamp) 33351da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 33363541f9e8SEric Dumazet tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3337f5fff5dcSTom Quetchenbach 33381da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 33391da177e4SLinus Torvalds 3340e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3341e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3342e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3343e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3344e88c64f0SHagen Paul Pfeifer 334513d3b1ebSLawrence Brakmo rcv_wnd = tcp_rwnd_init_bpf(sk); 334613d3b1ebSLawrence Brakmo if (rcv_wnd == 0) 334713d3b1ebSLawrence Brakmo rcv_wnd = dst_metric(dst, RTAX_INITRWND); 334813d3b1ebSLawrence Brakmo 3349ceef9ab6SEric Dumazet tcp_select_initial_window(sk, tcp_full_space(sk), 33501da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 33511da177e4SLinus Torvalds &tp->rcv_wnd, 33521da177e4SLinus Torvalds &tp->window_clamp, 33539bb37ef0SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_window_scaling, 335431d12926Slaurent chavey &rcv_wscale, 335513d3b1ebSLawrence Brakmo rcv_wnd); 33561da177e4SLinus Torvalds 33571da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 33581da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 33591da177e4SLinus Torvalds 33601da177e4SLinus Torvalds sk->sk_err = 0; 33611da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 33621da177e4SLinus Torvalds tp->snd_wnd = 0; 3363ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 33647f582b24SEric Dumazet tcp_write_queue_purge(sk); 33651da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 33661da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 336733f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3368370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 3369ee995283SPavel Emelyanov 3370ee995283SPavel Emelyanov if (likely(!tp->repair)) 33711da177e4SLinus Torvalds tp->rcv_nxt = 0; 3372c7781a6eSAndrew Vagin else 337370eabf0eSEric Dumazet tp->rcv_tstamp = tcp_jiffies32; 3374ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 3375ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 33761da177e4SLinus Torvalds 33778550f328SLawrence Brakmo inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); 3378463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 33791da177e4SLinus Torvalds tcp_clear_retrans(tp); 33801da177e4SLinus Torvalds } 33811da177e4SLinus Torvalds 3382783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3383783237e8SYuchung Cheng { 3384783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3385783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3386783237e8SYuchung Cheng 3387783237e8SYuchung Cheng tcb->end_seq += skb->len; 3388f4a775d1SEric Dumazet __skb_header_release(skb); 3389783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 3390783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 3391783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 3392783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3393783237e8SYuchung Cheng } 3394783237e8SYuchung Cheng 3395783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3396783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3397783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3398783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3399783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3400783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3401783237e8SYuchung Cheng */ 3402783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3403783237e8SYuchung Cheng { 3404783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3405783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 3406065263f4SWei Wang int space, err = 0; 3407355a901eSEric Dumazet struct sk_buff *syn_data; 3408783237e8SYuchung Cheng 340967da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3410065263f4SWei Wang if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) 3411783237e8SYuchung Cheng goto fallback; 3412783237e8SYuchung Cheng 3413783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3414783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3415783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3416783237e8SYuchung Cheng */ 34173541f9e8SEric Dumazet tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); 34183541f9e8SEric Dumazet 34191b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3420783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3421783237e8SYuchung Cheng 3422f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3423f5ddcbbbSEric Dumazet 3424f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3425f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3426f5ddcbbbSEric Dumazet 3427eb934478SEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); 3428355a901eSEric Dumazet if (!syn_data) 3429783237e8SYuchung Cheng goto fallback; 3430355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3431355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 343207e100f9SEric Dumazet if (space) { 343307e100f9SEric Dumazet int copied = copy_from_iter(skb_put(syn_data, space), space, 343457be5bdaSAl Viro &fo->data->msg_iter); 343557be5bdaSAl Viro if (unlikely(!copied)) { 3436ba233b34SEric Dumazet tcp_skb_tsorted_anchor_cleanup(syn_data); 3437355a901eSEric Dumazet kfree_skb(syn_data); 3438783237e8SYuchung Cheng goto fallback; 3439783237e8SYuchung Cheng } 344057be5bdaSAl Viro if (copied != space) { 344157be5bdaSAl Viro skb_trim(syn_data, copied); 344257be5bdaSAl Viro space = copied; 344357be5bdaSAl Viro } 344407e100f9SEric Dumazet } 3445355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3446355a901eSEric Dumazet if (space == fo->size) 3447355a901eSEric Dumazet fo->data = NULL; 3448355a901eSEric Dumazet fo->copied = space; 3449783237e8SYuchung Cheng 3450355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 34510f87230dSFrancis Yan if (syn_data->len) 34520f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3453355a901eSEric Dumazet 3454355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3455355a901eSEric Dumazet 3456d3edd06eSEric Dumazet syn->skb_mstamp_ns = syn_data->skb_mstamp_ns; 3457355a901eSEric Dumazet 3458355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3459355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3460355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3461355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3462431a9124SEric Dumazet */ 3463355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3464355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3465355a901eSEric Dumazet if (!err) { 346667da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 346775c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); 3468f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3469783237e8SYuchung Cheng goto done; 3470783237e8SYuchung Cheng } 3471783237e8SYuchung Cheng 347275c119afSEric Dumazet /* data was not sent, put it in write_queue */ 347375c119afSEric Dumazet __skb_queue_tail(&sk->sk_write_queue, syn_data); 3474b5b7db8dSEric Dumazet tp->packets_out -= tcp_skb_pcount(syn_data); 3475b5b7db8dSEric Dumazet 3476783237e8SYuchung Cheng fallback: 3477783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3478783237e8SYuchung Cheng if (fo->cookie.len > 0) 3479783237e8SYuchung Cheng fo->cookie.len = 0; 3480783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3481783237e8SYuchung Cheng if (err) 3482783237e8SYuchung Cheng tp->syn_fastopen = 0; 3483783237e8SYuchung Cheng done: 3484783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3485783237e8SYuchung Cheng return err; 3486783237e8SYuchung Cheng } 3487783237e8SYuchung Cheng 348867edfef7SAndi Kleen /* Build a SYN and send it off. */ 34891da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 34901da177e4SLinus Torvalds { 34911da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34921da177e4SLinus Torvalds struct sk_buff *buff; 3493ee586811SEric Paris int err; 34941da177e4SLinus Torvalds 3495de525be2SLawrence Brakmo tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); 34968ba60924SEric Dumazet 34978ba60924SEric Dumazet if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 34988ba60924SEric Dumazet return -EHOSTUNREACH; /* Routing failure or similar. */ 34998ba60924SEric Dumazet 35001da177e4SLinus Torvalds tcp_connect_init(sk); 35011da177e4SLinus Torvalds 35022b916477SAndrey Vagin if (unlikely(tp->repair)) { 35032b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 35042b916477SAndrey Vagin return 0; 35052b916477SAndrey Vagin } 35062b916477SAndrey Vagin 3507eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); 3508355a901eSEric Dumazet if (unlikely(!buff)) 35091da177e4SLinus Torvalds return -ENOBUFS; 35101da177e4SLinus Torvalds 3511a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 35129a568de4SEric Dumazet tcp_mstamp_refresh(tp); 35139a568de4SEric Dumazet tp->retrans_stamp = tcp_time_stamp(tp); 3514783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3515735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 351675c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 35171da177e4SLinus Torvalds 3518783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3519783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3520783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3521ee586811SEric Paris if (err == -ECONNREFUSED) 3522ee586811SEric Paris return err; 3523bd37a088SWei Yongjun 3524bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3525bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3526bd37a088SWei Yongjun */ 3527bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3528bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 3529b5b7db8dSEric Dumazet buff = tcp_send_head(sk); 3530b5b7db8dSEric Dumazet if (unlikely(buff)) { 3531b5b7db8dSEric Dumazet tp->snd_nxt = TCP_SKB_CB(buff)->seq; 3532b5b7db8dSEric Dumazet tp->pushed_seq = TCP_SKB_CB(buff)->seq; 3533b5b7db8dSEric Dumazet } 353481cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 35351da177e4SLinus Torvalds 35361da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 35373f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 35383f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 35391da177e4SLinus Torvalds return 0; 35401da177e4SLinus Torvalds } 35414bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 35421da177e4SLinus Torvalds 35431da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 35441da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 35451da177e4SLinus Torvalds * for details. 35461da177e4SLinus Torvalds */ 35471da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 35481da177e4SLinus Torvalds { 3549463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3550463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 35511da177e4SLinus Torvalds unsigned long timeout; 35521da177e4SLinus Torvalds 35531da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3554463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 35551da177e4SLinus Torvalds int max_ato = HZ / 2; 35561da177e4SLinus Torvalds 3557056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3558056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 35591da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 35601da177e4SLinus Torvalds 35611da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 35621da177e4SLinus Torvalds 35631da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3564463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 35651da177e4SLinus Torvalds * directly. 35661da177e4SLinus Torvalds */ 3567740b0f18SEric Dumazet if (tp->srtt_us) { 3568740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3569740b0f18SEric Dumazet TCP_DELACK_MIN); 35701da177e4SLinus Torvalds 35711da177e4SLinus Torvalds if (rtt < max_ato) 35721da177e4SLinus Torvalds max_ato = rtt; 35731da177e4SLinus Torvalds } 35741da177e4SLinus Torvalds 35751da177e4SLinus Torvalds ato = min(ato, max_ato); 35761da177e4SLinus Torvalds } 35771da177e4SLinus Torvalds 35781da177e4SLinus Torvalds /* Stay within the limit we were given */ 35791da177e4SLinus Torvalds timeout = jiffies + ato; 35801da177e4SLinus Torvalds 35811da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3582463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 35831da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 35841da177e4SLinus Torvalds * send ACK now. 35851da177e4SLinus Torvalds */ 3586463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3587463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 35881da177e4SLinus Torvalds tcp_send_ack(sk); 35891da177e4SLinus Torvalds return; 35901da177e4SLinus Torvalds } 35911da177e4SLinus Torvalds 3592463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3593463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 35941da177e4SLinus Torvalds } 3595463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3596463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3597463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 35981da177e4SLinus Torvalds } 35991da177e4SLinus Torvalds 36001da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 36012987babbSYuchung Cheng void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) 36021da177e4SLinus Torvalds { 36031da177e4SLinus Torvalds struct sk_buff *buff; 36041da177e4SLinus Torvalds 3605058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3606058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3607058dc334SIlpo Järvinen return; 3608058dc334SIlpo Järvinen 36091da177e4SLinus Torvalds /* We are not putting this on the write queue, so 36101da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 36111da177e4SLinus Torvalds * sock. 36121da177e4SLinus Torvalds */ 36137450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 36147450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 36157450aaf6SEric Dumazet if (unlikely(!buff)) { 3616463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3617463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 36183f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 36193f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 36201da177e4SLinus Torvalds return; 36211da177e4SLinus Torvalds } 36221da177e4SLinus Torvalds 36231da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 36241da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3625a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 36261da177e4SLinus Torvalds 362798781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 362898781965SEric Dumazet * too much. 362998781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 363098781965SEric Dumazet */ 363198781965SEric Dumazet skb_set_tcp_pure_ack(buff); 363298781965SEric Dumazet 36331da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 36342987babbSYuchung Cheng __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); 36351da177e4SLinus Torvalds } 363627cde44aSYuchung Cheng EXPORT_SYMBOL_GPL(__tcp_send_ack); 36372987babbSYuchung Cheng 36382987babbSYuchung Cheng void tcp_send_ack(struct sock *sk) 36392987babbSYuchung Cheng { 36402987babbSYuchung Cheng __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); 36411da177e4SLinus Torvalds } 36421da177e4SLinus Torvalds 36431da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 36441da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 36451da177e4SLinus Torvalds * 36461da177e4SLinus Torvalds * Question: what should we make while urgent mode? 36471da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 36481da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 36491da177e4SLinus Torvalds * 36501da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 36511da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 36521da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 36531da177e4SLinus Torvalds */ 3654e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 36551da177e4SLinus Torvalds { 36561da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 36571da177e4SLinus Torvalds struct sk_buff *skb; 36581da177e4SLinus Torvalds 36591da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 36607450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 36617450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 366251456b29SIan Morris if (!skb) 36631da177e4SLinus Torvalds return -1; 36641da177e4SLinus Torvalds 36651da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 36661da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 36671da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 36681da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 36691da177e4SLinus Torvalds * send it. 36701da177e4SLinus Torvalds */ 3671a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 3672e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 36737450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 36741da177e4SLinus Torvalds } 36751da177e4SLinus Torvalds 3676385e2070SEric Dumazet /* Called from setsockopt( ... TCP_REPAIR ) */ 3677ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3678ee995283SPavel Emelyanov { 3679ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3680ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 36819a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 3682e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 3683ee995283SPavel Emelyanov } 3684ee995283SPavel Emelyanov } 3685ee995283SPavel Emelyanov 368667edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 3687e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 36881da177e4SLinus Torvalds { 36891da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 36901da177e4SLinus Torvalds struct sk_buff *skb; 36911da177e4SLinus Torvalds 3692058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3693058dc334SIlpo Järvinen return -1; 3694058dc334SIlpo Järvinen 369500db4124SIan Morris skb = tcp_send_head(sk); 369600db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 36971da177e4SLinus Torvalds int err; 36980c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 369990840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 37001da177e4SLinus Torvalds 37011da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 37021da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 37031da177e4SLinus Torvalds 37041da177e4SLinus Torvalds /* We are probing the opening of a window 37051da177e4SLinus Torvalds * but the window size is != 0 37061da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 37071da177e4SLinus Torvalds */ 37081da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 37091da177e4SLinus Torvalds skb->len > mss) { 37101da177e4SLinus Torvalds seg_size = min(seg_size, mss); 37114de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 371275c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, 371375c119afSEric Dumazet skb, seg_size, mss, GFP_ATOMIC)) 37141da177e4SLinus Torvalds return -1; 37151da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 37165bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 37171da177e4SLinus Torvalds 37184de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3719dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 372066f5fe62SIlpo Järvinen if (!err) 372166f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 37221da177e4SLinus Torvalds return err; 37231da177e4SLinus Torvalds } else { 372433f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 3725e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 3726e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 37271da177e4SLinus Torvalds } 37281da177e4SLinus Torvalds } 37291da177e4SLinus Torvalds 37301da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 37311da177e4SLinus Torvalds * a partial packet else a zero probe. 37321da177e4SLinus Torvalds */ 37331da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 37341da177e4SLinus Torvalds { 3735463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 37361da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3737c6214a97SNikolay Borisov struct net *net = sock_net(sk); 3738fcdd1cf4SEric Dumazet unsigned long probe_max; 37391da177e4SLinus Torvalds int err; 37401da177e4SLinus Torvalds 3741e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 37421da177e4SLinus Torvalds 374375c119afSEric Dumazet if (tp->packets_out || tcp_write_queue_empty(sk)) { 37441da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 37456687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3746463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 37471da177e4SLinus Torvalds return; 37481da177e4SLinus Torvalds } 37491da177e4SLinus Torvalds 37501da177e4SLinus Torvalds if (err <= 0) { 3751c6214a97SNikolay Borisov if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) 3752463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 37536687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3754fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 37551da177e4SLinus Torvalds } else { 37561da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 37576687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 37581da177e4SLinus Torvalds * Let local senders to fight for local resources. 37591da177e4SLinus Torvalds * 37601da177e4SLinus Torvalds * Use accumulated backoff yet. 37611da177e4SLinus Torvalds */ 37626687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 37636687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3764fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 37651da177e4SLinus Torvalds } 3766fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 376721c8fe99SEric Dumazet tcp_probe0_when(sk, probe_max), 3768fcdd1cf4SEric Dumazet TCP_RTO_MAX); 37691da177e4SLinus Torvalds } 37705db92c99SOctavian Purdila 3771ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 37725db92c99SOctavian Purdila { 37735db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 37745db92c99SOctavian Purdila struct flowi fl; 37755db92c99SOctavian Purdila int res; 37765db92c99SOctavian Purdila 377758d607d3SEric Dumazet tcp_rsk(req)->txhash = net_tx_rndhash(); 3778b3d05147SEric Dumazet res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); 37795db92c99SOctavian Purdila if (!res) { 378090bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 378102a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 37827e32b443SYuchung Cheng if (unlikely(tcp_passive_fastopen(sk))) 37837e32b443SYuchung Cheng tcp_sk(sk)->total_retrans++; 3784cf34ce3dSSong Liu trace_tcp_retransmit_synack(sk, req); 37855db92c99SOctavian Purdila } 37865db92c99SOctavian Purdila return res; 37875db92c99SOctavian Purdila } 37885db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3789