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 5346d3ceabSEric Dumazet /* Default TSQ limit of two TSO segments */ 5446d3ceabSEric Dumazet int sysctl_tcp_limit_output_bytes __read_mostly = 131072; 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 62ab32ea5dSBrian Haley int sysctl_tcp_mtu_probing __read_mostly = 0; 6397b1ce25SShan Wei int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS; 645d424d5aSJohn Heffner 6535089bb2SDavid S. Miller /* By default, RFC2861 behavior. */ 66ab32ea5dSBrian Haley int sysctl_tcp_slow_start_after_idle __read_mostly = 1; 6735089bb2SDavid S. Miller 68c9bee3b7SEric Dumazet unsigned int sysctl_tcp_notsent_lowat __read_mostly = UINT_MAX; 69c9bee3b7SEric Dumazet EXPORT_SYMBOL(sysctl_tcp_notsent_lowat); 70c9bee3b7SEric Dumazet 7146d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 7246d3ceabSEric Dumazet int push_one, gfp_t gfp); 73519855c5SWilliam Allen Simpson 7467edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 75cf533ea5SEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) 766ff03ac3SIlpo Järvinen { 776ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 786ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7966f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 809e412ba7SIlpo Järvinen 81fe067e8aSDavid S. Miller tcp_advance_send_head(sk, skb); 821da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 838512430eSIlpo Järvinen 8466f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 856ba8a3b1SNandita Dukkipati if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || 866a5dc9e5SEric Dumazet icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { 87750ea2baSYuchung Cheng tcp_rearm_rto(sk); 881da177e4SLinus Torvalds } 89f19c29e3SYuchung Cheng 90f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 91f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 926a5dc9e5SEric Dumazet } 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 951da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 961da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 971da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 981da177e4SLinus Torvalds * invalid. OK, let's make this for now: 991da177e4SLinus Torvalds */ 100cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 1011da177e4SLinus Torvalds { 102cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1039e412ba7SIlpo Järvinen 10490840defSIlpo Järvinen if (!before(tcp_wnd_end(tp), tp->snd_nxt)) 1051da177e4SLinus Torvalds return tp->snd_nxt; 1061da177e4SLinus Torvalds else 10790840defSIlpo Järvinen return tcp_wnd_end(tp); 1081da177e4SLinus Torvalds } 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1111da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1121da177e4SLinus Torvalds * 1131da177e4SLinus Torvalds * 1. It is independent of path mtu. 1141da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1151da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1161da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1171da177e4SLinus Torvalds * large MSS. 1181da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1191da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1201da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1211da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1221da177e4SLinus Torvalds * probably even Jumbo". 1231da177e4SLinus Torvalds */ 1241da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1251da177e4SLinus Torvalds { 1261da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 127cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1281da177e4SLinus Torvalds int mss = tp->advmss; 1291da177e4SLinus Torvalds 1300dbaee3bSDavid S. Miller if (dst) { 1310dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1320dbaee3bSDavid S. Miller 1330dbaee3bSDavid S. Miller if (metric < mss) { 1340dbaee3bSDavid S. Miller mss = metric; 1351da177e4SLinus Torvalds tp->advmss = mss; 1361da177e4SLinus Torvalds } 1370dbaee3bSDavid S. Miller } 1381da177e4SLinus Torvalds 1391da177e4SLinus Torvalds return (__u16)mss; 1401da177e4SLinus Torvalds } 1411da177e4SLinus Torvalds 1421da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1431da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 144cf533ea5SEric Dumazet static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst) 1451da177e4SLinus Torvalds { 146463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1471da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1481da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1491da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1501da177e4SLinus Torvalds 1516687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1521da177e4SLinus Torvalds 1536687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1541da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1551da177e4SLinus Torvalds 156463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1571da177e4SLinus Torvalds cwnd >>= 1; 1581da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1591da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1601da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1611da177e4SLinus Torvalds } 1621da177e4SLinus Torvalds 16367edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 16440efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 165cf533ea5SEric Dumazet struct sock *sk) 1661da177e4SLinus Torvalds { 167463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 168463c84b9SArnaldo Carvalho de Melo const u32 now = tcp_time_stamp; 169bcefe17cSCong Wang const struct dst_entry *dst = __sk_dst_get(sk); 1701da177e4SLinus Torvalds 17135089bb2SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 17235089bb2SDavid S. Miller (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) 173463c84b9SArnaldo Carvalho de Melo tcp_cwnd_restart(sk, __sk_dst_get(sk)); 1741da177e4SLinus Torvalds 1751da177e4SLinus Torvalds tp->lsndtime = now; 1761da177e4SLinus Torvalds 1771da177e4SLinus Torvalds /* If it is a reply for ato after last received 1781da177e4SLinus Torvalds * packet, enter pingpong mode. 1791da177e4SLinus Torvalds */ 180bcefe17cSCong Wang if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato && 181bcefe17cSCong Wang (!dst || !dst_metric(dst, RTAX_QUICKACK))) 182463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1831da177e4SLinus Torvalds } 1841da177e4SLinus Torvalds 18567edfef7SAndi Kleen /* Account for an ACK we sent. */ 18640efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1871da177e4SLinus Torvalds { 188463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 189463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1901da177e4SLinus Torvalds } 1911da177e4SLinus Torvalds 19285f16525SYuchung Cheng 19385f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 19485f16525SYuchung Cheng { 19585f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 1969ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 19785f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 19885f16525SYuchung Cheng * limit when mss is larger than 1460. 19985f16525SYuchung Cheng */ 20085f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 20185f16525SYuchung Cheng 20285f16525SYuchung Cheng if (mss > 1460) 20385f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 20485f16525SYuchung Cheng return init_rwnd; 20585f16525SYuchung Cheng } 20685f16525SYuchung Cheng 2071da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2081da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2091da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2101da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2111da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2121da177e4SLinus Torvalds * This MUST be enforced by all callers. 2131da177e4SLinus Torvalds */ 2141da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 2151da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 21631d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 21731d12926Slaurent chavey __u32 init_rcv_wnd) 2181da177e4SLinus Torvalds { 2191da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2221da177e4SLinus Torvalds if (*window_clamp == 0) 2231da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 2241da177e4SLinus Torvalds space = min(*window_clamp, space); 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2271da177e4SLinus Torvalds if (space > mss) 2281da177e4SLinus Torvalds space = (space / mss) * mss; 2291da177e4SLinus Torvalds 2301da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 23115d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 23215d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 23315d99e02SRick Jones * we will truncate our initial window offering to 32K-1 23415d99e02SRick Jones * unless the remote has sent us a window scaling option, 23515d99e02SRick Jones * which we interpret as a sign the remote TCP is not 23615d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2371da177e4SLinus Torvalds */ 23815d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2391da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 24015d99e02SRick Jones else 24115d99e02SRick Jones (*rcv_wnd) = space; 24215d99e02SRick Jones 2431da177e4SLinus Torvalds (*rcv_wscale) = 0; 2441da177e4SLinus Torvalds if (wscale_ok) { 2451da177e4SLinus Torvalds /* Set window scaling on max possible window 2461da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 2471da177e4SLinus Torvalds */ 2481da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 249316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 2501da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 2511da177e4SLinus Torvalds space >>= 1; 2521da177e4SLinus Torvalds (*rcv_wscale)++; 2531da177e4SLinus Torvalds } 2541da177e4SLinus Torvalds } 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 25785f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 25885f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 259b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 2621da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2631da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2641da177e4SLinus Torvalds } 2654bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2681da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2691da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2701da177e4SLinus Torvalds * frame. 2711da177e4SLinus Torvalds */ 27240efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2731da177e4SLinus Torvalds { 2741da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2758e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2761da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2771da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2781da177e4SLinus Torvalds 2791da177e4SLinus Torvalds /* Never shrink the offered window */ 2801da177e4SLinus Torvalds if (new_win < cur_win) { 2811da177e4SLinus Torvalds /* Danger Will Robinson! 2821da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2831da177e4SLinus Torvalds * we will not be able to advertise a zero 2841da177e4SLinus Torvalds * window in time. --DaveM 2851da177e4SLinus Torvalds * 2861da177e4SLinus Torvalds * Relax Will Robinson. 2871da177e4SLinus Torvalds */ 2888e165e20SFlorian Westphal if (new_win == 0) 2898e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2908e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 291607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2941da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2951da177e4SLinus Torvalds 2961da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2971da177e4SLinus Torvalds * scaled window. 2981da177e4SLinus Torvalds */ 29915d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 3001da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 3011da177e4SLinus Torvalds else 3021da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 3031da177e4SLinus Torvalds 3041da177e4SLinus Torvalds /* RFC1323 scaling applied */ 3051da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 3061da177e4SLinus Torvalds 3071da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 3088e165e20SFlorian Westphal if (new_win == 0) { 3091da177e4SLinus Torvalds tp->pred_flags = 0; 3108e165e20SFlorian Westphal if (old_win) 3118e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3128e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3138e165e20SFlorian Westphal } else if (old_win == 0) { 3148e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3158e165e20SFlorian Westphal } 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds return new_win; 3181da177e4SLinus Torvalds } 3191da177e4SLinus Torvalds 32067edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 321cf533ea5SEric Dumazet static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb) 322bdf1ee5dSIlpo Järvinen { 3234de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 324bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3254de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 326bdf1ee5dSIlpo Järvinen } 327bdf1ee5dSIlpo Järvinen 32867edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 329bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) 330bdf1ee5dSIlpo Järvinen { 331bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 332bdf1ee5dSIlpo Järvinen 333bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 3345d134f1cSHannes Frederic Sowa if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1) { 3354de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 336bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 337bdf1ee5dSIlpo Järvinen } 338bdf1ee5dSIlpo Järvinen } 339bdf1ee5dSIlpo Järvinen 340bdf1ee5dSIlpo Järvinen static __inline__ void 341cf533ea5SEric Dumazet TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th) 342bdf1ee5dSIlpo Järvinen { 343bdf1ee5dSIlpo Järvinen if (inet_rsk(req)->ecn_ok) 344bdf1ee5dSIlpo Järvinen th->ece = 1; 345bdf1ee5dSIlpo Järvinen } 346bdf1ee5dSIlpo Järvinen 34767edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 34867edfef7SAndi Kleen * be sent. 34967edfef7SAndi Kleen */ 350bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, 351bdf1ee5dSIlpo Järvinen int tcp_header_len) 352bdf1ee5dSIlpo Järvinen { 353bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 354bdf1ee5dSIlpo Järvinen 355bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 356bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 357bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 358bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 359bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 360bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 361bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 362bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->cwr = 1; 363bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 364bdf1ee5dSIlpo Järvinen } 365bdf1ee5dSIlpo Järvinen } else { 366bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 367bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 368bdf1ee5dSIlpo Järvinen } 369bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 370bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->ece = 1; 371bdf1ee5dSIlpo Järvinen } 372bdf1ee5dSIlpo Järvinen } 373bdf1ee5dSIlpo Järvinen 374e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 375e870a8efSIlpo Järvinen * auto increment end seqno. 376e870a8efSIlpo Järvinen */ 377e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 378e870a8efSIlpo Järvinen { 3797b7fc97aSEric Dumazet struct skb_shared_info *shinfo = skb_shinfo(skb); 3807b7fc97aSEric Dumazet 3812e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 382e870a8efSIlpo Järvinen skb->csum = 0; 383e870a8efSIlpo Järvinen 3844de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 385e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 386e870a8efSIlpo Järvinen 3877b7fc97aSEric Dumazet shinfo->gso_segs = 1; 3887b7fc97aSEric Dumazet shinfo->gso_size = 0; 3897b7fc97aSEric Dumazet shinfo->gso_type = 0; 390e870a8efSIlpo Järvinen 391e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 392a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 393e870a8efSIlpo Järvinen seq++; 394e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 395e870a8efSIlpo Järvinen } 396e870a8efSIlpo Järvinen 397a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 39833f5f57eSIlpo Järvinen { 39933f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 40033f5f57eSIlpo Järvinen } 40133f5f57eSIlpo Järvinen 40233ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 40333ad798cSAdam Langley #define OPTION_TS (1 << 1) 40433ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 40589e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4062100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 40733ad798cSAdam Langley 40833ad798cSAdam Langley struct tcp_out_options { 4092100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4102100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 41133ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 41233ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 413bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 414bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4152100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4162100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 41733ad798cSAdam Langley }; 41833ad798cSAdam Langley 41967edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 42067edfef7SAndi Kleen * 42167edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 422fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 423fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4248e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 425fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 426fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 427fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 428fd6149d3SIlpo Järvinen * 429fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 430fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 431fd6149d3SIlpo Järvinen */ 43233ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 433bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 434bd0388aeSWilliam Allen Simpson { 4352100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 436bd0388aeSWilliam Allen Simpson 437bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4381a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4391a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 440bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 441bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 44233ad798cSAdam Langley ptr += 4; 44333ad798cSAdam Langley } 44433ad798cSAdam Langley 445fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 446fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 447fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 448fd6149d3SIlpo Järvinen opts->mss); 449fd6149d3SIlpo Järvinen } 450fd6149d3SIlpo Järvinen 451bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 452bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 45333ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 45433ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 45533ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 45633ad798cSAdam Langley TCPOLEN_TIMESTAMP); 457bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 45833ad798cSAdam Langley } else { 459496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 46040efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 46140efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 46240efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 46340efc6faSStephen Hemminger } 46433ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 46533ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 46633ad798cSAdam Langley } 46733ad798cSAdam Langley 468bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 46933ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 47033ad798cSAdam Langley (TCPOPT_NOP << 16) | 47133ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 47233ad798cSAdam Langley TCPOLEN_SACK_PERM); 47333ad798cSAdam Langley } 47433ad798cSAdam Langley 475bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 47633ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 47733ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 47833ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 47933ad798cSAdam Langley opts->ws); 48033ad798cSAdam Langley } 48133ad798cSAdam Langley 48233ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 48333ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 48433ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 48540efc6faSStephen Hemminger int this_sack; 48640efc6faSStephen Hemminger 48740efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 48840efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 48940efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 49033ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 49140efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 4922de979bdSStephen Hemminger 49333ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 49433ad798cSAdam Langley ++this_sack) { 49540efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 49640efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 49740efc6faSStephen Hemminger } 4982de979bdSStephen Hemminger 49940efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 50040efc6faSStephen Hemminger } 5012100c8d2SYuchung Cheng 5022100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5032100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 5042100c8d2SYuchung Cheng 5052100c8d2SYuchung Cheng *ptr++ = htonl((TCPOPT_EXP << 24) | 5062100c8d2SYuchung Cheng ((TCPOLEN_EXP_FASTOPEN_BASE + foc->len) << 16) | 5072100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 5082100c8d2SYuchung Cheng 5092100c8d2SYuchung Cheng memcpy(ptr, foc->val, foc->len); 5102100c8d2SYuchung Cheng if ((foc->len & 3) == 2) { 5112100c8d2SYuchung Cheng u8 *align = ((u8 *)ptr) + foc->len; 5122100c8d2SYuchung Cheng align[0] = align[1] = TCPOPT_NOP; 5132100c8d2SYuchung Cheng } 5142100c8d2SYuchung Cheng ptr += (foc->len + 3) >> 2; 5152100c8d2SYuchung Cheng } 51640efc6faSStephen Hemminger } 51740efc6faSStephen Hemminger 51867edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 51967edfef7SAndi Kleen * network wire format yet. 52067edfef7SAndi Kleen */ 52195c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 52233ad798cSAdam Langley struct tcp_out_options *opts, 523cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 524cf533ea5SEric Dumazet { 52533ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 52695c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 527783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 52833ad798cSAdam Langley 529cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 53033ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 53133ad798cSAdam Langley if (*md5) { 53233ad798cSAdam Langley opts->options |= OPTION_MD5; 533bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 534cfb6eeb4SYOSHIFUJI Hideaki } 53533ad798cSAdam Langley #else 53633ad798cSAdam Langley *md5 = NULL; 537cfb6eeb4SYOSHIFUJI Hideaki #endif 53833ad798cSAdam Langley 53933ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 54033ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 54133ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 54233ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 54333ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 54433ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 54533ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 54633ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 54733ad798cSAdam Langley * going out. */ 54833ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 549bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 55033ad798cSAdam Langley 551bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { 55233ad798cSAdam Langley opts->options |= OPTION_TS; 5537faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 55433ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 555bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 55633ad798cSAdam Langley } 557bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_window_scaling)) { 55833ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 55989e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 560bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 56133ad798cSAdam Langley } 562bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_sack)) { 56333ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 564b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 565bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 56633ad798cSAdam Langley } 56733ad798cSAdam Langley 568783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 569783237e8SYuchung Cheng u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len; 570783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 571783237e8SYuchung Cheng if (remaining >= need) { 572783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 573783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 574783237e8SYuchung Cheng remaining -= need; 575783237e8SYuchung Cheng tp->syn_fastopen = 1; 576783237e8SYuchung Cheng } 577783237e8SYuchung Cheng } 578bd0388aeSWilliam Allen Simpson 579bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 58033ad798cSAdam Langley } 58133ad798cSAdam Langley 58267edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 58395c96174SEric Dumazet static unsigned int tcp_synack_options(struct sock *sk, 58433ad798cSAdam Langley struct request_sock *req, 58595c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 58633ad798cSAdam Langley struct tcp_out_options *opts, 5874957faadSWilliam Allen Simpson struct tcp_md5sig_key **md5, 5888336886fSJerry Chu struct tcp_fastopen_cookie *foc) 5894957faadSWilliam Allen Simpson { 59033ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 59195c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 59233ad798cSAdam Langley 59333ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 59433ad798cSAdam Langley *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); 59533ad798cSAdam Langley if (*md5) { 59633ad798cSAdam Langley opts->options |= OPTION_MD5; 5974957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 5984957faadSWilliam Allen Simpson 5994957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6004957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6014957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6024957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6034957faadSWilliam Allen Simpson */ 604de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 60533ad798cSAdam Langley } 60633ad798cSAdam Langley #else 60733ad798cSAdam Langley *md5 = NULL; 60833ad798cSAdam Langley #endif 60933ad798cSAdam Langley 6104957faadSWilliam Allen Simpson /* We always send an MSS option. */ 61133ad798cSAdam Langley opts->mss = mss; 6124957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 61333ad798cSAdam Langley 61433ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 61533ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 61689e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6174957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 61833ad798cSAdam Langley } 619de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 62033ad798cSAdam Langley opts->options |= OPTION_TS; 6217faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb); 62233ad798cSAdam Langley opts->tsecr = req->ts_recent; 6234957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 62433ad798cSAdam Langley } 62533ad798cSAdam Langley if (likely(ireq->sack_ok)) { 62633ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 627de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 6284957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 62933ad798cSAdam Langley } 63089278c9dSYuchung Cheng if (foc != NULL && foc->len >= 0) { 6318336886fSJerry Chu u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 6328336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 6338336886fSJerry Chu if (remaining >= need) { 6348336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 6358336886fSJerry Chu opts->fastopen_cookie = foc; 6368336886fSJerry Chu remaining -= need; 6378336886fSJerry Chu } 6388336886fSJerry Chu } 6394957faadSWilliam Allen Simpson 6404957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 64133ad798cSAdam Langley } 64233ad798cSAdam Langley 64367edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 64467edfef7SAndi Kleen * final wire format yet. 64567edfef7SAndi Kleen */ 64695c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 64733ad798cSAdam Langley struct tcp_out_options *opts, 648cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 649cf533ea5SEric Dumazet { 65033ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 65195c96174SEric Dumazet unsigned int size = 0; 652cabeccbdSIlpo Järvinen unsigned int eff_sacks; 65333ad798cSAdam Langley 6545843ef42SAndi Kleen opts->options = 0; 6555843ef42SAndi Kleen 65633ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 65733ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 65833ad798cSAdam Langley if (unlikely(*md5)) { 65933ad798cSAdam Langley opts->options |= OPTION_MD5; 66033ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 66133ad798cSAdam Langley } 66233ad798cSAdam Langley #else 66333ad798cSAdam Langley *md5 = NULL; 66433ad798cSAdam Langley #endif 66533ad798cSAdam Langley 66633ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 66733ad798cSAdam Langley opts->options |= OPTION_TS; 6687faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 66933ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 67033ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 67133ad798cSAdam Langley } 67233ad798cSAdam Langley 673cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 674cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 67595c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 67633ad798cSAdam Langley opts->num_sack_blocks = 67795c96174SEric Dumazet min_t(unsigned int, eff_sacks, 67833ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 67933ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 68033ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 68133ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 68233ad798cSAdam Langley } 68333ad798cSAdam Langley 68433ad798cSAdam Langley return size; 68540efc6faSStephen Hemminger } 6861da177e4SLinus Torvalds 68746d3ceabSEric Dumazet 68846d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 68946d3ceabSEric Dumazet * 69046d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 69146d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 69246d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 69346d3ceabSEric Dumazet * 69446d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 69546d3ceabSEric Dumazet * needs to be reallocated in a driver. 6968e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 69746d3ceabSEric Dumazet * 69846d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 69946d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 70046d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 70146d3ceabSEric Dumazet */ 70246d3ceabSEric Dumazet struct tsq_tasklet { 70346d3ceabSEric Dumazet struct tasklet_struct tasklet; 70446d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 70546d3ceabSEric Dumazet }; 70646d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 70746d3ceabSEric Dumazet 7086f458dfbSEric Dumazet static void tcp_tsq_handler(struct sock *sk) 7096f458dfbSEric Dumazet { 7106f458dfbSEric Dumazet if ((1 << sk->sk_state) & 7116f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 7126f458dfbSEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) 713bf06200eSJohn Ogness tcp_write_xmit(sk, tcp_current_mss(sk), tcp_sk(sk)->nonagle, 714bf06200eSJohn Ogness 0, GFP_ATOMIC); 7156f458dfbSEric Dumazet } 71646d3ceabSEric Dumazet /* 7178e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 71846d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 7198e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 72046d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 72146d3ceabSEric Dumazet */ 72246d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 72346d3ceabSEric Dumazet { 72446d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 72546d3ceabSEric Dumazet LIST_HEAD(list); 72646d3ceabSEric Dumazet unsigned long flags; 72746d3ceabSEric Dumazet struct list_head *q, *n; 72846d3ceabSEric Dumazet struct tcp_sock *tp; 72946d3ceabSEric Dumazet struct sock *sk; 73046d3ceabSEric Dumazet 73146d3ceabSEric Dumazet local_irq_save(flags); 73246d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 73346d3ceabSEric Dumazet local_irq_restore(flags); 73446d3ceabSEric Dumazet 73546d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 73646d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 73746d3ceabSEric Dumazet list_del(&tp->tsq_node); 73846d3ceabSEric Dumazet 73946d3ceabSEric Dumazet sk = (struct sock *)tp; 74046d3ceabSEric Dumazet bh_lock_sock(sk); 74146d3ceabSEric Dumazet 74246d3ceabSEric Dumazet if (!sock_owned_by_user(sk)) { 7436f458dfbSEric Dumazet tcp_tsq_handler(sk); 74446d3ceabSEric Dumazet } else { 74546d3ceabSEric Dumazet /* defer the work to tcp_release_cb() */ 7466f458dfbSEric Dumazet set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); 74746d3ceabSEric Dumazet } 74846d3ceabSEric Dumazet bh_unlock_sock(sk); 74946d3ceabSEric Dumazet 75046d3ceabSEric Dumazet clear_bit(TSQ_QUEUED, &tp->tsq_flags); 75146d3ceabSEric Dumazet sk_free(sk); 75246d3ceabSEric Dumazet } 75346d3ceabSEric Dumazet } 75446d3ceabSEric Dumazet 7556f458dfbSEric Dumazet #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ 7566f458dfbSEric Dumazet (1UL << TCP_WRITE_TIMER_DEFERRED) | \ 757563d34d0SEric Dumazet (1UL << TCP_DELACK_TIMER_DEFERRED) | \ 758563d34d0SEric Dumazet (1UL << TCP_MTU_REDUCED_DEFERRED)) 75946d3ceabSEric Dumazet /** 76046d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 76146d3ceabSEric Dumazet * @sk: socket 76246d3ceabSEric Dumazet * 76346d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 76446d3ceabSEric Dumazet * actions before socket release. 76546d3ceabSEric Dumazet */ 76646d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 76746d3ceabSEric Dumazet { 76846d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 7696f458dfbSEric Dumazet unsigned long flags, nflags; 77046d3ceabSEric Dumazet 7716f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 7726f458dfbSEric Dumazet do { 7736f458dfbSEric Dumazet flags = tp->tsq_flags; 7746f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 7756f458dfbSEric Dumazet return; 7766f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 7776f458dfbSEric Dumazet } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); 7786f458dfbSEric Dumazet 7796f458dfbSEric Dumazet if (flags & (1UL << TCP_TSQ_DEFERRED)) 7806f458dfbSEric Dumazet tcp_tsq_handler(sk); 7816f458dfbSEric Dumazet 782c3f9b018SEric Dumazet /* Here begins the tricky part : 783c3f9b018SEric Dumazet * We are called from release_sock() with : 784c3f9b018SEric Dumazet * 1) BH disabled 785c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 786c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 787c3f9b018SEric Dumazet * 788c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 789c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 790c3f9b018SEric Dumazet */ 791c3f9b018SEric Dumazet sock_release_ownership(sk); 792c3f9b018SEric Dumazet 793144d56e9SEric Dumazet if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { 7946f458dfbSEric Dumazet tcp_write_timer_handler(sk); 795144d56e9SEric Dumazet __sock_put(sk); 796144d56e9SEric Dumazet } 797144d56e9SEric Dumazet if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { 7986f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 799144d56e9SEric Dumazet __sock_put(sk); 800144d56e9SEric Dumazet } 801144d56e9SEric Dumazet if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { 8024fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 803144d56e9SEric Dumazet __sock_put(sk); 804144d56e9SEric Dumazet } 80546d3ceabSEric Dumazet } 80646d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 80746d3ceabSEric Dumazet 80846d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 80946d3ceabSEric Dumazet { 81046d3ceabSEric Dumazet int i; 81146d3ceabSEric Dumazet 81246d3ceabSEric Dumazet for_each_possible_cpu(i) { 81346d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 81446d3ceabSEric Dumazet 81546d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 81646d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 81746d3ceabSEric Dumazet tcp_tasklet_func, 81846d3ceabSEric Dumazet (unsigned long)tsq); 81946d3ceabSEric Dumazet } 82046d3ceabSEric Dumazet } 82146d3ceabSEric Dumazet 82246d3ceabSEric Dumazet /* 82346d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 8248e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 82546d3ceabSEric Dumazet * hold qdisc lock. 82646d3ceabSEric Dumazet */ 827d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 82846d3ceabSEric Dumazet { 82946d3ceabSEric Dumazet struct sock *sk = skb->sk; 83046d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 83146d3ceabSEric Dumazet 83246d3ceabSEric Dumazet if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && 83346d3ceabSEric Dumazet !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { 83446d3ceabSEric Dumazet unsigned long flags; 83546d3ceabSEric Dumazet struct tsq_tasklet *tsq; 83646d3ceabSEric Dumazet 83746d3ceabSEric Dumazet /* Keep a ref on socket. 83846d3ceabSEric Dumazet * This last ref will be released in tcp_tasklet_func() 83946d3ceabSEric Dumazet */ 84046d3ceabSEric Dumazet atomic_sub(skb->truesize - 1, &sk->sk_wmem_alloc); 84146d3ceabSEric Dumazet 84246d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 84346d3ceabSEric Dumazet local_irq_save(flags); 84446d3ceabSEric Dumazet tsq = &__get_cpu_var(tsq_tasklet); 84546d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 84646d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 84746d3ceabSEric Dumazet local_irq_restore(flags); 84846d3ceabSEric Dumazet } else { 84946d3ceabSEric Dumazet sock_wfree(skb); 85046d3ceabSEric Dumazet } 85146d3ceabSEric Dumazet } 85246d3ceabSEric Dumazet 8531da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 8541da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 8551da177e4SLinus Torvalds * transmission and possible later retransmissions. 8561da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 8571da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 8581da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 8591da177e4SLinus Torvalds * device. 8601da177e4SLinus Torvalds * 8611da177e4SLinus Torvalds * We are working here with either a clone of the original 8621da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 8631da177e4SLinus Torvalds */ 864056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 865056834d9SIlpo Järvinen gfp_t gfp_mask) 8661da177e4SLinus Torvalds { 8676687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 868dfb4b9dcSDavid S. Miller struct inet_sock *inet; 869dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 870dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 87133ad798cSAdam Langley struct tcp_out_options opts; 87295c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 873cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 8741da177e4SLinus Torvalds struct tcphdr *th; 8751da177e4SLinus Torvalds int err; 8761da177e4SLinus Torvalds 877dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 878dfb4b9dcSDavid S. Miller 879ccdbb6e9SEric Dumazet if (clone_it) { 880740b0f18SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 881dfb4b9dcSDavid S. Miller 882dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 883dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 884dfb4b9dcSDavid S. Miller else 885dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 886dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 887dfb4b9dcSDavid S. Miller return -ENOBUFS; 888dfb4b9dcSDavid S. Miller } 889dfb4b9dcSDavid S. Miller 890dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 891dfb4b9dcSDavid S. Miller tp = tcp_sk(sk); 892dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 89333ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 8941da177e4SLinus Torvalds 8954de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 89633ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 89733ad798cSAdam Langley else 89833ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 89933ad798cSAdam Langley &md5); 90033ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 9011da177e4SLinus Torvalds 902547669d4SEric Dumazet if (tcp_packets_in_flight(tp) == 0) 9036687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_TX_START); 904547669d4SEric Dumazet 905547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 906547669d4SEric Dumazet * another queue. 907547669d4SEric Dumazet */ 908547669d4SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) == 0; 9091da177e4SLinus Torvalds 910aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 911aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 91246d3ceabSEric Dumazet 91346d3ceabSEric Dumazet skb_orphan(skb); 91446d3ceabSEric Dumazet skb->sk = sk; 915c9eeec26SEric Dumazet skb->destructor = tcp_wfree; 916b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 91746d3ceabSEric Dumazet atomic_add(skb->truesize, &sk->sk_wmem_alloc); 9181da177e4SLinus Torvalds 9191da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 920aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 921c720c7e8SEric Dumazet th->source = inet->inet_sport; 922c720c7e8SEric Dumazet th->dest = inet->inet_dport; 9231da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 9241da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 925df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 9264de075e0SEric Dumazet tcb->tcp_flags); 927dfb4b9dcSDavid S. Miller 9284de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 9291da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 9301da177e4SLinus Torvalds * is never scaled. 9311da177e4SLinus Torvalds */ 932600ff0c2SIlpo Järvinen th->window = htons(min(tp->rcv_wnd, 65535U)); 9331da177e4SLinus Torvalds } else { 9341da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 9351da177e4SLinus Torvalds } 9361da177e4SLinus Torvalds th->check = 0; 9371da177e4SLinus Torvalds th->urg_ptr = 0; 9381da177e4SLinus Torvalds 93933f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 9407691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 9417691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 9421da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 9431da177e4SLinus Torvalds th->urg = 1; 9447691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 9450eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 9467691367dSHerbert Xu th->urg = 1; 9477691367dSHerbert Xu } 9481da177e4SLinus Torvalds } 9491da177e4SLinus Torvalds 950bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 9514de075e0SEric Dumazet if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) 9529e412ba7SIlpo Järvinen TCP_ECN_send(sk, skb, tcp_header_size); 953dfb4b9dcSDavid S. Miller 954cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 955cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 956cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 957a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 958bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 95949a72dfbSAdam Langley md5, sk, NULL, skb); 960cfb6eeb4SYOSHIFUJI Hideaki } 961cfb6eeb4SYOSHIFUJI Hideaki #endif 962cfb6eeb4SYOSHIFUJI Hideaki 963bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 9641da177e4SLinus Torvalds 9654de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 966fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 9671da177e4SLinus Torvalds 9681da177e4SLinus Torvalds if (skb->len != tcp_header_size) 969cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 9701da177e4SLinus Torvalds 971bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 972aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 973aa2ea058STom Herbert tcp_skb_pcount(skb)); 9741da177e4SLinus Torvalds 9757faee5c0SEric Dumazet /* Our usage of tstamp should remain private */ 9767faee5c0SEric Dumazet skb->tstamp.tv64 = 0; 977*971f10ecSEric Dumazet 978*971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 979*971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 980*971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 981*971f10ecSEric Dumazet 982b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 9837faee5c0SEric Dumazet 98483de47cdSHua Zhong if (likely(err <= 0)) 9851da177e4SLinus Torvalds return err; 9861da177e4SLinus Torvalds 9875ee2c941SChristoph Paasch tcp_enter_cwr(sk); 9881da177e4SLinus Torvalds 989b9df3cb8SGerrit Renker return net_xmit_eval(err); 9901da177e4SLinus Torvalds } 9911da177e4SLinus Torvalds 99267edfef7SAndi Kleen /* This routine just queues the buffer for sending. 9931da177e4SLinus Torvalds * 9941da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 9951da177e4SLinus Torvalds * otherwise socket can stall. 9961da177e4SLinus Torvalds */ 9971da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 9981da177e4SLinus Torvalds { 9991da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10001da177e4SLinus Torvalds 10011da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 10021da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1003f4a775d1SEric Dumazet __skb_header_release(skb); 1004fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 10053ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 10063ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 10071da177e4SLinus Torvalds } 10081da177e4SLinus Torvalds 100967edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 1010cf533ea5SEric Dumazet static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, 1011056834d9SIlpo Järvinen unsigned int mss_now) 1012f6302d1dSDavid S. Miller { 10137b7fc97aSEric Dumazet struct skb_shared_info *shinfo = skb_shinfo(skb); 10147b7fc97aSEric Dumazet 1015c52e2421SEric Dumazet /* Make sure we own this skb before messing gso_size/gso_segs */ 1016c52e2421SEric Dumazet WARN_ON_ONCE(skb_cloned(skb)); 1017c52e2421SEric Dumazet 10188f26fb1cSEric Dumazet if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { 1019f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1020f6302d1dSDavid S. Miller * non-TSO case. 1021f6302d1dSDavid S. Miller */ 10227b7fc97aSEric Dumazet shinfo->gso_segs = 1; 10237b7fc97aSEric Dumazet shinfo->gso_size = 0; 10247b7fc97aSEric Dumazet shinfo->gso_type = 0; 1025f6302d1dSDavid S. Miller } else { 10267b7fc97aSEric Dumazet shinfo->gso_segs = DIV_ROUND_UP(skb->len, mss_now); 10277b7fc97aSEric Dumazet shinfo->gso_size = mss_now; 10287b7fc97aSEric Dumazet shinfo->gso_type = sk->sk_gso_type; 10291da177e4SLinus Torvalds } 10301da177e4SLinus Torvalds } 10311da177e4SLinus Torvalds 103291fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 103368f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 103491fed7a1SIlpo Järvinen */ 1035cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 103691fed7a1SIlpo Järvinen int decr) 103791fed7a1SIlpo Järvinen { 1038a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1039a47e5a98SIlpo Järvinen 1040dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 104191fed7a1SIlpo Järvinen return; 104291fed7a1SIlpo Järvinen 10436859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 104491fed7a1SIlpo Järvinen tp->fackets_out -= decr; 104591fed7a1SIlpo Järvinen } 104691fed7a1SIlpo Järvinen 1047797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1048797108d1SIlpo Järvinen * tweaks to fix counters 1049797108d1SIlpo Järvinen */ 1050cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1051797108d1SIlpo Järvinen { 1052797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1053797108d1SIlpo Järvinen 1054797108d1SIlpo Järvinen tp->packets_out -= decr; 1055797108d1SIlpo Järvinen 1056797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1057797108d1SIlpo Järvinen tp->sacked_out -= decr; 1058797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1059797108d1SIlpo Järvinen tp->retrans_out -= decr; 1060797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1061797108d1SIlpo Järvinen tp->lost_out -= decr; 1062797108d1SIlpo Järvinen 1063797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1064797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1065797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1066797108d1SIlpo Järvinen 1067797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1068797108d1SIlpo Järvinen 1069797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1070797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 107152cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1072797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1073797108d1SIlpo Järvinen 1074797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1075797108d1SIlpo Järvinen } 1076797108d1SIlpo Järvinen 1077490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1078490cc7d0SWillem de Bruijn { 1079490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1080490cc7d0SWillem de Bruijn 1081490cc7d0SWillem de Bruijn if (unlikely(shinfo->tx_flags & SKBTX_ANY_TSTAMP) && 1082490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1083490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1084490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1085490cc7d0SWillem de Bruijn 1086490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1087490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1088490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1089490cc7d0SWillem de Bruijn } 1090490cc7d0SWillem de Bruijn } 1091490cc7d0SWillem de Bruijn 10921da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 10931da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 10941da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 10951da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 10961da177e4SLinus Torvalds */ 1097056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 10986cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 10991da177e4SLinus Torvalds { 11001da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11011da177e4SLinus Torvalds struct sk_buff *buff; 11026475be16SDavid S. Miller int nsize, old_factor; 1103b60b49eaSHerbert Xu int nlen; 11049ce01461SIlpo Järvinen u8 flags; 11051da177e4SLinus Torvalds 11062fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 11072fceec13SIlpo Järvinen return -EINVAL; 11086a438bbeSStephen Hemminger 11091da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 11101da177e4SLinus Torvalds if (nsize < 0) 11111da177e4SLinus Torvalds nsize = 0; 11121da177e4SLinus Torvalds 11136cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 11141da177e4SLinus Torvalds return -ENOMEM; 11151da177e4SLinus Torvalds 11161da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 11176cc55e09SOctavian Purdila buff = sk_stream_alloc_skb(sk, nsize, gfp); 11181da177e4SLinus Torvalds if (buff == NULL) 11191da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1120ef5cb973SHerbert Xu 11213ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 11223ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1123b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1124b60b49eaSHerbert Xu buff->truesize += nlen; 1125b60b49eaSHerbert Xu skb->truesize -= nlen; 11261da177e4SLinus Torvalds 11271da177e4SLinus Torvalds /* Correct the sequence numbers. */ 11281da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 11291da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 11301da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 11311da177e4SLinus Torvalds 11321da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 11334de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 11344de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 11354de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1136e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 11371da177e4SLinus Torvalds 113884fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 11391da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1140056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1141056834d9SIlpo Järvinen skb_put(buff, nsize), 11421da177e4SLinus Torvalds nsize, 0); 11431da177e4SLinus Torvalds 11441da177e4SLinus Torvalds skb_trim(skb, len); 11451da177e4SLinus Torvalds 11461da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 11471da177e4SLinus Torvalds } else { 114884fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 11491da177e4SLinus Torvalds skb_split(skb, buff, len); 11501da177e4SLinus Torvalds } 11511da177e4SLinus Torvalds 11521da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 11531da177e4SLinus Torvalds 1154a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1155490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 11561da177e4SLinus Torvalds 11576475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 11586475be16SDavid S. Miller 11591da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 1160846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1161846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 11621da177e4SLinus Torvalds 11636475be16SDavid S. Miller /* If this packet has been sent out already, we must 11646475be16SDavid S. Miller * adjust the various packet counters. 11656475be16SDavid S. Miller */ 1166cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 11676475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 11686475be16SDavid S. Miller tcp_skb_pcount(buff); 11691da177e4SLinus Torvalds 1170797108d1SIlpo Järvinen if (diff) 1171797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 11721da177e4SLinus Torvalds } 11731da177e4SLinus Torvalds 11741da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1175f4a775d1SEric Dumazet __skb_header_release(buff); 1176fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 11771da177e4SLinus Torvalds 11781da177e4SLinus Torvalds return 0; 11791da177e4SLinus Torvalds } 11801da177e4SLinus Torvalds 11811da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 11821da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 11831da177e4SLinus Torvalds * immediately discarded. 11841da177e4SLinus Torvalds */ 1185f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 11861da177e4SLinus Torvalds { 11877b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 11881da177e4SLinus Torvalds int i, k, eat; 11891da177e4SLinus Torvalds 11904fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 11914fa48bf3SEric Dumazet if (eat) { 11924fa48bf3SEric Dumazet __skb_pull(skb, eat); 11934fa48bf3SEric Dumazet len -= eat; 11944fa48bf3SEric Dumazet if (!len) 11954fa48bf3SEric Dumazet return; 11964fa48bf3SEric Dumazet } 11971da177e4SLinus Torvalds eat = len; 11981da177e4SLinus Torvalds k = 0; 11997b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 12007b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 12017b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 12029e903e08SEric Dumazet 12039e903e08SEric Dumazet if (size <= eat) { 1204aff65da0SIan Campbell skb_frag_unref(skb, i); 12059e903e08SEric Dumazet eat -= size; 12061da177e4SLinus Torvalds } else { 12077b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 12081da177e4SLinus Torvalds if (eat) { 12097b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 12107b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 12111da177e4SLinus Torvalds eat = 0; 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds k++; 12141da177e4SLinus Torvalds } 12151da177e4SLinus Torvalds } 12167b7fc97aSEric Dumazet shinfo->nr_frags = k; 12171da177e4SLinus Torvalds 121827a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 12191da177e4SLinus Torvalds skb->data_len -= len; 12201da177e4SLinus Torvalds skb->len = skb->data_len; 12211da177e4SLinus Torvalds } 12221da177e4SLinus Torvalds 122367edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 12241da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 12251da177e4SLinus Torvalds { 122614bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 12271da177e4SLinus Torvalds return -ENOMEM; 12281da177e4SLinus Torvalds 12294fa48bf3SEric Dumazet __pskb_trim_head(skb, len); 12301da177e4SLinus Torvalds 12311da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 123284fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 12331da177e4SLinus Torvalds 12341da177e4SLinus Torvalds skb->truesize -= len; 12351da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 12363ab224beSHideo Aoki sk_mem_uncharge(sk, len); 12371da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 12381da177e4SLinus Torvalds 12395b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 12401da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 12415b35e1e6SNeal Cardwell tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds return 0; 12441da177e4SLinus Torvalds } 12451da177e4SLinus Torvalds 12461b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 12471b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 12485d424d5aSJohn Heffner { 1249cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1250cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 12515d424d5aSJohn Heffner int mss_now; 12525d424d5aSJohn Heffner 12535d424d5aSJohn Heffner /* Calculate base mss without TCP options: 12545d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 12555d424d5aSJohn Heffner */ 12565d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 12575d424d5aSJohn Heffner 125867469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 125967469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 126067469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 126167469601SEric Dumazet 126267469601SEric Dumazet if (dst && dst_allfrag(dst)) 126367469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 126467469601SEric Dumazet } 126567469601SEric Dumazet 12665d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 12675d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 12685d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 12695d424d5aSJohn Heffner 12705d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 12715d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 12725d424d5aSJohn Heffner 12735d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 12745d424d5aSJohn Heffner if (mss_now < 48) 12755d424d5aSJohn Heffner mss_now = 48; 12765d424d5aSJohn Heffner return mss_now; 12775d424d5aSJohn Heffner } 12785d424d5aSJohn Heffner 12791b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 12801b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 12811b63edd6SYuchung Cheng { 12821b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 12831b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 12841b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 12851b63edd6SYuchung Cheng } 12861b63edd6SYuchung Cheng 12875d424d5aSJohn Heffner /* Inverse of above */ 128867469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 12895d424d5aSJohn Heffner { 1290cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1291cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 12925d424d5aSJohn Heffner int mtu; 12935d424d5aSJohn Heffner 12945d424d5aSJohn Heffner mtu = mss + 12955d424d5aSJohn Heffner tp->tcp_header_len + 12965d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 12975d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 12985d424d5aSJohn Heffner 129967469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 130067469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 130167469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 130267469601SEric Dumazet 130367469601SEric Dumazet if (dst && dst_allfrag(dst)) 130467469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 130567469601SEric Dumazet } 13065d424d5aSJohn Heffner return mtu; 13075d424d5aSJohn Heffner } 13085d424d5aSJohn Heffner 130967edfef7SAndi Kleen /* MTU probing init per socket */ 13105d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 13115d424d5aSJohn Heffner { 13125d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 13135d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 13145d424d5aSJohn Heffner 13155d424d5aSJohn Heffner icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; 13165d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 13175d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 13185d424d5aSJohn Heffner icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); 13195d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 13205d424d5aSJohn Heffner } 13214bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 13225d424d5aSJohn Heffner 13231da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 13261da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 13271da177e4SLinus Torvalds 13281da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1329caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 13301da177e4SLinus Torvalds It also does not include TCP options. 13311da177e4SLinus Torvalds 1332d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 13351da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 13361da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 13371da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 13381da177e4SLinus Torvalds 13391da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 13401da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 13411da177e4SLinus Torvalds 1342d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1343d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 13441da177e4SLinus Torvalds */ 13451da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 13461da177e4SLinus Torvalds { 13471da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1348d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 13495d424d5aSJohn Heffner int mss_now; 13501da177e4SLinus Torvalds 13515d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 13525d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 13531da177e4SLinus Torvalds 13545d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1355409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 13561da177e4SLinus Torvalds 13571da177e4SLinus Torvalds /* And store cached results */ 1358d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 13595d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 13605d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1361c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 13621da177e4SLinus Torvalds 13631da177e4SLinus Torvalds return mss_now; 13641da177e4SLinus Torvalds } 13654bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 13681da177e4SLinus Torvalds * and even PMTU discovery events into account. 13691da177e4SLinus Torvalds */ 13700c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 13711da177e4SLinus Torvalds { 1372cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1373cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1374c1b4a7e6SDavid S. Miller u32 mss_now; 137595c96174SEric Dumazet unsigned int header_len; 137633ad798cSAdam Langley struct tcp_out_options opts; 137733ad798cSAdam Langley struct tcp_md5sig_key *md5; 13781da177e4SLinus Torvalds 1379c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1380c1b4a7e6SDavid S. Miller 13811da177e4SLinus Torvalds if (dst) { 13821da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1383d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 13841da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 13851da177e4SLinus Torvalds } 13861da177e4SLinus Torvalds 138733ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 138833ad798cSAdam Langley sizeof(struct tcphdr); 138933ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 139033ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 139133ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 139233ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 139333ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 139433ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 139533ad798cSAdam Langley mss_now -= delta; 139633ad798cSAdam Langley } 1397cfb6eeb4SYOSHIFUJI Hideaki 13981da177e4SLinus Torvalds return mss_now; 13991da177e4SLinus Torvalds } 14001da177e4SLinus Torvalds 140186fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 140286fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 140386fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 140486fd14adSWeiping Pan */ 140586fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1406a762a980SDavid S. Miller { 14079e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1408a762a980SDavid S. Miller 140986fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 141086fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 141186fd14adSWeiping Pan /* Limited by application or receiver window. */ 141286fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 141386fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 141486fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 141586fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 141686fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 141786fd14adSWeiping Pan } 141886fd14adSWeiping Pan tp->snd_cwnd_used = 0; 141986fd14adSWeiping Pan } 142086fd14adSWeiping Pan tp->snd_cwnd_stamp = tcp_time_stamp; 142186fd14adSWeiping Pan } 142286fd14adSWeiping Pan 1423ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1424a762a980SDavid S. Miller { 1425a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1426a762a980SDavid S. Miller 1427ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1428ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1429ca8a2263SNeal Cardwell */ 1430ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1431ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1432ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1433ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1434ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1435ca8a2263SNeal Cardwell } 1436e114a710SEric Dumazet 143724901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1438a762a980SDavid S. Miller /* Network is feed fully. */ 1439a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1440a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1441a762a980SDavid S. Miller } else { 1442a762a980SDavid S. Miller /* Network starves. */ 1443a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1444a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1445a762a980SDavid S. Miller 144615d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 144715d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1448a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1449a762a980SDavid S. Miller } 1450a762a980SDavid S. Miller } 1451a762a980SDavid S. Miller 1452d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1453d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1454d4589926SEric Dumazet { 1455d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1456d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1457d4589926SEric Dumazet } 1458d4589926SEric Dumazet 1459d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1460d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1461d4589926SEric Dumazet * The test is really : 1462d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1463d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1464d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1465d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 14660e3a4803SIlpo Järvinen */ 1467d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1468d4589926SEric Dumazet const struct sk_buff *skb) 1469d4589926SEric Dumazet { 1470d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1471d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1472d4589926SEric Dumazet } 1473d4589926SEric Dumazet 1474d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1475d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1476d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1477d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1478d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1479d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1480d4589926SEric Dumazet */ 1481d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1482cc93fc51SPeter Pan(潘卫平) int nonagle) 1483d4589926SEric Dumazet { 1484d4589926SEric Dumazet return partial && 1485d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1486d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1487d4589926SEric Dumazet } 1488d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1489d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1490d4589926SEric Dumazet const struct sk_buff *skb, 1491d4589926SEric Dumazet unsigned int mss_now, 1492d4589926SEric Dumazet unsigned int max_segs, 1493d4589926SEric Dumazet int nonagle) 1494c1b4a7e6SDavid S. Miller { 1495cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1496d4589926SEric Dumazet u32 partial, needed, window, max_len; 1497c1b4a7e6SDavid S. Miller 149890840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 14991485348dSBen Hutchings max_len = mss_now * max_segs; 15000e3a4803SIlpo Järvinen 15011485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 15021485348dSBen Hutchings return max_len; 15030e3a4803SIlpo Järvinen 15045ea3a748SIlpo Järvinen needed = min(skb->len, window); 15055ea3a748SIlpo Järvinen 15061485348dSBen Hutchings if (max_len <= needed) 15071485348dSBen Hutchings return max_len; 15080e3a4803SIlpo Järvinen 1509d4589926SEric Dumazet partial = needed % mss_now; 1510d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1511d4589926SEric Dumazet * to include this last segment in this skb. 1512d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1513d4589926SEric Dumazet */ 1514cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1515d4589926SEric Dumazet return needed - partial; 1516d4589926SEric Dumazet 1517d4589926SEric Dumazet return needed; 1518c1b4a7e6SDavid S. Miller } 1519c1b4a7e6SDavid S. Miller 1520c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1521c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1522c1b4a7e6SDavid S. Miller */ 1523cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1524cf533ea5SEric Dumazet const struct sk_buff *skb) 1525c1b4a7e6SDavid S. Miller { 1526c1b4a7e6SDavid S. Miller u32 in_flight, cwnd; 1527c1b4a7e6SDavid S. Miller 1528c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 15294de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 15304de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1531c1b4a7e6SDavid S. Miller return 1; 1532c1b4a7e6SDavid S. Miller 1533c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1534c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1535c1b4a7e6SDavid S. Miller if (in_flight < cwnd) 1536c1b4a7e6SDavid S. Miller return (cwnd - in_flight); 1537c1b4a7e6SDavid S. Miller 1538c1b4a7e6SDavid S. Miller return 0; 1539c1b4a7e6SDavid S. Miller } 1540c1b4a7e6SDavid S. Miller 1541b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 154267edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1543c1b4a7e6SDavid S. Miller * SKB onto the wire. 1544c1b4a7e6SDavid S. Miller */ 1545cf533ea5SEric Dumazet static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, 1546056834d9SIlpo Järvinen unsigned int mss_now) 1547c1b4a7e6SDavid S. Miller { 1548c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1549c1b4a7e6SDavid S. Miller 1550f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 1551846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1552c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1553c1b4a7e6SDavid S. Miller } 1554c1b4a7e6SDavid S. Miller return tso_segs; 1555c1b4a7e6SDavid S. Miller } 1556c1b4a7e6SDavid S. Miller 1557c1b4a7e6SDavid S. Miller 1558a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1559c1b4a7e6SDavid S. Miller * sent now. 1560c1b4a7e6SDavid S. Miller */ 1561a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1562c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1563c1b4a7e6SDavid S. Miller { 1564c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1565c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1566c1b4a7e6SDavid S. Miller * 1567c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1568c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1569c1b4a7e6SDavid S. Miller */ 1570c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1571a2a385d6SEric Dumazet return true; 1572c1b4a7e6SDavid S. Miller 15739b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 15749b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1575a2a385d6SEric Dumazet return true; 1576c1b4a7e6SDavid S. Miller 1577cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1578a2a385d6SEric Dumazet return true; 1579c1b4a7e6SDavid S. Miller 1580a2a385d6SEric Dumazet return false; 1581c1b4a7e6SDavid S. Miller } 1582c1b4a7e6SDavid S. Miller 1583c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1584a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1585a2a385d6SEric Dumazet const struct sk_buff *skb, 1586056834d9SIlpo Järvinen unsigned int cur_mss) 1587c1b4a7e6SDavid S. Miller { 1588c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1589c1b4a7e6SDavid S. Miller 1590c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1591c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1592c1b4a7e6SDavid S. Miller 159390840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1594c1b4a7e6SDavid S. Miller } 1595c1b4a7e6SDavid S. Miller 1596fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1597c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1598c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1599c1b4a7e6SDavid S. Miller */ 1600cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1601c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1602c1b4a7e6SDavid S. Miller { 1603cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1604c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1605c1b4a7e6SDavid S. Miller 1606846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 1607c1b4a7e6SDavid S. Miller 1608c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1609c1b4a7e6SDavid S. Miller return 0; 1610c1b4a7e6SDavid S. Miller 1611c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1612056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1613c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1614c1b4a7e6SDavid S. Miller 1615c1b4a7e6SDavid S. Miller return cwnd_quota; 1616c1b4a7e6SDavid S. Miller } 1617c1b4a7e6SDavid S. Miller 161867edfef7SAndi Kleen /* Test if sending is allowed right now. */ 1619a2a385d6SEric Dumazet bool tcp_may_send_now(struct sock *sk) 1620c1b4a7e6SDavid S. Miller { 1621cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1622fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1623c1b4a7e6SDavid S. Miller 1624a02cec21SEric Dumazet return skb && 16250c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1626c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1627a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1628c1b4a7e6SDavid S. Miller } 1629c1b4a7e6SDavid S. Miller 1630c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1631c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1632c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1633c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1634c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1635c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1636c1b4a7e6SDavid S. Miller */ 1637056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1638c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1639c1b4a7e6SDavid S. Miller { 1640c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1641c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 16429ce01461SIlpo Järvinen u8 flags; 1643c1b4a7e6SDavid S. Miller 1644c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1645c8ac3774SHerbert Xu if (skb->len != skb->data_len) 16466cc55e09SOctavian Purdila return tcp_fragment(sk, skb, len, mss_now, gfp); 1647c1b4a7e6SDavid S. Miller 1648c4ead4c5SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp); 1649c1b4a7e6SDavid S. Miller if (unlikely(buff == NULL)) 1650c1b4a7e6SDavid S. Miller return -ENOMEM; 1651c1b4a7e6SDavid S. Miller 16523ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 16533ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1654b60b49eaSHerbert Xu buff->truesize += nlen; 1655c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1656c1b4a7e6SDavid S. Miller 1657c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1658c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1659c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1660c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1661c1b4a7e6SDavid S. Miller 1662c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 16634de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 16644de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 16654de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1666c1b4a7e6SDavid S. Miller 1667c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1668c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1669c1b4a7e6SDavid S. Miller 167084fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1671c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1672490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1673c1b4a7e6SDavid S. Miller 1674c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 1675846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1676846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 1677c1b4a7e6SDavid S. Miller 1678c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1679f4a775d1SEric Dumazet __skb_header_release(buff); 1680fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1681c1b4a7e6SDavid S. Miller 1682c1b4a7e6SDavid S. Miller return 0; 1683c1b4a7e6SDavid S. Miller } 1684c1b4a7e6SDavid S. Miller 1685c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1686c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1687c1b4a7e6SDavid S. Miller * 1688c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1689c1b4a7e6SDavid S. Miller */ 1690ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1691ca8a2263SNeal Cardwell bool *is_cwnd_limited) 1692c1b4a7e6SDavid S. Miller { 16939e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 16946687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1695c1b4a7e6SDavid S. Miller u32 send_win, cong_win, limit, in_flight; 1696ad9f4f50SEric Dumazet int win_divisor; 1697c1b4a7e6SDavid S. Miller 16984de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1699ae8064acSJohn Heffner goto send_now; 1700c1b4a7e6SDavid S. Miller 17016687e988SArnaldo Carvalho de Melo if (icsk->icsk_ca_state != TCP_CA_Open) 1702ae8064acSJohn Heffner goto send_now; 1703ae8064acSJohn Heffner 1704ae8064acSJohn Heffner /* Defer for less than two clock ticks. */ 1705bd515c3eSIlpo Järvinen if (tp->tso_deferred && 1706a2acde07SIlpo Järvinen (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) 1707ae8064acSJohn Heffner goto send_now; 1708908a75c1SDavid S. Miller 1709c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1710c1b4a7e6SDavid S. Miller 1711056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1712c1b4a7e6SDavid S. Miller 171390840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1714c1b4a7e6SDavid S. Miller 1715c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1716c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1717c1b4a7e6SDavid S. Miller 1718c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1719c1b4a7e6SDavid S. Miller 1720ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 17211485348dSBen Hutchings if (limit >= min_t(unsigned int, sk->sk_gso_max_size, 172295bd09ebSEric Dumazet tp->xmit_size_goal_segs * tp->mss_cache)) 1723ae8064acSJohn Heffner goto send_now; 1724ba244fe9SDavid S. Miller 172562ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 172662ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 172762ad2761SIlpo Järvinen goto send_now; 172862ad2761SIlpo Järvinen 1729ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1730ad9f4f50SEric Dumazet if (win_divisor) { 1731c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1732c1b4a7e6SDavid S. Miller 1733c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1734c1b4a7e6SDavid S. Miller * just use it. 1735c1b4a7e6SDavid S. Miller */ 1736ad9f4f50SEric Dumazet chunk /= win_divisor; 1737c1b4a7e6SDavid S. Miller if (limit >= chunk) 1738ae8064acSJohn Heffner goto send_now; 1739c1b4a7e6SDavid S. Miller } else { 1740c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1741c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1742c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1743c1b4a7e6SDavid S. Miller * then send now. 1744c1b4a7e6SDavid S. Miller */ 17456b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1746ae8064acSJohn Heffner goto send_now; 1747c1b4a7e6SDavid S. Miller } 1748c1b4a7e6SDavid S. Miller 1749f4541d60SEric Dumazet /* Ok, it looks like it is advisable to defer. 1750f4541d60SEric Dumazet * Do not rearm the timer if already set to not break TCP ACK clocking. 1751f4541d60SEric Dumazet */ 1752f4541d60SEric Dumazet if (!tp->tso_deferred) 1753ae8064acSJohn Heffner tp->tso_deferred = 1 | (jiffies << 1); 1754ae8064acSJohn Heffner 1755ca8a2263SNeal Cardwell if (cong_win < send_win && cong_win < skb->len) 1756ca8a2263SNeal Cardwell *is_cwnd_limited = true; 1757ca8a2263SNeal Cardwell 1758a2a385d6SEric Dumazet return true; 1759ae8064acSJohn Heffner 1760ae8064acSJohn Heffner send_now: 1761ae8064acSJohn Heffner tp->tso_deferred = 0; 1762a2a385d6SEric Dumazet return false; 1763c1b4a7e6SDavid S. Miller } 1764c1b4a7e6SDavid S. Miller 17655d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 176667edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 176767edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 176867edfef7SAndi Kleen * changes resulting in larger path MTUs. 176967edfef7SAndi Kleen * 17705d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 17715d424d5aSJohn Heffner * 1 if a probe was sent, 1772056834d9SIlpo Järvinen * -1 otherwise 1773056834d9SIlpo Järvinen */ 17745d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 17755d424d5aSJohn Heffner { 17765d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 17775d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 17785d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 17795d424d5aSJohn Heffner int len; 17805d424d5aSJohn Heffner int probe_size; 178191cc17c0SIlpo Järvinen int size_needed; 17825d424d5aSJohn Heffner int copy; 17835d424d5aSJohn Heffner int mss_now; 17845d424d5aSJohn Heffner 17855d424d5aSJohn Heffner /* Not currently probing/verifying, 17865d424d5aSJohn Heffner * not in recovery, 17875d424d5aSJohn Heffner * have enough cwnd, and 17885d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 17895d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 17905d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 17915d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 17925d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1793cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 17945d424d5aSJohn Heffner return -1; 17955d424d5aSJohn Heffner 17965d424d5aSJohn Heffner /* Very simple search strategy: just double the MSS. */ 17970c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 17985d424d5aSJohn Heffner probe_size = 2 * tp->mss_cache; 179991cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 18005d424d5aSJohn Heffner if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { 18015d424d5aSJohn Heffner /* TODO: set timer for probe_converge_event */ 18025d424d5aSJohn Heffner return -1; 18035d424d5aSJohn Heffner } 18045d424d5aSJohn Heffner 18055d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 18067f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 18075d424d5aSJohn Heffner return -1; 18085d424d5aSJohn Heffner 180991cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 18105d424d5aSJohn Heffner return -1; 181190840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 18125d424d5aSJohn Heffner return 0; 18135d424d5aSJohn Heffner 1814d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1815d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1816d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 18175d424d5aSJohn Heffner return -1; 18185d424d5aSJohn Heffner else 18195d424d5aSJohn Heffner return 0; 18205d424d5aSJohn Heffner } 18215d424d5aSJohn Heffner 18225d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 18235d424d5aSJohn Heffner if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) 18245d424d5aSJohn Heffner return -1; 18253ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 18263ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 18275d424d5aSJohn Heffner 1828fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 18295d424d5aSJohn Heffner 18305d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 18315d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 18324de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 18335d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 18345d424d5aSJohn Heffner nskb->csum = 0; 183584fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 18365d424d5aSJohn Heffner 183750c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 183850c4817eSIlpo Järvinen 18395d424d5aSJohn Heffner len = 0; 1840234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 18415d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 18425d424d5aSJohn Heffner if (nskb->ip_summed) 18435d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 18445d424d5aSJohn Heffner else 18455d424d5aSJohn Heffner nskb->csum = skb_copy_and_csum_bits(skb, 0, 1846056834d9SIlpo Järvinen skb_put(nskb, copy), 1847056834d9SIlpo Järvinen copy, nskb->csum); 18485d424d5aSJohn Heffner 18495d424d5aSJohn Heffner if (skb->len <= copy) { 18505d424d5aSJohn Heffner /* We've eaten all the data from this skb. 18515d424d5aSJohn Heffner * Throw it away. */ 18524de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 1853fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 18543ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 18555d424d5aSJohn Heffner } else { 18564de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 1857a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 18585d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 18595d424d5aSJohn Heffner skb_pull(skb, copy); 186084fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 1861056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 1862056834d9SIlpo Järvinen skb->len, 0); 18635d424d5aSJohn Heffner } else { 18645d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 18655d424d5aSJohn Heffner tcp_set_skb_tso_segs(sk, skb, mss_now); 18665d424d5aSJohn Heffner } 18675d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 18685d424d5aSJohn Heffner } 18695d424d5aSJohn Heffner 18705d424d5aSJohn Heffner len += copy; 1871234b6860SIlpo Järvinen 1872234b6860SIlpo Järvinen if (len >= probe_size) 1873234b6860SIlpo Järvinen break; 18745d424d5aSJohn Heffner } 18755d424d5aSJohn Heffner tcp_init_tso_segs(sk, nskb, nskb->len); 18765d424d5aSJohn Heffner 18775d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 18787faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 18797faee5c0SEric Dumazet */ 18805d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 18815d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 18825d424d5aSJohn Heffner * effectively two packets. */ 18835d424d5aSJohn Heffner tp->snd_cwnd--; 188466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 18855d424d5aSJohn Heffner 18865d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 18870e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 18880e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 18895d424d5aSJohn Heffner 18905d424d5aSJohn Heffner return 1; 18915d424d5aSJohn Heffner } 18925d424d5aSJohn Heffner 18935d424d5aSJohn Heffner return -1; 18945d424d5aSJohn Heffner } 18955d424d5aSJohn Heffner 18961da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 18971da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 18981da177e4SLinus Torvalds * window for us. 18991da177e4SLinus Torvalds * 1900f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 1901f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 1902f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 1903f8269a49SIlpo Järvinen * 19046ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 19056ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 19066ba8a3b1SNandita Dukkipati 1907a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 1908a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 19091da177e4SLinus Torvalds */ 1910a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 1911d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 19121da177e4SLinus Torvalds { 19131da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 191492df7b51SDavid S. Miller struct sk_buff *skb; 1915c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 1916c1b4a7e6SDavid S. Miller int cwnd_quota; 19175d424d5aSJohn Heffner int result; 1918ca8a2263SNeal Cardwell bool is_cwnd_limited = false; 19191da177e4SLinus Torvalds 1920c1b4a7e6SDavid S. Miller sent_pkts = 0; 19215d424d5aSJohn Heffner 1922d5dd9175SIlpo Järvinen if (!push_one) { 19235d424d5aSJohn Heffner /* Do MTU probing. */ 1924d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 1925d5dd9175SIlpo Järvinen if (!result) { 1926a2a385d6SEric Dumazet return false; 19275d424d5aSJohn Heffner } else if (result > 0) { 19285d424d5aSJohn Heffner sent_pkts = 1; 19295d424d5aSJohn Heffner } 1930d5dd9175SIlpo Järvinen } 19315d424d5aSJohn Heffner 1932fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 1933c8ac3774SHerbert Xu unsigned int limit; 1934c8ac3774SHerbert Xu 1935b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 1936c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 1937c1b4a7e6SDavid S. Miller 19389d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 19397faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 19407faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 1941ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 19429d186cacSAndrey Vagin } 1943ec342325SAndrew Vagin 1944b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 19456ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 1946ca8a2263SNeal Cardwell is_cwnd_limited = true; 19476ba8a3b1SNandita Dukkipati if (push_one == 2) 19486ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 19496ba8a3b1SNandita Dukkipati cwnd_quota = 1; 19506ba8a3b1SNandita Dukkipati else 1951b68e9f85SHerbert Xu break; 19526ba8a3b1SNandita Dukkipati } 1953b68e9f85SHerbert Xu 1954b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 1955b68e9f85SHerbert Xu break; 1956b68e9f85SHerbert Xu 1957c1b4a7e6SDavid S. Miller if (tso_segs == 1) { 1958aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 1959aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1960aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 1961aa93466bSDavid S. Miller break; 1962c1b4a7e6SDavid S. Miller } else { 1963ca8a2263SNeal Cardwell if (!push_one && 1964ca8a2263SNeal Cardwell tcp_tso_should_defer(sk, skb, &is_cwnd_limited)) 1965aa93466bSDavid S. Miller break; 1966c1b4a7e6SDavid S. Miller } 1967aa93466bSDavid S. Miller 1968c9eeec26SEric Dumazet /* TCP Small Queues : 1969c9eeec26SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 1970c9eeec26SEric Dumazet * This allows for : 1971c9eeec26SEric Dumazet * - better RTT estimation and ACK scheduling 1972c9eeec26SEric Dumazet * - faster recovery 1973c9eeec26SEric Dumazet * - high rates 197498e09386SEric Dumazet * Alas, some drivers / subsystems require a fair amount 197598e09386SEric Dumazet * of queued bytes to ensure line rate. 197698e09386SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 197746d3ceabSEric Dumazet */ 197898e09386SEric Dumazet limit = max_t(unsigned int, sysctl_tcp_limit_output_bytes, 197998e09386SEric Dumazet sk->sk_pacing_rate >> 10); 1980c9eeec26SEric Dumazet 1981c9eeec26SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) { 198246d3ceabSEric Dumazet set_bit(TSQ_THROTTLED, &tp->tsq_flags); 1983bf06200eSJohn Ogness /* It is possible TX completion already happened 1984bf06200eSJohn Ogness * before we set TSQ_THROTTLED, so we must 1985bf06200eSJohn Ogness * test again the condition. 1986bf06200eSJohn Ogness */ 19874e857c58SPeter Zijlstra smp_mb__after_atomic(); 1988bf06200eSJohn Ogness if (atomic_read(&sk->sk_wmem_alloc) > limit) 198946d3ceabSEric Dumazet break; 199046d3ceabSEric Dumazet } 1991c9eeec26SEric Dumazet 1992c8ac3774SHerbert Xu limit = mss_now; 1993f8269a49SIlpo Järvinen if (tso_segs > 1 && !tcp_urg_mode(tp)) 19940e3a4803SIlpo Järvinen limit = tcp_mss_split_point(sk, skb, mss_now, 19951485348dSBen Hutchings min_t(unsigned int, 19961485348dSBen Hutchings cwnd_quota, 1997d4589926SEric Dumazet sk->sk_gso_max_segs), 1998d4589926SEric Dumazet nonagle); 1999c8ac3774SHerbert Xu 2000c8ac3774SHerbert Xu if (skb->len > limit && 2001c4ead4c5SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 20021da177e4SLinus Torvalds break; 20031da177e4SLinus Torvalds 2004d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 20051da177e4SLinus Torvalds break; 20061da177e4SLinus Torvalds 2007ec342325SAndrew Vagin repair: 20081da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 20091da177e4SLinus Torvalds * This call will increment packets_out. 20101da177e4SLinus Torvalds */ 201166f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 20121da177e4SLinus Torvalds 20131da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2014a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2015d5dd9175SIlpo Järvinen 2016d5dd9175SIlpo Järvinen if (push_one) 2017d5dd9175SIlpo Järvinen break; 20181da177e4SLinus Torvalds } 20191da177e4SLinus Torvalds 2020aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2021684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2022684bad11SYuchung Cheng tp->prr_out += sent_pkts; 20236ba8a3b1SNandita Dukkipati 20246ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 20256ba8a3b1SNandita Dukkipati if (push_one != 2) 20266ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 2027ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2028a2a385d6SEric Dumazet return false; 20291da177e4SLinus Torvalds } 20306ba8a3b1SNandita Dukkipati return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); 20316ba8a3b1SNandita Dukkipati } 20326ba8a3b1SNandita Dukkipati 20336ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 20346ba8a3b1SNandita Dukkipati { 20356ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 20366ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 20376ba8a3b1SNandita Dukkipati u32 timeout, tlp_time_stamp, rto_time_stamp; 2038740b0f18SEric Dumazet u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); 20396ba8a3b1SNandita Dukkipati 20406ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) 20416ba8a3b1SNandita Dukkipati return false; 20426ba8a3b1SNandita Dukkipati /* No consecutive loss probes. */ 20436ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { 20446ba8a3b1SNandita Dukkipati tcp_rearm_rto(sk); 20456ba8a3b1SNandita Dukkipati return false; 20466ba8a3b1SNandita Dukkipati } 20476ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 20486ba8a3b1SNandita Dukkipati * finishes. 20496ba8a3b1SNandita Dukkipati */ 20506ba8a3b1SNandita Dukkipati if (sk->sk_state == TCP_SYN_RECV) 20516ba8a3b1SNandita Dukkipati return false; 20526ba8a3b1SNandita Dukkipati 20536ba8a3b1SNandita Dukkipati /* TLP is only scheduled when next timer event is RTO. */ 20546ba8a3b1SNandita Dukkipati if (icsk->icsk_pending != ICSK_TIME_RETRANS) 20556ba8a3b1SNandita Dukkipati return false; 20566ba8a3b1SNandita Dukkipati 20576ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 20586ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 20596ba8a3b1SNandita Dukkipati */ 2060740b0f18SEric Dumazet if (sysctl_tcp_early_retrans < 3 || !tp->srtt_us || !tp->packets_out || 20616ba8a3b1SNandita Dukkipati !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) 20626ba8a3b1SNandita Dukkipati return false; 20636ba8a3b1SNandita Dukkipati 20646ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 20656ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 20666ba8a3b1SNandita Dukkipati return false; 20676ba8a3b1SNandita Dukkipati 20686ba8a3b1SNandita Dukkipati /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account 20696ba8a3b1SNandita Dukkipati * for delayed ack when there's one outstanding packet. 20706ba8a3b1SNandita Dukkipati */ 20716ba8a3b1SNandita Dukkipati timeout = rtt << 1; 20726ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 20736ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, 20746ba8a3b1SNandita Dukkipati (rtt + (rtt >> 1) + TCP_DELACK_MAX)); 20756ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, msecs_to_jiffies(10)); 20766ba8a3b1SNandita Dukkipati 20776ba8a3b1SNandita Dukkipati /* If RTO is shorter, just schedule TLP in its place. */ 20786ba8a3b1SNandita Dukkipati tlp_time_stamp = tcp_time_stamp + timeout; 20796ba8a3b1SNandita Dukkipati rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; 20806ba8a3b1SNandita Dukkipati if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { 20816ba8a3b1SNandita Dukkipati s32 delta = rto_time_stamp - tcp_time_stamp; 20826ba8a3b1SNandita Dukkipati if (delta > 0) 20836ba8a3b1SNandita Dukkipati timeout = delta; 20846ba8a3b1SNandita Dukkipati } 20856ba8a3b1SNandita Dukkipati 20866ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 20876ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 20886ba8a3b1SNandita Dukkipati return true; 20896ba8a3b1SNandita Dukkipati } 20906ba8a3b1SNandita Dukkipati 20911f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 20921f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 20931f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 20941f3279aeSEric Dumazet * Note: This is called from BH context only. 20951f3279aeSEric Dumazet */ 20961f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 20971f3279aeSEric Dumazet const struct sk_buff *skb) 20981f3279aeSEric Dumazet { 20991f3279aeSEric Dumazet const struct sk_buff *fclone = skb + 1; 21001f3279aeSEric Dumazet 21011f3279aeSEric Dumazet if (unlikely(skb->fclone == SKB_FCLONE_ORIG && 21021f3279aeSEric Dumazet fclone->fclone == SKB_FCLONE_CLONE)) { 21031f3279aeSEric Dumazet NET_INC_STATS_BH(sock_net(sk), 21041f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 21051f3279aeSEric Dumazet return true; 21061f3279aeSEric Dumazet } 21071f3279aeSEric Dumazet return false; 21081f3279aeSEric Dumazet } 21091f3279aeSEric Dumazet 21106ba8a3b1SNandita Dukkipati /* When probe timeout (PTO) fires, send a new segment if one exists, else 21116ba8a3b1SNandita Dukkipati * retransmit the last segment. 21126ba8a3b1SNandita Dukkipati */ 21136ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 21146ba8a3b1SNandita Dukkipati { 21159b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 21166ba8a3b1SNandita Dukkipati struct sk_buff *skb; 21176ba8a3b1SNandita Dukkipati int pcount; 21186ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 21196ba8a3b1SNandita Dukkipati int err = -1; 21206ba8a3b1SNandita Dukkipati 21216ba8a3b1SNandita Dukkipati if (tcp_send_head(sk) != NULL) { 21226ba8a3b1SNandita Dukkipati err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 21236ba8a3b1SNandita Dukkipati goto rearm_timer; 21246ba8a3b1SNandita Dukkipati } 21256ba8a3b1SNandita Dukkipati 21269b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 21279b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 21289b717a8dSNandita Dukkipati goto rearm_timer; 21299b717a8dSNandita Dukkipati 21306ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 21316ba8a3b1SNandita Dukkipati skb = tcp_write_queue_tail(sk); 21326ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 21336ba8a3b1SNandita Dukkipati goto rearm_timer; 21346ba8a3b1SNandita Dukkipati 21351f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 21361f3279aeSEric Dumazet goto rearm_timer; 21371f3279aeSEric Dumazet 21386ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 21396ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 21406ba8a3b1SNandita Dukkipati goto rearm_timer; 21416ba8a3b1SNandita Dukkipati 21426ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 21436cc55e09SOctavian Purdila if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, 21446cc55e09SOctavian Purdila GFP_ATOMIC))) 21456ba8a3b1SNandita Dukkipati goto rearm_timer; 21466ba8a3b1SNandita Dukkipati skb = tcp_write_queue_tail(sk); 21476ba8a3b1SNandita Dukkipati } 21486ba8a3b1SNandita Dukkipati 21496ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 21506ba8a3b1SNandita Dukkipati goto rearm_timer; 21516ba8a3b1SNandita Dukkipati 21526ba8a3b1SNandita Dukkipati err = __tcp_retransmit_skb(sk, skb); 21536ba8a3b1SNandita Dukkipati 21549b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 21559b717a8dSNandita Dukkipati if (likely(!err)) 21569b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 21579b717a8dSNandita Dukkipati 21586ba8a3b1SNandita Dukkipati rearm_timer: 21596ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 21606ba8a3b1SNandita Dukkipati inet_csk(sk)->icsk_rto, 21616ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 21626ba8a3b1SNandita Dukkipati 21636ba8a3b1SNandita Dukkipati if (likely(!err)) 21646ba8a3b1SNandita Dukkipati NET_INC_STATS_BH(sock_net(sk), 21656ba8a3b1SNandita Dukkipati LINUX_MIB_TCPLOSSPROBES); 21661da177e4SLinus Torvalds } 21671da177e4SLinus Torvalds 2168a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2169a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2170a762a980SDavid S. Miller * The socket must be locked by the caller. 2171a762a980SDavid S. Miller */ 21729e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 21739e412ba7SIlpo Järvinen int nonagle) 2174a762a980SDavid S. Miller { 2175726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2176726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2177726e07a8SIlpo Järvinen * all will be happy. 2178726e07a8SIlpo Järvinen */ 2179726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2180726e07a8SIlpo Järvinen return; 2181726e07a8SIlpo Järvinen 218299a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 218399a1dec7SMel Gorman sk_gfp_atomic(sk, GFP_ATOMIC))) 21849e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2185a762a980SDavid S. Miller } 2186a762a980SDavid S. Miller 2187c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2188c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2189c1b4a7e6SDavid S. Miller */ 2190c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2191c1b4a7e6SDavid S. Miller { 2192fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2193c1b4a7e6SDavid S. Miller 2194c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2195c1b4a7e6SDavid S. Miller 2196d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2197c1b4a7e6SDavid S. Miller } 2198c1b4a7e6SDavid S. Miller 21991da177e4SLinus Torvalds /* This function returns the amount that we can raise the 22001da177e4SLinus Torvalds * usable window based on the following constraints 22011da177e4SLinus Torvalds * 22021da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 22031da177e4SLinus Torvalds * 2. We limit memory per socket 22041da177e4SLinus Torvalds * 22051da177e4SLinus Torvalds * RFC 1122: 22061da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 22071da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 22081da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 22091da177e4SLinus Torvalds * 22101da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 22111da177e4SLinus Torvalds * it at least MSS bytes. 22121da177e4SLinus Torvalds * 22131da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 22141da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 22151da177e4SLinus Torvalds * 22161da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 22171da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 22181da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 22191da177e4SLinus Torvalds * window to always advance by a single byte. 22201da177e4SLinus Torvalds * 22211da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 22221da177e4SLinus Torvalds * then this will not be a problem. 22231da177e4SLinus Torvalds * 22241da177e4SLinus Torvalds * BSD seems to make the following compromise: 22251da177e4SLinus Torvalds * 22261da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 22271da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 22281da177e4SLinus Torvalds * then set the window to 0. 22291da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 22301da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 22311da177e4SLinus Torvalds * and from being larger than the largest representable value. 22321da177e4SLinus Torvalds * 22331da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 22341da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 22351da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 22361da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 22371da177e4SLinus Torvalds * because the pipeline is full. 22381da177e4SLinus Torvalds * 22391da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 22401da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 22411da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 22421da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 22431da177e4SLinus Torvalds * of having a fixed window size at almost all times. 22441da177e4SLinus Torvalds * 22451da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 22461da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 22471da177e4SLinus Torvalds * 22481da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 22491da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 22501da177e4SLinus Torvalds */ 22511da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 22521da177e4SLinus Torvalds { 2253463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 22541da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2255caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 22561da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 22571da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 22581da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 22591da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 22601da177e4SLinus Torvalds */ 2261463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 22621da177e4SLinus Torvalds int free_space = tcp_space(sk); 226386c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 226486c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 22651da177e4SLinus Torvalds int window; 22661da177e4SLinus Torvalds 22671da177e4SLinus Torvalds if (mss > full_space) 22681da177e4SLinus Torvalds mss = full_space; 22691da177e4SLinus Torvalds 2270b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2271463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 22721da177e4SLinus Torvalds 2273180d8cd9SGlauber Costa if (sk_under_memory_pressure(sk)) 2274056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2275056834d9SIlpo Järvinen 4U * tp->advmss); 22761da177e4SLinus Torvalds 227786c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 227886c1a045SFlorian Westphal * increase it due to wscale. 227986c1a045SFlorian Westphal */ 228086c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 228186c1a045SFlorian Westphal 228286c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 228386c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 228486c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 228586c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 228686c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 228786c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 228886c1a045SFlorian Westphal */ 228986c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 22901da177e4SLinus Torvalds return 0; 22911da177e4SLinus Torvalds } 22921da177e4SLinus Torvalds 22931da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 22941da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 22951da177e4SLinus Torvalds 22961da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 22971da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 22981da177e4SLinus Torvalds */ 22991da177e4SLinus Torvalds window = tp->rcv_wnd; 23001da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 23011da177e4SLinus Torvalds window = free_space; 23021da177e4SLinus Torvalds 23031da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 23041da177e4SLinus Torvalds * Import case: prevent zero window announcement if 23051da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 23061da177e4SLinus Torvalds */ 23071da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 23081da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 23091da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 23101da177e4SLinus Torvalds } else { 23111da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 23121da177e4SLinus Torvalds * Window clamp already applied above. 23131da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 23141da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 23151da177e4SLinus Torvalds * and multiply from happening most of the time. 23161da177e4SLinus Torvalds * We also don't do any window rounding when the free space 23171da177e4SLinus Torvalds * is too small. 23181da177e4SLinus Torvalds */ 23191da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 23201da177e4SLinus Torvalds window = (free_space / mss) * mss; 232184565070SJohn Heffner else if (mss == full_space && 2322b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 232384565070SJohn Heffner window = free_space; 23241da177e4SLinus Torvalds } 23251da177e4SLinus Torvalds 23261da177e4SLinus Torvalds return window; 23271da177e4SLinus Torvalds } 23281da177e4SLinus Torvalds 23294a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 23304a17fc3aSIlpo Järvinen static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 23311da177e4SLinus Torvalds { 23321da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2333fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2334058dc334SIlpo Järvinen int skb_size, next_skb_size; 23351da177e4SLinus Torvalds 2336058dc334SIlpo Järvinen skb_size = skb->len; 2337058dc334SIlpo Järvinen next_skb_size = next_skb->len; 23381da177e4SLinus Torvalds 2339058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 23401da177e4SLinus Torvalds 23416859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 2342a6963a6bSIlpo Järvinen 2343fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 23441da177e4SLinus Torvalds 2345058dc334SIlpo Järvinen skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), 23461a4e2d09SArnaldo Carvalho de Melo next_skb_size); 23471da177e4SLinus Torvalds 234852d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 234952d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 23501da177e4SLinus Torvalds 235184fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 23521da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 23531da177e4SLinus Torvalds 23541da177e4SLinus Torvalds /* Update sequence range on original skb. */ 23551da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 23561da177e4SLinus Torvalds 2357e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 23584de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 23591da177e4SLinus Torvalds 23601da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 23611da177e4SLinus Torvalds * packet counting does not break. 23621da177e4SLinus Torvalds */ 23634828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2364b7689205SIlpo Järvinen 2365b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2366ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2367ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2368ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2369b7689205SIlpo Järvinen 2370797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2371797108d1SIlpo Järvinen 23723ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 23731da177e4SLinus Torvalds } 23741da177e4SLinus Torvalds 237567edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2376a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 23774a17fc3aSIlpo Järvinen { 23784a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2379a2a385d6SEric Dumazet return false; 23804a17fc3aSIlpo Järvinen /* TODO: SACK collapsing could be used to remove this condition */ 23814a17fc3aSIlpo Järvinen if (skb_shinfo(skb)->nr_frags != 0) 2382a2a385d6SEric Dumazet return false; 23834a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2384a2a385d6SEric Dumazet return false; 23854a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2386a2a385d6SEric Dumazet return false; 23874a17fc3aSIlpo Järvinen /* Some heurestics for collapsing over SACK'd could be invented */ 23884a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2389a2a385d6SEric Dumazet return false; 23904a17fc3aSIlpo Järvinen 2391a2a385d6SEric Dumazet return true; 23924a17fc3aSIlpo Järvinen } 23934a17fc3aSIlpo Järvinen 239467edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 239567edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 239667edfef7SAndi Kleen */ 23974a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 23984a17fc3aSIlpo Järvinen int space) 23994a17fc3aSIlpo Järvinen { 24004a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 24014a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2402a2a385d6SEric Dumazet bool first = true; 24034a17fc3aSIlpo Järvinen 24044a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 24054a17fc3aSIlpo Järvinen return; 24064de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 24074a17fc3aSIlpo Järvinen return; 24084a17fc3aSIlpo Järvinen 24094a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 24104a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 24114a17fc3aSIlpo Järvinen break; 24124a17fc3aSIlpo Järvinen 24134a17fc3aSIlpo Järvinen space -= skb->len; 24144a17fc3aSIlpo Järvinen 24154a17fc3aSIlpo Järvinen if (first) { 2416a2a385d6SEric Dumazet first = false; 24174a17fc3aSIlpo Järvinen continue; 24184a17fc3aSIlpo Järvinen } 24194a17fc3aSIlpo Järvinen 24204a17fc3aSIlpo Järvinen if (space < 0) 24214a17fc3aSIlpo Järvinen break; 24224a17fc3aSIlpo Järvinen /* Punt if not enough space exists in the first SKB for 24234a17fc3aSIlpo Järvinen * the data in the second 24244a17fc3aSIlpo Järvinen */ 2425a21d4572SEric Dumazet if (skb->len > skb_availroom(to)) 24264a17fc3aSIlpo Järvinen break; 24274a17fc3aSIlpo Järvinen 24284a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 24294a17fc3aSIlpo Järvinen break; 24304a17fc3aSIlpo Järvinen 24314a17fc3aSIlpo Järvinen tcp_collapse_retrans(sk, to); 24324a17fc3aSIlpo Järvinen } 24334a17fc3aSIlpo Järvinen } 24344a17fc3aSIlpo Järvinen 24351da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 24361da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 24371da177e4SLinus Torvalds * error occurred which prevented the send. 24381da177e4SLinus Torvalds */ 243993b174adSYuchung Cheng int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 24401da177e4SLinus Torvalds { 24411da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 24425d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 24437d227cd2SSridhar Samudrala unsigned int cur_mss; 2444c84a5711SYuchung Cheng int err; 24451da177e4SLinus Torvalds 24465d424d5aSJohn Heffner /* Inconslusive MTU probe */ 24475d424d5aSJohn Heffner if (icsk->icsk_mtup.probe_size) { 24485d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 24495d424d5aSJohn Heffner } 24505d424d5aSJohn Heffner 24511da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2452caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 24531da177e4SLinus Torvalds */ 24541da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 24551da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 24561da177e4SLinus Torvalds return -EAGAIN; 24571da177e4SLinus Torvalds 24581f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 24591f3279aeSEric Dumazet return -EBUSY; 24601f3279aeSEric Dumazet 24611da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 24621da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 24631da177e4SLinus Torvalds BUG(); 24641da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 24651da177e4SLinus Torvalds return -ENOMEM; 24661da177e4SLinus Torvalds } 24671da177e4SLinus Torvalds 24687d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 24697d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 24707d227cd2SSridhar Samudrala 24710c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 24727d227cd2SSridhar Samudrala 24731da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 24741da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 24751da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 24761da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 24771da177e4SLinus Torvalds */ 24789d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 24799d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 24801da177e4SLinus Torvalds return -EAGAIN; 24811da177e4SLinus Torvalds 24821da177e4SLinus Torvalds if (skb->len > cur_mss) { 24836cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, cur_mss, cur_mss, GFP_ATOMIC)) 24841da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 248502276f3cSIlpo Järvinen } else { 24869eb9362eSIlpo Järvinen int oldpcount = tcp_skb_pcount(skb); 24879eb9362eSIlpo Järvinen 24889eb9362eSIlpo Järvinen if (unlikely(oldpcount > 1)) { 2489c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2490c52e2421SEric Dumazet return -ENOMEM; 249102276f3cSIlpo Järvinen tcp_init_tso_segs(sk, skb, cur_mss); 24929eb9362eSIlpo Järvinen tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); 24939eb9362eSIlpo Järvinen } 24941da177e4SLinus Torvalds } 24951da177e4SLinus Torvalds 24961da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 24971da177e4SLinus Torvalds 24981da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 24991da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 25001da177e4SLinus Torvalds */ 25011da177e4SLinus Torvalds 250250bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 250350bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 250450bceae9SThomas Graf * beyond what csum_start can cover. 250550bceae9SThomas Graf */ 250650bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 250750bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 2508117632e6SEric Dumazet struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, 2509117632e6SEric Dumazet GFP_ATOMIC); 2510c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2511117632e6SEric Dumazet -ENOBUFS; 2512117632e6SEric Dumazet } else { 2513c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2514117632e6SEric Dumazet } 2515c84a5711SYuchung Cheng 2516fc9f3501SEric Dumazet if (likely(!err)) { 2517c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2518fc9f3501SEric Dumazet /* Update global TCP statistics. */ 2519fc9f3501SEric Dumazet TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 2520fc9f3501SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 2521fc9f3501SEric Dumazet NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 2522fc9f3501SEric Dumazet tp->total_retrans++; 2523fc9f3501SEric Dumazet } 2524c84a5711SYuchung Cheng return err; 252593b174adSYuchung Cheng } 252693b174adSYuchung Cheng 252793b174adSYuchung Cheng int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 252893b174adSYuchung Cheng { 252993b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 253093b174adSYuchung Cheng int err = __tcp_retransmit_skb(sk, skb); 25311da177e4SLinus Torvalds 25321da177e4SLinus Torvalds if (err == 0) { 25331da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 25341da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2535e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 25361da177e4SLinus Torvalds } 25371da177e4SLinus Torvalds #endif 2538b08d6cb2SIlpo Järvinen if (!tp->retrans_out) 2539b08d6cb2SIlpo Järvinen tp->lost_retrans_low = tp->snd_nxt; 25401da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 25411da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 25421da177e4SLinus Torvalds 25431da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 25441da177e4SLinus Torvalds if (!tp->retrans_stamp) 25457faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 25461da177e4SLinus Torvalds 25471da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 25481da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 25491da177e4SLinus Torvalds */ 25501da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 25511f3279aeSEric Dumazet } else if (err != -EBUSY) { 255224ab6becSYuchung Cheng NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 25531da177e4SLinus Torvalds } 25546e08d5e3SYuchung Cheng 25556e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 25566e08d5e3SYuchung Cheng tp->undo_retrans = 0; 25576e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 25581da177e4SLinus Torvalds return err; 25591da177e4SLinus Torvalds } 25601da177e4SLinus Torvalds 256167edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 256267edfef7SAndi Kleen * window/congestion state. 256367edfef7SAndi Kleen */ 2564a2a385d6SEric Dumazet static bool tcp_can_forward_retransmit(struct sock *sk) 2565b5afe7bcSIlpo Järvinen { 2566b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2567cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2568b5afe7bcSIlpo Järvinen 2569b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2570b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2571a2a385d6SEric Dumazet return false; 2572b5afe7bcSIlpo Järvinen 2573b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2574b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2575a2a385d6SEric Dumazet return false; 2576b5afe7bcSIlpo Järvinen 2577b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2578b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2579b5afe7bcSIlpo Järvinen * 2580b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2581b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2582b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2583b5afe7bcSIlpo Järvinen */ 2584b5afe7bcSIlpo Järvinen 2585b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2586a2a385d6SEric Dumazet return false; 2587b5afe7bcSIlpo Järvinen 2588a2a385d6SEric Dumazet return true; 2589b5afe7bcSIlpo Järvinen } 2590b5afe7bcSIlpo Järvinen 25911da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 25921da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 25931da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 25941da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 25951da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 25961da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 25971da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 25981da177e4SLinus Torvalds */ 25991da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 26001da177e4SLinus Torvalds { 26016687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 26021da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 26031da177e4SLinus Torvalds struct sk_buff *skb; 26040e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2605618d9f25SIlpo Järvinen u32 last_lost; 260661eb55f4SIlpo Järvinen int mib_idx; 26070e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 26086a438bbeSStephen Hemminger 260945e77d31SIlpo Järvinen if (!tp->packets_out) 261045e77d31SIlpo Järvinen return; 261145e77d31SIlpo Järvinen 261208ebd172SIlpo Järvinen if (!tp->lost_out) 261308ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 261408ebd172SIlpo Järvinen 2615618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 26166a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2617618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2618618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2619618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2620618d9f25SIlpo Järvinen } else { 2621fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2622618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2623618d9f25SIlpo Järvinen } 26241da177e4SLinus Torvalds 2625fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 26261da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 26271da177e4SLinus Torvalds 2628fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2629fe067e8aSDavid S. Miller break; 26306a438bbeSStephen Hemminger /* we could do better than to assign each time */ 26310e1c54c2SIlpo Järvinen if (hole == NULL) 26326a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 26336a438bbeSStephen Hemminger 26341da177e4SLinus Torvalds /* Assume this retransmit will generate 26351da177e4SLinus Torvalds * only one packet for congestion window 26361da177e4SLinus Torvalds * calculation purposes. This works because 26371da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 26381da177e4SLinus Torvalds * packet to be MSS sized and all the 26391da177e4SLinus Torvalds * packet counting works out. 26401da177e4SLinus Torvalds */ 26411da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 26421da177e4SLinus Torvalds return; 26430e1c54c2SIlpo Järvinen 26440e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 26450e1c54c2SIlpo Järvinen begin_fwd: 26460e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2647006f582cSIlpo Järvinen break; 26480e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 26490e1c54c2SIlpo Järvinen 26500e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2651618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 26520e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 26530e1c54c2SIlpo Järvinen break; 26540e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 26550e1c54c2SIlpo Järvinen if (hole != NULL) { 26560e1c54c2SIlpo Järvinen skb = hole; 26570e1c54c2SIlpo Järvinen hole = NULL; 26580e1c54c2SIlpo Järvinen } 26590e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 26600e1c54c2SIlpo Järvinen goto begin_fwd; 26610e1c54c2SIlpo Järvinen 26620e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 2663ac11ba75SIlpo Järvinen if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 26640e1c54c2SIlpo Järvinen hole = skb; 266561eb55f4SIlpo Järvinen continue; 26661da177e4SLinus Torvalds 26670e1c54c2SIlpo Järvinen } else { 2668618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 26690e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 26700e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 26710e1c54c2SIlpo Järvinen else 26720e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 26730e1c54c2SIlpo Järvinen } 26740e1c54c2SIlpo Järvinen 26750e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 267661eb55f4SIlpo Järvinen continue; 267740b215e5SPavel Emelyanov 267824ab6becSYuchung Cheng if (tcp_retransmit_skb(sk, skb)) 26791da177e4SLinus Torvalds return; 268024ab6becSYuchung Cheng 2681de0744afSPavel Emelyanov NET_INC_STATS_BH(sock_net(sk), mib_idx); 26821da177e4SLinus Torvalds 2683684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2684a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2685a262f0cdSNandita Dukkipati 2686fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2687463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 26883f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 26893f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 26901da177e4SLinus Torvalds } 26911da177e4SLinus Torvalds } 26921da177e4SLinus Torvalds 26931da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 26941da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 26951da177e4SLinus Torvalds */ 26961da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 26971da177e4SLinus Torvalds { 26981da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2699fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_write_queue_tail(sk); 27001da177e4SLinus Torvalds int mss_now; 27011da177e4SLinus Torvalds 27021da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 27031da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 27041da177e4SLinus Torvalds * and IP options. 27051da177e4SLinus Torvalds */ 27060c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 27071da177e4SLinus Torvalds 2708fe067e8aSDavid S. Miller if (tcp_send_head(sk) != NULL) { 27094de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; 27101da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 27111da177e4SLinus Torvalds tp->write_seq++; 27121da177e4SLinus Torvalds } else { 27131da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 27141da177e4SLinus Torvalds for (;;) { 2715aa133076SWu Fengguang skb = alloc_skb_fclone(MAX_TCP_HEADER, 2716aa133076SWu Fengguang sk->sk_allocation); 27171da177e4SLinus Torvalds if (skb) 27181da177e4SLinus Torvalds break; 27191da177e4SLinus Torvalds yield(); 27201da177e4SLinus Torvalds } 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 27231da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 27241da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 2725e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 2726a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 27271da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 27281da177e4SLinus Torvalds } 27299e412ba7SIlpo Järvinen __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); 27301da177e4SLinus Torvalds } 27311da177e4SLinus Torvalds 27321da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 27331da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 27341da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 273565bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 27361da177e4SLinus Torvalds */ 2737dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 27381da177e4SLinus Torvalds { 27391da177e4SLinus Torvalds struct sk_buff *skb; 27401da177e4SLinus Torvalds 27411da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 27421da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 27431da177e4SLinus Torvalds if (!skb) { 27444e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 27451da177e4SLinus Torvalds return; 27461da177e4SLinus Torvalds } 27471da177e4SLinus Torvalds 27481da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 27491da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 2750e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 2751a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 27521da177e4SLinus Torvalds /* Send it off. */ 2753dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 27544e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 275526af65cbSSridhar Samudrala 275681cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 27571da177e4SLinus Torvalds } 27581da177e4SLinus Torvalds 275967edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 276067edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 27611da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 27621da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 27631da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 27641da177e4SLinus Torvalds */ 27651da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 27661da177e4SLinus Torvalds { 27671da177e4SLinus Torvalds struct sk_buff *skb; 27681da177e4SLinus Torvalds 2769fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 27704de075e0SEric Dumazet if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 277191df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 27721da177e4SLinus Torvalds return -EFAULT; 27731da177e4SLinus Torvalds } 27744de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 27751da177e4SLinus Torvalds if (skb_cloned(skb)) { 27761da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 27771da177e4SLinus Torvalds if (nskb == NULL) 27781da177e4SLinus Torvalds return -ENOMEM; 2779fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 2780f4a775d1SEric Dumazet __skb_header_release(nskb); 2781fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 27823ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 27833ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 27843ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 27851da177e4SLinus Torvalds skb = nskb; 27861da177e4SLinus Torvalds } 27871da177e4SLinus Torvalds 27884de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 27891da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 27901da177e4SLinus Torvalds } 2791dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 27921da177e4SLinus Torvalds } 27931da177e4SLinus Torvalds 27944aea39c1SEric Dumazet /** 27954aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 27964aea39c1SEric Dumazet * sk: listener socket 27974aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 27984aea39c1SEric Dumazet * req: request_sock pointer 27994aea39c1SEric Dumazet * 28004aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 28014aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 28024aea39c1SEric Dumazet */ 28031da177e4SLinus Torvalds struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 2804e6b4d113SWilliam Allen Simpson struct request_sock *req, 28058336886fSJerry Chu struct tcp_fastopen_cookie *foc) 28061da177e4SLinus Torvalds { 2807bd0388aeSWilliam Allen Simpson struct tcp_out_options opts; 28082e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 28091da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 28101da177e4SLinus Torvalds struct tcphdr *th; 28111da177e4SLinus Torvalds struct sk_buff *skb; 2812cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 2813bd0388aeSWilliam Allen Simpson int tcp_header_size; 2814f5fff5dcSTom Quetchenbach int mss; 28151da177e4SLinus Torvalds 2816a0b8486cSEric Dumazet skb = sock_wmalloc(sk, MAX_TCP_HEADER, 1, GFP_ATOMIC); 28174aea39c1SEric Dumazet if (unlikely(!skb)) { 28184aea39c1SEric Dumazet dst_release(dst); 28191da177e4SLinus Torvalds return NULL; 28204aea39c1SEric Dumazet } 28211da177e4SLinus Torvalds /* Reserve space for headers. */ 28221da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 28231da177e4SLinus Torvalds 28244aea39c1SEric Dumazet skb_dst_set(skb, dst); 2825ca10b9e9SEric Dumazet security_skb_owned_by(skb, sk); 28261da177e4SLinus Torvalds 28270dbaee3bSDavid S. Miller mss = dst_metric_advmss(dst); 2828f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) 2829f5fff5dcSTom Quetchenbach mss = tp->rx_opt.user_mss; 2830f5fff5dcSTom Quetchenbach 283133ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 28328b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 28338b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 28347faee5c0SEric Dumazet skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); 28358b5f12d0SFlorian Westphal else 28368b5f12d0SFlorian Westphal #endif 28377faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 28381a2c6181SChristoph Paasch tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5, 28391a2c6181SChristoph Paasch foc) + sizeof(*th); 284033ad798cSAdam Langley 2841aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 2842aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 28431da177e4SLinus Torvalds 2844aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 28451da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 28461da177e4SLinus Torvalds th->syn = 1; 28471da177e4SLinus Torvalds th->ack = 1; 28481da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 2849b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 2850634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 2851e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 2852e870a8efSIlpo Järvinen * not even correctly set) 2853e870a8efSIlpo Järvinen */ 2854e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 2855a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 28564957faadSWilliam Allen Simpson 28571da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 28588336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 28598336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 28601da177e4SLinus Torvalds 28611da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 2862600ff0c2SIlpo Järvinen th->window = htons(min(req->rcv_wnd, 65535U)); 2863bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 28641da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 2865a0b8486cSEric Dumazet TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_OUTSEGS); 2866cfb6eeb4SYOSHIFUJI Hideaki 2867cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2868cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 2869cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 2870bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 287149a72dfbSAdam Langley md5, NULL, req, skb); 2872cfb6eeb4SYOSHIFUJI Hideaki } 2873cfb6eeb4SYOSHIFUJI Hideaki #endif 2874cfb6eeb4SYOSHIFUJI Hideaki 28751da177e4SLinus Torvalds return skb; 28761da177e4SLinus Torvalds } 28774bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 28781da177e4SLinus Torvalds 287967edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 2880f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 28811da177e4SLinus Torvalds { 2882cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 28831da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 28841da177e4SLinus Torvalds __u8 rcv_wscale; 28851da177e4SLinus Torvalds 28861da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 28871da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 28881da177e4SLinus Torvalds */ 28891da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 2890bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 28911da177e4SLinus Torvalds 2892cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2893cfb6eeb4SYOSHIFUJI Hideaki if (tp->af_specific->md5_lookup(sk, sk) != NULL) 2894cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 2895cfb6eeb4SYOSHIFUJI Hideaki #endif 2896cfb6eeb4SYOSHIFUJI Hideaki 28971da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 28981da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 28991da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 29001da177e4SLinus Torvalds tp->max_window = 0; 29015d424d5aSJohn Heffner tcp_mtup_init(sk); 29021da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 29031da177e4SLinus Torvalds 29041da177e4SLinus Torvalds if (!tp->window_clamp) 29051da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 29060dbaee3bSDavid S. Miller tp->advmss = dst_metric_advmss(dst); 2907f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 2908f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 2909f5fff5dcSTom Quetchenbach 29101da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 29111da177e4SLinus Torvalds 2912e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 2913e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 2914e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 2915e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 2916e88c64f0SHagen Paul Pfeifer 29171da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 29181da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 29191da177e4SLinus Torvalds &tp->rcv_wnd, 29201da177e4SLinus Torvalds &tp->window_clamp, 2921bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 292231d12926Slaurent chavey &rcv_wscale, 292331d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 29241da177e4SLinus Torvalds 29251da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 29261da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 29271da177e4SLinus Torvalds 29281da177e4SLinus Torvalds sk->sk_err = 0; 29291da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 29301da177e4SLinus Torvalds tp->snd_wnd = 0; 2931ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 29321da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 29331da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 293433f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 2935370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 2936ee995283SPavel Emelyanov 2937ee995283SPavel Emelyanov if (likely(!tp->repair)) 29381da177e4SLinus Torvalds tp->rcv_nxt = 0; 2939c7781a6eSAndrew Vagin else 2940c7781a6eSAndrew Vagin tp->rcv_tstamp = tcp_time_stamp; 2941ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 2942ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 29431da177e4SLinus Torvalds 2944463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 2945463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 29461da177e4SLinus Torvalds tcp_clear_retrans(tp); 29471da177e4SLinus Torvalds } 29481da177e4SLinus Torvalds 2949783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 2950783237e8SYuchung Cheng { 2951783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 2952783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 2953783237e8SYuchung Cheng 2954783237e8SYuchung Cheng tcb->end_seq += skb->len; 2955f4a775d1SEric Dumazet __skb_header_release(skb); 2956783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 2957783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 2958783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 2959783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 2960783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 2961783237e8SYuchung Cheng } 2962783237e8SYuchung Cheng 2963783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 2964783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 2965783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 2966783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 2967783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 2968783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 2969783237e8SYuchung Cheng */ 2970783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 2971783237e8SYuchung Cheng { 2972783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 2973783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 2974aab48743SYuchung Cheng int syn_loss = 0, space, i, err = 0, iovlen = fo->data->msg_iovlen; 2975783237e8SYuchung Cheng struct sk_buff *syn_data = NULL, *data; 2976aab48743SYuchung Cheng unsigned long last_syn_loss = 0; 2977783237e8SYuchung Cheng 297867da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 2979aab48743SYuchung Cheng tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, 2980aab48743SYuchung Cheng &syn_loss, &last_syn_loss); 2981aab48743SYuchung Cheng /* Recurring FO SYN losses: revert to regular handshake temporarily */ 2982aab48743SYuchung Cheng if (syn_loss > 1 && 2983aab48743SYuchung Cheng time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { 2984aab48743SYuchung Cheng fo->cookie.len = -1; 2985aab48743SYuchung Cheng goto fallback; 2986aab48743SYuchung Cheng } 2987aab48743SYuchung Cheng 298867da22d2SYuchung Cheng if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) 298967da22d2SYuchung Cheng fo->cookie.len = -1; 299067da22d2SYuchung Cheng else if (fo->cookie.len <= 0) 2991783237e8SYuchung Cheng goto fallback; 2992783237e8SYuchung Cheng 2993783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 2994783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 2995783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 2996783237e8SYuchung Cheng */ 2997783237e8SYuchung Cheng if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) 2998783237e8SYuchung Cheng tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 29991b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3000783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3001783237e8SYuchung Cheng 3002f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3003f5ddcbbbSEric Dumazet 3004f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3005f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3006f5ddcbbbSEric Dumazet 3007f5ddcbbbSEric Dumazet syn_data = skb_copy_expand(syn, MAX_TCP_HEADER, space, 3008783237e8SYuchung Cheng sk->sk_allocation); 3009783237e8SYuchung Cheng if (syn_data == NULL) 3010783237e8SYuchung Cheng goto fallback; 3011783237e8SYuchung Cheng 3012783237e8SYuchung Cheng for (i = 0; i < iovlen && syn_data->len < space; ++i) { 3013783237e8SYuchung Cheng struct iovec *iov = &fo->data->msg_iov[i]; 3014783237e8SYuchung Cheng unsigned char __user *from = iov->iov_base; 3015783237e8SYuchung Cheng int len = iov->iov_len; 3016783237e8SYuchung Cheng 3017783237e8SYuchung Cheng if (syn_data->len + len > space) 3018783237e8SYuchung Cheng len = space - syn_data->len; 3019783237e8SYuchung Cheng else if (i + 1 == iovlen) 3020783237e8SYuchung Cheng /* No more data pending in inet_wait_for_connect() */ 3021783237e8SYuchung Cheng fo->data = NULL; 3022783237e8SYuchung Cheng 3023783237e8SYuchung Cheng if (skb_add_data(syn_data, from, len)) 3024783237e8SYuchung Cheng goto fallback; 3025783237e8SYuchung Cheng } 3026783237e8SYuchung Cheng 3027783237e8SYuchung Cheng /* Queue a data-only packet after the regular SYN for retransmission */ 3028783237e8SYuchung Cheng data = pskb_copy(syn_data, sk->sk_allocation); 3029783237e8SYuchung Cheng if (data == NULL) 3030783237e8SYuchung Cheng goto fallback; 3031783237e8SYuchung Cheng TCP_SKB_CB(data)->seq++; 3032783237e8SYuchung Cheng TCP_SKB_CB(data)->tcp_flags &= ~TCPHDR_SYN; 3033783237e8SYuchung Cheng TCP_SKB_CB(data)->tcp_flags = (TCPHDR_ACK|TCPHDR_PSH); 3034783237e8SYuchung Cheng tcp_connect_queue_skb(sk, data); 3035783237e8SYuchung Cheng fo->copied = data->len; 3036783237e8SYuchung Cheng 3037431a9124SEric Dumazet /* syn_data is about to be sent, we need to take current time stamps 3038431a9124SEric Dumazet * for the packets that are in write queue : SYN packet and DATA 3039431a9124SEric Dumazet */ 3040431a9124SEric Dumazet skb_mstamp_get(&syn->skb_mstamp); 3041431a9124SEric Dumazet data->skb_mstamp = syn->skb_mstamp; 3042431a9124SEric Dumazet 3043783237e8SYuchung Cheng if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) { 304467da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 3045f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3046783237e8SYuchung Cheng goto done; 3047783237e8SYuchung Cheng } 3048783237e8SYuchung Cheng syn_data = NULL; 3049783237e8SYuchung Cheng 3050783237e8SYuchung Cheng fallback: 3051783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3052783237e8SYuchung Cheng if (fo->cookie.len > 0) 3053783237e8SYuchung Cheng fo->cookie.len = 0; 3054783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3055783237e8SYuchung Cheng if (err) 3056783237e8SYuchung Cheng tp->syn_fastopen = 0; 3057783237e8SYuchung Cheng kfree_skb(syn_data); 3058783237e8SYuchung Cheng done: 3059783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3060783237e8SYuchung Cheng return err; 3061783237e8SYuchung Cheng } 3062783237e8SYuchung Cheng 306367edfef7SAndi Kleen /* Build a SYN and send it off. */ 30641da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 30651da177e4SLinus Torvalds { 30661da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 30671da177e4SLinus Torvalds struct sk_buff *buff; 3068ee586811SEric Paris int err; 30691da177e4SLinus Torvalds 30701da177e4SLinus Torvalds tcp_connect_init(sk); 30711da177e4SLinus Torvalds 30722b916477SAndrey Vagin if (unlikely(tp->repair)) { 30732b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 30742b916477SAndrey Vagin return 0; 30752b916477SAndrey Vagin } 30762b916477SAndrey Vagin 3077d179cd12SDavid S. Miller buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); 30781da177e4SLinus Torvalds if (unlikely(buff == NULL)) 30791da177e4SLinus Torvalds return -ENOBUFS; 30801da177e4SLinus Torvalds 30811da177e4SLinus Torvalds /* Reserve space for headers. */ 30821da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 30831da177e4SLinus Torvalds 3084a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 30857faee5c0SEric Dumazet tp->retrans_stamp = tcp_time_stamp; 3086783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3087e870a8efSIlpo Järvinen TCP_ECN_send_syn(sk, buff); 30881da177e4SLinus Torvalds 3089783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3090783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3091783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3092ee586811SEric Paris if (err == -ECONNREFUSED) 3093ee586811SEric Paris return err; 3094bd37a088SWei Yongjun 3095bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3096bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3097bd37a088SWei Yongjun */ 3098bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3099bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 310081cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 31011da177e4SLinus Torvalds 31021da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 31033f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 31043f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 31051da177e4SLinus Torvalds return 0; 31061da177e4SLinus Torvalds } 31074bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 31081da177e4SLinus Torvalds 31091da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 31101da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 31111da177e4SLinus Torvalds * for details. 31121da177e4SLinus Torvalds */ 31131da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 31141da177e4SLinus Torvalds { 3115463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3116463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 31171da177e4SLinus Torvalds unsigned long timeout; 31181da177e4SLinus Torvalds 31191da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3120463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 31211da177e4SLinus Torvalds int max_ato = HZ / 2; 31221da177e4SLinus Torvalds 3123056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3124056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 31251da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 31261da177e4SLinus Torvalds 31271da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 31281da177e4SLinus Torvalds 31291da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3130463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 31311da177e4SLinus Torvalds * directly. 31321da177e4SLinus Torvalds */ 3133740b0f18SEric Dumazet if (tp->srtt_us) { 3134740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3135740b0f18SEric Dumazet TCP_DELACK_MIN); 31361da177e4SLinus Torvalds 31371da177e4SLinus Torvalds if (rtt < max_ato) 31381da177e4SLinus Torvalds max_ato = rtt; 31391da177e4SLinus Torvalds } 31401da177e4SLinus Torvalds 31411da177e4SLinus Torvalds ato = min(ato, max_ato); 31421da177e4SLinus Torvalds } 31431da177e4SLinus Torvalds 31441da177e4SLinus Torvalds /* Stay within the limit we were given */ 31451da177e4SLinus Torvalds timeout = jiffies + ato; 31461da177e4SLinus Torvalds 31471da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3148463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 31491da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 31501da177e4SLinus Torvalds * send ACK now. 31511da177e4SLinus Torvalds */ 3152463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3153463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 31541da177e4SLinus Torvalds tcp_send_ack(sk); 31551da177e4SLinus Torvalds return; 31561da177e4SLinus Torvalds } 31571da177e4SLinus Torvalds 3158463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3159463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 31601da177e4SLinus Torvalds } 3161463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3162463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3163463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 31641da177e4SLinus Torvalds } 31651da177e4SLinus Torvalds 31661da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 31671da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 31681da177e4SLinus Torvalds { 31691da177e4SLinus Torvalds struct sk_buff *buff; 31701da177e4SLinus Torvalds 3171058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3172058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3173058dc334SIlpo Järvinen return; 3174058dc334SIlpo Järvinen 31751da177e4SLinus Torvalds /* We are not putting this on the write queue, so 31761da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 31771da177e4SLinus Torvalds * sock. 31781da177e4SLinus Torvalds */ 317999a1dec7SMel Gorman buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); 31801da177e4SLinus Torvalds if (buff == NULL) { 3181463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3182463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 31833f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 31843f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 31851da177e4SLinus Torvalds return; 31861da177e4SLinus Torvalds } 31871da177e4SLinus Torvalds 31881da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 31891da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3190a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 31911da177e4SLinus Torvalds 31921da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 31937faee5c0SEric Dumazet skb_mstamp_get(&buff->skb_mstamp); 319499a1dec7SMel Gorman tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); 31951da177e4SLinus Torvalds } 31961da177e4SLinus Torvalds 31971da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 31981da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 31991da177e4SLinus Torvalds * 32001da177e4SLinus Torvalds * Question: what should we make while urgent mode? 32011da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 32021da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 32031da177e4SLinus Torvalds * 32041da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 32051da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 32061da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 32071da177e4SLinus Torvalds */ 32081da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 32091da177e4SLinus Torvalds { 32101da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32111da177e4SLinus Torvalds struct sk_buff *skb; 32121da177e4SLinus Torvalds 32131da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 321499a1dec7SMel Gorman skb = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); 32151da177e4SLinus Torvalds if (skb == NULL) 32161da177e4SLinus Torvalds return -1; 32171da177e4SLinus Torvalds 32181da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 32191da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 32201da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 32211da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 32221da177e4SLinus Torvalds * send it. 32231da177e4SLinus Torvalds */ 3224a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 32257faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 3226dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); 32271da177e4SLinus Torvalds } 32281da177e4SLinus Torvalds 3229ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3230ee995283SPavel Emelyanov { 3231ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3232ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 3233ee995283SPavel Emelyanov tcp_xmit_probe_skb(sk, 0); 3234ee995283SPavel Emelyanov } 3235ee995283SPavel Emelyanov } 3236ee995283SPavel Emelyanov 323767edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 32381da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 32391da177e4SLinus Torvalds { 32401da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32411da177e4SLinus Torvalds struct sk_buff *skb; 32421da177e4SLinus Torvalds 3243058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3244058dc334SIlpo Järvinen return -1; 3245058dc334SIlpo Järvinen 3246fe067e8aSDavid S. Miller if ((skb = tcp_send_head(sk)) != NULL && 324790840defSIlpo Järvinen before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 32481da177e4SLinus Torvalds int err; 32490c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 325090840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 32511da177e4SLinus Torvalds 32521da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 32531da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 32541da177e4SLinus Torvalds 32551da177e4SLinus Torvalds /* We are probing the opening of a window 32561da177e4SLinus Torvalds * but the window size is != 0 32571da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 32581da177e4SLinus Torvalds */ 32591da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 32601da177e4SLinus Torvalds skb->len > mss) { 32611da177e4SLinus Torvalds seg_size = min(seg_size, mss); 32624de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 32636cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) 32641da177e4SLinus Torvalds return -1; 32651da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 3266846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 32671da177e4SLinus Torvalds 32684de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3269dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 327066f5fe62SIlpo Järvinen if (!err) 327166f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 32721da177e4SLinus Torvalds return err; 32731da177e4SLinus Torvalds } else { 327433f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 32754828e7f4SIlpo Järvinen tcp_xmit_probe_skb(sk, 1); 32761da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 32771da177e4SLinus Torvalds } 32781da177e4SLinus Torvalds } 32791da177e4SLinus Torvalds 32801da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 32811da177e4SLinus Torvalds * a partial packet else a zero probe. 32821da177e4SLinus Torvalds */ 32831da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 32841da177e4SLinus Torvalds { 3285463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 32861da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3287fcdd1cf4SEric Dumazet unsigned long probe_max; 32881da177e4SLinus Torvalds int err; 32891da177e4SLinus Torvalds 32901da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 32911da177e4SLinus Torvalds 3292fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 32931da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 32946687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3295463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 32961da177e4SLinus Torvalds return; 32971da177e4SLinus Torvalds } 32981da177e4SLinus Torvalds 32991da177e4SLinus Torvalds if (err <= 0) { 3300463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_backoff < sysctl_tcp_retries2) 3301463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 33026687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3303fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 33041da177e4SLinus Torvalds } else { 33051da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 33066687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 33071da177e4SLinus Torvalds * Let local senders to fight for local resources. 33081da177e4SLinus Torvalds * 33091da177e4SLinus Torvalds * Use accumulated backoff yet. 33101da177e4SLinus Torvalds */ 33116687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 33126687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3313fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 33141da177e4SLinus Torvalds } 3315fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 3316fcdd1cf4SEric Dumazet inet_csk_rto_backoff(icsk, probe_max), 3317fcdd1cf4SEric Dumazet TCP_RTO_MAX); 33181da177e4SLinus Torvalds } 33195db92c99SOctavian Purdila 33205db92c99SOctavian Purdila int tcp_rtx_synack(struct sock *sk, struct request_sock *req) 33215db92c99SOctavian Purdila { 33225db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 33235db92c99SOctavian Purdila struct flowi fl; 33245db92c99SOctavian Purdila int res; 33255db92c99SOctavian Purdila 33265db92c99SOctavian Purdila res = af_ops->send_synack(sk, NULL, &fl, req, 0, NULL); 33275db92c99SOctavian Purdila if (!res) { 33285db92c99SOctavian Purdila TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS); 33295db92c99SOctavian Purdila NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 33305db92c99SOctavian Purdila } 33315db92c99SOctavian Purdila return res; 33325db92c99SOctavian Purdila } 33335db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3334