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> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 46ab32ea5dSBrian Haley int sysctl_tcp_retrans_collapse __read_mostly = 1; 471da177e4SLinus Torvalds 4815d99e02SRick Jones /* People can turn this on to work with those rare, broken TCPs that 4915d99e02SRick Jones * interpret the window field as a signed quantity. 5015d99e02SRick Jones */ 51ab32ea5dSBrian Haley int sysctl_tcp_workaround_signed_windows __read_mostly = 0; 5215d99e02SRick Jones 53c39c4c6aSWei Liu /* Default TSQ limit of four TSO segments */ 54c39c4c6aSWei Liu int sysctl_tcp_limit_output_bytes __read_mostly = 262144; 5546d3ceabSEric Dumazet 561da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 571da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 581da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 591da177e4SLinus Torvalds */ 60ab32ea5dSBrian Haley int sysctl_tcp_tso_win_divisor __read_mostly = 3; 611da177e4SLinus Torvalds 6235089bb2SDavid S. Miller /* By default, RFC2861 behavior. */ 63ab32ea5dSBrian Haley int sysctl_tcp_slow_start_after_idle __read_mostly = 1; 6435089bb2SDavid S. Miller 6546d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6646d3ceabSEric Dumazet int push_one, gfp_t gfp); 67519855c5SWilliam Allen Simpson 6867edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 69cf533ea5SEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) 706ff03ac3SIlpo Järvinen { 716ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 726ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7366f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 749e412ba7SIlpo Järvinen 75fe067e8aSDavid S. Miller tcp_advance_send_head(sk, skb); 761da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 778512430eSIlpo Järvinen 7866f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 79bec41a11SYuchung Cheng if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) 80750ea2baSYuchung Cheng tcp_rearm_rto(sk); 81f19c29e3SYuchung Cheng 82f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 83f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 846a5dc9e5SEric Dumazet } 851da177e4SLinus Torvalds 86a4ecb15aSCui, Cheng /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one 87a4ecb15aSCui, Cheng * window scaling factor due to loss of precision. 881da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 891da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 901da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 911da177e4SLinus Torvalds * invalid. OK, let's make this for now: 921da177e4SLinus Torvalds */ 93cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 941da177e4SLinus Torvalds { 95cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 969e412ba7SIlpo Järvinen 97a4ecb15aSCui, Cheng if (!before(tcp_wnd_end(tp), tp->snd_nxt) || 98a4ecb15aSCui, Cheng (tp->rx_opt.wscale_ok && 99a4ecb15aSCui, Cheng ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) 1001da177e4SLinus Torvalds return tp->snd_nxt; 1011da177e4SLinus Torvalds else 10290840defSIlpo Järvinen return tcp_wnd_end(tp); 1031da177e4SLinus Torvalds } 1041da177e4SLinus Torvalds 1051da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1061da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1071da177e4SLinus Torvalds * 1081da177e4SLinus Torvalds * 1. It is independent of path mtu. 1091da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1101da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1111da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1121da177e4SLinus Torvalds * large MSS. 1131da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1141da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1151da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1161da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1171da177e4SLinus Torvalds * probably even Jumbo". 1181da177e4SLinus Torvalds */ 1191da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 122cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1231da177e4SLinus Torvalds int mss = tp->advmss; 1241da177e4SLinus Torvalds 1250dbaee3bSDavid S. Miller if (dst) { 1260dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1270dbaee3bSDavid S. Miller 1280dbaee3bSDavid S. Miller if (metric < mss) { 1290dbaee3bSDavid S. Miller mss = metric; 1301da177e4SLinus Torvalds tp->advmss = mss; 1311da177e4SLinus Torvalds } 1320dbaee3bSDavid S. Miller } 1331da177e4SLinus Torvalds 1341da177e4SLinus Torvalds return (__u16)mss; 1351da177e4SLinus Torvalds } 1361da177e4SLinus Torvalds 1371da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1386f021c62SEric Dumazet * This is the first part of cwnd validation mechanism. 1396f021c62SEric Dumazet */ 1406f021c62SEric Dumazet void tcp_cwnd_restart(struct sock *sk, s32 delta) 1411da177e4SLinus Torvalds { 142463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1436f021c62SEric Dumazet u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); 1441da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1451da177e4SLinus Torvalds 1466687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1471da177e4SLinus Torvalds 1486687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1491da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1501da177e4SLinus Torvalds 151463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1521da177e4SLinus Torvalds cwnd >>= 1; 1531da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 154c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1551da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1561da177e4SLinus Torvalds } 1571da177e4SLinus Torvalds 15867edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 15940efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 160cf533ea5SEric Dumazet struct sock *sk) 1611da177e4SLinus Torvalds { 162463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 163d635fbe2SEric Dumazet const u32 now = tcp_jiffies32; 1641da177e4SLinus Torvalds 16505c5a46dSNeal Cardwell if (tcp_packets_in_flight(tp) == 0) 16605c5a46dSNeal Cardwell tcp_ca_event(sk, CA_EVENT_TX_START); 16705c5a46dSNeal Cardwell 1681da177e4SLinus Torvalds tp->lsndtime = now; 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds /* If it is a reply for ato after last received 1711da177e4SLinus Torvalds * packet, enter pingpong mode. 1721da177e4SLinus Torvalds */ 1732251ae46SJon Maxwell if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 174463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1751da177e4SLinus Torvalds } 1761da177e4SLinus Torvalds 17767edfef7SAndi Kleen /* Account for an ACK we sent. */ 17840efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1791da177e4SLinus Torvalds { 180463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 181463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1821da177e4SLinus Torvalds } 1831da177e4SLinus Torvalds 18485f16525SYuchung Cheng 18585f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 18685f16525SYuchung Cheng { 18785f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 1889ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 18985f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 19085f16525SYuchung Cheng * limit when mss is larger than 1460. 19185f16525SYuchung Cheng */ 19285f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 19385f16525SYuchung Cheng 19485f16525SYuchung Cheng if (mss > 1460) 19585f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 19685f16525SYuchung Cheng return init_rwnd; 19785f16525SYuchung Cheng } 19885f16525SYuchung Cheng 1991da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2001da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2011da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2021da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2031da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2041da177e4SLinus Torvalds * This MUST be enforced by all callers. 2051da177e4SLinus Torvalds */ 2061da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 2071da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 20831d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 20931d12926Slaurent chavey __u32 init_rcv_wnd) 2101da177e4SLinus Torvalds { 2111da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2121da177e4SLinus Torvalds 2131da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2141da177e4SLinus Torvalds if (*window_clamp == 0) 215589c49cbSGao Feng (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); 2161da177e4SLinus Torvalds space = min(*window_clamp, space); 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2191da177e4SLinus Torvalds if (space > mss) 220589c49cbSGao Feng space = rounddown(space, mss); 2211da177e4SLinus Torvalds 2221da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22315d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22415d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 22515d99e02SRick Jones * we will truncate our initial window offering to 32K-1 22615d99e02SRick Jones * unless the remote has sent us a window scaling option, 22715d99e02SRick Jones * which we interpret as a sign the remote TCP is not 22815d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2291da177e4SLinus Torvalds */ 23015d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2311da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23215d99e02SRick Jones else 23315d99e02SRick Jones (*rcv_wnd) = space; 23415d99e02SRick Jones 2351da177e4SLinus Torvalds (*rcv_wscale) = 0; 2361da177e4SLinus Torvalds if (wscale_ok) { 237589c49cbSGao Feng /* Set window scaling on max possible window */ 238f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_tcp_rmem[2]); 239f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_rmem_max); 240316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 241589c49cbSGao Feng while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) { 2421da177e4SLinus Torvalds space >>= 1; 2431da177e4SLinus Torvalds (*rcv_wscale)++; 2441da177e4SLinus Torvalds } 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 24885f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 24985f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 250b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 254589c49cbSGao Feng (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); 2551da177e4SLinus Torvalds } 2564bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2571da177e4SLinus Torvalds 2581da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2591da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2601da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2611da177e4SLinus Torvalds * frame. 2621da177e4SLinus Torvalds */ 26340efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2641da177e4SLinus Torvalds { 2651da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2668e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2671da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2681da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2691da177e4SLinus Torvalds 2701da177e4SLinus Torvalds /* Never shrink the offered window */ 2711da177e4SLinus Torvalds if (new_win < cur_win) { 2721da177e4SLinus Torvalds /* Danger Will Robinson! 2731da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2741da177e4SLinus Torvalds * we will not be able to advertise a zero 2751da177e4SLinus Torvalds * window in time. --DaveM 2761da177e4SLinus Torvalds * 2771da177e4SLinus Torvalds * Relax Will Robinson. 2781da177e4SLinus Torvalds */ 2798e165e20SFlorian Westphal if (new_win == 0) 2808e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2818e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 282607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2831da177e4SLinus Torvalds } 2841da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2851da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2861da177e4SLinus Torvalds 2871da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2881da177e4SLinus Torvalds * scaled window. 2891da177e4SLinus Torvalds */ 29015d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2911da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2921da177e4SLinus Torvalds else 2931da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2941da177e4SLinus Torvalds 2951da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2961da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2971da177e4SLinus Torvalds 2981da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 2998e165e20SFlorian Westphal if (new_win == 0) { 3001da177e4SLinus Torvalds tp->pred_flags = 0; 3018e165e20SFlorian Westphal if (old_win) 3028e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3038e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3048e165e20SFlorian Westphal } else if (old_win == 0) { 3058e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3068e165e20SFlorian Westphal } 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds return new_win; 3091da177e4SLinus Torvalds } 3101da177e4SLinus Torvalds 31167edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 312735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 313bdf1ee5dSIlpo Järvinen { 31430e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 31530e502a3SDaniel Borkmann 3164de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 317bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3184de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 319*91b5b21cSLawrence Brakmo else if (tcp_ca_needs_ecn(sk) || 320*91b5b21cSLawrence Brakmo tcp_bpf_ca_needs_ecn(sk)) 32130e502a3SDaniel Borkmann INET_ECN_xmit(sk); 322bdf1ee5dSIlpo Järvinen } 323bdf1ee5dSIlpo Järvinen 32467edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 325735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 326bdf1ee5dSIlpo Järvinen { 327bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 328*91b5b21cSLawrence Brakmo bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); 329f7b3bec6SFlorian Westphal bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || 330*91b5b21cSLawrence Brakmo tcp_ca_needs_ecn(sk) || bpf_needs_ecn; 331f7b3bec6SFlorian Westphal 332f7b3bec6SFlorian Westphal if (!use_ecn) { 333f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 334f7b3bec6SFlorian Westphal 335f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 336f7b3bec6SFlorian Westphal use_ecn = true; 337f7b3bec6SFlorian Westphal } 338bdf1ee5dSIlpo Järvinen 339bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 340f7b3bec6SFlorian Westphal 341f7b3bec6SFlorian Westphal if (use_ecn) { 3424de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 343bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 344*91b5b21cSLawrence Brakmo if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) 34530e502a3SDaniel Borkmann INET_ECN_xmit(sk); 346bdf1ee5dSIlpo Järvinen } 347bdf1ee5dSIlpo Järvinen } 348bdf1ee5dSIlpo Järvinen 34949213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 35049213555SDaniel Borkmann { 35149213555SDaniel Borkmann if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) 35249213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 35349213555SDaniel Borkmann * SYN ACK is ultimatively being received. 35449213555SDaniel Borkmann */ 35549213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 35649213555SDaniel Borkmann } 35749213555SDaniel Borkmann 358735d3831SFlorian Westphal static void 3596ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 360bdf1ee5dSIlpo Järvinen { 3616ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 362bdf1ee5dSIlpo Järvinen th->ece = 1; 363bdf1ee5dSIlpo Järvinen } 364bdf1ee5dSIlpo Järvinen 36567edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 36667edfef7SAndi Kleen * be sent. 36767edfef7SAndi Kleen */ 368735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 369ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 370bdf1ee5dSIlpo Järvinen { 371bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 372bdf1ee5dSIlpo Järvinen 373bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 374bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 375bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 376bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 377bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 378bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 379bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 380ea1627c2SEric Dumazet th->cwr = 1; 381bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 382bdf1ee5dSIlpo Järvinen } 38330e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 384bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 385bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 386bdf1ee5dSIlpo Järvinen } 387bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 388ea1627c2SEric Dumazet th->ece = 1; 389bdf1ee5dSIlpo Järvinen } 390bdf1ee5dSIlpo Järvinen } 391bdf1ee5dSIlpo Järvinen 392e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 393e870a8efSIlpo Järvinen * auto increment end seqno. 394e870a8efSIlpo Järvinen */ 395e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 396e870a8efSIlpo Järvinen { 3972e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 398e870a8efSIlpo Järvinen skb->csum = 0; 399e870a8efSIlpo Järvinen 4004de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 401e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 402e870a8efSIlpo Järvinen 403cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 404e870a8efSIlpo Järvinen 405e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 406a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 407e870a8efSIlpo Järvinen seq++; 408e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 409e870a8efSIlpo Järvinen } 410e870a8efSIlpo Järvinen 411a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 41233f5f57eSIlpo Järvinen { 41333f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41433f5f57eSIlpo Järvinen } 41533f5f57eSIlpo Järvinen 41633ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 41733ad798cSAdam Langley #define OPTION_TS (1 << 1) 41833ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 41989e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4202100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 42133ad798cSAdam Langley 42233ad798cSAdam Langley struct tcp_out_options { 4232100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4242100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 42533ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 42633ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 427bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 428bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4292100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4302100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 43133ad798cSAdam Langley }; 43233ad798cSAdam Langley 43367edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 43467edfef7SAndi Kleen * 43567edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 436fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 437fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4388e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 439fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 440fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 441fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 442fd6149d3SIlpo Järvinen * 443fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 444fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 445fd6149d3SIlpo Järvinen */ 44633ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 447bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 448bd0388aeSWilliam Allen Simpson { 4492100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 450bd0388aeSWilliam Allen Simpson 451bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4521a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4531a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 454bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 455bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 45633ad798cSAdam Langley ptr += 4; 45733ad798cSAdam Langley } 45833ad798cSAdam Langley 459fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 460fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 461fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 462fd6149d3SIlpo Järvinen opts->mss); 463fd6149d3SIlpo Järvinen } 464fd6149d3SIlpo Järvinen 465bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 466bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 46733ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 46833ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 46933ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 47033ad798cSAdam Langley TCPOLEN_TIMESTAMP); 471bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 47233ad798cSAdam Langley } else { 473496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 47440efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 47540efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 47640efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 47740efc6faSStephen Hemminger } 47833ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 47933ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 48033ad798cSAdam Langley } 48133ad798cSAdam Langley 482bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 48333ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 48433ad798cSAdam Langley (TCPOPT_NOP << 16) | 48533ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 48633ad798cSAdam Langley TCPOLEN_SACK_PERM); 48733ad798cSAdam Langley } 48833ad798cSAdam Langley 489bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 49033ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 49133ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 49233ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 49333ad798cSAdam Langley opts->ws); 49433ad798cSAdam Langley } 49533ad798cSAdam Langley 49633ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 49733ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 49833ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 49940efc6faSStephen Hemminger int this_sack; 50040efc6faSStephen Hemminger 50140efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 50240efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 50340efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 50433ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 50540efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5062de979bdSStephen Hemminger 50733ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 50833ad798cSAdam Langley ++this_sack) { 50940efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 51040efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 51140efc6faSStephen Hemminger } 5122de979bdSStephen Hemminger 51340efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 51440efc6faSStephen Hemminger } 5152100c8d2SYuchung Cheng 5162100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5172100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 5187f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 5197f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 5202100c8d2SYuchung Cheng 5217f9b838bSDaniel Lee if (foc->exp) { 5227f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 5237f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 5242100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 5257f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 5267f9b838bSDaniel Lee } else { 5277f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 5287f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 5297f9b838bSDaniel Lee *p++ = len; 5302100c8d2SYuchung Cheng } 5317f9b838bSDaniel Lee 5327f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 5337f9b838bSDaniel Lee if ((len & 3) == 2) { 5347f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 5357f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 5367f9b838bSDaniel Lee } 5377f9b838bSDaniel Lee ptr += (len + 3) >> 2; 5382100c8d2SYuchung Cheng } 53940efc6faSStephen Hemminger } 54040efc6faSStephen Hemminger 54167edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 54267edfef7SAndi Kleen * network wire format yet. 54367edfef7SAndi Kleen */ 54495c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 54533ad798cSAdam Langley struct tcp_out_options *opts, 546cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 547cf533ea5SEric Dumazet { 54833ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 54995c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 550783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 55133ad798cSAdam Langley 552cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 55333ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 55433ad798cSAdam Langley if (*md5) { 55533ad798cSAdam Langley opts->options |= OPTION_MD5; 556bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 557cfb6eeb4SYOSHIFUJI Hideaki } 55833ad798cSAdam Langley #else 55933ad798cSAdam Langley *md5 = NULL; 560cfb6eeb4SYOSHIFUJI Hideaki #endif 56133ad798cSAdam Langley 56233ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 56333ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 56433ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 56533ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 56633ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 56733ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 56833ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 56933ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 57033ad798cSAdam Langley * going out. */ 57133ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 572bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 57333ad798cSAdam Langley 5745d2ed052SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) { 57533ad798cSAdam Langley opts->options |= OPTION_TS; 5767faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 57733ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 578bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 57933ad798cSAdam Langley } 5809bb37ef0SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) { 58133ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 58289e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 583bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 58433ad798cSAdam Langley } 585f9301034SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) { 58633ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 587b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 588bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 58933ad798cSAdam Langley } 59033ad798cSAdam Langley 591783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 5922646c831SDaniel Lee u32 need = fastopen->cookie.len; 5932646c831SDaniel Lee 5942646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 5952646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 596783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 597783237e8SYuchung Cheng if (remaining >= need) { 598783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 599783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 600783237e8SYuchung Cheng remaining -= need; 601783237e8SYuchung Cheng tp->syn_fastopen = 1; 6022646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 603783237e8SYuchung Cheng } 604783237e8SYuchung Cheng } 605bd0388aeSWilliam Allen Simpson 606bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 60733ad798cSAdam Langley } 60833ad798cSAdam Langley 60967edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 61037bfbddaSEric Dumazet static unsigned int tcp_synack_options(struct request_sock *req, 61195c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 61233ad798cSAdam Langley struct tcp_out_options *opts, 61380f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 6148336886fSJerry Chu struct tcp_fastopen_cookie *foc) 6154957faadSWilliam Allen Simpson { 61633ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 61795c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 61833ad798cSAdam Langley 61933ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 62080f03e27SEric Dumazet if (md5) { 62133ad798cSAdam Langley opts->options |= OPTION_MD5; 6224957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6234957faadSWilliam Allen Simpson 6244957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6254957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6264957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6274957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6284957faadSWilliam Allen Simpson */ 629de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 63033ad798cSAdam Langley } 63133ad798cSAdam Langley #endif 63233ad798cSAdam Langley 6334957faadSWilliam Allen Simpson /* We always send an MSS option. */ 63433ad798cSAdam Langley opts->mss = mss; 6354957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 63633ad798cSAdam Langley 63733ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 63833ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 63989e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6404957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 64133ad798cSAdam Langley } 642de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 64333ad798cSAdam Langley opts->options |= OPTION_TS; 64495a22caeSFlorian Westphal opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; 64533ad798cSAdam Langley opts->tsecr = req->ts_recent; 6464957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 64733ad798cSAdam Langley } 64833ad798cSAdam Langley if (likely(ireq->sack_ok)) { 64933ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 650de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 6514957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 65233ad798cSAdam Langley } 6537f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 6547f9b838bSDaniel Lee u32 need = foc->len; 6557f9b838bSDaniel Lee 6567f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 6577f9b838bSDaniel Lee TCPOLEN_FASTOPEN_BASE; 6588336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 6598336886fSJerry Chu if (remaining >= need) { 6608336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 6618336886fSJerry Chu opts->fastopen_cookie = foc; 6628336886fSJerry Chu remaining -= need; 6638336886fSJerry Chu } 6648336886fSJerry Chu } 6654957faadSWilliam Allen Simpson 6664957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 66733ad798cSAdam Langley } 66833ad798cSAdam Langley 66967edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 67067edfef7SAndi Kleen * final wire format yet. 67167edfef7SAndi Kleen */ 67295c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 67333ad798cSAdam Langley struct tcp_out_options *opts, 674cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 675cf533ea5SEric Dumazet { 67633ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 67795c96174SEric Dumazet unsigned int size = 0; 678cabeccbdSIlpo Järvinen unsigned int eff_sacks; 67933ad798cSAdam Langley 6805843ef42SAndi Kleen opts->options = 0; 6815843ef42SAndi Kleen 68233ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 68333ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 68433ad798cSAdam Langley if (unlikely(*md5)) { 68533ad798cSAdam Langley opts->options |= OPTION_MD5; 68633ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 68733ad798cSAdam Langley } 68833ad798cSAdam Langley #else 68933ad798cSAdam Langley *md5 = NULL; 69033ad798cSAdam Langley #endif 69133ad798cSAdam Langley 69233ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 69333ad798cSAdam Langley opts->options |= OPTION_TS; 6947faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 69533ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 69633ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 69733ad798cSAdam Langley } 69833ad798cSAdam Langley 699cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 700cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 70195c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 70233ad798cSAdam Langley opts->num_sack_blocks = 70395c96174SEric Dumazet min_t(unsigned int, eff_sacks, 70433ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 70533ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 70633ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 70733ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 70833ad798cSAdam Langley } 70933ad798cSAdam Langley 71033ad798cSAdam Langley return size; 71140efc6faSStephen Hemminger } 7121da177e4SLinus Torvalds 71346d3ceabSEric Dumazet 71446d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 71546d3ceabSEric Dumazet * 71646d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 71746d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 71846d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 71946d3ceabSEric Dumazet * 72046d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 72146d3ceabSEric Dumazet * needs to be reallocated in a driver. 7228e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 72346d3ceabSEric Dumazet * 72446d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 72546d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 72646d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 72746d3ceabSEric Dumazet */ 72846d3ceabSEric Dumazet struct tsq_tasklet { 72946d3ceabSEric Dumazet struct tasklet_struct tasklet; 73046d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 73146d3ceabSEric Dumazet }; 73246d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 73346d3ceabSEric Dumazet 7346f458dfbSEric Dumazet static void tcp_tsq_handler(struct sock *sk) 7356f458dfbSEric Dumazet { 7366f458dfbSEric Dumazet if ((1 << sk->sk_state) & 7376f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 738f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 739f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 740f9616c35SEric Dumazet 741f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 742f9616c35SEric Dumazet tp->snd_cwnd > tcp_packets_in_flight(tp)) 743f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 744f9616c35SEric Dumazet 745f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 746bf06200eSJohn Ogness 0, GFP_ATOMIC); 7476f458dfbSEric Dumazet } 748f9616c35SEric Dumazet } 74946d3ceabSEric Dumazet /* 7508e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 75146d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 7528e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 75346d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 75446d3ceabSEric Dumazet */ 75546d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 75646d3ceabSEric Dumazet { 75746d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 75846d3ceabSEric Dumazet LIST_HEAD(list); 75946d3ceabSEric Dumazet unsigned long flags; 76046d3ceabSEric Dumazet struct list_head *q, *n; 76146d3ceabSEric Dumazet struct tcp_sock *tp; 76246d3ceabSEric Dumazet struct sock *sk; 76346d3ceabSEric Dumazet 76446d3ceabSEric Dumazet local_irq_save(flags); 76546d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 76646d3ceabSEric Dumazet local_irq_restore(flags); 76746d3ceabSEric Dumazet 76846d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 76946d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 77046d3ceabSEric Dumazet list_del(&tp->tsq_node); 77146d3ceabSEric Dumazet 77246d3ceabSEric Dumazet sk = (struct sock *)tp; 7730a9648f1SEric Dumazet smp_mb__before_atomic(); 7747aa5470cSEric Dumazet clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); 7757aa5470cSEric Dumazet 776b223feb9SEric Dumazet if (!sk->sk_lock.owned && 7777aa5470cSEric Dumazet test_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) { 77846d3ceabSEric Dumazet bh_lock_sock(sk); 77946d3ceabSEric Dumazet if (!sock_owned_by_user(sk)) { 7807aa5470cSEric Dumazet clear_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags); 7816f458dfbSEric Dumazet tcp_tsq_handler(sk); 78246d3ceabSEric Dumazet } 78346d3ceabSEric Dumazet bh_unlock_sock(sk); 784b223feb9SEric Dumazet } 78546d3ceabSEric Dumazet 78646d3ceabSEric Dumazet sk_free(sk); 78746d3ceabSEric Dumazet } 78846d3ceabSEric Dumazet } 78946d3ceabSEric Dumazet 79040fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 79140fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 79240fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 79340fc3423SEric Dumazet TCPF_MTU_REDUCED_DEFERRED) 79446d3ceabSEric Dumazet /** 79546d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 79646d3ceabSEric Dumazet * @sk: socket 79746d3ceabSEric Dumazet * 79846d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 79946d3ceabSEric Dumazet * actions before socket release. 80046d3ceabSEric Dumazet */ 80146d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 80246d3ceabSEric Dumazet { 8036f458dfbSEric Dumazet unsigned long flags, nflags; 80446d3ceabSEric Dumazet 8056f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 8066f458dfbSEric Dumazet do { 8077aa5470cSEric Dumazet flags = sk->sk_tsq_flags; 8086f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 8096f458dfbSEric Dumazet return; 8106f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 8117aa5470cSEric Dumazet } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); 8126f458dfbSEric Dumazet 81340fc3423SEric Dumazet if (flags & TCPF_TSQ_DEFERRED) 8146f458dfbSEric Dumazet tcp_tsq_handler(sk); 8156f458dfbSEric Dumazet 816c3f9b018SEric Dumazet /* Here begins the tricky part : 817c3f9b018SEric Dumazet * We are called from release_sock() with : 818c3f9b018SEric Dumazet * 1) BH disabled 819c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 820c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 821c3f9b018SEric Dumazet * 822c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 823c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 824c3f9b018SEric Dumazet */ 825c3f9b018SEric Dumazet sock_release_ownership(sk); 826c3f9b018SEric Dumazet 82740fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 8286f458dfbSEric Dumazet tcp_write_timer_handler(sk); 829144d56e9SEric Dumazet __sock_put(sk); 830144d56e9SEric Dumazet } 83140fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 8326f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 833144d56e9SEric Dumazet __sock_put(sk); 834144d56e9SEric Dumazet } 83540fc3423SEric Dumazet if (flags & TCPF_MTU_REDUCED_DEFERRED) { 8364fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 837144d56e9SEric Dumazet __sock_put(sk); 838144d56e9SEric Dumazet } 83946d3ceabSEric Dumazet } 84046d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 84146d3ceabSEric Dumazet 84246d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 84346d3ceabSEric Dumazet { 84446d3ceabSEric Dumazet int i; 84546d3ceabSEric Dumazet 84646d3ceabSEric Dumazet for_each_possible_cpu(i) { 84746d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 84846d3ceabSEric Dumazet 84946d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 85046d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 85146d3ceabSEric Dumazet tcp_tasklet_func, 85246d3ceabSEric Dumazet (unsigned long)tsq); 85346d3ceabSEric Dumazet } 85446d3ceabSEric Dumazet } 85546d3ceabSEric Dumazet 85646d3ceabSEric Dumazet /* 85746d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 8588e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 85946d3ceabSEric Dumazet * hold qdisc lock. 86046d3ceabSEric Dumazet */ 861d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 86246d3ceabSEric Dumazet { 86346d3ceabSEric Dumazet struct sock *sk = skb->sk; 86446d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 865408f0a6cSEric Dumazet unsigned long flags, nval, oval; 8669b462d02SEric Dumazet 8679b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 8689b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 8699b462d02SEric Dumazet */ 87014afee4bSReshetova, Elena WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); 8719b462d02SEric Dumazet 8729b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 8739b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 8749b462d02SEric Dumazet * This gives : 8759b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 8769b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 8779b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 8789b462d02SEric Dumazet */ 87914afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 8809b462d02SEric Dumazet goto out; 88146d3ceabSEric Dumazet 8827aa5470cSEric Dumazet for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { 88346d3ceabSEric Dumazet struct tsq_tasklet *tsq; 884a9b204d1SEric Dumazet bool empty; 88546d3ceabSEric Dumazet 886408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 887408f0a6cSEric Dumazet goto out; 888408f0a6cSEric Dumazet 889b223feb9SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED; 8907aa5470cSEric Dumazet nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); 891408f0a6cSEric Dumazet if (nval != oval) 892408f0a6cSEric Dumazet continue; 893408f0a6cSEric Dumazet 89446d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 89546d3ceabSEric Dumazet local_irq_save(flags); 896903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 897a9b204d1SEric Dumazet empty = list_empty(&tsq->head); 89846d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 899a9b204d1SEric Dumazet if (empty) 90046d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 90146d3ceabSEric Dumazet local_irq_restore(flags); 9029b462d02SEric Dumazet return; 90346d3ceabSEric Dumazet } 9049b462d02SEric Dumazet out: 9059b462d02SEric Dumazet sk_free(sk); 90646d3ceabSEric Dumazet } 90746d3ceabSEric Dumazet 908218af599SEric Dumazet /* Note: Called under hard irq. 909218af599SEric Dumazet * We can not call TCP stack right away. 910218af599SEric Dumazet */ 911218af599SEric Dumazet enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 912218af599SEric Dumazet { 913218af599SEric Dumazet struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); 914218af599SEric Dumazet struct sock *sk = (struct sock *)tp; 915218af599SEric Dumazet unsigned long nval, oval; 916218af599SEric Dumazet 917218af599SEric Dumazet for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { 918218af599SEric Dumazet struct tsq_tasklet *tsq; 919218af599SEric Dumazet bool empty; 920218af599SEric Dumazet 921218af599SEric Dumazet if (oval & TSQF_QUEUED) 922218af599SEric Dumazet break; 923218af599SEric Dumazet 924218af599SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED; 925218af599SEric Dumazet nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); 926218af599SEric Dumazet if (nval != oval) 927218af599SEric Dumazet continue; 928218af599SEric Dumazet 92914afee4bSReshetova, Elena if (!refcount_inc_not_zero(&sk->sk_wmem_alloc)) 930218af599SEric Dumazet break; 931218af599SEric Dumazet /* queue this socket to tasklet queue */ 932218af599SEric Dumazet tsq = this_cpu_ptr(&tsq_tasklet); 933218af599SEric Dumazet empty = list_empty(&tsq->head); 934218af599SEric Dumazet list_add(&tp->tsq_node, &tsq->head); 935218af599SEric Dumazet if (empty) 936218af599SEric Dumazet tasklet_schedule(&tsq->tasklet); 937218af599SEric Dumazet break; 938218af599SEric Dumazet } 939218af599SEric Dumazet return HRTIMER_NORESTART; 940218af599SEric Dumazet } 941218af599SEric Dumazet 942218af599SEric Dumazet /* BBR congestion control needs pacing. 943218af599SEric Dumazet * Same remark for SO_MAX_PACING_RATE. 944218af599SEric Dumazet * sch_fq packet scheduler is efficiently handling pacing, 945218af599SEric Dumazet * but is not always installed/used. 946218af599SEric Dumazet * Return true if TCP stack should pace packets itself. 947218af599SEric Dumazet */ 948218af599SEric Dumazet static bool tcp_needs_internal_pacing(const struct sock *sk) 949218af599SEric Dumazet { 950218af599SEric Dumazet return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED; 951218af599SEric Dumazet } 952218af599SEric Dumazet 953218af599SEric Dumazet static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) 954218af599SEric Dumazet { 955218af599SEric Dumazet u64 len_ns; 956218af599SEric Dumazet u32 rate; 957218af599SEric Dumazet 958218af599SEric Dumazet if (!tcp_needs_internal_pacing(sk)) 959218af599SEric Dumazet return; 960218af599SEric Dumazet rate = sk->sk_pacing_rate; 961218af599SEric Dumazet if (!rate || rate == ~0U) 962218af599SEric Dumazet return; 963218af599SEric Dumazet 964218af599SEric Dumazet /* Should account for header sizes as sch_fq does, 965218af599SEric Dumazet * but lets make things simple. 966218af599SEric Dumazet */ 967218af599SEric Dumazet len_ns = (u64)skb->len * NSEC_PER_SEC; 968218af599SEric Dumazet do_div(len_ns, rate); 969218af599SEric Dumazet hrtimer_start(&tcp_sk(sk)->pacing_timer, 970218af599SEric Dumazet ktime_add_ns(ktime_get(), len_ns), 971218af599SEric Dumazet HRTIMER_MODE_ABS_PINNED); 972218af599SEric Dumazet } 973218af599SEric Dumazet 9741da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 9751da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 9761da177e4SLinus Torvalds * transmission and possible later retransmissions. 9771da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 9781da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 9791da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 9801da177e4SLinus Torvalds * device. 9811da177e4SLinus Torvalds * 9821da177e4SLinus Torvalds * We are working here with either a clone of the original 9831da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 9841da177e4SLinus Torvalds */ 985056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 986056834d9SIlpo Järvinen gfp_t gfp_mask) 9871da177e4SLinus Torvalds { 9886687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 989dfb4b9dcSDavid S. Miller struct inet_sock *inet; 990dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 991dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 99233ad798cSAdam Langley struct tcp_out_options opts; 99395c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 994cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 9951da177e4SLinus Torvalds struct tcphdr *th; 9961da177e4SLinus Torvalds int err; 9971da177e4SLinus Torvalds 998dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 9996f094b9eSLawrence Brakmo tp = tcp_sk(sk); 1000dfb4b9dcSDavid S. Miller 1001385e2070SEric Dumazet skb->skb_mstamp = tp->tcp_mstamp; 1002ccdbb6e9SEric Dumazet if (clone_it) { 10036f094b9eSLawrence Brakmo TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq 10046f094b9eSLawrence Brakmo - tp->snd_una; 1005b9f64820SYuchung Cheng tcp_rate_skb_sent(sk, skb); 1006dfb4b9dcSDavid S. Miller 1007dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 1008dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 1009dfb4b9dcSDavid S. Miller else 1010dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 1011dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 1012dfb4b9dcSDavid S. Miller return -ENOBUFS; 1013dfb4b9dcSDavid S. Miller } 1014dfb4b9dcSDavid S. Miller 1015dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 1016dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 101733ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 10181da177e4SLinus Torvalds 10194de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 102033ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 102133ad798cSAdam Langley else 102233ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 102333ad798cSAdam Langley &md5); 102433ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 10251da177e4SLinus Torvalds 1026547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 1027b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 1028b2532eb9SEric Dumazet * which holds one reference to sk_wmem_alloc. 1029b2532eb9SEric Dumazet * 1030b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 1031b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 1032547669d4SEric Dumazet */ 1033b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 10341da177e4SLinus Torvalds 103538ab52e8SEric Dumazet /* If we had to use memory reserve to allocate this skb, 103638ab52e8SEric Dumazet * this might cause drops if packet is looped back : 103738ab52e8SEric Dumazet * Other socket might not have SOCK_MEMALLOC. 103838ab52e8SEric Dumazet * Packets not looped back do not care about pfmemalloc. 103938ab52e8SEric Dumazet */ 104038ab52e8SEric Dumazet skb->pfmemalloc = 0; 104138ab52e8SEric Dumazet 1042aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 1043aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 104446d3ceabSEric Dumazet 104546d3ceabSEric Dumazet skb_orphan(skb); 104646d3ceabSEric Dumazet skb->sk = sk; 10471d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 1048b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 104914afee4bSReshetova, Elena refcount_add(skb->truesize, &sk->sk_wmem_alloc); 10501da177e4SLinus Torvalds 1051c3a2e837SJulian Anastasov skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); 1052c3a2e837SJulian Anastasov 10531da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 1054ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 1055c720c7e8SEric Dumazet th->source = inet->inet_sport; 1056c720c7e8SEric Dumazet th->dest = inet->inet_dport; 10571da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 10581da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 1059df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 10604de075e0SEric Dumazet tcb->tcp_flags); 1061dfb4b9dcSDavid S. Miller 10621da177e4SLinus Torvalds th->check = 0; 10631da177e4SLinus Torvalds th->urg_ptr = 0; 10641da177e4SLinus Torvalds 106533f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 10667691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 10677691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 10681da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 10691da177e4SLinus Torvalds th->urg = 1; 10707691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 10710eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 10727691367dSHerbert Xu th->urg = 1; 10737691367dSHerbert Xu } 10741da177e4SLinus Torvalds } 10751da177e4SLinus Torvalds 1076bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 107751466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 1078ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1079ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1080ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1081ea1627c2SEric Dumazet } else { 1082ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1083ea1627c2SEric Dumazet * is never scaled. 1084ea1627c2SEric Dumazet */ 1085ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1086ea1627c2SEric Dumazet } 1087cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1088cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1089cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1090a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1091bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 109239f8e58eSEric Dumazet md5, sk, skb); 1093cfb6eeb4SYOSHIFUJI Hideaki } 1094cfb6eeb4SYOSHIFUJI Hideaki #endif 1095cfb6eeb4SYOSHIFUJI Hideaki 1096bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 10971da177e4SLinus Torvalds 10984de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 1099fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 11001da177e4SLinus Torvalds 1101a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1102cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1103a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1104218af599SEric Dumazet tcp_internal_pacing(sk, skb); 1105a44d6eacSMartin KaFai Lau } 11061da177e4SLinus Torvalds 1107bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1108aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1109aa2ea058STom Herbert tcp_skb_pcount(skb)); 11101da177e4SLinus Torvalds 11112efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 1112f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1113cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1114f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1115cd7d8498SEric Dumazet 11167faee5c0SEric Dumazet /* Our usage of tstamp should remain private */ 11172456e855SThomas Gleixner skb->tstamp = 0; 1118971f10ecSEric Dumazet 1119971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1120971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1121971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1122971f10ecSEric Dumazet 1123b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 11247faee5c0SEric Dumazet 112583de47cdSHua Zhong if (likely(err <= 0)) 11261da177e4SLinus Torvalds return err; 11271da177e4SLinus Torvalds 11285ee2c941SChristoph Paasch tcp_enter_cwr(sk); 11291da177e4SLinus Torvalds 1130b9df3cb8SGerrit Renker return net_xmit_eval(err); 11311da177e4SLinus Torvalds } 11321da177e4SLinus Torvalds 113367edfef7SAndi Kleen /* This routine just queues the buffer for sending. 11341da177e4SLinus Torvalds * 11351da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 11361da177e4SLinus Torvalds * otherwise socket can stall. 11371da177e4SLinus Torvalds */ 11381da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 11391da177e4SLinus Torvalds { 11401da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11411da177e4SLinus Torvalds 11421da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 11431da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1144f4a775d1SEric Dumazet __skb_header_release(skb); 1145fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 11463ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 11473ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 11481da177e4SLinus Torvalds } 11491da177e4SLinus Torvalds 115067edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 11515bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1152f6302d1dSDavid S. Miller { 11538f26fb1cSEric Dumazet if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { 1154f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1155f6302d1dSDavid S. Miller * non-TSO case. 1156f6302d1dSDavid S. Miller */ 1157cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1158f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1159f6302d1dSDavid S. Miller } else { 1160cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1161f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 11621da177e4SLinus Torvalds } 11631da177e4SLinus Torvalds } 11641da177e4SLinus Torvalds 116591fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 116668f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 116791fed7a1SIlpo Järvinen */ 1168cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 116991fed7a1SIlpo Järvinen int decr) 117091fed7a1SIlpo Järvinen { 1171a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1172a47e5a98SIlpo Järvinen 1173dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 117491fed7a1SIlpo Järvinen return; 117591fed7a1SIlpo Järvinen 11766859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 117791fed7a1SIlpo Järvinen tp->fackets_out -= decr; 117891fed7a1SIlpo Järvinen } 117991fed7a1SIlpo Järvinen 1180797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1181797108d1SIlpo Järvinen * tweaks to fix counters 1182797108d1SIlpo Järvinen */ 1183cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1184797108d1SIlpo Järvinen { 1185797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1186797108d1SIlpo Järvinen 1187797108d1SIlpo Järvinen tp->packets_out -= decr; 1188797108d1SIlpo Järvinen 1189797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1190797108d1SIlpo Järvinen tp->sacked_out -= decr; 1191797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1192797108d1SIlpo Järvinen tp->retrans_out -= decr; 1193797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1194797108d1SIlpo Järvinen tp->lost_out -= decr; 1195797108d1SIlpo Järvinen 1196797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1197797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1198797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1199797108d1SIlpo Järvinen 1200797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1201797108d1SIlpo Järvinen 1202797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1203797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 120452cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1205797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1206797108d1SIlpo Järvinen 1207797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1208797108d1SIlpo Järvinen } 1209797108d1SIlpo Järvinen 12100a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 12110a2cf20cSSoheil Hassas Yeganeh { 12120a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 12130a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 12140a2cf20cSSoheil Hassas Yeganeh } 12150a2cf20cSSoheil Hassas Yeganeh 1216490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1217490cc7d0SWillem de Bruijn { 1218490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1219490cc7d0SWillem de Bruijn 12200a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1221490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1222490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1223490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1224490cc7d0SWillem de Bruijn 1225490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1226490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1227490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1228b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1229b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1230490cc7d0SWillem de Bruijn } 1231490cc7d0SWillem de Bruijn } 1232490cc7d0SWillem de Bruijn 1233a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1234a166140eSMartin KaFai Lau { 1235a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1236a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1237a166140eSMartin KaFai Lau } 1238a166140eSMartin KaFai Lau 12391da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 12401da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 12411da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 12421da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 12431da177e4SLinus Torvalds */ 1244056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 12456cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 12461da177e4SLinus Torvalds { 12471da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12481da177e4SLinus Torvalds struct sk_buff *buff; 12496475be16SDavid S. Miller int nsize, old_factor; 1250b60b49eaSHerbert Xu int nlen; 12519ce01461SIlpo Järvinen u8 flags; 12521da177e4SLinus Torvalds 12532fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 12542fceec13SIlpo Järvinen return -EINVAL; 12556a438bbeSStephen Hemminger 12561da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 12571da177e4SLinus Torvalds if (nsize < 0) 12581da177e4SLinus Torvalds nsize = 0; 12591da177e4SLinus Torvalds 12606cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 12611da177e4SLinus Torvalds return -ENOMEM; 12621da177e4SLinus Torvalds 12631da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 1264eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, nsize, gfp, true); 126551456b29SIan Morris if (!buff) 12661da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1267ef5cb973SHerbert Xu 12683ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 12693ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1270b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1271b60b49eaSHerbert Xu buff->truesize += nlen; 1272b60b49eaSHerbert Xu skb->truesize -= nlen; 12731da177e4SLinus Torvalds 12741da177e4SLinus Torvalds /* Correct the sequence numbers. */ 12751da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 12761da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 12771da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 12781da177e4SLinus Torvalds 12791da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 12804de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 12814de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 12824de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1283e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1284a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 12851da177e4SLinus Torvalds 128684fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 12871da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1288056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1289056834d9SIlpo Järvinen skb_put(buff, nsize), 12901da177e4SLinus Torvalds nsize, 0); 12911da177e4SLinus Torvalds 12921da177e4SLinus Torvalds skb_trim(skb, len); 12931da177e4SLinus Torvalds 12941da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 12951da177e4SLinus Torvalds } else { 129684fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 12971da177e4SLinus Torvalds skb_split(skb, buff, len); 12981da177e4SLinus Torvalds } 12991da177e4SLinus Torvalds 13001da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 13011da177e4SLinus Torvalds 1302a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1303490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 13041da177e4SLinus Torvalds 13056475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 13066475be16SDavid S. Miller 13071da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 13085bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 13095bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 13101da177e4SLinus Torvalds 1311b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1312b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1313b9f64820SYuchung Cheng 13146475be16SDavid S. Miller /* If this packet has been sent out already, we must 13156475be16SDavid S. Miller * adjust the various packet counters. 13166475be16SDavid S. Miller */ 1317cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 13186475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 13196475be16SDavid S. Miller tcp_skb_pcount(buff); 13201da177e4SLinus Torvalds 1321797108d1SIlpo Järvinen if (diff) 1322797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 13231da177e4SLinus Torvalds } 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1326f4a775d1SEric Dumazet __skb_header_release(buff); 1327fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 13281da177e4SLinus Torvalds 13291da177e4SLinus Torvalds return 0; 13301da177e4SLinus Torvalds } 13311da177e4SLinus Torvalds 1332f4d01666SEric Dumazet /* This is similar to __pskb_pull_tail(). The difference is that pulled 1333f4d01666SEric Dumazet * data is not copied, but immediately discarded. 13341da177e4SLinus Torvalds */ 13357162fb24SEric Dumazet static int __pskb_trim_head(struct sk_buff *skb, int len) 13361da177e4SLinus Torvalds { 13377b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 13381da177e4SLinus Torvalds int i, k, eat; 13391da177e4SLinus Torvalds 13404fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 13414fa48bf3SEric Dumazet if (eat) { 13424fa48bf3SEric Dumazet __skb_pull(skb, eat); 13434fa48bf3SEric Dumazet len -= eat; 13444fa48bf3SEric Dumazet if (!len) 13457162fb24SEric Dumazet return 0; 13464fa48bf3SEric Dumazet } 13471da177e4SLinus Torvalds eat = len; 13481da177e4SLinus Torvalds k = 0; 13497b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 13507b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 13517b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 13529e903e08SEric Dumazet 13539e903e08SEric Dumazet if (size <= eat) { 1354aff65da0SIan Campbell skb_frag_unref(skb, i); 13559e903e08SEric Dumazet eat -= size; 13561da177e4SLinus Torvalds } else { 13577b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 13581da177e4SLinus Torvalds if (eat) { 13597b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 13607b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 13611da177e4SLinus Torvalds eat = 0; 13621da177e4SLinus Torvalds } 13631da177e4SLinus Torvalds k++; 13641da177e4SLinus Torvalds } 13651da177e4SLinus Torvalds } 13667b7fc97aSEric Dumazet shinfo->nr_frags = k; 13671da177e4SLinus Torvalds 13681da177e4SLinus Torvalds skb->data_len -= len; 13691da177e4SLinus Torvalds skb->len = skb->data_len; 13707162fb24SEric Dumazet return len; 13711da177e4SLinus Torvalds } 13721da177e4SLinus Torvalds 137367edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 13741da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 13751da177e4SLinus Torvalds { 13767162fb24SEric Dumazet u32 delta_truesize; 13777162fb24SEric Dumazet 137814bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 13791da177e4SLinus Torvalds return -ENOMEM; 13801da177e4SLinus Torvalds 13817162fb24SEric Dumazet delta_truesize = __pskb_trim_head(skb, len); 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 138484fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 13851da177e4SLinus Torvalds 13867162fb24SEric Dumazet if (delta_truesize) { 13877162fb24SEric Dumazet skb->truesize -= delta_truesize; 13887162fb24SEric Dumazet sk->sk_wmem_queued -= delta_truesize; 13897162fb24SEric Dumazet sk_mem_uncharge(sk, delta_truesize); 13901da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 13917162fb24SEric Dumazet } 13921da177e4SLinus Torvalds 13935b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 13941da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 13955bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 13961da177e4SLinus Torvalds 13971da177e4SLinus Torvalds return 0; 13981da177e4SLinus Torvalds } 13991da177e4SLinus Torvalds 14001b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 14011b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 14025d424d5aSJohn Heffner { 1403cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1404cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 14055d424d5aSJohn Heffner int mss_now; 14065d424d5aSJohn Heffner 14075d424d5aSJohn Heffner /* Calculate base mss without TCP options: 14085d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 14095d424d5aSJohn Heffner */ 14105d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 14115d424d5aSJohn Heffner 141267469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 141367469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 141467469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 141567469601SEric Dumazet 141667469601SEric Dumazet if (dst && dst_allfrag(dst)) 141767469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 141867469601SEric Dumazet } 141967469601SEric Dumazet 14205d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 14215d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 14225d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 14235d424d5aSJohn Heffner 14245d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 14255d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 14265d424d5aSJohn Heffner 14275d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 14285d424d5aSJohn Heffner if (mss_now < 48) 14295d424d5aSJohn Heffner mss_now = 48; 14305d424d5aSJohn Heffner return mss_now; 14315d424d5aSJohn Heffner } 14325d424d5aSJohn Heffner 14331b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 14341b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 14351b63edd6SYuchung Cheng { 14361b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 14371b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 14381b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 14391b63edd6SYuchung Cheng } 14401b63edd6SYuchung Cheng 14415d424d5aSJohn Heffner /* Inverse of above */ 144267469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 14435d424d5aSJohn Heffner { 1444cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1445cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 14465d424d5aSJohn Heffner int mtu; 14475d424d5aSJohn Heffner 14485d424d5aSJohn Heffner mtu = mss + 14495d424d5aSJohn Heffner tp->tcp_header_len + 14505d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 14515d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 14525d424d5aSJohn Heffner 145367469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 145467469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 145567469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 145667469601SEric Dumazet 145767469601SEric Dumazet if (dst && dst_allfrag(dst)) 145867469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 145967469601SEric Dumazet } 14605d424d5aSJohn Heffner return mtu; 14615d424d5aSJohn Heffner } 1462556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 14635d424d5aSJohn Heffner 146467edfef7SAndi Kleen /* MTU probing init per socket */ 14655d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 14665d424d5aSJohn Heffner { 14675d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 14685d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1469b0f9ca53SFan Du struct net *net = sock_net(sk); 14705d424d5aSJohn Heffner 1471b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 14725d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 14735d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1474b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 14755d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 147605cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 1477c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 14785d424d5aSJohn Heffner } 14794bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 14805d424d5aSJohn Heffner 14811da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 14821da177e4SLinus Torvalds 14831da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 14841da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 14851da177e4SLinus Torvalds 14861da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1487caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 14881da177e4SLinus Torvalds It also does not include TCP options. 14891da177e4SLinus Torvalds 1490d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 14911da177e4SLinus Torvalds 14921da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 14931da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 14941da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 14951da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 14961da177e4SLinus Torvalds 14971da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 14981da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 14991da177e4SLinus Torvalds 1500d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1501d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 15021da177e4SLinus Torvalds */ 15031da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 15041da177e4SLinus Torvalds { 15051da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1506d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 15075d424d5aSJohn Heffner int mss_now; 15081da177e4SLinus Torvalds 15095d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 15105d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 15111da177e4SLinus Torvalds 15125d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1513409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 15141da177e4SLinus Torvalds 15151da177e4SLinus Torvalds /* And store cached results */ 1516d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 15175d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 15185d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1519c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 15201da177e4SLinus Torvalds 15211da177e4SLinus Torvalds return mss_now; 15221da177e4SLinus Torvalds } 15234bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 15261da177e4SLinus Torvalds * and even PMTU discovery events into account. 15271da177e4SLinus Torvalds */ 15280c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 15291da177e4SLinus Torvalds { 1530cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1531cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1532c1b4a7e6SDavid S. Miller u32 mss_now; 153395c96174SEric Dumazet unsigned int header_len; 153433ad798cSAdam Langley struct tcp_out_options opts; 153533ad798cSAdam Langley struct tcp_md5sig_key *md5; 15361da177e4SLinus Torvalds 1537c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1538c1b4a7e6SDavid S. Miller 15391da177e4SLinus Torvalds if (dst) { 15401da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1541d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 15421da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 15431da177e4SLinus Torvalds } 15441da177e4SLinus Torvalds 154533ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 154633ad798cSAdam Langley sizeof(struct tcphdr); 154733ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 154833ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 154933ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 155033ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 155133ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 155233ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 155333ad798cSAdam Langley mss_now -= delta; 155433ad798cSAdam Langley } 1555cfb6eeb4SYOSHIFUJI Hideaki 15561da177e4SLinus Torvalds return mss_now; 15571da177e4SLinus Torvalds } 15581da177e4SLinus Torvalds 155986fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 156086fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 156186fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 156286fd14adSWeiping Pan */ 156386fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1564a762a980SDavid S. Miller { 15659e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1566a762a980SDavid S. Miller 156786fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 156886fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 156986fd14adSWeiping Pan /* Limited by application or receiver window. */ 157086fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 157186fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 157286fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 157386fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 157486fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 157586fd14adSWeiping Pan } 157686fd14adSWeiping Pan tp->snd_cwnd_used = 0; 157786fd14adSWeiping Pan } 1578c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 157986fd14adSWeiping Pan } 158086fd14adSWeiping Pan 1581ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1582a762a980SDavid S. Miller { 15831b1fc3fdSWei Wang const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1584a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1585a762a980SDavid S. Miller 1586ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1587ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1588ca8a2263SNeal Cardwell */ 1589ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1590ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1591ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1592ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1593ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1594ca8a2263SNeal Cardwell } 1595e114a710SEric Dumazet 159624901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1597a762a980SDavid S. Miller /* Network is feed fully. */ 1598a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1599c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1600a762a980SDavid S. Miller } else { 1601a762a980SDavid S. Miller /* Network starves. */ 1602a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1603a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1604a762a980SDavid S. Miller 160515d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 1606c2203cf7SEric Dumazet (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && 16071b1fc3fdSWei Wang !ca_ops->cong_control) 1608a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1609b0f71bd3SFrancis Yan 1610b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1611b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1612b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1613b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 1614b0f71bd3SFrancis Yan * 3) no more data to send (null tcp_send_head ) 1615b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1616b0f71bd3SFrancis Yan */ 1617b0f71bd3SFrancis Yan if (!tcp_send_head(sk) && sk->sk_socket && 1618b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1619b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1620b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1621a762a980SDavid S. Miller } 1622a762a980SDavid S. Miller } 1623a762a980SDavid S. Miller 1624d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1625d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1626d4589926SEric Dumazet { 1627d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1628d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1629d4589926SEric Dumazet } 1630d4589926SEric Dumazet 1631d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1632d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1633d4589926SEric Dumazet * The test is really : 1634d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1635d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1636d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1637d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 16380e3a4803SIlpo Järvinen */ 1639d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1640d4589926SEric Dumazet const struct sk_buff *skb) 1641d4589926SEric Dumazet { 1642d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1643d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1644d4589926SEric Dumazet } 1645d4589926SEric Dumazet 1646d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1647d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1648d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1649d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1650d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1651d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1652d4589926SEric Dumazet */ 1653d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1654cc93fc51SPeter Pan(潘卫平) int nonagle) 1655d4589926SEric Dumazet { 1656d4589926SEric Dumazet return partial && 1657d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1658d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1659d4589926SEric Dumazet } 1660605ad7f1SEric Dumazet 1661605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1662605ad7f1SEric Dumazet * to send one TSO packet per ms 1663605ad7f1SEric Dumazet */ 16641b3878caSNeal Cardwell u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 16651b3878caSNeal Cardwell int min_tso_segs) 1666605ad7f1SEric Dumazet { 1667605ad7f1SEric Dumazet u32 bytes, segs; 1668605ad7f1SEric Dumazet 1669605ad7f1SEric Dumazet bytes = min(sk->sk_pacing_rate >> 10, 1670605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1671605ad7f1SEric Dumazet 1672605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1673605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1674605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1675605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1676605ad7f1SEric Dumazet */ 16771b3878caSNeal Cardwell segs = max_t(u32, bytes / mss_now, min_tso_segs); 1678605ad7f1SEric Dumazet 1679605ad7f1SEric Dumazet return min_t(u32, segs, sk->sk_gso_max_segs); 1680605ad7f1SEric Dumazet } 16811b3878caSNeal Cardwell EXPORT_SYMBOL(tcp_tso_autosize); 1682605ad7f1SEric Dumazet 1683ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1684ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1685ed6e7268SNeal Cardwell */ 1686ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1687ed6e7268SNeal Cardwell { 1688ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1689ed6e7268SNeal Cardwell u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0; 1690ed6e7268SNeal Cardwell 16911b3878caSNeal Cardwell return tso_segs ? : 16921b3878caSNeal Cardwell tcp_tso_autosize(sk, mss_now, sysctl_tcp_min_tso_segs); 1693ed6e7268SNeal Cardwell } 1694ed6e7268SNeal Cardwell 1695d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1696d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1697d4589926SEric Dumazet const struct sk_buff *skb, 1698d4589926SEric Dumazet unsigned int mss_now, 1699d4589926SEric Dumazet unsigned int max_segs, 1700d4589926SEric Dumazet int nonagle) 1701c1b4a7e6SDavid S. Miller { 1702cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1703d4589926SEric Dumazet u32 partial, needed, window, max_len; 1704c1b4a7e6SDavid S. Miller 170590840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 17061485348dSBen Hutchings max_len = mss_now * max_segs; 17070e3a4803SIlpo Järvinen 17081485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 17091485348dSBen Hutchings return max_len; 17100e3a4803SIlpo Järvinen 17115ea3a748SIlpo Järvinen needed = min(skb->len, window); 17125ea3a748SIlpo Järvinen 17131485348dSBen Hutchings if (max_len <= needed) 17141485348dSBen Hutchings return max_len; 17150e3a4803SIlpo Järvinen 1716d4589926SEric Dumazet partial = needed % mss_now; 1717d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1718d4589926SEric Dumazet * to include this last segment in this skb. 1719d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1720d4589926SEric Dumazet */ 1721cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1722d4589926SEric Dumazet return needed - partial; 1723d4589926SEric Dumazet 1724d4589926SEric Dumazet return needed; 1725c1b4a7e6SDavid S. Miller } 1726c1b4a7e6SDavid S. Miller 1727c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1728c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1729c1b4a7e6SDavid S. Miller */ 1730cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1731cf533ea5SEric Dumazet const struct sk_buff *skb) 1732c1b4a7e6SDavid S. Miller { 1733d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1734c1b4a7e6SDavid S. Miller 1735c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 17364de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 17374de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1738c1b4a7e6SDavid S. Miller return 1; 1739c1b4a7e6SDavid S. Miller 1740c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1741c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1742d649a7a8SEric Dumazet if (in_flight >= cwnd) 1743c1b4a7e6SDavid S. Miller return 0; 1744d649a7a8SEric Dumazet 1745d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1746d649a7a8SEric Dumazet * 2 GSO packets in flight. 1747d649a7a8SEric Dumazet */ 1748d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1749d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1750c1b4a7e6SDavid S. Miller } 1751c1b4a7e6SDavid S. Miller 1752b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 175367edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1754c1b4a7e6SDavid S. Miller * SKB onto the wire. 1755c1b4a7e6SDavid S. Miller */ 17565bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1757c1b4a7e6SDavid S. Miller { 1758c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1759c1b4a7e6SDavid S. Miller 1760f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 17615bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 1762c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1763c1b4a7e6SDavid S. Miller } 1764c1b4a7e6SDavid S. Miller return tso_segs; 1765c1b4a7e6SDavid S. Miller } 1766c1b4a7e6SDavid S. Miller 1767c1b4a7e6SDavid S. Miller 1768a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1769c1b4a7e6SDavid S. Miller * sent now. 1770c1b4a7e6SDavid S. Miller */ 1771a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1772c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1773c1b4a7e6SDavid S. Miller { 1774c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1775c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1776c1b4a7e6SDavid S. Miller * 1777c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1778c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1779c1b4a7e6SDavid S. Miller */ 1780c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1781a2a385d6SEric Dumazet return true; 1782c1b4a7e6SDavid S. Miller 17839b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 17849b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1785a2a385d6SEric Dumazet return true; 1786c1b4a7e6SDavid S. Miller 1787cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1788a2a385d6SEric Dumazet return true; 1789c1b4a7e6SDavid S. Miller 1790a2a385d6SEric Dumazet return false; 1791c1b4a7e6SDavid S. Miller } 1792c1b4a7e6SDavid S. Miller 1793c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1794a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1795a2a385d6SEric Dumazet const struct sk_buff *skb, 1796056834d9SIlpo Järvinen unsigned int cur_mss) 1797c1b4a7e6SDavid S. Miller { 1798c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1799c1b4a7e6SDavid S. Miller 1800c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1801c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1802c1b4a7e6SDavid S. Miller 180390840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1804c1b4a7e6SDavid S. Miller } 1805c1b4a7e6SDavid S. Miller 1806fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1807c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1808c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1809c1b4a7e6SDavid S. Miller */ 1810cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1811c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1812c1b4a7e6SDavid S. Miller { 1813cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1814c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1815c1b4a7e6SDavid S. Miller 18165bbb432cSEric Dumazet tcp_init_tso_segs(skb, cur_mss); 1817c1b4a7e6SDavid S. Miller 1818c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1819c1b4a7e6SDavid S. Miller return 0; 1820c1b4a7e6SDavid S. Miller 1821c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1822056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1823c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1824c1b4a7e6SDavid S. Miller 1825c1b4a7e6SDavid S. Miller return cwnd_quota; 1826c1b4a7e6SDavid S. Miller } 1827c1b4a7e6SDavid S. Miller 182867edfef7SAndi Kleen /* Test if sending is allowed right now. */ 1829a2a385d6SEric Dumazet bool tcp_may_send_now(struct sock *sk) 1830c1b4a7e6SDavid S. Miller { 1831cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1832fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1833c1b4a7e6SDavid S. Miller 1834a02cec21SEric Dumazet return skb && 18350c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1836c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1837a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1838c1b4a7e6SDavid S. Miller } 1839c1b4a7e6SDavid S. Miller 1840c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1841c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1842c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1843c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1844c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1845c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1846c1b4a7e6SDavid S. Miller */ 1847056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1848c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1849c1b4a7e6SDavid S. Miller { 1850c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1851c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 18529ce01461SIlpo Järvinen u8 flags; 1853c1b4a7e6SDavid S. Miller 1854c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1855c8ac3774SHerbert Xu if (skb->len != skb->data_len) 18566cc55e09SOctavian Purdila return tcp_fragment(sk, skb, len, mss_now, gfp); 1857c1b4a7e6SDavid S. Miller 1858eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp, true); 185951456b29SIan Morris if (unlikely(!buff)) 1860c1b4a7e6SDavid S. Miller return -ENOMEM; 1861c1b4a7e6SDavid S. Miller 18623ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 18633ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1864b60b49eaSHerbert Xu buff->truesize += nlen; 1865c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1866c1b4a7e6SDavid S. Miller 1867c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1868c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1869c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1870c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1871c1b4a7e6SDavid S. Miller 1872c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 18734de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 18744de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 18754de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1876c1b4a7e6SDavid S. Miller 1877c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1878c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1879c1b4a7e6SDavid S. Miller 1880a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 1881a166140eSMartin KaFai Lau 188284fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1883c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1884490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1885c1b4a7e6SDavid S. Miller 1886c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 18875bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 18885bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 1889c1b4a7e6SDavid S. Miller 1890c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1891f4a775d1SEric Dumazet __skb_header_release(buff); 1892fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1893c1b4a7e6SDavid S. Miller 1894c1b4a7e6SDavid S. Miller return 0; 1895c1b4a7e6SDavid S. Miller } 1896c1b4a7e6SDavid S. Miller 1897c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1898c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1899c1b4a7e6SDavid S. Miller * 1900c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1901c1b4a7e6SDavid S. Miller */ 1902ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1903605ad7f1SEric Dumazet bool *is_cwnd_limited, u32 max_segs) 1904c1b4a7e6SDavid S. Miller { 19056687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 190650c8339eSEric Dumazet u32 age, send_win, cong_win, limit, in_flight; 190750c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 190850c8339eSEric Dumazet struct sk_buff *head; 1909ad9f4f50SEric Dumazet int win_divisor; 1910c1b4a7e6SDavid S. Miller 19114de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1912ae8064acSJohn Heffner goto send_now; 1913c1b4a7e6SDavid S. Miller 191499d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 1915ae8064acSJohn Heffner goto send_now; 1916ae8064acSJohn Heffner 19175f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 19185f852eb5SEric Dumazet * only if the last write was recent. 19195f852eb5SEric Dumazet */ 1920d635fbe2SEric Dumazet if ((s32)(tcp_jiffies32 - tp->lsndtime) > 0) 1921ae8064acSJohn Heffner goto send_now; 1922908a75c1SDavid S. Miller 1923c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1924c1b4a7e6SDavid S. Miller 1925056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1926c1b4a7e6SDavid S. Miller 192790840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1928c1b4a7e6SDavid S. Miller 1929c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1930c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1931c1b4a7e6SDavid S. Miller 1932c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1933c1b4a7e6SDavid S. Miller 1934ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 1935605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 1936ae8064acSJohn Heffner goto send_now; 1937ba244fe9SDavid S. Miller 193862ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 193962ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 194062ad2761SIlpo Järvinen goto send_now; 194162ad2761SIlpo Järvinen 1942ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1943ad9f4f50SEric Dumazet if (win_divisor) { 1944c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1945c1b4a7e6SDavid S. Miller 1946c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1947c1b4a7e6SDavid S. Miller * just use it. 1948c1b4a7e6SDavid S. Miller */ 1949ad9f4f50SEric Dumazet chunk /= win_divisor; 1950c1b4a7e6SDavid S. Miller if (limit >= chunk) 1951ae8064acSJohn Heffner goto send_now; 1952c1b4a7e6SDavid S. Miller } else { 1953c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1954c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1955c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1956c1b4a7e6SDavid S. Miller * then send now. 1957c1b4a7e6SDavid S. Miller */ 19586b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1959ae8064acSJohn Heffner goto send_now; 1960c1b4a7e6SDavid S. Miller } 1961c1b4a7e6SDavid S. Miller 196250c8339eSEric Dumazet head = tcp_write_queue_head(sk); 1963385e2070SEric Dumazet 19649a568de4SEric Dumazet age = tcp_stamp_us_delta(tp->tcp_mstamp, head->skb_mstamp); 196550c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 196650c8339eSEric Dumazet if (age < (tp->srtt_us >> 4)) 196750c8339eSEric Dumazet goto send_now; 196850c8339eSEric Dumazet 19695f852eb5SEric Dumazet /* Ok, it looks like it is advisable to defer. */ 1970ae8064acSJohn Heffner 1971d2e1339fSBendik Rønning Opstad if (cong_win < send_win && cong_win <= skb->len) 1972ca8a2263SNeal Cardwell *is_cwnd_limited = true; 1973ca8a2263SNeal Cardwell 1974a2a385d6SEric Dumazet return true; 1975ae8064acSJohn Heffner 1976ae8064acSJohn Heffner send_now: 1977a2a385d6SEric Dumazet return false; 1978c1b4a7e6SDavid S. Miller } 1979c1b4a7e6SDavid S. Miller 198005cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 198105cbc0dbSFan Du { 198205cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 198305cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 198405cbc0dbSFan Du struct net *net = sock_net(sk); 198505cbc0dbSFan Du u32 interval; 198605cbc0dbSFan Du s32 delta; 198705cbc0dbSFan Du 198805cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 1989c74df29aSEric Dumazet delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; 199005cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 199105cbc0dbSFan Du int mss = tcp_current_mss(sk); 199205cbc0dbSFan Du 199305cbc0dbSFan Du /* Update current search range */ 199405cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 199505cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 199605cbc0dbSFan Du sizeof(struct tcphdr) + 199705cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 199805cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 199905cbc0dbSFan Du 200005cbc0dbSFan Du /* Update probe time stamp */ 2001c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 200205cbc0dbSFan Du } 200305cbc0dbSFan Du } 200405cbc0dbSFan Du 20055d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 200667edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 200767edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 200867edfef7SAndi Kleen * changes resulting in larger path MTUs. 200967edfef7SAndi Kleen * 20105d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 20115d424d5aSJohn Heffner * 1 if a probe was sent, 2012056834d9SIlpo Järvinen * -1 otherwise 2013056834d9SIlpo Järvinen */ 20145d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 20155d424d5aSJohn Heffner { 20165d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 201712a59abcSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 20185d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 20196b58e0a5SFan Du struct net *net = sock_net(sk); 20205d424d5aSJohn Heffner int probe_size; 202191cc17c0SIlpo Järvinen int size_needed; 202212a59abcSEric Dumazet int copy, len; 20235d424d5aSJohn Heffner int mss_now; 20246b58e0a5SFan Du int interval; 20255d424d5aSJohn Heffner 20265d424d5aSJohn Heffner /* Not currently probing/verifying, 20275d424d5aSJohn Heffner * not in recovery, 20285d424d5aSJohn Heffner * have enough cwnd, and 202912a59abcSEric Dumazet * not SACKing (the variable headers throw things off) 203012a59abcSEric Dumazet */ 203112a59abcSEric Dumazet if (likely(!icsk->icsk_mtup.enabled || 20325d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 20335d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 20345d424d5aSJohn Heffner tp->snd_cwnd < 11 || 203512a59abcSEric Dumazet tp->rx_opt.num_sacks || tp->rx_opt.dsack)) 20365d424d5aSJohn Heffner return -1; 20375d424d5aSJohn Heffner 20386b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 20396b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 20406b58e0a5SFan Du * smaller than a threshold, backoff from probing. 20416b58e0a5SFan Du */ 20420c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 20436b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 20446b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 204591cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 20466b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 204705cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 204805cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 204905cbc0dbSFan Du * probing process by not resetting search range to its orignal. 205005cbc0dbSFan Du */ 20516b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 205205cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 205305cbc0dbSFan Du /* Check whether enough time has elaplased for 205405cbc0dbSFan Du * another round of probing. 205505cbc0dbSFan Du */ 205605cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 20575d424d5aSJohn Heffner return -1; 20585d424d5aSJohn Heffner } 20595d424d5aSJohn Heffner 20605d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 20617f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 20625d424d5aSJohn Heffner return -1; 20635d424d5aSJohn Heffner 206491cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 20655d424d5aSJohn Heffner return -1; 206690840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 20675d424d5aSJohn Heffner return 0; 20685d424d5aSJohn Heffner 2069d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 2070d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 2071d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 20725d424d5aSJohn Heffner return -1; 20735d424d5aSJohn Heffner else 20745d424d5aSJohn Heffner return 0; 20755d424d5aSJohn Heffner } 20765d424d5aSJohn Heffner 20775d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 2078eb934478SEric Dumazet nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); 207951456b29SIan Morris if (!nskb) 20805d424d5aSJohn Heffner return -1; 20813ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 20823ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 20835d424d5aSJohn Heffner 2084fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 20855d424d5aSJohn Heffner 20865d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 20875d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 20884de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 20895d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 20905d424d5aSJohn Heffner nskb->csum = 0; 209184fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 20925d424d5aSJohn Heffner 209350c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 209450c4817eSIlpo Järvinen 20955d424d5aSJohn Heffner len = 0; 2096234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 20975d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 20982fe664f1SDouglas Caetano dos Santos if (nskb->ip_summed) { 20995d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 21002fe664f1SDouglas Caetano dos Santos } else { 21012fe664f1SDouglas Caetano dos Santos __wsum csum = skb_copy_and_csum_bits(skb, 0, 2102056834d9SIlpo Järvinen skb_put(nskb, copy), 21032fe664f1SDouglas Caetano dos Santos copy, 0); 21042fe664f1SDouglas Caetano dos Santos nskb->csum = csum_block_add(nskb->csum, csum, len); 21052fe664f1SDouglas Caetano dos Santos } 21065d424d5aSJohn Heffner 21075d424d5aSJohn Heffner if (skb->len <= copy) { 21085d424d5aSJohn Heffner /* We've eaten all the data from this skb. 21095d424d5aSJohn Heffner * Throw it away. */ 21104de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2111fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 21123ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 21135d424d5aSJohn Heffner } else { 21144de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2115a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 21165d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 21175d424d5aSJohn Heffner skb_pull(skb, copy); 211884fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 2119056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 2120056834d9SIlpo Järvinen skb->len, 0); 21215d424d5aSJohn Heffner } else { 21225d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 21235bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 21245d424d5aSJohn Heffner } 21255d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 21265d424d5aSJohn Heffner } 21275d424d5aSJohn Heffner 21285d424d5aSJohn Heffner len += copy; 2129234b6860SIlpo Järvinen 2130234b6860SIlpo Järvinen if (len >= probe_size) 2131234b6860SIlpo Järvinen break; 21325d424d5aSJohn Heffner } 21335bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 21345d424d5aSJohn Heffner 21355d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 21367faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 21377faee5c0SEric Dumazet */ 21385d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 21395d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 21405d424d5aSJohn Heffner * effectively two packets. */ 21415d424d5aSJohn Heffner tp->snd_cwnd--; 214266f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 21435d424d5aSJohn Heffner 21445d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 21450e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 21460e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 21475d424d5aSJohn Heffner 21485d424d5aSJohn Heffner return 1; 21495d424d5aSJohn Heffner } 21505d424d5aSJohn Heffner 21515d424d5aSJohn Heffner return -1; 21525d424d5aSJohn Heffner } 21535d424d5aSJohn Heffner 2154218af599SEric Dumazet static bool tcp_pacing_check(const struct sock *sk) 2155218af599SEric Dumazet { 2156218af599SEric Dumazet return tcp_needs_internal_pacing(sk) && 2157218af599SEric Dumazet hrtimer_active(&tcp_sk(sk)->pacing_timer); 2158218af599SEric Dumazet } 2159218af599SEric Dumazet 2160f9616c35SEric Dumazet /* TCP Small Queues : 2161f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2162f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2163f9616c35SEric Dumazet * This allows for : 2164f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2165f9616c35SEric Dumazet * - faster recovery 2166f9616c35SEric Dumazet * - high rates 2167f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2168f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2169f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2170f9616c35SEric Dumazet */ 2171f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2172f9616c35SEric Dumazet unsigned int factor) 2173f9616c35SEric Dumazet { 2174f9616c35SEric Dumazet unsigned int limit; 2175f9616c35SEric Dumazet 2176f9616c35SEric Dumazet limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10); 2177f9616c35SEric Dumazet limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes); 2178f9616c35SEric Dumazet limit <<= factor; 2179f9616c35SEric Dumazet 218014afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) { 218175eefc6cSEric Dumazet /* Always send the 1st or 2nd skb in write queue. 218275eefc6cSEric Dumazet * No need to wait for TX completion to call us back, 218375eefc6cSEric Dumazet * after softirq/tasklet schedule. 218475eefc6cSEric Dumazet * This helps when TX completions are delayed too much. 218575eefc6cSEric Dumazet */ 218675eefc6cSEric Dumazet if (skb == sk->sk_write_queue.next || 218775eefc6cSEric Dumazet skb->prev == sk->sk_write_queue.next) 218875eefc6cSEric Dumazet return false; 218975eefc6cSEric Dumazet 21907aa5470cSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2191f9616c35SEric Dumazet /* It is possible TX completion already happened 2192f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2193f9616c35SEric Dumazet * test again the condition. 2194f9616c35SEric Dumazet */ 2195f9616c35SEric Dumazet smp_mb__after_atomic(); 219614afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) 2197f9616c35SEric Dumazet return true; 2198f9616c35SEric Dumazet } 2199f9616c35SEric Dumazet return false; 2200f9616c35SEric Dumazet } 2201f9616c35SEric Dumazet 220205b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 220305b055e8SFrancis Yan { 2204628174ccSEric Dumazet const u32 now = tcp_jiffies32; 220505b055e8SFrancis Yan 220605b055e8SFrancis Yan if (tp->chrono_type > TCP_CHRONO_UNSPEC) 220705b055e8SFrancis Yan tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start; 220805b055e8SFrancis Yan tp->chrono_start = now; 220905b055e8SFrancis Yan tp->chrono_type = new; 221005b055e8SFrancis Yan } 221105b055e8SFrancis Yan 221205b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 221305b055e8SFrancis Yan { 221405b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 221505b055e8SFrancis Yan 221605b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 22170f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 22180f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 221905b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 222005b055e8SFrancis Yan */ 222105b055e8SFrancis Yan if (type > tp->chrono_type) 222205b055e8SFrancis Yan tcp_chrono_set(tp, type); 222305b055e8SFrancis Yan } 222405b055e8SFrancis Yan 222505b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 222605b055e8SFrancis Yan { 222705b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 222805b055e8SFrancis Yan 22290f87230dSFrancis Yan 22300f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 22310f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 22320f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 22330f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 22340f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 22350f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 22360f87230dSFrancis Yan */ 22370f87230dSFrancis Yan if (tcp_write_queue_empty(sk)) 223805b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 22390f87230dSFrancis Yan else if (type == tp->chrono_type) 22400f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 224105b055e8SFrancis Yan } 224205b055e8SFrancis Yan 22431da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 22441da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 22451da177e4SLinus Torvalds * window for us. 22461da177e4SLinus Torvalds * 2247f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2248f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2249f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2250f8269a49SIlpo Järvinen * 22516ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 22526ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 22536ba8a3b1SNandita Dukkipati 2254a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2255a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 22561da177e4SLinus Torvalds */ 2257a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2258d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 22591da177e4SLinus Torvalds { 22601da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 226192df7b51SDavid S. Miller struct sk_buff *skb; 2262c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2263c1b4a7e6SDavid S. Miller int cwnd_quota; 22645d424d5aSJohn Heffner int result; 22655615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2266605ad7f1SEric Dumazet u32 max_segs; 22671da177e4SLinus Torvalds 2268c1b4a7e6SDavid S. Miller sent_pkts = 0; 22695d424d5aSJohn Heffner 2270d5dd9175SIlpo Järvinen if (!push_one) { 22715d424d5aSJohn Heffner /* Do MTU probing. */ 2272d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2273d5dd9175SIlpo Järvinen if (!result) { 2274a2a385d6SEric Dumazet return false; 22755d424d5aSJohn Heffner } else if (result > 0) { 22765d424d5aSJohn Heffner sent_pkts = 1; 22775d424d5aSJohn Heffner } 2278d5dd9175SIlpo Järvinen } 22795d424d5aSJohn Heffner 2280ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 22819a568de4SEric Dumazet tcp_mstamp_refresh(tp); 2282fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2283c8ac3774SHerbert Xu unsigned int limit; 2284c8ac3774SHerbert Xu 2285218af599SEric Dumazet if (tcp_pacing_check(sk)) 2286218af599SEric Dumazet break; 2287218af599SEric Dumazet 22885bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2289c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2290c1b4a7e6SDavid S. Miller 22919d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 22927faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 2293385e2070SEric Dumazet skb->skb_mstamp = tp->tcp_mstamp; 2294ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 22959d186cacSAndrey Vagin } 2296ec342325SAndrew Vagin 2297b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 22986ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 22996ba8a3b1SNandita Dukkipati if (push_one == 2) 23006ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 23016ba8a3b1SNandita Dukkipati cwnd_quota = 1; 23026ba8a3b1SNandita Dukkipati else 2303b68e9f85SHerbert Xu break; 23046ba8a3b1SNandita Dukkipati } 2305b68e9f85SHerbert Xu 23065615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 23075615f886SFrancis Yan is_rwnd_limited = true; 2308b68e9f85SHerbert Xu break; 23095615f886SFrancis Yan } 2310b68e9f85SHerbert Xu 2311d6a4e26aSEric Dumazet if (tso_segs == 1) { 2312aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2313aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2314aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2315aa93466bSDavid S. Miller break; 2316c1b4a7e6SDavid S. Miller } else { 2317ca8a2263SNeal Cardwell if (!push_one && 2318605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2319605ad7f1SEric Dumazet max_segs)) 2320aa93466bSDavid S. Miller break; 2321c1b4a7e6SDavid S. Miller } 2322aa93466bSDavid S. Miller 2323605ad7f1SEric Dumazet limit = mss_now; 2324d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2325605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2326605ad7f1SEric Dumazet min_t(unsigned int, 2327605ad7f1SEric Dumazet cwnd_quota, 2328605ad7f1SEric Dumazet max_segs), 2329605ad7f1SEric Dumazet nonagle); 2330605ad7f1SEric Dumazet 2331605ad7f1SEric Dumazet if (skb->len > limit && 2332605ad7f1SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2333605ad7f1SEric Dumazet break; 2334605ad7f1SEric Dumazet 23357aa5470cSEric Dumazet if (test_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) 23367aa5470cSEric Dumazet clear_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags); 2337f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 233846d3ceabSEric Dumazet break; 2339c9eeec26SEric Dumazet 2340d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 23411da177e4SLinus Torvalds break; 23421da177e4SLinus Torvalds 2343ec342325SAndrew Vagin repair: 23441da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 23451da177e4SLinus Torvalds * This call will increment packets_out. 23461da177e4SLinus Torvalds */ 234766f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2350a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2351d5dd9175SIlpo Järvinen 2352d5dd9175SIlpo Järvinen if (push_one) 2353d5dd9175SIlpo Järvinen break; 23541da177e4SLinus Torvalds } 23551da177e4SLinus Torvalds 23565615f886SFrancis Yan if (is_rwnd_limited) 23575615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 23585615f886SFrancis Yan else 23595615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 23605615f886SFrancis Yan 2361aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2362684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2363684bad11SYuchung Cheng tp->prr_out += sent_pkts; 23646ba8a3b1SNandita Dukkipati 23656ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 23666ba8a3b1SNandita Dukkipati if (push_one != 2) 23676ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 2368d2e1339fSBendik Rønning Opstad is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); 2369ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2370a2a385d6SEric Dumazet return false; 23711da177e4SLinus Torvalds } 2372b340b264SYuchung Cheng return !tp->packets_out && tcp_send_head(sk); 23736ba8a3b1SNandita Dukkipati } 23746ba8a3b1SNandita Dukkipati 23756ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 23766ba8a3b1SNandita Dukkipati { 23776ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 23786ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 23796ba8a3b1SNandita Dukkipati u32 timeout, tlp_time_stamp, rto_time_stamp; 2380740b0f18SEric Dumazet u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); 23816ba8a3b1SNandita Dukkipati 23826ba8a3b1SNandita Dukkipati /* No consecutive loss probes. */ 23836ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { 23846ba8a3b1SNandita Dukkipati tcp_rearm_rto(sk); 23856ba8a3b1SNandita Dukkipati return false; 23866ba8a3b1SNandita Dukkipati } 23876ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 23886ba8a3b1SNandita Dukkipati * finishes. 23896ba8a3b1SNandita Dukkipati */ 2390f9b99582SYuchung Cheng if (tp->fastopen_rsk) 23916ba8a3b1SNandita Dukkipati return false; 23926ba8a3b1SNandita Dukkipati 23936ba8a3b1SNandita Dukkipati /* TLP is only scheduled when next timer event is RTO. */ 23946ba8a3b1SNandita Dukkipati if (icsk->icsk_pending != ICSK_TIME_RETRANS) 23956ba8a3b1SNandita Dukkipati return false; 23966ba8a3b1SNandita Dukkipati 23976ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 23986ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 23996ba8a3b1SNandita Dukkipati */ 2400bec41a11SYuchung Cheng if ((sysctl_tcp_early_retrans != 3 && sysctl_tcp_early_retrans != 4) || 2401bec41a11SYuchung Cheng !tp->packets_out || !tcp_is_sack(tp) || 2402bec41a11SYuchung Cheng icsk->icsk_ca_state != TCP_CA_Open) 24036ba8a3b1SNandita Dukkipati return false; 24046ba8a3b1SNandita Dukkipati 24056ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 24066ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 24076ba8a3b1SNandita Dukkipati return false; 24086ba8a3b1SNandita Dukkipati 24096ba8a3b1SNandita Dukkipati /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account 2410f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2411f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 24126ba8a3b1SNandita Dukkipati */ 2413f9b99582SYuchung Cheng timeout = rtt << 1 ? : TCP_TIMEOUT_INIT; 24146ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 24156ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, 24166ba8a3b1SNandita Dukkipati (rtt + (rtt >> 1) + TCP_DELACK_MAX)); 24176ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, msecs_to_jiffies(10)); 24186ba8a3b1SNandita Dukkipati 24196ba8a3b1SNandita Dukkipati /* If RTO is shorter, just schedule TLP in its place. */ 2420ac9517fcSEric Dumazet tlp_time_stamp = tcp_jiffies32 + timeout; 24216ba8a3b1SNandita Dukkipati rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; 24226ba8a3b1SNandita Dukkipati if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { 2423ac9517fcSEric Dumazet s32 delta = rto_time_stamp - tcp_jiffies32; 24246ba8a3b1SNandita Dukkipati if (delta > 0) 24256ba8a3b1SNandita Dukkipati timeout = delta; 24266ba8a3b1SNandita Dukkipati } 24276ba8a3b1SNandita Dukkipati 24286ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 24296ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 24306ba8a3b1SNandita Dukkipati return true; 24316ba8a3b1SNandita Dukkipati } 24326ba8a3b1SNandita Dukkipati 24331f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 24341f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 24351f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 24361f3279aeSEric Dumazet */ 24371f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 24381f3279aeSEric Dumazet const struct sk_buff *skb) 24391f3279aeSEric Dumazet { 244039bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2441c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 24421f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 24431f3279aeSEric Dumazet return true; 24441f3279aeSEric Dumazet } 24451f3279aeSEric Dumazet return false; 24461f3279aeSEric Dumazet } 24471f3279aeSEric Dumazet 2448b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 24496ba8a3b1SNandita Dukkipati * retransmit the last segment. 24506ba8a3b1SNandita Dukkipati */ 24516ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 24526ba8a3b1SNandita Dukkipati { 24539b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 24546ba8a3b1SNandita Dukkipati struct sk_buff *skb; 24556ba8a3b1SNandita Dukkipati int pcount; 24566ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 24576ba8a3b1SNandita Dukkipati 2458b340b264SYuchung Cheng skb = tcp_send_head(sk); 2459b340b264SYuchung Cheng if (skb) { 2460b340b264SYuchung Cheng if (tcp_snd_wnd_test(tp, skb, mss)) { 2461b340b264SYuchung Cheng pcount = tp->packets_out; 2462b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2463b340b264SYuchung Cheng if (tp->packets_out > pcount) 2464b340b264SYuchung Cheng goto probe_sent; 24656ba8a3b1SNandita Dukkipati goto rearm_timer; 24666ba8a3b1SNandita Dukkipati } 2467b340b264SYuchung Cheng skb = tcp_write_queue_prev(sk, skb); 2468b340b264SYuchung Cheng } else { 2469b340b264SYuchung Cheng skb = tcp_write_queue_tail(sk); 2470b340b264SYuchung Cheng } 24716ba8a3b1SNandita Dukkipati 24729b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 24739b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 24749b717a8dSNandita Dukkipati goto rearm_timer; 24759b717a8dSNandita Dukkipati 24766ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 24776ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 24786ba8a3b1SNandita Dukkipati goto rearm_timer; 24796ba8a3b1SNandita Dukkipati 24801f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 24811f3279aeSEric Dumazet goto rearm_timer; 24821f3279aeSEric Dumazet 24836ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 24846ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 24856ba8a3b1SNandita Dukkipati goto rearm_timer; 24866ba8a3b1SNandita Dukkipati 24876ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 24886cc55e09SOctavian Purdila if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, 24896cc55e09SOctavian Purdila GFP_ATOMIC))) 24906ba8a3b1SNandita Dukkipati goto rearm_timer; 2491b340b264SYuchung Cheng skb = tcp_write_queue_next(sk, skb); 24926ba8a3b1SNandita Dukkipati } 24936ba8a3b1SNandita Dukkipati 24946ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 24956ba8a3b1SNandita Dukkipati goto rearm_timer; 24966ba8a3b1SNandita Dukkipati 249710d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2498b340b264SYuchung Cheng goto rearm_timer; 24996ba8a3b1SNandita Dukkipati 25009b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 25019b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 25029b717a8dSNandita Dukkipati 2503b340b264SYuchung Cheng probe_sent: 2504c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2505fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2506fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2507b340b264SYuchung Cheng rearm_timer: 2508fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 25091da177e4SLinus Torvalds } 25101da177e4SLinus Torvalds 2511a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2512a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2513a762a980SDavid S. Miller * The socket must be locked by the caller. 2514a762a980SDavid S. Miller */ 25159e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 25169e412ba7SIlpo Järvinen int nonagle) 2517a762a980SDavid S. Miller { 2518726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2519726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2520726e07a8SIlpo Järvinen * all will be happy. 2521726e07a8SIlpo Järvinen */ 2522726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2523726e07a8SIlpo Järvinen return; 2524726e07a8SIlpo Järvinen 252599a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 25267450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 25279e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2528a762a980SDavid S. Miller } 2529a762a980SDavid S. Miller 2530c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2531c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2532c1b4a7e6SDavid S. Miller */ 2533c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2534c1b4a7e6SDavid S. Miller { 2535fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2536c1b4a7e6SDavid S. Miller 2537c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2538c1b4a7e6SDavid S. Miller 2539d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2540c1b4a7e6SDavid S. Miller } 2541c1b4a7e6SDavid S. Miller 25421da177e4SLinus Torvalds /* This function returns the amount that we can raise the 25431da177e4SLinus Torvalds * usable window based on the following constraints 25441da177e4SLinus Torvalds * 25451da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 25461da177e4SLinus Torvalds * 2. We limit memory per socket 25471da177e4SLinus Torvalds * 25481da177e4SLinus Torvalds * RFC 1122: 25491da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 25501da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 25511da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 25521da177e4SLinus Torvalds * 25531da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 25541da177e4SLinus Torvalds * it at least MSS bytes. 25551da177e4SLinus Torvalds * 25561da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 25571da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 25581da177e4SLinus Torvalds * 25591da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 25601da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 25611da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 25621da177e4SLinus Torvalds * window to always advance by a single byte. 25631da177e4SLinus Torvalds * 25641da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 25651da177e4SLinus Torvalds * then this will not be a problem. 25661da177e4SLinus Torvalds * 25671da177e4SLinus Torvalds * BSD seems to make the following compromise: 25681da177e4SLinus Torvalds * 25691da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 25701da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 25711da177e4SLinus Torvalds * then set the window to 0. 25721da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 25731da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 25741da177e4SLinus Torvalds * and from being larger than the largest representable value. 25751da177e4SLinus Torvalds * 25761da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 25771da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 25781da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 25791da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 25801da177e4SLinus Torvalds * because the pipeline is full. 25811da177e4SLinus Torvalds * 25821da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 25831da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 25841da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 25851da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 25861da177e4SLinus Torvalds * of having a fixed window size at almost all times. 25871da177e4SLinus Torvalds * 25881da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 25891da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 25901da177e4SLinus Torvalds * 25911da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 25921da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 25931da177e4SLinus Torvalds */ 25941da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 25951da177e4SLinus Torvalds { 2596463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 25971da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2598caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 25991da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 26001da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 26011da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 26021da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 26031da177e4SLinus Torvalds */ 2604463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 26051da177e4SLinus Torvalds int free_space = tcp_space(sk); 260686c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 260786c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 26081da177e4SLinus Torvalds int window; 26091da177e4SLinus Torvalds 261006425c30SEric Dumazet if (unlikely(mss > full_space)) { 26111da177e4SLinus Torvalds mss = full_space; 261206425c30SEric Dumazet if (mss <= 0) 261306425c30SEric Dumazet return 0; 261406425c30SEric Dumazet } 2615b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2616463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 26171da177e4SLinus Torvalds 2618b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 2619056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2620056834d9SIlpo Järvinen 4U * tp->advmss); 26211da177e4SLinus Torvalds 262286c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 262386c1a045SFlorian Westphal * increase it due to wscale. 262486c1a045SFlorian Westphal */ 262586c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 262686c1a045SFlorian Westphal 262786c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 262886c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 262986c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 263086c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 263186c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 263286c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 263386c1a045SFlorian Westphal */ 263486c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 26351da177e4SLinus Torvalds return 0; 26361da177e4SLinus Torvalds } 26371da177e4SLinus Torvalds 26381da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 26391da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 26401da177e4SLinus Torvalds 26411da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 26421da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 26431da177e4SLinus Torvalds */ 26441da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 26451da177e4SLinus Torvalds window = free_space; 26461da177e4SLinus Torvalds 26471da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 26481da177e4SLinus Torvalds * Import case: prevent zero window announcement if 26491da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 26501da177e4SLinus Torvalds */ 26511935299dSGao Feng window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); 26521da177e4SLinus Torvalds } else { 26531935299dSGao Feng window = tp->rcv_wnd; 26541da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 26551da177e4SLinus Torvalds * Window clamp already applied above. 26561da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 26571da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 26581da177e4SLinus Torvalds * and multiply from happening most of the time. 26591da177e4SLinus Torvalds * We also don't do any window rounding when the free space 26601da177e4SLinus Torvalds * is too small. 26611da177e4SLinus Torvalds */ 26621da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 26631935299dSGao Feng window = rounddown(free_space, mss); 266484565070SJohn Heffner else if (mss == full_space && 2665b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 266684565070SJohn Heffner window = free_space; 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds 26691da177e4SLinus Torvalds return window; 26701da177e4SLinus Torvalds } 26711da177e4SLinus Torvalds 2672cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 2673082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 2674082ac2d5SMartin KaFai Lau { 26750a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 26760a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 26770a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 2678082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 2679082ac2d5SMartin KaFai Lau 26800a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 2681082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 26822de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 26832de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 2684082ac2d5SMartin KaFai Lau } 2685082ac2d5SMartin KaFai Lau } 2686082ac2d5SMartin KaFai Lau 26874a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 2688f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 26891da177e4SLinus Torvalds { 26901da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2691fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2692058dc334SIlpo Järvinen int skb_size, next_skb_size; 26931da177e4SLinus Torvalds 2694058dc334SIlpo Järvinen skb_size = skb->len; 2695058dc334SIlpo Järvinen next_skb_size = next_skb->len; 26961da177e4SLinus Torvalds 2697058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 26981da177e4SLinus Torvalds 2699f8071cdeSEric Dumazet if (next_skb_size) { 2700f8071cdeSEric Dumazet if (next_skb_size <= skb_availroom(skb)) 2701f8071cdeSEric Dumazet skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), 2702f8071cdeSEric Dumazet next_skb_size); 2703f8071cdeSEric Dumazet else if (!skb_shift(skb, next_skb, next_skb_size)) 2704f8071cdeSEric Dumazet return false; 2705f8071cdeSEric Dumazet } 27066859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 2707a6963a6bSIlpo Järvinen 2708fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 27091da177e4SLinus Torvalds 271052d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 271152d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 27121da177e4SLinus Torvalds 271384fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 27141da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 27151da177e4SLinus Torvalds 27161da177e4SLinus Torvalds /* Update sequence range on original skb. */ 27171da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 27181da177e4SLinus Torvalds 2719e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 27204de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 27231da177e4SLinus Torvalds * packet counting does not break. 27241da177e4SLinus Torvalds */ 27254828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2726a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 2727b7689205SIlpo Järvinen 2728b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2729ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2730ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2731ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2732b7689205SIlpo Järvinen 2733797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2734797108d1SIlpo Järvinen 2735082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 2736082ac2d5SMartin KaFai Lau 27373ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 2738f8071cdeSEric Dumazet return true; 27391da177e4SLinus Torvalds } 27401da177e4SLinus Torvalds 274167edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2742a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 27434a17fc3aSIlpo Järvinen { 27444a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2745a2a385d6SEric Dumazet return false; 27464a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2747a2a385d6SEric Dumazet return false; 27484a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2749a2a385d6SEric Dumazet return false; 27502331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 27514a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2752a2a385d6SEric Dumazet return false; 27534a17fc3aSIlpo Järvinen 2754a2a385d6SEric Dumazet return true; 27554a17fc3aSIlpo Järvinen } 27564a17fc3aSIlpo Järvinen 275767edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 275867edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 275967edfef7SAndi Kleen */ 27604a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 27614a17fc3aSIlpo Järvinen int space) 27624a17fc3aSIlpo Järvinen { 27634a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 27644a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2765a2a385d6SEric Dumazet bool first = true; 27664a17fc3aSIlpo Järvinen 27674a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 27684a17fc3aSIlpo Järvinen return; 27694de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 27704a17fc3aSIlpo Järvinen return; 27714a17fc3aSIlpo Järvinen 27724a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 27734a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 27744a17fc3aSIlpo Järvinen break; 27754a17fc3aSIlpo Järvinen 2776a643b5d4SMartin KaFai Lau if (!tcp_skb_can_collapse_to(to)) 2777a643b5d4SMartin KaFai Lau break; 2778a643b5d4SMartin KaFai Lau 27794a17fc3aSIlpo Järvinen space -= skb->len; 27804a17fc3aSIlpo Järvinen 27814a17fc3aSIlpo Järvinen if (first) { 2782a2a385d6SEric Dumazet first = false; 27834a17fc3aSIlpo Järvinen continue; 27844a17fc3aSIlpo Järvinen } 27854a17fc3aSIlpo Järvinen 27864a17fc3aSIlpo Järvinen if (space < 0) 27874a17fc3aSIlpo Järvinen break; 27884a17fc3aSIlpo Järvinen 27894a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 27904a17fc3aSIlpo Järvinen break; 27914a17fc3aSIlpo Järvinen 2792f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 2793f8071cdeSEric Dumazet break; 27944a17fc3aSIlpo Järvinen } 27954a17fc3aSIlpo Järvinen } 27964a17fc3aSIlpo Järvinen 27971da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 27981da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 27991da177e4SLinus Torvalds * error occurred which prevented the send. 28001da177e4SLinus Torvalds */ 280110d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 28021da177e4SLinus Torvalds { 28035d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 280410d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 28057d227cd2SSridhar Samudrala unsigned int cur_mss; 280610d3be56SEric Dumazet int diff, len, err; 28071da177e4SLinus Torvalds 280810d3be56SEric Dumazet 280910d3be56SEric Dumazet /* Inconclusive MTU probe */ 281010d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 28115d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 28125d424d5aSJohn Heffner 28131da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2814caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 28151da177e4SLinus Torvalds */ 281614afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > 2817ffb4d6c8SEric Dumazet min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), 2818ffb4d6c8SEric Dumazet sk->sk_sndbuf)) 28191da177e4SLinus Torvalds return -EAGAIN; 28201da177e4SLinus Torvalds 28211f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 28221f3279aeSEric Dumazet return -EBUSY; 28231f3279aeSEric Dumazet 28241da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 28251da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 28261da177e4SLinus Torvalds BUG(); 28271da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 28281da177e4SLinus Torvalds return -ENOMEM; 28291da177e4SLinus Torvalds } 28301da177e4SLinus Torvalds 28317d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 28327d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 28337d227cd2SSridhar Samudrala 28340c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 28357d227cd2SSridhar Samudrala 28361da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 28371da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 28381da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 28391da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 28401da177e4SLinus Torvalds */ 28419d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 28429d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 28431da177e4SLinus Torvalds return -EAGAIN; 28441da177e4SLinus Torvalds 284510d3be56SEric Dumazet len = cur_mss * segs; 284610d3be56SEric Dumazet if (skb->len > len) { 284710d3be56SEric Dumazet if (tcp_fragment(sk, skb, len, cur_mss, GFP_ATOMIC)) 28481da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 284902276f3cSIlpo Järvinen } else { 2850c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2851c52e2421SEric Dumazet return -ENOMEM; 285210d3be56SEric Dumazet 285310d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 285410d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 285510d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 285610d3be56SEric Dumazet if (diff) 285710d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 285810d3be56SEric Dumazet if (skb->len < cur_mss) 285910d3be56SEric Dumazet tcp_retrans_try_collapse(sk, skb, cur_mss); 28601da177e4SLinus Torvalds } 28611da177e4SLinus Torvalds 286249213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 286349213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 286449213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 286549213555SDaniel Borkmann 2866678550c6SYuchung Cheng /* Update global and local TCP statistics. */ 2867678550c6SYuchung Cheng segs = tcp_skb_pcount(skb); 2868678550c6SYuchung Cheng TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 2869678550c6SYuchung Cheng if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 2870678550c6SYuchung Cheng __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 2871678550c6SYuchung Cheng tp->total_retrans += segs; 2872678550c6SYuchung Cheng 287350bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 287450bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 287550bceae9SThomas Graf * beyond what csum_start can cover. 287650bceae9SThomas Graf */ 287750bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 287850bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 287910a81980SEric Dumazet struct sk_buff *nskb; 288010a81980SEric Dumazet 2881385e2070SEric Dumazet skb->skb_mstamp = tp->tcp_mstamp; 288210a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 2883c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2884117632e6SEric Dumazet -ENOBUFS; 2885117632e6SEric Dumazet } else { 2886c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2887117632e6SEric Dumazet } 2888c84a5711SYuchung Cheng 2889fc9f3501SEric Dumazet if (likely(!err)) { 2890c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2891678550c6SYuchung Cheng } else if (err != -EBUSY) { 2892678550c6SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 2893fc9f3501SEric Dumazet } 2894c84a5711SYuchung Cheng return err; 289593b174adSYuchung Cheng } 289693b174adSYuchung Cheng 289710d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 289893b174adSYuchung Cheng { 289993b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 290010d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 29011da177e4SLinus Torvalds 29021da177e4SLinus Torvalds if (err == 0) { 29031da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 29041da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2905e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 29061da177e4SLinus Torvalds } 29071da177e4SLinus Torvalds #endif 29081da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 29091da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 29101da177e4SLinus Torvalds 29111da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 29121da177e4SLinus Torvalds if (!tp->retrans_stamp) 29137faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 29141da177e4SLinus Torvalds 29151da177e4SLinus Torvalds } 29166e08d5e3SYuchung Cheng 29176e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 29186e08d5e3SYuchung Cheng tp->undo_retrans = 0; 29196e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 29201da177e4SLinus Torvalds return err; 29211da177e4SLinus Torvalds } 29221da177e4SLinus Torvalds 29231da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 29241da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 29251da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 29261da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 29271da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 29281da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 29291da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 29301da177e4SLinus Torvalds */ 29311da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 29321da177e4SLinus Torvalds { 29336687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 29341da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 29351da177e4SLinus Torvalds struct sk_buff *skb; 29360e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2937840a3cbeSYuchung Cheng u32 max_segs; 293861eb55f4SIlpo Järvinen int mib_idx; 29396a438bbeSStephen Hemminger 294045e77d31SIlpo Järvinen if (!tp->packets_out) 294145e77d31SIlpo Järvinen return; 294245e77d31SIlpo Järvinen 2943618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 29446a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2945618d9f25SIlpo Järvinen } else { 2946fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2947618d9f25SIlpo Järvinen } 29481da177e4SLinus Torvalds 2949ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 2950fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 2951dca0aaf8SEric Dumazet __u8 sacked; 295210d3be56SEric Dumazet int segs; 29531da177e4SLinus Torvalds 2954fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2955fe067e8aSDavid S. Miller break; 2956218af599SEric Dumazet 2957218af599SEric Dumazet if (tcp_pacing_check(sk)) 2958218af599SEric Dumazet break; 2959218af599SEric Dumazet 29606a438bbeSStephen Hemminger /* we could do better than to assign each time */ 296151456b29SIan Morris if (!hole) 29626a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 29636a438bbeSStephen Hemminger 296410d3be56SEric Dumazet segs = tp->snd_cwnd - tcp_packets_in_flight(tp); 296510d3be56SEric Dumazet if (segs <= 0) 29661da177e4SLinus Torvalds return; 2967dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 2968a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 2969a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 2970a3d2e9f8SEric Dumazet */ 2971a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 29720e1c54c2SIlpo Järvinen 2973840a3cbeSYuchung Cheng if (tp->retrans_out >= tp->lost_out) { 2974006f582cSIlpo Järvinen break; 29750e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 297651456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 29770e1c54c2SIlpo Järvinen hole = skb; 297861eb55f4SIlpo Järvinen continue; 29791da177e4SLinus Torvalds 29800e1c54c2SIlpo Järvinen } else { 29810e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 29820e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 29830e1c54c2SIlpo Järvinen else 29840e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 29850e1c54c2SIlpo Järvinen } 29860e1c54c2SIlpo Järvinen 29870e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 298861eb55f4SIlpo Järvinen continue; 298940b215e5SPavel Emelyanov 2990f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 2991f9616c35SEric Dumazet return; 2992f9616c35SEric Dumazet 299310d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 29941da177e4SLinus Torvalds return; 299524ab6becSYuchung Cheng 2996de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 29971da177e4SLinus Torvalds 2998684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2999a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 3000a262f0cdSNandita Dukkipati 300157dde7f7SYuchung Cheng if (skb == tcp_write_queue_head(sk) && 300257dde7f7SYuchung Cheng icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) 3003463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 30043f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 30053f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 30061da177e4SLinus Torvalds } 30071da177e4SLinus Torvalds } 30081da177e4SLinus Torvalds 3009d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 3010d83769a5SEric Dumazet * connection tear down and (memory) recovery. 3011845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 3012845704a5SEric Dumazet * or even be forced to close flow without any FIN. 3013a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 3014a6c5ea4cSEric Dumazet * with edge trigger epoll() 3015d83769a5SEric Dumazet */ 3016a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 3017d83769a5SEric Dumazet { 3018e805605cSJohannes Weiner int amt; 3019d83769a5SEric Dumazet 3020d83769a5SEric Dumazet if (size <= sk->sk_forward_alloc) 3021d83769a5SEric Dumazet return; 3022d83769a5SEric Dumazet amt = sk_mem_pages(size); 3023d83769a5SEric Dumazet sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; 3024e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 3025e805605cSJohannes Weiner 3026baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 3027baac50bbSJohannes Weiner mem_cgroup_charge_skmem(sk->sk_memcg, amt); 3028d83769a5SEric Dumazet } 3029d83769a5SEric Dumazet 3030845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 3031845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 30321da177e4SLinus Torvalds */ 30331da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 30341da177e4SLinus Torvalds { 3035845704a5SEric Dumazet struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); 30361da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 30371da177e4SLinus Torvalds 3038845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 3039845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 3040845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 3041845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 30421da177e4SLinus Torvalds */ 3043b8da51ebSEric Dumazet if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) { 3044845704a5SEric Dumazet coalesce: 3045845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 3046845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 30471da177e4SLinus Torvalds tp->write_seq++; 3048845704a5SEric Dumazet if (!tcp_send_head(sk)) { 3049845704a5SEric Dumazet /* This means tskb was already sent. 3050845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 3051845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 3052845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 3053845704a5SEric Dumazet * does not change tp->snd_nxt. 3054845704a5SEric Dumazet */ 3055845704a5SEric Dumazet tp->snd_nxt++; 3056845704a5SEric Dumazet return; 3057845704a5SEric Dumazet } 30581da177e4SLinus Torvalds } else { 3059845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3060845704a5SEric Dumazet if (unlikely(!skb)) { 3061845704a5SEric Dumazet if (tskb) 3062845704a5SEric Dumazet goto coalesce; 3063845704a5SEric Dumazet return; 30641da177e4SLinus Torvalds } 3065d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3066a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 30671da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3068e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3069a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 30701da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 30711da177e4SLinus Torvalds } 3072845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 30731da177e4SLinus Torvalds } 30741da177e4SLinus Torvalds 30751da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 30761da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 30771da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 307865bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 30791da177e4SLinus Torvalds */ 3080dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 30811da177e4SLinus Torvalds { 30821da177e4SLinus Torvalds struct sk_buff *skb; 30831da177e4SLinus Torvalds 30847cc2b043SGao Feng TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 30857cc2b043SGao Feng 30861da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 30871da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 30881da177e4SLinus Torvalds if (!skb) { 30894e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 30901da177e4SLinus Torvalds return; 30911da177e4SLinus Torvalds } 30921da177e4SLinus Torvalds 30931da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 30941da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3095e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3096a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 30979a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 30981da177e4SLinus Torvalds /* Send it off. */ 3099dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 31004e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 31011da177e4SLinus Torvalds } 31021da177e4SLinus Torvalds 310367edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 310467edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 31051da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 31061da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 31071da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 31081da177e4SLinus Torvalds */ 31091da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 31101da177e4SLinus Torvalds { 31111da177e4SLinus Torvalds struct sk_buff *skb; 31121da177e4SLinus Torvalds 3113fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 311451456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 311591df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 31161da177e4SLinus Torvalds return -EFAULT; 31171da177e4SLinus Torvalds } 31184de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 31191da177e4SLinus Torvalds if (skb_cloned(skb)) { 31201da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 312151456b29SIan Morris if (!nskb) 31221da177e4SLinus Torvalds return -ENOMEM; 3123fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 3124f4a775d1SEric Dumazet __skb_header_release(nskb); 3125fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 31263ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 31273ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 31283ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 31291da177e4SLinus Torvalds skb = nskb; 31301da177e4SLinus Torvalds } 31311da177e4SLinus Torvalds 31324de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3133735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 31341da177e4SLinus Torvalds } 3135dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 31361da177e4SLinus Torvalds } 31371da177e4SLinus Torvalds 31384aea39c1SEric Dumazet /** 31394aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 31404aea39c1SEric Dumazet * sk: listener socket 31414aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 31424aea39c1SEric Dumazet * req: request_sock pointer 31434aea39c1SEric Dumazet * 31444aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 31454aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 31464aea39c1SEric Dumazet */ 31475d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3148e6b4d113SWilliam Allen Simpson struct request_sock *req, 3149ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3150b3d05147SEric Dumazet enum tcp_synack_type synack_type) 31511da177e4SLinus Torvalds { 31522e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 31535d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 315480f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 31555d062de7SEric Dumazet struct tcp_out_options opts; 31565d062de7SEric Dumazet struct sk_buff *skb; 3157bd0388aeSWilliam Allen Simpson int tcp_header_size; 31585d062de7SEric Dumazet struct tcphdr *th; 3159f5fff5dcSTom Quetchenbach int mss; 31601da177e4SLinus Torvalds 3161ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 31624aea39c1SEric Dumazet if (unlikely(!skb)) { 31634aea39c1SEric Dumazet dst_release(dst); 31641da177e4SLinus Torvalds return NULL; 31654aea39c1SEric Dumazet } 31661da177e4SLinus Torvalds /* Reserve space for headers. */ 31671da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 31681da177e4SLinus Torvalds 3169b3d05147SEric Dumazet switch (synack_type) { 3170b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 31719e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3172b3d05147SEric Dumazet break; 3173b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3174b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3175b3d05147SEric Dumazet * to avoid false sharing. 3176b3d05147SEric Dumazet */ 3177b3d05147SEric Dumazet break; 3178b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3179ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3180ca6fb065SEric Dumazet * cpu might call us concurrently. 3181ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3182ca6fb065SEric Dumazet */ 3183ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3184b3d05147SEric Dumazet break; 3185ca6fb065SEric Dumazet } 31864aea39c1SEric Dumazet skb_dst_set(skb, dst); 31871da177e4SLinus Torvalds 31883541f9e8SEric Dumazet mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3189f5fff5dcSTom Quetchenbach 319033ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 31918b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 31928b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 31939a568de4SEric Dumazet skb->skb_mstamp = cookie_init_timestamp(req); 31948b5f12d0SFlorian Westphal else 31958b5f12d0SFlorian Westphal #endif 31969a568de4SEric Dumazet skb->skb_mstamp = tcp_clock_us(); 319780f03e27SEric Dumazet 319880f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 319980f03e27SEric Dumazet rcu_read_lock(); 3200fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 320180f03e27SEric Dumazet #endif 320258d607d3SEric Dumazet skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); 320337bfbddaSEric Dumazet tcp_header_size = tcp_synack_options(req, mss, skb, &opts, md5, foc) + 320437bfbddaSEric Dumazet sizeof(*th); 320533ad798cSAdam Langley 3206aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3207aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 32081da177e4SLinus Torvalds 3209ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 32101da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 32111da177e4SLinus Torvalds th->syn = 1; 32121da177e4SLinus Torvalds th->ack = 1; 32136ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3214b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3215634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3216e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 3217e870a8efSIlpo Järvinen * not even correctly set) 3218e870a8efSIlpo Järvinen */ 3219e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 3220a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 32214957faadSWilliam Allen Simpson 32221da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 32238336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 32248336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 32251da177e4SLinus Torvalds 32261da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3227ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 32285d062de7SEric Dumazet tcp_options_write((__be32 *)(th + 1), NULL, &opts); 32291da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 323090bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3231cfb6eeb4SYOSHIFUJI Hideaki 3232cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3233cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 323480f03e27SEric Dumazet if (md5) 3235bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 323639f8e58eSEric Dumazet md5, req_to_sk(req), skb); 323780f03e27SEric Dumazet rcu_read_unlock(); 3238cfb6eeb4SYOSHIFUJI Hideaki #endif 3239cfb6eeb4SYOSHIFUJI Hideaki 3240b50edd78SEric Dumazet /* Do not fool tcpdump (if any), clean our debris */ 32412456e855SThomas Gleixner skb->tstamp = 0; 32421da177e4SLinus Torvalds return skb; 32431da177e4SLinus Torvalds } 32444bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 32451da177e4SLinus Torvalds 324681164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 324781164413SDaniel Borkmann { 324881164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 324981164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 325081164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 325181164413SDaniel Borkmann 325281164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 325381164413SDaniel Borkmann return; 325481164413SDaniel Borkmann 325581164413SDaniel Borkmann rcu_read_lock(); 325681164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 325781164413SDaniel Borkmann if (likely(ca && try_module_get(ca->owner))) { 325881164413SDaniel Borkmann module_put(icsk->icsk_ca_ops->owner); 325981164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 326081164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 326181164413SDaniel Borkmann } 326281164413SDaniel Borkmann rcu_read_unlock(); 326381164413SDaniel Borkmann } 326481164413SDaniel Borkmann 326567edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3266f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 32671da177e4SLinus Torvalds { 3268cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 32691da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32701da177e4SLinus Torvalds __u8 rcv_wscale; 327113d3b1ebSLawrence Brakmo u32 rcv_wnd; 32721da177e4SLinus Torvalds 32731da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 32741da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 32751da177e4SLinus Torvalds */ 32765d2ed052SEric Dumazet tp->tcp_header_len = sizeof(struct tcphdr); 32775d2ed052SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_timestamps) 32785d2ed052SEric Dumazet tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; 32791da177e4SLinus Torvalds 3280cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 328100db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3282cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3283cfb6eeb4SYOSHIFUJI Hideaki #endif 3284cfb6eeb4SYOSHIFUJI Hideaki 32851da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 32861da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 32871da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 32881da177e4SLinus Torvalds tp->max_window = 0; 32895d424d5aSJohn Heffner tcp_mtup_init(sk); 32901da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 32911da177e4SLinus Torvalds 329281164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 329381164413SDaniel Borkmann 32941da177e4SLinus Torvalds if (!tp->window_clamp) 32951da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 32963541f9e8SEric Dumazet tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3297f5fff5dcSTom Quetchenbach 32981da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 32991da177e4SLinus Torvalds 3300e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3301e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3302e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3303e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3304e88c64f0SHagen Paul Pfeifer 330513d3b1ebSLawrence Brakmo rcv_wnd = tcp_rwnd_init_bpf(sk); 330613d3b1ebSLawrence Brakmo if (rcv_wnd == 0) 330713d3b1ebSLawrence Brakmo rcv_wnd = dst_metric(dst, RTAX_INITRWND); 330813d3b1ebSLawrence Brakmo 33091da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 33101da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 33111da177e4SLinus Torvalds &tp->rcv_wnd, 33121da177e4SLinus Torvalds &tp->window_clamp, 33139bb37ef0SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_window_scaling, 331431d12926Slaurent chavey &rcv_wscale, 331513d3b1ebSLawrence Brakmo rcv_wnd); 33161da177e4SLinus Torvalds 33171da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 33181da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 33191da177e4SLinus Torvalds 33201da177e4SLinus Torvalds sk->sk_err = 0; 33211da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 33221da177e4SLinus Torvalds tp->snd_wnd = 0; 3323ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 33241da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 33251da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 332633f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3327370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 3328ee995283SPavel Emelyanov 3329ee995283SPavel Emelyanov if (likely(!tp->repair)) 33301da177e4SLinus Torvalds tp->rcv_nxt = 0; 3331c7781a6eSAndrew Vagin else 333270eabf0eSEric Dumazet tp->rcv_tstamp = tcp_jiffies32; 3333ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 3334ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 33351da177e4SLinus Torvalds 33368550f328SLawrence Brakmo inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); 3337463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 33381da177e4SLinus Torvalds tcp_clear_retrans(tp); 33391da177e4SLinus Torvalds } 33401da177e4SLinus Torvalds 3341783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3342783237e8SYuchung Cheng { 3343783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3344783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3345783237e8SYuchung Cheng 3346783237e8SYuchung Cheng tcb->end_seq += skb->len; 3347f4a775d1SEric Dumazet __skb_header_release(skb); 3348783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 3349783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 3350783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 3351783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 3352783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3353783237e8SYuchung Cheng } 3354783237e8SYuchung Cheng 3355783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3356783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3357783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3358783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3359783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3360783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3361783237e8SYuchung Cheng */ 3362783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3363783237e8SYuchung Cheng { 3364783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3365783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 3366065263f4SWei Wang int space, err = 0; 3367355a901eSEric Dumazet struct sk_buff *syn_data; 3368783237e8SYuchung Cheng 336967da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3370065263f4SWei Wang if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) 3371783237e8SYuchung Cheng goto fallback; 3372783237e8SYuchung Cheng 3373783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3374783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3375783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3376783237e8SYuchung Cheng */ 33773541f9e8SEric Dumazet tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); 33783541f9e8SEric Dumazet 33791b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3380783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3381783237e8SYuchung Cheng 3382f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3383f5ddcbbbSEric Dumazet 3384f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3385f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3386f5ddcbbbSEric Dumazet 3387eb934478SEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); 3388355a901eSEric Dumazet if (!syn_data) 3389783237e8SYuchung Cheng goto fallback; 3390355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3391355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 339207e100f9SEric Dumazet if (space) { 339307e100f9SEric Dumazet int copied = copy_from_iter(skb_put(syn_data, space), space, 339457be5bdaSAl Viro &fo->data->msg_iter); 339557be5bdaSAl Viro if (unlikely(!copied)) { 3396355a901eSEric Dumazet kfree_skb(syn_data); 3397783237e8SYuchung Cheng goto fallback; 3398783237e8SYuchung Cheng } 339957be5bdaSAl Viro if (copied != space) { 340057be5bdaSAl Viro skb_trim(syn_data, copied); 340157be5bdaSAl Viro space = copied; 340257be5bdaSAl Viro } 340307e100f9SEric Dumazet } 3404355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3405355a901eSEric Dumazet if (space == fo->size) 3406355a901eSEric Dumazet fo->data = NULL; 3407355a901eSEric Dumazet fo->copied = space; 3408783237e8SYuchung Cheng 3409355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 34100f87230dSFrancis Yan if (syn_data->len) 34110f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3412355a901eSEric Dumazet 3413355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3414355a901eSEric Dumazet 3415355a901eSEric Dumazet syn->skb_mstamp = syn_data->skb_mstamp; 3416355a901eSEric Dumazet 3417355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3418355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3419355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3420355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3421431a9124SEric Dumazet */ 3422355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3423355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3424355a901eSEric Dumazet if (!err) { 342567da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 3426f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3427783237e8SYuchung Cheng goto done; 3428783237e8SYuchung Cheng } 3429783237e8SYuchung Cheng 3430783237e8SYuchung Cheng fallback: 3431783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3432783237e8SYuchung Cheng if (fo->cookie.len > 0) 3433783237e8SYuchung Cheng fo->cookie.len = 0; 3434783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3435783237e8SYuchung Cheng if (err) 3436783237e8SYuchung Cheng tp->syn_fastopen = 0; 3437783237e8SYuchung Cheng done: 3438783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3439783237e8SYuchung Cheng return err; 3440783237e8SYuchung Cheng } 3441783237e8SYuchung Cheng 344267edfef7SAndi Kleen /* Build a SYN and send it off. */ 34431da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 34441da177e4SLinus Torvalds { 34451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34461da177e4SLinus Torvalds struct sk_buff *buff; 3447ee586811SEric Paris int err; 34481da177e4SLinus Torvalds 34499872a4bdSLawrence Brakmo tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB); 34501da177e4SLinus Torvalds tcp_connect_init(sk); 34511da177e4SLinus Torvalds 34522b916477SAndrey Vagin if (unlikely(tp->repair)) { 34532b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 34542b916477SAndrey Vagin return 0; 34552b916477SAndrey Vagin } 34562b916477SAndrey Vagin 3457eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); 3458355a901eSEric Dumazet if (unlikely(!buff)) 34591da177e4SLinus Torvalds return -ENOBUFS; 34601da177e4SLinus Torvalds 3461a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 34629a568de4SEric Dumazet tcp_mstamp_refresh(tp); 34639a568de4SEric Dumazet tp->retrans_stamp = tcp_time_stamp(tp); 3464783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3465735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 34661da177e4SLinus Torvalds 3467783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3468783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3469783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3470ee586811SEric Paris if (err == -ECONNREFUSED) 3471ee586811SEric Paris return err; 3472bd37a088SWei Yongjun 3473bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3474bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3475bd37a088SWei Yongjun */ 3476bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3477bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 347881cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 34791da177e4SLinus Torvalds 34801da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 34813f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 34823f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 34831da177e4SLinus Torvalds return 0; 34841da177e4SLinus Torvalds } 34854bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 34861da177e4SLinus Torvalds 34871da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 34881da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 34891da177e4SLinus Torvalds * for details. 34901da177e4SLinus Torvalds */ 34911da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 34921da177e4SLinus Torvalds { 3493463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3494463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 34951da177e4SLinus Torvalds unsigned long timeout; 34961da177e4SLinus Torvalds 34979890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_DELAYED_ACK); 34989890092eSFlorian Westphal 34991da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3500463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 35011da177e4SLinus Torvalds int max_ato = HZ / 2; 35021da177e4SLinus Torvalds 3503056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3504056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 35051da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 35061da177e4SLinus Torvalds 35071da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 35081da177e4SLinus Torvalds 35091da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3510463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 35111da177e4SLinus Torvalds * directly. 35121da177e4SLinus Torvalds */ 3513740b0f18SEric Dumazet if (tp->srtt_us) { 3514740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3515740b0f18SEric Dumazet TCP_DELACK_MIN); 35161da177e4SLinus Torvalds 35171da177e4SLinus Torvalds if (rtt < max_ato) 35181da177e4SLinus Torvalds max_ato = rtt; 35191da177e4SLinus Torvalds } 35201da177e4SLinus Torvalds 35211da177e4SLinus Torvalds ato = min(ato, max_ato); 35221da177e4SLinus Torvalds } 35231da177e4SLinus Torvalds 35241da177e4SLinus Torvalds /* Stay within the limit we were given */ 35251da177e4SLinus Torvalds timeout = jiffies + ato; 35261da177e4SLinus Torvalds 35271da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3528463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 35291da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 35301da177e4SLinus Torvalds * send ACK now. 35311da177e4SLinus Torvalds */ 3532463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3533463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 35341da177e4SLinus Torvalds tcp_send_ack(sk); 35351da177e4SLinus Torvalds return; 35361da177e4SLinus Torvalds } 35371da177e4SLinus Torvalds 3538463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3539463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 35401da177e4SLinus Torvalds } 3541463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3542463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3543463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 35441da177e4SLinus Torvalds } 35451da177e4SLinus Torvalds 35461da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 35471da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 35481da177e4SLinus Torvalds { 35491da177e4SLinus Torvalds struct sk_buff *buff; 35501da177e4SLinus Torvalds 3551058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3552058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3553058dc334SIlpo Järvinen return; 3554058dc334SIlpo Järvinen 35559890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK); 35569890092eSFlorian Westphal 35571da177e4SLinus Torvalds /* We are not putting this on the write queue, so 35581da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 35591da177e4SLinus Torvalds * sock. 35601da177e4SLinus Torvalds */ 35617450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 35627450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 35637450aaf6SEric Dumazet if (unlikely(!buff)) { 3564463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3565463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 35663f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 35673f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 35681da177e4SLinus Torvalds return; 35691da177e4SLinus Torvalds } 35701da177e4SLinus Torvalds 35711da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 35721da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3573a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 35741da177e4SLinus Torvalds 357598781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 357698781965SEric Dumazet * too much. 357798781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 357898781965SEric Dumazet */ 357998781965SEric Dumazet skb_set_tcp_pure_ack(buff); 358098781965SEric Dumazet 35811da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 35827450aaf6SEric Dumazet tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0); 35831da177e4SLinus Torvalds } 3584e3118e83SDaniel Borkmann EXPORT_SYMBOL_GPL(tcp_send_ack); 35851da177e4SLinus Torvalds 35861da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 35871da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 35881da177e4SLinus Torvalds * 35891da177e4SLinus Torvalds * Question: what should we make while urgent mode? 35901da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 35911da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 35921da177e4SLinus Torvalds * 35931da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 35941da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 35951da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 35961da177e4SLinus Torvalds */ 3597e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 35981da177e4SLinus Torvalds { 35991da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 36001da177e4SLinus Torvalds struct sk_buff *skb; 36011da177e4SLinus Torvalds 36021da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 36037450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 36047450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 360551456b29SIan Morris if (!skb) 36061da177e4SLinus Torvalds return -1; 36071da177e4SLinus Torvalds 36081da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 36091da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 36101da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 36111da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 36121da177e4SLinus Torvalds * send it. 36131da177e4SLinus Torvalds */ 3614a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 3615e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 36167450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 36171da177e4SLinus Torvalds } 36181da177e4SLinus Torvalds 3619385e2070SEric Dumazet /* Called from setsockopt( ... TCP_REPAIR ) */ 3620ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3621ee995283SPavel Emelyanov { 3622ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3623ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 36249a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 3625e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 3626ee995283SPavel Emelyanov } 3627ee995283SPavel Emelyanov } 3628ee995283SPavel Emelyanov 362967edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 3630e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 36311da177e4SLinus Torvalds { 36321da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 36331da177e4SLinus Torvalds struct sk_buff *skb; 36341da177e4SLinus Torvalds 3635058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3636058dc334SIlpo Järvinen return -1; 3637058dc334SIlpo Järvinen 363800db4124SIan Morris skb = tcp_send_head(sk); 363900db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 36401da177e4SLinus Torvalds int err; 36410c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 364290840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 36431da177e4SLinus Torvalds 36441da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 36451da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 36461da177e4SLinus Torvalds 36471da177e4SLinus Torvalds /* We are probing the opening of a window 36481da177e4SLinus Torvalds * but the window size is != 0 36491da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 36501da177e4SLinus Torvalds */ 36511da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 36521da177e4SLinus Torvalds skb->len > mss) { 36531da177e4SLinus Torvalds seg_size = min(seg_size, mss); 36544de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 36556cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) 36561da177e4SLinus Torvalds return -1; 36571da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 36585bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 36591da177e4SLinus Torvalds 36604de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3661dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 366266f5fe62SIlpo Järvinen if (!err) 366366f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 36641da177e4SLinus Torvalds return err; 36651da177e4SLinus Torvalds } else { 366633f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 3667e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 3668e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 36691da177e4SLinus Torvalds } 36701da177e4SLinus Torvalds } 36711da177e4SLinus Torvalds 36721da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 36731da177e4SLinus Torvalds * a partial packet else a zero probe. 36741da177e4SLinus Torvalds */ 36751da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 36761da177e4SLinus Torvalds { 3677463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 36781da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3679c6214a97SNikolay Borisov struct net *net = sock_net(sk); 3680fcdd1cf4SEric Dumazet unsigned long probe_max; 36811da177e4SLinus Torvalds int err; 36821da177e4SLinus Torvalds 3683e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 36841da177e4SLinus Torvalds 3685fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 36861da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 36876687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3688463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 36891da177e4SLinus Torvalds return; 36901da177e4SLinus Torvalds } 36911da177e4SLinus Torvalds 36921da177e4SLinus Torvalds if (err <= 0) { 3693c6214a97SNikolay Borisov if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) 3694463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 36956687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3696fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 36971da177e4SLinus Torvalds } else { 36981da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 36996687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 37001da177e4SLinus Torvalds * Let local senders to fight for local resources. 37011da177e4SLinus Torvalds * 37021da177e4SLinus Torvalds * Use accumulated backoff yet. 37031da177e4SLinus Torvalds */ 37046687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 37056687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3706fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 37071da177e4SLinus Torvalds } 3708fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 370921c8fe99SEric Dumazet tcp_probe0_when(sk, probe_max), 3710fcdd1cf4SEric Dumazet TCP_RTO_MAX); 37111da177e4SLinus Torvalds } 37125db92c99SOctavian Purdila 3713ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 37145db92c99SOctavian Purdila { 37155db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 37165db92c99SOctavian Purdila struct flowi fl; 37175db92c99SOctavian Purdila int res; 37185db92c99SOctavian Purdila 371958d607d3SEric Dumazet tcp_rsk(req)->txhash = net_tx_rndhash(); 3720b3d05147SEric Dumazet res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); 37215db92c99SOctavian Purdila if (!res) { 372290bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 372302a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 37247e32b443SYuchung Cheng if (unlikely(tcp_passive_fastopen(sk))) 37257e32b443SYuchung Cheng tcp_sk(sk)->total_retrans++; 37265db92c99SOctavian Purdila } 37275db92c99SOctavian Purdila return res; 37285db92c99SOctavian Purdila } 37295db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3730