11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 31da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 41da177e4SLinus Torvalds * interface as the means of communication with the user level. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 71da177e4SLinus Torvalds * 802c30a84SJesper Juhl * Authors: Ross Biro 91da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 101da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 111da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 121da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 131da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 141da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 151da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 161da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 171da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 181da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds /* 221da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 231da177e4SLinus Torvalds * : Fragmentation on mtu decrease 241da177e4SLinus Torvalds * : Segment collapse on retransmit 251da177e4SLinus Torvalds * : AF independence 261da177e4SLinus Torvalds * 271da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 281da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 291da177e4SLinus Torvalds * during syn/ack processing. 301da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 311da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 321da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 331da177e4SLinus Torvalds * J Hadi Salim : ECN support 341da177e4SLinus Torvalds * 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds 3791df42beSJoe Perches #define pr_fmt(fmt) "TCP: " fmt 3891df42beSJoe Perches 391da177e4SLinus Torvalds #include <net/tcp.h> 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds #include <linux/compiler.h> 425a0e3ad6STejun Heo #include <linux/gfp.h> 431da177e4SLinus Torvalds #include <linux/module.h> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 46ab32ea5dSBrian Haley int sysctl_tcp_retrans_collapse __read_mostly = 1; 471da177e4SLinus Torvalds 4815d99e02SRick Jones /* People can turn this on to work with those rare, broken TCPs that 4915d99e02SRick Jones * interpret the window field as a signed quantity. 5015d99e02SRick Jones */ 51ab32ea5dSBrian Haley int sysctl_tcp_workaround_signed_windows __read_mostly = 0; 5215d99e02SRick Jones 53c39c4c6aSWei Liu /* Default TSQ limit of four TSO segments */ 54c39c4c6aSWei Liu int sysctl_tcp_limit_output_bytes __read_mostly = 262144; 5546d3ceabSEric Dumazet 561da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 571da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 581da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 591da177e4SLinus Torvalds */ 60ab32ea5dSBrian Haley int sysctl_tcp_tso_win_divisor __read_mostly = 3; 611da177e4SLinus Torvalds 6235089bb2SDavid S. Miller /* By default, RFC2861 behavior. */ 63ab32ea5dSBrian Haley int sysctl_tcp_slow_start_after_idle __read_mostly = 1; 6435089bb2SDavid S. Miller 6546d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6646d3ceabSEric Dumazet int push_one, gfp_t gfp); 67519855c5SWilliam Allen Simpson 6867edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 69cf533ea5SEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) 706ff03ac3SIlpo Järvinen { 716ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 726ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7366f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 749e412ba7SIlpo Järvinen 75fe067e8aSDavid S. Miller tcp_advance_send_head(sk, skb); 761da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 778512430eSIlpo Järvinen 7866f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 796ba8a3b1SNandita Dukkipati if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || 806a5dc9e5SEric Dumazet icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { 81750ea2baSYuchung Cheng tcp_rearm_rto(sk); 821da177e4SLinus Torvalds } 83f19c29e3SYuchung Cheng 84f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 85f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 866a5dc9e5SEric Dumazet } 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 891da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 901da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 911da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 921da177e4SLinus Torvalds * invalid. OK, let's make this for now: 931da177e4SLinus Torvalds */ 94cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 951da177e4SLinus Torvalds { 96cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 979e412ba7SIlpo Järvinen 9890840defSIlpo Järvinen if (!before(tcp_wnd_end(tp), tp->snd_nxt)) 991da177e4SLinus Torvalds return tp->snd_nxt; 1001da177e4SLinus Torvalds else 10190840defSIlpo Järvinen return tcp_wnd_end(tp); 1021da177e4SLinus Torvalds } 1031da177e4SLinus Torvalds 1041da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1051da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1061da177e4SLinus Torvalds * 1071da177e4SLinus Torvalds * 1. It is independent of path mtu. 1081da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1091da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1101da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1111da177e4SLinus Torvalds * large MSS. 1121da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1131da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1141da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1151da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1161da177e4SLinus Torvalds * probably even Jumbo". 1171da177e4SLinus Torvalds */ 1181da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1191da177e4SLinus Torvalds { 1201da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 121cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1221da177e4SLinus Torvalds int mss = tp->advmss; 1231da177e4SLinus Torvalds 1240dbaee3bSDavid S. Miller if (dst) { 1250dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1260dbaee3bSDavid S. Miller 1270dbaee3bSDavid S. Miller if (metric < mss) { 1280dbaee3bSDavid S. Miller mss = metric; 1291da177e4SLinus Torvalds tp->advmss = mss; 1301da177e4SLinus Torvalds } 1310dbaee3bSDavid S. Miller } 1321da177e4SLinus Torvalds 1331da177e4SLinus Torvalds return (__u16)mss; 1341da177e4SLinus Torvalds } 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1376f021c62SEric Dumazet * This is the first part of cwnd validation mechanism. 1386f021c62SEric Dumazet */ 1396f021c62SEric Dumazet void tcp_cwnd_restart(struct sock *sk, s32 delta) 1401da177e4SLinus Torvalds { 141463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1426f021c62SEric Dumazet u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); 1431da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1441da177e4SLinus Torvalds 1456687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1461da177e4SLinus Torvalds 1476687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1481da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1491da177e4SLinus Torvalds 150463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1511da177e4SLinus Torvalds cwnd >>= 1; 1521da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1531da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1541da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1551da177e4SLinus Torvalds } 1561da177e4SLinus Torvalds 15767edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 15840efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 159cf533ea5SEric Dumazet struct sock *sk) 1601da177e4SLinus Torvalds { 161463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 162463c84b9SArnaldo Carvalho de Melo const u32 now = tcp_time_stamp; 1631da177e4SLinus Torvalds 16405c5a46dSNeal Cardwell if (tcp_packets_in_flight(tp) == 0) 16505c5a46dSNeal Cardwell tcp_ca_event(sk, CA_EVENT_TX_START); 16605c5a46dSNeal Cardwell 1671da177e4SLinus Torvalds tp->lsndtime = now; 1681da177e4SLinus Torvalds 1691da177e4SLinus Torvalds /* If it is a reply for ato after last received 1701da177e4SLinus Torvalds * packet, enter pingpong mode. 1711da177e4SLinus Torvalds */ 1722251ae46SJon Maxwell if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 173463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1741da177e4SLinus Torvalds } 1751da177e4SLinus Torvalds 17667edfef7SAndi Kleen /* Account for an ACK we sent. */ 17740efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1781da177e4SLinus Torvalds { 179463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 180463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1811da177e4SLinus Torvalds } 1821da177e4SLinus Torvalds 18385f16525SYuchung Cheng 18485f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 18585f16525SYuchung Cheng { 18685f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 1879ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 18885f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 18985f16525SYuchung Cheng * limit when mss is larger than 1460. 19085f16525SYuchung Cheng */ 19185f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 19285f16525SYuchung Cheng 19385f16525SYuchung Cheng if (mss > 1460) 19485f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 19585f16525SYuchung Cheng return init_rwnd; 19685f16525SYuchung Cheng } 19785f16525SYuchung Cheng 1981da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 1991da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2001da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2011da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2021da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2031da177e4SLinus Torvalds * This MUST be enforced by all callers. 2041da177e4SLinus Torvalds */ 2051da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 2061da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 20731d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 20831d12926Slaurent chavey __u32 init_rcv_wnd) 2091da177e4SLinus Torvalds { 2101da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2131da177e4SLinus Torvalds if (*window_clamp == 0) 2141da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 2151da177e4SLinus Torvalds space = min(*window_clamp, space); 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2181da177e4SLinus Torvalds if (space > mss) 2191da177e4SLinus Torvalds space = (space / mss) * mss; 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22215d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22315d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 22415d99e02SRick Jones * we will truncate our initial window offering to 32K-1 22515d99e02SRick Jones * unless the remote has sent us a window scaling option, 22615d99e02SRick Jones * which we interpret as a sign the remote TCP is not 22715d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2281da177e4SLinus Torvalds */ 22915d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2301da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23115d99e02SRick Jones else 23215d99e02SRick Jones (*rcv_wnd) = space; 23315d99e02SRick Jones 2341da177e4SLinus Torvalds (*rcv_wscale) = 0; 2351da177e4SLinus Torvalds if (wscale_ok) { 2361da177e4SLinus Torvalds /* Set window scaling on max possible window 2371da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 2381da177e4SLinus Torvalds */ 239f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_tcp_rmem[2]); 240f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_rmem_max); 241316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 2421da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 2431da177e4SLinus Torvalds space >>= 1; 2441da177e4SLinus Torvalds (*rcv_wscale)++; 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds } 2471da177e4SLinus Torvalds 2481da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 24985f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 25085f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 251b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2551da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2561da177e4SLinus Torvalds } 2574bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2601da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2611da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2621da177e4SLinus Torvalds * frame. 2631da177e4SLinus Torvalds */ 26440efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2651da177e4SLinus Torvalds { 2661da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2678e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2681da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2691da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds /* Never shrink the offered window */ 2721da177e4SLinus Torvalds if (new_win < cur_win) { 2731da177e4SLinus Torvalds /* Danger Will Robinson! 2741da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2751da177e4SLinus Torvalds * we will not be able to advertise a zero 2761da177e4SLinus Torvalds * window in time. --DaveM 2771da177e4SLinus Torvalds * 2781da177e4SLinus Torvalds * Relax Will Robinson. 2791da177e4SLinus Torvalds */ 2808e165e20SFlorian Westphal if (new_win == 0) 2818e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2828e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 283607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2841da177e4SLinus Torvalds } 2851da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2861da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2891da177e4SLinus Torvalds * scaled window. 2901da177e4SLinus Torvalds */ 29115d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2921da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2931da177e4SLinus Torvalds else 2941da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2951da177e4SLinus Torvalds 2961da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2971da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 3008e165e20SFlorian Westphal if (new_win == 0) { 3011da177e4SLinus Torvalds tp->pred_flags = 0; 3028e165e20SFlorian Westphal if (old_win) 3038e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3048e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3058e165e20SFlorian Westphal } else if (old_win == 0) { 3068e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3078e165e20SFlorian Westphal } 3081da177e4SLinus Torvalds 3091da177e4SLinus Torvalds return new_win; 3101da177e4SLinus Torvalds } 3111da177e4SLinus Torvalds 31267edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 313735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 314bdf1ee5dSIlpo Järvinen { 31530e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 31630e502a3SDaniel Borkmann 3174de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 318bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3194de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 32030e502a3SDaniel Borkmann else if (tcp_ca_needs_ecn(sk)) 32130e502a3SDaniel Borkmann INET_ECN_xmit(sk); 322bdf1ee5dSIlpo Järvinen } 323bdf1ee5dSIlpo Järvinen 32467edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 325735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 326bdf1ee5dSIlpo Järvinen { 327bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 328f7b3bec6SFlorian Westphal bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || 329f7b3bec6SFlorian Westphal tcp_ca_needs_ecn(sk); 330f7b3bec6SFlorian Westphal 331f7b3bec6SFlorian Westphal if (!use_ecn) { 332f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 333f7b3bec6SFlorian Westphal 334f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 335f7b3bec6SFlorian Westphal use_ecn = true; 336f7b3bec6SFlorian Westphal } 337bdf1ee5dSIlpo Järvinen 338bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 339f7b3bec6SFlorian Westphal 340f7b3bec6SFlorian Westphal if (use_ecn) { 3414de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 342bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 34330e502a3SDaniel Borkmann if (tcp_ca_needs_ecn(sk)) 34430e502a3SDaniel Borkmann INET_ECN_xmit(sk); 345bdf1ee5dSIlpo Järvinen } 346bdf1ee5dSIlpo Järvinen } 347bdf1ee5dSIlpo Järvinen 34849213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 34949213555SDaniel Borkmann { 35049213555SDaniel Borkmann if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) 35149213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 35249213555SDaniel Borkmann * SYN ACK is ultimatively being received. 35349213555SDaniel Borkmann */ 35449213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 35549213555SDaniel Borkmann } 35649213555SDaniel Borkmann 357735d3831SFlorian Westphal static void 3586ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 359bdf1ee5dSIlpo Järvinen { 3606ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 361bdf1ee5dSIlpo Järvinen th->ece = 1; 362bdf1ee5dSIlpo Järvinen } 363bdf1ee5dSIlpo Järvinen 36467edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 36567edfef7SAndi Kleen * be sent. 36667edfef7SAndi Kleen */ 367735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 368ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 369bdf1ee5dSIlpo Järvinen { 370bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 371bdf1ee5dSIlpo Järvinen 372bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 373bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 374bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 375bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 376bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 377bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 378bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 379ea1627c2SEric Dumazet th->cwr = 1; 380bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 381bdf1ee5dSIlpo Järvinen } 38230e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 383bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 384bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 385bdf1ee5dSIlpo Järvinen } 386bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 387ea1627c2SEric Dumazet th->ece = 1; 388bdf1ee5dSIlpo Järvinen } 389bdf1ee5dSIlpo Järvinen } 390bdf1ee5dSIlpo Järvinen 391e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 392e870a8efSIlpo Järvinen * auto increment end seqno. 393e870a8efSIlpo Järvinen */ 394e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 395e870a8efSIlpo Järvinen { 3962e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 397e870a8efSIlpo Järvinen skb->csum = 0; 398e870a8efSIlpo Järvinen 3994de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 400e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 401e870a8efSIlpo Järvinen 402cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 403e870a8efSIlpo Järvinen 404e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 405a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 406e870a8efSIlpo Järvinen seq++; 407e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 408e870a8efSIlpo Järvinen } 409e870a8efSIlpo Järvinen 410a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 41133f5f57eSIlpo Järvinen { 41233f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41333f5f57eSIlpo Järvinen } 41433f5f57eSIlpo Järvinen 41533ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 41633ad798cSAdam Langley #define OPTION_TS (1 << 1) 41733ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 41889e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4192100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 42033ad798cSAdam Langley 42133ad798cSAdam Langley struct tcp_out_options { 4222100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4232100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 42433ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 42533ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 426bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 427bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4282100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4292100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 43033ad798cSAdam Langley }; 43133ad798cSAdam Langley 43267edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 43367edfef7SAndi Kleen * 43467edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 435fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 436fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4378e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 438fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 439fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 440fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 441fd6149d3SIlpo Järvinen * 442fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 443fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 444fd6149d3SIlpo Järvinen */ 44533ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 446bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 447bd0388aeSWilliam Allen Simpson { 4482100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 449bd0388aeSWilliam Allen Simpson 450bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4511a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4521a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 453bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 454bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 45533ad798cSAdam Langley ptr += 4; 45633ad798cSAdam Langley } 45733ad798cSAdam Langley 458fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 459fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 460fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 461fd6149d3SIlpo Järvinen opts->mss); 462fd6149d3SIlpo Järvinen } 463fd6149d3SIlpo Järvinen 464bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 465bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 46633ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 46733ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 46833ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 46933ad798cSAdam Langley TCPOLEN_TIMESTAMP); 470bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 47133ad798cSAdam Langley } else { 472496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 47340efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 47440efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 47540efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 47640efc6faSStephen Hemminger } 47733ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 47833ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 47933ad798cSAdam Langley } 48033ad798cSAdam Langley 481bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 48233ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 48333ad798cSAdam Langley (TCPOPT_NOP << 16) | 48433ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 48533ad798cSAdam Langley TCPOLEN_SACK_PERM); 48633ad798cSAdam Langley } 48733ad798cSAdam Langley 488bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 48933ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 49033ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 49133ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 49233ad798cSAdam Langley opts->ws); 49333ad798cSAdam Langley } 49433ad798cSAdam Langley 49533ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 49633ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 49733ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 49840efc6faSStephen Hemminger int this_sack; 49940efc6faSStephen Hemminger 50040efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 50140efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 50240efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 50333ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 50440efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5052de979bdSStephen Hemminger 50633ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 50733ad798cSAdam Langley ++this_sack) { 50840efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 50940efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 51040efc6faSStephen Hemminger } 5112de979bdSStephen Hemminger 51240efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 51340efc6faSStephen Hemminger } 5142100c8d2SYuchung Cheng 5152100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5162100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 5177f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 5187f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 5192100c8d2SYuchung Cheng 5207f9b838bSDaniel Lee if (foc->exp) { 5217f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 5227f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 5232100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 5247f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 5257f9b838bSDaniel Lee } else { 5267f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 5277f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 5287f9b838bSDaniel Lee *p++ = len; 5292100c8d2SYuchung Cheng } 5307f9b838bSDaniel Lee 5317f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 5327f9b838bSDaniel Lee if ((len & 3) == 2) { 5337f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 5347f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 5357f9b838bSDaniel Lee } 5367f9b838bSDaniel Lee ptr += (len + 3) >> 2; 5372100c8d2SYuchung Cheng } 53840efc6faSStephen Hemminger } 53940efc6faSStephen Hemminger 54067edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 54167edfef7SAndi Kleen * network wire format yet. 54267edfef7SAndi Kleen */ 54395c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 54433ad798cSAdam Langley struct tcp_out_options *opts, 545cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 546cf533ea5SEric Dumazet { 54733ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 54895c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 549783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 55033ad798cSAdam Langley 551cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 55233ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 55333ad798cSAdam Langley if (*md5) { 55433ad798cSAdam Langley opts->options |= OPTION_MD5; 555bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 556cfb6eeb4SYOSHIFUJI Hideaki } 55733ad798cSAdam Langley #else 55833ad798cSAdam Langley *md5 = NULL; 559cfb6eeb4SYOSHIFUJI Hideaki #endif 56033ad798cSAdam Langley 56133ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 56233ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 56333ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 56433ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 56533ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 56633ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 56733ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 56833ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 56933ad798cSAdam Langley * going out. */ 57033ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 571bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 57233ad798cSAdam Langley 57351456b29SIan Morris if (likely(sysctl_tcp_timestamps && !*md5)) { 57433ad798cSAdam Langley opts->options |= OPTION_TS; 5757faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 57633ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 577bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 57833ad798cSAdam Langley } 579bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_window_scaling)) { 58033ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 58189e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 582bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 58333ad798cSAdam Langley } 584bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_sack)) { 58533ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 586b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 587bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 58833ad798cSAdam Langley } 58933ad798cSAdam Langley 590783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 5912646c831SDaniel Lee u32 need = fastopen->cookie.len; 5922646c831SDaniel Lee 5932646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 5942646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 595783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 596783237e8SYuchung Cheng if (remaining >= need) { 597783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 598783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 599783237e8SYuchung Cheng remaining -= need; 600783237e8SYuchung Cheng tp->syn_fastopen = 1; 6012646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 602783237e8SYuchung Cheng } 603783237e8SYuchung Cheng } 604bd0388aeSWilliam Allen Simpson 605bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 60633ad798cSAdam Langley } 60733ad798cSAdam Langley 60867edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 60937bfbddaSEric Dumazet static unsigned int tcp_synack_options(struct request_sock *req, 61095c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 61133ad798cSAdam Langley struct tcp_out_options *opts, 61280f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 6138336886fSJerry Chu struct tcp_fastopen_cookie *foc) 6144957faadSWilliam Allen Simpson { 61533ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 61695c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 61733ad798cSAdam Langley 61833ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 61980f03e27SEric Dumazet if (md5) { 62033ad798cSAdam Langley opts->options |= OPTION_MD5; 6214957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6224957faadSWilliam Allen Simpson 6234957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6244957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6254957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6264957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6274957faadSWilliam Allen Simpson */ 628de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 62933ad798cSAdam Langley } 63033ad798cSAdam Langley #endif 63133ad798cSAdam Langley 6324957faadSWilliam Allen Simpson /* We always send an MSS option. */ 63333ad798cSAdam Langley opts->mss = mss; 6344957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 63533ad798cSAdam Langley 63633ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 63733ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 63889e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6394957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 64033ad798cSAdam Langley } 641de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 64233ad798cSAdam Langley opts->options |= OPTION_TS; 6437faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb); 64433ad798cSAdam Langley opts->tsecr = req->ts_recent; 6454957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 64633ad798cSAdam Langley } 64733ad798cSAdam Langley if (likely(ireq->sack_ok)) { 64833ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 649de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 6504957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 65133ad798cSAdam Langley } 6527f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 6537f9b838bSDaniel Lee u32 need = foc->len; 6547f9b838bSDaniel Lee 6557f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 6567f9b838bSDaniel Lee TCPOLEN_FASTOPEN_BASE; 6578336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 6588336886fSJerry Chu if (remaining >= need) { 6598336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 6608336886fSJerry Chu opts->fastopen_cookie = foc; 6618336886fSJerry Chu remaining -= need; 6628336886fSJerry Chu } 6638336886fSJerry Chu } 6644957faadSWilliam Allen Simpson 6654957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 66633ad798cSAdam Langley } 66733ad798cSAdam Langley 66867edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 66967edfef7SAndi Kleen * final wire format yet. 67067edfef7SAndi Kleen */ 67195c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 67233ad798cSAdam Langley struct tcp_out_options *opts, 673cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 674cf533ea5SEric Dumazet { 67533ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 67695c96174SEric Dumazet unsigned int size = 0; 677cabeccbdSIlpo Järvinen unsigned int eff_sacks; 67833ad798cSAdam Langley 6795843ef42SAndi Kleen opts->options = 0; 6805843ef42SAndi Kleen 68133ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 68233ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 68333ad798cSAdam Langley if (unlikely(*md5)) { 68433ad798cSAdam Langley opts->options |= OPTION_MD5; 68533ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 68633ad798cSAdam Langley } 68733ad798cSAdam Langley #else 68833ad798cSAdam Langley *md5 = NULL; 68933ad798cSAdam Langley #endif 69033ad798cSAdam Langley 69133ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 69233ad798cSAdam Langley opts->options |= OPTION_TS; 6937faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 69433ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 69533ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 69633ad798cSAdam Langley } 69733ad798cSAdam Langley 698cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 699cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 70095c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 70133ad798cSAdam Langley opts->num_sack_blocks = 70295c96174SEric Dumazet min_t(unsigned int, eff_sacks, 70333ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 70433ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 70533ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 70633ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 70733ad798cSAdam Langley } 70833ad798cSAdam Langley 70933ad798cSAdam Langley return size; 71040efc6faSStephen Hemminger } 7111da177e4SLinus Torvalds 71246d3ceabSEric Dumazet 71346d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 71446d3ceabSEric Dumazet * 71546d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 71646d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 71746d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 71846d3ceabSEric Dumazet * 71946d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 72046d3ceabSEric Dumazet * needs to be reallocated in a driver. 7218e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 72246d3ceabSEric Dumazet * 72346d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 72446d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 72546d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 72646d3ceabSEric Dumazet */ 72746d3ceabSEric Dumazet struct tsq_tasklet { 72846d3ceabSEric Dumazet struct tasklet_struct tasklet; 72946d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 73046d3ceabSEric Dumazet }; 73146d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 73246d3ceabSEric Dumazet 7336f458dfbSEric Dumazet static void tcp_tsq_handler(struct sock *sk) 7346f458dfbSEric Dumazet { 7356f458dfbSEric Dumazet if ((1 << sk->sk_state) & 7366f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 737f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 738f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 739f9616c35SEric Dumazet 740f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 741f9616c35SEric Dumazet tp->snd_cwnd > tcp_packets_in_flight(tp)) 742f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 743f9616c35SEric Dumazet 744f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 745bf06200eSJohn Ogness 0, GFP_ATOMIC); 7466f458dfbSEric Dumazet } 747f9616c35SEric Dumazet } 74846d3ceabSEric Dumazet /* 7498e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 75046d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 7518e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 75246d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 75346d3ceabSEric Dumazet */ 75446d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 75546d3ceabSEric Dumazet { 75646d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 75746d3ceabSEric Dumazet LIST_HEAD(list); 75846d3ceabSEric Dumazet unsigned long flags; 75946d3ceabSEric Dumazet struct list_head *q, *n; 76046d3ceabSEric Dumazet struct tcp_sock *tp; 76146d3ceabSEric Dumazet struct sock *sk; 76246d3ceabSEric Dumazet 76346d3ceabSEric Dumazet local_irq_save(flags); 76446d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 76546d3ceabSEric Dumazet local_irq_restore(flags); 76646d3ceabSEric Dumazet 76746d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 76846d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 76946d3ceabSEric Dumazet list_del(&tp->tsq_node); 77046d3ceabSEric Dumazet 77146d3ceabSEric Dumazet sk = (struct sock *)tp; 77246d3ceabSEric Dumazet bh_lock_sock(sk); 77346d3ceabSEric Dumazet 77446d3ceabSEric Dumazet if (!sock_owned_by_user(sk)) { 7756f458dfbSEric Dumazet tcp_tsq_handler(sk); 77646d3ceabSEric Dumazet } else { 77746d3ceabSEric Dumazet /* defer the work to tcp_release_cb() */ 7786f458dfbSEric Dumazet set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); 77946d3ceabSEric Dumazet } 78046d3ceabSEric Dumazet bh_unlock_sock(sk); 78146d3ceabSEric Dumazet 78246d3ceabSEric Dumazet clear_bit(TSQ_QUEUED, &tp->tsq_flags); 78346d3ceabSEric Dumazet sk_free(sk); 78446d3ceabSEric Dumazet } 78546d3ceabSEric Dumazet } 78646d3ceabSEric Dumazet 7876f458dfbSEric Dumazet #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ 7886f458dfbSEric Dumazet (1UL << TCP_WRITE_TIMER_DEFERRED) | \ 789563d34d0SEric Dumazet (1UL << TCP_DELACK_TIMER_DEFERRED) | \ 790563d34d0SEric Dumazet (1UL << TCP_MTU_REDUCED_DEFERRED)) 79146d3ceabSEric Dumazet /** 79246d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 79346d3ceabSEric Dumazet * @sk: socket 79446d3ceabSEric Dumazet * 79546d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 79646d3ceabSEric Dumazet * actions before socket release. 79746d3ceabSEric Dumazet */ 79846d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 79946d3ceabSEric Dumazet { 80046d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 8016f458dfbSEric Dumazet unsigned long flags, nflags; 80246d3ceabSEric Dumazet 8036f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 8046f458dfbSEric Dumazet do { 8056f458dfbSEric Dumazet flags = tp->tsq_flags; 8066f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 8076f458dfbSEric Dumazet return; 8086f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 8096f458dfbSEric Dumazet } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); 8106f458dfbSEric Dumazet 8116f458dfbSEric Dumazet if (flags & (1UL << TCP_TSQ_DEFERRED)) 8126f458dfbSEric Dumazet tcp_tsq_handler(sk); 8136f458dfbSEric Dumazet 814c3f9b018SEric Dumazet /* Here begins the tricky part : 815c3f9b018SEric Dumazet * We are called from release_sock() with : 816c3f9b018SEric Dumazet * 1) BH disabled 817c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 818c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 819c3f9b018SEric Dumazet * 820c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 821c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 822c3f9b018SEric Dumazet */ 823c3f9b018SEric Dumazet sock_release_ownership(sk); 824c3f9b018SEric Dumazet 825144d56e9SEric Dumazet if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { 8266f458dfbSEric Dumazet tcp_write_timer_handler(sk); 827144d56e9SEric Dumazet __sock_put(sk); 828144d56e9SEric Dumazet } 829144d56e9SEric Dumazet if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { 8306f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 831144d56e9SEric Dumazet __sock_put(sk); 832144d56e9SEric Dumazet } 833144d56e9SEric Dumazet if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { 8344fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 835144d56e9SEric Dumazet __sock_put(sk); 836144d56e9SEric Dumazet } 83746d3ceabSEric Dumazet } 83846d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 83946d3ceabSEric Dumazet 84046d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 84146d3ceabSEric Dumazet { 84246d3ceabSEric Dumazet int i; 84346d3ceabSEric Dumazet 84446d3ceabSEric Dumazet for_each_possible_cpu(i) { 84546d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 84646d3ceabSEric Dumazet 84746d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 84846d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 84946d3ceabSEric Dumazet tcp_tasklet_func, 85046d3ceabSEric Dumazet (unsigned long)tsq); 85146d3ceabSEric Dumazet } 85246d3ceabSEric Dumazet } 85346d3ceabSEric Dumazet 85446d3ceabSEric Dumazet /* 85546d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 8568e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 85746d3ceabSEric Dumazet * hold qdisc lock. 85846d3ceabSEric Dumazet */ 859d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 86046d3ceabSEric Dumazet { 86146d3ceabSEric Dumazet struct sock *sk = skb->sk; 86246d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 8639b462d02SEric Dumazet int wmem; 8649b462d02SEric Dumazet 8659b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 8669b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 8679b462d02SEric Dumazet */ 8689b462d02SEric Dumazet wmem = atomic_sub_return(skb->truesize - 1, &sk->sk_wmem_alloc); 8699b462d02SEric Dumazet 8709b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 8719b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 8729b462d02SEric Dumazet * This gives : 8739b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 8749b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 8759b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 8769b462d02SEric Dumazet */ 8779b462d02SEric Dumazet if (wmem >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 8789b462d02SEric Dumazet goto out; 87946d3ceabSEric Dumazet 88046d3ceabSEric Dumazet if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && 88146d3ceabSEric Dumazet !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { 88246d3ceabSEric Dumazet unsigned long flags; 88346d3ceabSEric Dumazet struct tsq_tasklet *tsq; 88446d3ceabSEric Dumazet 88546d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 88646d3ceabSEric Dumazet local_irq_save(flags); 887903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 88846d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 88946d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 89046d3ceabSEric Dumazet local_irq_restore(flags); 8919b462d02SEric Dumazet return; 89246d3ceabSEric Dumazet } 8939b462d02SEric Dumazet out: 8949b462d02SEric Dumazet sk_free(sk); 89546d3ceabSEric Dumazet } 89646d3ceabSEric Dumazet 8971da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 8981da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 8991da177e4SLinus Torvalds * transmission and possible later retransmissions. 9001da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 9011da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 9021da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 9031da177e4SLinus Torvalds * device. 9041da177e4SLinus Torvalds * 9051da177e4SLinus Torvalds * We are working here with either a clone of the original 9061da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 9071da177e4SLinus Torvalds */ 908056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 909056834d9SIlpo Järvinen gfp_t gfp_mask) 9101da177e4SLinus Torvalds { 9116687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 912dfb4b9dcSDavid S. Miller struct inet_sock *inet; 913dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 914dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 91533ad798cSAdam Langley struct tcp_out_options opts; 91695c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 917cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 9181da177e4SLinus Torvalds struct tcphdr *th; 9191da177e4SLinus Torvalds int err; 9201da177e4SLinus Torvalds 921dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 9226f094b9eSLawrence Brakmo tp = tcp_sk(sk); 923dfb4b9dcSDavid S. Miller 924ccdbb6e9SEric Dumazet if (clone_it) { 925740b0f18SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 9266f094b9eSLawrence Brakmo TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq 9276f094b9eSLawrence Brakmo - tp->snd_una; 928b9f64820SYuchung Cheng tcp_rate_skb_sent(sk, skb); 929dfb4b9dcSDavid S. Miller 930dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 931dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 932dfb4b9dcSDavid S. Miller else 933dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 934dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 935dfb4b9dcSDavid S. Miller return -ENOBUFS; 936dfb4b9dcSDavid S. Miller } 937dfb4b9dcSDavid S. Miller 938dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 939dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 94033ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 9411da177e4SLinus Torvalds 9424de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 94333ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 94433ad798cSAdam Langley else 94533ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 94633ad798cSAdam Langley &md5); 94733ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 9481da177e4SLinus Torvalds 949547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 950b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 951b2532eb9SEric Dumazet * which holds one reference to sk_wmem_alloc. 952b2532eb9SEric Dumazet * 953b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 954b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 955547669d4SEric Dumazet */ 956b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 9571da177e4SLinus Torvalds 958aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 959aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 96046d3ceabSEric Dumazet 96146d3ceabSEric Dumazet skb_orphan(skb); 96246d3ceabSEric Dumazet skb->sk = sk; 9631d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 964b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 96546d3ceabSEric Dumazet atomic_add(skb->truesize, &sk->sk_wmem_alloc); 9661da177e4SLinus Torvalds 9671da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 968ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 969c720c7e8SEric Dumazet th->source = inet->inet_sport; 970c720c7e8SEric Dumazet th->dest = inet->inet_dport; 9711da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 9721da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 973df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 9744de075e0SEric Dumazet tcb->tcp_flags); 975dfb4b9dcSDavid S. Miller 9761da177e4SLinus Torvalds th->check = 0; 9771da177e4SLinus Torvalds th->urg_ptr = 0; 9781da177e4SLinus Torvalds 97933f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 9807691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 9817691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 9821da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 9831da177e4SLinus Torvalds th->urg = 1; 9847691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 9850eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 9867691367dSHerbert Xu th->urg = 1; 9877691367dSHerbert Xu } 9881da177e4SLinus Torvalds } 9891da177e4SLinus Torvalds 990bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 99151466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 992ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 993ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 994ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 995ea1627c2SEric Dumazet } else { 996ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 997ea1627c2SEric Dumazet * is never scaled. 998ea1627c2SEric Dumazet */ 999ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1000ea1627c2SEric Dumazet } 1001cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1002cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1003cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1004a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1005bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 100639f8e58eSEric Dumazet md5, sk, skb); 1007cfb6eeb4SYOSHIFUJI Hideaki } 1008cfb6eeb4SYOSHIFUJI Hideaki #endif 1009cfb6eeb4SYOSHIFUJI Hideaki 1010bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 10111da177e4SLinus Torvalds 10124de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 1013fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 10141da177e4SLinus Torvalds 1015a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1016cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1017a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1018a44d6eacSMartin KaFai Lau } 10191da177e4SLinus Torvalds 1020bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1021aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1022aa2ea058STom Herbert tcp_skb_pcount(skb)); 10231da177e4SLinus Torvalds 10242efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 1025f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1026cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1027f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1028cd7d8498SEric Dumazet 10297faee5c0SEric Dumazet /* Our usage of tstamp should remain private */ 10307faee5c0SEric Dumazet skb->tstamp.tv64 = 0; 1031971f10ecSEric Dumazet 1032971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1033971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1034971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1035971f10ecSEric Dumazet 1036b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 10377faee5c0SEric Dumazet 103883de47cdSHua Zhong if (likely(err <= 0)) 10391da177e4SLinus Torvalds return err; 10401da177e4SLinus Torvalds 10415ee2c941SChristoph Paasch tcp_enter_cwr(sk); 10421da177e4SLinus Torvalds 1043b9df3cb8SGerrit Renker return net_xmit_eval(err); 10441da177e4SLinus Torvalds } 10451da177e4SLinus Torvalds 104667edfef7SAndi Kleen /* This routine just queues the buffer for sending. 10471da177e4SLinus Torvalds * 10481da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 10491da177e4SLinus Torvalds * otherwise socket can stall. 10501da177e4SLinus Torvalds */ 10511da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 10521da177e4SLinus Torvalds { 10531da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10541da177e4SLinus Torvalds 10551da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 10561da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1057f4a775d1SEric Dumazet __skb_header_release(skb); 1058fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 10593ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 10603ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 10611da177e4SLinus Torvalds } 10621da177e4SLinus Torvalds 106367edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 10645bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1065f6302d1dSDavid S. Miller { 10668f26fb1cSEric Dumazet if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { 1067f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1068f6302d1dSDavid S. Miller * non-TSO case. 1069f6302d1dSDavid S. Miller */ 1070cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1071f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1072f6302d1dSDavid S. Miller } else { 1073cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1074f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 10751da177e4SLinus Torvalds } 10761da177e4SLinus Torvalds } 10771da177e4SLinus Torvalds 107891fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 107968f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 108091fed7a1SIlpo Järvinen */ 1081cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 108291fed7a1SIlpo Järvinen int decr) 108391fed7a1SIlpo Järvinen { 1084a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1085a47e5a98SIlpo Järvinen 1086dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 108791fed7a1SIlpo Järvinen return; 108891fed7a1SIlpo Järvinen 10896859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 109091fed7a1SIlpo Järvinen tp->fackets_out -= decr; 109191fed7a1SIlpo Järvinen } 109291fed7a1SIlpo Järvinen 1093797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1094797108d1SIlpo Järvinen * tweaks to fix counters 1095797108d1SIlpo Järvinen */ 1096cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1097797108d1SIlpo Järvinen { 1098797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1099797108d1SIlpo Järvinen 1100797108d1SIlpo Järvinen tp->packets_out -= decr; 1101797108d1SIlpo Järvinen 1102797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1103797108d1SIlpo Järvinen tp->sacked_out -= decr; 1104797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1105797108d1SIlpo Järvinen tp->retrans_out -= decr; 1106797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1107797108d1SIlpo Järvinen tp->lost_out -= decr; 1108797108d1SIlpo Järvinen 1109797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1110797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1111797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1112797108d1SIlpo Järvinen 1113797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1114797108d1SIlpo Järvinen 1115797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1116797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 111752cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1118797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1119797108d1SIlpo Järvinen 1120797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1121797108d1SIlpo Järvinen } 1122797108d1SIlpo Järvinen 11230a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 11240a2cf20cSSoheil Hassas Yeganeh { 11250a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 11260a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 11270a2cf20cSSoheil Hassas Yeganeh } 11280a2cf20cSSoheil Hassas Yeganeh 1129490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1130490cc7d0SWillem de Bruijn { 1131490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1132490cc7d0SWillem de Bruijn 11330a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1134490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1135490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1136490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1137490cc7d0SWillem de Bruijn 1138490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1139490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1140490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1141b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1142b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1143490cc7d0SWillem de Bruijn } 1144490cc7d0SWillem de Bruijn } 1145490cc7d0SWillem de Bruijn 1146a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1147a166140eSMartin KaFai Lau { 1148a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1149a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1150a166140eSMartin KaFai Lau } 1151a166140eSMartin KaFai Lau 11521da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 11531da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 11541da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 11551da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 11561da177e4SLinus Torvalds */ 1157056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 11586cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 11591da177e4SLinus Torvalds { 11601da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11611da177e4SLinus Torvalds struct sk_buff *buff; 11626475be16SDavid S. Miller int nsize, old_factor; 1163b60b49eaSHerbert Xu int nlen; 11649ce01461SIlpo Järvinen u8 flags; 11651da177e4SLinus Torvalds 11662fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 11672fceec13SIlpo Järvinen return -EINVAL; 11686a438bbeSStephen Hemminger 11691da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 11701da177e4SLinus Torvalds if (nsize < 0) 11711da177e4SLinus Torvalds nsize = 0; 11721da177e4SLinus Torvalds 11736cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 11741da177e4SLinus Torvalds return -ENOMEM; 11751da177e4SLinus Torvalds 11761da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 1177eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, nsize, gfp, true); 117851456b29SIan Morris if (!buff) 11791da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1180ef5cb973SHerbert Xu 11813ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 11823ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1183b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1184b60b49eaSHerbert Xu buff->truesize += nlen; 1185b60b49eaSHerbert Xu skb->truesize -= nlen; 11861da177e4SLinus Torvalds 11871da177e4SLinus Torvalds /* Correct the sequence numbers. */ 11881da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 11891da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 11901da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 11911da177e4SLinus Torvalds 11921da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 11934de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 11944de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 11954de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1196e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1197a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 11981da177e4SLinus Torvalds 119984fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 12001da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1201056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1202056834d9SIlpo Järvinen skb_put(buff, nsize), 12031da177e4SLinus Torvalds nsize, 0); 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds skb_trim(skb, len); 12061da177e4SLinus Torvalds 12071da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 12081da177e4SLinus Torvalds } else { 120984fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 12101da177e4SLinus Torvalds skb_split(skb, buff, len); 12111da177e4SLinus Torvalds } 12121da177e4SLinus Torvalds 12131da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 12141da177e4SLinus Torvalds 1215a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1216490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 12171da177e4SLinus Torvalds 12186475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 12196475be16SDavid S. Miller 12201da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 12215bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 12225bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 12231da177e4SLinus Torvalds 1224b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1225b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1226b9f64820SYuchung Cheng 12276475be16SDavid S. Miller /* If this packet has been sent out already, we must 12286475be16SDavid S. Miller * adjust the various packet counters. 12296475be16SDavid S. Miller */ 1230cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 12316475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 12326475be16SDavid S. Miller tcp_skb_pcount(buff); 12331da177e4SLinus Torvalds 1234797108d1SIlpo Järvinen if (diff) 1235797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 12361da177e4SLinus Torvalds } 12371da177e4SLinus Torvalds 12381da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1239f4a775d1SEric Dumazet __skb_header_release(buff); 1240fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 12411da177e4SLinus Torvalds 12421da177e4SLinus Torvalds return 0; 12431da177e4SLinus Torvalds } 12441da177e4SLinus Torvalds 12451da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 12461da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 12471da177e4SLinus Torvalds * immediately discarded. 12481da177e4SLinus Torvalds */ 1249f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 12501da177e4SLinus Torvalds { 12517b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 12521da177e4SLinus Torvalds int i, k, eat; 12531da177e4SLinus Torvalds 12544fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 12554fa48bf3SEric Dumazet if (eat) { 12564fa48bf3SEric Dumazet __skb_pull(skb, eat); 12574fa48bf3SEric Dumazet len -= eat; 12584fa48bf3SEric Dumazet if (!len) 12594fa48bf3SEric Dumazet return; 12604fa48bf3SEric Dumazet } 12611da177e4SLinus Torvalds eat = len; 12621da177e4SLinus Torvalds k = 0; 12637b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 12647b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 12657b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 12669e903e08SEric Dumazet 12679e903e08SEric Dumazet if (size <= eat) { 1268aff65da0SIan Campbell skb_frag_unref(skb, i); 12699e903e08SEric Dumazet eat -= size; 12701da177e4SLinus Torvalds } else { 12717b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 12721da177e4SLinus Torvalds if (eat) { 12737b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 12747b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 12751da177e4SLinus Torvalds eat = 0; 12761da177e4SLinus Torvalds } 12771da177e4SLinus Torvalds k++; 12781da177e4SLinus Torvalds } 12791da177e4SLinus Torvalds } 12807b7fc97aSEric Dumazet shinfo->nr_frags = k; 12811da177e4SLinus Torvalds 128227a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 12831da177e4SLinus Torvalds skb->data_len -= len; 12841da177e4SLinus Torvalds skb->len = skb->data_len; 12851da177e4SLinus Torvalds } 12861da177e4SLinus Torvalds 128767edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 12881da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 12891da177e4SLinus Torvalds { 129014bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 12911da177e4SLinus Torvalds return -ENOMEM; 12921da177e4SLinus Torvalds 12934fa48bf3SEric Dumazet __pskb_trim_head(skb, len); 12941da177e4SLinus Torvalds 12951da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 129684fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 12971da177e4SLinus Torvalds 12981da177e4SLinus Torvalds skb->truesize -= len; 12991da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 13003ab224beSHideo Aoki sk_mem_uncharge(sk, len); 13011da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 13021da177e4SLinus Torvalds 13035b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 13041da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 13055bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 13061da177e4SLinus Torvalds 13071da177e4SLinus Torvalds return 0; 13081da177e4SLinus Torvalds } 13091da177e4SLinus Torvalds 13101b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 13111b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 13125d424d5aSJohn Heffner { 1313cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1314cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 13155d424d5aSJohn Heffner int mss_now; 13165d424d5aSJohn Heffner 13175d424d5aSJohn Heffner /* Calculate base mss without TCP options: 13185d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 13195d424d5aSJohn Heffner */ 13205d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 13215d424d5aSJohn Heffner 132267469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 132367469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 132467469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 132567469601SEric Dumazet 132667469601SEric Dumazet if (dst && dst_allfrag(dst)) 132767469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 132867469601SEric Dumazet } 132967469601SEric Dumazet 13305d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 13315d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 13325d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 13335d424d5aSJohn Heffner 13345d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 13355d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 13365d424d5aSJohn Heffner 13375d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 13385d424d5aSJohn Heffner if (mss_now < 48) 13395d424d5aSJohn Heffner mss_now = 48; 13405d424d5aSJohn Heffner return mss_now; 13415d424d5aSJohn Heffner } 13425d424d5aSJohn Heffner 13431b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 13441b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 13451b63edd6SYuchung Cheng { 13461b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 13471b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 13481b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 13491b63edd6SYuchung Cheng } 13501b63edd6SYuchung Cheng 13515d424d5aSJohn Heffner /* Inverse of above */ 135267469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 13535d424d5aSJohn Heffner { 1354cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1355cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 13565d424d5aSJohn Heffner int mtu; 13575d424d5aSJohn Heffner 13585d424d5aSJohn Heffner mtu = mss + 13595d424d5aSJohn Heffner tp->tcp_header_len + 13605d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 13615d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 13625d424d5aSJohn Heffner 136367469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 136467469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 136567469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 136667469601SEric Dumazet 136767469601SEric Dumazet if (dst && dst_allfrag(dst)) 136867469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 136967469601SEric Dumazet } 13705d424d5aSJohn Heffner return mtu; 13715d424d5aSJohn Heffner } 1372556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 13735d424d5aSJohn Heffner 137467edfef7SAndi Kleen /* MTU probing init per socket */ 13755d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 13765d424d5aSJohn Heffner { 13775d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 13785d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1379b0f9ca53SFan Du struct net *net = sock_net(sk); 13805d424d5aSJohn Heffner 1381b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 13825d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 13835d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1384b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 13855d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 138605cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 138705cbc0dbSFan Du icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; 13885d424d5aSJohn Heffner } 13894bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 13905d424d5aSJohn Heffner 13911da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 13921da177e4SLinus Torvalds 13931da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 13941da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1397caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 13981da177e4SLinus Torvalds It also does not include TCP options. 13991da177e4SLinus Torvalds 1400d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 14011da177e4SLinus Torvalds 14021da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 14031da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 14041da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 14051da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 14061da177e4SLinus Torvalds 14071da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 14081da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 14091da177e4SLinus Torvalds 1410d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1411d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 14121da177e4SLinus Torvalds */ 14131da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 14141da177e4SLinus Torvalds { 14151da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1416d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 14175d424d5aSJohn Heffner int mss_now; 14181da177e4SLinus Torvalds 14195d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 14205d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 14211da177e4SLinus Torvalds 14225d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1423409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds /* And store cached results */ 1426d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 14275d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 14285d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1429c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 14301da177e4SLinus Torvalds 14311da177e4SLinus Torvalds return mss_now; 14321da177e4SLinus Torvalds } 14334bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 14361da177e4SLinus Torvalds * and even PMTU discovery events into account. 14371da177e4SLinus Torvalds */ 14380c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 14391da177e4SLinus Torvalds { 1440cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1441cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1442c1b4a7e6SDavid S. Miller u32 mss_now; 144395c96174SEric Dumazet unsigned int header_len; 144433ad798cSAdam Langley struct tcp_out_options opts; 144533ad798cSAdam Langley struct tcp_md5sig_key *md5; 14461da177e4SLinus Torvalds 1447c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1448c1b4a7e6SDavid S. Miller 14491da177e4SLinus Torvalds if (dst) { 14501da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1451d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 14521da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 14531da177e4SLinus Torvalds } 14541da177e4SLinus Torvalds 145533ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 145633ad798cSAdam Langley sizeof(struct tcphdr); 145733ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 145833ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 145933ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 146033ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 146133ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 146233ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 146333ad798cSAdam Langley mss_now -= delta; 146433ad798cSAdam Langley } 1465cfb6eeb4SYOSHIFUJI Hideaki 14661da177e4SLinus Torvalds return mss_now; 14671da177e4SLinus Torvalds } 14681da177e4SLinus Torvalds 146986fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 147086fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 147186fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 147286fd14adSWeiping Pan */ 147386fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1474a762a980SDavid S. Miller { 14759e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1476a762a980SDavid S. Miller 147786fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 147886fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 147986fd14adSWeiping Pan /* Limited by application or receiver window. */ 148086fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 148186fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 148286fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 148386fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 148486fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 148586fd14adSWeiping Pan } 148686fd14adSWeiping Pan tp->snd_cwnd_used = 0; 148786fd14adSWeiping Pan } 148886fd14adSWeiping Pan tp->snd_cwnd_stamp = tcp_time_stamp; 148986fd14adSWeiping Pan } 149086fd14adSWeiping Pan 1491ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1492a762a980SDavid S. Miller { 1493a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1494a762a980SDavid S. Miller 1495ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1496ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1497ca8a2263SNeal Cardwell */ 1498ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1499ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1500ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1501ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1502ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1503ca8a2263SNeal Cardwell } 1504e114a710SEric Dumazet 150524901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1506a762a980SDavid S. Miller /* Network is feed fully. */ 1507a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1508a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1509a762a980SDavid S. Miller } else { 1510a762a980SDavid S. Miller /* Network starves. */ 1511a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1512a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1513a762a980SDavid S. Miller 151415d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 151515d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1516a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1517*b0f71bd3SFrancis Yan 1518*b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1519*b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1520*b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1521*b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 1522*b0f71bd3SFrancis Yan * 3) no more data to send (null tcp_send_head ) 1523*b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1524*b0f71bd3SFrancis Yan */ 1525*b0f71bd3SFrancis Yan if (!tcp_send_head(sk) && sk->sk_socket && 1526*b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1527*b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1528*b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1529a762a980SDavid S. Miller } 1530a762a980SDavid S. Miller } 1531a762a980SDavid S. Miller 1532d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1533d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1534d4589926SEric Dumazet { 1535d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1536d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1537d4589926SEric Dumazet } 1538d4589926SEric Dumazet 1539d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1540d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1541d4589926SEric Dumazet * The test is really : 1542d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1543d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1544d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1545d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 15460e3a4803SIlpo Järvinen */ 1547d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1548d4589926SEric Dumazet const struct sk_buff *skb) 1549d4589926SEric Dumazet { 1550d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1551d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1552d4589926SEric Dumazet } 1553d4589926SEric Dumazet 1554d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1555d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1556d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1557d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1558d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1559d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1560d4589926SEric Dumazet */ 1561d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1562cc93fc51SPeter Pan(潘卫平) int nonagle) 1563d4589926SEric Dumazet { 1564d4589926SEric Dumazet return partial && 1565d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1566d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1567d4589926SEric Dumazet } 1568605ad7f1SEric Dumazet 1569605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1570605ad7f1SEric Dumazet * to send one TSO packet per ms 1571605ad7f1SEric Dumazet */ 15721b3878caSNeal Cardwell u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 15731b3878caSNeal Cardwell int min_tso_segs) 1574605ad7f1SEric Dumazet { 1575605ad7f1SEric Dumazet u32 bytes, segs; 1576605ad7f1SEric Dumazet 1577605ad7f1SEric Dumazet bytes = min(sk->sk_pacing_rate >> 10, 1578605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1579605ad7f1SEric Dumazet 1580605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1581605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1582605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1583605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1584605ad7f1SEric Dumazet */ 15851b3878caSNeal Cardwell segs = max_t(u32, bytes / mss_now, min_tso_segs); 1586605ad7f1SEric Dumazet 1587605ad7f1SEric Dumazet return min_t(u32, segs, sk->sk_gso_max_segs); 1588605ad7f1SEric Dumazet } 15891b3878caSNeal Cardwell EXPORT_SYMBOL(tcp_tso_autosize); 1590605ad7f1SEric Dumazet 1591ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1592ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1593ed6e7268SNeal Cardwell */ 1594ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1595ed6e7268SNeal Cardwell { 1596ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1597ed6e7268SNeal Cardwell u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0; 1598ed6e7268SNeal Cardwell 15991b3878caSNeal Cardwell return tso_segs ? : 16001b3878caSNeal Cardwell tcp_tso_autosize(sk, mss_now, sysctl_tcp_min_tso_segs); 1601ed6e7268SNeal Cardwell } 1602ed6e7268SNeal Cardwell 1603d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1604d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1605d4589926SEric Dumazet const struct sk_buff *skb, 1606d4589926SEric Dumazet unsigned int mss_now, 1607d4589926SEric Dumazet unsigned int max_segs, 1608d4589926SEric Dumazet int nonagle) 1609c1b4a7e6SDavid S. Miller { 1610cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1611d4589926SEric Dumazet u32 partial, needed, window, max_len; 1612c1b4a7e6SDavid S. Miller 161390840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 16141485348dSBen Hutchings max_len = mss_now * max_segs; 16150e3a4803SIlpo Järvinen 16161485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 16171485348dSBen Hutchings return max_len; 16180e3a4803SIlpo Järvinen 16195ea3a748SIlpo Järvinen needed = min(skb->len, window); 16205ea3a748SIlpo Järvinen 16211485348dSBen Hutchings if (max_len <= needed) 16221485348dSBen Hutchings return max_len; 16230e3a4803SIlpo Järvinen 1624d4589926SEric Dumazet partial = needed % mss_now; 1625d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1626d4589926SEric Dumazet * to include this last segment in this skb. 1627d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1628d4589926SEric Dumazet */ 1629cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1630d4589926SEric Dumazet return needed - partial; 1631d4589926SEric Dumazet 1632d4589926SEric Dumazet return needed; 1633c1b4a7e6SDavid S. Miller } 1634c1b4a7e6SDavid S. Miller 1635c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1636c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1637c1b4a7e6SDavid S. Miller */ 1638cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1639cf533ea5SEric Dumazet const struct sk_buff *skb) 1640c1b4a7e6SDavid S. Miller { 1641d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1642c1b4a7e6SDavid S. Miller 1643c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 16444de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 16454de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1646c1b4a7e6SDavid S. Miller return 1; 1647c1b4a7e6SDavid S. Miller 1648c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1649c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1650d649a7a8SEric Dumazet if (in_flight >= cwnd) 1651c1b4a7e6SDavid S. Miller return 0; 1652d649a7a8SEric Dumazet 1653d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1654d649a7a8SEric Dumazet * 2 GSO packets in flight. 1655d649a7a8SEric Dumazet */ 1656d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1657d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1658c1b4a7e6SDavid S. Miller } 1659c1b4a7e6SDavid S. Miller 1660b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 166167edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1662c1b4a7e6SDavid S. Miller * SKB onto the wire. 1663c1b4a7e6SDavid S. Miller */ 16645bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1665c1b4a7e6SDavid S. Miller { 1666c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1667c1b4a7e6SDavid S. Miller 1668f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 16695bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 1670c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1671c1b4a7e6SDavid S. Miller } 1672c1b4a7e6SDavid S. Miller return tso_segs; 1673c1b4a7e6SDavid S. Miller } 1674c1b4a7e6SDavid S. Miller 1675c1b4a7e6SDavid S. Miller 1676a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1677c1b4a7e6SDavid S. Miller * sent now. 1678c1b4a7e6SDavid S. Miller */ 1679a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1680c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1681c1b4a7e6SDavid S. Miller { 1682c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1683c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1684c1b4a7e6SDavid S. Miller * 1685c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1686c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1687c1b4a7e6SDavid S. Miller */ 1688c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1689a2a385d6SEric Dumazet return true; 1690c1b4a7e6SDavid S. Miller 16919b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 16929b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1693a2a385d6SEric Dumazet return true; 1694c1b4a7e6SDavid S. Miller 1695cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1696a2a385d6SEric Dumazet return true; 1697c1b4a7e6SDavid S. Miller 1698a2a385d6SEric Dumazet return false; 1699c1b4a7e6SDavid S. Miller } 1700c1b4a7e6SDavid S. Miller 1701c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1702a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1703a2a385d6SEric Dumazet const struct sk_buff *skb, 1704056834d9SIlpo Järvinen unsigned int cur_mss) 1705c1b4a7e6SDavid S. Miller { 1706c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1707c1b4a7e6SDavid S. Miller 1708c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1709c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1710c1b4a7e6SDavid S. Miller 171190840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1712c1b4a7e6SDavid S. Miller } 1713c1b4a7e6SDavid S. Miller 1714fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1715c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1716c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1717c1b4a7e6SDavid S. Miller */ 1718cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1719c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1720c1b4a7e6SDavid S. Miller { 1721cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1722c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1723c1b4a7e6SDavid S. Miller 17245bbb432cSEric Dumazet tcp_init_tso_segs(skb, cur_mss); 1725c1b4a7e6SDavid S. Miller 1726c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1727c1b4a7e6SDavid S. Miller return 0; 1728c1b4a7e6SDavid S. Miller 1729c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1730056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1731c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1732c1b4a7e6SDavid S. Miller 1733c1b4a7e6SDavid S. Miller return cwnd_quota; 1734c1b4a7e6SDavid S. Miller } 1735c1b4a7e6SDavid S. Miller 173667edfef7SAndi Kleen /* Test if sending is allowed right now. */ 1737a2a385d6SEric Dumazet bool tcp_may_send_now(struct sock *sk) 1738c1b4a7e6SDavid S. Miller { 1739cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1740fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1741c1b4a7e6SDavid S. Miller 1742a02cec21SEric Dumazet return skb && 17430c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1744c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1745a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1746c1b4a7e6SDavid S. Miller } 1747c1b4a7e6SDavid S. Miller 1748c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1749c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1750c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1751c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1752c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1753c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1754c1b4a7e6SDavid S. Miller */ 1755056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1756c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1757c1b4a7e6SDavid S. Miller { 1758c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1759c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 17609ce01461SIlpo Järvinen u8 flags; 1761c1b4a7e6SDavid S. Miller 1762c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1763c8ac3774SHerbert Xu if (skb->len != skb->data_len) 17646cc55e09SOctavian Purdila return tcp_fragment(sk, skb, len, mss_now, gfp); 1765c1b4a7e6SDavid S. Miller 1766eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp, true); 176751456b29SIan Morris if (unlikely(!buff)) 1768c1b4a7e6SDavid S. Miller return -ENOMEM; 1769c1b4a7e6SDavid S. Miller 17703ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 17713ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1772b60b49eaSHerbert Xu buff->truesize += nlen; 1773c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1774c1b4a7e6SDavid S. Miller 1775c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1776c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1777c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1778c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1779c1b4a7e6SDavid S. Miller 1780c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 17814de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 17824de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 17834de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1784c1b4a7e6SDavid S. Miller 1785c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1786c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1787c1b4a7e6SDavid S. Miller 1788a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 1789a166140eSMartin KaFai Lau 179084fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1791c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1792490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1793c1b4a7e6SDavid S. Miller 1794c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 17955bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 17965bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 1797c1b4a7e6SDavid S. Miller 1798c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1799f4a775d1SEric Dumazet __skb_header_release(buff); 1800fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1801c1b4a7e6SDavid S. Miller 1802c1b4a7e6SDavid S. Miller return 0; 1803c1b4a7e6SDavid S. Miller } 1804c1b4a7e6SDavid S. Miller 1805c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1806c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1807c1b4a7e6SDavid S. Miller * 1808c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1809c1b4a7e6SDavid S. Miller */ 1810ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1811605ad7f1SEric Dumazet bool *is_cwnd_limited, u32 max_segs) 1812c1b4a7e6SDavid S. Miller { 18136687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 181450c8339eSEric Dumazet u32 age, send_win, cong_win, limit, in_flight; 181550c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 181650c8339eSEric Dumazet struct skb_mstamp now; 181750c8339eSEric Dumazet struct sk_buff *head; 1818ad9f4f50SEric Dumazet int win_divisor; 1819c1b4a7e6SDavid S. Miller 18204de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1821ae8064acSJohn Heffner goto send_now; 1822c1b4a7e6SDavid S. Miller 182399d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 1824ae8064acSJohn Heffner goto send_now; 1825ae8064acSJohn Heffner 18265f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 18275f852eb5SEric Dumazet * only if the last write was recent. 18285f852eb5SEric Dumazet */ 18295f852eb5SEric Dumazet if ((s32)(tcp_time_stamp - tp->lsndtime) > 0) 1830ae8064acSJohn Heffner goto send_now; 1831908a75c1SDavid S. Miller 1832c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1833c1b4a7e6SDavid S. Miller 1834056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1835c1b4a7e6SDavid S. Miller 183690840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1837c1b4a7e6SDavid S. Miller 1838c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1839c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1840c1b4a7e6SDavid S. Miller 1841c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1842c1b4a7e6SDavid S. Miller 1843ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 1844605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 1845ae8064acSJohn Heffner goto send_now; 1846ba244fe9SDavid S. Miller 184762ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 184862ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 184962ad2761SIlpo Järvinen goto send_now; 185062ad2761SIlpo Järvinen 1851ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1852ad9f4f50SEric Dumazet if (win_divisor) { 1853c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1854c1b4a7e6SDavid S. Miller 1855c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1856c1b4a7e6SDavid S. Miller * just use it. 1857c1b4a7e6SDavid S. Miller */ 1858ad9f4f50SEric Dumazet chunk /= win_divisor; 1859c1b4a7e6SDavid S. Miller if (limit >= chunk) 1860ae8064acSJohn Heffner goto send_now; 1861c1b4a7e6SDavid S. Miller } else { 1862c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1863c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1864c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1865c1b4a7e6SDavid S. Miller * then send now. 1866c1b4a7e6SDavid S. Miller */ 18676b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1868ae8064acSJohn Heffner goto send_now; 1869c1b4a7e6SDavid S. Miller } 1870c1b4a7e6SDavid S. Miller 187150c8339eSEric Dumazet head = tcp_write_queue_head(sk); 187250c8339eSEric Dumazet skb_mstamp_get(&now); 187350c8339eSEric Dumazet age = skb_mstamp_us_delta(&now, &head->skb_mstamp); 187450c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 187550c8339eSEric Dumazet if (age < (tp->srtt_us >> 4)) 187650c8339eSEric Dumazet goto send_now; 187750c8339eSEric Dumazet 18785f852eb5SEric Dumazet /* Ok, it looks like it is advisable to defer. */ 1879ae8064acSJohn Heffner 1880d2e1339fSBendik Rønning Opstad if (cong_win < send_win && cong_win <= skb->len) 1881ca8a2263SNeal Cardwell *is_cwnd_limited = true; 1882ca8a2263SNeal Cardwell 1883a2a385d6SEric Dumazet return true; 1884ae8064acSJohn Heffner 1885ae8064acSJohn Heffner send_now: 1886a2a385d6SEric Dumazet return false; 1887c1b4a7e6SDavid S. Miller } 1888c1b4a7e6SDavid S. Miller 188905cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 189005cbc0dbSFan Du { 189105cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 189205cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 189305cbc0dbSFan Du struct net *net = sock_net(sk); 189405cbc0dbSFan Du u32 interval; 189505cbc0dbSFan Du s32 delta; 189605cbc0dbSFan Du 189705cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 189805cbc0dbSFan Du delta = tcp_time_stamp - icsk->icsk_mtup.probe_timestamp; 189905cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 190005cbc0dbSFan Du int mss = tcp_current_mss(sk); 190105cbc0dbSFan Du 190205cbc0dbSFan Du /* Update current search range */ 190305cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 190405cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 190505cbc0dbSFan Du sizeof(struct tcphdr) + 190605cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 190705cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 190805cbc0dbSFan Du 190905cbc0dbSFan Du /* Update probe time stamp */ 191005cbc0dbSFan Du icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; 191105cbc0dbSFan Du } 191205cbc0dbSFan Du } 191305cbc0dbSFan Du 19145d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 191567edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 191667edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 191767edfef7SAndi Kleen * changes resulting in larger path MTUs. 191867edfef7SAndi Kleen * 19195d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 19205d424d5aSJohn Heffner * 1 if a probe was sent, 1921056834d9SIlpo Järvinen * -1 otherwise 1922056834d9SIlpo Järvinen */ 19235d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 19245d424d5aSJohn Heffner { 19255d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 19265d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 19275d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 19286b58e0a5SFan Du struct net *net = sock_net(sk); 19295d424d5aSJohn Heffner int len; 19305d424d5aSJohn Heffner int probe_size; 193191cc17c0SIlpo Järvinen int size_needed; 19325d424d5aSJohn Heffner int copy; 19335d424d5aSJohn Heffner int mss_now; 19346b58e0a5SFan Du int interval; 19355d424d5aSJohn Heffner 19365d424d5aSJohn Heffner /* Not currently probing/verifying, 19375d424d5aSJohn Heffner * not in recovery, 19385d424d5aSJohn Heffner * have enough cwnd, and 19395d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 19405d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 19415d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 19425d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 19435d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1944cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 19455d424d5aSJohn Heffner return -1; 19465d424d5aSJohn Heffner 19476b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 19486b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 19496b58e0a5SFan Du * smaller than a threshold, backoff from probing. 19506b58e0a5SFan Du */ 19510c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 19526b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 19536b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 195491cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 19556b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 195605cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 195705cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 195805cbc0dbSFan Du * probing process by not resetting search range to its orignal. 195905cbc0dbSFan Du */ 19606b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 196105cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 196205cbc0dbSFan Du /* Check whether enough time has elaplased for 196305cbc0dbSFan Du * another round of probing. 196405cbc0dbSFan Du */ 196505cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 19665d424d5aSJohn Heffner return -1; 19675d424d5aSJohn Heffner } 19685d424d5aSJohn Heffner 19695d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 19707f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 19715d424d5aSJohn Heffner return -1; 19725d424d5aSJohn Heffner 197391cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 19745d424d5aSJohn Heffner return -1; 197590840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 19765d424d5aSJohn Heffner return 0; 19775d424d5aSJohn Heffner 1978d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1979d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1980d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 19815d424d5aSJohn Heffner return -1; 19825d424d5aSJohn Heffner else 19835d424d5aSJohn Heffner return 0; 19845d424d5aSJohn Heffner } 19855d424d5aSJohn Heffner 19865d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 1987eb934478SEric Dumazet nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); 198851456b29SIan Morris if (!nskb) 19895d424d5aSJohn Heffner return -1; 19903ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 19913ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 19925d424d5aSJohn Heffner 1993fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 19945d424d5aSJohn Heffner 19955d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 19965d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 19974de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 19985d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 19995d424d5aSJohn Heffner nskb->csum = 0; 200084fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 20015d424d5aSJohn Heffner 200250c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 200350c4817eSIlpo Järvinen 20045d424d5aSJohn Heffner len = 0; 2005234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 20065d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 20072fe664f1SDouglas Caetano dos Santos if (nskb->ip_summed) { 20085d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 20092fe664f1SDouglas Caetano dos Santos } else { 20102fe664f1SDouglas Caetano dos Santos __wsum csum = skb_copy_and_csum_bits(skb, 0, 2011056834d9SIlpo Järvinen skb_put(nskb, copy), 20122fe664f1SDouglas Caetano dos Santos copy, 0); 20132fe664f1SDouglas Caetano dos Santos nskb->csum = csum_block_add(nskb->csum, csum, len); 20142fe664f1SDouglas Caetano dos Santos } 20155d424d5aSJohn Heffner 20165d424d5aSJohn Heffner if (skb->len <= copy) { 20175d424d5aSJohn Heffner /* We've eaten all the data from this skb. 20185d424d5aSJohn Heffner * Throw it away. */ 20194de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2020fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 20213ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 20225d424d5aSJohn Heffner } else { 20234de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2024a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 20255d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 20265d424d5aSJohn Heffner skb_pull(skb, copy); 202784fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 2028056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 2029056834d9SIlpo Järvinen skb->len, 0); 20305d424d5aSJohn Heffner } else { 20315d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 20325bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 20335d424d5aSJohn Heffner } 20345d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 20355d424d5aSJohn Heffner } 20365d424d5aSJohn Heffner 20375d424d5aSJohn Heffner len += copy; 2038234b6860SIlpo Järvinen 2039234b6860SIlpo Järvinen if (len >= probe_size) 2040234b6860SIlpo Järvinen break; 20415d424d5aSJohn Heffner } 20425bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 20435d424d5aSJohn Heffner 20445d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 20457faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 20467faee5c0SEric Dumazet */ 20475d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 20485d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 20495d424d5aSJohn Heffner * effectively two packets. */ 20505d424d5aSJohn Heffner tp->snd_cwnd--; 205166f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 20525d424d5aSJohn Heffner 20535d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 20540e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 20550e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 20565d424d5aSJohn Heffner 20575d424d5aSJohn Heffner return 1; 20585d424d5aSJohn Heffner } 20595d424d5aSJohn Heffner 20605d424d5aSJohn Heffner return -1; 20615d424d5aSJohn Heffner } 20625d424d5aSJohn Heffner 2063f9616c35SEric Dumazet /* TCP Small Queues : 2064f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2065f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2066f9616c35SEric Dumazet * This allows for : 2067f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2068f9616c35SEric Dumazet * - faster recovery 2069f9616c35SEric Dumazet * - high rates 2070f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2071f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2072f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2073f9616c35SEric Dumazet */ 2074f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2075f9616c35SEric Dumazet unsigned int factor) 2076f9616c35SEric Dumazet { 2077f9616c35SEric Dumazet unsigned int limit; 2078f9616c35SEric Dumazet 2079f9616c35SEric Dumazet limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10); 2080f9616c35SEric Dumazet limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes); 2081f9616c35SEric Dumazet limit <<= factor; 2082f9616c35SEric Dumazet 2083f9616c35SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) { 2084f9616c35SEric Dumazet set_bit(TSQ_THROTTLED, &tcp_sk(sk)->tsq_flags); 2085f9616c35SEric Dumazet /* It is possible TX completion already happened 2086f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2087f9616c35SEric Dumazet * test again the condition. 2088f9616c35SEric Dumazet */ 2089f9616c35SEric Dumazet smp_mb__after_atomic(); 2090f9616c35SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) 2091f9616c35SEric Dumazet return true; 2092f9616c35SEric Dumazet } 2093f9616c35SEric Dumazet return false; 2094f9616c35SEric Dumazet } 2095f9616c35SEric Dumazet 209605b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 209705b055e8SFrancis Yan { 209805b055e8SFrancis Yan const u32 now = tcp_time_stamp; 209905b055e8SFrancis Yan 210005b055e8SFrancis Yan if (tp->chrono_type > TCP_CHRONO_UNSPEC) 210105b055e8SFrancis Yan tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start; 210205b055e8SFrancis Yan tp->chrono_start = now; 210305b055e8SFrancis Yan tp->chrono_type = new; 210405b055e8SFrancis Yan } 210505b055e8SFrancis Yan 210605b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 210705b055e8SFrancis Yan { 210805b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 210905b055e8SFrancis Yan 211005b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 21110f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 21120f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 211305b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 211405b055e8SFrancis Yan */ 211505b055e8SFrancis Yan if (type > tp->chrono_type) 211605b055e8SFrancis Yan tcp_chrono_set(tp, type); 211705b055e8SFrancis Yan } 211805b055e8SFrancis Yan 211905b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 212005b055e8SFrancis Yan { 212105b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 212205b055e8SFrancis Yan 21230f87230dSFrancis Yan 21240f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 21250f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 21260f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 21270f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 21280f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 21290f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 21300f87230dSFrancis Yan */ 21310f87230dSFrancis Yan if (tcp_write_queue_empty(sk)) 213205b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 21330f87230dSFrancis Yan else if (type == tp->chrono_type) 21340f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 213505b055e8SFrancis Yan } 213605b055e8SFrancis Yan 21371da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 21381da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 21391da177e4SLinus Torvalds * window for us. 21401da177e4SLinus Torvalds * 2141f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2142f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2143f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2144f8269a49SIlpo Järvinen * 21456ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 21466ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 21476ba8a3b1SNandita Dukkipati 2148a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2149a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 21501da177e4SLinus Torvalds */ 2151a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2152d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 21531da177e4SLinus Torvalds { 21541da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 215592df7b51SDavid S. Miller struct sk_buff *skb; 2156c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2157c1b4a7e6SDavid S. Miller int cwnd_quota; 21585d424d5aSJohn Heffner int result; 21595615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2160605ad7f1SEric Dumazet u32 max_segs; 21611da177e4SLinus Torvalds 2162c1b4a7e6SDavid S. Miller sent_pkts = 0; 21635d424d5aSJohn Heffner 2164d5dd9175SIlpo Järvinen if (!push_one) { 21655d424d5aSJohn Heffner /* Do MTU probing. */ 2166d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2167d5dd9175SIlpo Järvinen if (!result) { 2168a2a385d6SEric Dumazet return false; 21695d424d5aSJohn Heffner } else if (result > 0) { 21705d424d5aSJohn Heffner sent_pkts = 1; 21715d424d5aSJohn Heffner } 2172d5dd9175SIlpo Järvinen } 21735d424d5aSJohn Heffner 2174ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2175fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2176c8ac3774SHerbert Xu unsigned int limit; 2177c8ac3774SHerbert Xu 21785bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2179c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2180c1b4a7e6SDavid S. Miller 21819d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 21827faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 21837faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 2184ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 21859d186cacSAndrey Vagin } 2186ec342325SAndrew Vagin 2187b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 21886ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 21896ba8a3b1SNandita Dukkipati if (push_one == 2) 21906ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 21916ba8a3b1SNandita Dukkipati cwnd_quota = 1; 21926ba8a3b1SNandita Dukkipati else 2193b68e9f85SHerbert Xu break; 21946ba8a3b1SNandita Dukkipati } 2195b68e9f85SHerbert Xu 21965615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 21975615f886SFrancis Yan is_rwnd_limited = true; 2198b68e9f85SHerbert Xu break; 21995615f886SFrancis Yan } 2200b68e9f85SHerbert Xu 2201d6a4e26aSEric Dumazet if (tso_segs == 1) { 2202aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2203aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2204aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2205aa93466bSDavid S. Miller break; 2206c1b4a7e6SDavid S. Miller } else { 2207ca8a2263SNeal Cardwell if (!push_one && 2208605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2209605ad7f1SEric Dumazet max_segs)) 2210aa93466bSDavid S. Miller break; 2211c1b4a7e6SDavid S. Miller } 2212aa93466bSDavid S. Miller 2213605ad7f1SEric Dumazet limit = mss_now; 2214d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2215605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2216605ad7f1SEric Dumazet min_t(unsigned int, 2217605ad7f1SEric Dumazet cwnd_quota, 2218605ad7f1SEric Dumazet max_segs), 2219605ad7f1SEric Dumazet nonagle); 2220605ad7f1SEric Dumazet 2221605ad7f1SEric Dumazet if (skb->len > limit && 2222605ad7f1SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2223605ad7f1SEric Dumazet break; 2224605ad7f1SEric Dumazet 2225f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 222646d3ceabSEric Dumazet break; 2227c9eeec26SEric Dumazet 2228d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 22291da177e4SLinus Torvalds break; 22301da177e4SLinus Torvalds 2231ec342325SAndrew Vagin repair: 22321da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 22331da177e4SLinus Torvalds * This call will increment packets_out. 22341da177e4SLinus Torvalds */ 223566f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 22361da177e4SLinus Torvalds 22371da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2238a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2239d5dd9175SIlpo Järvinen 2240d5dd9175SIlpo Järvinen if (push_one) 2241d5dd9175SIlpo Järvinen break; 22421da177e4SLinus Torvalds } 22431da177e4SLinus Torvalds 22445615f886SFrancis Yan if (is_rwnd_limited) 22455615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 22465615f886SFrancis Yan else 22475615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 22485615f886SFrancis Yan 2249aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2250684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2251684bad11SYuchung Cheng tp->prr_out += sent_pkts; 22526ba8a3b1SNandita Dukkipati 22536ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 22546ba8a3b1SNandita Dukkipati if (push_one != 2) 22556ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 2256d2e1339fSBendik Rønning Opstad is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); 2257ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2258a2a385d6SEric Dumazet return false; 22591da177e4SLinus Torvalds } 2260b340b264SYuchung Cheng return !tp->packets_out && tcp_send_head(sk); 22616ba8a3b1SNandita Dukkipati } 22626ba8a3b1SNandita Dukkipati 22636ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 22646ba8a3b1SNandita Dukkipati { 22656ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 22666ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 22676ba8a3b1SNandita Dukkipati u32 timeout, tlp_time_stamp, rto_time_stamp; 2268740b0f18SEric Dumazet u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); 22696ba8a3b1SNandita Dukkipati 22706ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) 22716ba8a3b1SNandita Dukkipati return false; 22726ba8a3b1SNandita Dukkipati /* No consecutive loss probes. */ 22736ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { 22746ba8a3b1SNandita Dukkipati tcp_rearm_rto(sk); 22756ba8a3b1SNandita Dukkipati return false; 22766ba8a3b1SNandita Dukkipati } 22776ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 22786ba8a3b1SNandita Dukkipati * finishes. 22796ba8a3b1SNandita Dukkipati */ 2280f9b99582SYuchung Cheng if (tp->fastopen_rsk) 22816ba8a3b1SNandita Dukkipati return false; 22826ba8a3b1SNandita Dukkipati 22836ba8a3b1SNandita Dukkipati /* TLP is only scheduled when next timer event is RTO. */ 22846ba8a3b1SNandita Dukkipati if (icsk->icsk_pending != ICSK_TIME_RETRANS) 22856ba8a3b1SNandita Dukkipati return false; 22866ba8a3b1SNandita Dukkipati 22876ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 22886ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 22896ba8a3b1SNandita Dukkipati */ 2290f9b99582SYuchung Cheng if (sysctl_tcp_early_retrans < 3 || !tp->packets_out || 22916ba8a3b1SNandita Dukkipati !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) 22926ba8a3b1SNandita Dukkipati return false; 22936ba8a3b1SNandita Dukkipati 22946ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 22956ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 22966ba8a3b1SNandita Dukkipati return false; 22976ba8a3b1SNandita Dukkipati 22986ba8a3b1SNandita Dukkipati /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account 2299f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2300f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 23016ba8a3b1SNandita Dukkipati */ 2302f9b99582SYuchung Cheng timeout = rtt << 1 ? : TCP_TIMEOUT_INIT; 23036ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 23046ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, 23056ba8a3b1SNandita Dukkipati (rtt + (rtt >> 1) + TCP_DELACK_MAX)); 23066ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, msecs_to_jiffies(10)); 23076ba8a3b1SNandita Dukkipati 23086ba8a3b1SNandita Dukkipati /* If RTO is shorter, just schedule TLP in its place. */ 23096ba8a3b1SNandita Dukkipati tlp_time_stamp = tcp_time_stamp + timeout; 23106ba8a3b1SNandita Dukkipati rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; 23116ba8a3b1SNandita Dukkipati if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { 23126ba8a3b1SNandita Dukkipati s32 delta = rto_time_stamp - tcp_time_stamp; 23136ba8a3b1SNandita Dukkipati if (delta > 0) 23146ba8a3b1SNandita Dukkipati timeout = delta; 23156ba8a3b1SNandita Dukkipati } 23166ba8a3b1SNandita Dukkipati 23176ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 23186ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 23196ba8a3b1SNandita Dukkipati return true; 23206ba8a3b1SNandita Dukkipati } 23216ba8a3b1SNandita Dukkipati 23221f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 23231f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 23241f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 23251f3279aeSEric Dumazet */ 23261f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 23271f3279aeSEric Dumazet const struct sk_buff *skb) 23281f3279aeSEric Dumazet { 232939bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2330c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 23311f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 23321f3279aeSEric Dumazet return true; 23331f3279aeSEric Dumazet } 23341f3279aeSEric Dumazet return false; 23351f3279aeSEric Dumazet } 23361f3279aeSEric Dumazet 2337b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 23386ba8a3b1SNandita Dukkipati * retransmit the last segment. 23396ba8a3b1SNandita Dukkipati */ 23406ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 23416ba8a3b1SNandita Dukkipati { 23429b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 23436ba8a3b1SNandita Dukkipati struct sk_buff *skb; 23446ba8a3b1SNandita Dukkipati int pcount; 23456ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 23466ba8a3b1SNandita Dukkipati 2347b340b264SYuchung Cheng skb = tcp_send_head(sk); 2348b340b264SYuchung Cheng if (skb) { 2349b340b264SYuchung Cheng if (tcp_snd_wnd_test(tp, skb, mss)) { 2350b340b264SYuchung Cheng pcount = tp->packets_out; 2351b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2352b340b264SYuchung Cheng if (tp->packets_out > pcount) 2353b340b264SYuchung Cheng goto probe_sent; 23546ba8a3b1SNandita Dukkipati goto rearm_timer; 23556ba8a3b1SNandita Dukkipati } 2356b340b264SYuchung Cheng skb = tcp_write_queue_prev(sk, skb); 2357b340b264SYuchung Cheng } else { 2358b340b264SYuchung Cheng skb = tcp_write_queue_tail(sk); 2359b340b264SYuchung Cheng } 23606ba8a3b1SNandita Dukkipati 23619b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 23629b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 23639b717a8dSNandita Dukkipati goto rearm_timer; 23649b717a8dSNandita Dukkipati 23656ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 23666ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 23676ba8a3b1SNandita Dukkipati goto rearm_timer; 23686ba8a3b1SNandita Dukkipati 23691f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 23701f3279aeSEric Dumazet goto rearm_timer; 23711f3279aeSEric Dumazet 23726ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 23736ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 23746ba8a3b1SNandita Dukkipati goto rearm_timer; 23756ba8a3b1SNandita Dukkipati 23766ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 23776cc55e09SOctavian Purdila if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, 23786cc55e09SOctavian Purdila GFP_ATOMIC))) 23796ba8a3b1SNandita Dukkipati goto rearm_timer; 2380b340b264SYuchung Cheng skb = tcp_write_queue_next(sk, skb); 23816ba8a3b1SNandita Dukkipati } 23826ba8a3b1SNandita Dukkipati 23836ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 23846ba8a3b1SNandita Dukkipati goto rearm_timer; 23856ba8a3b1SNandita Dukkipati 238610d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2387b340b264SYuchung Cheng goto rearm_timer; 23886ba8a3b1SNandita Dukkipati 23899b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 23909b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 23919b717a8dSNandita Dukkipati 2392b340b264SYuchung Cheng probe_sent: 2393c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2394fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2395fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2396b340b264SYuchung Cheng rearm_timer: 2397fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 23981da177e4SLinus Torvalds } 23991da177e4SLinus Torvalds 2400a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2401a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2402a762a980SDavid S. Miller * The socket must be locked by the caller. 2403a762a980SDavid S. Miller */ 24049e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 24059e412ba7SIlpo Järvinen int nonagle) 2406a762a980SDavid S. Miller { 2407726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2408726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2409726e07a8SIlpo Järvinen * all will be happy. 2410726e07a8SIlpo Järvinen */ 2411726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2412726e07a8SIlpo Järvinen return; 2413726e07a8SIlpo Järvinen 241499a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 24157450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 24169e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2417a762a980SDavid S. Miller } 2418a762a980SDavid S. Miller 2419c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2420c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2421c1b4a7e6SDavid S. Miller */ 2422c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2423c1b4a7e6SDavid S. Miller { 2424fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2425c1b4a7e6SDavid S. Miller 2426c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2427c1b4a7e6SDavid S. Miller 2428d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2429c1b4a7e6SDavid S. Miller } 2430c1b4a7e6SDavid S. Miller 24311da177e4SLinus Torvalds /* This function returns the amount that we can raise the 24321da177e4SLinus Torvalds * usable window based on the following constraints 24331da177e4SLinus Torvalds * 24341da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 24351da177e4SLinus Torvalds * 2. We limit memory per socket 24361da177e4SLinus Torvalds * 24371da177e4SLinus Torvalds * RFC 1122: 24381da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 24391da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 24401da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 24411da177e4SLinus Torvalds * 24421da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 24431da177e4SLinus Torvalds * it at least MSS bytes. 24441da177e4SLinus Torvalds * 24451da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 24461da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 24471da177e4SLinus Torvalds * 24481da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 24491da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 24501da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 24511da177e4SLinus Torvalds * window to always advance by a single byte. 24521da177e4SLinus Torvalds * 24531da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 24541da177e4SLinus Torvalds * then this will not be a problem. 24551da177e4SLinus Torvalds * 24561da177e4SLinus Torvalds * BSD seems to make the following compromise: 24571da177e4SLinus Torvalds * 24581da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 24591da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 24601da177e4SLinus Torvalds * then set the window to 0. 24611da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 24621da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 24631da177e4SLinus Torvalds * and from being larger than the largest representable value. 24641da177e4SLinus Torvalds * 24651da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 24661da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 24671da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 24681da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 24691da177e4SLinus Torvalds * because the pipeline is full. 24701da177e4SLinus Torvalds * 24711da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 24721da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 24731da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 24741da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 24751da177e4SLinus Torvalds * of having a fixed window size at almost all times. 24761da177e4SLinus Torvalds * 24771da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 24781da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 24791da177e4SLinus Torvalds * 24801da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 24811da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 24821da177e4SLinus Torvalds */ 24831da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 24841da177e4SLinus Torvalds { 2485463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 24861da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2487caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 24881da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 24891da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 24901da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 24911da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 24921da177e4SLinus Torvalds */ 2493463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 24941da177e4SLinus Torvalds int free_space = tcp_space(sk); 249586c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 249686c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 24971da177e4SLinus Torvalds int window; 24981da177e4SLinus Torvalds 24991da177e4SLinus Torvalds if (mss > full_space) 25001da177e4SLinus Torvalds mss = full_space; 25011da177e4SLinus Torvalds 2502b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2503463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 25041da177e4SLinus Torvalds 2505b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 2506056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2507056834d9SIlpo Järvinen 4U * tp->advmss); 25081da177e4SLinus Torvalds 250986c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 251086c1a045SFlorian Westphal * increase it due to wscale. 251186c1a045SFlorian Westphal */ 251286c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 251386c1a045SFlorian Westphal 251486c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 251586c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 251686c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 251786c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 251886c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 251986c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 252086c1a045SFlorian Westphal */ 252186c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 25221da177e4SLinus Torvalds return 0; 25231da177e4SLinus Torvalds } 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 25261da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 25271da177e4SLinus Torvalds 25281da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 25291da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 25301da177e4SLinus Torvalds */ 25311da177e4SLinus Torvalds window = tp->rcv_wnd; 25321da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 25331da177e4SLinus Torvalds window = free_space; 25341da177e4SLinus Torvalds 25351da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 25361da177e4SLinus Torvalds * Import case: prevent zero window announcement if 25371da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 25381da177e4SLinus Torvalds */ 25391da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 25401da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 25411da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 25421da177e4SLinus Torvalds } else { 25431da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 25441da177e4SLinus Torvalds * Window clamp already applied above. 25451da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 25461da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 25471da177e4SLinus Torvalds * and multiply from happening most of the time. 25481da177e4SLinus Torvalds * We also don't do any window rounding when the free space 25491da177e4SLinus Torvalds * is too small. 25501da177e4SLinus Torvalds */ 25511da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 25521da177e4SLinus Torvalds window = (free_space / mss) * mss; 255384565070SJohn Heffner else if (mss == full_space && 2554b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 255584565070SJohn Heffner window = free_space; 25561da177e4SLinus Torvalds } 25571da177e4SLinus Torvalds 25581da177e4SLinus Torvalds return window; 25591da177e4SLinus Torvalds } 25601da177e4SLinus Torvalds 2561cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 2562082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 2563082ac2d5SMartin KaFai Lau { 25640a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 25650a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 25660a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 2567082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 2568082ac2d5SMartin KaFai Lau 25690a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 2570082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 25712de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 25722de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 2573082ac2d5SMartin KaFai Lau } 2574082ac2d5SMartin KaFai Lau } 2575082ac2d5SMartin KaFai Lau 25764a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 2577f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 25781da177e4SLinus Torvalds { 25791da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2580fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2581058dc334SIlpo Järvinen int skb_size, next_skb_size; 25821da177e4SLinus Torvalds 2583058dc334SIlpo Järvinen skb_size = skb->len; 2584058dc334SIlpo Järvinen next_skb_size = next_skb->len; 25851da177e4SLinus Torvalds 2586058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 25871da177e4SLinus Torvalds 2588f8071cdeSEric Dumazet if (next_skb_size) { 2589f8071cdeSEric Dumazet if (next_skb_size <= skb_availroom(skb)) 2590f8071cdeSEric Dumazet skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), 2591f8071cdeSEric Dumazet next_skb_size); 2592f8071cdeSEric Dumazet else if (!skb_shift(skb, next_skb, next_skb_size)) 2593f8071cdeSEric Dumazet return false; 2594f8071cdeSEric Dumazet } 25956859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 2596a6963a6bSIlpo Järvinen 2597fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 25981da177e4SLinus Torvalds 259952d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 260052d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 26011da177e4SLinus Torvalds 260284fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 26031da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 26041da177e4SLinus Torvalds 26051da177e4SLinus Torvalds /* Update sequence range on original skb. */ 26061da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 26071da177e4SLinus Torvalds 2608e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 26094de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 26101da177e4SLinus Torvalds 26111da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 26121da177e4SLinus Torvalds * packet counting does not break. 26131da177e4SLinus Torvalds */ 26144828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2615a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 2616b7689205SIlpo Järvinen 2617b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2618ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2619ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2620ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2621b7689205SIlpo Järvinen 2622797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2623797108d1SIlpo Järvinen 2624082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 2625082ac2d5SMartin KaFai Lau 26263ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 2627f8071cdeSEric Dumazet return true; 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds 263067edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2631a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 26324a17fc3aSIlpo Järvinen { 26334a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2634a2a385d6SEric Dumazet return false; 26354a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2636a2a385d6SEric Dumazet return false; 26374a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2638a2a385d6SEric Dumazet return false; 26392331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 26404a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2641a2a385d6SEric Dumazet return false; 26424a17fc3aSIlpo Järvinen 2643a2a385d6SEric Dumazet return true; 26444a17fc3aSIlpo Järvinen } 26454a17fc3aSIlpo Järvinen 264667edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 264767edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 264867edfef7SAndi Kleen */ 26494a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 26504a17fc3aSIlpo Järvinen int space) 26514a17fc3aSIlpo Järvinen { 26524a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 26534a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2654a2a385d6SEric Dumazet bool first = true; 26554a17fc3aSIlpo Järvinen 26564a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 26574a17fc3aSIlpo Järvinen return; 26584de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 26594a17fc3aSIlpo Järvinen return; 26604a17fc3aSIlpo Järvinen 26614a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 26624a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 26634a17fc3aSIlpo Järvinen break; 26644a17fc3aSIlpo Järvinen 2665a643b5d4SMartin KaFai Lau if (!tcp_skb_can_collapse_to(to)) 2666a643b5d4SMartin KaFai Lau break; 2667a643b5d4SMartin KaFai Lau 26684a17fc3aSIlpo Järvinen space -= skb->len; 26694a17fc3aSIlpo Järvinen 26704a17fc3aSIlpo Järvinen if (first) { 2671a2a385d6SEric Dumazet first = false; 26724a17fc3aSIlpo Järvinen continue; 26734a17fc3aSIlpo Järvinen } 26744a17fc3aSIlpo Järvinen 26754a17fc3aSIlpo Järvinen if (space < 0) 26764a17fc3aSIlpo Järvinen break; 26774a17fc3aSIlpo Järvinen 26784a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 26794a17fc3aSIlpo Järvinen break; 26804a17fc3aSIlpo Järvinen 2681f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 2682f8071cdeSEric Dumazet break; 26834a17fc3aSIlpo Järvinen } 26844a17fc3aSIlpo Järvinen } 26854a17fc3aSIlpo Järvinen 26861da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 26871da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 26881da177e4SLinus Torvalds * error occurred which prevented the send. 26891da177e4SLinus Torvalds */ 269010d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 26911da177e4SLinus Torvalds { 26925d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 269310d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 26947d227cd2SSridhar Samudrala unsigned int cur_mss; 269510d3be56SEric Dumazet int diff, len, err; 26961da177e4SLinus Torvalds 269710d3be56SEric Dumazet 269810d3be56SEric Dumazet /* Inconclusive MTU probe */ 269910d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 27005d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 27015d424d5aSJohn Heffner 27021da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2703caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 27041da177e4SLinus Torvalds */ 27051da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 2706ffb4d6c8SEric Dumazet min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), 2707ffb4d6c8SEric Dumazet sk->sk_sndbuf)) 27081da177e4SLinus Torvalds return -EAGAIN; 27091da177e4SLinus Torvalds 27101f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 27111f3279aeSEric Dumazet return -EBUSY; 27121f3279aeSEric Dumazet 27131da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 27141da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 27151da177e4SLinus Torvalds BUG(); 27161da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 27171da177e4SLinus Torvalds return -ENOMEM; 27181da177e4SLinus Torvalds } 27191da177e4SLinus Torvalds 27207d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 27217d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 27227d227cd2SSridhar Samudrala 27230c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 27247d227cd2SSridhar Samudrala 27251da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 27261da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 27271da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 27281da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 27291da177e4SLinus Torvalds */ 27309d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 27319d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 27321da177e4SLinus Torvalds return -EAGAIN; 27331da177e4SLinus Torvalds 273410d3be56SEric Dumazet len = cur_mss * segs; 273510d3be56SEric Dumazet if (skb->len > len) { 273610d3be56SEric Dumazet if (tcp_fragment(sk, skb, len, cur_mss, GFP_ATOMIC)) 27371da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 273802276f3cSIlpo Järvinen } else { 2739c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2740c52e2421SEric Dumazet return -ENOMEM; 274110d3be56SEric Dumazet 274210d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 274310d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 274410d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 274510d3be56SEric Dumazet if (diff) 274610d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 274710d3be56SEric Dumazet if (skb->len < cur_mss) 274810d3be56SEric Dumazet tcp_retrans_try_collapse(sk, skb, cur_mss); 27491da177e4SLinus Torvalds } 27501da177e4SLinus Torvalds 275149213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 275249213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 275349213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 275449213555SDaniel Borkmann 275550bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 275650bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 275750bceae9SThomas Graf * beyond what csum_start can cover. 275850bceae9SThomas Graf */ 275950bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 276050bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 276110a81980SEric Dumazet struct sk_buff *nskb; 276210a81980SEric Dumazet 276310a81980SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 276410a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 2765c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2766117632e6SEric Dumazet -ENOBUFS; 2767117632e6SEric Dumazet } else { 2768c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2769117632e6SEric Dumazet } 2770c84a5711SYuchung Cheng 2771fc9f3501SEric Dumazet if (likely(!err)) { 277210d3be56SEric Dumazet segs = tcp_skb_pcount(skb); 277310d3be56SEric Dumazet 2774c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2775fc9f3501SEric Dumazet /* Update global TCP statistics. */ 277610d3be56SEric Dumazet TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 2777fc9f3501SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 277802a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 277910d3be56SEric Dumazet tp->total_retrans += segs; 2780fc9f3501SEric Dumazet } 2781c84a5711SYuchung Cheng return err; 278293b174adSYuchung Cheng } 278393b174adSYuchung Cheng 278410d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 278593b174adSYuchung Cheng { 278693b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 278710d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 27881da177e4SLinus Torvalds 27891da177e4SLinus Torvalds if (err == 0) { 27901da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 27911da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2792e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 27931da177e4SLinus Torvalds } 27941da177e4SLinus Torvalds #endif 27951da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 27961da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 27971da177e4SLinus Torvalds 27981da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 27991da177e4SLinus Torvalds if (!tp->retrans_stamp) 28007faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 28011da177e4SLinus Torvalds 28021f3279aeSEric Dumazet } else if (err != -EBUSY) { 2803c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 28041da177e4SLinus Torvalds } 28056e08d5e3SYuchung Cheng 28066e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 28076e08d5e3SYuchung Cheng tp->undo_retrans = 0; 28086e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 28091da177e4SLinus Torvalds return err; 28101da177e4SLinus Torvalds } 28111da177e4SLinus Torvalds 281267edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 281367edfef7SAndi Kleen * window/congestion state. 281467edfef7SAndi Kleen */ 2815a2a385d6SEric Dumazet static bool tcp_can_forward_retransmit(struct sock *sk) 2816b5afe7bcSIlpo Järvinen { 2817b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2818cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2819b5afe7bcSIlpo Järvinen 2820b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2821b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2822a2a385d6SEric Dumazet return false; 2823b5afe7bcSIlpo Järvinen 2824b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2825b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2826a2a385d6SEric Dumazet return false; 2827b5afe7bcSIlpo Järvinen 2828b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2829b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2830b5afe7bcSIlpo Järvinen * 2831b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2832b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2833b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2834b5afe7bcSIlpo Järvinen */ 2835b5afe7bcSIlpo Järvinen 2836b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2837a2a385d6SEric Dumazet return false; 2838b5afe7bcSIlpo Järvinen 2839a2a385d6SEric Dumazet return true; 2840b5afe7bcSIlpo Järvinen } 2841b5afe7bcSIlpo Järvinen 28421da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 28431da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 28441da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 28451da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 28461da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 28471da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 28481da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 28491da177e4SLinus Torvalds */ 28501da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 28511da177e4SLinus Torvalds { 28526687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 28531da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 28541da177e4SLinus Torvalds struct sk_buff *skb; 28550e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2856a3d2e9f8SEric Dumazet u32 max_segs, last_lost; 285761eb55f4SIlpo Järvinen int mib_idx; 28580e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 28596a438bbeSStephen Hemminger 286045e77d31SIlpo Järvinen if (!tp->packets_out) 286145e77d31SIlpo Järvinen return; 286245e77d31SIlpo Järvinen 286308ebd172SIlpo Järvinen if (!tp->lost_out) 286408ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 286508ebd172SIlpo Järvinen 2866618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 28676a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2868618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2869618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2870618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2871618d9f25SIlpo Järvinen } else { 2872fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2873618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2874618d9f25SIlpo Järvinen } 28751da177e4SLinus Torvalds 2876ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 2877fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 2878dca0aaf8SEric Dumazet __u8 sacked; 287910d3be56SEric Dumazet int segs; 28801da177e4SLinus Torvalds 2881fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2882fe067e8aSDavid S. Miller break; 28836a438bbeSStephen Hemminger /* we could do better than to assign each time */ 288451456b29SIan Morris if (!hole) 28856a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 28866a438bbeSStephen Hemminger 288710d3be56SEric Dumazet segs = tp->snd_cwnd - tcp_packets_in_flight(tp); 288810d3be56SEric Dumazet if (segs <= 0) 28891da177e4SLinus Torvalds return; 2890dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 2891a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 2892a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 2893a3d2e9f8SEric Dumazet */ 2894a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 28950e1c54c2SIlpo Järvinen 28960e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 28970e1c54c2SIlpo Järvinen begin_fwd: 28980e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2899006f582cSIlpo Järvinen break; 29000e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 29010e1c54c2SIlpo Järvinen 29020e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2903618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 29040e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 29050e1c54c2SIlpo Järvinen break; 29060e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 290700db4124SIan Morris if (hole) { 29080e1c54c2SIlpo Järvinen skb = hole; 29090e1c54c2SIlpo Järvinen hole = NULL; 29100e1c54c2SIlpo Järvinen } 29110e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 29120e1c54c2SIlpo Järvinen goto begin_fwd; 29130e1c54c2SIlpo Järvinen 29140e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 291551456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 29160e1c54c2SIlpo Järvinen hole = skb; 291761eb55f4SIlpo Järvinen continue; 29181da177e4SLinus Torvalds 29190e1c54c2SIlpo Järvinen } else { 2920618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 29210e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 29220e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 29230e1c54c2SIlpo Järvinen else 29240e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 29250e1c54c2SIlpo Järvinen } 29260e1c54c2SIlpo Järvinen 29270e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 292861eb55f4SIlpo Järvinen continue; 292940b215e5SPavel Emelyanov 2930f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 2931f9616c35SEric Dumazet return; 2932f9616c35SEric Dumazet 293310d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 29341da177e4SLinus Torvalds return; 293524ab6becSYuchung Cheng 2936de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 29371da177e4SLinus Torvalds 2938684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2939a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2940a262f0cdSNandita Dukkipati 2941fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2942463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 29433f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 29443f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 29451da177e4SLinus Torvalds } 29461da177e4SLinus Torvalds } 29471da177e4SLinus Torvalds 2948d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 2949d83769a5SEric Dumazet * connection tear down and (memory) recovery. 2950845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 2951845704a5SEric Dumazet * or even be forced to close flow without any FIN. 2952a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 2953a6c5ea4cSEric Dumazet * with edge trigger epoll() 2954d83769a5SEric Dumazet */ 2955a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 2956d83769a5SEric Dumazet { 2957e805605cSJohannes Weiner int amt; 2958d83769a5SEric Dumazet 2959d83769a5SEric Dumazet if (size <= sk->sk_forward_alloc) 2960d83769a5SEric Dumazet return; 2961d83769a5SEric Dumazet amt = sk_mem_pages(size); 2962d83769a5SEric Dumazet sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; 2963e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 2964e805605cSJohannes Weiner 2965baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 2966baac50bbSJohannes Weiner mem_cgroup_charge_skmem(sk->sk_memcg, amt); 2967d83769a5SEric Dumazet } 2968d83769a5SEric Dumazet 2969845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 2970845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 29711da177e4SLinus Torvalds */ 29721da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 29731da177e4SLinus Torvalds { 2974845704a5SEric Dumazet struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); 29751da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 29761da177e4SLinus Torvalds 2977845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 2978845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 2979845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 2980845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 29811da177e4SLinus Torvalds */ 2982b8da51ebSEric Dumazet if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) { 2983845704a5SEric Dumazet coalesce: 2984845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 2985845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 29861da177e4SLinus Torvalds tp->write_seq++; 2987845704a5SEric Dumazet if (!tcp_send_head(sk)) { 2988845704a5SEric Dumazet /* This means tskb was already sent. 2989845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 2990845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 2991845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 2992845704a5SEric Dumazet * does not change tp->snd_nxt. 2993845704a5SEric Dumazet */ 2994845704a5SEric Dumazet tp->snd_nxt++; 2995845704a5SEric Dumazet return; 2996845704a5SEric Dumazet } 29971da177e4SLinus Torvalds } else { 2998845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 2999845704a5SEric Dumazet if (unlikely(!skb)) { 3000845704a5SEric Dumazet if (tskb) 3001845704a5SEric Dumazet goto coalesce; 3002845704a5SEric Dumazet return; 30031da177e4SLinus Torvalds } 3004d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3005a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 30061da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3007e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3008a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 30091da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 30101da177e4SLinus Torvalds } 3011845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 30121da177e4SLinus Torvalds } 30131da177e4SLinus Torvalds 30141da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 30151da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 30161da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 301765bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 30181da177e4SLinus Torvalds */ 3019dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 30201da177e4SLinus Torvalds { 30211da177e4SLinus Torvalds struct sk_buff *skb; 30221da177e4SLinus Torvalds 30231da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 30241da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 30251da177e4SLinus Torvalds if (!skb) { 30264e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 30271da177e4SLinus Torvalds return; 30281da177e4SLinus Torvalds } 30291da177e4SLinus Torvalds 30301da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 30311da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3032e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3033a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 3034675ee231SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 30351da177e4SLinus Torvalds /* Send it off. */ 3036dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 30374e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 303826af65cbSSridhar Samudrala 303981cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 30401da177e4SLinus Torvalds } 30411da177e4SLinus Torvalds 304267edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 304367edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 30441da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 30451da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 30461da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 30471da177e4SLinus Torvalds */ 30481da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 30491da177e4SLinus Torvalds { 30501da177e4SLinus Torvalds struct sk_buff *skb; 30511da177e4SLinus Torvalds 3052fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 305351456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 305491df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 30551da177e4SLinus Torvalds return -EFAULT; 30561da177e4SLinus Torvalds } 30574de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 30581da177e4SLinus Torvalds if (skb_cloned(skb)) { 30591da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 306051456b29SIan Morris if (!nskb) 30611da177e4SLinus Torvalds return -ENOMEM; 3062fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 3063f4a775d1SEric Dumazet __skb_header_release(nskb); 3064fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 30653ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 30663ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 30673ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 30681da177e4SLinus Torvalds skb = nskb; 30691da177e4SLinus Torvalds } 30701da177e4SLinus Torvalds 30714de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3072735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 30731da177e4SLinus Torvalds } 3074dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 30751da177e4SLinus Torvalds } 30761da177e4SLinus Torvalds 30774aea39c1SEric Dumazet /** 30784aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 30794aea39c1SEric Dumazet * sk: listener socket 30804aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 30814aea39c1SEric Dumazet * req: request_sock pointer 30824aea39c1SEric Dumazet * 30834aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 30844aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 30854aea39c1SEric Dumazet */ 30865d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3087e6b4d113SWilliam Allen Simpson struct request_sock *req, 3088ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3089b3d05147SEric Dumazet enum tcp_synack_type synack_type) 30901da177e4SLinus Torvalds { 30912e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 30925d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 309380f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 30945d062de7SEric Dumazet struct tcp_out_options opts; 30955d062de7SEric Dumazet struct sk_buff *skb; 3096bd0388aeSWilliam Allen Simpson int tcp_header_size; 30975d062de7SEric Dumazet struct tcphdr *th; 30985d062de7SEric Dumazet u16 user_mss; 3099f5fff5dcSTom Quetchenbach int mss; 31001da177e4SLinus Torvalds 3101ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 31024aea39c1SEric Dumazet if (unlikely(!skb)) { 31034aea39c1SEric Dumazet dst_release(dst); 31041da177e4SLinus Torvalds return NULL; 31054aea39c1SEric Dumazet } 31061da177e4SLinus Torvalds /* Reserve space for headers. */ 31071da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 31081da177e4SLinus Torvalds 3109b3d05147SEric Dumazet switch (synack_type) { 3110b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 31119e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3112b3d05147SEric Dumazet break; 3113b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3114b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3115b3d05147SEric Dumazet * to avoid false sharing. 3116b3d05147SEric Dumazet */ 3117b3d05147SEric Dumazet break; 3118b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3119ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3120ca6fb065SEric Dumazet * cpu might call us concurrently. 3121ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3122ca6fb065SEric Dumazet */ 3123ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3124b3d05147SEric Dumazet break; 3125ca6fb065SEric Dumazet } 31264aea39c1SEric Dumazet skb_dst_set(skb, dst); 31271da177e4SLinus Torvalds 31280dbaee3bSDavid S. Miller mss = dst_metric_advmss(dst); 31295d062de7SEric Dumazet user_mss = READ_ONCE(tp->rx_opt.user_mss); 31305d062de7SEric Dumazet if (user_mss && user_mss < mss) 31315d062de7SEric Dumazet mss = user_mss; 3132f5fff5dcSTom Quetchenbach 313333ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 31348b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 31358b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 31367faee5c0SEric Dumazet skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); 31378b5f12d0SFlorian Westphal else 31388b5f12d0SFlorian Westphal #endif 31397faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 314080f03e27SEric Dumazet 314180f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 314280f03e27SEric Dumazet rcu_read_lock(); 3143fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 314480f03e27SEric Dumazet #endif 314558d607d3SEric Dumazet skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); 314637bfbddaSEric Dumazet tcp_header_size = tcp_synack_options(req, mss, skb, &opts, md5, foc) + 314737bfbddaSEric Dumazet sizeof(*th); 314833ad798cSAdam Langley 3149aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3150aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 31511da177e4SLinus Torvalds 3152ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 31531da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 31541da177e4SLinus Torvalds th->syn = 1; 31551da177e4SLinus Torvalds th->ack = 1; 31566ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3157b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3158634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3159e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 3160e870a8efSIlpo Järvinen * not even correctly set) 3161e870a8efSIlpo Järvinen */ 3162e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 3163a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 31644957faadSWilliam Allen Simpson 31651da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 31668336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 31678336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 31681da177e4SLinus Torvalds 31691da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3170ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 31715d062de7SEric Dumazet tcp_options_write((__be32 *)(th + 1), NULL, &opts); 31721da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 317390bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3174cfb6eeb4SYOSHIFUJI Hideaki 3175cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3176cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 317780f03e27SEric Dumazet if (md5) 3178bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 317939f8e58eSEric Dumazet md5, req_to_sk(req), skb); 318080f03e27SEric Dumazet rcu_read_unlock(); 3181cfb6eeb4SYOSHIFUJI Hideaki #endif 3182cfb6eeb4SYOSHIFUJI Hideaki 3183b50edd78SEric Dumazet /* Do not fool tcpdump (if any), clean our debris */ 3184b50edd78SEric Dumazet skb->tstamp.tv64 = 0; 31851da177e4SLinus Torvalds return skb; 31861da177e4SLinus Torvalds } 31874bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 31881da177e4SLinus Torvalds 318981164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 319081164413SDaniel Borkmann { 319181164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 319281164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 319381164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 319481164413SDaniel Borkmann 319581164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 319681164413SDaniel Borkmann return; 319781164413SDaniel Borkmann 319881164413SDaniel Borkmann rcu_read_lock(); 319981164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 320081164413SDaniel Borkmann if (likely(ca && try_module_get(ca->owner))) { 320181164413SDaniel Borkmann module_put(icsk->icsk_ca_ops->owner); 320281164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 320381164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 320481164413SDaniel Borkmann } 320581164413SDaniel Borkmann rcu_read_unlock(); 320681164413SDaniel Borkmann } 320781164413SDaniel Borkmann 320867edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3209f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 32101da177e4SLinus Torvalds { 3211cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 32121da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32131da177e4SLinus Torvalds __u8 rcv_wscale; 32141da177e4SLinus Torvalds 32151da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 32161da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 32171da177e4SLinus Torvalds */ 32181da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 3219bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 32201da177e4SLinus Torvalds 3221cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 322200db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3223cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3224cfb6eeb4SYOSHIFUJI Hideaki #endif 3225cfb6eeb4SYOSHIFUJI Hideaki 32261da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 32271da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 32281da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 32291da177e4SLinus Torvalds tp->max_window = 0; 32305d424d5aSJohn Heffner tcp_mtup_init(sk); 32311da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 32321da177e4SLinus Torvalds 323381164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 323481164413SDaniel Borkmann 32351da177e4SLinus Torvalds if (!tp->window_clamp) 32361da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 32370dbaee3bSDavid S. Miller tp->advmss = dst_metric_advmss(dst); 3238f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 3239f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 3240f5fff5dcSTom Quetchenbach 32411da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 32421da177e4SLinus Torvalds 3243e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3244e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3245e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3246e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3247e88c64f0SHagen Paul Pfeifer 32481da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 32491da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 32501da177e4SLinus Torvalds &tp->rcv_wnd, 32511da177e4SLinus Torvalds &tp->window_clamp, 3252bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 325331d12926Slaurent chavey &rcv_wscale, 325431d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 32551da177e4SLinus Torvalds 32561da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 32571da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 32581da177e4SLinus Torvalds 32591da177e4SLinus Torvalds sk->sk_err = 0; 32601da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 32611da177e4SLinus Torvalds tp->snd_wnd = 0; 3262ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 32631da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 32641da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 326533f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3266370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 3267ee995283SPavel Emelyanov 3268ee995283SPavel Emelyanov if (likely(!tp->repair)) 32691da177e4SLinus Torvalds tp->rcv_nxt = 0; 3270c7781a6eSAndrew Vagin else 3271c7781a6eSAndrew Vagin tp->rcv_tstamp = tcp_time_stamp; 3272ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 3273ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 32741da177e4SLinus Torvalds 3275463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 3276463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 32771da177e4SLinus Torvalds tcp_clear_retrans(tp); 32781da177e4SLinus Torvalds } 32791da177e4SLinus Torvalds 3280783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3281783237e8SYuchung Cheng { 3282783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3283783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3284783237e8SYuchung Cheng 3285783237e8SYuchung Cheng tcb->end_seq += skb->len; 3286f4a775d1SEric Dumazet __skb_header_release(skb); 3287783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 3288783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 3289783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 3290783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 3291783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3292783237e8SYuchung Cheng } 3293783237e8SYuchung Cheng 3294783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3295783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3296783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3297783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3298783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3299783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3300783237e8SYuchung Cheng */ 3301783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3302783237e8SYuchung Cheng { 3303783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3304783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 330507e100f9SEric Dumazet int syn_loss = 0, space, err = 0; 3306aab48743SYuchung Cheng unsigned long last_syn_loss = 0; 3307355a901eSEric Dumazet struct sk_buff *syn_data; 3308783237e8SYuchung Cheng 330967da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3310aab48743SYuchung Cheng tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, 3311aab48743SYuchung Cheng &syn_loss, &last_syn_loss); 3312aab48743SYuchung Cheng /* Recurring FO SYN losses: revert to regular handshake temporarily */ 3313aab48743SYuchung Cheng if (syn_loss > 1 && 3314aab48743SYuchung Cheng time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { 3315aab48743SYuchung Cheng fo->cookie.len = -1; 3316aab48743SYuchung Cheng goto fallback; 3317aab48743SYuchung Cheng } 3318aab48743SYuchung Cheng 331967da22d2SYuchung Cheng if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) 332067da22d2SYuchung Cheng fo->cookie.len = -1; 332167da22d2SYuchung Cheng else if (fo->cookie.len <= 0) 3322783237e8SYuchung Cheng goto fallback; 3323783237e8SYuchung Cheng 3324783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3325783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3326783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3327783237e8SYuchung Cheng */ 3328783237e8SYuchung Cheng if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) 3329783237e8SYuchung Cheng tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 33301b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3331783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3332783237e8SYuchung Cheng 3333f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3334f5ddcbbbSEric Dumazet 3335f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3336f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3337f5ddcbbbSEric Dumazet 3338eb934478SEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); 3339355a901eSEric Dumazet if (!syn_data) 3340783237e8SYuchung Cheng goto fallback; 3341355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3342355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 334307e100f9SEric Dumazet if (space) { 334407e100f9SEric Dumazet int copied = copy_from_iter(skb_put(syn_data, space), space, 334557be5bdaSAl Viro &fo->data->msg_iter); 334657be5bdaSAl Viro if (unlikely(!copied)) { 3347355a901eSEric Dumazet kfree_skb(syn_data); 3348783237e8SYuchung Cheng goto fallback; 3349783237e8SYuchung Cheng } 335057be5bdaSAl Viro if (copied != space) { 335157be5bdaSAl Viro skb_trim(syn_data, copied); 335257be5bdaSAl Viro space = copied; 335357be5bdaSAl Viro } 335407e100f9SEric Dumazet } 3355355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3356355a901eSEric Dumazet if (space == fo->size) 3357355a901eSEric Dumazet fo->data = NULL; 3358355a901eSEric Dumazet fo->copied = space; 3359783237e8SYuchung Cheng 3360355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 33610f87230dSFrancis Yan if (syn_data->len) 33620f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3363355a901eSEric Dumazet 3364355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3365355a901eSEric Dumazet 3366355a901eSEric Dumazet syn->skb_mstamp = syn_data->skb_mstamp; 3367355a901eSEric Dumazet 3368355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3369355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3370355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3371355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3372431a9124SEric Dumazet */ 3373355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3374355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3375355a901eSEric Dumazet if (!err) { 337667da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 3377f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3378783237e8SYuchung Cheng goto done; 3379783237e8SYuchung Cheng } 3380783237e8SYuchung Cheng 3381783237e8SYuchung Cheng fallback: 3382783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3383783237e8SYuchung Cheng if (fo->cookie.len > 0) 3384783237e8SYuchung Cheng fo->cookie.len = 0; 3385783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3386783237e8SYuchung Cheng if (err) 3387783237e8SYuchung Cheng tp->syn_fastopen = 0; 3388783237e8SYuchung Cheng done: 3389783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3390783237e8SYuchung Cheng return err; 3391783237e8SYuchung Cheng } 3392783237e8SYuchung Cheng 339367edfef7SAndi Kleen /* Build a SYN and send it off. */ 33941da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 33951da177e4SLinus Torvalds { 33961da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 33971da177e4SLinus Torvalds struct sk_buff *buff; 3398ee586811SEric Paris int err; 33991da177e4SLinus Torvalds 34001da177e4SLinus Torvalds tcp_connect_init(sk); 34011da177e4SLinus Torvalds 34022b916477SAndrey Vagin if (unlikely(tp->repair)) { 34032b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 34042b916477SAndrey Vagin return 0; 34052b916477SAndrey Vagin } 34062b916477SAndrey Vagin 3407eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); 3408355a901eSEric Dumazet if (unlikely(!buff)) 34091da177e4SLinus Torvalds return -ENOBUFS; 34101da177e4SLinus Torvalds 3411a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 34127faee5c0SEric Dumazet tp->retrans_stamp = tcp_time_stamp; 3413783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3414735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 34151da177e4SLinus Torvalds 3416783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3417783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3418783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3419ee586811SEric Paris if (err == -ECONNREFUSED) 3420ee586811SEric Paris return err; 3421bd37a088SWei Yongjun 3422bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3423bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3424bd37a088SWei Yongjun */ 3425bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3426bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 342781cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 34281da177e4SLinus Torvalds 34291da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 34303f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 34313f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 34321da177e4SLinus Torvalds return 0; 34331da177e4SLinus Torvalds } 34344bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 34351da177e4SLinus Torvalds 34361da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 34371da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 34381da177e4SLinus Torvalds * for details. 34391da177e4SLinus Torvalds */ 34401da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 34411da177e4SLinus Torvalds { 3442463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3443463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 34441da177e4SLinus Torvalds unsigned long timeout; 34451da177e4SLinus Torvalds 34469890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_DELAYED_ACK); 34479890092eSFlorian Westphal 34481da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3449463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 34501da177e4SLinus Torvalds int max_ato = HZ / 2; 34511da177e4SLinus Torvalds 3452056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3453056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 34541da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 34551da177e4SLinus Torvalds 34561da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 34571da177e4SLinus Torvalds 34581da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3459463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 34601da177e4SLinus Torvalds * directly. 34611da177e4SLinus Torvalds */ 3462740b0f18SEric Dumazet if (tp->srtt_us) { 3463740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3464740b0f18SEric Dumazet TCP_DELACK_MIN); 34651da177e4SLinus Torvalds 34661da177e4SLinus Torvalds if (rtt < max_ato) 34671da177e4SLinus Torvalds max_ato = rtt; 34681da177e4SLinus Torvalds } 34691da177e4SLinus Torvalds 34701da177e4SLinus Torvalds ato = min(ato, max_ato); 34711da177e4SLinus Torvalds } 34721da177e4SLinus Torvalds 34731da177e4SLinus Torvalds /* Stay within the limit we were given */ 34741da177e4SLinus Torvalds timeout = jiffies + ato; 34751da177e4SLinus Torvalds 34761da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3477463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 34781da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 34791da177e4SLinus Torvalds * send ACK now. 34801da177e4SLinus Torvalds */ 3481463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3482463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 34831da177e4SLinus Torvalds tcp_send_ack(sk); 34841da177e4SLinus Torvalds return; 34851da177e4SLinus Torvalds } 34861da177e4SLinus Torvalds 3487463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3488463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 34891da177e4SLinus Torvalds } 3490463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3491463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3492463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 34931da177e4SLinus Torvalds } 34941da177e4SLinus Torvalds 34951da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 34961da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 34971da177e4SLinus Torvalds { 34981da177e4SLinus Torvalds struct sk_buff *buff; 34991da177e4SLinus Torvalds 3500058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3501058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3502058dc334SIlpo Järvinen return; 3503058dc334SIlpo Järvinen 35049890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK); 35059890092eSFlorian Westphal 35061da177e4SLinus Torvalds /* We are not putting this on the write queue, so 35071da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 35081da177e4SLinus Torvalds * sock. 35091da177e4SLinus Torvalds */ 35107450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 35117450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 35127450aaf6SEric Dumazet if (unlikely(!buff)) { 3513463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3514463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 35153f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 35163f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 35171da177e4SLinus Torvalds return; 35181da177e4SLinus Torvalds } 35191da177e4SLinus Torvalds 35201da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 35211da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3522a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 35231da177e4SLinus Torvalds 352498781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 352598781965SEric Dumazet * too much. 352698781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 352798781965SEric Dumazet * We also avoid tcp_wfree() overhead (cache line miss accessing 352898781965SEric Dumazet * tp->tsq_flags) by using regular sock_wfree() 352998781965SEric Dumazet */ 353098781965SEric Dumazet skb_set_tcp_pure_ack(buff); 353198781965SEric Dumazet 35321da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 35337faee5c0SEric Dumazet skb_mstamp_get(&buff->skb_mstamp); 35347450aaf6SEric Dumazet tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0); 35351da177e4SLinus Torvalds } 3536e3118e83SDaniel Borkmann EXPORT_SYMBOL_GPL(tcp_send_ack); 35371da177e4SLinus Torvalds 35381da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 35391da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 35401da177e4SLinus Torvalds * 35411da177e4SLinus Torvalds * Question: what should we make while urgent mode? 35421da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 35431da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 35441da177e4SLinus Torvalds * 35451da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 35461da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 35471da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 35481da177e4SLinus Torvalds */ 3549e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 35501da177e4SLinus Torvalds { 35511da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 35521da177e4SLinus Torvalds struct sk_buff *skb; 35531da177e4SLinus Torvalds 35541da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 35557450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 35567450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 355751456b29SIan Morris if (!skb) 35581da177e4SLinus Torvalds return -1; 35591da177e4SLinus Torvalds 35601da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 35611da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 35621da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 35631da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 35641da177e4SLinus Torvalds * send it. 35651da177e4SLinus Torvalds */ 3566a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 35677faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 3568e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 35697450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 35701da177e4SLinus Torvalds } 35711da177e4SLinus Torvalds 3572ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3573ee995283SPavel Emelyanov { 3574ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3575ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 3576e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 3577ee995283SPavel Emelyanov } 3578ee995283SPavel Emelyanov } 3579ee995283SPavel Emelyanov 358067edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 3581e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 35821da177e4SLinus Torvalds { 35831da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 35841da177e4SLinus Torvalds struct sk_buff *skb; 35851da177e4SLinus Torvalds 3586058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3587058dc334SIlpo Järvinen return -1; 3588058dc334SIlpo Järvinen 358900db4124SIan Morris skb = tcp_send_head(sk); 359000db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 35911da177e4SLinus Torvalds int err; 35920c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 359390840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 35941da177e4SLinus Torvalds 35951da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 35961da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 35971da177e4SLinus Torvalds 35981da177e4SLinus Torvalds /* We are probing the opening of a window 35991da177e4SLinus Torvalds * but the window size is != 0 36001da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 36011da177e4SLinus Torvalds */ 36021da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 36031da177e4SLinus Torvalds skb->len > mss) { 36041da177e4SLinus Torvalds seg_size = min(seg_size, mss); 36054de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 36066cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) 36071da177e4SLinus Torvalds return -1; 36081da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 36095bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 36101da177e4SLinus Torvalds 36114de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3612dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 361366f5fe62SIlpo Järvinen if (!err) 361466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 36151da177e4SLinus Torvalds return err; 36161da177e4SLinus Torvalds } else { 361733f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 3618e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 3619e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 36201da177e4SLinus Torvalds } 36211da177e4SLinus Torvalds } 36221da177e4SLinus Torvalds 36231da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 36241da177e4SLinus Torvalds * a partial packet else a zero probe. 36251da177e4SLinus Torvalds */ 36261da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 36271da177e4SLinus Torvalds { 3628463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 36291da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3630c6214a97SNikolay Borisov struct net *net = sock_net(sk); 3631fcdd1cf4SEric Dumazet unsigned long probe_max; 36321da177e4SLinus Torvalds int err; 36331da177e4SLinus Torvalds 3634e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 36351da177e4SLinus Torvalds 3636fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 36371da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 36386687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3639463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 36401da177e4SLinus Torvalds return; 36411da177e4SLinus Torvalds } 36421da177e4SLinus Torvalds 36431da177e4SLinus Torvalds if (err <= 0) { 3644c6214a97SNikolay Borisov if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) 3645463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 36466687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3647fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 36481da177e4SLinus Torvalds } else { 36491da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 36506687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 36511da177e4SLinus Torvalds * Let local senders to fight for local resources. 36521da177e4SLinus Torvalds * 36531da177e4SLinus Torvalds * Use accumulated backoff yet. 36541da177e4SLinus Torvalds */ 36556687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 36566687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3657fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 36581da177e4SLinus Torvalds } 3659fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 366021c8fe99SEric Dumazet tcp_probe0_when(sk, probe_max), 3661fcdd1cf4SEric Dumazet TCP_RTO_MAX); 36621da177e4SLinus Torvalds } 36635db92c99SOctavian Purdila 3664ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 36655db92c99SOctavian Purdila { 36665db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 36675db92c99SOctavian Purdila struct flowi fl; 36685db92c99SOctavian Purdila int res; 36695db92c99SOctavian Purdila 367058d607d3SEric Dumazet tcp_rsk(req)->txhash = net_tx_rndhash(); 3671b3d05147SEric Dumazet res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); 36725db92c99SOctavian Purdila if (!res) { 367390bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 367402a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 36757e32b443SYuchung Cheng if (unlikely(tcp_passive_fastopen(sk))) 36767e32b443SYuchung Cheng tcp_sk(sk)->total_retrans++; 36775db92c99SOctavian Purdila } 36785db92c99SOctavian Purdila return res; 36795db92c99SOctavian Purdila } 36805db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3681