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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 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
12 | * Florian La Roche, <flla@stud.uni-sb.de> | |
13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
16 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
18 | * Jorge Cwik, <jorge@laser.satlink.net> | |
19 | */ | |
20 | ||
21 | /* | |
22 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
23 | * : Fragmentation on mtu decrease | |
24 | * : Segment collapse on retransmit | |
25 | * : AF independence | |
26 | * | |
27 | * Linus Torvalds : send_delayed_ack | |
28 | * David S. Miller : Charge memory using the right skb | |
29 | * during syn/ack processing. | |
30 | * David S. Miller : Output engine completely rewritten. | |
31 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
32 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
33 | * J Hadi Salim : ECN support | |
34 | * | |
35 | */ | |
36 | ||
91df42be JP |
37 | #define pr_fmt(fmt) "TCP: " fmt |
38 | ||
1da177e4 LT |
39 | #include <net/tcp.h> |
40 | ||
41 | #include <linux/compiler.h> | |
5a0e3ad6 | 42 | #include <linux/gfp.h> |
1da177e4 | 43 | #include <linux/module.h> |
1da177e4 LT |
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 | |
09cb105e | 48 | /* People can turn this on to work with those rare, broken TCPs that |
15d99e02 RJ |
49 | * interpret the window field as a signed quantity. |
50 | */ | |
ab32ea5d | 51 | int sysctl_tcp_workaround_signed_windows __read_mostly = 0; |
15d99e02 | 52 | |
46d3ceab ED |
53 | /* Default TSQ limit of two TSO segments */ |
54 | int sysctl_tcp_limit_output_bytes __read_mostly = 131072; | |
55 | ||
1da177e4 LT |
56 | /* This limits the percentage of the congestion window which we |
57 | * will allow a single TSO frame to consume. Building TSO frames | |
58 | * which are too large can cause TCP streams to be bursty. | |
59 | */ | |
ab32ea5d | 60 | int sysctl_tcp_tso_win_divisor __read_mostly = 3; |
1da177e4 | 61 | |
ab32ea5d | 62 | int sysctl_tcp_mtu_probing __read_mostly = 0; |
97b1ce25 | 63 | int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS; |
5d424d5a | 64 | |
35089bb2 | 65 | /* By default, RFC2861 behavior. */ |
ab32ea5d | 66 | int sysctl_tcp_slow_start_after_idle __read_mostly = 1; |
35089bb2 | 67 | |
c9bee3b7 ED |
68 | unsigned int sysctl_tcp_notsent_lowat __read_mostly = UINT_MAX; |
69 | EXPORT_SYMBOL(sysctl_tcp_notsent_lowat); | |
70 | ||
46d3ceab ED |
71 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
72 | int push_one, gfp_t gfp); | |
519855c5 | 73 | |
67edfef7 | 74 | /* Account for new data that has been sent to the network. */ |
cf533ea5 | 75 | static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) |
1da177e4 | 76 | { |
6ba8a3b1 | 77 | struct inet_connection_sock *icsk = inet_csk(sk); |
9e412ba7 | 78 | struct tcp_sock *tp = tcp_sk(sk); |
66f5fe62 | 79 | unsigned int prior_packets = tp->packets_out; |
9e412ba7 | 80 | |
fe067e8a | 81 | tcp_advance_send_head(sk, skb); |
1da177e4 | 82 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; |
8512430e | 83 | |
66f5fe62 | 84 | tp->packets_out += tcp_skb_pcount(skb); |
6ba8a3b1 | 85 | if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || |
6a5dc9e5 | 86 | icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { |
750ea2ba | 87 | tcp_rearm_rto(sk); |
6a5dc9e5 | 88 | } |
1da177e4 LT |
89 | } |
90 | ||
91 | /* SND.NXT, if window was not shrunk. | |
92 | * If window has been shrunk, what should we make? It is not clear at all. | |
93 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
94 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
95 | * invalid. OK, let's make this for now: | |
96 | */ | |
cf533ea5 | 97 | static inline __u32 tcp_acceptable_seq(const struct sock *sk) |
1da177e4 | 98 | { |
cf533ea5 | 99 | const struct tcp_sock *tp = tcp_sk(sk); |
9e412ba7 | 100 | |
90840def | 101 | if (!before(tcp_wnd_end(tp), tp->snd_nxt)) |
1da177e4 LT |
102 | return tp->snd_nxt; |
103 | else | |
90840def | 104 | return tcp_wnd_end(tp); |
1da177e4 LT |
105 | } |
106 | ||
107 | /* Calculate mss to advertise in SYN segment. | |
108 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
109 | * | |
110 | * 1. It is independent of path mtu. | |
111 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
112 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
113 | * attached devices, because some buggy hosts are confused by | |
114 | * large MSS. | |
115 | * 4. We do not make 3, we advertise MSS, calculated from first | |
116 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
117 | * This may be overridden via information stored in routing table. | |
118 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
119 | * probably even Jumbo". | |
120 | */ | |
121 | static __u16 tcp_advertise_mss(struct sock *sk) | |
122 | { | |
123 | struct tcp_sock *tp = tcp_sk(sk); | |
cf533ea5 | 124 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
125 | int mss = tp->advmss; |
126 | ||
0dbaee3b DM |
127 | if (dst) { |
128 | unsigned int metric = dst_metric_advmss(dst); | |
129 | ||
130 | if (metric < mss) { | |
131 | mss = metric; | |
132 | tp->advmss = mss; | |
133 | } | |
1da177e4 LT |
134 | } |
135 | ||
136 | return (__u16)mss; | |
137 | } | |
138 | ||
139 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
140 | * This is the first part of cwnd validation mechanism. */ | |
cf533ea5 | 141 | static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst) |
1da177e4 | 142 | { |
463c84b9 | 143 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
144 | s32 delta = tcp_time_stamp - tp->lsndtime; |
145 | u32 restart_cwnd = tcp_init_cwnd(tp, dst); | |
146 | u32 cwnd = tp->snd_cwnd; | |
147 | ||
6687e988 | 148 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 149 | |
6687e988 | 150 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
151 | restart_cwnd = min(restart_cwnd, cwnd); |
152 | ||
463c84b9 | 153 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
154 | cwnd >>= 1; |
155 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
156 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
157 | tp->snd_cwnd_used = 0; | |
158 | } | |
159 | ||
67edfef7 | 160 | /* Congestion state accounting after a packet has been sent. */ |
40efc6fa | 161 | static void tcp_event_data_sent(struct tcp_sock *tp, |
cf533ea5 | 162 | struct sock *sk) |
1da177e4 | 163 | { |
463c84b9 ACM |
164 | struct inet_connection_sock *icsk = inet_csk(sk); |
165 | const u32 now = tcp_time_stamp; | |
bcefe17c | 166 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 | 167 | |
35089bb2 DM |
168 | if (sysctl_tcp_slow_start_after_idle && |
169 | (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) | |
463c84b9 | 170 | tcp_cwnd_restart(sk, __sk_dst_get(sk)); |
1da177e4 LT |
171 | |
172 | tp->lsndtime = now; | |
173 | ||
174 | /* If it is a reply for ato after last received | |
175 | * packet, enter pingpong mode. | |
176 | */ | |
bcefe17c CW |
177 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato && |
178 | (!dst || !dst_metric(dst, RTAX_QUICKACK))) | |
179 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
180 | } |
181 | ||
67edfef7 | 182 | /* Account for an ACK we sent. */ |
40efc6fa | 183 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 184 | { |
463c84b9 ACM |
185 | tcp_dec_quickack_mode(sk, pkts); |
186 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
187 | } |
188 | ||
85f16525 YC |
189 | |
190 | u32 tcp_default_init_rwnd(u32 mss) | |
191 | { | |
192 | /* Initial receive window should be twice of TCP_INIT_CWND to | |
9ef71e0c | 193 | * enable proper sending of new unsent data during fast recovery |
85f16525 YC |
194 | * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a |
195 | * limit when mss is larger than 1460. | |
196 | */ | |
197 | u32 init_rwnd = TCP_INIT_CWND * 2; | |
198 | ||
199 | if (mss > 1460) | |
200 | init_rwnd = max((1460 * init_rwnd) / mss, 2U); | |
201 | return init_rwnd; | |
202 | } | |
203 | ||
1da177e4 LT |
204 | /* Determine a window scaling and initial window to offer. |
205 | * Based on the assumption that the given amount of space | |
206 | * will be offered. Store the results in the tp structure. | |
207 | * NOTE: for smooth operation initial space offering should | |
208 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
209 | * This MUST be enforced by all callers. | |
210 | */ | |
211 | void tcp_select_initial_window(int __space, __u32 mss, | |
212 | __u32 *rcv_wnd, __u32 *window_clamp, | |
31d12926 | 213 | int wscale_ok, __u8 *rcv_wscale, |
214 | __u32 init_rcv_wnd) | |
1da177e4 LT |
215 | { |
216 | unsigned int space = (__space < 0 ? 0 : __space); | |
217 | ||
218 | /* If no clamp set the clamp to the max possible scaled window */ | |
219 | if (*window_clamp == 0) | |
220 | (*window_clamp) = (65535 << 14); | |
221 | space = min(*window_clamp, space); | |
222 | ||
223 | /* Quantize space offering to a multiple of mss if possible. */ | |
224 | if (space > mss) | |
225 | space = (space / mss) * mss; | |
226 | ||
227 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
228 | * will break some buggy TCP stacks. If the admin tells us |
229 | * it is likely we could be speaking with such a buggy stack | |
230 | * we will truncate our initial window offering to 32K-1 | |
231 | * unless the remote has sent us a window scaling option, | |
232 | * which we interpret as a sign the remote TCP is not | |
233 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 234 | */ |
15d99e02 RJ |
235 | if (sysctl_tcp_workaround_signed_windows) |
236 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
237 | else | |
238 | (*rcv_wnd) = space; | |
239 | ||
1da177e4 LT |
240 | (*rcv_wscale) = 0; |
241 | if (wscale_ok) { | |
242 | /* Set window scaling on max possible window | |
e905a9ed | 243 | * See RFC1323 for an explanation of the limit to 14 |
1da177e4 LT |
244 | */ |
245 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
316c1592 | 246 | space = min_t(u32, space, *window_clamp); |
1da177e4 LT |
247 | while (space > 65535 && (*rcv_wscale) < 14) { |
248 | space >>= 1; | |
249 | (*rcv_wscale)++; | |
250 | } | |
251 | } | |
252 | ||
056834d9 | 253 | if (mss > (1 << *rcv_wscale)) { |
85f16525 YC |
254 | if (!init_rcv_wnd) /* Use default unless specified otherwise */ |
255 | init_rcv_wnd = tcp_default_init_rwnd(mss); | |
256 | *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); | |
1da177e4 LT |
257 | } |
258 | ||
259 | /* Set the clamp no higher than max representable value */ | |
260 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
261 | } | |
4bc2f18b | 262 | EXPORT_SYMBOL(tcp_select_initial_window); |
1da177e4 LT |
263 | |
264 | /* Chose a new window to advertise, update state in tcp_sock for the | |
265 | * socket, and return result with RFC1323 scaling applied. The return | |
266 | * value can be stuffed directly into th->window for an outgoing | |
267 | * frame. | |
268 | */ | |
40efc6fa | 269 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
270 | { |
271 | struct tcp_sock *tp = tcp_sk(sk); | |
272 | u32 cur_win = tcp_receive_window(tp); | |
273 | u32 new_win = __tcp_select_window(sk); | |
274 | ||
275 | /* Never shrink the offered window */ | |
2de979bd | 276 | if (new_win < cur_win) { |
1da177e4 LT |
277 | /* Danger Will Robinson! |
278 | * Don't update rcv_wup/rcv_wnd here or else | |
279 | * we will not be able to advertise a zero | |
280 | * window in time. --DaveM | |
281 | * | |
282 | * Relax Will Robinson. | |
283 | */ | |
607bfbf2 | 284 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
285 | } |
286 | tp->rcv_wnd = new_win; | |
287 | tp->rcv_wup = tp->rcv_nxt; | |
288 | ||
289 | /* Make sure we do not exceed the maximum possible | |
290 | * scaled window. | |
291 | */ | |
15d99e02 | 292 | if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) |
1da177e4 LT |
293 | new_win = min(new_win, MAX_TCP_WINDOW); |
294 | else | |
295 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
296 | ||
297 | /* RFC1323 scaling applied */ | |
298 | new_win >>= tp->rx_opt.rcv_wscale; | |
299 | ||
300 | /* If we advertise zero window, disable fast path. */ | |
301 | if (new_win == 0) | |
302 | tp->pred_flags = 0; | |
303 | ||
304 | return new_win; | |
305 | } | |
306 | ||
67edfef7 | 307 | /* Packet ECN state for a SYN-ACK */ |
cf533ea5 | 308 | static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb) |
bdf1ee5d | 309 | { |
4de075e0 | 310 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
056834d9 | 311 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
4de075e0 | 312 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
bdf1ee5d IJ |
313 | } |
314 | ||
67edfef7 | 315 | /* Packet ECN state for a SYN. */ |
bdf1ee5d IJ |
316 | static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) |
317 | { | |
318 | struct tcp_sock *tp = tcp_sk(sk); | |
319 | ||
320 | tp->ecn_flags = 0; | |
5d134f1c | 321 | if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1) { |
4de075e0 | 322 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
bdf1ee5d IJ |
323 | tp->ecn_flags = TCP_ECN_OK; |
324 | } | |
325 | } | |
326 | ||
327 | static __inline__ void | |
cf533ea5 | 328 | TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th) |
bdf1ee5d IJ |
329 | { |
330 | if (inet_rsk(req)->ecn_ok) | |
331 | th->ece = 1; | |
332 | } | |
333 | ||
67edfef7 AK |
334 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
335 | * be sent. | |
336 | */ | |
bdf1ee5d IJ |
337 | static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, |
338 | int tcp_header_len) | |
339 | { | |
340 | struct tcp_sock *tp = tcp_sk(sk); | |
341 | ||
342 | if (tp->ecn_flags & TCP_ECN_OK) { | |
343 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
344 | if (skb->len != tcp_header_len && | |
345 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
346 | INET_ECN_xmit(sk); | |
056834d9 | 347 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d IJ |
348 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
349 | tcp_hdr(skb)->cwr = 1; | |
350 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; | |
351 | } | |
352 | } else { | |
353 | /* ACK or retransmitted segment: clear ECT|CE */ | |
354 | INET_ECN_dontxmit(sk); | |
355 | } | |
356 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
357 | tcp_hdr(skb)->ece = 1; | |
358 | } | |
359 | } | |
360 | ||
e870a8ef IJ |
361 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
362 | * auto increment end seqno. | |
363 | */ | |
364 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
365 | { | |
7b7fc97a ED |
366 | struct skb_shared_info *shinfo = skb_shinfo(skb); |
367 | ||
2e8e18ef | 368 | skb->ip_summed = CHECKSUM_PARTIAL; |
e870a8ef IJ |
369 | skb->csum = 0; |
370 | ||
4de075e0 | 371 | TCP_SKB_CB(skb)->tcp_flags = flags; |
e870a8ef IJ |
372 | TCP_SKB_CB(skb)->sacked = 0; |
373 | ||
7b7fc97a ED |
374 | shinfo->gso_segs = 1; |
375 | shinfo->gso_size = 0; | |
376 | shinfo->gso_type = 0; | |
e870a8ef IJ |
377 | |
378 | TCP_SKB_CB(skb)->seq = seq; | |
a3433f35 | 379 | if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
e870a8ef IJ |
380 | seq++; |
381 | TCP_SKB_CB(skb)->end_seq = seq; | |
382 | } | |
383 | ||
a2a385d6 | 384 | static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
33f5f57e IJ |
385 | { |
386 | return tp->snd_una != tp->snd_up; | |
387 | } | |
388 | ||
33ad798c AL |
389 | #define OPTION_SACK_ADVERTISE (1 << 0) |
390 | #define OPTION_TS (1 << 1) | |
391 | #define OPTION_MD5 (1 << 2) | |
89e95a61 | 392 | #define OPTION_WSCALE (1 << 3) |
2100c8d2 | 393 | #define OPTION_FAST_OPEN_COOKIE (1 << 8) |
33ad798c AL |
394 | |
395 | struct tcp_out_options { | |
2100c8d2 YC |
396 | u16 options; /* bit field of OPTION_* */ |
397 | u16 mss; /* 0 to disable */ | |
33ad798c AL |
398 | u8 ws; /* window scale, 0 to disable */ |
399 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 400 | u8 hash_size; /* bytes in hash_location */ |
bd0388ae | 401 | __u8 *hash_location; /* temporary pointer, overloaded */ |
2100c8d2 YC |
402 | __u32 tsval, tsecr; /* need to include OPTION_TS */ |
403 | struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ | |
33ad798c AL |
404 | }; |
405 | ||
67edfef7 AK |
406 | /* Write previously computed TCP options to the packet. |
407 | * | |
408 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
409 | * TCP options, we learned this through the hard way, so be careful here. |
410 | * Luckily we can at least blame others for their non-compliance but from | |
8e3bff96 | 411 | * inter-operability perspective it seems that we're somewhat stuck with |
fd6149d3 IJ |
412 | * the ordering which we have been using if we want to keep working with |
413 | * those broken things (not that it currently hurts anybody as there isn't | |
414 | * particular reason why the ordering would need to be changed). | |
415 | * | |
416 | * At least SACK_PERM as the first option is known to lead to a disaster | |
417 | * (but it may well be that other scenarios fail similarly). | |
418 | */ | |
33ad798c | 419 | static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
bd0388ae WAS |
420 | struct tcp_out_options *opts) |
421 | { | |
2100c8d2 | 422 | u16 options = opts->options; /* mungable copy */ |
bd0388ae | 423 | |
bd0388ae | 424 | if (unlikely(OPTION_MD5 & options)) { |
1a2c6181 CP |
425 | *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
426 | (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); | |
bd0388ae WAS |
427 | /* overload cookie hash location */ |
428 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 429 | ptr += 4; |
40efc6fa | 430 | } |
33ad798c | 431 | |
fd6149d3 IJ |
432 | if (unlikely(opts->mss)) { |
433 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
434 | (TCPOLEN_MSS << 16) | | |
435 | opts->mss); | |
436 | } | |
437 | ||
bd0388ae WAS |
438 | if (likely(OPTION_TS & options)) { |
439 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
440 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
441 | (TCPOLEN_SACK_PERM << 16) | | |
442 | (TCPOPT_TIMESTAMP << 8) | | |
443 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 444 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
445 | } else { |
446 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
447 | (TCPOPT_NOP << 16) | | |
448 | (TCPOPT_TIMESTAMP << 8) | | |
449 | TCPOLEN_TIMESTAMP); | |
450 | } | |
451 | *ptr++ = htonl(opts->tsval); | |
452 | *ptr++ = htonl(opts->tsecr); | |
453 | } | |
454 | ||
bd0388ae | 455 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
33ad798c AL |
456 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
457 | (TCPOPT_NOP << 16) | | |
458 | (TCPOPT_SACK_PERM << 8) | | |
459 | TCPOLEN_SACK_PERM); | |
460 | } | |
461 | ||
bd0388ae | 462 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
463 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
464 | (TCPOPT_WINDOW << 16) | | |
465 | (TCPOLEN_WINDOW << 8) | | |
466 | opts->ws); | |
467 | } | |
468 | ||
469 | if (unlikely(opts->num_sack_blocks)) { | |
470 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
471 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
472 | int this_sack; |
473 | ||
474 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
475 | (TCPOPT_NOP << 16) | | |
476 | (TCPOPT_SACK << 8) | | |
33ad798c | 477 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 478 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 479 | |
33ad798c AL |
480 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
481 | ++this_sack) { | |
40efc6fa SH |
482 | *ptr++ = htonl(sp[this_sack].start_seq); |
483 | *ptr++ = htonl(sp[this_sack].end_seq); | |
484 | } | |
2de979bd | 485 | |
5861f8e5 | 486 | tp->rx_opt.dsack = 0; |
40efc6fa | 487 | } |
2100c8d2 YC |
488 | |
489 | if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { | |
490 | struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; | |
491 | ||
492 | *ptr++ = htonl((TCPOPT_EXP << 24) | | |
493 | ((TCPOLEN_EXP_FASTOPEN_BASE + foc->len) << 16) | | |
494 | TCPOPT_FASTOPEN_MAGIC); | |
495 | ||
496 | memcpy(ptr, foc->val, foc->len); | |
497 | if ((foc->len & 3) == 2) { | |
498 | u8 *align = ((u8 *)ptr) + foc->len; | |
499 | align[0] = align[1] = TCPOPT_NOP; | |
500 | } | |
501 | ptr += (foc->len + 3) >> 2; | |
502 | } | |
33ad798c AL |
503 | } |
504 | ||
67edfef7 AK |
505 | /* Compute TCP options for SYN packets. This is not the final |
506 | * network wire format yet. | |
507 | */ | |
95c96174 | 508 | static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 509 | struct tcp_out_options *opts, |
cf533ea5 ED |
510 | struct tcp_md5sig_key **md5) |
511 | { | |
33ad798c | 512 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 513 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
783237e8 | 514 | struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
33ad798c | 515 | |
cfb6eeb4 | 516 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
517 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
518 | if (*md5) { | |
519 | opts->options |= OPTION_MD5; | |
bd0388ae | 520 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
cfb6eeb4 | 521 | } |
33ad798c AL |
522 | #else |
523 | *md5 = NULL; | |
cfb6eeb4 | 524 | #endif |
33ad798c AL |
525 | |
526 | /* We always get an MSS option. The option bytes which will be seen in | |
527 | * normal data packets should timestamps be used, must be in the MSS | |
528 | * advertised. But we subtract them from tp->mss_cache so that | |
529 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
530 | * fact here if necessary. If we don't do this correctly, as a | |
531 | * receiver we won't recognize data packets as being full sized when we | |
532 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
533 | * SACKs don't matter, we never delay an ACK when we have any of those | |
534 | * going out. */ | |
535 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 536 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 537 | |
bb5b7c11 | 538 | if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { |
33ad798c | 539 | opts->options |= OPTION_TS; |
ee684b6f | 540 | opts->tsval = TCP_SKB_CB(skb)->when + tp->tsoffset; |
33ad798c | 541 | opts->tsecr = tp->rx_opt.ts_recent; |
bd0388ae | 542 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 543 | } |
bb5b7c11 | 544 | if (likely(sysctl_tcp_window_scaling)) { |
33ad798c | 545 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 546 | opts->options |= OPTION_WSCALE; |
bd0388ae | 547 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 548 | } |
bb5b7c11 | 549 | if (likely(sysctl_tcp_sack)) { |
33ad798c | 550 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 551 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 552 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
553 | } |
554 | ||
783237e8 YC |
555 | if (fastopen && fastopen->cookie.len >= 0) { |
556 | u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len; | |
557 | need = (need + 3) & ~3U; /* Align to 32 bits */ | |
558 | if (remaining >= need) { | |
559 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
560 | opts->fastopen_cookie = &fastopen->cookie; | |
561 | remaining -= need; | |
562 | tp->syn_fastopen = 1; | |
563 | } | |
564 | } | |
bd0388ae | 565 | |
bd0388ae | 566 | return MAX_TCP_OPTION_SPACE - remaining; |
40efc6fa SH |
567 | } |
568 | ||
67edfef7 | 569 | /* Set up TCP options for SYN-ACKs. */ |
95c96174 | 570 | static unsigned int tcp_synack_options(struct sock *sk, |
33ad798c | 571 | struct request_sock *req, |
95c96174 | 572 | unsigned int mss, struct sk_buff *skb, |
33ad798c | 573 | struct tcp_out_options *opts, |
4957faad | 574 | struct tcp_md5sig_key **md5, |
8336886f | 575 | struct tcp_fastopen_cookie *foc) |
4957faad | 576 | { |
33ad798c | 577 | struct inet_request_sock *ireq = inet_rsk(req); |
95c96174 | 578 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
33ad798c | 579 | |
cfb6eeb4 | 580 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
581 | *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); |
582 | if (*md5) { | |
583 | opts->options |= OPTION_MD5; | |
4957faad WAS |
584 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
585 | ||
586 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
587 | * options. There was discussion about disabling SACK | |
588 | * rather than TS in order to fit in better with old, | |
589 | * buggy kernels, but that was deemed to be unnecessary. | |
590 | */ | |
de213e5e | 591 | ireq->tstamp_ok &= !ireq->sack_ok; |
cfb6eeb4 | 592 | } |
33ad798c AL |
593 | #else |
594 | *md5 = NULL; | |
cfb6eeb4 | 595 | #endif |
33ad798c | 596 | |
4957faad | 597 | /* We always send an MSS option. */ |
33ad798c | 598 | opts->mss = mss; |
4957faad | 599 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
600 | |
601 | if (likely(ireq->wscale_ok)) { | |
602 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 603 | opts->options |= OPTION_WSCALE; |
4957faad | 604 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 605 | } |
de213e5e | 606 | if (likely(ireq->tstamp_ok)) { |
33ad798c AL |
607 | opts->options |= OPTION_TS; |
608 | opts->tsval = TCP_SKB_CB(skb)->when; | |
609 | opts->tsecr = req->ts_recent; | |
4957faad | 610 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
611 | } |
612 | if (likely(ireq->sack_ok)) { | |
613 | opts->options |= OPTION_SACK_ADVERTISE; | |
de213e5e | 614 | if (unlikely(!ireq->tstamp_ok)) |
4957faad | 615 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c | 616 | } |
8336886f JC |
617 | if (foc != NULL) { |
618 | u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; | |
619 | need = (need + 3) & ~3U; /* Align to 32 bits */ | |
620 | if (remaining >= need) { | |
621 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
622 | opts->fastopen_cookie = foc; | |
623 | remaining -= need; | |
624 | } | |
625 | } | |
1a2c6181 | 626 | |
4957faad | 627 | return MAX_TCP_OPTION_SPACE - remaining; |
33ad798c AL |
628 | } |
629 | ||
67edfef7 AK |
630 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
631 | * final wire format yet. | |
632 | */ | |
95c96174 | 633 | static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 634 | struct tcp_out_options *opts, |
cf533ea5 ED |
635 | struct tcp_md5sig_key **md5) |
636 | { | |
33ad798c AL |
637 | struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; |
638 | struct tcp_sock *tp = tcp_sk(sk); | |
95c96174 | 639 | unsigned int size = 0; |
cabeccbd | 640 | unsigned int eff_sacks; |
33ad798c | 641 | |
5843ef42 AK |
642 | opts->options = 0; |
643 | ||
33ad798c AL |
644 | #ifdef CONFIG_TCP_MD5SIG |
645 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
646 | if (unlikely(*md5)) { | |
647 | opts->options |= OPTION_MD5; | |
648 | size += TCPOLEN_MD5SIG_ALIGNED; | |
649 | } | |
650 | #else | |
651 | *md5 = NULL; | |
652 | #endif | |
653 | ||
654 | if (likely(tp->rx_opt.tstamp_ok)) { | |
655 | opts->options |= OPTION_TS; | |
ee684b6f | 656 | opts->tsval = tcb ? tcb->when + tp->tsoffset : 0; |
33ad798c AL |
657 | opts->tsecr = tp->rx_opt.ts_recent; |
658 | size += TCPOLEN_TSTAMP_ALIGNED; | |
659 | } | |
660 | ||
cabeccbd IJ |
661 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
662 | if (unlikely(eff_sacks)) { | |
95c96174 | 663 | const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
33ad798c | 664 | opts->num_sack_blocks = |
95c96174 | 665 | min_t(unsigned int, eff_sacks, |
33ad798c AL |
666 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
667 | TCPOLEN_SACK_PERBLOCK); | |
668 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
669 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
670 | } | |
671 | ||
672 | return size; | |
40efc6fa | 673 | } |
1da177e4 | 674 | |
46d3ceab ED |
675 | |
676 | /* TCP SMALL QUEUES (TSQ) | |
677 | * | |
678 | * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) | |
679 | * to reduce RTT and bufferbloat. | |
680 | * We do this using a special skb destructor (tcp_wfree). | |
681 | * | |
682 | * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb | |
683 | * needs to be reallocated in a driver. | |
8e3bff96 | 684 | * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
46d3ceab ED |
685 | * |
686 | * Since transmit from skb destructor is forbidden, we use a tasklet | |
687 | * to process all sockets that eventually need to send more skbs. | |
688 | * We use one tasklet per cpu, with its own queue of sockets. | |
689 | */ | |
690 | struct tsq_tasklet { | |
691 | struct tasklet_struct tasklet; | |
692 | struct list_head head; /* queue of tcp sockets */ | |
693 | }; | |
694 | static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); | |
695 | ||
6f458dfb ED |
696 | static void tcp_tsq_handler(struct sock *sk) |
697 | { | |
698 | if ((1 << sk->sk_state) & | |
699 | (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | | |
700 | TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) | |
bf06200e JO |
701 | tcp_write_xmit(sk, tcp_current_mss(sk), tcp_sk(sk)->nonagle, |
702 | 0, GFP_ATOMIC); | |
6f458dfb | 703 | } |
46d3ceab | 704 | /* |
8e3bff96 | 705 | * One tasklet per cpu tries to send more skbs. |
46d3ceab | 706 | * We run in tasklet context but need to disable irqs when |
8e3bff96 | 707 | * transferring tsq->head because tcp_wfree() might |
46d3ceab ED |
708 | * interrupt us (non NAPI drivers) |
709 | */ | |
710 | static void tcp_tasklet_func(unsigned long data) | |
711 | { | |
712 | struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; | |
713 | LIST_HEAD(list); | |
714 | unsigned long flags; | |
715 | struct list_head *q, *n; | |
716 | struct tcp_sock *tp; | |
717 | struct sock *sk; | |
718 | ||
719 | local_irq_save(flags); | |
720 | list_splice_init(&tsq->head, &list); | |
721 | local_irq_restore(flags); | |
722 | ||
723 | list_for_each_safe(q, n, &list) { | |
724 | tp = list_entry(q, struct tcp_sock, tsq_node); | |
725 | list_del(&tp->tsq_node); | |
726 | ||
727 | sk = (struct sock *)tp; | |
728 | bh_lock_sock(sk); | |
729 | ||
730 | if (!sock_owned_by_user(sk)) { | |
6f458dfb | 731 | tcp_tsq_handler(sk); |
46d3ceab ED |
732 | } else { |
733 | /* defer the work to tcp_release_cb() */ | |
6f458dfb | 734 | set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); |
46d3ceab ED |
735 | } |
736 | bh_unlock_sock(sk); | |
737 | ||
738 | clear_bit(TSQ_QUEUED, &tp->tsq_flags); | |
739 | sk_free(sk); | |
740 | } | |
741 | } | |
742 | ||
6f458dfb ED |
743 | #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ |
744 | (1UL << TCP_WRITE_TIMER_DEFERRED) | \ | |
563d34d0 ED |
745 | (1UL << TCP_DELACK_TIMER_DEFERRED) | \ |
746 | (1UL << TCP_MTU_REDUCED_DEFERRED)) | |
46d3ceab ED |
747 | /** |
748 | * tcp_release_cb - tcp release_sock() callback | |
749 | * @sk: socket | |
750 | * | |
751 | * called from release_sock() to perform protocol dependent | |
752 | * actions before socket release. | |
753 | */ | |
754 | void tcp_release_cb(struct sock *sk) | |
755 | { | |
756 | struct tcp_sock *tp = tcp_sk(sk); | |
6f458dfb | 757 | unsigned long flags, nflags; |
46d3ceab | 758 | |
6f458dfb ED |
759 | /* perform an atomic operation only if at least one flag is set */ |
760 | do { | |
761 | flags = tp->tsq_flags; | |
762 | if (!(flags & TCP_DEFERRED_ALL)) | |
763 | return; | |
764 | nflags = flags & ~TCP_DEFERRED_ALL; | |
765 | } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); | |
766 | ||
767 | if (flags & (1UL << TCP_TSQ_DEFERRED)) | |
768 | tcp_tsq_handler(sk); | |
769 | ||
c3f9b018 ED |
770 | /* Here begins the tricky part : |
771 | * We are called from release_sock() with : | |
772 | * 1) BH disabled | |
773 | * 2) sk_lock.slock spinlock held | |
774 | * 3) socket owned by us (sk->sk_lock.owned == 1) | |
775 | * | |
776 | * But following code is meant to be called from BH handlers, | |
777 | * so we should keep BH disabled, but early release socket ownership | |
778 | */ | |
779 | sock_release_ownership(sk); | |
780 | ||
144d56e9 | 781 | if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { |
6f458dfb | 782 | tcp_write_timer_handler(sk); |
144d56e9 ED |
783 | __sock_put(sk); |
784 | } | |
785 | if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { | |
6f458dfb | 786 | tcp_delack_timer_handler(sk); |
144d56e9 ED |
787 | __sock_put(sk); |
788 | } | |
789 | if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { | |
563d34d0 | 790 | sk->sk_prot->mtu_reduced(sk); |
144d56e9 ED |
791 | __sock_put(sk); |
792 | } | |
46d3ceab ED |
793 | } |
794 | EXPORT_SYMBOL(tcp_release_cb); | |
795 | ||
796 | void __init tcp_tasklet_init(void) | |
797 | { | |
798 | int i; | |
799 | ||
800 | for_each_possible_cpu(i) { | |
801 | struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); | |
802 | ||
803 | INIT_LIST_HEAD(&tsq->head); | |
804 | tasklet_init(&tsq->tasklet, | |
805 | tcp_tasklet_func, | |
806 | (unsigned long)tsq); | |
807 | } | |
808 | } | |
809 | ||
810 | /* | |
811 | * Write buffer destructor automatically called from kfree_skb. | |
8e3bff96 | 812 | * We can't xmit new skbs from this context, as we might already |
46d3ceab ED |
813 | * hold qdisc lock. |
814 | */ | |
d6a4a104 | 815 | void tcp_wfree(struct sk_buff *skb) |
46d3ceab ED |
816 | { |
817 | struct sock *sk = skb->sk; | |
818 | struct tcp_sock *tp = tcp_sk(sk); | |
819 | ||
820 | if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && | |
821 | !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { | |
822 | unsigned long flags; | |
823 | struct tsq_tasklet *tsq; | |
824 | ||
825 | /* Keep a ref on socket. | |
826 | * This last ref will be released in tcp_tasklet_func() | |
827 | */ | |
828 | atomic_sub(skb->truesize - 1, &sk->sk_wmem_alloc); | |
829 | ||
830 | /* queue this socket to tasklet queue */ | |
831 | local_irq_save(flags); | |
832 | tsq = &__get_cpu_var(tsq_tasklet); | |
833 | list_add(&tp->tsq_node, &tsq->head); | |
834 | tasklet_schedule(&tsq->tasklet); | |
835 | local_irq_restore(flags); | |
836 | } else { | |
837 | sock_wfree(skb); | |
838 | } | |
839 | } | |
840 | ||
1da177e4 LT |
841 | /* This routine actually transmits TCP packets queued in by |
842 | * tcp_do_sendmsg(). This is used by both the initial | |
843 | * transmission and possible later retransmissions. | |
844 | * All SKB's seen here are completely headerless. It is our | |
845 | * job to build the TCP header, and pass the packet down to | |
846 | * IP so it can do the same plus pass the packet off to the | |
847 | * device. | |
848 | * | |
849 | * We are working here with either a clone of the original | |
850 | * SKB, or a fresh unique copy made by the retransmit engine. | |
851 | */ | |
056834d9 IJ |
852 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
853 | gfp_t gfp_mask) | |
1da177e4 | 854 | { |
dfb4b9dc DM |
855 | const struct inet_connection_sock *icsk = inet_csk(sk); |
856 | struct inet_sock *inet; | |
857 | struct tcp_sock *tp; | |
858 | struct tcp_skb_cb *tcb; | |
33ad798c | 859 | struct tcp_out_options opts; |
95c96174 | 860 | unsigned int tcp_options_size, tcp_header_size; |
cfb6eeb4 | 861 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 862 | struct tcphdr *th; |
dfb4b9dc DM |
863 | int err; |
864 | ||
865 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
866 | ||
ccdbb6e9 | 867 | if (clone_it) { |
0e280af0 ED |
868 | const struct sk_buff *fclone = skb + 1; |
869 | ||
ccdbb6e9 ED |
870 | /* If congestion control is doing timestamping, we must |
871 | * take such a timestamp before we potentially clone/copy. | |
872 | */ | |
873 | if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) | |
874 | __net_timestamp(skb); | |
875 | ||
0e280af0 ED |
876 | if (unlikely(skb->fclone == SKB_FCLONE_ORIG && |
877 | fclone->fclone == SKB_FCLONE_CLONE)) | |
9a9bfd03 ED |
878 | NET_INC_STATS(sock_net(sk), |
879 | LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); | |
0e280af0 | 880 | |
dfb4b9dc DM |
881 | if (unlikely(skb_cloned(skb))) |
882 | skb = pskb_copy(skb, gfp_mask); | |
883 | else | |
884 | skb = skb_clone(skb, gfp_mask); | |
885 | if (unlikely(!skb)) | |
886 | return -ENOBUFS; | |
887 | } | |
1da177e4 | 888 | |
dfb4b9dc DM |
889 | inet = inet_sk(sk); |
890 | tp = tcp_sk(sk); | |
891 | tcb = TCP_SKB_CB(skb); | |
33ad798c | 892 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 893 | |
4de075e0 | 894 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) |
33ad798c AL |
895 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
896 | else | |
897 | tcp_options_size = tcp_established_options(sk, skb, &opts, | |
898 | &md5); | |
899 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); | |
e905a9ed | 900 | |
547669d4 | 901 | if (tcp_packets_in_flight(tp) == 0) |
dfb4b9dc | 902 | tcp_ca_event(sk, CA_EVENT_TX_START); |
547669d4 ED |
903 | |
904 | /* if no packet is in qdisc/device queue, then allow XPS to select | |
905 | * another queue. | |
906 | */ | |
907 | skb->ooo_okay = sk_wmem_alloc_get(sk) == 0; | |
dfb4b9dc | 908 | |
aa8223c7 ACM |
909 | skb_push(skb, tcp_header_size); |
910 | skb_reset_transport_header(skb); | |
46d3ceab ED |
911 | |
912 | skb_orphan(skb); | |
913 | skb->sk = sk; | |
c9eeec26 | 914 | skb->destructor = tcp_wfree; |
46d3ceab | 915 | atomic_add(skb->truesize, &sk->sk_wmem_alloc); |
dfb4b9dc DM |
916 | |
917 | /* Build TCP header and checksum it. */ | |
aa8223c7 | 918 | th = tcp_hdr(skb); |
c720c7e8 ED |
919 | th->source = inet->inet_sport; |
920 | th->dest = inet->inet_dport; | |
dfb4b9dc DM |
921 | th->seq = htonl(tcb->seq); |
922 | th->ack_seq = htonl(tp->rcv_nxt); | |
df7a3b07 | 923 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
4de075e0 | 924 | tcb->tcp_flags); |
dfb4b9dc | 925 | |
4de075e0 | 926 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
dfb4b9dc DM |
927 | /* RFC1323: The window in SYN & SYN/ACK segments |
928 | * is never scaled. | |
929 | */ | |
600ff0c2 | 930 | th->window = htons(min(tp->rcv_wnd, 65535U)); |
dfb4b9dc DM |
931 | } else { |
932 | th->window = htons(tcp_select_window(sk)); | |
933 | } | |
934 | th->check = 0; | |
935 | th->urg_ptr = 0; | |
1da177e4 | 936 | |
33f5f57e | 937 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
938 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
939 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
940 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
941 | th->urg = 1; | |
942 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
0eae88f3 | 943 | th->urg_ptr = htons(0xFFFF); |
7691367d HX |
944 | th->urg = 1; |
945 | } | |
dfb4b9dc | 946 | } |
1da177e4 | 947 | |
bd0388ae | 948 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
4de075e0 | 949 | if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) |
9e412ba7 | 950 | TCP_ECN_send(sk, skb, tcp_header_size); |
1da177e4 | 951 | |
cfb6eeb4 YH |
952 | #ifdef CONFIG_TCP_MD5SIG |
953 | /* Calculate the MD5 hash, as we have all we need now */ | |
954 | if (md5) { | |
a465419b | 955 | sk_nocaps_add(sk, NETIF_F_GSO_MASK); |
bd0388ae | 956 | tp->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 957 | md5, sk, NULL, skb); |
cfb6eeb4 YH |
958 | } |
959 | #endif | |
960 | ||
bb296246 | 961 | icsk->icsk_af_ops->send_check(sk, skb); |
1da177e4 | 962 | |
4de075e0 | 963 | if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
dfb4b9dc | 964 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); |
1da177e4 | 965 | |
dfb4b9dc | 966 | if (skb->len != tcp_header_size) |
cf533ea5 | 967 | tcp_event_data_sent(tp, sk); |
1da177e4 | 968 | |
bd37a088 | 969 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
aa2ea058 TH |
970 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
971 | tcp_skb_pcount(skb)); | |
1da177e4 | 972 | |
d9d8da80 | 973 | err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl); |
83de47cd | 974 | if (likely(err <= 0)) |
dfb4b9dc DM |
975 | return err; |
976 | ||
3cfe3baa | 977 | tcp_enter_cwr(sk, 1); |
dfb4b9dc | 978 | |
b9df3cb8 | 979 | return net_xmit_eval(err); |
1da177e4 LT |
980 | } |
981 | ||
67edfef7 | 982 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
983 | * |
984 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
985 | * otherwise socket can stall. | |
986 | */ | |
987 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
988 | { | |
989 | struct tcp_sock *tp = tcp_sk(sk); | |
990 | ||
991 | /* Advance write_seq and place onto the write_queue. */ | |
992 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
993 | skb_header_release(skb); | |
fe067e8a | 994 | tcp_add_write_queue_tail(sk, skb); |
3ab224be HA |
995 | sk->sk_wmem_queued += skb->truesize; |
996 | sk_mem_charge(sk, skb->truesize); | |
1da177e4 LT |
997 | } |
998 | ||
67edfef7 | 999 | /* Initialize TSO segments for a packet. */ |
cf533ea5 | 1000 | static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, |
056834d9 | 1001 | unsigned int mss_now) |
f6302d1d | 1002 | { |
7b7fc97a ED |
1003 | struct skb_shared_info *shinfo = skb_shinfo(skb); |
1004 | ||
c52e2421 ED |
1005 | /* Make sure we own this skb before messing gso_size/gso_segs */ |
1006 | WARN_ON_ONCE(skb_cloned(skb)); | |
1007 | ||
8f26fb1c | 1008 | if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { |
f6302d1d DM |
1009 | /* Avoid the costly divide in the normal |
1010 | * non-TSO case. | |
1011 | */ | |
7b7fc97a ED |
1012 | shinfo->gso_segs = 1; |
1013 | shinfo->gso_size = 0; | |
1014 | shinfo->gso_type = 0; | |
f6302d1d | 1015 | } else { |
7b7fc97a ED |
1016 | shinfo->gso_segs = DIV_ROUND_UP(skb->len, mss_now); |
1017 | shinfo->gso_size = mss_now; | |
1018 | shinfo->gso_type = sk->sk_gso_type; | |
1da177e4 LT |
1019 | } |
1020 | } | |
1021 | ||
91fed7a1 | 1022 | /* When a modification to fackets out becomes necessary, we need to check |
68f8353b | 1023 | * skb is counted to fackets_out or not. |
91fed7a1 | 1024 | */ |
cf533ea5 | 1025 | static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, |
91fed7a1 IJ |
1026 | int decr) |
1027 | { | |
a47e5a98 IJ |
1028 | struct tcp_sock *tp = tcp_sk(sk); |
1029 | ||
dc86967b | 1030 | if (!tp->sacked_out || tcp_is_reno(tp)) |
91fed7a1 IJ |
1031 | return; |
1032 | ||
6859d494 | 1033 | if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) |
91fed7a1 | 1034 | tp->fackets_out -= decr; |
91fed7a1 IJ |
1035 | } |
1036 | ||
797108d1 IJ |
1037 | /* Pcount in the middle of the write queue got changed, we need to do various |
1038 | * tweaks to fix counters | |
1039 | */ | |
cf533ea5 | 1040 | static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
797108d1 IJ |
1041 | { |
1042 | struct tcp_sock *tp = tcp_sk(sk); | |
1043 | ||
1044 | tp->packets_out -= decr; | |
1045 | ||
1046 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
1047 | tp->sacked_out -= decr; | |
1048 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
1049 | tp->retrans_out -= decr; | |
1050 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
1051 | tp->lost_out -= decr; | |
1052 | ||
1053 | /* Reno case is special. Sigh... */ | |
1054 | if (tcp_is_reno(tp) && decr > 0) | |
1055 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
1056 | ||
1057 | tcp_adjust_fackets_out(sk, skb, decr); | |
1058 | ||
1059 | if (tp->lost_skb_hint && | |
1060 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
52cf3cc8 | 1061 | (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) |
797108d1 IJ |
1062 | tp->lost_cnt_hint -= decr; |
1063 | ||
1064 | tcp_verify_left_out(tp); | |
1065 | } | |
1066 | ||
1da177e4 LT |
1067 | /* Function to create two new TCP segments. Shrinks the given segment |
1068 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 1069 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
1070 | * Remember, these are still headerless SKBs at this point. |
1071 | */ | |
056834d9 IJ |
1072 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, |
1073 | unsigned int mss_now) | |
1da177e4 LT |
1074 | { |
1075 | struct tcp_sock *tp = tcp_sk(sk); | |
1076 | struct sk_buff *buff; | |
6475be16 | 1077 | int nsize, old_factor; |
b60b49ea | 1078 | int nlen; |
9ce01461 | 1079 | u8 flags; |
1da177e4 | 1080 | |
2fceec13 IJ |
1081 | if (WARN_ON(len > skb->len)) |
1082 | return -EINVAL; | |
6a438bbe | 1083 | |
1da177e4 LT |
1084 | nsize = skb_headlen(skb) - len; |
1085 | if (nsize < 0) | |
1086 | nsize = 0; | |
1087 | ||
c52e2421 | 1088 | if (skb_unclone(skb, GFP_ATOMIC)) |
1da177e4 LT |
1089 | return -ENOMEM; |
1090 | ||
1091 | /* Get a new skb... force flag on. */ | |
1092 | buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); | |
1093 | if (buff == NULL) | |
1094 | return -ENOMEM; /* We'll just try again later. */ | |
ef5cb973 | 1095 | |
3ab224be HA |
1096 | sk->sk_wmem_queued += buff->truesize; |
1097 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea HX |
1098 | nlen = skb->len - len - nsize; |
1099 | buff->truesize += nlen; | |
1100 | skb->truesize -= nlen; | |
1da177e4 LT |
1101 | |
1102 | /* Correct the sequence numbers. */ | |
1103 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1104 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1105 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1106 | ||
1107 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1108 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1109 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1110 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
e14c3caf | 1111 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 | 1112 | |
84fa7933 | 1113 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { |
1da177e4 | 1114 | /* Copy and checksum data tail into the new buffer. */ |
056834d9 IJ |
1115 | buff->csum = csum_partial_copy_nocheck(skb->data + len, |
1116 | skb_put(buff, nsize), | |
1da177e4 LT |
1117 | nsize, 0); |
1118 | ||
1119 | skb_trim(skb, len); | |
1120 | ||
1121 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
1122 | } else { | |
84fa7933 | 1123 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1124 | skb_split(skb, buff, len); |
1125 | } | |
1126 | ||
1127 | buff->ip_summed = skb->ip_summed; | |
1128 | ||
1129 | /* Looks stupid, but our code really uses when of | |
1130 | * skbs, which it never sent before. --ANK | |
1131 | */ | |
1132 | TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; | |
a61bbcf2 | 1133 | buff->tstamp = skb->tstamp; |
1da177e4 | 1134 | |
6475be16 DM |
1135 | old_factor = tcp_skb_pcount(skb); |
1136 | ||
1da177e4 | 1137 | /* Fix up tso_factor for both original and new SKB. */ |
846998ae DM |
1138 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1139 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
1da177e4 | 1140 | |
6475be16 DM |
1141 | /* If this packet has been sent out already, we must |
1142 | * adjust the various packet counters. | |
1143 | */ | |
cf0b450c | 1144 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1145 | int diff = old_factor - tcp_skb_pcount(skb) - |
1146 | tcp_skb_pcount(buff); | |
1da177e4 | 1147 | |
797108d1 IJ |
1148 | if (diff) |
1149 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1150 | } |
1151 | ||
1152 | /* Link BUFF into the send queue. */ | |
f44b5271 | 1153 | skb_header_release(buff); |
fe067e8a | 1154 | tcp_insert_write_queue_after(skb, buff, sk); |
1da177e4 LT |
1155 | |
1156 | return 0; | |
1157 | } | |
1158 | ||
1159 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
1160 | * eventually). The difference is that pulled data not copied, but | |
1161 | * immediately discarded. | |
1162 | */ | |
f2911969 | 1163 | static void __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 | 1164 | { |
7b7fc97a | 1165 | struct skb_shared_info *shinfo; |
1da177e4 LT |
1166 | int i, k, eat; |
1167 | ||
4fa48bf3 ED |
1168 | eat = min_t(int, len, skb_headlen(skb)); |
1169 | if (eat) { | |
1170 | __skb_pull(skb, eat); | |
1171 | len -= eat; | |
1172 | if (!len) | |
1173 | return; | |
1174 | } | |
1da177e4 LT |
1175 | eat = len; |
1176 | k = 0; | |
7b7fc97a ED |
1177 | shinfo = skb_shinfo(skb); |
1178 | for (i = 0; i < shinfo->nr_frags; i++) { | |
1179 | int size = skb_frag_size(&shinfo->frags[i]); | |
9e903e08 ED |
1180 | |
1181 | if (size <= eat) { | |
aff65da0 | 1182 | skb_frag_unref(skb, i); |
9e903e08 | 1183 | eat -= size; |
1da177e4 | 1184 | } else { |
7b7fc97a | 1185 | shinfo->frags[k] = shinfo->frags[i]; |
1da177e4 | 1186 | if (eat) { |
7b7fc97a ED |
1187 | shinfo->frags[k].page_offset += eat; |
1188 | skb_frag_size_sub(&shinfo->frags[k], eat); | |
1da177e4 LT |
1189 | eat = 0; |
1190 | } | |
1191 | k++; | |
1192 | } | |
1193 | } | |
7b7fc97a | 1194 | shinfo->nr_frags = k; |
1da177e4 | 1195 | |
27a884dc | 1196 | skb_reset_tail_pointer(skb); |
1da177e4 LT |
1197 | skb->data_len -= len; |
1198 | skb->len = skb->data_len; | |
1da177e4 LT |
1199 | } |
1200 | ||
67edfef7 | 1201 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1202 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1203 | { | |
14bbd6a5 | 1204 | if (skb_unclone(skb, GFP_ATOMIC)) |
1da177e4 LT |
1205 | return -ENOMEM; |
1206 | ||
4fa48bf3 | 1207 | __pskb_trim_head(skb, len); |
1da177e4 LT |
1208 | |
1209 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 1210 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1211 | |
1212 | skb->truesize -= len; | |
1213 | sk->sk_wmem_queued -= len; | |
3ab224be | 1214 | sk_mem_uncharge(sk, len); |
1da177e4 LT |
1215 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); |
1216 | ||
5b35e1e6 | 1217 | /* Any change of skb->len requires recalculation of tso factor. */ |
1da177e4 | 1218 | if (tcp_skb_pcount(skb) > 1) |
5b35e1e6 | 1219 | tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); |
1da177e4 LT |
1220 | |
1221 | return 0; | |
1222 | } | |
1223 | ||
1b63edd6 YC |
1224 | /* Calculate MSS not accounting any TCP options. */ |
1225 | static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
5d424d5a | 1226 | { |
cf533ea5 ED |
1227 | const struct tcp_sock *tp = tcp_sk(sk); |
1228 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1229 | int mss_now; |
1230 | ||
1231 | /* Calculate base mss without TCP options: | |
1232 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1233 | */ | |
1234 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1235 | ||
67469601 ED |
1236 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1237 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1238 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1239 | ||
1240 | if (dst && dst_allfrag(dst)) | |
1241 | mss_now -= icsk->icsk_af_ops->net_frag_header_len; | |
1242 | } | |
1243 | ||
5d424d5a JH |
1244 | /* Clamp it (mss_clamp does not include tcp options) */ |
1245 | if (mss_now > tp->rx_opt.mss_clamp) | |
1246 | mss_now = tp->rx_opt.mss_clamp; | |
1247 | ||
1248 | /* Now subtract optional transport overhead */ | |
1249 | mss_now -= icsk->icsk_ext_hdr_len; | |
1250 | ||
1251 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
1252 | if (mss_now < 48) | |
1253 | mss_now = 48; | |
5d424d5a JH |
1254 | return mss_now; |
1255 | } | |
1256 | ||
1b63edd6 YC |
1257 | /* Calculate MSS. Not accounting for SACKs here. */ |
1258 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
1259 | { | |
1260 | /* Subtract TCP options size, not including SACKs */ | |
1261 | return __tcp_mtu_to_mss(sk, pmtu) - | |
1262 | (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); | |
1263 | } | |
1264 | ||
5d424d5a | 1265 | /* Inverse of above */ |
67469601 | 1266 | int tcp_mss_to_mtu(struct sock *sk, int mss) |
5d424d5a | 1267 | { |
cf533ea5 ED |
1268 | const struct tcp_sock *tp = tcp_sk(sk); |
1269 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1270 | int mtu; |
1271 | ||
1272 | mtu = mss + | |
1273 | tp->tcp_header_len + | |
1274 | icsk->icsk_ext_hdr_len + | |
1275 | icsk->icsk_af_ops->net_header_len; | |
1276 | ||
67469601 ED |
1277 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1278 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1279 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1280 | ||
1281 | if (dst && dst_allfrag(dst)) | |
1282 | mtu += icsk->icsk_af_ops->net_frag_header_len; | |
1283 | } | |
5d424d5a JH |
1284 | return mtu; |
1285 | } | |
1286 | ||
67edfef7 | 1287 | /* MTU probing init per socket */ |
5d424d5a JH |
1288 | void tcp_mtup_init(struct sock *sk) |
1289 | { | |
1290 | struct tcp_sock *tp = tcp_sk(sk); | |
1291 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1292 | ||
1293 | icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; | |
1294 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + | |
e905a9ed | 1295 | icsk->icsk_af_ops->net_header_len; |
5d424d5a JH |
1296 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); |
1297 | icsk->icsk_mtup.probe_size = 0; | |
1298 | } | |
4bc2f18b | 1299 | EXPORT_SYMBOL(tcp_mtup_init); |
5d424d5a | 1300 | |
1da177e4 LT |
1301 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1302 | ||
1303 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1304 | for TCP options, but includes only bare TCP header. | |
1305 | ||
1306 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1307 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1308 | It also does not include TCP options. |
1309 | ||
d83d8461 | 1310 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1311 | |
1312 | tp->mss_cache is current effective sending mss, including | |
1313 | all tcp options except for SACKs. It is evaluated, | |
1314 | taking into account current pmtu, but never exceeds | |
1315 | tp->rx_opt.mss_clamp. | |
1316 | ||
1317 | NOTE1. rfc1122 clearly states that advertised MSS | |
1318 | DOES NOT include either tcp or ip options. | |
1319 | ||
d83d8461 ACM |
1320 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1321 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1322 | */ |
1da177e4 LT |
1323 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1324 | { | |
1325 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1326 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1327 | int mss_now; |
1da177e4 | 1328 | |
5d424d5a JH |
1329 | if (icsk->icsk_mtup.search_high > pmtu) |
1330 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1331 | |
5d424d5a | 1332 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1333 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1334 | |
1335 | /* And store cached results */ | |
d83d8461 | 1336 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1337 | if (icsk->icsk_mtup.enabled) |
1338 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1339 | tp->mss_cache = mss_now; |
1da177e4 LT |
1340 | |
1341 | return mss_now; | |
1342 | } | |
4bc2f18b | 1343 | EXPORT_SYMBOL(tcp_sync_mss); |
1da177e4 LT |
1344 | |
1345 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1346 | * and even PMTU discovery events into account. | |
1da177e4 | 1347 | */ |
0c54b85f | 1348 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 | 1349 | { |
cf533ea5 ED |
1350 | const struct tcp_sock *tp = tcp_sk(sk); |
1351 | const struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1352 | u32 mss_now; |
95c96174 | 1353 | unsigned int header_len; |
33ad798c AL |
1354 | struct tcp_out_options opts; |
1355 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1356 | |
1357 | mss_now = tp->mss_cache; | |
1358 | ||
1da177e4 LT |
1359 | if (dst) { |
1360 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1361 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1362 | mss_now = tcp_sync_mss(sk, mtu); |
1363 | } | |
1364 | ||
33ad798c AL |
1365 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1366 | sizeof(struct tcphdr); | |
1367 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1368 | * some common options. If this is an odd packet (because we have SACK | |
1369 | * blocks etc) then our calculated header_len will be different, and | |
1370 | * we have to adjust mss_now correspondingly */ | |
1371 | if (header_len != tp->tcp_header_len) { | |
1372 | int delta = (int) header_len - tp->tcp_header_len; | |
1373 | mss_now -= delta; | |
1374 | } | |
cfb6eeb4 | 1375 | |
1da177e4 LT |
1376 | return mss_now; |
1377 | } | |
1378 | ||
a762a980 | 1379 | /* Congestion window validation. (RFC2861) */ |
9e412ba7 | 1380 | static void tcp_cwnd_validate(struct sock *sk) |
a762a980 | 1381 | { |
9e412ba7 | 1382 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1383 | |
d436d686 | 1384 | if (tp->packets_out >= tp->snd_cwnd) { |
a762a980 DM |
1385 | /* Network is feed fully. */ |
1386 | tp->snd_cwnd_used = 0; | |
1387 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1388 | } else { | |
1389 | /* Network starves. */ | |
1390 | if (tp->packets_out > tp->snd_cwnd_used) | |
1391 | tp->snd_cwnd_used = tp->packets_out; | |
1392 | ||
15d33c07 DM |
1393 | if (sysctl_tcp_slow_start_after_idle && |
1394 | (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) | |
a762a980 DM |
1395 | tcp_cwnd_application_limited(sk); |
1396 | } | |
1397 | } | |
1398 | ||
d4589926 ED |
1399 | /* Minshall's variant of the Nagle send check. */ |
1400 | static bool tcp_minshall_check(const struct tcp_sock *tp) | |
1401 | { | |
1402 | return after(tp->snd_sml, tp->snd_una) && | |
1403 | !after(tp->snd_sml, tp->snd_nxt); | |
1404 | } | |
1405 | ||
1406 | /* Update snd_sml if this skb is under mss | |
1407 | * Note that a TSO packet might end with a sub-mss segment | |
1408 | * The test is really : | |
1409 | * if ((skb->len % mss) != 0) | |
1410 | * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1411 | * But we can avoid doing the divide again given we already have | |
1412 | * skb_pcount = skb->len / mss_now | |
0e3a4803 | 1413 | */ |
d4589926 ED |
1414 | static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
1415 | const struct sk_buff *skb) | |
1416 | { | |
1417 | if (skb->len < tcp_skb_pcount(skb) * mss_now) | |
1418 | tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1419 | } | |
1420 | ||
1421 | /* Return false, if packet can be sent now without violation Nagle's rules: | |
1422 | * 1. It is full sized. (provided by caller in %partial bool) | |
1423 | * 2. Or it contains FIN. (already checked by caller) | |
1424 | * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. | |
1425 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
1426 | * With Minshall's modification: all sent small packets are ACKed. | |
1427 | */ | |
1428 | static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, | |
1429 | unsigned int mss_now, int nonagle) | |
1430 | { | |
1431 | return partial && | |
1432 | ((nonagle & TCP_NAGLE_CORK) || | |
1433 | (!nonagle && tp->packets_out && tcp_minshall_check(tp))); | |
1434 | } | |
1435 | /* Returns the portion of skb which can be sent right away */ | |
1436 | static unsigned int tcp_mss_split_point(const struct sock *sk, | |
1437 | const struct sk_buff *skb, | |
1438 | unsigned int mss_now, | |
1439 | unsigned int max_segs, | |
1440 | int nonagle) | |
c1b4a7e6 | 1441 | { |
cf533ea5 | 1442 | const struct tcp_sock *tp = tcp_sk(sk); |
d4589926 | 1443 | u32 partial, needed, window, max_len; |
c1b4a7e6 | 1444 | |
90840def | 1445 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
1485348d | 1446 | max_len = mss_now * max_segs; |
0e3a4803 | 1447 | |
1485348d BH |
1448 | if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
1449 | return max_len; | |
0e3a4803 | 1450 | |
5ea3a748 IJ |
1451 | needed = min(skb->len, window); |
1452 | ||
1485348d BH |
1453 | if (max_len <= needed) |
1454 | return max_len; | |
0e3a4803 | 1455 | |
d4589926 ED |
1456 | partial = needed % mss_now; |
1457 | /* If last segment is not a full MSS, check if Nagle rules allow us | |
1458 | * to include this last segment in this skb. | |
1459 | * Otherwise, we'll split the skb at last MSS boundary | |
1460 | */ | |
1461 | if (tcp_nagle_check(partial != 0, tp, mss_now, nonagle)) | |
1462 | return needed - partial; | |
1463 | ||
1464 | return needed; | |
c1b4a7e6 DM |
1465 | } |
1466 | ||
1467 | /* Can at least one segment of SKB be sent right now, according to the | |
1468 | * congestion window rules? If so, return how many segments are allowed. | |
1469 | */ | |
cf533ea5 ED |
1470 | static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
1471 | const struct sk_buff *skb) | |
c1b4a7e6 DM |
1472 | { |
1473 | u32 in_flight, cwnd; | |
1474 | ||
1475 | /* Don't be strict about the congestion window for the final FIN. */ | |
4de075e0 ED |
1476 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
1477 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
1478 | return 1; |
1479 | ||
1480 | in_flight = tcp_packets_in_flight(tp); | |
1481 | cwnd = tp->snd_cwnd; | |
1482 | if (in_flight < cwnd) | |
1483 | return (cwnd - in_flight); | |
1484 | ||
1485 | return 0; | |
1486 | } | |
1487 | ||
b595076a | 1488 | /* Initialize TSO state of a skb. |
67edfef7 | 1489 | * This must be invoked the first time we consider transmitting |
c1b4a7e6 DM |
1490 | * SKB onto the wire. |
1491 | */ | |
cf533ea5 | 1492 | static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, |
056834d9 | 1493 | unsigned int mss_now) |
c1b4a7e6 DM |
1494 | { |
1495 | int tso_segs = tcp_skb_pcount(skb); | |
1496 | ||
f8269a49 | 1497 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
846998ae | 1498 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
1499 | tso_segs = tcp_skb_pcount(skb); |
1500 | } | |
1501 | return tso_segs; | |
1502 | } | |
1503 | ||
c1b4a7e6 | 1504 | |
a2a385d6 | 1505 | /* Return true if the Nagle test allows this packet to be |
c1b4a7e6 DM |
1506 | * sent now. |
1507 | */ | |
a2a385d6 ED |
1508 | static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
1509 | unsigned int cur_mss, int nonagle) | |
c1b4a7e6 DM |
1510 | { |
1511 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
1512 | * write_queue (they have no chances to get new data). | |
1513 | * | |
1514 | * This is implemented in the callers, where they modify the 'nonagle' | |
1515 | * argument based upon the location of SKB in the send queue. | |
1516 | */ | |
1517 | if (nonagle & TCP_NAGLE_PUSH) | |
a2a385d6 | 1518 | return true; |
c1b4a7e6 | 1519 | |
9b44190d YC |
1520 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
1521 | if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) | |
a2a385d6 | 1522 | return true; |
c1b4a7e6 | 1523 | |
d4589926 | 1524 | if (!tcp_nagle_check(skb->len < cur_mss, tp, cur_mss, nonagle)) |
a2a385d6 | 1525 | return true; |
c1b4a7e6 | 1526 | |
a2a385d6 | 1527 | return false; |
c1b4a7e6 DM |
1528 | } |
1529 | ||
1530 | /* Does at least the first segment of SKB fit into the send window? */ | |
a2a385d6 ED |
1531 | static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
1532 | const struct sk_buff *skb, | |
1533 | unsigned int cur_mss) | |
c1b4a7e6 DM |
1534 | { |
1535 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
1536 | ||
1537 | if (skb->len > cur_mss) | |
1538 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
1539 | ||
90840def | 1540 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
1541 | } |
1542 | ||
fe067e8a | 1543 | /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) |
c1b4a7e6 DM |
1544 | * should be put on the wire right now. If so, it returns the number of |
1545 | * packets allowed by the congestion window. | |
1546 | */ | |
cf533ea5 | 1547 | static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, |
c1b4a7e6 DM |
1548 | unsigned int cur_mss, int nonagle) |
1549 | { | |
cf533ea5 | 1550 | const struct tcp_sock *tp = tcp_sk(sk); |
c1b4a7e6 DM |
1551 | unsigned int cwnd_quota; |
1552 | ||
846998ae | 1553 | tcp_init_tso_segs(sk, skb, cur_mss); |
c1b4a7e6 DM |
1554 | |
1555 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
1556 | return 0; | |
1557 | ||
1558 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
056834d9 | 1559 | if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) |
c1b4a7e6 DM |
1560 | cwnd_quota = 0; |
1561 | ||
1562 | return cwnd_quota; | |
1563 | } | |
1564 | ||
67edfef7 | 1565 | /* Test if sending is allowed right now. */ |
a2a385d6 | 1566 | bool tcp_may_send_now(struct sock *sk) |
c1b4a7e6 | 1567 | { |
cf533ea5 | 1568 | const struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 1569 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 | 1570 | |
a02cec21 | 1571 | return skb && |
0c54b85f | 1572 | tcp_snd_test(sk, skb, tcp_current_mss(sk), |
c1b4a7e6 | 1573 | (tcp_skb_is_last(sk, skb) ? |
a02cec21 | 1574 | tp->nonagle : TCP_NAGLE_PUSH)); |
c1b4a7e6 DM |
1575 | } |
1576 | ||
1577 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet | |
1578 | * which is put after SKB on the list. It is very much like | |
1579 | * tcp_fragment() except that it may make several kinds of assumptions | |
1580 | * in order to speed up the splitting operation. In particular, we | |
1581 | * know that all the data is in scatter-gather pages, and that the | |
1582 | * packet has never been sent out before (and thus is not cloned). | |
1583 | */ | |
056834d9 | 1584 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
c4ead4c5 | 1585 | unsigned int mss_now, gfp_t gfp) |
c1b4a7e6 DM |
1586 | { |
1587 | struct sk_buff *buff; | |
1588 | int nlen = skb->len - len; | |
9ce01461 | 1589 | u8 flags; |
c1b4a7e6 DM |
1590 | |
1591 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 HX |
1592 | if (skb->len != skb->data_len) |
1593 | return tcp_fragment(sk, skb, len, mss_now); | |
c1b4a7e6 | 1594 | |
c4ead4c5 | 1595 | buff = sk_stream_alloc_skb(sk, 0, gfp); |
c1b4a7e6 DM |
1596 | if (unlikely(buff == NULL)) |
1597 | return -ENOMEM; | |
1598 | ||
3ab224be HA |
1599 | sk->sk_wmem_queued += buff->truesize; |
1600 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea | 1601 | buff->truesize += nlen; |
c1b4a7e6 DM |
1602 | skb->truesize -= nlen; |
1603 | ||
1604 | /* Correct the sequence numbers. */ | |
1605 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1606 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1607 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1608 | ||
1609 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1610 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1611 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1612 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
c1b4a7e6 DM |
1613 | |
1614 | /* This packet was never sent out yet, so no SACK bits. */ | |
1615 | TCP_SKB_CB(buff)->sacked = 0; | |
1616 | ||
84fa7933 | 1617 | buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; |
c1b4a7e6 DM |
1618 | skb_split(skb, buff, len); |
1619 | ||
1620 | /* Fix up tso_factor for both original and new SKB. */ | |
846998ae DM |
1621 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1622 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
c1b4a7e6 DM |
1623 | |
1624 | /* Link BUFF into the send queue. */ | |
1625 | skb_header_release(buff); | |
fe067e8a | 1626 | tcp_insert_write_queue_after(skb, buff, sk); |
c1b4a7e6 DM |
1627 | |
1628 | return 0; | |
1629 | } | |
1630 | ||
1631 | /* Try to defer sending, if possible, in order to minimize the amount | |
1632 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1633 | * | |
1634 | * This algorithm is from John Heffner. | |
1635 | */ | |
a2a385d6 | 1636 | static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) |
c1b4a7e6 | 1637 | { |
9e412ba7 | 1638 | struct tcp_sock *tp = tcp_sk(sk); |
6687e988 | 1639 | const struct inet_connection_sock *icsk = inet_csk(sk); |
c1b4a7e6 | 1640 | u32 send_win, cong_win, limit, in_flight; |
ad9f4f50 | 1641 | int win_divisor; |
c1b4a7e6 | 1642 | |
4de075e0 | 1643 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) |
ae8064ac | 1644 | goto send_now; |
c1b4a7e6 | 1645 | |
6687e988 | 1646 | if (icsk->icsk_ca_state != TCP_CA_Open) |
ae8064ac JH |
1647 | goto send_now; |
1648 | ||
1649 | /* Defer for less than two clock ticks. */ | |
bd515c3e | 1650 | if (tp->tso_deferred && |
a2acde07 | 1651 | (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) |
ae8064ac | 1652 | goto send_now; |
908a75c1 | 1653 | |
c1b4a7e6 DM |
1654 | in_flight = tcp_packets_in_flight(tp); |
1655 | ||
056834d9 | 1656 | BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); |
c1b4a7e6 | 1657 | |
90840def | 1658 | send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 DM |
1659 | |
1660 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1661 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1662 | ||
1663 | limit = min(send_win, cong_win); | |
1664 | ||
ba244fe9 | 1665 | /* If a full-sized TSO skb can be sent, do it. */ |
1485348d | 1666 | if (limit >= min_t(unsigned int, sk->sk_gso_max_size, |
95bd09eb | 1667 | tp->xmit_size_goal_segs * tp->mss_cache)) |
ae8064ac | 1668 | goto send_now; |
ba244fe9 | 1669 | |
62ad2761 IJ |
1670 | /* Middle in queue won't get any more data, full sendable already? */ |
1671 | if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) | |
1672 | goto send_now; | |
1673 | ||
ad9f4f50 ED |
1674 | win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); |
1675 | if (win_divisor) { | |
c1b4a7e6 DM |
1676 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
1677 | ||
1678 | /* If at least some fraction of a window is available, | |
1679 | * just use it. | |
1680 | */ | |
ad9f4f50 | 1681 | chunk /= win_divisor; |
c1b4a7e6 | 1682 | if (limit >= chunk) |
ae8064ac | 1683 | goto send_now; |
c1b4a7e6 DM |
1684 | } else { |
1685 | /* Different approach, try not to defer past a single | |
1686 | * ACK. Receiver should ACK every other full sized | |
1687 | * frame, so if we have space for more than 3 frames | |
1688 | * then send now. | |
1689 | */ | |
6b5a5c0d | 1690 | if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
ae8064ac | 1691 | goto send_now; |
c1b4a7e6 DM |
1692 | } |
1693 | ||
f4541d60 ED |
1694 | /* Ok, it looks like it is advisable to defer. |
1695 | * Do not rearm the timer if already set to not break TCP ACK clocking. | |
1696 | */ | |
1697 | if (!tp->tso_deferred) | |
1698 | tp->tso_deferred = 1 | (jiffies << 1); | |
ae8064ac | 1699 | |
a2a385d6 | 1700 | return true; |
ae8064ac JH |
1701 | |
1702 | send_now: | |
1703 | tp->tso_deferred = 0; | |
a2a385d6 | 1704 | return false; |
c1b4a7e6 DM |
1705 | } |
1706 | ||
5d424d5a | 1707 | /* Create a new MTU probe if we are ready. |
67edfef7 AK |
1708 | * MTU probe is regularly attempting to increase the path MTU by |
1709 | * deliberately sending larger packets. This discovers routing | |
1710 | * changes resulting in larger path MTUs. | |
1711 | * | |
5d424d5a JH |
1712 | * Returns 0 if we should wait to probe (no cwnd available), |
1713 | * 1 if a probe was sent, | |
056834d9 IJ |
1714 | * -1 otherwise |
1715 | */ | |
5d424d5a JH |
1716 | static int tcp_mtu_probe(struct sock *sk) |
1717 | { | |
1718 | struct tcp_sock *tp = tcp_sk(sk); | |
1719 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1720 | struct sk_buff *skb, *nskb, *next; | |
1721 | int len; | |
1722 | int probe_size; | |
91cc17c0 | 1723 | int size_needed; |
5d424d5a JH |
1724 | int copy; |
1725 | int mss_now; | |
1726 | ||
1727 | /* Not currently probing/verifying, | |
1728 | * not in recovery, | |
1729 | * have enough cwnd, and | |
1730 | * not SACKing (the variable headers throw things off) */ | |
1731 | if (!icsk->icsk_mtup.enabled || | |
1732 | icsk->icsk_mtup.probe_size || | |
1733 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
1734 | tp->snd_cwnd < 11 || | |
cabeccbd | 1735 | tp->rx_opt.num_sacks || tp->rx_opt.dsack) |
5d424d5a JH |
1736 | return -1; |
1737 | ||
1738 | /* Very simple search strategy: just double the MSS. */ | |
0c54b85f | 1739 | mss_now = tcp_current_mss(sk); |
056834d9 | 1740 | probe_size = 2 * tp->mss_cache; |
91cc17c0 | 1741 | size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
5d424d5a JH |
1742 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { |
1743 | /* TODO: set timer for probe_converge_event */ | |
1744 | return -1; | |
1745 | } | |
1746 | ||
1747 | /* Have enough data in the send queue to probe? */ | |
7f9c33e5 | 1748 | if (tp->write_seq - tp->snd_nxt < size_needed) |
5d424d5a JH |
1749 | return -1; |
1750 | ||
91cc17c0 IJ |
1751 | if (tp->snd_wnd < size_needed) |
1752 | return -1; | |
90840def | 1753 | if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
91cc17c0 | 1754 | return 0; |
5d424d5a | 1755 | |
d67c58e9 IJ |
1756 | /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
1757 | if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { | |
1758 | if (!tcp_packets_in_flight(tp)) | |
5d424d5a JH |
1759 | return -1; |
1760 | else | |
1761 | return 0; | |
1762 | } | |
1763 | ||
1764 | /* We're allowed to probe. Build it now. */ | |
1765 | if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) | |
1766 | return -1; | |
3ab224be HA |
1767 | sk->sk_wmem_queued += nskb->truesize; |
1768 | sk_mem_charge(sk, nskb->truesize); | |
5d424d5a | 1769 | |
fe067e8a | 1770 | skb = tcp_send_head(sk); |
5d424d5a JH |
1771 | |
1772 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
1773 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
4de075e0 | 1774 | TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
5d424d5a JH |
1775 | TCP_SKB_CB(nskb)->sacked = 0; |
1776 | nskb->csum = 0; | |
84fa7933 | 1777 | nskb->ip_summed = skb->ip_summed; |
5d424d5a | 1778 | |
50c4817e IJ |
1779 | tcp_insert_write_queue_before(nskb, skb, sk); |
1780 | ||
5d424d5a | 1781 | len = 0; |
234b6860 | 1782 | tcp_for_write_queue_from_safe(skb, next, sk) { |
5d424d5a JH |
1783 | copy = min_t(int, skb->len, probe_size - len); |
1784 | if (nskb->ip_summed) | |
1785 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); | |
1786 | else | |
1787 | nskb->csum = skb_copy_and_csum_bits(skb, 0, | |
056834d9 IJ |
1788 | skb_put(nskb, copy), |
1789 | copy, nskb->csum); | |
5d424d5a JH |
1790 | |
1791 | if (skb->len <= copy) { | |
1792 | /* We've eaten all the data from this skb. | |
1793 | * Throw it away. */ | |
4de075e0 | 1794 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
fe067e8a | 1795 | tcp_unlink_write_queue(skb, sk); |
3ab224be | 1796 | sk_wmem_free_skb(sk, skb); |
5d424d5a | 1797 | } else { |
4de075e0 | 1798 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
a3433f35 | 1799 | ~(TCPHDR_FIN|TCPHDR_PSH); |
5d424d5a JH |
1800 | if (!skb_shinfo(skb)->nr_frags) { |
1801 | skb_pull(skb, copy); | |
84fa7933 | 1802 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
056834d9 IJ |
1803 | skb->csum = csum_partial(skb->data, |
1804 | skb->len, 0); | |
5d424d5a JH |
1805 | } else { |
1806 | __pskb_trim_head(skb, copy); | |
1807 | tcp_set_skb_tso_segs(sk, skb, mss_now); | |
1808 | } | |
1809 | TCP_SKB_CB(skb)->seq += copy; | |
1810 | } | |
1811 | ||
1812 | len += copy; | |
234b6860 IJ |
1813 | |
1814 | if (len >= probe_size) | |
1815 | break; | |
5d424d5a JH |
1816 | } |
1817 | tcp_init_tso_segs(sk, nskb, nskb->len); | |
1818 | ||
1819 | /* We're ready to send. If this fails, the probe will | |
1820 | * be resegmented into mss-sized pieces by tcp_write_xmit(). */ | |
1821 | TCP_SKB_CB(nskb)->when = tcp_time_stamp; | |
1822 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { | |
1823 | /* Decrement cwnd here because we are sending | |
056834d9 | 1824 | * effectively two packets. */ |
5d424d5a | 1825 | tp->snd_cwnd--; |
66f5fe62 | 1826 | tcp_event_new_data_sent(sk, nskb); |
5d424d5a JH |
1827 | |
1828 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
1829 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
1830 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
1831 | |
1832 | return 1; | |
1833 | } | |
1834 | ||
1835 | return -1; | |
1836 | } | |
1837 | ||
1da177e4 LT |
1838 | /* This routine writes packets to the network. It advances the |
1839 | * send_head. This happens as incoming acks open up the remote | |
1840 | * window for us. | |
1841 | * | |
f8269a49 IJ |
1842 | * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
1843 | * snd_up-64k-mss .. snd_up cannot be large. However, taking into | |
1844 | * account rare use of URG, this is not a big flaw. | |
1845 | * | |
6ba8a3b1 ND |
1846 | * Send at most one packet when push_one > 0. Temporarily ignore |
1847 | * cwnd limit to force at most one packet out when push_one == 2. | |
1848 | ||
a2a385d6 ED |
1849 | * Returns true, if no segments are in flight and we have queued segments, |
1850 | * but cannot send anything now because of SWS or another problem. | |
1da177e4 | 1851 | */ |
a2a385d6 ED |
1852 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
1853 | int push_one, gfp_t gfp) | |
1da177e4 LT |
1854 | { |
1855 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 1856 | struct sk_buff *skb; |
c1b4a7e6 DM |
1857 | unsigned int tso_segs, sent_pkts; |
1858 | int cwnd_quota; | |
5d424d5a | 1859 | int result; |
1da177e4 | 1860 | |
92df7b51 | 1861 | sent_pkts = 0; |
5d424d5a | 1862 | |
d5dd9175 IJ |
1863 | if (!push_one) { |
1864 | /* Do MTU probing. */ | |
1865 | result = tcp_mtu_probe(sk); | |
1866 | if (!result) { | |
a2a385d6 | 1867 | return false; |
d5dd9175 IJ |
1868 | } else if (result > 0) { |
1869 | sent_pkts = 1; | |
1870 | } | |
5d424d5a JH |
1871 | } |
1872 | ||
fe067e8a | 1873 | while ((skb = tcp_send_head(sk))) { |
c8ac3774 HX |
1874 | unsigned int limit; |
1875 | ||
b68e9f85 | 1876 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 | 1877 | BUG_ON(!tso_segs); |
aa93466b | 1878 | |
ec342325 AV |
1879 | if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) |
1880 | goto repair; /* Skip network transmission */ | |
1881 | ||
b68e9f85 | 1882 | cwnd_quota = tcp_cwnd_test(tp, skb); |
6ba8a3b1 ND |
1883 | if (!cwnd_quota) { |
1884 | if (push_one == 2) | |
1885 | /* Force out a loss probe pkt. */ | |
1886 | cwnd_quota = 1; | |
1887 | else | |
1888 | break; | |
1889 | } | |
b68e9f85 HX |
1890 | |
1891 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) | |
1892 | break; | |
1893 | ||
c1b4a7e6 DM |
1894 | if (tso_segs == 1) { |
1895 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, | |
1896 | (tcp_skb_is_last(sk, skb) ? | |
1897 | nonagle : TCP_NAGLE_PUSH)))) | |
1898 | break; | |
1899 | } else { | |
d5dd9175 | 1900 | if (!push_one && tcp_tso_should_defer(sk, skb)) |
c1b4a7e6 DM |
1901 | break; |
1902 | } | |
aa93466b | 1903 | |
c9eeec26 ED |
1904 | /* TCP Small Queues : |
1905 | * Control number of packets in qdisc/devices to two packets / or ~1 ms. | |
1906 | * This allows for : | |
1907 | * - better RTT estimation and ACK scheduling | |
1908 | * - faster recovery | |
1909 | * - high rates | |
98e09386 ED |
1910 | * Alas, some drivers / subsystems require a fair amount |
1911 | * of queued bytes to ensure line rate. | |
1912 | * One example is wifi aggregation (802.11 AMPDU) | |
46d3ceab | 1913 | */ |
98e09386 ED |
1914 | limit = max_t(unsigned int, sysctl_tcp_limit_output_bytes, |
1915 | sk->sk_pacing_rate >> 10); | |
c9eeec26 ED |
1916 | |
1917 | if (atomic_read(&sk->sk_wmem_alloc) > limit) { | |
46d3ceab | 1918 | set_bit(TSQ_THROTTLED, &tp->tsq_flags); |
bf06200e JO |
1919 | /* It is possible TX completion already happened |
1920 | * before we set TSQ_THROTTLED, so we must | |
1921 | * test again the condition. | |
1922 | * We abuse smp_mb__after_clear_bit() because | |
1923 | * there is no smp_mb__after_set_bit() yet | |
1924 | */ | |
1925 | smp_mb__after_clear_bit(); | |
1926 | if (atomic_read(&sk->sk_wmem_alloc) > limit) | |
1927 | break; | |
46d3ceab | 1928 | } |
c9eeec26 | 1929 | |
c8ac3774 | 1930 | limit = mss_now; |
f8269a49 | 1931 | if (tso_segs > 1 && !tcp_urg_mode(tp)) |
0e3a4803 | 1932 | limit = tcp_mss_split_point(sk, skb, mss_now, |
1485348d BH |
1933 | min_t(unsigned int, |
1934 | cwnd_quota, | |
d4589926 ED |
1935 | sk->sk_gso_max_segs), |
1936 | nonagle); | |
1da177e4 | 1937 | |
c8ac3774 | 1938 | if (skb->len > limit && |
c4ead4c5 | 1939 | unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) |
c8ac3774 HX |
1940 | break; |
1941 | ||
92df7b51 | 1942 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
c1b4a7e6 | 1943 | |
d5dd9175 | 1944 | if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
92df7b51 | 1945 | break; |
1da177e4 | 1946 | |
ec342325 | 1947 | repair: |
92df7b51 DM |
1948 | /* Advance the send_head. This one is sent out. |
1949 | * This call will increment packets_out. | |
1950 | */ | |
66f5fe62 | 1951 | tcp_event_new_data_sent(sk, skb); |
1da177e4 | 1952 | |
92df7b51 | 1953 | tcp_minshall_update(tp, mss_now, skb); |
a262f0cd | 1954 | sent_pkts += tcp_skb_pcount(skb); |
d5dd9175 IJ |
1955 | |
1956 | if (push_one) | |
1957 | break; | |
92df7b51 | 1958 | } |
1da177e4 | 1959 | |
aa93466b | 1960 | if (likely(sent_pkts)) { |
684bad11 YC |
1961 | if (tcp_in_cwnd_reduction(sk)) |
1962 | tp->prr_out += sent_pkts; | |
6ba8a3b1 ND |
1963 | |
1964 | /* Send one loss probe per tail loss episode. */ | |
1965 | if (push_one != 2) | |
1966 | tcp_schedule_loss_probe(sk); | |
9e412ba7 | 1967 | tcp_cwnd_validate(sk); |
a2a385d6 | 1968 | return false; |
1da177e4 | 1969 | } |
6ba8a3b1 ND |
1970 | return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); |
1971 | } | |
1972 | ||
1973 | bool tcp_schedule_loss_probe(struct sock *sk) | |
1974 | { | |
1975 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1976 | struct tcp_sock *tp = tcp_sk(sk); | |
1977 | u32 timeout, tlp_time_stamp, rto_time_stamp; | |
1978 | u32 rtt = tp->srtt >> 3; | |
1979 | ||
1980 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) | |
1981 | return false; | |
1982 | /* No consecutive loss probes. */ | |
1983 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { | |
1984 | tcp_rearm_rto(sk); | |
1985 | return false; | |
1986 | } | |
1987 | /* Don't do any loss probe on a Fast Open connection before 3WHS | |
1988 | * finishes. | |
1989 | */ | |
1990 | if (sk->sk_state == TCP_SYN_RECV) | |
1991 | return false; | |
1992 | ||
1993 | /* TLP is only scheduled when next timer event is RTO. */ | |
1994 | if (icsk->icsk_pending != ICSK_TIME_RETRANS) | |
1995 | return false; | |
1996 | ||
1997 | /* Schedule a loss probe in 2*RTT for SACK capable connections | |
1998 | * in Open state, that are either limited by cwnd or application. | |
1999 | */ | |
4a5ab4e2 | 2000 | if (sysctl_tcp_early_retrans < 3 || !tp->srtt || !tp->packets_out || |
6ba8a3b1 ND |
2001 | !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) |
2002 | return false; | |
2003 | ||
2004 | if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && | |
2005 | tcp_send_head(sk)) | |
2006 | return false; | |
2007 | ||
2008 | /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account | |
2009 | * for delayed ack when there's one outstanding packet. | |
2010 | */ | |
2011 | timeout = rtt << 1; | |
2012 | if (tp->packets_out == 1) | |
2013 | timeout = max_t(u32, timeout, | |
2014 | (rtt + (rtt >> 1) + TCP_DELACK_MAX)); | |
2015 | timeout = max_t(u32, timeout, msecs_to_jiffies(10)); | |
2016 | ||
2017 | /* If RTO is shorter, just schedule TLP in its place. */ | |
2018 | tlp_time_stamp = tcp_time_stamp + timeout; | |
2019 | rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; | |
2020 | if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { | |
2021 | s32 delta = rto_time_stamp - tcp_time_stamp; | |
2022 | if (delta > 0) | |
2023 | timeout = delta; | |
2024 | } | |
2025 | ||
2026 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, | |
2027 | TCP_RTO_MAX); | |
2028 | return true; | |
2029 | } | |
2030 | ||
2031 | /* When probe timeout (PTO) fires, send a new segment if one exists, else | |
2032 | * retransmit the last segment. | |
2033 | */ | |
2034 | void tcp_send_loss_probe(struct sock *sk) | |
2035 | { | |
9b717a8d | 2036 | struct tcp_sock *tp = tcp_sk(sk); |
6ba8a3b1 ND |
2037 | struct sk_buff *skb; |
2038 | int pcount; | |
2039 | int mss = tcp_current_mss(sk); | |
2040 | int err = -1; | |
2041 | ||
2042 | if (tcp_send_head(sk) != NULL) { | |
2043 | err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); | |
2044 | goto rearm_timer; | |
2045 | } | |
2046 | ||
9b717a8d ND |
2047 | /* At most one outstanding TLP retransmission. */ |
2048 | if (tp->tlp_high_seq) | |
2049 | goto rearm_timer; | |
2050 | ||
6ba8a3b1 ND |
2051 | /* Retransmit last segment. */ |
2052 | skb = tcp_write_queue_tail(sk); | |
2053 | if (WARN_ON(!skb)) | |
2054 | goto rearm_timer; | |
2055 | ||
2056 | pcount = tcp_skb_pcount(skb); | |
2057 | if (WARN_ON(!pcount)) | |
2058 | goto rearm_timer; | |
2059 | ||
2060 | if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { | |
2061 | if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss))) | |
2062 | goto rearm_timer; | |
2063 | skb = tcp_write_queue_tail(sk); | |
2064 | } | |
2065 | ||
2066 | if (WARN_ON(!skb || !tcp_skb_pcount(skb))) | |
2067 | goto rearm_timer; | |
2068 | ||
2069 | /* Probe with zero data doesn't trigger fast recovery. */ | |
2070 | if (skb->len > 0) | |
2071 | err = __tcp_retransmit_skb(sk, skb); | |
2072 | ||
9b717a8d ND |
2073 | /* Record snd_nxt for loss detection. */ |
2074 | if (likely(!err)) | |
2075 | tp->tlp_high_seq = tp->snd_nxt; | |
2076 | ||
6ba8a3b1 ND |
2077 | rearm_timer: |
2078 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
2079 | inet_csk(sk)->icsk_rto, | |
2080 | TCP_RTO_MAX); | |
2081 | ||
2082 | if (likely(!err)) | |
2083 | NET_INC_STATS_BH(sock_net(sk), | |
2084 | LINUX_MIB_TCPLOSSPROBES); | |
2085 | return; | |
1da177e4 LT |
2086 | } |
2087 | ||
a762a980 DM |
2088 | /* Push out any pending frames which were held back due to |
2089 | * TCP_CORK or attempt at coalescing tiny packets. | |
2090 | * The socket must be locked by the caller. | |
2091 | */ | |
9e412ba7 IJ |
2092 | void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
2093 | int nonagle) | |
a762a980 | 2094 | { |
726e07a8 IJ |
2095 | /* If we are closed, the bytes will have to remain here. |
2096 | * In time closedown will finish, we empty the write queue and | |
2097 | * all will be happy. | |
2098 | */ | |
2099 | if (unlikely(sk->sk_state == TCP_CLOSE)) | |
2100 | return; | |
2101 | ||
99a1dec7 MG |
2102 | if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
2103 | sk_gfp_atomic(sk, GFP_ATOMIC))) | |
726e07a8 | 2104 | tcp_check_probe_timer(sk); |
a762a980 DM |
2105 | } |
2106 | ||
c1b4a7e6 DM |
2107 | /* Send _single_ skb sitting at the send head. This function requires |
2108 | * true push pending frames to setup probe timer etc. | |
2109 | */ | |
2110 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
2111 | { | |
fe067e8a | 2112 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
2113 | |
2114 | BUG_ON(!skb || skb->len < mss_now); | |
2115 | ||
d5dd9175 | 2116 | tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
c1b4a7e6 DM |
2117 | } |
2118 | ||
1da177e4 LT |
2119 | /* This function returns the amount that we can raise the |
2120 | * usable window based on the following constraints | |
e905a9ed | 2121 | * |
1da177e4 LT |
2122 | * 1. The window can never be shrunk once it is offered (RFC 793) |
2123 | * 2. We limit memory per socket | |
2124 | * | |
2125 | * RFC 1122: | |
2126 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
2127 | * RECV.NEXT + RCV.WIN fixed until: | |
2128 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
2129 | * | |
2130 | * i.e. don't raise the right edge of the window until you can raise | |
2131 | * it at least MSS bytes. | |
2132 | * | |
2133 | * Unfortunately, the recommended algorithm breaks header prediction, | |
2134 | * since header prediction assumes th->window stays fixed. | |
2135 | * | |
2136 | * Strictly speaking, keeping th->window fixed violates the receiver | |
2137 | * side SWS prevention criteria. The problem is that under this rule | |
2138 | * a stream of single byte packets will cause the right side of the | |
2139 | * window to always advance by a single byte. | |
e905a9ed | 2140 | * |
1da177e4 LT |
2141 | * Of course, if the sender implements sender side SWS prevention |
2142 | * then this will not be a problem. | |
e905a9ed | 2143 | * |
1da177e4 | 2144 | * BSD seems to make the following compromise: |
e905a9ed | 2145 | * |
1da177e4 LT |
2146 | * If the free space is less than the 1/4 of the maximum |
2147 | * space available and the free space is less than 1/2 mss, | |
2148 | * then set the window to 0. | |
2149 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
2150 | * Otherwise, just prevent the window from shrinking | |
2151 | * and from being larger than the largest representable value. | |
2152 | * | |
2153 | * This prevents incremental opening of the window in the regime | |
2154 | * where TCP is limited by the speed of the reader side taking | |
2155 | * data out of the TCP receive queue. It does nothing about | |
2156 | * those cases where the window is constrained on the sender side | |
2157 | * because the pipeline is full. | |
2158 | * | |
2159 | * BSD also seems to "accidentally" limit itself to windows that are a | |
2160 | * multiple of MSS, at least until the free space gets quite small. | |
2161 | * This would appear to be a side effect of the mbuf implementation. | |
2162 | * Combining these two algorithms results in the observed behavior | |
2163 | * of having a fixed window size at almost all times. | |
2164 | * | |
2165 | * Below we obtain similar behavior by forcing the offered window to | |
2166 | * a multiple of the mss when it is feasible to do so. | |
2167 | * | |
2168 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
2169 | * Regular options like TIMESTAMP are taken into account. | |
2170 | */ | |
2171 | u32 __tcp_select_window(struct sock *sk) | |
2172 | { | |
463c84b9 | 2173 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 2174 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 2175 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
2176 | * here. I don't know if the value based on our guesses |
2177 | * of peer's MSS is better for the performance. It's more correct | |
2178 | * but may be worse for the performance because of rcv_mss | |
2179 | * fluctuations. --SAW 1998/11/1 | |
2180 | */ | |
463c84b9 | 2181 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 LT |
2182 | int free_space = tcp_space(sk); |
2183 | int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); | |
2184 | int window; | |
2185 | ||
2186 | if (mss > full_space) | |
e905a9ed | 2187 | mss = full_space; |
1da177e4 | 2188 | |
b92edbe0 | 2189 | if (free_space < (full_space >> 1)) { |
463c84b9 | 2190 | icsk->icsk_ack.quick = 0; |
1da177e4 | 2191 | |
180d8cd9 | 2192 | if (sk_under_memory_pressure(sk)) |
056834d9 IJ |
2193 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, |
2194 | 4U * tp->advmss); | |
1da177e4 LT |
2195 | |
2196 | if (free_space < mss) | |
2197 | return 0; | |
2198 | } | |
2199 | ||
2200 | if (free_space > tp->rcv_ssthresh) | |
2201 | free_space = tp->rcv_ssthresh; | |
2202 | ||
2203 | /* Don't do rounding if we are using window scaling, since the | |
2204 | * scaled window will not line up with the MSS boundary anyway. | |
2205 | */ | |
2206 | window = tp->rcv_wnd; | |
2207 | if (tp->rx_opt.rcv_wscale) { | |
2208 | window = free_space; | |
2209 | ||
2210 | /* Advertise enough space so that it won't get scaled away. | |
2211 | * Import case: prevent zero window announcement if | |
2212 | * 1<<rcv_wscale > mss. | |
2213 | */ | |
2214 | if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) | |
2215 | window = (((window >> tp->rx_opt.rcv_wscale) + 1) | |
2216 | << tp->rx_opt.rcv_wscale); | |
2217 | } else { | |
2218 | /* Get the largest window that is a nice multiple of mss. | |
2219 | * Window clamp already applied above. | |
2220 | * If our current window offering is within 1 mss of the | |
2221 | * free space we just keep it. This prevents the divide | |
2222 | * and multiply from happening most of the time. | |
2223 | * We also don't do any window rounding when the free space | |
2224 | * is too small. | |
2225 | */ | |
2226 | if (window <= free_space - mss || window > free_space) | |
056834d9 | 2227 | window = (free_space / mss) * mss; |
84565070 | 2228 | else if (mss == full_space && |
b92edbe0 | 2229 | free_space > window + (full_space >> 1)) |
84565070 | 2230 | window = free_space; |
1da177e4 LT |
2231 | } |
2232 | ||
2233 | return window; | |
2234 | } | |
2235 | ||
4a17fc3a IJ |
2236 | /* Collapses two adjacent SKB's during retransmission. */ |
2237 | static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) | |
1da177e4 LT |
2238 | { |
2239 | struct tcp_sock *tp = tcp_sk(sk); | |
fe067e8a | 2240 | struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); |
058dc334 | 2241 | int skb_size, next_skb_size; |
1da177e4 | 2242 | |
058dc334 IJ |
2243 | skb_size = skb->len; |
2244 | next_skb_size = next_skb->len; | |
1da177e4 | 2245 | |
058dc334 | 2246 | BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
a6963a6b | 2247 | |
058dc334 | 2248 | tcp_highest_sack_combine(sk, next_skb, skb); |
1da177e4 | 2249 | |
058dc334 | 2250 | tcp_unlink_write_queue(next_skb, sk); |
1da177e4 | 2251 | |
058dc334 IJ |
2252 | skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), |
2253 | next_skb_size); | |
1da177e4 | 2254 | |
058dc334 IJ |
2255 | if (next_skb->ip_summed == CHECKSUM_PARTIAL) |
2256 | skb->ip_summed = CHECKSUM_PARTIAL; | |
1da177e4 | 2257 | |
058dc334 IJ |
2258 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
2259 | skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); | |
1da177e4 | 2260 | |
058dc334 IJ |
2261 | /* Update sequence range on original skb. */ |
2262 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1da177e4 | 2263 | |
e6c7d085 | 2264 | /* Merge over control information. This moves PSH/FIN etc. over */ |
4de075e0 | 2265 | TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
058dc334 IJ |
2266 | |
2267 | /* All done, get rid of second SKB and account for it so | |
2268 | * packet counting does not break. | |
2269 | */ | |
2270 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; | |
058dc334 IJ |
2271 | |
2272 | /* changed transmit queue under us so clear hints */ | |
ef9da47c IJ |
2273 | tcp_clear_retrans_hints_partial(tp); |
2274 | if (next_skb == tp->retransmit_skb_hint) | |
2275 | tp->retransmit_skb_hint = skb; | |
058dc334 | 2276 | |
797108d1 IJ |
2277 | tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
2278 | ||
058dc334 | 2279 | sk_wmem_free_skb(sk, next_skb); |
1da177e4 LT |
2280 | } |
2281 | ||
67edfef7 | 2282 | /* Check if coalescing SKBs is legal. */ |
a2a385d6 | 2283 | static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
4a17fc3a IJ |
2284 | { |
2285 | if (tcp_skb_pcount(skb) > 1) | |
a2a385d6 | 2286 | return false; |
4a17fc3a IJ |
2287 | /* TODO: SACK collapsing could be used to remove this condition */ |
2288 | if (skb_shinfo(skb)->nr_frags != 0) | |
a2a385d6 | 2289 | return false; |
4a17fc3a | 2290 | if (skb_cloned(skb)) |
a2a385d6 | 2291 | return false; |
4a17fc3a | 2292 | if (skb == tcp_send_head(sk)) |
a2a385d6 | 2293 | return false; |
4a17fc3a IJ |
2294 | /* Some heurestics for collapsing over SACK'd could be invented */ |
2295 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
a2a385d6 | 2296 | return false; |
4a17fc3a | 2297 | |
a2a385d6 | 2298 | return true; |
4a17fc3a IJ |
2299 | } |
2300 | ||
67edfef7 AK |
2301 | /* Collapse packets in the retransmit queue to make to create |
2302 | * less packets on the wire. This is only done on retransmission. | |
2303 | */ | |
4a17fc3a IJ |
2304 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
2305 | int space) | |
2306 | { | |
2307 | struct tcp_sock *tp = tcp_sk(sk); | |
2308 | struct sk_buff *skb = to, *tmp; | |
a2a385d6 | 2309 | bool first = true; |
4a17fc3a IJ |
2310 | |
2311 | if (!sysctl_tcp_retrans_collapse) | |
2312 | return; | |
4de075e0 | 2313 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
4a17fc3a IJ |
2314 | return; |
2315 | ||
2316 | tcp_for_write_queue_from_safe(skb, tmp, sk) { | |
2317 | if (!tcp_can_collapse(sk, skb)) | |
2318 | break; | |
2319 | ||
2320 | space -= skb->len; | |
2321 | ||
2322 | if (first) { | |
a2a385d6 | 2323 | first = false; |
4a17fc3a IJ |
2324 | continue; |
2325 | } | |
2326 | ||
2327 | if (space < 0) | |
2328 | break; | |
2329 | /* Punt if not enough space exists in the first SKB for | |
2330 | * the data in the second | |
2331 | */ | |
a21d4572 | 2332 | if (skb->len > skb_availroom(to)) |
4a17fc3a IJ |
2333 | break; |
2334 | ||
2335 | if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) | |
2336 | break; | |
2337 | ||
2338 | tcp_collapse_retrans(sk, to); | |
2339 | } | |
2340 | } | |
2341 | ||
1da177e4 LT |
2342 | /* This retransmits one SKB. Policy decisions and retransmit queue |
2343 | * state updates are done by the caller. Returns non-zero if an | |
2344 | * error occurred which prevented the send. | |
2345 | */ | |
93b174ad | 2346 | int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) |
1da177e4 LT |
2347 | { |
2348 | struct tcp_sock *tp = tcp_sk(sk); | |
5d424d5a | 2349 | struct inet_connection_sock *icsk = inet_csk(sk); |
7d227cd2 | 2350 | unsigned int cur_mss; |
c84a5711 | 2351 | int err; |
1da177e4 | 2352 | |
5d424d5a JH |
2353 | /* Inconslusive MTU probe */ |
2354 | if (icsk->icsk_mtup.probe_size) { | |
2355 | icsk->icsk_mtup.probe_size = 0; | |
2356 | } | |
2357 | ||
1da177e4 | 2358 | /* Do not sent more than we queued. 1/4 is reserved for possible |
caa20d9a | 2359 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 LT |
2360 | */ |
2361 | if (atomic_read(&sk->sk_wmem_alloc) > | |
2362 | min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) | |
2363 | return -EAGAIN; | |
2364 | ||
2365 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { | |
2366 | if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
2367 | BUG(); | |
1da177e4 LT |
2368 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
2369 | return -ENOMEM; | |
2370 | } | |
2371 | ||
7d227cd2 SS |
2372 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
2373 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
2374 | ||
0c54b85f | 2375 | cur_mss = tcp_current_mss(sk); |
7d227cd2 | 2376 | |
1da177e4 LT |
2377 | /* If receiver has shrunk his window, and skb is out of |
2378 | * new window, do not retransmit it. The exception is the | |
2379 | * case, when window is shrunk to zero. In this case | |
2380 | * our retransmit serves as a zero window probe. | |
2381 | */ | |
9d4fb27d JP |
2382 | if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && |
2383 | TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1da177e4 LT |
2384 | return -EAGAIN; |
2385 | ||
2386 | if (skb->len > cur_mss) { | |
846998ae | 2387 | if (tcp_fragment(sk, skb, cur_mss, cur_mss)) |
1da177e4 | 2388 | return -ENOMEM; /* We'll try again later. */ |
02276f3c | 2389 | } else { |
9eb9362e IJ |
2390 | int oldpcount = tcp_skb_pcount(skb); |
2391 | ||
2392 | if (unlikely(oldpcount > 1)) { | |
c52e2421 ED |
2393 | if (skb_unclone(skb, GFP_ATOMIC)) |
2394 | return -ENOMEM; | |
9eb9362e IJ |
2395 | tcp_init_tso_segs(sk, skb, cur_mss); |
2396 | tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); | |
2397 | } | |
1da177e4 LT |
2398 | } |
2399 | ||
4a17fc3a | 2400 | tcp_retrans_try_collapse(sk, skb, cur_mss); |
1da177e4 | 2401 | |
1da177e4 LT |
2402 | /* Make a copy, if the first transmission SKB clone we made |
2403 | * is still in somebody's hands, else make a clone. | |
2404 | */ | |
2405 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
1da177e4 | 2406 | |
50bceae9 TG |
2407 | /* make sure skb->data is aligned on arches that require it |
2408 | * and check if ack-trimming & collapsing extended the headroom | |
2409 | * beyond what csum_start can cover. | |
2410 | */ | |
2411 | if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || | |
2412 | skb_headroom(skb) >= 0xFFFF)) { | |
117632e6 ED |
2413 | struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, |
2414 | GFP_ATOMIC); | |
c84a5711 YC |
2415 | err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : |
2416 | -ENOBUFS; | |
117632e6 | 2417 | } else { |
c84a5711 | 2418 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
117632e6 | 2419 | } |
c84a5711 YC |
2420 | |
2421 | if (likely(!err)) | |
2422 | TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; | |
2423 | return err; | |
93b174ad YC |
2424 | } |
2425 | ||
2426 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) | |
2427 | { | |
2428 | struct tcp_sock *tp = tcp_sk(sk); | |
2429 | int err = __tcp_retransmit_skb(sk, skb); | |
1da177e4 LT |
2430 | |
2431 | if (err == 0) { | |
2432 | /* Update global TCP statistics. */ | |
81cc8a75 | 2433 | TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); |
1da177e4 LT |
2434 | |
2435 | tp->total_retrans++; | |
2436 | ||
2437 | #if FASTRETRANS_DEBUG > 0 | |
056834d9 | 2438 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
e87cc472 | 2439 | net_dbg_ratelimited("retrans_out leaked\n"); |
1da177e4 LT |
2440 | } |
2441 | #endif | |
b08d6cb2 IJ |
2442 | if (!tp->retrans_out) |
2443 | tp->lost_retrans_low = tp->snd_nxt; | |
1da177e4 LT |
2444 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; |
2445 | tp->retrans_out += tcp_skb_pcount(skb); | |
2446 | ||
2447 | /* Save stamp of the first retransmit. */ | |
2448 | if (!tp->retrans_stamp) | |
2449 | tp->retrans_stamp = TCP_SKB_CB(skb)->when; | |
2450 | ||
c24f691b | 2451 | tp->undo_retrans += tcp_skb_pcount(skb); |
1da177e4 LT |
2452 | |
2453 | /* snd_nxt is stored to detect loss of retransmitted segment, | |
2454 | * see tcp_input.c tcp_sacktag_write_queue(). | |
2455 | */ | |
2456 | TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; | |
24ab6bec YC |
2457 | } else { |
2458 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); | |
1da177e4 LT |
2459 | } |
2460 | return err; | |
2461 | } | |
2462 | ||
67edfef7 AK |
2463 | /* Check if we forward retransmits are possible in the current |
2464 | * window/congestion state. | |
2465 | */ | |
a2a385d6 | 2466 | static bool tcp_can_forward_retransmit(struct sock *sk) |
b5afe7bc IJ |
2467 | { |
2468 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
cf533ea5 | 2469 | const struct tcp_sock *tp = tcp_sk(sk); |
b5afe7bc IJ |
2470 | |
2471 | /* Forward retransmissions are possible only during Recovery. */ | |
2472 | if (icsk->icsk_ca_state != TCP_CA_Recovery) | |
a2a385d6 | 2473 | return false; |
b5afe7bc IJ |
2474 | |
2475 | /* No forward retransmissions in Reno are possible. */ | |
2476 | if (tcp_is_reno(tp)) | |
a2a385d6 | 2477 | return false; |
b5afe7bc IJ |
2478 | |
2479 | /* Yeah, we have to make difficult choice between forward transmission | |
2480 | * and retransmission... Both ways have their merits... | |
2481 | * | |
2482 | * For now we do not retransmit anything, while we have some new | |
2483 | * segments to send. In the other cases, follow rule 3 for | |
2484 | * NextSeg() specified in RFC3517. | |
2485 | */ | |
2486 | ||
2487 | if (tcp_may_send_now(sk)) | |
a2a385d6 | 2488 | return false; |
b5afe7bc | 2489 | |
a2a385d6 | 2490 | return true; |
b5afe7bc IJ |
2491 | } |
2492 | ||
1da177e4 LT |
2493 | /* This gets called after a retransmit timeout, and the initially |
2494 | * retransmitted data is acknowledged. It tries to continue | |
2495 | * resending the rest of the retransmit queue, until either | |
2496 | * we've sent it all or the congestion window limit is reached. | |
2497 | * If doing SACK, the first ACK which comes back for a timeout | |
2498 | * based retransmit packet might feed us FACK information again. | |
2499 | * If so, we use it to avoid unnecessarily retransmissions. | |
2500 | */ | |
2501 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
2502 | { | |
6687e988 | 2503 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2504 | struct tcp_sock *tp = tcp_sk(sk); |
2505 | struct sk_buff *skb; | |
0e1c54c2 | 2506 | struct sk_buff *hole = NULL; |
618d9f25 | 2507 | u32 last_lost; |
61eb55f4 | 2508 | int mib_idx; |
0e1c54c2 | 2509 | int fwd_rexmitting = 0; |
6a438bbe | 2510 | |
45e77d31 IJ |
2511 | if (!tp->packets_out) |
2512 | return; | |
2513 | ||
08ebd172 IJ |
2514 | if (!tp->lost_out) |
2515 | tp->retransmit_high = tp->snd_una; | |
2516 | ||
618d9f25 | 2517 | if (tp->retransmit_skb_hint) { |
6a438bbe | 2518 | skb = tp->retransmit_skb_hint; |
618d9f25 IJ |
2519 | last_lost = TCP_SKB_CB(skb)->end_seq; |
2520 | if (after(last_lost, tp->retransmit_high)) | |
2521 | last_lost = tp->retransmit_high; | |
2522 | } else { | |
fe067e8a | 2523 | skb = tcp_write_queue_head(sk); |
618d9f25 IJ |
2524 | last_lost = tp->snd_una; |
2525 | } | |
1da177e4 | 2526 | |
08ebd172 IJ |
2527 | tcp_for_write_queue_from(skb, sk) { |
2528 | __u8 sacked = TCP_SKB_CB(skb)->sacked; | |
1da177e4 | 2529 | |
08ebd172 IJ |
2530 | if (skb == tcp_send_head(sk)) |
2531 | break; | |
2532 | /* we could do better than to assign each time */ | |
0e1c54c2 IJ |
2533 | if (hole == NULL) |
2534 | tp->retransmit_skb_hint = skb; | |
08ebd172 IJ |
2535 | |
2536 | /* Assume this retransmit will generate | |
2537 | * only one packet for congestion window | |
2538 | * calculation purposes. This works because | |
2539 | * tcp_retransmit_skb() will chop up the | |
2540 | * packet to be MSS sized and all the | |
2541 | * packet counting works out. | |
2542 | */ | |
2543 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
2544 | return; | |
1da177e4 | 2545 | |
0e1c54c2 IJ |
2546 | if (fwd_rexmitting) { |
2547 | begin_fwd: | |
2548 | if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) | |
2549 | break; | |
2550 | mib_idx = LINUX_MIB_TCPFORWARDRETRANS; | |
6a438bbe | 2551 | |
0e1c54c2 | 2552 | } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { |
618d9f25 | 2553 | tp->retransmit_high = last_lost; |
0e1c54c2 IJ |
2554 | if (!tcp_can_forward_retransmit(sk)) |
2555 | break; | |
2556 | /* Backtrack if necessary to non-L'ed skb */ | |
2557 | if (hole != NULL) { | |
2558 | skb = hole; | |
2559 | hole = NULL; | |
2560 | } | |
2561 | fwd_rexmitting = 1; | |
2562 | goto begin_fwd; | |
1da177e4 | 2563 | |
0e1c54c2 | 2564 | } else if (!(sacked & TCPCB_LOST)) { |
ac11ba75 | 2565 | if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
0e1c54c2 IJ |
2566 | hole = skb; |
2567 | continue; | |
1da177e4 | 2568 | |
0e1c54c2 | 2569 | } else { |
618d9f25 | 2570 | last_lost = TCP_SKB_CB(skb)->end_seq; |
0e1c54c2 IJ |
2571 | if (icsk->icsk_ca_state != TCP_CA_Loss) |
2572 | mib_idx = LINUX_MIB_TCPFASTRETRANS; | |
2573 | else | |
2574 | mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; | |
2575 | } | |
1da177e4 | 2576 | |
0e1c54c2 | 2577 | if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
1da177e4 LT |
2578 | continue; |
2579 | ||
24ab6bec | 2580 | if (tcp_retransmit_skb(sk, skb)) |
0e1c54c2 | 2581 | return; |
24ab6bec | 2582 | |
0e1c54c2 | 2583 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 | 2584 | |
684bad11 | 2585 | if (tcp_in_cwnd_reduction(sk)) |
a262f0cd ND |
2586 | tp->prr_out += tcp_skb_pcount(skb); |
2587 | ||
fe067e8a | 2588 | if (skb == tcp_write_queue_head(sk)) |
3f421baa ACM |
2589 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
2590 | inet_csk(sk)->icsk_rto, | |
2591 | TCP_RTO_MAX); | |
1da177e4 LT |
2592 | } |
2593 | } | |
2594 | ||
1da177e4 LT |
2595 | /* Send a fin. The caller locks the socket for us. This cannot be |
2596 | * allowed to fail queueing a FIN frame under any circumstances. | |
2597 | */ | |
2598 | void tcp_send_fin(struct sock *sk) | |
2599 | { | |
e905a9ed | 2600 | struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 2601 | struct sk_buff *skb = tcp_write_queue_tail(sk); |
1da177e4 | 2602 | int mss_now; |
e905a9ed | 2603 | |
1da177e4 LT |
2604 | /* Optimization, tack on the FIN if we have a queue of |
2605 | * unsent frames. But be careful about outgoing SACKS | |
2606 | * and IP options. | |
2607 | */ | |
0c54b85f | 2608 | mss_now = tcp_current_mss(sk); |
1da177e4 | 2609 | |
fe067e8a | 2610 | if (tcp_send_head(sk) != NULL) { |
4de075e0 | 2611 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; |
1da177e4 LT |
2612 | TCP_SKB_CB(skb)->end_seq++; |
2613 | tp->write_seq++; | |
2614 | } else { | |
2615 | /* Socket is locked, keep trying until memory is available. */ | |
2616 | for (;;) { | |
aa133076 WF |
2617 | skb = alloc_skb_fclone(MAX_TCP_HEADER, |
2618 | sk->sk_allocation); | |
1da177e4 LT |
2619 | if (skb) |
2620 | break; | |
2621 | yield(); | |
2622 | } | |
2623 | ||
2624 | /* Reserve space for headers and prepare control bits. */ | |
2625 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 | 2626 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
e870a8ef | 2627 | tcp_init_nondata_skb(skb, tp->write_seq, |
a3433f35 | 2628 | TCPHDR_ACK | TCPHDR_FIN); |
1da177e4 LT |
2629 | tcp_queue_skb(sk, skb); |
2630 | } | |
9e412ba7 | 2631 | __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); |
1da177e4 LT |
2632 | } |
2633 | ||
2634 | /* We get here when a process closes a file descriptor (either due to | |
2635 | * an explicit close() or as a byproduct of exit()'ing) and there | |
2636 | * was unread data in the receive queue. This behavior is recommended | |
65bb723c | 2637 | * by RFC 2525, section 2.17. -DaveM |
1da177e4 | 2638 | */ |
dd0fc66f | 2639 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 | 2640 | { |
1da177e4 LT |
2641 | struct sk_buff *skb; |
2642 | ||
2643 | /* NOTE: No TCP options attached and we never retransmit this. */ | |
2644 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
2645 | if (!skb) { | |
4e673444 | 2646 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
1da177e4 LT |
2647 | return; |
2648 | } | |
2649 | ||
2650 | /* Reserve space for headers and prepare control bits. */ | |
2651 | skb_reserve(skb, MAX_TCP_HEADER); | |
e870a8ef | 2652 | tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
a3433f35 | 2653 | TCPHDR_ACK | TCPHDR_RST); |
1da177e4 | 2654 | /* Send it off. */ |
1da177e4 | 2655 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
dfb4b9dc | 2656 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
4e673444 | 2657 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
26af65cb | 2658 | |
81cc8a75 | 2659 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
1da177e4 LT |
2660 | } |
2661 | ||
67edfef7 AK |
2662 | /* Send a crossed SYN-ACK during socket establishment. |
2663 | * WARNING: This routine must only be called when we have already sent | |
1da177e4 LT |
2664 | * a SYN packet that crossed the incoming SYN that caused this routine |
2665 | * to get called. If this assumption fails then the initial rcv_wnd | |
2666 | * and rcv_wscale values will not be correct. | |
2667 | */ | |
2668 | int tcp_send_synack(struct sock *sk) | |
2669 | { | |
056834d9 | 2670 | struct sk_buff *skb; |
1da177e4 | 2671 | |
fe067e8a | 2672 | skb = tcp_write_queue_head(sk); |
4de075e0 | 2673 | if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
91df42be | 2674 | pr_debug("%s: wrong queue state\n", __func__); |
1da177e4 LT |
2675 | return -EFAULT; |
2676 | } | |
4de075e0 | 2677 | if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
1da177e4 LT |
2678 | if (skb_cloned(skb)) { |
2679 | struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); | |
2680 | if (nskb == NULL) | |
2681 | return -ENOMEM; | |
fe067e8a | 2682 | tcp_unlink_write_queue(skb, sk); |
1da177e4 | 2683 | skb_header_release(nskb); |
fe067e8a | 2684 | __tcp_add_write_queue_head(sk, nskb); |
3ab224be HA |
2685 | sk_wmem_free_skb(sk, skb); |
2686 | sk->sk_wmem_queued += nskb->truesize; | |
2687 | sk_mem_charge(sk, nskb->truesize); | |
1da177e4 LT |
2688 | skb = nskb; |
2689 | } | |
2690 | ||
4de075e0 | 2691 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
1da177e4 LT |
2692 | TCP_ECN_send_synack(tcp_sk(sk), skb); |
2693 | } | |
2694 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2695 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2696 | } |
2697 | ||
4aea39c1 ED |
2698 | /** |
2699 | * tcp_make_synack - Prepare a SYN-ACK. | |
2700 | * sk: listener socket | |
2701 | * dst: dst entry attached to the SYNACK | |
2702 | * req: request_sock pointer | |
4aea39c1 ED |
2703 | * |
2704 | * Allocate one skb and build a SYNACK packet. | |
2705 | * @dst is consumed : Caller should not use it again. | |
2706 | */ | |
056834d9 | 2707 | struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, |
e6b4d113 | 2708 | struct request_sock *req, |
8336886f | 2709 | struct tcp_fastopen_cookie *foc) |
1da177e4 | 2710 | { |
bd0388ae | 2711 | struct tcp_out_options opts; |
2e6599cb | 2712 | struct inet_request_sock *ireq = inet_rsk(req); |
1da177e4 LT |
2713 | struct tcp_sock *tp = tcp_sk(sk); |
2714 | struct tcphdr *th; | |
1da177e4 | 2715 | struct sk_buff *skb; |
cfb6eeb4 | 2716 | struct tcp_md5sig_key *md5; |
bd0388ae | 2717 | int tcp_header_size; |
f5fff5dc | 2718 | int mss; |
1da177e4 | 2719 | |
eb8895de | 2720 | skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); |
4aea39c1 ED |
2721 | if (unlikely(!skb)) { |
2722 | dst_release(dst); | |
1da177e4 | 2723 | return NULL; |
4aea39c1 | 2724 | } |
1da177e4 LT |
2725 | /* Reserve space for headers. */ |
2726 | skb_reserve(skb, MAX_TCP_HEADER); | |
2727 | ||
4aea39c1 | 2728 | skb_dst_set(skb, dst); |
ca10b9e9 | 2729 | security_skb_owned_by(skb, sk); |
1da177e4 | 2730 | |
0dbaee3b | 2731 | mss = dst_metric_advmss(dst); |
f5fff5dc TQ |
2732 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) |
2733 | mss = tp->rx_opt.user_mss; | |
2734 | ||
33ad798c AL |
2735 | if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ |
2736 | __u8 rcv_wscale; | |
2737 | /* Set this up on the first call only */ | |
2738 | req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); | |
e88c64f0 HPP |
2739 | |
2740 | /* limit the window selection if the user enforce a smaller rx buffer */ | |
2741 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
2742 | (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0)) | |
2743 | req->window_clamp = tcp_full_space(sk); | |
2744 | ||
33ad798c AL |
2745 | /* tcp_full_space because it is guaranteed to be the first packet */ |
2746 | tcp_select_initial_window(tcp_full_space(sk), | |
f5fff5dc | 2747 | mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
33ad798c AL |
2748 | &req->rcv_wnd, |
2749 | &req->window_clamp, | |
2750 | ireq->wscale_ok, | |
31d12926 | 2751 | &rcv_wscale, |
2752 | dst_metric(dst, RTAX_INITRWND)); | |
33ad798c AL |
2753 | ireq->rcv_wscale = rcv_wscale; |
2754 | } | |
2755 | ||
2756 | memset(&opts, 0, sizeof(opts)); | |
8b5f12d0 FW |
2757 | #ifdef CONFIG_SYN_COOKIES |
2758 | if (unlikely(req->cookie_ts)) | |
2759 | TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); | |
2760 | else | |
2761 | #endif | |
33ad798c | 2762 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
1a2c6181 CP |
2763 | tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5, |
2764 | foc) + sizeof(*th); | |
cfb6eeb4 | 2765 | |
aa8223c7 ACM |
2766 | skb_push(skb, tcp_header_size); |
2767 | skb_reset_transport_header(skb); | |
1da177e4 | 2768 | |
aa8223c7 | 2769 | th = tcp_hdr(skb); |
1da177e4 LT |
2770 | memset(th, 0, sizeof(struct tcphdr)); |
2771 | th->syn = 1; | |
2772 | th->ack = 1; | |
1da177e4 | 2773 | TCP_ECN_make_synack(req, th); |
b44084c2 | 2774 | th->source = htons(ireq->ir_num); |
634fb979 | 2775 | th->dest = ireq->ir_rmt_port; |
e870a8ef IJ |
2776 | /* Setting of flags are superfluous here for callers (and ECE is |
2777 | * not even correctly set) | |
2778 | */ | |
2779 | tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, | |
a3433f35 | 2780 | TCPHDR_SYN | TCPHDR_ACK); |
4957faad | 2781 | |
1da177e4 | 2782 | th->seq = htonl(TCP_SKB_CB(skb)->seq); |
8336886f JC |
2783 | /* XXX data is queued and acked as is. No buffer/window check */ |
2784 | th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); | |
1da177e4 LT |
2785 | |
2786 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
600ff0c2 | 2787 | th->window = htons(min(req->rcv_wnd, 65535U)); |
bd0388ae | 2788 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
1da177e4 | 2789 | th->doff = (tcp_header_size >> 2); |
aa2ea058 | 2790 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb)); |
cfb6eeb4 YH |
2791 | |
2792 | #ifdef CONFIG_TCP_MD5SIG | |
2793 | /* Okay, we have all we need - do the md5 hash if needed */ | |
2794 | if (md5) { | |
bd0388ae | 2795 | tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 2796 | md5, NULL, req, skb); |
cfb6eeb4 YH |
2797 | } |
2798 | #endif | |
2799 | ||
1da177e4 LT |
2800 | return skb; |
2801 | } | |
4bc2f18b | 2802 | EXPORT_SYMBOL(tcp_make_synack); |
1da177e4 | 2803 | |
67edfef7 | 2804 | /* Do all connect socket setups that can be done AF independent. */ |
f7e56a76 | 2805 | static void tcp_connect_init(struct sock *sk) |
1da177e4 | 2806 | { |
cf533ea5 | 2807 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
2808 | struct tcp_sock *tp = tcp_sk(sk); |
2809 | __u8 rcv_wscale; | |
2810 | ||
2811 | /* We'll fix this up when we get a response from the other end. | |
2812 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
2813 | */ | |
2814 | tp->tcp_header_len = sizeof(struct tcphdr) + | |
bb5b7c11 | 2815 | (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); |
1da177e4 | 2816 | |
cfb6eeb4 YH |
2817 | #ifdef CONFIG_TCP_MD5SIG |
2818 | if (tp->af_specific->md5_lookup(sk, sk) != NULL) | |
2819 | tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; | |
2820 | #endif | |
2821 | ||
1da177e4 LT |
2822 | /* If user gave his TCP_MAXSEG, record it to clamp */ |
2823 | if (tp->rx_opt.user_mss) | |
2824 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
2825 | tp->max_window = 0; | |
5d424d5a | 2826 | tcp_mtup_init(sk); |
1da177e4 LT |
2827 | tcp_sync_mss(sk, dst_mtu(dst)); |
2828 | ||
2829 | if (!tp->window_clamp) | |
2830 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
0dbaee3b | 2831 | tp->advmss = dst_metric_advmss(dst); |
f5fff5dc TQ |
2832 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) |
2833 | tp->advmss = tp->rx_opt.user_mss; | |
2834 | ||
1da177e4 | 2835 | tcp_initialize_rcv_mss(sk); |
1da177e4 | 2836 | |
e88c64f0 HPP |
2837 | /* limit the window selection if the user enforce a smaller rx buffer */ |
2838 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
2839 | (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) | |
2840 | tp->window_clamp = tcp_full_space(sk); | |
2841 | ||
1da177e4 LT |
2842 | tcp_select_initial_window(tcp_full_space(sk), |
2843 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), | |
2844 | &tp->rcv_wnd, | |
2845 | &tp->window_clamp, | |
bb5b7c11 | 2846 | sysctl_tcp_window_scaling, |
31d12926 | 2847 | &rcv_wscale, |
2848 | dst_metric(dst, RTAX_INITRWND)); | |
1da177e4 LT |
2849 | |
2850 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
2851 | tp->rcv_ssthresh = tp->rcv_wnd; | |
2852 | ||
2853 | sk->sk_err = 0; | |
2854 | sock_reset_flag(sk, SOCK_DONE); | |
2855 | tp->snd_wnd = 0; | |
ee7537b6 | 2856 | tcp_init_wl(tp, 0); |
1da177e4 LT |
2857 | tp->snd_una = tp->write_seq; |
2858 | tp->snd_sml = tp->write_seq; | |
33f5f57e | 2859 | tp->snd_up = tp->write_seq; |
370816ae | 2860 | tp->snd_nxt = tp->write_seq; |
ee995283 PE |
2861 | |
2862 | if (likely(!tp->repair)) | |
2863 | tp->rcv_nxt = 0; | |
c7781a6e AV |
2864 | else |
2865 | tp->rcv_tstamp = tcp_time_stamp; | |
ee995283 PE |
2866 | tp->rcv_wup = tp->rcv_nxt; |
2867 | tp->copied_seq = tp->rcv_nxt; | |
1da177e4 | 2868 | |
463c84b9 ACM |
2869 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
2870 | inet_csk(sk)->icsk_retransmits = 0; | |
1da177e4 LT |
2871 | tcp_clear_retrans(tp); |
2872 | } | |
2873 | ||
783237e8 YC |
2874 | static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
2875 | { | |
2876 | struct tcp_sock *tp = tcp_sk(sk); | |
2877 | struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); | |
2878 | ||
2879 | tcb->end_seq += skb->len; | |
2880 | skb_header_release(skb); | |
2881 | __tcp_add_write_queue_tail(sk, skb); | |
2882 | sk->sk_wmem_queued += skb->truesize; | |
2883 | sk_mem_charge(sk, skb->truesize); | |
2884 | tp->write_seq = tcb->end_seq; | |
2885 | tp->packets_out += tcp_skb_pcount(skb); | |
2886 | } | |
2887 | ||
2888 | /* Build and send a SYN with data and (cached) Fast Open cookie. However, | |
2889 | * queue a data-only packet after the regular SYN, such that regular SYNs | |
2890 | * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges | |
2891 | * only the SYN sequence, the data are retransmitted in the first ACK. | |
2892 | * If cookie is not cached or other error occurs, falls back to send a | |
2893 | * regular SYN with Fast Open cookie request option. | |
2894 | */ | |
2895 | static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) | |
2896 | { | |
2897 | struct tcp_sock *tp = tcp_sk(sk); | |
2898 | struct tcp_fastopen_request *fo = tp->fastopen_req; | |
aab48743 | 2899 | int syn_loss = 0, space, i, err = 0, iovlen = fo->data->msg_iovlen; |
783237e8 | 2900 | struct sk_buff *syn_data = NULL, *data; |
aab48743 YC |
2901 | unsigned long last_syn_loss = 0; |
2902 | ||
67da22d2 | 2903 | tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
aab48743 YC |
2904 | tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, |
2905 | &syn_loss, &last_syn_loss); | |
2906 | /* Recurring FO SYN losses: revert to regular handshake temporarily */ | |
2907 | if (syn_loss > 1 && | |
2908 | time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { | |
2909 | fo->cookie.len = -1; | |
2910 | goto fallback; | |
2911 | } | |
783237e8 | 2912 | |
67da22d2 YC |
2913 | if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) |
2914 | fo->cookie.len = -1; | |
2915 | else if (fo->cookie.len <= 0) | |
783237e8 YC |
2916 | goto fallback; |
2917 | ||
2918 | /* MSS for SYN-data is based on cached MSS and bounded by PMTU and | |
2919 | * user-MSS. Reserve maximum option space for middleboxes that add | |
2920 | * private TCP options. The cost is reduced data space in SYN :( | |
2921 | */ | |
2922 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) | |
2923 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
1b63edd6 | 2924 | space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - |
783237e8 YC |
2925 | MAX_TCP_OPTION_SPACE; |
2926 | ||
f5ddcbbb ED |
2927 | space = min_t(size_t, space, fo->size); |
2928 | ||
2929 | /* limit to order-0 allocations */ | |
2930 | space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); | |
2931 | ||
2932 | syn_data = skb_copy_expand(syn, MAX_TCP_HEADER, space, | |
783237e8 YC |
2933 | sk->sk_allocation); |
2934 | if (syn_data == NULL) | |
2935 | goto fallback; | |
2936 | ||
2937 | for (i = 0; i < iovlen && syn_data->len < space; ++i) { | |
2938 | struct iovec *iov = &fo->data->msg_iov[i]; | |
2939 | unsigned char __user *from = iov->iov_base; | |
2940 | int len = iov->iov_len; | |
2941 | ||
2942 | if (syn_data->len + len > space) | |
2943 | len = space - syn_data->len; | |
2944 | else if (i + 1 == iovlen) | |
2945 | /* No more data pending in inet_wait_for_connect() */ | |
2946 | fo->data = NULL; | |
2947 | ||
2948 | if (skb_add_data(syn_data, from, len)) | |
2949 | goto fallback; | |
2950 | } | |
2951 | ||
2952 | /* Queue a data-only packet after the regular SYN for retransmission */ | |
2953 | data = pskb_copy(syn_data, sk->sk_allocation); | |
2954 | if (data == NULL) | |
2955 | goto fallback; | |
2956 | TCP_SKB_CB(data)->seq++; | |
2957 | TCP_SKB_CB(data)->tcp_flags &= ~TCPHDR_SYN; | |
2958 | TCP_SKB_CB(data)->tcp_flags = (TCPHDR_ACK|TCPHDR_PSH); | |
2959 | tcp_connect_queue_skb(sk, data); | |
2960 | fo->copied = data->len; | |
2961 | ||
2962 | if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) { | |
67da22d2 | 2963 | tp->syn_data = (fo->copied > 0); |
783237e8 YC |
2964 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVE); |
2965 | goto done; | |
2966 | } | |
2967 | syn_data = NULL; | |
2968 | ||
2969 | fallback: | |
2970 | /* Send a regular SYN with Fast Open cookie request option */ | |
2971 | if (fo->cookie.len > 0) | |
2972 | fo->cookie.len = 0; | |
2973 | err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); | |
2974 | if (err) | |
2975 | tp->syn_fastopen = 0; | |
2976 | kfree_skb(syn_data); | |
2977 | done: | |
2978 | fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ | |
2979 | return err; | |
2980 | } | |
2981 | ||
67edfef7 | 2982 | /* Build a SYN and send it off. */ |
1da177e4 LT |
2983 | int tcp_connect(struct sock *sk) |
2984 | { | |
2985 | struct tcp_sock *tp = tcp_sk(sk); | |
2986 | struct sk_buff *buff; | |
ee586811 | 2987 | int err; |
1da177e4 LT |
2988 | |
2989 | tcp_connect_init(sk); | |
2990 | ||
2b916477 AV |
2991 | if (unlikely(tp->repair)) { |
2992 | tcp_finish_connect(sk, NULL); | |
2993 | return 0; | |
2994 | } | |
2995 | ||
d179cd12 | 2996 | buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); |
1da177e4 LT |
2997 | if (unlikely(buff == NULL)) |
2998 | return -ENOBUFS; | |
2999 | ||
3000 | /* Reserve space for headers. */ | |
3001 | skb_reserve(buff, MAX_TCP_HEADER); | |
3002 | ||
a3433f35 | 3003 | tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
783237e8 YC |
3004 | tp->retrans_stamp = TCP_SKB_CB(buff)->when = tcp_time_stamp; |
3005 | tcp_connect_queue_skb(sk, buff); | |
e870a8ef | 3006 | TCP_ECN_send_syn(sk, buff); |
1da177e4 | 3007 | |
783237e8 YC |
3008 | /* Send off SYN; include data in Fast Open. */ |
3009 | err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : | |
3010 | tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); | |
ee586811 EP |
3011 | if (err == -ECONNREFUSED) |
3012 | return err; | |
bd37a088 WY |
3013 | |
3014 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
3015 | * in order to make this packet get counted in tcpOutSegs. | |
3016 | */ | |
3017 | tp->snd_nxt = tp->write_seq; | |
3018 | tp->pushed_seq = tp->write_seq; | |
81cc8a75 | 3019 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
1da177e4 LT |
3020 | |
3021 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
3022 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3023 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
3024 | return 0; |
3025 | } | |
4bc2f18b | 3026 | EXPORT_SYMBOL(tcp_connect); |
1da177e4 LT |
3027 | |
3028 | /* Send out a delayed ack, the caller does the policy checking | |
3029 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
3030 | * for details. | |
3031 | */ | |
3032 | void tcp_send_delayed_ack(struct sock *sk) | |
3033 | { | |
463c84b9 ACM |
3034 | struct inet_connection_sock *icsk = inet_csk(sk); |
3035 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
3036 | unsigned long timeout; |
3037 | ||
3038 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 3039 | const struct tcp_sock *tp = tcp_sk(sk); |
056834d9 | 3040 | int max_ato = HZ / 2; |
1da177e4 | 3041 | |
056834d9 IJ |
3042 | if (icsk->icsk_ack.pingpong || |
3043 | (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) | |
1da177e4 LT |
3044 | max_ato = TCP_DELACK_MAX; |
3045 | ||
3046 | /* Slow path, intersegment interval is "high". */ | |
3047 | ||
3048 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 3049 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
3050 | * directly. |
3051 | */ | |
3052 | if (tp->srtt) { | |
056834d9 | 3053 | int rtt = max(tp->srtt >> 3, TCP_DELACK_MIN); |
1da177e4 LT |
3054 | |
3055 | if (rtt < max_ato) | |
3056 | max_ato = rtt; | |
3057 | } | |
3058 | ||
3059 | ato = min(ato, max_ato); | |
3060 | } | |
3061 | ||
3062 | /* Stay within the limit we were given */ | |
3063 | timeout = jiffies + ato; | |
3064 | ||
3065 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 3066 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
3067 | /* If delack timer was blocked or is about to expire, |
3068 | * send ACK now. | |
3069 | */ | |
463c84b9 ACM |
3070 | if (icsk->icsk_ack.blocked || |
3071 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
3072 | tcp_send_ack(sk); |
3073 | return; | |
3074 | } | |
3075 | ||
463c84b9 ACM |
3076 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
3077 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 3078 | } |
463c84b9 ACM |
3079 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
3080 | icsk->icsk_ack.timeout = timeout; | |
3081 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
3082 | } |
3083 | ||
3084 | /* This routine sends an ack and also updates the window. */ | |
3085 | void tcp_send_ack(struct sock *sk) | |
3086 | { | |
058dc334 | 3087 | struct sk_buff *buff; |
1da177e4 | 3088 | |
058dc334 IJ |
3089 | /* If we have been reset, we may not send again. */ |
3090 | if (sk->sk_state == TCP_CLOSE) | |
3091 | return; | |
1da177e4 | 3092 | |
058dc334 IJ |
3093 | /* We are not putting this on the write queue, so |
3094 | * tcp_transmit_skb() will set the ownership to this | |
3095 | * sock. | |
3096 | */ | |
99a1dec7 | 3097 | buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); |
058dc334 IJ |
3098 | if (buff == NULL) { |
3099 | inet_csk_schedule_ack(sk); | |
3100 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3101 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, | |
3102 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
3103 | return; | |
1da177e4 | 3104 | } |
058dc334 IJ |
3105 | |
3106 | /* Reserve space for headers and prepare control bits. */ | |
3107 | skb_reserve(buff, MAX_TCP_HEADER); | |
a3433f35 | 3108 | tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
058dc334 IJ |
3109 | |
3110 | /* Send it off, this clears delayed acks for us. */ | |
058dc334 | 3111 | TCP_SKB_CB(buff)->when = tcp_time_stamp; |
99a1dec7 | 3112 | tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); |
1da177e4 LT |
3113 | } |
3114 | ||
3115 | /* This routine sends a packet with an out of date sequence | |
3116 | * number. It assumes the other end will try to ack it. | |
3117 | * | |
3118 | * Question: what should we make while urgent mode? | |
3119 | * 4.4BSD forces sending single byte of data. We cannot send | |
3120 | * out of window data, because we have SND.NXT==SND.MAX... | |
3121 | * | |
3122 | * Current solution: to send TWO zero-length segments in urgent mode: | |
3123 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
3124 | * out-of-date with SND.UNA-1 to probe window. | |
3125 | */ | |
3126 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent) | |
3127 | { | |
3128 | struct tcp_sock *tp = tcp_sk(sk); | |
3129 | struct sk_buff *skb; | |
3130 | ||
3131 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
99a1dec7 | 3132 | skb = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); |
e905a9ed | 3133 | if (skb == NULL) |
1da177e4 LT |
3134 | return -1; |
3135 | ||
3136 | /* Reserve space for headers and set control bits. */ | |
3137 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 LT |
3138 | /* Use a previous sequence. This should cause the other |
3139 | * end to send an ack. Don't queue or clone SKB, just | |
3140 | * send it. | |
3141 | */ | |
a3433f35 | 3142 | tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
1da177e4 | 3143 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
dfb4b9dc | 3144 | return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); |
1da177e4 LT |
3145 | } |
3146 | ||
ee995283 PE |
3147 | void tcp_send_window_probe(struct sock *sk) |
3148 | { | |
3149 | if (sk->sk_state == TCP_ESTABLISHED) { | |
3150 | tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; | |
3151 | tcp_xmit_probe_skb(sk, 0); | |
3152 | } | |
3153 | } | |
3154 | ||
67edfef7 | 3155 | /* Initiate keepalive or window probe from timer. */ |
1da177e4 LT |
3156 | int tcp_write_wakeup(struct sock *sk) |
3157 | { | |
058dc334 IJ |
3158 | struct tcp_sock *tp = tcp_sk(sk); |
3159 | struct sk_buff *skb; | |
1da177e4 | 3160 | |
058dc334 IJ |
3161 | if (sk->sk_state == TCP_CLOSE) |
3162 | return -1; | |
3163 | ||
3164 | if ((skb = tcp_send_head(sk)) != NULL && | |
3165 | before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { | |
3166 | int err; | |
0c54b85f | 3167 | unsigned int mss = tcp_current_mss(sk); |
058dc334 IJ |
3168 | unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
3169 | ||
3170 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
3171 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
3172 | ||
3173 | /* We are probing the opening of a window | |
3174 | * but the window size is != 0 | |
3175 | * must have been a result SWS avoidance ( sender ) | |
3176 | */ | |
3177 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
3178 | skb->len > mss) { | |
3179 | seg_size = min(seg_size, mss); | |
4de075e0 | 3180 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3181 | if (tcp_fragment(sk, skb, seg_size, mss)) |
3182 | return -1; | |
3183 | } else if (!tcp_skb_pcount(skb)) | |
3184 | tcp_set_skb_tso_segs(sk, skb, mss); | |
3185 | ||
4de075e0 | 3186 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3187 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
3188 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); | |
3189 | if (!err) | |
3190 | tcp_event_new_data_sent(sk, skb); | |
3191 | return err; | |
3192 | } else { | |
33f5f57e | 3193 | if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
058dc334 IJ |
3194 | tcp_xmit_probe_skb(sk, 1); |
3195 | return tcp_xmit_probe_skb(sk, 0); | |
1da177e4 | 3196 | } |
1da177e4 LT |
3197 | } |
3198 | ||
3199 | /* A window probe timeout has occurred. If window is not closed send | |
3200 | * a partial packet else a zero probe. | |
3201 | */ | |
3202 | void tcp_send_probe0(struct sock *sk) | |
3203 | { | |
463c84b9 | 3204 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
3205 | struct tcp_sock *tp = tcp_sk(sk); |
3206 | int err; | |
3207 | ||
3208 | err = tcp_write_wakeup(sk); | |
3209 | ||
fe067e8a | 3210 | if (tp->packets_out || !tcp_send_head(sk)) { |
1da177e4 | 3211 | /* Cancel probe timer, if it is not required. */ |
6687e988 | 3212 | icsk->icsk_probes_out = 0; |
463c84b9 | 3213 | icsk->icsk_backoff = 0; |
1da177e4 LT |
3214 | return; |
3215 | } | |
3216 | ||
3217 | if (err <= 0) { | |
463c84b9 ACM |
3218 | if (icsk->icsk_backoff < sysctl_tcp_retries2) |
3219 | icsk->icsk_backoff++; | |
6687e988 | 3220 | icsk->icsk_probes_out++; |
e905a9ed | 3221 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
3f421baa ACM |
3222 | min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), |
3223 | TCP_RTO_MAX); | |
1da177e4 LT |
3224 | } else { |
3225 | /* If packet was not sent due to local congestion, | |
6687e988 | 3226 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
3227 | * Let local senders to fight for local resources. |
3228 | * | |
3229 | * Use accumulated backoff yet. | |
3230 | */ | |
6687e988 ACM |
3231 | if (!icsk->icsk_probes_out) |
3232 | icsk->icsk_probes_out = 1; | |
e905a9ed | 3233 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
463c84b9 | 3234 | min(icsk->icsk_rto << icsk->icsk_backoff, |
3f421baa ACM |
3235 | TCP_RESOURCE_PROBE_INTERVAL), |
3236 | TCP_RTO_MAX); | |
1da177e4 LT |
3237 | } |
3238 | } |