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 } 896a5dc9e5SEric Dumazet } 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 921da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 931da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 941da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 951da177e4SLinus Torvalds * invalid. OK, let's make this for now: 961da177e4SLinus Torvalds */ 97cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 981da177e4SLinus Torvalds { 99cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1009e412ba7SIlpo Järvinen 10190840defSIlpo Järvinen if (!before(tcp_wnd_end(tp), tp->snd_nxt)) 1021da177e4SLinus Torvalds return tp->snd_nxt; 1031da177e4SLinus Torvalds else 10490840defSIlpo Järvinen return tcp_wnd_end(tp); 1051da177e4SLinus Torvalds } 1061da177e4SLinus Torvalds 1071da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1081da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1091da177e4SLinus Torvalds * 1101da177e4SLinus Torvalds * 1. It is independent of path mtu. 1111da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1121da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1131da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1141da177e4SLinus Torvalds * large MSS. 1151da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1161da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1171da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1181da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1191da177e4SLinus Torvalds * probably even Jumbo". 1201da177e4SLinus Torvalds */ 1211da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1221da177e4SLinus Torvalds { 1231da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 124cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1251da177e4SLinus Torvalds int mss = tp->advmss; 1261da177e4SLinus Torvalds 1270dbaee3bSDavid S. Miller if (dst) { 1280dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1290dbaee3bSDavid S. Miller 1300dbaee3bSDavid S. Miller if (metric < mss) { 1310dbaee3bSDavid S. Miller mss = metric; 1321da177e4SLinus Torvalds tp->advmss = mss; 1331da177e4SLinus Torvalds } 1340dbaee3bSDavid S. Miller } 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds return (__u16)mss; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 1391da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1401da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 141cf533ea5SEric Dumazet static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst) 1421da177e4SLinus Torvalds { 143463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1441da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1451da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1461da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1471da177e4SLinus Torvalds 1486687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1491da177e4SLinus Torvalds 1506687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1511da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1521da177e4SLinus Torvalds 153463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1541da177e4SLinus Torvalds cwnd >>= 1; 1551da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1561da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1571da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 16067edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 16140efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 162cf533ea5SEric Dumazet struct sock *sk) 1631da177e4SLinus Torvalds { 164463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 165463c84b9SArnaldo Carvalho de Melo const u32 now = tcp_time_stamp; 166bcefe17cSCong Wang const struct dst_entry *dst = __sk_dst_get(sk); 1671da177e4SLinus Torvalds 16835089bb2SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 16935089bb2SDavid S. Miller (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) 170463c84b9SArnaldo Carvalho de Melo tcp_cwnd_restart(sk, __sk_dst_get(sk)); 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds tp->lsndtime = now; 1731da177e4SLinus Torvalds 1741da177e4SLinus Torvalds /* If it is a reply for ato after last received 1751da177e4SLinus Torvalds * packet, enter pingpong mode. 1761da177e4SLinus Torvalds */ 177bcefe17cSCong Wang if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato && 178bcefe17cSCong Wang (!dst || !dst_metric(dst, RTAX_QUICKACK))) 179463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1801da177e4SLinus Torvalds } 1811da177e4SLinus Torvalds 18267edfef7SAndi Kleen /* Account for an ACK we sent. */ 18340efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1841da177e4SLinus Torvalds { 185463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 186463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1871da177e4SLinus Torvalds } 1881da177e4SLinus Torvalds 18985f16525SYuchung Cheng 19085f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 19185f16525SYuchung Cheng { 19285f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 1939ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 19485f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 19585f16525SYuchung Cheng * limit when mss is larger than 1460. 19685f16525SYuchung Cheng */ 19785f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 19885f16525SYuchung Cheng 19985f16525SYuchung Cheng if (mss > 1460) 20085f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 20185f16525SYuchung Cheng return init_rwnd; 20285f16525SYuchung Cheng } 20385f16525SYuchung Cheng 2041da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2051da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2061da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2071da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2081da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2091da177e4SLinus Torvalds * This MUST be enforced by all callers. 2101da177e4SLinus Torvalds */ 2111da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 2121da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 21331d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 21431d12926Slaurent chavey __u32 init_rcv_wnd) 2151da177e4SLinus Torvalds { 2161da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2191da177e4SLinus Torvalds if (*window_clamp == 0) 2201da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 2211da177e4SLinus Torvalds space = min(*window_clamp, space); 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2241da177e4SLinus Torvalds if (space > mss) 2251da177e4SLinus Torvalds space = (space / mss) * mss; 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22815d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22915d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 23015d99e02SRick Jones * we will truncate our initial window offering to 32K-1 23115d99e02SRick Jones * unless the remote has sent us a window scaling option, 23215d99e02SRick Jones * which we interpret as a sign the remote TCP is not 23315d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2341da177e4SLinus Torvalds */ 23515d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2361da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23715d99e02SRick Jones else 23815d99e02SRick Jones (*rcv_wnd) = space; 23915d99e02SRick Jones 2401da177e4SLinus Torvalds (*rcv_wscale) = 0; 2411da177e4SLinus Torvalds if (wscale_ok) { 2421da177e4SLinus Torvalds /* Set window scaling on max possible window 2431da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 2441da177e4SLinus Torvalds */ 2451da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 246316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 2471da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 2481da177e4SLinus Torvalds space >>= 1; 2491da177e4SLinus Torvalds (*rcv_wscale)++; 2501da177e4SLinus Torvalds } 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 25485f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 25585f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 256b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2601da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2611da177e4SLinus Torvalds } 2624bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2651da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2661da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2671da177e4SLinus Torvalds * frame. 2681da177e4SLinus Torvalds */ 26940efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2701da177e4SLinus Torvalds { 2711da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2721da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2731da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds /* Never shrink the offered window */ 2761da177e4SLinus Torvalds if (new_win < cur_win) { 2771da177e4SLinus Torvalds /* Danger Will Robinson! 2781da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2791da177e4SLinus Torvalds * we will not be able to advertise a zero 2801da177e4SLinus Torvalds * window in time. --DaveM 2811da177e4SLinus Torvalds * 2821da177e4SLinus Torvalds * Relax Will Robinson. 2831da177e4SLinus Torvalds */ 284607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2851da177e4SLinus Torvalds } 2861da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2871da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2881da177e4SLinus Torvalds 2891da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2901da177e4SLinus Torvalds * scaled window. 2911da177e4SLinus Torvalds */ 29215d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2931da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2941da177e4SLinus Torvalds else 2951da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2981da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 3011da177e4SLinus Torvalds if (new_win == 0) 3021da177e4SLinus Torvalds tp->pred_flags = 0; 3031da177e4SLinus Torvalds 3041da177e4SLinus Torvalds return new_win; 3051da177e4SLinus Torvalds } 3061da177e4SLinus Torvalds 30767edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 308cf533ea5SEric Dumazet static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb) 309bdf1ee5dSIlpo Järvinen { 3104de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 311bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3124de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 313bdf1ee5dSIlpo Järvinen } 314bdf1ee5dSIlpo Järvinen 31567edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 316bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) 317bdf1ee5dSIlpo Järvinen { 318bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 319bdf1ee5dSIlpo Järvinen 320bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 3215d134f1cSHannes Frederic Sowa if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1) { 3224de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 323bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 324bdf1ee5dSIlpo Järvinen } 325bdf1ee5dSIlpo Järvinen } 326bdf1ee5dSIlpo Järvinen 327bdf1ee5dSIlpo Järvinen static __inline__ void 328cf533ea5SEric Dumazet TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th) 329bdf1ee5dSIlpo Järvinen { 330bdf1ee5dSIlpo Järvinen if (inet_rsk(req)->ecn_ok) 331bdf1ee5dSIlpo Järvinen th->ece = 1; 332bdf1ee5dSIlpo Järvinen } 333bdf1ee5dSIlpo Järvinen 33467edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 33567edfef7SAndi Kleen * be sent. 33667edfef7SAndi Kleen */ 337bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, 338bdf1ee5dSIlpo Järvinen int tcp_header_len) 339bdf1ee5dSIlpo Järvinen { 340bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 341bdf1ee5dSIlpo Järvinen 342bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 343bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 344bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 345bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 346bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 347bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 348bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 349bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->cwr = 1; 350bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 351bdf1ee5dSIlpo Järvinen } 352bdf1ee5dSIlpo Järvinen } else { 353bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 354bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 355bdf1ee5dSIlpo Järvinen } 356bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 357bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->ece = 1; 358bdf1ee5dSIlpo Järvinen } 359bdf1ee5dSIlpo Järvinen } 360bdf1ee5dSIlpo Järvinen 361e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 362e870a8efSIlpo Järvinen * auto increment end seqno. 363e870a8efSIlpo Järvinen */ 364e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 365e870a8efSIlpo Järvinen { 3662e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 367e870a8efSIlpo Järvinen skb->csum = 0; 368e870a8efSIlpo Järvinen 3694de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 370e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 371e870a8efSIlpo Järvinen 372e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_segs = 1; 373e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_size = 0; 374e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_type = 0; 375e870a8efSIlpo Järvinen 376e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 377a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 378e870a8efSIlpo Järvinen seq++; 379e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 380e870a8efSIlpo Järvinen } 381e870a8efSIlpo Järvinen 382a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 38333f5f57eSIlpo Järvinen { 38433f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 38533f5f57eSIlpo Järvinen } 38633f5f57eSIlpo Järvinen 38733ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 38833ad798cSAdam Langley #define OPTION_TS (1 << 1) 38933ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 39089e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 3912100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 39233ad798cSAdam Langley 39333ad798cSAdam Langley struct tcp_out_options { 3942100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 3952100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 39633ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 39733ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 398bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 399bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4002100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4012100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 40233ad798cSAdam Langley }; 40333ad798cSAdam Langley 40467edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 40567edfef7SAndi Kleen * 40667edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 407fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 408fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 409fd6149d3SIlpo Järvinen * inter-operatibility perspective it seems that we're somewhat stuck with 410fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 411fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 412fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 413fd6149d3SIlpo Järvinen * 414fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 415fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 416fd6149d3SIlpo Järvinen */ 41733ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 418bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 419bd0388aeSWilliam Allen Simpson { 4202100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 421bd0388aeSWilliam Allen Simpson 422bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4231a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4241a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 425bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 426bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 42733ad798cSAdam Langley ptr += 4; 42833ad798cSAdam Langley } 42933ad798cSAdam Langley 430fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 431fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 432fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 433fd6149d3SIlpo Järvinen opts->mss); 434fd6149d3SIlpo Järvinen } 435fd6149d3SIlpo Järvinen 436bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 437bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 43833ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 43933ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 44033ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 44133ad798cSAdam Langley TCPOLEN_TIMESTAMP); 442bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 44333ad798cSAdam Langley } else { 444496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 44540efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 44640efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 44740efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 44840efc6faSStephen Hemminger } 44933ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 45033ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 45133ad798cSAdam Langley } 45233ad798cSAdam Langley 453bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 45433ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 45533ad798cSAdam Langley (TCPOPT_NOP << 16) | 45633ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 45733ad798cSAdam Langley TCPOLEN_SACK_PERM); 45833ad798cSAdam Langley } 45933ad798cSAdam Langley 460bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 46133ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 46233ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 46333ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 46433ad798cSAdam Langley opts->ws); 46533ad798cSAdam Langley } 46633ad798cSAdam Langley 46733ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 46833ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 46933ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 47040efc6faSStephen Hemminger int this_sack; 47140efc6faSStephen Hemminger 47240efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 47340efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 47440efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 47533ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 47640efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 4772de979bdSStephen Hemminger 47833ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 47933ad798cSAdam Langley ++this_sack) { 48040efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 48140efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 48240efc6faSStephen Hemminger } 4832de979bdSStephen Hemminger 48440efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 48540efc6faSStephen Hemminger } 4862100c8d2SYuchung Cheng 4872100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 4882100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 4892100c8d2SYuchung Cheng 4902100c8d2SYuchung Cheng *ptr++ = htonl((TCPOPT_EXP << 24) | 4912100c8d2SYuchung Cheng ((TCPOLEN_EXP_FASTOPEN_BASE + foc->len) << 16) | 4922100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 4932100c8d2SYuchung Cheng 4942100c8d2SYuchung Cheng memcpy(ptr, foc->val, foc->len); 4952100c8d2SYuchung Cheng if ((foc->len & 3) == 2) { 4962100c8d2SYuchung Cheng u8 *align = ((u8 *)ptr) + foc->len; 4972100c8d2SYuchung Cheng align[0] = align[1] = TCPOPT_NOP; 4982100c8d2SYuchung Cheng } 4992100c8d2SYuchung Cheng ptr += (foc->len + 3) >> 2; 5002100c8d2SYuchung Cheng } 50140efc6faSStephen Hemminger } 50240efc6faSStephen Hemminger 50367edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 50467edfef7SAndi Kleen * network wire format yet. 50567edfef7SAndi Kleen */ 50695c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 50733ad798cSAdam Langley struct tcp_out_options *opts, 508cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 509cf533ea5SEric Dumazet { 51033ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 51195c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 512783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 51333ad798cSAdam Langley 514cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 51533ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 51633ad798cSAdam Langley if (*md5) { 51733ad798cSAdam Langley opts->options |= OPTION_MD5; 518bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 519cfb6eeb4SYOSHIFUJI Hideaki } 52033ad798cSAdam Langley #else 52133ad798cSAdam Langley *md5 = NULL; 522cfb6eeb4SYOSHIFUJI Hideaki #endif 52333ad798cSAdam Langley 52433ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 52533ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 52633ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 52733ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 52833ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 52933ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 53033ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 53133ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 53233ad798cSAdam Langley * going out. */ 53333ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 534bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 53533ad798cSAdam Langley 536bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { 53733ad798cSAdam Langley opts->options |= OPTION_TS; 538ee684b6fSAndrey Vagin opts->tsval = TCP_SKB_CB(skb)->when + tp->tsoffset; 53933ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 540bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 54133ad798cSAdam Langley } 542bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_window_scaling)) { 54333ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 54489e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 545bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 54633ad798cSAdam Langley } 547bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_sack)) { 54833ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 549b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 550bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 55133ad798cSAdam Langley } 55233ad798cSAdam Langley 553783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 554783237e8SYuchung Cheng u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len; 555783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 556783237e8SYuchung Cheng if (remaining >= need) { 557783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 558783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 559783237e8SYuchung Cheng remaining -= need; 560783237e8SYuchung Cheng tp->syn_fastopen = 1; 561783237e8SYuchung Cheng } 562783237e8SYuchung Cheng } 563bd0388aeSWilliam Allen Simpson 564bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 56533ad798cSAdam Langley } 56633ad798cSAdam Langley 56767edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 56895c96174SEric Dumazet static unsigned int tcp_synack_options(struct sock *sk, 56933ad798cSAdam Langley struct request_sock *req, 57095c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 57133ad798cSAdam Langley struct tcp_out_options *opts, 5724957faadSWilliam Allen Simpson struct tcp_md5sig_key **md5, 5738336886fSJerry Chu struct tcp_fastopen_cookie *foc) 5744957faadSWilliam Allen Simpson { 57533ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 57695c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 57733ad798cSAdam Langley 57833ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 57933ad798cSAdam Langley *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); 58033ad798cSAdam Langley if (*md5) { 58133ad798cSAdam Langley opts->options |= OPTION_MD5; 5824957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 5834957faadSWilliam Allen Simpson 5844957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 5854957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 5864957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 5874957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 5884957faadSWilliam Allen Simpson */ 589de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 59033ad798cSAdam Langley } 59133ad798cSAdam Langley #else 59233ad798cSAdam Langley *md5 = NULL; 59333ad798cSAdam Langley #endif 59433ad798cSAdam Langley 5954957faadSWilliam Allen Simpson /* We always send an MSS option. */ 59633ad798cSAdam Langley opts->mss = mss; 5974957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 59833ad798cSAdam Langley 59933ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 60033ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 60189e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6024957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 60333ad798cSAdam Langley } 604de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 60533ad798cSAdam Langley opts->options |= OPTION_TS; 60633ad798cSAdam Langley opts->tsval = TCP_SKB_CB(skb)->when; 60733ad798cSAdam Langley opts->tsecr = req->ts_recent; 6084957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 60933ad798cSAdam Langley } 61033ad798cSAdam Langley if (likely(ireq->sack_ok)) { 61133ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 612de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 6134957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 61433ad798cSAdam Langley } 6158336886fSJerry Chu if (foc != NULL) { 6168336886fSJerry Chu u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 6178336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 6188336886fSJerry Chu if (remaining >= need) { 6198336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 6208336886fSJerry Chu opts->fastopen_cookie = foc; 6218336886fSJerry Chu remaining -= need; 6228336886fSJerry Chu } 6238336886fSJerry Chu } 6244957faadSWilliam Allen Simpson 6254957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 62633ad798cSAdam Langley } 62733ad798cSAdam Langley 62867edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 62967edfef7SAndi Kleen * final wire format yet. 63067edfef7SAndi Kleen */ 63195c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 63233ad798cSAdam Langley struct tcp_out_options *opts, 633cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 634cf533ea5SEric Dumazet { 63533ad798cSAdam Langley struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; 63633ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 63795c96174SEric Dumazet unsigned int size = 0; 638cabeccbdSIlpo Järvinen unsigned int eff_sacks; 63933ad798cSAdam Langley 640*5843ef42SAndi Kleen opts->options = 0; 641*5843ef42SAndi Kleen 64233ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 64333ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 64433ad798cSAdam Langley if (unlikely(*md5)) { 64533ad798cSAdam Langley opts->options |= OPTION_MD5; 64633ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 64733ad798cSAdam Langley } 64833ad798cSAdam Langley #else 64933ad798cSAdam Langley *md5 = NULL; 65033ad798cSAdam Langley #endif 65133ad798cSAdam Langley 65233ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 65333ad798cSAdam Langley opts->options |= OPTION_TS; 654ee684b6fSAndrey Vagin opts->tsval = tcb ? tcb->when + tp->tsoffset : 0; 65533ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 65633ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 65733ad798cSAdam Langley } 65833ad798cSAdam Langley 659cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 660cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 66195c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 66233ad798cSAdam Langley opts->num_sack_blocks = 66395c96174SEric Dumazet min_t(unsigned int, eff_sacks, 66433ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 66533ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 66633ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 66733ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 66833ad798cSAdam Langley } 66933ad798cSAdam Langley 67033ad798cSAdam Langley return size; 67140efc6faSStephen Hemminger } 6721da177e4SLinus Torvalds 67346d3ceabSEric Dumazet 67446d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 67546d3ceabSEric Dumazet * 67646d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 67746d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 67846d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 67946d3ceabSEric Dumazet * 68046d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 68146d3ceabSEric Dumazet * needs to be reallocated in a driver. 68246d3ceabSEric Dumazet * The invariant being skb->truesize substracted from sk->sk_wmem_alloc 68346d3ceabSEric Dumazet * 68446d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 68546d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 68646d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 68746d3ceabSEric Dumazet */ 68846d3ceabSEric Dumazet struct tsq_tasklet { 68946d3ceabSEric Dumazet struct tasklet_struct tasklet; 69046d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 69146d3ceabSEric Dumazet }; 69246d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 69346d3ceabSEric Dumazet 6946f458dfbSEric Dumazet static void tcp_tsq_handler(struct sock *sk) 6956f458dfbSEric Dumazet { 6966f458dfbSEric Dumazet if ((1 << sk->sk_state) & 6976f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 6986f458dfbSEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) 6996f458dfbSEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), 0, 0, GFP_ATOMIC); 7006f458dfbSEric Dumazet } 70146d3ceabSEric Dumazet /* 70246d3ceabSEric Dumazet * One tasklest per cpu tries to send more skbs. 70346d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 70446d3ceabSEric Dumazet * transfering tsq->head because tcp_wfree() might 70546d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 70646d3ceabSEric Dumazet */ 70746d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 70846d3ceabSEric Dumazet { 70946d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 71046d3ceabSEric Dumazet LIST_HEAD(list); 71146d3ceabSEric Dumazet unsigned long flags; 71246d3ceabSEric Dumazet struct list_head *q, *n; 71346d3ceabSEric Dumazet struct tcp_sock *tp; 71446d3ceabSEric Dumazet struct sock *sk; 71546d3ceabSEric Dumazet 71646d3ceabSEric Dumazet local_irq_save(flags); 71746d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 71846d3ceabSEric Dumazet local_irq_restore(flags); 71946d3ceabSEric Dumazet 72046d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 72146d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 72246d3ceabSEric Dumazet list_del(&tp->tsq_node); 72346d3ceabSEric Dumazet 72446d3ceabSEric Dumazet sk = (struct sock *)tp; 72546d3ceabSEric Dumazet bh_lock_sock(sk); 72646d3ceabSEric Dumazet 72746d3ceabSEric Dumazet if (!sock_owned_by_user(sk)) { 7286f458dfbSEric Dumazet tcp_tsq_handler(sk); 72946d3ceabSEric Dumazet } else { 73046d3ceabSEric Dumazet /* defer the work to tcp_release_cb() */ 7316f458dfbSEric Dumazet set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); 73246d3ceabSEric Dumazet } 73346d3ceabSEric Dumazet bh_unlock_sock(sk); 73446d3ceabSEric Dumazet 73546d3ceabSEric Dumazet clear_bit(TSQ_QUEUED, &tp->tsq_flags); 73646d3ceabSEric Dumazet sk_free(sk); 73746d3ceabSEric Dumazet } 73846d3ceabSEric Dumazet } 73946d3ceabSEric Dumazet 7406f458dfbSEric Dumazet #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ 7416f458dfbSEric Dumazet (1UL << TCP_WRITE_TIMER_DEFERRED) | \ 742563d34d0SEric Dumazet (1UL << TCP_DELACK_TIMER_DEFERRED) | \ 743563d34d0SEric Dumazet (1UL << TCP_MTU_REDUCED_DEFERRED)) 74446d3ceabSEric Dumazet /** 74546d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 74646d3ceabSEric Dumazet * @sk: socket 74746d3ceabSEric Dumazet * 74846d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 74946d3ceabSEric Dumazet * actions before socket release. 75046d3ceabSEric Dumazet */ 75146d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 75246d3ceabSEric Dumazet { 75346d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 7546f458dfbSEric Dumazet unsigned long flags, nflags; 75546d3ceabSEric Dumazet 7566f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 7576f458dfbSEric Dumazet do { 7586f458dfbSEric Dumazet flags = tp->tsq_flags; 7596f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 7606f458dfbSEric Dumazet return; 7616f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 7626f458dfbSEric Dumazet } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); 7636f458dfbSEric Dumazet 7646f458dfbSEric Dumazet if (flags & (1UL << TCP_TSQ_DEFERRED)) 7656f458dfbSEric Dumazet tcp_tsq_handler(sk); 7666f458dfbSEric Dumazet 767144d56e9SEric Dumazet if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { 7686f458dfbSEric Dumazet tcp_write_timer_handler(sk); 769144d56e9SEric Dumazet __sock_put(sk); 770144d56e9SEric Dumazet } 771144d56e9SEric Dumazet if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { 7726f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 773144d56e9SEric Dumazet __sock_put(sk); 774144d56e9SEric Dumazet } 775144d56e9SEric Dumazet if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { 776563d34d0SEric Dumazet sk->sk_prot->mtu_reduced(sk); 777144d56e9SEric Dumazet __sock_put(sk); 778144d56e9SEric Dumazet } 77946d3ceabSEric Dumazet } 78046d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 78146d3ceabSEric Dumazet 78246d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 78346d3ceabSEric Dumazet { 78446d3ceabSEric Dumazet int i; 78546d3ceabSEric Dumazet 78646d3ceabSEric Dumazet for_each_possible_cpu(i) { 78746d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 78846d3ceabSEric Dumazet 78946d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 79046d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 79146d3ceabSEric Dumazet tcp_tasklet_func, 79246d3ceabSEric Dumazet (unsigned long)tsq); 79346d3ceabSEric Dumazet } 79446d3ceabSEric Dumazet } 79546d3ceabSEric Dumazet 79646d3ceabSEric Dumazet /* 79746d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 79846d3ceabSEric Dumazet * We cant xmit new skbs from this context, as we might already 79946d3ceabSEric Dumazet * hold qdisc lock. 80046d3ceabSEric Dumazet */ 801d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 80246d3ceabSEric Dumazet { 80346d3ceabSEric Dumazet struct sock *sk = skb->sk; 80446d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 80546d3ceabSEric Dumazet 80646d3ceabSEric Dumazet if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && 80746d3ceabSEric Dumazet !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { 80846d3ceabSEric Dumazet unsigned long flags; 80946d3ceabSEric Dumazet struct tsq_tasklet *tsq; 81046d3ceabSEric Dumazet 81146d3ceabSEric Dumazet /* Keep a ref on socket. 81246d3ceabSEric Dumazet * This last ref will be released in tcp_tasklet_func() 81346d3ceabSEric Dumazet */ 81446d3ceabSEric Dumazet atomic_sub(skb->truesize - 1, &sk->sk_wmem_alloc); 81546d3ceabSEric Dumazet 81646d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 81746d3ceabSEric Dumazet local_irq_save(flags); 81846d3ceabSEric Dumazet tsq = &__get_cpu_var(tsq_tasklet); 81946d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 82046d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 82146d3ceabSEric Dumazet local_irq_restore(flags); 82246d3ceabSEric Dumazet } else { 82346d3ceabSEric Dumazet sock_wfree(skb); 82446d3ceabSEric Dumazet } 82546d3ceabSEric Dumazet } 82646d3ceabSEric Dumazet 8271da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 8281da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 8291da177e4SLinus Torvalds * transmission and possible later retransmissions. 8301da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 8311da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 8321da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 8331da177e4SLinus Torvalds * device. 8341da177e4SLinus Torvalds * 8351da177e4SLinus Torvalds * We are working here with either a clone of the original 8361da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 8371da177e4SLinus Torvalds */ 838056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 839056834d9SIlpo Järvinen gfp_t gfp_mask) 8401da177e4SLinus Torvalds { 8416687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 842dfb4b9dcSDavid S. Miller struct inet_sock *inet; 843dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 844dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 84533ad798cSAdam Langley struct tcp_out_options opts; 84695c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 847cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 8481da177e4SLinus Torvalds struct tcphdr *th; 8491da177e4SLinus Torvalds int err; 8501da177e4SLinus Torvalds 851dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 852dfb4b9dcSDavid S. Miller 853dfb4b9dcSDavid S. Miller /* If congestion control is doing timestamping, we must 854dfb4b9dcSDavid S. Miller * take such a timestamp before we potentially clone/copy. 855dfb4b9dcSDavid S. Miller */ 856164891aaSStephen Hemminger if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) 857dfb4b9dcSDavid S. Miller __net_timestamp(skb); 858dfb4b9dcSDavid S. Miller 859dfb4b9dcSDavid S. Miller if (likely(clone_it)) { 8600e280af0SEric Dumazet const struct sk_buff *fclone = skb + 1; 8610e280af0SEric Dumazet 8620e280af0SEric Dumazet if (unlikely(skb->fclone == SKB_FCLONE_ORIG && 8630e280af0SEric Dumazet fclone->fclone == SKB_FCLONE_CLONE)) 8640e280af0SEric Dumazet NET_INC_STATS_BH(sock_net(sk), 8650e280af0SEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 8660e280af0SEric Dumazet 867dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 868dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 869dfb4b9dcSDavid S. Miller else 870dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 871dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 872dfb4b9dcSDavid S. Miller return -ENOBUFS; 873dfb4b9dcSDavid S. Miller } 874dfb4b9dcSDavid S. Miller 875dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 876dfb4b9dcSDavid S. Miller tp = tcp_sk(sk); 877dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 87833ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 8791da177e4SLinus Torvalds 8804de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 88133ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 88233ad798cSAdam Langley else 88333ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 88433ad798cSAdam Langley &md5); 88533ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 8861da177e4SLinus Torvalds 887547669d4SEric Dumazet if (tcp_packets_in_flight(tp) == 0) 8886687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_TX_START); 889547669d4SEric Dumazet 890547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 891547669d4SEric Dumazet * another queue. 892547669d4SEric Dumazet */ 893547669d4SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) == 0; 8941da177e4SLinus Torvalds 895aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 896aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 89746d3ceabSEric Dumazet 89846d3ceabSEric Dumazet skb_orphan(skb); 89946d3ceabSEric Dumazet skb->sk = sk; 900c9eeec26SEric Dumazet skb->destructor = tcp_wfree; 90146d3ceabSEric Dumazet atomic_add(skb->truesize, &sk->sk_wmem_alloc); 9021da177e4SLinus Torvalds 9031da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 904aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 905c720c7e8SEric Dumazet th->source = inet->inet_sport; 906c720c7e8SEric Dumazet th->dest = inet->inet_dport; 9071da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 9081da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 909df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 9104de075e0SEric Dumazet tcb->tcp_flags); 911dfb4b9dcSDavid S. Miller 9124de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 9131da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 9141da177e4SLinus Torvalds * is never scaled. 9151da177e4SLinus Torvalds */ 916600ff0c2SIlpo Järvinen th->window = htons(min(tp->rcv_wnd, 65535U)); 9171da177e4SLinus Torvalds } else { 9181da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 9191da177e4SLinus Torvalds } 9201da177e4SLinus Torvalds th->check = 0; 9211da177e4SLinus Torvalds th->urg_ptr = 0; 9221da177e4SLinus Torvalds 92333f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 9247691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 9257691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 9261da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 9271da177e4SLinus Torvalds th->urg = 1; 9287691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 9290eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 9307691367dSHerbert Xu th->urg = 1; 9317691367dSHerbert Xu } 9321da177e4SLinus Torvalds } 9331da177e4SLinus Torvalds 934bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 9354de075e0SEric Dumazet if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) 9369e412ba7SIlpo Järvinen TCP_ECN_send(sk, skb, tcp_header_size); 937dfb4b9dcSDavid S. Miller 938cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 939cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 940cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 941a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 942bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 94349a72dfbSAdam Langley md5, sk, NULL, skb); 944cfb6eeb4SYOSHIFUJI Hideaki } 945cfb6eeb4SYOSHIFUJI Hideaki #endif 946cfb6eeb4SYOSHIFUJI Hideaki 947bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 9481da177e4SLinus Torvalds 9494de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 950fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 9511da177e4SLinus Torvalds 9521da177e4SLinus Torvalds if (skb->len != tcp_header_size) 953cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 9541da177e4SLinus Torvalds 955bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 956aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 957aa2ea058STom Herbert tcp_skb_pcount(skb)); 9581da177e4SLinus Torvalds 959d9d8da80SDavid S. Miller err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl); 96083de47cdSHua Zhong if (likely(err <= 0)) 9611da177e4SLinus Torvalds return err; 9621da177e4SLinus Torvalds 9633cfe3baaSIlpo Järvinen tcp_enter_cwr(sk, 1); 9641da177e4SLinus Torvalds 965b9df3cb8SGerrit Renker return net_xmit_eval(err); 9661da177e4SLinus Torvalds } 9671da177e4SLinus Torvalds 96867edfef7SAndi Kleen /* This routine just queues the buffer for sending. 9691da177e4SLinus Torvalds * 9701da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 9711da177e4SLinus Torvalds * otherwise socket can stall. 9721da177e4SLinus Torvalds */ 9731da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 9741da177e4SLinus Torvalds { 9751da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 9761da177e4SLinus Torvalds 9771da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 9781da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 9791da177e4SLinus Torvalds skb_header_release(skb); 980fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 9813ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 9823ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 9831da177e4SLinus Torvalds } 9841da177e4SLinus Torvalds 98567edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 986cf533ea5SEric Dumazet static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, 987056834d9SIlpo Järvinen unsigned int mss_now) 988f6302d1dSDavid S. Miller { 9898e5b9ddaSHerbert Xu if (skb->len <= mss_now || !sk_can_gso(sk) || 9908e5b9ddaSHerbert Xu skb->ip_summed == CHECKSUM_NONE) { 991f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 992f6302d1dSDavid S. Miller * non-TSO case. 993f6302d1dSDavid S. Miller */ 9947967168cSHerbert Xu skb_shinfo(skb)->gso_segs = 1; 9957967168cSHerbert Xu skb_shinfo(skb)->gso_size = 0; 996c9af6db4SPravin B Shelar skb_shinfo(skb)->gso_type = 0; 997f6302d1dSDavid S. Miller } else { 998356f89e1SIlpo Järvinen skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now); 9997967168cSHerbert Xu skb_shinfo(skb)->gso_size = mss_now; 1000c9af6db4SPravin B Shelar skb_shinfo(skb)->gso_type = sk->sk_gso_type; 10011da177e4SLinus Torvalds } 10021da177e4SLinus Torvalds } 10031da177e4SLinus Torvalds 100491fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 100568f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 100691fed7a1SIlpo Järvinen */ 1007cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 100891fed7a1SIlpo Järvinen int decr) 100991fed7a1SIlpo Järvinen { 1010a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1011a47e5a98SIlpo Järvinen 1012dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 101391fed7a1SIlpo Järvinen return; 101491fed7a1SIlpo Järvinen 10156859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 101691fed7a1SIlpo Järvinen tp->fackets_out -= decr; 101791fed7a1SIlpo Järvinen } 101891fed7a1SIlpo Järvinen 1019797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1020797108d1SIlpo Järvinen * tweaks to fix counters 1021797108d1SIlpo Järvinen */ 1022cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1023797108d1SIlpo Järvinen { 1024797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1025797108d1SIlpo Järvinen 1026797108d1SIlpo Järvinen tp->packets_out -= decr; 1027797108d1SIlpo Järvinen 1028797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1029797108d1SIlpo Järvinen tp->sacked_out -= decr; 1030797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1031797108d1SIlpo Järvinen tp->retrans_out -= decr; 1032797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1033797108d1SIlpo Järvinen tp->lost_out -= decr; 1034797108d1SIlpo Järvinen 1035797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1036797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1037797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1038797108d1SIlpo Järvinen 1039797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1040797108d1SIlpo Järvinen 1041797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1042797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 104352cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1044797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1045797108d1SIlpo Järvinen 1046797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1047797108d1SIlpo Järvinen } 1048797108d1SIlpo Järvinen 10491da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 10501da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 10511da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 10521da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 10531da177e4SLinus Torvalds */ 1054056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 1055056834d9SIlpo Järvinen unsigned int mss_now) 10561da177e4SLinus Torvalds { 10571da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10581da177e4SLinus Torvalds struct sk_buff *buff; 10596475be16SDavid S. Miller int nsize, old_factor; 1060b60b49eaSHerbert Xu int nlen; 10619ce01461SIlpo Järvinen u8 flags; 10621da177e4SLinus Torvalds 10632fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 10642fceec13SIlpo Järvinen return -EINVAL; 10656a438bbeSStephen Hemminger 10661da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 10671da177e4SLinus Torvalds if (nsize < 0) 10681da177e4SLinus Torvalds nsize = 0; 10691da177e4SLinus Torvalds 10701da177e4SLinus Torvalds if (skb_cloned(skb) && 10711da177e4SLinus Torvalds skb_is_nonlinear(skb) && 10721da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 10731da177e4SLinus Torvalds return -ENOMEM; 10741da177e4SLinus Torvalds 10751da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 10761da177e4SLinus Torvalds buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); 10771da177e4SLinus Torvalds if (buff == NULL) 10781da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1079ef5cb973SHerbert Xu 10803ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 10813ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1082b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1083b60b49eaSHerbert Xu buff->truesize += nlen; 1084b60b49eaSHerbert Xu skb->truesize -= nlen; 10851da177e4SLinus Torvalds 10861da177e4SLinus Torvalds /* Correct the sequence numbers. */ 10871da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 10881da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 10891da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 10901da177e4SLinus Torvalds 10911da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 10924de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 10934de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 10944de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1095e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 10961da177e4SLinus Torvalds 109784fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 10981da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1099056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1100056834d9SIlpo Järvinen skb_put(buff, nsize), 11011da177e4SLinus Torvalds nsize, 0); 11021da177e4SLinus Torvalds 11031da177e4SLinus Torvalds skb_trim(skb, len); 11041da177e4SLinus Torvalds 11051da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 11061da177e4SLinus Torvalds } else { 110784fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 11081da177e4SLinus Torvalds skb_split(skb, buff, len); 11091da177e4SLinus Torvalds } 11101da177e4SLinus Torvalds 11111da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 11121da177e4SLinus Torvalds 11131da177e4SLinus Torvalds /* Looks stupid, but our code really uses when of 11141da177e4SLinus Torvalds * skbs, which it never sent before. --ANK 11151da177e4SLinus Torvalds */ 11161da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; 1117a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 11181da177e4SLinus Torvalds 11196475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 11206475be16SDavid S. Miller 11211da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 1122846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1123846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 11241da177e4SLinus Torvalds 11256475be16SDavid S. Miller /* If this packet has been sent out already, we must 11266475be16SDavid S. Miller * adjust the various packet counters. 11276475be16SDavid S. Miller */ 1128cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 11296475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 11306475be16SDavid S. Miller tcp_skb_pcount(buff); 11311da177e4SLinus Torvalds 1132797108d1SIlpo Järvinen if (diff) 1133797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 11341da177e4SLinus Torvalds } 11351da177e4SLinus Torvalds 11361da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1137f44b5271SDavid S. Miller skb_header_release(buff); 1138fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 11391da177e4SLinus Torvalds 11401da177e4SLinus Torvalds return 0; 11411da177e4SLinus Torvalds } 11421da177e4SLinus Torvalds 11431da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 11441da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 11451da177e4SLinus Torvalds * immediately discarded. 11461da177e4SLinus Torvalds */ 1147f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 11481da177e4SLinus Torvalds { 11491da177e4SLinus Torvalds int i, k, eat; 11501da177e4SLinus Torvalds 11514fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 11524fa48bf3SEric Dumazet if (eat) { 11534fa48bf3SEric Dumazet __skb_pull(skb, eat); 11544fa48bf3SEric Dumazet len -= eat; 11554fa48bf3SEric Dumazet if (!len) 11564fa48bf3SEric Dumazet return; 11574fa48bf3SEric Dumazet } 11581da177e4SLinus Torvalds eat = len; 11591da177e4SLinus Torvalds k = 0; 11601da177e4SLinus Torvalds for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 11619e903e08SEric Dumazet int size = skb_frag_size(&skb_shinfo(skb)->frags[i]); 11629e903e08SEric Dumazet 11639e903e08SEric Dumazet if (size <= eat) { 1164aff65da0SIan Campbell skb_frag_unref(skb, i); 11659e903e08SEric Dumazet eat -= size; 11661da177e4SLinus Torvalds } else { 11671da177e4SLinus Torvalds skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 11681da177e4SLinus Torvalds if (eat) { 11691da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].page_offset += eat; 11709e903e08SEric Dumazet skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat); 11711da177e4SLinus Torvalds eat = 0; 11721da177e4SLinus Torvalds } 11731da177e4SLinus Torvalds k++; 11741da177e4SLinus Torvalds } 11751da177e4SLinus Torvalds } 11761da177e4SLinus Torvalds skb_shinfo(skb)->nr_frags = k; 11771da177e4SLinus Torvalds 117827a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 11791da177e4SLinus Torvalds skb->data_len -= len; 11801da177e4SLinus Torvalds skb->len = skb->data_len; 11811da177e4SLinus Torvalds } 11821da177e4SLinus Torvalds 118367edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 11841da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 11851da177e4SLinus Torvalds { 118614bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 11871da177e4SLinus Torvalds return -ENOMEM; 11881da177e4SLinus Torvalds 11894fa48bf3SEric Dumazet __pskb_trim_head(skb, len); 11901da177e4SLinus Torvalds 11911da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 119284fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 11931da177e4SLinus Torvalds 11941da177e4SLinus Torvalds skb->truesize -= len; 11951da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 11963ab224beSHideo Aoki sk_mem_uncharge(sk, len); 11971da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 11981da177e4SLinus Torvalds 11995b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 12001da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 12015b35e1e6SNeal Cardwell tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds return 0; 12041da177e4SLinus Torvalds } 12051da177e4SLinus Torvalds 12061b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 12071b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 12085d424d5aSJohn Heffner { 1209cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1210cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 12115d424d5aSJohn Heffner int mss_now; 12125d424d5aSJohn Heffner 12135d424d5aSJohn Heffner /* Calculate base mss without TCP options: 12145d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 12155d424d5aSJohn Heffner */ 12165d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 12175d424d5aSJohn Heffner 121867469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 121967469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 122067469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 122167469601SEric Dumazet 122267469601SEric Dumazet if (dst && dst_allfrag(dst)) 122367469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 122467469601SEric Dumazet } 122567469601SEric Dumazet 12265d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 12275d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 12285d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 12295d424d5aSJohn Heffner 12305d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 12315d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 12325d424d5aSJohn Heffner 12335d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 12345d424d5aSJohn Heffner if (mss_now < 48) 12355d424d5aSJohn Heffner mss_now = 48; 12365d424d5aSJohn Heffner return mss_now; 12375d424d5aSJohn Heffner } 12385d424d5aSJohn Heffner 12391b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 12401b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 12411b63edd6SYuchung Cheng { 12421b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 12431b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 12441b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 12451b63edd6SYuchung Cheng } 12461b63edd6SYuchung Cheng 12475d424d5aSJohn Heffner /* Inverse of above */ 124867469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 12495d424d5aSJohn Heffner { 1250cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1251cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 12525d424d5aSJohn Heffner int mtu; 12535d424d5aSJohn Heffner 12545d424d5aSJohn Heffner mtu = mss + 12555d424d5aSJohn Heffner tp->tcp_header_len + 12565d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 12575d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 12585d424d5aSJohn Heffner 125967469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 126067469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 126167469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 126267469601SEric Dumazet 126367469601SEric Dumazet if (dst && dst_allfrag(dst)) 126467469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 126567469601SEric Dumazet } 12665d424d5aSJohn Heffner return mtu; 12675d424d5aSJohn Heffner } 12685d424d5aSJohn Heffner 126967edfef7SAndi Kleen /* MTU probing init per socket */ 12705d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 12715d424d5aSJohn Heffner { 12725d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 12735d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 12745d424d5aSJohn Heffner 12755d424d5aSJohn Heffner icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; 12765d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 12775d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 12785d424d5aSJohn Heffner icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); 12795d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 12805d424d5aSJohn Heffner } 12814bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 12825d424d5aSJohn Heffner 12831da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 12841da177e4SLinus Torvalds 12851da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 12861da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1289caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 12901da177e4SLinus Torvalds It also does not include TCP options. 12911da177e4SLinus Torvalds 1292d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 12931da177e4SLinus Torvalds 12941da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 12951da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 12961da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 12971da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 12981da177e4SLinus Torvalds 12991da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 13001da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 13011da177e4SLinus Torvalds 1302d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1303d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 13041da177e4SLinus Torvalds */ 13051da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 13061da177e4SLinus Torvalds { 13071da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1308d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 13095d424d5aSJohn Heffner int mss_now; 13101da177e4SLinus Torvalds 13115d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 13125d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 13131da177e4SLinus Torvalds 13145d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1315409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 13161da177e4SLinus Torvalds 13171da177e4SLinus Torvalds /* And store cached results */ 1318d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 13195d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 13205d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1321c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 13221da177e4SLinus Torvalds 13231da177e4SLinus Torvalds return mss_now; 13241da177e4SLinus Torvalds } 13254bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 13261da177e4SLinus Torvalds 13271da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 13281da177e4SLinus Torvalds * and even PMTU discovery events into account. 13291da177e4SLinus Torvalds */ 13300c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 13311da177e4SLinus Torvalds { 1332cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1333cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1334c1b4a7e6SDavid S. Miller u32 mss_now; 133595c96174SEric Dumazet unsigned int header_len; 133633ad798cSAdam Langley struct tcp_out_options opts; 133733ad798cSAdam Langley struct tcp_md5sig_key *md5; 13381da177e4SLinus Torvalds 1339c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1340c1b4a7e6SDavid S. Miller 13411da177e4SLinus Torvalds if (dst) { 13421da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1343d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 13441da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 13451da177e4SLinus Torvalds } 13461da177e4SLinus Torvalds 134733ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 134833ad798cSAdam Langley sizeof(struct tcphdr); 134933ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 135033ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 135133ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 135233ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 135333ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 135433ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 135533ad798cSAdam Langley mss_now -= delta; 135633ad798cSAdam Langley } 1357cfb6eeb4SYOSHIFUJI Hideaki 13581da177e4SLinus Torvalds return mss_now; 13591da177e4SLinus Torvalds } 13601da177e4SLinus Torvalds 1361a762a980SDavid S. Miller /* Congestion window validation. (RFC2861) */ 13629e412ba7SIlpo Järvinen static void tcp_cwnd_validate(struct sock *sk) 1363a762a980SDavid S. Miller { 13649e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1365a762a980SDavid S. Miller 1366d436d686SIlpo Järvinen if (tp->packets_out >= tp->snd_cwnd) { 1367a762a980SDavid S. Miller /* Network is feed fully. */ 1368a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1369a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1370a762a980SDavid S. Miller } else { 1371a762a980SDavid S. Miller /* Network starves. */ 1372a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1373a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1374a762a980SDavid S. Miller 137515d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 137615d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1377a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1378a762a980SDavid S. Miller } 1379a762a980SDavid S. Miller } 1380a762a980SDavid S. Miller 13810e3a4803SIlpo Järvinen /* Returns the portion of skb which can be sent right away without 13820e3a4803SIlpo Järvinen * introducing MSS oddities to segment boundaries. In rare cases where 13830e3a4803SIlpo Järvinen * mss_now != mss_cache, we will request caller to create a small skb 13840e3a4803SIlpo Järvinen * per input skb which could be mostly avoided here (if desired). 13855ea3a748SIlpo Järvinen * 13865ea3a748SIlpo Järvinen * We explicitly want to create a request for splitting write queue tail 13875ea3a748SIlpo Järvinen * to a small skb for Nagle purposes while avoiding unnecessary modulos, 13885ea3a748SIlpo Järvinen * thus all the complexity (cwnd_len is always MSS multiple which we 13895ea3a748SIlpo Järvinen * return whenever allowed by the other factors). Basically we need the 13905ea3a748SIlpo Järvinen * modulo only when the receiver window alone is the limiting factor or 13915ea3a748SIlpo Järvinen * when we would be allowed to send the split-due-to-Nagle skb fully. 13920e3a4803SIlpo Järvinen */ 1393cf533ea5SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb, 13941485348dSBen Hutchings unsigned int mss_now, unsigned int max_segs) 1395c1b4a7e6SDavid S. Miller { 1396cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 13971485348dSBen Hutchings u32 needed, window, max_len; 1398c1b4a7e6SDavid S. Miller 139990840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 14001485348dSBen Hutchings max_len = mss_now * max_segs; 14010e3a4803SIlpo Järvinen 14021485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 14031485348dSBen Hutchings return max_len; 14040e3a4803SIlpo Järvinen 14055ea3a748SIlpo Järvinen needed = min(skb->len, window); 14065ea3a748SIlpo Järvinen 14071485348dSBen Hutchings if (max_len <= needed) 14081485348dSBen Hutchings return max_len; 14090e3a4803SIlpo Järvinen 14100e3a4803SIlpo Järvinen return needed - needed % mss_now; 1411c1b4a7e6SDavid S. Miller } 1412c1b4a7e6SDavid S. Miller 1413c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1414c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1415c1b4a7e6SDavid S. Miller */ 1416cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1417cf533ea5SEric Dumazet const struct sk_buff *skb) 1418c1b4a7e6SDavid S. Miller { 1419c1b4a7e6SDavid S. Miller u32 in_flight, cwnd; 1420c1b4a7e6SDavid S. Miller 1421c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 14224de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 14234de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1424c1b4a7e6SDavid S. Miller return 1; 1425c1b4a7e6SDavid S. Miller 1426c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1427c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1428c1b4a7e6SDavid S. Miller if (in_flight < cwnd) 1429c1b4a7e6SDavid S. Miller return (cwnd - in_flight); 1430c1b4a7e6SDavid S. Miller 1431c1b4a7e6SDavid S. Miller return 0; 1432c1b4a7e6SDavid S. Miller } 1433c1b4a7e6SDavid S. Miller 1434b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 143567edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1436c1b4a7e6SDavid S. Miller * SKB onto the wire. 1437c1b4a7e6SDavid S. Miller */ 1438cf533ea5SEric Dumazet static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, 1439056834d9SIlpo Järvinen unsigned int mss_now) 1440c1b4a7e6SDavid S. Miller { 1441c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1442c1b4a7e6SDavid S. Miller 1443f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 1444846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1445c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1446c1b4a7e6SDavid S. Miller } 1447c1b4a7e6SDavid S. Miller return tso_segs; 1448c1b4a7e6SDavid S. Miller } 1449c1b4a7e6SDavid S. Miller 145067edfef7SAndi Kleen /* Minshall's variant of the Nagle send check. */ 1451a2a385d6SEric Dumazet static inline bool tcp_minshall_check(const struct tcp_sock *tp) 1452c1b4a7e6SDavid S. Miller { 1453c1b4a7e6SDavid S. Miller return after(tp->snd_sml, tp->snd_una) && 1454c1b4a7e6SDavid S. Miller !after(tp->snd_sml, tp->snd_nxt); 1455c1b4a7e6SDavid S. Miller } 1456c1b4a7e6SDavid S. Miller 1457a2a385d6SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1458c1b4a7e6SDavid S. Miller * 1. It is full sized. 1459c1b4a7e6SDavid S. Miller * 2. Or it contains FIN. (already checked by caller) 14606d67e9beSFeng King * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1461c1b4a7e6SDavid S. Miller * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1462c1b4a7e6SDavid S. Miller * With Minshall's modification: all sent small packets are ACKed. 1463c1b4a7e6SDavid S. Miller */ 1464a2a385d6SEric Dumazet static inline bool tcp_nagle_check(const struct tcp_sock *tp, 1465c1b4a7e6SDavid S. Miller const struct sk_buff *skb, 146695c96174SEric Dumazet unsigned int mss_now, int nonagle) 1467c1b4a7e6SDavid S. Miller { 1468a02cec21SEric Dumazet return skb->len < mss_now && 1469c1b4a7e6SDavid S. Miller ((nonagle & TCP_NAGLE_CORK) || 1470a02cec21SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1471c1b4a7e6SDavid S. Miller } 1472c1b4a7e6SDavid S. Miller 1473a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1474c1b4a7e6SDavid S. Miller * sent now. 1475c1b4a7e6SDavid S. Miller */ 1476a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1477c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1478c1b4a7e6SDavid S. Miller { 1479c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1480c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1481c1b4a7e6SDavid S. Miller * 1482c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1483c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1484c1b4a7e6SDavid S. Miller */ 1485c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1486a2a385d6SEric Dumazet return true; 1487c1b4a7e6SDavid S. Miller 14889b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 14899b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1490a2a385d6SEric Dumazet return true; 1491c1b4a7e6SDavid S. Miller 1492c1b4a7e6SDavid S. Miller if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) 1493a2a385d6SEric Dumazet return true; 1494c1b4a7e6SDavid S. Miller 1495a2a385d6SEric Dumazet return false; 1496c1b4a7e6SDavid S. Miller } 1497c1b4a7e6SDavid S. Miller 1498c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1499a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1500a2a385d6SEric Dumazet const struct sk_buff *skb, 1501056834d9SIlpo Järvinen unsigned int cur_mss) 1502c1b4a7e6SDavid S. Miller { 1503c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1504c1b4a7e6SDavid S. Miller 1505c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1506c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1507c1b4a7e6SDavid S. Miller 150890840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1509c1b4a7e6SDavid S. Miller } 1510c1b4a7e6SDavid S. Miller 1511fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1512c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1513c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1514c1b4a7e6SDavid S. Miller */ 1515cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1516c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1517c1b4a7e6SDavid S. Miller { 1518cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1519c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1520c1b4a7e6SDavid S. Miller 1521846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 1522c1b4a7e6SDavid S. Miller 1523c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1524c1b4a7e6SDavid S. Miller return 0; 1525c1b4a7e6SDavid S. Miller 1526c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1527056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1528c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1529c1b4a7e6SDavid S. Miller 1530c1b4a7e6SDavid S. Miller return cwnd_quota; 1531c1b4a7e6SDavid S. Miller } 1532c1b4a7e6SDavid S. Miller 153367edfef7SAndi Kleen /* Test if sending is allowed right now. */ 1534a2a385d6SEric Dumazet bool tcp_may_send_now(struct sock *sk) 1535c1b4a7e6SDavid S. Miller { 1536cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1537fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1538c1b4a7e6SDavid S. Miller 1539a02cec21SEric Dumazet return skb && 15400c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1541c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1542a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1543c1b4a7e6SDavid S. Miller } 1544c1b4a7e6SDavid S. Miller 1545c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1546c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1547c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1548c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1549c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1550c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1551c1b4a7e6SDavid S. Miller */ 1552056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1553c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1554c1b4a7e6SDavid S. Miller { 1555c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1556c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 15579ce01461SIlpo Järvinen u8 flags; 1558c1b4a7e6SDavid S. Miller 1559c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1560c8ac3774SHerbert Xu if (skb->len != skb->data_len) 1561c8ac3774SHerbert Xu return tcp_fragment(sk, skb, len, mss_now); 1562c1b4a7e6SDavid S. Miller 1563c4ead4c5SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp); 1564c1b4a7e6SDavid S. Miller if (unlikely(buff == NULL)) 1565c1b4a7e6SDavid S. Miller return -ENOMEM; 1566c1b4a7e6SDavid S. Miller 15673ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 15683ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1569b60b49eaSHerbert Xu buff->truesize += nlen; 1570c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1571c1b4a7e6SDavid S. Miller 1572c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1573c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1574c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1575c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1576c1b4a7e6SDavid S. Miller 1577c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 15784de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 15794de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 15804de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1581c1b4a7e6SDavid S. Miller 1582c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1583c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1584c1b4a7e6SDavid S. Miller 158584fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1586c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1587c1b4a7e6SDavid S. Miller 1588c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 1589846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1590846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 1591c1b4a7e6SDavid S. Miller 1592c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1593c1b4a7e6SDavid S. Miller skb_header_release(buff); 1594fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1595c1b4a7e6SDavid S. Miller 1596c1b4a7e6SDavid S. Miller return 0; 1597c1b4a7e6SDavid S. Miller } 1598c1b4a7e6SDavid S. Miller 1599c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1600c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1601c1b4a7e6SDavid S. Miller * 1602c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1603c1b4a7e6SDavid S. Miller */ 1604a2a385d6SEric Dumazet static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) 1605c1b4a7e6SDavid S. Miller { 16069e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 16076687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1608c1b4a7e6SDavid S. Miller u32 send_win, cong_win, limit, in_flight; 1609ad9f4f50SEric Dumazet int win_divisor; 1610c1b4a7e6SDavid S. Miller 16114de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1612ae8064acSJohn Heffner goto send_now; 1613c1b4a7e6SDavid S. Miller 16146687e988SArnaldo Carvalho de Melo if (icsk->icsk_ca_state != TCP_CA_Open) 1615ae8064acSJohn Heffner goto send_now; 1616ae8064acSJohn Heffner 1617ae8064acSJohn Heffner /* Defer for less than two clock ticks. */ 1618bd515c3eSIlpo Järvinen if (tp->tso_deferred && 1619a2acde07SIlpo Järvinen (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) 1620ae8064acSJohn Heffner goto send_now; 1621908a75c1SDavid S. Miller 1622c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1623c1b4a7e6SDavid S. Miller 1624056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1625c1b4a7e6SDavid S. Miller 162690840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1627c1b4a7e6SDavid S. Miller 1628c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1629c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1630c1b4a7e6SDavid S. Miller 1631c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1632c1b4a7e6SDavid S. Miller 1633ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 16341485348dSBen Hutchings if (limit >= min_t(unsigned int, sk->sk_gso_max_size, 163595bd09ebSEric Dumazet tp->xmit_size_goal_segs * tp->mss_cache)) 1636ae8064acSJohn Heffner goto send_now; 1637ba244fe9SDavid S. Miller 163862ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 163962ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 164062ad2761SIlpo Järvinen goto send_now; 164162ad2761SIlpo Järvinen 1642ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1643ad9f4f50SEric Dumazet if (win_divisor) { 1644c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1645c1b4a7e6SDavid S. Miller 1646c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1647c1b4a7e6SDavid S. Miller * just use it. 1648c1b4a7e6SDavid S. Miller */ 1649ad9f4f50SEric Dumazet chunk /= win_divisor; 1650c1b4a7e6SDavid S. Miller if (limit >= chunk) 1651ae8064acSJohn Heffner goto send_now; 1652c1b4a7e6SDavid S. Miller } else { 1653c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1654c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1655c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1656c1b4a7e6SDavid S. Miller * then send now. 1657c1b4a7e6SDavid S. Miller */ 16586b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1659ae8064acSJohn Heffner goto send_now; 1660c1b4a7e6SDavid S. Miller } 1661c1b4a7e6SDavid S. Miller 1662f4541d60SEric Dumazet /* Ok, it looks like it is advisable to defer. 1663f4541d60SEric Dumazet * Do not rearm the timer if already set to not break TCP ACK clocking. 1664f4541d60SEric Dumazet */ 1665f4541d60SEric Dumazet if (!tp->tso_deferred) 1666ae8064acSJohn Heffner tp->tso_deferred = 1 | (jiffies << 1); 1667ae8064acSJohn Heffner 1668a2a385d6SEric Dumazet return true; 1669ae8064acSJohn Heffner 1670ae8064acSJohn Heffner send_now: 1671ae8064acSJohn Heffner tp->tso_deferred = 0; 1672a2a385d6SEric Dumazet return false; 1673c1b4a7e6SDavid S. Miller } 1674c1b4a7e6SDavid S. Miller 16755d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 167667edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 167767edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 167867edfef7SAndi Kleen * changes resulting in larger path MTUs. 167967edfef7SAndi Kleen * 16805d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 16815d424d5aSJohn Heffner * 1 if a probe was sent, 1682056834d9SIlpo Järvinen * -1 otherwise 1683056834d9SIlpo Järvinen */ 16845d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 16855d424d5aSJohn Heffner { 16865d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 16875d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 16885d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 16895d424d5aSJohn Heffner int len; 16905d424d5aSJohn Heffner int probe_size; 169191cc17c0SIlpo Järvinen int size_needed; 16925d424d5aSJohn Heffner int copy; 16935d424d5aSJohn Heffner int mss_now; 16945d424d5aSJohn Heffner 16955d424d5aSJohn Heffner /* Not currently probing/verifying, 16965d424d5aSJohn Heffner * not in recovery, 16975d424d5aSJohn Heffner * have enough cwnd, and 16985d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 16995d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 17005d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 17015d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 17025d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1703cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 17045d424d5aSJohn Heffner return -1; 17055d424d5aSJohn Heffner 17065d424d5aSJohn Heffner /* Very simple search strategy: just double the MSS. */ 17070c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 17085d424d5aSJohn Heffner probe_size = 2 * tp->mss_cache; 170991cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 17105d424d5aSJohn Heffner if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { 17115d424d5aSJohn Heffner /* TODO: set timer for probe_converge_event */ 17125d424d5aSJohn Heffner return -1; 17135d424d5aSJohn Heffner } 17145d424d5aSJohn Heffner 17155d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 17167f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 17175d424d5aSJohn Heffner return -1; 17185d424d5aSJohn Heffner 171991cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 17205d424d5aSJohn Heffner return -1; 172190840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 17225d424d5aSJohn Heffner return 0; 17235d424d5aSJohn Heffner 1724d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1725d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1726d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 17275d424d5aSJohn Heffner return -1; 17285d424d5aSJohn Heffner else 17295d424d5aSJohn Heffner return 0; 17305d424d5aSJohn Heffner } 17315d424d5aSJohn Heffner 17325d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 17335d424d5aSJohn Heffner if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) 17345d424d5aSJohn Heffner return -1; 17353ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 17363ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 17375d424d5aSJohn Heffner 1738fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 17395d424d5aSJohn Heffner 17405d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 17415d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 17424de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 17435d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 17445d424d5aSJohn Heffner nskb->csum = 0; 174584fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 17465d424d5aSJohn Heffner 174750c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 174850c4817eSIlpo Järvinen 17495d424d5aSJohn Heffner len = 0; 1750234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 17515d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 17525d424d5aSJohn Heffner if (nskb->ip_summed) 17535d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 17545d424d5aSJohn Heffner else 17555d424d5aSJohn Heffner nskb->csum = skb_copy_and_csum_bits(skb, 0, 1756056834d9SIlpo Järvinen skb_put(nskb, copy), 1757056834d9SIlpo Järvinen copy, nskb->csum); 17585d424d5aSJohn Heffner 17595d424d5aSJohn Heffner if (skb->len <= copy) { 17605d424d5aSJohn Heffner /* We've eaten all the data from this skb. 17615d424d5aSJohn Heffner * Throw it away. */ 17624de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 1763fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 17643ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 17655d424d5aSJohn Heffner } else { 17664de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 1767a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 17685d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 17695d424d5aSJohn Heffner skb_pull(skb, copy); 177084fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 1771056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 1772056834d9SIlpo Järvinen skb->len, 0); 17735d424d5aSJohn Heffner } else { 17745d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 17755d424d5aSJohn Heffner tcp_set_skb_tso_segs(sk, skb, mss_now); 17765d424d5aSJohn Heffner } 17775d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 17785d424d5aSJohn Heffner } 17795d424d5aSJohn Heffner 17805d424d5aSJohn Heffner len += copy; 1781234b6860SIlpo Järvinen 1782234b6860SIlpo Järvinen if (len >= probe_size) 1783234b6860SIlpo Järvinen break; 17845d424d5aSJohn Heffner } 17855d424d5aSJohn Heffner tcp_init_tso_segs(sk, nskb, nskb->len); 17865d424d5aSJohn Heffner 17875d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 17885d424d5aSJohn Heffner * be resegmented into mss-sized pieces by tcp_write_xmit(). */ 17895d424d5aSJohn Heffner TCP_SKB_CB(nskb)->when = tcp_time_stamp; 17905d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 17915d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 17925d424d5aSJohn Heffner * effectively two packets. */ 17935d424d5aSJohn Heffner tp->snd_cwnd--; 179466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 17955d424d5aSJohn Heffner 17965d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 17970e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 17980e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 17995d424d5aSJohn Heffner 18005d424d5aSJohn Heffner return 1; 18015d424d5aSJohn Heffner } 18025d424d5aSJohn Heffner 18035d424d5aSJohn Heffner return -1; 18045d424d5aSJohn Heffner } 18055d424d5aSJohn Heffner 18061da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 18071da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 18081da177e4SLinus Torvalds * window for us. 18091da177e4SLinus Torvalds * 1810f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 1811f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 1812f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 1813f8269a49SIlpo Järvinen * 18146ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 18156ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 18166ba8a3b1SNandita Dukkipati 1817a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 1818a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 18191da177e4SLinus Torvalds */ 1820a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 1821d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 18221da177e4SLinus Torvalds { 18231da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 182492df7b51SDavid S. Miller struct sk_buff *skb; 1825c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 1826c1b4a7e6SDavid S. Miller int cwnd_quota; 18275d424d5aSJohn Heffner int result; 18281da177e4SLinus Torvalds 1829c1b4a7e6SDavid S. Miller sent_pkts = 0; 18305d424d5aSJohn Heffner 1831d5dd9175SIlpo Järvinen if (!push_one) { 18325d424d5aSJohn Heffner /* Do MTU probing. */ 1833d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 1834d5dd9175SIlpo Järvinen if (!result) { 1835a2a385d6SEric Dumazet return false; 18365d424d5aSJohn Heffner } else if (result > 0) { 18375d424d5aSJohn Heffner sent_pkts = 1; 18385d424d5aSJohn Heffner } 1839d5dd9175SIlpo Järvinen } 18405d424d5aSJohn Heffner 1841fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 1842c8ac3774SHerbert Xu unsigned int limit; 1843c8ac3774SHerbert Xu 1844b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 1845c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 1846c1b4a7e6SDavid S. Miller 1847ec342325SAndrew Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) 1848ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 1849ec342325SAndrew Vagin 1850b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 18516ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 18526ba8a3b1SNandita Dukkipati if (push_one == 2) 18536ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 18546ba8a3b1SNandita Dukkipati cwnd_quota = 1; 18556ba8a3b1SNandita Dukkipati else 1856b68e9f85SHerbert Xu break; 18576ba8a3b1SNandita Dukkipati } 1858b68e9f85SHerbert Xu 1859b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 1860b68e9f85SHerbert Xu break; 1861b68e9f85SHerbert Xu 1862c1b4a7e6SDavid S. Miller if (tso_segs == 1) { 1863aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 1864aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1865aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 1866aa93466bSDavid S. Miller break; 1867c1b4a7e6SDavid S. Miller } else { 1868d5dd9175SIlpo Järvinen if (!push_one && tcp_tso_should_defer(sk, skb)) 1869aa93466bSDavid S. Miller break; 1870c1b4a7e6SDavid S. Miller } 1871aa93466bSDavid S. Miller 1872c9eeec26SEric Dumazet /* TCP Small Queues : 1873c9eeec26SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 1874c9eeec26SEric Dumazet * This allows for : 1875c9eeec26SEric Dumazet * - better RTT estimation and ACK scheduling 1876c9eeec26SEric Dumazet * - faster recovery 1877c9eeec26SEric Dumazet * - high rates 187846d3ceabSEric Dumazet */ 1879c9eeec26SEric Dumazet limit = max(skb->truesize, sk->sk_pacing_rate >> 10); 1880c9eeec26SEric Dumazet 1881c9eeec26SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) { 188246d3ceabSEric Dumazet set_bit(TSQ_THROTTLED, &tp->tsq_flags); 188346d3ceabSEric Dumazet break; 188446d3ceabSEric Dumazet } 1885c9eeec26SEric Dumazet 1886c8ac3774SHerbert Xu limit = mss_now; 1887f8269a49SIlpo Järvinen if (tso_segs > 1 && !tcp_urg_mode(tp)) 18880e3a4803SIlpo Järvinen limit = tcp_mss_split_point(sk, skb, mss_now, 18891485348dSBen Hutchings min_t(unsigned int, 18901485348dSBen Hutchings cwnd_quota, 18911485348dSBen Hutchings sk->sk_gso_max_segs)); 1892c8ac3774SHerbert Xu 1893c8ac3774SHerbert Xu if (skb->len > limit && 1894c4ead4c5SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 18951da177e4SLinus Torvalds break; 18961da177e4SLinus Torvalds 18971da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 1898c1b4a7e6SDavid S. Miller 1899d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 19001da177e4SLinus Torvalds break; 19011da177e4SLinus Torvalds 1902ec342325SAndrew Vagin repair: 19031da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 19041da177e4SLinus Torvalds * This call will increment packets_out. 19051da177e4SLinus Torvalds */ 190666f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 19071da177e4SLinus Torvalds 19081da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 1909a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 1910d5dd9175SIlpo Järvinen 1911d5dd9175SIlpo Järvinen if (push_one) 1912d5dd9175SIlpo Järvinen break; 19131da177e4SLinus Torvalds } 19141da177e4SLinus Torvalds 1915aa93466bSDavid S. Miller if (likely(sent_pkts)) { 1916684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 1917684bad11SYuchung Cheng tp->prr_out += sent_pkts; 19186ba8a3b1SNandita Dukkipati 19196ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 19206ba8a3b1SNandita Dukkipati if (push_one != 2) 19216ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 19229e412ba7SIlpo Järvinen tcp_cwnd_validate(sk); 1923a2a385d6SEric Dumazet return false; 19241da177e4SLinus Torvalds } 19256ba8a3b1SNandita Dukkipati return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); 19266ba8a3b1SNandita Dukkipati } 19276ba8a3b1SNandita Dukkipati 19286ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 19296ba8a3b1SNandita Dukkipati { 19306ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 19316ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 19326ba8a3b1SNandita Dukkipati u32 timeout, tlp_time_stamp, rto_time_stamp; 19336ba8a3b1SNandita Dukkipati u32 rtt = tp->srtt >> 3; 19346ba8a3b1SNandita Dukkipati 19356ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) 19366ba8a3b1SNandita Dukkipati return false; 19376ba8a3b1SNandita Dukkipati /* No consecutive loss probes. */ 19386ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { 19396ba8a3b1SNandita Dukkipati tcp_rearm_rto(sk); 19406ba8a3b1SNandita Dukkipati return false; 19416ba8a3b1SNandita Dukkipati } 19426ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 19436ba8a3b1SNandita Dukkipati * finishes. 19446ba8a3b1SNandita Dukkipati */ 19456ba8a3b1SNandita Dukkipati if (sk->sk_state == TCP_SYN_RECV) 19466ba8a3b1SNandita Dukkipati return false; 19476ba8a3b1SNandita Dukkipati 19486ba8a3b1SNandita Dukkipati /* TLP is only scheduled when next timer event is RTO. */ 19496ba8a3b1SNandita Dukkipati if (icsk->icsk_pending != ICSK_TIME_RETRANS) 19506ba8a3b1SNandita Dukkipati return false; 19516ba8a3b1SNandita Dukkipati 19526ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 19536ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 19546ba8a3b1SNandita Dukkipati */ 19556ba8a3b1SNandita Dukkipati if (sysctl_tcp_early_retrans < 3 || !rtt || !tp->packets_out || 19566ba8a3b1SNandita Dukkipati !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) 19576ba8a3b1SNandita Dukkipati return false; 19586ba8a3b1SNandita Dukkipati 19596ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 19606ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 19616ba8a3b1SNandita Dukkipati return false; 19626ba8a3b1SNandita Dukkipati 19636ba8a3b1SNandita Dukkipati /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account 19646ba8a3b1SNandita Dukkipati * for delayed ack when there's one outstanding packet. 19656ba8a3b1SNandita Dukkipati */ 19666ba8a3b1SNandita Dukkipati timeout = rtt << 1; 19676ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 19686ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, 19696ba8a3b1SNandita Dukkipati (rtt + (rtt >> 1) + TCP_DELACK_MAX)); 19706ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, msecs_to_jiffies(10)); 19716ba8a3b1SNandita Dukkipati 19726ba8a3b1SNandita Dukkipati /* If RTO is shorter, just schedule TLP in its place. */ 19736ba8a3b1SNandita Dukkipati tlp_time_stamp = tcp_time_stamp + timeout; 19746ba8a3b1SNandita Dukkipati rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; 19756ba8a3b1SNandita Dukkipati if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { 19766ba8a3b1SNandita Dukkipati s32 delta = rto_time_stamp - tcp_time_stamp; 19776ba8a3b1SNandita Dukkipati if (delta > 0) 19786ba8a3b1SNandita Dukkipati timeout = delta; 19796ba8a3b1SNandita Dukkipati } 19806ba8a3b1SNandita Dukkipati 19816ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 19826ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 19836ba8a3b1SNandita Dukkipati return true; 19846ba8a3b1SNandita Dukkipati } 19856ba8a3b1SNandita Dukkipati 19866ba8a3b1SNandita Dukkipati /* When probe timeout (PTO) fires, send a new segment if one exists, else 19876ba8a3b1SNandita Dukkipati * retransmit the last segment. 19886ba8a3b1SNandita Dukkipati */ 19896ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 19906ba8a3b1SNandita Dukkipati { 19919b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 19926ba8a3b1SNandita Dukkipati struct sk_buff *skb; 19936ba8a3b1SNandita Dukkipati int pcount; 19946ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 19956ba8a3b1SNandita Dukkipati int err = -1; 19966ba8a3b1SNandita Dukkipati 19976ba8a3b1SNandita Dukkipati if (tcp_send_head(sk) != NULL) { 19986ba8a3b1SNandita Dukkipati err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 19996ba8a3b1SNandita Dukkipati goto rearm_timer; 20006ba8a3b1SNandita Dukkipati } 20016ba8a3b1SNandita Dukkipati 20029b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 20039b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 20049b717a8dSNandita Dukkipati goto rearm_timer; 20059b717a8dSNandita Dukkipati 20066ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 20076ba8a3b1SNandita Dukkipati skb = tcp_write_queue_tail(sk); 20086ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 20096ba8a3b1SNandita Dukkipati goto rearm_timer; 20106ba8a3b1SNandita Dukkipati 20116ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 20126ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 20136ba8a3b1SNandita Dukkipati goto rearm_timer; 20146ba8a3b1SNandita Dukkipati 20156ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 20166ba8a3b1SNandita Dukkipati if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss))) 20176ba8a3b1SNandita Dukkipati goto rearm_timer; 20186ba8a3b1SNandita Dukkipati skb = tcp_write_queue_tail(sk); 20196ba8a3b1SNandita Dukkipati } 20206ba8a3b1SNandita Dukkipati 20216ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 20226ba8a3b1SNandita Dukkipati goto rearm_timer; 20236ba8a3b1SNandita Dukkipati 20246ba8a3b1SNandita Dukkipati /* Probe with zero data doesn't trigger fast recovery. */ 20256ba8a3b1SNandita Dukkipati if (skb->len > 0) 20266ba8a3b1SNandita Dukkipati err = __tcp_retransmit_skb(sk, skb); 20276ba8a3b1SNandita Dukkipati 20289b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 20299b717a8dSNandita Dukkipati if (likely(!err)) 20309b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 20319b717a8dSNandita Dukkipati 20326ba8a3b1SNandita Dukkipati rearm_timer: 20336ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 20346ba8a3b1SNandita Dukkipati inet_csk(sk)->icsk_rto, 20356ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 20366ba8a3b1SNandita Dukkipati 20376ba8a3b1SNandita Dukkipati if (likely(!err)) 20386ba8a3b1SNandita Dukkipati NET_INC_STATS_BH(sock_net(sk), 20396ba8a3b1SNandita Dukkipati LINUX_MIB_TCPLOSSPROBES); 20406ba8a3b1SNandita Dukkipati return; 20411da177e4SLinus Torvalds } 20421da177e4SLinus Torvalds 2043a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2044a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2045a762a980SDavid S. Miller * The socket must be locked by the caller. 2046a762a980SDavid S. Miller */ 20479e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 20489e412ba7SIlpo Järvinen int nonagle) 2049a762a980SDavid S. Miller { 2050726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2051726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2052726e07a8SIlpo Järvinen * all will be happy. 2053726e07a8SIlpo Järvinen */ 2054726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2055726e07a8SIlpo Järvinen return; 2056726e07a8SIlpo Järvinen 205799a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 205899a1dec7SMel Gorman sk_gfp_atomic(sk, GFP_ATOMIC))) 20599e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2060a762a980SDavid S. Miller } 2061a762a980SDavid S. Miller 2062c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2063c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2064c1b4a7e6SDavid S. Miller */ 2065c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2066c1b4a7e6SDavid S. Miller { 2067fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2068c1b4a7e6SDavid S. Miller 2069c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2070c1b4a7e6SDavid S. Miller 2071d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2072c1b4a7e6SDavid S. Miller } 2073c1b4a7e6SDavid S. Miller 20741da177e4SLinus Torvalds /* This function returns the amount that we can raise the 20751da177e4SLinus Torvalds * usable window based on the following constraints 20761da177e4SLinus Torvalds * 20771da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 20781da177e4SLinus Torvalds * 2. We limit memory per socket 20791da177e4SLinus Torvalds * 20801da177e4SLinus Torvalds * RFC 1122: 20811da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 20821da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 20831da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 20841da177e4SLinus Torvalds * 20851da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 20861da177e4SLinus Torvalds * it at least MSS bytes. 20871da177e4SLinus Torvalds * 20881da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 20891da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 20901da177e4SLinus Torvalds * 20911da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 20921da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 20931da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 20941da177e4SLinus Torvalds * window to always advance by a single byte. 20951da177e4SLinus Torvalds * 20961da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 20971da177e4SLinus Torvalds * then this will not be a problem. 20981da177e4SLinus Torvalds * 20991da177e4SLinus Torvalds * BSD seems to make the following compromise: 21001da177e4SLinus Torvalds * 21011da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 21021da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 21031da177e4SLinus Torvalds * then set the window to 0. 21041da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 21051da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 21061da177e4SLinus Torvalds * and from being larger than the largest representable value. 21071da177e4SLinus Torvalds * 21081da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 21091da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 21101da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 21111da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 21121da177e4SLinus Torvalds * because the pipeline is full. 21131da177e4SLinus Torvalds * 21141da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 21151da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 21161da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 21171da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 21181da177e4SLinus Torvalds * of having a fixed window size at almost all times. 21191da177e4SLinus Torvalds * 21201da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 21211da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 21221da177e4SLinus Torvalds * 21231da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 21241da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 21251da177e4SLinus Torvalds */ 21261da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 21271da177e4SLinus Torvalds { 2128463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 21291da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2130caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 21311da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 21321da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 21331da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 21341da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 21351da177e4SLinus Torvalds */ 2136463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 21371da177e4SLinus Torvalds int free_space = tcp_space(sk); 21381da177e4SLinus Torvalds int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); 21391da177e4SLinus Torvalds int window; 21401da177e4SLinus Torvalds 21411da177e4SLinus Torvalds if (mss > full_space) 21421da177e4SLinus Torvalds mss = full_space; 21431da177e4SLinus Torvalds 2144b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2145463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 21461da177e4SLinus Torvalds 2147180d8cd9SGlauber Costa if (sk_under_memory_pressure(sk)) 2148056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2149056834d9SIlpo Järvinen 4U * tp->advmss); 21501da177e4SLinus Torvalds 21511da177e4SLinus Torvalds if (free_space < mss) 21521da177e4SLinus Torvalds return 0; 21531da177e4SLinus Torvalds } 21541da177e4SLinus Torvalds 21551da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 21561da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 21571da177e4SLinus Torvalds 21581da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 21591da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 21601da177e4SLinus Torvalds */ 21611da177e4SLinus Torvalds window = tp->rcv_wnd; 21621da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 21631da177e4SLinus Torvalds window = free_space; 21641da177e4SLinus Torvalds 21651da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 21661da177e4SLinus Torvalds * Import case: prevent zero window announcement if 21671da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 21681da177e4SLinus Torvalds */ 21691da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 21701da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 21711da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 21721da177e4SLinus Torvalds } else { 21731da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 21741da177e4SLinus Torvalds * Window clamp already applied above. 21751da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 21761da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 21771da177e4SLinus Torvalds * and multiply from happening most of the time. 21781da177e4SLinus Torvalds * We also don't do any window rounding when the free space 21791da177e4SLinus Torvalds * is too small. 21801da177e4SLinus Torvalds */ 21811da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 21821da177e4SLinus Torvalds window = (free_space / mss) * mss; 218384565070SJohn Heffner else if (mss == full_space && 2184b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 218584565070SJohn Heffner window = free_space; 21861da177e4SLinus Torvalds } 21871da177e4SLinus Torvalds 21881da177e4SLinus Torvalds return window; 21891da177e4SLinus Torvalds } 21901da177e4SLinus Torvalds 21914a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 21924a17fc3aSIlpo Järvinen static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 21931da177e4SLinus Torvalds { 21941da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2195fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2196058dc334SIlpo Järvinen int skb_size, next_skb_size; 21971da177e4SLinus Torvalds 2198058dc334SIlpo Järvinen skb_size = skb->len; 2199058dc334SIlpo Järvinen next_skb_size = next_skb->len; 22001da177e4SLinus Torvalds 2201058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 22021da177e4SLinus Torvalds 22036859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 2204a6963a6bSIlpo Järvinen 2205fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 22061da177e4SLinus Torvalds 2207058dc334SIlpo Järvinen skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), 22081a4e2d09SArnaldo Carvalho de Melo next_skb_size); 22091da177e4SLinus Torvalds 221052d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 221152d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 22121da177e4SLinus Torvalds 221384fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 22141da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 22151da177e4SLinus Torvalds 22161da177e4SLinus Torvalds /* Update sequence range on original skb. */ 22171da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 22181da177e4SLinus Torvalds 2219e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 22204de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 22211da177e4SLinus Torvalds 22221da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 22231da177e4SLinus Torvalds * packet counting does not break. 22241da177e4SLinus Torvalds */ 22254828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2226b7689205SIlpo Järvinen 2227b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2228ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2229ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2230ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2231b7689205SIlpo Järvinen 2232797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2233797108d1SIlpo Järvinen 22343ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 22351da177e4SLinus Torvalds } 22361da177e4SLinus Torvalds 223767edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2238a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 22394a17fc3aSIlpo Järvinen { 22404a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2241a2a385d6SEric Dumazet return false; 22424a17fc3aSIlpo Järvinen /* TODO: SACK collapsing could be used to remove this condition */ 22434a17fc3aSIlpo Järvinen if (skb_shinfo(skb)->nr_frags != 0) 2244a2a385d6SEric Dumazet return false; 22454a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2246a2a385d6SEric Dumazet return false; 22474a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2248a2a385d6SEric Dumazet return false; 22494a17fc3aSIlpo Järvinen /* Some heurestics for collapsing over SACK'd could be invented */ 22504a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2251a2a385d6SEric Dumazet return false; 22524a17fc3aSIlpo Järvinen 2253a2a385d6SEric Dumazet return true; 22544a17fc3aSIlpo Järvinen } 22554a17fc3aSIlpo Järvinen 225667edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 225767edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 225867edfef7SAndi Kleen */ 22594a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 22604a17fc3aSIlpo Järvinen int space) 22614a17fc3aSIlpo Järvinen { 22624a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 22634a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2264a2a385d6SEric Dumazet bool first = true; 22654a17fc3aSIlpo Järvinen 22664a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 22674a17fc3aSIlpo Järvinen return; 22684de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 22694a17fc3aSIlpo Järvinen return; 22704a17fc3aSIlpo Järvinen 22714a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 22724a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 22734a17fc3aSIlpo Järvinen break; 22744a17fc3aSIlpo Järvinen 22754a17fc3aSIlpo Järvinen space -= skb->len; 22764a17fc3aSIlpo Järvinen 22774a17fc3aSIlpo Järvinen if (first) { 2278a2a385d6SEric Dumazet first = false; 22794a17fc3aSIlpo Järvinen continue; 22804a17fc3aSIlpo Järvinen } 22814a17fc3aSIlpo Järvinen 22824a17fc3aSIlpo Järvinen if (space < 0) 22834a17fc3aSIlpo Järvinen break; 22844a17fc3aSIlpo Järvinen /* Punt if not enough space exists in the first SKB for 22854a17fc3aSIlpo Järvinen * the data in the second 22864a17fc3aSIlpo Järvinen */ 2287a21d4572SEric Dumazet if (skb->len > skb_availroom(to)) 22884a17fc3aSIlpo Järvinen break; 22894a17fc3aSIlpo Järvinen 22904a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 22914a17fc3aSIlpo Järvinen break; 22924a17fc3aSIlpo Järvinen 22934a17fc3aSIlpo Järvinen tcp_collapse_retrans(sk, to); 22944a17fc3aSIlpo Järvinen } 22954a17fc3aSIlpo Järvinen } 22964a17fc3aSIlpo Järvinen 22971da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 22981da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 22991da177e4SLinus Torvalds * error occurred which prevented the send. 23001da177e4SLinus Torvalds */ 230193b174adSYuchung Cheng int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 23021da177e4SLinus Torvalds { 23031da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 23045d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 23057d227cd2SSridhar Samudrala unsigned int cur_mss; 23061da177e4SLinus Torvalds 23075d424d5aSJohn Heffner /* Inconslusive MTU probe */ 23085d424d5aSJohn Heffner if (icsk->icsk_mtup.probe_size) { 23095d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 23105d424d5aSJohn Heffner } 23115d424d5aSJohn Heffner 23121da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2313caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 23141da177e4SLinus Torvalds */ 23151da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 23161da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 23171da177e4SLinus Torvalds return -EAGAIN; 23181da177e4SLinus Torvalds 23191da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 23201da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 23211da177e4SLinus Torvalds BUG(); 23221da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 23231da177e4SLinus Torvalds return -ENOMEM; 23241da177e4SLinus Torvalds } 23251da177e4SLinus Torvalds 23267d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 23277d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 23287d227cd2SSridhar Samudrala 23290c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 23307d227cd2SSridhar Samudrala 23311da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 23321da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 23331da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 23341da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 23351da177e4SLinus Torvalds */ 23369d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 23379d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 23381da177e4SLinus Torvalds return -EAGAIN; 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds if (skb->len > cur_mss) { 2341846998aeSDavid S. Miller if (tcp_fragment(sk, skb, cur_mss, cur_mss)) 23421da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 234302276f3cSIlpo Järvinen } else { 23449eb9362eSIlpo Järvinen int oldpcount = tcp_skb_pcount(skb); 23459eb9362eSIlpo Järvinen 23469eb9362eSIlpo Järvinen if (unlikely(oldpcount > 1)) { 234702276f3cSIlpo Järvinen tcp_init_tso_segs(sk, skb, cur_mss); 23489eb9362eSIlpo Järvinen tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); 23499eb9362eSIlpo Järvinen } 23501da177e4SLinus Torvalds } 23511da177e4SLinus Torvalds 23521da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 23531da177e4SLinus Torvalds 23541da177e4SLinus Torvalds /* Some Solaris stacks overoptimize and ignore the FIN on a 23551da177e4SLinus Torvalds * retransmit when old data is attached. So strip it off 23561da177e4SLinus Torvalds * since it is cheap to do so and saves bytes on the network. 23571da177e4SLinus Torvalds */ 23581da177e4SLinus Torvalds if (skb->len > 0 && 23594de075e0SEric Dumazet (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 23601da177e4SLinus Torvalds tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { 23611da177e4SLinus Torvalds if (!pskb_trim(skb, 0)) { 2362e870a8efSIlpo Järvinen /* Reuse, even though it does some unnecessary work */ 2363e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1, 23644de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags); 23651da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 23661da177e4SLinus Torvalds } 23671da177e4SLinus Torvalds } 23681da177e4SLinus Torvalds 23691da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 23701da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 23711da177e4SLinus Torvalds */ 23721da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 23731da177e4SLinus Torvalds 237450bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 237550bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 237650bceae9SThomas Graf * beyond what csum_start can cover. 237750bceae9SThomas Graf */ 237850bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 237950bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 2380117632e6SEric Dumazet struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, 2381117632e6SEric Dumazet GFP_ATOMIC); 238293b174adSYuchung Cheng return nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2383117632e6SEric Dumazet -ENOBUFS; 2384117632e6SEric Dumazet } else { 238593b174adSYuchung Cheng return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2386117632e6SEric Dumazet } 238793b174adSYuchung Cheng } 238893b174adSYuchung Cheng 238993b174adSYuchung Cheng int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 239093b174adSYuchung Cheng { 239193b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 239293b174adSYuchung Cheng int err = __tcp_retransmit_skb(sk, skb); 23931da177e4SLinus Torvalds 23941da177e4SLinus Torvalds if (err == 0) { 23951da177e4SLinus Torvalds /* Update global TCP statistics. */ 239681cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 23971da177e4SLinus Torvalds 23981da177e4SLinus Torvalds tp->total_retrans++; 23991da177e4SLinus Torvalds 24001da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 24011da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2402e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 24031da177e4SLinus Torvalds } 24041da177e4SLinus Torvalds #endif 2405b08d6cb2SIlpo Järvinen if (!tp->retrans_out) 2406b08d6cb2SIlpo Järvinen tp->lost_retrans_low = tp->snd_nxt; 24071da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 24081da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 24091da177e4SLinus Torvalds 24101da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 24111da177e4SLinus Torvalds if (!tp->retrans_stamp) 24121da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(skb)->when; 24131da177e4SLinus Torvalds 2414c24f691bSYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 24151da177e4SLinus Torvalds 24161da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 24171da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 24181da177e4SLinus Torvalds */ 24191da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 242024ab6becSYuchung Cheng } else { 242124ab6becSYuchung Cheng NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 24221da177e4SLinus Torvalds } 24231da177e4SLinus Torvalds return err; 24241da177e4SLinus Torvalds } 24251da177e4SLinus Torvalds 242667edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 242767edfef7SAndi Kleen * window/congestion state. 242867edfef7SAndi Kleen */ 2429a2a385d6SEric Dumazet static bool tcp_can_forward_retransmit(struct sock *sk) 2430b5afe7bcSIlpo Järvinen { 2431b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2432cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2433b5afe7bcSIlpo Järvinen 2434b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2435b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2436a2a385d6SEric Dumazet return false; 2437b5afe7bcSIlpo Järvinen 2438b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2439b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2440a2a385d6SEric Dumazet return false; 2441b5afe7bcSIlpo Järvinen 2442b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2443b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2444b5afe7bcSIlpo Järvinen * 2445b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2446b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2447b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2448b5afe7bcSIlpo Järvinen */ 2449b5afe7bcSIlpo Järvinen 2450b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2451a2a385d6SEric Dumazet return false; 2452b5afe7bcSIlpo Järvinen 2453a2a385d6SEric Dumazet return true; 2454b5afe7bcSIlpo Järvinen } 2455b5afe7bcSIlpo Järvinen 24561da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 24571da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 24581da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 24591da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 24601da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 24611da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 24621da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 24631da177e4SLinus Torvalds */ 24641da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 24651da177e4SLinus Torvalds { 24666687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 24671da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 24681da177e4SLinus Torvalds struct sk_buff *skb; 24690e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2470618d9f25SIlpo Järvinen u32 last_lost; 247161eb55f4SIlpo Järvinen int mib_idx; 24720e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 24736a438bbeSStephen Hemminger 247445e77d31SIlpo Järvinen if (!tp->packets_out) 247545e77d31SIlpo Järvinen return; 247645e77d31SIlpo Järvinen 247708ebd172SIlpo Järvinen if (!tp->lost_out) 247808ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 247908ebd172SIlpo Järvinen 2480618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 24816a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2482618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2483618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2484618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2485618d9f25SIlpo Järvinen } else { 2486fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2487618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2488618d9f25SIlpo Järvinen } 24891da177e4SLinus Torvalds 2490fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 24911da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 24921da177e4SLinus Torvalds 2493fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2494fe067e8aSDavid S. Miller break; 24956a438bbeSStephen Hemminger /* we could do better than to assign each time */ 24960e1c54c2SIlpo Järvinen if (hole == NULL) 24976a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 24986a438bbeSStephen Hemminger 24991da177e4SLinus Torvalds /* Assume this retransmit will generate 25001da177e4SLinus Torvalds * only one packet for congestion window 25011da177e4SLinus Torvalds * calculation purposes. This works because 25021da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 25031da177e4SLinus Torvalds * packet to be MSS sized and all the 25041da177e4SLinus Torvalds * packet counting works out. 25051da177e4SLinus Torvalds */ 25061da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 25071da177e4SLinus Torvalds return; 25080e1c54c2SIlpo Järvinen 25090e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 25100e1c54c2SIlpo Järvinen begin_fwd: 25110e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2512006f582cSIlpo Järvinen break; 25130e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 25140e1c54c2SIlpo Järvinen 25150e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2516618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 25170e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 25180e1c54c2SIlpo Järvinen break; 25190e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 25200e1c54c2SIlpo Järvinen if (hole != NULL) { 25210e1c54c2SIlpo Järvinen skb = hole; 25220e1c54c2SIlpo Järvinen hole = NULL; 25230e1c54c2SIlpo Järvinen } 25240e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 25250e1c54c2SIlpo Järvinen goto begin_fwd; 25260e1c54c2SIlpo Järvinen 25270e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 2528ac11ba75SIlpo Järvinen if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 25290e1c54c2SIlpo Järvinen hole = skb; 253061eb55f4SIlpo Järvinen continue; 25311da177e4SLinus Torvalds 25320e1c54c2SIlpo Järvinen } else { 2533618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 25340e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 25350e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 25360e1c54c2SIlpo Järvinen else 25370e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 25380e1c54c2SIlpo Järvinen } 25390e1c54c2SIlpo Järvinen 25400e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 254161eb55f4SIlpo Järvinen continue; 254240b215e5SPavel Emelyanov 254324ab6becSYuchung Cheng if (tcp_retransmit_skb(sk, skb)) 25441da177e4SLinus Torvalds return; 254524ab6becSYuchung Cheng 2546de0744afSPavel Emelyanov NET_INC_STATS_BH(sock_net(sk), mib_idx); 25471da177e4SLinus Torvalds 2548684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2549a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2550a262f0cdSNandita Dukkipati 2551fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2552463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 25533f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 25543f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 25551da177e4SLinus Torvalds } 25561da177e4SLinus Torvalds } 25571da177e4SLinus Torvalds 25581da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 25591da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 25601da177e4SLinus Torvalds */ 25611da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 25621da177e4SLinus Torvalds { 25631da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2564fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_write_queue_tail(sk); 25651da177e4SLinus Torvalds int mss_now; 25661da177e4SLinus Torvalds 25671da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 25681da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 25691da177e4SLinus Torvalds * and IP options. 25701da177e4SLinus Torvalds */ 25710c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 25721da177e4SLinus Torvalds 2573fe067e8aSDavid S. Miller if (tcp_send_head(sk) != NULL) { 25744de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; 25751da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 25761da177e4SLinus Torvalds tp->write_seq++; 25771da177e4SLinus Torvalds } else { 25781da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 25791da177e4SLinus Torvalds for (;;) { 2580aa133076SWu Fengguang skb = alloc_skb_fclone(MAX_TCP_HEADER, 2581aa133076SWu Fengguang sk->sk_allocation); 25821da177e4SLinus Torvalds if (skb) 25831da177e4SLinus Torvalds break; 25841da177e4SLinus Torvalds yield(); 25851da177e4SLinus Torvalds } 25861da177e4SLinus Torvalds 25871da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 25881da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 25891da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 2590e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 2591a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 25921da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 25931da177e4SLinus Torvalds } 25949e412ba7SIlpo Järvinen __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); 25951da177e4SLinus Torvalds } 25961da177e4SLinus Torvalds 25971da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 25981da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 25991da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 260065bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 26011da177e4SLinus Torvalds */ 2602dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 26031da177e4SLinus Torvalds { 26041da177e4SLinus Torvalds struct sk_buff *skb; 26051da177e4SLinus Torvalds 26061da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 26071da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 26081da177e4SLinus Torvalds if (!skb) { 26094e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 26101da177e4SLinus Torvalds return; 26111da177e4SLinus Torvalds } 26121da177e4SLinus Torvalds 26131da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 26141da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 2615e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 2616a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 26171da177e4SLinus Torvalds /* Send it off. */ 26181da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2619dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 26204e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 262126af65cbSSridhar Samudrala 262281cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 26231da177e4SLinus Torvalds } 26241da177e4SLinus Torvalds 262567edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 262667edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 26271da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 26281da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 26291da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 26301da177e4SLinus Torvalds */ 26311da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 26321da177e4SLinus Torvalds { 26331da177e4SLinus Torvalds struct sk_buff *skb; 26341da177e4SLinus Torvalds 2635fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 26364de075e0SEric Dumazet if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 263791df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 26381da177e4SLinus Torvalds return -EFAULT; 26391da177e4SLinus Torvalds } 26404de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 26411da177e4SLinus Torvalds if (skb_cloned(skb)) { 26421da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 26431da177e4SLinus Torvalds if (nskb == NULL) 26441da177e4SLinus Torvalds return -ENOMEM; 2645fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 26461da177e4SLinus Torvalds skb_header_release(nskb); 2647fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 26483ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 26493ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 26503ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 26511da177e4SLinus Torvalds skb = nskb; 26521da177e4SLinus Torvalds } 26531da177e4SLinus Torvalds 26544de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 26551da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 26561da177e4SLinus Torvalds } 26571da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2658dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 26591da177e4SLinus Torvalds } 26601da177e4SLinus Torvalds 26614aea39c1SEric Dumazet /** 26624aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 26634aea39c1SEric Dumazet * sk: listener socket 26644aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 26654aea39c1SEric Dumazet * req: request_sock pointer 26664aea39c1SEric Dumazet * 26674aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 26684aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 26694aea39c1SEric Dumazet */ 26701da177e4SLinus Torvalds struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 2671e6b4d113SWilliam Allen Simpson struct request_sock *req, 26728336886fSJerry Chu struct tcp_fastopen_cookie *foc) 26731da177e4SLinus Torvalds { 2674bd0388aeSWilliam Allen Simpson struct tcp_out_options opts; 26752e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 26761da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 26771da177e4SLinus Torvalds struct tcphdr *th; 26781da177e4SLinus Torvalds struct sk_buff *skb; 2679cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 2680bd0388aeSWilliam Allen Simpson int tcp_header_size; 2681f5fff5dcSTom Quetchenbach int mss; 26821da177e4SLinus Torvalds 2683eb8895deSPhil Oester skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); 26844aea39c1SEric Dumazet if (unlikely(!skb)) { 26854aea39c1SEric Dumazet dst_release(dst); 26861da177e4SLinus Torvalds return NULL; 26874aea39c1SEric Dumazet } 26881da177e4SLinus Torvalds /* Reserve space for headers. */ 26891da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 26901da177e4SLinus Torvalds 26914aea39c1SEric Dumazet skb_dst_set(skb, dst); 2692ca10b9e9SEric Dumazet security_skb_owned_by(skb, sk); 26931da177e4SLinus Torvalds 26940dbaee3bSDavid S. Miller mss = dst_metric_advmss(dst); 2695f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) 2696f5fff5dcSTom Quetchenbach mss = tp->rx_opt.user_mss; 2697f5fff5dcSTom Quetchenbach 269833ad798cSAdam Langley if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ 269933ad798cSAdam Langley __u8 rcv_wscale; 270033ad798cSAdam Langley /* Set this up on the first call only */ 270133ad798cSAdam Langley req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); 2702e88c64f0SHagen Paul Pfeifer 2703e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 2704e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 2705e88c64f0SHagen Paul Pfeifer (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0)) 2706e88c64f0SHagen Paul Pfeifer req->window_clamp = tcp_full_space(sk); 2707e88c64f0SHagen Paul Pfeifer 270833ad798cSAdam Langley /* tcp_full_space because it is guaranteed to be the first packet */ 270933ad798cSAdam Langley tcp_select_initial_window(tcp_full_space(sk), 2710f5fff5dcSTom Quetchenbach mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), 271133ad798cSAdam Langley &req->rcv_wnd, 271233ad798cSAdam Langley &req->window_clamp, 271333ad798cSAdam Langley ireq->wscale_ok, 271431d12926Slaurent chavey &rcv_wscale, 271531d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 271633ad798cSAdam Langley ireq->rcv_wscale = rcv_wscale; 271733ad798cSAdam Langley } 2718cfb6eeb4SYOSHIFUJI Hideaki 271933ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 27208b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 27218b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 27228b5f12d0SFlorian Westphal TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); 27238b5f12d0SFlorian Westphal else 27248b5f12d0SFlorian Westphal #endif 272533ad798cSAdam Langley TCP_SKB_CB(skb)->when = tcp_time_stamp; 27261a2c6181SChristoph Paasch tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5, 27271a2c6181SChristoph Paasch foc) + sizeof(*th); 272833ad798cSAdam Langley 2729aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 2730aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 27311da177e4SLinus Torvalds 2732aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 27331da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 27341da177e4SLinus Torvalds th->syn = 1; 27351da177e4SLinus Torvalds th->ack = 1; 27361da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 2737a3116ac5SKOVACS Krisztian th->source = ireq->loc_port; 27382e6599cbSArnaldo Carvalho de Melo th->dest = ireq->rmt_port; 2739e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 2740e870a8efSIlpo Järvinen * not even correctly set) 2741e870a8efSIlpo Järvinen */ 2742e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 2743a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 27444957faadSWilliam Allen Simpson 27451da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 27468336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 27478336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 2750600ff0c2SIlpo Järvinen th->window = htons(min(req->rcv_wnd, 65535U)); 2751bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 27521da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 2753aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb)); 2754cfb6eeb4SYOSHIFUJI Hideaki 2755cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2756cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 2757cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 2758bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 275949a72dfbSAdam Langley md5, NULL, req, skb); 2760cfb6eeb4SYOSHIFUJI Hideaki } 2761cfb6eeb4SYOSHIFUJI Hideaki #endif 2762cfb6eeb4SYOSHIFUJI Hideaki 27631da177e4SLinus Torvalds return skb; 27641da177e4SLinus Torvalds } 27654bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 27661da177e4SLinus Torvalds 276767edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 2768370816aeSPavel Emelyanov void tcp_connect_init(struct sock *sk) 27691da177e4SLinus Torvalds { 2770cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 27711da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27721da177e4SLinus Torvalds __u8 rcv_wscale; 27731da177e4SLinus Torvalds 27741da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 27751da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 27761da177e4SLinus Torvalds */ 27771da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 2778bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 27791da177e4SLinus Torvalds 2780cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2781cfb6eeb4SYOSHIFUJI Hideaki if (tp->af_specific->md5_lookup(sk, sk) != NULL) 2782cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 2783cfb6eeb4SYOSHIFUJI Hideaki #endif 2784cfb6eeb4SYOSHIFUJI Hideaki 27851da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 27861da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 27871da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 27881da177e4SLinus Torvalds tp->max_window = 0; 27895d424d5aSJohn Heffner tcp_mtup_init(sk); 27901da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 27911da177e4SLinus Torvalds 27921da177e4SLinus Torvalds if (!tp->window_clamp) 27931da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 27940dbaee3bSDavid S. Miller tp->advmss = dst_metric_advmss(dst); 2795f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 2796f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 2797f5fff5dcSTom Quetchenbach 27981da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 27991da177e4SLinus Torvalds 2800e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 2801e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 2802e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 2803e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 2804e88c64f0SHagen Paul Pfeifer 28051da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 28061da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 28071da177e4SLinus Torvalds &tp->rcv_wnd, 28081da177e4SLinus Torvalds &tp->window_clamp, 2809bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 281031d12926Slaurent chavey &rcv_wscale, 281131d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 28121da177e4SLinus Torvalds 28131da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 28141da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds sk->sk_err = 0; 28171da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 28181da177e4SLinus Torvalds tp->snd_wnd = 0; 2819ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 28201da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 28211da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 282233f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 2823370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 2824ee995283SPavel Emelyanov 2825ee995283SPavel Emelyanov if (likely(!tp->repair)) 28261da177e4SLinus Torvalds tp->rcv_nxt = 0; 2827c7781a6eSAndrew Vagin else 2828c7781a6eSAndrew Vagin tp->rcv_tstamp = tcp_time_stamp; 2829ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 2830ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 28311da177e4SLinus Torvalds 2832463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 2833463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 28341da177e4SLinus Torvalds tcp_clear_retrans(tp); 28351da177e4SLinus Torvalds } 28361da177e4SLinus Torvalds 2837783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 2838783237e8SYuchung Cheng { 2839783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 2840783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 2841783237e8SYuchung Cheng 2842783237e8SYuchung Cheng tcb->end_seq += skb->len; 2843783237e8SYuchung Cheng skb_header_release(skb); 2844783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 2845783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 2846783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 2847783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 2848783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 2849783237e8SYuchung Cheng } 2850783237e8SYuchung Cheng 2851783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 2852783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 2853783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 2854783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 2855783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 2856783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 2857783237e8SYuchung Cheng */ 2858783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 2859783237e8SYuchung Cheng { 2860783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 2861783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 2862aab48743SYuchung Cheng int syn_loss = 0, space, i, err = 0, iovlen = fo->data->msg_iovlen; 2863783237e8SYuchung Cheng struct sk_buff *syn_data = NULL, *data; 2864aab48743SYuchung Cheng unsigned long last_syn_loss = 0; 2865783237e8SYuchung Cheng 286667da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 2867aab48743SYuchung Cheng tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, 2868aab48743SYuchung Cheng &syn_loss, &last_syn_loss); 2869aab48743SYuchung Cheng /* Recurring FO SYN losses: revert to regular handshake temporarily */ 2870aab48743SYuchung Cheng if (syn_loss > 1 && 2871aab48743SYuchung Cheng time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { 2872aab48743SYuchung Cheng fo->cookie.len = -1; 2873aab48743SYuchung Cheng goto fallback; 2874aab48743SYuchung Cheng } 2875aab48743SYuchung Cheng 287667da22d2SYuchung Cheng if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) 287767da22d2SYuchung Cheng fo->cookie.len = -1; 287867da22d2SYuchung Cheng else if (fo->cookie.len <= 0) 2879783237e8SYuchung Cheng goto fallback; 2880783237e8SYuchung Cheng 2881783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 2882783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 2883783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 2884783237e8SYuchung Cheng */ 2885783237e8SYuchung Cheng if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) 2886783237e8SYuchung Cheng tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 28871b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 2888783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 2889783237e8SYuchung Cheng 2890783237e8SYuchung Cheng syn_data = skb_copy_expand(syn, skb_headroom(syn), space, 2891783237e8SYuchung Cheng sk->sk_allocation); 2892783237e8SYuchung Cheng if (syn_data == NULL) 2893783237e8SYuchung Cheng goto fallback; 2894783237e8SYuchung Cheng 2895783237e8SYuchung Cheng for (i = 0; i < iovlen && syn_data->len < space; ++i) { 2896783237e8SYuchung Cheng struct iovec *iov = &fo->data->msg_iov[i]; 2897783237e8SYuchung Cheng unsigned char __user *from = iov->iov_base; 2898783237e8SYuchung Cheng int len = iov->iov_len; 2899783237e8SYuchung Cheng 2900783237e8SYuchung Cheng if (syn_data->len + len > space) 2901783237e8SYuchung Cheng len = space - syn_data->len; 2902783237e8SYuchung Cheng else if (i + 1 == iovlen) 2903783237e8SYuchung Cheng /* No more data pending in inet_wait_for_connect() */ 2904783237e8SYuchung Cheng fo->data = NULL; 2905783237e8SYuchung Cheng 2906783237e8SYuchung Cheng if (skb_add_data(syn_data, from, len)) 2907783237e8SYuchung Cheng goto fallback; 2908783237e8SYuchung Cheng } 2909783237e8SYuchung Cheng 2910783237e8SYuchung Cheng /* Queue a data-only packet after the regular SYN for retransmission */ 2911783237e8SYuchung Cheng data = pskb_copy(syn_data, sk->sk_allocation); 2912783237e8SYuchung Cheng if (data == NULL) 2913783237e8SYuchung Cheng goto fallback; 2914783237e8SYuchung Cheng TCP_SKB_CB(data)->seq++; 2915783237e8SYuchung Cheng TCP_SKB_CB(data)->tcp_flags &= ~TCPHDR_SYN; 2916783237e8SYuchung Cheng TCP_SKB_CB(data)->tcp_flags = (TCPHDR_ACK|TCPHDR_PSH); 2917783237e8SYuchung Cheng tcp_connect_queue_skb(sk, data); 2918783237e8SYuchung Cheng fo->copied = data->len; 2919783237e8SYuchung Cheng 2920783237e8SYuchung Cheng if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) { 292167da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 2922783237e8SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVE); 2923783237e8SYuchung Cheng goto done; 2924783237e8SYuchung Cheng } 2925783237e8SYuchung Cheng syn_data = NULL; 2926783237e8SYuchung Cheng 2927783237e8SYuchung Cheng fallback: 2928783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 2929783237e8SYuchung Cheng if (fo->cookie.len > 0) 2930783237e8SYuchung Cheng fo->cookie.len = 0; 2931783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 2932783237e8SYuchung Cheng if (err) 2933783237e8SYuchung Cheng tp->syn_fastopen = 0; 2934783237e8SYuchung Cheng kfree_skb(syn_data); 2935783237e8SYuchung Cheng done: 2936783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 2937783237e8SYuchung Cheng return err; 2938783237e8SYuchung Cheng } 2939783237e8SYuchung Cheng 294067edfef7SAndi Kleen /* Build a SYN and send it off. */ 29411da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 29421da177e4SLinus Torvalds { 29431da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 29441da177e4SLinus Torvalds struct sk_buff *buff; 2945ee586811SEric Paris int err; 29461da177e4SLinus Torvalds 29471da177e4SLinus Torvalds tcp_connect_init(sk); 29481da177e4SLinus Torvalds 29492b916477SAndrey Vagin if (unlikely(tp->repair)) { 29502b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 29512b916477SAndrey Vagin return 0; 29522b916477SAndrey Vagin } 29532b916477SAndrey Vagin 2954d179cd12SDavid S. Miller buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); 29551da177e4SLinus Torvalds if (unlikely(buff == NULL)) 29561da177e4SLinus Torvalds return -ENOBUFS; 29571da177e4SLinus Torvalds 29581da177e4SLinus Torvalds /* Reserve space for headers. */ 29591da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 29601da177e4SLinus Torvalds 2961a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 2962783237e8SYuchung Cheng tp->retrans_stamp = TCP_SKB_CB(buff)->when = tcp_time_stamp; 2963783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 2964e870a8efSIlpo Järvinen TCP_ECN_send_syn(sk, buff); 29651da177e4SLinus Torvalds 2966783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 2967783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 2968783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 2969ee586811SEric Paris if (err == -ECONNREFUSED) 2970ee586811SEric Paris return err; 2971bd37a088SWei Yongjun 2972bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 2973bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 2974bd37a088SWei Yongjun */ 2975bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 2976bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 297781cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 29781da177e4SLinus Torvalds 29791da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 29803f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 29813f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 29821da177e4SLinus Torvalds return 0; 29831da177e4SLinus Torvalds } 29844bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 29851da177e4SLinus Torvalds 29861da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 29871da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 29881da177e4SLinus Torvalds * for details. 29891da177e4SLinus Torvalds */ 29901da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 29911da177e4SLinus Torvalds { 2992463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 2993463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 29941da177e4SLinus Torvalds unsigned long timeout; 29951da177e4SLinus Torvalds 29961da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 2997463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 29981da177e4SLinus Torvalds int max_ato = HZ / 2; 29991da177e4SLinus Torvalds 3000056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3001056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 30021da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 30031da177e4SLinus Torvalds 30041da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 30051da177e4SLinus Torvalds 30061da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3007463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 30081da177e4SLinus Torvalds * directly. 30091da177e4SLinus Torvalds */ 30101da177e4SLinus Torvalds if (tp->srtt) { 30111da177e4SLinus Torvalds int rtt = max(tp->srtt >> 3, TCP_DELACK_MIN); 30121da177e4SLinus Torvalds 30131da177e4SLinus Torvalds if (rtt < max_ato) 30141da177e4SLinus Torvalds max_ato = rtt; 30151da177e4SLinus Torvalds } 30161da177e4SLinus Torvalds 30171da177e4SLinus Torvalds ato = min(ato, max_ato); 30181da177e4SLinus Torvalds } 30191da177e4SLinus Torvalds 30201da177e4SLinus Torvalds /* Stay within the limit we were given */ 30211da177e4SLinus Torvalds timeout = jiffies + ato; 30221da177e4SLinus Torvalds 30231da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3024463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 30251da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 30261da177e4SLinus Torvalds * send ACK now. 30271da177e4SLinus Torvalds */ 3028463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3029463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 30301da177e4SLinus Torvalds tcp_send_ack(sk); 30311da177e4SLinus Torvalds return; 30321da177e4SLinus Torvalds } 30331da177e4SLinus Torvalds 3034463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3035463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 30361da177e4SLinus Torvalds } 3037463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3038463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3039463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 30401da177e4SLinus Torvalds } 30411da177e4SLinus Torvalds 30421da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 30431da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 30441da177e4SLinus Torvalds { 30451da177e4SLinus Torvalds struct sk_buff *buff; 30461da177e4SLinus Torvalds 3047058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3048058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3049058dc334SIlpo Järvinen return; 3050058dc334SIlpo Järvinen 30511da177e4SLinus Torvalds /* We are not putting this on the write queue, so 30521da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 30531da177e4SLinus Torvalds * sock. 30541da177e4SLinus Torvalds */ 305599a1dec7SMel Gorman buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); 30561da177e4SLinus Torvalds if (buff == NULL) { 3057463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3058463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 30593f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 30603f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 30611da177e4SLinus Torvalds return; 30621da177e4SLinus Torvalds } 30631da177e4SLinus Torvalds 30641da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 30651da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3066a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 30671da177e4SLinus Torvalds 30681da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 30691da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 307099a1dec7SMel Gorman tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); 30711da177e4SLinus Torvalds } 30721da177e4SLinus Torvalds 30731da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 30741da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 30751da177e4SLinus Torvalds * 30761da177e4SLinus Torvalds * Question: what should we make while urgent mode? 30771da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 30781da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 30791da177e4SLinus Torvalds * 30801da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 30811da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 30821da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 30831da177e4SLinus Torvalds */ 30841da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 30851da177e4SLinus Torvalds { 30861da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 30871da177e4SLinus Torvalds struct sk_buff *skb; 30881da177e4SLinus Torvalds 30891da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 309099a1dec7SMel Gorman skb = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); 30911da177e4SLinus Torvalds if (skb == NULL) 30921da177e4SLinus Torvalds return -1; 30931da177e4SLinus Torvalds 30941da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 30951da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 30961da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 30971da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 30981da177e4SLinus Torvalds * send it. 30991da177e4SLinus Torvalds */ 3100a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 31011da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 3102dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); 31031da177e4SLinus Torvalds } 31041da177e4SLinus Torvalds 3105ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3106ee995283SPavel Emelyanov { 3107ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3108ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 3109c0e88ff0SPavel Emelyanov tcp_sk(sk)->snd_nxt = tcp_sk(sk)->write_seq; 3110ee995283SPavel Emelyanov tcp_xmit_probe_skb(sk, 0); 3111ee995283SPavel Emelyanov } 3112ee995283SPavel Emelyanov } 3113ee995283SPavel Emelyanov 311467edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 31151da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 31161da177e4SLinus Torvalds { 31171da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 31181da177e4SLinus Torvalds struct sk_buff *skb; 31191da177e4SLinus Torvalds 3120058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3121058dc334SIlpo Järvinen return -1; 3122058dc334SIlpo Järvinen 3123fe067e8aSDavid S. Miller if ((skb = tcp_send_head(sk)) != NULL && 312490840defSIlpo Järvinen before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 31251da177e4SLinus Torvalds int err; 31260c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 312790840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 31281da177e4SLinus Torvalds 31291da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 31301da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 31311da177e4SLinus Torvalds 31321da177e4SLinus Torvalds /* We are probing the opening of a window 31331da177e4SLinus Torvalds * but the window size is != 0 31341da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 31351da177e4SLinus Torvalds */ 31361da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 31371da177e4SLinus Torvalds skb->len > mss) { 31381da177e4SLinus Torvalds seg_size = min(seg_size, mss); 31394de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3140846998aeSDavid S. Miller if (tcp_fragment(sk, skb, seg_size, mss)) 31411da177e4SLinus Torvalds return -1; 31421da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 3143846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 31441da177e4SLinus Torvalds 31454de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 31461da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 3147dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 314866f5fe62SIlpo Järvinen if (!err) 314966f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 31501da177e4SLinus Torvalds return err; 31511da177e4SLinus Torvalds } else { 315233f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 31534828e7f4SIlpo Järvinen tcp_xmit_probe_skb(sk, 1); 31541da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 31551da177e4SLinus Torvalds } 31561da177e4SLinus Torvalds } 31571da177e4SLinus Torvalds 31581da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 31591da177e4SLinus Torvalds * a partial packet else a zero probe. 31601da177e4SLinus Torvalds */ 31611da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 31621da177e4SLinus Torvalds { 3163463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 31641da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 31651da177e4SLinus Torvalds int err; 31661da177e4SLinus Torvalds 31671da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 31681da177e4SLinus Torvalds 3169fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 31701da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 31716687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3172463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 31731da177e4SLinus Torvalds return; 31741da177e4SLinus Torvalds } 31751da177e4SLinus Torvalds 31761da177e4SLinus Torvalds if (err <= 0) { 3177463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_backoff < sysctl_tcp_retries2) 3178463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 31796687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3180463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 31813f421baaSArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), 31823f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 31831da177e4SLinus Torvalds } else { 31841da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 31856687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 31861da177e4SLinus Torvalds * Let local senders to fight for local resources. 31871da177e4SLinus Torvalds * 31881da177e4SLinus Torvalds * Use accumulated backoff yet. 31891da177e4SLinus Torvalds */ 31906687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 31916687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3192463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 3193463c84b9SArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, 31943f421baaSArnaldo Carvalho de Melo TCP_RESOURCE_PROBE_INTERVAL), 31953f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 31961da177e4SLinus Torvalds } 31971da177e4SLinus Torvalds } 3198