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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> |
60e2a778 | 44 | #include <linux/static_key.h> |
1da177e4 | 45 | |
e086101b | 46 | #include <trace/events/tcp.h> |
35089bb2 | 47 | |
9799ccb0 ED |
48 | /* Refresh clocks of a TCP socket, |
49 | * ensuring monotically increasing values. | |
50 | */ | |
51 | void tcp_mstamp_refresh(struct tcp_sock *tp) | |
52 | { | |
53 | u64 val = tcp_clock_ns(); | |
54 | ||
55 | /* departure time for next data packet */ | |
56 | if (val > tp->tcp_wstamp_ns) | |
57 | tp->tcp_wstamp_ns = val; | |
58 | ||
59 | val = div_u64(val, NSEC_PER_USEC); | |
60 | if (val > tp->tcp_mstamp) | |
61 | tp->tcp_mstamp = val; | |
62 | } | |
63 | ||
46d3ceab ED |
64 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
65 | int push_one, gfp_t gfp); | |
519855c5 | 66 | |
67edfef7 | 67 | /* Account for new data that has been sent to the network. */ |
75c119af | 68 | static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) |
1da177e4 | 69 | { |
6ba8a3b1 | 70 | struct inet_connection_sock *icsk = inet_csk(sk); |
9e412ba7 | 71 | struct tcp_sock *tp = tcp_sk(sk); |
66f5fe62 | 72 | unsigned int prior_packets = tp->packets_out; |
9e412ba7 | 73 | |
1da177e4 | 74 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; |
8512430e | 75 | |
75c119af ED |
76 | __skb_unlink(skb, &sk->sk_write_queue); |
77 | tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); | |
78 | ||
66f5fe62 | 79 | tp->packets_out += tcp_skb_pcount(skb); |
bec41a11 | 80 | if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) |
750ea2ba | 81 | tcp_rearm_rto(sk); |
f19c29e3 | 82 | |
f7324acd DM |
83 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, |
84 | tcp_skb_pcount(skb)); | |
1da177e4 LT |
85 | } |
86 | ||
a4ecb15a CC |
87 | /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one |
88 | * window scaling factor due to loss of precision. | |
1da177e4 LT |
89 | * If window has been shrunk, what should we make? It is not clear at all. |
90 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
91 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
92 | * invalid. OK, let's make this for now: | |
93 | */ | |
cf533ea5 | 94 | static inline __u32 tcp_acceptable_seq(const struct sock *sk) |
1da177e4 | 95 | { |
cf533ea5 | 96 | const struct tcp_sock *tp = tcp_sk(sk); |
9e412ba7 | 97 | |
a4ecb15a CC |
98 | if (!before(tcp_wnd_end(tp), tp->snd_nxt) || |
99 | (tp->rx_opt.wscale_ok && | |
100 | ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) | |
1da177e4 LT |
101 | return tp->snd_nxt; |
102 | else | |
90840def | 103 | return tcp_wnd_end(tp); |
1da177e4 LT |
104 | } |
105 | ||
106 | /* Calculate mss to advertise in SYN segment. | |
107 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
108 | * | |
109 | * 1. It is independent of path mtu. | |
110 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
111 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
112 | * attached devices, because some buggy hosts are confused by | |
113 | * large MSS. | |
114 | * 4. We do not make 3, we advertise MSS, calculated from first | |
115 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
116 | * This may be overridden via information stored in routing table. | |
117 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
118 | * probably even Jumbo". | |
119 | */ | |
120 | static __u16 tcp_advertise_mss(struct sock *sk) | |
121 | { | |
122 | struct tcp_sock *tp = tcp_sk(sk); | |
cf533ea5 | 123 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
124 | int mss = tp->advmss; |
125 | ||
0dbaee3b DM |
126 | if (dst) { |
127 | unsigned int metric = dst_metric_advmss(dst); | |
128 | ||
129 | if (metric < mss) { | |
130 | mss = metric; | |
131 | tp->advmss = mss; | |
132 | } | |
1da177e4 LT |
133 | } |
134 | ||
135 | return (__u16)mss; | |
136 | } | |
137 | ||
138 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
6f021c62 ED |
139 | * This is the first part of cwnd validation mechanism. |
140 | */ | |
141 | void tcp_cwnd_restart(struct sock *sk, s32 delta) | |
1da177e4 | 142 | { |
463c84b9 | 143 | struct tcp_sock *tp = tcp_sk(sk); |
6f021c62 | 144 | u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
1da177e4 LT |
145 | u32 cwnd = tp->snd_cwnd; |
146 | ||
6687e988 | 147 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 148 | |
6687e988 | 149 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
150 | restart_cwnd = min(restart_cwnd, cwnd); |
151 | ||
463c84b9 | 152 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
153 | cwnd >>= 1; |
154 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
c2203cf7 | 155 | tp->snd_cwnd_stamp = tcp_jiffies32; |
1da177e4 LT |
156 | tp->snd_cwnd_used = 0; |
157 | } | |
158 | ||
67edfef7 | 159 | /* Congestion state accounting after a packet has been sent. */ |
40efc6fa | 160 | static void tcp_event_data_sent(struct tcp_sock *tp, |
cf533ea5 | 161 | struct sock *sk) |
1da177e4 | 162 | { |
463c84b9 | 163 | struct inet_connection_sock *icsk = inet_csk(sk); |
d635fbe2 | 164 | const u32 now = tcp_jiffies32; |
1da177e4 | 165 | |
05c5a46d NC |
166 | if (tcp_packets_in_flight(tp) == 0) |
167 | tcp_ca_event(sk, CA_EVENT_TX_START); | |
168 | ||
1da177e4 LT |
169 | tp->lsndtime = now; |
170 | ||
171 | /* If it is a reply for ato after last received | |
172 | * packet, enter pingpong mode. | |
173 | */ | |
2251ae46 JM |
174 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
175 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
176 | } |
177 | ||
67edfef7 | 178 | /* Account for an ACK we sent. */ |
27cde44a YC |
179 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, |
180 | u32 rcv_nxt) | |
1da177e4 | 181 | { |
5d9f4262 ED |
182 | struct tcp_sock *tp = tcp_sk(sk); |
183 | ||
184 | if (unlikely(tp->compressed_ack)) { | |
200d95f4 ED |
185 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, |
186 | tp->compressed_ack); | |
5d9f4262 ED |
187 | tp->compressed_ack = 0; |
188 | if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) | |
189 | __sock_put(sk); | |
190 | } | |
27cde44a YC |
191 | |
192 | if (unlikely(rcv_nxt != tp->rcv_nxt)) | |
193 | return; /* Special ACK sent by DCTCP to reflect ECN */ | |
463c84b9 ACM |
194 | tcp_dec_quickack_mode(sk, pkts); |
195 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
196 | } |
197 | ||
85f16525 YC |
198 | |
199 | u32 tcp_default_init_rwnd(u32 mss) | |
200 | { | |
201 | /* Initial receive window should be twice of TCP_INIT_CWND to | |
9ef71e0c | 202 | * enable proper sending of new unsent data during fast recovery |
85f16525 YC |
203 | * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a |
204 | * limit when mss is larger than 1460. | |
205 | */ | |
206 | u32 init_rwnd = TCP_INIT_CWND * 2; | |
207 | ||
208 | if (mss > 1460) | |
209 | init_rwnd = max((1460 * init_rwnd) / mss, 2U); | |
210 | return init_rwnd; | |
211 | } | |
212 | ||
1da177e4 LT |
213 | /* Determine a window scaling and initial window to offer. |
214 | * Based on the assumption that the given amount of space | |
215 | * will be offered. Store the results in the tp structure. | |
216 | * NOTE: for smooth operation initial space offering should | |
217 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
218 | * This MUST be enforced by all callers. | |
219 | */ | |
ceef9ab6 | 220 | void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, |
1da177e4 | 221 | __u32 *rcv_wnd, __u32 *window_clamp, |
31d12926 | 222 | int wscale_ok, __u8 *rcv_wscale, |
223 | __u32 init_rcv_wnd) | |
1da177e4 LT |
224 | { |
225 | unsigned int space = (__space < 0 ? 0 : __space); | |
226 | ||
227 | /* If no clamp set the clamp to the max possible scaled window */ | |
228 | if (*window_clamp == 0) | |
589c49cb | 229 | (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); |
1da177e4 LT |
230 | space = min(*window_clamp, space); |
231 | ||
232 | /* Quantize space offering to a multiple of mss if possible. */ | |
233 | if (space > mss) | |
589c49cb | 234 | space = rounddown(space, mss); |
1da177e4 LT |
235 | |
236 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
237 | * will break some buggy TCP stacks. If the admin tells us |
238 | * it is likely we could be speaking with such a buggy stack | |
239 | * we will truncate our initial window offering to 32K-1 | |
240 | * unless the remote has sent us a window scaling option, | |
241 | * which we interpret as a sign the remote TCP is not | |
242 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 243 | */ |
ceef9ab6 | 244 | if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) |
15d99e02 RJ |
245 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); |
246 | else | |
247 | (*rcv_wnd) = space; | |
248 | ||
1da177e4 LT |
249 | (*rcv_wscale) = 0; |
250 | if (wscale_ok) { | |
589c49cb | 251 | /* Set window scaling on max possible window */ |
356d1833 | 252 | space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]); |
f626300a | 253 | space = max_t(u32, space, sysctl_rmem_max); |
316c1592 | 254 | space = min_t(u32, space, *window_clamp); |
589c49cb | 255 | while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) { |
1da177e4 LT |
256 | space >>= 1; |
257 | (*rcv_wscale)++; | |
258 | } | |
259 | } | |
260 | ||
c36207bd WW |
261 | if (!init_rcv_wnd) /* Use default unless specified otherwise */ |
262 | init_rcv_wnd = tcp_default_init_rwnd(mss); | |
263 | *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); | |
1da177e4 LT |
264 | |
265 | /* Set the clamp no higher than max representable value */ | |
589c49cb | 266 | (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); |
1da177e4 | 267 | } |
4bc2f18b | 268 | EXPORT_SYMBOL(tcp_select_initial_window); |
1da177e4 LT |
269 | |
270 | /* Chose a new window to advertise, update state in tcp_sock for the | |
271 | * socket, and return result with RFC1323 scaling applied. The return | |
272 | * value can be stuffed directly into th->window for an outgoing | |
273 | * frame. | |
274 | */ | |
40efc6fa | 275 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
276 | { |
277 | struct tcp_sock *tp = tcp_sk(sk); | |
8e165e20 | 278 | u32 old_win = tp->rcv_wnd; |
1da177e4 LT |
279 | u32 cur_win = tcp_receive_window(tp); |
280 | u32 new_win = __tcp_select_window(sk); | |
281 | ||
282 | /* Never shrink the offered window */ | |
2de979bd | 283 | if (new_win < cur_win) { |
1da177e4 LT |
284 | /* Danger Will Robinson! |
285 | * Don't update rcv_wup/rcv_wnd here or else | |
286 | * we will not be able to advertise a zero | |
287 | * window in time. --DaveM | |
288 | * | |
289 | * Relax Will Robinson. | |
290 | */ | |
8e165e20 FW |
291 | if (new_win == 0) |
292 | NET_INC_STATS(sock_net(sk), | |
293 | LINUX_MIB_TCPWANTZEROWINDOWADV); | |
607bfbf2 | 294 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
295 | } |
296 | tp->rcv_wnd = new_win; | |
297 | tp->rcv_wup = tp->rcv_nxt; | |
298 | ||
299 | /* Make sure we do not exceed the maximum possible | |
300 | * scaled window. | |
301 | */ | |
ceef9ab6 ED |
302 | if (!tp->rx_opt.rcv_wscale && |
303 | sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) | |
1da177e4 LT |
304 | new_win = min(new_win, MAX_TCP_WINDOW); |
305 | else | |
306 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
307 | ||
308 | /* RFC1323 scaling applied */ | |
309 | new_win >>= tp->rx_opt.rcv_wscale; | |
310 | ||
31770e34 | 311 | /* If we advertise zero window, disable fast path. */ |
8e165e20 | 312 | if (new_win == 0) { |
31770e34 | 313 | tp->pred_flags = 0; |
8e165e20 FW |
314 | if (old_win) |
315 | NET_INC_STATS(sock_net(sk), | |
316 | LINUX_MIB_TCPTOZEROWINDOWADV); | |
317 | } else if (old_win == 0) { | |
318 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); | |
319 | } | |
1da177e4 LT |
320 | |
321 | return new_win; | |
322 | } | |
323 | ||
67edfef7 | 324 | /* Packet ECN state for a SYN-ACK */ |
735d3831 | 325 | static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d | 326 | { |
30e502a3 DB |
327 | const struct tcp_sock *tp = tcp_sk(sk); |
328 | ||
4de075e0 | 329 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
056834d9 | 330 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
4de075e0 | 331 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
91b5b21c LB |
332 | else if (tcp_ca_needs_ecn(sk) || |
333 | tcp_bpf_ca_needs_ecn(sk)) | |
30e502a3 | 334 | INET_ECN_xmit(sk); |
bdf1ee5d IJ |
335 | } |
336 | ||
67edfef7 | 337 | /* Packet ECN state for a SYN. */ |
735d3831 | 338 | static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d IJ |
339 | { |
340 | struct tcp_sock *tp = tcp_sk(sk); | |
91b5b21c | 341 | bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); |
f7b3bec6 | 342 | bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || |
91b5b21c | 343 | tcp_ca_needs_ecn(sk) || bpf_needs_ecn; |
f7b3bec6 FW |
344 | |
345 | if (!use_ecn) { | |
346 | const struct dst_entry *dst = __sk_dst_get(sk); | |
347 | ||
348 | if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) | |
349 | use_ecn = true; | |
350 | } | |
bdf1ee5d IJ |
351 | |
352 | tp->ecn_flags = 0; | |
f7b3bec6 FW |
353 | |
354 | if (use_ecn) { | |
4de075e0 | 355 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
bdf1ee5d | 356 | tp->ecn_flags = TCP_ECN_OK; |
91b5b21c | 357 | if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) |
30e502a3 | 358 | INET_ECN_xmit(sk); |
bdf1ee5d IJ |
359 | } |
360 | } | |
361 | ||
49213555 DB |
362 | static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) |
363 | { | |
364 | if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) | |
365 | /* tp->ecn_flags are cleared at a later point in time when | |
366 | * SYN ACK is ultimatively being received. | |
367 | */ | |
368 | TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); | |
369 | } | |
370 | ||
735d3831 | 371 | static void |
6ac705b1 | 372 | tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) |
bdf1ee5d | 373 | { |
6ac705b1 | 374 | if (inet_rsk(req)->ecn_ok) |
bdf1ee5d IJ |
375 | th->ece = 1; |
376 | } | |
377 | ||
67edfef7 AK |
378 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
379 | * be sent. | |
380 | */ | |
735d3831 | 381 | static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, |
ea1627c2 | 382 | struct tcphdr *th, int tcp_header_len) |
bdf1ee5d IJ |
383 | { |
384 | struct tcp_sock *tp = tcp_sk(sk); | |
385 | ||
386 | if (tp->ecn_flags & TCP_ECN_OK) { | |
387 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
388 | if (skb->len != tcp_header_len && | |
389 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
390 | INET_ECN_xmit(sk); | |
056834d9 | 391 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d | 392 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
ea1627c2 | 393 | th->cwr = 1; |
bdf1ee5d IJ |
394 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; |
395 | } | |
30e502a3 | 396 | } else if (!tcp_ca_needs_ecn(sk)) { |
bdf1ee5d IJ |
397 | /* ACK or retransmitted segment: clear ECT|CE */ |
398 | INET_ECN_dontxmit(sk); | |
399 | } | |
400 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
ea1627c2 | 401 | th->ece = 1; |
bdf1ee5d IJ |
402 | } |
403 | } | |
404 | ||
e870a8ef IJ |
405 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
406 | * auto increment end seqno. | |
407 | */ | |
408 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
409 | { | |
2e8e18ef | 410 | skb->ip_summed = CHECKSUM_PARTIAL; |
e870a8ef | 411 | |
4de075e0 | 412 | TCP_SKB_CB(skb)->tcp_flags = flags; |
e870a8ef IJ |
413 | TCP_SKB_CB(skb)->sacked = 0; |
414 | ||
cd7d8498 | 415 | tcp_skb_pcount_set(skb, 1); |
e870a8ef IJ |
416 | |
417 | TCP_SKB_CB(skb)->seq = seq; | |
a3433f35 | 418 | if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
e870a8ef IJ |
419 | seq++; |
420 | TCP_SKB_CB(skb)->end_seq = seq; | |
421 | } | |
422 | ||
a2a385d6 | 423 | static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
33f5f57e IJ |
424 | { |
425 | return tp->snd_una != tp->snd_up; | |
426 | } | |
427 | ||
33ad798c AL |
428 | #define OPTION_SACK_ADVERTISE (1 << 0) |
429 | #define OPTION_TS (1 << 1) | |
430 | #define OPTION_MD5 (1 << 2) | |
89e95a61 | 431 | #define OPTION_WSCALE (1 << 3) |
2100c8d2 | 432 | #define OPTION_FAST_OPEN_COOKIE (1 << 8) |
60e2a778 UB |
433 | #define OPTION_SMC (1 << 9) |
434 | ||
435 | static void smc_options_write(__be32 *ptr, u16 *options) | |
436 | { | |
437 | #if IS_ENABLED(CONFIG_SMC) | |
438 | if (static_branch_unlikely(&tcp_have_smc)) { | |
439 | if (unlikely(OPTION_SMC & *options)) { | |
440 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
441 | (TCPOPT_NOP << 16) | | |
442 | (TCPOPT_EXP << 8) | | |
443 | (TCPOLEN_EXP_SMC_BASE)); | |
444 | *ptr++ = htonl(TCPOPT_SMC_MAGIC); | |
445 | } | |
446 | } | |
447 | #endif | |
448 | } | |
33ad798c AL |
449 | |
450 | struct tcp_out_options { | |
2100c8d2 YC |
451 | u16 options; /* bit field of OPTION_* */ |
452 | u16 mss; /* 0 to disable */ | |
33ad798c AL |
453 | u8 ws; /* window scale, 0 to disable */ |
454 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 455 | u8 hash_size; /* bytes in hash_location */ |
bd0388ae | 456 | __u8 *hash_location; /* temporary pointer, overloaded */ |
2100c8d2 YC |
457 | __u32 tsval, tsecr; /* need to include OPTION_TS */ |
458 | struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ | |
33ad798c AL |
459 | }; |
460 | ||
67edfef7 AK |
461 | /* Write previously computed TCP options to the packet. |
462 | * | |
463 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
464 | * TCP options, we learned this through the hard way, so be careful here. |
465 | * Luckily we can at least blame others for their non-compliance but from | |
8e3bff96 | 466 | * inter-operability perspective it seems that we're somewhat stuck with |
fd6149d3 IJ |
467 | * the ordering which we have been using if we want to keep working with |
468 | * those broken things (not that it currently hurts anybody as there isn't | |
469 | * particular reason why the ordering would need to be changed). | |
470 | * | |
471 | * At least SACK_PERM as the first option is known to lead to a disaster | |
472 | * (but it may well be that other scenarios fail similarly). | |
473 | */ | |
33ad798c | 474 | static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
bd0388ae WAS |
475 | struct tcp_out_options *opts) |
476 | { | |
2100c8d2 | 477 | u16 options = opts->options; /* mungable copy */ |
bd0388ae | 478 | |
bd0388ae | 479 | if (unlikely(OPTION_MD5 & options)) { |
1a2c6181 CP |
480 | *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
481 | (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); | |
bd0388ae WAS |
482 | /* overload cookie hash location */ |
483 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 484 | ptr += 4; |
40efc6fa | 485 | } |
33ad798c | 486 | |
fd6149d3 IJ |
487 | if (unlikely(opts->mss)) { |
488 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
489 | (TCPOLEN_MSS << 16) | | |
490 | opts->mss); | |
491 | } | |
492 | ||
bd0388ae WAS |
493 | if (likely(OPTION_TS & options)) { |
494 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
495 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
496 | (TCPOLEN_SACK_PERM << 16) | | |
497 | (TCPOPT_TIMESTAMP << 8) | | |
498 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 499 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
500 | } else { |
501 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
502 | (TCPOPT_NOP << 16) | | |
503 | (TCPOPT_TIMESTAMP << 8) | | |
504 | TCPOLEN_TIMESTAMP); | |
505 | } | |
506 | *ptr++ = htonl(opts->tsval); | |
507 | *ptr++ = htonl(opts->tsecr); | |
508 | } | |
509 | ||
bd0388ae | 510 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
33ad798c AL |
511 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
512 | (TCPOPT_NOP << 16) | | |
513 | (TCPOPT_SACK_PERM << 8) | | |
514 | TCPOLEN_SACK_PERM); | |
515 | } | |
516 | ||
bd0388ae | 517 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
518 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
519 | (TCPOPT_WINDOW << 16) | | |
520 | (TCPOLEN_WINDOW << 8) | | |
521 | opts->ws); | |
522 | } | |
523 | ||
524 | if (unlikely(opts->num_sack_blocks)) { | |
525 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
526 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
527 | int this_sack; |
528 | ||
529 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
530 | (TCPOPT_NOP << 16) | | |
531 | (TCPOPT_SACK << 8) | | |
33ad798c | 532 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 533 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 534 | |
33ad798c AL |
535 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
536 | ++this_sack) { | |
40efc6fa SH |
537 | *ptr++ = htonl(sp[this_sack].start_seq); |
538 | *ptr++ = htonl(sp[this_sack].end_seq); | |
539 | } | |
2de979bd | 540 | |
5861f8e5 | 541 | tp->rx_opt.dsack = 0; |
40efc6fa | 542 | } |
2100c8d2 YC |
543 | |
544 | if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { | |
545 | struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; | |
7f9b838b DL |
546 | u8 *p = (u8 *)ptr; |
547 | u32 len; /* Fast Open option length */ | |
548 | ||
549 | if (foc->exp) { | |
550 | len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; | |
551 | *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | | |
552 | TCPOPT_FASTOPEN_MAGIC); | |
553 | p += TCPOLEN_EXP_FASTOPEN_BASE; | |
554 | } else { | |
555 | len = TCPOLEN_FASTOPEN_BASE + foc->len; | |
556 | *p++ = TCPOPT_FASTOPEN; | |
557 | *p++ = len; | |
558 | } | |
2100c8d2 | 559 | |
7f9b838b DL |
560 | memcpy(p, foc->val, foc->len); |
561 | if ((len & 3) == 2) { | |
562 | p[foc->len] = TCPOPT_NOP; | |
563 | p[foc->len + 1] = TCPOPT_NOP; | |
2100c8d2 | 564 | } |
7f9b838b | 565 | ptr += (len + 3) >> 2; |
2100c8d2 | 566 | } |
60e2a778 UB |
567 | |
568 | smc_options_write(ptr, &options); | |
569 | } | |
570 | ||
571 | static void smc_set_option(const struct tcp_sock *tp, | |
572 | struct tcp_out_options *opts, | |
573 | unsigned int *remaining) | |
574 | { | |
575 | #if IS_ENABLED(CONFIG_SMC) | |
576 | if (static_branch_unlikely(&tcp_have_smc)) { | |
577 | if (tp->syn_smc) { | |
578 | if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { | |
579 | opts->options |= OPTION_SMC; | |
580 | *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; | |
581 | } | |
582 | } | |
583 | } | |
584 | #endif | |
585 | } | |
586 | ||
587 | static void smc_set_option_cond(const struct tcp_sock *tp, | |
588 | const struct inet_request_sock *ireq, | |
589 | struct tcp_out_options *opts, | |
590 | unsigned int *remaining) | |
591 | { | |
592 | #if IS_ENABLED(CONFIG_SMC) | |
593 | if (static_branch_unlikely(&tcp_have_smc)) { | |
594 | if (tp->syn_smc && ireq->smc_ok) { | |
595 | if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { | |
596 | opts->options |= OPTION_SMC; | |
597 | *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; | |
598 | } | |
599 | } | |
600 | } | |
601 | #endif | |
33ad798c AL |
602 | } |
603 | ||
67edfef7 AK |
604 | /* Compute TCP options for SYN packets. This is not the final |
605 | * network wire format yet. | |
606 | */ | |
95c96174 | 607 | static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 608 | struct tcp_out_options *opts, |
cf533ea5 ED |
609 | struct tcp_md5sig_key **md5) |
610 | { | |
33ad798c | 611 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 612 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
783237e8 | 613 | struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
33ad798c | 614 | |
8c2320e8 | 615 | *md5 = NULL; |
cfb6eeb4 | 616 | #ifdef CONFIG_TCP_MD5SIG |
8c2320e8 ED |
617 | if (unlikely(rcu_access_pointer(tp->md5sig_info))) { |
618 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
619 | if (*md5) { | |
620 | opts->options |= OPTION_MD5; | |
621 | remaining -= TCPOLEN_MD5SIG_ALIGNED; | |
622 | } | |
cfb6eeb4 YH |
623 | } |
624 | #endif | |
33ad798c AL |
625 | |
626 | /* We always get an MSS option. The option bytes which will be seen in | |
627 | * normal data packets should timestamps be used, must be in the MSS | |
628 | * advertised. But we subtract them from tp->mss_cache so that | |
629 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
630 | * fact here if necessary. If we don't do this correctly, as a | |
631 | * receiver we won't recognize data packets as being full sized when we | |
632 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
633 | * SACKs don't matter, we never delay an ACK when we have any of those | |
634 | * going out. */ | |
635 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 636 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 637 | |
5d2ed052 | 638 | if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) { |
33ad798c | 639 | opts->options |= OPTION_TS; |
7faee5c0 | 640 | opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; |
33ad798c | 641 | opts->tsecr = tp->rx_opt.ts_recent; |
bd0388ae | 642 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 643 | } |
9bb37ef0 | 644 | if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) { |
33ad798c | 645 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 646 | opts->options |= OPTION_WSCALE; |
bd0388ae | 647 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 648 | } |
f9301034 | 649 | if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) { |
33ad798c | 650 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 651 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 652 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
653 | } |
654 | ||
783237e8 | 655 | if (fastopen && fastopen->cookie.len >= 0) { |
2646c831 DL |
656 | u32 need = fastopen->cookie.len; |
657 | ||
658 | need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : | |
659 | TCPOLEN_FASTOPEN_BASE; | |
783237e8 YC |
660 | need = (need + 3) & ~3U; /* Align to 32 bits */ |
661 | if (remaining >= need) { | |
662 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
663 | opts->fastopen_cookie = &fastopen->cookie; | |
664 | remaining -= need; | |
665 | tp->syn_fastopen = 1; | |
2646c831 | 666 | tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; |
783237e8 YC |
667 | } |
668 | } | |
bd0388ae | 669 | |
60e2a778 UB |
670 | smc_set_option(tp, opts, &remaining); |
671 | ||
bd0388ae | 672 | return MAX_TCP_OPTION_SPACE - remaining; |
40efc6fa SH |
673 | } |
674 | ||
67edfef7 | 675 | /* Set up TCP options for SYN-ACKs. */ |
60e2a778 UB |
676 | static unsigned int tcp_synack_options(const struct sock *sk, |
677 | struct request_sock *req, | |
37bfbdda ED |
678 | unsigned int mss, struct sk_buff *skb, |
679 | struct tcp_out_options *opts, | |
680 | const struct tcp_md5sig_key *md5, | |
681 | struct tcp_fastopen_cookie *foc) | |
4957faad | 682 | { |
33ad798c | 683 | struct inet_request_sock *ireq = inet_rsk(req); |
95c96174 | 684 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
33ad798c | 685 | |
cfb6eeb4 | 686 | #ifdef CONFIG_TCP_MD5SIG |
80f03e27 | 687 | if (md5) { |
33ad798c | 688 | opts->options |= OPTION_MD5; |
4957faad WAS |
689 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
690 | ||
691 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
692 | * options. There was discussion about disabling SACK | |
693 | * rather than TS in order to fit in better with old, | |
694 | * buggy kernels, but that was deemed to be unnecessary. | |
695 | */ | |
de213e5e | 696 | ireq->tstamp_ok &= !ireq->sack_ok; |
cfb6eeb4 YH |
697 | } |
698 | #endif | |
33ad798c | 699 | |
4957faad | 700 | /* We always send an MSS option. */ |
33ad798c | 701 | opts->mss = mss; |
4957faad | 702 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
703 | |
704 | if (likely(ireq->wscale_ok)) { | |
705 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 706 | opts->options |= OPTION_WSCALE; |
4957faad | 707 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 708 | } |
de213e5e | 709 | if (likely(ireq->tstamp_ok)) { |
33ad798c | 710 | opts->options |= OPTION_TS; |
95a22cae | 711 | opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; |
33ad798c | 712 | opts->tsecr = req->ts_recent; |
4957faad | 713 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
714 | } |
715 | if (likely(ireq->sack_ok)) { | |
716 | opts->options |= OPTION_SACK_ADVERTISE; | |
de213e5e | 717 | if (unlikely(!ireq->tstamp_ok)) |
4957faad | 718 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c | 719 | } |
7f9b838b DL |
720 | if (foc != NULL && foc->len >= 0) { |
721 | u32 need = foc->len; | |
722 | ||
723 | need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : | |
724 | TCPOLEN_FASTOPEN_BASE; | |
8336886f JC |
725 | need = (need + 3) & ~3U; /* Align to 32 bits */ |
726 | if (remaining >= need) { | |
727 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
728 | opts->fastopen_cookie = foc; | |
729 | remaining -= need; | |
730 | } | |
731 | } | |
1a2c6181 | 732 | |
60e2a778 UB |
733 | smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); |
734 | ||
4957faad | 735 | return MAX_TCP_OPTION_SPACE - remaining; |
33ad798c AL |
736 | } |
737 | ||
67edfef7 AK |
738 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
739 | * final wire format yet. | |
740 | */ | |
95c96174 | 741 | static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 742 | struct tcp_out_options *opts, |
cf533ea5 ED |
743 | struct tcp_md5sig_key **md5) |
744 | { | |
33ad798c | 745 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 746 | unsigned int size = 0; |
cabeccbd | 747 | unsigned int eff_sacks; |
33ad798c | 748 | |
5843ef42 AK |
749 | opts->options = 0; |
750 | ||
8c2320e8 | 751 | *md5 = NULL; |
33ad798c | 752 | #ifdef CONFIG_TCP_MD5SIG |
8c2320e8 ED |
753 | if (unlikely(rcu_access_pointer(tp->md5sig_info))) { |
754 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
755 | if (*md5) { | |
756 | opts->options |= OPTION_MD5; | |
757 | size += TCPOLEN_MD5SIG_ALIGNED; | |
758 | } | |
33ad798c | 759 | } |
33ad798c AL |
760 | #endif |
761 | ||
762 | if (likely(tp->rx_opt.tstamp_ok)) { | |
763 | opts->options |= OPTION_TS; | |
7faee5c0 | 764 | opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; |
33ad798c AL |
765 | opts->tsecr = tp->rx_opt.ts_recent; |
766 | size += TCPOLEN_TSTAMP_ALIGNED; | |
767 | } | |
768 | ||
cabeccbd IJ |
769 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
770 | if (unlikely(eff_sacks)) { | |
95c96174 | 771 | const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
33ad798c | 772 | opts->num_sack_blocks = |
95c96174 | 773 | min_t(unsigned int, eff_sacks, |
33ad798c AL |
774 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
775 | TCPOLEN_SACK_PERBLOCK); | |
776 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
777 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
778 | } | |
779 | ||
780 | return size; | |
40efc6fa | 781 | } |
1da177e4 | 782 | |
46d3ceab ED |
783 | |
784 | /* TCP SMALL QUEUES (TSQ) | |
785 | * | |
786 | * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) | |
787 | * to reduce RTT and bufferbloat. | |
788 | * We do this using a special skb destructor (tcp_wfree). | |
789 | * | |
790 | * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb | |
791 | * needs to be reallocated in a driver. | |
8e3bff96 | 792 | * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
46d3ceab ED |
793 | * |
794 | * Since transmit from skb destructor is forbidden, we use a tasklet | |
795 | * to process all sockets that eventually need to send more skbs. | |
796 | * We use one tasklet per cpu, with its own queue of sockets. | |
797 | */ | |
798 | struct tsq_tasklet { | |
799 | struct tasklet_struct tasklet; | |
800 | struct list_head head; /* queue of tcp sockets */ | |
801 | }; | |
802 | static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); | |
803 | ||
73a6bab5 | 804 | static void tcp_tsq_write(struct sock *sk) |
6f458dfb ED |
805 | { |
806 | if ((1 << sk->sk_state) & | |
807 | (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | | |
f9616c35 ED |
808 | TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { |
809 | struct tcp_sock *tp = tcp_sk(sk); | |
810 | ||
811 | if (tp->lost_out > tp->retrans_out && | |
3a91d29f KD |
812 | tp->snd_cwnd > tcp_packets_in_flight(tp)) { |
813 | tcp_mstamp_refresh(tp); | |
f9616c35 | 814 | tcp_xmit_retransmit_queue(sk); |
3a91d29f | 815 | } |
f9616c35 ED |
816 | |
817 | tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, | |
bf06200e | 818 | 0, GFP_ATOMIC); |
f9616c35 | 819 | } |
6f458dfb | 820 | } |
73a6bab5 ED |
821 | |
822 | static void tcp_tsq_handler(struct sock *sk) | |
823 | { | |
824 | bh_lock_sock(sk); | |
825 | if (!sock_owned_by_user(sk)) | |
826 | tcp_tsq_write(sk); | |
827 | else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) | |
828 | sock_hold(sk); | |
829 | bh_unlock_sock(sk); | |
830 | } | |
46d3ceab | 831 | /* |
8e3bff96 | 832 | * One tasklet per cpu tries to send more skbs. |
46d3ceab | 833 | * We run in tasklet context but need to disable irqs when |
8e3bff96 | 834 | * transferring tsq->head because tcp_wfree() might |
46d3ceab ED |
835 | * interrupt us (non NAPI drivers) |
836 | */ | |
837 | static void tcp_tasklet_func(unsigned long data) | |
838 | { | |
839 | struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; | |
840 | LIST_HEAD(list); | |
841 | unsigned long flags; | |
842 | struct list_head *q, *n; | |
843 | struct tcp_sock *tp; | |
844 | struct sock *sk; | |
845 | ||
846 | local_irq_save(flags); | |
847 | list_splice_init(&tsq->head, &list); | |
848 | local_irq_restore(flags); | |
849 | ||
850 | list_for_each_safe(q, n, &list) { | |
851 | tp = list_entry(q, struct tcp_sock, tsq_node); | |
852 | list_del(&tp->tsq_node); | |
853 | ||
854 | sk = (struct sock *)tp; | |
0a9648f1 | 855 | smp_mb__before_atomic(); |
7aa5470c ED |
856 | clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); |
857 | ||
73a6bab5 | 858 | tcp_tsq_handler(sk); |
46d3ceab ED |
859 | sk_free(sk); |
860 | } | |
861 | } | |
862 | ||
40fc3423 ED |
863 | #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ |
864 | TCPF_WRITE_TIMER_DEFERRED | \ | |
865 | TCPF_DELACK_TIMER_DEFERRED | \ | |
866 | TCPF_MTU_REDUCED_DEFERRED) | |
46d3ceab ED |
867 | /** |
868 | * tcp_release_cb - tcp release_sock() callback | |
869 | * @sk: socket | |
870 | * | |
871 | * called from release_sock() to perform protocol dependent | |
872 | * actions before socket release. | |
873 | */ | |
874 | void tcp_release_cb(struct sock *sk) | |
875 | { | |
6f458dfb | 876 | unsigned long flags, nflags; |
46d3ceab | 877 | |
6f458dfb ED |
878 | /* perform an atomic operation only if at least one flag is set */ |
879 | do { | |
7aa5470c | 880 | flags = sk->sk_tsq_flags; |
6f458dfb ED |
881 | if (!(flags & TCP_DEFERRED_ALL)) |
882 | return; | |
883 | nflags = flags & ~TCP_DEFERRED_ALL; | |
7aa5470c | 884 | } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); |
6f458dfb | 885 | |
73a6bab5 ED |
886 | if (flags & TCPF_TSQ_DEFERRED) { |
887 | tcp_tsq_write(sk); | |
888 | __sock_put(sk); | |
889 | } | |
c3f9b018 ED |
890 | /* Here begins the tricky part : |
891 | * We are called from release_sock() with : | |
892 | * 1) BH disabled | |
893 | * 2) sk_lock.slock spinlock held | |
894 | * 3) socket owned by us (sk->sk_lock.owned == 1) | |
895 | * | |
896 | * But following code is meant to be called from BH handlers, | |
897 | * so we should keep BH disabled, but early release socket ownership | |
898 | */ | |
899 | sock_release_ownership(sk); | |
900 | ||
40fc3423 | 901 | if (flags & TCPF_WRITE_TIMER_DEFERRED) { |
6f458dfb | 902 | tcp_write_timer_handler(sk); |
144d56e9 ED |
903 | __sock_put(sk); |
904 | } | |
40fc3423 | 905 | if (flags & TCPF_DELACK_TIMER_DEFERRED) { |
6f458dfb | 906 | tcp_delack_timer_handler(sk); |
144d56e9 ED |
907 | __sock_put(sk); |
908 | } | |
40fc3423 | 909 | if (flags & TCPF_MTU_REDUCED_DEFERRED) { |
4fab9071 | 910 | inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); |
144d56e9 ED |
911 | __sock_put(sk); |
912 | } | |
46d3ceab ED |
913 | } |
914 | EXPORT_SYMBOL(tcp_release_cb); | |
915 | ||
916 | void __init tcp_tasklet_init(void) | |
917 | { | |
918 | int i; | |
919 | ||
920 | for_each_possible_cpu(i) { | |
921 | struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); | |
922 | ||
923 | INIT_LIST_HEAD(&tsq->head); | |
924 | tasklet_init(&tsq->tasklet, | |
925 | tcp_tasklet_func, | |
926 | (unsigned long)tsq); | |
927 | } | |
928 | } | |
929 | ||
930 | /* | |
931 | * Write buffer destructor automatically called from kfree_skb. | |
8e3bff96 | 932 | * We can't xmit new skbs from this context, as we might already |
46d3ceab ED |
933 | * hold qdisc lock. |
934 | */ | |
d6a4a104 | 935 | void tcp_wfree(struct sk_buff *skb) |
46d3ceab ED |
936 | { |
937 | struct sock *sk = skb->sk; | |
938 | struct tcp_sock *tp = tcp_sk(sk); | |
408f0a6c | 939 | unsigned long flags, nval, oval; |
9b462d02 ED |
940 | |
941 | /* Keep one reference on sk_wmem_alloc. | |
942 | * Will be released by sk_free() from here or tcp_tasklet_func() | |
943 | */ | |
14afee4b | 944 | WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); |
9b462d02 ED |
945 | |
946 | /* If this softirq is serviced by ksoftirqd, we are likely under stress. | |
947 | * Wait until our queues (qdisc + devices) are drained. | |
948 | * This gives : | |
949 | * - less callbacks to tcp_write_xmit(), reducing stress (batches) | |
950 | * - chance for incoming ACK (processed by another cpu maybe) | |
951 | * to migrate this flow (skb->ooo_okay will be eventually set) | |
952 | */ | |
14afee4b | 953 | if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) |
9b462d02 | 954 | goto out; |
46d3ceab | 955 | |
7aa5470c | 956 | for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { |
46d3ceab | 957 | struct tsq_tasklet *tsq; |
a9b204d1 | 958 | bool empty; |
46d3ceab | 959 | |
408f0a6c ED |
960 | if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) |
961 | goto out; | |
962 | ||
73a6bab5 | 963 | nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; |
7aa5470c | 964 | nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); |
408f0a6c ED |
965 | if (nval != oval) |
966 | continue; | |
967 | ||
46d3ceab ED |
968 | /* queue this socket to tasklet queue */ |
969 | local_irq_save(flags); | |
903ceff7 | 970 | tsq = this_cpu_ptr(&tsq_tasklet); |
a9b204d1 | 971 | empty = list_empty(&tsq->head); |
46d3ceab | 972 | list_add(&tp->tsq_node, &tsq->head); |
a9b204d1 ED |
973 | if (empty) |
974 | tasklet_schedule(&tsq->tasklet); | |
46d3ceab | 975 | local_irq_restore(flags); |
9b462d02 | 976 | return; |
46d3ceab | 977 | } |
9b462d02 ED |
978 | out: |
979 | sk_free(sk); | |
46d3ceab ED |
980 | } |
981 | ||
73a6bab5 ED |
982 | /* Note: Called under soft irq. |
983 | * We can call TCP stack right away, unless socket is owned by user. | |
218af599 ED |
984 | */ |
985 | enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) | |
986 | { | |
987 | struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); | |
988 | struct sock *sk = (struct sock *)tp; | |
218af599 | 989 | |
73a6bab5 ED |
990 | tcp_tsq_handler(sk); |
991 | sock_put(sk); | |
218af599 | 992 | |
218af599 ED |
993 | return HRTIMER_NORESTART; |
994 | } | |
995 | ||
c092dd5f | 996 | static void tcp_internal_pacing(struct sock *sk) |
218af599 | 997 | { |
218af599 ED |
998 | if (!tcp_needs_internal_pacing(sk)) |
999 | return; | |
218af599 | 1000 | hrtimer_start(&tcp_sk(sk)->pacing_timer, |
c092dd5f | 1001 | ns_to_ktime(tcp_sk(sk)->tcp_wstamp_ns), |
73a6bab5 ED |
1002 | HRTIMER_MODE_ABS_PINNED_SOFT); |
1003 | sock_hold(sk); | |
218af599 ED |
1004 | } |
1005 | ||
ab408b6d | 1006 | static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb) |
e2080072 | 1007 | { |
ab408b6d ED |
1008 | struct tcp_sock *tp = tcp_sk(sk); |
1009 | ||
d3edd06e | 1010 | skb->skb_mstamp_ns = tp->tcp_wstamp_ns; |
ab408b6d ED |
1011 | if (sk->sk_pacing_status != SK_PACING_NONE) { |
1012 | u32 rate = sk->sk_pacing_rate; | |
1013 | ||
1014 | /* Original sch_fq does not pace first 10 MSS | |
1015 | * Note that tp->data_segs_out overflows after 2^32 packets, | |
1016 | * this is a minor annoyance. | |
1017 | */ | |
1018 | if (rate != ~0U && rate && tp->data_segs_out >= 10) { | |
1019 | tp->tcp_wstamp_ns += div_u64((u64)skb->len * NSEC_PER_SEC, rate); | |
c092dd5f ED |
1020 | |
1021 | tcp_internal_pacing(sk); | |
ab408b6d ED |
1022 | } |
1023 | } | |
e2080072 ED |
1024 | list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
1025 | } | |
1026 | ||
1da177e4 LT |
1027 | /* This routine actually transmits TCP packets queued in by |
1028 | * tcp_do_sendmsg(). This is used by both the initial | |
1029 | * transmission and possible later retransmissions. | |
1030 | * All SKB's seen here are completely headerless. It is our | |
1031 | * job to build the TCP header, and pass the packet down to | |
1032 | * IP so it can do the same plus pass the packet off to the | |
1033 | * device. | |
1034 | * | |
1035 | * We are working here with either a clone of the original | |
1036 | * SKB, or a fresh unique copy made by the retransmit engine. | |
1037 | */ | |
2987babb YC |
1038 | static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, |
1039 | int clone_it, gfp_t gfp_mask, u32 rcv_nxt) | |
1da177e4 | 1040 | { |
dfb4b9dc DM |
1041 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1042 | struct inet_sock *inet; | |
1043 | struct tcp_sock *tp; | |
1044 | struct tcp_skb_cb *tcb; | |
33ad798c | 1045 | struct tcp_out_options opts; |
95c96174 | 1046 | unsigned int tcp_options_size, tcp_header_size; |
8c72c65b | 1047 | struct sk_buff *oskb = NULL; |
cfb6eeb4 | 1048 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 1049 | struct tcphdr *th; |
dfb4b9dc DM |
1050 | int err; |
1051 | ||
1052 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
6f094b9e | 1053 | tp = tcp_sk(sk); |
dfb4b9dc | 1054 | |
ccdbb6e9 | 1055 | if (clone_it) { |
6f094b9e LB |
1056 | TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq |
1057 | - tp->snd_una; | |
8c72c65b | 1058 | oskb = skb; |
e2080072 ED |
1059 | |
1060 | tcp_skb_tsorted_save(oskb) { | |
1061 | if (unlikely(skb_cloned(oskb))) | |
1062 | skb = pskb_copy(oskb, gfp_mask); | |
1063 | else | |
1064 | skb = skb_clone(oskb, gfp_mask); | |
1065 | } tcp_skb_tsorted_restore(oskb); | |
1066 | ||
dfb4b9dc DM |
1067 | if (unlikely(!skb)) |
1068 | return -ENOBUFS; | |
1069 | } | |
d3edd06e | 1070 | skb->skb_mstamp_ns = tp->tcp_wstamp_ns; |
1da177e4 | 1071 | |
dfb4b9dc | 1072 | inet = inet_sk(sk); |
dfb4b9dc | 1073 | tcb = TCP_SKB_CB(skb); |
33ad798c | 1074 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 1075 | |
4de075e0 | 1076 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) |
33ad798c AL |
1077 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
1078 | else | |
1079 | tcp_options_size = tcp_established_options(sk, skb, &opts, | |
1080 | &md5); | |
1081 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); | |
e905a9ed | 1082 | |
547669d4 | 1083 | /* if no packet is in qdisc/device queue, then allow XPS to select |
b2532eb9 | 1084 | * another queue. We can be called from tcp_tsq_handler() |
73a6bab5 | 1085 | * which holds one reference to sk. |
b2532eb9 ED |
1086 | * |
1087 | * TODO: Ideally, in-flight pure ACK packets should not matter here. | |
1088 | * One way to get this would be to set skb->truesize = 2 on them. | |
547669d4 | 1089 | */ |
b2532eb9 | 1090 | skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); |
dfb4b9dc | 1091 | |
38ab52e8 ED |
1092 | /* If we had to use memory reserve to allocate this skb, |
1093 | * this might cause drops if packet is looped back : | |
1094 | * Other socket might not have SOCK_MEMALLOC. | |
1095 | * Packets not looped back do not care about pfmemalloc. | |
1096 | */ | |
1097 | skb->pfmemalloc = 0; | |
1098 | ||
aa8223c7 ACM |
1099 | skb_push(skb, tcp_header_size); |
1100 | skb_reset_transport_header(skb); | |
46d3ceab ED |
1101 | |
1102 | skb_orphan(skb); | |
1103 | skb->sk = sk; | |
1d2077ac | 1104 | skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; |
b73c3d0e | 1105 | skb_set_hash_from_sk(skb, sk); |
14afee4b | 1106 | refcount_add(skb->truesize, &sk->sk_wmem_alloc); |
dfb4b9dc | 1107 | |
c3a2e837 JA |
1108 | skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); |
1109 | ||
dfb4b9dc | 1110 | /* Build TCP header and checksum it. */ |
ea1627c2 | 1111 | th = (struct tcphdr *)skb->data; |
c720c7e8 ED |
1112 | th->source = inet->inet_sport; |
1113 | th->dest = inet->inet_dport; | |
dfb4b9dc | 1114 | th->seq = htonl(tcb->seq); |
2987babb | 1115 | th->ack_seq = htonl(rcv_nxt); |
df7a3b07 | 1116 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
4de075e0 | 1117 | tcb->tcp_flags); |
dfb4b9dc | 1118 | |
dfb4b9dc DM |
1119 | th->check = 0; |
1120 | th->urg_ptr = 0; | |
1da177e4 | 1121 | |
33f5f57e | 1122 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
1123 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
1124 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
1125 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
1126 | th->urg = 1; | |
1127 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
0eae88f3 | 1128 | th->urg_ptr = htons(0xFFFF); |
7691367d HX |
1129 | th->urg = 1; |
1130 | } | |
dfb4b9dc | 1131 | } |
1da177e4 | 1132 | |
bd0388ae | 1133 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
51466a75 | 1134 | skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
ea1627c2 ED |
1135 | if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { |
1136 | th->window = htons(tcp_select_window(sk)); | |
1137 | tcp_ecn_send(sk, skb, th, tcp_header_size); | |
1138 | } else { | |
1139 | /* RFC1323: The window in SYN & SYN/ACK segments | |
1140 | * is never scaled. | |
1141 | */ | |
1142 | th->window = htons(min(tp->rcv_wnd, 65535U)); | |
1143 | } | |
cfb6eeb4 YH |
1144 | #ifdef CONFIG_TCP_MD5SIG |
1145 | /* Calculate the MD5 hash, as we have all we need now */ | |
1146 | if (md5) { | |
a465419b | 1147 | sk_nocaps_add(sk, NETIF_F_GSO_MASK); |
bd0388ae | 1148 | tp->af_specific->calc_md5_hash(opts.hash_location, |
39f8e58e | 1149 | md5, sk, skb); |
cfb6eeb4 YH |
1150 | } |
1151 | #endif | |
1152 | ||
bb296246 | 1153 | icsk->icsk_af_ops->send_check(sk, skb); |
1da177e4 | 1154 | |
4de075e0 | 1155 | if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
27cde44a | 1156 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt); |
1da177e4 | 1157 | |
a44d6eac | 1158 | if (skb->len != tcp_header_size) { |
cf533ea5 | 1159 | tcp_event_data_sent(tp, sk); |
a44d6eac | 1160 | tp->data_segs_out += tcp_skb_pcount(skb); |
ba113c3a | 1161 | tp->bytes_sent += skb->len - tcp_header_size; |
a44d6eac | 1162 | } |
1da177e4 | 1163 | |
bd37a088 | 1164 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
aa2ea058 TH |
1165 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
1166 | tcp_skb_pcount(skb)); | |
1da177e4 | 1167 | |
2efd055c | 1168 | tp->segs_out += tcp_skb_pcount(skb); |
f69ad292 | 1169 | /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ |
cd7d8498 | 1170 | skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); |
f69ad292 | 1171 | skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); |
cd7d8498 | 1172 | |
d3edd06e | 1173 | /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ |
971f10ec ED |
1174 | |
1175 | /* Cleanup our debris for IP stacks */ | |
1176 | memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), | |
1177 | sizeof(struct inet6_skb_parm))); | |
1178 | ||
b0270e91 | 1179 | err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); |
7faee5c0 | 1180 | |
8c72c65b ED |
1181 | if (unlikely(err > 0)) { |
1182 | tcp_enter_cwr(sk); | |
1183 | err = net_xmit_eval(err); | |
1184 | } | |
fc225799 | 1185 | if (!err && oskb) { |
ab408b6d | 1186 | tcp_update_skb_after_send(sk, oskb); |
fc225799 ED |
1187 | tcp_rate_skb_sent(sk, oskb); |
1188 | } | |
8c72c65b | 1189 | return err; |
1da177e4 LT |
1190 | } |
1191 | ||
2987babb YC |
1192 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
1193 | gfp_t gfp_mask) | |
1194 | { | |
1195 | return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, | |
1196 | tcp_sk(sk)->rcv_nxt); | |
1197 | } | |
1198 | ||
67edfef7 | 1199 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
1200 | * |
1201 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
1202 | * otherwise socket can stall. | |
1203 | */ | |
1204 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
1205 | { | |
1206 | struct tcp_sock *tp = tcp_sk(sk); | |
1207 | ||
1208 | /* Advance write_seq and place onto the write_queue. */ | |
1209 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
f4a775d1 | 1210 | __skb_header_release(skb); |
fe067e8a | 1211 | tcp_add_write_queue_tail(sk, skb); |
3ab224be HA |
1212 | sk->sk_wmem_queued += skb->truesize; |
1213 | sk_mem_charge(sk, skb->truesize); | |
1da177e4 LT |
1214 | } |
1215 | ||
67edfef7 | 1216 | /* Initialize TSO segments for a packet. */ |
5bbb432c | 1217 | static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
f6302d1d | 1218 | { |
4a64fd6c | 1219 | if (skb->len <= mss_now) { |
f6302d1d DM |
1220 | /* Avoid the costly divide in the normal |
1221 | * non-TSO case. | |
1222 | */ | |
cd7d8498 | 1223 | tcp_skb_pcount_set(skb, 1); |
f69ad292 | 1224 | TCP_SKB_CB(skb)->tcp_gso_size = 0; |
f6302d1d | 1225 | } else { |
cd7d8498 | 1226 | tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); |
f69ad292 | 1227 | TCP_SKB_CB(skb)->tcp_gso_size = mss_now; |
1da177e4 LT |
1228 | } |
1229 | } | |
1230 | ||
797108d1 IJ |
1231 | /* Pcount in the middle of the write queue got changed, we need to do various |
1232 | * tweaks to fix counters | |
1233 | */ | |
cf533ea5 | 1234 | static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
797108d1 IJ |
1235 | { |
1236 | struct tcp_sock *tp = tcp_sk(sk); | |
1237 | ||
1238 | tp->packets_out -= decr; | |
1239 | ||
1240 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
1241 | tp->sacked_out -= decr; | |
1242 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
1243 | tp->retrans_out -= decr; | |
1244 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
1245 | tp->lost_out -= decr; | |
1246 | ||
1247 | /* Reno case is special. Sigh... */ | |
1248 | if (tcp_is_reno(tp) && decr > 0) | |
1249 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
1250 | ||
797108d1 IJ |
1251 | if (tp->lost_skb_hint && |
1252 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
713bafea | 1253 | (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) |
797108d1 IJ |
1254 | tp->lost_cnt_hint -= decr; |
1255 | ||
1256 | tcp_verify_left_out(tp); | |
1257 | } | |
1258 | ||
0a2cf20c SHY |
1259 | static bool tcp_has_tx_tstamp(const struct sk_buff *skb) |
1260 | { | |
1261 | return TCP_SKB_CB(skb)->txstamp_ack || | |
1262 | (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); | |
1263 | } | |
1264 | ||
490cc7d0 WB |
1265 | static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) |
1266 | { | |
1267 | struct skb_shared_info *shinfo = skb_shinfo(skb); | |
1268 | ||
0a2cf20c | 1269 | if (unlikely(tcp_has_tx_tstamp(skb)) && |
490cc7d0 WB |
1270 | !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { |
1271 | struct skb_shared_info *shinfo2 = skb_shinfo(skb2); | |
1272 | u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; | |
1273 | ||
1274 | shinfo->tx_flags &= ~tsflags; | |
1275 | shinfo2->tx_flags |= tsflags; | |
1276 | swap(shinfo->tskey, shinfo2->tskey); | |
b51e13fa MKL |
1277 | TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; |
1278 | TCP_SKB_CB(skb)->txstamp_ack = 0; | |
490cc7d0 WB |
1279 | } |
1280 | } | |
1281 | ||
a166140e MKL |
1282 | static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) |
1283 | { | |
1284 | TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; | |
1285 | TCP_SKB_CB(skb)->eor = 0; | |
1286 | } | |
1287 | ||
75c119af ED |
1288 | /* Insert buff after skb on the write or rtx queue of sk. */ |
1289 | static void tcp_insert_write_queue_after(struct sk_buff *skb, | |
1290 | struct sk_buff *buff, | |
1291 | struct sock *sk, | |
1292 | enum tcp_queue tcp_queue) | |
1293 | { | |
1294 | if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) | |
1295 | __skb_queue_after(&sk->sk_write_queue, skb, buff); | |
1296 | else | |
1297 | tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); | |
1298 | } | |
1299 | ||
1da177e4 LT |
1300 | /* Function to create two new TCP segments. Shrinks the given segment |
1301 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 1302 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
1303 | * Remember, these are still headerless SKBs at this point. |
1304 | */ | |
75c119af ED |
1305 | int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, |
1306 | struct sk_buff *skb, u32 len, | |
6cc55e09 | 1307 | unsigned int mss_now, gfp_t gfp) |
1da177e4 LT |
1308 | { |
1309 | struct tcp_sock *tp = tcp_sk(sk); | |
1310 | struct sk_buff *buff; | |
6475be16 | 1311 | int nsize, old_factor; |
b60b49ea | 1312 | int nlen; |
9ce01461 | 1313 | u8 flags; |
1da177e4 | 1314 | |
2fceec13 IJ |
1315 | if (WARN_ON(len > skb->len)) |
1316 | return -EINVAL; | |
6a438bbe | 1317 | |
1da177e4 LT |
1318 | nsize = skb_headlen(skb) - len; |
1319 | if (nsize < 0) | |
1320 | nsize = 0; | |
1321 | ||
6cc55e09 | 1322 | if (skb_unclone(skb, gfp)) |
1da177e4 LT |
1323 | return -ENOMEM; |
1324 | ||
1325 | /* Get a new skb... force flag on. */ | |
eb934478 | 1326 | buff = sk_stream_alloc_skb(sk, nsize, gfp, true); |
51456b29 | 1327 | if (!buff) |
1da177e4 | 1328 | return -ENOMEM; /* We'll just try again later. */ |
ef5cb973 | 1329 | |
3ab224be HA |
1330 | sk->sk_wmem_queued += buff->truesize; |
1331 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea HX |
1332 | nlen = skb->len - len - nsize; |
1333 | buff->truesize += nlen; | |
1334 | skb->truesize -= nlen; | |
1da177e4 LT |
1335 | |
1336 | /* Correct the sequence numbers. */ | |
1337 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1338 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1339 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1340 | ||
1341 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1342 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1343 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1344 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
e14c3caf | 1345 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
a166140e | 1346 | tcp_skb_fragment_eor(skb, buff); |
1da177e4 | 1347 | |
98be9b12 | 1348 | skb_split(skb, buff, len); |
1da177e4 | 1349 | |
98be9b12 | 1350 | buff->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 | 1351 | |
a61bbcf2 | 1352 | buff->tstamp = skb->tstamp; |
490cc7d0 | 1353 | tcp_fragment_tstamp(skb, buff); |
1da177e4 | 1354 | |
6475be16 DM |
1355 | old_factor = tcp_skb_pcount(skb); |
1356 | ||
1da177e4 | 1357 | /* Fix up tso_factor for both original and new SKB. */ |
5bbb432c ED |
1358 | tcp_set_skb_tso_segs(skb, mss_now); |
1359 | tcp_set_skb_tso_segs(buff, mss_now); | |
1da177e4 | 1360 | |
b9f64820 YC |
1361 | /* Update delivered info for the new segment */ |
1362 | TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; | |
1363 | ||
6475be16 DM |
1364 | /* If this packet has been sent out already, we must |
1365 | * adjust the various packet counters. | |
1366 | */ | |
cf0b450c | 1367 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1368 | int diff = old_factor - tcp_skb_pcount(skb) - |
1369 | tcp_skb_pcount(buff); | |
1da177e4 | 1370 | |
797108d1 IJ |
1371 | if (diff) |
1372 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1373 | } |
1374 | ||
1375 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1376 | __skb_header_release(buff); |
75c119af | 1377 | tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); |
f67971e6 ED |
1378 | if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) |
1379 | list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); | |
1da177e4 LT |
1380 | |
1381 | return 0; | |
1382 | } | |
1383 | ||
f4d01666 ED |
1384 | /* This is similar to __pskb_pull_tail(). The difference is that pulled |
1385 | * data is not copied, but immediately discarded. | |
1da177e4 | 1386 | */ |
7162fb24 | 1387 | static int __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 | 1388 | { |
7b7fc97a | 1389 | struct skb_shared_info *shinfo; |
1da177e4 LT |
1390 | int i, k, eat; |
1391 | ||
4fa48bf3 ED |
1392 | eat = min_t(int, len, skb_headlen(skb)); |
1393 | if (eat) { | |
1394 | __skb_pull(skb, eat); | |
1395 | len -= eat; | |
1396 | if (!len) | |
7162fb24 | 1397 | return 0; |
4fa48bf3 | 1398 | } |
1da177e4 LT |
1399 | eat = len; |
1400 | k = 0; | |
7b7fc97a ED |
1401 | shinfo = skb_shinfo(skb); |
1402 | for (i = 0; i < shinfo->nr_frags; i++) { | |
1403 | int size = skb_frag_size(&shinfo->frags[i]); | |
9e903e08 ED |
1404 | |
1405 | if (size <= eat) { | |
aff65da0 | 1406 | skb_frag_unref(skb, i); |
9e903e08 | 1407 | eat -= size; |
1da177e4 | 1408 | } else { |
7b7fc97a | 1409 | shinfo->frags[k] = shinfo->frags[i]; |
1da177e4 | 1410 | if (eat) { |
7b7fc97a ED |
1411 | shinfo->frags[k].page_offset += eat; |
1412 | skb_frag_size_sub(&shinfo->frags[k], eat); | |
1da177e4 LT |
1413 | eat = 0; |
1414 | } | |
1415 | k++; | |
1416 | } | |
1417 | } | |
7b7fc97a | 1418 | shinfo->nr_frags = k; |
1da177e4 | 1419 | |
1da177e4 LT |
1420 | skb->data_len -= len; |
1421 | skb->len = skb->data_len; | |
7162fb24 | 1422 | return len; |
1da177e4 LT |
1423 | } |
1424 | ||
67edfef7 | 1425 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1426 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1427 | { | |
7162fb24 ED |
1428 | u32 delta_truesize; |
1429 | ||
14bbd6a5 | 1430 | if (skb_unclone(skb, GFP_ATOMIC)) |
1da177e4 LT |
1431 | return -ENOMEM; |
1432 | ||
7162fb24 | 1433 | delta_truesize = __pskb_trim_head(skb, len); |
1da177e4 LT |
1434 | |
1435 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 1436 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 | 1437 | |
7162fb24 ED |
1438 | if (delta_truesize) { |
1439 | skb->truesize -= delta_truesize; | |
1440 | sk->sk_wmem_queued -= delta_truesize; | |
1441 | sk_mem_uncharge(sk, delta_truesize); | |
1442 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); | |
1443 | } | |
1da177e4 | 1444 | |
5b35e1e6 | 1445 | /* Any change of skb->len requires recalculation of tso factor. */ |
1da177e4 | 1446 | if (tcp_skb_pcount(skb) > 1) |
5bbb432c | 1447 | tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); |
1da177e4 LT |
1448 | |
1449 | return 0; | |
1450 | } | |
1451 | ||
1b63edd6 YC |
1452 | /* Calculate MSS not accounting any TCP options. */ |
1453 | static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
5d424d5a | 1454 | { |
cf533ea5 ED |
1455 | const struct tcp_sock *tp = tcp_sk(sk); |
1456 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1457 | int mss_now; |
1458 | ||
1459 | /* Calculate base mss without TCP options: | |
1460 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1461 | */ | |
1462 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1463 | ||
67469601 ED |
1464 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1465 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1466 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1467 | ||
1468 | if (dst && dst_allfrag(dst)) | |
1469 | mss_now -= icsk->icsk_af_ops->net_frag_header_len; | |
1470 | } | |
1471 | ||
5d424d5a JH |
1472 | /* Clamp it (mss_clamp does not include tcp options) */ |
1473 | if (mss_now > tp->rx_opt.mss_clamp) | |
1474 | mss_now = tp->rx_opt.mss_clamp; | |
1475 | ||
1476 | /* Now subtract optional transport overhead */ | |
1477 | mss_now -= icsk->icsk_ext_hdr_len; | |
1478 | ||
1479 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
1480 | if (mss_now < 48) | |
1481 | mss_now = 48; | |
5d424d5a JH |
1482 | return mss_now; |
1483 | } | |
1484 | ||
1b63edd6 YC |
1485 | /* Calculate MSS. Not accounting for SACKs here. */ |
1486 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
1487 | { | |
1488 | /* Subtract TCP options size, not including SACKs */ | |
1489 | return __tcp_mtu_to_mss(sk, pmtu) - | |
1490 | (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); | |
1491 | } | |
1492 | ||
5d424d5a | 1493 | /* Inverse of above */ |
67469601 | 1494 | int tcp_mss_to_mtu(struct sock *sk, int mss) |
5d424d5a | 1495 | { |
cf533ea5 ED |
1496 | const struct tcp_sock *tp = tcp_sk(sk); |
1497 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1498 | int mtu; |
1499 | ||
1500 | mtu = mss + | |
1501 | tp->tcp_header_len + | |
1502 | icsk->icsk_ext_hdr_len + | |
1503 | icsk->icsk_af_ops->net_header_len; | |
1504 | ||
67469601 ED |
1505 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1506 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1507 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1508 | ||
1509 | if (dst && dst_allfrag(dst)) | |
1510 | mtu += icsk->icsk_af_ops->net_frag_header_len; | |
1511 | } | |
5d424d5a JH |
1512 | return mtu; |
1513 | } | |
556c6b46 | 1514 | EXPORT_SYMBOL(tcp_mss_to_mtu); |
5d424d5a | 1515 | |
67edfef7 | 1516 | /* MTU probing init per socket */ |
5d424d5a JH |
1517 | void tcp_mtup_init(struct sock *sk) |
1518 | { | |
1519 | struct tcp_sock *tp = tcp_sk(sk); | |
1520 | struct inet_connection_sock *icsk = inet_csk(sk); | |
b0f9ca53 | 1521 | struct net *net = sock_net(sk); |
5d424d5a | 1522 | |
b0f9ca53 | 1523 | icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; |
5d424d5a | 1524 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + |
e905a9ed | 1525 | icsk->icsk_af_ops->net_header_len; |
b0f9ca53 | 1526 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); |
5d424d5a | 1527 | icsk->icsk_mtup.probe_size = 0; |
05cbc0db | 1528 | if (icsk->icsk_mtup.enabled) |
c74df29a | 1529 | icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
5d424d5a | 1530 | } |
4bc2f18b | 1531 | EXPORT_SYMBOL(tcp_mtup_init); |
5d424d5a | 1532 | |
1da177e4 LT |
1533 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1534 | ||
1535 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1536 | for TCP options, but includes only bare TCP header. | |
1537 | ||
1538 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1539 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1540 | It also does not include TCP options. |
1541 | ||
d83d8461 | 1542 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1543 | |
1544 | tp->mss_cache is current effective sending mss, including | |
1545 | all tcp options except for SACKs. It is evaluated, | |
1546 | taking into account current pmtu, but never exceeds | |
1547 | tp->rx_opt.mss_clamp. | |
1548 | ||
1549 | NOTE1. rfc1122 clearly states that advertised MSS | |
1550 | DOES NOT include either tcp or ip options. | |
1551 | ||
d83d8461 ACM |
1552 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1553 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1554 | */ |
1da177e4 LT |
1555 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1556 | { | |
1557 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1558 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1559 | int mss_now; |
1da177e4 | 1560 | |
5d424d5a JH |
1561 | if (icsk->icsk_mtup.search_high > pmtu) |
1562 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1563 | |
5d424d5a | 1564 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1565 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1566 | |
1567 | /* And store cached results */ | |
d83d8461 | 1568 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1569 | if (icsk->icsk_mtup.enabled) |
1570 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1571 | tp->mss_cache = mss_now; |
1da177e4 LT |
1572 | |
1573 | return mss_now; | |
1574 | } | |
4bc2f18b | 1575 | EXPORT_SYMBOL(tcp_sync_mss); |
1da177e4 LT |
1576 | |
1577 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1578 | * and even PMTU discovery events into account. | |
1da177e4 | 1579 | */ |
0c54b85f | 1580 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 | 1581 | { |
cf533ea5 ED |
1582 | const struct tcp_sock *tp = tcp_sk(sk); |
1583 | const struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1584 | u32 mss_now; |
95c96174 | 1585 | unsigned int header_len; |
33ad798c AL |
1586 | struct tcp_out_options opts; |
1587 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1588 | |
1589 | mss_now = tp->mss_cache; | |
1590 | ||
1da177e4 LT |
1591 | if (dst) { |
1592 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1593 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1594 | mss_now = tcp_sync_mss(sk, mtu); |
1595 | } | |
1596 | ||
33ad798c AL |
1597 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1598 | sizeof(struct tcphdr); | |
1599 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1600 | * some common options. If this is an odd packet (because we have SACK | |
1601 | * blocks etc) then our calculated header_len will be different, and | |
1602 | * we have to adjust mss_now correspondingly */ | |
1603 | if (header_len != tp->tcp_header_len) { | |
1604 | int delta = (int) header_len - tp->tcp_header_len; | |
1605 | mss_now -= delta; | |
1606 | } | |
cfb6eeb4 | 1607 | |
1da177e4 LT |
1608 | return mss_now; |
1609 | } | |
1610 | ||
86fd14ad WP |
1611 | /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. |
1612 | * As additional protections, we do not touch cwnd in retransmission phases, | |
1613 | * and if application hit its sndbuf limit recently. | |
1614 | */ | |
1615 | static void tcp_cwnd_application_limited(struct sock *sk) | |
1616 | { | |
1617 | struct tcp_sock *tp = tcp_sk(sk); | |
1618 | ||
1619 | if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && | |
1620 | sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { | |
1621 | /* Limited by application or receiver window. */ | |
1622 | u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); | |
1623 | u32 win_used = max(tp->snd_cwnd_used, init_win); | |
1624 | if (win_used < tp->snd_cwnd) { | |
1625 | tp->snd_ssthresh = tcp_current_ssthresh(sk); | |
1626 | tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; | |
1627 | } | |
1628 | tp->snd_cwnd_used = 0; | |
1629 | } | |
c2203cf7 | 1630 | tp->snd_cwnd_stamp = tcp_jiffies32; |
86fd14ad WP |
1631 | } |
1632 | ||
ca8a2263 | 1633 | static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) |
a762a980 | 1634 | { |
1b1fc3fd | 1635 | const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; |
9e412ba7 | 1636 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1637 | |
ca8a2263 NC |
1638 | /* Track the maximum number of outstanding packets in each |
1639 | * window, and remember whether we were cwnd-limited then. | |
1640 | */ | |
1641 | if (!before(tp->snd_una, tp->max_packets_seq) || | |
1642 | tp->packets_out > tp->max_packets_out) { | |
1643 | tp->max_packets_out = tp->packets_out; | |
1644 | tp->max_packets_seq = tp->snd_nxt; | |
1645 | tp->is_cwnd_limited = is_cwnd_limited; | |
1646 | } | |
e114a710 | 1647 | |
24901551 | 1648 | if (tcp_is_cwnd_limited(sk)) { |
a762a980 DM |
1649 | /* Network is feed fully. */ |
1650 | tp->snd_cwnd_used = 0; | |
c2203cf7 | 1651 | tp->snd_cwnd_stamp = tcp_jiffies32; |
a762a980 DM |
1652 | } else { |
1653 | /* Network starves. */ | |
1654 | if (tp->packets_out > tp->snd_cwnd_used) | |
1655 | tp->snd_cwnd_used = tp->packets_out; | |
1656 | ||
b510f0d2 | 1657 | if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle && |
c2203cf7 | 1658 | (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && |
1b1fc3fd | 1659 | !ca_ops->cong_control) |
a762a980 | 1660 | tcp_cwnd_application_limited(sk); |
b0f71bd3 FY |
1661 | |
1662 | /* The following conditions together indicate the starvation | |
1663 | * is caused by insufficient sender buffer: | |
1664 | * 1) just sent some data (see tcp_write_xmit) | |
1665 | * 2) not cwnd limited (this else condition) | |
75c119af | 1666 | * 3) no more data to send (tcp_write_queue_empty()) |
b0f71bd3 FY |
1667 | * 4) application is hitting buffer limit (SOCK_NOSPACE) |
1668 | */ | |
75c119af | 1669 | if (tcp_write_queue_empty(sk) && sk->sk_socket && |
b0f71bd3 FY |
1670 | test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && |
1671 | (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) | |
1672 | tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); | |
a762a980 DM |
1673 | } |
1674 | } | |
1675 | ||
d4589926 ED |
1676 | /* Minshall's variant of the Nagle send check. */ |
1677 | static bool tcp_minshall_check(const struct tcp_sock *tp) | |
1678 | { | |
1679 | return after(tp->snd_sml, tp->snd_una) && | |
1680 | !after(tp->snd_sml, tp->snd_nxt); | |
1681 | } | |
1682 | ||
1683 | /* Update snd_sml if this skb is under mss | |
1684 | * Note that a TSO packet might end with a sub-mss segment | |
1685 | * The test is really : | |
1686 | * if ((skb->len % mss) != 0) | |
1687 | * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1688 | * But we can avoid doing the divide again given we already have | |
1689 | * skb_pcount = skb->len / mss_now | |
0e3a4803 | 1690 | */ |
d4589926 ED |
1691 | static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
1692 | const struct sk_buff *skb) | |
1693 | { | |
1694 | if (skb->len < tcp_skb_pcount(skb) * mss_now) | |
1695 | tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1696 | } | |
1697 | ||
1698 | /* Return false, if packet can be sent now without violation Nagle's rules: | |
1699 | * 1. It is full sized. (provided by caller in %partial bool) | |
1700 | * 2. Or it contains FIN. (already checked by caller) | |
1701 | * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. | |
1702 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
1703 | * With Minshall's modification: all sent small packets are ACKed. | |
1704 | */ | |
1705 | static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, | |
cc93fc51 | 1706 | int nonagle) |
d4589926 ED |
1707 | { |
1708 | return partial && | |
1709 | ((nonagle & TCP_NAGLE_CORK) || | |
1710 | (!nonagle && tp->packets_out && tcp_minshall_check(tp))); | |
1711 | } | |
605ad7f1 ED |
1712 | |
1713 | /* Return how many segs we'd like on a TSO packet, | |
1714 | * to send one TSO packet per ms | |
1715 | */ | |
dcb8c9b4 ED |
1716 | static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, |
1717 | int min_tso_segs) | |
605ad7f1 ED |
1718 | { |
1719 | u32 bytes, segs; | |
1720 | ||
3a9b76fd | 1721 | bytes = min(sk->sk_pacing_rate >> sk->sk_pacing_shift, |
605ad7f1 ED |
1722 | sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); |
1723 | ||
1724 | /* Goal is to send at least one packet per ms, | |
1725 | * not one big TSO packet every 100 ms. | |
1726 | * This preserves ACK clocking and is consistent | |
1727 | * with tcp_tso_should_defer() heuristic. | |
1728 | */ | |
1b3878ca | 1729 | segs = max_t(u32, bytes / mss_now, min_tso_segs); |
605ad7f1 | 1730 | |
350c9f48 | 1731 | return segs; |
605ad7f1 ED |
1732 | } |
1733 | ||
ed6e7268 NC |
1734 | /* Return the number of segments we want in the skb we are transmitting. |
1735 | * See if congestion control module wants to decide; otherwise, autosize. | |
1736 | */ | |
1737 | static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) | |
1738 | { | |
1739 | const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; | |
dcb8c9b4 | 1740 | u32 min_tso, tso_segs; |
ed6e7268 | 1741 | |
dcb8c9b4 ED |
1742 | min_tso = ca_ops->min_tso_segs ? |
1743 | ca_ops->min_tso_segs(sk) : | |
1744 | sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs; | |
1745 | ||
1746 | tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); | |
350c9f48 | 1747 | return min_t(u32, tso_segs, sk->sk_gso_max_segs); |
ed6e7268 NC |
1748 | } |
1749 | ||
d4589926 ED |
1750 | /* Returns the portion of skb which can be sent right away */ |
1751 | static unsigned int tcp_mss_split_point(const struct sock *sk, | |
1752 | const struct sk_buff *skb, | |
1753 | unsigned int mss_now, | |
1754 | unsigned int max_segs, | |
1755 | int nonagle) | |
c1b4a7e6 | 1756 | { |
cf533ea5 | 1757 | const struct tcp_sock *tp = tcp_sk(sk); |
d4589926 | 1758 | u32 partial, needed, window, max_len; |
c1b4a7e6 | 1759 | |
90840def | 1760 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
1485348d | 1761 | max_len = mss_now * max_segs; |
0e3a4803 | 1762 | |
1485348d BH |
1763 | if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
1764 | return max_len; | |
0e3a4803 | 1765 | |
5ea3a748 IJ |
1766 | needed = min(skb->len, window); |
1767 | ||
1485348d BH |
1768 | if (max_len <= needed) |
1769 | return max_len; | |
0e3a4803 | 1770 | |
d4589926 ED |
1771 | partial = needed % mss_now; |
1772 | /* If last segment is not a full MSS, check if Nagle rules allow us | |
1773 | * to include this last segment in this skb. | |
1774 | * Otherwise, we'll split the skb at last MSS boundary | |
1775 | */ | |
cc93fc51 | 1776 | if (tcp_nagle_check(partial != 0, tp, nonagle)) |
d4589926 ED |
1777 | return needed - partial; |
1778 | ||
1779 | return needed; | |
c1b4a7e6 DM |
1780 | } |
1781 | ||
1782 | /* Can at least one segment of SKB be sent right now, according to the | |
1783 | * congestion window rules? If so, return how many segments are allowed. | |
1784 | */ | |
cf533ea5 ED |
1785 | static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
1786 | const struct sk_buff *skb) | |
c1b4a7e6 | 1787 | { |
d649a7a8 | 1788 | u32 in_flight, cwnd, halfcwnd; |
c1b4a7e6 DM |
1789 | |
1790 | /* Don't be strict about the congestion window for the final FIN. */ | |
4de075e0 ED |
1791 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
1792 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
1793 | return 1; |
1794 | ||
1795 | in_flight = tcp_packets_in_flight(tp); | |
1796 | cwnd = tp->snd_cwnd; | |
d649a7a8 ED |
1797 | if (in_flight >= cwnd) |
1798 | return 0; | |
c1b4a7e6 | 1799 | |
d649a7a8 ED |
1800 | /* For better scheduling, ensure we have at least |
1801 | * 2 GSO packets in flight. | |
1802 | */ | |
1803 | halfcwnd = max(cwnd >> 1, 1U); | |
1804 | return min(halfcwnd, cwnd - in_flight); | |
c1b4a7e6 DM |
1805 | } |
1806 | ||
b595076a | 1807 | /* Initialize TSO state of a skb. |
67edfef7 | 1808 | * This must be invoked the first time we consider transmitting |
c1b4a7e6 DM |
1809 | * SKB onto the wire. |
1810 | */ | |
5bbb432c | 1811 | static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
c1b4a7e6 DM |
1812 | { |
1813 | int tso_segs = tcp_skb_pcount(skb); | |
1814 | ||
f8269a49 | 1815 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
5bbb432c | 1816 | tcp_set_skb_tso_segs(skb, mss_now); |
c1b4a7e6 DM |
1817 | tso_segs = tcp_skb_pcount(skb); |
1818 | } | |
1819 | return tso_segs; | |
1820 | } | |
1821 | ||
c1b4a7e6 | 1822 | |
a2a385d6 | 1823 | /* Return true if the Nagle test allows this packet to be |
c1b4a7e6 DM |
1824 | * sent now. |
1825 | */ | |
a2a385d6 ED |
1826 | static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
1827 | unsigned int cur_mss, int nonagle) | |
c1b4a7e6 DM |
1828 | { |
1829 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
1830 | * write_queue (they have no chances to get new data). | |
1831 | * | |
1832 | * This is implemented in the callers, where they modify the 'nonagle' | |
1833 | * argument based upon the location of SKB in the send queue. | |
1834 | */ | |
1835 | if (nonagle & TCP_NAGLE_PUSH) | |
a2a385d6 | 1836 | return true; |
c1b4a7e6 | 1837 | |
9b44190d YC |
1838 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
1839 | if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) | |
a2a385d6 | 1840 | return true; |
c1b4a7e6 | 1841 | |
cc93fc51 | 1842 | if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) |
a2a385d6 | 1843 | return true; |
c1b4a7e6 | 1844 | |
a2a385d6 | 1845 | return false; |
c1b4a7e6 DM |
1846 | } |
1847 | ||
1848 | /* Does at least the first segment of SKB fit into the send window? */ | |
a2a385d6 ED |
1849 | static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
1850 | const struct sk_buff *skb, | |
1851 | unsigned int cur_mss) | |
c1b4a7e6 DM |
1852 | { |
1853 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
1854 | ||
1855 | if (skb->len > cur_mss) | |
1856 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
1857 | ||
90840def | 1858 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
1859 | } |
1860 | ||
c1b4a7e6 DM |
1861 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet |
1862 | * which is put after SKB on the list. It is very much like | |
1863 | * tcp_fragment() except that it may make several kinds of assumptions | |
1864 | * in order to speed up the splitting operation. In particular, we | |
1865 | * know that all the data is in scatter-gather pages, and that the | |
1866 | * packet has never been sent out before (and thus is not cloned). | |
1867 | */ | |
75c119af ED |
1868 | static int tso_fragment(struct sock *sk, enum tcp_queue tcp_queue, |
1869 | struct sk_buff *skb, unsigned int len, | |
c4ead4c5 | 1870 | unsigned int mss_now, gfp_t gfp) |
c1b4a7e6 DM |
1871 | { |
1872 | struct sk_buff *buff; | |
1873 | int nlen = skb->len - len; | |
9ce01461 | 1874 | u8 flags; |
c1b4a7e6 DM |
1875 | |
1876 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 | 1877 | if (skb->len != skb->data_len) |
75c119af | 1878 | return tcp_fragment(sk, tcp_queue, skb, len, mss_now, gfp); |
c1b4a7e6 | 1879 | |
eb934478 | 1880 | buff = sk_stream_alloc_skb(sk, 0, gfp, true); |
51456b29 | 1881 | if (unlikely(!buff)) |
c1b4a7e6 DM |
1882 | return -ENOMEM; |
1883 | ||
3ab224be HA |
1884 | sk->sk_wmem_queued += buff->truesize; |
1885 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea | 1886 | buff->truesize += nlen; |
c1b4a7e6 DM |
1887 | skb->truesize -= nlen; |
1888 | ||
1889 | /* Correct the sequence numbers. */ | |
1890 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1891 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1892 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1893 | ||
1894 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1895 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1896 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1897 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
c1b4a7e6 DM |
1898 | |
1899 | /* This packet was never sent out yet, so no SACK bits. */ | |
1900 | TCP_SKB_CB(buff)->sacked = 0; | |
1901 | ||
a166140e MKL |
1902 | tcp_skb_fragment_eor(skb, buff); |
1903 | ||
98be9b12 | 1904 | buff->ip_summed = CHECKSUM_PARTIAL; |
c1b4a7e6 | 1905 | skb_split(skb, buff, len); |
490cc7d0 | 1906 | tcp_fragment_tstamp(skb, buff); |
c1b4a7e6 DM |
1907 | |
1908 | /* Fix up tso_factor for both original and new SKB. */ | |
5bbb432c ED |
1909 | tcp_set_skb_tso_segs(skb, mss_now); |
1910 | tcp_set_skb_tso_segs(buff, mss_now); | |
c1b4a7e6 DM |
1911 | |
1912 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1913 | __skb_header_release(buff); |
75c119af | 1914 | tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); |
c1b4a7e6 DM |
1915 | |
1916 | return 0; | |
1917 | } | |
1918 | ||
1919 | /* Try to defer sending, if possible, in order to minimize the amount | |
1920 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1921 | * | |
1922 | * This algorithm is from John Heffner. | |
1923 | */ | |
ca8a2263 | 1924 | static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, |
605ad7f1 | 1925 | bool *is_cwnd_limited, u32 max_segs) |
c1b4a7e6 | 1926 | { |
6687e988 | 1927 | const struct inet_connection_sock *icsk = inet_csk(sk); |
50c8339e ED |
1928 | u32 age, send_win, cong_win, limit, in_flight; |
1929 | struct tcp_sock *tp = tcp_sk(sk); | |
50c8339e | 1930 | struct sk_buff *head; |
ad9f4f50 | 1931 | int win_divisor; |
c1b4a7e6 | 1932 | |
4de075e0 | 1933 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) |
ae8064ac | 1934 | goto send_now; |
c1b4a7e6 | 1935 | |
99d7662a | 1936 | if (icsk->icsk_ca_state >= TCP_CA_Recovery) |
ae8064ac JH |
1937 | goto send_now; |
1938 | ||
5f852eb5 ED |
1939 | /* Avoid bursty behavior by allowing defer |
1940 | * only if the last write was recent. | |
1941 | */ | |
d635fbe2 | 1942 | if ((s32)(tcp_jiffies32 - tp->lsndtime) > 0) |
ae8064ac | 1943 | goto send_now; |
908a75c1 | 1944 | |
c1b4a7e6 DM |
1945 | in_flight = tcp_packets_in_flight(tp); |
1946 | ||
c8c9aeb5 SB |
1947 | BUG_ON(tcp_skb_pcount(skb) <= 1); |
1948 | BUG_ON(tp->snd_cwnd <= in_flight); | |
c1b4a7e6 | 1949 | |
90840def | 1950 | send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 DM |
1951 | |
1952 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1953 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1954 | ||
1955 | limit = min(send_win, cong_win); | |
1956 | ||
ba244fe9 | 1957 | /* If a full-sized TSO skb can be sent, do it. */ |
605ad7f1 | 1958 | if (limit >= max_segs * tp->mss_cache) |
ae8064ac | 1959 | goto send_now; |
ba244fe9 | 1960 | |
62ad2761 IJ |
1961 | /* Middle in queue won't get any more data, full sendable already? */ |
1962 | if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) | |
1963 | goto send_now; | |
1964 | ||
5bbcc0f5 | 1965 | win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); |
ad9f4f50 | 1966 | if (win_divisor) { |
c1b4a7e6 DM |
1967 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
1968 | ||
1969 | /* If at least some fraction of a window is available, | |
1970 | * just use it. | |
1971 | */ | |
ad9f4f50 | 1972 | chunk /= win_divisor; |
c1b4a7e6 | 1973 | if (limit >= chunk) |
ae8064ac | 1974 | goto send_now; |
c1b4a7e6 DM |
1975 | } else { |
1976 | /* Different approach, try not to defer past a single | |
1977 | * ACK. Receiver should ACK every other full sized | |
1978 | * frame, so if we have space for more than 3 frames | |
1979 | * then send now. | |
1980 | */ | |
6b5a5c0d | 1981 | if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
ae8064ac | 1982 | goto send_now; |
c1b4a7e6 DM |
1983 | } |
1984 | ||
75c119af ED |
1985 | /* TODO : use tsorted_sent_queue ? */ |
1986 | head = tcp_rtx_queue_head(sk); | |
1987 | if (!head) | |
1988 | goto send_now; | |
2fd66ffb | 1989 | age = tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(head)); |
50c8339e ED |
1990 | /* If next ACK is likely to come too late (half srtt), do not defer */ |
1991 | if (age < (tp->srtt_us >> 4)) | |
1992 | goto send_now; | |
1993 | ||
5f852eb5 | 1994 | /* Ok, it looks like it is advisable to defer. */ |
ae8064ac | 1995 | |
d2e1339f | 1996 | if (cong_win < send_win && cong_win <= skb->len) |
ca8a2263 NC |
1997 | *is_cwnd_limited = true; |
1998 | ||
a2a385d6 | 1999 | return true; |
ae8064ac JH |
2000 | |
2001 | send_now: | |
a2a385d6 | 2002 | return false; |
c1b4a7e6 DM |
2003 | } |
2004 | ||
05cbc0db FD |
2005 | static inline void tcp_mtu_check_reprobe(struct sock *sk) |
2006 | { | |
2007 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2008 | struct tcp_sock *tp = tcp_sk(sk); | |
2009 | struct net *net = sock_net(sk); | |
2010 | u32 interval; | |
2011 | s32 delta; | |
2012 | ||
2013 | interval = net->ipv4.sysctl_tcp_probe_interval; | |
c74df29a | 2014 | delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; |
05cbc0db FD |
2015 | if (unlikely(delta >= interval * HZ)) { |
2016 | int mss = tcp_current_mss(sk); | |
2017 | ||
2018 | /* Update current search range */ | |
2019 | icsk->icsk_mtup.probe_size = 0; | |
2020 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + | |
2021 | sizeof(struct tcphdr) + | |
2022 | icsk->icsk_af_ops->net_header_len; | |
2023 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
2024 | ||
2025 | /* Update probe time stamp */ | |
c74df29a | 2026 | icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
05cbc0db FD |
2027 | } |
2028 | } | |
2029 | ||
808cf9e3 IL |
2030 | static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) |
2031 | { | |
2032 | struct sk_buff *skb, *next; | |
2033 | ||
2034 | skb = tcp_send_head(sk); | |
2035 | tcp_for_write_queue_from_safe(skb, next, sk) { | |
2036 | if (len <= skb->len) | |
2037 | break; | |
2038 | ||
2039 | if (unlikely(TCP_SKB_CB(skb)->eor)) | |
2040 | return false; | |
2041 | ||
2042 | len -= skb->len; | |
2043 | } | |
2044 | ||
2045 | return true; | |
2046 | } | |
2047 | ||
5d424d5a | 2048 | /* Create a new MTU probe if we are ready. |
67edfef7 AK |
2049 | * MTU probe is regularly attempting to increase the path MTU by |
2050 | * deliberately sending larger packets. This discovers routing | |
2051 | * changes resulting in larger path MTUs. | |
2052 | * | |
5d424d5a JH |
2053 | * Returns 0 if we should wait to probe (no cwnd available), |
2054 | * 1 if a probe was sent, | |
056834d9 IJ |
2055 | * -1 otherwise |
2056 | */ | |
5d424d5a JH |
2057 | static int tcp_mtu_probe(struct sock *sk) |
2058 | { | |
5d424d5a | 2059 | struct inet_connection_sock *icsk = inet_csk(sk); |
12a59abc | 2060 | struct tcp_sock *tp = tcp_sk(sk); |
5d424d5a | 2061 | struct sk_buff *skb, *nskb, *next; |
6b58e0a5 | 2062 | struct net *net = sock_net(sk); |
5d424d5a | 2063 | int probe_size; |
91cc17c0 | 2064 | int size_needed; |
12a59abc | 2065 | int copy, len; |
5d424d5a | 2066 | int mss_now; |
6b58e0a5 | 2067 | int interval; |
5d424d5a JH |
2068 | |
2069 | /* Not currently probing/verifying, | |
2070 | * not in recovery, | |
2071 | * have enough cwnd, and | |
12a59abc ED |
2072 | * not SACKing (the variable headers throw things off) |
2073 | */ | |
2074 | if (likely(!icsk->icsk_mtup.enabled || | |
2075 | icsk->icsk_mtup.probe_size || | |
2076 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
2077 | tp->snd_cwnd < 11 || | |
2078 | tp->rx_opt.num_sacks || tp->rx_opt.dsack)) | |
5d424d5a JH |
2079 | return -1; |
2080 | ||
6b58e0a5 FD |
2081 | /* Use binary search for probe_size between tcp_mss_base, |
2082 | * and current mss_clamp. if (search_high - search_low) | |
2083 | * smaller than a threshold, backoff from probing. | |
2084 | */ | |
0c54b85f | 2085 | mss_now = tcp_current_mss(sk); |
6b58e0a5 FD |
2086 | probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + |
2087 | icsk->icsk_mtup.search_low) >> 1); | |
91cc17c0 | 2088 | size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
6b58e0a5 | 2089 | interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; |
05cbc0db FD |
2090 | /* When misfortune happens, we are reprobing actively, |
2091 | * and then reprobe timer has expired. We stick with current | |
2092 | * probing process by not resetting search range to its orignal. | |
2093 | */ | |
6b58e0a5 | 2094 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || |
05cbc0db FD |
2095 | interval < net->ipv4.sysctl_tcp_probe_threshold) { |
2096 | /* Check whether enough time has elaplased for | |
2097 | * another round of probing. | |
2098 | */ | |
2099 | tcp_mtu_check_reprobe(sk); | |
5d424d5a JH |
2100 | return -1; |
2101 | } | |
2102 | ||
2103 | /* Have enough data in the send queue to probe? */ | |
7f9c33e5 | 2104 | if (tp->write_seq - tp->snd_nxt < size_needed) |
5d424d5a JH |
2105 | return -1; |
2106 | ||
91cc17c0 IJ |
2107 | if (tp->snd_wnd < size_needed) |
2108 | return -1; | |
90840def | 2109 | if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
91cc17c0 | 2110 | return 0; |
5d424d5a | 2111 | |
d67c58e9 IJ |
2112 | /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
2113 | if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { | |
2114 | if (!tcp_packets_in_flight(tp)) | |
5d424d5a JH |
2115 | return -1; |
2116 | else | |
2117 | return 0; | |
2118 | } | |
2119 | ||
808cf9e3 IL |
2120 | if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) |
2121 | return -1; | |
2122 | ||
5d424d5a | 2123 | /* We're allowed to probe. Build it now. */ |
eb934478 | 2124 | nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); |
51456b29 | 2125 | if (!nskb) |
5d424d5a | 2126 | return -1; |
3ab224be HA |
2127 | sk->sk_wmem_queued += nskb->truesize; |
2128 | sk_mem_charge(sk, nskb->truesize); | |
5d424d5a | 2129 | |
fe067e8a | 2130 | skb = tcp_send_head(sk); |
5d424d5a JH |
2131 | |
2132 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
2133 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
4de075e0 | 2134 | TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
5d424d5a JH |
2135 | TCP_SKB_CB(nskb)->sacked = 0; |
2136 | nskb->csum = 0; | |
98be9b12 | 2137 | nskb->ip_summed = CHECKSUM_PARTIAL; |
5d424d5a | 2138 | |
50c4817e | 2139 | tcp_insert_write_queue_before(nskb, skb, sk); |
2b7cda9c | 2140 | tcp_highest_sack_replace(sk, skb, nskb); |
50c4817e | 2141 | |
5d424d5a | 2142 | len = 0; |
234b6860 | 2143 | tcp_for_write_queue_from_safe(skb, next, sk) { |
5d424d5a | 2144 | copy = min_t(int, skb->len, probe_size - len); |
98be9b12 | 2145 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); |
5d424d5a JH |
2146 | |
2147 | if (skb->len <= copy) { | |
2148 | /* We've eaten all the data from this skb. | |
2149 | * Throw it away. */ | |
4de075e0 | 2150 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
808cf9e3 IL |
2151 | /* If this is the last SKB we copy and eor is set |
2152 | * we need to propagate it to the new skb. | |
2153 | */ | |
2154 | TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; | |
fe067e8a | 2155 | tcp_unlink_write_queue(skb, sk); |
3ab224be | 2156 | sk_wmem_free_skb(sk, skb); |
5d424d5a | 2157 | } else { |
4de075e0 | 2158 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
a3433f35 | 2159 | ~(TCPHDR_FIN|TCPHDR_PSH); |
5d424d5a JH |
2160 | if (!skb_shinfo(skb)->nr_frags) { |
2161 | skb_pull(skb, copy); | |
5d424d5a JH |
2162 | } else { |
2163 | __pskb_trim_head(skb, copy); | |
5bbb432c | 2164 | tcp_set_skb_tso_segs(skb, mss_now); |
5d424d5a JH |
2165 | } |
2166 | TCP_SKB_CB(skb)->seq += copy; | |
2167 | } | |
2168 | ||
2169 | len += copy; | |
234b6860 IJ |
2170 | |
2171 | if (len >= probe_size) | |
2172 | break; | |
5d424d5a | 2173 | } |
5bbb432c | 2174 | tcp_init_tso_segs(nskb, nskb->len); |
5d424d5a JH |
2175 | |
2176 | /* We're ready to send. If this fails, the probe will | |
7faee5c0 ED |
2177 | * be resegmented into mss-sized pieces by tcp_write_xmit(). |
2178 | */ | |
5d424d5a JH |
2179 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { |
2180 | /* Decrement cwnd here because we are sending | |
056834d9 | 2181 | * effectively two packets. */ |
5d424d5a | 2182 | tp->snd_cwnd--; |
66f5fe62 | 2183 | tcp_event_new_data_sent(sk, nskb); |
5d424d5a JH |
2184 | |
2185 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
2186 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
2187 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
2188 | |
2189 | return 1; | |
2190 | } | |
2191 | ||
2192 | return -1; | |
2193 | } | |
2194 | ||
218af599 ED |
2195 | static bool tcp_pacing_check(const struct sock *sk) |
2196 | { | |
2197 | return tcp_needs_internal_pacing(sk) && | |
73a6bab5 | 2198 | hrtimer_is_queued(&tcp_sk(sk)->pacing_timer); |
218af599 ED |
2199 | } |
2200 | ||
f9616c35 ED |
2201 | /* TCP Small Queues : |
2202 | * Control number of packets in qdisc/devices to two packets / or ~1 ms. | |
2203 | * (These limits are doubled for retransmits) | |
2204 | * This allows for : | |
2205 | * - better RTT estimation and ACK scheduling | |
2206 | * - faster recovery | |
2207 | * - high rates | |
2208 | * Alas, some drivers / subsystems require a fair amount | |
2209 | * of queued bytes to ensure line rate. | |
2210 | * One example is wifi aggregation (802.11 AMPDU) | |
2211 | */ | |
2212 | static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, | |
2213 | unsigned int factor) | |
2214 | { | |
2215 | unsigned int limit; | |
2216 | ||
3a9b76fd | 2217 | limit = max(2 * skb->truesize, sk->sk_pacing_rate >> sk->sk_pacing_shift); |
9184d8bb ED |
2218 | limit = min_t(u32, limit, |
2219 | sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes); | |
f9616c35 ED |
2220 | limit <<= factor; |
2221 | ||
14afee4b | 2222 | if (refcount_read(&sk->sk_wmem_alloc) > limit) { |
75c119af | 2223 | /* Always send skb if rtx queue is empty. |
75eefc6c ED |
2224 | * No need to wait for TX completion to call us back, |
2225 | * after softirq/tasklet schedule. | |
2226 | * This helps when TX completions are delayed too much. | |
2227 | */ | |
75c119af | 2228 | if (tcp_rtx_queue_empty(sk)) |
75eefc6c ED |
2229 | return false; |
2230 | ||
7aa5470c | 2231 | set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); |
f9616c35 ED |
2232 | /* It is possible TX completion already happened |
2233 | * before we set TSQ_THROTTLED, so we must | |
2234 | * test again the condition. | |
2235 | */ | |
2236 | smp_mb__after_atomic(); | |
14afee4b | 2237 | if (refcount_read(&sk->sk_wmem_alloc) > limit) |
f9616c35 ED |
2238 | return true; |
2239 | } | |
2240 | return false; | |
2241 | } | |
2242 | ||
05b055e8 FY |
2243 | static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) |
2244 | { | |
628174cc | 2245 | const u32 now = tcp_jiffies32; |
efe967cd | 2246 | enum tcp_chrono old = tp->chrono_type; |
05b055e8 | 2247 | |
efe967cd AB |
2248 | if (old > TCP_CHRONO_UNSPEC) |
2249 | tp->chrono_stat[old - 1] += now - tp->chrono_start; | |
05b055e8 FY |
2250 | tp->chrono_start = now; |
2251 | tp->chrono_type = new; | |
2252 | } | |
2253 | ||
2254 | void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) | |
2255 | { | |
2256 | struct tcp_sock *tp = tcp_sk(sk); | |
2257 | ||
2258 | /* If there are multiple conditions worthy of tracking in a | |
0f87230d FY |
2259 | * chronograph then the highest priority enum takes precedence |
2260 | * over the other conditions. So that if something "more interesting" | |
05b055e8 FY |
2261 | * starts happening, stop the previous chrono and start a new one. |
2262 | */ | |
2263 | if (type > tp->chrono_type) | |
2264 | tcp_chrono_set(tp, type); | |
2265 | } | |
2266 | ||
2267 | void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) | |
2268 | { | |
2269 | struct tcp_sock *tp = tcp_sk(sk); | |
2270 | ||
0f87230d FY |
2271 | |
2272 | /* There are multiple conditions worthy of tracking in a | |
2273 | * chronograph, so that the highest priority enum takes | |
2274 | * precedence over the other conditions (see tcp_chrono_start). | |
2275 | * If a condition stops, we only stop chrono tracking if | |
2276 | * it's the "most interesting" or current chrono we are | |
2277 | * tracking and starts busy chrono if we have pending data. | |
2278 | */ | |
75c119af | 2279 | if (tcp_rtx_and_write_queues_empty(sk)) |
0f87230d FY |
2280 | tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); |
2281 | else if (type == tp->chrono_type) | |
2282 | tcp_chrono_set(tp, TCP_CHRONO_BUSY); | |
05b055e8 FY |
2283 | } |
2284 | ||
1da177e4 LT |
2285 | /* This routine writes packets to the network. It advances the |
2286 | * send_head. This happens as incoming acks open up the remote | |
2287 | * window for us. | |
2288 | * | |
f8269a49 IJ |
2289 | * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
2290 | * snd_up-64k-mss .. snd_up cannot be large. However, taking into | |
2291 | * account rare use of URG, this is not a big flaw. | |
2292 | * | |
6ba8a3b1 ND |
2293 | * Send at most one packet when push_one > 0. Temporarily ignore |
2294 | * cwnd limit to force at most one packet out when push_one == 2. | |
2295 | ||
a2a385d6 ED |
2296 | * Returns true, if no segments are in flight and we have queued segments, |
2297 | * but cannot send anything now because of SWS or another problem. | |
1da177e4 | 2298 | */ |
a2a385d6 ED |
2299 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
2300 | int push_one, gfp_t gfp) | |
1da177e4 LT |
2301 | { |
2302 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 2303 | struct sk_buff *skb; |
c1b4a7e6 DM |
2304 | unsigned int tso_segs, sent_pkts; |
2305 | int cwnd_quota; | |
5d424d5a | 2306 | int result; |
5615f886 | 2307 | bool is_cwnd_limited = false, is_rwnd_limited = false; |
605ad7f1 | 2308 | u32 max_segs; |
1da177e4 | 2309 | |
92df7b51 | 2310 | sent_pkts = 0; |
5d424d5a | 2311 | |
ee1836ae | 2312 | tcp_mstamp_refresh(tp); |
d5dd9175 IJ |
2313 | if (!push_one) { |
2314 | /* Do MTU probing. */ | |
2315 | result = tcp_mtu_probe(sk); | |
2316 | if (!result) { | |
a2a385d6 | 2317 | return false; |
d5dd9175 IJ |
2318 | } else if (result > 0) { |
2319 | sent_pkts = 1; | |
2320 | } | |
5d424d5a JH |
2321 | } |
2322 | ||
ed6e7268 | 2323 | max_segs = tcp_tso_segs(sk, mss_now); |
fe067e8a | 2324 | while ((skb = tcp_send_head(sk))) { |
c8ac3774 HX |
2325 | unsigned int limit; |
2326 | ||
218af599 ED |
2327 | if (tcp_pacing_check(sk)) |
2328 | break; | |
2329 | ||
5bbb432c | 2330 | tso_segs = tcp_init_tso_segs(skb, mss_now); |
c1b4a7e6 | 2331 | BUG_ON(!tso_segs); |
aa93466b | 2332 | |
9d186cac | 2333 | if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { |
7faee5c0 | 2334 | /* "skb_mstamp" is used as a start point for the retransmit timer */ |
ab408b6d | 2335 | tcp_update_skb_after_send(sk, skb); |
ec342325 | 2336 | goto repair; /* Skip network transmission */ |
9d186cac | 2337 | } |
ec342325 | 2338 | |
b68e9f85 | 2339 | cwnd_quota = tcp_cwnd_test(tp, skb); |
6ba8a3b1 ND |
2340 | if (!cwnd_quota) { |
2341 | if (push_one == 2) | |
2342 | /* Force out a loss probe pkt. */ | |
2343 | cwnd_quota = 1; | |
2344 | else | |
2345 | break; | |
2346 | } | |
b68e9f85 | 2347 | |
5615f886 FY |
2348 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { |
2349 | is_rwnd_limited = true; | |
b68e9f85 | 2350 | break; |
5615f886 | 2351 | } |
b68e9f85 | 2352 | |
d6a4e26a | 2353 | if (tso_segs == 1) { |
c1b4a7e6 DM |
2354 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, |
2355 | (tcp_skb_is_last(sk, skb) ? | |
2356 | nonagle : TCP_NAGLE_PUSH)))) | |
2357 | break; | |
2358 | } else { | |
ca8a2263 | 2359 | if (!push_one && |
605ad7f1 ED |
2360 | tcp_tso_should_defer(sk, skb, &is_cwnd_limited, |
2361 | max_segs)) | |
c1b4a7e6 DM |
2362 | break; |
2363 | } | |
aa93466b | 2364 | |
605ad7f1 | 2365 | limit = mss_now; |
d6a4e26a | 2366 | if (tso_segs > 1 && !tcp_urg_mode(tp)) |
605ad7f1 ED |
2367 | limit = tcp_mss_split_point(sk, skb, mss_now, |
2368 | min_t(unsigned int, | |
2369 | cwnd_quota, | |
2370 | max_segs), | |
2371 | nonagle); | |
2372 | ||
2373 | if (skb->len > limit && | |
75c119af ED |
2374 | unlikely(tso_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
2375 | skb, limit, mss_now, gfp))) | |
605ad7f1 ED |
2376 | break; |
2377 | ||
f9616c35 ED |
2378 | if (tcp_small_queue_check(sk, skb, 0)) |
2379 | break; | |
c9eeec26 | 2380 | |
d5dd9175 | 2381 | if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
92df7b51 | 2382 | break; |
1da177e4 | 2383 | |
ec342325 | 2384 | repair: |
92df7b51 DM |
2385 | /* Advance the send_head. This one is sent out. |
2386 | * This call will increment packets_out. | |
2387 | */ | |
66f5fe62 | 2388 | tcp_event_new_data_sent(sk, skb); |
1da177e4 | 2389 | |
92df7b51 | 2390 | tcp_minshall_update(tp, mss_now, skb); |
a262f0cd | 2391 | sent_pkts += tcp_skb_pcount(skb); |
d5dd9175 IJ |
2392 | |
2393 | if (push_one) | |
2394 | break; | |
92df7b51 | 2395 | } |
1da177e4 | 2396 | |
5615f886 FY |
2397 | if (is_rwnd_limited) |
2398 | tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); | |
2399 | else | |
2400 | tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); | |
2401 | ||
aa93466b | 2402 | if (likely(sent_pkts)) { |
684bad11 YC |
2403 | if (tcp_in_cwnd_reduction(sk)) |
2404 | tp->prr_out += sent_pkts; | |
6ba8a3b1 ND |
2405 | |
2406 | /* Send one loss probe per tail loss episode. */ | |
2407 | if (push_one != 2) | |
ed66dfaf | 2408 | tcp_schedule_loss_probe(sk, false); |
d2e1339f | 2409 | is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); |
ca8a2263 | 2410 | tcp_cwnd_validate(sk, is_cwnd_limited); |
a2a385d6 | 2411 | return false; |
1da177e4 | 2412 | } |
75c119af | 2413 | return !tp->packets_out && !tcp_write_queue_empty(sk); |
6ba8a3b1 ND |
2414 | } |
2415 | ||
ed66dfaf | 2416 | bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) |
6ba8a3b1 ND |
2417 | { |
2418 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2419 | struct tcp_sock *tp = tcp_sk(sk); | |
a2815817 | 2420 | u32 timeout, rto_delta_us; |
2ae21cf5 | 2421 | int early_retrans; |
6ba8a3b1 | 2422 | |
6ba8a3b1 ND |
2423 | /* Don't do any loss probe on a Fast Open connection before 3WHS |
2424 | * finishes. | |
2425 | */ | |
f9b99582 | 2426 | if (tp->fastopen_rsk) |
6ba8a3b1 ND |
2427 | return false; |
2428 | ||
2ae21cf5 | 2429 | early_retrans = sock_net(sk)->ipv4.sysctl_tcp_early_retrans; |
6ba8a3b1 | 2430 | /* Schedule a loss probe in 2*RTT for SACK capable connections |
b4f70c3d | 2431 | * not in loss recovery, that are either limited by cwnd or application. |
6ba8a3b1 | 2432 | */ |
2ae21cf5 | 2433 | if ((early_retrans != 3 && early_retrans != 4) || |
bec41a11 | 2434 | !tp->packets_out || !tcp_is_sack(tp) || |
b4f70c3d NC |
2435 | (icsk->icsk_ca_state != TCP_CA_Open && |
2436 | icsk->icsk_ca_state != TCP_CA_CWR)) | |
6ba8a3b1 ND |
2437 | return false; |
2438 | ||
bb4d991a | 2439 | /* Probe timeout is 2*rtt. Add minimum RTO to account |
f9b99582 YC |
2440 | * for delayed ack when there's one outstanding packet. If no RTT |
2441 | * sample is available then probe after TCP_TIMEOUT_INIT. | |
6ba8a3b1 | 2442 | */ |
bb4d991a YC |
2443 | if (tp->srtt_us) { |
2444 | timeout = usecs_to_jiffies(tp->srtt_us >> 2); | |
2445 | if (tp->packets_out == 1) | |
2446 | timeout += TCP_RTO_MIN; | |
2447 | else | |
2448 | timeout += TCP_TIMEOUT_MIN; | |
2449 | } else { | |
2450 | timeout = TCP_TIMEOUT_INIT; | |
2451 | } | |
6ba8a3b1 | 2452 | |
a2815817 | 2453 | /* If the RTO formula yields an earlier time, then use that time. */ |
ed66dfaf NC |
2454 | rto_delta_us = advancing_rto ? |
2455 | jiffies_to_usecs(inet_csk(sk)->icsk_rto) : | |
2456 | tcp_rto_delta_us(sk); /* How far in future is RTO? */ | |
a2815817 NC |
2457 | if (rto_delta_us > 0) |
2458 | timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); | |
6ba8a3b1 ND |
2459 | |
2460 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, | |
2461 | TCP_RTO_MAX); | |
2462 | return true; | |
2463 | } | |
2464 | ||
1f3279ae ED |
2465 | /* Thanks to skb fast clones, we can detect if a prior transmit of |
2466 | * a packet is still in a qdisc or driver queue. | |
2467 | * In this case, there is very little point doing a retransmit ! | |
1f3279ae ED |
2468 | */ |
2469 | static bool skb_still_in_host_queue(const struct sock *sk, | |
2470 | const struct sk_buff *skb) | |
2471 | { | |
39bb5e62 | 2472 | if (unlikely(skb_fclone_busy(sk, skb))) { |
c10d9310 ED |
2473 | NET_INC_STATS(sock_net(sk), |
2474 | LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); | |
1f3279ae ED |
2475 | return true; |
2476 | } | |
2477 | return false; | |
2478 | } | |
2479 | ||
b340b264 | 2480 | /* When probe timeout (PTO) fires, try send a new segment if possible, else |
6ba8a3b1 ND |
2481 | * retransmit the last segment. |
2482 | */ | |
2483 | void tcp_send_loss_probe(struct sock *sk) | |
2484 | { | |
9b717a8d | 2485 | struct tcp_sock *tp = tcp_sk(sk); |
6ba8a3b1 ND |
2486 | struct sk_buff *skb; |
2487 | int pcount; | |
2488 | int mss = tcp_current_mss(sk); | |
6ba8a3b1 | 2489 | |
b340b264 | 2490 | skb = tcp_send_head(sk); |
75c119af ED |
2491 | if (skb && tcp_snd_wnd_test(tp, skb, mss)) { |
2492 | pcount = tp->packets_out; | |
2493 | tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); | |
2494 | if (tp->packets_out > pcount) | |
2495 | goto probe_sent; | |
2496 | goto rearm_timer; | |
6ba8a3b1 | 2497 | } |
75c119af | 2498 | skb = skb_rb_last(&sk->tcp_rtx_queue); |
6ba8a3b1 | 2499 | |
9b717a8d ND |
2500 | /* At most one outstanding TLP retransmission. */ |
2501 | if (tp->tlp_high_seq) | |
2502 | goto rearm_timer; | |
2503 | ||
6ba8a3b1 | 2504 | /* Retransmit last segment. */ |
6ba8a3b1 ND |
2505 | if (WARN_ON(!skb)) |
2506 | goto rearm_timer; | |
2507 | ||
1f3279ae ED |
2508 | if (skb_still_in_host_queue(sk, skb)) |
2509 | goto rearm_timer; | |
2510 | ||
6ba8a3b1 ND |
2511 | pcount = tcp_skb_pcount(skb); |
2512 | if (WARN_ON(!pcount)) | |
2513 | goto rearm_timer; | |
2514 | ||
2515 | if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { | |
75c119af ED |
2516 | if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, |
2517 | (pcount - 1) * mss, mss, | |
6cc55e09 | 2518 | GFP_ATOMIC))) |
6ba8a3b1 | 2519 | goto rearm_timer; |
75c119af | 2520 | skb = skb_rb_next(skb); |
6ba8a3b1 ND |
2521 | } |
2522 | ||
2523 | if (WARN_ON(!skb || !tcp_skb_pcount(skb))) | |
2524 | goto rearm_timer; | |
2525 | ||
10d3be56 | 2526 | if (__tcp_retransmit_skb(sk, skb, 1)) |
b340b264 | 2527 | goto rearm_timer; |
6ba8a3b1 | 2528 | |
9b717a8d | 2529 | /* Record snd_nxt for loss detection. */ |
b340b264 | 2530 | tp->tlp_high_seq = tp->snd_nxt; |
9b717a8d | 2531 | |
b340b264 | 2532 | probe_sent: |
c10d9310 | 2533 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); |
b340b264 YC |
2534 | /* Reset s.t. tcp_rearm_rto will restart timer from now */ |
2535 | inet_csk(sk)->icsk_pending = 0; | |
6ba8a3b1 | 2536 | rearm_timer: |
fcd16c0a | 2537 | tcp_rearm_rto(sk); |
1da177e4 LT |
2538 | } |
2539 | ||
a762a980 DM |
2540 | /* Push out any pending frames which were held back due to |
2541 | * TCP_CORK or attempt at coalescing tiny packets. | |
2542 | * The socket must be locked by the caller. | |
2543 | */ | |
9e412ba7 IJ |
2544 | void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
2545 | int nonagle) | |
a762a980 | 2546 | { |
726e07a8 IJ |
2547 | /* If we are closed, the bytes will have to remain here. |
2548 | * In time closedown will finish, we empty the write queue and | |
2549 | * all will be happy. | |
2550 | */ | |
2551 | if (unlikely(sk->sk_state == TCP_CLOSE)) | |
2552 | return; | |
2553 | ||
99a1dec7 | 2554 | if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
7450aaf6 | 2555 | sk_gfp_mask(sk, GFP_ATOMIC))) |
726e07a8 | 2556 | tcp_check_probe_timer(sk); |
a762a980 DM |
2557 | } |
2558 | ||
c1b4a7e6 DM |
2559 | /* Send _single_ skb sitting at the send head. This function requires |
2560 | * true push pending frames to setup probe timer etc. | |
2561 | */ | |
2562 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
2563 | { | |
fe067e8a | 2564 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
2565 | |
2566 | BUG_ON(!skb || skb->len < mss_now); | |
2567 | ||
d5dd9175 | 2568 | tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
c1b4a7e6 DM |
2569 | } |
2570 | ||
1da177e4 LT |
2571 | /* This function returns the amount that we can raise the |
2572 | * usable window based on the following constraints | |
e905a9ed | 2573 | * |
1da177e4 LT |
2574 | * 1. The window can never be shrunk once it is offered (RFC 793) |
2575 | * 2. We limit memory per socket | |
2576 | * | |
2577 | * RFC 1122: | |
2578 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
2579 | * RECV.NEXT + RCV.WIN fixed until: | |
2580 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
2581 | * | |
2582 | * i.e. don't raise the right edge of the window until you can raise | |
2583 | * it at least MSS bytes. | |
2584 | * | |
2585 | * Unfortunately, the recommended algorithm breaks header prediction, | |
2586 | * since header prediction assumes th->window stays fixed. | |
2587 | * | |
2588 | * Strictly speaking, keeping th->window fixed violates the receiver | |
2589 | * side SWS prevention criteria. The problem is that under this rule | |
2590 | * a stream of single byte packets will cause the right side of the | |
2591 | * window to always advance by a single byte. | |
e905a9ed | 2592 | * |
1da177e4 LT |
2593 | * Of course, if the sender implements sender side SWS prevention |
2594 | * then this will not be a problem. | |
e905a9ed | 2595 | * |
1da177e4 | 2596 | * BSD seems to make the following compromise: |
e905a9ed | 2597 | * |
1da177e4 LT |
2598 | * If the free space is less than the 1/4 of the maximum |
2599 | * space available and the free space is less than 1/2 mss, | |
2600 | * then set the window to 0. | |
2601 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
2602 | * Otherwise, just prevent the window from shrinking | |
2603 | * and from being larger than the largest representable value. | |
2604 | * | |
2605 | * This prevents incremental opening of the window in the regime | |
2606 | * where TCP is limited by the speed of the reader side taking | |
2607 | * data out of the TCP receive queue. It does nothing about | |
2608 | * those cases where the window is constrained on the sender side | |
2609 | * because the pipeline is full. | |
2610 | * | |
2611 | * BSD also seems to "accidentally" limit itself to windows that are a | |
2612 | * multiple of MSS, at least until the free space gets quite small. | |
2613 | * This would appear to be a side effect of the mbuf implementation. | |
2614 | * Combining these two algorithms results in the observed behavior | |
2615 | * of having a fixed window size at almost all times. | |
2616 | * | |
2617 | * Below we obtain similar behavior by forcing the offered window to | |
2618 | * a multiple of the mss when it is feasible to do so. | |
2619 | * | |
2620 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
2621 | * Regular options like TIMESTAMP are taken into account. | |
2622 | */ | |
2623 | u32 __tcp_select_window(struct sock *sk) | |
2624 | { | |
463c84b9 | 2625 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 2626 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 2627 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
2628 | * here. I don't know if the value based on our guesses |
2629 | * of peer's MSS is better for the performance. It's more correct | |
2630 | * but may be worse for the performance because of rcv_mss | |
2631 | * fluctuations. --SAW 1998/11/1 | |
2632 | */ | |
463c84b9 | 2633 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 | 2634 | int free_space = tcp_space(sk); |
86c1a045 FW |
2635 | int allowed_space = tcp_full_space(sk); |
2636 | int full_space = min_t(int, tp->window_clamp, allowed_space); | |
1da177e4 LT |
2637 | int window; |
2638 | ||
06425c30 | 2639 | if (unlikely(mss > full_space)) { |
e905a9ed | 2640 | mss = full_space; |
06425c30 ED |
2641 | if (mss <= 0) |
2642 | return 0; | |
2643 | } | |
b92edbe0 | 2644 | if (free_space < (full_space >> 1)) { |
463c84b9 | 2645 | icsk->icsk_ack.quick = 0; |
1da177e4 | 2646 | |
b8da51eb | 2647 | if (tcp_under_memory_pressure(sk)) |
056834d9 IJ |
2648 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, |
2649 | 4U * tp->advmss); | |
1da177e4 | 2650 | |
86c1a045 FW |
2651 | /* free_space might become our new window, make sure we don't |
2652 | * increase it due to wscale. | |
2653 | */ | |
2654 | free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); | |
2655 | ||
2656 | /* if free space is less than mss estimate, or is below 1/16th | |
2657 | * of the maximum allowed, try to move to zero-window, else | |
2658 | * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and | |
2659 | * new incoming data is dropped due to memory limits. | |
2660 | * With large window, mss test triggers way too late in order | |
2661 | * to announce zero window in time before rmem limit kicks in. | |
2662 | */ | |
2663 | if (free_space < (allowed_space >> 4) || free_space < mss) | |
1da177e4 LT |
2664 | return 0; |
2665 | } | |
2666 | ||
2667 | if (free_space > tp->rcv_ssthresh) | |
2668 | free_space = tp->rcv_ssthresh; | |
2669 | ||
2670 | /* Don't do rounding if we are using window scaling, since the | |
2671 | * scaled window will not line up with the MSS boundary anyway. | |
2672 | */ | |
1da177e4 LT |
2673 | if (tp->rx_opt.rcv_wscale) { |
2674 | window = free_space; | |
2675 | ||
2676 | /* Advertise enough space so that it won't get scaled away. | |
2677 | * Import case: prevent zero window announcement if | |
2678 | * 1<<rcv_wscale > mss. | |
2679 | */ | |
1935299d | 2680 | window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); |
1da177e4 | 2681 | } else { |
1935299d | 2682 | window = tp->rcv_wnd; |
1da177e4 LT |
2683 | /* Get the largest window that is a nice multiple of mss. |
2684 | * Window clamp already applied above. | |
2685 | * If our current window offering is within 1 mss of the | |
2686 | * free space we just keep it. This prevents the divide | |
2687 | * and multiply from happening most of the time. | |
2688 | * We also don't do any window rounding when the free space | |
2689 | * is too small. | |
2690 | */ | |
2691 | if (window <= free_space - mss || window > free_space) | |
1935299d | 2692 | window = rounddown(free_space, mss); |
84565070 | 2693 | else if (mss == full_space && |
b92edbe0 | 2694 | free_space > window + (full_space >> 1)) |
84565070 | 2695 | window = free_space; |
1da177e4 LT |
2696 | } |
2697 | ||
2698 | return window; | |
2699 | } | |
2700 | ||
cfea5a68 MKL |
2701 | void tcp_skb_collapse_tstamp(struct sk_buff *skb, |
2702 | const struct sk_buff *next_skb) | |
082ac2d5 | 2703 | { |
0a2cf20c SHY |
2704 | if (unlikely(tcp_has_tx_tstamp(next_skb))) { |
2705 | const struct skb_shared_info *next_shinfo = | |
2706 | skb_shinfo(next_skb); | |
082ac2d5 MKL |
2707 | struct skb_shared_info *shinfo = skb_shinfo(skb); |
2708 | ||
0a2cf20c | 2709 | shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; |
082ac2d5 | 2710 | shinfo->tskey = next_shinfo->tskey; |
2de8023e MKL |
2711 | TCP_SKB_CB(skb)->txstamp_ack |= |
2712 | TCP_SKB_CB(next_skb)->txstamp_ack; | |
082ac2d5 MKL |
2713 | } |
2714 | } | |
2715 | ||
4a17fc3a | 2716 | /* Collapses two adjacent SKB's during retransmission. */ |
f8071cde | 2717 | static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) |
1da177e4 LT |
2718 | { |
2719 | struct tcp_sock *tp = tcp_sk(sk); | |
75c119af | 2720 | struct sk_buff *next_skb = skb_rb_next(skb); |
13dde04f | 2721 | int next_skb_size; |
1da177e4 | 2722 | |
058dc334 | 2723 | next_skb_size = next_skb->len; |
1da177e4 | 2724 | |
058dc334 | 2725 | BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
a6963a6b | 2726 | |
f8071cde ED |
2727 | if (next_skb_size) { |
2728 | if (next_skb_size <= skb_availroom(skb)) | |
2729 | skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), | |
2730 | next_skb_size); | |
2731 | else if (!skb_shift(skb, next_skb, next_skb_size)) | |
2732 | return false; | |
2733 | } | |
2b7cda9c | 2734 | tcp_highest_sack_replace(sk, next_skb, skb); |
1da177e4 | 2735 | |
058dc334 IJ |
2736 | /* Update sequence range on original skb. */ |
2737 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1da177e4 | 2738 | |
e6c7d085 | 2739 | /* Merge over control information. This moves PSH/FIN etc. over */ |
4de075e0 | 2740 | TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
058dc334 IJ |
2741 | |
2742 | /* All done, get rid of second SKB and account for it so | |
2743 | * packet counting does not break. | |
2744 | */ | |
2745 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; | |
a643b5d4 | 2746 | TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; |
058dc334 IJ |
2747 | |
2748 | /* changed transmit queue under us so clear hints */ | |
ef9da47c IJ |
2749 | tcp_clear_retrans_hints_partial(tp); |
2750 | if (next_skb == tp->retransmit_skb_hint) | |
2751 | tp->retransmit_skb_hint = skb; | |
058dc334 | 2752 | |
797108d1 IJ |
2753 | tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
2754 | ||
082ac2d5 MKL |
2755 | tcp_skb_collapse_tstamp(skb, next_skb); |
2756 | ||
75c119af | 2757 | tcp_rtx_queue_unlink_and_free(next_skb, sk); |
f8071cde | 2758 | return true; |
1da177e4 LT |
2759 | } |
2760 | ||
67edfef7 | 2761 | /* Check if coalescing SKBs is legal. */ |
a2a385d6 | 2762 | static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
4a17fc3a IJ |
2763 | { |
2764 | if (tcp_skb_pcount(skb) > 1) | |
a2a385d6 | 2765 | return false; |
4a17fc3a | 2766 | if (skb_cloned(skb)) |
a2a385d6 | 2767 | return false; |
2331ccc5 | 2768 | /* Some heuristics for collapsing over SACK'd could be invented */ |
4a17fc3a | 2769 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) |
a2a385d6 | 2770 | return false; |
4a17fc3a | 2771 | |
a2a385d6 | 2772 | return true; |
4a17fc3a IJ |
2773 | } |
2774 | ||
67edfef7 AK |
2775 | /* Collapse packets in the retransmit queue to make to create |
2776 | * less packets on the wire. This is only done on retransmission. | |
2777 | */ | |
4a17fc3a IJ |
2778 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
2779 | int space) | |
2780 | { | |
2781 | struct tcp_sock *tp = tcp_sk(sk); | |
2782 | struct sk_buff *skb = to, *tmp; | |
a2a385d6 | 2783 | bool first = true; |
4a17fc3a | 2784 | |
e0a1e5b5 | 2785 | if (!sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse) |
4a17fc3a | 2786 | return; |
4de075e0 | 2787 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
4a17fc3a IJ |
2788 | return; |
2789 | ||
75c119af | 2790 | skb_rbtree_walk_from_safe(skb, tmp) { |
4a17fc3a IJ |
2791 | if (!tcp_can_collapse(sk, skb)) |
2792 | break; | |
2793 | ||
a643b5d4 MKL |
2794 | if (!tcp_skb_can_collapse_to(to)) |
2795 | break; | |
2796 | ||
4a17fc3a IJ |
2797 | space -= skb->len; |
2798 | ||
2799 | if (first) { | |
a2a385d6 | 2800 | first = false; |
4a17fc3a IJ |
2801 | continue; |
2802 | } | |
2803 | ||
2804 | if (space < 0) | |
2805 | break; | |
4a17fc3a IJ |
2806 | |
2807 | if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) | |
2808 | break; | |
2809 | ||
f8071cde ED |
2810 | if (!tcp_collapse_retrans(sk, to)) |
2811 | break; | |
4a17fc3a IJ |
2812 | } |
2813 | } | |
2814 | ||
1da177e4 LT |
2815 | /* This retransmits one SKB. Policy decisions and retransmit queue |
2816 | * state updates are done by the caller. Returns non-zero if an | |
2817 | * error occurred which prevented the send. | |
2818 | */ | |
10d3be56 | 2819 | int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) |
1da177e4 | 2820 | { |
5d424d5a | 2821 | struct inet_connection_sock *icsk = inet_csk(sk); |
10d3be56 | 2822 | struct tcp_sock *tp = tcp_sk(sk); |
7d227cd2 | 2823 | unsigned int cur_mss; |
10d3be56 ED |
2824 | int diff, len, err; |
2825 | ||
1da177e4 | 2826 | |
10d3be56 ED |
2827 | /* Inconclusive MTU probe */ |
2828 | if (icsk->icsk_mtup.probe_size) | |
5d424d5a | 2829 | icsk->icsk_mtup.probe_size = 0; |
5d424d5a | 2830 | |
1da177e4 | 2831 | /* Do not sent more than we queued. 1/4 is reserved for possible |
caa20d9a | 2832 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 | 2833 | */ |
14afee4b | 2834 | if (refcount_read(&sk->sk_wmem_alloc) > |
ffb4d6c8 ED |
2835 | min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), |
2836 | sk->sk_sndbuf)) | |
1da177e4 LT |
2837 | return -EAGAIN; |
2838 | ||
1f3279ae ED |
2839 | if (skb_still_in_host_queue(sk, skb)) |
2840 | return -EBUSY; | |
2841 | ||
1da177e4 | 2842 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { |
7f582b24 ED |
2843 | if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { |
2844 | WARN_ON_ONCE(1); | |
2845 | return -EINVAL; | |
2846 | } | |
1da177e4 LT |
2847 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
2848 | return -ENOMEM; | |
2849 | } | |
2850 | ||
7d227cd2 SS |
2851 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
2852 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
2853 | ||
0c54b85f | 2854 | cur_mss = tcp_current_mss(sk); |
7d227cd2 | 2855 | |
1da177e4 LT |
2856 | /* If receiver has shrunk his window, and skb is out of |
2857 | * new window, do not retransmit it. The exception is the | |
2858 | * case, when window is shrunk to zero. In this case | |
2859 | * our retransmit serves as a zero window probe. | |
2860 | */ | |
9d4fb27d JP |
2861 | if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && |
2862 | TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1da177e4 LT |
2863 | return -EAGAIN; |
2864 | ||
10d3be56 ED |
2865 | len = cur_mss * segs; |
2866 | if (skb->len > len) { | |
75c119af ED |
2867 | if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, |
2868 | cur_mss, GFP_ATOMIC)) | |
1da177e4 | 2869 | return -ENOMEM; /* We'll try again later. */ |
02276f3c | 2870 | } else { |
10d3be56 ED |
2871 | if (skb_unclone(skb, GFP_ATOMIC)) |
2872 | return -ENOMEM; | |
9eb9362e | 2873 | |
10d3be56 ED |
2874 | diff = tcp_skb_pcount(skb); |
2875 | tcp_set_skb_tso_segs(skb, cur_mss); | |
2876 | diff -= tcp_skb_pcount(skb); | |
2877 | if (diff) | |
2878 | tcp_adjust_pcount(sk, skb, diff); | |
2879 | if (skb->len < cur_mss) | |
2880 | tcp_retrans_try_collapse(sk, skb, cur_mss); | |
1da177e4 LT |
2881 | } |
2882 | ||
49213555 DB |
2883 | /* RFC3168, section 6.1.1.1. ECN fallback */ |
2884 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) | |
2885 | tcp_ecn_clear_syn(sk, skb); | |
2886 | ||
678550c6 YC |
2887 | /* Update global and local TCP statistics. */ |
2888 | segs = tcp_skb_pcount(skb); | |
2889 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); | |
2890 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) | |
2891 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
2892 | tp->total_retrans += segs; | |
fb31c9b9 | 2893 | tp->bytes_retrans += skb->len; |
678550c6 | 2894 | |
50bceae9 TG |
2895 | /* make sure skb->data is aligned on arches that require it |
2896 | * and check if ack-trimming & collapsing extended the headroom | |
2897 | * beyond what csum_start can cover. | |
2898 | */ | |
2899 | if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || | |
2900 | skb_headroom(skb) >= 0xFFFF)) { | |
10a81980 ED |
2901 | struct sk_buff *nskb; |
2902 | ||
e2080072 ED |
2903 | tcp_skb_tsorted_save(skb) { |
2904 | nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); | |
2905 | err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : | |
2906 | -ENOBUFS; | |
2907 | } tcp_skb_tsorted_restore(skb); | |
2908 | ||
5889e2c0 | 2909 | if (!err) { |
ab408b6d | 2910 | tcp_update_skb_after_send(sk, skb); |
5889e2c0 YS |
2911 | tcp_rate_skb_sent(sk, skb); |
2912 | } | |
117632e6 | 2913 | } else { |
c84a5711 | 2914 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
117632e6 | 2915 | } |
c84a5711 | 2916 | |
a31ad29e LB |
2917 | if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) |
2918 | tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, | |
2919 | TCP_SKB_CB(skb)->seq, segs, err); | |
2920 | ||
fc9f3501 | 2921 | if (likely(!err)) { |
c84a5711 | 2922 | TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; |
e086101b | 2923 | trace_tcp_retransmit_skb(sk, skb); |
678550c6 YC |
2924 | } else if (err != -EBUSY) { |
2925 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); | |
fc9f3501 | 2926 | } |
c84a5711 | 2927 | return err; |
93b174ad YC |
2928 | } |
2929 | ||
10d3be56 | 2930 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) |
93b174ad YC |
2931 | { |
2932 | struct tcp_sock *tp = tcp_sk(sk); | |
10d3be56 | 2933 | int err = __tcp_retransmit_skb(sk, skb, segs); |
1da177e4 LT |
2934 | |
2935 | if (err == 0) { | |
1da177e4 | 2936 | #if FASTRETRANS_DEBUG > 0 |
056834d9 | 2937 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
e87cc472 | 2938 | net_dbg_ratelimited("retrans_out leaked\n"); |
1da177e4 LT |
2939 | } |
2940 | #endif | |
2941 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; | |
2942 | tp->retrans_out += tcp_skb_pcount(skb); | |
2943 | ||
2944 | /* Save stamp of the first retransmit. */ | |
2945 | if (!tp->retrans_stamp) | |
7faee5c0 | 2946 | tp->retrans_stamp = tcp_skb_timestamp(skb); |
1da177e4 | 2947 | |
1da177e4 | 2948 | } |
6e08d5e3 YC |
2949 | |
2950 | if (tp->undo_retrans < 0) | |
2951 | tp->undo_retrans = 0; | |
2952 | tp->undo_retrans += tcp_skb_pcount(skb); | |
1da177e4 LT |
2953 | return err; |
2954 | } | |
2955 | ||
2956 | /* This gets called after a retransmit timeout, and the initially | |
2957 | * retransmitted data is acknowledged. It tries to continue | |
2958 | * resending the rest of the retransmit queue, until either | |
2959 | * we've sent it all or the congestion window limit is reached. | |
1da177e4 LT |
2960 | */ |
2961 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
2962 | { | |
6687e988 | 2963 | const struct inet_connection_sock *icsk = inet_csk(sk); |
b9f1f1ce | 2964 | struct sk_buff *skb, *rtx_head, *hole = NULL; |
1da177e4 | 2965 | struct tcp_sock *tp = tcp_sk(sk); |
840a3cbe | 2966 | u32 max_segs; |
61eb55f4 | 2967 | int mib_idx; |
6a438bbe | 2968 | |
45e77d31 IJ |
2969 | if (!tp->packets_out) |
2970 | return; | |
2971 | ||
b9f1f1ce ED |
2972 | rtx_head = tcp_rtx_queue_head(sk); |
2973 | skb = tp->retransmit_skb_hint ?: rtx_head; | |
ed6e7268 | 2974 | max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); |
75c119af | 2975 | skb_rbtree_walk_from(skb) { |
dca0aaf8 | 2976 | __u8 sacked; |
10d3be56 | 2977 | int segs; |
1da177e4 | 2978 | |
218af599 ED |
2979 | if (tcp_pacing_check(sk)) |
2980 | break; | |
2981 | ||
08ebd172 | 2982 | /* we could do better than to assign each time */ |
51456b29 | 2983 | if (!hole) |
0e1c54c2 | 2984 | tp->retransmit_skb_hint = skb; |
08ebd172 | 2985 | |
10d3be56 ED |
2986 | segs = tp->snd_cwnd - tcp_packets_in_flight(tp); |
2987 | if (segs <= 0) | |
08ebd172 | 2988 | return; |
dca0aaf8 | 2989 | sacked = TCP_SKB_CB(skb)->sacked; |
a3d2e9f8 ED |
2990 | /* In case tcp_shift_skb_data() have aggregated large skbs, |
2991 | * we need to make sure not sending too bigs TSO packets | |
2992 | */ | |
2993 | segs = min_t(int, segs, max_segs); | |
1da177e4 | 2994 | |
840a3cbe YC |
2995 | if (tp->retrans_out >= tp->lost_out) { |
2996 | break; | |
0e1c54c2 | 2997 | } else if (!(sacked & TCPCB_LOST)) { |
51456b29 | 2998 | if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
0e1c54c2 IJ |
2999 | hole = skb; |
3000 | continue; | |
1da177e4 | 3001 | |
0e1c54c2 IJ |
3002 | } else { |
3003 | if (icsk->icsk_ca_state != TCP_CA_Loss) | |
3004 | mib_idx = LINUX_MIB_TCPFASTRETRANS; | |
3005 | else | |
3006 | mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; | |
3007 | } | |
1da177e4 | 3008 | |
0e1c54c2 | 3009 | if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
1da177e4 LT |
3010 | continue; |
3011 | ||
f9616c35 ED |
3012 | if (tcp_small_queue_check(sk, skb, 1)) |
3013 | return; | |
3014 | ||
10d3be56 | 3015 | if (tcp_retransmit_skb(sk, skb, segs)) |
0e1c54c2 | 3016 | return; |
24ab6bec | 3017 | |
de1d6578 | 3018 | NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); |
1da177e4 | 3019 | |
684bad11 | 3020 | if (tcp_in_cwnd_reduction(sk)) |
a262f0cd ND |
3021 | tp->prr_out += tcp_skb_pcount(skb); |
3022 | ||
75c119af | 3023 | if (skb == rtx_head && |
57dde7f7 | 3024 | icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) |
3f421baa ACM |
3025 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3026 | inet_csk(sk)->icsk_rto, | |
3027 | TCP_RTO_MAX); | |
1da177e4 LT |
3028 | } |
3029 | } | |
3030 | ||
d83769a5 ED |
3031 | /* We allow to exceed memory limits for FIN packets to expedite |
3032 | * connection tear down and (memory) recovery. | |
845704a5 ED |
3033 | * Otherwise tcp_send_fin() could be tempted to either delay FIN |
3034 | * or even be forced to close flow without any FIN. | |
a6c5ea4c ED |
3035 | * In general, we want to allow one skb per socket to avoid hangs |
3036 | * with edge trigger epoll() | |
d83769a5 | 3037 | */ |
a6c5ea4c | 3038 | void sk_forced_mem_schedule(struct sock *sk, int size) |
d83769a5 | 3039 | { |
e805605c | 3040 | int amt; |
d83769a5 ED |
3041 | |
3042 | if (size <= sk->sk_forward_alloc) | |
3043 | return; | |
3044 | amt = sk_mem_pages(size); | |
3045 | sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; | |
e805605c JW |
3046 | sk_memory_allocated_add(sk, amt); |
3047 | ||
baac50bb JW |
3048 | if (mem_cgroup_sockets_enabled && sk->sk_memcg) |
3049 | mem_cgroup_charge_skmem(sk->sk_memcg, amt); | |
d83769a5 ED |
3050 | } |
3051 | ||
845704a5 ED |
3052 | /* Send a FIN. The caller locks the socket for us. |
3053 | * We should try to send a FIN packet really hard, but eventually give up. | |
1da177e4 LT |
3054 | */ |
3055 | void tcp_send_fin(struct sock *sk) | |
3056 | { | |
845704a5 | 3057 | struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); |
e905a9ed | 3058 | struct tcp_sock *tp = tcp_sk(sk); |
e905a9ed | 3059 | |
845704a5 ED |
3060 | /* Optimization, tack on the FIN if we have one skb in write queue and |
3061 | * this skb was not yet sent, or we are under memory pressure. | |
3062 | * Note: in the latter case, FIN packet will be sent after a timeout, | |
3063 | * as TCP stack thinks it has already been transmitted. | |
1da177e4 | 3064 | */ |
75c119af ED |
3065 | if (!tskb && tcp_under_memory_pressure(sk)) |
3066 | tskb = skb_rb_last(&sk->tcp_rtx_queue); | |
3067 | ||
3068 | if (tskb) { | |
845704a5 ED |
3069 | coalesce: |
3070 | TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; | |
3071 | TCP_SKB_CB(tskb)->end_seq++; | |
1da177e4 | 3072 | tp->write_seq++; |
75c119af | 3073 | if (tcp_write_queue_empty(sk)) { |
845704a5 ED |
3074 | /* This means tskb was already sent. |
3075 | * Pretend we included the FIN on previous transmit. | |
3076 | * We need to set tp->snd_nxt to the value it would have | |
3077 | * if FIN had been sent. This is because retransmit path | |
3078 | * does not change tp->snd_nxt. | |
3079 | */ | |
3080 | tp->snd_nxt++; | |
3081 | return; | |
3082 | } | |
1da177e4 | 3083 | } else { |
845704a5 ED |
3084 | skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); |
3085 | if (unlikely(!skb)) { | |
3086 | if (tskb) | |
3087 | goto coalesce; | |
3088 | return; | |
1da177e4 | 3089 | } |
e2080072 | 3090 | INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); |
d83769a5 | 3091 | skb_reserve(skb, MAX_TCP_HEADER); |
a6c5ea4c | 3092 | sk_forced_mem_schedule(sk, skb->truesize); |
1da177e4 | 3093 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
e870a8ef | 3094 | tcp_init_nondata_skb(skb, tp->write_seq, |
a3433f35 | 3095 | TCPHDR_ACK | TCPHDR_FIN); |
1da177e4 LT |
3096 | tcp_queue_skb(sk, skb); |
3097 | } | |
845704a5 | 3098 | __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); |
1da177e4 LT |
3099 | } |
3100 | ||
3101 | /* We get here when a process closes a file descriptor (either due to | |
3102 | * an explicit close() or as a byproduct of exit()'ing) and there | |
3103 | * was unread data in the receive queue. This behavior is recommended | |
65bb723c | 3104 | * by RFC 2525, section 2.17. -DaveM |
1da177e4 | 3105 | */ |
dd0fc66f | 3106 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 | 3107 | { |
1da177e4 LT |
3108 | struct sk_buff *skb; |
3109 | ||
7cc2b043 GF |
3110 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
3111 | ||
1da177e4 LT |
3112 | /* NOTE: No TCP options attached and we never retransmit this. */ |
3113 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
3114 | if (!skb) { | |
4e673444 | 3115 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
1da177e4 LT |
3116 | return; |
3117 | } | |
3118 | ||
3119 | /* Reserve space for headers and prepare control bits. */ | |
3120 | skb_reserve(skb, MAX_TCP_HEADER); | |
e870a8ef | 3121 | tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
a3433f35 | 3122 | TCPHDR_ACK | TCPHDR_RST); |
9a568de4 | 3123 | tcp_mstamp_refresh(tcp_sk(sk)); |
1da177e4 | 3124 | /* Send it off. */ |
dfb4b9dc | 3125 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
4e673444 | 3126 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
c24b14c4 SL |
3127 | |
3128 | /* skb of trace_tcp_send_reset() keeps the skb that caused RST, | |
3129 | * skb here is different to the troublesome skb, so use NULL | |
3130 | */ | |
3131 | trace_tcp_send_reset(sk, NULL); | |
1da177e4 LT |
3132 | } |
3133 | ||
67edfef7 AK |
3134 | /* Send a crossed SYN-ACK during socket establishment. |
3135 | * WARNING: This routine must only be called when we have already sent | |
1da177e4 LT |
3136 | * a SYN packet that crossed the incoming SYN that caused this routine |
3137 | * to get called. If this assumption fails then the initial rcv_wnd | |
3138 | * and rcv_wscale values will not be correct. | |
3139 | */ | |
3140 | int tcp_send_synack(struct sock *sk) | |
3141 | { | |
056834d9 | 3142 | struct sk_buff *skb; |
1da177e4 | 3143 | |
75c119af | 3144 | skb = tcp_rtx_queue_head(sk); |
51456b29 | 3145 | if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
75c119af | 3146 | pr_err("%s: wrong queue state\n", __func__); |
1da177e4 LT |
3147 | return -EFAULT; |
3148 | } | |
4de075e0 | 3149 | if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
1da177e4 | 3150 | if (skb_cloned(skb)) { |
e2080072 ED |
3151 | struct sk_buff *nskb; |
3152 | ||
3153 | tcp_skb_tsorted_save(skb) { | |
3154 | nskb = skb_copy(skb, GFP_ATOMIC); | |
3155 | } tcp_skb_tsorted_restore(skb); | |
51456b29 | 3156 | if (!nskb) |
1da177e4 | 3157 | return -ENOMEM; |
e2080072 | 3158 | INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); |
75c119af | 3159 | tcp_rtx_queue_unlink_and_free(skb, sk); |
f4a775d1 | 3160 | __skb_header_release(nskb); |
75c119af | 3161 | tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); |
3ab224be HA |
3162 | sk->sk_wmem_queued += nskb->truesize; |
3163 | sk_mem_charge(sk, nskb->truesize); | |
1da177e4 LT |
3164 | skb = nskb; |
3165 | } | |
3166 | ||
4de075e0 | 3167 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
735d3831 | 3168 | tcp_ecn_send_synack(sk, skb); |
1da177e4 | 3169 | } |
dfb4b9dc | 3170 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
3171 | } |
3172 | ||
4aea39c1 ED |
3173 | /** |
3174 | * tcp_make_synack - Prepare a SYN-ACK. | |
3175 | * sk: listener socket | |
3176 | * dst: dst entry attached to the SYNACK | |
3177 | * req: request_sock pointer | |
4aea39c1 ED |
3178 | * |
3179 | * Allocate one skb and build a SYNACK packet. | |
3180 | * @dst is consumed : Caller should not use it again. | |
3181 | */ | |
5d062de7 | 3182 | struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, |
e6b4d113 | 3183 | struct request_sock *req, |
ca6fb065 | 3184 | struct tcp_fastopen_cookie *foc, |
b3d05147 | 3185 | enum tcp_synack_type synack_type) |
1da177e4 | 3186 | { |
2e6599cb | 3187 | struct inet_request_sock *ireq = inet_rsk(req); |
5d062de7 | 3188 | const struct tcp_sock *tp = tcp_sk(sk); |
80f03e27 | 3189 | struct tcp_md5sig_key *md5 = NULL; |
5d062de7 ED |
3190 | struct tcp_out_options opts; |
3191 | struct sk_buff *skb; | |
bd0388ae | 3192 | int tcp_header_size; |
5d062de7 | 3193 | struct tcphdr *th; |
f5fff5dc | 3194 | int mss; |
1da177e4 | 3195 | |
ca6fb065 | 3196 | skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); |
4aea39c1 ED |
3197 | if (unlikely(!skb)) { |
3198 | dst_release(dst); | |
1da177e4 | 3199 | return NULL; |
4aea39c1 | 3200 | } |
1da177e4 LT |
3201 | /* Reserve space for headers. */ |
3202 | skb_reserve(skb, MAX_TCP_HEADER); | |
3203 | ||
b3d05147 ED |
3204 | switch (synack_type) { |
3205 | case TCP_SYNACK_NORMAL: | |
9e17f8a4 | 3206 | skb_set_owner_w(skb, req_to_sk(req)); |
b3d05147 ED |
3207 | break; |
3208 | case TCP_SYNACK_COOKIE: | |
3209 | /* Under synflood, we do not attach skb to a socket, | |
3210 | * to avoid false sharing. | |
3211 | */ | |
3212 | break; | |
3213 | case TCP_SYNACK_FASTOPEN: | |
ca6fb065 ED |
3214 | /* sk is a const pointer, because we want to express multiple |
3215 | * cpu might call us concurrently. | |
3216 | * sk->sk_wmem_alloc in an atomic, we can promote to rw. | |
3217 | */ | |
3218 | skb_set_owner_w(skb, (struct sock *)sk); | |
b3d05147 | 3219 | break; |
ca6fb065 | 3220 | } |
4aea39c1 | 3221 | skb_dst_set(skb, dst); |
1da177e4 | 3222 | |
3541f9e8 | 3223 | mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
f5fff5dc | 3224 | |
33ad798c | 3225 | memset(&opts, 0, sizeof(opts)); |
8b5f12d0 FW |
3226 | #ifdef CONFIG_SYN_COOKIES |
3227 | if (unlikely(req->cookie_ts)) | |
d3edd06e | 3228 | skb->skb_mstamp_ns = cookie_init_timestamp(req); |
8b5f12d0 FW |
3229 | else |
3230 | #endif | |
d3edd06e | 3231 | skb->skb_mstamp_ns = tcp_clock_ns(); |
80f03e27 ED |
3232 | |
3233 | #ifdef CONFIG_TCP_MD5SIG | |
3234 | rcu_read_lock(); | |
fd3a154a | 3235 | md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); |
80f03e27 | 3236 | #endif |
58d607d3 | 3237 | skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); |
60e2a778 UB |
3238 | tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, |
3239 | foc) + sizeof(*th); | |
cfb6eeb4 | 3240 | |
aa8223c7 ACM |
3241 | skb_push(skb, tcp_header_size); |
3242 | skb_reset_transport_header(skb); | |
1da177e4 | 3243 | |
ea1627c2 | 3244 | th = (struct tcphdr *)skb->data; |
1da177e4 LT |
3245 | memset(th, 0, sizeof(struct tcphdr)); |
3246 | th->syn = 1; | |
3247 | th->ack = 1; | |
6ac705b1 | 3248 | tcp_ecn_make_synack(req, th); |
b44084c2 | 3249 | th->source = htons(ireq->ir_num); |
634fb979 | 3250 | th->dest = ireq->ir_rmt_port; |
e05a90ec | 3251 | skb->mark = ireq->ir_mark; |
3b117750 ED |
3252 | skb->ip_summed = CHECKSUM_PARTIAL; |
3253 | th->seq = htonl(tcp_rsk(req)->snt_isn); | |
8336886f JC |
3254 | /* XXX data is queued and acked as is. No buffer/window check */ |
3255 | th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); | |
1da177e4 LT |
3256 | |
3257 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
ed53d0ab | 3258 | th->window = htons(min(req->rsk_rcv_wnd, 65535U)); |
5d062de7 | 3259 | tcp_options_write((__be32 *)(th + 1), NULL, &opts); |
1da177e4 | 3260 | th->doff = (tcp_header_size >> 2); |
90bbcc60 | 3261 | __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); |
cfb6eeb4 YH |
3262 | |
3263 | #ifdef CONFIG_TCP_MD5SIG | |
3264 | /* Okay, we have all we need - do the md5 hash if needed */ | |
80f03e27 | 3265 | if (md5) |
bd0388ae | 3266 | tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
39f8e58e | 3267 | md5, req_to_sk(req), skb); |
80f03e27 | 3268 | rcu_read_unlock(); |
cfb6eeb4 YH |
3269 | #endif |
3270 | ||
b50edd78 | 3271 | /* Do not fool tcpdump (if any), clean our debris */ |
2456e855 | 3272 | skb->tstamp = 0; |
1da177e4 LT |
3273 | return skb; |
3274 | } | |
4bc2f18b | 3275 | EXPORT_SYMBOL(tcp_make_synack); |
1da177e4 | 3276 | |
81164413 DB |
3277 | static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) |
3278 | { | |
3279 | struct inet_connection_sock *icsk = inet_csk(sk); | |
3280 | const struct tcp_congestion_ops *ca; | |
3281 | u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); | |
3282 | ||
3283 | if (ca_key == TCP_CA_UNSPEC) | |
3284 | return; | |
3285 | ||
3286 | rcu_read_lock(); | |
3287 | ca = tcp_ca_find_key(ca_key); | |
3288 | if (likely(ca && try_module_get(ca->owner))) { | |
3289 | module_put(icsk->icsk_ca_ops->owner); | |
3290 | icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); | |
3291 | icsk->icsk_ca_ops = ca; | |
3292 | } | |
3293 | rcu_read_unlock(); | |
3294 | } | |
3295 | ||
67edfef7 | 3296 | /* Do all connect socket setups that can be done AF independent. */ |
f7e56a76 | 3297 | static void tcp_connect_init(struct sock *sk) |
1da177e4 | 3298 | { |
cf533ea5 | 3299 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
3300 | struct tcp_sock *tp = tcp_sk(sk); |
3301 | __u8 rcv_wscale; | |
13d3b1eb | 3302 | u32 rcv_wnd; |
1da177e4 LT |
3303 | |
3304 | /* We'll fix this up when we get a response from the other end. | |
3305 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
3306 | */ | |
5d2ed052 ED |
3307 | tp->tcp_header_len = sizeof(struct tcphdr); |
3308 | if (sock_net(sk)->ipv4.sysctl_tcp_timestamps) | |
3309 | tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; | |
1da177e4 | 3310 | |
cfb6eeb4 | 3311 | #ifdef CONFIG_TCP_MD5SIG |
00db4124 | 3312 | if (tp->af_specific->md5_lookup(sk, sk)) |
cfb6eeb4 YH |
3313 | tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; |
3314 | #endif | |
3315 | ||
1da177e4 LT |
3316 | /* If user gave his TCP_MAXSEG, record it to clamp */ |
3317 | if (tp->rx_opt.user_mss) | |
3318 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
3319 | tp->max_window = 0; | |
5d424d5a | 3320 | tcp_mtup_init(sk); |
1da177e4 LT |
3321 | tcp_sync_mss(sk, dst_mtu(dst)); |
3322 | ||
81164413 DB |
3323 | tcp_ca_dst_init(sk, dst); |
3324 | ||
1da177e4 LT |
3325 | if (!tp->window_clamp) |
3326 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
3541f9e8 | 3327 | tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
f5fff5dc | 3328 | |
1da177e4 | 3329 | tcp_initialize_rcv_mss(sk); |
1da177e4 | 3330 | |
e88c64f0 HPP |
3331 | /* limit the window selection if the user enforce a smaller rx buffer */ |
3332 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
3333 | (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) | |
3334 | tp->window_clamp = tcp_full_space(sk); | |
3335 | ||
13d3b1eb LB |
3336 | rcv_wnd = tcp_rwnd_init_bpf(sk); |
3337 | if (rcv_wnd == 0) | |
3338 | rcv_wnd = dst_metric(dst, RTAX_INITRWND); | |
3339 | ||
ceef9ab6 | 3340 | tcp_select_initial_window(sk, tcp_full_space(sk), |
1da177e4 LT |
3341 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), |
3342 | &tp->rcv_wnd, | |
3343 | &tp->window_clamp, | |
9bb37ef0 | 3344 | sock_net(sk)->ipv4.sysctl_tcp_window_scaling, |
31d12926 | 3345 | &rcv_wscale, |
13d3b1eb | 3346 | rcv_wnd); |
1da177e4 LT |
3347 | |
3348 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
3349 | tp->rcv_ssthresh = tp->rcv_wnd; | |
3350 | ||
3351 | sk->sk_err = 0; | |
3352 | sock_reset_flag(sk, SOCK_DONE); | |
3353 | tp->snd_wnd = 0; | |
ee7537b6 | 3354 | tcp_init_wl(tp, 0); |
7f582b24 | 3355 | tcp_write_queue_purge(sk); |
1da177e4 LT |
3356 | tp->snd_una = tp->write_seq; |
3357 | tp->snd_sml = tp->write_seq; | |
33f5f57e | 3358 | tp->snd_up = tp->write_seq; |
370816ae | 3359 | tp->snd_nxt = tp->write_seq; |
ee995283 PE |
3360 | |
3361 | if (likely(!tp->repair)) | |
3362 | tp->rcv_nxt = 0; | |
c7781a6e | 3363 | else |
70eabf0e | 3364 | tp->rcv_tstamp = tcp_jiffies32; |
ee995283 PE |
3365 | tp->rcv_wup = tp->rcv_nxt; |
3366 | tp->copied_seq = tp->rcv_nxt; | |
1da177e4 | 3367 | |
8550f328 | 3368 | inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); |
463c84b9 | 3369 | inet_csk(sk)->icsk_retransmits = 0; |
1da177e4 LT |
3370 | tcp_clear_retrans(tp); |
3371 | } | |
3372 | ||
783237e8 YC |
3373 | static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
3374 | { | |
3375 | struct tcp_sock *tp = tcp_sk(sk); | |
3376 | struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); | |
3377 | ||
3378 | tcb->end_seq += skb->len; | |
f4a775d1 | 3379 | __skb_header_release(skb); |
783237e8 YC |
3380 | sk->sk_wmem_queued += skb->truesize; |
3381 | sk_mem_charge(sk, skb->truesize); | |
3382 | tp->write_seq = tcb->end_seq; | |
3383 | tp->packets_out += tcp_skb_pcount(skb); | |
3384 | } | |
3385 | ||
3386 | /* Build and send a SYN with data and (cached) Fast Open cookie. However, | |
3387 | * queue a data-only packet after the regular SYN, such that regular SYNs | |
3388 | * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges | |
3389 | * only the SYN sequence, the data are retransmitted in the first ACK. | |
3390 | * If cookie is not cached or other error occurs, falls back to send a | |
3391 | * regular SYN with Fast Open cookie request option. | |
3392 | */ | |
3393 | static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) | |
3394 | { | |
3395 | struct tcp_sock *tp = tcp_sk(sk); | |
3396 | struct tcp_fastopen_request *fo = tp->fastopen_req; | |
065263f4 | 3397 | int space, err = 0; |
355a901e | 3398 | struct sk_buff *syn_data; |
aab48743 | 3399 | |
67da22d2 | 3400 | tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
065263f4 | 3401 | if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) |
783237e8 YC |
3402 | goto fallback; |
3403 | ||
3404 | /* MSS for SYN-data is based on cached MSS and bounded by PMTU and | |
3405 | * user-MSS. Reserve maximum option space for middleboxes that add | |
3406 | * private TCP options. The cost is reduced data space in SYN :( | |
3407 | */ | |
3541f9e8 ED |
3408 | tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); |
3409 | ||
1b63edd6 | 3410 | space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - |
783237e8 YC |
3411 | MAX_TCP_OPTION_SPACE; |
3412 | ||
f5ddcbbb ED |
3413 | space = min_t(size_t, space, fo->size); |
3414 | ||
3415 | /* limit to order-0 allocations */ | |
3416 | space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); | |
3417 | ||
eb934478 | 3418 | syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); |
355a901e | 3419 | if (!syn_data) |
783237e8 | 3420 | goto fallback; |
355a901e ED |
3421 | syn_data->ip_summed = CHECKSUM_PARTIAL; |
3422 | memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); | |
07e100f9 ED |
3423 | if (space) { |
3424 | int copied = copy_from_iter(skb_put(syn_data, space), space, | |
3425 | &fo->data->msg_iter); | |
3426 | if (unlikely(!copied)) { | |
ba233b34 | 3427 | tcp_skb_tsorted_anchor_cleanup(syn_data); |
07e100f9 ED |
3428 | kfree_skb(syn_data); |
3429 | goto fallback; | |
3430 | } | |
3431 | if (copied != space) { | |
3432 | skb_trim(syn_data, copied); | |
3433 | space = copied; | |
3434 | } | |
57be5bda | 3435 | } |
355a901e ED |
3436 | /* No more data pending in inet_wait_for_connect() */ |
3437 | if (space == fo->size) | |
3438 | fo->data = NULL; | |
3439 | fo->copied = space; | |
783237e8 | 3440 | |
355a901e | 3441 | tcp_connect_queue_skb(sk, syn_data); |
0f87230d FY |
3442 | if (syn_data->len) |
3443 | tcp_chrono_start(sk, TCP_CHRONO_BUSY); | |
783237e8 | 3444 | |
355a901e | 3445 | err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); |
783237e8 | 3446 | |
d3edd06e | 3447 | syn->skb_mstamp_ns = syn_data->skb_mstamp_ns; |
431a9124 | 3448 | |
355a901e ED |
3449 | /* Now full SYN+DATA was cloned and sent (or not), |
3450 | * remove the SYN from the original skb (syn_data) | |
3451 | * we keep in write queue in case of a retransmit, as we | |
3452 | * also have the SYN packet (with no data) in the same queue. | |
3453 | */ | |
3454 | TCP_SKB_CB(syn_data)->seq++; | |
3455 | TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; | |
3456 | if (!err) { | |
67da22d2 | 3457 | tp->syn_data = (fo->copied > 0); |
75c119af | 3458 | tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); |
f19c29e3 | 3459 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); |
783237e8 YC |
3460 | goto done; |
3461 | } | |
783237e8 | 3462 | |
75c119af ED |
3463 | /* data was not sent, put it in write_queue */ |
3464 | __skb_queue_tail(&sk->sk_write_queue, syn_data); | |
b5b7db8d ED |
3465 | tp->packets_out -= tcp_skb_pcount(syn_data); |
3466 | ||
783237e8 YC |
3467 | fallback: |
3468 | /* Send a regular SYN with Fast Open cookie request option */ | |
3469 | if (fo->cookie.len > 0) | |
3470 | fo->cookie.len = 0; | |
3471 | err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); | |
3472 | if (err) | |
3473 | tp->syn_fastopen = 0; | |
783237e8 YC |
3474 | done: |
3475 | fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ | |
3476 | return err; | |
3477 | } | |
3478 | ||
67edfef7 | 3479 | /* Build a SYN and send it off. */ |
1da177e4 LT |
3480 | int tcp_connect(struct sock *sk) |
3481 | { | |
3482 | struct tcp_sock *tp = tcp_sk(sk); | |
3483 | struct sk_buff *buff; | |
ee586811 | 3484 | int err; |
1da177e4 | 3485 | |
de525be2 | 3486 | tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); |
8ba60924 ED |
3487 | |
3488 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) | |
3489 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
3490 | ||
1da177e4 LT |
3491 | tcp_connect_init(sk); |
3492 | ||
2b916477 AV |
3493 | if (unlikely(tp->repair)) { |
3494 | tcp_finish_connect(sk, NULL); | |
3495 | return 0; | |
3496 | } | |
3497 | ||
eb934478 | 3498 | buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); |
355a901e | 3499 | if (unlikely(!buff)) |
1da177e4 LT |
3500 | return -ENOBUFS; |
3501 | ||
a3433f35 | 3502 | tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
9a568de4 ED |
3503 | tcp_mstamp_refresh(tp); |
3504 | tp->retrans_stamp = tcp_time_stamp(tp); | |
783237e8 | 3505 | tcp_connect_queue_skb(sk, buff); |
735d3831 | 3506 | tcp_ecn_send_syn(sk, buff); |
75c119af | 3507 | tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); |
1da177e4 | 3508 | |
783237e8 YC |
3509 | /* Send off SYN; include data in Fast Open. */ |
3510 | err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : | |
3511 | tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); | |
ee586811 EP |
3512 | if (err == -ECONNREFUSED) |
3513 | return err; | |
bd37a088 WY |
3514 | |
3515 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
3516 | * in order to make this packet get counted in tcpOutSegs. | |
3517 | */ | |
3518 | tp->snd_nxt = tp->write_seq; | |
3519 | tp->pushed_seq = tp->write_seq; | |
b5b7db8d ED |
3520 | buff = tcp_send_head(sk); |
3521 | if (unlikely(buff)) { | |
3522 | tp->snd_nxt = TCP_SKB_CB(buff)->seq; | |
3523 | tp->pushed_seq = TCP_SKB_CB(buff)->seq; | |
3524 | } | |
81cc8a75 | 3525 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
1da177e4 LT |
3526 | |
3527 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
3528 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3529 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
3530 | return 0; |
3531 | } | |
4bc2f18b | 3532 | EXPORT_SYMBOL(tcp_connect); |
1da177e4 LT |
3533 | |
3534 | /* Send out a delayed ack, the caller does the policy checking | |
3535 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
3536 | * for details. | |
3537 | */ | |
3538 | void tcp_send_delayed_ack(struct sock *sk) | |
3539 | { | |
463c84b9 ACM |
3540 | struct inet_connection_sock *icsk = inet_csk(sk); |
3541 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
3542 | unsigned long timeout; |
3543 | ||
3544 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 3545 | const struct tcp_sock *tp = tcp_sk(sk); |
056834d9 | 3546 | int max_ato = HZ / 2; |
1da177e4 | 3547 | |
056834d9 IJ |
3548 | if (icsk->icsk_ack.pingpong || |
3549 | (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) | |
1da177e4 LT |
3550 | max_ato = TCP_DELACK_MAX; |
3551 | ||
3552 | /* Slow path, intersegment interval is "high". */ | |
3553 | ||
3554 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 3555 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
3556 | * directly. |
3557 | */ | |
740b0f18 ED |
3558 | if (tp->srtt_us) { |
3559 | int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), | |
3560 | TCP_DELACK_MIN); | |
1da177e4 LT |
3561 | |
3562 | if (rtt < max_ato) | |
3563 | max_ato = rtt; | |
3564 | } | |
3565 | ||
3566 | ato = min(ato, max_ato); | |
3567 | } | |
3568 | ||
3569 | /* Stay within the limit we were given */ | |
3570 | timeout = jiffies + ato; | |
3571 | ||
3572 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 3573 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
3574 | /* If delack timer was blocked or is about to expire, |
3575 | * send ACK now. | |
3576 | */ | |
463c84b9 ACM |
3577 | if (icsk->icsk_ack.blocked || |
3578 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
3579 | tcp_send_ack(sk); |
3580 | return; | |
3581 | } | |
3582 | ||
463c84b9 ACM |
3583 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
3584 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 3585 | } |
463c84b9 ACM |
3586 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
3587 | icsk->icsk_ack.timeout = timeout; | |
3588 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
3589 | } |
3590 | ||
3591 | /* This routine sends an ack and also updates the window. */ | |
2987babb | 3592 | void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) |
1da177e4 | 3593 | { |
058dc334 | 3594 | struct sk_buff *buff; |
1da177e4 | 3595 | |
058dc334 IJ |
3596 | /* If we have been reset, we may not send again. */ |
3597 | if (sk->sk_state == TCP_CLOSE) | |
3598 | return; | |
1da177e4 | 3599 | |
058dc334 IJ |
3600 | /* We are not putting this on the write queue, so |
3601 | * tcp_transmit_skb() will set the ownership to this | |
3602 | * sock. | |
3603 | */ | |
7450aaf6 ED |
3604 | buff = alloc_skb(MAX_TCP_HEADER, |
3605 | sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); | |
3606 | if (unlikely(!buff)) { | |
058dc334 IJ |
3607 | inet_csk_schedule_ack(sk); |
3608 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3609 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, | |
3610 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
3611 | return; | |
1da177e4 | 3612 | } |
058dc334 IJ |
3613 | |
3614 | /* Reserve space for headers and prepare control bits. */ | |
3615 | skb_reserve(buff, MAX_TCP_HEADER); | |
a3433f35 | 3616 | tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
058dc334 | 3617 | |
98781965 ED |
3618 | /* We do not want pure acks influencing TCP Small Queues or fq/pacing |
3619 | * too much. | |
3620 | * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 | |
98781965 ED |
3621 | */ |
3622 | skb_set_tcp_pure_ack(buff); | |
3623 | ||
058dc334 | 3624 | /* Send it off, this clears delayed acks for us. */ |
2987babb YC |
3625 | __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); |
3626 | } | |
27cde44a | 3627 | EXPORT_SYMBOL_GPL(__tcp_send_ack); |
2987babb YC |
3628 | |
3629 | void tcp_send_ack(struct sock *sk) | |
3630 | { | |
3631 | __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); | |
1da177e4 LT |
3632 | } |
3633 | ||
3634 | /* This routine sends a packet with an out of date sequence | |
3635 | * number. It assumes the other end will try to ack it. | |
3636 | * | |
3637 | * Question: what should we make while urgent mode? | |
3638 | * 4.4BSD forces sending single byte of data. We cannot send | |
3639 | * out of window data, because we have SND.NXT==SND.MAX... | |
3640 | * | |
3641 | * Current solution: to send TWO zero-length segments in urgent mode: | |
3642 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
3643 | * out-of-date with SND.UNA-1 to probe window. | |
3644 | */ | |
e520af48 | 3645 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) |
1da177e4 LT |
3646 | { |
3647 | struct tcp_sock *tp = tcp_sk(sk); | |
3648 | struct sk_buff *skb; | |
3649 | ||
3650 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
7450aaf6 ED |
3651 | skb = alloc_skb(MAX_TCP_HEADER, |
3652 | sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); | |
51456b29 | 3653 | if (!skb) |
1da177e4 LT |
3654 | return -1; |
3655 | ||
3656 | /* Reserve space for headers and set control bits. */ | |
3657 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 LT |
3658 | /* Use a previous sequence. This should cause the other |
3659 | * end to send an ack. Don't queue or clone SKB, just | |
3660 | * send it. | |
3661 | */ | |
a3433f35 | 3662 | tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
e2e8009f | 3663 | NET_INC_STATS(sock_net(sk), mib); |
7450aaf6 | 3664 | return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); |
1da177e4 LT |
3665 | } |
3666 | ||
385e2070 | 3667 | /* Called from setsockopt( ... TCP_REPAIR ) */ |
ee995283 PE |
3668 | void tcp_send_window_probe(struct sock *sk) |
3669 | { | |
3670 | if (sk->sk_state == TCP_ESTABLISHED) { | |
3671 | tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; | |
9a568de4 | 3672 | tcp_mstamp_refresh(tcp_sk(sk)); |
e520af48 | 3673 | tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); |
ee995283 PE |
3674 | } |
3675 | } | |
3676 | ||
67edfef7 | 3677 | /* Initiate keepalive or window probe from timer. */ |
e520af48 | 3678 | int tcp_write_wakeup(struct sock *sk, int mib) |
1da177e4 | 3679 | { |
058dc334 IJ |
3680 | struct tcp_sock *tp = tcp_sk(sk); |
3681 | struct sk_buff *skb; | |
1da177e4 | 3682 | |
058dc334 IJ |
3683 | if (sk->sk_state == TCP_CLOSE) |
3684 | return -1; | |
3685 | ||
00db4124 IM |
3686 | skb = tcp_send_head(sk); |
3687 | if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { | |
058dc334 | 3688 | int err; |
0c54b85f | 3689 | unsigned int mss = tcp_current_mss(sk); |
058dc334 IJ |
3690 | unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
3691 | ||
3692 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
3693 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
3694 | ||
3695 | /* We are probing the opening of a window | |
3696 | * but the window size is != 0 | |
3697 | * must have been a result SWS avoidance ( sender ) | |
3698 | */ | |
3699 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
3700 | skb->len > mss) { | |
3701 | seg_size = min(seg_size, mss); | |
4de075e0 | 3702 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
75c119af ED |
3703 | if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
3704 | skb, seg_size, mss, GFP_ATOMIC)) | |
058dc334 IJ |
3705 | return -1; |
3706 | } else if (!tcp_skb_pcount(skb)) | |
5bbb432c | 3707 | tcp_set_skb_tso_segs(skb, mss); |
058dc334 | 3708 | |
4de075e0 | 3709 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3710 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
3711 | if (!err) | |
3712 | tcp_event_new_data_sent(sk, skb); | |
3713 | return err; | |
3714 | } else { | |
33f5f57e | 3715 | if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
e520af48 ED |
3716 | tcp_xmit_probe_skb(sk, 1, mib); |
3717 | return tcp_xmit_probe_skb(sk, 0, mib); | |
1da177e4 | 3718 | } |
1da177e4 LT |
3719 | } |
3720 | ||
3721 | /* A window probe timeout has occurred. If window is not closed send | |
3722 | * a partial packet else a zero probe. | |
3723 | */ | |
3724 | void tcp_send_probe0(struct sock *sk) | |
3725 | { | |
463c84b9 | 3726 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 3727 | struct tcp_sock *tp = tcp_sk(sk); |
c6214a97 | 3728 | struct net *net = sock_net(sk); |
fcdd1cf4 | 3729 | unsigned long probe_max; |
1da177e4 LT |
3730 | int err; |
3731 | ||
e520af48 | 3732 | err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); |
1da177e4 | 3733 | |
75c119af | 3734 | if (tp->packets_out || tcp_write_queue_empty(sk)) { |
1da177e4 | 3735 | /* Cancel probe timer, if it is not required. */ |
6687e988 | 3736 | icsk->icsk_probes_out = 0; |
463c84b9 | 3737 | icsk->icsk_backoff = 0; |
1da177e4 LT |
3738 | return; |
3739 | } | |
3740 | ||
3741 | if (err <= 0) { | |
c6214a97 | 3742 | if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) |
463c84b9 | 3743 | icsk->icsk_backoff++; |
6687e988 | 3744 | icsk->icsk_probes_out++; |
fcdd1cf4 | 3745 | probe_max = TCP_RTO_MAX; |
1da177e4 LT |
3746 | } else { |
3747 | /* If packet was not sent due to local congestion, | |
6687e988 | 3748 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
3749 | * Let local senders to fight for local resources. |
3750 | * | |
3751 | * Use accumulated backoff yet. | |
3752 | */ | |
6687e988 ACM |
3753 | if (!icsk->icsk_probes_out) |
3754 | icsk->icsk_probes_out = 1; | |
fcdd1cf4 | 3755 | probe_max = TCP_RESOURCE_PROBE_INTERVAL; |
1da177e4 | 3756 | } |
fcdd1cf4 | 3757 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
21c8fe99 | 3758 | tcp_probe0_when(sk, probe_max), |
fcdd1cf4 | 3759 | TCP_RTO_MAX); |
1da177e4 | 3760 | } |
5db92c99 | 3761 | |
ea3bea3a | 3762 | int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) |
5db92c99 OP |
3763 | { |
3764 | const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; | |
3765 | struct flowi fl; | |
3766 | int res; | |
3767 | ||
58d607d3 | 3768 | tcp_rsk(req)->txhash = net_tx_rndhash(); |
b3d05147 | 3769 | res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL); |
5db92c99 | 3770 | if (!res) { |
90bbcc60 | 3771 | __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); |
02a1d6e7 | 3772 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); |
7e32b443 YC |
3773 | if (unlikely(tcp_passive_fastopen(sk))) |
3774 | tcp_sk(sk)->total_retrans++; | |
cf34ce3d | 3775 | trace_tcp_retransmit_synack(sk, req); |
5db92c99 OP |
3776 | } |
3777 | return res; | |
3778 | } | |
3779 | EXPORT_SYMBOL(tcp_rtx_synack); |