11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 31da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 41da177e4SLinus Torvalds * interface as the means of communication with the user level. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 71da177e4SLinus Torvalds * 802c30a84SJesper Juhl * Authors: Ross Biro 91da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 101da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 111da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 121da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 131da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 141da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 151da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 161da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 171da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 181da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds /* 221da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 231da177e4SLinus Torvalds * : Fragmentation on mtu decrease 241da177e4SLinus Torvalds * : Segment collapse on retransmit 251da177e4SLinus Torvalds * : AF independence 261da177e4SLinus Torvalds * 271da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 281da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 291da177e4SLinus Torvalds * during syn/ack processing. 301da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 311da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 321da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 331da177e4SLinus Torvalds * J Hadi Salim : ECN support 341da177e4SLinus Torvalds * 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds 3791df42beSJoe Perches #define pr_fmt(fmt) "TCP: " fmt 3891df42beSJoe Perches 391da177e4SLinus Torvalds #include <net/tcp.h> 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds #include <linux/compiler.h> 425a0e3ad6STejun Heo #include <linux/gfp.h> 431da177e4SLinus Torvalds #include <linux/module.h> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 46ab32ea5dSBrian Haley int sysctl_tcp_retrans_collapse __read_mostly = 1; 471da177e4SLinus Torvalds 4815d99e02SRick Jones /* People can turn this on to work with those rare, broken TCPs that 4915d99e02SRick Jones * interpret the window field as a signed quantity. 5015d99e02SRick Jones */ 51ab32ea5dSBrian Haley int sysctl_tcp_workaround_signed_windows __read_mostly = 0; 5215d99e02SRick Jones 5346d3ceabSEric Dumazet /* Default TSQ limit of two TSO segments */ 5446d3ceabSEric Dumazet int sysctl_tcp_limit_output_bytes __read_mostly = 131072; 5546d3ceabSEric Dumazet 561da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 571da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 581da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 591da177e4SLinus Torvalds */ 60ab32ea5dSBrian Haley int sysctl_tcp_tso_win_divisor __read_mostly = 3; 611da177e4SLinus Torvalds 6235089bb2SDavid S. Miller /* By default, RFC2861 behavior. */ 63ab32ea5dSBrian Haley int sysctl_tcp_slow_start_after_idle __read_mostly = 1; 6435089bb2SDavid S. Miller 65c9bee3b7SEric Dumazet unsigned int sysctl_tcp_notsent_lowat __read_mostly = UINT_MAX; 66c9bee3b7SEric Dumazet EXPORT_SYMBOL(sysctl_tcp_notsent_lowat); 67c9bee3b7SEric Dumazet 6846d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6946d3ceabSEric Dumazet int push_one, gfp_t gfp); 70519855c5SWilliam Allen Simpson 7167edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 72cf533ea5SEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) 736ff03ac3SIlpo Järvinen { 746ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 756ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7666f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 779e412ba7SIlpo Järvinen 78fe067e8aSDavid S. Miller tcp_advance_send_head(sk, skb); 791da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 808512430eSIlpo Järvinen 8166f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 826ba8a3b1SNandita Dukkipati if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || 836a5dc9e5SEric Dumazet icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { 84750ea2baSYuchung Cheng tcp_rearm_rto(sk); 851da177e4SLinus Torvalds } 86f19c29e3SYuchung Cheng 87f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 88f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 896a5dc9e5SEric Dumazet } 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 921da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 931da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 941da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 951da177e4SLinus Torvalds * invalid. OK, let's make this for now: 961da177e4SLinus Torvalds */ 97cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 981da177e4SLinus Torvalds { 99cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1009e412ba7SIlpo Järvinen 10190840defSIlpo Järvinen if (!before(tcp_wnd_end(tp), tp->snd_nxt)) 1021da177e4SLinus Torvalds return tp->snd_nxt; 1031da177e4SLinus Torvalds else 10490840defSIlpo Järvinen return tcp_wnd_end(tp); 1051da177e4SLinus Torvalds } 1061da177e4SLinus Torvalds 1071da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1081da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1091da177e4SLinus Torvalds * 1101da177e4SLinus Torvalds * 1. It is independent of path mtu. 1111da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1121da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1131da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1141da177e4SLinus Torvalds * large MSS. 1151da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1161da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1171da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1181da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1191da177e4SLinus Torvalds * probably even Jumbo". 1201da177e4SLinus Torvalds */ 1211da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1221da177e4SLinus Torvalds { 1231da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 124cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1251da177e4SLinus Torvalds int mss = tp->advmss; 1261da177e4SLinus Torvalds 1270dbaee3bSDavid S. Miller if (dst) { 1280dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1290dbaee3bSDavid S. Miller 1300dbaee3bSDavid S. Miller if (metric < mss) { 1310dbaee3bSDavid S. Miller mss = metric; 1321da177e4SLinus Torvalds tp->advmss = mss; 1331da177e4SLinus Torvalds } 1340dbaee3bSDavid S. Miller } 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds return (__u16)mss; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 1391da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1401da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 141cf533ea5SEric Dumazet static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst) 1421da177e4SLinus Torvalds { 143463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1441da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1451da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1461da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1471da177e4SLinus Torvalds 1486687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1491da177e4SLinus Torvalds 1506687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1511da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1521da177e4SLinus Torvalds 153463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1541da177e4SLinus Torvalds cwnd >>= 1; 1551da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1561da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1571da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 16067edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 16140efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 162cf533ea5SEric Dumazet struct sock *sk) 1631da177e4SLinus Torvalds { 164463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 165463c84b9SArnaldo Carvalho de Melo const u32 now = tcp_time_stamp; 166bcefe17cSCong Wang const struct dst_entry *dst = __sk_dst_get(sk); 1671da177e4SLinus Torvalds 16835089bb2SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 16935089bb2SDavid S. Miller (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) 170463c84b9SArnaldo Carvalho de Melo tcp_cwnd_restart(sk, __sk_dst_get(sk)); 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds tp->lsndtime = now; 1731da177e4SLinus Torvalds 1741da177e4SLinus Torvalds /* If it is a reply for ato after last received 1751da177e4SLinus Torvalds * packet, enter pingpong mode. 1761da177e4SLinus Torvalds */ 177bcefe17cSCong Wang if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato && 178bcefe17cSCong Wang (!dst || !dst_metric(dst, RTAX_QUICKACK))) 179463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1801da177e4SLinus Torvalds } 1811da177e4SLinus Torvalds 18267edfef7SAndi Kleen /* Account for an ACK we sent. */ 18340efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1841da177e4SLinus Torvalds { 185463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 186463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1871da177e4SLinus Torvalds } 1881da177e4SLinus Torvalds 18985f16525SYuchung Cheng 19085f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 19185f16525SYuchung Cheng { 19285f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 1939ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 19485f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 19585f16525SYuchung Cheng * limit when mss is larger than 1460. 19685f16525SYuchung Cheng */ 19785f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 19885f16525SYuchung Cheng 19985f16525SYuchung Cheng if (mss > 1460) 20085f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 20185f16525SYuchung Cheng return init_rwnd; 20285f16525SYuchung Cheng } 20385f16525SYuchung Cheng 2041da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2051da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2061da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2071da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2081da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2091da177e4SLinus Torvalds * This MUST be enforced by all callers. 2101da177e4SLinus Torvalds */ 2111da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 2121da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 21331d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 21431d12926Slaurent chavey __u32 init_rcv_wnd) 2151da177e4SLinus Torvalds { 2161da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2191da177e4SLinus Torvalds if (*window_clamp == 0) 2201da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 2211da177e4SLinus Torvalds space = min(*window_clamp, space); 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2241da177e4SLinus Torvalds if (space > mss) 2251da177e4SLinus Torvalds space = (space / mss) * mss; 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22815d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22915d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 23015d99e02SRick Jones * we will truncate our initial window offering to 32K-1 23115d99e02SRick Jones * unless the remote has sent us a window scaling option, 23215d99e02SRick Jones * which we interpret as a sign the remote TCP is not 23315d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2341da177e4SLinus Torvalds */ 23515d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2361da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23715d99e02SRick Jones else 23815d99e02SRick Jones (*rcv_wnd) = space; 23915d99e02SRick Jones 2401da177e4SLinus Torvalds (*rcv_wscale) = 0; 2411da177e4SLinus Torvalds if (wscale_ok) { 2421da177e4SLinus Torvalds /* Set window scaling on max possible window 2431da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 2441da177e4SLinus Torvalds */ 2451da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 246316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 2471da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 2481da177e4SLinus Torvalds space >>= 1; 2491da177e4SLinus Torvalds (*rcv_wscale)++; 2501da177e4SLinus Torvalds } 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 25485f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 25585f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 256b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2601da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2611da177e4SLinus Torvalds } 2624bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2651da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2661da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2671da177e4SLinus Torvalds * frame. 2681da177e4SLinus Torvalds */ 26940efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2701da177e4SLinus Torvalds { 2711da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2728e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2731da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2741da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds /* Never shrink the offered window */ 2771da177e4SLinus Torvalds if (new_win < cur_win) { 2781da177e4SLinus Torvalds /* Danger Will Robinson! 2791da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2801da177e4SLinus Torvalds * we will not be able to advertise a zero 2811da177e4SLinus Torvalds * window in time. --DaveM 2821da177e4SLinus Torvalds * 2831da177e4SLinus Torvalds * Relax Will Robinson. 2841da177e4SLinus Torvalds */ 2858e165e20SFlorian Westphal if (new_win == 0) 2868e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2878e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 288607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2891da177e4SLinus Torvalds } 2901da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2911da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2941da177e4SLinus Torvalds * scaled window. 2951da177e4SLinus Torvalds */ 29615d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2971da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2981da177e4SLinus Torvalds else 2991da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 3001da177e4SLinus Torvalds 3011da177e4SLinus Torvalds /* RFC1323 scaling applied */ 3021da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 3031da177e4SLinus Torvalds 3041da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 3058e165e20SFlorian Westphal if (new_win == 0) { 3061da177e4SLinus Torvalds tp->pred_flags = 0; 3078e165e20SFlorian Westphal if (old_win) 3088e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3098e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3108e165e20SFlorian Westphal } else if (old_win == 0) { 3118e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3128e165e20SFlorian Westphal } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds return new_win; 3151da177e4SLinus Torvalds } 3161da177e4SLinus Torvalds 31767edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 318735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 319bdf1ee5dSIlpo Järvinen { 32030e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 32130e502a3SDaniel Borkmann 3224de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 323bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3244de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 32530e502a3SDaniel Borkmann else if (tcp_ca_needs_ecn(sk)) 32630e502a3SDaniel Borkmann INET_ECN_xmit(sk); 327bdf1ee5dSIlpo Järvinen } 328bdf1ee5dSIlpo Järvinen 32967edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 330735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 331bdf1ee5dSIlpo Järvinen { 332bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 333f7b3bec6SFlorian Westphal bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || 334f7b3bec6SFlorian Westphal tcp_ca_needs_ecn(sk); 335f7b3bec6SFlorian Westphal 336f7b3bec6SFlorian Westphal if (!use_ecn) { 337f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 338f7b3bec6SFlorian Westphal 339f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 340f7b3bec6SFlorian Westphal use_ecn = true; 341f7b3bec6SFlorian Westphal } 342bdf1ee5dSIlpo Järvinen 343bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 344f7b3bec6SFlorian Westphal 345f7b3bec6SFlorian Westphal if (use_ecn) { 3464de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 347bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 34830e502a3SDaniel Borkmann if (tcp_ca_needs_ecn(sk)) 34930e502a3SDaniel Borkmann INET_ECN_xmit(sk); 350bdf1ee5dSIlpo Järvinen } 351bdf1ee5dSIlpo Järvinen } 352bdf1ee5dSIlpo Järvinen 353735d3831SFlorian Westphal static void 354735d3831SFlorian Westphal tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th, 35530e502a3SDaniel Borkmann struct sock *sk) 356bdf1ee5dSIlpo Järvinen { 35730e502a3SDaniel Borkmann if (inet_rsk(req)->ecn_ok) { 358bdf1ee5dSIlpo Järvinen th->ece = 1; 35930e502a3SDaniel Borkmann if (tcp_ca_needs_ecn(sk)) 36030e502a3SDaniel Borkmann INET_ECN_xmit(sk); 36130e502a3SDaniel Borkmann } 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, 368bdf1ee5dSIlpo Järvinen 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; 379bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->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) 387bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->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 { 3967b7fc97aSEric Dumazet struct skb_shared_info *shinfo = skb_shinfo(skb); 3977b7fc97aSEric Dumazet 3982e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 399e870a8efSIlpo Järvinen skb->csum = 0; 400e870a8efSIlpo Järvinen 4014de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 402e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 403e870a8efSIlpo Järvinen 404cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 4057b7fc97aSEric Dumazet shinfo->gso_size = 0; 4067b7fc97aSEric Dumazet shinfo->gso_type = 0; 407e870a8efSIlpo Järvinen 408e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 409a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 410e870a8efSIlpo Järvinen seq++; 411e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 412e870a8efSIlpo Järvinen } 413e870a8efSIlpo Järvinen 414a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 41533f5f57eSIlpo Järvinen { 41633f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41733f5f57eSIlpo Järvinen } 41833f5f57eSIlpo Järvinen 41933ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 42033ad798cSAdam Langley #define OPTION_TS (1 << 1) 42133ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 42289e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4232100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 42433ad798cSAdam Langley 42533ad798cSAdam Langley struct tcp_out_options { 4262100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4272100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 42833ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 42933ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 430bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 431bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4322100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4332100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 43433ad798cSAdam Langley }; 43533ad798cSAdam Langley 43667edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 43767edfef7SAndi Kleen * 43867edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 439fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 440fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4418e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 442fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 443fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 444fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 445fd6149d3SIlpo Järvinen * 446fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 447fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 448fd6149d3SIlpo Järvinen */ 44933ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 450bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 451bd0388aeSWilliam Allen Simpson { 4522100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 453bd0388aeSWilliam Allen Simpson 454bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4551a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4561a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 457bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 458bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 45933ad798cSAdam Langley ptr += 4; 46033ad798cSAdam Langley } 46133ad798cSAdam Langley 462fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 463fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 464fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 465fd6149d3SIlpo Järvinen opts->mss); 466fd6149d3SIlpo Järvinen } 467fd6149d3SIlpo Järvinen 468bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 469bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 47033ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 47133ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 47233ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 47333ad798cSAdam Langley TCPOLEN_TIMESTAMP); 474bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 47533ad798cSAdam Langley } else { 476496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 47740efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 47840efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 47940efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 48040efc6faSStephen Hemminger } 48133ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 48233ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 48333ad798cSAdam Langley } 48433ad798cSAdam Langley 485bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 48633ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 48733ad798cSAdam Langley (TCPOPT_NOP << 16) | 48833ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 48933ad798cSAdam Langley TCPOLEN_SACK_PERM); 49033ad798cSAdam Langley } 49133ad798cSAdam Langley 492bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 49333ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 49433ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 49533ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 49633ad798cSAdam Langley opts->ws); 49733ad798cSAdam Langley } 49833ad798cSAdam Langley 49933ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 50033ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 50133ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 50240efc6faSStephen Hemminger int this_sack; 50340efc6faSStephen Hemminger 50440efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 50540efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 50640efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 50733ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 50840efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5092de979bdSStephen Hemminger 51033ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 51133ad798cSAdam Langley ++this_sack) { 51240efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 51340efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 51440efc6faSStephen Hemminger } 5152de979bdSStephen Hemminger 51640efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 51740efc6faSStephen Hemminger } 5182100c8d2SYuchung Cheng 5192100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5202100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 521*7f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 522*7f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 5232100c8d2SYuchung Cheng 524*7f9b838bSDaniel Lee if (foc->exp) { 525*7f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 526*7f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 5272100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 528*7f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 529*7f9b838bSDaniel Lee } else { 530*7f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 531*7f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 532*7f9b838bSDaniel Lee *p++ = len; 5332100c8d2SYuchung Cheng } 534*7f9b838bSDaniel Lee 535*7f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 536*7f9b838bSDaniel Lee if ((len & 3) == 2) { 537*7f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 538*7f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 539*7f9b838bSDaniel Lee } 540*7f9b838bSDaniel Lee ptr += (len + 3) >> 2; 5412100c8d2SYuchung Cheng } 54240efc6faSStephen Hemminger } 54340efc6faSStephen Hemminger 54467edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 54567edfef7SAndi Kleen * network wire format yet. 54667edfef7SAndi Kleen */ 54795c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 54833ad798cSAdam Langley struct tcp_out_options *opts, 549cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 550cf533ea5SEric Dumazet { 55133ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 55295c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 553783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 55433ad798cSAdam Langley 555cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 55633ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 55733ad798cSAdam Langley if (*md5) { 55833ad798cSAdam Langley opts->options |= OPTION_MD5; 559bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 560cfb6eeb4SYOSHIFUJI Hideaki } 56133ad798cSAdam Langley #else 56233ad798cSAdam Langley *md5 = NULL; 563cfb6eeb4SYOSHIFUJI Hideaki #endif 56433ad798cSAdam Langley 56533ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 56633ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 56733ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 56833ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 56933ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 57033ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 57133ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 57233ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 57333ad798cSAdam Langley * going out. */ 57433ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 575bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 57633ad798cSAdam Langley 57751456b29SIan Morris if (likely(sysctl_tcp_timestamps && !*md5)) { 57833ad798cSAdam Langley opts->options |= OPTION_TS; 5797faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 58033ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 581bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 58233ad798cSAdam Langley } 583bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_window_scaling)) { 58433ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 58589e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 586bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 58733ad798cSAdam Langley } 588bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_sack)) { 58933ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 590b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 591bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 59233ad798cSAdam Langley } 59333ad798cSAdam Langley 594783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 595783237e8SYuchung Cheng u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len; 596783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 597783237e8SYuchung Cheng if (remaining >= need) { 598783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 599783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 600783237e8SYuchung Cheng remaining -= need; 601783237e8SYuchung Cheng tp->syn_fastopen = 1; 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. */ 60995c96174SEric Dumazet static unsigned int tcp_synack_options(struct sock *sk, 61033ad798cSAdam Langley struct request_sock *req, 61195c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 61233ad798cSAdam Langley struct tcp_out_options *opts, 61380f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 6148336886fSJerry Chu struct tcp_fastopen_cookie *foc) 6154957faadSWilliam Allen Simpson { 61633ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 61795c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 61833ad798cSAdam Langley 61933ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 62080f03e27SEric Dumazet if (md5) { 62133ad798cSAdam Langley opts->options |= OPTION_MD5; 6224957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6234957faadSWilliam Allen Simpson 6244957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6254957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6264957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6274957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6284957faadSWilliam Allen Simpson */ 629de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 63033ad798cSAdam Langley } 63133ad798cSAdam Langley #endif 63233ad798cSAdam Langley 6334957faadSWilliam Allen Simpson /* We always send an MSS option. */ 63433ad798cSAdam Langley opts->mss = mss; 6354957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 63633ad798cSAdam Langley 63733ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 63833ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 63989e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6404957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 64133ad798cSAdam Langley } 642de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 64333ad798cSAdam Langley opts->options |= OPTION_TS; 6447faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb); 64533ad798cSAdam Langley opts->tsecr = req->ts_recent; 6464957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 64733ad798cSAdam Langley } 64833ad798cSAdam Langley if (likely(ireq->sack_ok)) { 64933ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 650de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 6514957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 65233ad798cSAdam Langley } 653*7f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 654*7f9b838bSDaniel Lee u32 need = foc->len; 655*7f9b838bSDaniel Lee 656*7f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 657*7f9b838bSDaniel Lee TCPOLEN_FASTOPEN_BASE; 6588336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 6598336886fSJerry Chu if (remaining >= need) { 6608336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 6618336886fSJerry Chu opts->fastopen_cookie = foc; 6628336886fSJerry Chu remaining -= need; 6638336886fSJerry Chu } 6648336886fSJerry Chu } 6654957faadSWilliam Allen Simpson 6664957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 66733ad798cSAdam Langley } 66833ad798cSAdam Langley 66967edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 67067edfef7SAndi Kleen * final wire format yet. 67167edfef7SAndi Kleen */ 67295c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 67333ad798cSAdam Langley struct tcp_out_options *opts, 674cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 675cf533ea5SEric Dumazet { 67633ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 67795c96174SEric Dumazet unsigned int size = 0; 678cabeccbdSIlpo Järvinen unsigned int eff_sacks; 67933ad798cSAdam Langley 6805843ef42SAndi Kleen opts->options = 0; 6815843ef42SAndi Kleen 68233ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 68333ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 68433ad798cSAdam Langley if (unlikely(*md5)) { 68533ad798cSAdam Langley opts->options |= OPTION_MD5; 68633ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 68733ad798cSAdam Langley } 68833ad798cSAdam Langley #else 68933ad798cSAdam Langley *md5 = NULL; 69033ad798cSAdam Langley #endif 69133ad798cSAdam Langley 69233ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 69333ad798cSAdam Langley opts->options |= OPTION_TS; 6947faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 69533ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 69633ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 69733ad798cSAdam Langley } 69833ad798cSAdam Langley 699cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 700cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 70195c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 70233ad798cSAdam Langley opts->num_sack_blocks = 70395c96174SEric Dumazet min_t(unsigned int, eff_sacks, 70433ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 70533ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 70633ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 70733ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 70833ad798cSAdam Langley } 70933ad798cSAdam Langley 71033ad798cSAdam Langley return size; 71140efc6faSStephen Hemminger } 7121da177e4SLinus Torvalds 71346d3ceabSEric Dumazet 71446d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 71546d3ceabSEric Dumazet * 71646d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 71746d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 71846d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 71946d3ceabSEric Dumazet * 72046d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 72146d3ceabSEric Dumazet * needs to be reallocated in a driver. 7228e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 72346d3ceabSEric Dumazet * 72446d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 72546d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 72646d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 72746d3ceabSEric Dumazet */ 72846d3ceabSEric Dumazet struct tsq_tasklet { 72946d3ceabSEric Dumazet struct tasklet_struct tasklet; 73046d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 73146d3ceabSEric Dumazet }; 73246d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 73346d3ceabSEric Dumazet 7346f458dfbSEric Dumazet static void tcp_tsq_handler(struct sock *sk) 7356f458dfbSEric Dumazet { 7366f458dfbSEric Dumazet if ((1 << sk->sk_state) & 7376f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 7386f458dfbSEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) 739bf06200eSJohn Ogness tcp_write_xmit(sk, tcp_current_mss(sk), tcp_sk(sk)->nonagle, 740bf06200eSJohn Ogness 0, GFP_ATOMIC); 7416f458dfbSEric Dumazet } 74246d3ceabSEric Dumazet /* 7438e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 74446d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 7458e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 74646d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 74746d3ceabSEric Dumazet */ 74846d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 74946d3ceabSEric Dumazet { 75046d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 75146d3ceabSEric Dumazet LIST_HEAD(list); 75246d3ceabSEric Dumazet unsigned long flags; 75346d3ceabSEric Dumazet struct list_head *q, *n; 75446d3ceabSEric Dumazet struct tcp_sock *tp; 75546d3ceabSEric Dumazet struct sock *sk; 75646d3ceabSEric Dumazet 75746d3ceabSEric Dumazet local_irq_save(flags); 75846d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 75946d3ceabSEric Dumazet local_irq_restore(flags); 76046d3ceabSEric Dumazet 76146d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 76246d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 76346d3ceabSEric Dumazet list_del(&tp->tsq_node); 76446d3ceabSEric Dumazet 76546d3ceabSEric Dumazet sk = (struct sock *)tp; 76646d3ceabSEric Dumazet bh_lock_sock(sk); 76746d3ceabSEric Dumazet 76846d3ceabSEric Dumazet if (!sock_owned_by_user(sk)) { 7696f458dfbSEric Dumazet tcp_tsq_handler(sk); 77046d3ceabSEric Dumazet } else { 77146d3ceabSEric Dumazet /* defer the work to tcp_release_cb() */ 7726f458dfbSEric Dumazet set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); 77346d3ceabSEric Dumazet } 77446d3ceabSEric Dumazet bh_unlock_sock(sk); 77546d3ceabSEric Dumazet 77646d3ceabSEric Dumazet clear_bit(TSQ_QUEUED, &tp->tsq_flags); 77746d3ceabSEric Dumazet sk_free(sk); 77846d3ceabSEric Dumazet } 77946d3ceabSEric Dumazet } 78046d3ceabSEric Dumazet 7816f458dfbSEric Dumazet #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ 7826f458dfbSEric Dumazet (1UL << TCP_WRITE_TIMER_DEFERRED) | \ 783563d34d0SEric Dumazet (1UL << TCP_DELACK_TIMER_DEFERRED) | \ 784563d34d0SEric Dumazet (1UL << TCP_MTU_REDUCED_DEFERRED)) 78546d3ceabSEric Dumazet /** 78646d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 78746d3ceabSEric Dumazet * @sk: socket 78846d3ceabSEric Dumazet * 78946d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 79046d3ceabSEric Dumazet * actions before socket release. 79146d3ceabSEric Dumazet */ 79246d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 79346d3ceabSEric Dumazet { 79446d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 7956f458dfbSEric Dumazet unsigned long flags, nflags; 79646d3ceabSEric Dumazet 7976f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 7986f458dfbSEric Dumazet do { 7996f458dfbSEric Dumazet flags = tp->tsq_flags; 8006f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 8016f458dfbSEric Dumazet return; 8026f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 8036f458dfbSEric Dumazet } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); 8046f458dfbSEric Dumazet 8056f458dfbSEric Dumazet if (flags & (1UL << TCP_TSQ_DEFERRED)) 8066f458dfbSEric Dumazet tcp_tsq_handler(sk); 8076f458dfbSEric Dumazet 808c3f9b018SEric Dumazet /* Here begins the tricky part : 809c3f9b018SEric Dumazet * We are called from release_sock() with : 810c3f9b018SEric Dumazet * 1) BH disabled 811c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 812c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 813c3f9b018SEric Dumazet * 814c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 815c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 816c3f9b018SEric Dumazet */ 817c3f9b018SEric Dumazet sock_release_ownership(sk); 818c3f9b018SEric Dumazet 819144d56e9SEric Dumazet if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { 8206f458dfbSEric Dumazet tcp_write_timer_handler(sk); 821144d56e9SEric Dumazet __sock_put(sk); 822144d56e9SEric Dumazet } 823144d56e9SEric Dumazet if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { 8246f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 825144d56e9SEric Dumazet __sock_put(sk); 826144d56e9SEric Dumazet } 827144d56e9SEric Dumazet if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { 8284fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 829144d56e9SEric Dumazet __sock_put(sk); 830144d56e9SEric Dumazet } 83146d3ceabSEric Dumazet } 83246d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 83346d3ceabSEric Dumazet 83446d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 83546d3ceabSEric Dumazet { 83646d3ceabSEric Dumazet int i; 83746d3ceabSEric Dumazet 83846d3ceabSEric Dumazet for_each_possible_cpu(i) { 83946d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 84046d3ceabSEric Dumazet 84146d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 84246d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 84346d3ceabSEric Dumazet tcp_tasklet_func, 84446d3ceabSEric Dumazet (unsigned long)tsq); 84546d3ceabSEric Dumazet } 84646d3ceabSEric Dumazet } 84746d3ceabSEric Dumazet 84846d3ceabSEric Dumazet /* 84946d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 8508e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 85146d3ceabSEric Dumazet * hold qdisc lock. 85246d3ceabSEric Dumazet */ 853d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 85446d3ceabSEric Dumazet { 85546d3ceabSEric Dumazet struct sock *sk = skb->sk; 85646d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 8579b462d02SEric Dumazet int wmem; 8589b462d02SEric Dumazet 8599b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 8609b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 8619b462d02SEric Dumazet */ 8629b462d02SEric Dumazet wmem = atomic_sub_return(skb->truesize - 1, &sk->sk_wmem_alloc); 8639b462d02SEric Dumazet 8649b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 8659b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 8669b462d02SEric Dumazet * This gives : 8679b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 8689b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 8699b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 8709b462d02SEric Dumazet */ 8719b462d02SEric Dumazet if (wmem >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 8729b462d02SEric Dumazet goto out; 87346d3ceabSEric Dumazet 87446d3ceabSEric Dumazet if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && 87546d3ceabSEric Dumazet !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { 87646d3ceabSEric Dumazet unsigned long flags; 87746d3ceabSEric Dumazet struct tsq_tasklet *tsq; 87846d3ceabSEric Dumazet 87946d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 88046d3ceabSEric Dumazet local_irq_save(flags); 881903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 88246d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 88346d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 88446d3ceabSEric Dumazet local_irq_restore(flags); 8859b462d02SEric Dumazet return; 88646d3ceabSEric Dumazet } 8879b462d02SEric Dumazet out: 8889b462d02SEric Dumazet sk_free(sk); 88946d3ceabSEric Dumazet } 89046d3ceabSEric Dumazet 8911da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 8921da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 8931da177e4SLinus Torvalds * transmission and possible later retransmissions. 8941da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 8951da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 8961da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 8971da177e4SLinus Torvalds * device. 8981da177e4SLinus Torvalds * 8991da177e4SLinus Torvalds * We are working here with either a clone of the original 9001da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 9011da177e4SLinus Torvalds */ 902056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 903056834d9SIlpo Järvinen gfp_t gfp_mask) 9041da177e4SLinus Torvalds { 9056687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 906dfb4b9dcSDavid S. Miller struct inet_sock *inet; 907dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 908dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 90933ad798cSAdam Langley struct tcp_out_options opts; 91095c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 911cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 9121da177e4SLinus Torvalds struct tcphdr *th; 9131da177e4SLinus Torvalds int err; 9141da177e4SLinus Torvalds 915dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 916dfb4b9dcSDavid S. Miller 917ccdbb6e9SEric Dumazet if (clone_it) { 918740b0f18SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 919dfb4b9dcSDavid S. Miller 920dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 921dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 922dfb4b9dcSDavid S. Miller else 923dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 924dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 925dfb4b9dcSDavid S. Miller return -ENOBUFS; 926dfb4b9dcSDavid S. Miller } 927dfb4b9dcSDavid S. Miller 928dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 929dfb4b9dcSDavid S. Miller tp = tcp_sk(sk); 930dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 93133ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 9321da177e4SLinus Torvalds 9334de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 93433ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 93533ad798cSAdam Langley else 93633ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 93733ad798cSAdam Langley &md5); 93833ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 9391da177e4SLinus Torvalds 940547669d4SEric Dumazet if (tcp_packets_in_flight(tp) == 0) 9416687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_TX_START); 942547669d4SEric Dumazet 943547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 944b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 945b2532eb9SEric Dumazet * which holds one reference to sk_wmem_alloc. 946b2532eb9SEric Dumazet * 947b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 948b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 949547669d4SEric Dumazet */ 950b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 9511da177e4SLinus Torvalds 952aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 953aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 95446d3ceabSEric Dumazet 95546d3ceabSEric Dumazet skb_orphan(skb); 95646d3ceabSEric Dumazet skb->sk = sk; 95798781965SEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? sock_wfree : tcp_wfree; 958b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 95946d3ceabSEric Dumazet atomic_add(skb->truesize, &sk->sk_wmem_alloc); 9601da177e4SLinus Torvalds 9611da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 962aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 963c720c7e8SEric Dumazet th->source = inet->inet_sport; 964c720c7e8SEric Dumazet th->dest = inet->inet_dport; 9651da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 9661da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 967df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 9684de075e0SEric Dumazet tcb->tcp_flags); 969dfb4b9dcSDavid S. Miller 9704de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 9711da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 9721da177e4SLinus Torvalds * is never scaled. 9731da177e4SLinus Torvalds */ 974600ff0c2SIlpo Järvinen th->window = htons(min(tp->rcv_wnd, 65535U)); 9751da177e4SLinus Torvalds } else { 9761da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 9771da177e4SLinus Torvalds } 9781da177e4SLinus Torvalds th->check = 0; 9791da177e4SLinus Torvalds th->urg_ptr = 0; 9801da177e4SLinus Torvalds 98133f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 9827691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 9837691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 9841da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 9851da177e4SLinus Torvalds th->urg = 1; 9867691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 9870eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 9887691367dSHerbert Xu th->urg = 1; 9897691367dSHerbert Xu } 9901da177e4SLinus Torvalds } 9911da177e4SLinus Torvalds 992bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 9934de075e0SEric Dumazet if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) 994735d3831SFlorian Westphal tcp_ecn_send(sk, skb, tcp_header_size); 995dfb4b9dcSDavid S. Miller 996cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 997cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 998cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 999a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1000bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 100139f8e58eSEric Dumazet md5, sk, skb); 1002cfb6eeb4SYOSHIFUJI Hideaki } 1003cfb6eeb4SYOSHIFUJI Hideaki #endif 1004cfb6eeb4SYOSHIFUJI Hideaki 1005bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 10061da177e4SLinus Torvalds 10074de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 1008fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 10091da177e4SLinus Torvalds 10101da177e4SLinus Torvalds if (skb->len != tcp_header_size) 1011cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 10121da177e4SLinus Torvalds 1013bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1014aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1015aa2ea058STom Herbert tcp_skb_pcount(skb)); 10161da177e4SLinus Torvalds 1017cd7d8498SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_segs */ 1018cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1019cd7d8498SEric Dumazet 10207faee5c0SEric Dumazet /* Our usage of tstamp should remain private */ 10217faee5c0SEric Dumazet skb->tstamp.tv64 = 0; 1022971f10ecSEric Dumazet 1023971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1024971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1025971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1026971f10ecSEric Dumazet 1027b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 10287faee5c0SEric Dumazet 102983de47cdSHua Zhong if (likely(err <= 0)) 10301da177e4SLinus Torvalds return err; 10311da177e4SLinus Torvalds 10325ee2c941SChristoph Paasch tcp_enter_cwr(sk); 10331da177e4SLinus Torvalds 1034b9df3cb8SGerrit Renker return net_xmit_eval(err); 10351da177e4SLinus Torvalds } 10361da177e4SLinus Torvalds 103767edfef7SAndi Kleen /* This routine just queues the buffer for sending. 10381da177e4SLinus Torvalds * 10391da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 10401da177e4SLinus Torvalds * otherwise socket can stall. 10411da177e4SLinus Torvalds */ 10421da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 10431da177e4SLinus Torvalds { 10441da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10451da177e4SLinus Torvalds 10461da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 10471da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1048f4a775d1SEric Dumazet __skb_header_release(skb); 1049fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 10503ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 10513ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 10521da177e4SLinus Torvalds } 10531da177e4SLinus Torvalds 105467edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 1055cf533ea5SEric Dumazet static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, 1056056834d9SIlpo Järvinen unsigned int mss_now) 1057f6302d1dSDavid S. Miller { 10587b7fc97aSEric Dumazet struct skb_shared_info *shinfo = skb_shinfo(skb); 10597b7fc97aSEric Dumazet 1060c52e2421SEric Dumazet /* Make sure we own this skb before messing gso_size/gso_segs */ 1061c52e2421SEric Dumazet WARN_ON_ONCE(skb_cloned(skb)); 1062c52e2421SEric Dumazet 10638f26fb1cSEric Dumazet if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { 1064f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1065f6302d1dSDavid S. Miller * non-TSO case. 1066f6302d1dSDavid S. Miller */ 1067cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 10687b7fc97aSEric Dumazet shinfo->gso_size = 0; 10697b7fc97aSEric Dumazet shinfo->gso_type = 0; 1070f6302d1dSDavid S. Miller } else { 1071cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 10727b7fc97aSEric Dumazet shinfo->gso_size = mss_now; 10737b7fc97aSEric Dumazet shinfo->gso_type = sk->sk_gso_type; 10741da177e4SLinus Torvalds } 10751da177e4SLinus Torvalds } 10761da177e4SLinus Torvalds 107791fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 107868f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 107991fed7a1SIlpo Järvinen */ 1080cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 108191fed7a1SIlpo Järvinen int decr) 108291fed7a1SIlpo Järvinen { 1083a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1084a47e5a98SIlpo Järvinen 1085dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 108691fed7a1SIlpo Järvinen return; 108791fed7a1SIlpo Järvinen 10886859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 108991fed7a1SIlpo Järvinen tp->fackets_out -= decr; 109091fed7a1SIlpo Järvinen } 109191fed7a1SIlpo Järvinen 1092797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1093797108d1SIlpo Järvinen * tweaks to fix counters 1094797108d1SIlpo Järvinen */ 1095cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1096797108d1SIlpo Järvinen { 1097797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1098797108d1SIlpo Järvinen 1099797108d1SIlpo Järvinen tp->packets_out -= decr; 1100797108d1SIlpo Järvinen 1101797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1102797108d1SIlpo Järvinen tp->sacked_out -= decr; 1103797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1104797108d1SIlpo Järvinen tp->retrans_out -= decr; 1105797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1106797108d1SIlpo Järvinen tp->lost_out -= decr; 1107797108d1SIlpo Järvinen 1108797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1109797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1110797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1111797108d1SIlpo Järvinen 1112797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1113797108d1SIlpo Järvinen 1114797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1115797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 111652cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1117797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1118797108d1SIlpo Järvinen 1119797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1120797108d1SIlpo Järvinen } 1121797108d1SIlpo Järvinen 1122490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1123490cc7d0SWillem de Bruijn { 1124490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1125490cc7d0SWillem de Bruijn 1126490cc7d0SWillem de Bruijn if (unlikely(shinfo->tx_flags & SKBTX_ANY_TSTAMP) && 1127490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1128490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1129490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1130490cc7d0SWillem de Bruijn 1131490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1132490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1133490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1134490cc7d0SWillem de Bruijn } 1135490cc7d0SWillem de Bruijn } 1136490cc7d0SWillem de Bruijn 11371da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 11381da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 11391da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 11401da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 11411da177e4SLinus Torvalds */ 1142056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 11436cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 11441da177e4SLinus Torvalds { 11451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11461da177e4SLinus Torvalds struct sk_buff *buff; 11476475be16SDavid S. Miller int nsize, old_factor; 1148b60b49eaSHerbert Xu int nlen; 11499ce01461SIlpo Järvinen u8 flags; 11501da177e4SLinus Torvalds 11512fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 11522fceec13SIlpo Järvinen return -EINVAL; 11536a438bbeSStephen Hemminger 11541da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 11551da177e4SLinus Torvalds if (nsize < 0) 11561da177e4SLinus Torvalds nsize = 0; 11571da177e4SLinus Torvalds 11586cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 11591da177e4SLinus Torvalds return -ENOMEM; 11601da177e4SLinus Torvalds 11611da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 11626cc55e09SOctavian Purdila buff = sk_stream_alloc_skb(sk, nsize, gfp); 116351456b29SIan Morris if (!buff) 11641da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1165ef5cb973SHerbert Xu 11663ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 11673ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1168b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1169b60b49eaSHerbert Xu buff->truesize += nlen; 1170b60b49eaSHerbert Xu skb->truesize -= nlen; 11711da177e4SLinus Torvalds 11721da177e4SLinus Torvalds /* Correct the sequence numbers. */ 11731da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 11741da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 11751da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 11761da177e4SLinus Torvalds 11771da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 11784de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 11794de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 11804de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1181e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 11821da177e4SLinus Torvalds 118384fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 11841da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1185056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1186056834d9SIlpo Järvinen skb_put(buff, nsize), 11871da177e4SLinus Torvalds nsize, 0); 11881da177e4SLinus Torvalds 11891da177e4SLinus Torvalds skb_trim(skb, len); 11901da177e4SLinus Torvalds 11911da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 11921da177e4SLinus Torvalds } else { 119384fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 11941da177e4SLinus Torvalds skb_split(skb, buff, len); 11951da177e4SLinus Torvalds } 11961da177e4SLinus Torvalds 11971da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 11981da177e4SLinus Torvalds 1199a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1200490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 12011da177e4SLinus Torvalds 12026475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 12036475be16SDavid S. Miller 12041da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 1205846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1206846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 12071da177e4SLinus Torvalds 12086475be16SDavid S. Miller /* If this packet has been sent out already, we must 12096475be16SDavid S. Miller * adjust the various packet counters. 12106475be16SDavid S. Miller */ 1211cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 12126475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 12136475be16SDavid S. Miller tcp_skb_pcount(buff); 12141da177e4SLinus Torvalds 1215797108d1SIlpo Järvinen if (diff) 1216797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 12171da177e4SLinus Torvalds } 12181da177e4SLinus Torvalds 12191da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1220f4a775d1SEric Dumazet __skb_header_release(buff); 1221fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 12221da177e4SLinus Torvalds 12231da177e4SLinus Torvalds return 0; 12241da177e4SLinus Torvalds } 12251da177e4SLinus Torvalds 12261da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 12271da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 12281da177e4SLinus Torvalds * immediately discarded. 12291da177e4SLinus Torvalds */ 1230f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 12311da177e4SLinus Torvalds { 12327b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 12331da177e4SLinus Torvalds int i, k, eat; 12341da177e4SLinus Torvalds 12354fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 12364fa48bf3SEric Dumazet if (eat) { 12374fa48bf3SEric Dumazet __skb_pull(skb, eat); 12384fa48bf3SEric Dumazet len -= eat; 12394fa48bf3SEric Dumazet if (!len) 12404fa48bf3SEric Dumazet return; 12414fa48bf3SEric Dumazet } 12421da177e4SLinus Torvalds eat = len; 12431da177e4SLinus Torvalds k = 0; 12447b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 12457b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 12467b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 12479e903e08SEric Dumazet 12489e903e08SEric Dumazet if (size <= eat) { 1249aff65da0SIan Campbell skb_frag_unref(skb, i); 12509e903e08SEric Dumazet eat -= size; 12511da177e4SLinus Torvalds } else { 12527b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 12531da177e4SLinus Torvalds if (eat) { 12547b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 12557b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 12561da177e4SLinus Torvalds eat = 0; 12571da177e4SLinus Torvalds } 12581da177e4SLinus Torvalds k++; 12591da177e4SLinus Torvalds } 12601da177e4SLinus Torvalds } 12617b7fc97aSEric Dumazet shinfo->nr_frags = k; 12621da177e4SLinus Torvalds 126327a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 12641da177e4SLinus Torvalds skb->data_len -= len; 12651da177e4SLinus Torvalds skb->len = skb->data_len; 12661da177e4SLinus Torvalds } 12671da177e4SLinus Torvalds 126867edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 12691da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 12701da177e4SLinus Torvalds { 127114bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 12721da177e4SLinus Torvalds return -ENOMEM; 12731da177e4SLinus Torvalds 12744fa48bf3SEric Dumazet __pskb_trim_head(skb, len); 12751da177e4SLinus Torvalds 12761da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 127784fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 12781da177e4SLinus Torvalds 12791da177e4SLinus Torvalds skb->truesize -= len; 12801da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 12813ab224beSHideo Aoki sk_mem_uncharge(sk, len); 12821da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 12831da177e4SLinus Torvalds 12845b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 12851da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 12865b35e1e6SNeal Cardwell tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds return 0; 12891da177e4SLinus Torvalds } 12901da177e4SLinus Torvalds 12911b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 12921b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 12935d424d5aSJohn Heffner { 1294cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1295cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 12965d424d5aSJohn Heffner int mss_now; 12975d424d5aSJohn Heffner 12985d424d5aSJohn Heffner /* Calculate base mss without TCP options: 12995d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 13005d424d5aSJohn Heffner */ 13015d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 13025d424d5aSJohn Heffner 130367469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 130467469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 130567469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 130667469601SEric Dumazet 130767469601SEric Dumazet if (dst && dst_allfrag(dst)) 130867469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 130967469601SEric Dumazet } 131067469601SEric Dumazet 13115d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 13125d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 13135d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 13145d424d5aSJohn Heffner 13155d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 13165d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 13175d424d5aSJohn Heffner 13185d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 13195d424d5aSJohn Heffner if (mss_now < 48) 13205d424d5aSJohn Heffner mss_now = 48; 13215d424d5aSJohn Heffner return mss_now; 13225d424d5aSJohn Heffner } 13235d424d5aSJohn Heffner 13241b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 13251b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 13261b63edd6SYuchung Cheng { 13271b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 13281b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 13291b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 13301b63edd6SYuchung Cheng } 13311b63edd6SYuchung Cheng 13325d424d5aSJohn Heffner /* Inverse of above */ 133367469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 13345d424d5aSJohn Heffner { 1335cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1336cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 13375d424d5aSJohn Heffner int mtu; 13385d424d5aSJohn Heffner 13395d424d5aSJohn Heffner mtu = mss + 13405d424d5aSJohn Heffner tp->tcp_header_len + 13415d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 13425d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 13435d424d5aSJohn Heffner 134467469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 134567469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 134667469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 134767469601SEric Dumazet 134867469601SEric Dumazet if (dst && dst_allfrag(dst)) 134967469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 135067469601SEric Dumazet } 13515d424d5aSJohn Heffner return mtu; 13525d424d5aSJohn Heffner } 13535d424d5aSJohn Heffner 135467edfef7SAndi Kleen /* MTU probing init per socket */ 13555d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 13565d424d5aSJohn Heffner { 13575d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 13585d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1359b0f9ca53SFan Du struct net *net = sock_net(sk); 13605d424d5aSJohn Heffner 1361b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 13625d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 13635d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1364b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 13655d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 136605cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 136705cbc0dbSFan Du icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; 13685d424d5aSJohn Heffner } 13694bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 13705d424d5aSJohn Heffner 13711da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 13721da177e4SLinus Torvalds 13731da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 13741da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 13751da177e4SLinus Torvalds 13761da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1377caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 13781da177e4SLinus Torvalds It also does not include TCP options. 13791da177e4SLinus Torvalds 1380d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 13811da177e4SLinus Torvalds 13821da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 13831da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 13841da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 13851da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 13861da177e4SLinus Torvalds 13871da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 13881da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 13891da177e4SLinus Torvalds 1390d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1391d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 13921da177e4SLinus Torvalds */ 13931da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 13941da177e4SLinus Torvalds { 13951da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1396d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 13975d424d5aSJohn Heffner int mss_now; 13981da177e4SLinus Torvalds 13995d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 14005d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 14011da177e4SLinus Torvalds 14025d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1403409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 14041da177e4SLinus Torvalds 14051da177e4SLinus Torvalds /* And store cached results */ 1406d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 14075d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 14085d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1409c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 14101da177e4SLinus Torvalds 14111da177e4SLinus Torvalds return mss_now; 14121da177e4SLinus Torvalds } 14134bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 14141da177e4SLinus Torvalds 14151da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 14161da177e4SLinus Torvalds * and even PMTU discovery events into account. 14171da177e4SLinus Torvalds */ 14180c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 14191da177e4SLinus Torvalds { 1420cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1421cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1422c1b4a7e6SDavid S. Miller u32 mss_now; 142395c96174SEric Dumazet unsigned int header_len; 142433ad798cSAdam Langley struct tcp_out_options opts; 142533ad798cSAdam Langley struct tcp_md5sig_key *md5; 14261da177e4SLinus Torvalds 1427c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1428c1b4a7e6SDavid S. Miller 14291da177e4SLinus Torvalds if (dst) { 14301da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1431d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 14321da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 14331da177e4SLinus Torvalds } 14341da177e4SLinus Torvalds 143533ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 143633ad798cSAdam Langley sizeof(struct tcphdr); 143733ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 143833ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 143933ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 144033ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 144133ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 144233ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 144333ad798cSAdam Langley mss_now -= delta; 144433ad798cSAdam Langley } 1445cfb6eeb4SYOSHIFUJI Hideaki 14461da177e4SLinus Torvalds return mss_now; 14471da177e4SLinus Torvalds } 14481da177e4SLinus Torvalds 144986fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 145086fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 145186fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 145286fd14adSWeiping Pan */ 145386fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1454a762a980SDavid S. Miller { 14559e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1456a762a980SDavid S. Miller 145786fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 145886fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 145986fd14adSWeiping Pan /* Limited by application or receiver window. */ 146086fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 146186fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 146286fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 146386fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 146486fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 146586fd14adSWeiping Pan } 146686fd14adSWeiping Pan tp->snd_cwnd_used = 0; 146786fd14adSWeiping Pan } 146886fd14adSWeiping Pan tp->snd_cwnd_stamp = tcp_time_stamp; 146986fd14adSWeiping Pan } 147086fd14adSWeiping Pan 1471ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1472a762a980SDavid S. Miller { 1473a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1474a762a980SDavid S. Miller 1475ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1476ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1477ca8a2263SNeal Cardwell */ 1478ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1479ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1480ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1481ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1482ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1483ca8a2263SNeal Cardwell } 1484e114a710SEric Dumazet 148524901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1486a762a980SDavid S. Miller /* Network is feed fully. */ 1487a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1488a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1489a762a980SDavid S. Miller } else { 1490a762a980SDavid S. Miller /* Network starves. */ 1491a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1492a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1493a762a980SDavid S. Miller 149415d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 149515d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1496a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1497a762a980SDavid S. Miller } 1498a762a980SDavid S. Miller } 1499a762a980SDavid S. Miller 1500d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1501d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1502d4589926SEric Dumazet { 1503d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1504d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1505d4589926SEric Dumazet } 1506d4589926SEric Dumazet 1507d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1508d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1509d4589926SEric Dumazet * The test is really : 1510d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1511d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1512d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1513d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 15140e3a4803SIlpo Järvinen */ 1515d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1516d4589926SEric Dumazet const struct sk_buff *skb) 1517d4589926SEric Dumazet { 1518d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1519d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1520d4589926SEric Dumazet } 1521d4589926SEric Dumazet 1522d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1523d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1524d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1525d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1526d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1527d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1528d4589926SEric Dumazet */ 1529d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1530cc93fc51SPeter Pan(潘卫平) int nonagle) 1531d4589926SEric Dumazet { 1532d4589926SEric Dumazet return partial && 1533d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1534d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1535d4589926SEric Dumazet } 1536605ad7f1SEric Dumazet 1537605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1538605ad7f1SEric Dumazet * to send one TSO packet per ms 1539605ad7f1SEric Dumazet */ 1540605ad7f1SEric Dumazet static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now) 1541605ad7f1SEric Dumazet { 1542605ad7f1SEric Dumazet u32 bytes, segs; 1543605ad7f1SEric Dumazet 1544605ad7f1SEric Dumazet bytes = min(sk->sk_pacing_rate >> 10, 1545605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1546605ad7f1SEric Dumazet 1547605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1548605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1549605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1550605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1551605ad7f1SEric Dumazet */ 1552605ad7f1SEric Dumazet segs = max_t(u32, bytes / mss_now, sysctl_tcp_min_tso_segs); 1553605ad7f1SEric Dumazet 1554605ad7f1SEric Dumazet return min_t(u32, segs, sk->sk_gso_max_segs); 1555605ad7f1SEric Dumazet } 1556605ad7f1SEric Dumazet 1557d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1558d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1559d4589926SEric Dumazet const struct sk_buff *skb, 1560d4589926SEric Dumazet unsigned int mss_now, 1561d4589926SEric Dumazet unsigned int max_segs, 1562d4589926SEric Dumazet int nonagle) 1563c1b4a7e6SDavid S. Miller { 1564cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1565d4589926SEric Dumazet u32 partial, needed, window, max_len; 1566c1b4a7e6SDavid S. Miller 156790840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 15681485348dSBen Hutchings max_len = mss_now * max_segs; 15690e3a4803SIlpo Järvinen 15701485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 15711485348dSBen Hutchings return max_len; 15720e3a4803SIlpo Järvinen 15735ea3a748SIlpo Järvinen needed = min(skb->len, window); 15745ea3a748SIlpo Järvinen 15751485348dSBen Hutchings if (max_len <= needed) 15761485348dSBen Hutchings return max_len; 15770e3a4803SIlpo Järvinen 1578d4589926SEric Dumazet partial = needed % mss_now; 1579d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1580d4589926SEric Dumazet * to include this last segment in this skb. 1581d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1582d4589926SEric Dumazet */ 1583cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1584d4589926SEric Dumazet return needed - partial; 1585d4589926SEric Dumazet 1586d4589926SEric Dumazet return needed; 1587c1b4a7e6SDavid S. Miller } 1588c1b4a7e6SDavid S. Miller 1589c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1590c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1591c1b4a7e6SDavid S. Miller */ 1592cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1593cf533ea5SEric Dumazet const struct sk_buff *skb) 1594c1b4a7e6SDavid S. Miller { 1595d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1596c1b4a7e6SDavid S. Miller 1597c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 15984de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 15994de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1600c1b4a7e6SDavid S. Miller return 1; 1601c1b4a7e6SDavid S. Miller 1602c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1603c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1604d649a7a8SEric Dumazet if (in_flight >= cwnd) 1605c1b4a7e6SDavid S. Miller return 0; 1606d649a7a8SEric Dumazet 1607d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1608d649a7a8SEric Dumazet * 2 GSO packets in flight. 1609d649a7a8SEric Dumazet */ 1610d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1611d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1612c1b4a7e6SDavid S. Miller } 1613c1b4a7e6SDavid S. Miller 1614b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 161567edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1616c1b4a7e6SDavid S. Miller * SKB onto the wire. 1617c1b4a7e6SDavid S. Miller */ 1618cf533ea5SEric Dumazet static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, 1619056834d9SIlpo Järvinen unsigned int mss_now) 1620c1b4a7e6SDavid S. Miller { 1621c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1622c1b4a7e6SDavid S. Miller 1623f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 1624846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1625c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1626c1b4a7e6SDavid S. Miller } 1627c1b4a7e6SDavid S. Miller return tso_segs; 1628c1b4a7e6SDavid S. Miller } 1629c1b4a7e6SDavid S. Miller 1630c1b4a7e6SDavid S. Miller 1631a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1632c1b4a7e6SDavid S. Miller * sent now. 1633c1b4a7e6SDavid S. Miller */ 1634a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1635c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1636c1b4a7e6SDavid S. Miller { 1637c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1638c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1639c1b4a7e6SDavid S. Miller * 1640c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1641c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1642c1b4a7e6SDavid S. Miller */ 1643c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1644a2a385d6SEric Dumazet return true; 1645c1b4a7e6SDavid S. Miller 16469b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 16479b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1648a2a385d6SEric Dumazet return true; 1649c1b4a7e6SDavid S. Miller 1650cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1651a2a385d6SEric Dumazet return true; 1652c1b4a7e6SDavid S. Miller 1653a2a385d6SEric Dumazet return false; 1654c1b4a7e6SDavid S. Miller } 1655c1b4a7e6SDavid S. Miller 1656c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1657a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1658a2a385d6SEric Dumazet const struct sk_buff *skb, 1659056834d9SIlpo Järvinen unsigned int cur_mss) 1660c1b4a7e6SDavid S. Miller { 1661c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1662c1b4a7e6SDavid S. Miller 1663c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1664c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1665c1b4a7e6SDavid S. Miller 166690840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1667c1b4a7e6SDavid S. Miller } 1668c1b4a7e6SDavid S. Miller 1669fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1670c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1671c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1672c1b4a7e6SDavid S. Miller */ 1673cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1674c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1675c1b4a7e6SDavid S. Miller { 1676cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1677c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1678c1b4a7e6SDavid S. Miller 1679846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 1680c1b4a7e6SDavid S. Miller 1681c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1682c1b4a7e6SDavid S. Miller return 0; 1683c1b4a7e6SDavid S. Miller 1684c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1685056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1686c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1687c1b4a7e6SDavid S. Miller 1688c1b4a7e6SDavid S. Miller return cwnd_quota; 1689c1b4a7e6SDavid S. Miller } 1690c1b4a7e6SDavid S. Miller 169167edfef7SAndi Kleen /* Test if sending is allowed right now. */ 1692a2a385d6SEric Dumazet bool tcp_may_send_now(struct sock *sk) 1693c1b4a7e6SDavid S. Miller { 1694cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1695fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1696c1b4a7e6SDavid S. Miller 1697a02cec21SEric Dumazet return skb && 16980c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1699c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1700a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1701c1b4a7e6SDavid S. Miller } 1702c1b4a7e6SDavid S. Miller 1703c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1704c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1705c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1706c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1707c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1708c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1709c1b4a7e6SDavid S. Miller */ 1710056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1711c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1712c1b4a7e6SDavid S. Miller { 1713c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1714c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 17159ce01461SIlpo Järvinen u8 flags; 1716c1b4a7e6SDavid S. Miller 1717c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1718c8ac3774SHerbert Xu if (skb->len != skb->data_len) 17196cc55e09SOctavian Purdila return tcp_fragment(sk, skb, len, mss_now, gfp); 1720c1b4a7e6SDavid S. Miller 1721c4ead4c5SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp); 172251456b29SIan Morris if (unlikely(!buff)) 1723c1b4a7e6SDavid S. Miller return -ENOMEM; 1724c1b4a7e6SDavid S. Miller 17253ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 17263ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1727b60b49eaSHerbert Xu buff->truesize += nlen; 1728c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1729c1b4a7e6SDavid S. Miller 1730c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1731c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1732c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1733c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1734c1b4a7e6SDavid S. Miller 1735c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 17364de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 17374de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 17384de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1739c1b4a7e6SDavid S. Miller 1740c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1741c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1742c1b4a7e6SDavid S. Miller 174384fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1744c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1745490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1746c1b4a7e6SDavid S. Miller 1747c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 1748846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1749846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 1750c1b4a7e6SDavid S. Miller 1751c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1752f4a775d1SEric Dumazet __skb_header_release(buff); 1753fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1754c1b4a7e6SDavid S. Miller 1755c1b4a7e6SDavid S. Miller return 0; 1756c1b4a7e6SDavid S. Miller } 1757c1b4a7e6SDavid S. Miller 1758c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1759c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1760c1b4a7e6SDavid S. Miller * 1761c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1762c1b4a7e6SDavid S. Miller */ 1763ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1764605ad7f1SEric Dumazet bool *is_cwnd_limited, u32 max_segs) 1765c1b4a7e6SDavid S. Miller { 17666687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 176750c8339eSEric Dumazet u32 age, send_win, cong_win, limit, in_flight; 176850c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 176950c8339eSEric Dumazet struct skb_mstamp now; 177050c8339eSEric Dumazet struct sk_buff *head; 1771ad9f4f50SEric Dumazet int win_divisor; 1772c1b4a7e6SDavid S. Miller 17734de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1774ae8064acSJohn Heffner goto send_now; 1775c1b4a7e6SDavid S. Miller 1776a0ea700eSEric Dumazet if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_CWR))) 1777ae8064acSJohn Heffner goto send_now; 1778ae8064acSJohn Heffner 17795f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 17805f852eb5SEric Dumazet * only if the last write was recent. 17815f852eb5SEric Dumazet */ 17825f852eb5SEric Dumazet if ((s32)(tcp_time_stamp - tp->lsndtime) > 0) 1783ae8064acSJohn Heffner goto send_now; 1784908a75c1SDavid S. Miller 1785c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1786c1b4a7e6SDavid S. Miller 1787056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1788c1b4a7e6SDavid S. Miller 178990840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1790c1b4a7e6SDavid S. Miller 1791c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1792c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1793c1b4a7e6SDavid S. Miller 1794c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1795c1b4a7e6SDavid S. Miller 1796ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 1797605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 1798ae8064acSJohn Heffner goto send_now; 1799ba244fe9SDavid S. Miller 180062ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 180162ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 180262ad2761SIlpo Järvinen goto send_now; 180362ad2761SIlpo Järvinen 1804ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1805ad9f4f50SEric Dumazet if (win_divisor) { 1806c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1807c1b4a7e6SDavid S. Miller 1808c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1809c1b4a7e6SDavid S. Miller * just use it. 1810c1b4a7e6SDavid S. Miller */ 1811ad9f4f50SEric Dumazet chunk /= win_divisor; 1812c1b4a7e6SDavid S. Miller if (limit >= chunk) 1813ae8064acSJohn Heffner goto send_now; 1814c1b4a7e6SDavid S. Miller } else { 1815c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1816c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1817c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1818c1b4a7e6SDavid S. Miller * then send now. 1819c1b4a7e6SDavid S. Miller */ 18206b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1821ae8064acSJohn Heffner goto send_now; 1822c1b4a7e6SDavid S. Miller } 1823c1b4a7e6SDavid S. Miller 182450c8339eSEric Dumazet head = tcp_write_queue_head(sk); 182550c8339eSEric Dumazet skb_mstamp_get(&now); 182650c8339eSEric Dumazet age = skb_mstamp_us_delta(&now, &head->skb_mstamp); 182750c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 182850c8339eSEric Dumazet if (age < (tp->srtt_us >> 4)) 182950c8339eSEric Dumazet goto send_now; 183050c8339eSEric Dumazet 18315f852eb5SEric Dumazet /* Ok, it looks like it is advisable to defer. */ 1832ae8064acSJohn Heffner 1833ca8a2263SNeal Cardwell if (cong_win < send_win && cong_win < skb->len) 1834ca8a2263SNeal Cardwell *is_cwnd_limited = true; 1835ca8a2263SNeal Cardwell 1836a2a385d6SEric Dumazet return true; 1837ae8064acSJohn Heffner 1838ae8064acSJohn Heffner send_now: 1839a2a385d6SEric Dumazet return false; 1840c1b4a7e6SDavid S. Miller } 1841c1b4a7e6SDavid S. Miller 184205cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 184305cbc0dbSFan Du { 184405cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 184505cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 184605cbc0dbSFan Du struct net *net = sock_net(sk); 184705cbc0dbSFan Du u32 interval; 184805cbc0dbSFan Du s32 delta; 184905cbc0dbSFan Du 185005cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 185105cbc0dbSFan Du delta = tcp_time_stamp - icsk->icsk_mtup.probe_timestamp; 185205cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 185305cbc0dbSFan Du int mss = tcp_current_mss(sk); 185405cbc0dbSFan Du 185505cbc0dbSFan Du /* Update current search range */ 185605cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 185705cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 185805cbc0dbSFan Du sizeof(struct tcphdr) + 185905cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 186005cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 186105cbc0dbSFan Du 186205cbc0dbSFan Du /* Update probe time stamp */ 186305cbc0dbSFan Du icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; 186405cbc0dbSFan Du } 186505cbc0dbSFan Du } 186605cbc0dbSFan Du 18675d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 186867edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 186967edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 187067edfef7SAndi Kleen * changes resulting in larger path MTUs. 187167edfef7SAndi Kleen * 18725d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 18735d424d5aSJohn Heffner * 1 if a probe was sent, 1874056834d9SIlpo Järvinen * -1 otherwise 1875056834d9SIlpo Järvinen */ 18765d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 18775d424d5aSJohn Heffner { 18785d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 18795d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 18805d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 18816b58e0a5SFan Du struct net *net = sock_net(sk); 18825d424d5aSJohn Heffner int len; 18835d424d5aSJohn Heffner int probe_size; 188491cc17c0SIlpo Järvinen int size_needed; 18855d424d5aSJohn Heffner int copy; 18865d424d5aSJohn Heffner int mss_now; 18876b58e0a5SFan Du int interval; 18885d424d5aSJohn Heffner 18895d424d5aSJohn Heffner /* Not currently probing/verifying, 18905d424d5aSJohn Heffner * not in recovery, 18915d424d5aSJohn Heffner * have enough cwnd, and 18925d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 18935d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 18945d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 18955d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 18965d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1897cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 18985d424d5aSJohn Heffner return -1; 18995d424d5aSJohn Heffner 19006b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 19016b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 19026b58e0a5SFan Du * smaller than a threshold, backoff from probing. 19036b58e0a5SFan Du */ 19040c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 19056b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 19066b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 190791cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 19086b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 190905cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 191005cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 191105cbc0dbSFan Du * probing process by not resetting search range to its orignal. 191205cbc0dbSFan Du */ 19136b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 191405cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 191505cbc0dbSFan Du /* Check whether enough time has elaplased for 191605cbc0dbSFan Du * another round of probing. 191705cbc0dbSFan Du */ 191805cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 19195d424d5aSJohn Heffner return -1; 19205d424d5aSJohn Heffner } 19215d424d5aSJohn Heffner 19225d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 19237f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 19245d424d5aSJohn Heffner return -1; 19255d424d5aSJohn Heffner 192691cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 19275d424d5aSJohn Heffner return -1; 192890840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 19295d424d5aSJohn Heffner return 0; 19305d424d5aSJohn Heffner 1931d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1932d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1933d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 19345d424d5aSJohn Heffner return -1; 19355d424d5aSJohn Heffner else 19365d424d5aSJohn Heffner return 0; 19375d424d5aSJohn Heffner } 19385d424d5aSJohn Heffner 19395d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 194051456b29SIan Morris nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC); 194151456b29SIan Morris if (!nskb) 19425d424d5aSJohn Heffner return -1; 19433ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 19443ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 19455d424d5aSJohn Heffner 1946fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 19475d424d5aSJohn Heffner 19485d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 19495d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 19504de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 19515d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 19525d424d5aSJohn Heffner nskb->csum = 0; 195384fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 19545d424d5aSJohn Heffner 195550c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 195650c4817eSIlpo Järvinen 19575d424d5aSJohn Heffner len = 0; 1958234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 19595d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 19605d424d5aSJohn Heffner if (nskb->ip_summed) 19615d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 19625d424d5aSJohn Heffner else 19635d424d5aSJohn Heffner nskb->csum = skb_copy_and_csum_bits(skb, 0, 1964056834d9SIlpo Järvinen skb_put(nskb, copy), 1965056834d9SIlpo Järvinen copy, nskb->csum); 19665d424d5aSJohn Heffner 19675d424d5aSJohn Heffner if (skb->len <= copy) { 19685d424d5aSJohn Heffner /* We've eaten all the data from this skb. 19695d424d5aSJohn Heffner * Throw it away. */ 19704de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 1971fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 19723ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 19735d424d5aSJohn Heffner } else { 19744de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 1975a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 19765d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 19775d424d5aSJohn Heffner skb_pull(skb, copy); 197884fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 1979056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 1980056834d9SIlpo Järvinen skb->len, 0); 19815d424d5aSJohn Heffner } else { 19825d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 19835d424d5aSJohn Heffner tcp_set_skb_tso_segs(sk, skb, mss_now); 19845d424d5aSJohn Heffner } 19855d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 19865d424d5aSJohn Heffner } 19875d424d5aSJohn Heffner 19885d424d5aSJohn Heffner len += copy; 1989234b6860SIlpo Järvinen 1990234b6860SIlpo Järvinen if (len >= probe_size) 1991234b6860SIlpo Järvinen break; 19925d424d5aSJohn Heffner } 19935d424d5aSJohn Heffner tcp_init_tso_segs(sk, nskb, nskb->len); 19945d424d5aSJohn Heffner 19955d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 19967faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 19977faee5c0SEric Dumazet */ 19985d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 19995d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 20005d424d5aSJohn Heffner * effectively two packets. */ 20015d424d5aSJohn Heffner tp->snd_cwnd--; 200266f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 20035d424d5aSJohn Heffner 20045d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 20050e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 20060e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 20075d424d5aSJohn Heffner 20085d424d5aSJohn Heffner return 1; 20095d424d5aSJohn Heffner } 20105d424d5aSJohn Heffner 20115d424d5aSJohn Heffner return -1; 20125d424d5aSJohn Heffner } 20135d424d5aSJohn Heffner 20141da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 20151da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 20161da177e4SLinus Torvalds * window for us. 20171da177e4SLinus Torvalds * 2018f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2019f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2020f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2021f8269a49SIlpo Järvinen * 20226ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 20236ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 20246ba8a3b1SNandita Dukkipati 2025a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2026a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 20271da177e4SLinus Torvalds */ 2028a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2029d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 20301da177e4SLinus Torvalds { 20311da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 203292df7b51SDavid S. Miller struct sk_buff *skb; 2033c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2034c1b4a7e6SDavid S. Miller int cwnd_quota; 20355d424d5aSJohn Heffner int result; 2036ca8a2263SNeal Cardwell bool is_cwnd_limited = false; 2037605ad7f1SEric Dumazet u32 max_segs; 20381da177e4SLinus Torvalds 2039c1b4a7e6SDavid S. Miller sent_pkts = 0; 20405d424d5aSJohn Heffner 2041d5dd9175SIlpo Järvinen if (!push_one) { 20425d424d5aSJohn Heffner /* Do MTU probing. */ 2043d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2044d5dd9175SIlpo Järvinen if (!result) { 2045a2a385d6SEric Dumazet return false; 20465d424d5aSJohn Heffner } else if (result > 0) { 20475d424d5aSJohn Heffner sent_pkts = 1; 20485d424d5aSJohn Heffner } 2049d5dd9175SIlpo Järvinen } 20505d424d5aSJohn Heffner 2051605ad7f1SEric Dumazet max_segs = tcp_tso_autosize(sk, mss_now); 2052fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2053c8ac3774SHerbert Xu unsigned int limit; 2054c8ac3774SHerbert Xu 2055b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 2056c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2057c1b4a7e6SDavid S. Miller 20589d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 20597faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 20607faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 2061ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 20629d186cacSAndrey Vagin } 2063ec342325SAndrew Vagin 2064b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 20656ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 2066ca8a2263SNeal Cardwell is_cwnd_limited = true; 20676ba8a3b1SNandita Dukkipati if (push_one == 2) 20686ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 20696ba8a3b1SNandita Dukkipati cwnd_quota = 1; 20706ba8a3b1SNandita Dukkipati else 2071b68e9f85SHerbert Xu break; 20726ba8a3b1SNandita Dukkipati } 2073b68e9f85SHerbert Xu 2074b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 2075b68e9f85SHerbert Xu break; 2076b68e9f85SHerbert Xu 2077843925f3SHerbert Xu if (tso_segs == 1 || !max_segs) { 2078aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2079aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2080aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2081aa93466bSDavid S. Miller break; 2082c1b4a7e6SDavid S. Miller } else { 2083ca8a2263SNeal Cardwell if (!push_one && 2084605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2085605ad7f1SEric Dumazet max_segs)) 2086aa93466bSDavid S. Miller break; 2087c1b4a7e6SDavid S. Miller } 2088aa93466bSDavid S. Miller 2089605ad7f1SEric Dumazet limit = mss_now; 2090843925f3SHerbert Xu if (tso_segs > 1 && max_segs && !tcp_urg_mode(tp)) 2091605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2092605ad7f1SEric Dumazet min_t(unsigned int, 2093605ad7f1SEric Dumazet cwnd_quota, 2094605ad7f1SEric Dumazet max_segs), 2095605ad7f1SEric Dumazet nonagle); 2096605ad7f1SEric Dumazet 2097605ad7f1SEric Dumazet if (skb->len > limit && 2098605ad7f1SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2099605ad7f1SEric Dumazet break; 2100605ad7f1SEric Dumazet 2101c9eeec26SEric Dumazet /* TCP Small Queues : 2102c9eeec26SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2103c9eeec26SEric Dumazet * This allows for : 2104c9eeec26SEric Dumazet * - better RTT estimation and ACK scheduling 2105c9eeec26SEric Dumazet * - faster recovery 2106c9eeec26SEric Dumazet * - high rates 210798e09386SEric Dumazet * Alas, some drivers / subsystems require a fair amount 210898e09386SEric Dumazet * of queued bytes to ensure line rate. 210998e09386SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 211046d3ceabSEric Dumazet */ 2111605ad7f1SEric Dumazet limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10); 2112605ad7f1SEric Dumazet limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes); 2113c9eeec26SEric Dumazet 2114c9eeec26SEric Dumazet if (atomic_read(&sk->sk_wmem_alloc) > limit) { 211546d3ceabSEric Dumazet set_bit(TSQ_THROTTLED, &tp->tsq_flags); 2116bf06200eSJohn Ogness /* It is possible TX completion already happened 2117bf06200eSJohn Ogness * before we set TSQ_THROTTLED, so we must 2118bf06200eSJohn Ogness * test again the condition. 2119bf06200eSJohn Ogness */ 21204e857c58SPeter Zijlstra smp_mb__after_atomic(); 2121bf06200eSJohn Ogness if (atomic_read(&sk->sk_wmem_alloc) > limit) 212246d3ceabSEric Dumazet break; 212346d3ceabSEric Dumazet } 2124c9eeec26SEric Dumazet 2125d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 21261da177e4SLinus Torvalds break; 21271da177e4SLinus Torvalds 2128ec342325SAndrew Vagin repair: 21291da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 21301da177e4SLinus Torvalds * This call will increment packets_out. 21311da177e4SLinus Torvalds */ 213266f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 21331da177e4SLinus Torvalds 21341da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2135a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2136d5dd9175SIlpo Järvinen 2137d5dd9175SIlpo Järvinen if (push_one) 2138d5dd9175SIlpo Järvinen break; 21391da177e4SLinus Torvalds } 21401da177e4SLinus Torvalds 2141aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2142684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2143684bad11SYuchung Cheng tp->prr_out += sent_pkts; 21446ba8a3b1SNandita Dukkipati 21456ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 21466ba8a3b1SNandita Dukkipati if (push_one != 2) 21476ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 2148ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2149a2a385d6SEric Dumazet return false; 21501da177e4SLinus Torvalds } 21516ba8a3b1SNandita Dukkipati return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); 21526ba8a3b1SNandita Dukkipati } 21536ba8a3b1SNandita Dukkipati 21546ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 21556ba8a3b1SNandita Dukkipati { 21566ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 21576ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 21586ba8a3b1SNandita Dukkipati u32 timeout, tlp_time_stamp, rto_time_stamp; 2159740b0f18SEric Dumazet u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); 21606ba8a3b1SNandita Dukkipati 21616ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) 21626ba8a3b1SNandita Dukkipati return false; 21636ba8a3b1SNandita Dukkipati /* No consecutive loss probes. */ 21646ba8a3b1SNandita Dukkipati if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { 21656ba8a3b1SNandita Dukkipati tcp_rearm_rto(sk); 21666ba8a3b1SNandita Dukkipati return false; 21676ba8a3b1SNandita Dukkipati } 21686ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 21696ba8a3b1SNandita Dukkipati * finishes. 21706ba8a3b1SNandita Dukkipati */ 21716ba8a3b1SNandita Dukkipati if (sk->sk_state == TCP_SYN_RECV) 21726ba8a3b1SNandita Dukkipati return false; 21736ba8a3b1SNandita Dukkipati 21746ba8a3b1SNandita Dukkipati /* TLP is only scheduled when next timer event is RTO. */ 21756ba8a3b1SNandita Dukkipati if (icsk->icsk_pending != ICSK_TIME_RETRANS) 21766ba8a3b1SNandita Dukkipati return false; 21776ba8a3b1SNandita Dukkipati 21786ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 21796ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 21806ba8a3b1SNandita Dukkipati */ 2181740b0f18SEric Dumazet if (sysctl_tcp_early_retrans < 3 || !tp->srtt_us || !tp->packets_out || 21826ba8a3b1SNandita Dukkipati !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) 21836ba8a3b1SNandita Dukkipati return false; 21846ba8a3b1SNandita Dukkipati 21856ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 21866ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 21876ba8a3b1SNandita Dukkipati return false; 21886ba8a3b1SNandita Dukkipati 21896ba8a3b1SNandita Dukkipati /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account 21906ba8a3b1SNandita Dukkipati * for delayed ack when there's one outstanding packet. 21916ba8a3b1SNandita Dukkipati */ 21926ba8a3b1SNandita Dukkipati timeout = rtt << 1; 21936ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 21946ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, 21956ba8a3b1SNandita Dukkipati (rtt + (rtt >> 1) + TCP_DELACK_MAX)); 21966ba8a3b1SNandita Dukkipati timeout = max_t(u32, timeout, msecs_to_jiffies(10)); 21976ba8a3b1SNandita Dukkipati 21986ba8a3b1SNandita Dukkipati /* If RTO is shorter, just schedule TLP in its place. */ 21996ba8a3b1SNandita Dukkipati tlp_time_stamp = tcp_time_stamp + timeout; 22006ba8a3b1SNandita Dukkipati rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; 22016ba8a3b1SNandita Dukkipati if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { 22026ba8a3b1SNandita Dukkipati s32 delta = rto_time_stamp - tcp_time_stamp; 22036ba8a3b1SNandita Dukkipati if (delta > 0) 22046ba8a3b1SNandita Dukkipati timeout = delta; 22056ba8a3b1SNandita Dukkipati } 22066ba8a3b1SNandita Dukkipati 22076ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 22086ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 22096ba8a3b1SNandita Dukkipati return true; 22106ba8a3b1SNandita Dukkipati } 22116ba8a3b1SNandita Dukkipati 22121f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 22131f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 22141f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 22151f3279aeSEric Dumazet * Note: This is called from BH context only. 22161f3279aeSEric Dumazet */ 22171f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 22181f3279aeSEric Dumazet const struct sk_buff *skb) 22191f3279aeSEric Dumazet { 222039bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 22211f3279aeSEric Dumazet NET_INC_STATS_BH(sock_net(sk), 22221f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 22231f3279aeSEric Dumazet return true; 22241f3279aeSEric Dumazet } 22251f3279aeSEric Dumazet return false; 22261f3279aeSEric Dumazet } 22271f3279aeSEric Dumazet 22286ba8a3b1SNandita Dukkipati /* When probe timeout (PTO) fires, send a new segment if one exists, else 22296ba8a3b1SNandita Dukkipati * retransmit the last segment. 22306ba8a3b1SNandita Dukkipati */ 22316ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 22326ba8a3b1SNandita Dukkipati { 22339b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 22346ba8a3b1SNandita Dukkipati struct sk_buff *skb; 22356ba8a3b1SNandita Dukkipati int pcount; 22366ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 22376ba8a3b1SNandita Dukkipati int err = -1; 22386ba8a3b1SNandita Dukkipati 223900db4124SIan Morris if (tcp_send_head(sk)) { 22406ba8a3b1SNandita Dukkipati err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 22416ba8a3b1SNandita Dukkipati goto rearm_timer; 22426ba8a3b1SNandita Dukkipati } 22436ba8a3b1SNandita Dukkipati 22449b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 22459b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 22469b717a8dSNandita Dukkipati goto rearm_timer; 22479b717a8dSNandita Dukkipati 22486ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 22496ba8a3b1SNandita Dukkipati skb = tcp_write_queue_tail(sk); 22506ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 22516ba8a3b1SNandita Dukkipati goto rearm_timer; 22526ba8a3b1SNandita Dukkipati 22531f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 22541f3279aeSEric Dumazet goto rearm_timer; 22551f3279aeSEric Dumazet 22566ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 22576ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 22586ba8a3b1SNandita Dukkipati goto rearm_timer; 22596ba8a3b1SNandita Dukkipati 22606ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 22616cc55e09SOctavian Purdila if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, 22626cc55e09SOctavian Purdila GFP_ATOMIC))) 22636ba8a3b1SNandita Dukkipati goto rearm_timer; 22646ba8a3b1SNandita Dukkipati skb = tcp_write_queue_tail(sk); 22656ba8a3b1SNandita Dukkipati } 22666ba8a3b1SNandita Dukkipati 22676ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 22686ba8a3b1SNandita Dukkipati goto rearm_timer; 22696ba8a3b1SNandita Dukkipati 22706ba8a3b1SNandita Dukkipati err = __tcp_retransmit_skb(sk, skb); 22716ba8a3b1SNandita Dukkipati 22729b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 22739b717a8dSNandita Dukkipati if (likely(!err)) 22749b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 22759b717a8dSNandita Dukkipati 22766ba8a3b1SNandita Dukkipati rearm_timer: 22776ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 22786ba8a3b1SNandita Dukkipati inet_csk(sk)->icsk_rto, 22796ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 22806ba8a3b1SNandita Dukkipati 22816ba8a3b1SNandita Dukkipati if (likely(!err)) 22826ba8a3b1SNandita Dukkipati NET_INC_STATS_BH(sock_net(sk), 22836ba8a3b1SNandita Dukkipati LINUX_MIB_TCPLOSSPROBES); 22841da177e4SLinus Torvalds } 22851da177e4SLinus Torvalds 2286a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2287a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2288a762a980SDavid S. Miller * The socket must be locked by the caller. 2289a762a980SDavid S. Miller */ 22909e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 22919e412ba7SIlpo Järvinen int nonagle) 2292a762a980SDavid S. Miller { 2293726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2294726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2295726e07a8SIlpo Järvinen * all will be happy. 2296726e07a8SIlpo Järvinen */ 2297726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2298726e07a8SIlpo Järvinen return; 2299726e07a8SIlpo Järvinen 230099a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 230199a1dec7SMel Gorman sk_gfp_atomic(sk, GFP_ATOMIC))) 23029e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2303a762a980SDavid S. Miller } 2304a762a980SDavid S. Miller 2305c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2306c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2307c1b4a7e6SDavid S. Miller */ 2308c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2309c1b4a7e6SDavid S. Miller { 2310fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2311c1b4a7e6SDavid S. Miller 2312c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2313c1b4a7e6SDavid S. Miller 2314d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2315c1b4a7e6SDavid S. Miller } 2316c1b4a7e6SDavid S. Miller 23171da177e4SLinus Torvalds /* This function returns the amount that we can raise the 23181da177e4SLinus Torvalds * usable window based on the following constraints 23191da177e4SLinus Torvalds * 23201da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 23211da177e4SLinus Torvalds * 2. We limit memory per socket 23221da177e4SLinus Torvalds * 23231da177e4SLinus Torvalds * RFC 1122: 23241da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 23251da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 23261da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 23271da177e4SLinus Torvalds * 23281da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 23291da177e4SLinus Torvalds * it at least MSS bytes. 23301da177e4SLinus Torvalds * 23311da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 23321da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 23331da177e4SLinus Torvalds * 23341da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 23351da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 23361da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 23371da177e4SLinus Torvalds * window to always advance by a single byte. 23381da177e4SLinus Torvalds * 23391da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 23401da177e4SLinus Torvalds * then this will not be a problem. 23411da177e4SLinus Torvalds * 23421da177e4SLinus Torvalds * BSD seems to make the following compromise: 23431da177e4SLinus Torvalds * 23441da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 23451da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 23461da177e4SLinus Torvalds * then set the window to 0. 23471da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 23481da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 23491da177e4SLinus Torvalds * and from being larger than the largest representable value. 23501da177e4SLinus Torvalds * 23511da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 23521da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 23531da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 23541da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 23551da177e4SLinus Torvalds * because the pipeline is full. 23561da177e4SLinus Torvalds * 23571da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 23581da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 23591da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 23601da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 23611da177e4SLinus Torvalds * of having a fixed window size at almost all times. 23621da177e4SLinus Torvalds * 23631da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 23641da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 23651da177e4SLinus Torvalds * 23661da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 23671da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 23681da177e4SLinus Torvalds */ 23691da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 23701da177e4SLinus Torvalds { 2371463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 23721da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2373caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 23741da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 23751da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 23761da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 23771da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 23781da177e4SLinus Torvalds */ 2379463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 23801da177e4SLinus Torvalds int free_space = tcp_space(sk); 238186c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 238286c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 23831da177e4SLinus Torvalds int window; 23841da177e4SLinus Torvalds 23851da177e4SLinus Torvalds if (mss > full_space) 23861da177e4SLinus Torvalds mss = full_space; 23871da177e4SLinus Torvalds 2388b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2389463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 23901da177e4SLinus Torvalds 2391180d8cd9SGlauber Costa if (sk_under_memory_pressure(sk)) 2392056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2393056834d9SIlpo Järvinen 4U * tp->advmss); 23941da177e4SLinus Torvalds 239586c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 239686c1a045SFlorian Westphal * increase it due to wscale. 239786c1a045SFlorian Westphal */ 239886c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 239986c1a045SFlorian Westphal 240086c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 240186c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 240286c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 240386c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 240486c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 240586c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 240686c1a045SFlorian Westphal */ 240786c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 24081da177e4SLinus Torvalds return 0; 24091da177e4SLinus Torvalds } 24101da177e4SLinus Torvalds 24111da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 24121da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 24131da177e4SLinus Torvalds 24141da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 24151da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 24161da177e4SLinus Torvalds */ 24171da177e4SLinus Torvalds window = tp->rcv_wnd; 24181da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 24191da177e4SLinus Torvalds window = free_space; 24201da177e4SLinus Torvalds 24211da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 24221da177e4SLinus Torvalds * Import case: prevent zero window announcement if 24231da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 24241da177e4SLinus Torvalds */ 24251da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 24261da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 24271da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 24281da177e4SLinus Torvalds } else { 24291da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 24301da177e4SLinus Torvalds * Window clamp already applied above. 24311da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 24321da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 24331da177e4SLinus Torvalds * and multiply from happening most of the time. 24341da177e4SLinus Torvalds * We also don't do any window rounding when the free space 24351da177e4SLinus Torvalds * is too small. 24361da177e4SLinus Torvalds */ 24371da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 24381da177e4SLinus Torvalds window = (free_space / mss) * mss; 243984565070SJohn Heffner else if (mss == full_space && 2440b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 244184565070SJohn Heffner window = free_space; 24421da177e4SLinus Torvalds } 24431da177e4SLinus Torvalds 24441da177e4SLinus Torvalds return window; 24451da177e4SLinus Torvalds } 24461da177e4SLinus Torvalds 24474a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 24484a17fc3aSIlpo Järvinen static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 24491da177e4SLinus Torvalds { 24501da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2451fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2452058dc334SIlpo Järvinen int skb_size, next_skb_size; 24531da177e4SLinus Torvalds 2454058dc334SIlpo Järvinen skb_size = skb->len; 2455058dc334SIlpo Järvinen next_skb_size = next_skb->len; 24561da177e4SLinus Torvalds 2457058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 24581da177e4SLinus Torvalds 24596859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 2460a6963a6bSIlpo Järvinen 2461fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 24621da177e4SLinus Torvalds 2463058dc334SIlpo Järvinen skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), 24641a4e2d09SArnaldo Carvalho de Melo next_skb_size); 24651da177e4SLinus Torvalds 246652d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 246752d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 24681da177e4SLinus Torvalds 246984fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 24701da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 24711da177e4SLinus Torvalds 24721da177e4SLinus Torvalds /* Update sequence range on original skb. */ 24731da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 24741da177e4SLinus Torvalds 2475e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 24764de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 24771da177e4SLinus Torvalds 24781da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 24791da177e4SLinus Torvalds * packet counting does not break. 24801da177e4SLinus Torvalds */ 24814828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2482b7689205SIlpo Järvinen 2483b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2484ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2485ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2486ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2487b7689205SIlpo Järvinen 2488797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2489797108d1SIlpo Järvinen 24903ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 24911da177e4SLinus Torvalds } 24921da177e4SLinus Torvalds 249367edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2494a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 24954a17fc3aSIlpo Järvinen { 24964a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2497a2a385d6SEric Dumazet return false; 24984a17fc3aSIlpo Järvinen /* TODO: SACK collapsing could be used to remove this condition */ 24994a17fc3aSIlpo Järvinen if (skb_shinfo(skb)->nr_frags != 0) 2500a2a385d6SEric Dumazet return false; 25014a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2502a2a385d6SEric Dumazet return false; 25034a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2504a2a385d6SEric Dumazet return false; 25054a17fc3aSIlpo Järvinen /* Some heurestics for collapsing over SACK'd could be invented */ 25064a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2507a2a385d6SEric Dumazet return false; 25084a17fc3aSIlpo Järvinen 2509a2a385d6SEric Dumazet return true; 25104a17fc3aSIlpo Järvinen } 25114a17fc3aSIlpo Järvinen 251267edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 251367edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 251467edfef7SAndi Kleen */ 25154a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 25164a17fc3aSIlpo Järvinen int space) 25174a17fc3aSIlpo Järvinen { 25184a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 25194a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2520a2a385d6SEric Dumazet bool first = true; 25214a17fc3aSIlpo Järvinen 25224a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 25234a17fc3aSIlpo Järvinen return; 25244de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 25254a17fc3aSIlpo Järvinen return; 25264a17fc3aSIlpo Järvinen 25274a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 25284a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 25294a17fc3aSIlpo Järvinen break; 25304a17fc3aSIlpo Järvinen 25314a17fc3aSIlpo Järvinen space -= skb->len; 25324a17fc3aSIlpo Järvinen 25334a17fc3aSIlpo Järvinen if (first) { 2534a2a385d6SEric Dumazet first = false; 25354a17fc3aSIlpo Järvinen continue; 25364a17fc3aSIlpo Järvinen } 25374a17fc3aSIlpo Järvinen 25384a17fc3aSIlpo Järvinen if (space < 0) 25394a17fc3aSIlpo Järvinen break; 25404a17fc3aSIlpo Järvinen /* Punt if not enough space exists in the first SKB for 25414a17fc3aSIlpo Järvinen * the data in the second 25424a17fc3aSIlpo Järvinen */ 2543a21d4572SEric Dumazet if (skb->len > skb_availroom(to)) 25444a17fc3aSIlpo Järvinen break; 25454a17fc3aSIlpo Järvinen 25464a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 25474a17fc3aSIlpo Järvinen break; 25484a17fc3aSIlpo Järvinen 25494a17fc3aSIlpo Järvinen tcp_collapse_retrans(sk, to); 25504a17fc3aSIlpo Järvinen } 25514a17fc3aSIlpo Järvinen } 25524a17fc3aSIlpo Järvinen 25531da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 25541da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 25551da177e4SLinus Torvalds * error occurred which prevented the send. 25561da177e4SLinus Torvalds */ 255793b174adSYuchung Cheng int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 25581da177e4SLinus Torvalds { 25591da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 25605d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 25617d227cd2SSridhar Samudrala unsigned int cur_mss; 2562c84a5711SYuchung Cheng int err; 25631da177e4SLinus Torvalds 25645d424d5aSJohn Heffner /* Inconslusive MTU probe */ 25655d424d5aSJohn Heffner if (icsk->icsk_mtup.probe_size) { 25665d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 25675d424d5aSJohn Heffner } 25685d424d5aSJohn Heffner 25691da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2570caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 25711da177e4SLinus Torvalds */ 25721da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 25731da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 25741da177e4SLinus Torvalds return -EAGAIN; 25751da177e4SLinus Torvalds 25761f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 25771f3279aeSEric Dumazet return -EBUSY; 25781f3279aeSEric Dumazet 25791da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 25801da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 25811da177e4SLinus Torvalds BUG(); 25821da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 25831da177e4SLinus Torvalds return -ENOMEM; 25841da177e4SLinus Torvalds } 25851da177e4SLinus Torvalds 25867d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 25877d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 25887d227cd2SSridhar Samudrala 25890c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 25907d227cd2SSridhar Samudrala 25911da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 25921da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 25931da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 25941da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 25951da177e4SLinus Torvalds */ 25969d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 25979d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 25981da177e4SLinus Torvalds return -EAGAIN; 25991da177e4SLinus Torvalds 26001da177e4SLinus Torvalds if (skb->len > cur_mss) { 26016cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, cur_mss, cur_mss, GFP_ATOMIC)) 26021da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 260302276f3cSIlpo Järvinen } else { 26049eb9362eSIlpo Järvinen int oldpcount = tcp_skb_pcount(skb); 26059eb9362eSIlpo Järvinen 26069eb9362eSIlpo Järvinen if (unlikely(oldpcount > 1)) { 2607c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2608c52e2421SEric Dumazet return -ENOMEM; 260902276f3cSIlpo Järvinen tcp_init_tso_segs(sk, skb, cur_mss); 26109eb9362eSIlpo Järvinen tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); 26119eb9362eSIlpo Järvinen } 26121da177e4SLinus Torvalds } 26131da177e4SLinus Torvalds 26141da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 26151da177e4SLinus Torvalds 26161da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 26171da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 26181da177e4SLinus Torvalds */ 26191da177e4SLinus Torvalds 262050bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 262150bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 262250bceae9SThomas Graf * beyond what csum_start can cover. 262350bceae9SThomas Graf */ 262450bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 262550bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 2626117632e6SEric Dumazet struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, 2627117632e6SEric Dumazet GFP_ATOMIC); 2628c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2629117632e6SEric Dumazet -ENOBUFS; 2630117632e6SEric Dumazet } else { 2631c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2632117632e6SEric Dumazet } 2633c84a5711SYuchung Cheng 2634fc9f3501SEric Dumazet if (likely(!err)) { 2635c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2636fc9f3501SEric Dumazet /* Update global TCP statistics. */ 2637fc9f3501SEric Dumazet TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 2638fc9f3501SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 2639fc9f3501SEric Dumazet NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 2640fc9f3501SEric Dumazet tp->total_retrans++; 2641fc9f3501SEric Dumazet } 2642c84a5711SYuchung Cheng return err; 264393b174adSYuchung Cheng } 264493b174adSYuchung Cheng 264593b174adSYuchung Cheng int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 264693b174adSYuchung Cheng { 264793b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 264893b174adSYuchung Cheng int err = __tcp_retransmit_skb(sk, skb); 26491da177e4SLinus Torvalds 26501da177e4SLinus Torvalds if (err == 0) { 26511da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 26521da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2653e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 26541da177e4SLinus Torvalds } 26551da177e4SLinus Torvalds #endif 2656b08d6cb2SIlpo Järvinen if (!tp->retrans_out) 2657b08d6cb2SIlpo Järvinen tp->lost_retrans_low = tp->snd_nxt; 26581da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 26591da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 26601da177e4SLinus Torvalds 26611da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 26621da177e4SLinus Torvalds if (!tp->retrans_stamp) 26637faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 26641da177e4SLinus Torvalds 26651da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 26661da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 26671da177e4SLinus Torvalds */ 26681da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 26691f3279aeSEric Dumazet } else if (err != -EBUSY) { 267024ab6becSYuchung Cheng NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 26711da177e4SLinus Torvalds } 26726e08d5e3SYuchung Cheng 26736e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 26746e08d5e3SYuchung Cheng tp->undo_retrans = 0; 26756e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 26761da177e4SLinus Torvalds return err; 26771da177e4SLinus Torvalds } 26781da177e4SLinus Torvalds 267967edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 268067edfef7SAndi Kleen * window/congestion state. 268167edfef7SAndi Kleen */ 2682a2a385d6SEric Dumazet static bool tcp_can_forward_retransmit(struct sock *sk) 2683b5afe7bcSIlpo Järvinen { 2684b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2685cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2686b5afe7bcSIlpo Järvinen 2687b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2688b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2689a2a385d6SEric Dumazet return false; 2690b5afe7bcSIlpo Järvinen 2691b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2692b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2693a2a385d6SEric Dumazet return false; 2694b5afe7bcSIlpo Järvinen 2695b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2696b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2697b5afe7bcSIlpo Järvinen * 2698b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2699b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2700b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2701b5afe7bcSIlpo Järvinen */ 2702b5afe7bcSIlpo Järvinen 2703b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2704a2a385d6SEric Dumazet return false; 2705b5afe7bcSIlpo Järvinen 2706a2a385d6SEric Dumazet return true; 2707b5afe7bcSIlpo Järvinen } 2708b5afe7bcSIlpo Järvinen 27091da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 27101da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 27111da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 27121da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 27131da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 27141da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 27151da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 27161da177e4SLinus Torvalds */ 27171da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 27181da177e4SLinus Torvalds { 27196687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 27201da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27211da177e4SLinus Torvalds struct sk_buff *skb; 27220e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2723618d9f25SIlpo Järvinen u32 last_lost; 272461eb55f4SIlpo Järvinen int mib_idx; 27250e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 27266a438bbeSStephen Hemminger 272745e77d31SIlpo Järvinen if (!tp->packets_out) 272845e77d31SIlpo Järvinen return; 272945e77d31SIlpo Järvinen 273008ebd172SIlpo Järvinen if (!tp->lost_out) 273108ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 273208ebd172SIlpo Järvinen 2733618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 27346a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2735618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2736618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2737618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2738618d9f25SIlpo Järvinen } else { 2739fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2740618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2741618d9f25SIlpo Järvinen } 27421da177e4SLinus Torvalds 2743fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 27441da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 27451da177e4SLinus Torvalds 2746fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2747fe067e8aSDavid S. Miller break; 27486a438bbeSStephen Hemminger /* we could do better than to assign each time */ 274951456b29SIan Morris if (!hole) 27506a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 27516a438bbeSStephen Hemminger 27521da177e4SLinus Torvalds /* Assume this retransmit will generate 27531da177e4SLinus Torvalds * only one packet for congestion window 27541da177e4SLinus Torvalds * calculation purposes. This works because 27551da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 27561da177e4SLinus Torvalds * packet to be MSS sized and all the 27571da177e4SLinus Torvalds * packet counting works out. 27581da177e4SLinus Torvalds */ 27591da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 27601da177e4SLinus Torvalds return; 27610e1c54c2SIlpo Järvinen 27620e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 27630e1c54c2SIlpo Järvinen begin_fwd: 27640e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2765006f582cSIlpo Järvinen break; 27660e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 27670e1c54c2SIlpo Järvinen 27680e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2769618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 27700e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 27710e1c54c2SIlpo Järvinen break; 27720e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 277300db4124SIan Morris if (hole) { 27740e1c54c2SIlpo Järvinen skb = hole; 27750e1c54c2SIlpo Järvinen hole = NULL; 27760e1c54c2SIlpo Järvinen } 27770e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 27780e1c54c2SIlpo Järvinen goto begin_fwd; 27790e1c54c2SIlpo Järvinen 27800e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 278151456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 27820e1c54c2SIlpo Järvinen hole = skb; 278361eb55f4SIlpo Järvinen continue; 27841da177e4SLinus Torvalds 27850e1c54c2SIlpo Järvinen } else { 2786618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 27870e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 27880e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 27890e1c54c2SIlpo Järvinen else 27900e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 27910e1c54c2SIlpo Järvinen } 27920e1c54c2SIlpo Järvinen 27930e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 279461eb55f4SIlpo Järvinen continue; 279540b215e5SPavel Emelyanov 279624ab6becSYuchung Cheng if (tcp_retransmit_skb(sk, skb)) 27971da177e4SLinus Torvalds return; 279824ab6becSYuchung Cheng 2799de0744afSPavel Emelyanov NET_INC_STATS_BH(sock_net(sk), mib_idx); 28001da177e4SLinus Torvalds 2801684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2802a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2803a262f0cdSNandita Dukkipati 2804fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2805463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 28063f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 28073f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds } 28101da177e4SLinus Torvalds 28111da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 28121da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 28131da177e4SLinus Torvalds */ 28141da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 28151da177e4SLinus Torvalds { 28161da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2817fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_write_queue_tail(sk); 28181da177e4SLinus Torvalds int mss_now; 28191da177e4SLinus Torvalds 28201da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 28211da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 28221da177e4SLinus Torvalds * and IP options. 28231da177e4SLinus Torvalds */ 28240c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 28251da177e4SLinus Torvalds 282600db4124SIan Morris if (tcp_send_head(sk)) { 28274de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; 28281da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 28291da177e4SLinus Torvalds tp->write_seq++; 28301da177e4SLinus Torvalds } else { 28311da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 28321da177e4SLinus Torvalds for (;;) { 2833d22e1537SJosh Hunt skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation); 28341da177e4SLinus Torvalds if (skb) 28351da177e4SLinus Torvalds break; 28361da177e4SLinus Torvalds yield(); 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 2839e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 2840a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 28411da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 28421da177e4SLinus Torvalds } 28439e412ba7SIlpo Järvinen __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); 28441da177e4SLinus Torvalds } 28451da177e4SLinus Torvalds 28461da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 28471da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 28481da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 284965bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 28501da177e4SLinus Torvalds */ 2851dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 28521da177e4SLinus Torvalds { 28531da177e4SLinus Torvalds struct sk_buff *skb; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 28561da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 28571da177e4SLinus Torvalds if (!skb) { 28584e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 28591da177e4SLinus Torvalds return; 28601da177e4SLinus Torvalds } 28611da177e4SLinus Torvalds 28621da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 28631da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 2864e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 2865a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 28661da177e4SLinus Torvalds /* Send it off. */ 2867dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 28684e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 286926af65cbSSridhar Samudrala 287081cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 28711da177e4SLinus Torvalds } 28721da177e4SLinus Torvalds 287367edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 287467edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 28751da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 28761da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 28771da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 28781da177e4SLinus Torvalds */ 28791da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 28801da177e4SLinus Torvalds { 28811da177e4SLinus Torvalds struct sk_buff *skb; 28821da177e4SLinus Torvalds 2883fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 288451456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 288591df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 28861da177e4SLinus Torvalds return -EFAULT; 28871da177e4SLinus Torvalds } 28884de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 28891da177e4SLinus Torvalds if (skb_cloned(skb)) { 28901da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 289151456b29SIan Morris if (!nskb) 28921da177e4SLinus Torvalds return -ENOMEM; 2893fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 2894f4a775d1SEric Dumazet __skb_header_release(nskb); 2895fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 28963ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 28973ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 28983ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 28991da177e4SLinus Torvalds skb = nskb; 29001da177e4SLinus Torvalds } 29011da177e4SLinus Torvalds 29024de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 2903735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 29041da177e4SLinus Torvalds } 2905dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 29061da177e4SLinus Torvalds } 29071da177e4SLinus Torvalds 29084aea39c1SEric Dumazet /** 29094aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 29104aea39c1SEric Dumazet * sk: listener socket 29114aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 29124aea39c1SEric Dumazet * req: request_sock pointer 29134aea39c1SEric Dumazet * 29144aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 29154aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 29164aea39c1SEric Dumazet */ 29171da177e4SLinus Torvalds struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 2918e6b4d113SWilliam Allen Simpson struct request_sock *req, 29198336886fSJerry Chu struct tcp_fastopen_cookie *foc) 29201da177e4SLinus Torvalds { 2921bd0388aeSWilliam Allen Simpson struct tcp_out_options opts; 29222e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 29231da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 29241da177e4SLinus Torvalds struct tcphdr *th; 29251da177e4SLinus Torvalds struct sk_buff *skb; 292680f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 2927bd0388aeSWilliam Allen Simpson int tcp_header_size; 2928f5fff5dcSTom Quetchenbach int mss; 29291da177e4SLinus Torvalds 2930a0b8486cSEric Dumazet skb = sock_wmalloc(sk, MAX_TCP_HEADER, 1, GFP_ATOMIC); 29314aea39c1SEric Dumazet if (unlikely(!skb)) { 29324aea39c1SEric Dumazet dst_release(dst); 29331da177e4SLinus Torvalds return NULL; 29344aea39c1SEric Dumazet } 29351da177e4SLinus Torvalds /* Reserve space for headers. */ 29361da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 29371da177e4SLinus Torvalds 29384aea39c1SEric Dumazet skb_dst_set(skb, dst); 29391da177e4SLinus Torvalds 29400dbaee3bSDavid S. Miller mss = dst_metric_advmss(dst); 2941f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) 2942f5fff5dcSTom Quetchenbach mss = tp->rx_opt.user_mss; 2943f5fff5dcSTom Quetchenbach 294433ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 29458b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 29468b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 29477faee5c0SEric Dumazet skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); 29488b5f12d0SFlorian Westphal else 29498b5f12d0SFlorian Westphal #endif 29507faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 295180f03e27SEric Dumazet 295280f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 295380f03e27SEric Dumazet rcu_read_lock(); 2954fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 295580f03e27SEric Dumazet #endif 295680f03e27SEric Dumazet tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, 29571a2c6181SChristoph Paasch foc) + sizeof(*th); 295833ad798cSAdam Langley 2959aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 2960aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 29611da177e4SLinus Torvalds 2962aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 29631da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 29641da177e4SLinus Torvalds th->syn = 1; 29651da177e4SLinus Torvalds th->ack = 1; 2966735d3831SFlorian Westphal tcp_ecn_make_synack(req, th, sk); 2967b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 2968634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 2969e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 2970e870a8efSIlpo Järvinen * not even correctly set) 2971e870a8efSIlpo Järvinen */ 2972e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 2973a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 29744957faadSWilliam Allen Simpson 29751da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 29768336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 29778336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 29781da177e4SLinus Torvalds 29791da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 2980600ff0c2SIlpo Järvinen th->window = htons(min(req->rcv_wnd, 65535U)); 2981bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 29821da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 2983a0b8486cSEric Dumazet TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_OUTSEGS); 2984cfb6eeb4SYOSHIFUJI Hideaki 2985cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2986cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 298780f03e27SEric Dumazet if (md5) 2988bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 298939f8e58eSEric Dumazet md5, req_to_sk(req), skb); 299080f03e27SEric Dumazet rcu_read_unlock(); 2991cfb6eeb4SYOSHIFUJI Hideaki #endif 2992cfb6eeb4SYOSHIFUJI Hideaki 29931da177e4SLinus Torvalds return skb; 29941da177e4SLinus Torvalds } 29954bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 29961da177e4SLinus Torvalds 299781164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 299881164413SDaniel Borkmann { 299981164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 300081164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 300181164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 300281164413SDaniel Borkmann 300381164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 300481164413SDaniel Borkmann return; 300581164413SDaniel Borkmann 300681164413SDaniel Borkmann rcu_read_lock(); 300781164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 300881164413SDaniel Borkmann if (likely(ca && try_module_get(ca->owner))) { 300981164413SDaniel Borkmann module_put(icsk->icsk_ca_ops->owner); 301081164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 301181164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 301281164413SDaniel Borkmann } 301381164413SDaniel Borkmann rcu_read_unlock(); 301481164413SDaniel Borkmann } 301581164413SDaniel Borkmann 301667edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3017f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 30181da177e4SLinus Torvalds { 3019cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 30201da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 30211da177e4SLinus Torvalds __u8 rcv_wscale; 30221da177e4SLinus Torvalds 30231da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 30241da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 30251da177e4SLinus Torvalds */ 30261da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 3027bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 30281da177e4SLinus Torvalds 3029cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 303000db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3031cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3032cfb6eeb4SYOSHIFUJI Hideaki #endif 3033cfb6eeb4SYOSHIFUJI Hideaki 30341da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 30351da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 30361da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 30371da177e4SLinus Torvalds tp->max_window = 0; 30385d424d5aSJohn Heffner tcp_mtup_init(sk); 30391da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 30401da177e4SLinus Torvalds 304181164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 304281164413SDaniel Borkmann 30431da177e4SLinus Torvalds if (!tp->window_clamp) 30441da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 30450dbaee3bSDavid S. Miller tp->advmss = dst_metric_advmss(dst); 3046f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 3047f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 3048f5fff5dcSTom Quetchenbach 30491da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 30501da177e4SLinus Torvalds 3051e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3052e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3053e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3054e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3055e88c64f0SHagen Paul Pfeifer 30561da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 30571da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 30581da177e4SLinus Torvalds &tp->rcv_wnd, 30591da177e4SLinus Torvalds &tp->window_clamp, 3060bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 306131d12926Slaurent chavey &rcv_wscale, 306231d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 30631da177e4SLinus Torvalds 30641da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 30651da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 30661da177e4SLinus Torvalds 30671da177e4SLinus Torvalds sk->sk_err = 0; 30681da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 30691da177e4SLinus Torvalds tp->snd_wnd = 0; 3070ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 30711da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 30721da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 307333f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3074370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 3075ee995283SPavel Emelyanov 3076ee995283SPavel Emelyanov if (likely(!tp->repair)) 30771da177e4SLinus Torvalds tp->rcv_nxt = 0; 3078c7781a6eSAndrew Vagin else 3079c7781a6eSAndrew Vagin tp->rcv_tstamp = tcp_time_stamp; 3080ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 3081ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 30821da177e4SLinus Torvalds 3083463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 3084463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 30851da177e4SLinus Torvalds tcp_clear_retrans(tp); 30861da177e4SLinus Torvalds } 30871da177e4SLinus Torvalds 3088783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3089783237e8SYuchung Cheng { 3090783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3091783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3092783237e8SYuchung Cheng 3093783237e8SYuchung Cheng tcb->end_seq += skb->len; 3094f4a775d1SEric Dumazet __skb_header_release(skb); 3095783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 3096783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 3097783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 3098783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 3099783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3100783237e8SYuchung Cheng } 3101783237e8SYuchung Cheng 3102783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3103783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3104783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3105783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3106783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3107783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3108783237e8SYuchung Cheng */ 3109783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3110783237e8SYuchung Cheng { 3111783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3112783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 311357be5bdaSAl Viro int syn_loss = 0, space, err = 0, copied; 3114aab48743SYuchung Cheng unsigned long last_syn_loss = 0; 3115355a901eSEric Dumazet struct sk_buff *syn_data; 3116783237e8SYuchung Cheng 311767da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3118aab48743SYuchung Cheng tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, 3119aab48743SYuchung Cheng &syn_loss, &last_syn_loss); 3120aab48743SYuchung Cheng /* Recurring FO SYN losses: revert to regular handshake temporarily */ 3121aab48743SYuchung Cheng if (syn_loss > 1 && 3122aab48743SYuchung Cheng time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { 3123aab48743SYuchung Cheng fo->cookie.len = -1; 3124aab48743SYuchung Cheng goto fallback; 3125aab48743SYuchung Cheng } 3126aab48743SYuchung Cheng 312767da22d2SYuchung Cheng if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) 312867da22d2SYuchung Cheng fo->cookie.len = -1; 312967da22d2SYuchung Cheng else if (fo->cookie.len <= 0) 3130783237e8SYuchung Cheng goto fallback; 3131783237e8SYuchung Cheng 3132783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3133783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3134783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3135783237e8SYuchung Cheng */ 3136783237e8SYuchung Cheng if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) 3137783237e8SYuchung Cheng tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 31381b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3139783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3140783237e8SYuchung Cheng 3141f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3142f5ddcbbbSEric Dumazet 3143f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3144f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3145f5ddcbbbSEric Dumazet 3146355a901eSEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation); 3147355a901eSEric Dumazet if (!syn_data) 3148783237e8SYuchung Cheng goto fallback; 3149355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3150355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 315157be5bdaSAl Viro copied = copy_from_iter(skb_put(syn_data, space), space, 315257be5bdaSAl Viro &fo->data->msg_iter); 315357be5bdaSAl Viro if (unlikely(!copied)) { 3154355a901eSEric Dumazet kfree_skb(syn_data); 3155783237e8SYuchung Cheng goto fallback; 3156783237e8SYuchung Cheng } 315757be5bdaSAl Viro if (copied != space) { 315857be5bdaSAl Viro skb_trim(syn_data, copied); 315957be5bdaSAl Viro space = copied; 316057be5bdaSAl Viro } 3161783237e8SYuchung Cheng 3162355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3163355a901eSEric Dumazet if (space == fo->size) 3164355a901eSEric Dumazet fo->data = NULL; 3165355a901eSEric Dumazet fo->copied = space; 3166783237e8SYuchung Cheng 3167355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 3168355a901eSEric Dumazet 3169355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3170355a901eSEric Dumazet 3171355a901eSEric Dumazet syn->skb_mstamp = syn_data->skb_mstamp; 3172355a901eSEric Dumazet 3173355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3174355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3175355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3176355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3177431a9124SEric Dumazet */ 3178355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3179355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3180355a901eSEric Dumazet if (!err) { 318167da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 3182f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3183783237e8SYuchung Cheng goto done; 3184783237e8SYuchung Cheng } 3185783237e8SYuchung Cheng 3186783237e8SYuchung Cheng fallback: 3187783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3188783237e8SYuchung Cheng if (fo->cookie.len > 0) 3189783237e8SYuchung Cheng fo->cookie.len = 0; 3190783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3191783237e8SYuchung Cheng if (err) 3192783237e8SYuchung Cheng tp->syn_fastopen = 0; 3193783237e8SYuchung Cheng done: 3194783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3195783237e8SYuchung Cheng return err; 3196783237e8SYuchung Cheng } 3197783237e8SYuchung Cheng 319867edfef7SAndi Kleen /* Build a SYN and send it off. */ 31991da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 32001da177e4SLinus Torvalds { 32011da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32021da177e4SLinus Torvalds struct sk_buff *buff; 3203ee586811SEric Paris int err; 32041da177e4SLinus Torvalds 32051da177e4SLinus Torvalds tcp_connect_init(sk); 32061da177e4SLinus Torvalds 32072b916477SAndrey Vagin if (unlikely(tp->repair)) { 32082b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 32092b916477SAndrey Vagin return 0; 32102b916477SAndrey Vagin } 32112b916477SAndrey Vagin 3212355a901eSEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation); 3213355a901eSEric Dumazet if (unlikely(!buff)) 32141da177e4SLinus Torvalds return -ENOBUFS; 32151da177e4SLinus Torvalds 3216a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 32177faee5c0SEric Dumazet tp->retrans_stamp = tcp_time_stamp; 3218783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3219735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 32201da177e4SLinus Torvalds 3221783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3222783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3223783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3224ee586811SEric Paris if (err == -ECONNREFUSED) 3225ee586811SEric Paris return err; 3226bd37a088SWei Yongjun 3227bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3228bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3229bd37a088SWei Yongjun */ 3230bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3231bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 323281cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 32331da177e4SLinus Torvalds 32341da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 32353f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 32363f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 32371da177e4SLinus Torvalds return 0; 32381da177e4SLinus Torvalds } 32394bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 32401da177e4SLinus Torvalds 32411da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 32421da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 32431da177e4SLinus Torvalds * for details. 32441da177e4SLinus Torvalds */ 32451da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 32461da177e4SLinus Torvalds { 3247463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3248463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 32491da177e4SLinus Torvalds unsigned long timeout; 32501da177e4SLinus Torvalds 32519890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_DELAYED_ACK); 32529890092eSFlorian Westphal 32531da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3254463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 32551da177e4SLinus Torvalds int max_ato = HZ / 2; 32561da177e4SLinus Torvalds 3257056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3258056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 32591da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 32601da177e4SLinus Torvalds 32611da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 32621da177e4SLinus Torvalds 32631da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3264463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 32651da177e4SLinus Torvalds * directly. 32661da177e4SLinus Torvalds */ 3267740b0f18SEric Dumazet if (tp->srtt_us) { 3268740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3269740b0f18SEric Dumazet TCP_DELACK_MIN); 32701da177e4SLinus Torvalds 32711da177e4SLinus Torvalds if (rtt < max_ato) 32721da177e4SLinus Torvalds max_ato = rtt; 32731da177e4SLinus Torvalds } 32741da177e4SLinus Torvalds 32751da177e4SLinus Torvalds ato = min(ato, max_ato); 32761da177e4SLinus Torvalds } 32771da177e4SLinus Torvalds 32781da177e4SLinus Torvalds /* Stay within the limit we were given */ 32791da177e4SLinus Torvalds timeout = jiffies + ato; 32801da177e4SLinus Torvalds 32811da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3282463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 32831da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 32841da177e4SLinus Torvalds * send ACK now. 32851da177e4SLinus Torvalds */ 3286463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3287463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 32881da177e4SLinus Torvalds tcp_send_ack(sk); 32891da177e4SLinus Torvalds return; 32901da177e4SLinus Torvalds } 32911da177e4SLinus Torvalds 3292463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3293463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 32941da177e4SLinus Torvalds } 3295463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3296463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3297463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 32981da177e4SLinus Torvalds } 32991da177e4SLinus Torvalds 33001da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 33011da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 33021da177e4SLinus Torvalds { 33031da177e4SLinus Torvalds struct sk_buff *buff; 33041da177e4SLinus Torvalds 3305058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3306058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3307058dc334SIlpo Järvinen return; 3308058dc334SIlpo Järvinen 33099890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK); 33109890092eSFlorian Westphal 33111da177e4SLinus Torvalds /* We are not putting this on the write queue, so 33121da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 33131da177e4SLinus Torvalds * sock. 33141da177e4SLinus Torvalds */ 331599a1dec7SMel Gorman buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); 331651456b29SIan Morris if (!buff) { 3317463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3318463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 33193f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 33203f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 33211da177e4SLinus Torvalds return; 33221da177e4SLinus Torvalds } 33231da177e4SLinus Torvalds 33241da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 33251da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3326a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 33271da177e4SLinus Torvalds 332898781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 332998781965SEric Dumazet * too much. 333098781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 333198781965SEric Dumazet * We also avoid tcp_wfree() overhead (cache line miss accessing 333298781965SEric Dumazet * tp->tsq_flags) by using regular sock_wfree() 333398781965SEric Dumazet */ 333498781965SEric Dumazet skb_set_tcp_pure_ack(buff); 333598781965SEric Dumazet 33361da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 33377faee5c0SEric Dumazet skb_mstamp_get(&buff->skb_mstamp); 333899a1dec7SMel Gorman tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); 33391da177e4SLinus Torvalds } 3340e3118e83SDaniel Borkmann EXPORT_SYMBOL_GPL(tcp_send_ack); 33411da177e4SLinus Torvalds 33421da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 33431da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 33441da177e4SLinus Torvalds * 33451da177e4SLinus Torvalds * Question: what should we make while urgent mode? 33461da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 33471da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 33481da177e4SLinus Torvalds * 33491da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 33501da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 33511da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 33521da177e4SLinus Torvalds */ 33531da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 33541da177e4SLinus Torvalds { 33551da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 33561da177e4SLinus Torvalds struct sk_buff *skb; 33571da177e4SLinus Torvalds 33581da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 335999a1dec7SMel Gorman skb = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); 336051456b29SIan Morris if (!skb) 33611da177e4SLinus Torvalds return -1; 33621da177e4SLinus Torvalds 33631da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 33641da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 33651da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 33661da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 33671da177e4SLinus Torvalds * send it. 33681da177e4SLinus Torvalds */ 3369a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 33707faee5c0SEric Dumazet skb_mstamp_get(&skb->skb_mstamp); 3371dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); 33721da177e4SLinus Torvalds } 33731da177e4SLinus Torvalds 3374ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3375ee995283SPavel Emelyanov { 3376ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3377ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 3378ee995283SPavel Emelyanov tcp_xmit_probe_skb(sk, 0); 3379ee995283SPavel Emelyanov } 3380ee995283SPavel Emelyanov } 3381ee995283SPavel Emelyanov 338267edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 33831da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 33841da177e4SLinus Torvalds { 33851da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 33861da177e4SLinus Torvalds struct sk_buff *skb; 33871da177e4SLinus Torvalds 3388058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3389058dc334SIlpo Järvinen return -1; 3390058dc334SIlpo Järvinen 339100db4124SIan Morris skb = tcp_send_head(sk); 339200db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 33931da177e4SLinus Torvalds int err; 33940c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 339590840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 33961da177e4SLinus Torvalds 33971da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 33981da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 33991da177e4SLinus Torvalds 34001da177e4SLinus Torvalds /* We are probing the opening of a window 34011da177e4SLinus Torvalds * but the window size is != 0 34021da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 34031da177e4SLinus Torvalds */ 34041da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 34051da177e4SLinus Torvalds skb->len > mss) { 34061da177e4SLinus Torvalds seg_size = min(seg_size, mss); 34074de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 34086cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) 34091da177e4SLinus Torvalds return -1; 34101da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 3411846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 34121da177e4SLinus Torvalds 34134de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3414dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 341566f5fe62SIlpo Järvinen if (!err) 341666f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 34171da177e4SLinus Torvalds return err; 34181da177e4SLinus Torvalds } else { 341933f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 34204828e7f4SIlpo Järvinen tcp_xmit_probe_skb(sk, 1); 34211da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 34221da177e4SLinus Torvalds } 34231da177e4SLinus Torvalds } 34241da177e4SLinus Torvalds 34251da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 34261da177e4SLinus Torvalds * a partial packet else a zero probe. 34271da177e4SLinus Torvalds */ 34281da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 34291da177e4SLinus Torvalds { 3430463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 34311da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3432fcdd1cf4SEric Dumazet unsigned long probe_max; 34331da177e4SLinus Torvalds int err; 34341da177e4SLinus Torvalds 34351da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 34361da177e4SLinus Torvalds 3437fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 34381da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 34396687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3440463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 34411da177e4SLinus Torvalds return; 34421da177e4SLinus Torvalds } 34431da177e4SLinus Torvalds 34441da177e4SLinus Torvalds if (err <= 0) { 3445463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_backoff < sysctl_tcp_retries2) 3446463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 34476687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3448fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 34491da177e4SLinus Torvalds } else { 34501da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 34516687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 34521da177e4SLinus Torvalds * Let local senders to fight for local resources. 34531da177e4SLinus Torvalds * 34541da177e4SLinus Torvalds * Use accumulated backoff yet. 34551da177e4SLinus Torvalds */ 34566687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 34576687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3458fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 34591da177e4SLinus Torvalds } 3460fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 3461fcdd1cf4SEric Dumazet inet_csk_rto_backoff(icsk, probe_max), 3462fcdd1cf4SEric Dumazet TCP_RTO_MAX); 34631da177e4SLinus Torvalds } 34645db92c99SOctavian Purdila 34655db92c99SOctavian Purdila int tcp_rtx_synack(struct sock *sk, struct request_sock *req) 34665db92c99SOctavian Purdila { 34675db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 34685db92c99SOctavian Purdila struct flowi fl; 34695db92c99SOctavian Purdila int res; 34705db92c99SOctavian Purdila 34715db92c99SOctavian Purdila res = af_ops->send_synack(sk, NULL, &fl, req, 0, NULL); 34725db92c99SOctavian Purdila if (!res) { 34735db92c99SOctavian Purdila TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS); 34745db92c99SOctavian Purdila NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 34755db92c99SOctavian Purdila } 34765db92c99SOctavian Purdila return res; 34775db92c99SOctavian Purdila } 34785db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3479