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 * 81da177e4SLinus Torvalds * Version: $Id: tcp_output.c,v 1.146 2002/02/01 22:01:04 davem Exp $ 91da177e4SLinus Torvalds * 1002c30a84SJesper Juhl * Authors: Ross Biro 111da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 121da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 131da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 141da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 151da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 161da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 171da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 181da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 191da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 201da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 211da177e4SLinus Torvalds */ 221da177e4SLinus Torvalds 231da177e4SLinus Torvalds /* 241da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 251da177e4SLinus Torvalds * : Fragmentation on mtu decrease 261da177e4SLinus Torvalds * : Segment collapse on retransmit 271da177e4SLinus Torvalds * : AF independence 281da177e4SLinus Torvalds * 291da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 301da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 311da177e4SLinus Torvalds * during syn/ack processing. 321da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 331da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 341da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 351da177e4SLinus Torvalds * J Hadi Salim : ECN support 361da177e4SLinus Torvalds * 371da177e4SLinus Torvalds */ 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds #include <net/tcp.h> 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds #include <linux/compiler.h> 421da177e4SLinus Torvalds #include <linux/module.h> 431da177e4SLinus Torvalds #include <linux/smp_lock.h> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 461da177e4SLinus Torvalds int sysctl_tcp_retrans_collapse = 1; 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 491da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 501da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 511da177e4SLinus Torvalds */ 52c1b4a7e6SDavid S. Miller int sysctl_tcp_tso_win_divisor = 3; 531da177e4SLinus Torvalds 541da177e4SLinus Torvalds static inline void update_send_head(struct sock *sk, struct tcp_sock *tp, 551da177e4SLinus Torvalds struct sk_buff *skb) 561da177e4SLinus Torvalds { 571da177e4SLinus Torvalds sk->sk_send_head = skb->next; 581da177e4SLinus Torvalds if (sk->sk_send_head == (struct sk_buff *)&sk->sk_write_queue) 591da177e4SLinus Torvalds sk->sk_send_head = NULL; 601da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 611da177e4SLinus Torvalds tcp_packets_out_inc(sk, tp, skb); 621da177e4SLinus Torvalds } 631da177e4SLinus Torvalds 641da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 651da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 661da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 671da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 681da177e4SLinus Torvalds * invalid. OK, let's make this for now: 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds static inline __u32 tcp_acceptable_seq(struct sock *sk, struct tcp_sock *tp) 711da177e4SLinus Torvalds { 721da177e4SLinus Torvalds if (!before(tp->snd_una+tp->snd_wnd, tp->snd_nxt)) 731da177e4SLinus Torvalds return tp->snd_nxt; 741da177e4SLinus Torvalds else 751da177e4SLinus Torvalds return tp->snd_una+tp->snd_wnd; 761da177e4SLinus Torvalds } 771da177e4SLinus Torvalds 781da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 791da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 801da177e4SLinus Torvalds * 811da177e4SLinus Torvalds * 1. It is independent of path mtu. 821da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 831da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 841da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 851da177e4SLinus Torvalds * large MSS. 861da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 871da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 881da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 891da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 901da177e4SLinus Torvalds * probably even Jumbo". 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 931da177e4SLinus Torvalds { 941da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 951da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 961da177e4SLinus Torvalds int mss = tp->advmss; 971da177e4SLinus Torvalds 981da177e4SLinus Torvalds if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { 991da177e4SLinus Torvalds mss = dst_metric(dst, RTAX_ADVMSS); 1001da177e4SLinus Torvalds tp->advmss = mss; 1011da177e4SLinus Torvalds } 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds return (__u16)mss; 1041da177e4SLinus Torvalds } 1051da177e4SLinus Torvalds 1061da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1071da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 1081da177e4SLinus Torvalds static void tcp_cwnd_restart(struct tcp_sock *tp, struct dst_entry *dst) 1091da177e4SLinus Torvalds { 1101da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1111da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1121da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1131da177e4SLinus Torvalds 114317a76f9SStephen Hemminger tcp_ca_event(tp, CA_EVENT_CWND_RESTART); 1151da177e4SLinus Torvalds 1161da177e4SLinus Torvalds tp->snd_ssthresh = tcp_current_ssthresh(tp); 1171da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1181da177e4SLinus Torvalds 1191da177e4SLinus Torvalds while ((delta -= tp->rto) > 0 && cwnd > restart_cwnd) 1201da177e4SLinus Torvalds cwnd >>= 1; 1211da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1221da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1231da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1241da177e4SLinus Torvalds } 1251da177e4SLinus Torvalds 1261da177e4SLinus Torvalds static inline void tcp_event_data_sent(struct tcp_sock *tp, 1271da177e4SLinus Torvalds struct sk_buff *skb, struct sock *sk) 1281da177e4SLinus Torvalds { 1291da177e4SLinus Torvalds u32 now = tcp_time_stamp; 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds if (!tp->packets_out && (s32)(now - tp->lsndtime) > tp->rto) 1321da177e4SLinus Torvalds tcp_cwnd_restart(tp, __sk_dst_get(sk)); 1331da177e4SLinus Torvalds 1341da177e4SLinus Torvalds tp->lsndtime = now; 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds /* If it is a reply for ato after last received 1371da177e4SLinus Torvalds * packet, enter pingpong mode. 1381da177e4SLinus Torvalds */ 1391da177e4SLinus Torvalds if ((u32)(now - tp->ack.lrcvtime) < tp->ack.ato) 1401da177e4SLinus Torvalds tp->ack.pingpong = 1; 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds 143fc6415bcSDavid S. Miller static __inline__ void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1441da177e4SLinus Torvalds { 1451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1461da177e4SLinus Torvalds 147fc6415bcSDavid S. Miller tcp_dec_quickack_mode(tp, pkts); 1481da177e4SLinus Torvalds tcp_clear_xmit_timer(sk, TCP_TIME_DACK); 1491da177e4SLinus Torvalds } 1501da177e4SLinus Torvalds 1511da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 1521da177e4SLinus Torvalds * Based on the assumption that the given amount of space 1531da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 1541da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 1551da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 1561da177e4SLinus Torvalds * This MUST be enforced by all callers. 1571da177e4SLinus Torvalds */ 1581da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 1591da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 1601da177e4SLinus Torvalds int wscale_ok, __u8 *rcv_wscale) 1611da177e4SLinus Torvalds { 1621da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 1631da177e4SLinus Torvalds 1641da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 1651da177e4SLinus Torvalds if (*window_clamp == 0) 1661da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 1671da177e4SLinus Torvalds space = min(*window_clamp, space); 1681da177e4SLinus Torvalds 1691da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 1701da177e4SLinus Torvalds if (space > mss) 1711da177e4SLinus Torvalds space = (space / mss) * mss; 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 1741da177e4SLinus Torvalds * will break some buggy TCP stacks. We try to be nice. 1751da177e4SLinus Torvalds * If we are not window scaling, then this truncates 1761da177e4SLinus Torvalds * our initial window offering to 32k. There should also 1771da177e4SLinus Torvalds * be a sysctl option to stop being nice. 1781da177e4SLinus Torvalds */ 1791da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 1801da177e4SLinus Torvalds (*rcv_wscale) = 0; 1811da177e4SLinus Torvalds if (wscale_ok) { 1821da177e4SLinus Torvalds /* Set window scaling on max possible window 1831da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 1841da177e4SLinus Torvalds */ 1851da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 1861da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 1871da177e4SLinus Torvalds space >>= 1; 1881da177e4SLinus Torvalds (*rcv_wscale)++; 1891da177e4SLinus Torvalds } 1901da177e4SLinus Torvalds } 1911da177e4SLinus Torvalds 1921da177e4SLinus Torvalds /* Set initial window to value enough for senders, 1931da177e4SLinus Torvalds * following RFC1414. Senders, not following this RFC, 1941da177e4SLinus Torvalds * will be satisfied with 2. 1951da177e4SLinus Torvalds */ 1961da177e4SLinus Torvalds if (mss > (1<<*rcv_wscale)) { 1971da177e4SLinus Torvalds int init_cwnd = 4; 1981da177e4SLinus Torvalds if (mss > 1460*3) 1991da177e4SLinus Torvalds init_cwnd = 2; 2001da177e4SLinus Torvalds else if (mss > 1460) 2011da177e4SLinus Torvalds init_cwnd = 3; 2021da177e4SLinus Torvalds if (*rcv_wnd > init_cwnd*mss) 2031da177e4SLinus Torvalds *rcv_wnd = init_cwnd*mss; 2041da177e4SLinus Torvalds } 2051da177e4SLinus Torvalds 2061da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2071da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2081da177e4SLinus Torvalds } 2091da177e4SLinus Torvalds 2101da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2111da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2121da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2131da177e4SLinus Torvalds * frame. 2141da177e4SLinus Torvalds */ 2151da177e4SLinus Torvalds static __inline__ u16 tcp_select_window(struct sock *sk) 2161da177e4SLinus Torvalds { 2171da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2181da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2191da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* Never shrink the offered window */ 2221da177e4SLinus Torvalds if(new_win < cur_win) { 2231da177e4SLinus Torvalds /* Danger Will Robinson! 2241da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2251da177e4SLinus Torvalds * we will not be able to advertise a zero 2261da177e4SLinus Torvalds * window in time. --DaveM 2271da177e4SLinus Torvalds * 2281da177e4SLinus Torvalds * Relax Will Robinson. 2291da177e4SLinus Torvalds */ 2301da177e4SLinus Torvalds new_win = cur_win; 2311da177e4SLinus Torvalds } 2321da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2331da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2341da177e4SLinus Torvalds 2351da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2361da177e4SLinus Torvalds * scaled window. 2371da177e4SLinus Torvalds */ 2381da177e4SLinus Torvalds if (!tp->rx_opt.rcv_wscale) 2391da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2401da177e4SLinus Torvalds else 2411da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2441da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 2471da177e4SLinus Torvalds if (new_win == 0) 2481da177e4SLinus Torvalds tp->pred_flags = 0; 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds return new_win; 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 2551da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 2561da177e4SLinus Torvalds * transmission and possible later retransmissions. 2571da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 2581da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 2591da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 2601da177e4SLinus Torvalds * device. 2611da177e4SLinus Torvalds * 2621da177e4SLinus Torvalds * We are working here with either a clone of the original 2631da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 2641da177e4SLinus Torvalds */ 2651da177e4SLinus Torvalds static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb) 2661da177e4SLinus Torvalds { 2671da177e4SLinus Torvalds if (skb != NULL) { 2681da177e4SLinus Torvalds struct inet_sock *inet = inet_sk(sk); 2691da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2701da177e4SLinus Torvalds struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 2711da177e4SLinus Torvalds int tcp_header_size = tp->tcp_header_len; 2721da177e4SLinus Torvalds struct tcphdr *th; 2731da177e4SLinus Torvalds int sysctl_flags; 2741da177e4SLinus Torvalds int err; 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds BUG_ON(!tcp_skb_pcount(skb)); 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds #define SYSCTL_FLAG_TSTAMPS 0x1 2791da177e4SLinus Torvalds #define SYSCTL_FLAG_WSCALE 0x2 2801da177e4SLinus Torvalds #define SYSCTL_FLAG_SACK 0x4 2811da177e4SLinus Torvalds 282317a76f9SStephen Hemminger /* If congestion control is doing timestamping */ 283317a76f9SStephen Hemminger if (tp->ca_ops->rtt_sample) 284317a76f9SStephen Hemminger do_gettimeofday(&skb->stamp); 285317a76f9SStephen Hemminger 2861da177e4SLinus Torvalds sysctl_flags = 0; 2871da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_SYN) { 2881da177e4SLinus Torvalds tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS; 2891da177e4SLinus Torvalds if(sysctl_tcp_timestamps) { 2901da177e4SLinus Torvalds tcp_header_size += TCPOLEN_TSTAMP_ALIGNED; 2911da177e4SLinus Torvalds sysctl_flags |= SYSCTL_FLAG_TSTAMPS; 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds if(sysctl_tcp_window_scaling) { 2941da177e4SLinus Torvalds tcp_header_size += TCPOLEN_WSCALE_ALIGNED; 2951da177e4SLinus Torvalds sysctl_flags |= SYSCTL_FLAG_WSCALE; 2961da177e4SLinus Torvalds } 2971da177e4SLinus Torvalds if(sysctl_tcp_sack) { 2981da177e4SLinus Torvalds sysctl_flags |= SYSCTL_FLAG_SACK; 2991da177e4SLinus Torvalds if(!(sysctl_flags & SYSCTL_FLAG_TSTAMPS)) 3001da177e4SLinus Torvalds tcp_header_size += TCPOLEN_SACKPERM_ALIGNED; 3011da177e4SLinus Torvalds } 3021da177e4SLinus Torvalds } else if (tp->rx_opt.eff_sacks) { 3031da177e4SLinus Torvalds /* A SACK is 2 pad bytes, a 2 byte header, plus 3041da177e4SLinus Torvalds * 2 32-bit sequence numbers for each SACK block. 3051da177e4SLinus Torvalds */ 3061da177e4SLinus Torvalds tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED + 3071da177e4SLinus Torvalds (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); 3081da177e4SLinus Torvalds } 3091da177e4SLinus Torvalds 310317a76f9SStephen Hemminger if (tcp_packets_in_flight(tp) == 0) 311317a76f9SStephen Hemminger tcp_ca_event(tp, CA_EVENT_TX_START); 3121da177e4SLinus Torvalds 3131da177e4SLinus Torvalds th = (struct tcphdr *) skb_push(skb, tcp_header_size); 3141da177e4SLinus Torvalds skb->h.th = th; 3151da177e4SLinus Torvalds skb_set_owner_w(skb, sk); 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 3181da177e4SLinus Torvalds th->source = inet->sport; 3191da177e4SLinus Torvalds th->dest = inet->dport; 3201da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 3211da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 3221da177e4SLinus Torvalds *(((__u16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | tcb->flags); 3231da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_SYN) { 3241da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 3251da177e4SLinus Torvalds * is never scaled. 3261da177e4SLinus Torvalds */ 3271da177e4SLinus Torvalds th->window = htons(tp->rcv_wnd); 3281da177e4SLinus Torvalds } else { 3291da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 3301da177e4SLinus Torvalds } 3311da177e4SLinus Torvalds th->check = 0; 3321da177e4SLinus Torvalds th->urg_ptr = 0; 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds if (tp->urg_mode && 3351da177e4SLinus Torvalds between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF)) { 3361da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up-tcb->seq); 3371da177e4SLinus Torvalds th->urg = 1; 3381da177e4SLinus Torvalds } 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_SYN) { 3411da177e4SLinus Torvalds tcp_syn_build_options((__u32 *)(th + 1), 3421da177e4SLinus Torvalds tcp_advertise_mss(sk), 3431da177e4SLinus Torvalds (sysctl_flags & SYSCTL_FLAG_TSTAMPS), 3441da177e4SLinus Torvalds (sysctl_flags & SYSCTL_FLAG_SACK), 3451da177e4SLinus Torvalds (sysctl_flags & SYSCTL_FLAG_WSCALE), 3461da177e4SLinus Torvalds tp->rx_opt.rcv_wscale, 3471da177e4SLinus Torvalds tcb->when, 3481da177e4SLinus Torvalds tp->rx_opt.ts_recent); 3491da177e4SLinus Torvalds } else { 3501da177e4SLinus Torvalds tcp_build_and_update_options((__u32 *)(th + 1), 3511da177e4SLinus Torvalds tp, tcb->when); 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds TCP_ECN_send(sk, tp, skb, tcp_header_size); 3541da177e4SLinus Torvalds } 3551da177e4SLinus Torvalds tp->af_specific->send_check(sk, th, skb->len, skb); 3561da177e4SLinus Torvalds 3571da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_ACK) 358fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds if (skb->len != tcp_header_size) 3611da177e4SLinus Torvalds tcp_event_data_sent(tp, skb, sk); 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_OUTSEGS); 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvalds err = tp->af_specific->queue_xmit(skb, 0); 3661da177e4SLinus Torvalds if (err <= 0) 3671da177e4SLinus Torvalds return err; 3681da177e4SLinus Torvalds 3691da177e4SLinus Torvalds tcp_enter_cwr(tp); 3701da177e4SLinus Torvalds 3711da177e4SLinus Torvalds /* NET_XMIT_CN is special. It does not guarantee, 3721da177e4SLinus Torvalds * that this packet is lost. It tells that device 3731da177e4SLinus Torvalds * is about to start to drop packets or already 3741da177e4SLinus Torvalds * drops some packets of the same priority and 3751da177e4SLinus Torvalds * invokes us to send less aggressively. 3761da177e4SLinus Torvalds */ 3771da177e4SLinus Torvalds return err == NET_XMIT_CN ? 0 : err; 3781da177e4SLinus Torvalds } 3791da177e4SLinus Torvalds return -ENOBUFS; 3801da177e4SLinus Torvalds #undef SYSCTL_FLAG_TSTAMPS 3811da177e4SLinus Torvalds #undef SYSCTL_FLAG_WSCALE 3821da177e4SLinus Torvalds #undef SYSCTL_FLAG_SACK 3831da177e4SLinus Torvalds } 3841da177e4SLinus Torvalds 3851da177e4SLinus Torvalds 3861da177e4SLinus Torvalds /* This routine just queue's the buffer 3871da177e4SLinus Torvalds * 3881da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 3891da177e4SLinus Torvalds * otherwise socket can stall. 3901da177e4SLinus Torvalds */ 3911da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 3921da177e4SLinus Torvalds { 3931da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3941da177e4SLinus Torvalds 3951da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 3961da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 3971da177e4SLinus Torvalds skb_header_release(skb); 3981da177e4SLinus Torvalds __skb_queue_tail(&sk->sk_write_queue, skb); 3991da177e4SLinus Torvalds sk_charge_skb(sk, skb); 4001da177e4SLinus Torvalds 4011da177e4SLinus Torvalds /* Queue it, remembering where we must start sending. */ 4021da177e4SLinus Torvalds if (sk->sk_send_head == NULL) 4031da177e4SLinus Torvalds sk->sk_send_head = skb; 4041da177e4SLinus Torvalds } 4051da177e4SLinus Torvalds 406846998aeSDavid S. Miller static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) 407f6302d1dSDavid S. Miller { 408846998aeSDavid S. Miller if (skb->len <= mss_now || 409f6302d1dSDavid S. Miller !(sk->sk_route_caps & NETIF_F_TSO)) { 410f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 411f6302d1dSDavid S. Miller * non-TSO case. 412f6302d1dSDavid S. Miller */ 413f6302d1dSDavid S. Miller skb_shinfo(skb)->tso_segs = 1; 414f6302d1dSDavid S. Miller skb_shinfo(skb)->tso_size = 0; 415f6302d1dSDavid S. Miller } else { 416f6302d1dSDavid S. Miller unsigned int factor; 417f6302d1dSDavid S. Miller 418846998aeSDavid S. Miller factor = skb->len + (mss_now - 1); 419846998aeSDavid S. Miller factor /= mss_now; 420f6302d1dSDavid S. Miller skb_shinfo(skb)->tso_segs = factor; 421846998aeSDavid S. Miller skb_shinfo(skb)->tso_size = mss_now; 4221da177e4SLinus Torvalds } 4231da177e4SLinus Torvalds } 4241da177e4SLinus Torvalds 4251da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 4261da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 4271da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 4281da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 4291da177e4SLinus Torvalds */ 430846998aeSDavid S. Miller static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss_now) 4311da177e4SLinus Torvalds { 4321da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 4331da177e4SLinus Torvalds struct sk_buff *buff; 4341da177e4SLinus Torvalds int nsize; 4351da177e4SLinus Torvalds u16 flags; 4361da177e4SLinus Torvalds 4371da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 4381da177e4SLinus Torvalds if (nsize < 0) 4391da177e4SLinus Torvalds nsize = 0; 4401da177e4SLinus Torvalds 4411da177e4SLinus Torvalds if (skb_cloned(skb) && 4421da177e4SLinus Torvalds skb_is_nonlinear(skb) && 4431da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 4441da177e4SLinus Torvalds return -ENOMEM; 4451da177e4SLinus Torvalds 4461da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 4471da177e4SLinus Torvalds buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); 4481da177e4SLinus Torvalds if (buff == NULL) 4491da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 4501da177e4SLinus Torvalds sk_charge_skb(sk, buff); 4511da177e4SLinus Torvalds 4521da177e4SLinus Torvalds /* Correct the sequence numbers. */ 4531da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 4541da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 4551da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 4561da177e4SLinus Torvalds 4571da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 4581da177e4SLinus Torvalds flags = TCP_SKB_CB(skb)->flags; 4591da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); 4601da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = flags; 4611da177e4SLinus Torvalds TCP_SKB_CB(buff)->sacked = 4621da177e4SLinus Torvalds (TCP_SKB_CB(skb)->sacked & 4631da177e4SLinus Torvalds (TCPCB_LOST | TCPCB_EVER_RETRANS | TCPCB_AT_TAIL)); 4641da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked &= ~TCPCB_AT_TAIL; 4651da177e4SLinus Torvalds 4661da177e4SLinus Torvalds if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_HW) { 4671da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 4681da177e4SLinus Torvalds buff->csum = csum_partial_copy_nocheck(skb->data + len, skb_put(buff, nsize), 4691da177e4SLinus Torvalds nsize, 0); 4701da177e4SLinus Torvalds 4711da177e4SLinus Torvalds skb_trim(skb, len); 4721da177e4SLinus Torvalds 4731da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 4741da177e4SLinus Torvalds } else { 4751da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_HW; 4761da177e4SLinus Torvalds skb_split(skb, buff, len); 4771da177e4SLinus Torvalds } 4781da177e4SLinus Torvalds 4791da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 4801da177e4SLinus Torvalds 4811da177e4SLinus Torvalds /* Looks stupid, but our code really uses when of 4821da177e4SLinus Torvalds * skbs, which it never sent before. --ANK 4831da177e4SLinus Torvalds */ 4841da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; 485317a76f9SStephen Hemminger buff->stamp = skb->stamp; 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { 4881da177e4SLinus Torvalds tp->lost_out -= tcp_skb_pcount(skb); 4891da177e4SLinus Torvalds tp->left_out -= tcp_skb_pcount(skb); 4901da177e4SLinus Torvalds } 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 493846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 494846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 4951da177e4SLinus Torvalds 4961da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { 4971da177e4SLinus Torvalds tp->lost_out += tcp_skb_pcount(skb); 4981da177e4SLinus Torvalds tp->left_out += tcp_skb_pcount(skb); 4991da177e4SLinus Torvalds } 5001da177e4SLinus Torvalds 5011da177e4SLinus Torvalds if (TCP_SKB_CB(buff)->sacked&TCPCB_LOST) { 5021da177e4SLinus Torvalds tp->lost_out += tcp_skb_pcount(buff); 5031da177e4SLinus Torvalds tp->left_out += tcp_skb_pcount(buff); 5041da177e4SLinus Torvalds } 5051da177e4SLinus Torvalds 5061da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 507f44b5271SDavid S. Miller skb_header_release(buff); 5081da177e4SLinus Torvalds __skb_append(skb, buff); 5091da177e4SLinus Torvalds 5101da177e4SLinus Torvalds return 0; 5111da177e4SLinus Torvalds } 5121da177e4SLinus Torvalds 5131da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 5141da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 5151da177e4SLinus Torvalds * immediately discarded. 5161da177e4SLinus Torvalds */ 5171da177e4SLinus Torvalds static unsigned char *__pskb_trim_head(struct sk_buff *skb, int len) 5181da177e4SLinus Torvalds { 5191da177e4SLinus Torvalds int i, k, eat; 5201da177e4SLinus Torvalds 5211da177e4SLinus Torvalds eat = len; 5221da177e4SLinus Torvalds k = 0; 5231da177e4SLinus Torvalds for (i=0; i<skb_shinfo(skb)->nr_frags; i++) { 5241da177e4SLinus Torvalds if (skb_shinfo(skb)->frags[i].size <= eat) { 5251da177e4SLinus Torvalds put_page(skb_shinfo(skb)->frags[i].page); 5261da177e4SLinus Torvalds eat -= skb_shinfo(skb)->frags[i].size; 5271da177e4SLinus Torvalds } else { 5281da177e4SLinus Torvalds skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 5291da177e4SLinus Torvalds if (eat) { 5301da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].page_offset += eat; 5311da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].size -= eat; 5321da177e4SLinus Torvalds eat = 0; 5331da177e4SLinus Torvalds } 5341da177e4SLinus Torvalds k++; 5351da177e4SLinus Torvalds } 5361da177e4SLinus Torvalds } 5371da177e4SLinus Torvalds skb_shinfo(skb)->nr_frags = k; 5381da177e4SLinus Torvalds 5391da177e4SLinus Torvalds skb->tail = skb->data; 5401da177e4SLinus Torvalds skb->data_len -= len; 5411da177e4SLinus Torvalds skb->len = skb->data_len; 5421da177e4SLinus Torvalds return skb->tail; 5431da177e4SLinus Torvalds } 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 5461da177e4SLinus Torvalds { 5471da177e4SLinus Torvalds if (skb_cloned(skb) && 5481da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 5491da177e4SLinus Torvalds return -ENOMEM; 5501da177e4SLinus Torvalds 5511da177e4SLinus Torvalds if (len <= skb_headlen(skb)) { 5521da177e4SLinus Torvalds __skb_pull(skb, len); 5531da177e4SLinus Torvalds } else { 5541da177e4SLinus Torvalds if (__pskb_trim_head(skb, len-skb_headlen(skb)) == NULL) 5551da177e4SLinus Torvalds return -ENOMEM; 5561da177e4SLinus Torvalds } 5571da177e4SLinus Torvalds 5581da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 5591da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_HW; 5601da177e4SLinus Torvalds 5611da177e4SLinus Torvalds skb->truesize -= len; 5621da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 5631da177e4SLinus Torvalds sk->sk_forward_alloc += len; 5641da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 5651da177e4SLinus Torvalds 5661da177e4SLinus Torvalds /* Any change of skb->len requires recalculation of tso 5671da177e4SLinus Torvalds * factor and mss. 5681da177e4SLinus Torvalds */ 5691da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 570846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1)); 5711da177e4SLinus Torvalds 5721da177e4SLinus Torvalds return 0; 5731da177e4SLinus Torvalds } 5741da177e4SLinus Torvalds 5751da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 5781da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 5791da177e4SLinus Torvalds 5801da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 5811da177e4SLinus Torvalds It is minumum of user_mss and mss received with SYN. 5821da177e4SLinus Torvalds It also does not include TCP options. 5831da177e4SLinus Torvalds 5841da177e4SLinus Torvalds tp->pmtu_cookie is last pmtu, seen by this function. 5851da177e4SLinus Torvalds 5861da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 5871da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 5881da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 5891da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 5901da177e4SLinus Torvalds 5911da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 5921da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 5931da177e4SLinus Torvalds 5941da177e4SLinus Torvalds NOTE2. tp->pmtu_cookie and tp->mss_cache are READ ONLY outside 5951da177e4SLinus Torvalds this function. --ANK (980731) 5961da177e4SLinus Torvalds */ 5971da177e4SLinus Torvalds 5981da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 5991da177e4SLinus Torvalds { 6001da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 6011da177e4SLinus Torvalds int mss_now; 6021da177e4SLinus Torvalds 6031da177e4SLinus Torvalds /* Calculate base mss without TCP options: 6041da177e4SLinus Torvalds It is MMS_S - sizeof(tcphdr) of rfc1122 6051da177e4SLinus Torvalds */ 6061da177e4SLinus Torvalds mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct tcphdr); 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds /* Clamp it (mss_clamp does not include tcp options) */ 6091da177e4SLinus Torvalds if (mss_now > tp->rx_opt.mss_clamp) 6101da177e4SLinus Torvalds mss_now = tp->rx_opt.mss_clamp; 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds /* Now subtract optional transport overhead */ 6131da177e4SLinus Torvalds mss_now -= tp->ext_header_len; 6141da177e4SLinus Torvalds 6151da177e4SLinus Torvalds /* Then reserve room for full set of TCP options and 8 bytes of data */ 6161da177e4SLinus Torvalds if (mss_now < 48) 6171da177e4SLinus Torvalds mss_now = 48; 6181da177e4SLinus Torvalds 6191da177e4SLinus Torvalds /* Now subtract TCP options size, not including SACKs */ 6201da177e4SLinus Torvalds mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); 6211da177e4SLinus Torvalds 6221da177e4SLinus Torvalds /* Bound mss with half of window */ 6231da177e4SLinus Torvalds if (tp->max_window && mss_now > (tp->max_window>>1)) 6241da177e4SLinus Torvalds mss_now = max((tp->max_window>>1), 68U - tp->tcp_header_len); 6251da177e4SLinus Torvalds 6261da177e4SLinus Torvalds /* And store cached results */ 6271da177e4SLinus Torvalds tp->pmtu_cookie = pmtu; 628c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 6291da177e4SLinus Torvalds 6301da177e4SLinus Torvalds return mss_now; 6311da177e4SLinus Torvalds } 6321da177e4SLinus Torvalds 6331da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 6341da177e4SLinus Torvalds * and even PMTU discovery events into account. 6351da177e4SLinus Torvalds * 6361da177e4SLinus Torvalds * LARGESEND note: !urg_mode is overkill, only frames up to snd_up 6371da177e4SLinus Torvalds * cannot be large. However, taking into account rare use of URG, this 6381da177e4SLinus Torvalds * is not a big flaw. 6391da177e4SLinus Torvalds */ 640c1b4a7e6SDavid S. Miller unsigned int tcp_current_mss(struct sock *sk, int large_allowed) 6411da177e4SLinus Torvalds { 6421da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 6431da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 644c1b4a7e6SDavid S. Miller u32 mss_now; 645c1b4a7e6SDavid S. Miller u16 xmit_size_goal; 646c1b4a7e6SDavid S. Miller int doing_tso = 0; 6471da177e4SLinus Torvalds 648c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 649c1b4a7e6SDavid S. Miller 650c1b4a7e6SDavid S. Miller if (large_allowed && 651c1b4a7e6SDavid S. Miller (sk->sk_route_caps & NETIF_F_TSO) && 652c1b4a7e6SDavid S. Miller !tp->urg_mode) 653c1b4a7e6SDavid S. Miller doing_tso = 1; 654c1b4a7e6SDavid S. Miller 6551da177e4SLinus Torvalds if (dst) { 6561da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 6571da177e4SLinus Torvalds if (mtu != tp->pmtu_cookie) 6581da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 6591da177e4SLinus Torvalds } 6601da177e4SLinus Torvalds 6611da177e4SLinus Torvalds if (tp->rx_opt.eff_sacks) 6621da177e4SLinus Torvalds mss_now -= (TCPOLEN_SACK_BASE_ALIGNED + 6631da177e4SLinus Torvalds (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); 664c1b4a7e6SDavid S. Miller 665c1b4a7e6SDavid S. Miller xmit_size_goal = mss_now; 666c1b4a7e6SDavid S. Miller 667c1b4a7e6SDavid S. Miller if (doing_tso) { 668c1b4a7e6SDavid S. Miller xmit_size_goal = 65535 - 669c1b4a7e6SDavid S. Miller tp->af_specific->net_header_len - 670c1b4a7e6SDavid S. Miller tp->ext_header_len - tp->tcp_header_len; 671c1b4a7e6SDavid S. Miller 672c1b4a7e6SDavid S. Miller if (tp->max_window && 673c1b4a7e6SDavid S. Miller (xmit_size_goal > (tp->max_window >> 1))) 674c1b4a7e6SDavid S. Miller xmit_size_goal = max((tp->max_window >> 1), 675c1b4a7e6SDavid S. Miller 68U - tp->tcp_header_len); 676c1b4a7e6SDavid S. Miller 677c1b4a7e6SDavid S. Miller xmit_size_goal -= (xmit_size_goal % mss_now); 678c1b4a7e6SDavid S. Miller } 679c1b4a7e6SDavid S. Miller tp->xmit_size_goal = xmit_size_goal; 680c1b4a7e6SDavid S. Miller 6811da177e4SLinus Torvalds return mss_now; 6821da177e4SLinus Torvalds } 6831da177e4SLinus Torvalds 684a762a980SDavid S. Miller /* Congestion window validation. (RFC2861) */ 685a762a980SDavid S. Miller 686a762a980SDavid S. Miller static inline void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp) 687a762a980SDavid S. Miller { 688a762a980SDavid S. Miller __u32 packets_out = tp->packets_out; 689a762a980SDavid S. Miller 690a762a980SDavid S. Miller if (packets_out >= tp->snd_cwnd) { 691a762a980SDavid S. Miller /* Network is feed fully. */ 692a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 693a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 694a762a980SDavid S. Miller } else { 695a762a980SDavid S. Miller /* Network starves. */ 696a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 697a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 698a762a980SDavid S. Miller 699a762a980SDavid S. Miller if ((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= tp->rto) 700a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 701a762a980SDavid S. Miller } 702a762a980SDavid S. Miller } 703a762a980SDavid S. Miller 704c1b4a7e6SDavid S. Miller static unsigned int tcp_window_allows(struct tcp_sock *tp, struct sk_buff *skb, unsigned int mss_now, unsigned int cwnd) 705c1b4a7e6SDavid S. Miller { 706c1b4a7e6SDavid S. Miller u32 window, cwnd_len; 707c1b4a7e6SDavid S. Miller 708c1b4a7e6SDavid S. Miller window = (tp->snd_una + tp->snd_wnd - TCP_SKB_CB(skb)->seq); 709c1b4a7e6SDavid S. Miller cwnd_len = mss_now * cwnd; 710c1b4a7e6SDavid S. Miller return min(window, cwnd_len); 711c1b4a7e6SDavid S. Miller } 712c1b4a7e6SDavid S. Miller 713c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 714c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 715c1b4a7e6SDavid S. Miller */ 716c1b4a7e6SDavid S. Miller static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *skb) 717c1b4a7e6SDavid S. Miller { 718c1b4a7e6SDavid S. Miller u32 in_flight, cwnd; 719c1b4a7e6SDavid S. Miller 720c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 721c1b4a7e6SDavid S. Miller if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) 722c1b4a7e6SDavid S. Miller return 1; 723c1b4a7e6SDavid S. Miller 724c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 725c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 726c1b4a7e6SDavid S. Miller if (in_flight < cwnd) 727c1b4a7e6SDavid S. Miller return (cwnd - in_flight); 728c1b4a7e6SDavid S. Miller 729c1b4a7e6SDavid S. Miller return 0; 730c1b4a7e6SDavid S. Miller } 731c1b4a7e6SDavid S. Miller 732c1b4a7e6SDavid S. Miller /* This must be invoked the first time we consider transmitting 733c1b4a7e6SDavid S. Miller * SKB onto the wire. 734c1b4a7e6SDavid S. Miller */ 735846998aeSDavid S. Miller static inline int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) 736c1b4a7e6SDavid S. Miller { 737c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 738c1b4a7e6SDavid S. Miller 739846998aeSDavid S. Miller if (!tso_segs || 740846998aeSDavid S. Miller (tso_segs > 1 && 741846998aeSDavid S. Miller skb_shinfo(skb)->tso_size != mss_now)) { 742846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 743c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 744c1b4a7e6SDavid S. Miller } 745c1b4a7e6SDavid S. Miller return tso_segs; 746c1b4a7e6SDavid S. Miller } 747c1b4a7e6SDavid S. Miller 748c1b4a7e6SDavid S. Miller static inline int tcp_minshall_check(const struct tcp_sock *tp) 749c1b4a7e6SDavid S. Miller { 750c1b4a7e6SDavid S. Miller return after(tp->snd_sml,tp->snd_una) && 751c1b4a7e6SDavid S. Miller !after(tp->snd_sml, tp->snd_nxt); 752c1b4a7e6SDavid S. Miller } 753c1b4a7e6SDavid S. Miller 754c1b4a7e6SDavid S. Miller /* Return 0, if packet can be sent now without violation Nagle's rules: 755c1b4a7e6SDavid S. Miller * 1. It is full sized. 756c1b4a7e6SDavid S. Miller * 2. Or it contains FIN. (already checked by caller) 757c1b4a7e6SDavid S. Miller * 3. Or TCP_NODELAY was set. 758c1b4a7e6SDavid S. Miller * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 759c1b4a7e6SDavid S. Miller * With Minshall's modification: all sent small packets are ACKed. 760c1b4a7e6SDavid S. Miller */ 761c1b4a7e6SDavid S. Miller 762c1b4a7e6SDavid S. Miller static inline int tcp_nagle_check(const struct tcp_sock *tp, 763c1b4a7e6SDavid S. Miller const struct sk_buff *skb, 764c1b4a7e6SDavid S. Miller unsigned mss_now, int nonagle) 765c1b4a7e6SDavid S. Miller { 766c1b4a7e6SDavid S. Miller return (skb->len < mss_now && 767c1b4a7e6SDavid S. Miller ((nonagle&TCP_NAGLE_CORK) || 768c1b4a7e6SDavid S. Miller (!nonagle && 769c1b4a7e6SDavid S. Miller tp->packets_out && 770c1b4a7e6SDavid S. Miller tcp_minshall_check(tp)))); 771c1b4a7e6SDavid S. Miller } 772c1b4a7e6SDavid S. Miller 773c1b4a7e6SDavid S. Miller /* Return non-zero if the Nagle test allows this packet to be 774c1b4a7e6SDavid S. Miller * sent now. 775c1b4a7e6SDavid S. Miller */ 776c1b4a7e6SDavid S. Miller static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, 777c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 778c1b4a7e6SDavid S. Miller { 779c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 780c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 781c1b4a7e6SDavid S. Miller * 782c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 783c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 784c1b4a7e6SDavid S. Miller */ 785c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 786c1b4a7e6SDavid S. Miller return 1; 787c1b4a7e6SDavid S. Miller 788c1b4a7e6SDavid S. Miller /* Don't use the nagle rule for urgent data (or for the final FIN). */ 789c1b4a7e6SDavid S. Miller if (tp->urg_mode || 790c1b4a7e6SDavid S. Miller (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) 791c1b4a7e6SDavid S. Miller return 1; 792c1b4a7e6SDavid S. Miller 793c1b4a7e6SDavid S. Miller if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) 794c1b4a7e6SDavid S. Miller return 1; 795c1b4a7e6SDavid S. Miller 796c1b4a7e6SDavid S. Miller return 0; 797c1b4a7e6SDavid S. Miller } 798c1b4a7e6SDavid S. Miller 799c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 800c1b4a7e6SDavid S. Miller static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, unsigned int cur_mss) 801c1b4a7e6SDavid S. Miller { 802c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 803c1b4a7e6SDavid S. Miller 804c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 805c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 806c1b4a7e6SDavid S. Miller 807c1b4a7e6SDavid S. Miller return !after(end_seq, tp->snd_una + tp->snd_wnd); 808c1b4a7e6SDavid S. Miller } 809c1b4a7e6SDavid S. Miller 810c1b4a7e6SDavid S. Miller /* This checks if the data bearing packet SKB (usually sk->sk_send_head) 811c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 812c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 813c1b4a7e6SDavid S. Miller */ 814c1b4a7e6SDavid S. Miller static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, 815c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 816c1b4a7e6SDavid S. Miller { 817c1b4a7e6SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 818c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 819c1b4a7e6SDavid S. Miller 820846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 821c1b4a7e6SDavid S. Miller 822c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 823c1b4a7e6SDavid S. Miller return 0; 824c1b4a7e6SDavid S. Miller 825c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 826c1b4a7e6SDavid S. Miller if (cwnd_quota && 827c1b4a7e6SDavid S. Miller !tcp_snd_wnd_test(tp, skb, cur_mss)) 828c1b4a7e6SDavid S. Miller cwnd_quota = 0; 829c1b4a7e6SDavid S. Miller 830c1b4a7e6SDavid S. Miller return cwnd_quota; 831c1b4a7e6SDavid S. Miller } 832c1b4a7e6SDavid S. Miller 833c1b4a7e6SDavid S. Miller static inline int tcp_skb_is_last(const struct sock *sk, 834c1b4a7e6SDavid S. Miller const struct sk_buff *skb) 835c1b4a7e6SDavid S. Miller { 836c1b4a7e6SDavid S. Miller return skb->next == (struct sk_buff *)&sk->sk_write_queue; 837c1b4a7e6SDavid S. Miller } 838c1b4a7e6SDavid S. Miller 839c1b4a7e6SDavid S. Miller int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp) 840c1b4a7e6SDavid S. Miller { 841c1b4a7e6SDavid S. Miller struct sk_buff *skb = sk->sk_send_head; 842c1b4a7e6SDavid S. Miller 843c1b4a7e6SDavid S. Miller return (skb && 844c1b4a7e6SDavid S. Miller tcp_snd_test(sk, skb, tcp_current_mss(sk, 1), 845c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 846c1b4a7e6SDavid S. Miller TCP_NAGLE_PUSH : 847c1b4a7e6SDavid S. Miller tp->nonagle))); 848c1b4a7e6SDavid S. Miller } 849c1b4a7e6SDavid S. Miller 850c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 851c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 852c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 853c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 854c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 855c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 856c1b4a7e6SDavid S. Miller */ 857846998aeSDavid S. Miller static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, unsigned int mss_now) 858c1b4a7e6SDavid S. Miller { 859c1b4a7e6SDavid S. Miller struct sk_buff *buff; 860c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 861c1b4a7e6SDavid S. Miller u16 flags; 862c1b4a7e6SDavid S. Miller 863c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 864*c8ac3774SHerbert Xu if (skb->len != skb->data_len) 865*c8ac3774SHerbert Xu return tcp_fragment(sk, skb, len, mss_now); 866c1b4a7e6SDavid S. Miller 867c1b4a7e6SDavid S. Miller buff = sk_stream_alloc_pskb(sk, 0, 0, GFP_ATOMIC); 868c1b4a7e6SDavid S. Miller if (unlikely(buff == NULL)) 869c1b4a7e6SDavid S. Miller return -ENOMEM; 870c1b4a7e6SDavid S. Miller 871c1b4a7e6SDavid S. Miller buff->truesize = nlen; 872c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 873c1b4a7e6SDavid S. Miller 874c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 875c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 876c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 877c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 878c1b4a7e6SDavid S. Miller 879c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 880c1b4a7e6SDavid S. Miller flags = TCP_SKB_CB(skb)->flags; 881c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); 882c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->flags = flags; 883c1b4a7e6SDavid S. Miller 884c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 885c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 886c1b4a7e6SDavid S. Miller 887c1b4a7e6SDavid S. Miller buff->ip_summed = skb->ip_summed = CHECKSUM_HW; 888c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 889c1b4a7e6SDavid S. Miller 890c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 891846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 892846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 893c1b4a7e6SDavid S. Miller 894c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 895c1b4a7e6SDavid S. Miller skb_header_release(buff); 896c1b4a7e6SDavid S. Miller __skb_append(skb, buff); 897c1b4a7e6SDavid S. Miller 898c1b4a7e6SDavid S. Miller return 0; 899c1b4a7e6SDavid S. Miller } 900c1b4a7e6SDavid S. Miller 901c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 902c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 903c1b4a7e6SDavid S. Miller * 904c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 905c1b4a7e6SDavid S. Miller */ 906c1b4a7e6SDavid S. Miller static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) 907c1b4a7e6SDavid S. Miller { 908c1b4a7e6SDavid S. Miller u32 send_win, cong_win, limit, in_flight; 909c1b4a7e6SDavid S. Miller 910c1b4a7e6SDavid S. Miller if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) 911c1b4a7e6SDavid S. Miller return 0; 912c1b4a7e6SDavid S. Miller 913908a75c1SDavid S. Miller if (tp->ca_state != TCP_CA_Open) 914908a75c1SDavid S. Miller return 0; 915908a75c1SDavid S. Miller 916c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 917c1b4a7e6SDavid S. Miller 918c1b4a7e6SDavid S. Miller BUG_ON(tcp_skb_pcount(skb) <= 1 || 919c1b4a7e6SDavid S. Miller (tp->snd_cwnd <= in_flight)); 920c1b4a7e6SDavid S. Miller 921c1b4a7e6SDavid S. Miller send_win = (tp->snd_una + tp->snd_wnd) - TCP_SKB_CB(skb)->seq; 922c1b4a7e6SDavid S. Miller 923c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 924c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 925c1b4a7e6SDavid S. Miller 926c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 927c1b4a7e6SDavid S. Miller 928c1b4a7e6SDavid S. Miller /* If sk_send_head can be sent fully now, just do it. */ 929c1b4a7e6SDavid S. Miller if (skb->len <= limit) 930c1b4a7e6SDavid S. Miller return 0; 931c1b4a7e6SDavid S. Miller 932c1b4a7e6SDavid S. Miller if (sysctl_tcp_tso_win_divisor) { 933c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 934c1b4a7e6SDavid S. Miller 935c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 936c1b4a7e6SDavid S. Miller * just use it. 937c1b4a7e6SDavid S. Miller */ 938c1b4a7e6SDavid S. Miller chunk /= sysctl_tcp_tso_win_divisor; 939c1b4a7e6SDavid S. Miller if (limit >= chunk) 940c1b4a7e6SDavid S. Miller return 0; 941c1b4a7e6SDavid S. Miller } else { 942c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 943c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 944c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 945c1b4a7e6SDavid S. Miller * then send now. 946c1b4a7e6SDavid S. Miller */ 947c1b4a7e6SDavid S. Miller if (limit > tcp_max_burst(tp) * tp->mss_cache) 948c1b4a7e6SDavid S. Miller return 0; 949c1b4a7e6SDavid S. Miller } 950c1b4a7e6SDavid S. Miller 951c1b4a7e6SDavid S. Miller /* Ok, it looks like it is advisable to defer. */ 952c1b4a7e6SDavid S. Miller return 1; 953c1b4a7e6SDavid S. Miller } 954c1b4a7e6SDavid S. Miller 9551da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 9561da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 9571da177e4SLinus Torvalds * window for us. 9581da177e4SLinus Torvalds * 9591da177e4SLinus Torvalds * Returns 1, if no segments are in flight and we have queued segments, but 9601da177e4SLinus Torvalds * cannot send anything now because of SWS or another problem. 9611da177e4SLinus Torvalds */ 962a2e2a59cSDavid S. Miller static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) 9631da177e4SLinus Torvalds { 9641da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 96592df7b51SDavid S. Miller struct sk_buff *skb; 966c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 967c1b4a7e6SDavid S. Miller int cwnd_quota; 9681da177e4SLinus Torvalds 9691da177e4SLinus Torvalds /* If we are closed, the bytes will have to remain here. 9701da177e4SLinus Torvalds * In time closedown will finish, we empty the write queue and all 9711da177e4SLinus Torvalds * will be happy. 9721da177e4SLinus Torvalds */ 97392df7b51SDavid S. Miller if (unlikely(sk->sk_state == TCP_CLOSE)) 97492df7b51SDavid S. Miller return 0; 97592df7b51SDavid S. Miller 976c1b4a7e6SDavid S. Miller sent_pkts = 0; 977b68e9f85SHerbert Xu while ((skb = sk->sk_send_head)) { 978*c8ac3774SHerbert Xu unsigned int limit; 979*c8ac3774SHerbert Xu 980b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 981c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 982c1b4a7e6SDavid S. Miller 983b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 984b68e9f85SHerbert Xu if (!cwnd_quota) 985b68e9f85SHerbert Xu break; 986b68e9f85SHerbert Xu 987b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 988b68e9f85SHerbert Xu break; 989b68e9f85SHerbert Xu 990c1b4a7e6SDavid S. Miller if (tso_segs == 1) { 991aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 992aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 993aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 994aa93466bSDavid S. Miller break; 995c1b4a7e6SDavid S. Miller } else { 996c1b4a7e6SDavid S. Miller if (tcp_tso_should_defer(sk, tp, skb)) 997aa93466bSDavid S. Miller break; 998c1b4a7e6SDavid S. Miller } 999aa93466bSDavid S. Miller 1000*c8ac3774SHerbert Xu limit = mss_now; 1001c1b4a7e6SDavid S. Miller if (tso_segs > 1) { 1002*c8ac3774SHerbert Xu limit = tcp_window_allows(tp, skb, 1003c1b4a7e6SDavid S. Miller mss_now, cwnd_quota); 1004c1b4a7e6SDavid S. Miller 1005c1b4a7e6SDavid S. Miller if (skb->len < limit) { 1006c1b4a7e6SDavid S. Miller unsigned int trim = skb->len % mss_now; 1007c1b4a7e6SDavid S. Miller 1008c1b4a7e6SDavid S. Miller if (trim) 1009c1b4a7e6SDavid S. Miller limit = skb->len - trim; 1010c1b4a7e6SDavid S. Miller } 1011c1b4a7e6SDavid S. Miller } 1012*c8ac3774SHerbert Xu 1013*c8ac3774SHerbert Xu if (skb->len > limit && 1014*c8ac3774SHerbert Xu unlikely(tso_fragment(sk, skb, limit, mss_now))) 10151da177e4SLinus Torvalds break; 10161da177e4SLinus Torvalds 10171da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 1018c1b4a7e6SDavid S. Miller 1019aa93466bSDavid S. Miller if (unlikely(tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)))) 10201da177e4SLinus Torvalds break; 10211da177e4SLinus Torvalds 10221da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 10231da177e4SLinus Torvalds * This call will increment packets_out. 10241da177e4SLinus Torvalds */ 10251da177e4SLinus Torvalds update_send_head(sk, tp, skb); 10261da177e4SLinus Torvalds 10271da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 1028aa93466bSDavid S. Miller sent_pkts++; 10291da177e4SLinus Torvalds } 10301da177e4SLinus Torvalds 1031aa93466bSDavid S. Miller if (likely(sent_pkts)) { 10321da177e4SLinus Torvalds tcp_cwnd_validate(sk, tp); 10331da177e4SLinus Torvalds return 0; 10341da177e4SLinus Torvalds } 10351da177e4SLinus Torvalds return !tp->packets_out && sk->sk_send_head; 10361da177e4SLinus Torvalds } 10371da177e4SLinus Torvalds 1038a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 1039a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 1040a762a980SDavid S. Miller * The socket must be locked by the caller. 1041a762a980SDavid S. Miller */ 1042a762a980SDavid S. Miller void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp, 1043a2e2a59cSDavid S. Miller unsigned int cur_mss, int nonagle) 1044a762a980SDavid S. Miller { 1045a762a980SDavid S. Miller struct sk_buff *skb = sk->sk_send_head; 1046a762a980SDavid S. Miller 1047a762a980SDavid S. Miller if (skb) { 104855c97f3eSDavid S. Miller if (tcp_write_xmit(sk, cur_mss, nonagle)) 1049a762a980SDavid S. Miller tcp_check_probe_timer(sk, tp); 1050a762a980SDavid S. Miller } 1051a762a980SDavid S. Miller } 1052a762a980SDavid S. Miller 1053c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 1054c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 1055c1b4a7e6SDavid S. Miller */ 1056c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 1057c1b4a7e6SDavid S. Miller { 1058c1b4a7e6SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1059c1b4a7e6SDavid S. Miller struct sk_buff *skb = sk->sk_send_head; 1060c1b4a7e6SDavid S. Miller unsigned int tso_segs, cwnd_quota; 1061c1b4a7e6SDavid S. Miller 1062c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 1063c1b4a7e6SDavid S. Miller 1064846998aeSDavid S. Miller tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 1065c1b4a7e6SDavid S. Miller cwnd_quota = tcp_snd_test(sk, skb, mss_now, TCP_NAGLE_PUSH); 1066c1b4a7e6SDavid S. Miller 1067c1b4a7e6SDavid S. Miller if (likely(cwnd_quota)) { 1068*c8ac3774SHerbert Xu unsigned int limit; 1069*c8ac3774SHerbert Xu 1070c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 1071c1b4a7e6SDavid S. Miller 1072*c8ac3774SHerbert Xu limit = mss_now; 1073c1b4a7e6SDavid S. Miller if (tso_segs > 1) { 1074*c8ac3774SHerbert Xu limit = tcp_window_allows(tp, skb, 1075c1b4a7e6SDavid S. Miller mss_now, cwnd_quota); 1076c1b4a7e6SDavid S. Miller 1077c1b4a7e6SDavid S. Miller if (skb->len < limit) { 1078c1b4a7e6SDavid S. Miller unsigned int trim = skb->len % mss_now; 1079c1b4a7e6SDavid S. Miller 1080c1b4a7e6SDavid S. Miller if (trim) 1081c1b4a7e6SDavid S. Miller limit = skb->len - trim; 1082c1b4a7e6SDavid S. Miller } 1083c1b4a7e6SDavid S. Miller } 1084*c8ac3774SHerbert Xu 1085*c8ac3774SHerbert Xu if (skb->len > limit && 1086*c8ac3774SHerbert Xu unlikely(tso_fragment(sk, skb, limit, mss_now))) 1087c1b4a7e6SDavid S. Miller return; 1088c1b4a7e6SDavid S. Miller 1089c1b4a7e6SDavid S. Miller /* Send it out now. */ 1090c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->when = tcp_time_stamp; 1091c1b4a7e6SDavid S. Miller 1092c1b4a7e6SDavid S. Miller if (likely(!tcp_transmit_skb(sk, skb_clone(skb, sk->sk_allocation)))) { 1093c1b4a7e6SDavid S. Miller update_send_head(sk, tp, skb); 1094c1b4a7e6SDavid S. Miller tcp_cwnd_validate(sk, tp); 1095c1b4a7e6SDavid S. Miller return; 1096c1b4a7e6SDavid S. Miller } 1097c1b4a7e6SDavid S. Miller } 1098c1b4a7e6SDavid S. Miller } 1099c1b4a7e6SDavid S. Miller 11001da177e4SLinus Torvalds /* This function returns the amount that we can raise the 11011da177e4SLinus Torvalds * usable window based on the following constraints 11021da177e4SLinus Torvalds * 11031da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 11041da177e4SLinus Torvalds * 2. We limit memory per socket 11051da177e4SLinus Torvalds * 11061da177e4SLinus Torvalds * RFC 1122: 11071da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 11081da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 11091da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 11101da177e4SLinus Torvalds * 11111da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 11121da177e4SLinus Torvalds * it at least MSS bytes. 11131da177e4SLinus Torvalds * 11141da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 11151da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 11161da177e4SLinus Torvalds * 11171da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 11181da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 11191da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 11201da177e4SLinus Torvalds * window to always advance by a single byte. 11211da177e4SLinus Torvalds * 11221da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 11231da177e4SLinus Torvalds * then this will not be a problem. 11241da177e4SLinus Torvalds * 11251da177e4SLinus Torvalds * BSD seems to make the following compromise: 11261da177e4SLinus Torvalds * 11271da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 11281da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 11291da177e4SLinus Torvalds * then set the window to 0. 11301da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 11311da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 11321da177e4SLinus Torvalds * and from being larger than the largest representable value. 11331da177e4SLinus Torvalds * 11341da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 11351da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 11361da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 11371da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 11381da177e4SLinus Torvalds * because the pipeline is full. 11391da177e4SLinus Torvalds * 11401da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 11411da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 11421da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 11431da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 11441da177e4SLinus Torvalds * of having a fixed window size at almost all times. 11451da177e4SLinus Torvalds * 11461da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 11471da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 11481da177e4SLinus Torvalds * 11491da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 11501da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 11511da177e4SLinus Torvalds */ 11521da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 11531da177e4SLinus Torvalds { 11541da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11551da177e4SLinus Torvalds /* MSS for the peer's data. Previous verions used mss_clamp 11561da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 11571da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 11581da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 11591da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 11601da177e4SLinus Torvalds */ 11611da177e4SLinus Torvalds int mss = tp->ack.rcv_mss; 11621da177e4SLinus Torvalds int free_space = tcp_space(sk); 11631da177e4SLinus Torvalds int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); 11641da177e4SLinus Torvalds int window; 11651da177e4SLinus Torvalds 11661da177e4SLinus Torvalds if (mss > full_space) 11671da177e4SLinus Torvalds mss = full_space; 11681da177e4SLinus Torvalds 11691da177e4SLinus Torvalds if (free_space < full_space/2) { 11701da177e4SLinus Torvalds tp->ack.quick = 0; 11711da177e4SLinus Torvalds 11721da177e4SLinus Torvalds if (tcp_memory_pressure) 11731da177e4SLinus Torvalds tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U*tp->advmss); 11741da177e4SLinus Torvalds 11751da177e4SLinus Torvalds if (free_space < mss) 11761da177e4SLinus Torvalds return 0; 11771da177e4SLinus Torvalds } 11781da177e4SLinus Torvalds 11791da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 11801da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 11811da177e4SLinus Torvalds 11821da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 11831da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 11841da177e4SLinus Torvalds */ 11851da177e4SLinus Torvalds window = tp->rcv_wnd; 11861da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 11871da177e4SLinus Torvalds window = free_space; 11881da177e4SLinus Torvalds 11891da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 11901da177e4SLinus Torvalds * Import case: prevent zero window announcement if 11911da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 11921da177e4SLinus Torvalds */ 11931da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 11941da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 11951da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 11961da177e4SLinus Torvalds } else { 11971da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 11981da177e4SLinus Torvalds * Window clamp already applied above. 11991da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 12001da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 12011da177e4SLinus Torvalds * and multiply from happening most of the time. 12021da177e4SLinus Torvalds * We also don't do any window rounding when the free space 12031da177e4SLinus Torvalds * is too small. 12041da177e4SLinus Torvalds */ 12051da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 12061da177e4SLinus Torvalds window = (free_space/mss)*mss; 12071da177e4SLinus Torvalds } 12081da177e4SLinus Torvalds 12091da177e4SLinus Torvalds return window; 12101da177e4SLinus Torvalds } 12111da177e4SLinus Torvalds 12121da177e4SLinus Torvalds /* Attempt to collapse two adjacent SKB's during retransmission. */ 12131da177e4SLinus Torvalds static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int mss_now) 12141da177e4SLinus Torvalds { 12151da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12161da177e4SLinus Torvalds struct sk_buff *next_skb = skb->next; 12171da177e4SLinus Torvalds 12181da177e4SLinus Torvalds /* The first test we must make is that neither of these two 12191da177e4SLinus Torvalds * SKB's are still referenced by someone else. 12201da177e4SLinus Torvalds */ 12211da177e4SLinus Torvalds if (!skb_cloned(skb) && !skb_cloned(next_skb)) { 12221da177e4SLinus Torvalds int skb_size = skb->len, next_skb_size = next_skb->len; 12231da177e4SLinus Torvalds u16 flags = TCP_SKB_CB(skb)->flags; 12241da177e4SLinus Torvalds 12251da177e4SLinus Torvalds /* Also punt if next skb has been SACK'd. */ 12261da177e4SLinus Torvalds if(TCP_SKB_CB(next_skb)->sacked & TCPCB_SACKED_ACKED) 12271da177e4SLinus Torvalds return; 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds /* Next skb is out of window. */ 12301da177e4SLinus Torvalds if (after(TCP_SKB_CB(next_skb)->end_seq, tp->snd_una+tp->snd_wnd)) 12311da177e4SLinus Torvalds return; 12321da177e4SLinus Torvalds 12331da177e4SLinus Torvalds /* Punt if not enough space exists in the first SKB for 12341da177e4SLinus Torvalds * the data in the second, or the total combined payload 12351da177e4SLinus Torvalds * would exceed the MSS. 12361da177e4SLinus Torvalds */ 12371da177e4SLinus Torvalds if ((next_skb_size > skb_tailroom(skb)) || 12381da177e4SLinus Torvalds ((skb_size + next_skb_size) > mss_now)) 12391da177e4SLinus Torvalds return; 12401da177e4SLinus Torvalds 12411da177e4SLinus Torvalds BUG_ON(tcp_skb_pcount(skb) != 1 || 12421da177e4SLinus Torvalds tcp_skb_pcount(next_skb) != 1); 12431da177e4SLinus Torvalds 12441da177e4SLinus Torvalds /* Ok. We will be able to collapse the packet. */ 12451da177e4SLinus Torvalds __skb_unlink(next_skb, next_skb->list); 12461da177e4SLinus Torvalds 12471da177e4SLinus Torvalds memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size); 12481da177e4SLinus Torvalds 12491da177e4SLinus Torvalds if (next_skb->ip_summed == CHECKSUM_HW) 12501da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_HW; 12511da177e4SLinus Torvalds 12521da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_HW) 12531da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 12541da177e4SLinus Torvalds 12551da177e4SLinus Torvalds /* Update sequence range on original skb. */ 12561da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 12571da177e4SLinus Torvalds 12581da177e4SLinus Torvalds /* Merge over control information. */ 12591da177e4SLinus Torvalds flags |= TCP_SKB_CB(next_skb)->flags; /* This moves PSH/FIN etc. over */ 12601da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = flags; 12611da177e4SLinus Torvalds 12621da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 12631da177e4SLinus Torvalds * packet counting does not break. 12641da177e4SLinus Torvalds */ 12651da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked&(TCPCB_EVER_RETRANS|TCPCB_AT_TAIL); 12661da177e4SLinus Torvalds if (TCP_SKB_CB(next_skb)->sacked&TCPCB_SACKED_RETRANS) 12671da177e4SLinus Torvalds tp->retrans_out -= tcp_skb_pcount(next_skb); 12681da177e4SLinus Torvalds if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST) { 12691da177e4SLinus Torvalds tp->lost_out -= tcp_skb_pcount(next_skb); 12701da177e4SLinus Torvalds tp->left_out -= tcp_skb_pcount(next_skb); 12711da177e4SLinus Torvalds } 12721da177e4SLinus Torvalds /* Reno case is special. Sigh... */ 12731da177e4SLinus Torvalds if (!tp->rx_opt.sack_ok && tp->sacked_out) { 12741da177e4SLinus Torvalds tcp_dec_pcount_approx(&tp->sacked_out, next_skb); 12751da177e4SLinus Torvalds tp->left_out -= tcp_skb_pcount(next_skb); 12761da177e4SLinus Torvalds } 12771da177e4SLinus Torvalds 12781da177e4SLinus Torvalds /* Not quite right: it can be > snd.fack, but 12791da177e4SLinus Torvalds * it is better to underestimate fackets. 12801da177e4SLinus Torvalds */ 12811da177e4SLinus Torvalds tcp_dec_pcount_approx(&tp->fackets_out, next_skb); 12821da177e4SLinus Torvalds tcp_packets_out_dec(tp, next_skb); 12831da177e4SLinus Torvalds sk_stream_free_skb(sk, next_skb); 12841da177e4SLinus Torvalds } 12851da177e4SLinus Torvalds } 12861da177e4SLinus Torvalds 12871da177e4SLinus Torvalds /* Do a simple retransmit without using the backoff mechanisms in 12881da177e4SLinus Torvalds * tcp_timer. This is used for path mtu discovery. 12891da177e4SLinus Torvalds * The socket is already locked here. 12901da177e4SLinus Torvalds */ 12911da177e4SLinus Torvalds void tcp_simple_retransmit(struct sock *sk) 12921da177e4SLinus Torvalds { 12931da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12941da177e4SLinus Torvalds struct sk_buff *skb; 12951da177e4SLinus Torvalds unsigned int mss = tcp_current_mss(sk, 0); 12961da177e4SLinus Torvalds int lost = 0; 12971da177e4SLinus Torvalds 12981da177e4SLinus Torvalds sk_stream_for_retrans_queue(skb, sk) { 12991da177e4SLinus Torvalds if (skb->len > mss && 13001da177e4SLinus Torvalds !(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) { 13011da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { 13021da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; 13031da177e4SLinus Torvalds tp->retrans_out -= tcp_skb_pcount(skb); 13041da177e4SLinus Torvalds } 13051da177e4SLinus Torvalds if (!(TCP_SKB_CB(skb)->sacked&TCPCB_LOST)) { 13061da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; 13071da177e4SLinus Torvalds tp->lost_out += tcp_skb_pcount(skb); 13081da177e4SLinus Torvalds lost = 1; 13091da177e4SLinus Torvalds } 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds } 13121da177e4SLinus Torvalds 13131da177e4SLinus Torvalds if (!lost) 13141da177e4SLinus Torvalds return; 13151da177e4SLinus Torvalds 13161da177e4SLinus Torvalds tcp_sync_left_out(tp); 13171da177e4SLinus Torvalds 13181da177e4SLinus Torvalds /* Don't muck with the congestion window here. 13191da177e4SLinus Torvalds * Reason is that we do not increase amount of _data_ 13201da177e4SLinus Torvalds * in network, but units changed and effective 13211da177e4SLinus Torvalds * cwnd/ssthresh really reduced now. 13221da177e4SLinus Torvalds */ 13231da177e4SLinus Torvalds if (tp->ca_state != TCP_CA_Loss) { 13241da177e4SLinus Torvalds tp->high_seq = tp->snd_nxt; 13251da177e4SLinus Torvalds tp->snd_ssthresh = tcp_current_ssthresh(tp); 13261da177e4SLinus Torvalds tp->prior_ssthresh = 0; 13271da177e4SLinus Torvalds tp->undo_marker = 0; 13281da177e4SLinus Torvalds tcp_set_ca_state(tp, TCP_CA_Loss); 13291da177e4SLinus Torvalds } 13301da177e4SLinus Torvalds tcp_xmit_retransmit_queue(sk); 13311da177e4SLinus Torvalds } 13321da177e4SLinus Torvalds 13331da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 13341da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 13351da177e4SLinus Torvalds * error occurred which prevented the send. 13361da177e4SLinus Torvalds */ 13371da177e4SLinus Torvalds int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 13381da177e4SLinus Torvalds { 13391da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 13401da177e4SLinus Torvalds unsigned int cur_mss = tcp_current_mss(sk, 0); 13411da177e4SLinus Torvalds int err; 13421da177e4SLinus Torvalds 13431da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 13441da177e4SLinus Torvalds * copying overhead: frgagmentation, tunneling, mangling etc. 13451da177e4SLinus Torvalds */ 13461da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 13471da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 13481da177e4SLinus Torvalds return -EAGAIN; 13491da177e4SLinus Torvalds 13501da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 13511da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 13521da177e4SLinus Torvalds BUG(); 13531da177e4SLinus Torvalds 13541da177e4SLinus Torvalds if (sk->sk_route_caps & NETIF_F_TSO) { 13551da177e4SLinus Torvalds sk->sk_route_caps &= ~NETIF_F_TSO; 13561da177e4SLinus Torvalds sock_set_flag(sk, SOCK_NO_LARGESEND); 13571da177e4SLinus Torvalds } 13581da177e4SLinus Torvalds 13591da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 13601da177e4SLinus Torvalds return -ENOMEM; 13611da177e4SLinus Torvalds } 13621da177e4SLinus Torvalds 13631da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 13641da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 13651da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 13661da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 13671da177e4SLinus Torvalds */ 13681da177e4SLinus Torvalds if (!before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd) 13691da177e4SLinus Torvalds && TCP_SKB_CB(skb)->seq != tp->snd_una) 13701da177e4SLinus Torvalds return -EAGAIN; 13711da177e4SLinus Torvalds 13721da177e4SLinus Torvalds if (skb->len > cur_mss) { 13731da177e4SLinus Torvalds int old_factor = tcp_skb_pcount(skb); 1374b5da623aSHerbert Xu int diff; 13751da177e4SLinus Torvalds 1376846998aeSDavid S. Miller if (tcp_fragment(sk, skb, cur_mss, cur_mss)) 13771da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 13781da177e4SLinus Torvalds 13791da177e4SLinus Torvalds /* New SKB created, account for it. */ 1380b5da623aSHerbert Xu diff = old_factor - tcp_skb_pcount(skb) - 1381b5da623aSHerbert Xu tcp_skb_pcount(skb->next); 1382b5da623aSHerbert Xu tp->packets_out -= diff; 1383b5da623aSHerbert Xu 1384b5da623aSHerbert Xu if (diff > 0) { 1385b5da623aSHerbert Xu tp->fackets_out -= diff; 1386b5da623aSHerbert Xu if ((int)tp->fackets_out < 0) 1387b5da623aSHerbert Xu tp->fackets_out = 0; 1388b5da623aSHerbert Xu } 13891da177e4SLinus Torvalds } 13901da177e4SLinus Torvalds 13911da177e4SLinus Torvalds /* Collapse two adjacent packets if worthwhile and we can. */ 13921da177e4SLinus Torvalds if(!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN) && 13931da177e4SLinus Torvalds (skb->len < (cur_mss >> 1)) && 13941da177e4SLinus Torvalds (skb->next != sk->sk_send_head) && 13951da177e4SLinus Torvalds (skb->next != (struct sk_buff *)&sk->sk_write_queue) && 13961da177e4SLinus Torvalds (skb_shinfo(skb)->nr_frags == 0 && skb_shinfo(skb->next)->nr_frags == 0) && 13971da177e4SLinus Torvalds (tcp_skb_pcount(skb) == 1 && tcp_skb_pcount(skb->next) == 1) && 13981da177e4SLinus Torvalds (sysctl_tcp_retrans_collapse != 0)) 13991da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds if(tp->af_specific->rebuild_header(sk)) 14021da177e4SLinus Torvalds return -EHOSTUNREACH; /* Routing failure or similar. */ 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds /* Some Solaris stacks overoptimize and ignore the FIN on a 14051da177e4SLinus Torvalds * retransmit when old data is attached. So strip it off 14061da177e4SLinus Torvalds * since it is cheap to do so and saves bytes on the network. 14071da177e4SLinus Torvalds */ 14081da177e4SLinus Torvalds if(skb->len > 0 && 14091da177e4SLinus Torvalds (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && 14101da177e4SLinus Torvalds tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { 14111da177e4SLinus Torvalds if (!pskb_trim(skb, 0)) { 14121da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1; 14131da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 14141da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 14151da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 14161da177e4SLinus Torvalds skb->csum = 0; 14171da177e4SLinus Torvalds } 14181da177e4SLinus Torvalds } 14191da177e4SLinus Torvalds 14201da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 14211da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 14221da177e4SLinus Torvalds */ 14231da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds err = tcp_transmit_skb(sk, (skb_cloned(skb) ? 14261da177e4SLinus Torvalds pskb_copy(skb, GFP_ATOMIC): 14271da177e4SLinus Torvalds skb_clone(skb, GFP_ATOMIC))); 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds if (err == 0) { 14301da177e4SLinus Torvalds /* Update global TCP statistics. */ 14311da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_RETRANSSEGS); 14321da177e4SLinus Torvalds 14331da177e4SLinus Torvalds tp->total_retrans++; 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 14361da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { 14371da177e4SLinus Torvalds if (net_ratelimit()) 14381da177e4SLinus Torvalds printk(KERN_DEBUG "retrans_out leaked.\n"); 14391da177e4SLinus Torvalds } 14401da177e4SLinus Torvalds #endif 14411da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 14421da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 14451da177e4SLinus Torvalds if (!tp->retrans_stamp) 14461da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(skb)->when; 14471da177e4SLinus Torvalds 14481da177e4SLinus Torvalds tp->undo_retrans++; 14491da177e4SLinus Torvalds 14501da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 14511da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 14521da177e4SLinus Torvalds */ 14531da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 14541da177e4SLinus Torvalds } 14551da177e4SLinus Torvalds return err; 14561da177e4SLinus Torvalds } 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 14591da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 14601da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 14611da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 14621da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 14631da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 14641da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 14651da177e4SLinus Torvalds */ 14661da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 14671da177e4SLinus Torvalds { 14681da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 14691da177e4SLinus Torvalds struct sk_buff *skb; 14701da177e4SLinus Torvalds int packet_cnt = tp->lost_out; 14711da177e4SLinus Torvalds 14721da177e4SLinus Torvalds /* First pass: retransmit lost packets. */ 14731da177e4SLinus Torvalds if (packet_cnt) { 14741da177e4SLinus Torvalds sk_stream_for_retrans_queue(skb, sk) { 14751da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 14761da177e4SLinus Torvalds 14771da177e4SLinus Torvalds /* Assume this retransmit will generate 14781da177e4SLinus Torvalds * only one packet for congestion window 14791da177e4SLinus Torvalds * calculation purposes. This works because 14801da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 14811da177e4SLinus Torvalds * packet to be MSS sized and all the 14821da177e4SLinus Torvalds * packet counting works out. 14831da177e4SLinus Torvalds */ 14841da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 14851da177e4SLinus Torvalds return; 14861da177e4SLinus Torvalds 14871da177e4SLinus Torvalds if (sacked&TCPCB_LOST) { 14881da177e4SLinus Torvalds if (!(sacked&(TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) { 14891da177e4SLinus Torvalds if (tcp_retransmit_skb(sk, skb)) 14901da177e4SLinus Torvalds return; 14911da177e4SLinus Torvalds if (tp->ca_state != TCP_CA_Loss) 14921da177e4SLinus Torvalds NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS); 14931da177e4SLinus Torvalds else 14941da177e4SLinus Torvalds NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS); 14951da177e4SLinus Torvalds 14961da177e4SLinus Torvalds if (skb == 14971da177e4SLinus Torvalds skb_peek(&sk->sk_write_queue)) 14981da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); 14991da177e4SLinus Torvalds } 15001da177e4SLinus Torvalds 15011da177e4SLinus Torvalds packet_cnt -= tcp_skb_pcount(skb); 15021da177e4SLinus Torvalds if (packet_cnt <= 0) 15031da177e4SLinus Torvalds break; 15041da177e4SLinus Torvalds } 15051da177e4SLinus Torvalds } 15061da177e4SLinus Torvalds } 15071da177e4SLinus Torvalds 15081da177e4SLinus Torvalds /* OK, demanded retransmission is finished. */ 15091da177e4SLinus Torvalds 15101da177e4SLinus Torvalds /* Forward retransmissions are possible only during Recovery. */ 15111da177e4SLinus Torvalds if (tp->ca_state != TCP_CA_Recovery) 15121da177e4SLinus Torvalds return; 15131da177e4SLinus Torvalds 15141da177e4SLinus Torvalds /* No forward retransmissions in Reno are possible. */ 15151da177e4SLinus Torvalds if (!tp->rx_opt.sack_ok) 15161da177e4SLinus Torvalds return; 15171da177e4SLinus Torvalds 15181da177e4SLinus Torvalds /* Yeah, we have to make difficult choice between forward transmission 15191da177e4SLinus Torvalds * and retransmission... Both ways have their merits... 15201da177e4SLinus Torvalds * 15211da177e4SLinus Torvalds * For now we do not retransmit anything, while we have some new 15221da177e4SLinus Torvalds * segments to send. 15231da177e4SLinus Torvalds */ 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds if (tcp_may_send_now(sk, tp)) 15261da177e4SLinus Torvalds return; 15271da177e4SLinus Torvalds 15281da177e4SLinus Torvalds packet_cnt = 0; 15291da177e4SLinus Torvalds 15301da177e4SLinus Torvalds sk_stream_for_retrans_queue(skb, sk) { 15311da177e4SLinus Torvalds /* Similar to the retransmit loop above we 15321da177e4SLinus Torvalds * can pretend that the retransmitted SKB 15331da177e4SLinus Torvalds * we send out here will be composed of one 15341da177e4SLinus Torvalds * real MSS sized packet because tcp_retransmit_skb() 15351da177e4SLinus Torvalds * will fragment it if necessary. 15361da177e4SLinus Torvalds */ 15371da177e4SLinus Torvalds if (++packet_cnt > tp->fackets_out) 15381da177e4SLinus Torvalds break; 15391da177e4SLinus Torvalds 15401da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 15411da177e4SLinus Torvalds break; 15421da177e4SLinus Torvalds 15431da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) 15441da177e4SLinus Torvalds continue; 15451da177e4SLinus Torvalds 15461da177e4SLinus Torvalds /* Ok, retransmit it. */ 15471da177e4SLinus Torvalds if (tcp_retransmit_skb(sk, skb)) 15481da177e4SLinus Torvalds break; 15491da177e4SLinus Torvalds 15501da177e4SLinus Torvalds if (skb == skb_peek(&sk->sk_write_queue)) 15511da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); 15521da177e4SLinus Torvalds 15531da177e4SLinus Torvalds NET_INC_STATS_BH(LINUX_MIB_TCPFORWARDRETRANS); 15541da177e4SLinus Torvalds } 15551da177e4SLinus Torvalds } 15561da177e4SLinus Torvalds 15571da177e4SLinus Torvalds 15581da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 15591da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 15601da177e4SLinus Torvalds */ 15611da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 15621da177e4SLinus Torvalds { 15631da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 15641da177e4SLinus Torvalds struct sk_buff *skb = skb_peek_tail(&sk->sk_write_queue); 15651da177e4SLinus Torvalds int mss_now; 15661da177e4SLinus Torvalds 15671da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 15681da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 15691da177e4SLinus Torvalds * and IP options. 15701da177e4SLinus Torvalds */ 15711da177e4SLinus Torvalds mss_now = tcp_current_mss(sk, 1); 15721da177e4SLinus Torvalds 15731da177e4SLinus Torvalds if (sk->sk_send_head != NULL) { 15741da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; 15751da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 15761da177e4SLinus Torvalds tp->write_seq++; 15771da177e4SLinus Torvalds } else { 15781da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 15791da177e4SLinus Torvalds for (;;) { 15801da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_KERNEL); 15811da177e4SLinus Torvalds if (skb) 15821da177e4SLinus Torvalds break; 15831da177e4SLinus Torvalds yield(); 15841da177e4SLinus Torvalds } 15851da177e4SLinus Torvalds 15861da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 15871da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 15881da177e4SLinus Torvalds skb->csum = 0; 15891da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); 15901da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = 0; 15911da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 15921da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 15931da177e4SLinus Torvalds 15941da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 15951da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = tp->write_seq; 15961da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; 15971da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 15981da177e4SLinus Torvalds } 15991da177e4SLinus Torvalds __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_OFF); 16001da177e4SLinus Torvalds } 16011da177e4SLinus Torvalds 16021da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 16031da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 16041da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 16051da177e4SLinus Torvalds * by draft-ietf-tcpimpl-prob-03.txt section 3.10. -DaveM 16061da177e4SLinus Torvalds */ 160786a76cafSVictor Fusco void tcp_send_active_reset(struct sock *sk, unsigned int __nocast priority) 16081da177e4SLinus Torvalds { 16091da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 16101da177e4SLinus Torvalds struct sk_buff *skb; 16111da177e4SLinus Torvalds 16121da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 16131da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 16141da177e4SLinus Torvalds if (!skb) { 16151da177e4SLinus Torvalds NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); 16161da177e4SLinus Torvalds return; 16171da177e4SLinus Torvalds } 16181da177e4SLinus Torvalds 16191da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 16201da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 16211da177e4SLinus Torvalds skb->csum = 0; 16221da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST); 16231da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = 0; 16241da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 16251da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 16261da177e4SLinus Torvalds 16271da177e4SLinus Torvalds /* Send it off. */ 16281da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk, tp); 16291da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; 16301da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 16311da177e4SLinus Torvalds if (tcp_transmit_skb(sk, skb)) 16321da177e4SLinus Torvalds NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); 16331da177e4SLinus Torvalds } 16341da177e4SLinus Torvalds 16351da177e4SLinus Torvalds /* WARNING: This routine must only be called when we have already sent 16361da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 16371da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 16381da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 16391da177e4SLinus Torvalds */ 16401da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 16411da177e4SLinus Torvalds { 16421da177e4SLinus Torvalds struct sk_buff* skb; 16431da177e4SLinus Torvalds 16441da177e4SLinus Torvalds skb = skb_peek(&sk->sk_write_queue); 16451da177e4SLinus Torvalds if (skb == NULL || !(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_SYN)) { 16461da177e4SLinus Torvalds printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); 16471da177e4SLinus Torvalds return -EFAULT; 16481da177e4SLinus Torvalds } 16491da177e4SLinus Torvalds if (!(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_ACK)) { 16501da177e4SLinus Torvalds if (skb_cloned(skb)) { 16511da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 16521da177e4SLinus Torvalds if (nskb == NULL) 16531da177e4SLinus Torvalds return -ENOMEM; 16541da177e4SLinus Torvalds __skb_unlink(skb, &sk->sk_write_queue); 16551da177e4SLinus Torvalds skb_header_release(nskb); 16561da177e4SLinus Torvalds __skb_queue_head(&sk->sk_write_queue, nskb); 16571da177e4SLinus Torvalds sk_stream_free_skb(sk, skb); 16581da177e4SLinus Torvalds sk_charge_skb(sk, nskb); 16591da177e4SLinus Torvalds skb = nskb; 16601da177e4SLinus Torvalds } 16611da177e4SLinus Torvalds 16621da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ACK; 16631da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 16641da177e4SLinus Torvalds } 16651da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 16661da177e4SLinus Torvalds return tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)); 16671da177e4SLinus Torvalds } 16681da177e4SLinus Torvalds 16691da177e4SLinus Torvalds /* 16701da177e4SLinus Torvalds * Prepare a SYN-ACK. 16711da177e4SLinus Torvalds */ 16721da177e4SLinus Torvalds struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, 167360236fddSArnaldo Carvalho de Melo struct request_sock *req) 16741da177e4SLinus Torvalds { 16752e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 16761da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 16771da177e4SLinus Torvalds struct tcphdr *th; 16781da177e4SLinus Torvalds int tcp_header_size; 16791da177e4SLinus Torvalds struct sk_buff *skb; 16801da177e4SLinus Torvalds 16811da177e4SLinus Torvalds skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); 16821da177e4SLinus Torvalds if (skb == NULL) 16831da177e4SLinus Torvalds return NULL; 16841da177e4SLinus Torvalds 16851da177e4SLinus Torvalds /* Reserve space for headers. */ 16861da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 16871da177e4SLinus Torvalds 16881da177e4SLinus Torvalds skb->dst = dst_clone(dst); 16891da177e4SLinus Torvalds 16901da177e4SLinus Torvalds tcp_header_size = (sizeof(struct tcphdr) + TCPOLEN_MSS + 16912e6599cbSArnaldo Carvalho de Melo (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) + 16922e6599cbSArnaldo Carvalho de Melo (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) + 16931da177e4SLinus Torvalds /* SACK_PERM is in the place of NOP NOP of TS */ 16942e6599cbSArnaldo Carvalho de Melo ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0)); 16951da177e4SLinus Torvalds skb->h.th = th = (struct tcphdr *) skb_push(skb, tcp_header_size); 16961da177e4SLinus Torvalds 16971da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 16981da177e4SLinus Torvalds th->syn = 1; 16991da177e4SLinus Torvalds th->ack = 1; 17001da177e4SLinus Torvalds if (dst->dev->features&NETIF_F_TSO) 17012e6599cbSArnaldo Carvalho de Melo ireq->ecn_ok = 0; 17021da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 17031da177e4SLinus Torvalds th->source = inet_sk(sk)->sport; 17042e6599cbSArnaldo Carvalho de Melo th->dest = ireq->rmt_port; 17052e6599cbSArnaldo Carvalho de Melo TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn; 17061da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; 17071da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = 0; 17081da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 17091da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 17101da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 17112e6599cbSArnaldo Carvalho de Melo th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); 17121da177e4SLinus Torvalds if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ 17131da177e4SLinus Torvalds __u8 rcv_wscale; 17141da177e4SLinus Torvalds /* Set this up on the first call only */ 17151da177e4SLinus Torvalds req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); 17161da177e4SLinus Torvalds /* tcp_full_space because it is guaranteed to be the first packet */ 17171da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 17182e6599cbSArnaldo Carvalho de Melo dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), 17191da177e4SLinus Torvalds &req->rcv_wnd, 17201da177e4SLinus Torvalds &req->window_clamp, 17212e6599cbSArnaldo Carvalho de Melo ireq->wscale_ok, 17221da177e4SLinus Torvalds &rcv_wscale); 17232e6599cbSArnaldo Carvalho de Melo ireq->rcv_wscale = rcv_wscale; 17241da177e4SLinus Torvalds } 17251da177e4SLinus Torvalds 17261da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 17271da177e4SLinus Torvalds th->window = htons(req->rcv_wnd); 17281da177e4SLinus Torvalds 17291da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 17302e6599cbSArnaldo Carvalho de Melo tcp_syn_build_options((__u32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok, 17312e6599cbSArnaldo Carvalho de Melo ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale, 17321da177e4SLinus Torvalds TCP_SKB_CB(skb)->when, 17331da177e4SLinus Torvalds req->ts_recent); 17341da177e4SLinus Torvalds 17351da177e4SLinus Torvalds skb->csum = 0; 17361da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 17371da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_OUTSEGS); 17381da177e4SLinus Torvalds return skb; 17391da177e4SLinus Torvalds } 17401da177e4SLinus Torvalds 17411da177e4SLinus Torvalds /* 17421da177e4SLinus Torvalds * Do all connect socket setups that can be done AF independent. 17431da177e4SLinus Torvalds */ 17441da177e4SLinus Torvalds static inline void tcp_connect_init(struct sock *sk) 17451da177e4SLinus Torvalds { 17461da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 17471da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 17481da177e4SLinus Torvalds __u8 rcv_wscale; 17491da177e4SLinus Torvalds 17501da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 17511da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 17521da177e4SLinus Torvalds */ 17531da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 17541da177e4SLinus Torvalds (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 17551da177e4SLinus Torvalds 17561da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 17571da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 17581da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 17591da177e4SLinus Torvalds tp->max_window = 0; 17601da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 17611da177e4SLinus Torvalds 17621da177e4SLinus Torvalds if (!tp->window_clamp) 17631da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 17641da177e4SLinus Torvalds tp->advmss = dst_metric(dst, RTAX_ADVMSS); 17651da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 17661da177e4SLinus Torvalds 17671da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 17681da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 17691da177e4SLinus Torvalds &tp->rcv_wnd, 17701da177e4SLinus Torvalds &tp->window_clamp, 17711da177e4SLinus Torvalds sysctl_tcp_window_scaling, 17721da177e4SLinus Torvalds &rcv_wscale); 17731da177e4SLinus Torvalds 17741da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 17751da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 17761da177e4SLinus Torvalds 17771da177e4SLinus Torvalds sk->sk_err = 0; 17781da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 17791da177e4SLinus Torvalds tp->snd_wnd = 0; 17801da177e4SLinus Torvalds tcp_init_wl(tp, tp->write_seq, 0); 17811da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 17821da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 17831da177e4SLinus Torvalds tp->rcv_nxt = 0; 17841da177e4SLinus Torvalds tp->rcv_wup = 0; 17851da177e4SLinus Torvalds tp->copied_seq = 0; 17861da177e4SLinus Torvalds 17871da177e4SLinus Torvalds tp->rto = TCP_TIMEOUT_INIT; 17881da177e4SLinus Torvalds tp->retransmits = 0; 17891da177e4SLinus Torvalds tcp_clear_retrans(tp); 17901da177e4SLinus Torvalds } 17911da177e4SLinus Torvalds 17921da177e4SLinus Torvalds /* 17931da177e4SLinus Torvalds * Build a SYN and send it off. 17941da177e4SLinus Torvalds */ 17951da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 17961da177e4SLinus Torvalds { 17971da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 17981da177e4SLinus Torvalds struct sk_buff *buff; 17991da177e4SLinus Torvalds 18001da177e4SLinus Torvalds tcp_connect_init(sk); 18011da177e4SLinus Torvalds 18021da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER + 15, sk->sk_allocation); 18031da177e4SLinus Torvalds if (unlikely(buff == NULL)) 18041da177e4SLinus Torvalds return -ENOBUFS; 18051da177e4SLinus Torvalds 18061da177e4SLinus Torvalds /* Reserve space for headers. */ 18071da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 18081da177e4SLinus Torvalds 18091da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN; 18101da177e4SLinus Torvalds TCP_ECN_send_syn(sk, tp, buff); 18111da177e4SLinus Torvalds TCP_SKB_CB(buff)->sacked = 0; 18121da177e4SLinus Torvalds skb_shinfo(buff)->tso_segs = 1; 18131da177e4SLinus Torvalds skb_shinfo(buff)->tso_size = 0; 18141da177e4SLinus Torvalds buff->csum = 0; 18151da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = tp->write_seq++; 18161da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = tp->write_seq; 18171da177e4SLinus Torvalds tp->snd_nxt = tp->write_seq; 18181da177e4SLinus Torvalds tp->pushed_seq = tp->write_seq; 18191da177e4SLinus Torvalds 18201da177e4SLinus Torvalds /* Send it off. */ 18211da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 18221da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(buff)->when; 18231da177e4SLinus Torvalds skb_header_release(buff); 18241da177e4SLinus Torvalds __skb_queue_tail(&sk->sk_write_queue, buff); 18251da177e4SLinus Torvalds sk_charge_skb(sk, buff); 18261da177e4SLinus Torvalds tp->packets_out += tcp_skb_pcount(buff); 18271da177e4SLinus Torvalds tcp_transmit_skb(sk, skb_clone(buff, GFP_KERNEL)); 18281da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_ACTIVEOPENS); 18291da177e4SLinus Torvalds 18301da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 18311da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); 18321da177e4SLinus Torvalds return 0; 18331da177e4SLinus Torvalds } 18341da177e4SLinus Torvalds 18351da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 18361da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 18371da177e4SLinus Torvalds * for details. 18381da177e4SLinus Torvalds */ 18391da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 18401da177e4SLinus Torvalds { 18411da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 18421da177e4SLinus Torvalds int ato = tp->ack.ato; 18431da177e4SLinus Torvalds unsigned long timeout; 18441da177e4SLinus Torvalds 18451da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 18461da177e4SLinus Torvalds int max_ato = HZ/2; 18471da177e4SLinus Torvalds 18481da177e4SLinus Torvalds if (tp->ack.pingpong || (tp->ack.pending&TCP_ACK_PUSHED)) 18491da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 18501da177e4SLinus Torvalds 18511da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 18521da177e4SLinus Torvalds 18531da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 18541da177e4SLinus Torvalds * Do not use tp->rto here, use results of rtt measurements 18551da177e4SLinus Torvalds * directly. 18561da177e4SLinus Torvalds */ 18571da177e4SLinus Torvalds if (tp->srtt) { 18581da177e4SLinus Torvalds int rtt = max(tp->srtt>>3, TCP_DELACK_MIN); 18591da177e4SLinus Torvalds 18601da177e4SLinus Torvalds if (rtt < max_ato) 18611da177e4SLinus Torvalds max_ato = rtt; 18621da177e4SLinus Torvalds } 18631da177e4SLinus Torvalds 18641da177e4SLinus Torvalds ato = min(ato, max_ato); 18651da177e4SLinus Torvalds } 18661da177e4SLinus Torvalds 18671da177e4SLinus Torvalds /* Stay within the limit we were given */ 18681da177e4SLinus Torvalds timeout = jiffies + ato; 18691da177e4SLinus Torvalds 18701da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 18711da177e4SLinus Torvalds if (tp->ack.pending&TCP_ACK_TIMER) { 18721da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 18731da177e4SLinus Torvalds * send ACK now. 18741da177e4SLinus Torvalds */ 18751da177e4SLinus Torvalds if (tp->ack.blocked || time_before_eq(tp->ack.timeout, jiffies+(ato>>2))) { 18761da177e4SLinus Torvalds tcp_send_ack(sk); 18771da177e4SLinus Torvalds return; 18781da177e4SLinus Torvalds } 18791da177e4SLinus Torvalds 18801da177e4SLinus Torvalds if (!time_before(timeout, tp->ack.timeout)) 18811da177e4SLinus Torvalds timeout = tp->ack.timeout; 18821da177e4SLinus Torvalds } 18831da177e4SLinus Torvalds tp->ack.pending |= TCP_ACK_SCHED|TCP_ACK_TIMER; 18841da177e4SLinus Torvalds tp->ack.timeout = timeout; 18851da177e4SLinus Torvalds sk_reset_timer(sk, &tp->delack_timer, timeout); 18861da177e4SLinus Torvalds } 18871da177e4SLinus Torvalds 18881da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 18891da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 18901da177e4SLinus Torvalds { 18911da177e4SLinus Torvalds /* If we have been reset, we may not send again. */ 18921da177e4SLinus Torvalds if (sk->sk_state != TCP_CLOSE) { 18931da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 18941da177e4SLinus Torvalds struct sk_buff *buff; 18951da177e4SLinus Torvalds 18961da177e4SLinus Torvalds /* We are not putting this on the write queue, so 18971da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 18981da177e4SLinus Torvalds * sock. 18991da177e4SLinus Torvalds */ 19001da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 19011da177e4SLinus Torvalds if (buff == NULL) { 19021da177e4SLinus Torvalds tcp_schedule_ack(tp); 19031da177e4SLinus Torvalds tp->ack.ato = TCP_ATO_MIN; 19041da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_DACK, TCP_DELACK_MAX); 19051da177e4SLinus Torvalds return; 19061da177e4SLinus Torvalds } 19071da177e4SLinus Torvalds 19081da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 19091da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 19101da177e4SLinus Torvalds buff->csum = 0; 19111da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK; 19121da177e4SLinus Torvalds TCP_SKB_CB(buff)->sacked = 0; 19131da177e4SLinus Torvalds skb_shinfo(buff)->tso_segs = 1; 19141da177e4SLinus Torvalds skb_shinfo(buff)->tso_size = 0; 19151da177e4SLinus Torvalds 19161da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 19171da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk, tp); 19181da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 19191da177e4SLinus Torvalds tcp_transmit_skb(sk, buff); 19201da177e4SLinus Torvalds } 19211da177e4SLinus Torvalds } 19221da177e4SLinus Torvalds 19231da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 19241da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 19251da177e4SLinus Torvalds * 19261da177e4SLinus Torvalds * Question: what should we make while urgent mode? 19271da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 19281da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 19291da177e4SLinus Torvalds * 19301da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 19311da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 19321da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 19331da177e4SLinus Torvalds */ 19341da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 19351da177e4SLinus Torvalds { 19361da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 19371da177e4SLinus Torvalds struct sk_buff *skb; 19381da177e4SLinus Torvalds 19391da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 19401da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 19411da177e4SLinus Torvalds if (skb == NULL) 19421da177e4SLinus Torvalds return -1; 19431da177e4SLinus Torvalds 19441da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 19451da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 19461da177e4SLinus Torvalds skb->csum = 0; 19471da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK; 19481da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = urgent; 19491da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 19501da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 19511da177e4SLinus Torvalds 19521da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 19531da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 19541da177e4SLinus Torvalds * send it. 19551da177e4SLinus Torvalds */ 19561da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = urgent ? tp->snd_una : tp->snd_una - 1; 19571da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; 19581da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 19591da177e4SLinus Torvalds return tcp_transmit_skb(sk, skb); 19601da177e4SLinus Torvalds } 19611da177e4SLinus Torvalds 19621da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 19631da177e4SLinus Torvalds { 19641da177e4SLinus Torvalds if (sk->sk_state != TCP_CLOSE) { 19651da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 19661da177e4SLinus Torvalds struct sk_buff *skb; 19671da177e4SLinus Torvalds 19681da177e4SLinus Torvalds if ((skb = sk->sk_send_head) != NULL && 19691da177e4SLinus Torvalds before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd)) { 19701da177e4SLinus Torvalds int err; 19711da177e4SLinus Torvalds unsigned int mss = tcp_current_mss(sk, 0); 19721da177e4SLinus Torvalds unsigned int seg_size = tp->snd_una+tp->snd_wnd-TCP_SKB_CB(skb)->seq; 19731da177e4SLinus Torvalds 19741da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 19751da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 19761da177e4SLinus Torvalds 19771da177e4SLinus Torvalds /* We are probing the opening of a window 19781da177e4SLinus Torvalds * but the window size is != 0 19791da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 19801da177e4SLinus Torvalds */ 19811da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 19821da177e4SLinus Torvalds skb->len > mss) { 19831da177e4SLinus Torvalds seg_size = min(seg_size, mss); 19841da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 1985846998aeSDavid S. Miller if (tcp_fragment(sk, skb, seg_size, mss)) 19861da177e4SLinus Torvalds return -1; 19871da177e4SLinus Torvalds /* SWS override triggered forced fragmentation. 19881da177e4SLinus Torvalds * Disable TSO, the connection is too sick. */ 19891da177e4SLinus Torvalds if (sk->sk_route_caps & NETIF_F_TSO) { 19901da177e4SLinus Torvalds sock_set_flag(sk, SOCK_NO_LARGESEND); 19911da177e4SLinus Torvalds sk->sk_route_caps &= ~NETIF_F_TSO; 19921da177e4SLinus Torvalds } 19931da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 1994846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 19951da177e4SLinus Torvalds 19961da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 19971da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 19981da177e4SLinus Torvalds err = tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)); 19991da177e4SLinus Torvalds if (!err) { 20001da177e4SLinus Torvalds update_send_head(sk, tp, skb); 20011da177e4SLinus Torvalds } 20021da177e4SLinus Torvalds return err; 20031da177e4SLinus Torvalds } else { 20041da177e4SLinus Torvalds if (tp->urg_mode && 20051da177e4SLinus Torvalds between(tp->snd_up, tp->snd_una+1, tp->snd_una+0xFFFF)) 20061da177e4SLinus Torvalds tcp_xmit_probe_skb(sk, TCPCB_URG); 20071da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 20081da177e4SLinus Torvalds } 20091da177e4SLinus Torvalds } 20101da177e4SLinus Torvalds return -1; 20111da177e4SLinus Torvalds } 20121da177e4SLinus Torvalds 20131da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 20141da177e4SLinus Torvalds * a partial packet else a zero probe. 20151da177e4SLinus Torvalds */ 20161da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 20171da177e4SLinus Torvalds { 20181da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 20191da177e4SLinus Torvalds int err; 20201da177e4SLinus Torvalds 20211da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 20221da177e4SLinus Torvalds 20231da177e4SLinus Torvalds if (tp->packets_out || !sk->sk_send_head) { 20241da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 20251da177e4SLinus Torvalds tp->probes_out = 0; 20261da177e4SLinus Torvalds tp->backoff = 0; 20271da177e4SLinus Torvalds return; 20281da177e4SLinus Torvalds } 20291da177e4SLinus Torvalds 20301da177e4SLinus Torvalds if (err <= 0) { 20311da177e4SLinus Torvalds if (tp->backoff < sysctl_tcp_retries2) 20321da177e4SLinus Torvalds tp->backoff++; 20331da177e4SLinus Torvalds tp->probes_out++; 20341da177e4SLinus Torvalds tcp_reset_xmit_timer (sk, TCP_TIME_PROBE0, 20351da177e4SLinus Torvalds min(tp->rto << tp->backoff, TCP_RTO_MAX)); 20361da177e4SLinus Torvalds } else { 20371da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 20381da177e4SLinus Torvalds * do not backoff and do not remember probes_out. 20391da177e4SLinus Torvalds * Let local senders to fight for local resources. 20401da177e4SLinus Torvalds * 20411da177e4SLinus Torvalds * Use accumulated backoff yet. 20421da177e4SLinus Torvalds */ 20431da177e4SLinus Torvalds if (!tp->probes_out) 20441da177e4SLinus Torvalds tp->probes_out=1; 20451da177e4SLinus Torvalds tcp_reset_xmit_timer (sk, TCP_TIME_PROBE0, 20461da177e4SLinus Torvalds min(tp->rto << tp->backoff, TCP_RESOURCE_PROBE_INTERVAL)); 20471da177e4SLinus Torvalds } 20481da177e4SLinus Torvalds } 20491da177e4SLinus Torvalds 20501da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_connect); 20511da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_make_synack); 20521da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_simple_retransmit); 20531da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_sync_mss); 2054