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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Implementation of the Transmission Control Protocol(TCP). | |
7 | * | |
8 | * Version: $Id: tcp_output.c,v 1.146 2002/02/01 22:01:04 davem Exp $ | |
9 | * | |
02c30a84 | 10 | * Authors: Ross Biro |
1da177e4 LT |
11 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
12 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
13 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
14 | * Florian La Roche, <flla@stud.uni-sb.de> | |
15 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
16 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
17 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
18 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
19 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
20 | * Jorge Cwik, <jorge@laser.satlink.net> | |
21 | */ | |
22 | ||
23 | /* | |
24 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
25 | * : Fragmentation on mtu decrease | |
26 | * : Segment collapse on retransmit | |
27 | * : AF independence | |
28 | * | |
29 | * Linus Torvalds : send_delayed_ack | |
30 | * David S. Miller : Charge memory using the right skb | |
31 | * during syn/ack processing. | |
32 | * David S. Miller : Output engine completely rewritten. | |
33 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
34 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
35 | * J Hadi Salim : ECN support | |
36 | * | |
37 | */ | |
38 | ||
39 | #include <net/tcp.h> | |
40 | ||
41 | #include <linux/compiler.h> | |
42 | #include <linux/module.h> | |
43 | #include <linux/smp_lock.h> | |
44 | ||
45 | /* People can turn this off for buggy TCP's found in printers etc. */ | |
ab32ea5d | 46 | int sysctl_tcp_retrans_collapse __read_mostly = 1; |
1da177e4 | 47 | |
15d99e02 RJ |
48 | /* People can turn this on to work with those rare, broken TCPs that |
49 | * interpret the window field as a signed quantity. | |
50 | */ | |
ab32ea5d | 51 | int sysctl_tcp_workaround_signed_windows __read_mostly = 0; |
15d99e02 | 52 | |
1da177e4 LT |
53 | /* This limits the percentage of the congestion window which we |
54 | * will allow a single TSO frame to consume. Building TSO frames | |
55 | * which are too large can cause TCP streams to be bursty. | |
56 | */ | |
ab32ea5d | 57 | int sysctl_tcp_tso_win_divisor __read_mostly = 3; |
1da177e4 | 58 | |
ab32ea5d BH |
59 | int sysctl_tcp_mtu_probing __read_mostly = 0; |
60 | int sysctl_tcp_base_mss __read_mostly = 512; | |
5d424d5a | 61 | |
35089bb2 | 62 | /* By default, RFC2861 behavior. */ |
ab32ea5d | 63 | int sysctl_tcp_slow_start_after_idle __read_mostly = 1; |
35089bb2 | 64 | |
40efc6fa SH |
65 | static void update_send_head(struct sock *sk, struct tcp_sock *tp, |
66 | struct sk_buff *skb) | |
1da177e4 LT |
67 | { |
68 | sk->sk_send_head = skb->next; | |
69 | if (sk->sk_send_head == (struct sk_buff *)&sk->sk_write_queue) | |
70 | sk->sk_send_head = NULL; | |
71 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; | |
72 | tcp_packets_out_inc(sk, tp, skb); | |
73 | } | |
74 | ||
75 | /* SND.NXT, if window was not shrunk. | |
76 | * If window has been shrunk, what should we make? It is not clear at all. | |
77 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
78 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
79 | * invalid. OK, let's make this for now: | |
80 | */ | |
81 | static inline __u32 tcp_acceptable_seq(struct sock *sk, struct tcp_sock *tp) | |
82 | { | |
83 | if (!before(tp->snd_una+tp->snd_wnd, tp->snd_nxt)) | |
84 | return tp->snd_nxt; | |
85 | else | |
86 | return tp->snd_una+tp->snd_wnd; | |
87 | } | |
88 | ||
89 | /* Calculate mss to advertise in SYN segment. | |
90 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
91 | * | |
92 | * 1. It is independent of path mtu. | |
93 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
94 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
95 | * attached devices, because some buggy hosts are confused by | |
96 | * large MSS. | |
97 | * 4. We do not make 3, we advertise MSS, calculated from first | |
98 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
99 | * This may be overridden via information stored in routing table. | |
100 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
101 | * probably even Jumbo". | |
102 | */ | |
103 | static __u16 tcp_advertise_mss(struct sock *sk) | |
104 | { | |
105 | struct tcp_sock *tp = tcp_sk(sk); | |
106 | struct dst_entry *dst = __sk_dst_get(sk); | |
107 | int mss = tp->advmss; | |
108 | ||
109 | if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { | |
110 | mss = dst_metric(dst, RTAX_ADVMSS); | |
111 | tp->advmss = mss; | |
112 | } | |
113 | ||
114 | return (__u16)mss; | |
115 | } | |
116 | ||
117 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
118 | * This is the first part of cwnd validation mechanism. */ | |
463c84b9 | 119 | static void tcp_cwnd_restart(struct sock *sk, struct dst_entry *dst) |
1da177e4 | 120 | { |
463c84b9 | 121 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
122 | s32 delta = tcp_time_stamp - tp->lsndtime; |
123 | u32 restart_cwnd = tcp_init_cwnd(tp, dst); | |
124 | u32 cwnd = tp->snd_cwnd; | |
125 | ||
6687e988 | 126 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 127 | |
6687e988 | 128 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
129 | restart_cwnd = min(restart_cwnd, cwnd); |
130 | ||
463c84b9 | 131 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
132 | cwnd >>= 1; |
133 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
134 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
135 | tp->snd_cwnd_used = 0; | |
136 | } | |
137 | ||
40efc6fa SH |
138 | static void tcp_event_data_sent(struct tcp_sock *tp, |
139 | struct sk_buff *skb, struct sock *sk) | |
1da177e4 | 140 | { |
463c84b9 ACM |
141 | struct inet_connection_sock *icsk = inet_csk(sk); |
142 | const u32 now = tcp_time_stamp; | |
1da177e4 | 143 | |
35089bb2 DM |
144 | if (sysctl_tcp_slow_start_after_idle && |
145 | (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) | |
463c84b9 | 146 | tcp_cwnd_restart(sk, __sk_dst_get(sk)); |
1da177e4 LT |
147 | |
148 | tp->lsndtime = now; | |
149 | ||
150 | /* If it is a reply for ato after last received | |
151 | * packet, enter pingpong mode. | |
152 | */ | |
463c84b9 ACM |
153 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
154 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
155 | } |
156 | ||
40efc6fa | 157 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 158 | { |
463c84b9 ACM |
159 | tcp_dec_quickack_mode(sk, pkts); |
160 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
161 | } |
162 | ||
163 | /* Determine a window scaling and initial window to offer. | |
164 | * Based on the assumption that the given amount of space | |
165 | * will be offered. Store the results in the tp structure. | |
166 | * NOTE: for smooth operation initial space offering should | |
167 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
168 | * This MUST be enforced by all callers. | |
169 | */ | |
170 | void tcp_select_initial_window(int __space, __u32 mss, | |
171 | __u32 *rcv_wnd, __u32 *window_clamp, | |
172 | int wscale_ok, __u8 *rcv_wscale) | |
173 | { | |
174 | unsigned int space = (__space < 0 ? 0 : __space); | |
175 | ||
176 | /* If no clamp set the clamp to the max possible scaled window */ | |
177 | if (*window_clamp == 0) | |
178 | (*window_clamp) = (65535 << 14); | |
179 | space = min(*window_clamp, space); | |
180 | ||
181 | /* Quantize space offering to a multiple of mss if possible. */ | |
182 | if (space > mss) | |
183 | space = (space / mss) * mss; | |
184 | ||
185 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
186 | * will break some buggy TCP stacks. If the admin tells us |
187 | * it is likely we could be speaking with such a buggy stack | |
188 | * we will truncate our initial window offering to 32K-1 | |
189 | * unless the remote has sent us a window scaling option, | |
190 | * which we interpret as a sign the remote TCP is not | |
191 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 192 | */ |
15d99e02 RJ |
193 | if (sysctl_tcp_workaround_signed_windows) |
194 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
195 | else | |
196 | (*rcv_wnd) = space; | |
197 | ||
1da177e4 LT |
198 | (*rcv_wscale) = 0; |
199 | if (wscale_ok) { | |
200 | /* Set window scaling on max possible window | |
201 | * See RFC1323 for an explanation of the limit to 14 | |
202 | */ | |
203 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
316c1592 | 204 | space = min_t(u32, space, *window_clamp); |
1da177e4 LT |
205 | while (space > 65535 && (*rcv_wscale) < 14) { |
206 | space >>= 1; | |
207 | (*rcv_wscale)++; | |
208 | } | |
209 | } | |
210 | ||
211 | /* Set initial window to value enough for senders, | |
6b251858 | 212 | * following RFC2414. Senders, not following this RFC, |
1da177e4 LT |
213 | * will be satisfied with 2. |
214 | */ | |
215 | if (mss > (1<<*rcv_wscale)) { | |
01ff367e DM |
216 | int init_cwnd = 4; |
217 | if (mss > 1460*3) | |
1da177e4 | 218 | init_cwnd = 2; |
01ff367e DM |
219 | else if (mss > 1460) |
220 | init_cwnd = 3; | |
1da177e4 LT |
221 | if (*rcv_wnd > init_cwnd*mss) |
222 | *rcv_wnd = init_cwnd*mss; | |
223 | } | |
224 | ||
225 | /* Set the clamp no higher than max representable value */ | |
226 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
227 | } | |
228 | ||
229 | /* Chose a new window to advertise, update state in tcp_sock for the | |
230 | * socket, and return result with RFC1323 scaling applied. The return | |
231 | * value can be stuffed directly into th->window for an outgoing | |
232 | * frame. | |
233 | */ | |
40efc6fa | 234 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
235 | { |
236 | struct tcp_sock *tp = tcp_sk(sk); | |
237 | u32 cur_win = tcp_receive_window(tp); | |
238 | u32 new_win = __tcp_select_window(sk); | |
239 | ||
240 | /* Never shrink the offered window */ | |
241 | if(new_win < cur_win) { | |
242 | /* Danger Will Robinson! | |
243 | * Don't update rcv_wup/rcv_wnd here or else | |
244 | * we will not be able to advertise a zero | |
245 | * window in time. --DaveM | |
246 | * | |
247 | * Relax Will Robinson. | |
248 | */ | |
249 | new_win = cur_win; | |
250 | } | |
251 | tp->rcv_wnd = new_win; | |
252 | tp->rcv_wup = tp->rcv_nxt; | |
253 | ||
254 | /* Make sure we do not exceed the maximum possible | |
255 | * scaled window. | |
256 | */ | |
15d99e02 | 257 | if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) |
1da177e4 LT |
258 | new_win = min(new_win, MAX_TCP_WINDOW); |
259 | else | |
260 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
261 | ||
262 | /* RFC1323 scaling applied */ | |
263 | new_win >>= tp->rx_opt.rcv_wscale; | |
264 | ||
265 | /* If we advertise zero window, disable fast path. */ | |
266 | if (new_win == 0) | |
267 | tp->pred_flags = 0; | |
268 | ||
269 | return new_win; | |
270 | } | |
271 | ||
df7a3b07 | 272 | static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp, |
40efc6fa SH |
273 | __u32 tstamp) |
274 | { | |
275 | if (tp->rx_opt.tstamp_ok) { | |
496c98df YH |
276 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
277 | (TCPOPT_NOP << 16) | | |
278 | (TCPOPT_TIMESTAMP << 8) | | |
279 | TCPOLEN_TIMESTAMP); | |
40efc6fa SH |
280 | *ptr++ = htonl(tstamp); |
281 | *ptr++ = htonl(tp->rx_opt.ts_recent); | |
282 | } | |
283 | if (tp->rx_opt.eff_sacks) { | |
284 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks; | |
285 | int this_sack; | |
286 | ||
287 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
288 | (TCPOPT_NOP << 16) | | |
289 | (TCPOPT_SACK << 8) | | |
290 | (TCPOLEN_SACK_BASE + (tp->rx_opt.eff_sacks * | |
291 | TCPOLEN_SACK_PERBLOCK))); | |
292 | for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) { | |
293 | *ptr++ = htonl(sp[this_sack].start_seq); | |
294 | *ptr++ = htonl(sp[this_sack].end_seq); | |
295 | } | |
296 | if (tp->rx_opt.dsack) { | |
297 | tp->rx_opt.dsack = 0; | |
298 | tp->rx_opt.eff_sacks--; | |
299 | } | |
300 | } | |
301 | } | |
302 | ||
303 | /* Construct a tcp options header for a SYN or SYN_ACK packet. | |
304 | * If this is every changed make sure to change the definition of | |
305 | * MAX_SYN_SIZE to match the new maximum number of options that you | |
306 | * can generate. | |
307 | */ | |
df7a3b07 | 308 | static void tcp_syn_build_options(__be32 *ptr, int mss, int ts, int sack, |
40efc6fa SH |
309 | int offer_wscale, int wscale, __u32 tstamp, |
310 | __u32 ts_recent) | |
311 | { | |
312 | /* We always get an MSS option. | |
313 | * The option bytes which will be seen in normal data | |
314 | * packets should timestamps be used, must be in the MSS | |
315 | * advertised. But we subtract them from tp->mss_cache so | |
316 | * that calculations in tcp_sendmsg are simpler etc. | |
317 | * So account for this fact here if necessary. If we | |
318 | * don't do this correctly, as a receiver we won't | |
319 | * recognize data packets as being full sized when we | |
320 | * should, and thus we won't abide by the delayed ACK | |
321 | * rules correctly. | |
322 | * SACKs don't matter, we never delay an ACK when we | |
323 | * have any of those going out. | |
324 | */ | |
325 | *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss); | |
326 | if (ts) { | |
327 | if(sack) | |
496c98df YH |
328 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
329 | (TCPOLEN_SACK_PERM << 16) | | |
330 | (TCPOPT_TIMESTAMP << 8) | | |
331 | TCPOLEN_TIMESTAMP); | |
40efc6fa | 332 | else |
496c98df YH |
333 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
334 | (TCPOPT_NOP << 16) | | |
335 | (TCPOPT_TIMESTAMP << 8) | | |
336 | TCPOLEN_TIMESTAMP); | |
40efc6fa SH |
337 | *ptr++ = htonl(tstamp); /* TSVAL */ |
338 | *ptr++ = htonl(ts_recent); /* TSECR */ | |
339 | } else if(sack) | |
496c98df YH |
340 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
341 | (TCPOPT_NOP << 16) | | |
342 | (TCPOPT_SACK_PERM << 8) | | |
343 | TCPOLEN_SACK_PERM); | |
40efc6fa | 344 | if (offer_wscale) |
496c98df YH |
345 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
346 | (TCPOPT_WINDOW << 16) | | |
347 | (TCPOLEN_WINDOW << 8) | | |
348 | (wscale)); | |
40efc6fa | 349 | } |
1da177e4 LT |
350 | |
351 | /* This routine actually transmits TCP packets queued in by | |
352 | * tcp_do_sendmsg(). This is used by both the initial | |
353 | * transmission and possible later retransmissions. | |
354 | * All SKB's seen here are completely headerless. It is our | |
355 | * job to build the TCP header, and pass the packet down to | |
356 | * IP so it can do the same plus pass the packet off to the | |
357 | * device. | |
358 | * | |
359 | * We are working here with either a clone of the original | |
360 | * SKB, or a fresh unique copy made by the retransmit engine. | |
361 | */ | |
dfb4b9dc | 362 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, gfp_t gfp_mask) |
1da177e4 | 363 | { |
dfb4b9dc DM |
364 | const struct inet_connection_sock *icsk = inet_csk(sk); |
365 | struct inet_sock *inet; | |
366 | struct tcp_sock *tp; | |
367 | struct tcp_skb_cb *tcb; | |
368 | int tcp_header_size; | |
369 | struct tcphdr *th; | |
370 | int sysctl_flags; | |
371 | int err; | |
372 | ||
373 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
374 | ||
375 | /* If congestion control is doing timestamping, we must | |
376 | * take such a timestamp before we potentially clone/copy. | |
377 | */ | |
378 | if (icsk->icsk_ca_ops->rtt_sample) | |
379 | __net_timestamp(skb); | |
380 | ||
381 | if (likely(clone_it)) { | |
382 | if (unlikely(skb_cloned(skb))) | |
383 | skb = pskb_copy(skb, gfp_mask); | |
384 | else | |
385 | skb = skb_clone(skb, gfp_mask); | |
386 | if (unlikely(!skb)) | |
387 | return -ENOBUFS; | |
388 | } | |
1da177e4 | 389 | |
dfb4b9dc DM |
390 | inet = inet_sk(sk); |
391 | tp = tcp_sk(sk); | |
392 | tcb = TCP_SKB_CB(skb); | |
393 | tcp_header_size = tp->tcp_header_len; | |
1da177e4 LT |
394 | |
395 | #define SYSCTL_FLAG_TSTAMPS 0x1 | |
396 | #define SYSCTL_FLAG_WSCALE 0x2 | |
397 | #define SYSCTL_FLAG_SACK 0x4 | |
398 | ||
dfb4b9dc DM |
399 | sysctl_flags = 0; |
400 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { | |
401 | tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS; | |
402 | if(sysctl_tcp_timestamps) { | |
403 | tcp_header_size += TCPOLEN_TSTAMP_ALIGNED; | |
404 | sysctl_flags |= SYSCTL_FLAG_TSTAMPS; | |
1da177e4 | 405 | } |
dfb4b9dc DM |
406 | if (sysctl_tcp_window_scaling) { |
407 | tcp_header_size += TCPOLEN_WSCALE_ALIGNED; | |
408 | sysctl_flags |= SYSCTL_FLAG_WSCALE; | |
1da177e4 | 409 | } |
dfb4b9dc DM |
410 | if (sysctl_tcp_sack) { |
411 | sysctl_flags |= SYSCTL_FLAG_SACK; | |
412 | if (!(sysctl_flags & SYSCTL_FLAG_TSTAMPS)) | |
413 | tcp_header_size += TCPOLEN_SACKPERM_ALIGNED; | |
1da177e4 | 414 | } |
dfb4b9dc DM |
415 | } else if (unlikely(tp->rx_opt.eff_sacks)) { |
416 | /* A SACK is 2 pad bytes, a 2 byte header, plus | |
417 | * 2 32-bit sequence numbers for each SACK block. | |
418 | */ | |
419 | tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED + | |
420 | (tp->rx_opt.eff_sacks * | |
421 | TCPOLEN_SACK_PERBLOCK)); | |
422 | } | |
423 | ||
424 | if (tcp_packets_in_flight(tp) == 0) | |
425 | tcp_ca_event(sk, CA_EVENT_TX_START); | |
426 | ||
427 | th = (struct tcphdr *) skb_push(skb, tcp_header_size); | |
428 | skb->h.th = th; | |
429 | skb_set_owner_w(skb, sk); | |
430 | ||
431 | /* Build TCP header and checksum it. */ | |
432 | th->source = inet->sport; | |
433 | th->dest = inet->dport; | |
434 | th->seq = htonl(tcb->seq); | |
435 | th->ack_seq = htonl(tp->rcv_nxt); | |
df7a3b07 | 436 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
dfb4b9dc DM |
437 | tcb->flags); |
438 | ||
439 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { | |
440 | /* RFC1323: The window in SYN & SYN/ACK segments | |
441 | * is never scaled. | |
442 | */ | |
443 | th->window = htons(tp->rcv_wnd); | |
444 | } else { | |
445 | th->window = htons(tcp_select_window(sk)); | |
446 | } | |
447 | th->check = 0; | |
448 | th->urg_ptr = 0; | |
1da177e4 | 449 | |
dfb4b9dc DM |
450 | if (unlikely(tp->urg_mode && |
451 | between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF))) { | |
452 | th->urg_ptr = htons(tp->snd_up-tcb->seq); | |
453 | th->urg = 1; | |
454 | } | |
1da177e4 | 455 | |
dfb4b9dc | 456 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { |
df7a3b07 | 457 | tcp_syn_build_options((__be32 *)(th + 1), |
dfb4b9dc DM |
458 | tcp_advertise_mss(sk), |
459 | (sysctl_flags & SYSCTL_FLAG_TSTAMPS), | |
460 | (sysctl_flags & SYSCTL_FLAG_SACK), | |
461 | (sysctl_flags & SYSCTL_FLAG_WSCALE), | |
462 | tp->rx_opt.rcv_wscale, | |
463 | tcb->when, | |
464 | tp->rx_opt.ts_recent); | |
465 | } else { | |
df7a3b07 | 466 | tcp_build_and_update_options((__be32 *)(th + 1), |
dfb4b9dc DM |
467 | tp, tcb->when); |
468 | TCP_ECN_send(sk, tp, skb, tcp_header_size); | |
469 | } | |
1da177e4 | 470 | |
8292a17a | 471 | icsk->icsk_af_ops->send_check(sk, skb->len, skb); |
1da177e4 | 472 | |
dfb4b9dc DM |
473 | if (likely(tcb->flags & TCPCB_FLAG_ACK)) |
474 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); | |
1da177e4 | 475 | |
dfb4b9dc DM |
476 | if (skb->len != tcp_header_size) |
477 | tcp_event_data_sent(tp, skb, sk); | |
1da177e4 | 478 | |
bd37a088 WY |
479 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
480 | TCP_INC_STATS(TCP_MIB_OUTSEGS); | |
1da177e4 | 481 | |
8292a17a | 482 | err = icsk->icsk_af_ops->queue_xmit(skb, 0); |
83de47cd | 483 | if (likely(err <= 0)) |
dfb4b9dc DM |
484 | return err; |
485 | ||
486 | tcp_enter_cwr(sk); | |
487 | ||
488 | /* NET_XMIT_CN is special. It does not guarantee, | |
489 | * that this packet is lost. It tells that device | |
490 | * is about to start to drop packets or already | |
491 | * drops some packets of the same priority and | |
492 | * invokes us to send less aggressively. | |
493 | */ | |
494 | return err == NET_XMIT_CN ? 0 : err; | |
1da177e4 | 495 | |
1da177e4 LT |
496 | #undef SYSCTL_FLAG_TSTAMPS |
497 | #undef SYSCTL_FLAG_WSCALE | |
498 | #undef SYSCTL_FLAG_SACK | |
499 | } | |
500 | ||
501 | ||
502 | /* This routine just queue's the buffer | |
503 | * | |
504 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
505 | * otherwise socket can stall. | |
506 | */ | |
507 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
508 | { | |
509 | struct tcp_sock *tp = tcp_sk(sk); | |
510 | ||
511 | /* Advance write_seq and place onto the write_queue. */ | |
512 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
513 | skb_header_release(skb); | |
514 | __skb_queue_tail(&sk->sk_write_queue, skb); | |
515 | sk_charge_skb(sk, skb); | |
516 | ||
517 | /* Queue it, remembering where we must start sending. */ | |
518 | if (sk->sk_send_head == NULL) | |
519 | sk->sk_send_head = skb; | |
520 | } | |
521 | ||
846998ae | 522 | static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) |
f6302d1d | 523 | { |
bcd76111 | 524 | if (skb->len <= mss_now || !sk_can_gso(sk)) { |
f6302d1d DM |
525 | /* Avoid the costly divide in the normal |
526 | * non-TSO case. | |
527 | */ | |
7967168c HX |
528 | skb_shinfo(skb)->gso_segs = 1; |
529 | skb_shinfo(skb)->gso_size = 0; | |
530 | skb_shinfo(skb)->gso_type = 0; | |
f6302d1d DM |
531 | } else { |
532 | unsigned int factor; | |
533 | ||
846998ae DM |
534 | factor = skb->len + (mss_now - 1); |
535 | factor /= mss_now; | |
7967168c HX |
536 | skb_shinfo(skb)->gso_segs = factor; |
537 | skb_shinfo(skb)->gso_size = mss_now; | |
bcd76111 | 538 | skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
1da177e4 LT |
539 | } |
540 | } | |
541 | ||
1da177e4 LT |
542 | /* Function to create two new TCP segments. Shrinks the given segment |
543 | * to the specified size and appends a new segment with the rest of the | |
544 | * packet to the list. This won't be called frequently, I hope. | |
545 | * Remember, these are still headerless SKBs at this point. | |
546 | */ | |
6475be16 | 547 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss_now) |
1da177e4 LT |
548 | { |
549 | struct tcp_sock *tp = tcp_sk(sk); | |
550 | struct sk_buff *buff; | |
6475be16 | 551 | int nsize, old_factor; |
b60b49ea | 552 | int nlen; |
1da177e4 LT |
553 | u16 flags; |
554 | ||
b2cc99f0 | 555 | BUG_ON(len > skb->len); |
6a438bbe SH |
556 | |
557 | clear_all_retrans_hints(tp); | |
1da177e4 LT |
558 | nsize = skb_headlen(skb) - len; |
559 | if (nsize < 0) | |
560 | nsize = 0; | |
561 | ||
562 | if (skb_cloned(skb) && | |
563 | skb_is_nonlinear(skb) && | |
564 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
565 | return -ENOMEM; | |
566 | ||
567 | /* Get a new skb... force flag on. */ | |
568 | buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); | |
569 | if (buff == NULL) | |
570 | return -ENOMEM; /* We'll just try again later. */ | |
ef5cb973 | 571 | |
b60b49ea HX |
572 | sk_charge_skb(sk, buff); |
573 | nlen = skb->len - len - nsize; | |
574 | buff->truesize += nlen; | |
575 | skb->truesize -= nlen; | |
1da177e4 LT |
576 | |
577 | /* Correct the sequence numbers. */ | |
578 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
579 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
580 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
581 | ||
582 | /* PSH and FIN should only be set in the second packet. */ | |
583 | flags = TCP_SKB_CB(skb)->flags; | |
584 | TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); | |
585 | TCP_SKB_CB(buff)->flags = flags; | |
e14c3caf | 586 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 LT |
587 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_AT_TAIL; |
588 | ||
84fa7933 | 589 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { |
1da177e4 LT |
590 | /* Copy and checksum data tail into the new buffer. */ |
591 | buff->csum = csum_partial_copy_nocheck(skb->data + len, skb_put(buff, nsize), | |
592 | nsize, 0); | |
593 | ||
594 | skb_trim(skb, len); | |
595 | ||
596 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
597 | } else { | |
84fa7933 | 598 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
599 | skb_split(skb, buff, len); |
600 | } | |
601 | ||
602 | buff->ip_summed = skb->ip_summed; | |
603 | ||
604 | /* Looks stupid, but our code really uses when of | |
605 | * skbs, which it never sent before. --ANK | |
606 | */ | |
607 | TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; | |
a61bbcf2 | 608 | buff->tstamp = skb->tstamp; |
1da177e4 | 609 | |
6475be16 DM |
610 | old_factor = tcp_skb_pcount(skb); |
611 | ||
1da177e4 | 612 | /* Fix up tso_factor for both original and new SKB. */ |
846998ae DM |
613 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
614 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
1da177e4 | 615 | |
6475be16 DM |
616 | /* If this packet has been sent out already, we must |
617 | * adjust the various packet counters. | |
618 | */ | |
cf0b450c | 619 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
620 | int diff = old_factor - tcp_skb_pcount(skb) - |
621 | tcp_skb_pcount(buff); | |
1da177e4 | 622 | |
6475be16 | 623 | tp->packets_out -= diff; |
e14c3caf HX |
624 | |
625 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
626 | tp->sacked_out -= diff; | |
627 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
628 | tp->retrans_out -= diff; | |
629 | ||
6475be16 DM |
630 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { |
631 | tp->lost_out -= diff; | |
632 | tp->left_out -= diff; | |
633 | } | |
83ca28be | 634 | |
6475be16 | 635 | if (diff > 0) { |
83ca28be HX |
636 | /* Adjust Reno SACK estimate. */ |
637 | if (!tp->rx_opt.sack_ok) { | |
638 | tp->sacked_out -= diff; | |
639 | if ((int)tp->sacked_out < 0) | |
640 | tp->sacked_out = 0; | |
641 | tcp_sync_left_out(tp); | |
642 | } | |
643 | ||
6475be16 DM |
644 | tp->fackets_out -= diff; |
645 | if ((int)tp->fackets_out < 0) | |
646 | tp->fackets_out = 0; | |
647 | } | |
1da177e4 LT |
648 | } |
649 | ||
650 | /* Link BUFF into the send queue. */ | |
f44b5271 | 651 | skb_header_release(buff); |
8728b834 | 652 | __skb_append(skb, buff, &sk->sk_write_queue); |
1da177e4 LT |
653 | |
654 | return 0; | |
655 | } | |
656 | ||
657 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
658 | * eventually). The difference is that pulled data not copied, but | |
659 | * immediately discarded. | |
660 | */ | |
f2911969 | 661 | static void __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 LT |
662 | { |
663 | int i, k, eat; | |
664 | ||
665 | eat = len; | |
666 | k = 0; | |
667 | for (i=0; i<skb_shinfo(skb)->nr_frags; i++) { | |
668 | if (skb_shinfo(skb)->frags[i].size <= eat) { | |
669 | put_page(skb_shinfo(skb)->frags[i].page); | |
670 | eat -= skb_shinfo(skb)->frags[i].size; | |
671 | } else { | |
672 | skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; | |
673 | if (eat) { | |
674 | skb_shinfo(skb)->frags[k].page_offset += eat; | |
675 | skb_shinfo(skb)->frags[k].size -= eat; | |
676 | eat = 0; | |
677 | } | |
678 | k++; | |
679 | } | |
680 | } | |
681 | skb_shinfo(skb)->nr_frags = k; | |
682 | ||
683 | skb->tail = skb->data; | |
684 | skb->data_len -= len; | |
685 | skb->len = skb->data_len; | |
1da177e4 LT |
686 | } |
687 | ||
688 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) | |
689 | { | |
690 | if (skb_cloned(skb) && | |
691 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
692 | return -ENOMEM; | |
693 | ||
f2911969 HX |
694 | /* If len == headlen, we avoid __skb_pull to preserve alignment. */ |
695 | if (unlikely(len < skb_headlen(skb))) | |
1da177e4 | 696 | __skb_pull(skb, len); |
f2911969 HX |
697 | else |
698 | __pskb_trim_head(skb, len - skb_headlen(skb)); | |
1da177e4 LT |
699 | |
700 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 701 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
702 | |
703 | skb->truesize -= len; | |
704 | sk->sk_wmem_queued -= len; | |
705 | sk->sk_forward_alloc += len; | |
706 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); | |
707 | ||
708 | /* Any change of skb->len requires recalculation of tso | |
709 | * factor and mss. | |
710 | */ | |
711 | if (tcp_skb_pcount(skb) > 1) | |
846998ae | 712 | tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1)); |
1da177e4 LT |
713 | |
714 | return 0; | |
715 | } | |
716 | ||
5d424d5a JH |
717 | /* Not accounting for SACKs here. */ |
718 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
719 | { | |
720 | struct tcp_sock *tp = tcp_sk(sk); | |
721 | struct inet_connection_sock *icsk = inet_csk(sk); | |
722 | int mss_now; | |
723 | ||
724 | /* Calculate base mss without TCP options: | |
725 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
726 | */ | |
727 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
728 | ||
729 | /* Clamp it (mss_clamp does not include tcp options) */ | |
730 | if (mss_now > tp->rx_opt.mss_clamp) | |
731 | mss_now = tp->rx_opt.mss_clamp; | |
732 | ||
733 | /* Now subtract optional transport overhead */ | |
734 | mss_now -= icsk->icsk_ext_hdr_len; | |
735 | ||
736 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
737 | if (mss_now < 48) | |
738 | mss_now = 48; | |
739 | ||
740 | /* Now subtract TCP options size, not including SACKs */ | |
741 | mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); | |
742 | ||
743 | return mss_now; | |
744 | } | |
745 | ||
746 | /* Inverse of above */ | |
747 | int tcp_mss_to_mtu(struct sock *sk, int mss) | |
748 | { | |
749 | struct tcp_sock *tp = tcp_sk(sk); | |
750 | struct inet_connection_sock *icsk = inet_csk(sk); | |
751 | int mtu; | |
752 | ||
753 | mtu = mss + | |
754 | tp->tcp_header_len + | |
755 | icsk->icsk_ext_hdr_len + | |
756 | icsk->icsk_af_ops->net_header_len; | |
757 | ||
758 | return mtu; | |
759 | } | |
760 | ||
761 | void tcp_mtup_init(struct sock *sk) | |
762 | { | |
763 | struct tcp_sock *tp = tcp_sk(sk); | |
764 | struct inet_connection_sock *icsk = inet_csk(sk); | |
765 | ||
766 | icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; | |
767 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + | |
768 | icsk->icsk_af_ops->net_header_len; | |
769 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); | |
770 | icsk->icsk_mtup.probe_size = 0; | |
771 | } | |
772 | ||
1da177e4 LT |
773 | /* This function synchronize snd mss to current pmtu/exthdr set. |
774 | ||
775 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
776 | for TCP options, but includes only bare TCP header. | |
777 | ||
778 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 779 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
780 | It also does not include TCP options. |
781 | ||
d83d8461 | 782 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
783 | |
784 | tp->mss_cache is current effective sending mss, including | |
785 | all tcp options except for SACKs. It is evaluated, | |
786 | taking into account current pmtu, but never exceeds | |
787 | tp->rx_opt.mss_clamp. | |
788 | ||
789 | NOTE1. rfc1122 clearly states that advertised MSS | |
790 | DOES NOT include either tcp or ip options. | |
791 | ||
d83d8461 ACM |
792 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
793 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 LT |
794 | */ |
795 | ||
796 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) | |
797 | { | |
798 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 799 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 800 | int mss_now; |
1da177e4 | 801 | |
5d424d5a JH |
802 | if (icsk->icsk_mtup.search_high > pmtu) |
803 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 804 | |
5d424d5a | 805 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
1da177e4 LT |
806 | |
807 | /* Bound mss with half of window */ | |
808 | if (tp->max_window && mss_now > (tp->max_window>>1)) | |
809 | mss_now = max((tp->max_window>>1), 68U - tp->tcp_header_len); | |
810 | ||
811 | /* And store cached results */ | |
d83d8461 | 812 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
813 | if (icsk->icsk_mtup.enabled) |
814 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 815 | tp->mss_cache = mss_now; |
1da177e4 LT |
816 | |
817 | return mss_now; | |
818 | } | |
819 | ||
820 | /* Compute the current effective MSS, taking SACKs and IP options, | |
821 | * and even PMTU discovery events into account. | |
822 | * | |
823 | * LARGESEND note: !urg_mode is overkill, only frames up to snd_up | |
824 | * cannot be large. However, taking into account rare use of URG, this | |
825 | * is not a big flaw. | |
826 | */ | |
c1b4a7e6 | 827 | unsigned int tcp_current_mss(struct sock *sk, int large_allowed) |
1da177e4 LT |
828 | { |
829 | struct tcp_sock *tp = tcp_sk(sk); | |
830 | struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 DM |
831 | u32 mss_now; |
832 | u16 xmit_size_goal; | |
833 | int doing_tso = 0; | |
834 | ||
835 | mss_now = tp->mss_cache; | |
836 | ||
bcd76111 | 837 | if (large_allowed && sk_can_gso(sk) && !tp->urg_mode) |
c1b4a7e6 | 838 | doing_tso = 1; |
1da177e4 | 839 | |
1da177e4 LT |
840 | if (dst) { |
841 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 842 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
843 | mss_now = tcp_sync_mss(sk, mtu); |
844 | } | |
845 | ||
c1b4a7e6 DM |
846 | if (tp->rx_opt.eff_sacks) |
847 | mss_now -= (TCPOLEN_SACK_BASE_ALIGNED + | |
848 | (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); | |
1da177e4 | 849 | |
c1b4a7e6 | 850 | xmit_size_goal = mss_now; |
1da177e4 | 851 | |
c1b4a7e6 | 852 | if (doing_tso) { |
8292a17a ACM |
853 | xmit_size_goal = (65535 - |
854 | inet_csk(sk)->icsk_af_ops->net_header_len - | |
d83d8461 ACM |
855 | inet_csk(sk)->icsk_ext_hdr_len - |
856 | tp->tcp_header_len); | |
1da177e4 | 857 | |
c1b4a7e6 DM |
858 | if (tp->max_window && |
859 | (xmit_size_goal > (tp->max_window >> 1))) | |
860 | xmit_size_goal = max((tp->max_window >> 1), | |
861 | 68U - tp->tcp_header_len); | |
1da177e4 | 862 | |
c1b4a7e6 | 863 | xmit_size_goal -= (xmit_size_goal % mss_now); |
1da177e4 | 864 | } |
c1b4a7e6 | 865 | tp->xmit_size_goal = xmit_size_goal; |
1da177e4 | 866 | |
1da177e4 LT |
867 | return mss_now; |
868 | } | |
869 | ||
a762a980 DM |
870 | /* Congestion window validation. (RFC2861) */ |
871 | ||
40efc6fa | 872 | static void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp) |
a762a980 DM |
873 | { |
874 | __u32 packets_out = tp->packets_out; | |
875 | ||
876 | if (packets_out >= tp->snd_cwnd) { | |
877 | /* Network is feed fully. */ | |
878 | tp->snd_cwnd_used = 0; | |
879 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
880 | } else { | |
881 | /* Network starves. */ | |
882 | if (tp->packets_out > tp->snd_cwnd_used) | |
883 | tp->snd_cwnd_used = tp->packets_out; | |
884 | ||
463c84b9 | 885 | if ((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) |
a762a980 DM |
886 | tcp_cwnd_application_limited(sk); |
887 | } | |
888 | } | |
889 | ||
c1b4a7e6 DM |
890 | static unsigned int tcp_window_allows(struct tcp_sock *tp, struct sk_buff *skb, unsigned int mss_now, unsigned int cwnd) |
891 | { | |
892 | u32 window, cwnd_len; | |
893 | ||
894 | window = (tp->snd_una + tp->snd_wnd - TCP_SKB_CB(skb)->seq); | |
895 | cwnd_len = mss_now * cwnd; | |
896 | return min(window, cwnd_len); | |
897 | } | |
898 | ||
899 | /* Can at least one segment of SKB be sent right now, according to the | |
900 | * congestion window rules? If so, return how many segments are allowed. | |
901 | */ | |
902 | static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *skb) | |
903 | { | |
904 | u32 in_flight, cwnd; | |
905 | ||
906 | /* Don't be strict about the congestion window for the final FIN. */ | |
907 | if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) | |
908 | return 1; | |
909 | ||
910 | in_flight = tcp_packets_in_flight(tp); | |
911 | cwnd = tp->snd_cwnd; | |
912 | if (in_flight < cwnd) | |
913 | return (cwnd - in_flight); | |
914 | ||
915 | return 0; | |
916 | } | |
917 | ||
918 | /* This must be invoked the first time we consider transmitting | |
919 | * SKB onto the wire. | |
920 | */ | |
40efc6fa | 921 | static int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) |
c1b4a7e6 DM |
922 | { |
923 | int tso_segs = tcp_skb_pcount(skb); | |
924 | ||
846998ae DM |
925 | if (!tso_segs || |
926 | (tso_segs > 1 && | |
7967168c | 927 | tcp_skb_mss(skb) != mss_now)) { |
846998ae | 928 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
929 | tso_segs = tcp_skb_pcount(skb); |
930 | } | |
931 | return tso_segs; | |
932 | } | |
933 | ||
934 | static inline int tcp_minshall_check(const struct tcp_sock *tp) | |
935 | { | |
936 | return after(tp->snd_sml,tp->snd_una) && | |
937 | !after(tp->snd_sml, tp->snd_nxt); | |
938 | } | |
939 | ||
940 | /* Return 0, if packet can be sent now without violation Nagle's rules: | |
941 | * 1. It is full sized. | |
942 | * 2. Or it contains FIN. (already checked by caller) | |
943 | * 3. Or TCP_NODELAY was set. | |
944 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
945 | * With Minshall's modification: all sent small packets are ACKed. | |
946 | */ | |
947 | ||
948 | static inline int tcp_nagle_check(const struct tcp_sock *tp, | |
949 | const struct sk_buff *skb, | |
950 | unsigned mss_now, int nonagle) | |
951 | { | |
952 | return (skb->len < mss_now && | |
953 | ((nonagle&TCP_NAGLE_CORK) || | |
954 | (!nonagle && | |
955 | tp->packets_out && | |
956 | tcp_minshall_check(tp)))); | |
957 | } | |
958 | ||
959 | /* Return non-zero if the Nagle test allows this packet to be | |
960 | * sent now. | |
961 | */ | |
962 | static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, | |
963 | unsigned int cur_mss, int nonagle) | |
964 | { | |
965 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
966 | * write_queue (they have no chances to get new data). | |
967 | * | |
968 | * This is implemented in the callers, where they modify the 'nonagle' | |
969 | * argument based upon the location of SKB in the send queue. | |
970 | */ | |
971 | if (nonagle & TCP_NAGLE_PUSH) | |
972 | return 1; | |
973 | ||
974 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ | |
975 | if (tp->urg_mode || | |
976 | (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) | |
977 | return 1; | |
978 | ||
979 | if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) | |
980 | return 1; | |
981 | ||
982 | return 0; | |
983 | } | |
984 | ||
985 | /* Does at least the first segment of SKB fit into the send window? */ | |
986 | static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, unsigned int cur_mss) | |
987 | { | |
988 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
989 | ||
990 | if (skb->len > cur_mss) | |
991 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
992 | ||
993 | return !after(end_seq, tp->snd_una + tp->snd_wnd); | |
994 | } | |
995 | ||
996 | /* This checks if the data bearing packet SKB (usually sk->sk_send_head) | |
997 | * should be put on the wire right now. If so, it returns the number of | |
998 | * packets allowed by the congestion window. | |
999 | */ | |
1000 | static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, | |
1001 | unsigned int cur_mss, int nonagle) | |
1002 | { | |
1003 | struct tcp_sock *tp = tcp_sk(sk); | |
1004 | unsigned int cwnd_quota; | |
1005 | ||
846998ae | 1006 | tcp_init_tso_segs(sk, skb, cur_mss); |
c1b4a7e6 DM |
1007 | |
1008 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
1009 | return 0; | |
1010 | ||
1011 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
1012 | if (cwnd_quota && | |
1013 | !tcp_snd_wnd_test(tp, skb, cur_mss)) | |
1014 | cwnd_quota = 0; | |
1015 | ||
1016 | return cwnd_quota; | |
1017 | } | |
1018 | ||
1019 | static inline int tcp_skb_is_last(const struct sock *sk, | |
1020 | const struct sk_buff *skb) | |
1021 | { | |
1022 | return skb->next == (struct sk_buff *)&sk->sk_write_queue; | |
1023 | } | |
1024 | ||
1025 | int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp) | |
1026 | { | |
1027 | struct sk_buff *skb = sk->sk_send_head; | |
1028 | ||
1029 | return (skb && | |
1030 | tcp_snd_test(sk, skb, tcp_current_mss(sk, 1), | |
1031 | (tcp_skb_is_last(sk, skb) ? | |
1032 | TCP_NAGLE_PUSH : | |
1033 | tp->nonagle))); | |
1034 | } | |
1035 | ||
1036 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet | |
1037 | * which is put after SKB on the list. It is very much like | |
1038 | * tcp_fragment() except that it may make several kinds of assumptions | |
1039 | * in order to speed up the splitting operation. In particular, we | |
1040 | * know that all the data is in scatter-gather pages, and that the | |
1041 | * packet has never been sent out before (and thus is not cloned). | |
1042 | */ | |
846998ae | 1043 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, unsigned int mss_now) |
c1b4a7e6 DM |
1044 | { |
1045 | struct sk_buff *buff; | |
1046 | int nlen = skb->len - len; | |
1047 | u16 flags; | |
1048 | ||
1049 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 HX |
1050 | if (skb->len != skb->data_len) |
1051 | return tcp_fragment(sk, skb, len, mss_now); | |
c1b4a7e6 DM |
1052 | |
1053 | buff = sk_stream_alloc_pskb(sk, 0, 0, GFP_ATOMIC); | |
1054 | if (unlikely(buff == NULL)) | |
1055 | return -ENOMEM; | |
1056 | ||
b60b49ea HX |
1057 | sk_charge_skb(sk, buff); |
1058 | buff->truesize += nlen; | |
c1b4a7e6 DM |
1059 | skb->truesize -= nlen; |
1060 | ||
1061 | /* Correct the sequence numbers. */ | |
1062 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1063 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1064 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1065 | ||
1066 | /* PSH and FIN should only be set in the second packet. */ | |
1067 | flags = TCP_SKB_CB(skb)->flags; | |
1068 | TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); | |
1069 | TCP_SKB_CB(buff)->flags = flags; | |
1070 | ||
1071 | /* This packet was never sent out yet, so no SACK bits. */ | |
1072 | TCP_SKB_CB(buff)->sacked = 0; | |
1073 | ||
84fa7933 | 1074 | buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; |
c1b4a7e6 DM |
1075 | skb_split(skb, buff, len); |
1076 | ||
1077 | /* Fix up tso_factor for both original and new SKB. */ | |
846998ae DM |
1078 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1079 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
c1b4a7e6 DM |
1080 | |
1081 | /* Link BUFF into the send queue. */ | |
1082 | skb_header_release(buff); | |
8728b834 | 1083 | __skb_append(skb, buff, &sk->sk_write_queue); |
c1b4a7e6 DM |
1084 | |
1085 | return 0; | |
1086 | } | |
1087 | ||
1088 | /* Try to defer sending, if possible, in order to minimize the amount | |
1089 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1090 | * | |
1091 | * This algorithm is from John Heffner. | |
1092 | */ | |
1093 | static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) | |
1094 | { | |
6687e988 | 1095 | const struct inet_connection_sock *icsk = inet_csk(sk); |
c1b4a7e6 DM |
1096 | u32 send_win, cong_win, limit, in_flight; |
1097 | ||
1098 | if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) | |
1099 | return 0; | |
1100 | ||
6687e988 | 1101 | if (icsk->icsk_ca_state != TCP_CA_Open) |
908a75c1 DM |
1102 | return 0; |
1103 | ||
c1b4a7e6 DM |
1104 | in_flight = tcp_packets_in_flight(tp); |
1105 | ||
1106 | BUG_ON(tcp_skb_pcount(skb) <= 1 || | |
1107 | (tp->snd_cwnd <= in_flight)); | |
1108 | ||
1109 | send_win = (tp->snd_una + tp->snd_wnd) - TCP_SKB_CB(skb)->seq; | |
1110 | ||
1111 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1112 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1113 | ||
1114 | limit = min(send_win, cong_win); | |
1115 | ||
ba244fe9 DM |
1116 | /* If a full-sized TSO skb can be sent, do it. */ |
1117 | if (limit >= 65536) | |
1118 | return 0; | |
1119 | ||
c1b4a7e6 DM |
1120 | if (sysctl_tcp_tso_win_divisor) { |
1121 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); | |
1122 | ||
1123 | /* If at least some fraction of a window is available, | |
1124 | * just use it. | |
1125 | */ | |
1126 | chunk /= sysctl_tcp_tso_win_divisor; | |
1127 | if (limit >= chunk) | |
1128 | return 0; | |
1129 | } else { | |
1130 | /* Different approach, try not to defer past a single | |
1131 | * ACK. Receiver should ACK every other full sized | |
1132 | * frame, so if we have space for more than 3 frames | |
1133 | * then send now. | |
1134 | */ | |
1135 | if (limit > tcp_max_burst(tp) * tp->mss_cache) | |
1136 | return 0; | |
1137 | } | |
1138 | ||
1139 | /* Ok, it looks like it is advisable to defer. */ | |
1140 | return 1; | |
1141 | } | |
1142 | ||
5d424d5a JH |
1143 | /* Create a new MTU probe if we are ready. |
1144 | * Returns 0 if we should wait to probe (no cwnd available), | |
1145 | * 1 if a probe was sent, | |
1146 | * -1 otherwise */ | |
1147 | static int tcp_mtu_probe(struct sock *sk) | |
1148 | { | |
1149 | struct tcp_sock *tp = tcp_sk(sk); | |
1150 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1151 | struct sk_buff *skb, *nskb, *next; | |
1152 | int len; | |
1153 | int probe_size; | |
1154 | unsigned int pif; | |
1155 | int copy; | |
1156 | int mss_now; | |
1157 | ||
1158 | /* Not currently probing/verifying, | |
1159 | * not in recovery, | |
1160 | * have enough cwnd, and | |
1161 | * not SACKing (the variable headers throw things off) */ | |
1162 | if (!icsk->icsk_mtup.enabled || | |
1163 | icsk->icsk_mtup.probe_size || | |
1164 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
1165 | tp->snd_cwnd < 11 || | |
1166 | tp->rx_opt.eff_sacks) | |
1167 | return -1; | |
1168 | ||
1169 | /* Very simple search strategy: just double the MSS. */ | |
1170 | mss_now = tcp_current_mss(sk, 0); | |
1171 | probe_size = 2*tp->mss_cache; | |
1172 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { | |
1173 | /* TODO: set timer for probe_converge_event */ | |
1174 | return -1; | |
1175 | } | |
1176 | ||
1177 | /* Have enough data in the send queue to probe? */ | |
1178 | len = 0; | |
1179 | if ((skb = sk->sk_send_head) == NULL) | |
1180 | return -1; | |
1181 | while ((len += skb->len) < probe_size && !tcp_skb_is_last(sk, skb)) | |
1182 | skb = skb->next; | |
1183 | if (len < probe_size) | |
1184 | return -1; | |
1185 | ||
1186 | /* Receive window check. */ | |
1187 | if (after(TCP_SKB_CB(skb)->seq + probe_size, tp->snd_una + tp->snd_wnd)) { | |
1188 | if (tp->snd_wnd < probe_size) | |
1189 | return -1; | |
1190 | else | |
1191 | return 0; | |
1192 | } | |
1193 | ||
1194 | /* Do we need to wait to drain cwnd? */ | |
1195 | pif = tcp_packets_in_flight(tp); | |
1196 | if (pif + 2 > tp->snd_cwnd) { | |
1197 | /* With no packets in flight, don't stall. */ | |
1198 | if (pif == 0) | |
1199 | return -1; | |
1200 | else | |
1201 | return 0; | |
1202 | } | |
1203 | ||
1204 | /* We're allowed to probe. Build it now. */ | |
1205 | if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) | |
1206 | return -1; | |
1207 | sk_charge_skb(sk, nskb); | |
1208 | ||
1209 | skb = sk->sk_send_head; | |
1210 | __skb_insert(nskb, skb->prev, skb, &sk->sk_write_queue); | |
1211 | sk->sk_send_head = nskb; | |
1212 | ||
1213 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
1214 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
1215 | TCP_SKB_CB(nskb)->flags = TCPCB_FLAG_ACK; | |
1216 | TCP_SKB_CB(nskb)->sacked = 0; | |
1217 | nskb->csum = 0; | |
84fa7933 | 1218 | nskb->ip_summed = skb->ip_summed; |
5d424d5a JH |
1219 | |
1220 | len = 0; | |
1221 | while (len < probe_size) { | |
1222 | next = skb->next; | |
1223 | ||
1224 | copy = min_t(int, skb->len, probe_size - len); | |
1225 | if (nskb->ip_summed) | |
1226 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); | |
1227 | else | |
1228 | nskb->csum = skb_copy_and_csum_bits(skb, 0, | |
1229 | skb_put(nskb, copy), copy, nskb->csum); | |
1230 | ||
1231 | if (skb->len <= copy) { | |
1232 | /* We've eaten all the data from this skb. | |
1233 | * Throw it away. */ | |
1234 | TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags; | |
1235 | __skb_unlink(skb, &sk->sk_write_queue); | |
1236 | sk_stream_free_skb(sk, skb); | |
1237 | } else { | |
1238 | TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags & | |
1239 | ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); | |
1240 | if (!skb_shinfo(skb)->nr_frags) { | |
1241 | skb_pull(skb, copy); | |
84fa7933 | 1242 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
5d424d5a JH |
1243 | skb->csum = csum_partial(skb->data, skb->len, 0); |
1244 | } else { | |
1245 | __pskb_trim_head(skb, copy); | |
1246 | tcp_set_skb_tso_segs(sk, skb, mss_now); | |
1247 | } | |
1248 | TCP_SKB_CB(skb)->seq += copy; | |
1249 | } | |
1250 | ||
1251 | len += copy; | |
1252 | skb = next; | |
1253 | } | |
1254 | tcp_init_tso_segs(sk, nskb, nskb->len); | |
1255 | ||
1256 | /* We're ready to send. If this fails, the probe will | |
1257 | * be resegmented into mss-sized pieces by tcp_write_xmit(). */ | |
1258 | TCP_SKB_CB(nskb)->when = tcp_time_stamp; | |
1259 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { | |
1260 | /* Decrement cwnd here because we are sending | |
1261 | * effectively two packets. */ | |
1262 | tp->snd_cwnd--; | |
1263 | update_send_head(sk, tp, nskb); | |
1264 | ||
1265 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
1266 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
1267 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
1268 | |
1269 | return 1; | |
1270 | } | |
1271 | ||
1272 | return -1; | |
1273 | } | |
1274 | ||
1275 | ||
1da177e4 LT |
1276 | /* This routine writes packets to the network. It advances the |
1277 | * send_head. This happens as incoming acks open up the remote | |
1278 | * window for us. | |
1279 | * | |
1280 | * Returns 1, if no segments are in flight and we have queued segments, but | |
1281 | * cannot send anything now because of SWS or another problem. | |
1282 | */ | |
a2e2a59c | 1283 | static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) |
1da177e4 LT |
1284 | { |
1285 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 1286 | struct sk_buff *skb; |
c1b4a7e6 DM |
1287 | unsigned int tso_segs, sent_pkts; |
1288 | int cwnd_quota; | |
5d424d5a | 1289 | int result; |
1da177e4 LT |
1290 | |
1291 | /* If we are closed, the bytes will have to remain here. | |
1292 | * In time closedown will finish, we empty the write queue and all | |
1293 | * will be happy. | |
1294 | */ | |
92df7b51 DM |
1295 | if (unlikely(sk->sk_state == TCP_CLOSE)) |
1296 | return 0; | |
1da177e4 | 1297 | |
92df7b51 | 1298 | sent_pkts = 0; |
5d424d5a JH |
1299 | |
1300 | /* Do MTU probing. */ | |
1301 | if ((result = tcp_mtu_probe(sk)) == 0) { | |
1302 | return 0; | |
1303 | } else if (result > 0) { | |
1304 | sent_pkts = 1; | |
1305 | } | |
1306 | ||
b68e9f85 | 1307 | while ((skb = sk->sk_send_head)) { |
c8ac3774 HX |
1308 | unsigned int limit; |
1309 | ||
b68e9f85 | 1310 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 | 1311 | BUG_ON(!tso_segs); |
aa93466b | 1312 | |
b68e9f85 HX |
1313 | cwnd_quota = tcp_cwnd_test(tp, skb); |
1314 | if (!cwnd_quota) | |
1315 | break; | |
1316 | ||
1317 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) | |
1318 | break; | |
1319 | ||
c1b4a7e6 DM |
1320 | if (tso_segs == 1) { |
1321 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, | |
1322 | (tcp_skb_is_last(sk, skb) ? | |
1323 | nonagle : TCP_NAGLE_PUSH)))) | |
1324 | break; | |
1325 | } else { | |
1326 | if (tcp_tso_should_defer(sk, tp, skb)) | |
1327 | break; | |
1328 | } | |
aa93466b | 1329 | |
c8ac3774 | 1330 | limit = mss_now; |
c1b4a7e6 | 1331 | if (tso_segs > 1) { |
c8ac3774 HX |
1332 | limit = tcp_window_allows(tp, skb, |
1333 | mss_now, cwnd_quota); | |
c1b4a7e6 DM |
1334 | |
1335 | if (skb->len < limit) { | |
1336 | unsigned int trim = skb->len % mss_now; | |
aa93466b | 1337 | |
c1b4a7e6 DM |
1338 | if (trim) |
1339 | limit = skb->len - trim; | |
1340 | } | |
92df7b51 | 1341 | } |
1da177e4 | 1342 | |
c8ac3774 HX |
1343 | if (skb->len > limit && |
1344 | unlikely(tso_fragment(sk, skb, limit, mss_now))) | |
1345 | break; | |
1346 | ||
92df7b51 | 1347 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
c1b4a7e6 | 1348 | |
dfb4b9dc | 1349 | if (unlikely(tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC))) |
92df7b51 | 1350 | break; |
1da177e4 | 1351 | |
92df7b51 DM |
1352 | /* Advance the send_head. This one is sent out. |
1353 | * This call will increment packets_out. | |
1354 | */ | |
1355 | update_send_head(sk, tp, skb); | |
1da177e4 | 1356 | |
92df7b51 | 1357 | tcp_minshall_update(tp, mss_now, skb); |
aa93466b | 1358 | sent_pkts++; |
92df7b51 | 1359 | } |
1da177e4 | 1360 | |
aa93466b | 1361 | if (likely(sent_pkts)) { |
92df7b51 DM |
1362 | tcp_cwnd_validate(sk, tp); |
1363 | return 0; | |
1da177e4 | 1364 | } |
92df7b51 | 1365 | return !tp->packets_out && sk->sk_send_head; |
1da177e4 LT |
1366 | } |
1367 | ||
a762a980 DM |
1368 | /* Push out any pending frames which were held back due to |
1369 | * TCP_CORK or attempt at coalescing tiny packets. | |
1370 | * The socket must be locked by the caller. | |
1371 | */ | |
1372 | void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp, | |
a2e2a59c | 1373 | unsigned int cur_mss, int nonagle) |
a762a980 DM |
1374 | { |
1375 | struct sk_buff *skb = sk->sk_send_head; | |
1376 | ||
1377 | if (skb) { | |
55c97f3e | 1378 | if (tcp_write_xmit(sk, cur_mss, nonagle)) |
a762a980 DM |
1379 | tcp_check_probe_timer(sk, tp); |
1380 | } | |
1381 | } | |
1382 | ||
c1b4a7e6 DM |
1383 | /* Send _single_ skb sitting at the send head. This function requires |
1384 | * true push pending frames to setup probe timer etc. | |
1385 | */ | |
1386 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
1387 | { | |
1388 | struct tcp_sock *tp = tcp_sk(sk); | |
1389 | struct sk_buff *skb = sk->sk_send_head; | |
1390 | unsigned int tso_segs, cwnd_quota; | |
1391 | ||
1392 | BUG_ON(!skb || skb->len < mss_now); | |
1393 | ||
846998ae | 1394 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
1395 | cwnd_quota = tcp_snd_test(sk, skb, mss_now, TCP_NAGLE_PUSH); |
1396 | ||
1397 | if (likely(cwnd_quota)) { | |
c8ac3774 HX |
1398 | unsigned int limit; |
1399 | ||
c1b4a7e6 DM |
1400 | BUG_ON(!tso_segs); |
1401 | ||
c8ac3774 | 1402 | limit = mss_now; |
c1b4a7e6 | 1403 | if (tso_segs > 1) { |
c8ac3774 HX |
1404 | limit = tcp_window_allows(tp, skb, |
1405 | mss_now, cwnd_quota); | |
c1b4a7e6 DM |
1406 | |
1407 | if (skb->len < limit) { | |
1408 | unsigned int trim = skb->len % mss_now; | |
1409 | ||
1410 | if (trim) | |
1411 | limit = skb->len - trim; | |
1412 | } | |
c1b4a7e6 DM |
1413 | } |
1414 | ||
c8ac3774 HX |
1415 | if (skb->len > limit && |
1416 | unlikely(tso_fragment(sk, skb, limit, mss_now))) | |
1417 | return; | |
1418 | ||
c1b4a7e6 DM |
1419 | /* Send it out now. */ |
1420 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
1421 | ||
dfb4b9dc | 1422 | if (likely(!tcp_transmit_skb(sk, skb, 1, sk->sk_allocation))) { |
c1b4a7e6 DM |
1423 | update_send_head(sk, tp, skb); |
1424 | tcp_cwnd_validate(sk, tp); | |
1425 | return; | |
1426 | } | |
1427 | } | |
1428 | } | |
1429 | ||
1da177e4 LT |
1430 | /* This function returns the amount that we can raise the |
1431 | * usable window based on the following constraints | |
1432 | * | |
1433 | * 1. The window can never be shrunk once it is offered (RFC 793) | |
1434 | * 2. We limit memory per socket | |
1435 | * | |
1436 | * RFC 1122: | |
1437 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
1438 | * RECV.NEXT + RCV.WIN fixed until: | |
1439 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
1440 | * | |
1441 | * i.e. don't raise the right edge of the window until you can raise | |
1442 | * it at least MSS bytes. | |
1443 | * | |
1444 | * Unfortunately, the recommended algorithm breaks header prediction, | |
1445 | * since header prediction assumes th->window stays fixed. | |
1446 | * | |
1447 | * Strictly speaking, keeping th->window fixed violates the receiver | |
1448 | * side SWS prevention criteria. The problem is that under this rule | |
1449 | * a stream of single byte packets will cause the right side of the | |
1450 | * window to always advance by a single byte. | |
1451 | * | |
1452 | * Of course, if the sender implements sender side SWS prevention | |
1453 | * then this will not be a problem. | |
1454 | * | |
1455 | * BSD seems to make the following compromise: | |
1456 | * | |
1457 | * If the free space is less than the 1/4 of the maximum | |
1458 | * space available and the free space is less than 1/2 mss, | |
1459 | * then set the window to 0. | |
1460 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
1461 | * Otherwise, just prevent the window from shrinking | |
1462 | * and from being larger than the largest representable value. | |
1463 | * | |
1464 | * This prevents incremental opening of the window in the regime | |
1465 | * where TCP is limited by the speed of the reader side taking | |
1466 | * data out of the TCP receive queue. It does nothing about | |
1467 | * those cases where the window is constrained on the sender side | |
1468 | * because the pipeline is full. | |
1469 | * | |
1470 | * BSD also seems to "accidentally" limit itself to windows that are a | |
1471 | * multiple of MSS, at least until the free space gets quite small. | |
1472 | * This would appear to be a side effect of the mbuf implementation. | |
1473 | * Combining these two algorithms results in the observed behavior | |
1474 | * of having a fixed window size at almost all times. | |
1475 | * | |
1476 | * Below we obtain similar behavior by forcing the offered window to | |
1477 | * a multiple of the mss when it is feasible to do so. | |
1478 | * | |
1479 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
1480 | * Regular options like TIMESTAMP are taken into account. | |
1481 | */ | |
1482 | u32 __tcp_select_window(struct sock *sk) | |
1483 | { | |
463c84b9 | 1484 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 1485 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 1486 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
1487 | * here. I don't know if the value based on our guesses |
1488 | * of peer's MSS is better for the performance. It's more correct | |
1489 | * but may be worse for the performance because of rcv_mss | |
1490 | * fluctuations. --SAW 1998/11/1 | |
1491 | */ | |
463c84b9 | 1492 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 LT |
1493 | int free_space = tcp_space(sk); |
1494 | int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); | |
1495 | int window; | |
1496 | ||
1497 | if (mss > full_space) | |
1498 | mss = full_space; | |
1499 | ||
1500 | if (free_space < full_space/2) { | |
463c84b9 | 1501 | icsk->icsk_ack.quick = 0; |
1da177e4 LT |
1502 | |
1503 | if (tcp_memory_pressure) | |
1504 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U*tp->advmss); | |
1505 | ||
1506 | if (free_space < mss) | |
1507 | return 0; | |
1508 | } | |
1509 | ||
1510 | if (free_space > tp->rcv_ssthresh) | |
1511 | free_space = tp->rcv_ssthresh; | |
1512 | ||
1513 | /* Don't do rounding if we are using window scaling, since the | |
1514 | * scaled window will not line up with the MSS boundary anyway. | |
1515 | */ | |
1516 | window = tp->rcv_wnd; | |
1517 | if (tp->rx_opt.rcv_wscale) { | |
1518 | window = free_space; | |
1519 | ||
1520 | /* Advertise enough space so that it won't get scaled away. | |
1521 | * Import case: prevent zero window announcement if | |
1522 | * 1<<rcv_wscale > mss. | |
1523 | */ | |
1524 | if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) | |
1525 | window = (((window >> tp->rx_opt.rcv_wscale) + 1) | |
1526 | << tp->rx_opt.rcv_wscale); | |
1527 | } else { | |
1528 | /* Get the largest window that is a nice multiple of mss. | |
1529 | * Window clamp already applied above. | |
1530 | * If our current window offering is within 1 mss of the | |
1531 | * free space we just keep it. This prevents the divide | |
1532 | * and multiply from happening most of the time. | |
1533 | * We also don't do any window rounding when the free space | |
1534 | * is too small. | |
1535 | */ | |
1536 | if (window <= free_space - mss || window > free_space) | |
1537 | window = (free_space/mss)*mss; | |
1538 | } | |
1539 | ||
1540 | return window; | |
1541 | } | |
1542 | ||
1543 | /* Attempt to collapse two adjacent SKB's during retransmission. */ | |
1544 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int mss_now) | |
1545 | { | |
1546 | struct tcp_sock *tp = tcp_sk(sk); | |
1547 | struct sk_buff *next_skb = skb->next; | |
1548 | ||
1549 | /* The first test we must make is that neither of these two | |
1550 | * SKB's are still referenced by someone else. | |
1551 | */ | |
1552 | if (!skb_cloned(skb) && !skb_cloned(next_skb)) { | |
1553 | int skb_size = skb->len, next_skb_size = next_skb->len; | |
1554 | u16 flags = TCP_SKB_CB(skb)->flags; | |
1555 | ||
1556 | /* Also punt if next skb has been SACK'd. */ | |
1557 | if(TCP_SKB_CB(next_skb)->sacked & TCPCB_SACKED_ACKED) | |
1558 | return; | |
1559 | ||
1560 | /* Next skb is out of window. */ | |
1561 | if (after(TCP_SKB_CB(next_skb)->end_seq, tp->snd_una+tp->snd_wnd)) | |
1562 | return; | |
1563 | ||
1564 | /* Punt if not enough space exists in the first SKB for | |
1565 | * the data in the second, or the total combined payload | |
1566 | * would exceed the MSS. | |
1567 | */ | |
1568 | if ((next_skb_size > skb_tailroom(skb)) || | |
1569 | ((skb_size + next_skb_size) > mss_now)) | |
1570 | return; | |
1571 | ||
1572 | BUG_ON(tcp_skb_pcount(skb) != 1 || | |
1573 | tcp_skb_pcount(next_skb) != 1); | |
1574 | ||
6a438bbe SH |
1575 | /* changing transmit queue under us so clear hints */ |
1576 | clear_all_retrans_hints(tp); | |
1577 | ||
1578 | /* Ok. We will be able to collapse the packet. */ | |
8728b834 | 1579 | __skb_unlink(next_skb, &sk->sk_write_queue); |
1da177e4 LT |
1580 | |
1581 | memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size); | |
1582 | ||
84fa7933 | 1583 | skb->ip_summed = next_skb->ip_summed; |
1da177e4 | 1584 | |
84fa7933 | 1585 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
1da177e4 LT |
1586 | skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); |
1587 | ||
1588 | /* Update sequence range on original skb. */ | |
1589 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1590 | ||
1591 | /* Merge over control information. */ | |
1592 | flags |= TCP_SKB_CB(next_skb)->flags; /* This moves PSH/FIN etc. over */ | |
1593 | TCP_SKB_CB(skb)->flags = flags; | |
1594 | ||
1595 | /* All done, get rid of second SKB and account for it so | |
1596 | * packet counting does not break. | |
1597 | */ | |
1598 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked&(TCPCB_EVER_RETRANS|TCPCB_AT_TAIL); | |
1599 | if (TCP_SKB_CB(next_skb)->sacked&TCPCB_SACKED_RETRANS) | |
1600 | tp->retrans_out -= tcp_skb_pcount(next_skb); | |
1601 | if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST) { | |
1602 | tp->lost_out -= tcp_skb_pcount(next_skb); | |
1603 | tp->left_out -= tcp_skb_pcount(next_skb); | |
1604 | } | |
1605 | /* Reno case is special. Sigh... */ | |
1606 | if (!tp->rx_opt.sack_ok && tp->sacked_out) { | |
1607 | tcp_dec_pcount_approx(&tp->sacked_out, next_skb); | |
1608 | tp->left_out -= tcp_skb_pcount(next_skb); | |
1609 | } | |
1610 | ||
1611 | /* Not quite right: it can be > snd.fack, but | |
1612 | * it is better to underestimate fackets. | |
1613 | */ | |
1614 | tcp_dec_pcount_approx(&tp->fackets_out, next_skb); | |
1615 | tcp_packets_out_dec(tp, next_skb); | |
1616 | sk_stream_free_skb(sk, next_skb); | |
1617 | } | |
1618 | } | |
1619 | ||
1620 | /* Do a simple retransmit without using the backoff mechanisms in | |
1621 | * tcp_timer. This is used for path mtu discovery. | |
1622 | * The socket is already locked here. | |
1623 | */ | |
1624 | void tcp_simple_retransmit(struct sock *sk) | |
1625 | { | |
6687e988 | 1626 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1627 | struct tcp_sock *tp = tcp_sk(sk); |
1628 | struct sk_buff *skb; | |
1629 | unsigned int mss = tcp_current_mss(sk, 0); | |
1630 | int lost = 0; | |
1631 | ||
1632 | sk_stream_for_retrans_queue(skb, sk) { | |
1633 | if (skb->len > mss && | |
1634 | !(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) { | |
1635 | if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { | |
1636 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; | |
1637 | tp->retrans_out -= tcp_skb_pcount(skb); | |
1638 | } | |
1639 | if (!(TCP_SKB_CB(skb)->sacked&TCPCB_LOST)) { | |
1640 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1641 | tp->lost_out += tcp_skb_pcount(skb); | |
1642 | lost = 1; | |
1643 | } | |
1644 | } | |
1645 | } | |
1646 | ||
6a438bbe SH |
1647 | clear_all_retrans_hints(tp); |
1648 | ||
1da177e4 LT |
1649 | if (!lost) |
1650 | return; | |
1651 | ||
1652 | tcp_sync_left_out(tp); | |
1653 | ||
1654 | /* Don't muck with the congestion window here. | |
1655 | * Reason is that we do not increase amount of _data_ | |
1656 | * in network, but units changed and effective | |
1657 | * cwnd/ssthresh really reduced now. | |
1658 | */ | |
6687e988 | 1659 | if (icsk->icsk_ca_state != TCP_CA_Loss) { |
1da177e4 | 1660 | tp->high_seq = tp->snd_nxt; |
6687e988 | 1661 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
1662 | tp->prior_ssthresh = 0; |
1663 | tp->undo_marker = 0; | |
6687e988 | 1664 | tcp_set_ca_state(sk, TCP_CA_Loss); |
1da177e4 LT |
1665 | } |
1666 | tcp_xmit_retransmit_queue(sk); | |
1667 | } | |
1668 | ||
1669 | /* This retransmits one SKB. Policy decisions and retransmit queue | |
1670 | * state updates are done by the caller. Returns non-zero if an | |
1671 | * error occurred which prevented the send. | |
1672 | */ | |
1673 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) | |
1674 | { | |
1675 | struct tcp_sock *tp = tcp_sk(sk); | |
5d424d5a | 1676 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1677 | unsigned int cur_mss = tcp_current_mss(sk, 0); |
1678 | int err; | |
1679 | ||
5d424d5a JH |
1680 | /* Inconslusive MTU probe */ |
1681 | if (icsk->icsk_mtup.probe_size) { | |
1682 | icsk->icsk_mtup.probe_size = 0; | |
1683 | } | |
1684 | ||
1da177e4 | 1685 | /* Do not sent more than we queued. 1/4 is reserved for possible |
caa20d9a | 1686 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 LT |
1687 | */ |
1688 | if (atomic_read(&sk->sk_wmem_alloc) > | |
1689 | min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) | |
1690 | return -EAGAIN; | |
1691 | ||
1692 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { | |
1693 | if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
1694 | BUG(); | |
1da177e4 LT |
1695 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
1696 | return -ENOMEM; | |
1697 | } | |
1698 | ||
1699 | /* If receiver has shrunk his window, and skb is out of | |
1700 | * new window, do not retransmit it. The exception is the | |
1701 | * case, when window is shrunk to zero. In this case | |
1702 | * our retransmit serves as a zero window probe. | |
1703 | */ | |
1704 | if (!before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd) | |
1705 | && TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1706 | return -EAGAIN; | |
1707 | ||
1708 | if (skb->len > cur_mss) { | |
846998ae | 1709 | if (tcp_fragment(sk, skb, cur_mss, cur_mss)) |
1da177e4 | 1710 | return -ENOMEM; /* We'll try again later. */ |
1da177e4 LT |
1711 | } |
1712 | ||
1713 | /* Collapse two adjacent packets if worthwhile and we can. */ | |
1714 | if(!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN) && | |
1715 | (skb->len < (cur_mss >> 1)) && | |
1716 | (skb->next != sk->sk_send_head) && | |
1717 | (skb->next != (struct sk_buff *)&sk->sk_write_queue) && | |
1718 | (skb_shinfo(skb)->nr_frags == 0 && skb_shinfo(skb->next)->nr_frags == 0) && | |
1719 | (tcp_skb_pcount(skb) == 1 && tcp_skb_pcount(skb->next) == 1) && | |
1720 | (sysctl_tcp_retrans_collapse != 0)) | |
1721 | tcp_retrans_try_collapse(sk, skb, cur_mss); | |
1722 | ||
8292a17a | 1723 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
1da177e4 LT |
1724 | return -EHOSTUNREACH; /* Routing failure or similar. */ |
1725 | ||
1726 | /* Some Solaris stacks overoptimize and ignore the FIN on a | |
1727 | * retransmit when old data is attached. So strip it off | |
1728 | * since it is cheap to do so and saves bytes on the network. | |
1729 | */ | |
1730 | if(skb->len > 0 && | |
1731 | (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && | |
1732 | tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { | |
1733 | if (!pskb_trim(skb, 0)) { | |
1734 | TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1; | |
7967168c HX |
1735 | skb_shinfo(skb)->gso_segs = 1; |
1736 | skb_shinfo(skb)->gso_size = 0; | |
1737 | skb_shinfo(skb)->gso_type = 0; | |
1da177e4 LT |
1738 | skb->ip_summed = CHECKSUM_NONE; |
1739 | skb->csum = 0; | |
1740 | } | |
1741 | } | |
1742 | ||
1743 | /* Make a copy, if the first transmission SKB clone we made | |
1744 | * is still in somebody's hands, else make a clone. | |
1745 | */ | |
1746 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
1da177e4 | 1747 | |
dfb4b9dc | 1748 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
1749 | |
1750 | if (err == 0) { | |
1751 | /* Update global TCP statistics. */ | |
1752 | TCP_INC_STATS(TCP_MIB_RETRANSSEGS); | |
1753 | ||
1754 | tp->total_retrans++; | |
1755 | ||
1756 | #if FASTRETRANS_DEBUG > 0 | |
1757 | if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { | |
1758 | if (net_ratelimit()) | |
1759 | printk(KERN_DEBUG "retrans_out leaked.\n"); | |
1760 | } | |
1761 | #endif | |
1762 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; | |
1763 | tp->retrans_out += tcp_skb_pcount(skb); | |
1764 | ||
1765 | /* Save stamp of the first retransmit. */ | |
1766 | if (!tp->retrans_stamp) | |
1767 | tp->retrans_stamp = TCP_SKB_CB(skb)->when; | |
1768 | ||
1769 | tp->undo_retrans++; | |
1770 | ||
1771 | /* snd_nxt is stored to detect loss of retransmitted segment, | |
1772 | * see tcp_input.c tcp_sacktag_write_queue(). | |
1773 | */ | |
1774 | TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; | |
1775 | } | |
1776 | return err; | |
1777 | } | |
1778 | ||
1779 | /* This gets called after a retransmit timeout, and the initially | |
1780 | * retransmitted data is acknowledged. It tries to continue | |
1781 | * resending the rest of the retransmit queue, until either | |
1782 | * we've sent it all or the congestion window limit is reached. | |
1783 | * If doing SACK, the first ACK which comes back for a timeout | |
1784 | * based retransmit packet might feed us FACK information again. | |
1785 | * If so, we use it to avoid unnecessarily retransmissions. | |
1786 | */ | |
1787 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
1788 | { | |
6687e988 | 1789 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1790 | struct tcp_sock *tp = tcp_sk(sk); |
1791 | struct sk_buff *skb; | |
6a438bbe SH |
1792 | int packet_cnt; |
1793 | ||
1794 | if (tp->retransmit_skb_hint) { | |
1795 | skb = tp->retransmit_skb_hint; | |
1796 | packet_cnt = tp->retransmit_cnt_hint; | |
1797 | }else{ | |
1798 | skb = sk->sk_write_queue.next; | |
1799 | packet_cnt = 0; | |
1800 | } | |
1da177e4 LT |
1801 | |
1802 | /* First pass: retransmit lost packets. */ | |
6a438bbe SH |
1803 | if (tp->lost_out) { |
1804 | sk_stream_for_retrans_queue_from(skb, sk) { | |
1da177e4 LT |
1805 | __u8 sacked = TCP_SKB_CB(skb)->sacked; |
1806 | ||
6a438bbe SH |
1807 | /* we could do better than to assign each time */ |
1808 | tp->retransmit_skb_hint = skb; | |
1809 | tp->retransmit_cnt_hint = packet_cnt; | |
1810 | ||
1da177e4 LT |
1811 | /* Assume this retransmit will generate |
1812 | * only one packet for congestion window | |
1813 | * calculation purposes. This works because | |
1814 | * tcp_retransmit_skb() will chop up the | |
1815 | * packet to be MSS sized and all the | |
1816 | * packet counting works out. | |
1817 | */ | |
1818 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
1819 | return; | |
1820 | ||
6a438bbe | 1821 | if (sacked & TCPCB_LOST) { |
1da177e4 | 1822 | if (!(sacked&(TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) { |
6a438bbe SH |
1823 | if (tcp_retransmit_skb(sk, skb)) { |
1824 | tp->retransmit_skb_hint = NULL; | |
1da177e4 | 1825 | return; |
6a438bbe | 1826 | } |
6687e988 | 1827 | if (icsk->icsk_ca_state != TCP_CA_Loss) |
1da177e4 LT |
1828 | NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS); |
1829 | else | |
1830 | NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS); | |
1831 | ||
1832 | if (skb == | |
1833 | skb_peek(&sk->sk_write_queue)) | |
463c84b9 | 1834 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3f421baa ACM |
1835 | inet_csk(sk)->icsk_rto, |
1836 | TCP_RTO_MAX); | |
1da177e4 LT |
1837 | } |
1838 | ||
6a438bbe SH |
1839 | packet_cnt += tcp_skb_pcount(skb); |
1840 | if (packet_cnt >= tp->lost_out) | |
1da177e4 LT |
1841 | break; |
1842 | } | |
1843 | } | |
1844 | } | |
1845 | ||
1846 | /* OK, demanded retransmission is finished. */ | |
1847 | ||
1848 | /* Forward retransmissions are possible only during Recovery. */ | |
6687e988 | 1849 | if (icsk->icsk_ca_state != TCP_CA_Recovery) |
1da177e4 LT |
1850 | return; |
1851 | ||
1852 | /* No forward retransmissions in Reno are possible. */ | |
1853 | if (!tp->rx_opt.sack_ok) | |
1854 | return; | |
1855 | ||
1856 | /* Yeah, we have to make difficult choice between forward transmission | |
1857 | * and retransmission... Both ways have their merits... | |
1858 | * | |
1859 | * For now we do not retransmit anything, while we have some new | |
1860 | * segments to send. | |
1861 | */ | |
1862 | ||
1863 | if (tcp_may_send_now(sk, tp)) | |
1864 | return; | |
1865 | ||
6a438bbe SH |
1866 | if (tp->forward_skb_hint) { |
1867 | skb = tp->forward_skb_hint; | |
1868 | packet_cnt = tp->forward_cnt_hint; | |
1869 | } else{ | |
1870 | skb = sk->sk_write_queue.next; | |
1871 | packet_cnt = 0; | |
1872 | } | |
1873 | ||
1874 | sk_stream_for_retrans_queue_from(skb, sk) { | |
1875 | tp->forward_cnt_hint = packet_cnt; | |
1876 | tp->forward_skb_hint = skb; | |
1da177e4 | 1877 | |
1da177e4 LT |
1878 | /* Similar to the retransmit loop above we |
1879 | * can pretend that the retransmitted SKB | |
1880 | * we send out here will be composed of one | |
1881 | * real MSS sized packet because tcp_retransmit_skb() | |
1882 | * will fragment it if necessary. | |
1883 | */ | |
1884 | if (++packet_cnt > tp->fackets_out) | |
1885 | break; | |
1886 | ||
1887 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
1888 | break; | |
1889 | ||
1890 | if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) | |
1891 | continue; | |
1892 | ||
1893 | /* Ok, retransmit it. */ | |
6a438bbe SH |
1894 | if (tcp_retransmit_skb(sk, skb)) { |
1895 | tp->forward_skb_hint = NULL; | |
1da177e4 | 1896 | break; |
6a438bbe | 1897 | } |
1da177e4 LT |
1898 | |
1899 | if (skb == skb_peek(&sk->sk_write_queue)) | |
3f421baa ACM |
1900 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
1901 | inet_csk(sk)->icsk_rto, | |
1902 | TCP_RTO_MAX); | |
1da177e4 LT |
1903 | |
1904 | NET_INC_STATS_BH(LINUX_MIB_TCPFORWARDRETRANS); | |
1905 | } | |
1906 | } | |
1907 | ||
1908 | ||
1909 | /* Send a fin. The caller locks the socket for us. This cannot be | |
1910 | * allowed to fail queueing a FIN frame under any circumstances. | |
1911 | */ | |
1912 | void tcp_send_fin(struct sock *sk) | |
1913 | { | |
1914 | struct tcp_sock *tp = tcp_sk(sk); | |
1915 | struct sk_buff *skb = skb_peek_tail(&sk->sk_write_queue); | |
1916 | int mss_now; | |
1917 | ||
1918 | /* Optimization, tack on the FIN if we have a queue of | |
1919 | * unsent frames. But be careful about outgoing SACKS | |
1920 | * and IP options. | |
1921 | */ | |
1922 | mss_now = tcp_current_mss(sk, 1); | |
1923 | ||
1924 | if (sk->sk_send_head != NULL) { | |
1925 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; | |
1926 | TCP_SKB_CB(skb)->end_seq++; | |
1927 | tp->write_seq++; | |
1928 | } else { | |
1929 | /* Socket is locked, keep trying until memory is available. */ | |
1930 | for (;;) { | |
d179cd12 | 1931 | skb = alloc_skb_fclone(MAX_TCP_HEADER, GFP_KERNEL); |
1da177e4 LT |
1932 | if (skb) |
1933 | break; | |
1934 | yield(); | |
1935 | } | |
1936 | ||
1937 | /* Reserve space for headers and prepare control bits. */ | |
1938 | skb_reserve(skb, MAX_TCP_HEADER); | |
1939 | skb->csum = 0; | |
1940 | TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); | |
1941 | TCP_SKB_CB(skb)->sacked = 0; | |
7967168c HX |
1942 | skb_shinfo(skb)->gso_segs = 1; |
1943 | skb_shinfo(skb)->gso_size = 0; | |
1944 | skb_shinfo(skb)->gso_type = 0; | |
1da177e4 LT |
1945 | |
1946 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ | |
1947 | TCP_SKB_CB(skb)->seq = tp->write_seq; | |
1948 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; | |
1949 | tcp_queue_skb(sk, skb); | |
1950 | } | |
1951 | __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_OFF); | |
1952 | } | |
1953 | ||
1954 | /* We get here when a process closes a file descriptor (either due to | |
1955 | * an explicit close() or as a byproduct of exit()'ing) and there | |
1956 | * was unread data in the receive queue. This behavior is recommended | |
1957 | * by draft-ietf-tcpimpl-prob-03.txt section 3.10. -DaveM | |
1958 | */ | |
dd0fc66f | 1959 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 LT |
1960 | { |
1961 | struct tcp_sock *tp = tcp_sk(sk); | |
1962 | struct sk_buff *skb; | |
1963 | ||
1964 | /* NOTE: No TCP options attached and we never retransmit this. */ | |
1965 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
1966 | if (!skb) { | |
1967 | NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); | |
1968 | return; | |
1969 | } | |
1970 | ||
1971 | /* Reserve space for headers and prepare control bits. */ | |
1972 | skb_reserve(skb, MAX_TCP_HEADER); | |
1973 | skb->csum = 0; | |
1974 | TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST); | |
1975 | TCP_SKB_CB(skb)->sacked = 0; | |
7967168c HX |
1976 | skb_shinfo(skb)->gso_segs = 1; |
1977 | skb_shinfo(skb)->gso_size = 0; | |
1978 | skb_shinfo(skb)->gso_type = 0; | |
1da177e4 LT |
1979 | |
1980 | /* Send it off. */ | |
1981 | TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk, tp); | |
1982 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; | |
1983 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 1984 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
1da177e4 LT |
1985 | NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); |
1986 | } | |
1987 | ||
1988 | /* WARNING: This routine must only be called when we have already sent | |
1989 | * a SYN packet that crossed the incoming SYN that caused this routine | |
1990 | * to get called. If this assumption fails then the initial rcv_wnd | |
1991 | * and rcv_wscale values will not be correct. | |
1992 | */ | |
1993 | int tcp_send_synack(struct sock *sk) | |
1994 | { | |
1995 | struct sk_buff* skb; | |
1996 | ||
1997 | skb = skb_peek(&sk->sk_write_queue); | |
1998 | if (skb == NULL || !(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_SYN)) { | |
1999 | printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); | |
2000 | return -EFAULT; | |
2001 | } | |
2002 | if (!(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_ACK)) { | |
2003 | if (skb_cloned(skb)) { | |
2004 | struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); | |
2005 | if (nskb == NULL) | |
2006 | return -ENOMEM; | |
2007 | __skb_unlink(skb, &sk->sk_write_queue); | |
2008 | skb_header_release(nskb); | |
2009 | __skb_queue_head(&sk->sk_write_queue, nskb); | |
2010 | sk_stream_free_skb(sk, skb); | |
2011 | sk_charge_skb(sk, nskb); | |
2012 | skb = nskb; | |
2013 | } | |
2014 | ||
2015 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ACK; | |
2016 | TCP_ECN_send_synack(tcp_sk(sk), skb); | |
2017 | } | |
2018 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2019 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2020 | } |
2021 | ||
2022 | /* | |
2023 | * Prepare a SYN-ACK. | |
2024 | */ | |
2025 | struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, | |
60236fdd | 2026 | struct request_sock *req) |
1da177e4 | 2027 | { |
2e6599cb | 2028 | struct inet_request_sock *ireq = inet_rsk(req); |
1da177e4 LT |
2029 | struct tcp_sock *tp = tcp_sk(sk); |
2030 | struct tcphdr *th; | |
2031 | int tcp_header_size; | |
2032 | struct sk_buff *skb; | |
2033 | ||
2034 | skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); | |
2035 | if (skb == NULL) | |
2036 | return NULL; | |
2037 | ||
2038 | /* Reserve space for headers. */ | |
2039 | skb_reserve(skb, MAX_TCP_HEADER); | |
2040 | ||
2041 | skb->dst = dst_clone(dst); | |
2042 | ||
2043 | tcp_header_size = (sizeof(struct tcphdr) + TCPOLEN_MSS + | |
2e6599cb ACM |
2044 | (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) + |
2045 | (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) + | |
1da177e4 | 2046 | /* SACK_PERM is in the place of NOP NOP of TS */ |
2e6599cb | 2047 | ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0)); |
1da177e4 LT |
2048 | skb->h.th = th = (struct tcphdr *) skb_push(skb, tcp_header_size); |
2049 | ||
2050 | memset(th, 0, sizeof(struct tcphdr)); | |
2051 | th->syn = 1; | |
2052 | th->ack = 1; | |
1da177e4 LT |
2053 | TCP_ECN_make_synack(req, th); |
2054 | th->source = inet_sk(sk)->sport; | |
2e6599cb ACM |
2055 | th->dest = ireq->rmt_port; |
2056 | TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn; | |
1da177e4 LT |
2057 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; |
2058 | TCP_SKB_CB(skb)->sacked = 0; | |
7967168c HX |
2059 | skb_shinfo(skb)->gso_segs = 1; |
2060 | skb_shinfo(skb)->gso_size = 0; | |
2061 | skb_shinfo(skb)->gso_type = 0; | |
1da177e4 | 2062 | th->seq = htonl(TCP_SKB_CB(skb)->seq); |
2e6599cb | 2063 | th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); |
1da177e4 LT |
2064 | if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ |
2065 | __u8 rcv_wscale; | |
2066 | /* Set this up on the first call only */ | |
2067 | req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); | |
2068 | /* tcp_full_space because it is guaranteed to be the first packet */ | |
2069 | tcp_select_initial_window(tcp_full_space(sk), | |
2e6599cb | 2070 | dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
1da177e4 LT |
2071 | &req->rcv_wnd, |
2072 | &req->window_clamp, | |
2e6599cb | 2073 | ireq->wscale_ok, |
1da177e4 | 2074 | &rcv_wscale); |
2e6599cb | 2075 | ireq->rcv_wscale = rcv_wscale; |
1da177e4 LT |
2076 | } |
2077 | ||
2078 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
2079 | th->window = htons(req->rcv_wnd); | |
2080 | ||
2081 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
df7a3b07 | 2082 | tcp_syn_build_options((__be32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok, |
2e6599cb | 2083 | ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale, |
1da177e4 LT |
2084 | TCP_SKB_CB(skb)->when, |
2085 | req->ts_recent); | |
2086 | ||
2087 | skb->csum = 0; | |
2088 | th->doff = (tcp_header_size >> 2); | |
2089 | TCP_INC_STATS(TCP_MIB_OUTSEGS); | |
2090 | return skb; | |
2091 | } | |
2092 | ||
2093 | /* | |
2094 | * Do all connect socket setups that can be done AF independent. | |
2095 | */ | |
40efc6fa | 2096 | static void tcp_connect_init(struct sock *sk) |
1da177e4 LT |
2097 | { |
2098 | struct dst_entry *dst = __sk_dst_get(sk); | |
2099 | struct tcp_sock *tp = tcp_sk(sk); | |
2100 | __u8 rcv_wscale; | |
2101 | ||
2102 | /* We'll fix this up when we get a response from the other end. | |
2103 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
2104 | */ | |
2105 | tp->tcp_header_len = sizeof(struct tcphdr) + | |
2106 | (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); | |
2107 | ||
2108 | /* If user gave his TCP_MAXSEG, record it to clamp */ | |
2109 | if (tp->rx_opt.user_mss) | |
2110 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
2111 | tp->max_window = 0; | |
5d424d5a | 2112 | tcp_mtup_init(sk); |
1da177e4 LT |
2113 | tcp_sync_mss(sk, dst_mtu(dst)); |
2114 | ||
2115 | if (!tp->window_clamp) | |
2116 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
2117 | tp->advmss = dst_metric(dst, RTAX_ADVMSS); | |
2118 | tcp_initialize_rcv_mss(sk); | |
1da177e4 LT |
2119 | |
2120 | tcp_select_initial_window(tcp_full_space(sk), | |
2121 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), | |
2122 | &tp->rcv_wnd, | |
2123 | &tp->window_clamp, | |
2124 | sysctl_tcp_window_scaling, | |
2125 | &rcv_wscale); | |
2126 | ||
2127 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
2128 | tp->rcv_ssthresh = tp->rcv_wnd; | |
2129 | ||
2130 | sk->sk_err = 0; | |
2131 | sock_reset_flag(sk, SOCK_DONE); | |
2132 | tp->snd_wnd = 0; | |
2133 | tcp_init_wl(tp, tp->write_seq, 0); | |
2134 | tp->snd_una = tp->write_seq; | |
2135 | tp->snd_sml = tp->write_seq; | |
2136 | tp->rcv_nxt = 0; | |
2137 | tp->rcv_wup = 0; | |
2138 | tp->copied_seq = 0; | |
2139 | ||
463c84b9 ACM |
2140 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
2141 | inet_csk(sk)->icsk_retransmits = 0; | |
1da177e4 LT |
2142 | tcp_clear_retrans(tp); |
2143 | } | |
2144 | ||
2145 | /* | |
2146 | * Build a SYN and send it off. | |
2147 | */ | |
2148 | int tcp_connect(struct sock *sk) | |
2149 | { | |
2150 | struct tcp_sock *tp = tcp_sk(sk); | |
2151 | struct sk_buff *buff; | |
2152 | ||
2153 | tcp_connect_init(sk); | |
2154 | ||
d179cd12 | 2155 | buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); |
1da177e4 LT |
2156 | if (unlikely(buff == NULL)) |
2157 | return -ENOBUFS; | |
2158 | ||
2159 | /* Reserve space for headers. */ | |
2160 | skb_reserve(buff, MAX_TCP_HEADER); | |
2161 | ||
2162 | TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN; | |
2163 | TCP_ECN_send_syn(sk, tp, buff); | |
2164 | TCP_SKB_CB(buff)->sacked = 0; | |
7967168c HX |
2165 | skb_shinfo(buff)->gso_segs = 1; |
2166 | skb_shinfo(buff)->gso_size = 0; | |
2167 | skb_shinfo(buff)->gso_type = 0; | |
1da177e4 | 2168 | buff->csum = 0; |
bd37a088 | 2169 | tp->snd_nxt = tp->write_seq; |
1da177e4 LT |
2170 | TCP_SKB_CB(buff)->seq = tp->write_seq++; |
2171 | TCP_SKB_CB(buff)->end_seq = tp->write_seq; | |
1da177e4 LT |
2172 | |
2173 | /* Send it off. */ | |
2174 | TCP_SKB_CB(buff)->when = tcp_time_stamp; | |
2175 | tp->retrans_stamp = TCP_SKB_CB(buff)->when; | |
2176 | skb_header_release(buff); | |
2177 | __skb_queue_tail(&sk->sk_write_queue, buff); | |
2178 | sk_charge_skb(sk, buff); | |
2179 | tp->packets_out += tcp_skb_pcount(buff); | |
dfb4b9dc | 2180 | tcp_transmit_skb(sk, buff, 1, GFP_KERNEL); |
bd37a088 WY |
2181 | |
2182 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
2183 | * in order to make this packet get counted in tcpOutSegs. | |
2184 | */ | |
2185 | tp->snd_nxt = tp->write_seq; | |
2186 | tp->pushed_seq = tp->write_seq; | |
1da177e4 LT |
2187 | TCP_INC_STATS(TCP_MIB_ACTIVEOPENS); |
2188 | ||
2189 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
2190 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
2191 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
2192 | return 0; |
2193 | } | |
2194 | ||
2195 | /* Send out a delayed ack, the caller does the policy checking | |
2196 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
2197 | * for details. | |
2198 | */ | |
2199 | void tcp_send_delayed_ack(struct sock *sk) | |
2200 | { | |
463c84b9 ACM |
2201 | struct inet_connection_sock *icsk = inet_csk(sk); |
2202 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
2203 | unsigned long timeout; |
2204 | ||
2205 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 2206 | const struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
2207 | int max_ato = HZ/2; |
2208 | ||
463c84b9 | 2209 | if (icsk->icsk_ack.pingpong || (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) |
1da177e4 LT |
2210 | max_ato = TCP_DELACK_MAX; |
2211 | ||
2212 | /* Slow path, intersegment interval is "high". */ | |
2213 | ||
2214 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 2215 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
2216 | * directly. |
2217 | */ | |
2218 | if (tp->srtt) { | |
2219 | int rtt = max(tp->srtt>>3, TCP_DELACK_MIN); | |
2220 | ||
2221 | if (rtt < max_ato) | |
2222 | max_ato = rtt; | |
2223 | } | |
2224 | ||
2225 | ato = min(ato, max_ato); | |
2226 | } | |
2227 | ||
2228 | /* Stay within the limit we were given */ | |
2229 | timeout = jiffies + ato; | |
2230 | ||
2231 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 2232 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
2233 | /* If delack timer was blocked or is about to expire, |
2234 | * send ACK now. | |
2235 | */ | |
463c84b9 ACM |
2236 | if (icsk->icsk_ack.blocked || |
2237 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
2238 | tcp_send_ack(sk); |
2239 | return; | |
2240 | } | |
2241 | ||
463c84b9 ACM |
2242 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
2243 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 2244 | } |
463c84b9 ACM |
2245 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
2246 | icsk->icsk_ack.timeout = timeout; | |
2247 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
2248 | } |
2249 | ||
2250 | /* This routine sends an ack and also updates the window. */ | |
2251 | void tcp_send_ack(struct sock *sk) | |
2252 | { | |
2253 | /* If we have been reset, we may not send again. */ | |
2254 | if (sk->sk_state != TCP_CLOSE) { | |
2255 | struct tcp_sock *tp = tcp_sk(sk); | |
2256 | struct sk_buff *buff; | |
2257 | ||
2258 | /* We are not putting this on the write queue, so | |
2259 | * tcp_transmit_skb() will set the ownership to this | |
2260 | * sock. | |
2261 | */ | |
2262 | buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); | |
2263 | if (buff == NULL) { | |
463c84b9 ACM |
2264 | inet_csk_schedule_ack(sk); |
2265 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3f421baa ACM |
2266 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, |
2267 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
1da177e4 LT |
2268 | return; |
2269 | } | |
2270 | ||
2271 | /* Reserve space for headers and prepare control bits. */ | |
2272 | skb_reserve(buff, MAX_TCP_HEADER); | |
2273 | buff->csum = 0; | |
2274 | TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK; | |
2275 | TCP_SKB_CB(buff)->sacked = 0; | |
7967168c HX |
2276 | skb_shinfo(buff)->gso_segs = 1; |
2277 | skb_shinfo(buff)->gso_size = 0; | |
2278 | skb_shinfo(buff)->gso_type = 0; | |
1da177e4 LT |
2279 | |
2280 | /* Send it off, this clears delayed acks for us. */ | |
2281 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk, tp); | |
2282 | TCP_SKB_CB(buff)->when = tcp_time_stamp; | |
dfb4b9dc | 2283 | tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC); |
1da177e4 LT |
2284 | } |
2285 | } | |
2286 | ||
2287 | /* This routine sends a packet with an out of date sequence | |
2288 | * number. It assumes the other end will try to ack it. | |
2289 | * | |
2290 | * Question: what should we make while urgent mode? | |
2291 | * 4.4BSD forces sending single byte of data. We cannot send | |
2292 | * out of window data, because we have SND.NXT==SND.MAX... | |
2293 | * | |
2294 | * Current solution: to send TWO zero-length segments in urgent mode: | |
2295 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
2296 | * out-of-date with SND.UNA-1 to probe window. | |
2297 | */ | |
2298 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent) | |
2299 | { | |
2300 | struct tcp_sock *tp = tcp_sk(sk); | |
2301 | struct sk_buff *skb; | |
2302 | ||
2303 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
2304 | skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); | |
2305 | if (skb == NULL) | |
2306 | return -1; | |
2307 | ||
2308 | /* Reserve space for headers and set control bits. */ | |
2309 | skb_reserve(skb, MAX_TCP_HEADER); | |
2310 | skb->csum = 0; | |
2311 | TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK; | |
2312 | TCP_SKB_CB(skb)->sacked = urgent; | |
7967168c HX |
2313 | skb_shinfo(skb)->gso_segs = 1; |
2314 | skb_shinfo(skb)->gso_size = 0; | |
2315 | skb_shinfo(skb)->gso_type = 0; | |
1da177e4 LT |
2316 | |
2317 | /* Use a previous sequence. This should cause the other | |
2318 | * end to send an ack. Don't queue or clone SKB, just | |
2319 | * send it. | |
2320 | */ | |
2321 | TCP_SKB_CB(skb)->seq = urgent ? tp->snd_una : tp->snd_una - 1; | |
2322 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; | |
2323 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2324 | return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); |
1da177e4 LT |
2325 | } |
2326 | ||
2327 | int tcp_write_wakeup(struct sock *sk) | |
2328 | { | |
2329 | if (sk->sk_state != TCP_CLOSE) { | |
2330 | struct tcp_sock *tp = tcp_sk(sk); | |
2331 | struct sk_buff *skb; | |
2332 | ||
2333 | if ((skb = sk->sk_send_head) != NULL && | |
2334 | before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd)) { | |
2335 | int err; | |
2336 | unsigned int mss = tcp_current_mss(sk, 0); | |
2337 | unsigned int seg_size = tp->snd_una+tp->snd_wnd-TCP_SKB_CB(skb)->seq; | |
2338 | ||
2339 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
2340 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
2341 | ||
2342 | /* We are probing the opening of a window | |
2343 | * but the window size is != 0 | |
2344 | * must have been a result SWS avoidance ( sender ) | |
2345 | */ | |
2346 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
2347 | skb->len > mss) { | |
2348 | seg_size = min(seg_size, mss); | |
2349 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; | |
846998ae | 2350 | if (tcp_fragment(sk, skb, seg_size, mss)) |
1da177e4 | 2351 | return -1; |
1da177e4 | 2352 | } else if (!tcp_skb_pcount(skb)) |
846998ae | 2353 | tcp_set_skb_tso_segs(sk, skb, mss); |
1da177e4 LT |
2354 | |
2355 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; | |
2356 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2357 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2358 | if (!err) { |
2359 | update_send_head(sk, tp, skb); | |
2360 | } | |
2361 | return err; | |
2362 | } else { | |
2363 | if (tp->urg_mode && | |
2364 | between(tp->snd_up, tp->snd_una+1, tp->snd_una+0xFFFF)) | |
2365 | tcp_xmit_probe_skb(sk, TCPCB_URG); | |
2366 | return tcp_xmit_probe_skb(sk, 0); | |
2367 | } | |
2368 | } | |
2369 | return -1; | |
2370 | } | |
2371 | ||
2372 | /* A window probe timeout has occurred. If window is not closed send | |
2373 | * a partial packet else a zero probe. | |
2374 | */ | |
2375 | void tcp_send_probe0(struct sock *sk) | |
2376 | { | |
463c84b9 | 2377 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2378 | struct tcp_sock *tp = tcp_sk(sk); |
2379 | int err; | |
2380 | ||
2381 | err = tcp_write_wakeup(sk); | |
2382 | ||
2383 | if (tp->packets_out || !sk->sk_send_head) { | |
2384 | /* Cancel probe timer, if it is not required. */ | |
6687e988 | 2385 | icsk->icsk_probes_out = 0; |
463c84b9 | 2386 | icsk->icsk_backoff = 0; |
1da177e4 LT |
2387 | return; |
2388 | } | |
2389 | ||
2390 | if (err <= 0) { | |
463c84b9 ACM |
2391 | if (icsk->icsk_backoff < sysctl_tcp_retries2) |
2392 | icsk->icsk_backoff++; | |
6687e988 | 2393 | icsk->icsk_probes_out++; |
463c84b9 | 2394 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
3f421baa ACM |
2395 | min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), |
2396 | TCP_RTO_MAX); | |
1da177e4 LT |
2397 | } else { |
2398 | /* If packet was not sent due to local congestion, | |
6687e988 | 2399 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
2400 | * Let local senders to fight for local resources. |
2401 | * | |
2402 | * Use accumulated backoff yet. | |
2403 | */ | |
6687e988 ACM |
2404 | if (!icsk->icsk_probes_out) |
2405 | icsk->icsk_probes_out = 1; | |
463c84b9 ACM |
2406 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
2407 | min(icsk->icsk_rto << icsk->icsk_backoff, | |
3f421baa ACM |
2408 | TCP_RESOURCE_PROBE_INTERVAL), |
2409 | TCP_RTO_MAX); | |
1da177e4 LT |
2410 | } |
2411 | } | |
2412 | ||
2413 | EXPORT_SYMBOL(tcp_connect); | |
2414 | EXPORT_SYMBOL(tcp_make_synack); | |
2415 | EXPORT_SYMBOL(tcp_simple_retransmit); | |
2416 | EXPORT_SYMBOL(tcp_sync_mss); | |
f4805ede | 2417 | EXPORT_SYMBOL(sysctl_tcp_tso_win_divisor); |
5d424d5a | 2418 | EXPORT_SYMBOL(tcp_mtup_init); |