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; 64395a22caeSFlorian Westphal opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; 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 78740fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 78840fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 78940fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 79040fc3423SEric Dumazet TCPF_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 81140fc3423SEric Dumazet if (flags & TCPF_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 82540fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 8266f458dfbSEric Dumazet tcp_write_timer_handler(sk); 827144d56e9SEric Dumazet __sock_put(sk); 828144d56e9SEric Dumazet } 82940fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 8306f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 831144d56e9SEric Dumazet __sock_put(sk); 832144d56e9SEric Dumazet } 83340fc3423SEric Dumazet if (flags & TCPF_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); 863*408f0a6cSEric Dumazet unsigned long flags, nval, oval; 8649b462d02SEric Dumazet int wmem; 8659b462d02SEric Dumazet 8669b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 8679b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 8689b462d02SEric Dumazet */ 8699b462d02SEric Dumazet wmem = atomic_sub_return(skb->truesize - 1, &sk->sk_wmem_alloc); 8709b462d02SEric Dumazet 8719b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 8729b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 8739b462d02SEric Dumazet * This gives : 8749b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 8759b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 8769b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 8779b462d02SEric Dumazet */ 8789b462d02SEric Dumazet if (wmem >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 8799b462d02SEric Dumazet goto out; 88046d3ceabSEric Dumazet 881*408f0a6cSEric Dumazet for (oval = READ_ONCE(tp->tsq_flags);; oval = nval) { 88246d3ceabSEric Dumazet struct tsq_tasklet *tsq; 88346d3ceabSEric Dumazet 884*408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 885*408f0a6cSEric Dumazet goto out; 886*408f0a6cSEric Dumazet 887*408f0a6cSEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; 888*408f0a6cSEric Dumazet nval = cmpxchg(&tp->tsq_flags, oval, nval); 889*408f0a6cSEric Dumazet if (nval != oval) 890*408f0a6cSEric Dumazet continue; 891*408f0a6cSEric Dumazet 89246d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 89346d3ceabSEric Dumazet local_irq_save(flags); 894903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 89546d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 89646d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 89746d3ceabSEric Dumazet local_irq_restore(flags); 8989b462d02SEric Dumazet return; 89946d3ceabSEric Dumazet } 9009b462d02SEric Dumazet out: 9019b462d02SEric Dumazet sk_free(sk); 90246d3ceabSEric Dumazet } 90346d3ceabSEric Dumazet 9041da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 9051da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 9061da177e4SLinus Torvalds * transmission and possible later retransmissions. 9071da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 9081da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 9091da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 9101da177e4SLinus Torvalds * device. 9111da177e4SLinus Torvalds * 9121da177e4SLinus Torvalds * We are working here with either a clone of the original 9131da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 9141da177e4SLinus Torvalds */ 915056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 916056834d9SIlpo Järvinen gfp_t gfp_mask) 9171da177e4SLinus Torvalds { 9186687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 919dfb4b9dcSDavid S. Miller struct inet_sock *inet; 920dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 921dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 92233ad798cSAdam Langley struct tcp_out_options opts; 92395c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 924cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 9251da177e4SLinus Torvalds struct tcphdr *th; 9261da177e4SLinus Torvalds int err; 9271da177e4SLinus Torvalds 928dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 9296f094b9eSLawrence Brakmo tp = tcp_sk(sk); 930dfb4b9dcSDavid S. Miller 931ccdbb6e9SEric Dumazet if (clone_it) { 932740b0f18SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 9336f094b9eSLawrence Brakmo TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq 9346f094b9eSLawrence Brakmo - tp->snd_una; 935b9f64820SYuchung Cheng tcp_rate_skb_sent(sk, skb); 936dfb4b9dcSDavid S. Miller 937dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 938dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 939dfb4b9dcSDavid S. Miller else 940dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 941dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 942dfb4b9dcSDavid S. Miller return -ENOBUFS; 943dfb4b9dcSDavid S. Miller } 944dfb4b9dcSDavid S. Miller 945dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 946dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 94733ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 9481da177e4SLinus Torvalds 9494de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 95033ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 95133ad798cSAdam Langley else 95233ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 95333ad798cSAdam Langley &md5); 95433ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 9551da177e4SLinus Torvalds 956547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 957b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 958b2532eb9SEric Dumazet * which holds one reference to sk_wmem_alloc. 959b2532eb9SEric Dumazet * 960b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 961b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 962547669d4SEric Dumazet */ 963b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 9641da177e4SLinus Torvalds 965aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 966aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 96746d3ceabSEric Dumazet 96846d3ceabSEric Dumazet skb_orphan(skb); 96946d3ceabSEric Dumazet skb->sk = sk; 9701d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 971b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 97246d3ceabSEric Dumazet atomic_add(skb->truesize, &sk->sk_wmem_alloc); 9731da177e4SLinus Torvalds 9741da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 975ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 976c720c7e8SEric Dumazet th->source = inet->inet_sport; 977c720c7e8SEric Dumazet th->dest = inet->inet_dport; 9781da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 9791da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 980df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 9814de075e0SEric Dumazet tcb->tcp_flags); 982dfb4b9dcSDavid S. Miller 9831da177e4SLinus Torvalds th->check = 0; 9841da177e4SLinus Torvalds th->urg_ptr = 0; 9851da177e4SLinus Torvalds 98633f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 9877691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 9887691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 9891da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 9901da177e4SLinus Torvalds th->urg = 1; 9917691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 9920eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 9937691367dSHerbert Xu th->urg = 1; 9947691367dSHerbert Xu } 9951da177e4SLinus Torvalds } 9961da177e4SLinus Torvalds 997bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 99851466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 999ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1000ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1001ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1002ea1627c2SEric Dumazet } else { 1003ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1004ea1627c2SEric Dumazet * is never scaled. 1005ea1627c2SEric Dumazet */ 1006ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1007ea1627c2SEric Dumazet } 1008cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1009cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1010cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1011a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1012bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 101339f8e58eSEric Dumazet md5, sk, skb); 1014cfb6eeb4SYOSHIFUJI Hideaki } 1015cfb6eeb4SYOSHIFUJI Hideaki #endif 1016cfb6eeb4SYOSHIFUJI Hideaki 1017bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 10181da177e4SLinus Torvalds 10194de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 1020fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 10211da177e4SLinus Torvalds 1022a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1023cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1024a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1025a44d6eacSMartin KaFai Lau } 10261da177e4SLinus Torvalds 1027bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1028aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1029aa2ea058STom Herbert tcp_skb_pcount(skb)); 10301da177e4SLinus Torvalds 10312efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 1032f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1033cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1034f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1035cd7d8498SEric Dumazet 10367faee5c0SEric Dumazet /* Our usage of tstamp should remain private */ 10377faee5c0SEric Dumazet skb->tstamp.tv64 = 0; 1038971f10ecSEric Dumazet 1039971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1040971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1041971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1042971f10ecSEric Dumazet 1043b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 10447faee5c0SEric Dumazet 104583de47cdSHua Zhong if (likely(err <= 0)) 10461da177e4SLinus Torvalds return err; 10471da177e4SLinus Torvalds 10485ee2c941SChristoph Paasch tcp_enter_cwr(sk); 10491da177e4SLinus Torvalds 1050b9df3cb8SGerrit Renker return net_xmit_eval(err); 10511da177e4SLinus Torvalds } 10521da177e4SLinus Torvalds 105367edfef7SAndi Kleen /* This routine just queues the buffer for sending. 10541da177e4SLinus Torvalds * 10551da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 10561da177e4SLinus Torvalds * otherwise socket can stall. 10571da177e4SLinus Torvalds */ 10581da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 10591da177e4SLinus Torvalds { 10601da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10611da177e4SLinus Torvalds 10621da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 10631da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1064f4a775d1SEric Dumazet __skb_header_release(skb); 1065fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 10663ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 10673ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 10681da177e4SLinus Torvalds } 10691da177e4SLinus Torvalds 107067edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 10715bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1072f6302d1dSDavid S. Miller { 10738f26fb1cSEric Dumazet if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { 1074f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1075f6302d1dSDavid S. Miller * non-TSO case. 1076f6302d1dSDavid S. Miller */ 1077cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1078f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1079f6302d1dSDavid S. Miller } else { 1080cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1081f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 10821da177e4SLinus Torvalds } 10831da177e4SLinus Torvalds } 10841da177e4SLinus Torvalds 108591fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 108668f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 108791fed7a1SIlpo Järvinen */ 1088cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 108991fed7a1SIlpo Järvinen int decr) 109091fed7a1SIlpo Järvinen { 1091a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1092a47e5a98SIlpo Järvinen 1093dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 109491fed7a1SIlpo Järvinen return; 109591fed7a1SIlpo Järvinen 10966859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 109791fed7a1SIlpo Järvinen tp->fackets_out -= decr; 109891fed7a1SIlpo Järvinen } 109991fed7a1SIlpo Järvinen 1100797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1101797108d1SIlpo Järvinen * tweaks to fix counters 1102797108d1SIlpo Järvinen */ 1103cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1104797108d1SIlpo Järvinen { 1105797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1106797108d1SIlpo Järvinen 1107797108d1SIlpo Järvinen tp->packets_out -= decr; 1108797108d1SIlpo Järvinen 1109797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1110797108d1SIlpo Järvinen tp->sacked_out -= decr; 1111797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1112797108d1SIlpo Järvinen tp->retrans_out -= decr; 1113797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1114797108d1SIlpo Järvinen tp->lost_out -= decr; 1115797108d1SIlpo Järvinen 1116797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1117797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1118797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1119797108d1SIlpo Järvinen 1120797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1121797108d1SIlpo Järvinen 1122797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1123797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 112452cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1125797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1126797108d1SIlpo Järvinen 1127797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1128797108d1SIlpo Järvinen } 1129797108d1SIlpo Järvinen 11300a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 11310a2cf20cSSoheil Hassas Yeganeh { 11320a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 11330a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 11340a2cf20cSSoheil Hassas Yeganeh } 11350a2cf20cSSoheil Hassas Yeganeh 1136490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1137490cc7d0SWillem de Bruijn { 1138490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1139490cc7d0SWillem de Bruijn 11400a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1141490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1142490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1143490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1144490cc7d0SWillem de Bruijn 1145490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1146490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1147490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1148b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1149b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1150490cc7d0SWillem de Bruijn } 1151490cc7d0SWillem de Bruijn } 1152490cc7d0SWillem de Bruijn 1153a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1154a166140eSMartin KaFai Lau { 1155a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1156a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1157a166140eSMartin KaFai Lau } 1158a166140eSMartin KaFai Lau 11591da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 11601da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 11611da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 11621da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 11631da177e4SLinus Torvalds */ 1164056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 11656cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 11661da177e4SLinus Torvalds { 11671da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11681da177e4SLinus Torvalds struct sk_buff *buff; 11696475be16SDavid S. Miller int nsize, old_factor; 1170b60b49eaSHerbert Xu int nlen; 11719ce01461SIlpo Järvinen u8 flags; 11721da177e4SLinus Torvalds 11732fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 11742fceec13SIlpo Järvinen return -EINVAL; 11756a438bbeSStephen Hemminger 11761da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 11771da177e4SLinus Torvalds if (nsize < 0) 11781da177e4SLinus Torvalds nsize = 0; 11791da177e4SLinus Torvalds 11806cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 11811da177e4SLinus Torvalds return -ENOMEM; 11821da177e4SLinus Torvalds 11831da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 1184eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, nsize, gfp, true); 118551456b29SIan Morris if (!buff) 11861da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1187ef5cb973SHerbert Xu 11883ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 11893ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1190b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1191b60b49eaSHerbert Xu buff->truesize += nlen; 1192b60b49eaSHerbert Xu skb->truesize -= nlen; 11931da177e4SLinus Torvalds 11941da177e4SLinus Torvalds /* Correct the sequence numbers. */ 11951da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 11961da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 11971da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 11981da177e4SLinus Torvalds 11991da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 12004de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 12014de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 12024de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1203e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1204a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 12051da177e4SLinus Torvalds 120684fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 12071da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1208056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1209056834d9SIlpo Järvinen skb_put(buff, nsize), 12101da177e4SLinus Torvalds nsize, 0); 12111da177e4SLinus Torvalds 12121da177e4SLinus Torvalds skb_trim(skb, len); 12131da177e4SLinus Torvalds 12141da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 12151da177e4SLinus Torvalds } else { 121684fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 12171da177e4SLinus Torvalds skb_split(skb, buff, len); 12181da177e4SLinus Torvalds } 12191da177e4SLinus Torvalds 12201da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 12211da177e4SLinus Torvalds 1222a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1223490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 12241da177e4SLinus Torvalds 12256475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 12266475be16SDavid S. Miller 12271da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 12285bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 12295bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 12301da177e4SLinus Torvalds 1231b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1232b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1233b9f64820SYuchung Cheng 12346475be16SDavid S. Miller /* If this packet has been sent out already, we must 12356475be16SDavid S. Miller * adjust the various packet counters. 12366475be16SDavid S. Miller */ 1237cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 12386475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 12396475be16SDavid S. Miller tcp_skb_pcount(buff); 12401da177e4SLinus Torvalds 1241797108d1SIlpo Järvinen if (diff) 1242797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 12431da177e4SLinus Torvalds } 12441da177e4SLinus Torvalds 12451da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1246f4a775d1SEric Dumazet __skb_header_release(buff); 1247fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 12481da177e4SLinus Torvalds 12491da177e4SLinus Torvalds return 0; 12501da177e4SLinus Torvalds } 12511da177e4SLinus Torvalds 12521da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 12531da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 12541da177e4SLinus Torvalds * immediately discarded. 12551da177e4SLinus Torvalds */ 1256f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 12571da177e4SLinus Torvalds { 12587b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 12591da177e4SLinus Torvalds int i, k, eat; 12601da177e4SLinus Torvalds 12614fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 12624fa48bf3SEric Dumazet if (eat) { 12634fa48bf3SEric Dumazet __skb_pull(skb, eat); 12644fa48bf3SEric Dumazet len -= eat; 12654fa48bf3SEric Dumazet if (!len) 12664fa48bf3SEric Dumazet return; 12674fa48bf3SEric Dumazet } 12681da177e4SLinus Torvalds eat = len; 12691da177e4SLinus Torvalds k = 0; 12707b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 12717b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 12727b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 12739e903e08SEric Dumazet 12749e903e08SEric Dumazet if (size <= eat) { 1275aff65da0SIan Campbell skb_frag_unref(skb, i); 12769e903e08SEric Dumazet eat -= size; 12771da177e4SLinus Torvalds } else { 12787b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 12791da177e4SLinus Torvalds if (eat) { 12807b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 12817b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 12821da177e4SLinus Torvalds eat = 0; 12831da177e4SLinus Torvalds } 12841da177e4SLinus Torvalds k++; 12851da177e4SLinus Torvalds } 12861da177e4SLinus Torvalds } 12877b7fc97aSEric Dumazet shinfo->nr_frags = k; 12881da177e4SLinus Torvalds 128927a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 12901da177e4SLinus Torvalds skb->data_len -= len; 12911da177e4SLinus Torvalds skb->len = skb->data_len; 12921da177e4SLinus Torvalds } 12931da177e4SLinus Torvalds 129467edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 12951da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 12961da177e4SLinus Torvalds { 129714bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 12981da177e4SLinus Torvalds return -ENOMEM; 12991da177e4SLinus Torvalds 13004fa48bf3SEric Dumazet __pskb_trim_head(skb, len); 13011da177e4SLinus Torvalds 13021da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 130384fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 13041da177e4SLinus Torvalds 13051da177e4SLinus Torvalds skb->truesize -= len; 13061da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 13073ab224beSHideo Aoki sk_mem_uncharge(sk, len); 13081da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 13091da177e4SLinus Torvalds 13105b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 13111da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 13125bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 13131da177e4SLinus Torvalds 13141da177e4SLinus Torvalds return 0; 13151da177e4SLinus Torvalds } 13161da177e4SLinus Torvalds 13171b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 13181b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 13195d424d5aSJohn Heffner { 1320cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1321cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 13225d424d5aSJohn Heffner int mss_now; 13235d424d5aSJohn Heffner 13245d424d5aSJohn Heffner /* Calculate base mss without TCP options: 13255d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 13265d424d5aSJohn Heffner */ 13275d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 13285d424d5aSJohn Heffner 132967469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 133067469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 133167469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 133267469601SEric Dumazet 133367469601SEric Dumazet if (dst && dst_allfrag(dst)) 133467469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 133567469601SEric Dumazet } 133667469601SEric Dumazet 13375d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 13385d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 13395d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 13405d424d5aSJohn Heffner 13415d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 13425d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 13435d424d5aSJohn Heffner 13445d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 13455d424d5aSJohn Heffner if (mss_now < 48) 13465d424d5aSJohn Heffner mss_now = 48; 13475d424d5aSJohn Heffner return mss_now; 13485d424d5aSJohn Heffner } 13495d424d5aSJohn Heffner 13501b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 13511b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 13521b63edd6SYuchung Cheng { 13531b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 13541b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 13551b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 13561b63edd6SYuchung Cheng } 13571b63edd6SYuchung Cheng 13585d424d5aSJohn Heffner /* Inverse of above */ 135967469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 13605d424d5aSJohn Heffner { 1361cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1362cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 13635d424d5aSJohn Heffner int mtu; 13645d424d5aSJohn Heffner 13655d424d5aSJohn Heffner mtu = mss + 13665d424d5aSJohn Heffner tp->tcp_header_len + 13675d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 13685d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 13695d424d5aSJohn Heffner 137067469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 137167469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 137267469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 137367469601SEric Dumazet 137467469601SEric Dumazet if (dst && dst_allfrag(dst)) 137567469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 137667469601SEric Dumazet } 13775d424d5aSJohn Heffner return mtu; 13785d424d5aSJohn Heffner } 1379556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 13805d424d5aSJohn Heffner 138167edfef7SAndi Kleen /* MTU probing init per socket */ 13825d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 13835d424d5aSJohn Heffner { 13845d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 13855d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1386b0f9ca53SFan Du struct net *net = sock_net(sk); 13875d424d5aSJohn Heffner 1388b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 13895d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 13905d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1391b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 13925d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 139305cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 139405cbc0dbSFan Du icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; 13955d424d5aSJohn Heffner } 13964bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 13975d424d5aSJohn Heffner 13981da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 13991da177e4SLinus Torvalds 14001da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 14011da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 14021da177e4SLinus Torvalds 14031da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1404caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 14051da177e4SLinus Torvalds It also does not include TCP options. 14061da177e4SLinus Torvalds 1407d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 14101da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 14111da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 14121da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 14151da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 14161da177e4SLinus Torvalds 1417d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1418d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 14191da177e4SLinus Torvalds */ 14201da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 14211da177e4SLinus Torvalds { 14221da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1423d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 14245d424d5aSJohn Heffner int mss_now; 14251da177e4SLinus Torvalds 14265d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 14275d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 14281da177e4SLinus Torvalds 14295d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1430409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 14311da177e4SLinus Torvalds 14321da177e4SLinus Torvalds /* And store cached results */ 1433d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 14345d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 14355d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1436c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 14371da177e4SLinus Torvalds 14381da177e4SLinus Torvalds return mss_now; 14391da177e4SLinus Torvalds } 14404bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 14431da177e4SLinus Torvalds * and even PMTU discovery events into account. 14441da177e4SLinus Torvalds */ 14450c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 14461da177e4SLinus Torvalds { 1447cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1448cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1449c1b4a7e6SDavid S. Miller u32 mss_now; 145095c96174SEric Dumazet unsigned int header_len; 145133ad798cSAdam Langley struct tcp_out_options opts; 145233ad798cSAdam Langley struct tcp_md5sig_key *md5; 14531da177e4SLinus Torvalds 1454c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1455c1b4a7e6SDavid S. Miller 14561da177e4SLinus Torvalds if (dst) { 14571da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1458d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 14591da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 14601da177e4SLinus Torvalds } 14611da177e4SLinus Torvalds 146233ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 146333ad798cSAdam Langley sizeof(struct tcphdr); 146433ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 146533ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 146633ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 146733ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 146833ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 146933ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 147033ad798cSAdam Langley mss_now -= delta; 147133ad798cSAdam Langley } 1472cfb6eeb4SYOSHIFUJI Hideaki 14731da177e4SLinus Torvalds return mss_now; 14741da177e4SLinus Torvalds } 14751da177e4SLinus Torvalds 147686fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 147786fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 147886fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 147986fd14adSWeiping Pan */ 148086fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1481a762a980SDavid S. Miller { 14829e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1483a762a980SDavid S. Miller 148486fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 148586fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 148686fd14adSWeiping Pan /* Limited by application or receiver window. */ 148786fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 148886fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 148986fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 149086fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 149186fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 149286fd14adSWeiping Pan } 149386fd14adSWeiping Pan tp->snd_cwnd_used = 0; 149486fd14adSWeiping Pan } 149586fd14adSWeiping Pan tp->snd_cwnd_stamp = tcp_time_stamp; 149686fd14adSWeiping Pan } 149786fd14adSWeiping Pan 1498ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1499a762a980SDavid S. Miller { 1500a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1501a762a980SDavid S. Miller 1502ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1503ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1504ca8a2263SNeal Cardwell */ 1505ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1506ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1507ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1508ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1509ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1510ca8a2263SNeal Cardwell } 1511e114a710SEric Dumazet 151224901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1513a762a980SDavid S. Miller /* Network is feed fully. */ 1514a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1515a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1516a762a980SDavid S. Miller } else { 1517a762a980SDavid S. Miller /* Network starves. */ 1518a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1519a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1520a762a980SDavid S. Miller 152115d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 152215d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1523a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1524b0f71bd3SFrancis Yan 1525b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1526b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1527b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1528b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 1529b0f71bd3SFrancis Yan * 3) no more data to send (null tcp_send_head ) 1530b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1531b0f71bd3SFrancis Yan */ 1532b0f71bd3SFrancis Yan if (!tcp_send_head(sk) && sk->sk_socket && 1533b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1534b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1535b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1536a762a980SDavid S. Miller } 1537a762a980SDavid S. Miller } 1538a762a980SDavid S. Miller 1539d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1540d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1541d4589926SEric Dumazet { 1542d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1543d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1544d4589926SEric Dumazet } 1545d4589926SEric Dumazet 1546d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1547d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1548d4589926SEric Dumazet * The test is really : 1549d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1550d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1551d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1552d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 15530e3a4803SIlpo Järvinen */ 1554d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1555d4589926SEric Dumazet const struct sk_buff *skb) 1556d4589926SEric Dumazet { 1557d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1558d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1559d4589926SEric Dumazet } 1560d4589926SEric Dumazet 1561d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1562d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1563d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1564d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1565d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1566d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1567d4589926SEric Dumazet */ 1568d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1569cc93fc51SPeter Pan(潘卫平) int nonagle) 1570d4589926SEric Dumazet { 1571d4589926SEric Dumazet return partial && 1572d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1573d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1574d4589926SEric Dumazet } 1575605ad7f1SEric Dumazet 1576605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1577605ad7f1SEric Dumazet * to send one TSO packet per ms 1578605ad7f1SEric Dumazet */ 15791b3878caSNeal Cardwell u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 15801b3878caSNeal Cardwell int min_tso_segs) 1581605ad7f1SEric Dumazet { 1582605ad7f1SEric Dumazet u32 bytes, segs; 1583605ad7f1SEric Dumazet 1584605ad7f1SEric Dumazet bytes = min(sk->sk_pacing_rate >> 10, 1585605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1586605ad7f1SEric Dumazet 1587605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1588605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1589605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1590605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1591605ad7f1SEric Dumazet */ 15921b3878caSNeal Cardwell segs = max_t(u32, bytes / mss_now, min_tso_segs); 1593605ad7f1SEric Dumazet 1594605ad7f1SEric Dumazet return min_t(u32, segs, sk->sk_gso_max_segs); 1595605ad7f1SEric Dumazet } 15961b3878caSNeal Cardwell EXPORT_SYMBOL(tcp_tso_autosize); 1597605ad7f1SEric Dumazet 1598ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1599ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1600ed6e7268SNeal Cardwell */ 1601ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1602ed6e7268SNeal Cardwell { 1603ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1604ed6e7268SNeal Cardwell u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0; 1605ed6e7268SNeal Cardwell 16061b3878caSNeal Cardwell return tso_segs ? : 16071b3878caSNeal Cardwell tcp_tso_autosize(sk, mss_now, sysctl_tcp_min_tso_segs); 1608ed6e7268SNeal Cardwell } 1609ed6e7268SNeal Cardwell 1610d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1611d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1612d4589926SEric Dumazet const struct sk_buff *skb, 1613d4589926SEric Dumazet unsigned int mss_now, 1614d4589926SEric Dumazet unsigned int max_segs, 1615d4589926SEric Dumazet int nonagle) 1616c1b4a7e6SDavid S. Miller { 1617cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1618d4589926SEric Dumazet u32 partial, needed, window, max_len; 1619c1b4a7e6SDavid S. Miller 162090840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 16211485348dSBen Hutchings max_len = mss_now * max_segs; 16220e3a4803SIlpo Järvinen 16231485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 16241485348dSBen Hutchings return max_len; 16250e3a4803SIlpo Järvinen 16265ea3a748SIlpo Järvinen needed = min(skb->len, window); 16275ea3a748SIlpo Järvinen 16281485348dSBen Hutchings if (max_len <= needed) 16291485348dSBen Hutchings return max_len; 16300e3a4803SIlpo Järvinen 1631d4589926SEric Dumazet partial = needed % mss_now; 1632d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1633d4589926SEric Dumazet * to include this last segment in this skb. 1634d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1635d4589926SEric Dumazet */ 1636cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1637d4589926SEric Dumazet return needed - partial; 1638d4589926SEric Dumazet 1639d4589926SEric Dumazet return needed; 1640c1b4a7e6SDavid S. Miller } 1641c1b4a7e6SDavid S. Miller 1642c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1643c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1644c1b4a7e6SDavid S. Miller */ 1645cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1646cf533ea5SEric Dumazet const struct sk_buff *skb) 1647c1b4a7e6SDavid S. Miller { 1648d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1649c1b4a7e6SDavid S. Miller 1650c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 16514de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 16524de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1653c1b4a7e6SDavid S. Miller return 1; 1654c1b4a7e6SDavid S. Miller 1655c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1656c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1657d649a7a8SEric Dumazet if (in_flight >= cwnd) 1658c1b4a7e6SDavid S. Miller return 0; 1659d649a7a8SEric Dumazet 1660d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1661d649a7a8SEric Dumazet * 2 GSO packets in flight. 1662d649a7a8SEric Dumazet */ 1663d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1664d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1665c1b4a7e6SDavid S. Miller } 1666c1b4a7e6SDavid S. Miller 1667b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 166867edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1669c1b4a7e6SDavid S. Miller * SKB onto the wire. 1670c1b4a7e6SDavid S. Miller */ 16715bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1672c1b4a7e6SDavid S. Miller { 1673c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1674c1b4a7e6SDavid S. Miller 1675f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 16765bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 1677c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1678c1b4a7e6SDavid S. Miller } 1679c1b4a7e6SDavid S. Miller return tso_segs; 1680c1b4a7e6SDavid S. Miller } 1681c1b4a7e6SDavid S. Miller 1682c1b4a7e6SDavid S. Miller 1683a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1684c1b4a7e6SDavid S. Miller * sent now. 1685c1b4a7e6SDavid S. Miller */ 1686a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1687c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1688c1b4a7e6SDavid S. Miller { 1689c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1690c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1691c1b4a7e6SDavid S. Miller * 1692c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1693c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1694c1b4a7e6SDavid S. Miller */ 1695c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1696a2a385d6SEric Dumazet return true; 1697c1b4a7e6SDavid S. Miller 16989b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 16999b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1700a2a385d6SEric Dumazet return true; 1701c1b4a7e6SDavid S. Miller 1702cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1703a2a385d6SEric Dumazet return true; 1704c1b4a7e6SDavid S. Miller 1705a2a385d6SEric Dumazet return false; 1706c1b4a7e6SDavid S. Miller } 1707c1b4a7e6SDavid S. Miller 1708c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1709a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1710a2a385d6SEric Dumazet const struct sk_buff *skb, 1711056834d9SIlpo Järvinen unsigned int cur_mss) 1712c1b4a7e6SDavid S. Miller { 1713c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1714c1b4a7e6SDavid S. Miller 1715c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1716c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1717c1b4a7e6SDavid S. Miller 171890840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1719c1b4a7e6SDavid S. Miller } 1720c1b4a7e6SDavid S. Miller 1721fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1722c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1723c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1724c1b4a7e6SDavid S. Miller */ 1725cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1726c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1727c1b4a7e6SDavid S. Miller { 1728cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1729c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1730c1b4a7e6SDavid S. Miller 17315bbb432cSEric Dumazet tcp_init_tso_segs(skb, cur_mss); 1732c1b4a7e6SDavid S. Miller 1733c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1734c1b4a7e6SDavid S. Miller return 0; 1735c1b4a7e6SDavid S. Miller 1736c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1737056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1738c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1739c1b4a7e6SDavid S. Miller 1740c1b4a7e6SDavid S. Miller return cwnd_quota; 1741c1b4a7e6SDavid S. Miller } 1742c1b4a7e6SDavid S. Miller 174367edfef7SAndi Kleen /* Test if sending is allowed right now. */ 1744a2a385d6SEric Dumazet bool tcp_may_send_now(struct sock *sk) 1745c1b4a7e6SDavid S. Miller { 1746cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1747fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1748c1b4a7e6SDavid S. Miller 1749a02cec21SEric Dumazet return skb && 17500c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1751c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1752a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1753c1b4a7e6SDavid S. Miller } 1754c1b4a7e6SDavid S. Miller 1755c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1756c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1757c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1758c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1759c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1760c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1761c1b4a7e6SDavid S. Miller */ 1762056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1763c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1764c1b4a7e6SDavid S. Miller { 1765c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1766c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 17679ce01461SIlpo Järvinen u8 flags; 1768c1b4a7e6SDavid S. Miller 1769c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1770c8ac3774SHerbert Xu if (skb->len != skb->data_len) 17716cc55e09SOctavian Purdila return tcp_fragment(sk, skb, len, mss_now, gfp); 1772c1b4a7e6SDavid S. Miller 1773eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp, true); 177451456b29SIan Morris if (unlikely(!buff)) 1775c1b4a7e6SDavid S. Miller return -ENOMEM; 1776c1b4a7e6SDavid S. Miller 17773ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 17783ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1779b60b49eaSHerbert Xu buff->truesize += nlen; 1780c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1781c1b4a7e6SDavid S. Miller 1782c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1783c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1784c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1785c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1786c1b4a7e6SDavid S. Miller 1787c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 17884de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 17894de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 17904de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1791c1b4a7e6SDavid S. Miller 1792c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1793c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1794c1b4a7e6SDavid S. Miller 1795a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 1796a166140eSMartin KaFai Lau 179784fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1798c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1799490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1800c1b4a7e6SDavid S. Miller 1801c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 18025bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 18035bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 1804c1b4a7e6SDavid S. Miller 1805c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1806f4a775d1SEric Dumazet __skb_header_release(buff); 1807fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1808c1b4a7e6SDavid S. Miller 1809c1b4a7e6SDavid S. Miller return 0; 1810c1b4a7e6SDavid S. Miller } 1811c1b4a7e6SDavid S. Miller 1812c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1813c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1814c1b4a7e6SDavid S. Miller * 1815c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1816c1b4a7e6SDavid S. Miller */ 1817ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1818605ad7f1SEric Dumazet bool *is_cwnd_limited, u32 max_segs) 1819c1b4a7e6SDavid S. Miller { 18206687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 182150c8339eSEric Dumazet u32 age, send_win, cong_win, limit, in_flight; 182250c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 182350c8339eSEric Dumazet struct skb_mstamp now; 182450c8339eSEric Dumazet struct sk_buff *head; 1825ad9f4f50SEric Dumazet int win_divisor; 1826c1b4a7e6SDavid S. Miller 18274de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1828ae8064acSJohn Heffner goto send_now; 1829c1b4a7e6SDavid S. Miller 183099d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 1831ae8064acSJohn Heffner goto send_now; 1832ae8064acSJohn Heffner 18335f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 18345f852eb5SEric Dumazet * only if the last write was recent. 18355f852eb5SEric Dumazet */ 18365f852eb5SEric Dumazet if ((s32)(tcp_time_stamp - tp->lsndtime) > 0) 1837ae8064acSJohn Heffner goto send_now; 1838908a75c1SDavid S. Miller 1839c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1840c1b4a7e6SDavid S. Miller 1841056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1842c1b4a7e6SDavid S. Miller 184390840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1844c1b4a7e6SDavid S. Miller 1845c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1846c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1847c1b4a7e6SDavid S. Miller 1848c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1849c1b4a7e6SDavid S. Miller 1850ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 1851605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 1852ae8064acSJohn Heffner goto send_now; 1853ba244fe9SDavid S. Miller 185462ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 185562ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 185662ad2761SIlpo Järvinen goto send_now; 185762ad2761SIlpo Järvinen 1858ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1859ad9f4f50SEric Dumazet if (win_divisor) { 1860c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1861c1b4a7e6SDavid S. Miller 1862c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1863c1b4a7e6SDavid S. Miller * just use it. 1864c1b4a7e6SDavid S. Miller */ 1865ad9f4f50SEric Dumazet chunk /= win_divisor; 1866c1b4a7e6SDavid S. Miller if (limit >= chunk) 1867ae8064acSJohn Heffner goto send_now; 1868c1b4a7e6SDavid S. Miller } else { 1869c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1870c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1871c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1872c1b4a7e6SDavid S. Miller * then send now. 1873c1b4a7e6SDavid S. Miller */ 18746b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1875ae8064acSJohn Heffner goto send_now; 1876c1b4a7e6SDavid S. Miller } 1877c1b4a7e6SDavid S. Miller 187850c8339eSEric Dumazet head = tcp_write_queue_head(sk); 187950c8339eSEric Dumazet skb_mstamp_get(&now); 188050c8339eSEric Dumazet age = skb_mstamp_us_delta(&now, &head->skb_mstamp); 188150c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 188250c8339eSEric Dumazet if (age < (tp->srtt_us >> 4)) 188350c8339eSEric Dumazet goto send_now; 188450c8339eSEric Dumazet 18855f852eb5SEric Dumazet /* Ok, it looks like it is advisable to defer. */ 1886ae8064acSJohn Heffner 1887d2e1339fSBendik Rønning Opstad if (cong_win < send_win && cong_win <= skb->len) 1888ca8a2263SNeal Cardwell *is_cwnd_limited = true; 1889ca8a2263SNeal Cardwell 1890a2a385d6SEric Dumazet return true; 1891ae8064acSJohn Heffner 1892ae8064acSJohn Heffner send_now: 1893a2a385d6SEric Dumazet return false; 1894c1b4a7e6SDavid S. Miller } 1895c1b4a7e6SDavid S. Miller 189605cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 189705cbc0dbSFan Du { 189805cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 189905cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 190005cbc0dbSFan Du struct net *net = sock_net(sk); 190105cbc0dbSFan Du u32 interval; 190205cbc0dbSFan Du s32 delta; 190305cbc0dbSFan Du 190405cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 190505cbc0dbSFan Du delta = tcp_time_stamp - icsk->icsk_mtup.probe_timestamp; 190605cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 190705cbc0dbSFan Du int mss = tcp_current_mss(sk); 190805cbc0dbSFan Du 190905cbc0dbSFan Du /* Update current search range */ 191005cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 191105cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 191205cbc0dbSFan Du sizeof(struct tcphdr) + 191305cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 191405cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 191505cbc0dbSFan Du 191605cbc0dbSFan Du /* Update probe time stamp */ 191705cbc0dbSFan Du icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; 191805cbc0dbSFan Du } 191905cbc0dbSFan Du } 192005cbc0dbSFan Du 19215d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 192267edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 192367edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 192467edfef7SAndi Kleen * changes resulting in larger path MTUs. 192567edfef7SAndi Kleen * 19265d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 19275d424d5aSJohn Heffner * 1 if a probe was sent, 1928056834d9SIlpo Järvinen * -1 otherwise 1929056834d9SIlpo Järvinen */ 19305d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 19315d424d5aSJohn Heffner { 19325d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 19335d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 19345d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 19356b58e0a5SFan Du struct net *net = sock_net(sk); 19365d424d5aSJohn Heffner int len; 19375d424d5aSJohn Heffner int probe_size; 193891cc17c0SIlpo Järvinen int size_needed; 19395d424d5aSJohn Heffner int copy; 19405d424d5aSJohn Heffner int mss_now; 19416b58e0a5SFan Du int interval; 19425d424d5aSJohn Heffner 19435d424d5aSJohn Heffner /* Not currently probing/verifying, 19445d424d5aSJohn Heffner * not in recovery, 19455d424d5aSJohn Heffner * have enough cwnd, and 19465d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 19475d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 19485d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 19495d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 19505d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1951cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 19525d424d5aSJohn Heffner return -1; 19535d424d5aSJohn Heffner 19546b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 19556b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 19566b58e0a5SFan Du * smaller than a threshold, backoff from probing. 19576b58e0a5SFan Du */ 19580c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 19596b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 19606b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 196191cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 19626b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 196305cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 196405cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 196505cbc0dbSFan Du * probing process by not resetting search range to its orignal. 196605cbc0dbSFan Du */ 19676b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 196805cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 196905cbc0dbSFan Du /* Check whether enough time has elaplased for 197005cbc0dbSFan Du * another round of probing. 197105cbc0dbSFan Du */ 197205cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 19735d424d5aSJohn Heffner return -1; 19745d424d5aSJohn Heffner } 19755d424d5aSJohn Heffner 19765d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 19777f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 19785d424d5aSJohn Heffner return -1; 19795d424d5aSJohn Heffner 198091cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 19815d424d5aSJohn Heffner return -1; 198290840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 19835d424d5aSJohn Heffner return 0; 19845d424d5aSJohn Heffner 1985d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1986d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1987d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 19885d424d5aSJohn Heffner return -1; 19895d424d5aSJohn Heffner else 19905d424d5aSJohn Heffner return 0; 19915d424d5aSJohn Heffner } 19925d424d5aSJohn Heffner 19935d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 1994eb934478SEric Dumazet nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); 199551456b29SIan Morris if (!nskb) 19965d424d5aSJohn Heffner return -1; 19973ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 19983ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 19995d424d5aSJohn Heffner 2000fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 20015d424d5aSJohn Heffner 20025d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 20035d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 20044de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 20055d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 20065d424d5aSJohn Heffner nskb->csum = 0; 200784fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 20085d424d5aSJohn Heffner 200950c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 201050c4817eSIlpo Järvinen 20115d424d5aSJohn Heffner len = 0; 2012234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 20135d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 20142fe664f1SDouglas Caetano dos Santos if (nskb->ip_summed) { 20155d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 20162fe664f1SDouglas Caetano dos Santos } else { 20172fe664f1SDouglas Caetano dos Santos __wsum csum = skb_copy_and_csum_bits(skb, 0, 2018056834d9SIlpo Järvinen skb_put(nskb, copy), 20192fe664f1SDouglas Caetano dos Santos copy, 0); 20202fe664f1SDouglas Caetano dos Santos nskb->csum = csum_block_add(nskb->csum, csum, len); 20212fe664f1SDouglas Caetano dos Santos } 20225d424d5aSJohn Heffner 20235d424d5aSJohn Heffner if (skb->len <= copy) { 20245d424d5aSJohn Heffner /* We've eaten all the data from this skb. 20255d424d5aSJohn Heffner * Throw it away. */ 20264de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2027fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 20283ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 20295d424d5aSJohn Heffner } else { 20304de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2031a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 20325d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 20335d424d5aSJohn Heffner skb_pull(skb, copy); 203484fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 2035056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 2036056834d9SIlpo Järvinen skb->len, 0); 20375d424d5aSJohn Heffner } else { 20385d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 20395bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 20405d424d5aSJohn Heffner } 20415d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 20425d424d5aSJohn Heffner } 20435d424d5aSJohn Heffner 20445d424d5aSJohn Heffner len += copy; 2045234b6860SIlpo Järvinen 2046234b6860SIlpo Järvinen if (len >= probe_size) 2047234b6860SIlpo Järvinen break; 20485d424d5aSJohn Heffner } 20495bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 20505d424d5aSJohn Heffner 20515d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 20527faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 20537faee5c0SEric Dumazet */ 20545d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 20555d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 20565d424d5aSJohn Heffner * effectively two packets. */ 20575d424d5aSJohn Heffner tp->snd_cwnd--; 205866f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 20595d424d5aSJohn Heffner 20605d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 20610e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 20620e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 20635d424d5aSJohn Heffner 20645d424d5aSJohn Heffner return 1; 20655d424d5aSJohn Heffner } 20665d424d5aSJohn Heffner 20675d424d5aSJohn Heffner return -1; 20685d424d5aSJohn Heffner } 20695d424d5aSJohn Heffner 2070f9616c35SEric Dumazet /* TCP Small Queues : 2071f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2072f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2073f9616c35SEric Dumazet * This allows for : 2074f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2075f9616c35SEric Dumazet * - faster recovery 2076f9616c35SEric Dumazet * - high rates 2077f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2078f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2079f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2080f9616c35SEric Dumazet */ 2081f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2082f9616c35SEric Dumazet unsigned int factor) 2083f9616c35SEric Dumazet { 2084f9616c35SEric Dumazet unsigned int limit; 2085f9616c35SEric Dumazet 2086f9616c35SEric Dumazet limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10); 2087f9616c35SEric Dumazet limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes); 2088f9616c35SEric Dumazet limit <<= factor; 2089f9616c35SEric Dumazet 2090f9616c35SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) { 2091f9616c35SEric Dumazet set_bit(TSQ_THROTTLED, &tcp_sk(sk)->tsq_flags); 2092f9616c35SEric Dumazet /* It is possible TX completion already happened 2093f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2094f9616c35SEric Dumazet * test again the condition. 2095f9616c35SEric Dumazet */ 2096f9616c35SEric Dumazet smp_mb__after_atomic(); 2097f9616c35SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) 2098f9616c35SEric Dumazet return true; 2099f9616c35SEric Dumazet } 2100f9616c35SEric Dumazet return false; 2101f9616c35SEric Dumazet } 2102f9616c35SEric Dumazet 210305b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 210405b055e8SFrancis Yan { 210505b055e8SFrancis Yan const u32 now = tcp_time_stamp; 210605b055e8SFrancis Yan 210705b055e8SFrancis Yan if (tp->chrono_type > TCP_CHRONO_UNSPEC) 210805b055e8SFrancis Yan tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start; 210905b055e8SFrancis Yan tp->chrono_start = now; 211005b055e8SFrancis Yan tp->chrono_type = new; 211105b055e8SFrancis Yan } 211205b055e8SFrancis Yan 211305b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 211405b055e8SFrancis Yan { 211505b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 211605b055e8SFrancis Yan 211705b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 21180f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 21190f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 212005b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 212105b055e8SFrancis Yan */ 212205b055e8SFrancis Yan if (type > tp->chrono_type) 212305b055e8SFrancis Yan tcp_chrono_set(tp, type); 212405b055e8SFrancis Yan } 212505b055e8SFrancis Yan 212605b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 212705b055e8SFrancis Yan { 212805b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 212905b055e8SFrancis Yan 21300f87230dSFrancis Yan 21310f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 21320f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 21330f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 21340f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 21350f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 21360f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 21370f87230dSFrancis Yan */ 21380f87230dSFrancis Yan if (tcp_write_queue_empty(sk)) 213905b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 21400f87230dSFrancis Yan else if (type == tp->chrono_type) 21410f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 214205b055e8SFrancis Yan } 214305b055e8SFrancis Yan 21441da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 21451da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 21461da177e4SLinus Torvalds * window for us. 21471da177e4SLinus Torvalds * 2148f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2149f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2150f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2151f8269a49SIlpo Järvinen * 21526ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 21536ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 21546ba8a3b1SNandita Dukkipati 2155a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2156a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 21571da177e4SLinus Torvalds */ 2158a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2159d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 21601da177e4SLinus Torvalds { 21611da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 216292df7b51SDavid S. Miller struct sk_buff *skb; 2163c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2164c1b4a7e6SDavid S. Miller int cwnd_quota; 21655d424d5aSJohn Heffner int result; 21665615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2167605ad7f1SEric Dumazet u32 max_segs; 21681da177e4SLinus Torvalds 2169c1b4a7e6SDavid S. Miller sent_pkts = 0; 21705d424d5aSJohn Heffner 2171d5dd9175SIlpo Järvinen if (!push_one) { 21725d424d5aSJohn Heffner /* Do MTU probing. */ 2173d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2174d5dd9175SIlpo Järvinen if (!result) { 2175a2a385d6SEric Dumazet return false; 21765d424d5aSJohn Heffner } else if (result > 0) { 21775d424d5aSJohn Heffner sent_pkts = 1; 21785d424d5aSJohn Heffner } 2179d5dd9175SIlpo Järvinen } 21805d424d5aSJohn Heffner 2181ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2182fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2183c8ac3774SHerbert Xu unsigned int limit; 2184c8ac3774SHerbert Xu 21855bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2186c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2187c1b4a7e6SDavid S. Miller 21889d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 21897faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 21907faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 2191ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 21929d186cacSAndrey Vagin } 2193ec342325SAndrew Vagin 2194b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 21956ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 21966ba8a3b1SNandita Dukkipati if (push_one == 2) 21976ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 21986ba8a3b1SNandita Dukkipati cwnd_quota = 1; 21996ba8a3b1SNandita Dukkipati else 2200b68e9f85SHerbert Xu break; 22016ba8a3b1SNandita Dukkipati } 2202b68e9f85SHerbert Xu 22035615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 22045615f886SFrancis Yan is_rwnd_limited = true; 2205b68e9f85SHerbert Xu break; 22065615f886SFrancis Yan } 2207b68e9f85SHerbert Xu 2208d6a4e26aSEric Dumazet if (tso_segs == 1) { 2209aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2210aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2211aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2212aa93466bSDavid S. Miller break; 2213c1b4a7e6SDavid S. Miller } else { 2214ca8a2263SNeal Cardwell if (!push_one && 2215605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2216605ad7f1SEric Dumazet max_segs)) 2217aa93466bSDavid S. Miller break; 2218c1b4a7e6SDavid S. Miller } 2219aa93466bSDavid S. Miller 2220605ad7f1SEric Dumazet limit = mss_now; 2221d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2222605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2223605ad7f1SEric Dumazet min_t(unsigned int, 2224605ad7f1SEric Dumazet cwnd_quota, 2225605ad7f1SEric Dumazet max_segs), 2226605ad7f1SEric Dumazet nonagle); 2227605ad7f1SEric Dumazet 2228605ad7f1SEric Dumazet if (skb->len > limit && 2229605ad7f1SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2230605ad7f1SEric Dumazet break; 2231605ad7f1SEric Dumazet 2232f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 223346d3ceabSEric Dumazet break; 2234c9eeec26SEric Dumazet 2235d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 22361da177e4SLinus Torvalds break; 22371da177e4SLinus Torvalds 2238ec342325SAndrew Vagin repair: 22391da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 22401da177e4SLinus Torvalds * This call will increment packets_out. 22411da177e4SLinus Torvalds */ 224266f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 22431da177e4SLinus Torvalds 22441da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2245a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2246d5dd9175SIlpo Järvinen 2247d5dd9175SIlpo Järvinen if (push_one) 2248d5dd9175SIlpo Järvinen break; 22491da177e4SLinus Torvalds } 22501da177e4SLinus Torvalds 22515615f886SFrancis Yan if (is_rwnd_limited) 22525615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 22535615f886SFrancis Yan else 22545615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 22555615f886SFrancis Yan 2256aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2257684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2258684bad11SYuchung Cheng tp->prr_out += sent_pkts; 22596ba8a3b1SNandita Dukkipati 22606ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 22616ba8a3b1SNandita Dukkipati if (push_one != 2) 22626ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 2263d2e1339fSBendik Rønning Opstad is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); 2264ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2265a2a385d6SEric Dumazet return false; 22661da177e4SLinus Torvalds } 2267b340b264SYuchung Cheng return !tp->packets_out && tcp_send_head(sk); 22686ba8a3b1SNandita Dukkipati } 22696ba8a3b1SNandita Dukkipati 22706ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 22716ba8a3b1SNandita Dukkipati { 22726ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 22736ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 22746ba8a3b1SNandita Dukkipati u32 timeout, tlp_time_stamp, rto_time_stamp; 2275740b0f18SEric Dumazet u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); 22766ba8a3b1SNandita Dukkipati 22776ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) 22786ba8a3b1SNandita Dukkipati return false; 22796ba8a3b1SNandita Dukkipati /* No consecutive loss probes. */ 22806ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { 22816ba8a3b1SNandita Dukkipati tcp_rearm_rto(sk); 22826ba8a3b1SNandita Dukkipati return false; 22836ba8a3b1SNandita Dukkipati } 22846ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 22856ba8a3b1SNandita Dukkipati * finishes. 22866ba8a3b1SNandita Dukkipati */ 2287f9b99582SYuchung Cheng if (tp->fastopen_rsk) 22886ba8a3b1SNandita Dukkipati return false; 22896ba8a3b1SNandita Dukkipati 22906ba8a3b1SNandita Dukkipati /* TLP is only scheduled when next timer event is RTO. */ 22916ba8a3b1SNandita Dukkipati if (icsk->icsk_pending != ICSK_TIME_RETRANS) 22926ba8a3b1SNandita Dukkipati return false; 22936ba8a3b1SNandita Dukkipati 22946ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 22956ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 22966ba8a3b1SNandita Dukkipati */ 2297f9b99582SYuchung Cheng if (sysctl_tcp_early_retrans < 3 || !tp->packets_out || 22986ba8a3b1SNandita Dukkipati !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) 22996ba8a3b1SNandita Dukkipati return false; 23006ba8a3b1SNandita Dukkipati 23016ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 23026ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 23036ba8a3b1SNandita Dukkipati return false; 23046ba8a3b1SNandita Dukkipati 23056ba8a3b1SNandita Dukkipati /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account 2306f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2307f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 23086ba8a3b1SNandita Dukkipati */ 2309f9b99582SYuchung Cheng timeout = rtt << 1 ? : TCP_TIMEOUT_INIT; 23106ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 23116ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, 23126ba8a3b1SNandita Dukkipati (rtt + (rtt >> 1) + TCP_DELACK_MAX)); 23136ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, msecs_to_jiffies(10)); 23146ba8a3b1SNandita Dukkipati 23156ba8a3b1SNandita Dukkipati /* If RTO is shorter, just schedule TLP in its place. */ 23166ba8a3b1SNandita Dukkipati tlp_time_stamp = tcp_time_stamp + timeout; 23176ba8a3b1SNandita Dukkipati rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; 23186ba8a3b1SNandita Dukkipati if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { 23196ba8a3b1SNandita Dukkipati s32 delta = rto_time_stamp - tcp_time_stamp; 23206ba8a3b1SNandita Dukkipati if (delta > 0) 23216ba8a3b1SNandita Dukkipati timeout = delta; 23226ba8a3b1SNandita Dukkipati } 23236ba8a3b1SNandita Dukkipati 23246ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 23256ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 23266ba8a3b1SNandita Dukkipati return true; 23276ba8a3b1SNandita Dukkipati } 23286ba8a3b1SNandita Dukkipati 23291f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 23301f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 23311f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 23321f3279aeSEric Dumazet */ 23331f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 23341f3279aeSEric Dumazet const struct sk_buff *skb) 23351f3279aeSEric Dumazet { 233639bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2337c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 23381f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 23391f3279aeSEric Dumazet return true; 23401f3279aeSEric Dumazet } 23411f3279aeSEric Dumazet return false; 23421f3279aeSEric Dumazet } 23431f3279aeSEric Dumazet 2344b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 23456ba8a3b1SNandita Dukkipati * retransmit the last segment. 23466ba8a3b1SNandita Dukkipati */ 23476ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 23486ba8a3b1SNandita Dukkipati { 23499b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 23506ba8a3b1SNandita Dukkipati struct sk_buff *skb; 23516ba8a3b1SNandita Dukkipati int pcount; 23526ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 23536ba8a3b1SNandita Dukkipati 2354b340b264SYuchung Cheng skb = tcp_send_head(sk); 2355b340b264SYuchung Cheng if (skb) { 2356b340b264SYuchung Cheng if (tcp_snd_wnd_test(tp, skb, mss)) { 2357b340b264SYuchung Cheng pcount = tp->packets_out; 2358b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2359b340b264SYuchung Cheng if (tp->packets_out > pcount) 2360b340b264SYuchung Cheng goto probe_sent; 23616ba8a3b1SNandita Dukkipati goto rearm_timer; 23626ba8a3b1SNandita Dukkipati } 2363b340b264SYuchung Cheng skb = tcp_write_queue_prev(sk, skb); 2364b340b264SYuchung Cheng } else { 2365b340b264SYuchung Cheng skb = tcp_write_queue_tail(sk); 2366b340b264SYuchung Cheng } 23676ba8a3b1SNandita Dukkipati 23689b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 23699b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 23709b717a8dSNandita Dukkipati goto rearm_timer; 23719b717a8dSNandita Dukkipati 23726ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 23736ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 23746ba8a3b1SNandita Dukkipati goto rearm_timer; 23756ba8a3b1SNandita Dukkipati 23761f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 23771f3279aeSEric Dumazet goto rearm_timer; 23781f3279aeSEric Dumazet 23796ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 23806ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 23816ba8a3b1SNandita Dukkipati goto rearm_timer; 23826ba8a3b1SNandita Dukkipati 23836ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 23846cc55e09SOctavian Purdila if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, 23856cc55e09SOctavian Purdila GFP_ATOMIC))) 23866ba8a3b1SNandita Dukkipati goto rearm_timer; 2387b340b264SYuchung Cheng skb = tcp_write_queue_next(sk, skb); 23886ba8a3b1SNandita Dukkipati } 23896ba8a3b1SNandita Dukkipati 23906ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 23916ba8a3b1SNandita Dukkipati goto rearm_timer; 23926ba8a3b1SNandita Dukkipati 239310d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2394b340b264SYuchung Cheng goto rearm_timer; 23956ba8a3b1SNandita Dukkipati 23969b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 23979b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 23989b717a8dSNandita Dukkipati 2399b340b264SYuchung Cheng probe_sent: 2400c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2401fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2402fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2403b340b264SYuchung Cheng rearm_timer: 2404fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 24051da177e4SLinus Torvalds } 24061da177e4SLinus Torvalds 2407a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2408a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2409a762a980SDavid S. Miller * The socket must be locked by the caller. 2410a762a980SDavid S. Miller */ 24119e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 24129e412ba7SIlpo Järvinen int nonagle) 2413a762a980SDavid S. Miller { 2414726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2415726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2416726e07a8SIlpo Järvinen * all will be happy. 2417726e07a8SIlpo Järvinen */ 2418726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2419726e07a8SIlpo Järvinen return; 2420726e07a8SIlpo Järvinen 242199a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 24227450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 24239e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2424a762a980SDavid S. Miller } 2425a762a980SDavid S. Miller 2426c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2427c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2428c1b4a7e6SDavid S. Miller */ 2429c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2430c1b4a7e6SDavid S. Miller { 2431fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2432c1b4a7e6SDavid S. Miller 2433c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2434c1b4a7e6SDavid S. Miller 2435d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2436c1b4a7e6SDavid S. Miller } 2437c1b4a7e6SDavid S. Miller 24381da177e4SLinus Torvalds /* This function returns the amount that we can raise the 24391da177e4SLinus Torvalds * usable window based on the following constraints 24401da177e4SLinus Torvalds * 24411da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 24421da177e4SLinus Torvalds * 2. We limit memory per socket 24431da177e4SLinus Torvalds * 24441da177e4SLinus Torvalds * RFC 1122: 24451da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 24461da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 24471da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 24481da177e4SLinus Torvalds * 24491da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 24501da177e4SLinus Torvalds * it at least MSS bytes. 24511da177e4SLinus Torvalds * 24521da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 24531da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 24541da177e4SLinus Torvalds * 24551da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 24561da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 24571da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 24581da177e4SLinus Torvalds * window to always advance by a single byte. 24591da177e4SLinus Torvalds * 24601da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 24611da177e4SLinus Torvalds * then this will not be a problem. 24621da177e4SLinus Torvalds * 24631da177e4SLinus Torvalds * BSD seems to make the following compromise: 24641da177e4SLinus Torvalds * 24651da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 24661da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 24671da177e4SLinus Torvalds * then set the window to 0. 24681da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 24691da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 24701da177e4SLinus Torvalds * and from being larger than the largest representable value. 24711da177e4SLinus Torvalds * 24721da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 24731da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 24741da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 24751da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 24761da177e4SLinus Torvalds * because the pipeline is full. 24771da177e4SLinus Torvalds * 24781da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 24791da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 24801da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 24811da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 24821da177e4SLinus Torvalds * of having a fixed window size at almost all times. 24831da177e4SLinus Torvalds * 24841da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 24851da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 24861da177e4SLinus Torvalds * 24871da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 24881da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 24891da177e4SLinus Torvalds */ 24901da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 24911da177e4SLinus Torvalds { 2492463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 24931da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2494caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 24951da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 24961da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 24971da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 24981da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 24991da177e4SLinus Torvalds */ 2500463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 25011da177e4SLinus Torvalds int free_space = tcp_space(sk); 250286c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 250386c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 25041da177e4SLinus Torvalds int window; 25051da177e4SLinus Torvalds 25061da177e4SLinus Torvalds if (mss > full_space) 25071da177e4SLinus Torvalds mss = full_space; 25081da177e4SLinus Torvalds 2509b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2510463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 25111da177e4SLinus Torvalds 2512b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 2513056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2514056834d9SIlpo Järvinen 4U * tp->advmss); 25151da177e4SLinus Torvalds 251686c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 251786c1a045SFlorian Westphal * increase it due to wscale. 251886c1a045SFlorian Westphal */ 251986c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 252086c1a045SFlorian Westphal 252186c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 252286c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 252386c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 252486c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 252586c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 252686c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 252786c1a045SFlorian Westphal */ 252886c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 25291da177e4SLinus Torvalds return 0; 25301da177e4SLinus Torvalds } 25311da177e4SLinus Torvalds 25321da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 25331da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 25341da177e4SLinus Torvalds 25351da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 25361da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 25371da177e4SLinus Torvalds */ 25381da177e4SLinus Torvalds window = tp->rcv_wnd; 25391da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 25401da177e4SLinus Torvalds window = free_space; 25411da177e4SLinus Torvalds 25421da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 25431da177e4SLinus Torvalds * Import case: prevent zero window announcement if 25441da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 25451da177e4SLinus Torvalds */ 25461da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 25471da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 25481da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 25491da177e4SLinus Torvalds } else { 25501da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 25511da177e4SLinus Torvalds * Window clamp already applied above. 25521da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 25531da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 25541da177e4SLinus Torvalds * and multiply from happening most of the time. 25551da177e4SLinus Torvalds * We also don't do any window rounding when the free space 25561da177e4SLinus Torvalds * is too small. 25571da177e4SLinus Torvalds */ 25581da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 25591da177e4SLinus Torvalds window = (free_space / mss) * mss; 256084565070SJohn Heffner else if (mss == full_space && 2561b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 256284565070SJohn Heffner window = free_space; 25631da177e4SLinus Torvalds } 25641da177e4SLinus Torvalds 25651da177e4SLinus Torvalds return window; 25661da177e4SLinus Torvalds } 25671da177e4SLinus Torvalds 2568cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 2569082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 2570082ac2d5SMartin KaFai Lau { 25710a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 25720a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 25730a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 2574082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 2575082ac2d5SMartin KaFai Lau 25760a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 2577082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 25782de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 25792de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 2580082ac2d5SMartin KaFai Lau } 2581082ac2d5SMartin KaFai Lau } 2582082ac2d5SMartin KaFai Lau 25834a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 2584f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 25851da177e4SLinus Torvalds { 25861da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2587fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2588058dc334SIlpo Järvinen int skb_size, next_skb_size; 25891da177e4SLinus Torvalds 2590058dc334SIlpo Järvinen skb_size = skb->len; 2591058dc334SIlpo Järvinen next_skb_size = next_skb->len; 25921da177e4SLinus Torvalds 2593058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 25941da177e4SLinus Torvalds 2595f8071cdeSEric Dumazet if (next_skb_size) { 2596f8071cdeSEric Dumazet if (next_skb_size <= skb_availroom(skb)) 2597f8071cdeSEric Dumazet skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), 2598f8071cdeSEric Dumazet next_skb_size); 2599f8071cdeSEric Dumazet else if (!skb_shift(skb, next_skb, next_skb_size)) 2600f8071cdeSEric Dumazet return false; 2601f8071cdeSEric Dumazet } 26026859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 2603a6963a6bSIlpo Järvinen 2604fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 26051da177e4SLinus Torvalds 260652d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 260752d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 26081da177e4SLinus Torvalds 260984fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 26101da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 26111da177e4SLinus Torvalds 26121da177e4SLinus Torvalds /* Update sequence range on original skb. */ 26131da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 26141da177e4SLinus Torvalds 2615e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 26164de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 26171da177e4SLinus Torvalds 26181da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 26191da177e4SLinus Torvalds * packet counting does not break. 26201da177e4SLinus Torvalds */ 26214828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2622a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 2623b7689205SIlpo Järvinen 2624b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2625ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2626ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2627ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2628b7689205SIlpo Järvinen 2629797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2630797108d1SIlpo Järvinen 2631082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 2632082ac2d5SMartin KaFai Lau 26333ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 2634f8071cdeSEric Dumazet return true; 26351da177e4SLinus Torvalds } 26361da177e4SLinus Torvalds 263767edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2638a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 26394a17fc3aSIlpo Järvinen { 26404a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2641a2a385d6SEric Dumazet return false; 26424a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2643a2a385d6SEric Dumazet return false; 26444a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2645a2a385d6SEric Dumazet return false; 26462331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 26474a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2648a2a385d6SEric Dumazet return false; 26494a17fc3aSIlpo Järvinen 2650a2a385d6SEric Dumazet return true; 26514a17fc3aSIlpo Järvinen } 26524a17fc3aSIlpo Järvinen 265367edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 265467edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 265567edfef7SAndi Kleen */ 26564a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 26574a17fc3aSIlpo Järvinen int space) 26584a17fc3aSIlpo Järvinen { 26594a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 26604a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2661a2a385d6SEric Dumazet bool first = true; 26624a17fc3aSIlpo Järvinen 26634a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 26644a17fc3aSIlpo Järvinen return; 26654de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 26664a17fc3aSIlpo Järvinen return; 26674a17fc3aSIlpo Järvinen 26684a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 26694a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 26704a17fc3aSIlpo Järvinen break; 26714a17fc3aSIlpo Järvinen 2672a643b5d4SMartin KaFai Lau if (!tcp_skb_can_collapse_to(to)) 2673a643b5d4SMartin KaFai Lau break; 2674a643b5d4SMartin KaFai Lau 26754a17fc3aSIlpo Järvinen space -= skb->len; 26764a17fc3aSIlpo Järvinen 26774a17fc3aSIlpo Järvinen if (first) { 2678a2a385d6SEric Dumazet first = false; 26794a17fc3aSIlpo Järvinen continue; 26804a17fc3aSIlpo Järvinen } 26814a17fc3aSIlpo Järvinen 26824a17fc3aSIlpo Järvinen if (space < 0) 26834a17fc3aSIlpo Järvinen break; 26844a17fc3aSIlpo Järvinen 26854a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 26864a17fc3aSIlpo Järvinen break; 26874a17fc3aSIlpo Järvinen 2688f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 2689f8071cdeSEric Dumazet break; 26904a17fc3aSIlpo Järvinen } 26914a17fc3aSIlpo Järvinen } 26924a17fc3aSIlpo Järvinen 26931da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 26941da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 26951da177e4SLinus Torvalds * error occurred which prevented the send. 26961da177e4SLinus Torvalds */ 269710d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 26981da177e4SLinus Torvalds { 26995d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 270010d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 27017d227cd2SSridhar Samudrala unsigned int cur_mss; 270210d3be56SEric Dumazet int diff, len, err; 27031da177e4SLinus Torvalds 270410d3be56SEric Dumazet 270510d3be56SEric Dumazet /* Inconclusive MTU probe */ 270610d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 27075d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 27085d424d5aSJohn Heffner 27091da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2710caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 27111da177e4SLinus Torvalds */ 27121da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 2713ffb4d6c8SEric Dumazet min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), 2714ffb4d6c8SEric Dumazet sk->sk_sndbuf)) 27151da177e4SLinus Torvalds return -EAGAIN; 27161da177e4SLinus Torvalds 27171f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 27181f3279aeSEric Dumazet return -EBUSY; 27191f3279aeSEric Dumazet 27201da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 27211da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 27221da177e4SLinus Torvalds BUG(); 27231da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 27241da177e4SLinus Torvalds return -ENOMEM; 27251da177e4SLinus Torvalds } 27261da177e4SLinus Torvalds 27277d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 27287d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 27297d227cd2SSridhar Samudrala 27300c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 27317d227cd2SSridhar Samudrala 27321da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 27331da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 27341da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 27351da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 27361da177e4SLinus Torvalds */ 27379d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 27389d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 27391da177e4SLinus Torvalds return -EAGAIN; 27401da177e4SLinus Torvalds 274110d3be56SEric Dumazet len = cur_mss * segs; 274210d3be56SEric Dumazet if (skb->len > len) { 274310d3be56SEric Dumazet if (tcp_fragment(sk, skb, len, cur_mss, GFP_ATOMIC)) 27441da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 274502276f3cSIlpo Järvinen } else { 2746c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2747c52e2421SEric Dumazet return -ENOMEM; 274810d3be56SEric Dumazet 274910d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 275010d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 275110d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 275210d3be56SEric Dumazet if (diff) 275310d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 275410d3be56SEric Dumazet if (skb->len < cur_mss) 275510d3be56SEric Dumazet tcp_retrans_try_collapse(sk, skb, cur_mss); 27561da177e4SLinus Torvalds } 27571da177e4SLinus Torvalds 275849213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 275949213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 276049213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 276149213555SDaniel Borkmann 276250bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 276350bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 276450bceae9SThomas Graf * beyond what csum_start can cover. 276550bceae9SThomas Graf */ 276650bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 276750bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 276810a81980SEric Dumazet struct sk_buff *nskb; 276910a81980SEric Dumazet 277010a81980SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 277110a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 2772c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2773117632e6SEric Dumazet -ENOBUFS; 2774117632e6SEric Dumazet } else { 2775c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2776117632e6SEric Dumazet } 2777c84a5711SYuchung Cheng 2778fc9f3501SEric Dumazet if (likely(!err)) { 277910d3be56SEric Dumazet segs = tcp_skb_pcount(skb); 278010d3be56SEric Dumazet 2781c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2782fc9f3501SEric Dumazet /* Update global TCP statistics. */ 278310d3be56SEric Dumazet TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 2784fc9f3501SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 278502a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 278610d3be56SEric Dumazet tp->total_retrans += segs; 2787fc9f3501SEric Dumazet } 2788c84a5711SYuchung Cheng return err; 278993b174adSYuchung Cheng } 279093b174adSYuchung Cheng 279110d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 279293b174adSYuchung Cheng { 279393b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 279410d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 27951da177e4SLinus Torvalds 27961da177e4SLinus Torvalds if (err == 0) { 27971da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 27981da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2799e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 28001da177e4SLinus Torvalds } 28011da177e4SLinus Torvalds #endif 28021da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 28031da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 28041da177e4SLinus Torvalds 28051da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 28061da177e4SLinus Torvalds if (!tp->retrans_stamp) 28077faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 28081da177e4SLinus Torvalds 28091f3279aeSEric Dumazet } else if (err != -EBUSY) { 2810c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 28111da177e4SLinus Torvalds } 28126e08d5e3SYuchung Cheng 28136e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 28146e08d5e3SYuchung Cheng tp->undo_retrans = 0; 28156e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 28161da177e4SLinus Torvalds return err; 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds 281967edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 282067edfef7SAndi Kleen * window/congestion state. 282167edfef7SAndi Kleen */ 2822a2a385d6SEric Dumazet static bool tcp_can_forward_retransmit(struct sock *sk) 2823b5afe7bcSIlpo Järvinen { 2824b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2825cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2826b5afe7bcSIlpo Järvinen 2827b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2828b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2829a2a385d6SEric Dumazet return false; 2830b5afe7bcSIlpo Järvinen 2831b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2832b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2833a2a385d6SEric Dumazet return false; 2834b5afe7bcSIlpo Järvinen 2835b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2836b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2837b5afe7bcSIlpo Järvinen * 2838b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2839b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2840b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2841b5afe7bcSIlpo Järvinen */ 2842b5afe7bcSIlpo Järvinen 2843b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2844a2a385d6SEric Dumazet return false; 2845b5afe7bcSIlpo Järvinen 2846a2a385d6SEric Dumazet return true; 2847b5afe7bcSIlpo Järvinen } 2848b5afe7bcSIlpo Järvinen 28491da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 28501da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 28511da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 28521da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 28531da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 28541da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 28551da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 28561da177e4SLinus Torvalds */ 28571da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 28581da177e4SLinus Torvalds { 28596687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 28601da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 28611da177e4SLinus Torvalds struct sk_buff *skb; 28620e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2863a3d2e9f8SEric Dumazet u32 max_segs, last_lost; 286461eb55f4SIlpo Järvinen int mib_idx; 28650e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 28666a438bbeSStephen Hemminger 286745e77d31SIlpo Järvinen if (!tp->packets_out) 286845e77d31SIlpo Järvinen return; 286945e77d31SIlpo Järvinen 287008ebd172SIlpo Järvinen if (!tp->lost_out) 287108ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 287208ebd172SIlpo Järvinen 2873618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 28746a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2875618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2876618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2877618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2878618d9f25SIlpo Järvinen } else { 2879fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2880618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2881618d9f25SIlpo Järvinen } 28821da177e4SLinus Torvalds 2883ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 2884fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 2885dca0aaf8SEric Dumazet __u8 sacked; 288610d3be56SEric Dumazet int segs; 28871da177e4SLinus Torvalds 2888fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2889fe067e8aSDavid S. Miller break; 28906a438bbeSStephen Hemminger /* we could do better than to assign each time */ 289151456b29SIan Morris if (!hole) 28926a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 28936a438bbeSStephen Hemminger 289410d3be56SEric Dumazet segs = tp->snd_cwnd - tcp_packets_in_flight(tp); 289510d3be56SEric Dumazet if (segs <= 0) 28961da177e4SLinus Torvalds return; 2897dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 2898a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 2899a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 2900a3d2e9f8SEric Dumazet */ 2901a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 29020e1c54c2SIlpo Järvinen 29030e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 29040e1c54c2SIlpo Järvinen begin_fwd: 29050e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2906006f582cSIlpo Järvinen break; 29070e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 29080e1c54c2SIlpo Järvinen 29090e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2910618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 29110e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 29120e1c54c2SIlpo Järvinen break; 29130e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 291400db4124SIan Morris if (hole) { 29150e1c54c2SIlpo Järvinen skb = hole; 29160e1c54c2SIlpo Järvinen hole = NULL; 29170e1c54c2SIlpo Järvinen } 29180e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 29190e1c54c2SIlpo Järvinen goto begin_fwd; 29200e1c54c2SIlpo Järvinen 29210e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 292251456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 29230e1c54c2SIlpo Järvinen hole = skb; 292461eb55f4SIlpo Järvinen continue; 29251da177e4SLinus Torvalds 29260e1c54c2SIlpo Järvinen } else { 2927618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 29280e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 29290e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 29300e1c54c2SIlpo Järvinen else 29310e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 29320e1c54c2SIlpo Järvinen } 29330e1c54c2SIlpo Järvinen 29340e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 293561eb55f4SIlpo Järvinen continue; 293640b215e5SPavel Emelyanov 2937f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 2938f9616c35SEric Dumazet return; 2939f9616c35SEric Dumazet 294010d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 29411da177e4SLinus Torvalds return; 294224ab6becSYuchung Cheng 2943de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 29441da177e4SLinus Torvalds 2945684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2946a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2947a262f0cdSNandita Dukkipati 2948fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2949463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 29503f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 29513f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 29521da177e4SLinus Torvalds } 29531da177e4SLinus Torvalds } 29541da177e4SLinus Torvalds 2955d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 2956d83769a5SEric Dumazet * connection tear down and (memory) recovery. 2957845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 2958845704a5SEric Dumazet * or even be forced to close flow without any FIN. 2959a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 2960a6c5ea4cSEric Dumazet * with edge trigger epoll() 2961d83769a5SEric Dumazet */ 2962a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 2963d83769a5SEric Dumazet { 2964e805605cSJohannes Weiner int amt; 2965d83769a5SEric Dumazet 2966d83769a5SEric Dumazet if (size <= sk->sk_forward_alloc) 2967d83769a5SEric Dumazet return; 2968d83769a5SEric Dumazet amt = sk_mem_pages(size); 2969d83769a5SEric Dumazet sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; 2970e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 2971e805605cSJohannes Weiner 2972baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 2973baac50bbSJohannes Weiner mem_cgroup_charge_skmem(sk->sk_memcg, amt); 2974d83769a5SEric Dumazet } 2975d83769a5SEric Dumazet 2976845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 2977845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 29781da177e4SLinus Torvalds */ 29791da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 29801da177e4SLinus Torvalds { 2981845704a5SEric Dumazet struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); 29821da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 29831da177e4SLinus Torvalds 2984845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 2985845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 2986845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 2987845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 29881da177e4SLinus Torvalds */ 2989b8da51ebSEric Dumazet if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) { 2990845704a5SEric Dumazet coalesce: 2991845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 2992845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 29931da177e4SLinus Torvalds tp->write_seq++; 2994845704a5SEric Dumazet if (!tcp_send_head(sk)) { 2995845704a5SEric Dumazet /* This means tskb was already sent. 2996845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 2997845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 2998845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 2999845704a5SEric Dumazet * does not change tp->snd_nxt. 3000845704a5SEric Dumazet */ 3001845704a5SEric Dumazet tp->snd_nxt++; 3002845704a5SEric Dumazet return; 3003845704a5SEric Dumazet } 30041da177e4SLinus Torvalds } else { 3005845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3006845704a5SEric Dumazet if (unlikely(!skb)) { 3007845704a5SEric Dumazet if (tskb) 3008845704a5SEric Dumazet goto coalesce; 3009845704a5SEric Dumazet return; 30101da177e4SLinus Torvalds } 3011d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3012a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 30131da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3014e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3015a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 30161da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 30171da177e4SLinus Torvalds } 3018845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 30191da177e4SLinus Torvalds } 30201da177e4SLinus Torvalds 30211da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 30221da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 30231da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 302465bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 30251da177e4SLinus Torvalds */ 3026dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 30271da177e4SLinus Torvalds { 30281da177e4SLinus Torvalds struct sk_buff *skb; 30291da177e4SLinus Torvalds 30301da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 30311da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 30321da177e4SLinus Torvalds if (!skb) { 30334e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 30341da177e4SLinus Torvalds return; 30351da177e4SLinus Torvalds } 30361da177e4SLinus Torvalds 30371da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 30381da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3039e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3040a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 3041675ee231SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 30421da177e4SLinus Torvalds /* Send it off. */ 3043dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 30444e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 304526af65cbSSridhar Samudrala 304681cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 30471da177e4SLinus Torvalds } 30481da177e4SLinus Torvalds 304967edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 305067edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 30511da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 30521da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 30531da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 30541da177e4SLinus Torvalds */ 30551da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 30561da177e4SLinus Torvalds { 30571da177e4SLinus Torvalds struct sk_buff *skb; 30581da177e4SLinus Torvalds 3059fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 306051456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 306191df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 30621da177e4SLinus Torvalds return -EFAULT; 30631da177e4SLinus Torvalds } 30644de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 30651da177e4SLinus Torvalds if (skb_cloned(skb)) { 30661da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 306751456b29SIan Morris if (!nskb) 30681da177e4SLinus Torvalds return -ENOMEM; 3069fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 3070f4a775d1SEric Dumazet __skb_header_release(nskb); 3071fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 30723ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 30733ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 30743ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 30751da177e4SLinus Torvalds skb = nskb; 30761da177e4SLinus Torvalds } 30771da177e4SLinus Torvalds 30784de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3079735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 30801da177e4SLinus Torvalds } 3081dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 30821da177e4SLinus Torvalds } 30831da177e4SLinus Torvalds 30844aea39c1SEric Dumazet /** 30854aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 30864aea39c1SEric Dumazet * sk: listener socket 30874aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 30884aea39c1SEric Dumazet * req: request_sock pointer 30894aea39c1SEric Dumazet * 30904aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 30914aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 30924aea39c1SEric Dumazet */ 30935d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3094e6b4d113SWilliam Allen Simpson struct request_sock *req, 3095ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3096b3d05147SEric Dumazet enum tcp_synack_type synack_type) 30971da177e4SLinus Torvalds { 30982e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 30995d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 310080f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 31015d062de7SEric Dumazet struct tcp_out_options opts; 31025d062de7SEric Dumazet struct sk_buff *skb; 3103bd0388aeSWilliam Allen Simpson int tcp_header_size; 31045d062de7SEric Dumazet struct tcphdr *th; 31055d062de7SEric Dumazet u16 user_mss; 3106f5fff5dcSTom Quetchenbach int mss; 31071da177e4SLinus Torvalds 3108ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 31094aea39c1SEric Dumazet if (unlikely(!skb)) { 31104aea39c1SEric Dumazet dst_release(dst); 31111da177e4SLinus Torvalds return NULL; 31124aea39c1SEric Dumazet } 31131da177e4SLinus Torvalds /* Reserve space for headers. */ 31141da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 31151da177e4SLinus Torvalds 3116b3d05147SEric Dumazet switch (synack_type) { 3117b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 31189e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3119b3d05147SEric Dumazet break; 3120b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3121b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3122b3d05147SEric Dumazet * to avoid false sharing. 3123b3d05147SEric Dumazet */ 3124b3d05147SEric Dumazet break; 3125b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3126ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3127ca6fb065SEric Dumazet * cpu might call us concurrently. 3128ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3129ca6fb065SEric Dumazet */ 3130ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3131b3d05147SEric Dumazet break; 3132ca6fb065SEric Dumazet } 31334aea39c1SEric Dumazet skb_dst_set(skb, dst); 31341da177e4SLinus Torvalds 31350dbaee3bSDavid S. Miller mss = dst_metric_advmss(dst); 31365d062de7SEric Dumazet user_mss = READ_ONCE(tp->rx_opt.user_mss); 31375d062de7SEric Dumazet if (user_mss && user_mss < mss) 31385d062de7SEric Dumazet mss = user_mss; 3139f5fff5dcSTom Quetchenbach 314033ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 31418b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 31428b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 31437faee5c0SEric Dumazet skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); 31448b5f12d0SFlorian Westphal else 31458b5f12d0SFlorian Westphal #endif 31467faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 314780f03e27SEric Dumazet 314880f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 314980f03e27SEric Dumazet rcu_read_lock(); 3150fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 315180f03e27SEric Dumazet #endif 315258d607d3SEric Dumazet skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); 315337bfbddaSEric Dumazet tcp_header_size = tcp_synack_options(req, mss, skb, &opts, md5, foc) + 315437bfbddaSEric Dumazet sizeof(*th); 315533ad798cSAdam Langley 3156aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3157aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 31581da177e4SLinus Torvalds 3159ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 31601da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 31611da177e4SLinus Torvalds th->syn = 1; 31621da177e4SLinus Torvalds th->ack = 1; 31636ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3164b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3165634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3166e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 3167e870a8efSIlpo Järvinen * not even correctly set) 3168e870a8efSIlpo Järvinen */ 3169e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 3170a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 31714957faadSWilliam Allen Simpson 31721da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 31738336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 31748336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 31751da177e4SLinus Torvalds 31761da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3177ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 31785d062de7SEric Dumazet tcp_options_write((__be32 *)(th + 1), NULL, &opts); 31791da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 318090bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3181cfb6eeb4SYOSHIFUJI Hideaki 3182cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3183cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 318480f03e27SEric Dumazet if (md5) 3185bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 318639f8e58eSEric Dumazet md5, req_to_sk(req), skb); 318780f03e27SEric Dumazet rcu_read_unlock(); 3188cfb6eeb4SYOSHIFUJI Hideaki #endif 3189cfb6eeb4SYOSHIFUJI Hideaki 3190b50edd78SEric Dumazet /* Do not fool tcpdump (if any), clean our debris */ 3191b50edd78SEric Dumazet skb->tstamp.tv64 = 0; 31921da177e4SLinus Torvalds return skb; 31931da177e4SLinus Torvalds } 31944bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 31951da177e4SLinus Torvalds 319681164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 319781164413SDaniel Borkmann { 319881164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 319981164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 320081164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 320181164413SDaniel Borkmann 320281164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 320381164413SDaniel Borkmann return; 320481164413SDaniel Borkmann 320581164413SDaniel Borkmann rcu_read_lock(); 320681164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 320781164413SDaniel Borkmann if (likely(ca && try_module_get(ca->owner))) { 320881164413SDaniel Borkmann module_put(icsk->icsk_ca_ops->owner); 320981164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 321081164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 321181164413SDaniel Borkmann } 321281164413SDaniel Borkmann rcu_read_unlock(); 321381164413SDaniel Borkmann } 321481164413SDaniel Borkmann 321567edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3216f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 32171da177e4SLinus Torvalds { 3218cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 32191da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32201da177e4SLinus Torvalds __u8 rcv_wscale; 32211da177e4SLinus Torvalds 32221da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 32231da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 32241da177e4SLinus Torvalds */ 32251da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 3226bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 32271da177e4SLinus Torvalds 3228cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 322900db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3230cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3231cfb6eeb4SYOSHIFUJI Hideaki #endif 3232cfb6eeb4SYOSHIFUJI Hideaki 32331da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 32341da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 32351da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 32361da177e4SLinus Torvalds tp->max_window = 0; 32375d424d5aSJohn Heffner tcp_mtup_init(sk); 32381da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 32391da177e4SLinus Torvalds 324081164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 324181164413SDaniel Borkmann 32421da177e4SLinus Torvalds if (!tp->window_clamp) 32431da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 32440dbaee3bSDavid S. Miller tp->advmss = dst_metric_advmss(dst); 3245f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 3246f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 3247f5fff5dcSTom Quetchenbach 32481da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 32491da177e4SLinus Torvalds 3250e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3251e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3252e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3253e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3254e88c64f0SHagen Paul Pfeifer 32551da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 32561da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 32571da177e4SLinus Torvalds &tp->rcv_wnd, 32581da177e4SLinus Torvalds &tp->window_clamp, 3259bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 326031d12926Slaurent chavey &rcv_wscale, 326131d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 32621da177e4SLinus Torvalds 32631da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 32641da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 32651da177e4SLinus Torvalds 32661da177e4SLinus Torvalds sk->sk_err = 0; 32671da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 32681da177e4SLinus Torvalds tp->snd_wnd = 0; 3269ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 32701da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 32711da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 327233f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3273370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 3274ee995283SPavel Emelyanov 3275ee995283SPavel Emelyanov if (likely(!tp->repair)) 32761da177e4SLinus Torvalds tp->rcv_nxt = 0; 3277c7781a6eSAndrew Vagin else 3278c7781a6eSAndrew Vagin tp->rcv_tstamp = tcp_time_stamp; 3279ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 3280ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 32811da177e4SLinus Torvalds 3282463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 3283463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 32841da177e4SLinus Torvalds tcp_clear_retrans(tp); 32851da177e4SLinus Torvalds } 32861da177e4SLinus Torvalds 3287783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3288783237e8SYuchung Cheng { 3289783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3290783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3291783237e8SYuchung Cheng 3292783237e8SYuchung Cheng tcb->end_seq += skb->len; 3293f4a775d1SEric Dumazet __skb_header_release(skb); 3294783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 3295783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 3296783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 3297783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 3298783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3299783237e8SYuchung Cheng } 3300783237e8SYuchung Cheng 3301783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3302783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3303783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3304783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3305783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3306783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3307783237e8SYuchung Cheng */ 3308783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3309783237e8SYuchung Cheng { 3310783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3311783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 331207e100f9SEric Dumazet int syn_loss = 0, space, err = 0; 3313aab48743SYuchung Cheng unsigned long last_syn_loss = 0; 3314355a901eSEric Dumazet struct sk_buff *syn_data; 3315783237e8SYuchung Cheng 331667da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3317aab48743SYuchung Cheng tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, 3318aab48743SYuchung Cheng &syn_loss, &last_syn_loss); 3319aab48743SYuchung Cheng /* Recurring FO SYN losses: revert to regular handshake temporarily */ 3320aab48743SYuchung Cheng if (syn_loss > 1 && 3321aab48743SYuchung Cheng time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { 3322aab48743SYuchung Cheng fo->cookie.len = -1; 3323aab48743SYuchung Cheng goto fallback; 3324aab48743SYuchung Cheng } 3325aab48743SYuchung Cheng 332667da22d2SYuchung Cheng if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) 332767da22d2SYuchung Cheng fo->cookie.len = -1; 332867da22d2SYuchung Cheng else if (fo->cookie.len <= 0) 3329783237e8SYuchung Cheng goto fallback; 3330783237e8SYuchung Cheng 3331783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3332783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3333783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3334783237e8SYuchung Cheng */ 3335783237e8SYuchung Cheng if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) 3336783237e8SYuchung Cheng tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 33371b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3338783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3339783237e8SYuchung Cheng 3340f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3341f5ddcbbbSEric Dumazet 3342f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3343f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3344f5ddcbbbSEric Dumazet 3345eb934478SEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); 3346355a901eSEric Dumazet if (!syn_data) 3347783237e8SYuchung Cheng goto fallback; 3348355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3349355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 335007e100f9SEric Dumazet if (space) { 335107e100f9SEric Dumazet int copied = copy_from_iter(skb_put(syn_data, space), space, 335257be5bdaSAl Viro &fo->data->msg_iter); 335357be5bdaSAl Viro if (unlikely(!copied)) { 3354355a901eSEric Dumazet kfree_skb(syn_data); 3355783237e8SYuchung Cheng goto fallback; 3356783237e8SYuchung Cheng } 335757be5bdaSAl Viro if (copied != space) { 335857be5bdaSAl Viro skb_trim(syn_data, copied); 335957be5bdaSAl Viro space = copied; 336057be5bdaSAl Viro } 336107e100f9SEric Dumazet } 3362355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3363355a901eSEric Dumazet if (space == fo->size) 3364355a901eSEric Dumazet fo->data = NULL; 3365355a901eSEric Dumazet fo->copied = space; 3366783237e8SYuchung Cheng 3367355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 33680f87230dSFrancis Yan if (syn_data->len) 33690f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3370355a901eSEric Dumazet 3371355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3372355a901eSEric Dumazet 3373355a901eSEric Dumazet syn->skb_mstamp = syn_data->skb_mstamp; 3374355a901eSEric Dumazet 3375355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3376355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3377355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3378355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3379431a9124SEric Dumazet */ 3380355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3381355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3382355a901eSEric Dumazet if (!err) { 338367da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 3384f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3385783237e8SYuchung Cheng goto done; 3386783237e8SYuchung Cheng } 3387783237e8SYuchung Cheng 3388783237e8SYuchung Cheng fallback: 3389783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3390783237e8SYuchung Cheng if (fo->cookie.len > 0) 3391783237e8SYuchung Cheng fo->cookie.len = 0; 3392783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3393783237e8SYuchung Cheng if (err) 3394783237e8SYuchung Cheng tp->syn_fastopen = 0; 3395783237e8SYuchung Cheng done: 3396783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3397783237e8SYuchung Cheng return err; 3398783237e8SYuchung Cheng } 3399783237e8SYuchung Cheng 340067edfef7SAndi Kleen /* Build a SYN and send it off. */ 34011da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 34021da177e4SLinus Torvalds { 34031da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34041da177e4SLinus Torvalds struct sk_buff *buff; 3405ee586811SEric Paris int err; 34061da177e4SLinus Torvalds 34071da177e4SLinus Torvalds tcp_connect_init(sk); 34081da177e4SLinus Torvalds 34092b916477SAndrey Vagin if (unlikely(tp->repair)) { 34102b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 34112b916477SAndrey Vagin return 0; 34122b916477SAndrey Vagin } 34132b916477SAndrey Vagin 3414eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); 3415355a901eSEric Dumazet if (unlikely(!buff)) 34161da177e4SLinus Torvalds return -ENOBUFS; 34171da177e4SLinus Torvalds 3418a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 34197faee5c0SEric Dumazet tp->retrans_stamp = tcp_time_stamp; 3420783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3421735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 34221da177e4SLinus Torvalds 3423783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3424783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3425783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3426ee586811SEric Paris if (err == -ECONNREFUSED) 3427ee586811SEric Paris return err; 3428bd37a088SWei Yongjun 3429bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3430bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3431bd37a088SWei Yongjun */ 3432bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3433bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 343481cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 34351da177e4SLinus Torvalds 34361da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 34373f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 34383f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 34391da177e4SLinus Torvalds return 0; 34401da177e4SLinus Torvalds } 34414bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 34421da177e4SLinus Torvalds 34431da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 34441da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 34451da177e4SLinus Torvalds * for details. 34461da177e4SLinus Torvalds */ 34471da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 34481da177e4SLinus Torvalds { 3449463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3450463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 34511da177e4SLinus Torvalds unsigned long timeout; 34521da177e4SLinus Torvalds 34539890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_DELAYED_ACK); 34549890092eSFlorian Westphal 34551da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3456463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 34571da177e4SLinus Torvalds int max_ato = HZ / 2; 34581da177e4SLinus Torvalds 3459056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3460056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 34611da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 34621da177e4SLinus Torvalds 34631da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 34641da177e4SLinus Torvalds 34651da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3466463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 34671da177e4SLinus Torvalds * directly. 34681da177e4SLinus Torvalds */ 3469740b0f18SEric Dumazet if (tp->srtt_us) { 3470740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3471740b0f18SEric Dumazet TCP_DELACK_MIN); 34721da177e4SLinus Torvalds 34731da177e4SLinus Torvalds if (rtt < max_ato) 34741da177e4SLinus Torvalds max_ato = rtt; 34751da177e4SLinus Torvalds } 34761da177e4SLinus Torvalds 34771da177e4SLinus Torvalds ato = min(ato, max_ato); 34781da177e4SLinus Torvalds } 34791da177e4SLinus Torvalds 34801da177e4SLinus Torvalds /* Stay within the limit we were given */ 34811da177e4SLinus Torvalds timeout = jiffies + ato; 34821da177e4SLinus Torvalds 34831da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3484463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 34851da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 34861da177e4SLinus Torvalds * send ACK now. 34871da177e4SLinus Torvalds */ 3488463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3489463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 34901da177e4SLinus Torvalds tcp_send_ack(sk); 34911da177e4SLinus Torvalds return; 34921da177e4SLinus Torvalds } 34931da177e4SLinus Torvalds 3494463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3495463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 34961da177e4SLinus Torvalds } 3497463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3498463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3499463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 35001da177e4SLinus Torvalds } 35011da177e4SLinus Torvalds 35021da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 35031da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 35041da177e4SLinus Torvalds { 35051da177e4SLinus Torvalds struct sk_buff *buff; 35061da177e4SLinus Torvalds 3507058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3508058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3509058dc334SIlpo Järvinen return; 3510058dc334SIlpo Järvinen 35119890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK); 35129890092eSFlorian Westphal 35131da177e4SLinus Torvalds /* We are not putting this on the write queue, so 35141da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 35151da177e4SLinus Torvalds * sock. 35161da177e4SLinus Torvalds */ 35177450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 35187450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 35197450aaf6SEric Dumazet if (unlikely(!buff)) { 3520463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3521463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 35223f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 35233f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 35241da177e4SLinus Torvalds return; 35251da177e4SLinus Torvalds } 35261da177e4SLinus Torvalds 35271da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 35281da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3529a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 35301da177e4SLinus Torvalds 353198781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 353298781965SEric Dumazet * too much. 353398781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 353498781965SEric Dumazet * We also avoid tcp_wfree() overhead (cache line miss accessing 353598781965SEric Dumazet * tp->tsq_flags) by using regular sock_wfree() 353698781965SEric Dumazet */ 353798781965SEric Dumazet skb_set_tcp_pure_ack(buff); 353898781965SEric Dumazet 35391da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 35407faee5c0SEric Dumazet skb_mstamp_get(&buff->skb_mstamp); 35417450aaf6SEric Dumazet tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0); 35421da177e4SLinus Torvalds } 3543e3118e83SDaniel Borkmann EXPORT_SYMBOL_GPL(tcp_send_ack); 35441da177e4SLinus Torvalds 35451da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 35461da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 35471da177e4SLinus Torvalds * 35481da177e4SLinus Torvalds * Question: what should we make while urgent mode? 35491da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 35501da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 35511da177e4SLinus Torvalds * 35521da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 35531da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 35541da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 35551da177e4SLinus Torvalds */ 3556e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 35571da177e4SLinus Torvalds { 35581da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 35591da177e4SLinus Torvalds struct sk_buff *skb; 35601da177e4SLinus Torvalds 35611da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 35627450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 35637450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 356451456b29SIan Morris if (!skb) 35651da177e4SLinus Torvalds return -1; 35661da177e4SLinus Torvalds 35671da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 35681da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 35691da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 35701da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 35711da177e4SLinus Torvalds * send it. 35721da177e4SLinus Torvalds */ 3573a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 35747faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 3575e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 35767450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 35771da177e4SLinus Torvalds } 35781da177e4SLinus Torvalds 3579ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3580ee995283SPavel Emelyanov { 3581ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3582ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 3583e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 3584ee995283SPavel Emelyanov } 3585ee995283SPavel Emelyanov } 3586ee995283SPavel Emelyanov 358767edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 3588e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 35891da177e4SLinus Torvalds { 35901da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 35911da177e4SLinus Torvalds struct sk_buff *skb; 35921da177e4SLinus Torvalds 3593058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3594058dc334SIlpo Järvinen return -1; 3595058dc334SIlpo Järvinen 359600db4124SIan Morris skb = tcp_send_head(sk); 359700db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 35981da177e4SLinus Torvalds int err; 35990c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 360090840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 36011da177e4SLinus Torvalds 36021da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 36031da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 36041da177e4SLinus Torvalds 36051da177e4SLinus Torvalds /* We are probing the opening of a window 36061da177e4SLinus Torvalds * but the window size is != 0 36071da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 36081da177e4SLinus Torvalds */ 36091da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 36101da177e4SLinus Torvalds skb->len > mss) { 36111da177e4SLinus Torvalds seg_size = min(seg_size, mss); 36124de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 36136cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) 36141da177e4SLinus Torvalds return -1; 36151da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 36165bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 36171da177e4SLinus Torvalds 36184de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3619dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 362066f5fe62SIlpo Järvinen if (!err) 362166f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 36221da177e4SLinus Torvalds return err; 36231da177e4SLinus Torvalds } else { 362433f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 3625e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 3626e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 36271da177e4SLinus Torvalds } 36281da177e4SLinus Torvalds } 36291da177e4SLinus Torvalds 36301da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 36311da177e4SLinus Torvalds * a partial packet else a zero probe. 36321da177e4SLinus Torvalds */ 36331da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 36341da177e4SLinus Torvalds { 3635463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 36361da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3637c6214a97SNikolay Borisov struct net *net = sock_net(sk); 3638fcdd1cf4SEric Dumazet unsigned long probe_max; 36391da177e4SLinus Torvalds int err; 36401da177e4SLinus Torvalds 3641e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 36421da177e4SLinus Torvalds 3643fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 36441da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 36456687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3646463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 36471da177e4SLinus Torvalds return; 36481da177e4SLinus Torvalds } 36491da177e4SLinus Torvalds 36501da177e4SLinus Torvalds if (err <= 0) { 3651c6214a97SNikolay Borisov if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) 3652463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 36536687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3654fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 36551da177e4SLinus Torvalds } else { 36561da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 36576687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 36581da177e4SLinus Torvalds * Let local senders to fight for local resources. 36591da177e4SLinus Torvalds * 36601da177e4SLinus Torvalds * Use accumulated backoff yet. 36611da177e4SLinus Torvalds */ 36626687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 36636687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3664fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 36651da177e4SLinus Torvalds } 3666fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 366721c8fe99SEric Dumazet tcp_probe0_when(sk, probe_max), 3668fcdd1cf4SEric Dumazet TCP_RTO_MAX); 36691da177e4SLinus Torvalds } 36705db92c99SOctavian Purdila 3671ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 36725db92c99SOctavian Purdila { 36735db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 36745db92c99SOctavian Purdila struct flowi fl; 36755db92c99SOctavian Purdila int res; 36765db92c99SOctavian Purdila 367758d607d3SEric Dumazet tcp_rsk(req)->txhash = net_tx_rndhash(); 3678b3d05147SEric Dumazet res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); 36795db92c99SOctavian Purdila if (!res) { 368090bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 368102a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 36827e32b443SYuchung Cheng if (unlikely(tcp_passive_fastopen(sk))) 36837e32b443SYuchung Cheng tcp_sk(sk)->total_retrans++; 36845db92c99SOctavian Purdila } 36855db92c99SOctavian Purdila return res; 36865db92c99SOctavian Purdila } 36875db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3688