11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 31da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 41da177e4SLinus Torvalds * interface as the means of communication with the user level. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 71da177e4SLinus Torvalds * 802c30a84SJesper Juhl * Authors: Ross Biro 91da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 101da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 111da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 121da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 131da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 141da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 151da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 161da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 171da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 181da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds /* 221da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 231da177e4SLinus Torvalds * : Fragmentation on mtu decrease 241da177e4SLinus Torvalds * : Segment collapse on retransmit 251da177e4SLinus Torvalds * : AF independence 261da177e4SLinus Torvalds * 271da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 281da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 291da177e4SLinus Torvalds * during syn/ack processing. 301da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 311da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 321da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 331da177e4SLinus Torvalds * J Hadi Salim : ECN support 341da177e4SLinus Torvalds * 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds 3791df42beSJoe Perches #define pr_fmt(fmt) "TCP: " fmt 3891df42beSJoe Perches 391da177e4SLinus Torvalds #include <net/tcp.h> 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds #include <linux/compiler.h> 425a0e3ad6STejun Heo #include <linux/gfp.h> 431da177e4SLinus Torvalds #include <linux/module.h> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 46ab32ea5dSBrian Haley int sysctl_tcp_retrans_collapse __read_mostly = 1; 471da177e4SLinus Torvalds 4815d99e02SRick Jones /* People can turn this on to work with those rare, broken TCPs that 4915d99e02SRick Jones * interpret the window field as a signed quantity. 5015d99e02SRick Jones */ 51ab32ea5dSBrian Haley int sysctl_tcp_workaround_signed_windows __read_mostly = 0; 5215d99e02SRick Jones 53c39c4c6aSWei Liu /* Default TSQ limit of four TSO segments */ 54c39c4c6aSWei Liu int sysctl_tcp_limit_output_bytes __read_mostly = 262144; 5546d3ceabSEric Dumazet 561da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 571da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 581da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 591da177e4SLinus Torvalds */ 60ab32ea5dSBrian Haley int sysctl_tcp_tso_win_divisor __read_mostly = 3; 611da177e4SLinus Torvalds 6235089bb2SDavid S. Miller /* By default, RFC2861 behavior. */ 63ab32ea5dSBrian Haley int sysctl_tcp_slow_start_after_idle __read_mostly = 1; 6435089bb2SDavid S. Miller 6546d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6646d3ceabSEric Dumazet int push_one, gfp_t gfp); 67519855c5SWilliam Allen Simpson 6867edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 69cf533ea5SEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) 706ff03ac3SIlpo Järvinen { 716ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 726ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7366f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 749e412ba7SIlpo Järvinen 75fe067e8aSDavid S. Miller tcp_advance_send_head(sk, skb); 761da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 778512430eSIlpo Järvinen 7866f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 79bec41a11SYuchung Cheng if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) 80750ea2baSYuchung Cheng tcp_rearm_rto(sk); 81f19c29e3SYuchung Cheng 82f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 83f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 846a5dc9e5SEric Dumazet } 851da177e4SLinus Torvalds 86a4ecb15aSCui, Cheng /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one 87a4ecb15aSCui, Cheng * window scaling factor due to loss of precision. 881da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 891da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 901da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 911da177e4SLinus Torvalds * invalid. OK, let's make this for now: 921da177e4SLinus Torvalds */ 93cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 941da177e4SLinus Torvalds { 95cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 969e412ba7SIlpo Järvinen 97a4ecb15aSCui, Cheng if (!before(tcp_wnd_end(tp), tp->snd_nxt) || 98a4ecb15aSCui, Cheng (tp->rx_opt.wscale_ok && 99a4ecb15aSCui, Cheng ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) 1001da177e4SLinus Torvalds return tp->snd_nxt; 1011da177e4SLinus Torvalds else 10290840defSIlpo Järvinen return tcp_wnd_end(tp); 1031da177e4SLinus Torvalds } 1041da177e4SLinus Torvalds 1051da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1061da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1071da177e4SLinus Torvalds * 1081da177e4SLinus Torvalds * 1. It is independent of path mtu. 1091da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1101da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1111da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1121da177e4SLinus Torvalds * large MSS. 1131da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1141da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1151da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1161da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1171da177e4SLinus Torvalds * probably even Jumbo". 1181da177e4SLinus Torvalds */ 1191da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 122cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1231da177e4SLinus Torvalds int mss = tp->advmss; 1241da177e4SLinus Torvalds 1250dbaee3bSDavid S. Miller if (dst) { 1260dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1270dbaee3bSDavid S. Miller 1280dbaee3bSDavid S. Miller if (metric < mss) { 1290dbaee3bSDavid S. Miller mss = metric; 1301da177e4SLinus Torvalds tp->advmss = mss; 1311da177e4SLinus Torvalds } 1320dbaee3bSDavid S. Miller } 1331da177e4SLinus Torvalds 1341da177e4SLinus Torvalds return (__u16)mss; 1351da177e4SLinus Torvalds } 1361da177e4SLinus Torvalds 1371da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1386f021c62SEric Dumazet * This is the first part of cwnd validation mechanism. 1396f021c62SEric Dumazet */ 1406f021c62SEric Dumazet void tcp_cwnd_restart(struct sock *sk, s32 delta) 1411da177e4SLinus Torvalds { 142463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1436f021c62SEric Dumazet u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); 1441da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1451da177e4SLinus Torvalds 1466687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1471da177e4SLinus Torvalds 1486687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1491da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1501da177e4SLinus Torvalds 151463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1521da177e4SLinus Torvalds cwnd >>= 1; 1531da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 154c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1551da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1561da177e4SLinus Torvalds } 1571da177e4SLinus Torvalds 15867edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 15940efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 160cf533ea5SEric Dumazet struct sock *sk) 1611da177e4SLinus Torvalds { 162463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 163d635fbe2SEric Dumazet const u32 now = tcp_jiffies32; 1641da177e4SLinus Torvalds 16505c5a46dSNeal Cardwell if (tcp_packets_in_flight(tp) == 0) 16605c5a46dSNeal Cardwell tcp_ca_event(sk, CA_EVENT_TX_START); 16705c5a46dSNeal Cardwell 1681da177e4SLinus Torvalds tp->lsndtime = now; 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds /* If it is a reply for ato after last received 1711da177e4SLinus Torvalds * packet, enter pingpong mode. 1721da177e4SLinus Torvalds */ 1732251ae46SJon Maxwell if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 174463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1751da177e4SLinus Torvalds } 1761da177e4SLinus Torvalds 17767edfef7SAndi Kleen /* Account for an ACK we sent. */ 17840efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1791da177e4SLinus Torvalds { 180463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 181463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1821da177e4SLinus Torvalds } 1831da177e4SLinus Torvalds 18485f16525SYuchung Cheng 18585f16525SYuchung Cheng u32 tcp_default_init_rwnd(u32 mss) 18685f16525SYuchung Cheng { 18785f16525SYuchung Cheng /* Initial receive window should be twice of TCP_INIT_CWND to 1889ef71e0cSWeiping Pan * enable proper sending of new unsent data during fast recovery 18985f16525SYuchung Cheng * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a 19085f16525SYuchung Cheng * limit when mss is larger than 1460. 19185f16525SYuchung Cheng */ 19285f16525SYuchung Cheng u32 init_rwnd = TCP_INIT_CWND * 2; 19385f16525SYuchung Cheng 19485f16525SYuchung Cheng if (mss > 1460) 19585f16525SYuchung Cheng init_rwnd = max((1460 * init_rwnd) / mss, 2U); 19685f16525SYuchung Cheng return init_rwnd; 19785f16525SYuchung Cheng } 19885f16525SYuchung Cheng 1991da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2001da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2011da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2021da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2031da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2041da177e4SLinus Torvalds * This MUST be enforced by all callers. 2051da177e4SLinus Torvalds */ 2061da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 2071da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 20831d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 20931d12926Slaurent chavey __u32 init_rcv_wnd) 2101da177e4SLinus Torvalds { 2111da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2121da177e4SLinus Torvalds 2131da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2141da177e4SLinus Torvalds if (*window_clamp == 0) 215589c49cbSGao Feng (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); 2161da177e4SLinus Torvalds space = min(*window_clamp, space); 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2191da177e4SLinus Torvalds if (space > mss) 220589c49cbSGao Feng space = rounddown(space, mss); 2211da177e4SLinus Torvalds 2221da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22315d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22415d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 22515d99e02SRick Jones * we will truncate our initial window offering to 32K-1 22615d99e02SRick Jones * unless the remote has sent us a window scaling option, 22715d99e02SRick Jones * which we interpret as a sign the remote TCP is not 22815d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2291da177e4SLinus Torvalds */ 23015d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2311da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23215d99e02SRick Jones else 23315d99e02SRick Jones (*rcv_wnd) = space; 23415d99e02SRick Jones 2351da177e4SLinus Torvalds (*rcv_wscale) = 0; 2361da177e4SLinus Torvalds if (wscale_ok) { 237589c49cbSGao Feng /* Set window scaling on max possible window */ 238f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_tcp_rmem[2]); 239f626300aSSoheil Hassas Yeganeh space = max_t(u32, space, sysctl_rmem_max); 240316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 241589c49cbSGao Feng while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) { 2421da177e4SLinus Torvalds space >>= 1; 2431da177e4SLinus Torvalds (*rcv_wscale)++; 2441da177e4SLinus Torvalds } 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 24885f16525SYuchung Cheng if (!init_rcv_wnd) /* Use default unless specified otherwise */ 24985f16525SYuchung Cheng init_rcv_wnd = tcp_default_init_rwnd(mss); 250b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 254589c49cbSGao Feng (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); 2551da177e4SLinus Torvalds } 2564bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2571da177e4SLinus Torvalds 2581da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2591da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2601da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2611da177e4SLinus Torvalds * frame. 2621da177e4SLinus Torvalds */ 26340efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2641da177e4SLinus Torvalds { 2651da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2668e165e20SFlorian Westphal u32 old_win = tp->rcv_wnd; 2671da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2681da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2691da177e4SLinus Torvalds 2701da177e4SLinus Torvalds /* Never shrink the offered window */ 2711da177e4SLinus Torvalds if (new_win < cur_win) { 2721da177e4SLinus Torvalds /* Danger Will Robinson! 2731da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2741da177e4SLinus Torvalds * we will not be able to advertise a zero 2751da177e4SLinus Torvalds * window in time. --DaveM 2761da177e4SLinus Torvalds * 2771da177e4SLinus Torvalds * Relax Will Robinson. 2781da177e4SLinus Torvalds */ 2798e165e20SFlorian Westphal if (new_win == 0) 2808e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 2818e165e20SFlorian Westphal LINUX_MIB_TCPWANTZEROWINDOWADV); 282607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2831da177e4SLinus Torvalds } 2841da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2851da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2861da177e4SLinus Torvalds 2871da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2881da177e4SLinus Torvalds * scaled window. 2891da177e4SLinus Torvalds */ 29015d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2911da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2921da177e4SLinus Torvalds else 2931da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2941da177e4SLinus Torvalds 2951da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2961da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2971da177e4SLinus Torvalds 29831770e34SFlorian Westphal /* If we advertise zero window, disable fast path. */ 2998e165e20SFlorian Westphal if (new_win == 0) { 30031770e34SFlorian Westphal tp->pred_flags = 0; 3018e165e20SFlorian Westphal if (old_win) 3028e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), 3038e165e20SFlorian Westphal LINUX_MIB_TCPTOZEROWINDOWADV); 3048e165e20SFlorian Westphal } else if (old_win == 0) { 3058e165e20SFlorian Westphal NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); 3068e165e20SFlorian Westphal } 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds return new_win; 3091da177e4SLinus Torvalds } 3101da177e4SLinus Torvalds 31167edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 312735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 313bdf1ee5dSIlpo Järvinen { 31430e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 31530e502a3SDaniel Borkmann 3164de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 317bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3184de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 31991b5b21cSLawrence Brakmo else if (tcp_ca_needs_ecn(sk) || 32091b5b21cSLawrence Brakmo tcp_bpf_ca_needs_ecn(sk)) 32130e502a3SDaniel Borkmann INET_ECN_xmit(sk); 322bdf1ee5dSIlpo Järvinen } 323bdf1ee5dSIlpo Järvinen 32467edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 325735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 326bdf1ee5dSIlpo Järvinen { 327bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 32891b5b21cSLawrence Brakmo bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); 329f7b3bec6SFlorian Westphal bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || 33091b5b21cSLawrence Brakmo tcp_ca_needs_ecn(sk) || bpf_needs_ecn; 331f7b3bec6SFlorian Westphal 332f7b3bec6SFlorian Westphal if (!use_ecn) { 333f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 334f7b3bec6SFlorian Westphal 335f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 336f7b3bec6SFlorian Westphal use_ecn = true; 337f7b3bec6SFlorian Westphal } 338bdf1ee5dSIlpo Järvinen 339bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 340f7b3bec6SFlorian Westphal 341f7b3bec6SFlorian Westphal if (use_ecn) { 3424de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 343bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 34491b5b21cSLawrence Brakmo if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) 34530e502a3SDaniel Borkmann INET_ECN_xmit(sk); 346bdf1ee5dSIlpo Järvinen } 347bdf1ee5dSIlpo Järvinen } 348bdf1ee5dSIlpo Järvinen 34949213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 35049213555SDaniel Borkmann { 35149213555SDaniel Borkmann if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) 35249213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 35349213555SDaniel Borkmann * SYN ACK is ultimatively being received. 35449213555SDaniel Borkmann */ 35549213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 35649213555SDaniel Borkmann } 35749213555SDaniel Borkmann 358735d3831SFlorian Westphal static void 3596ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 360bdf1ee5dSIlpo Järvinen { 3616ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 362bdf1ee5dSIlpo Järvinen th->ece = 1; 363bdf1ee5dSIlpo Järvinen } 364bdf1ee5dSIlpo Järvinen 36567edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 36667edfef7SAndi Kleen * be sent. 36767edfef7SAndi Kleen */ 368735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 369ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 370bdf1ee5dSIlpo Järvinen { 371bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 372bdf1ee5dSIlpo Järvinen 373bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 374bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 375bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 376bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 377bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 378bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 379bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 380ea1627c2SEric Dumazet th->cwr = 1; 381bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 382bdf1ee5dSIlpo Järvinen } 38330e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 384bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 385bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 386bdf1ee5dSIlpo Järvinen } 387bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 388ea1627c2SEric Dumazet th->ece = 1; 389bdf1ee5dSIlpo Järvinen } 390bdf1ee5dSIlpo Järvinen } 391bdf1ee5dSIlpo Järvinen 392e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 393e870a8efSIlpo Järvinen * auto increment end seqno. 394e870a8efSIlpo Järvinen */ 395e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 396e870a8efSIlpo Järvinen { 3972e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 398e870a8efSIlpo Järvinen skb->csum = 0; 399e870a8efSIlpo Järvinen 4004de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 401e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 402e870a8efSIlpo Järvinen 403cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 404e870a8efSIlpo Järvinen 405e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 406a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 407e870a8efSIlpo Järvinen seq++; 408e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 409e870a8efSIlpo Järvinen } 410e870a8efSIlpo Järvinen 411a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 41233f5f57eSIlpo Järvinen { 41333f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41433f5f57eSIlpo Järvinen } 41533f5f57eSIlpo Järvinen 41633ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 41733ad798cSAdam Langley #define OPTION_TS (1 << 1) 41833ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 41989e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 4202100c8d2SYuchung Cheng #define OPTION_FAST_OPEN_COOKIE (1 << 8) 42133ad798cSAdam Langley 42233ad798cSAdam Langley struct tcp_out_options { 4232100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4242100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 42533ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 42633ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 427bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 428bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4292100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4302100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 43133ad798cSAdam Langley }; 43233ad798cSAdam Langley 43367edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 43467edfef7SAndi Kleen * 43567edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 436fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 437fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 4388e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 439fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 440fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 441fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 442fd6149d3SIlpo Järvinen * 443fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 444fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 445fd6149d3SIlpo Järvinen */ 44633ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 447bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 448bd0388aeSWilliam Allen Simpson { 4492100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 450bd0388aeSWilliam Allen Simpson 451bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 4521a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 4531a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 454bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 455bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 45633ad798cSAdam Langley ptr += 4; 45733ad798cSAdam Langley } 45833ad798cSAdam Langley 459fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 460fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 461fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 462fd6149d3SIlpo Järvinen opts->mss); 463fd6149d3SIlpo Järvinen } 464fd6149d3SIlpo Järvinen 465bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 466bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 46733ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 46833ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 46933ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 47033ad798cSAdam Langley TCPOLEN_TIMESTAMP); 471bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 47233ad798cSAdam Langley } else { 473496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 47440efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 47540efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 47640efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 47740efc6faSStephen Hemminger } 47833ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 47933ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 48033ad798cSAdam Langley } 48133ad798cSAdam Langley 482bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 48333ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 48433ad798cSAdam Langley (TCPOPT_NOP << 16) | 48533ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 48633ad798cSAdam Langley TCPOLEN_SACK_PERM); 48733ad798cSAdam Langley } 48833ad798cSAdam Langley 489bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 49033ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 49133ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 49233ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 49333ad798cSAdam Langley opts->ws); 49433ad798cSAdam Langley } 49533ad798cSAdam Langley 49633ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 49733ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 49833ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 49940efc6faSStephen Hemminger int this_sack; 50040efc6faSStephen Hemminger 50140efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 50240efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 50340efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 50433ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 50540efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5062de979bdSStephen Hemminger 50733ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 50833ad798cSAdam Langley ++this_sack) { 50940efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 51040efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 51140efc6faSStephen Hemminger } 5122de979bdSStephen Hemminger 51340efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 51440efc6faSStephen Hemminger } 5152100c8d2SYuchung Cheng 5162100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 5172100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 5187f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 5197f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 5202100c8d2SYuchung Cheng 5217f9b838bSDaniel Lee if (foc->exp) { 5227f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 5237f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 5242100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 5257f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 5267f9b838bSDaniel Lee } else { 5277f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 5287f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 5297f9b838bSDaniel Lee *p++ = len; 5302100c8d2SYuchung Cheng } 5317f9b838bSDaniel Lee 5327f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 5337f9b838bSDaniel Lee if ((len & 3) == 2) { 5347f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 5357f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 5367f9b838bSDaniel Lee } 5377f9b838bSDaniel Lee ptr += (len + 3) >> 2; 5382100c8d2SYuchung Cheng } 53940efc6faSStephen Hemminger } 54040efc6faSStephen Hemminger 54167edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 54267edfef7SAndi Kleen * network wire format yet. 54367edfef7SAndi Kleen */ 54495c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 54533ad798cSAdam Langley struct tcp_out_options *opts, 546cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 547cf533ea5SEric Dumazet { 54833ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 54995c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 550783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 55133ad798cSAdam Langley 552cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 55333ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 55433ad798cSAdam Langley if (*md5) { 55533ad798cSAdam Langley opts->options |= OPTION_MD5; 556bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 557cfb6eeb4SYOSHIFUJI Hideaki } 55833ad798cSAdam Langley #else 55933ad798cSAdam Langley *md5 = NULL; 560cfb6eeb4SYOSHIFUJI Hideaki #endif 56133ad798cSAdam Langley 56233ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 56333ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 56433ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 56533ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 56633ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 56733ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 56833ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 56933ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 57033ad798cSAdam Langley * going out. */ 57133ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 572bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 57333ad798cSAdam Langley 5745d2ed052SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) { 57533ad798cSAdam Langley opts->options |= OPTION_TS; 5767faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 57733ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 578bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 57933ad798cSAdam Langley } 5809bb37ef0SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) { 58133ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 58289e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 583bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 58433ad798cSAdam Langley } 585f9301034SEric Dumazet if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) { 58633ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 587b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 588bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 58933ad798cSAdam Langley } 59033ad798cSAdam Langley 591783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 5922646c831SDaniel Lee u32 need = fastopen->cookie.len; 5932646c831SDaniel Lee 5942646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 5952646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 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; 6022646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 603783237e8SYuchung Cheng } 604783237e8SYuchung Cheng } 605bd0388aeSWilliam Allen Simpson 606bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 60733ad798cSAdam Langley } 60833ad798cSAdam Langley 60967edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 61037bfbddaSEric Dumazet static unsigned int tcp_synack_options(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; 64495a22caeSFlorian Westphal opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; 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 } 6537f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 6547f9b838bSDaniel Lee u32 need = foc->len; 6557f9b838bSDaniel Lee 6567f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 6577f9b838bSDaniel 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 | 738f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 739f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 740f9616c35SEric Dumazet 741f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 7423a91d29fSKoichiro Den tp->snd_cwnd > tcp_packets_in_flight(tp)) { 7433a91d29fSKoichiro Den tcp_mstamp_refresh(tp); 744f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 7453a91d29fSKoichiro Den } 746f9616c35SEric Dumazet 747f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 748bf06200eSJohn Ogness 0, GFP_ATOMIC); 7496f458dfbSEric Dumazet } 750f9616c35SEric Dumazet } 75146d3ceabSEric Dumazet /* 7528e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 75346d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 7548e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 75546d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 75646d3ceabSEric Dumazet */ 75746d3ceabSEric Dumazet static void tcp_tasklet_func(unsigned long data) 75846d3ceabSEric Dumazet { 75946d3ceabSEric Dumazet struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; 76046d3ceabSEric Dumazet LIST_HEAD(list); 76146d3ceabSEric Dumazet unsigned long flags; 76246d3ceabSEric Dumazet struct list_head *q, *n; 76346d3ceabSEric Dumazet struct tcp_sock *tp; 76446d3ceabSEric Dumazet struct sock *sk; 76546d3ceabSEric Dumazet 76646d3ceabSEric Dumazet local_irq_save(flags); 76746d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 76846d3ceabSEric Dumazet local_irq_restore(flags); 76946d3ceabSEric Dumazet 77046d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 77146d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 77246d3ceabSEric Dumazet list_del(&tp->tsq_node); 77346d3ceabSEric Dumazet 77446d3ceabSEric Dumazet sk = (struct sock *)tp; 7750a9648f1SEric Dumazet smp_mb__before_atomic(); 7767aa5470cSEric Dumazet clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); 7777aa5470cSEric Dumazet 778b223feb9SEric Dumazet if (!sk->sk_lock.owned && 7797aa5470cSEric Dumazet test_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) { 78046d3ceabSEric Dumazet bh_lock_sock(sk); 78146d3ceabSEric Dumazet if (!sock_owned_by_user(sk)) { 7827aa5470cSEric Dumazet clear_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags); 7836f458dfbSEric Dumazet tcp_tsq_handler(sk); 78446d3ceabSEric Dumazet } 78546d3ceabSEric Dumazet bh_unlock_sock(sk); 786b223feb9SEric Dumazet } 78746d3ceabSEric Dumazet 78846d3ceabSEric Dumazet sk_free(sk); 78946d3ceabSEric Dumazet } 79046d3ceabSEric Dumazet } 79146d3ceabSEric Dumazet 79240fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 79340fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 79440fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 79540fc3423SEric Dumazet TCPF_MTU_REDUCED_DEFERRED) 79646d3ceabSEric Dumazet /** 79746d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 79846d3ceabSEric Dumazet * @sk: socket 79946d3ceabSEric Dumazet * 80046d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 80146d3ceabSEric Dumazet * actions before socket release. 80246d3ceabSEric Dumazet */ 80346d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 80446d3ceabSEric Dumazet { 8056f458dfbSEric Dumazet unsigned long flags, nflags; 80646d3ceabSEric Dumazet 8076f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 8086f458dfbSEric Dumazet do { 8097aa5470cSEric Dumazet flags = sk->sk_tsq_flags; 8106f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 8116f458dfbSEric Dumazet return; 8126f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 8137aa5470cSEric Dumazet } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); 8146f458dfbSEric Dumazet 81540fc3423SEric Dumazet if (flags & TCPF_TSQ_DEFERRED) 8166f458dfbSEric Dumazet tcp_tsq_handler(sk); 8176f458dfbSEric Dumazet 818c3f9b018SEric Dumazet /* Here begins the tricky part : 819c3f9b018SEric Dumazet * We are called from release_sock() with : 820c3f9b018SEric Dumazet * 1) BH disabled 821c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 822c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 823c3f9b018SEric Dumazet * 824c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 825c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 826c3f9b018SEric Dumazet */ 827c3f9b018SEric Dumazet sock_release_ownership(sk); 828c3f9b018SEric Dumazet 82940fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 8306f458dfbSEric Dumazet tcp_write_timer_handler(sk); 831144d56e9SEric Dumazet __sock_put(sk); 832144d56e9SEric Dumazet } 83340fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 8346f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 835144d56e9SEric Dumazet __sock_put(sk); 836144d56e9SEric Dumazet } 83740fc3423SEric Dumazet if (flags & TCPF_MTU_REDUCED_DEFERRED) { 8384fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 839144d56e9SEric Dumazet __sock_put(sk); 840144d56e9SEric Dumazet } 84146d3ceabSEric Dumazet } 84246d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 84346d3ceabSEric Dumazet 84446d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 84546d3ceabSEric Dumazet { 84646d3ceabSEric Dumazet int i; 84746d3ceabSEric Dumazet 84846d3ceabSEric Dumazet for_each_possible_cpu(i) { 84946d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 85046d3ceabSEric Dumazet 85146d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 85246d3ceabSEric Dumazet tasklet_init(&tsq->tasklet, 85346d3ceabSEric Dumazet tcp_tasklet_func, 85446d3ceabSEric Dumazet (unsigned long)tsq); 85546d3ceabSEric Dumazet } 85646d3ceabSEric Dumazet } 85746d3ceabSEric Dumazet 85846d3ceabSEric Dumazet /* 85946d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 8608e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 86146d3ceabSEric Dumazet * hold qdisc lock. 86246d3ceabSEric Dumazet */ 863d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 86446d3ceabSEric Dumazet { 86546d3ceabSEric Dumazet struct sock *sk = skb->sk; 86646d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 867408f0a6cSEric Dumazet unsigned long flags, nval, oval; 8689b462d02SEric Dumazet 8699b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 8709b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 8719b462d02SEric Dumazet */ 87214afee4bSReshetova, Elena WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); 8739b462d02SEric Dumazet 8749b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 8759b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 8769b462d02SEric Dumazet * This gives : 8779b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 8789b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 8799b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 8809b462d02SEric Dumazet */ 88114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 8829b462d02SEric Dumazet goto out; 88346d3ceabSEric Dumazet 8847aa5470cSEric Dumazet for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { 88546d3ceabSEric Dumazet struct tsq_tasklet *tsq; 886a9b204d1SEric Dumazet bool empty; 88746d3ceabSEric Dumazet 888408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 889408f0a6cSEric Dumazet goto out; 890408f0a6cSEric Dumazet 891b223feb9SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED; 8927aa5470cSEric Dumazet nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); 893408f0a6cSEric Dumazet if (nval != oval) 894408f0a6cSEric Dumazet continue; 895408f0a6cSEric Dumazet 89646d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 89746d3ceabSEric Dumazet local_irq_save(flags); 898903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 899a9b204d1SEric Dumazet empty = list_empty(&tsq->head); 90046d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 901a9b204d1SEric Dumazet if (empty) 90246d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 90346d3ceabSEric Dumazet local_irq_restore(flags); 9049b462d02SEric Dumazet return; 90546d3ceabSEric Dumazet } 9069b462d02SEric Dumazet out: 9079b462d02SEric Dumazet sk_free(sk); 90846d3ceabSEric Dumazet } 90946d3ceabSEric Dumazet 910218af599SEric Dumazet /* Note: Called under hard irq. 911218af599SEric Dumazet * We can not call TCP stack right away. 912218af599SEric Dumazet */ 913218af599SEric Dumazet enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 914218af599SEric Dumazet { 915218af599SEric Dumazet struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); 916218af599SEric Dumazet struct sock *sk = (struct sock *)tp; 917218af599SEric Dumazet unsigned long nval, oval; 918218af599SEric Dumazet 919218af599SEric Dumazet for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { 920218af599SEric Dumazet struct tsq_tasklet *tsq; 921218af599SEric Dumazet bool empty; 922218af599SEric Dumazet 923218af599SEric Dumazet if (oval & TSQF_QUEUED) 924218af599SEric Dumazet break; 925218af599SEric Dumazet 926218af599SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED; 927218af599SEric Dumazet nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); 928218af599SEric Dumazet if (nval != oval) 929218af599SEric Dumazet continue; 930218af599SEric Dumazet 93114afee4bSReshetova, Elena if (!refcount_inc_not_zero(&sk->sk_wmem_alloc)) 932218af599SEric Dumazet break; 933218af599SEric Dumazet /* queue this socket to tasklet queue */ 934218af599SEric Dumazet tsq = this_cpu_ptr(&tsq_tasklet); 935218af599SEric Dumazet empty = list_empty(&tsq->head); 936218af599SEric Dumazet list_add(&tp->tsq_node, &tsq->head); 937218af599SEric Dumazet if (empty) 938218af599SEric Dumazet tasklet_schedule(&tsq->tasklet); 939218af599SEric Dumazet break; 940218af599SEric Dumazet } 941218af599SEric Dumazet return HRTIMER_NORESTART; 942218af599SEric Dumazet } 943218af599SEric Dumazet 944218af599SEric Dumazet /* BBR congestion control needs pacing. 945218af599SEric Dumazet * Same remark for SO_MAX_PACING_RATE. 946218af599SEric Dumazet * sch_fq packet scheduler is efficiently handling pacing, 947218af599SEric Dumazet * but is not always installed/used. 948218af599SEric Dumazet * Return true if TCP stack should pace packets itself. 949218af599SEric Dumazet */ 950218af599SEric Dumazet static bool tcp_needs_internal_pacing(const struct sock *sk) 951218af599SEric Dumazet { 952218af599SEric Dumazet return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED; 953218af599SEric Dumazet } 954218af599SEric Dumazet 955218af599SEric Dumazet static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) 956218af599SEric Dumazet { 957218af599SEric Dumazet u64 len_ns; 958218af599SEric Dumazet u32 rate; 959218af599SEric Dumazet 960218af599SEric Dumazet if (!tcp_needs_internal_pacing(sk)) 961218af599SEric Dumazet return; 962218af599SEric Dumazet rate = sk->sk_pacing_rate; 963218af599SEric Dumazet if (!rate || rate == ~0U) 964218af599SEric Dumazet return; 965218af599SEric Dumazet 966218af599SEric Dumazet /* Should account for header sizes as sch_fq does, 967218af599SEric Dumazet * but lets make things simple. 968218af599SEric Dumazet */ 969218af599SEric Dumazet len_ns = (u64)skb->len * NSEC_PER_SEC; 970218af599SEric Dumazet do_div(len_ns, rate); 971218af599SEric Dumazet hrtimer_start(&tcp_sk(sk)->pacing_timer, 972218af599SEric Dumazet ktime_add_ns(ktime_get(), len_ns), 973218af599SEric Dumazet HRTIMER_MODE_ABS_PINNED); 974218af599SEric Dumazet } 975218af599SEric Dumazet 9761da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 9771da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 9781da177e4SLinus Torvalds * transmission and possible later retransmissions. 9791da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 9801da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 9811da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 9821da177e4SLinus Torvalds * device. 9831da177e4SLinus Torvalds * 9841da177e4SLinus Torvalds * We are working here with either a clone of the original 9851da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 9861da177e4SLinus Torvalds */ 987056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 988056834d9SIlpo Järvinen gfp_t gfp_mask) 9891da177e4SLinus Torvalds { 9906687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 991dfb4b9dcSDavid S. Miller struct inet_sock *inet; 992dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 993dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 99433ad798cSAdam Langley struct tcp_out_options opts; 99595c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 9968c72c65bSEric Dumazet struct sk_buff *oskb = NULL; 997cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 9981da177e4SLinus Torvalds struct tcphdr *th; 9991da177e4SLinus Torvalds int err; 10001da177e4SLinus Torvalds 1001dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 10026f094b9eSLawrence Brakmo tp = tcp_sk(sk); 1003dfb4b9dcSDavid S. Miller 1004ccdbb6e9SEric Dumazet if (clone_it) { 10056f094b9eSLawrence Brakmo TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq 10066f094b9eSLawrence Brakmo - tp->snd_una; 10078c72c65bSEric Dumazet oskb = skb; 1008dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 1009dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 1010dfb4b9dcSDavid S. Miller else 1011dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 1012dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 1013dfb4b9dcSDavid S. Miller return -ENOBUFS; 1014dfb4b9dcSDavid S. Miller } 10158c72c65bSEric Dumazet skb->skb_mstamp = tp->tcp_mstamp; 1016dfb4b9dcSDavid S. Miller 1017dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 1018dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 101933ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 10201da177e4SLinus Torvalds 10214de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 102233ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 102333ad798cSAdam Langley else 102433ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 102533ad798cSAdam Langley &md5); 102633ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 10271da177e4SLinus Torvalds 1028547669d4SEric Dumazet /* if no packet is in qdisc/device queue, then allow XPS to select 1029b2532eb9SEric Dumazet * another queue. We can be called from tcp_tsq_handler() 1030b2532eb9SEric Dumazet * which holds one reference to sk_wmem_alloc. 1031b2532eb9SEric Dumazet * 1032b2532eb9SEric Dumazet * TODO: Ideally, in-flight pure ACK packets should not matter here. 1033b2532eb9SEric Dumazet * One way to get this would be to set skb->truesize = 2 on them. 1034547669d4SEric Dumazet */ 1035b2532eb9SEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); 10361da177e4SLinus Torvalds 103738ab52e8SEric Dumazet /* If we had to use memory reserve to allocate this skb, 103838ab52e8SEric Dumazet * this might cause drops if packet is looped back : 103938ab52e8SEric Dumazet * Other socket might not have SOCK_MEMALLOC. 104038ab52e8SEric Dumazet * Packets not looped back do not care about pfmemalloc. 104138ab52e8SEric Dumazet */ 104238ab52e8SEric Dumazet skb->pfmemalloc = 0; 104338ab52e8SEric Dumazet 1044aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 1045aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 104646d3ceabSEric Dumazet 104746d3ceabSEric Dumazet skb_orphan(skb); 104846d3ceabSEric Dumazet skb->sk = sk; 10491d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 1050b73c3d0eSTom Herbert skb_set_hash_from_sk(skb, sk); 105114afee4bSReshetova, Elena refcount_add(skb->truesize, &sk->sk_wmem_alloc); 10521da177e4SLinus Torvalds 1053c3a2e837SJulian Anastasov skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); 1054c3a2e837SJulian Anastasov 10551da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 1056ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 1057c720c7e8SEric Dumazet th->source = inet->inet_sport; 1058c720c7e8SEric Dumazet th->dest = inet->inet_dport; 10591da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 10601da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 1061df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 10624de075e0SEric Dumazet tcb->tcp_flags); 1063dfb4b9dcSDavid S. Miller 10641da177e4SLinus Torvalds th->check = 0; 10651da177e4SLinus Torvalds th->urg_ptr = 0; 10661da177e4SLinus Torvalds 106733f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 10687691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 10697691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 10701da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 10711da177e4SLinus Torvalds th->urg = 1; 10727691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 10730eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 10747691367dSHerbert Xu th->urg = 1; 10757691367dSHerbert Xu } 10761da177e4SLinus Torvalds } 10771da177e4SLinus Torvalds 1078bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 107951466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 1080ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1081ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1082ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1083ea1627c2SEric Dumazet } else { 1084ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1085ea1627c2SEric Dumazet * is never scaled. 1086ea1627c2SEric Dumazet */ 1087ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1088ea1627c2SEric Dumazet } 1089cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1090cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1091cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1092a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 1093bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 109439f8e58eSEric Dumazet md5, sk, skb); 1095cfb6eeb4SYOSHIFUJI Hideaki } 1096cfb6eeb4SYOSHIFUJI Hideaki #endif 1097cfb6eeb4SYOSHIFUJI Hideaki 1098bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 10991da177e4SLinus Torvalds 11004de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 1101fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 11021da177e4SLinus Torvalds 1103a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1104cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1105a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1106218af599SEric Dumazet tcp_internal_pacing(sk, skb); 1107a44d6eacSMartin KaFai Lau } 11081da177e4SLinus Torvalds 1109bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1110aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1111aa2ea058STom Herbert tcp_skb_pcount(skb)); 11121da177e4SLinus Torvalds 11132efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 1114f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1115cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1116f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1117cd7d8498SEric Dumazet 11187faee5c0SEric Dumazet /* Our usage of tstamp should remain private */ 11192456e855SThomas Gleixner skb->tstamp = 0; 1120971f10ecSEric Dumazet 1121971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1122971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1123971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1124971f10ecSEric Dumazet 1125b0270e91SEric Dumazet err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 11267faee5c0SEric Dumazet 11278c72c65bSEric Dumazet if (unlikely(err > 0)) { 11285ee2c941SChristoph Paasch tcp_enter_cwr(sk); 11298c72c65bSEric Dumazet err = net_xmit_eval(err); 11308c72c65bSEric Dumazet } 1131fc225799SEric Dumazet if (!err && oskb) { 11328c72c65bSEric Dumazet oskb->skb_mstamp = tp->tcp_mstamp; 1133fc225799SEric Dumazet tcp_rate_skb_sent(sk, oskb); 1134fc225799SEric Dumazet } 11358c72c65bSEric Dumazet return err; 11361da177e4SLinus Torvalds } 11371da177e4SLinus Torvalds 113867edfef7SAndi Kleen /* This routine just queues the buffer for sending. 11391da177e4SLinus Torvalds * 11401da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 11411da177e4SLinus Torvalds * otherwise socket can stall. 11421da177e4SLinus Torvalds */ 11431da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 11441da177e4SLinus Torvalds { 11451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11461da177e4SLinus Torvalds 11471da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 11481da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 1149f4a775d1SEric Dumazet __skb_header_release(skb); 1150fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 11513ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 11523ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 11531da177e4SLinus Torvalds } 11541da177e4SLinus Torvalds 115567edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 11565bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1157f6302d1dSDavid S. Miller { 11588f26fb1cSEric Dumazet if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { 1159f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1160f6302d1dSDavid S. Miller * non-TSO case. 1161f6302d1dSDavid S. Miller */ 1162cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1163f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1164f6302d1dSDavid S. Miller } else { 1165cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1166f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 11671da177e4SLinus Torvalds } 11681da177e4SLinus Torvalds } 11691da177e4SLinus Torvalds 117091fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 117168f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 117291fed7a1SIlpo Järvinen */ 1173cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 117491fed7a1SIlpo Järvinen int decr) 117591fed7a1SIlpo Järvinen { 1176a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1177a47e5a98SIlpo Järvinen 1178dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 117991fed7a1SIlpo Järvinen return; 118091fed7a1SIlpo Järvinen 11816859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 118291fed7a1SIlpo Järvinen tp->fackets_out -= decr; 118391fed7a1SIlpo Järvinen } 118491fed7a1SIlpo Järvinen 1185797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1186797108d1SIlpo Järvinen * tweaks to fix counters 1187797108d1SIlpo Järvinen */ 1188cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1189797108d1SIlpo Järvinen { 1190797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1191797108d1SIlpo Järvinen 1192797108d1SIlpo Järvinen tp->packets_out -= decr; 1193797108d1SIlpo Järvinen 1194797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1195797108d1SIlpo Järvinen tp->sacked_out -= decr; 1196797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1197797108d1SIlpo Järvinen tp->retrans_out -= decr; 1198797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1199797108d1SIlpo Järvinen tp->lost_out -= decr; 1200797108d1SIlpo Järvinen 1201797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1202797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1203797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1204797108d1SIlpo Järvinen 1205797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 1206797108d1SIlpo Järvinen 1207797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1208797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 120952cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 1210797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1211797108d1SIlpo Järvinen 1212797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1213797108d1SIlpo Järvinen } 1214797108d1SIlpo Järvinen 12150a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 12160a2cf20cSSoheil Hassas Yeganeh { 12170a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 12180a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 12190a2cf20cSSoheil Hassas Yeganeh } 12200a2cf20cSSoheil Hassas Yeganeh 1221490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1222490cc7d0SWillem de Bruijn { 1223490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1224490cc7d0SWillem de Bruijn 12250a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1226490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1227490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1228490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1229490cc7d0SWillem de Bruijn 1230490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1231490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1232490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1233b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1234b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1235490cc7d0SWillem de Bruijn } 1236490cc7d0SWillem de Bruijn } 1237490cc7d0SWillem de Bruijn 1238a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1239a166140eSMartin KaFai Lau { 1240a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1241a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1242a166140eSMartin KaFai Lau } 1243a166140eSMartin KaFai Lau 12441da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 12451da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 12461da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 12471da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 12481da177e4SLinus Torvalds */ 1249056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 12506cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 12511da177e4SLinus Torvalds { 12521da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12531da177e4SLinus Torvalds struct sk_buff *buff; 12546475be16SDavid S. Miller int nsize, old_factor; 1255b60b49eaSHerbert Xu int nlen; 12569ce01461SIlpo Järvinen u8 flags; 12571da177e4SLinus Torvalds 12582fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 12592fceec13SIlpo Järvinen return -EINVAL; 12606a438bbeSStephen Hemminger 12611da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 12621da177e4SLinus Torvalds if (nsize < 0) 12631da177e4SLinus Torvalds nsize = 0; 12641da177e4SLinus Torvalds 12656cc55e09SOctavian Purdila if (skb_unclone(skb, gfp)) 12661da177e4SLinus Torvalds return -ENOMEM; 12671da177e4SLinus Torvalds 12681da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 1269eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, nsize, gfp, true); 127051456b29SIan Morris if (!buff) 12711da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1272ef5cb973SHerbert Xu 12733ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 12743ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1275b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1276b60b49eaSHerbert Xu buff->truesize += nlen; 1277b60b49eaSHerbert Xu skb->truesize -= nlen; 12781da177e4SLinus Torvalds 12791da177e4SLinus Torvalds /* Correct the sequence numbers. */ 12801da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 12811da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 12821da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 12831da177e4SLinus Torvalds 12841da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 12854de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 12864de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 12874de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1288e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1289a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 12901da177e4SLinus Torvalds 129184fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 12921da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1293056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1294056834d9SIlpo Järvinen skb_put(buff, nsize), 12951da177e4SLinus Torvalds nsize, 0); 12961da177e4SLinus Torvalds 12971da177e4SLinus Torvalds skb_trim(skb, len); 12981da177e4SLinus Torvalds 12991da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 13001da177e4SLinus Torvalds } else { 130184fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 13021da177e4SLinus Torvalds skb_split(skb, buff, len); 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds 13051da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 13061da177e4SLinus Torvalds 1307a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 1308490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 13091da177e4SLinus Torvalds 13106475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 13116475be16SDavid S. Miller 13121da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 13135bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 13145bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 13151da177e4SLinus Torvalds 1316b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1317b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1318b9f64820SYuchung Cheng 13196475be16SDavid S. Miller /* If this packet has been sent out already, we must 13206475be16SDavid S. Miller * adjust the various packet counters. 13216475be16SDavid S. Miller */ 1322cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 13236475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 13246475be16SDavid S. Miller tcp_skb_pcount(buff); 13251da177e4SLinus Torvalds 1326797108d1SIlpo Järvinen if (diff) 1327797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 13281da177e4SLinus Torvalds } 13291da177e4SLinus Torvalds 13301da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1331f4a775d1SEric Dumazet __skb_header_release(buff); 1332fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds return 0; 13351da177e4SLinus Torvalds } 13361da177e4SLinus Torvalds 1337f4d01666SEric Dumazet /* This is similar to __pskb_pull_tail(). The difference is that pulled 1338f4d01666SEric Dumazet * data is not copied, but immediately discarded. 13391da177e4SLinus Torvalds */ 13407162fb24SEric Dumazet static int __pskb_trim_head(struct sk_buff *skb, int len) 13411da177e4SLinus Torvalds { 13427b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 13431da177e4SLinus Torvalds int i, k, eat; 13441da177e4SLinus Torvalds 13454fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 13464fa48bf3SEric Dumazet if (eat) { 13474fa48bf3SEric Dumazet __skb_pull(skb, eat); 13484fa48bf3SEric Dumazet len -= eat; 13494fa48bf3SEric Dumazet if (!len) 13507162fb24SEric Dumazet return 0; 13514fa48bf3SEric Dumazet } 13521da177e4SLinus Torvalds eat = len; 13531da177e4SLinus Torvalds k = 0; 13547b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 13557b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 13567b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 13579e903e08SEric Dumazet 13589e903e08SEric Dumazet if (size <= eat) { 1359aff65da0SIan Campbell skb_frag_unref(skb, i); 13609e903e08SEric Dumazet eat -= size; 13611da177e4SLinus Torvalds } else { 13627b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 13631da177e4SLinus Torvalds if (eat) { 13647b7fc97aSEric Dumazet shinfo->frags[k].page_offset += eat; 13657b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 13661da177e4SLinus Torvalds eat = 0; 13671da177e4SLinus Torvalds } 13681da177e4SLinus Torvalds k++; 13691da177e4SLinus Torvalds } 13701da177e4SLinus Torvalds } 13717b7fc97aSEric Dumazet shinfo->nr_frags = k; 13721da177e4SLinus Torvalds 13731da177e4SLinus Torvalds skb->data_len -= len; 13741da177e4SLinus Torvalds skb->len = skb->data_len; 13757162fb24SEric Dumazet return len; 13761da177e4SLinus Torvalds } 13771da177e4SLinus Torvalds 137867edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 13791da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 13801da177e4SLinus Torvalds { 13817162fb24SEric Dumazet u32 delta_truesize; 13827162fb24SEric Dumazet 138314bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC)) 13841da177e4SLinus Torvalds return -ENOMEM; 13851da177e4SLinus Torvalds 13867162fb24SEric Dumazet delta_truesize = __pskb_trim_head(skb, len); 13871da177e4SLinus Torvalds 13881da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 138984fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 13901da177e4SLinus Torvalds 13917162fb24SEric Dumazet if (delta_truesize) { 13927162fb24SEric Dumazet skb->truesize -= delta_truesize; 13937162fb24SEric Dumazet sk->sk_wmem_queued -= delta_truesize; 13947162fb24SEric Dumazet sk_mem_uncharge(sk, delta_truesize); 13951da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 13967162fb24SEric Dumazet } 13971da177e4SLinus Torvalds 13985b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 13991da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 14005bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 14011da177e4SLinus Torvalds 14021da177e4SLinus Torvalds return 0; 14031da177e4SLinus Torvalds } 14041da177e4SLinus Torvalds 14051b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 14061b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 14075d424d5aSJohn Heffner { 1408cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1409cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 14105d424d5aSJohn Heffner int mss_now; 14115d424d5aSJohn Heffner 14125d424d5aSJohn Heffner /* Calculate base mss without TCP options: 14135d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 14145d424d5aSJohn Heffner */ 14155d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 14165d424d5aSJohn Heffner 141767469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 141867469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 141967469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 142067469601SEric Dumazet 142167469601SEric Dumazet if (dst && dst_allfrag(dst)) 142267469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 142367469601SEric Dumazet } 142467469601SEric Dumazet 14255d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 14265d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 14275d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 14285d424d5aSJohn Heffner 14295d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 14305d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 14315d424d5aSJohn Heffner 14325d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 14335d424d5aSJohn Heffner if (mss_now < 48) 14345d424d5aSJohn Heffner mss_now = 48; 14355d424d5aSJohn Heffner return mss_now; 14365d424d5aSJohn Heffner } 14375d424d5aSJohn Heffner 14381b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 14391b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 14401b63edd6SYuchung Cheng { 14411b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 14421b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 14431b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 14441b63edd6SYuchung Cheng } 14451b63edd6SYuchung Cheng 14465d424d5aSJohn Heffner /* Inverse of above */ 144767469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 14485d424d5aSJohn Heffner { 1449cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1450cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 14515d424d5aSJohn Heffner int mtu; 14525d424d5aSJohn Heffner 14535d424d5aSJohn Heffner mtu = mss + 14545d424d5aSJohn Heffner tp->tcp_header_len + 14555d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 14565d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 14575d424d5aSJohn Heffner 145867469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 145967469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 146067469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 146167469601SEric Dumazet 146267469601SEric Dumazet if (dst && dst_allfrag(dst)) 146367469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 146467469601SEric Dumazet } 14655d424d5aSJohn Heffner return mtu; 14665d424d5aSJohn Heffner } 1467556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 14685d424d5aSJohn Heffner 146967edfef7SAndi Kleen /* MTU probing init per socket */ 14705d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 14715d424d5aSJohn Heffner { 14725d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 14735d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1474b0f9ca53SFan Du struct net *net = sock_net(sk); 14755d424d5aSJohn Heffner 1476b0f9ca53SFan Du icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; 14775d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 14785d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 1479b0f9ca53SFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); 14805d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 148105cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 1482c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 14835d424d5aSJohn Heffner } 14844bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 14855d424d5aSJohn Heffner 14861da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 14871da177e4SLinus Torvalds 14881da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 14891da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 14901da177e4SLinus Torvalds 14911da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1492caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 14931da177e4SLinus Torvalds It also does not include TCP options. 14941da177e4SLinus Torvalds 1495d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 14961da177e4SLinus Torvalds 14971da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 14981da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 14991da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 15001da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 15011da177e4SLinus Torvalds 15021da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 15031da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 15041da177e4SLinus Torvalds 1505d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1506d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 15071da177e4SLinus Torvalds */ 15081da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 15091da177e4SLinus Torvalds { 15101da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1511d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 15125d424d5aSJohn Heffner int mss_now; 15131da177e4SLinus Torvalds 15145d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 15155d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 15161da177e4SLinus Torvalds 15175d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1518409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 15191da177e4SLinus Torvalds 15201da177e4SLinus Torvalds /* And store cached results */ 1521d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 15225d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 15235d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1524c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 15251da177e4SLinus Torvalds 15261da177e4SLinus Torvalds return mss_now; 15271da177e4SLinus Torvalds } 15284bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 15291da177e4SLinus Torvalds 15301da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 15311da177e4SLinus Torvalds * and even PMTU discovery events into account. 15321da177e4SLinus Torvalds */ 15330c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 15341da177e4SLinus Torvalds { 1535cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1536cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1537c1b4a7e6SDavid S. Miller u32 mss_now; 153895c96174SEric Dumazet unsigned int header_len; 153933ad798cSAdam Langley struct tcp_out_options opts; 154033ad798cSAdam Langley struct tcp_md5sig_key *md5; 15411da177e4SLinus Torvalds 1542c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1543c1b4a7e6SDavid S. Miller 15441da177e4SLinus Torvalds if (dst) { 15451da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1546d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 15471da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 15481da177e4SLinus Torvalds } 15491da177e4SLinus Torvalds 155033ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 155133ad798cSAdam Langley sizeof(struct tcphdr); 155233ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 155333ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 155433ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 155533ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 155633ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 155733ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 155833ad798cSAdam Langley mss_now -= delta; 155933ad798cSAdam Langley } 1560cfb6eeb4SYOSHIFUJI Hideaki 15611da177e4SLinus Torvalds return mss_now; 15621da177e4SLinus Torvalds } 15631da177e4SLinus Torvalds 156486fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 156586fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 156686fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 156786fd14adSWeiping Pan */ 156886fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1569a762a980SDavid S. Miller { 15709e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1571a762a980SDavid S. Miller 157286fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 157386fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 157486fd14adSWeiping Pan /* Limited by application or receiver window. */ 157586fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 157686fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 157786fd14adSWeiping Pan if (win_used < tp->snd_cwnd) { 157886fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 157986fd14adSWeiping Pan tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; 158086fd14adSWeiping Pan } 158186fd14adSWeiping Pan tp->snd_cwnd_used = 0; 158286fd14adSWeiping Pan } 1583c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 158486fd14adSWeiping Pan } 158586fd14adSWeiping Pan 1586ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1587a762a980SDavid S. Miller { 15881b1fc3fdSWei Wang const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1589a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1590a762a980SDavid S. Miller 1591ca8a2263SNeal Cardwell /* Track the maximum number of outstanding packets in each 1592ca8a2263SNeal Cardwell * window, and remember whether we were cwnd-limited then. 1593ca8a2263SNeal Cardwell */ 1594ca8a2263SNeal Cardwell if (!before(tp->snd_una, tp->max_packets_seq) || 1595ca8a2263SNeal Cardwell tp->packets_out > tp->max_packets_out) { 1596ca8a2263SNeal Cardwell tp->max_packets_out = tp->packets_out; 1597ca8a2263SNeal Cardwell tp->max_packets_seq = tp->snd_nxt; 1598ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1599ca8a2263SNeal Cardwell } 1600e114a710SEric Dumazet 160124901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1602a762a980SDavid S. Miller /* Network is feed fully. */ 1603a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1604c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1605a762a980SDavid S. Miller } else { 1606a762a980SDavid S. Miller /* Network starves. */ 1607a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1608a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1609a762a980SDavid S. Miller 161015d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 1611c2203cf7SEric Dumazet (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && 16121b1fc3fdSWei Wang !ca_ops->cong_control) 1613a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1614b0f71bd3SFrancis Yan 1615b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1616b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1617b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1618b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 1619b0f71bd3SFrancis Yan * 3) no more data to send (null tcp_send_head ) 1620b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1621b0f71bd3SFrancis Yan */ 1622b0f71bd3SFrancis Yan if (!tcp_send_head(sk) && sk->sk_socket && 1623b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1624b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1625b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1626a762a980SDavid S. Miller } 1627a762a980SDavid S. Miller } 1628a762a980SDavid S. Miller 1629d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1630d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1631d4589926SEric Dumazet { 1632d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1633d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1634d4589926SEric Dumazet } 1635d4589926SEric Dumazet 1636d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1637d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1638d4589926SEric Dumazet * The test is really : 1639d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1640d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1641d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1642d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 16430e3a4803SIlpo Järvinen */ 1644d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1645d4589926SEric Dumazet const struct sk_buff *skb) 1646d4589926SEric Dumazet { 1647d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1648d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1649d4589926SEric Dumazet } 1650d4589926SEric Dumazet 1651d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1652d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1653d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1654d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1655d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1656d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1657d4589926SEric Dumazet */ 1658d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1659cc93fc51SPeter Pan(潘卫平) int nonagle) 1660d4589926SEric Dumazet { 1661d4589926SEric Dumazet return partial && 1662d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1663d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1664d4589926SEric Dumazet } 1665605ad7f1SEric Dumazet 1666605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 1667605ad7f1SEric Dumazet * to send one TSO packet per ms 1668605ad7f1SEric Dumazet */ 16691b3878caSNeal Cardwell u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 16701b3878caSNeal Cardwell int min_tso_segs) 1671605ad7f1SEric Dumazet { 1672605ad7f1SEric Dumazet u32 bytes, segs; 1673605ad7f1SEric Dumazet 1674605ad7f1SEric Dumazet bytes = min(sk->sk_pacing_rate >> 10, 1675605ad7f1SEric Dumazet sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); 1676605ad7f1SEric Dumazet 1677605ad7f1SEric Dumazet /* Goal is to send at least one packet per ms, 1678605ad7f1SEric Dumazet * not one big TSO packet every 100 ms. 1679605ad7f1SEric Dumazet * This preserves ACK clocking and is consistent 1680605ad7f1SEric Dumazet * with tcp_tso_should_defer() heuristic. 1681605ad7f1SEric Dumazet */ 16821b3878caSNeal Cardwell segs = max_t(u32, bytes / mss_now, min_tso_segs); 1683605ad7f1SEric Dumazet 1684605ad7f1SEric Dumazet return min_t(u32, segs, sk->sk_gso_max_segs); 1685605ad7f1SEric Dumazet } 16861b3878caSNeal Cardwell EXPORT_SYMBOL(tcp_tso_autosize); 1687605ad7f1SEric Dumazet 1688ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1689ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1690ed6e7268SNeal Cardwell */ 1691ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1692ed6e7268SNeal Cardwell { 1693ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1694ed6e7268SNeal Cardwell u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0; 1695ed6e7268SNeal Cardwell 16961b3878caSNeal Cardwell return tso_segs ? : 16971b3878caSNeal Cardwell tcp_tso_autosize(sk, mss_now, sysctl_tcp_min_tso_segs); 1698ed6e7268SNeal Cardwell } 1699ed6e7268SNeal Cardwell 1700d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1701d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1702d4589926SEric Dumazet const struct sk_buff *skb, 1703d4589926SEric Dumazet unsigned int mss_now, 1704d4589926SEric Dumazet unsigned int max_segs, 1705d4589926SEric Dumazet int nonagle) 1706c1b4a7e6SDavid S. Miller { 1707cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1708d4589926SEric Dumazet u32 partial, needed, window, max_len; 1709c1b4a7e6SDavid S. Miller 171090840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 17111485348dSBen Hutchings max_len = mss_now * max_segs; 17120e3a4803SIlpo Järvinen 17131485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 17141485348dSBen Hutchings return max_len; 17150e3a4803SIlpo Järvinen 17165ea3a748SIlpo Järvinen needed = min(skb->len, window); 17175ea3a748SIlpo Järvinen 17181485348dSBen Hutchings if (max_len <= needed) 17191485348dSBen Hutchings return max_len; 17200e3a4803SIlpo Järvinen 1721d4589926SEric Dumazet partial = needed % mss_now; 1722d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 1723d4589926SEric Dumazet * to include this last segment in this skb. 1724d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 1725d4589926SEric Dumazet */ 1726cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 1727d4589926SEric Dumazet return needed - partial; 1728d4589926SEric Dumazet 1729d4589926SEric Dumazet return needed; 1730c1b4a7e6SDavid S. Miller } 1731c1b4a7e6SDavid S. Miller 1732c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1733c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1734c1b4a7e6SDavid S. Miller */ 1735cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1736cf533ea5SEric Dumazet const struct sk_buff *skb) 1737c1b4a7e6SDavid S. Miller { 1738d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 1739c1b4a7e6SDavid S. Miller 1740c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 17414de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 17424de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1743c1b4a7e6SDavid S. Miller return 1; 1744c1b4a7e6SDavid S. Miller 1745c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1746c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1747d649a7a8SEric Dumazet if (in_flight >= cwnd) 1748c1b4a7e6SDavid S. Miller return 0; 1749d649a7a8SEric Dumazet 1750d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 1751d649a7a8SEric Dumazet * 2 GSO packets in flight. 1752d649a7a8SEric Dumazet */ 1753d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 1754d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 1755c1b4a7e6SDavid S. Miller } 1756c1b4a7e6SDavid S. Miller 1757b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 175867edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1759c1b4a7e6SDavid S. Miller * SKB onto the wire. 1760c1b4a7e6SDavid S. Miller */ 17615bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1762c1b4a7e6SDavid S. Miller { 1763c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1764c1b4a7e6SDavid S. Miller 1765f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 17665bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 1767c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1768c1b4a7e6SDavid S. Miller } 1769c1b4a7e6SDavid S. Miller return tso_segs; 1770c1b4a7e6SDavid S. Miller } 1771c1b4a7e6SDavid S. Miller 1772c1b4a7e6SDavid S. Miller 1773a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 1774c1b4a7e6SDavid S. Miller * sent now. 1775c1b4a7e6SDavid S. Miller */ 1776a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1777c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1778c1b4a7e6SDavid S. Miller { 1779c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1780c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1781c1b4a7e6SDavid S. Miller * 1782c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1783c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1784c1b4a7e6SDavid S. Miller */ 1785c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1786a2a385d6SEric Dumazet return true; 1787c1b4a7e6SDavid S. Miller 17889b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 17899b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1790a2a385d6SEric Dumazet return true; 1791c1b4a7e6SDavid S. Miller 1792cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 1793a2a385d6SEric Dumazet return true; 1794c1b4a7e6SDavid S. Miller 1795a2a385d6SEric Dumazet return false; 1796c1b4a7e6SDavid S. Miller } 1797c1b4a7e6SDavid S. Miller 1798c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1799a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 1800a2a385d6SEric Dumazet const struct sk_buff *skb, 1801056834d9SIlpo Järvinen unsigned int cur_mss) 1802c1b4a7e6SDavid S. Miller { 1803c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1804c1b4a7e6SDavid S. Miller 1805c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1806c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1807c1b4a7e6SDavid S. Miller 180890840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1809c1b4a7e6SDavid S. Miller } 1810c1b4a7e6SDavid S. Miller 1811c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1812c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1813c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1814c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1815c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1816c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1817c1b4a7e6SDavid S. Miller */ 1818056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1819c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1820c1b4a7e6SDavid S. Miller { 1821c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1822c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 18239ce01461SIlpo Järvinen u8 flags; 1824c1b4a7e6SDavid S. Miller 1825c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1826c8ac3774SHerbert Xu if (skb->len != skb->data_len) 18276cc55e09SOctavian Purdila return tcp_fragment(sk, skb, len, mss_now, gfp); 1828c1b4a7e6SDavid S. Miller 1829eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp, true); 183051456b29SIan Morris if (unlikely(!buff)) 1831c1b4a7e6SDavid S. Miller return -ENOMEM; 1832c1b4a7e6SDavid S. Miller 18333ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 18343ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1835b60b49eaSHerbert Xu buff->truesize += nlen; 1836c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1837c1b4a7e6SDavid S. Miller 1838c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1839c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1840c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1841c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1842c1b4a7e6SDavid S. Miller 1843c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 18444de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 18454de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 18464de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1847c1b4a7e6SDavid S. Miller 1848c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1849c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1850c1b4a7e6SDavid S. Miller 1851a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 1852a166140eSMartin KaFai Lau 185384fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1854c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1855490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 1856c1b4a7e6SDavid S. Miller 1857c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 18585bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 18595bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 1860c1b4a7e6SDavid S. Miller 1861c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1862f4a775d1SEric Dumazet __skb_header_release(buff); 1863fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1864c1b4a7e6SDavid S. Miller 1865c1b4a7e6SDavid S. Miller return 0; 1866c1b4a7e6SDavid S. Miller } 1867c1b4a7e6SDavid S. Miller 1868c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1869c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1870c1b4a7e6SDavid S. Miller * 1871c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1872c1b4a7e6SDavid S. Miller */ 1873ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 1874605ad7f1SEric Dumazet bool *is_cwnd_limited, u32 max_segs) 1875c1b4a7e6SDavid S. Miller { 18766687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 187750c8339eSEric Dumazet u32 age, send_win, cong_win, limit, in_flight; 187850c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 187950c8339eSEric Dumazet struct sk_buff *head; 1880ad9f4f50SEric Dumazet int win_divisor; 1881c1b4a7e6SDavid S. Miller 18824de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1883ae8064acSJohn Heffner goto send_now; 1884c1b4a7e6SDavid S. Miller 188599d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 1886ae8064acSJohn Heffner goto send_now; 1887ae8064acSJohn Heffner 18885f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 18895f852eb5SEric Dumazet * only if the last write was recent. 18905f852eb5SEric Dumazet */ 1891d635fbe2SEric Dumazet if ((s32)(tcp_jiffies32 - tp->lsndtime) > 0) 1892ae8064acSJohn Heffner goto send_now; 1893908a75c1SDavid S. Miller 1894c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1895c1b4a7e6SDavid S. Miller 1896056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1897c1b4a7e6SDavid S. Miller 189890840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1899c1b4a7e6SDavid S. Miller 1900c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1901c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1902c1b4a7e6SDavid S. Miller 1903c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1904c1b4a7e6SDavid S. Miller 1905ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 1906605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 1907ae8064acSJohn Heffner goto send_now; 1908ba244fe9SDavid S. Miller 190962ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 191062ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 191162ad2761SIlpo Järvinen goto send_now; 191262ad2761SIlpo Järvinen 1913ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1914ad9f4f50SEric Dumazet if (win_divisor) { 1915c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1916c1b4a7e6SDavid S. Miller 1917c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1918c1b4a7e6SDavid S. Miller * just use it. 1919c1b4a7e6SDavid S. Miller */ 1920ad9f4f50SEric Dumazet chunk /= win_divisor; 1921c1b4a7e6SDavid S. Miller if (limit >= chunk) 1922ae8064acSJohn Heffner goto send_now; 1923c1b4a7e6SDavid S. Miller } else { 1924c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1925c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1926c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1927c1b4a7e6SDavid S. Miller * then send now. 1928c1b4a7e6SDavid S. Miller */ 19296b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1930ae8064acSJohn Heffner goto send_now; 1931c1b4a7e6SDavid S. Miller } 1932c1b4a7e6SDavid S. Miller 193350c8339eSEric Dumazet head = tcp_write_queue_head(sk); 1934385e2070SEric Dumazet 19359a568de4SEric Dumazet age = tcp_stamp_us_delta(tp->tcp_mstamp, head->skb_mstamp); 193650c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 193750c8339eSEric Dumazet if (age < (tp->srtt_us >> 4)) 193850c8339eSEric Dumazet goto send_now; 193950c8339eSEric Dumazet 19405f852eb5SEric Dumazet /* Ok, it looks like it is advisable to defer. */ 1941ae8064acSJohn Heffner 1942d2e1339fSBendik Rønning Opstad if (cong_win < send_win && cong_win <= skb->len) 1943ca8a2263SNeal Cardwell *is_cwnd_limited = true; 1944ca8a2263SNeal Cardwell 1945a2a385d6SEric Dumazet return true; 1946ae8064acSJohn Heffner 1947ae8064acSJohn Heffner send_now: 1948a2a385d6SEric Dumazet return false; 1949c1b4a7e6SDavid S. Miller } 1950c1b4a7e6SDavid S. Miller 195105cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 195205cbc0dbSFan Du { 195305cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 195405cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 195505cbc0dbSFan Du struct net *net = sock_net(sk); 195605cbc0dbSFan Du u32 interval; 195705cbc0dbSFan Du s32 delta; 195805cbc0dbSFan Du 195905cbc0dbSFan Du interval = net->ipv4.sysctl_tcp_probe_interval; 1960c74df29aSEric Dumazet delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; 196105cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 196205cbc0dbSFan Du int mss = tcp_current_mss(sk); 196305cbc0dbSFan Du 196405cbc0dbSFan Du /* Update current search range */ 196505cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 196605cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 196705cbc0dbSFan Du sizeof(struct tcphdr) + 196805cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 196905cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 197005cbc0dbSFan Du 197105cbc0dbSFan Du /* Update probe time stamp */ 1972c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 197305cbc0dbSFan Du } 197405cbc0dbSFan Du } 197505cbc0dbSFan Du 19765d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 197767edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 197867edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 197967edfef7SAndi Kleen * changes resulting in larger path MTUs. 198067edfef7SAndi Kleen * 19815d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 19825d424d5aSJohn Heffner * 1 if a probe was sent, 1983056834d9SIlpo Järvinen * -1 otherwise 1984056834d9SIlpo Järvinen */ 19855d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 19865d424d5aSJohn Heffner { 19875d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 198812a59abcSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 19895d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 19906b58e0a5SFan Du struct net *net = sock_net(sk); 19915d424d5aSJohn Heffner int probe_size; 199291cc17c0SIlpo Järvinen int size_needed; 199312a59abcSEric Dumazet int copy, len; 19945d424d5aSJohn Heffner int mss_now; 19956b58e0a5SFan Du int interval; 19965d424d5aSJohn Heffner 19975d424d5aSJohn Heffner /* Not currently probing/verifying, 19985d424d5aSJohn Heffner * not in recovery, 19995d424d5aSJohn Heffner * have enough cwnd, and 200012a59abcSEric Dumazet * not SACKing (the variable headers throw things off) 200112a59abcSEric Dumazet */ 200212a59abcSEric Dumazet if (likely(!icsk->icsk_mtup.enabled || 20035d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 20045d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 20055d424d5aSJohn Heffner tp->snd_cwnd < 11 || 200612a59abcSEric Dumazet tp->rx_opt.num_sacks || tp->rx_opt.dsack)) 20075d424d5aSJohn Heffner return -1; 20085d424d5aSJohn Heffner 20096b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 20106b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 20116b58e0a5SFan Du * smaller than a threshold, backoff from probing. 20126b58e0a5SFan Du */ 20130c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 20146b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 20156b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 201691cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 20176b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 201805cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 201905cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 202005cbc0dbSFan Du * probing process by not resetting search range to its orignal. 202105cbc0dbSFan Du */ 20226b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 202305cbc0dbSFan Du interval < net->ipv4.sysctl_tcp_probe_threshold) { 202405cbc0dbSFan Du /* Check whether enough time has elaplased for 202505cbc0dbSFan Du * another round of probing. 202605cbc0dbSFan Du */ 202705cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 20285d424d5aSJohn Heffner return -1; 20295d424d5aSJohn Heffner } 20305d424d5aSJohn Heffner 20315d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 20327f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 20335d424d5aSJohn Heffner return -1; 20345d424d5aSJohn Heffner 203591cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 20365d424d5aSJohn Heffner return -1; 203790840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 20385d424d5aSJohn Heffner return 0; 20395d424d5aSJohn Heffner 2040d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 2041d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 2042d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 20435d424d5aSJohn Heffner return -1; 20445d424d5aSJohn Heffner else 20455d424d5aSJohn Heffner return 0; 20465d424d5aSJohn Heffner } 20475d424d5aSJohn Heffner 20485d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 2049eb934478SEric Dumazet nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); 205051456b29SIan Morris if (!nskb) 20515d424d5aSJohn Heffner return -1; 20523ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 20533ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 20545d424d5aSJohn Heffner 2055fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 20565d424d5aSJohn Heffner 20575d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 20585d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 20594de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 20605d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 20615d424d5aSJohn Heffner nskb->csum = 0; 206284fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 20635d424d5aSJohn Heffner 206450c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 2065*2b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 206650c4817eSIlpo Järvinen 20675d424d5aSJohn Heffner len = 0; 2068234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 20695d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 20702fe664f1SDouglas Caetano dos Santos if (nskb->ip_summed) { 20715d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 20722fe664f1SDouglas Caetano dos Santos } else { 20732fe664f1SDouglas Caetano dos Santos __wsum csum = skb_copy_and_csum_bits(skb, 0, 2074056834d9SIlpo Järvinen skb_put(nskb, copy), 20752fe664f1SDouglas Caetano dos Santos copy, 0); 20762fe664f1SDouglas Caetano dos Santos nskb->csum = csum_block_add(nskb->csum, csum, len); 20772fe664f1SDouglas Caetano dos Santos } 20785d424d5aSJohn Heffner 20795d424d5aSJohn Heffner if (skb->len <= copy) { 20805d424d5aSJohn Heffner /* We've eaten all the data from this skb. 20815d424d5aSJohn Heffner * Throw it away. */ 20824de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2083fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 20843ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 20855d424d5aSJohn Heffner } else { 20864de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2087a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 20885d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 20895d424d5aSJohn Heffner skb_pull(skb, copy); 209084fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 2091056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 2092056834d9SIlpo Järvinen skb->len, 0); 20935d424d5aSJohn Heffner } else { 20945d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 20955bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 20965d424d5aSJohn Heffner } 20975d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 20985d424d5aSJohn Heffner } 20995d424d5aSJohn Heffner 21005d424d5aSJohn Heffner len += copy; 2101234b6860SIlpo Järvinen 2102234b6860SIlpo Järvinen if (len >= probe_size) 2103234b6860SIlpo Järvinen break; 21045d424d5aSJohn Heffner } 21055bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 21065d424d5aSJohn Heffner 21075d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 21087faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 21097faee5c0SEric Dumazet */ 21105d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 21115d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 21125d424d5aSJohn Heffner * effectively two packets. */ 21135d424d5aSJohn Heffner tp->snd_cwnd--; 211466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 21155d424d5aSJohn Heffner 21165d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 21170e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 21180e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 21195d424d5aSJohn Heffner 21205d424d5aSJohn Heffner return 1; 21215d424d5aSJohn Heffner } 21225d424d5aSJohn Heffner 21235d424d5aSJohn Heffner return -1; 21245d424d5aSJohn Heffner } 21255d424d5aSJohn Heffner 2126218af599SEric Dumazet static bool tcp_pacing_check(const struct sock *sk) 2127218af599SEric Dumazet { 2128218af599SEric Dumazet return tcp_needs_internal_pacing(sk) && 2129218af599SEric Dumazet hrtimer_active(&tcp_sk(sk)->pacing_timer); 2130218af599SEric Dumazet } 2131218af599SEric Dumazet 2132f9616c35SEric Dumazet /* TCP Small Queues : 2133f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2134f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2135f9616c35SEric Dumazet * This allows for : 2136f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2137f9616c35SEric Dumazet * - faster recovery 2138f9616c35SEric Dumazet * - high rates 2139f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2140f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2141f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2142f9616c35SEric Dumazet */ 2143f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2144f9616c35SEric Dumazet unsigned int factor) 2145f9616c35SEric Dumazet { 2146f9616c35SEric Dumazet unsigned int limit; 2147f9616c35SEric Dumazet 2148f9616c35SEric Dumazet limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10); 2149f9616c35SEric Dumazet limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes); 2150f9616c35SEric Dumazet limit <<= factor; 2151f9616c35SEric Dumazet 215214afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) { 215375eefc6cSEric Dumazet /* Always send the 1st or 2nd skb in write queue. 215475eefc6cSEric Dumazet * No need to wait for TX completion to call us back, 215575eefc6cSEric Dumazet * after softirq/tasklet schedule. 215675eefc6cSEric Dumazet * This helps when TX completions are delayed too much. 215775eefc6cSEric Dumazet */ 215875eefc6cSEric Dumazet if (skb == sk->sk_write_queue.next || 215975eefc6cSEric Dumazet skb->prev == sk->sk_write_queue.next) 216075eefc6cSEric Dumazet return false; 216175eefc6cSEric Dumazet 21627aa5470cSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2163f9616c35SEric Dumazet /* It is possible TX completion already happened 2164f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2165f9616c35SEric Dumazet * test again the condition. 2166f9616c35SEric Dumazet */ 2167f9616c35SEric Dumazet smp_mb__after_atomic(); 216814afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) 2169f9616c35SEric Dumazet return true; 2170f9616c35SEric Dumazet } 2171f9616c35SEric Dumazet return false; 2172f9616c35SEric Dumazet } 2173f9616c35SEric Dumazet 217405b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 217505b055e8SFrancis Yan { 2176628174ccSEric Dumazet const u32 now = tcp_jiffies32; 2177efe967cdSArnd Bergmann enum tcp_chrono old = tp->chrono_type; 217805b055e8SFrancis Yan 2179efe967cdSArnd Bergmann if (old > TCP_CHRONO_UNSPEC) 2180efe967cdSArnd Bergmann tp->chrono_stat[old - 1] += now - tp->chrono_start; 218105b055e8SFrancis Yan tp->chrono_start = now; 218205b055e8SFrancis Yan tp->chrono_type = new; 218305b055e8SFrancis Yan } 218405b055e8SFrancis Yan 218505b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 218605b055e8SFrancis Yan { 218705b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 218805b055e8SFrancis Yan 218905b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 21900f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 21910f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 219205b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 219305b055e8SFrancis Yan */ 219405b055e8SFrancis Yan if (type > tp->chrono_type) 219505b055e8SFrancis Yan tcp_chrono_set(tp, type); 219605b055e8SFrancis Yan } 219705b055e8SFrancis Yan 219805b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 219905b055e8SFrancis Yan { 220005b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 220105b055e8SFrancis Yan 22020f87230dSFrancis Yan 22030f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 22040f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 22050f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 22060f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 22070f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 22080f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 22090f87230dSFrancis Yan */ 22100f87230dSFrancis Yan if (tcp_write_queue_empty(sk)) 221105b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 22120f87230dSFrancis Yan else if (type == tp->chrono_type) 22130f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 221405b055e8SFrancis Yan } 221505b055e8SFrancis Yan 22161da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 22171da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 22181da177e4SLinus Torvalds * window for us. 22191da177e4SLinus Torvalds * 2220f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2221f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2222f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2223f8269a49SIlpo Järvinen * 22246ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 22256ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 22266ba8a3b1SNandita Dukkipati 2227a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2228a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 22291da177e4SLinus Torvalds */ 2230a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2231d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 22321da177e4SLinus Torvalds { 22331da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 223492df7b51SDavid S. Miller struct sk_buff *skb; 2235c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2236c1b4a7e6SDavid S. Miller int cwnd_quota; 22375d424d5aSJohn Heffner int result; 22385615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2239605ad7f1SEric Dumazet u32 max_segs; 22401da177e4SLinus Torvalds 2241c1b4a7e6SDavid S. Miller sent_pkts = 0; 22425d424d5aSJohn Heffner 2243ee1836aeSEric Dumazet tcp_mstamp_refresh(tp); 2244d5dd9175SIlpo Järvinen if (!push_one) { 22455d424d5aSJohn Heffner /* Do MTU probing. */ 2246d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2247d5dd9175SIlpo Järvinen if (!result) { 2248a2a385d6SEric Dumazet return false; 22495d424d5aSJohn Heffner } else if (result > 0) { 22505d424d5aSJohn Heffner sent_pkts = 1; 22515d424d5aSJohn Heffner } 2252d5dd9175SIlpo Järvinen } 22535d424d5aSJohn Heffner 2254ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2255fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2256c8ac3774SHerbert Xu unsigned int limit; 2257c8ac3774SHerbert Xu 2258218af599SEric Dumazet if (tcp_pacing_check(sk)) 2259218af599SEric Dumazet break; 2260218af599SEric Dumazet 22615bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2262c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2263c1b4a7e6SDavid S. Miller 22649d186cacSAndrey Vagin if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 22657faee5c0SEric Dumazet /* "skb_mstamp" is used as a start point for the retransmit timer */ 2266385e2070SEric Dumazet skb->skb_mstamp = tp->tcp_mstamp; 2267ec342325SAndrew Vagin goto repair; /* Skip network transmission */ 22689d186cacSAndrey Vagin } 2269ec342325SAndrew Vagin 2270b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 22716ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 22726ba8a3b1SNandita Dukkipati if (push_one == 2) 22736ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 22746ba8a3b1SNandita Dukkipati cwnd_quota = 1; 22756ba8a3b1SNandita Dukkipati else 2276b68e9f85SHerbert Xu break; 22776ba8a3b1SNandita Dukkipati } 2278b68e9f85SHerbert Xu 22795615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 22805615f886SFrancis Yan is_rwnd_limited = true; 2281b68e9f85SHerbert Xu break; 22825615f886SFrancis Yan } 2283b68e9f85SHerbert Xu 2284d6a4e26aSEric Dumazet if (tso_segs == 1) { 2285aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2286aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2287aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2288aa93466bSDavid S. Miller break; 2289c1b4a7e6SDavid S. Miller } else { 2290ca8a2263SNeal Cardwell if (!push_one && 2291605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2292605ad7f1SEric Dumazet max_segs)) 2293aa93466bSDavid S. Miller break; 2294c1b4a7e6SDavid S. Miller } 2295aa93466bSDavid S. Miller 2296605ad7f1SEric Dumazet limit = mss_now; 2297d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2298605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2299605ad7f1SEric Dumazet min_t(unsigned int, 2300605ad7f1SEric Dumazet cwnd_quota, 2301605ad7f1SEric Dumazet max_segs), 2302605ad7f1SEric Dumazet nonagle); 2303605ad7f1SEric Dumazet 2304605ad7f1SEric Dumazet if (skb->len > limit && 2305605ad7f1SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2306605ad7f1SEric Dumazet break; 2307605ad7f1SEric Dumazet 23087aa5470cSEric Dumazet if (test_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) 23097aa5470cSEric Dumazet clear_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags); 2310f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 231146d3ceabSEric Dumazet break; 2312c9eeec26SEric Dumazet 2313d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 23141da177e4SLinus Torvalds break; 23151da177e4SLinus Torvalds 2316ec342325SAndrew Vagin repair: 23171da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 23181da177e4SLinus Torvalds * This call will increment packets_out. 23191da177e4SLinus Torvalds */ 232066f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 23211da177e4SLinus Torvalds 23221da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2323a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2324d5dd9175SIlpo Järvinen 2325d5dd9175SIlpo Järvinen if (push_one) 2326d5dd9175SIlpo Järvinen break; 23271da177e4SLinus Torvalds } 23281da177e4SLinus Torvalds 23295615f886SFrancis Yan if (is_rwnd_limited) 23305615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 23315615f886SFrancis Yan else 23325615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 23335615f886SFrancis Yan 2334aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2335684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2336684bad11SYuchung Cheng tp->prr_out += sent_pkts; 23376ba8a3b1SNandita Dukkipati 23386ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 23396ba8a3b1SNandita Dukkipati if (push_one != 2) 23406ba8a3b1SNandita Dukkipati tcp_schedule_loss_probe(sk); 2341d2e1339fSBendik Rønning Opstad is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); 2342ca8a2263SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2343a2a385d6SEric Dumazet return false; 23441da177e4SLinus Torvalds } 2345b340b264SYuchung Cheng return !tp->packets_out && tcp_send_head(sk); 23466ba8a3b1SNandita Dukkipati } 23476ba8a3b1SNandita Dukkipati 23486ba8a3b1SNandita Dukkipati bool tcp_schedule_loss_probe(struct sock *sk) 23496ba8a3b1SNandita Dukkipati { 23506ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 23516ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 2352a2815817SNeal Cardwell u32 timeout, rto_delta_us; 23536ba8a3b1SNandita Dukkipati 23546ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 23556ba8a3b1SNandita Dukkipati * finishes. 23566ba8a3b1SNandita Dukkipati */ 2357f9b99582SYuchung Cheng if (tp->fastopen_rsk) 23586ba8a3b1SNandita Dukkipati return false; 23596ba8a3b1SNandita Dukkipati 23606ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 23616ba8a3b1SNandita Dukkipati * in Open state, that are either limited by cwnd or application. 23626ba8a3b1SNandita Dukkipati */ 2363bec41a11SYuchung Cheng if ((sysctl_tcp_early_retrans != 3 && sysctl_tcp_early_retrans != 4) || 2364bec41a11SYuchung Cheng !tp->packets_out || !tcp_is_sack(tp) || 2365bec41a11SYuchung Cheng icsk->icsk_ca_state != TCP_CA_Open) 23666ba8a3b1SNandita Dukkipati return false; 23676ba8a3b1SNandita Dukkipati 23686ba8a3b1SNandita Dukkipati if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && 23696ba8a3b1SNandita Dukkipati tcp_send_head(sk)) 23706ba8a3b1SNandita Dukkipati return false; 23716ba8a3b1SNandita Dukkipati 2372bb4d991aSYuchung Cheng /* Probe timeout is 2*rtt. Add minimum RTO to account 2373f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2374f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 23756ba8a3b1SNandita Dukkipati */ 2376bb4d991aSYuchung Cheng if (tp->srtt_us) { 2377bb4d991aSYuchung Cheng timeout = usecs_to_jiffies(tp->srtt_us >> 2); 23786ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 2379bb4d991aSYuchung Cheng timeout += TCP_RTO_MIN; 2380bb4d991aSYuchung Cheng else 2381bb4d991aSYuchung Cheng timeout += TCP_TIMEOUT_MIN; 2382bb4d991aSYuchung Cheng } else { 2383bb4d991aSYuchung Cheng timeout = TCP_TIMEOUT_INIT; 2384bb4d991aSYuchung Cheng } 23856ba8a3b1SNandita Dukkipati 2386a2815817SNeal Cardwell /* If the RTO formula yields an earlier time, then use that time. */ 2387a2815817SNeal Cardwell rto_delta_us = tcp_rto_delta_us(sk); /* How far in future is RTO? */ 2388a2815817SNeal Cardwell if (rto_delta_us > 0) 2389a2815817SNeal Cardwell timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); 23906ba8a3b1SNandita Dukkipati 23916ba8a3b1SNandita Dukkipati inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, 23926ba8a3b1SNandita Dukkipati TCP_RTO_MAX); 23936ba8a3b1SNandita Dukkipati return true; 23946ba8a3b1SNandita Dukkipati } 23956ba8a3b1SNandita Dukkipati 23961f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 23971f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 23981f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 23991f3279aeSEric Dumazet */ 24001f3279aeSEric Dumazet static bool skb_still_in_host_queue(const struct sock *sk, 24011f3279aeSEric Dumazet const struct sk_buff *skb) 24021f3279aeSEric Dumazet { 240339bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2404c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 24051f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 24061f3279aeSEric Dumazet return true; 24071f3279aeSEric Dumazet } 24081f3279aeSEric Dumazet return false; 24091f3279aeSEric Dumazet } 24101f3279aeSEric Dumazet 2411b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 24126ba8a3b1SNandita Dukkipati * retransmit the last segment. 24136ba8a3b1SNandita Dukkipati */ 24146ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 24156ba8a3b1SNandita Dukkipati { 24169b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 24176ba8a3b1SNandita Dukkipati struct sk_buff *skb; 24186ba8a3b1SNandita Dukkipati int pcount; 24196ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 24206ba8a3b1SNandita Dukkipati 2421b340b264SYuchung Cheng skb = tcp_send_head(sk); 2422b340b264SYuchung Cheng if (skb) { 2423b340b264SYuchung Cheng if (tcp_snd_wnd_test(tp, skb, mss)) { 2424b340b264SYuchung Cheng pcount = tp->packets_out; 2425b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2426b340b264SYuchung Cheng if (tp->packets_out > pcount) 2427b340b264SYuchung Cheng goto probe_sent; 24286ba8a3b1SNandita Dukkipati goto rearm_timer; 24296ba8a3b1SNandita Dukkipati } 2430b340b264SYuchung Cheng skb = tcp_write_queue_prev(sk, skb); 2431b340b264SYuchung Cheng } else { 2432b340b264SYuchung Cheng skb = tcp_write_queue_tail(sk); 2433b340b264SYuchung Cheng } 24346ba8a3b1SNandita Dukkipati 24359b717a8dSNandita Dukkipati /* At most one outstanding TLP retransmission. */ 24369b717a8dSNandita Dukkipati if (tp->tlp_high_seq) 24379b717a8dSNandita Dukkipati goto rearm_timer; 24389b717a8dSNandita Dukkipati 24396ba8a3b1SNandita Dukkipati /* Retransmit last segment. */ 24406ba8a3b1SNandita Dukkipati if (WARN_ON(!skb)) 24416ba8a3b1SNandita Dukkipati goto rearm_timer; 24426ba8a3b1SNandita Dukkipati 24431f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 24441f3279aeSEric Dumazet goto rearm_timer; 24451f3279aeSEric Dumazet 24466ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 24476ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 24486ba8a3b1SNandita Dukkipati goto rearm_timer; 24496ba8a3b1SNandita Dukkipati 24506ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 24516cc55e09SOctavian Purdila if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, 24526cc55e09SOctavian Purdila GFP_ATOMIC))) 24536ba8a3b1SNandita Dukkipati goto rearm_timer; 2454b340b264SYuchung Cheng skb = tcp_write_queue_next(sk, skb); 24556ba8a3b1SNandita Dukkipati } 24566ba8a3b1SNandita Dukkipati 24576ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 24586ba8a3b1SNandita Dukkipati goto rearm_timer; 24596ba8a3b1SNandita Dukkipati 246010d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2461b340b264SYuchung Cheng goto rearm_timer; 24626ba8a3b1SNandita Dukkipati 24639b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 24649b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 24659b717a8dSNandita Dukkipati 2466b340b264SYuchung Cheng probe_sent: 2467c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2468fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2469fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2470b340b264SYuchung Cheng rearm_timer: 2471fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 24721da177e4SLinus Torvalds } 24731da177e4SLinus Torvalds 2474a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2475a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2476a762a980SDavid S. Miller * The socket must be locked by the caller. 2477a762a980SDavid S. Miller */ 24789e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 24799e412ba7SIlpo Järvinen int nonagle) 2480a762a980SDavid S. Miller { 2481726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2482726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2483726e07a8SIlpo Järvinen * all will be happy. 2484726e07a8SIlpo Järvinen */ 2485726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2486726e07a8SIlpo Järvinen return; 2487726e07a8SIlpo Järvinen 248899a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 24897450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 24909e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2491a762a980SDavid S. Miller } 2492a762a980SDavid S. Miller 2493c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2494c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2495c1b4a7e6SDavid S. Miller */ 2496c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2497c1b4a7e6SDavid S. Miller { 2498fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2499c1b4a7e6SDavid S. Miller 2500c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2501c1b4a7e6SDavid S. Miller 2502d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2503c1b4a7e6SDavid S. Miller } 2504c1b4a7e6SDavid S. Miller 25051da177e4SLinus Torvalds /* This function returns the amount that we can raise the 25061da177e4SLinus Torvalds * usable window based on the following constraints 25071da177e4SLinus Torvalds * 25081da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 25091da177e4SLinus Torvalds * 2. We limit memory per socket 25101da177e4SLinus Torvalds * 25111da177e4SLinus Torvalds * RFC 1122: 25121da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 25131da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 25141da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 25151da177e4SLinus Torvalds * 25161da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 25171da177e4SLinus Torvalds * it at least MSS bytes. 25181da177e4SLinus Torvalds * 25191da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 25201da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 25211da177e4SLinus Torvalds * 25221da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 25231da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 25241da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 25251da177e4SLinus Torvalds * window to always advance by a single byte. 25261da177e4SLinus Torvalds * 25271da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 25281da177e4SLinus Torvalds * then this will not be a problem. 25291da177e4SLinus Torvalds * 25301da177e4SLinus Torvalds * BSD seems to make the following compromise: 25311da177e4SLinus Torvalds * 25321da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 25331da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 25341da177e4SLinus Torvalds * then set the window to 0. 25351da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 25361da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 25371da177e4SLinus Torvalds * and from being larger than the largest representable value. 25381da177e4SLinus Torvalds * 25391da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 25401da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 25411da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 25421da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 25431da177e4SLinus Torvalds * because the pipeline is full. 25441da177e4SLinus Torvalds * 25451da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 25461da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 25471da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 25481da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 25491da177e4SLinus Torvalds * of having a fixed window size at almost all times. 25501da177e4SLinus Torvalds * 25511da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 25521da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 25531da177e4SLinus Torvalds * 25541da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 25551da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 25561da177e4SLinus Torvalds */ 25571da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 25581da177e4SLinus Torvalds { 2559463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 25601da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2561caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 25621da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 25631da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 25641da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 25651da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 25661da177e4SLinus Torvalds */ 2567463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 25681da177e4SLinus Torvalds int free_space = tcp_space(sk); 256986c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 257086c1a045SFlorian Westphal int full_space = min_t(int, tp->window_clamp, allowed_space); 25711da177e4SLinus Torvalds int window; 25721da177e4SLinus Torvalds 257306425c30SEric Dumazet if (unlikely(mss > full_space)) { 25741da177e4SLinus Torvalds mss = full_space; 257506425c30SEric Dumazet if (mss <= 0) 257606425c30SEric Dumazet return 0; 257706425c30SEric Dumazet } 2578b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 2579463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 25801da177e4SLinus Torvalds 2581b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 2582056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 2583056834d9SIlpo Järvinen 4U * tp->advmss); 25841da177e4SLinus Torvalds 258586c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 258686c1a045SFlorian Westphal * increase it due to wscale. 258786c1a045SFlorian Westphal */ 258886c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 258986c1a045SFlorian Westphal 259086c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 259186c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 259286c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 259386c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 259486c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 259586c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 259686c1a045SFlorian Westphal */ 259786c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 25981da177e4SLinus Torvalds return 0; 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds 26011da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 26021da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 26031da177e4SLinus Torvalds 26041da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 26051da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 26061da177e4SLinus Torvalds */ 26071da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 26081da177e4SLinus Torvalds window = free_space; 26091da177e4SLinus Torvalds 26101da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 26111da177e4SLinus Torvalds * Import case: prevent zero window announcement if 26121da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 26131da177e4SLinus Torvalds */ 26141935299dSGao Feng window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); 26151da177e4SLinus Torvalds } else { 26161935299dSGao Feng window = tp->rcv_wnd; 26171da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 26181da177e4SLinus Torvalds * Window clamp already applied above. 26191da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 26201da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 26211da177e4SLinus Torvalds * and multiply from happening most of the time. 26221da177e4SLinus Torvalds * We also don't do any window rounding when the free space 26231da177e4SLinus Torvalds * is too small. 26241da177e4SLinus Torvalds */ 26251da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 26261935299dSGao Feng window = rounddown(free_space, mss); 262784565070SJohn Heffner else if (mss == full_space && 2628b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 262984565070SJohn Heffner window = free_space; 26301da177e4SLinus Torvalds } 26311da177e4SLinus Torvalds 26321da177e4SLinus Torvalds return window; 26331da177e4SLinus Torvalds } 26341da177e4SLinus Torvalds 2635cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 2636082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 2637082ac2d5SMartin KaFai Lau { 26380a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 26390a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 26400a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 2641082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 2642082ac2d5SMartin KaFai Lau 26430a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 2644082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 26452de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 26462de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 2647082ac2d5SMartin KaFai Lau } 2648082ac2d5SMartin KaFai Lau } 2649082ac2d5SMartin KaFai Lau 26504a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 2651f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 26521da177e4SLinus Torvalds { 26531da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2654fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 2655058dc334SIlpo Järvinen int skb_size, next_skb_size; 26561da177e4SLinus Torvalds 2657058dc334SIlpo Järvinen skb_size = skb->len; 2658058dc334SIlpo Järvinen next_skb_size = next_skb->len; 26591da177e4SLinus Torvalds 2660058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 26611da177e4SLinus Torvalds 2662f8071cdeSEric Dumazet if (next_skb_size) { 2663f8071cdeSEric Dumazet if (next_skb_size <= skb_availroom(skb)) 2664f8071cdeSEric Dumazet skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), 2665f8071cdeSEric Dumazet next_skb_size); 2666f8071cdeSEric Dumazet else if (!skb_shift(skb, next_skb, next_skb_size)) 2667f8071cdeSEric Dumazet return false; 2668f8071cdeSEric Dumazet } 2669*2b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, next_skb, skb); 2670a6963a6bSIlpo Järvinen 2671fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 26721da177e4SLinus Torvalds 267352d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 267452d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 26751da177e4SLinus Torvalds 267684fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 26771da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 26781da177e4SLinus Torvalds 26791da177e4SLinus Torvalds /* Update sequence range on original skb. */ 26801da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 26811da177e4SLinus Torvalds 2682e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 26834de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 26841da177e4SLinus Torvalds 26851da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 26861da177e4SLinus Torvalds * packet counting does not break. 26871da177e4SLinus Torvalds */ 26884828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2689a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 2690b7689205SIlpo Järvinen 2691b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2692ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2693ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2694ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2695b7689205SIlpo Järvinen 2696797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2697797108d1SIlpo Järvinen 2698082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 2699082ac2d5SMartin KaFai Lau 27003ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 2701f8071cdeSEric Dumazet return true; 27021da177e4SLinus Torvalds } 27031da177e4SLinus Torvalds 270467edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2705a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 27064a17fc3aSIlpo Järvinen { 27074a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 2708a2a385d6SEric Dumazet return false; 27094a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 2710a2a385d6SEric Dumazet return false; 27114a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 2712a2a385d6SEric Dumazet return false; 27132331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 27144a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 2715a2a385d6SEric Dumazet return false; 27164a17fc3aSIlpo Järvinen 2717a2a385d6SEric Dumazet return true; 27184a17fc3aSIlpo Järvinen } 27194a17fc3aSIlpo Järvinen 272067edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 272167edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 272267edfef7SAndi Kleen */ 27234a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 27244a17fc3aSIlpo Järvinen int space) 27254a17fc3aSIlpo Järvinen { 27264a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 27274a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 2728a2a385d6SEric Dumazet bool first = true; 27294a17fc3aSIlpo Järvinen 27304a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 27314a17fc3aSIlpo Järvinen return; 27324de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 27334a17fc3aSIlpo Järvinen return; 27344a17fc3aSIlpo Järvinen 27354a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 27364a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 27374a17fc3aSIlpo Järvinen break; 27384a17fc3aSIlpo Järvinen 2739a643b5d4SMartin KaFai Lau if (!tcp_skb_can_collapse_to(to)) 2740a643b5d4SMartin KaFai Lau break; 2741a643b5d4SMartin KaFai Lau 27424a17fc3aSIlpo Järvinen space -= skb->len; 27434a17fc3aSIlpo Järvinen 27444a17fc3aSIlpo Järvinen if (first) { 2745a2a385d6SEric Dumazet first = false; 27464a17fc3aSIlpo Järvinen continue; 27474a17fc3aSIlpo Järvinen } 27484a17fc3aSIlpo Järvinen 27494a17fc3aSIlpo Järvinen if (space < 0) 27504a17fc3aSIlpo Järvinen break; 27514a17fc3aSIlpo Järvinen 27524a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 27534a17fc3aSIlpo Järvinen break; 27544a17fc3aSIlpo Järvinen 2755f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 2756f8071cdeSEric Dumazet break; 27574a17fc3aSIlpo Järvinen } 27584a17fc3aSIlpo Järvinen } 27594a17fc3aSIlpo Järvinen 27601da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 27611da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 27621da177e4SLinus Torvalds * error occurred which prevented the send. 27631da177e4SLinus Torvalds */ 276410d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 27651da177e4SLinus Torvalds { 27665d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 276710d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 27687d227cd2SSridhar Samudrala unsigned int cur_mss; 276910d3be56SEric Dumazet int diff, len, err; 27701da177e4SLinus Torvalds 277110d3be56SEric Dumazet 277210d3be56SEric Dumazet /* Inconclusive MTU probe */ 277310d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 27745d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 27755d424d5aSJohn Heffner 27761da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2777caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 27781da177e4SLinus Torvalds */ 277914afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > 2780ffb4d6c8SEric Dumazet min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), 2781ffb4d6c8SEric Dumazet sk->sk_sndbuf)) 27821da177e4SLinus Torvalds return -EAGAIN; 27831da177e4SLinus Torvalds 27841f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 27851f3279aeSEric Dumazet return -EBUSY; 27861f3279aeSEric Dumazet 27871da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 27881da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 27891da177e4SLinus Torvalds BUG(); 27901da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 27911da177e4SLinus Torvalds return -ENOMEM; 27921da177e4SLinus Torvalds } 27931da177e4SLinus Torvalds 27947d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 27957d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 27967d227cd2SSridhar Samudrala 27970c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 27987d227cd2SSridhar Samudrala 27991da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 28001da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 28011da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 28021da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 28031da177e4SLinus Torvalds */ 28049d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 28059d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 28061da177e4SLinus Torvalds return -EAGAIN; 28071da177e4SLinus Torvalds 280810d3be56SEric Dumazet len = cur_mss * segs; 280910d3be56SEric Dumazet if (skb->len > len) { 281010d3be56SEric Dumazet if (tcp_fragment(sk, skb, len, cur_mss, GFP_ATOMIC)) 28111da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 281202276f3cSIlpo Järvinen } else { 2813c52e2421SEric Dumazet if (skb_unclone(skb, GFP_ATOMIC)) 2814c52e2421SEric Dumazet return -ENOMEM; 281510d3be56SEric Dumazet 281610d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 281710d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 281810d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 281910d3be56SEric Dumazet if (diff) 282010d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 282110d3be56SEric Dumazet if (skb->len < cur_mss) 282210d3be56SEric Dumazet tcp_retrans_try_collapse(sk, skb, cur_mss); 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds 282549213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 282649213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 282749213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 282849213555SDaniel Borkmann 2829678550c6SYuchung Cheng /* Update global and local TCP statistics. */ 2830678550c6SYuchung Cheng segs = tcp_skb_pcount(skb); 2831678550c6SYuchung Cheng TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 2832678550c6SYuchung Cheng if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 2833678550c6SYuchung Cheng __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 2834678550c6SYuchung Cheng tp->total_retrans += segs; 2835678550c6SYuchung Cheng 283650bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 283750bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 283850bceae9SThomas Graf * beyond what csum_start can cover. 283950bceae9SThomas Graf */ 284050bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 284150bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 284210a81980SEric Dumazet struct sk_buff *nskb; 284310a81980SEric Dumazet 284410a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 2845c84a5711SYuchung Cheng err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2846117632e6SEric Dumazet -ENOBUFS; 28475889e2c0SYousuk Seung if (!err) { 28488c72c65bSEric Dumazet skb->skb_mstamp = tp->tcp_mstamp; 28495889e2c0SYousuk Seung tcp_rate_skb_sent(sk, skb); 28505889e2c0SYousuk Seung } 2851117632e6SEric Dumazet } else { 2852c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2853117632e6SEric Dumazet } 2854c84a5711SYuchung Cheng 2855fc9f3501SEric Dumazet if (likely(!err)) { 2856c84a5711SYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 2857678550c6SYuchung Cheng } else if (err != -EBUSY) { 2858678550c6SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 2859fc9f3501SEric Dumazet } 2860c84a5711SYuchung Cheng return err; 286193b174adSYuchung Cheng } 286293b174adSYuchung Cheng 286310d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 286493b174adSYuchung Cheng { 286593b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 286610d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 28671da177e4SLinus Torvalds 28681da177e4SLinus Torvalds if (err == 0) { 28691da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 28701da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 2871e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 28721da177e4SLinus Torvalds } 28731da177e4SLinus Torvalds #endif 28741da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 28751da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 28781da177e4SLinus Torvalds if (!tp->retrans_stamp) 28797faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 28801da177e4SLinus Torvalds 28811da177e4SLinus Torvalds } 28826e08d5e3SYuchung Cheng 28836e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 28846e08d5e3SYuchung Cheng tp->undo_retrans = 0; 28856e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 28861da177e4SLinus Torvalds return err; 28871da177e4SLinus Torvalds } 28881da177e4SLinus Torvalds 28891da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 28901da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 28911da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 28921da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 28931da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 28941da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 28951da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 28961da177e4SLinus Torvalds */ 28971da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 28981da177e4SLinus Torvalds { 28996687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 29001da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 29011da177e4SLinus Torvalds struct sk_buff *skb; 29020e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2903840a3cbeSYuchung Cheng u32 max_segs; 290461eb55f4SIlpo Järvinen int mib_idx; 29056a438bbeSStephen Hemminger 290645e77d31SIlpo Järvinen if (!tp->packets_out) 290745e77d31SIlpo Järvinen return; 290845e77d31SIlpo Järvinen 2909618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 29106a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2911618d9f25SIlpo Järvinen } else { 2912fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2913618d9f25SIlpo Järvinen } 29141da177e4SLinus Torvalds 2915ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 2916fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 2917dca0aaf8SEric Dumazet __u8 sacked; 291810d3be56SEric Dumazet int segs; 29191da177e4SLinus Torvalds 2920fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2921fe067e8aSDavid S. Miller break; 2922218af599SEric Dumazet 2923218af599SEric Dumazet if (tcp_pacing_check(sk)) 2924218af599SEric Dumazet break; 2925218af599SEric Dumazet 29266a438bbeSStephen Hemminger /* we could do better than to assign each time */ 292751456b29SIan Morris if (!hole) 29286a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 29296a438bbeSStephen Hemminger 293010d3be56SEric Dumazet segs = tp->snd_cwnd - tcp_packets_in_flight(tp); 293110d3be56SEric Dumazet if (segs <= 0) 29321da177e4SLinus Torvalds return; 2933dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 2934a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 2935a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 2936a3d2e9f8SEric Dumazet */ 2937a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 29380e1c54c2SIlpo Järvinen 2939840a3cbeSYuchung Cheng if (tp->retrans_out >= tp->lost_out) { 2940006f582cSIlpo Järvinen break; 29410e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 294251456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 29430e1c54c2SIlpo Järvinen hole = skb; 294461eb55f4SIlpo Järvinen continue; 29451da177e4SLinus Torvalds 29460e1c54c2SIlpo Järvinen } else { 29470e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 29480e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 29490e1c54c2SIlpo Järvinen else 29500e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 29510e1c54c2SIlpo Järvinen } 29520e1c54c2SIlpo Järvinen 29530e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 295461eb55f4SIlpo Järvinen continue; 295540b215e5SPavel Emelyanov 2956f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 2957f9616c35SEric Dumazet return; 2958f9616c35SEric Dumazet 295910d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 29601da177e4SLinus Torvalds return; 296124ab6becSYuchung Cheng 2962de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 29631da177e4SLinus Torvalds 2964684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2965a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2966a262f0cdSNandita Dukkipati 296757dde7f7SYuchung Cheng if (skb == tcp_write_queue_head(sk) && 296857dde7f7SYuchung Cheng icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) 2969463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 29703f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 29713f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 29721da177e4SLinus Torvalds } 29731da177e4SLinus Torvalds } 29741da177e4SLinus Torvalds 2975d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 2976d83769a5SEric Dumazet * connection tear down and (memory) recovery. 2977845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 2978845704a5SEric Dumazet * or even be forced to close flow without any FIN. 2979a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 2980a6c5ea4cSEric Dumazet * with edge trigger epoll() 2981d83769a5SEric Dumazet */ 2982a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 2983d83769a5SEric Dumazet { 2984e805605cSJohannes Weiner int amt; 2985d83769a5SEric Dumazet 2986d83769a5SEric Dumazet if (size <= sk->sk_forward_alloc) 2987d83769a5SEric Dumazet return; 2988d83769a5SEric Dumazet amt = sk_mem_pages(size); 2989d83769a5SEric Dumazet sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; 2990e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 2991e805605cSJohannes Weiner 2992baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 2993baac50bbSJohannes Weiner mem_cgroup_charge_skmem(sk->sk_memcg, amt); 2994d83769a5SEric Dumazet } 2995d83769a5SEric Dumazet 2996845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 2997845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 29981da177e4SLinus Torvalds */ 29991da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 30001da177e4SLinus Torvalds { 3001845704a5SEric Dumazet struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); 30021da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 30031da177e4SLinus Torvalds 3004845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 3005845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 3006845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 3007845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 30081da177e4SLinus Torvalds */ 3009b8da51ebSEric Dumazet if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) { 3010845704a5SEric Dumazet coalesce: 3011845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 3012845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 30131da177e4SLinus Torvalds tp->write_seq++; 3014845704a5SEric Dumazet if (!tcp_send_head(sk)) { 3015845704a5SEric Dumazet /* This means tskb was already sent. 3016845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 3017845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 3018845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 3019845704a5SEric Dumazet * does not change tp->snd_nxt. 3020845704a5SEric Dumazet */ 3021845704a5SEric Dumazet tp->snd_nxt++; 3022845704a5SEric Dumazet return; 3023845704a5SEric Dumazet } 30241da177e4SLinus Torvalds } else { 3025845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3026845704a5SEric Dumazet if (unlikely(!skb)) { 3027845704a5SEric Dumazet if (tskb) 3028845704a5SEric Dumazet goto coalesce; 3029845704a5SEric Dumazet return; 30301da177e4SLinus Torvalds } 3031d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3032a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 30331da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3034e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3035a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 30361da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 30371da177e4SLinus Torvalds } 3038845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 30391da177e4SLinus Torvalds } 30401da177e4SLinus Torvalds 30411da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 30421da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 30431da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 304465bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 30451da177e4SLinus Torvalds */ 3046dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 30471da177e4SLinus Torvalds { 30481da177e4SLinus Torvalds struct sk_buff *skb; 30491da177e4SLinus Torvalds 30507cc2b043SGao Feng TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 30517cc2b043SGao Feng 30521da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 30531da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 30541da177e4SLinus Torvalds if (!skb) { 30554e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 30561da177e4SLinus Torvalds return; 30571da177e4SLinus Torvalds } 30581da177e4SLinus Torvalds 30591da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 30601da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3061e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3062a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 30639a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 30641da177e4SLinus Torvalds /* Send it off. */ 3065dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 30664e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 30671da177e4SLinus Torvalds } 30681da177e4SLinus Torvalds 306967edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 307067edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 30711da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 30721da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 30731da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 30741da177e4SLinus Torvalds */ 30751da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 30761da177e4SLinus Torvalds { 30771da177e4SLinus Torvalds struct sk_buff *skb; 30781da177e4SLinus Torvalds 3079fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 308051456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 308191df42beSJoe Perches pr_debug("%s: wrong queue state\n", __func__); 30821da177e4SLinus Torvalds return -EFAULT; 30831da177e4SLinus Torvalds } 30844de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 30851da177e4SLinus Torvalds if (skb_cloned(skb)) { 30861da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 308751456b29SIan Morris if (!nskb) 30881da177e4SLinus Torvalds return -ENOMEM; 3089fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 3090f4a775d1SEric Dumazet __skb_header_release(nskb); 3091fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 30923ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 30933ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 30943ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 30951da177e4SLinus Torvalds skb = nskb; 30961da177e4SLinus Torvalds } 30971da177e4SLinus Torvalds 30984de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3099735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 31001da177e4SLinus Torvalds } 3101dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 31021da177e4SLinus Torvalds } 31031da177e4SLinus Torvalds 31044aea39c1SEric Dumazet /** 31054aea39c1SEric Dumazet * tcp_make_synack - Prepare a SYN-ACK. 31064aea39c1SEric Dumazet * sk: listener socket 31074aea39c1SEric Dumazet * dst: dst entry attached to the SYNACK 31084aea39c1SEric Dumazet * req: request_sock pointer 31094aea39c1SEric Dumazet * 31104aea39c1SEric Dumazet * Allocate one skb and build a SYNACK packet. 31114aea39c1SEric Dumazet * @dst is consumed : Caller should not use it again. 31124aea39c1SEric Dumazet */ 31135d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3114e6b4d113SWilliam Allen Simpson struct request_sock *req, 3115ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3116b3d05147SEric Dumazet enum tcp_synack_type synack_type) 31171da177e4SLinus Torvalds { 31182e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 31195d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 312080f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 31215d062de7SEric Dumazet struct tcp_out_options opts; 31225d062de7SEric Dumazet struct sk_buff *skb; 3123bd0388aeSWilliam Allen Simpson int tcp_header_size; 31245d062de7SEric Dumazet struct tcphdr *th; 3125f5fff5dcSTom Quetchenbach int mss; 31261da177e4SLinus Torvalds 3127ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 31284aea39c1SEric Dumazet if (unlikely(!skb)) { 31294aea39c1SEric Dumazet dst_release(dst); 31301da177e4SLinus Torvalds return NULL; 31314aea39c1SEric Dumazet } 31321da177e4SLinus Torvalds /* Reserve space for headers. */ 31331da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 31341da177e4SLinus Torvalds 3135b3d05147SEric Dumazet switch (synack_type) { 3136b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 31379e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3138b3d05147SEric Dumazet break; 3139b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3140b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3141b3d05147SEric Dumazet * to avoid false sharing. 3142b3d05147SEric Dumazet */ 3143b3d05147SEric Dumazet break; 3144b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3145ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3146ca6fb065SEric Dumazet * cpu might call us concurrently. 3147ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3148ca6fb065SEric Dumazet */ 3149ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3150b3d05147SEric Dumazet break; 3151ca6fb065SEric Dumazet } 31524aea39c1SEric Dumazet skb_dst_set(skb, dst); 31531da177e4SLinus Torvalds 31543541f9e8SEric Dumazet mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3155f5fff5dcSTom Quetchenbach 315633ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 31578b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 31588b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 31599a568de4SEric Dumazet skb->skb_mstamp = cookie_init_timestamp(req); 31608b5f12d0SFlorian Westphal else 31618b5f12d0SFlorian Westphal #endif 31629a568de4SEric Dumazet skb->skb_mstamp = tcp_clock_us(); 316380f03e27SEric Dumazet 316480f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 316580f03e27SEric Dumazet rcu_read_lock(); 3166fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 316780f03e27SEric Dumazet #endif 316858d607d3SEric Dumazet skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); 316937bfbddaSEric Dumazet tcp_header_size = tcp_synack_options(req, mss, skb, &opts, md5, foc) + 317037bfbddaSEric Dumazet sizeof(*th); 317133ad798cSAdam Langley 3172aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3173aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 31741da177e4SLinus Torvalds 3175ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 31761da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 31771da177e4SLinus Torvalds th->syn = 1; 31781da177e4SLinus Torvalds th->ack = 1; 31796ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3180b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3181634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3182e05a90ecSJamal Hadi Salim skb->mark = ireq->ir_mark; 3183e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 3184e870a8efSIlpo Järvinen * not even correctly set) 3185e870a8efSIlpo Järvinen */ 3186e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 3187a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 31884957faadSWilliam Allen Simpson 31891da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 31908336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 31918336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 31921da177e4SLinus Torvalds 31931da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3194ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 31955d062de7SEric Dumazet tcp_options_write((__be32 *)(th + 1), NULL, &opts); 31961da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 319790bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3198cfb6eeb4SYOSHIFUJI Hideaki 3199cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3200cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 320180f03e27SEric Dumazet if (md5) 3202bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 320339f8e58eSEric Dumazet md5, req_to_sk(req), skb); 320480f03e27SEric Dumazet rcu_read_unlock(); 3205cfb6eeb4SYOSHIFUJI Hideaki #endif 3206cfb6eeb4SYOSHIFUJI Hideaki 3207b50edd78SEric Dumazet /* Do not fool tcpdump (if any), clean our debris */ 32082456e855SThomas Gleixner skb->tstamp = 0; 32091da177e4SLinus Torvalds return skb; 32101da177e4SLinus Torvalds } 32114bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 32121da177e4SLinus Torvalds 321381164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 321481164413SDaniel Borkmann { 321581164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 321681164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 321781164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 321881164413SDaniel Borkmann 321981164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 322081164413SDaniel Borkmann return; 322181164413SDaniel Borkmann 322281164413SDaniel Borkmann rcu_read_lock(); 322381164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 322481164413SDaniel Borkmann if (likely(ca && try_module_get(ca->owner))) { 322581164413SDaniel Borkmann module_put(icsk->icsk_ca_ops->owner); 322681164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 322781164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 322881164413SDaniel Borkmann } 322981164413SDaniel Borkmann rcu_read_unlock(); 323081164413SDaniel Borkmann } 323181164413SDaniel Borkmann 323267edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3233f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 32341da177e4SLinus Torvalds { 3235cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 32361da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 32371da177e4SLinus Torvalds __u8 rcv_wscale; 323813d3b1ebSLawrence Brakmo u32 rcv_wnd; 32391da177e4SLinus Torvalds 32401da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 32411da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 32421da177e4SLinus Torvalds */ 32435d2ed052SEric Dumazet tp->tcp_header_len = sizeof(struct tcphdr); 32445d2ed052SEric Dumazet if (sock_net(sk)->ipv4.sysctl_tcp_timestamps) 32455d2ed052SEric Dumazet tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; 32461da177e4SLinus Torvalds 3247cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 324800db4124SIan Morris if (tp->af_specific->md5_lookup(sk, sk)) 3249cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 3250cfb6eeb4SYOSHIFUJI Hideaki #endif 3251cfb6eeb4SYOSHIFUJI Hideaki 32521da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 32531da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 32541da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 32551da177e4SLinus Torvalds tp->max_window = 0; 32565d424d5aSJohn Heffner tcp_mtup_init(sk); 32571da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 32581da177e4SLinus Torvalds 325981164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 326081164413SDaniel Borkmann 32611da177e4SLinus Torvalds if (!tp->window_clamp) 32621da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 32633541f9e8SEric Dumazet tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3264f5fff5dcSTom Quetchenbach 32651da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 32661da177e4SLinus Torvalds 3267e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3268e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3269e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3270e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3271e88c64f0SHagen Paul Pfeifer 327213d3b1ebSLawrence Brakmo rcv_wnd = tcp_rwnd_init_bpf(sk); 327313d3b1ebSLawrence Brakmo if (rcv_wnd == 0) 327413d3b1ebSLawrence Brakmo rcv_wnd = dst_metric(dst, RTAX_INITRWND); 327513d3b1ebSLawrence Brakmo 32761da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 32771da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 32781da177e4SLinus Torvalds &tp->rcv_wnd, 32791da177e4SLinus Torvalds &tp->window_clamp, 32809bb37ef0SEric Dumazet sock_net(sk)->ipv4.sysctl_tcp_window_scaling, 328131d12926Slaurent chavey &rcv_wscale, 328213d3b1ebSLawrence Brakmo rcv_wnd); 32831da177e4SLinus Torvalds 32841da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 32851da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 32861da177e4SLinus Torvalds 32871da177e4SLinus Torvalds sk->sk_err = 0; 32881da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 32891da177e4SLinus Torvalds tp->snd_wnd = 0; 3290ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 32911da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 32921da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 329333f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3294370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 3295ee995283SPavel Emelyanov 3296ee995283SPavel Emelyanov if (likely(!tp->repair)) 32971da177e4SLinus Torvalds tp->rcv_nxt = 0; 3298c7781a6eSAndrew Vagin else 329970eabf0eSEric Dumazet tp->rcv_tstamp = tcp_jiffies32; 3300ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 3301ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 33021da177e4SLinus Torvalds 33038550f328SLawrence Brakmo inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); 3304463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 33051da177e4SLinus Torvalds tcp_clear_retrans(tp); 33061da177e4SLinus Torvalds } 33071da177e4SLinus Torvalds 3308783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3309783237e8SYuchung Cheng { 3310783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3311783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3312783237e8SYuchung Cheng 3313783237e8SYuchung Cheng tcb->end_seq += skb->len; 3314f4a775d1SEric Dumazet __skb_header_release(skb); 3315783237e8SYuchung Cheng __tcp_add_write_queue_tail(sk, skb); 3316783237e8SYuchung Cheng sk->sk_wmem_queued += skb->truesize; 3317783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 3318783237e8SYuchung Cheng tp->write_seq = tcb->end_seq; 3319783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3320783237e8SYuchung Cheng } 3321783237e8SYuchung Cheng 3322783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3323783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3324783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3325783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3326783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3327783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3328783237e8SYuchung Cheng */ 3329783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3330783237e8SYuchung Cheng { 3331783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3332783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 3333065263f4SWei Wang int space, err = 0; 3334355a901eSEric Dumazet struct sk_buff *syn_data; 3335783237e8SYuchung Cheng 333667da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3337065263f4SWei Wang if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) 3338783237e8SYuchung Cheng goto fallback; 3339783237e8SYuchung Cheng 3340783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3341783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3342783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3343783237e8SYuchung Cheng */ 33443541f9e8SEric Dumazet tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); 33453541f9e8SEric Dumazet 33461b63edd6SYuchung Cheng space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - 3347783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3348783237e8SYuchung Cheng 3349f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3350f5ddcbbbSEric Dumazet 3351f5ddcbbbSEric Dumazet /* limit to order-0 allocations */ 3352f5ddcbbbSEric Dumazet space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); 3353f5ddcbbbSEric Dumazet 3354eb934478SEric Dumazet syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); 3355355a901eSEric Dumazet if (!syn_data) 3356783237e8SYuchung Cheng goto fallback; 3357355a901eSEric Dumazet syn_data->ip_summed = CHECKSUM_PARTIAL; 3358355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 335907e100f9SEric Dumazet if (space) { 336007e100f9SEric Dumazet int copied = copy_from_iter(skb_put(syn_data, space), space, 336157be5bdaSAl Viro &fo->data->msg_iter); 336257be5bdaSAl Viro if (unlikely(!copied)) { 3363355a901eSEric Dumazet kfree_skb(syn_data); 3364783237e8SYuchung Cheng goto fallback; 3365783237e8SYuchung Cheng } 336657be5bdaSAl Viro if (copied != space) { 336757be5bdaSAl Viro skb_trim(syn_data, copied); 336857be5bdaSAl Viro space = copied; 336957be5bdaSAl Viro } 337007e100f9SEric Dumazet } 3371355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3372355a901eSEric Dumazet if (space == fo->size) 3373355a901eSEric Dumazet fo->data = NULL; 3374355a901eSEric Dumazet fo->copied = space; 3375783237e8SYuchung Cheng 3376355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 33770f87230dSFrancis Yan if (syn_data->len) 33780f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3379355a901eSEric Dumazet 3380355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3381355a901eSEric Dumazet 3382355a901eSEric Dumazet syn->skb_mstamp = syn_data->skb_mstamp; 3383355a901eSEric Dumazet 3384355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3385355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3386355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3387355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3388431a9124SEric Dumazet */ 3389355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3390355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3391355a901eSEric Dumazet if (!err) { 339267da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 3393f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3394783237e8SYuchung Cheng goto done; 3395783237e8SYuchung Cheng } 3396783237e8SYuchung Cheng 3397b5b7db8dSEric Dumazet /* data was not sent, this is our new send_head */ 3398b5b7db8dSEric Dumazet sk->sk_send_head = syn_data; 3399b5b7db8dSEric Dumazet tp->packets_out -= tcp_skb_pcount(syn_data); 3400b5b7db8dSEric Dumazet 3401783237e8SYuchung Cheng fallback: 3402783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3403783237e8SYuchung Cheng if (fo->cookie.len > 0) 3404783237e8SYuchung Cheng fo->cookie.len = 0; 3405783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3406783237e8SYuchung Cheng if (err) 3407783237e8SYuchung Cheng tp->syn_fastopen = 0; 3408783237e8SYuchung Cheng done: 3409783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3410783237e8SYuchung Cheng return err; 3411783237e8SYuchung Cheng } 3412783237e8SYuchung Cheng 341367edfef7SAndi Kleen /* Build a SYN and send it off. */ 34141da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 34151da177e4SLinus Torvalds { 34161da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34171da177e4SLinus Torvalds struct sk_buff *buff; 3418ee586811SEric Paris int err; 34191da177e4SLinus Torvalds 34209872a4bdSLawrence Brakmo tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB); 34218ba60924SEric Dumazet 34228ba60924SEric Dumazet if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 34238ba60924SEric Dumazet return -EHOSTUNREACH; /* Routing failure or similar. */ 34248ba60924SEric Dumazet 34251da177e4SLinus Torvalds tcp_connect_init(sk); 34261da177e4SLinus Torvalds 34272b916477SAndrey Vagin if (unlikely(tp->repair)) { 34282b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 34292b916477SAndrey Vagin return 0; 34302b916477SAndrey Vagin } 34312b916477SAndrey Vagin 3432eb934478SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); 3433355a901eSEric Dumazet if (unlikely(!buff)) 34341da177e4SLinus Torvalds return -ENOBUFS; 34351da177e4SLinus Torvalds 3436a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 34379a568de4SEric Dumazet tcp_mstamp_refresh(tp); 34389a568de4SEric Dumazet tp->retrans_stamp = tcp_time_stamp(tp); 3439783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3440735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 34411da177e4SLinus Torvalds 3442783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3443783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3444783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3445ee586811SEric Paris if (err == -ECONNREFUSED) 3446ee586811SEric Paris return err; 3447bd37a088SWei Yongjun 3448bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3449bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3450bd37a088SWei Yongjun */ 3451bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 3452bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 3453b5b7db8dSEric Dumazet buff = tcp_send_head(sk); 3454b5b7db8dSEric Dumazet if (unlikely(buff)) { 3455b5b7db8dSEric Dumazet tp->snd_nxt = TCP_SKB_CB(buff)->seq; 3456b5b7db8dSEric Dumazet tp->pushed_seq = TCP_SKB_CB(buff)->seq; 3457b5b7db8dSEric Dumazet } 345881cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 34591da177e4SLinus Torvalds 34601da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 34613f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 34623f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 34631da177e4SLinus Torvalds return 0; 34641da177e4SLinus Torvalds } 34654bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 34661da177e4SLinus Torvalds 34671da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 34681da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 34691da177e4SLinus Torvalds * for details. 34701da177e4SLinus Torvalds */ 34711da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 34721da177e4SLinus Torvalds { 3473463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3474463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 34751da177e4SLinus Torvalds unsigned long timeout; 34761da177e4SLinus Torvalds 34779890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_DELAYED_ACK); 34789890092eSFlorian Westphal 34791da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3480463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 34811da177e4SLinus Torvalds int max_ato = HZ / 2; 34821da177e4SLinus Torvalds 3483056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 3484056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 34851da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 34861da177e4SLinus Torvalds 34871da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 34881da177e4SLinus Torvalds 34891da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 3490463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 34911da177e4SLinus Torvalds * directly. 34921da177e4SLinus Torvalds */ 3493740b0f18SEric Dumazet if (tp->srtt_us) { 3494740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 3495740b0f18SEric Dumazet TCP_DELACK_MIN); 34961da177e4SLinus Torvalds 34971da177e4SLinus Torvalds if (rtt < max_ato) 34981da177e4SLinus Torvalds max_ato = rtt; 34991da177e4SLinus Torvalds } 35001da177e4SLinus Torvalds 35011da177e4SLinus Torvalds ato = min(ato, max_ato); 35021da177e4SLinus Torvalds } 35031da177e4SLinus Torvalds 35041da177e4SLinus Torvalds /* Stay within the limit we were given */ 35051da177e4SLinus Torvalds timeout = jiffies + ato; 35061da177e4SLinus Torvalds 35071da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 3508463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 35091da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 35101da177e4SLinus Torvalds * send ACK now. 35111da177e4SLinus Torvalds */ 3512463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 3513463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 35141da177e4SLinus Torvalds tcp_send_ack(sk); 35151da177e4SLinus Torvalds return; 35161da177e4SLinus Torvalds } 35171da177e4SLinus Torvalds 3518463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 3519463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 35201da177e4SLinus Torvalds } 3521463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 3522463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 3523463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 35241da177e4SLinus Torvalds } 35251da177e4SLinus Torvalds 35261da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 35271da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 35281da177e4SLinus Torvalds { 35291da177e4SLinus Torvalds struct sk_buff *buff; 35301da177e4SLinus Torvalds 3531058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 3532058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3533058dc334SIlpo Järvinen return; 3534058dc334SIlpo Järvinen 35359890092eSFlorian Westphal tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK); 35369890092eSFlorian Westphal 35371da177e4SLinus Torvalds /* We are not putting this on the write queue, so 35381da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 35391da177e4SLinus Torvalds * sock. 35401da177e4SLinus Torvalds */ 35417450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 35427450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 35437450aaf6SEric Dumazet if (unlikely(!buff)) { 3544463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 3545463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 35463f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 35473f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 35481da177e4SLinus Torvalds return; 35491da177e4SLinus Torvalds } 35501da177e4SLinus Torvalds 35511da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 35521da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 3553a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 35541da177e4SLinus Torvalds 355598781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 355698781965SEric Dumazet * too much. 355798781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 355898781965SEric Dumazet */ 355998781965SEric Dumazet skb_set_tcp_pure_ack(buff); 356098781965SEric Dumazet 35611da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 35627450aaf6SEric Dumazet tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0); 35631da177e4SLinus Torvalds } 3564e3118e83SDaniel Borkmann EXPORT_SYMBOL_GPL(tcp_send_ack); 35651da177e4SLinus Torvalds 35661da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 35671da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 35681da177e4SLinus Torvalds * 35691da177e4SLinus Torvalds * Question: what should we make while urgent mode? 35701da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 35711da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 35721da177e4SLinus Torvalds * 35731da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 35741da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 35751da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 35761da177e4SLinus Torvalds */ 3577e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 35781da177e4SLinus Torvalds { 35791da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 35801da177e4SLinus Torvalds struct sk_buff *skb; 35811da177e4SLinus Torvalds 35821da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 35837450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 35847450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 358551456b29SIan Morris if (!skb) 35861da177e4SLinus Torvalds return -1; 35871da177e4SLinus Torvalds 35881da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 35891da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 35901da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 35911da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 35921da177e4SLinus Torvalds * send it. 35931da177e4SLinus Torvalds */ 3594a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 3595e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 35967450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 35971da177e4SLinus Torvalds } 35981da177e4SLinus Torvalds 3599385e2070SEric Dumazet /* Called from setsockopt( ... TCP_REPAIR ) */ 3600ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 3601ee995283SPavel Emelyanov { 3602ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 3603ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 36049a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 3605e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 3606ee995283SPavel Emelyanov } 3607ee995283SPavel Emelyanov } 3608ee995283SPavel Emelyanov 360967edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 3610e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 36111da177e4SLinus Torvalds { 36121da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 36131da177e4SLinus Torvalds struct sk_buff *skb; 36141da177e4SLinus Torvalds 3615058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 3616058dc334SIlpo Järvinen return -1; 3617058dc334SIlpo Järvinen 361800db4124SIan Morris skb = tcp_send_head(sk); 361900db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 36201da177e4SLinus Torvalds int err; 36210c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 362290840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 36231da177e4SLinus Torvalds 36241da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 36251da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 36261da177e4SLinus Torvalds 36271da177e4SLinus Torvalds /* We are probing the opening of a window 36281da177e4SLinus Torvalds * but the window size is != 0 36291da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 36301da177e4SLinus Torvalds */ 36311da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 36321da177e4SLinus Torvalds skb->len > mss) { 36331da177e4SLinus Torvalds seg_size = min(seg_size, mss); 36344de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 36356cc55e09SOctavian Purdila if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) 36361da177e4SLinus Torvalds return -1; 36371da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 36385bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 36391da177e4SLinus Torvalds 36404de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 3641dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 364266f5fe62SIlpo Järvinen if (!err) 364366f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 36441da177e4SLinus Torvalds return err; 36451da177e4SLinus Torvalds } else { 364633f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 3647e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 3648e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 36491da177e4SLinus Torvalds } 36501da177e4SLinus Torvalds } 36511da177e4SLinus Torvalds 36521da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 36531da177e4SLinus Torvalds * a partial packet else a zero probe. 36541da177e4SLinus Torvalds */ 36551da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 36561da177e4SLinus Torvalds { 3657463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 36581da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3659c6214a97SNikolay Borisov struct net *net = sock_net(sk); 3660fcdd1cf4SEric Dumazet unsigned long probe_max; 36611da177e4SLinus Torvalds int err; 36621da177e4SLinus Torvalds 3663e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 36641da177e4SLinus Torvalds 3665fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 36661da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 36676687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 3668463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 36691da177e4SLinus Torvalds return; 36701da177e4SLinus Torvalds } 36711da177e4SLinus Torvalds 36721da177e4SLinus Torvalds if (err <= 0) { 3673c6214a97SNikolay Borisov if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) 3674463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 36756687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 3676fcdd1cf4SEric Dumazet probe_max = TCP_RTO_MAX; 36771da177e4SLinus Torvalds } else { 36781da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 36796687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 36801da177e4SLinus Torvalds * Let local senders to fight for local resources. 36811da177e4SLinus Torvalds * 36821da177e4SLinus Torvalds * Use accumulated backoff yet. 36831da177e4SLinus Torvalds */ 36846687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 36856687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 3686fcdd1cf4SEric Dumazet probe_max = TCP_RESOURCE_PROBE_INTERVAL; 36871da177e4SLinus Torvalds } 3688fcdd1cf4SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 368921c8fe99SEric Dumazet tcp_probe0_when(sk, probe_max), 3690fcdd1cf4SEric Dumazet TCP_RTO_MAX); 36911da177e4SLinus Torvalds } 36925db92c99SOctavian Purdila 3693ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 36945db92c99SOctavian Purdila { 36955db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 36965db92c99SOctavian Purdila struct flowi fl; 36975db92c99SOctavian Purdila int res; 36985db92c99SOctavian Purdila 369958d607d3SEric Dumazet tcp_rsk(req)->txhash = net_tx_rndhash(); 3700b3d05147SEric Dumazet res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); 37015db92c99SOctavian Purdila if (!res) { 370290bbcc60SEric Dumazet __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 370302a1d6e7SEric Dumazet __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 37047e32b443SYuchung Cheng if (unlikely(tcp_passive_fastopen(sk))) 37057e32b443SYuchung Cheng tcp_sk(sk)->total_retrans++; 37065db92c99SOctavian Purdila } 37075db92c99SOctavian Purdila return res; 37085db92c99SOctavian Purdila } 37095db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 3710