Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Implementation of the Transmission Control Protocol(TCP). | |
7 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
12 | * Florian La Roche, <flla@stud.uni-sb.de> | |
13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
16 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
18 | * Jorge Cwik, <jorge@laser.satlink.net> | |
19 | */ | |
20 | ||
21 | /* | |
22 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
23 | * : Fragmentation on mtu decrease | |
24 | * : Segment collapse on retransmit | |
25 | * : AF independence | |
26 | * | |
27 | * Linus Torvalds : send_delayed_ack | |
28 | * David S. Miller : Charge memory using the right skb | |
29 | * during syn/ack processing. | |
30 | * David S. Miller : Output engine completely rewritten. | |
31 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
32 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
33 | * J Hadi Salim : ECN support | |
34 | * | |
35 | */ | |
36 | ||
91df42be JP |
37 | #define pr_fmt(fmt) "TCP: " fmt |
38 | ||
1da177e4 LT |
39 | #include <net/tcp.h> |
40 | ||
41 | #include <linux/compiler.h> | |
5a0e3ad6 | 42 | #include <linux/gfp.h> |
1da177e4 | 43 | #include <linux/module.h> |
1da177e4 LT |
44 | |
45 | /* People can turn this off for buggy TCP's found in printers etc. */ | |
ab32ea5d | 46 | int sysctl_tcp_retrans_collapse __read_mostly = 1; |
1da177e4 | 47 | |
09cb105e | 48 | /* People can turn this on to work with those rare, broken TCPs that |
15d99e02 RJ |
49 | * interpret the window field as a signed quantity. |
50 | */ | |
ab32ea5d | 51 | int sysctl_tcp_workaround_signed_windows __read_mostly = 0; |
15d99e02 | 52 | |
c39c4c6a WL |
53 | /* Default TSQ limit of four TSO segments */ |
54 | int sysctl_tcp_limit_output_bytes __read_mostly = 262144; | |
46d3ceab | 55 | |
1da177e4 LT |
56 | /* This limits the percentage of the congestion window which we |
57 | * will allow a single TSO frame to consume. Building TSO frames | |
58 | * which are too large can cause TCP streams to be bursty. | |
59 | */ | |
ab32ea5d | 60 | int sysctl_tcp_tso_win_divisor __read_mostly = 3; |
1da177e4 | 61 | |
35089bb2 | 62 | /* By default, RFC2861 behavior. */ |
ab32ea5d | 63 | int sysctl_tcp_slow_start_after_idle __read_mostly = 1; |
35089bb2 | 64 | |
46d3ceab ED |
65 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
66 | int push_one, gfp_t gfp); | |
519855c5 | 67 | |
67edfef7 | 68 | /* Account for new data that has been sent to the network. */ |
cf533ea5 | 69 | static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) |
1da177e4 | 70 | { |
6ba8a3b1 | 71 | struct inet_connection_sock *icsk = inet_csk(sk); |
9e412ba7 | 72 | struct tcp_sock *tp = tcp_sk(sk); |
66f5fe62 | 73 | unsigned int prior_packets = tp->packets_out; |
9e412ba7 | 74 | |
fe067e8a | 75 | tcp_advance_send_head(sk, skb); |
1da177e4 | 76 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; |
8512430e | 77 | |
66f5fe62 | 78 | tp->packets_out += tcp_skb_pcount(skb); |
6ba8a3b1 | 79 | if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || |
6a5dc9e5 | 80 | icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { |
750ea2ba | 81 | tcp_rearm_rto(sk); |
6a5dc9e5 | 82 | } |
f19c29e3 | 83 | |
f7324acd DM |
84 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, |
85 | tcp_skb_pcount(skb)); | |
1da177e4 LT |
86 | } |
87 | ||
88 | /* SND.NXT, if window was not shrunk. | |
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 | |
90840def | 98 | if (!before(tcp_wnd_end(tp), tp->snd_nxt)) |
1da177e4 LT |
99 | return tp->snd_nxt; |
100 | else | |
90840def | 101 | return tcp_wnd_end(tp); |
1da177e4 LT |
102 | } |
103 | ||
104 | /* Calculate mss to advertise in SYN segment. | |
105 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
106 | * | |
107 | * 1. It is independent of path mtu. | |
108 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
109 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
110 | * attached devices, because some buggy hosts are confused by | |
111 | * large MSS. | |
112 | * 4. We do not make 3, we advertise MSS, calculated from first | |
113 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
114 | * This may be overridden via information stored in routing table. | |
115 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
116 | * probably even Jumbo". | |
117 | */ | |
118 | static __u16 tcp_advertise_mss(struct sock *sk) | |
119 | { | |
120 | struct tcp_sock *tp = tcp_sk(sk); | |
cf533ea5 | 121 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
122 | int mss = tp->advmss; |
123 | ||
0dbaee3b DM |
124 | if (dst) { |
125 | unsigned int metric = dst_metric_advmss(dst); | |
126 | ||
127 | if (metric < mss) { | |
128 | mss = metric; | |
129 | tp->advmss = mss; | |
130 | } | |
1da177e4 LT |
131 | } |
132 | ||
133 | return (__u16)mss; | |
134 | } | |
135 | ||
136 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
6f021c62 ED |
137 | * This is the first part of cwnd validation mechanism. |
138 | */ | |
139 | void tcp_cwnd_restart(struct sock *sk, s32 delta) | |
1da177e4 | 140 | { |
463c84b9 | 141 | struct tcp_sock *tp = tcp_sk(sk); |
6f021c62 | 142 | u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
1da177e4 LT |
143 | u32 cwnd = tp->snd_cwnd; |
144 | ||
6687e988 | 145 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 146 | |
6687e988 | 147 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
148 | restart_cwnd = min(restart_cwnd, cwnd); |
149 | ||
463c84b9 | 150 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
151 | cwnd >>= 1; |
152 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
153 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
154 | tp->snd_cwnd_used = 0; | |
155 | } | |
156 | ||
67edfef7 | 157 | /* Congestion state accounting after a packet has been sent. */ |
40efc6fa | 158 | static void tcp_event_data_sent(struct tcp_sock *tp, |
cf533ea5 | 159 | struct sock *sk) |
1da177e4 | 160 | { |
463c84b9 ACM |
161 | struct inet_connection_sock *icsk = inet_csk(sk); |
162 | const u32 now = tcp_time_stamp; | |
1da177e4 | 163 | |
05c5a46d NC |
164 | if (tcp_packets_in_flight(tp) == 0) |
165 | tcp_ca_event(sk, CA_EVENT_TX_START); | |
166 | ||
1da177e4 LT |
167 | tp->lsndtime = now; |
168 | ||
169 | /* If it is a reply for ato after last received | |
170 | * packet, enter pingpong mode. | |
171 | */ | |
2251ae46 JM |
172 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
173 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
174 | } |
175 | ||
67edfef7 | 176 | /* Account for an ACK we sent. */ |
40efc6fa | 177 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 178 | { |
463c84b9 ACM |
179 | tcp_dec_quickack_mode(sk, pkts); |
180 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
181 | } |
182 | ||
85f16525 YC |
183 | |
184 | u32 tcp_default_init_rwnd(u32 mss) | |
185 | { | |
186 | /* Initial receive window should be twice of TCP_INIT_CWND to | |
9ef71e0c | 187 | * enable proper sending of new unsent data during fast recovery |
85f16525 YC |
188 | * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a |
189 | * limit when mss is larger than 1460. | |
190 | */ | |
191 | u32 init_rwnd = TCP_INIT_CWND * 2; | |
192 | ||
193 | if (mss > 1460) | |
194 | init_rwnd = max((1460 * init_rwnd) / mss, 2U); | |
195 | return init_rwnd; | |
196 | } | |
197 | ||
1da177e4 LT |
198 | /* Determine a window scaling and initial window to offer. |
199 | * Based on the assumption that the given amount of space | |
200 | * will be offered. Store the results in the tp structure. | |
201 | * NOTE: for smooth operation initial space offering should | |
202 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
203 | * This MUST be enforced by all callers. | |
204 | */ | |
205 | void tcp_select_initial_window(int __space, __u32 mss, | |
206 | __u32 *rcv_wnd, __u32 *window_clamp, | |
31d12926 | 207 | int wscale_ok, __u8 *rcv_wscale, |
208 | __u32 init_rcv_wnd) | |
1da177e4 LT |
209 | { |
210 | unsigned int space = (__space < 0 ? 0 : __space); | |
211 | ||
212 | /* If no clamp set the clamp to the max possible scaled window */ | |
213 | if (*window_clamp == 0) | |
214 | (*window_clamp) = (65535 << 14); | |
215 | space = min(*window_clamp, space); | |
216 | ||
217 | /* Quantize space offering to a multiple of mss if possible. */ | |
218 | if (space > mss) | |
219 | space = (space / mss) * mss; | |
220 | ||
221 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
222 | * will break some buggy TCP stacks. If the admin tells us |
223 | * it is likely we could be speaking with such a buggy stack | |
224 | * we will truncate our initial window offering to 32K-1 | |
225 | * unless the remote has sent us a window scaling option, | |
226 | * which we interpret as a sign the remote TCP is not | |
227 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 228 | */ |
15d99e02 RJ |
229 | if (sysctl_tcp_workaround_signed_windows) |
230 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
231 | else | |
232 | (*rcv_wnd) = space; | |
233 | ||
1da177e4 LT |
234 | (*rcv_wscale) = 0; |
235 | if (wscale_ok) { | |
236 | /* Set window scaling on max possible window | |
e905a9ed | 237 | * See RFC1323 for an explanation of the limit to 14 |
1da177e4 LT |
238 | */ |
239 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
316c1592 | 240 | space = min_t(u32, space, *window_clamp); |
1da177e4 LT |
241 | while (space > 65535 && (*rcv_wscale) < 14) { |
242 | space >>= 1; | |
243 | (*rcv_wscale)++; | |
244 | } | |
245 | } | |
246 | ||
056834d9 | 247 | if (mss > (1 << *rcv_wscale)) { |
85f16525 YC |
248 | if (!init_rcv_wnd) /* Use default unless specified otherwise */ |
249 | init_rcv_wnd = tcp_default_init_rwnd(mss); | |
250 | *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); | |
1da177e4 LT |
251 | } |
252 | ||
253 | /* Set the clamp no higher than max representable value */ | |
254 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
255 | } | |
4bc2f18b | 256 | EXPORT_SYMBOL(tcp_select_initial_window); |
1da177e4 LT |
257 | |
258 | /* Chose a new window to advertise, update state in tcp_sock for the | |
259 | * socket, and return result with RFC1323 scaling applied. The return | |
260 | * value can be stuffed directly into th->window for an outgoing | |
261 | * frame. | |
262 | */ | |
40efc6fa | 263 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
264 | { |
265 | struct tcp_sock *tp = tcp_sk(sk); | |
8e165e20 | 266 | u32 old_win = tp->rcv_wnd; |
1da177e4 LT |
267 | u32 cur_win = tcp_receive_window(tp); |
268 | u32 new_win = __tcp_select_window(sk); | |
269 | ||
270 | /* Never shrink the offered window */ | |
2de979bd | 271 | if (new_win < cur_win) { |
1da177e4 LT |
272 | /* Danger Will Robinson! |
273 | * Don't update rcv_wup/rcv_wnd here or else | |
274 | * we will not be able to advertise a zero | |
275 | * window in time. --DaveM | |
276 | * | |
277 | * Relax Will Robinson. | |
278 | */ | |
8e165e20 FW |
279 | if (new_win == 0) |
280 | NET_INC_STATS(sock_net(sk), | |
281 | LINUX_MIB_TCPWANTZEROWINDOWADV); | |
607bfbf2 | 282 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
283 | } |
284 | tp->rcv_wnd = new_win; | |
285 | tp->rcv_wup = tp->rcv_nxt; | |
286 | ||
287 | /* Make sure we do not exceed the maximum possible | |
288 | * scaled window. | |
289 | */ | |
15d99e02 | 290 | if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) |
1da177e4 LT |
291 | new_win = min(new_win, MAX_TCP_WINDOW); |
292 | else | |
293 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
294 | ||
295 | /* RFC1323 scaling applied */ | |
296 | new_win >>= tp->rx_opt.rcv_wscale; | |
297 | ||
298 | /* If we advertise zero window, disable fast path. */ | |
8e165e20 | 299 | if (new_win == 0) { |
1da177e4 | 300 | tp->pred_flags = 0; |
8e165e20 FW |
301 | if (old_win) |
302 | NET_INC_STATS(sock_net(sk), | |
303 | LINUX_MIB_TCPTOZEROWINDOWADV); | |
304 | } else if (old_win == 0) { | |
305 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); | |
306 | } | |
1da177e4 LT |
307 | |
308 | return new_win; | |
309 | } | |
310 | ||
67edfef7 | 311 | /* Packet ECN state for a SYN-ACK */ |
735d3831 | 312 | static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d | 313 | { |
30e502a3 DB |
314 | const struct tcp_sock *tp = tcp_sk(sk); |
315 | ||
4de075e0 | 316 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
056834d9 | 317 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
4de075e0 | 318 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
30e502a3 DB |
319 | else if (tcp_ca_needs_ecn(sk)) |
320 | INET_ECN_xmit(sk); | |
bdf1ee5d IJ |
321 | } |
322 | ||
67edfef7 | 323 | /* Packet ECN state for a SYN. */ |
735d3831 | 324 | static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d IJ |
325 | { |
326 | struct tcp_sock *tp = tcp_sk(sk); | |
f7b3bec6 FW |
327 | bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || |
328 | tcp_ca_needs_ecn(sk); | |
329 | ||
330 | if (!use_ecn) { | |
331 | const struct dst_entry *dst = __sk_dst_get(sk); | |
332 | ||
333 | if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) | |
334 | use_ecn = true; | |
335 | } | |
bdf1ee5d IJ |
336 | |
337 | tp->ecn_flags = 0; | |
f7b3bec6 FW |
338 | |
339 | if (use_ecn) { | |
4de075e0 | 340 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
bdf1ee5d | 341 | tp->ecn_flags = TCP_ECN_OK; |
30e502a3 DB |
342 | if (tcp_ca_needs_ecn(sk)) |
343 | INET_ECN_xmit(sk); | |
bdf1ee5d IJ |
344 | } |
345 | } | |
346 | ||
49213555 DB |
347 | static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) |
348 | { | |
349 | if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) | |
350 | /* tp->ecn_flags are cleared at a later point in time when | |
351 | * SYN ACK is ultimatively being received. | |
352 | */ | |
353 | TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); | |
354 | } | |
355 | ||
735d3831 | 356 | static void |
6ac705b1 | 357 | tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) |
bdf1ee5d | 358 | { |
6ac705b1 | 359 | if (inet_rsk(req)->ecn_ok) |
bdf1ee5d IJ |
360 | th->ece = 1; |
361 | } | |
362 | ||
67edfef7 AK |
363 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
364 | * be sent. | |
365 | */ | |
735d3831 | 366 | static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, |
bdf1ee5d IJ |
367 | int tcp_header_len) |
368 | { | |
369 | struct tcp_sock *tp = tcp_sk(sk); | |
370 | ||
371 | if (tp->ecn_flags & TCP_ECN_OK) { | |
372 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
373 | if (skb->len != tcp_header_len && | |
374 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
375 | INET_ECN_xmit(sk); | |
056834d9 | 376 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d IJ |
377 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
378 | tcp_hdr(skb)->cwr = 1; | |
379 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; | |
380 | } | |
30e502a3 | 381 | } else if (!tcp_ca_needs_ecn(sk)) { |
bdf1ee5d IJ |
382 | /* ACK or retransmitted segment: clear ECT|CE */ |
383 | INET_ECN_dontxmit(sk); | |
384 | } | |
385 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
386 | tcp_hdr(skb)->ece = 1; | |
387 | } | |
388 | } | |
389 | ||
e870a8ef IJ |
390 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
391 | * auto increment end seqno. | |
392 | */ | |
393 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
394 | { | |
2e8e18ef | 395 | skb->ip_summed = CHECKSUM_PARTIAL; |
e870a8ef IJ |
396 | skb->csum = 0; |
397 | ||
4de075e0 | 398 | TCP_SKB_CB(skb)->tcp_flags = flags; |
e870a8ef IJ |
399 | TCP_SKB_CB(skb)->sacked = 0; |
400 | ||
cd7d8498 | 401 | tcp_skb_pcount_set(skb, 1); |
e870a8ef IJ |
402 | |
403 | TCP_SKB_CB(skb)->seq = seq; | |
a3433f35 | 404 | if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
e870a8ef IJ |
405 | seq++; |
406 | TCP_SKB_CB(skb)->end_seq = seq; | |
407 | } | |
408 | ||
a2a385d6 | 409 | static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
33f5f57e IJ |
410 | { |
411 | return tp->snd_una != tp->snd_up; | |
412 | } | |
413 | ||
33ad798c AL |
414 | #define OPTION_SACK_ADVERTISE (1 << 0) |
415 | #define OPTION_TS (1 << 1) | |
416 | #define OPTION_MD5 (1 << 2) | |
89e95a61 | 417 | #define OPTION_WSCALE (1 << 3) |
2100c8d2 | 418 | #define OPTION_FAST_OPEN_COOKIE (1 << 8) |
33ad798c AL |
419 | |
420 | struct tcp_out_options { | |
2100c8d2 YC |
421 | u16 options; /* bit field of OPTION_* */ |
422 | u16 mss; /* 0 to disable */ | |
33ad798c AL |
423 | u8 ws; /* window scale, 0 to disable */ |
424 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 425 | u8 hash_size; /* bytes in hash_location */ |
bd0388ae | 426 | __u8 *hash_location; /* temporary pointer, overloaded */ |
2100c8d2 YC |
427 | __u32 tsval, tsecr; /* need to include OPTION_TS */ |
428 | struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ | |
33ad798c AL |
429 | }; |
430 | ||
67edfef7 AK |
431 | /* Write previously computed TCP options to the packet. |
432 | * | |
433 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
434 | * TCP options, we learned this through the hard way, so be careful here. |
435 | * Luckily we can at least blame others for their non-compliance but from | |
8e3bff96 | 436 | * inter-operability perspective it seems that we're somewhat stuck with |
fd6149d3 IJ |
437 | * the ordering which we have been using if we want to keep working with |
438 | * those broken things (not that it currently hurts anybody as there isn't | |
439 | * particular reason why the ordering would need to be changed). | |
440 | * | |
441 | * At least SACK_PERM as the first option is known to lead to a disaster | |
442 | * (but it may well be that other scenarios fail similarly). | |
443 | */ | |
33ad798c | 444 | static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
bd0388ae WAS |
445 | struct tcp_out_options *opts) |
446 | { | |
2100c8d2 | 447 | u16 options = opts->options; /* mungable copy */ |
bd0388ae | 448 | |
bd0388ae | 449 | if (unlikely(OPTION_MD5 & options)) { |
1a2c6181 CP |
450 | *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
451 | (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); | |
bd0388ae WAS |
452 | /* overload cookie hash location */ |
453 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 454 | ptr += 4; |
40efc6fa | 455 | } |
33ad798c | 456 | |
fd6149d3 IJ |
457 | if (unlikely(opts->mss)) { |
458 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
459 | (TCPOLEN_MSS << 16) | | |
460 | opts->mss); | |
461 | } | |
462 | ||
bd0388ae WAS |
463 | if (likely(OPTION_TS & options)) { |
464 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
465 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
466 | (TCPOLEN_SACK_PERM << 16) | | |
467 | (TCPOPT_TIMESTAMP << 8) | | |
468 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 469 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
470 | } else { |
471 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
472 | (TCPOPT_NOP << 16) | | |
473 | (TCPOPT_TIMESTAMP << 8) | | |
474 | TCPOLEN_TIMESTAMP); | |
475 | } | |
476 | *ptr++ = htonl(opts->tsval); | |
477 | *ptr++ = htonl(opts->tsecr); | |
478 | } | |
479 | ||
bd0388ae | 480 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
33ad798c AL |
481 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
482 | (TCPOPT_NOP << 16) | | |
483 | (TCPOPT_SACK_PERM << 8) | | |
484 | TCPOLEN_SACK_PERM); | |
485 | } | |
486 | ||
bd0388ae | 487 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
488 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
489 | (TCPOPT_WINDOW << 16) | | |
490 | (TCPOLEN_WINDOW << 8) | | |
491 | opts->ws); | |
492 | } | |
493 | ||
494 | if (unlikely(opts->num_sack_blocks)) { | |
495 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
496 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
497 | int this_sack; |
498 | ||
499 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
500 | (TCPOPT_NOP << 16) | | |
501 | (TCPOPT_SACK << 8) | | |
33ad798c | 502 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 503 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 504 | |
33ad798c AL |
505 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
506 | ++this_sack) { | |
40efc6fa SH |
507 | *ptr++ = htonl(sp[this_sack].start_seq); |
508 | *ptr++ = htonl(sp[this_sack].end_seq); | |
509 | } | |
2de979bd | 510 | |
5861f8e5 | 511 | tp->rx_opt.dsack = 0; |
40efc6fa | 512 | } |
2100c8d2 YC |
513 | |
514 | if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { | |
515 | struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; | |
7f9b838b DL |
516 | u8 *p = (u8 *)ptr; |
517 | u32 len; /* Fast Open option length */ | |
518 | ||
519 | if (foc->exp) { | |
520 | len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; | |
521 | *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | | |
522 | TCPOPT_FASTOPEN_MAGIC); | |
523 | p += TCPOLEN_EXP_FASTOPEN_BASE; | |
524 | } else { | |
525 | len = TCPOLEN_FASTOPEN_BASE + foc->len; | |
526 | *p++ = TCPOPT_FASTOPEN; | |
527 | *p++ = len; | |
528 | } | |
2100c8d2 | 529 | |
7f9b838b DL |
530 | memcpy(p, foc->val, foc->len); |
531 | if ((len & 3) == 2) { | |
532 | p[foc->len] = TCPOPT_NOP; | |
533 | p[foc->len + 1] = TCPOPT_NOP; | |
2100c8d2 | 534 | } |
7f9b838b | 535 | ptr += (len + 3) >> 2; |
2100c8d2 | 536 | } |
33ad798c AL |
537 | } |
538 | ||
67edfef7 AK |
539 | /* Compute TCP options for SYN packets. This is not the final |
540 | * network wire format yet. | |
541 | */ | |
95c96174 | 542 | static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 543 | struct tcp_out_options *opts, |
cf533ea5 ED |
544 | struct tcp_md5sig_key **md5) |
545 | { | |
33ad798c | 546 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 547 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
783237e8 | 548 | struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
33ad798c | 549 | |
cfb6eeb4 | 550 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
551 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
552 | if (*md5) { | |
553 | opts->options |= OPTION_MD5; | |
bd0388ae | 554 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
cfb6eeb4 | 555 | } |
33ad798c AL |
556 | #else |
557 | *md5 = NULL; | |
cfb6eeb4 | 558 | #endif |
33ad798c AL |
559 | |
560 | /* We always get an MSS option. The option bytes which will be seen in | |
561 | * normal data packets should timestamps be used, must be in the MSS | |
562 | * advertised. But we subtract them from tp->mss_cache so that | |
563 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
564 | * fact here if necessary. If we don't do this correctly, as a | |
565 | * receiver we won't recognize data packets as being full sized when we | |
566 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
567 | * SACKs don't matter, we never delay an ACK when we have any of those | |
568 | * going out. */ | |
569 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 570 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 571 | |
51456b29 | 572 | if (likely(sysctl_tcp_timestamps && !*md5)) { |
33ad798c | 573 | opts->options |= OPTION_TS; |
7faee5c0 | 574 | opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; |
33ad798c | 575 | opts->tsecr = tp->rx_opt.ts_recent; |
bd0388ae | 576 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 577 | } |
bb5b7c11 | 578 | if (likely(sysctl_tcp_window_scaling)) { |
33ad798c | 579 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 580 | opts->options |= OPTION_WSCALE; |
bd0388ae | 581 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 582 | } |
bb5b7c11 | 583 | if (likely(sysctl_tcp_sack)) { |
33ad798c | 584 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 585 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 586 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
587 | } |
588 | ||
783237e8 | 589 | if (fastopen && fastopen->cookie.len >= 0) { |
2646c831 DL |
590 | u32 need = fastopen->cookie.len; |
591 | ||
592 | need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : | |
593 | TCPOLEN_FASTOPEN_BASE; | |
783237e8 YC |
594 | need = (need + 3) & ~3U; /* Align to 32 bits */ |
595 | if (remaining >= need) { | |
596 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
597 | opts->fastopen_cookie = &fastopen->cookie; | |
598 | remaining -= need; | |
599 | tp->syn_fastopen = 1; | |
2646c831 | 600 | tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; |
783237e8 YC |
601 | } |
602 | } | |
bd0388ae | 603 | |
bd0388ae | 604 | return MAX_TCP_OPTION_SPACE - remaining; |
40efc6fa SH |
605 | } |
606 | ||
67edfef7 | 607 | /* Set up TCP options for SYN-ACKs. */ |
37bfbdda ED |
608 | static unsigned int tcp_synack_options(struct request_sock *req, |
609 | unsigned int mss, struct sk_buff *skb, | |
610 | struct tcp_out_options *opts, | |
611 | const struct tcp_md5sig_key *md5, | |
612 | struct tcp_fastopen_cookie *foc) | |
4957faad | 613 | { |
33ad798c | 614 | struct inet_request_sock *ireq = inet_rsk(req); |
95c96174 | 615 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
33ad798c | 616 | |
cfb6eeb4 | 617 | #ifdef CONFIG_TCP_MD5SIG |
80f03e27 | 618 | if (md5) { |
33ad798c | 619 | opts->options |= OPTION_MD5; |
4957faad WAS |
620 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
621 | ||
622 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
623 | * options. There was discussion about disabling SACK | |
624 | * rather than TS in order to fit in better with old, | |
625 | * buggy kernels, but that was deemed to be unnecessary. | |
626 | */ | |
de213e5e | 627 | ireq->tstamp_ok &= !ireq->sack_ok; |
cfb6eeb4 YH |
628 | } |
629 | #endif | |
33ad798c | 630 | |
4957faad | 631 | /* We always send an MSS option. */ |
33ad798c | 632 | opts->mss = mss; |
4957faad | 633 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
634 | |
635 | if (likely(ireq->wscale_ok)) { | |
636 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 637 | opts->options |= OPTION_WSCALE; |
4957faad | 638 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 639 | } |
de213e5e | 640 | if (likely(ireq->tstamp_ok)) { |
33ad798c | 641 | opts->options |= OPTION_TS; |
7faee5c0 | 642 | opts->tsval = tcp_skb_timestamp(skb); |
33ad798c | 643 | opts->tsecr = req->ts_recent; |
4957faad | 644 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
645 | } |
646 | if (likely(ireq->sack_ok)) { | |
647 | opts->options |= OPTION_SACK_ADVERTISE; | |
de213e5e | 648 | if (unlikely(!ireq->tstamp_ok)) |
4957faad | 649 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c | 650 | } |
7f9b838b DL |
651 | if (foc != NULL && foc->len >= 0) { |
652 | u32 need = foc->len; | |
653 | ||
654 | need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : | |
655 | TCPOLEN_FASTOPEN_BASE; | |
8336886f JC |
656 | need = (need + 3) & ~3U; /* Align to 32 bits */ |
657 | if (remaining >= need) { | |
658 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
659 | opts->fastopen_cookie = foc; | |
660 | remaining -= need; | |
661 | } | |
662 | } | |
1a2c6181 | 663 | |
4957faad | 664 | return MAX_TCP_OPTION_SPACE - remaining; |
33ad798c AL |
665 | } |
666 | ||
67edfef7 AK |
667 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
668 | * final wire format yet. | |
669 | */ | |
95c96174 | 670 | static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 671 | struct tcp_out_options *opts, |
cf533ea5 ED |
672 | struct tcp_md5sig_key **md5) |
673 | { | |
33ad798c | 674 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 675 | unsigned int size = 0; |
cabeccbd | 676 | unsigned int eff_sacks; |
33ad798c | 677 | |
5843ef42 AK |
678 | opts->options = 0; |
679 | ||
33ad798c AL |
680 | #ifdef CONFIG_TCP_MD5SIG |
681 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
682 | if (unlikely(*md5)) { | |
683 | opts->options |= OPTION_MD5; | |
684 | size += TCPOLEN_MD5SIG_ALIGNED; | |
685 | } | |
686 | #else | |
687 | *md5 = NULL; | |
688 | #endif | |
689 | ||
690 | if (likely(tp->rx_opt.tstamp_ok)) { | |
691 | opts->options |= OPTION_TS; | |
7faee5c0 | 692 | opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; |
33ad798c AL |
693 | opts->tsecr = tp->rx_opt.ts_recent; |
694 | size += TCPOLEN_TSTAMP_ALIGNED; | |
695 | } | |
696 | ||
cabeccbd IJ |
697 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
698 | if (unlikely(eff_sacks)) { | |
95c96174 | 699 | const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
33ad798c | 700 | opts->num_sack_blocks = |
95c96174 | 701 | min_t(unsigned int, eff_sacks, |
33ad798c AL |
702 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
703 | TCPOLEN_SACK_PERBLOCK); | |
704 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
705 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
706 | } | |
707 | ||
708 | return size; | |
40efc6fa | 709 | } |
1da177e4 | 710 | |
46d3ceab ED |
711 | |
712 | /* TCP SMALL QUEUES (TSQ) | |
713 | * | |
714 | * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) | |
715 | * to reduce RTT and bufferbloat. | |
716 | * We do this using a special skb destructor (tcp_wfree). | |
717 | * | |
718 | * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb | |
719 | * needs to be reallocated in a driver. | |
8e3bff96 | 720 | * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
46d3ceab ED |
721 | * |
722 | * Since transmit from skb destructor is forbidden, we use a tasklet | |
723 | * to process all sockets that eventually need to send more skbs. | |
724 | * We use one tasklet per cpu, with its own queue of sockets. | |
725 | */ | |
726 | struct tsq_tasklet { | |
727 | struct tasklet_struct tasklet; | |
728 | struct list_head head; /* queue of tcp sockets */ | |
729 | }; | |
730 | static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); | |
731 | ||
6f458dfb ED |
732 | static void tcp_tsq_handler(struct sock *sk) |
733 | { | |
734 | if ((1 << sk->sk_state) & | |
735 | (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | | |
736 | TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) | |
bf06200e JO |
737 | tcp_write_xmit(sk, tcp_current_mss(sk), tcp_sk(sk)->nonagle, |
738 | 0, GFP_ATOMIC); | |
6f458dfb | 739 | } |
46d3ceab | 740 | /* |
8e3bff96 | 741 | * One tasklet per cpu tries to send more skbs. |
46d3ceab | 742 | * We run in tasklet context but need to disable irqs when |
8e3bff96 | 743 | * transferring tsq->head because tcp_wfree() might |
46d3ceab ED |
744 | * interrupt us (non NAPI drivers) |
745 | */ | |
746 | static void tcp_tasklet_func(unsigned long data) | |
747 | { | |
748 | struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; | |
749 | LIST_HEAD(list); | |
750 | unsigned long flags; | |
751 | struct list_head *q, *n; | |
752 | struct tcp_sock *tp; | |
753 | struct sock *sk; | |
754 | ||
755 | local_irq_save(flags); | |
756 | list_splice_init(&tsq->head, &list); | |
757 | local_irq_restore(flags); | |
758 | ||
759 | list_for_each_safe(q, n, &list) { | |
760 | tp = list_entry(q, struct tcp_sock, tsq_node); | |
761 | list_del(&tp->tsq_node); | |
762 | ||
763 | sk = (struct sock *)tp; | |
764 | bh_lock_sock(sk); | |
765 | ||
766 | if (!sock_owned_by_user(sk)) { | |
6f458dfb | 767 | tcp_tsq_handler(sk); |
46d3ceab ED |
768 | } else { |
769 | /* defer the work to tcp_release_cb() */ | |
6f458dfb | 770 | set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); |
46d3ceab ED |
771 | } |
772 | bh_unlock_sock(sk); | |
773 | ||
774 | clear_bit(TSQ_QUEUED, &tp->tsq_flags); | |
775 | sk_free(sk); | |
776 | } | |
777 | } | |
778 | ||
6f458dfb ED |
779 | #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ |
780 | (1UL << TCP_WRITE_TIMER_DEFERRED) | \ | |
563d34d0 ED |
781 | (1UL << TCP_DELACK_TIMER_DEFERRED) | \ |
782 | (1UL << TCP_MTU_REDUCED_DEFERRED)) | |
46d3ceab ED |
783 | /** |
784 | * tcp_release_cb - tcp release_sock() callback | |
785 | * @sk: socket | |
786 | * | |
787 | * called from release_sock() to perform protocol dependent | |
788 | * actions before socket release. | |
789 | */ | |
790 | void tcp_release_cb(struct sock *sk) | |
791 | { | |
792 | struct tcp_sock *tp = tcp_sk(sk); | |
6f458dfb | 793 | unsigned long flags, nflags; |
46d3ceab | 794 | |
6f458dfb ED |
795 | /* perform an atomic operation only if at least one flag is set */ |
796 | do { | |
797 | flags = tp->tsq_flags; | |
798 | if (!(flags & TCP_DEFERRED_ALL)) | |
799 | return; | |
800 | nflags = flags & ~TCP_DEFERRED_ALL; | |
801 | } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); | |
802 | ||
803 | if (flags & (1UL << TCP_TSQ_DEFERRED)) | |
804 | tcp_tsq_handler(sk); | |
805 | ||
c3f9b018 ED |
806 | /* Here begins the tricky part : |
807 | * We are called from release_sock() with : | |
808 | * 1) BH disabled | |
809 | * 2) sk_lock.slock spinlock held | |
810 | * 3) socket owned by us (sk->sk_lock.owned == 1) | |
811 | * | |
812 | * But following code is meant to be called from BH handlers, | |
813 | * so we should keep BH disabled, but early release socket ownership | |
814 | */ | |
815 | sock_release_ownership(sk); | |
816 | ||
144d56e9 | 817 | if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { |
6f458dfb | 818 | tcp_write_timer_handler(sk); |
144d56e9 ED |
819 | __sock_put(sk); |
820 | } | |
821 | if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { | |
6f458dfb | 822 | tcp_delack_timer_handler(sk); |
144d56e9 ED |
823 | __sock_put(sk); |
824 | } | |
825 | if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { | |
4fab9071 | 826 | inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); |
144d56e9 ED |
827 | __sock_put(sk); |
828 | } | |
46d3ceab ED |
829 | } |
830 | EXPORT_SYMBOL(tcp_release_cb); | |
831 | ||
832 | void __init tcp_tasklet_init(void) | |
833 | { | |
834 | int i; | |
835 | ||
836 | for_each_possible_cpu(i) { | |
837 | struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); | |
838 | ||
839 | INIT_LIST_HEAD(&tsq->head); | |
840 | tasklet_init(&tsq->tasklet, | |
841 | tcp_tasklet_func, | |
842 | (unsigned long)tsq); | |
843 | } | |
844 | } | |
845 | ||
846 | /* | |
847 | * Write buffer destructor automatically called from kfree_skb. | |
8e3bff96 | 848 | * We can't xmit new skbs from this context, as we might already |
46d3ceab ED |
849 | * hold qdisc lock. |
850 | */ | |
d6a4a104 | 851 | void tcp_wfree(struct sk_buff *skb) |
46d3ceab ED |
852 | { |
853 | struct sock *sk = skb->sk; | |
854 | struct tcp_sock *tp = tcp_sk(sk); | |
9b462d02 ED |
855 | int wmem; |
856 | ||
857 | /* Keep one reference on sk_wmem_alloc. | |
858 | * Will be released by sk_free() from here or tcp_tasklet_func() | |
859 | */ | |
860 | wmem = atomic_sub_return(skb->truesize - 1, &sk->sk_wmem_alloc); | |
861 | ||
862 | /* If this softirq is serviced by ksoftirqd, we are likely under stress. | |
863 | * Wait until our queues (qdisc + devices) are drained. | |
864 | * This gives : | |
865 | * - less callbacks to tcp_write_xmit(), reducing stress (batches) | |
866 | * - chance for incoming ACK (processed by another cpu maybe) | |
867 | * to migrate this flow (skb->ooo_okay will be eventually set) | |
868 | */ | |
869 | if (wmem >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) | |
870 | goto out; | |
46d3ceab ED |
871 | |
872 | if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && | |
873 | !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { | |
874 | unsigned long flags; | |
875 | struct tsq_tasklet *tsq; | |
876 | ||
46d3ceab ED |
877 | /* queue this socket to tasklet queue */ |
878 | local_irq_save(flags); | |
903ceff7 | 879 | tsq = this_cpu_ptr(&tsq_tasklet); |
46d3ceab ED |
880 | list_add(&tp->tsq_node, &tsq->head); |
881 | tasklet_schedule(&tsq->tasklet); | |
882 | local_irq_restore(flags); | |
9b462d02 | 883 | return; |
46d3ceab | 884 | } |
9b462d02 ED |
885 | out: |
886 | sk_free(sk); | |
46d3ceab ED |
887 | } |
888 | ||
1da177e4 LT |
889 | /* This routine actually transmits TCP packets queued in by |
890 | * tcp_do_sendmsg(). This is used by both the initial | |
891 | * transmission and possible later retransmissions. | |
892 | * All SKB's seen here are completely headerless. It is our | |
893 | * job to build the TCP header, and pass the packet down to | |
894 | * IP so it can do the same plus pass the packet off to the | |
895 | * device. | |
896 | * | |
897 | * We are working here with either a clone of the original | |
898 | * SKB, or a fresh unique copy made by the retransmit engine. | |
899 | */ | |
056834d9 IJ |
900 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
901 | gfp_t gfp_mask) | |
1da177e4 | 902 | { |
dfb4b9dc DM |
903 | const struct inet_connection_sock *icsk = inet_csk(sk); |
904 | struct inet_sock *inet; | |
905 | struct tcp_sock *tp; | |
906 | struct tcp_skb_cb *tcb; | |
33ad798c | 907 | struct tcp_out_options opts; |
95c96174 | 908 | unsigned int tcp_options_size, tcp_header_size; |
cfb6eeb4 | 909 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 910 | struct tcphdr *th; |
dfb4b9dc DM |
911 | int err; |
912 | ||
913 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
914 | ||
ccdbb6e9 | 915 | if (clone_it) { |
740b0f18 | 916 | skb_mstamp_get(&skb->skb_mstamp); |
ccdbb6e9 | 917 | |
dfb4b9dc DM |
918 | if (unlikely(skb_cloned(skb))) |
919 | skb = pskb_copy(skb, gfp_mask); | |
920 | else | |
921 | skb = skb_clone(skb, gfp_mask); | |
922 | if (unlikely(!skb)) | |
923 | return -ENOBUFS; | |
924 | } | |
1da177e4 | 925 | |
dfb4b9dc DM |
926 | inet = inet_sk(sk); |
927 | tp = tcp_sk(sk); | |
928 | tcb = TCP_SKB_CB(skb); | |
33ad798c | 929 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 930 | |
4de075e0 | 931 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) |
33ad798c AL |
932 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
933 | else | |
934 | tcp_options_size = tcp_established_options(sk, skb, &opts, | |
935 | &md5); | |
936 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); | |
e905a9ed | 937 | |
547669d4 | 938 | /* if no packet is in qdisc/device queue, then allow XPS to select |
b2532eb9 ED |
939 | * another queue. We can be called from tcp_tsq_handler() |
940 | * which holds one reference to sk_wmem_alloc. | |
941 | * | |
942 | * TODO: Ideally, in-flight pure ACK packets should not matter here. | |
943 | * One way to get this would be to set skb->truesize = 2 on them. | |
547669d4 | 944 | */ |
b2532eb9 | 945 | skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); |
dfb4b9dc | 946 | |
aa8223c7 ACM |
947 | skb_push(skb, tcp_header_size); |
948 | skb_reset_transport_header(skb); | |
46d3ceab ED |
949 | |
950 | skb_orphan(skb); | |
951 | skb->sk = sk; | |
98781965 | 952 | skb->destructor = skb_is_tcp_pure_ack(skb) ? sock_wfree : tcp_wfree; |
b73c3d0e | 953 | skb_set_hash_from_sk(skb, sk); |
46d3ceab | 954 | atomic_add(skb->truesize, &sk->sk_wmem_alloc); |
dfb4b9dc DM |
955 | |
956 | /* Build TCP header and checksum it. */ | |
aa8223c7 | 957 | th = tcp_hdr(skb); |
c720c7e8 ED |
958 | th->source = inet->inet_sport; |
959 | th->dest = inet->inet_dport; | |
dfb4b9dc DM |
960 | th->seq = htonl(tcb->seq); |
961 | th->ack_seq = htonl(tp->rcv_nxt); | |
df7a3b07 | 962 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
4de075e0 | 963 | tcb->tcp_flags); |
dfb4b9dc | 964 | |
4de075e0 | 965 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
dfb4b9dc DM |
966 | /* RFC1323: The window in SYN & SYN/ACK segments |
967 | * is never scaled. | |
968 | */ | |
600ff0c2 | 969 | th->window = htons(min(tp->rcv_wnd, 65535U)); |
dfb4b9dc DM |
970 | } else { |
971 | th->window = htons(tcp_select_window(sk)); | |
972 | } | |
973 | th->check = 0; | |
974 | th->urg_ptr = 0; | |
1da177e4 | 975 | |
33f5f57e | 976 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
977 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
978 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
979 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
980 | th->urg = 1; | |
981 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
0eae88f3 | 982 | th->urg_ptr = htons(0xFFFF); |
7691367d HX |
983 | th->urg = 1; |
984 | } | |
dfb4b9dc | 985 | } |
1da177e4 | 986 | |
bd0388ae | 987 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
51466a75 | 988 | skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
4de075e0 | 989 | if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) |
735d3831 | 990 | tcp_ecn_send(sk, skb, tcp_header_size); |
1da177e4 | 991 | |
cfb6eeb4 YH |
992 | #ifdef CONFIG_TCP_MD5SIG |
993 | /* Calculate the MD5 hash, as we have all we need now */ | |
994 | if (md5) { | |
a465419b | 995 | sk_nocaps_add(sk, NETIF_F_GSO_MASK); |
bd0388ae | 996 | tp->af_specific->calc_md5_hash(opts.hash_location, |
39f8e58e | 997 | md5, sk, skb); |
cfb6eeb4 YH |
998 | } |
999 | #endif | |
1000 | ||
bb296246 | 1001 | icsk->icsk_af_ops->send_check(sk, skb); |
1da177e4 | 1002 | |
4de075e0 | 1003 | if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
dfb4b9dc | 1004 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); |
1da177e4 | 1005 | |
a44d6eac | 1006 | if (skb->len != tcp_header_size) { |
cf533ea5 | 1007 | tcp_event_data_sent(tp, sk); |
a44d6eac MKL |
1008 | tp->data_segs_out += tcp_skb_pcount(skb); |
1009 | } | |
1da177e4 | 1010 | |
bd37a088 | 1011 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
aa2ea058 TH |
1012 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
1013 | tcp_skb_pcount(skb)); | |
1da177e4 | 1014 | |
2efd055c | 1015 | tp->segs_out += tcp_skb_pcount(skb); |
f69ad292 | 1016 | /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ |
cd7d8498 | 1017 | skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); |
f69ad292 | 1018 | skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); |
cd7d8498 | 1019 | |
7faee5c0 ED |
1020 | /* Our usage of tstamp should remain private */ |
1021 | skb->tstamp.tv64 = 0; | |
971f10ec ED |
1022 | |
1023 | /* Cleanup our debris for IP stacks */ | |
1024 | memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), | |
1025 | sizeof(struct inet6_skb_parm))); | |
1026 | ||
b0270e91 | 1027 | err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); |
7faee5c0 | 1028 | |
83de47cd | 1029 | if (likely(err <= 0)) |
dfb4b9dc DM |
1030 | return err; |
1031 | ||
5ee2c941 | 1032 | tcp_enter_cwr(sk); |
dfb4b9dc | 1033 | |
b9df3cb8 | 1034 | return net_xmit_eval(err); |
1da177e4 LT |
1035 | } |
1036 | ||
67edfef7 | 1037 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
1038 | * |
1039 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
1040 | * otherwise socket can stall. | |
1041 | */ | |
1042 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
1043 | { | |
1044 | struct tcp_sock *tp = tcp_sk(sk); | |
1045 | ||
1046 | /* Advance write_seq and place onto the write_queue. */ | |
1047 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
f4a775d1 | 1048 | __skb_header_release(skb); |
fe067e8a | 1049 | tcp_add_write_queue_tail(sk, skb); |
3ab224be HA |
1050 | sk->sk_wmem_queued += skb->truesize; |
1051 | sk_mem_charge(sk, skb->truesize); | |
1da177e4 LT |
1052 | } |
1053 | ||
67edfef7 | 1054 | /* Initialize TSO segments for a packet. */ |
5bbb432c | 1055 | static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
f6302d1d | 1056 | { |
8f26fb1c | 1057 | if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { |
f6302d1d DM |
1058 | /* Avoid the costly divide in the normal |
1059 | * non-TSO case. | |
1060 | */ | |
cd7d8498 | 1061 | tcp_skb_pcount_set(skb, 1); |
f69ad292 | 1062 | TCP_SKB_CB(skb)->tcp_gso_size = 0; |
f6302d1d | 1063 | } else { |
cd7d8498 | 1064 | tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); |
f69ad292 | 1065 | TCP_SKB_CB(skb)->tcp_gso_size = mss_now; |
1da177e4 LT |
1066 | } |
1067 | } | |
1068 | ||
91fed7a1 | 1069 | /* When a modification to fackets out becomes necessary, we need to check |
68f8353b | 1070 | * skb is counted to fackets_out or not. |
91fed7a1 | 1071 | */ |
cf533ea5 | 1072 | static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, |
91fed7a1 IJ |
1073 | int decr) |
1074 | { | |
a47e5a98 IJ |
1075 | struct tcp_sock *tp = tcp_sk(sk); |
1076 | ||
dc86967b | 1077 | if (!tp->sacked_out || tcp_is_reno(tp)) |
91fed7a1 IJ |
1078 | return; |
1079 | ||
6859d494 | 1080 | if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) |
91fed7a1 | 1081 | tp->fackets_out -= decr; |
91fed7a1 IJ |
1082 | } |
1083 | ||
797108d1 IJ |
1084 | /* Pcount in the middle of the write queue got changed, we need to do various |
1085 | * tweaks to fix counters | |
1086 | */ | |
cf533ea5 | 1087 | static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
797108d1 IJ |
1088 | { |
1089 | struct tcp_sock *tp = tcp_sk(sk); | |
1090 | ||
1091 | tp->packets_out -= decr; | |
1092 | ||
1093 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
1094 | tp->sacked_out -= decr; | |
1095 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
1096 | tp->retrans_out -= decr; | |
1097 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
1098 | tp->lost_out -= decr; | |
1099 | ||
1100 | /* Reno case is special. Sigh... */ | |
1101 | if (tcp_is_reno(tp) && decr > 0) | |
1102 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
1103 | ||
1104 | tcp_adjust_fackets_out(sk, skb, decr); | |
1105 | ||
1106 | if (tp->lost_skb_hint && | |
1107 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
52cf3cc8 | 1108 | (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) |
797108d1 IJ |
1109 | tp->lost_cnt_hint -= decr; |
1110 | ||
1111 | tcp_verify_left_out(tp); | |
1112 | } | |
1113 | ||
490cc7d0 WB |
1114 | static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) |
1115 | { | |
1116 | struct skb_shared_info *shinfo = skb_shinfo(skb); | |
1117 | ||
1118 | if (unlikely(shinfo->tx_flags & SKBTX_ANY_TSTAMP) && | |
1119 | !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { | |
1120 | struct skb_shared_info *shinfo2 = skb_shinfo(skb2); | |
1121 | u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; | |
1122 | ||
1123 | shinfo->tx_flags &= ~tsflags; | |
1124 | shinfo2->tx_flags |= tsflags; | |
1125 | swap(shinfo->tskey, shinfo2->tskey); | |
1126 | } | |
1127 | } | |
1128 | ||
1da177e4 LT |
1129 | /* Function to create two new TCP segments. Shrinks the given segment |
1130 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 1131 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
1132 | * Remember, these are still headerless SKBs at this point. |
1133 | */ | |
056834d9 | 1134 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, |
6cc55e09 | 1135 | unsigned int mss_now, gfp_t gfp) |
1da177e4 LT |
1136 | { |
1137 | struct tcp_sock *tp = tcp_sk(sk); | |
1138 | struct sk_buff *buff; | |
6475be16 | 1139 | int nsize, old_factor; |
b60b49ea | 1140 | int nlen; |
9ce01461 | 1141 | u8 flags; |
1da177e4 | 1142 | |
2fceec13 IJ |
1143 | if (WARN_ON(len > skb->len)) |
1144 | return -EINVAL; | |
6a438bbe | 1145 | |
1da177e4 LT |
1146 | nsize = skb_headlen(skb) - len; |
1147 | if (nsize < 0) | |
1148 | nsize = 0; | |
1149 | ||
6cc55e09 | 1150 | if (skb_unclone(skb, gfp)) |
1da177e4 LT |
1151 | return -ENOMEM; |
1152 | ||
1153 | /* Get a new skb... force flag on. */ | |
eb934478 | 1154 | buff = sk_stream_alloc_skb(sk, nsize, gfp, true); |
51456b29 | 1155 | if (!buff) |
1da177e4 | 1156 | return -ENOMEM; /* We'll just try again later. */ |
ef5cb973 | 1157 | |
3ab224be HA |
1158 | sk->sk_wmem_queued += buff->truesize; |
1159 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea HX |
1160 | nlen = skb->len - len - nsize; |
1161 | buff->truesize += nlen; | |
1162 | skb->truesize -= nlen; | |
1da177e4 LT |
1163 | |
1164 | /* Correct the sequence numbers. */ | |
1165 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1166 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1167 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1168 | ||
1169 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1170 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1171 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1172 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
e14c3caf | 1173 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 | 1174 | |
84fa7933 | 1175 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { |
1da177e4 | 1176 | /* Copy and checksum data tail into the new buffer. */ |
056834d9 IJ |
1177 | buff->csum = csum_partial_copy_nocheck(skb->data + len, |
1178 | skb_put(buff, nsize), | |
1da177e4 LT |
1179 | nsize, 0); |
1180 | ||
1181 | skb_trim(skb, len); | |
1182 | ||
1183 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
1184 | } else { | |
84fa7933 | 1185 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1186 | skb_split(skb, buff, len); |
1187 | } | |
1188 | ||
1189 | buff->ip_summed = skb->ip_summed; | |
1190 | ||
a61bbcf2 | 1191 | buff->tstamp = skb->tstamp; |
490cc7d0 | 1192 | tcp_fragment_tstamp(skb, buff); |
1da177e4 | 1193 | |
6475be16 DM |
1194 | old_factor = tcp_skb_pcount(skb); |
1195 | ||
1da177e4 | 1196 | /* Fix up tso_factor for both original and new SKB. */ |
5bbb432c ED |
1197 | tcp_set_skb_tso_segs(skb, mss_now); |
1198 | tcp_set_skb_tso_segs(buff, mss_now); | |
1da177e4 | 1199 | |
6475be16 DM |
1200 | /* If this packet has been sent out already, we must |
1201 | * adjust the various packet counters. | |
1202 | */ | |
cf0b450c | 1203 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1204 | int diff = old_factor - tcp_skb_pcount(skb) - |
1205 | tcp_skb_pcount(buff); | |
1da177e4 | 1206 | |
797108d1 IJ |
1207 | if (diff) |
1208 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1209 | } |
1210 | ||
1211 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1212 | __skb_header_release(buff); |
fe067e8a | 1213 | tcp_insert_write_queue_after(skb, buff, sk); |
1da177e4 LT |
1214 | |
1215 | return 0; | |
1216 | } | |
1217 | ||
1218 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
1219 | * eventually). The difference is that pulled data not copied, but | |
1220 | * immediately discarded. | |
1221 | */ | |
f2911969 | 1222 | static void __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 | 1223 | { |
7b7fc97a | 1224 | struct skb_shared_info *shinfo; |
1da177e4 LT |
1225 | int i, k, eat; |
1226 | ||
4fa48bf3 ED |
1227 | eat = min_t(int, len, skb_headlen(skb)); |
1228 | if (eat) { | |
1229 | __skb_pull(skb, eat); | |
1230 | len -= eat; | |
1231 | if (!len) | |
1232 | return; | |
1233 | } | |
1da177e4 LT |
1234 | eat = len; |
1235 | k = 0; | |
7b7fc97a ED |
1236 | shinfo = skb_shinfo(skb); |
1237 | for (i = 0; i < shinfo->nr_frags; i++) { | |
1238 | int size = skb_frag_size(&shinfo->frags[i]); | |
9e903e08 ED |
1239 | |
1240 | if (size <= eat) { | |
aff65da0 | 1241 | skb_frag_unref(skb, i); |
9e903e08 | 1242 | eat -= size; |
1da177e4 | 1243 | } else { |
7b7fc97a | 1244 | shinfo->frags[k] = shinfo->frags[i]; |
1da177e4 | 1245 | if (eat) { |
7b7fc97a ED |
1246 | shinfo->frags[k].page_offset += eat; |
1247 | skb_frag_size_sub(&shinfo->frags[k], eat); | |
1da177e4 LT |
1248 | eat = 0; |
1249 | } | |
1250 | k++; | |
1251 | } | |
1252 | } | |
7b7fc97a | 1253 | shinfo->nr_frags = k; |
1da177e4 | 1254 | |
27a884dc | 1255 | skb_reset_tail_pointer(skb); |
1da177e4 LT |
1256 | skb->data_len -= len; |
1257 | skb->len = skb->data_len; | |
1da177e4 LT |
1258 | } |
1259 | ||
67edfef7 | 1260 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1261 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1262 | { | |
14bbd6a5 | 1263 | if (skb_unclone(skb, GFP_ATOMIC)) |
1da177e4 LT |
1264 | return -ENOMEM; |
1265 | ||
4fa48bf3 | 1266 | __pskb_trim_head(skb, len); |
1da177e4 LT |
1267 | |
1268 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 1269 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1270 | |
1271 | skb->truesize -= len; | |
1272 | sk->sk_wmem_queued -= len; | |
3ab224be | 1273 | sk_mem_uncharge(sk, len); |
1da177e4 LT |
1274 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); |
1275 | ||
5b35e1e6 | 1276 | /* Any change of skb->len requires recalculation of tso factor. */ |
1da177e4 | 1277 | if (tcp_skb_pcount(skb) > 1) |
5bbb432c | 1278 | tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); |
1da177e4 LT |
1279 | |
1280 | return 0; | |
1281 | } | |
1282 | ||
1b63edd6 YC |
1283 | /* Calculate MSS not accounting any TCP options. */ |
1284 | static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
5d424d5a | 1285 | { |
cf533ea5 ED |
1286 | const struct tcp_sock *tp = tcp_sk(sk); |
1287 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1288 | int mss_now; |
1289 | ||
1290 | /* Calculate base mss without TCP options: | |
1291 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1292 | */ | |
1293 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1294 | ||
67469601 ED |
1295 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1296 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1297 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1298 | ||
1299 | if (dst && dst_allfrag(dst)) | |
1300 | mss_now -= icsk->icsk_af_ops->net_frag_header_len; | |
1301 | } | |
1302 | ||
5d424d5a JH |
1303 | /* Clamp it (mss_clamp does not include tcp options) */ |
1304 | if (mss_now > tp->rx_opt.mss_clamp) | |
1305 | mss_now = tp->rx_opt.mss_clamp; | |
1306 | ||
1307 | /* Now subtract optional transport overhead */ | |
1308 | mss_now -= icsk->icsk_ext_hdr_len; | |
1309 | ||
1310 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
1311 | if (mss_now < 48) | |
1312 | mss_now = 48; | |
5d424d5a JH |
1313 | return mss_now; |
1314 | } | |
1315 | ||
1b63edd6 YC |
1316 | /* Calculate MSS. Not accounting for SACKs here. */ |
1317 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
1318 | { | |
1319 | /* Subtract TCP options size, not including SACKs */ | |
1320 | return __tcp_mtu_to_mss(sk, pmtu) - | |
1321 | (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); | |
1322 | } | |
1323 | ||
5d424d5a | 1324 | /* Inverse of above */ |
67469601 | 1325 | int tcp_mss_to_mtu(struct sock *sk, int mss) |
5d424d5a | 1326 | { |
cf533ea5 ED |
1327 | const struct tcp_sock *tp = tcp_sk(sk); |
1328 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1329 | int mtu; |
1330 | ||
1331 | mtu = mss + | |
1332 | tp->tcp_header_len + | |
1333 | icsk->icsk_ext_hdr_len + | |
1334 | icsk->icsk_af_ops->net_header_len; | |
1335 | ||
67469601 ED |
1336 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1337 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1338 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1339 | ||
1340 | if (dst && dst_allfrag(dst)) | |
1341 | mtu += icsk->icsk_af_ops->net_frag_header_len; | |
1342 | } | |
5d424d5a JH |
1343 | return mtu; |
1344 | } | |
1345 | ||
67edfef7 | 1346 | /* MTU probing init per socket */ |
5d424d5a JH |
1347 | void tcp_mtup_init(struct sock *sk) |
1348 | { | |
1349 | struct tcp_sock *tp = tcp_sk(sk); | |
1350 | struct inet_connection_sock *icsk = inet_csk(sk); | |
b0f9ca53 | 1351 | struct net *net = sock_net(sk); |
5d424d5a | 1352 | |
b0f9ca53 | 1353 | icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; |
5d424d5a | 1354 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + |
e905a9ed | 1355 | icsk->icsk_af_ops->net_header_len; |
b0f9ca53 | 1356 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); |
5d424d5a | 1357 | icsk->icsk_mtup.probe_size = 0; |
05cbc0db FD |
1358 | if (icsk->icsk_mtup.enabled) |
1359 | icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; | |
5d424d5a | 1360 | } |
4bc2f18b | 1361 | EXPORT_SYMBOL(tcp_mtup_init); |
5d424d5a | 1362 | |
1da177e4 LT |
1363 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1364 | ||
1365 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1366 | for TCP options, but includes only bare TCP header. | |
1367 | ||
1368 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1369 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1370 | It also does not include TCP options. |
1371 | ||
d83d8461 | 1372 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1373 | |
1374 | tp->mss_cache is current effective sending mss, including | |
1375 | all tcp options except for SACKs. It is evaluated, | |
1376 | taking into account current pmtu, but never exceeds | |
1377 | tp->rx_opt.mss_clamp. | |
1378 | ||
1379 | NOTE1. rfc1122 clearly states that advertised MSS | |
1380 | DOES NOT include either tcp or ip options. | |
1381 | ||
d83d8461 ACM |
1382 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1383 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1384 | */ |
1da177e4 LT |
1385 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1386 | { | |
1387 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1388 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1389 | int mss_now; |
1da177e4 | 1390 | |
5d424d5a JH |
1391 | if (icsk->icsk_mtup.search_high > pmtu) |
1392 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1393 | |
5d424d5a | 1394 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1395 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1396 | |
1397 | /* And store cached results */ | |
d83d8461 | 1398 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1399 | if (icsk->icsk_mtup.enabled) |
1400 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1401 | tp->mss_cache = mss_now; |
1da177e4 LT |
1402 | |
1403 | return mss_now; | |
1404 | } | |
4bc2f18b | 1405 | EXPORT_SYMBOL(tcp_sync_mss); |
1da177e4 LT |
1406 | |
1407 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1408 | * and even PMTU discovery events into account. | |
1da177e4 | 1409 | */ |
0c54b85f | 1410 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 | 1411 | { |
cf533ea5 ED |
1412 | const struct tcp_sock *tp = tcp_sk(sk); |
1413 | const struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1414 | u32 mss_now; |
95c96174 | 1415 | unsigned int header_len; |
33ad798c AL |
1416 | struct tcp_out_options opts; |
1417 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1418 | |
1419 | mss_now = tp->mss_cache; | |
1420 | ||
1da177e4 LT |
1421 | if (dst) { |
1422 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1423 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1424 | mss_now = tcp_sync_mss(sk, mtu); |
1425 | } | |
1426 | ||
33ad798c AL |
1427 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1428 | sizeof(struct tcphdr); | |
1429 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1430 | * some common options. If this is an odd packet (because we have SACK | |
1431 | * blocks etc) then our calculated header_len will be different, and | |
1432 | * we have to adjust mss_now correspondingly */ | |
1433 | if (header_len != tp->tcp_header_len) { | |
1434 | int delta = (int) header_len - tp->tcp_header_len; | |
1435 | mss_now -= delta; | |
1436 | } | |
cfb6eeb4 | 1437 | |
1da177e4 LT |
1438 | return mss_now; |
1439 | } | |
1440 | ||
86fd14ad WP |
1441 | /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. |
1442 | * As additional protections, we do not touch cwnd in retransmission phases, | |
1443 | * and if application hit its sndbuf limit recently. | |
1444 | */ | |
1445 | static void tcp_cwnd_application_limited(struct sock *sk) | |
1446 | { | |
1447 | struct tcp_sock *tp = tcp_sk(sk); | |
1448 | ||
1449 | if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && | |
1450 | sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { | |
1451 | /* Limited by application or receiver window. */ | |
1452 | u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); | |
1453 | u32 win_used = max(tp->snd_cwnd_used, init_win); | |
1454 | if (win_used < tp->snd_cwnd) { | |
1455 | tp->snd_ssthresh = tcp_current_ssthresh(sk); | |
1456 | tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; | |
1457 | } | |
1458 | tp->snd_cwnd_used = 0; | |
1459 | } | |
1460 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1461 | } | |
1462 | ||
ca8a2263 | 1463 | static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) |
a762a980 | 1464 | { |
9e412ba7 | 1465 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1466 | |
ca8a2263 NC |
1467 | /* Track the maximum number of outstanding packets in each |
1468 | * window, and remember whether we were cwnd-limited then. | |
1469 | */ | |
1470 | if (!before(tp->snd_una, tp->max_packets_seq) || | |
1471 | tp->packets_out > tp->max_packets_out) { | |
1472 | tp->max_packets_out = tp->packets_out; | |
1473 | tp->max_packets_seq = tp->snd_nxt; | |
1474 | tp->is_cwnd_limited = is_cwnd_limited; | |
1475 | } | |
e114a710 | 1476 | |
24901551 | 1477 | if (tcp_is_cwnd_limited(sk)) { |
a762a980 DM |
1478 | /* Network is feed fully. */ |
1479 | tp->snd_cwnd_used = 0; | |
1480 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1481 | } else { | |
1482 | /* Network starves. */ | |
1483 | if (tp->packets_out > tp->snd_cwnd_used) | |
1484 | tp->snd_cwnd_used = tp->packets_out; | |
1485 | ||
15d33c07 DM |
1486 | if (sysctl_tcp_slow_start_after_idle && |
1487 | (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) | |
a762a980 DM |
1488 | tcp_cwnd_application_limited(sk); |
1489 | } | |
1490 | } | |
1491 | ||
d4589926 ED |
1492 | /* Minshall's variant of the Nagle send check. */ |
1493 | static bool tcp_minshall_check(const struct tcp_sock *tp) | |
1494 | { | |
1495 | return after(tp->snd_sml, tp->snd_una) && | |
1496 | !after(tp->snd_sml, tp->snd_nxt); | |
1497 | } | |
1498 | ||
1499 | /* Update snd_sml if this skb is under mss | |
1500 | * Note that a TSO packet might end with a sub-mss segment | |
1501 | * The test is really : | |
1502 | * if ((skb->len % mss) != 0) | |
1503 | * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1504 | * But we can avoid doing the divide again given we already have | |
1505 | * skb_pcount = skb->len / mss_now | |
0e3a4803 | 1506 | */ |
d4589926 ED |
1507 | static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
1508 | const struct sk_buff *skb) | |
1509 | { | |
1510 | if (skb->len < tcp_skb_pcount(skb) * mss_now) | |
1511 | tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1512 | } | |
1513 | ||
1514 | /* Return false, if packet can be sent now without violation Nagle's rules: | |
1515 | * 1. It is full sized. (provided by caller in %partial bool) | |
1516 | * 2. Or it contains FIN. (already checked by caller) | |
1517 | * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. | |
1518 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
1519 | * With Minshall's modification: all sent small packets are ACKed. | |
1520 | */ | |
1521 | static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, | |
cc93fc51 | 1522 | int nonagle) |
d4589926 ED |
1523 | { |
1524 | return partial && | |
1525 | ((nonagle & TCP_NAGLE_CORK) || | |
1526 | (!nonagle && tp->packets_out && tcp_minshall_check(tp))); | |
1527 | } | |
605ad7f1 ED |
1528 | |
1529 | /* Return how many segs we'd like on a TSO packet, | |
1530 | * to send one TSO packet per ms | |
1531 | */ | |
1532 | static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now) | |
1533 | { | |
1534 | u32 bytes, segs; | |
1535 | ||
1536 | bytes = min(sk->sk_pacing_rate >> 10, | |
1537 | sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); | |
1538 | ||
1539 | /* Goal is to send at least one packet per ms, | |
1540 | * not one big TSO packet every 100 ms. | |
1541 | * This preserves ACK clocking and is consistent | |
1542 | * with tcp_tso_should_defer() heuristic. | |
1543 | */ | |
1544 | segs = max_t(u32, bytes / mss_now, sysctl_tcp_min_tso_segs); | |
1545 | ||
1546 | return min_t(u32, segs, sk->sk_gso_max_segs); | |
1547 | } | |
1548 | ||
d4589926 ED |
1549 | /* Returns the portion of skb which can be sent right away */ |
1550 | static unsigned int tcp_mss_split_point(const struct sock *sk, | |
1551 | const struct sk_buff *skb, | |
1552 | unsigned int mss_now, | |
1553 | unsigned int max_segs, | |
1554 | int nonagle) | |
c1b4a7e6 | 1555 | { |
cf533ea5 | 1556 | const struct tcp_sock *tp = tcp_sk(sk); |
d4589926 | 1557 | u32 partial, needed, window, max_len; |
c1b4a7e6 | 1558 | |
90840def | 1559 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
1485348d | 1560 | max_len = mss_now * max_segs; |
0e3a4803 | 1561 | |
1485348d BH |
1562 | if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
1563 | return max_len; | |
0e3a4803 | 1564 | |
5ea3a748 IJ |
1565 | needed = min(skb->len, window); |
1566 | ||
1485348d BH |
1567 | if (max_len <= needed) |
1568 | return max_len; | |
0e3a4803 | 1569 | |
d4589926 ED |
1570 | partial = needed % mss_now; |
1571 | /* If last segment is not a full MSS, check if Nagle rules allow us | |
1572 | * to include this last segment in this skb. | |
1573 | * Otherwise, we'll split the skb at last MSS boundary | |
1574 | */ | |
cc93fc51 | 1575 | if (tcp_nagle_check(partial != 0, tp, nonagle)) |
d4589926 ED |
1576 | return needed - partial; |
1577 | ||
1578 | return needed; | |
c1b4a7e6 DM |
1579 | } |
1580 | ||
1581 | /* Can at least one segment of SKB be sent right now, according to the | |
1582 | * congestion window rules? If so, return how many segments are allowed. | |
1583 | */ | |
cf533ea5 ED |
1584 | static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
1585 | const struct sk_buff *skb) | |
c1b4a7e6 | 1586 | { |
d649a7a8 | 1587 | u32 in_flight, cwnd, halfcwnd; |
c1b4a7e6 DM |
1588 | |
1589 | /* Don't be strict about the congestion window for the final FIN. */ | |
4de075e0 ED |
1590 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
1591 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
1592 | return 1; |
1593 | ||
1594 | in_flight = tcp_packets_in_flight(tp); | |
1595 | cwnd = tp->snd_cwnd; | |
d649a7a8 ED |
1596 | if (in_flight >= cwnd) |
1597 | return 0; | |
c1b4a7e6 | 1598 | |
d649a7a8 ED |
1599 | /* For better scheduling, ensure we have at least |
1600 | * 2 GSO packets in flight. | |
1601 | */ | |
1602 | halfcwnd = max(cwnd >> 1, 1U); | |
1603 | return min(halfcwnd, cwnd - in_flight); | |
c1b4a7e6 DM |
1604 | } |
1605 | ||
b595076a | 1606 | /* Initialize TSO state of a skb. |
67edfef7 | 1607 | * This must be invoked the first time we consider transmitting |
c1b4a7e6 DM |
1608 | * SKB onto the wire. |
1609 | */ | |
5bbb432c | 1610 | static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
c1b4a7e6 DM |
1611 | { |
1612 | int tso_segs = tcp_skb_pcount(skb); | |
1613 | ||
f8269a49 | 1614 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
5bbb432c | 1615 | tcp_set_skb_tso_segs(skb, mss_now); |
c1b4a7e6 DM |
1616 | tso_segs = tcp_skb_pcount(skb); |
1617 | } | |
1618 | return tso_segs; | |
1619 | } | |
1620 | ||
c1b4a7e6 | 1621 | |
a2a385d6 | 1622 | /* Return true if the Nagle test allows this packet to be |
c1b4a7e6 DM |
1623 | * sent now. |
1624 | */ | |
a2a385d6 ED |
1625 | static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
1626 | unsigned int cur_mss, int nonagle) | |
c1b4a7e6 DM |
1627 | { |
1628 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
1629 | * write_queue (they have no chances to get new data). | |
1630 | * | |
1631 | * This is implemented in the callers, where they modify the 'nonagle' | |
1632 | * argument based upon the location of SKB in the send queue. | |
1633 | */ | |
1634 | if (nonagle & TCP_NAGLE_PUSH) | |
a2a385d6 | 1635 | return true; |
c1b4a7e6 | 1636 | |
9b44190d YC |
1637 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
1638 | if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) | |
a2a385d6 | 1639 | return true; |
c1b4a7e6 | 1640 | |
cc93fc51 | 1641 | if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) |
a2a385d6 | 1642 | return true; |
c1b4a7e6 | 1643 | |
a2a385d6 | 1644 | return false; |
c1b4a7e6 DM |
1645 | } |
1646 | ||
1647 | /* Does at least the first segment of SKB fit into the send window? */ | |
a2a385d6 ED |
1648 | static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
1649 | const struct sk_buff *skb, | |
1650 | unsigned int cur_mss) | |
c1b4a7e6 DM |
1651 | { |
1652 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
1653 | ||
1654 | if (skb->len > cur_mss) | |
1655 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
1656 | ||
90840def | 1657 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
1658 | } |
1659 | ||
fe067e8a | 1660 | /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) |
c1b4a7e6 DM |
1661 | * should be put on the wire right now. If so, it returns the number of |
1662 | * packets allowed by the congestion window. | |
1663 | */ | |
cf533ea5 | 1664 | static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, |
c1b4a7e6 DM |
1665 | unsigned int cur_mss, int nonagle) |
1666 | { | |
cf533ea5 | 1667 | const struct tcp_sock *tp = tcp_sk(sk); |
c1b4a7e6 DM |
1668 | unsigned int cwnd_quota; |
1669 | ||
5bbb432c | 1670 | tcp_init_tso_segs(skb, cur_mss); |
c1b4a7e6 DM |
1671 | |
1672 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
1673 | return 0; | |
1674 | ||
1675 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
056834d9 | 1676 | if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) |
c1b4a7e6 DM |
1677 | cwnd_quota = 0; |
1678 | ||
1679 | return cwnd_quota; | |
1680 | } | |
1681 | ||
67edfef7 | 1682 | /* Test if sending is allowed right now. */ |
a2a385d6 | 1683 | bool tcp_may_send_now(struct sock *sk) |
c1b4a7e6 | 1684 | { |
cf533ea5 | 1685 | const struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 1686 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 | 1687 | |
a02cec21 | 1688 | return skb && |
0c54b85f | 1689 | tcp_snd_test(sk, skb, tcp_current_mss(sk), |
c1b4a7e6 | 1690 | (tcp_skb_is_last(sk, skb) ? |
a02cec21 | 1691 | tp->nonagle : TCP_NAGLE_PUSH)); |
c1b4a7e6 DM |
1692 | } |
1693 | ||
1694 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet | |
1695 | * which is put after SKB on the list. It is very much like | |
1696 | * tcp_fragment() except that it may make several kinds of assumptions | |
1697 | * in order to speed up the splitting operation. In particular, we | |
1698 | * know that all the data is in scatter-gather pages, and that the | |
1699 | * packet has never been sent out before (and thus is not cloned). | |
1700 | */ | |
056834d9 | 1701 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
c4ead4c5 | 1702 | unsigned int mss_now, gfp_t gfp) |
c1b4a7e6 DM |
1703 | { |
1704 | struct sk_buff *buff; | |
1705 | int nlen = skb->len - len; | |
9ce01461 | 1706 | u8 flags; |
c1b4a7e6 DM |
1707 | |
1708 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 | 1709 | if (skb->len != skb->data_len) |
6cc55e09 | 1710 | return tcp_fragment(sk, skb, len, mss_now, gfp); |
c1b4a7e6 | 1711 | |
eb934478 | 1712 | buff = sk_stream_alloc_skb(sk, 0, gfp, true); |
51456b29 | 1713 | if (unlikely(!buff)) |
c1b4a7e6 DM |
1714 | return -ENOMEM; |
1715 | ||
3ab224be HA |
1716 | sk->sk_wmem_queued += buff->truesize; |
1717 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea | 1718 | buff->truesize += nlen; |
c1b4a7e6 DM |
1719 | skb->truesize -= nlen; |
1720 | ||
1721 | /* Correct the sequence numbers. */ | |
1722 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1723 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1724 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1725 | ||
1726 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1727 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1728 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1729 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
c1b4a7e6 DM |
1730 | |
1731 | /* This packet was never sent out yet, so no SACK bits. */ | |
1732 | TCP_SKB_CB(buff)->sacked = 0; | |
1733 | ||
84fa7933 | 1734 | buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; |
c1b4a7e6 | 1735 | skb_split(skb, buff, len); |
490cc7d0 | 1736 | tcp_fragment_tstamp(skb, buff); |
c1b4a7e6 DM |
1737 | |
1738 | /* Fix up tso_factor for both original and new SKB. */ | |
5bbb432c ED |
1739 | tcp_set_skb_tso_segs(skb, mss_now); |
1740 | tcp_set_skb_tso_segs(buff, mss_now); | |
c1b4a7e6 DM |
1741 | |
1742 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1743 | __skb_header_release(buff); |
fe067e8a | 1744 | tcp_insert_write_queue_after(skb, buff, sk); |
c1b4a7e6 DM |
1745 | |
1746 | return 0; | |
1747 | } | |
1748 | ||
1749 | /* Try to defer sending, if possible, in order to minimize the amount | |
1750 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1751 | * | |
1752 | * This algorithm is from John Heffner. | |
1753 | */ | |
ca8a2263 | 1754 | static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, |
605ad7f1 | 1755 | bool *is_cwnd_limited, u32 max_segs) |
c1b4a7e6 | 1756 | { |
6687e988 | 1757 | const struct inet_connection_sock *icsk = inet_csk(sk); |
50c8339e ED |
1758 | u32 age, send_win, cong_win, limit, in_flight; |
1759 | struct tcp_sock *tp = tcp_sk(sk); | |
1760 | struct skb_mstamp now; | |
1761 | struct sk_buff *head; | |
ad9f4f50 | 1762 | int win_divisor; |
c1b4a7e6 | 1763 | |
4de075e0 | 1764 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) |
ae8064ac | 1765 | goto send_now; |
c1b4a7e6 | 1766 | |
99d7662a | 1767 | if (icsk->icsk_ca_state >= TCP_CA_Recovery) |
ae8064ac JH |
1768 | goto send_now; |
1769 | ||
5f852eb5 ED |
1770 | /* Avoid bursty behavior by allowing defer |
1771 | * only if the last write was recent. | |
1772 | */ | |
1773 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 0) | |
ae8064ac | 1774 | goto send_now; |
908a75c1 | 1775 | |
c1b4a7e6 DM |
1776 | in_flight = tcp_packets_in_flight(tp); |
1777 | ||
056834d9 | 1778 | BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); |
c1b4a7e6 | 1779 | |
90840def | 1780 | send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 DM |
1781 | |
1782 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1783 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1784 | ||
1785 | limit = min(send_win, cong_win); | |
1786 | ||
ba244fe9 | 1787 | /* If a full-sized TSO skb can be sent, do it. */ |
605ad7f1 | 1788 | if (limit >= max_segs * tp->mss_cache) |
ae8064ac | 1789 | goto send_now; |
ba244fe9 | 1790 | |
62ad2761 IJ |
1791 | /* Middle in queue won't get any more data, full sendable already? */ |
1792 | if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) | |
1793 | goto send_now; | |
1794 | ||
ad9f4f50 ED |
1795 | win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); |
1796 | if (win_divisor) { | |
c1b4a7e6 DM |
1797 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
1798 | ||
1799 | /* If at least some fraction of a window is available, | |
1800 | * just use it. | |
1801 | */ | |
ad9f4f50 | 1802 | chunk /= win_divisor; |
c1b4a7e6 | 1803 | if (limit >= chunk) |
ae8064ac | 1804 | goto send_now; |
c1b4a7e6 DM |
1805 | } else { |
1806 | /* Different approach, try not to defer past a single | |
1807 | * ACK. Receiver should ACK every other full sized | |
1808 | * frame, so if we have space for more than 3 frames | |
1809 | * then send now. | |
1810 | */ | |
6b5a5c0d | 1811 | if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
ae8064ac | 1812 | goto send_now; |
c1b4a7e6 DM |
1813 | } |
1814 | ||
50c8339e ED |
1815 | head = tcp_write_queue_head(sk); |
1816 | skb_mstamp_get(&now); | |
1817 | age = skb_mstamp_us_delta(&now, &head->skb_mstamp); | |
1818 | /* If next ACK is likely to come too late (half srtt), do not defer */ | |
1819 | if (age < (tp->srtt_us >> 4)) | |
1820 | goto send_now; | |
1821 | ||
5f852eb5 | 1822 | /* Ok, it looks like it is advisable to defer. */ |
ae8064ac | 1823 | |
d2e1339f | 1824 | if (cong_win < send_win && cong_win <= skb->len) |
ca8a2263 NC |
1825 | *is_cwnd_limited = true; |
1826 | ||
a2a385d6 | 1827 | return true; |
ae8064ac JH |
1828 | |
1829 | send_now: | |
a2a385d6 | 1830 | return false; |
c1b4a7e6 DM |
1831 | } |
1832 | ||
05cbc0db FD |
1833 | static inline void tcp_mtu_check_reprobe(struct sock *sk) |
1834 | { | |
1835 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1836 | struct tcp_sock *tp = tcp_sk(sk); | |
1837 | struct net *net = sock_net(sk); | |
1838 | u32 interval; | |
1839 | s32 delta; | |
1840 | ||
1841 | interval = net->ipv4.sysctl_tcp_probe_interval; | |
1842 | delta = tcp_time_stamp - icsk->icsk_mtup.probe_timestamp; | |
1843 | if (unlikely(delta >= interval * HZ)) { | |
1844 | int mss = tcp_current_mss(sk); | |
1845 | ||
1846 | /* Update current search range */ | |
1847 | icsk->icsk_mtup.probe_size = 0; | |
1848 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + | |
1849 | sizeof(struct tcphdr) + | |
1850 | icsk->icsk_af_ops->net_header_len; | |
1851 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
1852 | ||
1853 | /* Update probe time stamp */ | |
1854 | icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; | |
1855 | } | |
1856 | } | |
1857 | ||
5d424d5a | 1858 | /* Create a new MTU probe if we are ready. |
67edfef7 AK |
1859 | * MTU probe is regularly attempting to increase the path MTU by |
1860 | * deliberately sending larger packets. This discovers routing | |
1861 | * changes resulting in larger path MTUs. | |
1862 | * | |
5d424d5a JH |
1863 | * Returns 0 if we should wait to probe (no cwnd available), |
1864 | * 1 if a probe was sent, | |
056834d9 IJ |
1865 | * -1 otherwise |
1866 | */ | |
5d424d5a JH |
1867 | static int tcp_mtu_probe(struct sock *sk) |
1868 | { | |
1869 | struct tcp_sock *tp = tcp_sk(sk); | |
1870 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1871 | struct sk_buff *skb, *nskb, *next; | |
6b58e0a5 | 1872 | struct net *net = sock_net(sk); |
5d424d5a JH |
1873 | int len; |
1874 | int probe_size; | |
91cc17c0 | 1875 | int size_needed; |
5d424d5a JH |
1876 | int copy; |
1877 | int mss_now; | |
6b58e0a5 | 1878 | int interval; |
5d424d5a JH |
1879 | |
1880 | /* Not currently probing/verifying, | |
1881 | * not in recovery, | |
1882 | * have enough cwnd, and | |
1883 | * not SACKing (the variable headers throw things off) */ | |
1884 | if (!icsk->icsk_mtup.enabled || | |
1885 | icsk->icsk_mtup.probe_size || | |
1886 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
1887 | tp->snd_cwnd < 11 || | |
cabeccbd | 1888 | tp->rx_opt.num_sacks || tp->rx_opt.dsack) |
5d424d5a JH |
1889 | return -1; |
1890 | ||
6b58e0a5 FD |
1891 | /* Use binary search for probe_size between tcp_mss_base, |
1892 | * and current mss_clamp. if (search_high - search_low) | |
1893 | * smaller than a threshold, backoff from probing. | |
1894 | */ | |
0c54b85f | 1895 | mss_now = tcp_current_mss(sk); |
6b58e0a5 FD |
1896 | probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + |
1897 | icsk->icsk_mtup.search_low) >> 1); | |
91cc17c0 | 1898 | size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
6b58e0a5 | 1899 | interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; |
05cbc0db FD |
1900 | /* When misfortune happens, we are reprobing actively, |
1901 | * and then reprobe timer has expired. We stick with current | |
1902 | * probing process by not resetting search range to its orignal. | |
1903 | */ | |
6b58e0a5 | 1904 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || |
05cbc0db FD |
1905 | interval < net->ipv4.sysctl_tcp_probe_threshold) { |
1906 | /* Check whether enough time has elaplased for | |
1907 | * another round of probing. | |
1908 | */ | |
1909 | tcp_mtu_check_reprobe(sk); | |
5d424d5a JH |
1910 | return -1; |
1911 | } | |
1912 | ||
1913 | /* Have enough data in the send queue to probe? */ | |
7f9c33e5 | 1914 | if (tp->write_seq - tp->snd_nxt < size_needed) |
5d424d5a JH |
1915 | return -1; |
1916 | ||
91cc17c0 IJ |
1917 | if (tp->snd_wnd < size_needed) |
1918 | return -1; | |
90840def | 1919 | if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
91cc17c0 | 1920 | return 0; |
5d424d5a | 1921 | |
d67c58e9 IJ |
1922 | /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
1923 | if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { | |
1924 | if (!tcp_packets_in_flight(tp)) | |
5d424d5a JH |
1925 | return -1; |
1926 | else | |
1927 | return 0; | |
1928 | } | |
1929 | ||
1930 | /* We're allowed to probe. Build it now. */ | |
eb934478 | 1931 | nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); |
51456b29 | 1932 | if (!nskb) |
5d424d5a | 1933 | return -1; |
3ab224be HA |
1934 | sk->sk_wmem_queued += nskb->truesize; |
1935 | sk_mem_charge(sk, nskb->truesize); | |
5d424d5a | 1936 | |
fe067e8a | 1937 | skb = tcp_send_head(sk); |
5d424d5a JH |
1938 | |
1939 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
1940 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
4de075e0 | 1941 | TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
5d424d5a JH |
1942 | TCP_SKB_CB(nskb)->sacked = 0; |
1943 | nskb->csum = 0; | |
84fa7933 | 1944 | nskb->ip_summed = skb->ip_summed; |
5d424d5a | 1945 | |
50c4817e IJ |
1946 | tcp_insert_write_queue_before(nskb, skb, sk); |
1947 | ||
5d424d5a | 1948 | len = 0; |
234b6860 | 1949 | tcp_for_write_queue_from_safe(skb, next, sk) { |
5d424d5a JH |
1950 | copy = min_t(int, skb->len, probe_size - len); |
1951 | if (nskb->ip_summed) | |
1952 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); | |
1953 | else | |
1954 | nskb->csum = skb_copy_and_csum_bits(skb, 0, | |
056834d9 IJ |
1955 | skb_put(nskb, copy), |
1956 | copy, nskb->csum); | |
5d424d5a JH |
1957 | |
1958 | if (skb->len <= copy) { | |
1959 | /* We've eaten all the data from this skb. | |
1960 | * Throw it away. */ | |
4de075e0 | 1961 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
fe067e8a | 1962 | tcp_unlink_write_queue(skb, sk); |
3ab224be | 1963 | sk_wmem_free_skb(sk, skb); |
5d424d5a | 1964 | } else { |
4de075e0 | 1965 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
a3433f35 | 1966 | ~(TCPHDR_FIN|TCPHDR_PSH); |
5d424d5a JH |
1967 | if (!skb_shinfo(skb)->nr_frags) { |
1968 | skb_pull(skb, copy); | |
84fa7933 | 1969 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
056834d9 IJ |
1970 | skb->csum = csum_partial(skb->data, |
1971 | skb->len, 0); | |
5d424d5a JH |
1972 | } else { |
1973 | __pskb_trim_head(skb, copy); | |
5bbb432c | 1974 | tcp_set_skb_tso_segs(skb, mss_now); |
5d424d5a JH |
1975 | } |
1976 | TCP_SKB_CB(skb)->seq += copy; | |
1977 | } | |
1978 | ||
1979 | len += copy; | |
234b6860 IJ |
1980 | |
1981 | if (len >= probe_size) | |
1982 | break; | |
5d424d5a | 1983 | } |
5bbb432c | 1984 | tcp_init_tso_segs(nskb, nskb->len); |
5d424d5a JH |
1985 | |
1986 | /* We're ready to send. If this fails, the probe will | |
7faee5c0 ED |
1987 | * be resegmented into mss-sized pieces by tcp_write_xmit(). |
1988 | */ | |
5d424d5a JH |
1989 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { |
1990 | /* Decrement cwnd here because we are sending | |
056834d9 | 1991 | * effectively two packets. */ |
5d424d5a | 1992 | tp->snd_cwnd--; |
66f5fe62 | 1993 | tcp_event_new_data_sent(sk, nskb); |
5d424d5a JH |
1994 | |
1995 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
1996 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
1997 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
1998 | |
1999 | return 1; | |
2000 | } | |
2001 | ||
2002 | return -1; | |
2003 | } | |
2004 | ||
1da177e4 LT |
2005 | /* This routine writes packets to the network. It advances the |
2006 | * send_head. This happens as incoming acks open up the remote | |
2007 | * window for us. | |
2008 | * | |
f8269a49 IJ |
2009 | * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
2010 | * snd_up-64k-mss .. snd_up cannot be large. However, taking into | |
2011 | * account rare use of URG, this is not a big flaw. | |
2012 | * | |
6ba8a3b1 ND |
2013 | * Send at most one packet when push_one > 0. Temporarily ignore |
2014 | * cwnd limit to force at most one packet out when push_one == 2. | |
2015 | ||
a2a385d6 ED |
2016 | * Returns true, if no segments are in flight and we have queued segments, |
2017 | * but cannot send anything now because of SWS or another problem. | |
1da177e4 | 2018 | */ |
a2a385d6 ED |
2019 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
2020 | int push_one, gfp_t gfp) | |
1da177e4 LT |
2021 | { |
2022 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 2023 | struct sk_buff *skb; |
c1b4a7e6 DM |
2024 | unsigned int tso_segs, sent_pkts; |
2025 | int cwnd_quota; | |
5d424d5a | 2026 | int result; |
ca8a2263 | 2027 | bool is_cwnd_limited = false; |
605ad7f1 | 2028 | u32 max_segs; |
1da177e4 | 2029 | |
92df7b51 | 2030 | sent_pkts = 0; |
5d424d5a | 2031 | |
d5dd9175 IJ |
2032 | if (!push_one) { |
2033 | /* Do MTU probing. */ | |
2034 | result = tcp_mtu_probe(sk); | |
2035 | if (!result) { | |
a2a385d6 | 2036 | return false; |
d5dd9175 IJ |
2037 | } else if (result > 0) { |
2038 | sent_pkts = 1; | |
2039 | } | |
5d424d5a JH |
2040 | } |
2041 | ||
605ad7f1 | 2042 | max_segs = tcp_tso_autosize(sk, mss_now); |
fe067e8a | 2043 | while ((skb = tcp_send_head(sk))) { |
c8ac3774 HX |
2044 | unsigned int limit; |
2045 | ||
5bbb432c | 2046 | tso_segs = tcp_init_tso_segs(skb, mss_now); |
c1b4a7e6 | 2047 | BUG_ON(!tso_segs); |
aa93466b | 2048 | |
9d186cac | 2049 | if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { |
7faee5c0 ED |
2050 | /* "skb_mstamp" is used as a start point for the retransmit timer */ |
2051 | skb_mstamp_get(&skb->skb_mstamp); | |
ec342325 | 2052 | goto repair; /* Skip network transmission */ |
9d186cac | 2053 | } |
ec342325 | 2054 | |
b68e9f85 | 2055 | cwnd_quota = tcp_cwnd_test(tp, skb); |
6ba8a3b1 ND |
2056 | if (!cwnd_quota) { |
2057 | if (push_one == 2) | |
2058 | /* Force out a loss probe pkt. */ | |
2059 | cwnd_quota = 1; | |
2060 | else | |
2061 | break; | |
2062 | } | |
b68e9f85 HX |
2063 | |
2064 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) | |
2065 | break; | |
2066 | ||
d6a4e26a | 2067 | if (tso_segs == 1) { |
c1b4a7e6 DM |
2068 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, |
2069 | (tcp_skb_is_last(sk, skb) ? | |
2070 | nonagle : TCP_NAGLE_PUSH)))) | |
2071 | break; | |
2072 | } else { | |
ca8a2263 | 2073 | if (!push_one && |
605ad7f1 ED |
2074 | tcp_tso_should_defer(sk, skb, &is_cwnd_limited, |
2075 | max_segs)) | |
c1b4a7e6 DM |
2076 | break; |
2077 | } | |
aa93466b | 2078 | |
605ad7f1 | 2079 | limit = mss_now; |
d6a4e26a | 2080 | if (tso_segs > 1 && !tcp_urg_mode(tp)) |
605ad7f1 ED |
2081 | limit = tcp_mss_split_point(sk, skb, mss_now, |
2082 | min_t(unsigned int, | |
2083 | cwnd_quota, | |
2084 | max_segs), | |
2085 | nonagle); | |
2086 | ||
2087 | if (skb->len > limit && | |
2088 | unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) | |
2089 | break; | |
2090 | ||
c9eeec26 ED |
2091 | /* TCP Small Queues : |
2092 | * Control number of packets in qdisc/devices to two packets / or ~1 ms. | |
2093 | * This allows for : | |
2094 | * - better RTT estimation and ACK scheduling | |
2095 | * - faster recovery | |
2096 | * - high rates | |
98e09386 ED |
2097 | * Alas, some drivers / subsystems require a fair amount |
2098 | * of queued bytes to ensure line rate. | |
2099 | * One example is wifi aggregation (802.11 AMPDU) | |
46d3ceab | 2100 | */ |
605ad7f1 ED |
2101 | limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10); |
2102 | limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes); | |
c9eeec26 ED |
2103 | |
2104 | if (atomic_read(&sk->sk_wmem_alloc) > limit) { | |
46d3ceab | 2105 | set_bit(TSQ_THROTTLED, &tp->tsq_flags); |
bf06200e JO |
2106 | /* It is possible TX completion already happened |
2107 | * before we set TSQ_THROTTLED, so we must | |
2108 | * test again the condition. | |
bf06200e | 2109 | */ |
4e857c58 | 2110 | smp_mb__after_atomic(); |
bf06200e JO |
2111 | if (atomic_read(&sk->sk_wmem_alloc) > limit) |
2112 | break; | |
46d3ceab | 2113 | } |
c9eeec26 | 2114 | |
d5dd9175 | 2115 | if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
92df7b51 | 2116 | break; |
1da177e4 | 2117 | |
ec342325 | 2118 | repair: |
92df7b51 DM |
2119 | /* Advance the send_head. This one is sent out. |
2120 | * This call will increment packets_out. | |
2121 | */ | |
66f5fe62 | 2122 | tcp_event_new_data_sent(sk, skb); |
1da177e4 | 2123 | |
92df7b51 | 2124 | tcp_minshall_update(tp, mss_now, skb); |
a262f0cd | 2125 | sent_pkts += tcp_skb_pcount(skb); |
d5dd9175 IJ |
2126 | |
2127 | if (push_one) | |
2128 | break; | |
92df7b51 | 2129 | } |
1da177e4 | 2130 | |
aa93466b | 2131 | if (likely(sent_pkts)) { |
684bad11 YC |
2132 | if (tcp_in_cwnd_reduction(sk)) |
2133 | tp->prr_out += sent_pkts; | |
6ba8a3b1 ND |
2134 | |
2135 | /* Send one loss probe per tail loss episode. */ | |
2136 | if (push_one != 2) | |
2137 | tcp_schedule_loss_probe(sk); | |
d2e1339f | 2138 | is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); |
ca8a2263 | 2139 | tcp_cwnd_validate(sk, is_cwnd_limited); |
a2a385d6 | 2140 | return false; |
1da177e4 | 2141 | } |
b340b264 | 2142 | return !tp->packets_out && tcp_send_head(sk); |
6ba8a3b1 ND |
2143 | } |
2144 | ||
2145 | bool tcp_schedule_loss_probe(struct sock *sk) | |
2146 | { | |
2147 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2148 | struct tcp_sock *tp = tcp_sk(sk); | |
2149 | u32 timeout, tlp_time_stamp, rto_time_stamp; | |
740b0f18 | 2150 | u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); |
6ba8a3b1 ND |
2151 | |
2152 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) | |
2153 | return false; | |
2154 | /* No consecutive loss probes. */ | |
2155 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { | |
2156 | tcp_rearm_rto(sk); | |
2157 | return false; | |
2158 | } | |
2159 | /* Don't do any loss probe on a Fast Open connection before 3WHS | |
2160 | * finishes. | |
2161 | */ | |
f9b99582 | 2162 | if (tp->fastopen_rsk) |
6ba8a3b1 ND |
2163 | return false; |
2164 | ||
2165 | /* TLP is only scheduled when next timer event is RTO. */ | |
2166 | if (icsk->icsk_pending != ICSK_TIME_RETRANS) | |
2167 | return false; | |
2168 | ||
2169 | /* Schedule a loss probe in 2*RTT for SACK capable connections | |
2170 | * in Open state, that are either limited by cwnd or application. | |
2171 | */ | |
f9b99582 | 2172 | if (sysctl_tcp_early_retrans < 3 || !tp->packets_out || |
6ba8a3b1 ND |
2173 | !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) |
2174 | return false; | |
2175 | ||
2176 | if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && | |
2177 | tcp_send_head(sk)) | |
2178 | return false; | |
2179 | ||
2180 | /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account | |
f9b99582 YC |
2181 | * for delayed ack when there's one outstanding packet. If no RTT |
2182 | * sample is available then probe after TCP_TIMEOUT_INIT. | |
6ba8a3b1 | 2183 | */ |
f9b99582 | 2184 | timeout = rtt << 1 ? : TCP_TIMEOUT_INIT; |
6ba8a3b1 ND |
2185 | if (tp->packets_out == 1) |
2186 | timeout = max_t(u32, timeout, | |
2187 | (rtt + (rtt >> 1) + TCP_DELACK_MAX)); | |
2188 | timeout = max_t(u32, timeout, msecs_to_jiffies(10)); | |
2189 | ||
2190 | /* If RTO is shorter, just schedule TLP in its place. */ | |
2191 | tlp_time_stamp = tcp_time_stamp + timeout; | |
2192 | rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; | |
2193 | if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { | |
2194 | s32 delta = rto_time_stamp - tcp_time_stamp; | |
2195 | if (delta > 0) | |
2196 | timeout = delta; | |
2197 | } | |
2198 | ||
2199 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, | |
2200 | TCP_RTO_MAX); | |
2201 | return true; | |
2202 | } | |
2203 | ||
1f3279ae ED |
2204 | /* Thanks to skb fast clones, we can detect if a prior transmit of |
2205 | * a packet is still in a qdisc or driver queue. | |
2206 | * In this case, there is very little point doing a retransmit ! | |
2207 | * Note: This is called from BH context only. | |
2208 | */ | |
2209 | static bool skb_still_in_host_queue(const struct sock *sk, | |
2210 | const struct sk_buff *skb) | |
2211 | { | |
39bb5e62 | 2212 | if (unlikely(skb_fclone_busy(sk, skb))) { |
1f3279ae ED |
2213 | NET_INC_STATS_BH(sock_net(sk), |
2214 | LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); | |
2215 | return true; | |
2216 | } | |
2217 | return false; | |
2218 | } | |
2219 | ||
b340b264 | 2220 | /* When probe timeout (PTO) fires, try send a new segment if possible, else |
6ba8a3b1 ND |
2221 | * retransmit the last segment. |
2222 | */ | |
2223 | void tcp_send_loss_probe(struct sock *sk) | |
2224 | { | |
9b717a8d | 2225 | struct tcp_sock *tp = tcp_sk(sk); |
6ba8a3b1 ND |
2226 | struct sk_buff *skb; |
2227 | int pcount; | |
2228 | int mss = tcp_current_mss(sk); | |
6ba8a3b1 | 2229 | |
b340b264 YC |
2230 | skb = tcp_send_head(sk); |
2231 | if (skb) { | |
2232 | if (tcp_snd_wnd_test(tp, skb, mss)) { | |
2233 | pcount = tp->packets_out; | |
2234 | tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); | |
2235 | if (tp->packets_out > pcount) | |
2236 | goto probe_sent; | |
2237 | goto rearm_timer; | |
2238 | } | |
2239 | skb = tcp_write_queue_prev(sk, skb); | |
2240 | } else { | |
2241 | skb = tcp_write_queue_tail(sk); | |
6ba8a3b1 ND |
2242 | } |
2243 | ||
9b717a8d ND |
2244 | /* At most one outstanding TLP retransmission. */ |
2245 | if (tp->tlp_high_seq) | |
2246 | goto rearm_timer; | |
2247 | ||
6ba8a3b1 | 2248 | /* Retransmit last segment. */ |
6ba8a3b1 ND |
2249 | if (WARN_ON(!skb)) |
2250 | goto rearm_timer; | |
2251 | ||
1f3279ae ED |
2252 | if (skb_still_in_host_queue(sk, skb)) |
2253 | goto rearm_timer; | |
2254 | ||
6ba8a3b1 ND |
2255 | pcount = tcp_skb_pcount(skb); |
2256 | if (WARN_ON(!pcount)) | |
2257 | goto rearm_timer; | |
2258 | ||
2259 | if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { | |
6cc55e09 OP |
2260 | if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, |
2261 | GFP_ATOMIC))) | |
6ba8a3b1 | 2262 | goto rearm_timer; |
b340b264 | 2263 | skb = tcp_write_queue_next(sk, skb); |
6ba8a3b1 ND |
2264 | } |
2265 | ||
2266 | if (WARN_ON(!skb || !tcp_skb_pcount(skb))) | |
2267 | goto rearm_timer; | |
2268 | ||
b340b264 YC |
2269 | if (__tcp_retransmit_skb(sk, skb)) |
2270 | goto rearm_timer; | |
6ba8a3b1 | 2271 | |
9b717a8d | 2272 | /* Record snd_nxt for loss detection. */ |
b340b264 | 2273 | tp->tlp_high_seq = tp->snd_nxt; |
9b717a8d | 2274 | |
b340b264 YC |
2275 | probe_sent: |
2276 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); | |
2277 | /* Reset s.t. tcp_rearm_rto will restart timer from now */ | |
2278 | inet_csk(sk)->icsk_pending = 0; | |
6ba8a3b1 | 2279 | rearm_timer: |
fcd16c0a | 2280 | tcp_rearm_rto(sk); |
1da177e4 LT |
2281 | } |
2282 | ||
a762a980 DM |
2283 | /* Push out any pending frames which were held back due to |
2284 | * TCP_CORK or attempt at coalescing tiny packets. | |
2285 | * The socket must be locked by the caller. | |
2286 | */ | |
9e412ba7 IJ |
2287 | void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
2288 | int nonagle) | |
a762a980 | 2289 | { |
726e07a8 IJ |
2290 | /* If we are closed, the bytes will have to remain here. |
2291 | * In time closedown will finish, we empty the write queue and | |
2292 | * all will be happy. | |
2293 | */ | |
2294 | if (unlikely(sk->sk_state == TCP_CLOSE)) | |
2295 | return; | |
2296 | ||
99a1dec7 | 2297 | if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
7450aaf6 | 2298 | sk_gfp_mask(sk, GFP_ATOMIC))) |
726e07a8 | 2299 | tcp_check_probe_timer(sk); |
a762a980 DM |
2300 | } |
2301 | ||
c1b4a7e6 DM |
2302 | /* Send _single_ skb sitting at the send head. This function requires |
2303 | * true push pending frames to setup probe timer etc. | |
2304 | */ | |
2305 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
2306 | { | |
fe067e8a | 2307 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
2308 | |
2309 | BUG_ON(!skb || skb->len < mss_now); | |
2310 | ||
d5dd9175 | 2311 | tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
c1b4a7e6 DM |
2312 | } |
2313 | ||
1da177e4 LT |
2314 | /* This function returns the amount that we can raise the |
2315 | * usable window based on the following constraints | |
e905a9ed | 2316 | * |
1da177e4 LT |
2317 | * 1. The window can never be shrunk once it is offered (RFC 793) |
2318 | * 2. We limit memory per socket | |
2319 | * | |
2320 | * RFC 1122: | |
2321 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
2322 | * RECV.NEXT + RCV.WIN fixed until: | |
2323 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
2324 | * | |
2325 | * i.e. don't raise the right edge of the window until you can raise | |
2326 | * it at least MSS bytes. | |
2327 | * | |
2328 | * Unfortunately, the recommended algorithm breaks header prediction, | |
2329 | * since header prediction assumes th->window stays fixed. | |
2330 | * | |
2331 | * Strictly speaking, keeping th->window fixed violates the receiver | |
2332 | * side SWS prevention criteria. The problem is that under this rule | |
2333 | * a stream of single byte packets will cause the right side of the | |
2334 | * window to always advance by a single byte. | |
e905a9ed | 2335 | * |
1da177e4 LT |
2336 | * Of course, if the sender implements sender side SWS prevention |
2337 | * then this will not be a problem. | |
e905a9ed | 2338 | * |
1da177e4 | 2339 | * BSD seems to make the following compromise: |
e905a9ed | 2340 | * |
1da177e4 LT |
2341 | * If the free space is less than the 1/4 of the maximum |
2342 | * space available and the free space is less than 1/2 mss, | |
2343 | * then set the window to 0. | |
2344 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
2345 | * Otherwise, just prevent the window from shrinking | |
2346 | * and from being larger than the largest representable value. | |
2347 | * | |
2348 | * This prevents incremental opening of the window in the regime | |
2349 | * where TCP is limited by the speed of the reader side taking | |
2350 | * data out of the TCP receive queue. It does nothing about | |
2351 | * those cases where the window is constrained on the sender side | |
2352 | * because the pipeline is full. | |
2353 | * | |
2354 | * BSD also seems to "accidentally" limit itself to windows that are a | |
2355 | * multiple of MSS, at least until the free space gets quite small. | |
2356 | * This would appear to be a side effect of the mbuf implementation. | |
2357 | * Combining these two algorithms results in the observed behavior | |
2358 | * of having a fixed window size at almost all times. | |
2359 | * | |
2360 | * Below we obtain similar behavior by forcing the offered window to | |
2361 | * a multiple of the mss when it is feasible to do so. | |
2362 | * | |
2363 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
2364 | * Regular options like TIMESTAMP are taken into account. | |
2365 | */ | |
2366 | u32 __tcp_select_window(struct sock *sk) | |
2367 | { | |
463c84b9 | 2368 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 2369 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 2370 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
2371 | * here. I don't know if the value based on our guesses |
2372 | * of peer's MSS is better for the performance. It's more correct | |
2373 | * but may be worse for the performance because of rcv_mss | |
2374 | * fluctuations. --SAW 1998/11/1 | |
2375 | */ | |
463c84b9 | 2376 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 | 2377 | int free_space = tcp_space(sk); |
86c1a045 FW |
2378 | int allowed_space = tcp_full_space(sk); |
2379 | int full_space = min_t(int, tp->window_clamp, allowed_space); | |
1da177e4 LT |
2380 | int window; |
2381 | ||
2382 | if (mss > full_space) | |
e905a9ed | 2383 | mss = full_space; |
1da177e4 | 2384 | |
b92edbe0 | 2385 | if (free_space < (full_space >> 1)) { |
463c84b9 | 2386 | icsk->icsk_ack.quick = 0; |
1da177e4 | 2387 | |
b8da51eb | 2388 | if (tcp_under_memory_pressure(sk)) |
056834d9 IJ |
2389 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, |
2390 | 4U * tp->advmss); | |
1da177e4 | 2391 | |
86c1a045 FW |
2392 | /* free_space might become our new window, make sure we don't |
2393 | * increase it due to wscale. | |
2394 | */ | |
2395 | free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); | |
2396 | ||
2397 | /* if free space is less than mss estimate, or is below 1/16th | |
2398 | * of the maximum allowed, try to move to zero-window, else | |
2399 | * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and | |
2400 | * new incoming data is dropped due to memory limits. | |
2401 | * With large window, mss test triggers way too late in order | |
2402 | * to announce zero window in time before rmem limit kicks in. | |
2403 | */ | |
2404 | if (free_space < (allowed_space >> 4) || free_space < mss) | |
1da177e4 LT |
2405 | return 0; |
2406 | } | |
2407 | ||
2408 | if (free_space > tp->rcv_ssthresh) | |
2409 | free_space = tp->rcv_ssthresh; | |
2410 | ||
2411 | /* Don't do rounding if we are using window scaling, since the | |
2412 | * scaled window will not line up with the MSS boundary anyway. | |
2413 | */ | |
2414 | window = tp->rcv_wnd; | |
2415 | if (tp->rx_opt.rcv_wscale) { | |
2416 | window = free_space; | |
2417 | ||
2418 | /* Advertise enough space so that it won't get scaled away. | |
2419 | * Import case: prevent zero window announcement if | |
2420 | * 1<<rcv_wscale > mss. | |
2421 | */ | |
2422 | if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) | |
2423 | window = (((window >> tp->rx_opt.rcv_wscale) + 1) | |
2424 | << tp->rx_opt.rcv_wscale); | |
2425 | } else { | |
2426 | /* Get the largest window that is a nice multiple of mss. | |
2427 | * Window clamp already applied above. | |
2428 | * If our current window offering is within 1 mss of the | |
2429 | * free space we just keep it. This prevents the divide | |
2430 | * and multiply from happening most of the time. | |
2431 | * We also don't do any window rounding when the free space | |
2432 | * is too small. | |
2433 | */ | |
2434 | if (window <= free_space - mss || window > free_space) | |
056834d9 | 2435 | window = (free_space / mss) * mss; |
84565070 | 2436 | else if (mss == full_space && |
b92edbe0 | 2437 | free_space > window + (full_space >> 1)) |
84565070 | 2438 | window = free_space; |
1da177e4 LT |
2439 | } |
2440 | ||
2441 | return window; | |
2442 | } | |
2443 | ||
cfea5a68 MKL |
2444 | void tcp_skb_collapse_tstamp(struct sk_buff *skb, |
2445 | const struct sk_buff *next_skb) | |
082ac2d5 MKL |
2446 | { |
2447 | const struct skb_shared_info *next_shinfo = skb_shinfo(next_skb); | |
2448 | u8 tsflags = next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; | |
2449 | ||
2450 | if (unlikely(tsflags)) { | |
2451 | struct skb_shared_info *shinfo = skb_shinfo(skb); | |
2452 | ||
2453 | shinfo->tx_flags |= tsflags; | |
2454 | shinfo->tskey = next_shinfo->tskey; | |
2455 | } | |
2456 | } | |
2457 | ||
4a17fc3a IJ |
2458 | /* Collapses two adjacent SKB's during retransmission. */ |
2459 | static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) | |
1da177e4 LT |
2460 | { |
2461 | struct tcp_sock *tp = tcp_sk(sk); | |
fe067e8a | 2462 | struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); |
058dc334 | 2463 | int skb_size, next_skb_size; |
1da177e4 | 2464 | |
058dc334 IJ |
2465 | skb_size = skb->len; |
2466 | next_skb_size = next_skb->len; | |
1da177e4 | 2467 | |
058dc334 | 2468 | BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
a6963a6b | 2469 | |
058dc334 | 2470 | tcp_highest_sack_combine(sk, next_skb, skb); |
1da177e4 | 2471 | |
058dc334 | 2472 | tcp_unlink_write_queue(next_skb, sk); |
1da177e4 | 2473 | |
058dc334 IJ |
2474 | skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), |
2475 | next_skb_size); | |
1da177e4 | 2476 | |
058dc334 IJ |
2477 | if (next_skb->ip_summed == CHECKSUM_PARTIAL) |
2478 | skb->ip_summed = CHECKSUM_PARTIAL; | |
1da177e4 | 2479 | |
058dc334 IJ |
2480 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
2481 | skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); | |
1da177e4 | 2482 | |
058dc334 IJ |
2483 | /* Update sequence range on original skb. */ |
2484 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1da177e4 | 2485 | |
e6c7d085 | 2486 | /* Merge over control information. This moves PSH/FIN etc. over */ |
4de075e0 | 2487 | TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
058dc334 IJ |
2488 | |
2489 | /* All done, get rid of second SKB and account for it so | |
2490 | * packet counting does not break. | |
2491 | */ | |
2492 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; | |
058dc334 IJ |
2493 | |
2494 | /* changed transmit queue under us so clear hints */ | |
ef9da47c IJ |
2495 | tcp_clear_retrans_hints_partial(tp); |
2496 | if (next_skb == tp->retransmit_skb_hint) | |
2497 | tp->retransmit_skb_hint = skb; | |
058dc334 | 2498 | |
797108d1 IJ |
2499 | tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
2500 | ||
082ac2d5 MKL |
2501 | tcp_skb_collapse_tstamp(skb, next_skb); |
2502 | ||
058dc334 | 2503 | sk_wmem_free_skb(sk, next_skb); |
1da177e4 LT |
2504 | } |
2505 | ||
67edfef7 | 2506 | /* Check if coalescing SKBs is legal. */ |
a2a385d6 | 2507 | static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
4a17fc3a IJ |
2508 | { |
2509 | if (tcp_skb_pcount(skb) > 1) | |
a2a385d6 | 2510 | return false; |
4a17fc3a IJ |
2511 | /* TODO: SACK collapsing could be used to remove this condition */ |
2512 | if (skb_shinfo(skb)->nr_frags != 0) | |
a2a385d6 | 2513 | return false; |
4a17fc3a | 2514 | if (skb_cloned(skb)) |
a2a385d6 | 2515 | return false; |
4a17fc3a | 2516 | if (skb == tcp_send_head(sk)) |
a2a385d6 | 2517 | return false; |
4a17fc3a IJ |
2518 | /* Some heurestics for collapsing over SACK'd could be invented */ |
2519 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
a2a385d6 | 2520 | return false; |
4a17fc3a | 2521 | |
a2a385d6 | 2522 | return true; |
4a17fc3a IJ |
2523 | } |
2524 | ||
67edfef7 AK |
2525 | /* Collapse packets in the retransmit queue to make to create |
2526 | * less packets on the wire. This is only done on retransmission. | |
2527 | */ | |
4a17fc3a IJ |
2528 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
2529 | int space) | |
2530 | { | |
2531 | struct tcp_sock *tp = tcp_sk(sk); | |
2532 | struct sk_buff *skb = to, *tmp; | |
a2a385d6 | 2533 | bool first = true; |
4a17fc3a IJ |
2534 | |
2535 | if (!sysctl_tcp_retrans_collapse) | |
2536 | return; | |
4de075e0 | 2537 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
4a17fc3a IJ |
2538 | return; |
2539 | ||
2540 | tcp_for_write_queue_from_safe(skb, tmp, sk) { | |
2541 | if (!tcp_can_collapse(sk, skb)) | |
2542 | break; | |
2543 | ||
2544 | space -= skb->len; | |
2545 | ||
2546 | if (first) { | |
a2a385d6 | 2547 | first = false; |
4a17fc3a IJ |
2548 | continue; |
2549 | } | |
2550 | ||
2551 | if (space < 0) | |
2552 | break; | |
2553 | /* Punt if not enough space exists in the first SKB for | |
2554 | * the data in the second | |
2555 | */ | |
a21d4572 | 2556 | if (skb->len > skb_availroom(to)) |
4a17fc3a IJ |
2557 | break; |
2558 | ||
2559 | if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) | |
2560 | break; | |
2561 | ||
2562 | tcp_collapse_retrans(sk, to); | |
2563 | } | |
2564 | } | |
2565 | ||
1da177e4 LT |
2566 | /* This retransmits one SKB. Policy decisions and retransmit queue |
2567 | * state updates are done by the caller. Returns non-zero if an | |
2568 | * error occurred which prevented the send. | |
2569 | */ | |
93b174ad | 2570 | int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) |
1da177e4 LT |
2571 | { |
2572 | struct tcp_sock *tp = tcp_sk(sk); | |
5d424d5a | 2573 | struct inet_connection_sock *icsk = inet_csk(sk); |
7d227cd2 | 2574 | unsigned int cur_mss; |
c84a5711 | 2575 | int err; |
1da177e4 | 2576 | |
5d424d5a JH |
2577 | /* Inconslusive MTU probe */ |
2578 | if (icsk->icsk_mtup.probe_size) { | |
2579 | icsk->icsk_mtup.probe_size = 0; | |
2580 | } | |
2581 | ||
1da177e4 | 2582 | /* Do not sent more than we queued. 1/4 is reserved for possible |
caa20d9a | 2583 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 LT |
2584 | */ |
2585 | if (atomic_read(&sk->sk_wmem_alloc) > | |
2586 | min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) | |
2587 | return -EAGAIN; | |
2588 | ||
1f3279ae ED |
2589 | if (skb_still_in_host_queue(sk, skb)) |
2590 | return -EBUSY; | |
2591 | ||
1da177e4 LT |
2592 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { |
2593 | if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
2594 | BUG(); | |
1da177e4 LT |
2595 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
2596 | return -ENOMEM; | |
2597 | } | |
2598 | ||
7d227cd2 SS |
2599 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
2600 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
2601 | ||
0c54b85f | 2602 | cur_mss = tcp_current_mss(sk); |
7d227cd2 | 2603 | |
1da177e4 LT |
2604 | /* If receiver has shrunk his window, and skb is out of |
2605 | * new window, do not retransmit it. The exception is the | |
2606 | * case, when window is shrunk to zero. In this case | |
2607 | * our retransmit serves as a zero window probe. | |
2608 | */ | |
9d4fb27d JP |
2609 | if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && |
2610 | TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1da177e4 LT |
2611 | return -EAGAIN; |
2612 | ||
2613 | if (skb->len > cur_mss) { | |
6cc55e09 | 2614 | if (tcp_fragment(sk, skb, cur_mss, cur_mss, GFP_ATOMIC)) |
1da177e4 | 2615 | return -ENOMEM; /* We'll try again later. */ |
02276f3c | 2616 | } else { |
9eb9362e IJ |
2617 | int oldpcount = tcp_skb_pcount(skb); |
2618 | ||
2619 | if (unlikely(oldpcount > 1)) { | |
c52e2421 ED |
2620 | if (skb_unclone(skb, GFP_ATOMIC)) |
2621 | return -ENOMEM; | |
5bbb432c | 2622 | tcp_init_tso_segs(skb, cur_mss); |
9eb9362e IJ |
2623 | tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); |
2624 | } | |
1da177e4 LT |
2625 | } |
2626 | ||
49213555 DB |
2627 | /* RFC3168, section 6.1.1.1. ECN fallback */ |
2628 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) | |
2629 | tcp_ecn_clear_syn(sk, skb); | |
2630 | ||
4a17fc3a | 2631 | tcp_retrans_try_collapse(sk, skb, cur_mss); |
1da177e4 | 2632 | |
1da177e4 LT |
2633 | /* Make a copy, if the first transmission SKB clone we made |
2634 | * is still in somebody's hands, else make a clone. | |
2635 | */ | |
1da177e4 | 2636 | |
50bceae9 TG |
2637 | /* make sure skb->data is aligned on arches that require it |
2638 | * and check if ack-trimming & collapsing extended the headroom | |
2639 | * beyond what csum_start can cover. | |
2640 | */ | |
2641 | if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || | |
2642 | skb_headroom(skb) >= 0xFFFF)) { | |
117632e6 ED |
2643 | struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, |
2644 | GFP_ATOMIC); | |
c84a5711 YC |
2645 | err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : |
2646 | -ENOBUFS; | |
117632e6 | 2647 | } else { |
c84a5711 | 2648 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
117632e6 | 2649 | } |
c84a5711 | 2650 | |
fc9f3501 | 2651 | if (likely(!err)) { |
c84a5711 | 2652 | TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; |
fc9f3501 ED |
2653 | /* Update global TCP statistics. */ |
2654 | TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); | |
2655 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) | |
2656 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
2657 | tp->total_retrans++; | |
2658 | } | |
c84a5711 | 2659 | return err; |
93b174ad YC |
2660 | } |
2661 | ||
2662 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) | |
2663 | { | |
2664 | struct tcp_sock *tp = tcp_sk(sk); | |
2665 | int err = __tcp_retransmit_skb(sk, skb); | |
1da177e4 LT |
2666 | |
2667 | if (err == 0) { | |
1da177e4 | 2668 | #if FASTRETRANS_DEBUG > 0 |
056834d9 | 2669 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
e87cc472 | 2670 | net_dbg_ratelimited("retrans_out leaked\n"); |
1da177e4 LT |
2671 | } |
2672 | #endif | |
2673 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; | |
2674 | tp->retrans_out += tcp_skb_pcount(skb); | |
2675 | ||
2676 | /* Save stamp of the first retransmit. */ | |
2677 | if (!tp->retrans_stamp) | |
7faee5c0 | 2678 | tp->retrans_stamp = tcp_skb_timestamp(skb); |
1da177e4 | 2679 | |
1f3279ae | 2680 | } else if (err != -EBUSY) { |
24ab6bec | 2681 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); |
1da177e4 | 2682 | } |
6e08d5e3 YC |
2683 | |
2684 | if (tp->undo_retrans < 0) | |
2685 | tp->undo_retrans = 0; | |
2686 | tp->undo_retrans += tcp_skb_pcount(skb); | |
1da177e4 LT |
2687 | return err; |
2688 | } | |
2689 | ||
67edfef7 AK |
2690 | /* Check if we forward retransmits are possible in the current |
2691 | * window/congestion state. | |
2692 | */ | |
a2a385d6 | 2693 | static bool tcp_can_forward_retransmit(struct sock *sk) |
b5afe7bc IJ |
2694 | { |
2695 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
cf533ea5 | 2696 | const struct tcp_sock *tp = tcp_sk(sk); |
b5afe7bc IJ |
2697 | |
2698 | /* Forward retransmissions are possible only during Recovery. */ | |
2699 | if (icsk->icsk_ca_state != TCP_CA_Recovery) | |
a2a385d6 | 2700 | return false; |
b5afe7bc IJ |
2701 | |
2702 | /* No forward retransmissions in Reno are possible. */ | |
2703 | if (tcp_is_reno(tp)) | |
a2a385d6 | 2704 | return false; |
b5afe7bc IJ |
2705 | |
2706 | /* Yeah, we have to make difficult choice between forward transmission | |
2707 | * and retransmission... Both ways have their merits... | |
2708 | * | |
2709 | * For now we do not retransmit anything, while we have some new | |
2710 | * segments to send. In the other cases, follow rule 3 for | |
2711 | * NextSeg() specified in RFC3517. | |
2712 | */ | |
2713 | ||
2714 | if (tcp_may_send_now(sk)) | |
a2a385d6 | 2715 | return false; |
b5afe7bc | 2716 | |
a2a385d6 | 2717 | return true; |
b5afe7bc IJ |
2718 | } |
2719 | ||
1da177e4 LT |
2720 | /* This gets called after a retransmit timeout, and the initially |
2721 | * retransmitted data is acknowledged. It tries to continue | |
2722 | * resending the rest of the retransmit queue, until either | |
2723 | * we've sent it all or the congestion window limit is reached. | |
2724 | * If doing SACK, the first ACK which comes back for a timeout | |
2725 | * based retransmit packet might feed us FACK information again. | |
2726 | * If so, we use it to avoid unnecessarily retransmissions. | |
2727 | */ | |
2728 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
2729 | { | |
6687e988 | 2730 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2731 | struct tcp_sock *tp = tcp_sk(sk); |
2732 | struct sk_buff *skb; | |
0e1c54c2 | 2733 | struct sk_buff *hole = NULL; |
618d9f25 | 2734 | u32 last_lost; |
61eb55f4 | 2735 | int mib_idx; |
0e1c54c2 | 2736 | int fwd_rexmitting = 0; |
6a438bbe | 2737 | |
45e77d31 IJ |
2738 | if (!tp->packets_out) |
2739 | return; | |
2740 | ||
08ebd172 IJ |
2741 | if (!tp->lost_out) |
2742 | tp->retransmit_high = tp->snd_una; | |
2743 | ||
618d9f25 | 2744 | if (tp->retransmit_skb_hint) { |
6a438bbe | 2745 | skb = tp->retransmit_skb_hint; |
618d9f25 IJ |
2746 | last_lost = TCP_SKB_CB(skb)->end_seq; |
2747 | if (after(last_lost, tp->retransmit_high)) | |
2748 | last_lost = tp->retransmit_high; | |
2749 | } else { | |
fe067e8a | 2750 | skb = tcp_write_queue_head(sk); |
618d9f25 IJ |
2751 | last_lost = tp->snd_una; |
2752 | } | |
1da177e4 | 2753 | |
08ebd172 IJ |
2754 | tcp_for_write_queue_from(skb, sk) { |
2755 | __u8 sacked = TCP_SKB_CB(skb)->sacked; | |
1da177e4 | 2756 | |
08ebd172 IJ |
2757 | if (skb == tcp_send_head(sk)) |
2758 | break; | |
2759 | /* we could do better than to assign each time */ | |
51456b29 | 2760 | if (!hole) |
0e1c54c2 | 2761 | tp->retransmit_skb_hint = skb; |
08ebd172 IJ |
2762 | |
2763 | /* Assume this retransmit will generate | |
2764 | * only one packet for congestion window | |
2765 | * calculation purposes. This works because | |
2766 | * tcp_retransmit_skb() will chop up the | |
2767 | * packet to be MSS sized and all the | |
2768 | * packet counting works out. | |
2769 | */ | |
2770 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
2771 | return; | |
1da177e4 | 2772 | |
0e1c54c2 IJ |
2773 | if (fwd_rexmitting) { |
2774 | begin_fwd: | |
2775 | if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) | |
2776 | break; | |
2777 | mib_idx = LINUX_MIB_TCPFORWARDRETRANS; | |
6a438bbe | 2778 | |
0e1c54c2 | 2779 | } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { |
618d9f25 | 2780 | tp->retransmit_high = last_lost; |
0e1c54c2 IJ |
2781 | if (!tcp_can_forward_retransmit(sk)) |
2782 | break; | |
2783 | /* Backtrack if necessary to non-L'ed skb */ | |
00db4124 | 2784 | if (hole) { |
0e1c54c2 IJ |
2785 | skb = hole; |
2786 | hole = NULL; | |
2787 | } | |
2788 | fwd_rexmitting = 1; | |
2789 | goto begin_fwd; | |
1da177e4 | 2790 | |
0e1c54c2 | 2791 | } else if (!(sacked & TCPCB_LOST)) { |
51456b29 | 2792 | if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
0e1c54c2 IJ |
2793 | hole = skb; |
2794 | continue; | |
1da177e4 | 2795 | |
0e1c54c2 | 2796 | } else { |
618d9f25 | 2797 | last_lost = TCP_SKB_CB(skb)->end_seq; |
0e1c54c2 IJ |
2798 | if (icsk->icsk_ca_state != TCP_CA_Loss) |
2799 | mib_idx = LINUX_MIB_TCPFASTRETRANS; | |
2800 | else | |
2801 | mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; | |
2802 | } | |
1da177e4 | 2803 | |
0e1c54c2 | 2804 | if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
1da177e4 LT |
2805 | continue; |
2806 | ||
24ab6bec | 2807 | if (tcp_retransmit_skb(sk, skb)) |
0e1c54c2 | 2808 | return; |
24ab6bec | 2809 | |
0e1c54c2 | 2810 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 | 2811 | |
684bad11 | 2812 | if (tcp_in_cwnd_reduction(sk)) |
a262f0cd ND |
2813 | tp->prr_out += tcp_skb_pcount(skb); |
2814 | ||
fe067e8a | 2815 | if (skb == tcp_write_queue_head(sk)) |
3f421baa ACM |
2816 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
2817 | inet_csk(sk)->icsk_rto, | |
2818 | TCP_RTO_MAX); | |
1da177e4 LT |
2819 | } |
2820 | } | |
2821 | ||
d83769a5 ED |
2822 | /* We allow to exceed memory limits for FIN packets to expedite |
2823 | * connection tear down and (memory) recovery. | |
845704a5 ED |
2824 | * Otherwise tcp_send_fin() could be tempted to either delay FIN |
2825 | * or even be forced to close flow without any FIN. | |
a6c5ea4c ED |
2826 | * In general, we want to allow one skb per socket to avoid hangs |
2827 | * with edge trigger epoll() | |
d83769a5 | 2828 | */ |
a6c5ea4c | 2829 | void sk_forced_mem_schedule(struct sock *sk, int size) |
d83769a5 | 2830 | { |
e805605c | 2831 | int amt; |
d83769a5 ED |
2832 | |
2833 | if (size <= sk->sk_forward_alloc) | |
2834 | return; | |
2835 | amt = sk_mem_pages(size); | |
2836 | sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; | |
e805605c JW |
2837 | sk_memory_allocated_add(sk, amt); |
2838 | ||
baac50bb JW |
2839 | if (mem_cgroup_sockets_enabled && sk->sk_memcg) |
2840 | mem_cgroup_charge_skmem(sk->sk_memcg, amt); | |
d83769a5 ED |
2841 | } |
2842 | ||
845704a5 ED |
2843 | /* Send a FIN. The caller locks the socket for us. |
2844 | * We should try to send a FIN packet really hard, but eventually give up. | |
1da177e4 LT |
2845 | */ |
2846 | void tcp_send_fin(struct sock *sk) | |
2847 | { | |
845704a5 | 2848 | struct sk_buff *skb, *tskb = tcp_write_queue_tail(sk); |
e905a9ed | 2849 | struct tcp_sock *tp = tcp_sk(sk); |
e905a9ed | 2850 | |
845704a5 ED |
2851 | /* Optimization, tack on the FIN if we have one skb in write queue and |
2852 | * this skb was not yet sent, or we are under memory pressure. | |
2853 | * Note: in the latter case, FIN packet will be sent after a timeout, | |
2854 | * as TCP stack thinks it has already been transmitted. | |
1da177e4 | 2855 | */ |
b8da51eb | 2856 | if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) { |
845704a5 ED |
2857 | coalesce: |
2858 | TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; | |
2859 | TCP_SKB_CB(tskb)->end_seq++; | |
1da177e4 | 2860 | tp->write_seq++; |
845704a5 ED |
2861 | if (!tcp_send_head(sk)) { |
2862 | /* This means tskb was already sent. | |
2863 | * Pretend we included the FIN on previous transmit. | |
2864 | * We need to set tp->snd_nxt to the value it would have | |
2865 | * if FIN had been sent. This is because retransmit path | |
2866 | * does not change tp->snd_nxt. | |
2867 | */ | |
2868 | tp->snd_nxt++; | |
2869 | return; | |
2870 | } | |
1da177e4 | 2871 | } else { |
845704a5 ED |
2872 | skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); |
2873 | if (unlikely(!skb)) { | |
2874 | if (tskb) | |
2875 | goto coalesce; | |
2876 | return; | |
1da177e4 | 2877 | } |
d83769a5 | 2878 | skb_reserve(skb, MAX_TCP_HEADER); |
a6c5ea4c | 2879 | sk_forced_mem_schedule(sk, skb->truesize); |
1da177e4 | 2880 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
e870a8ef | 2881 | tcp_init_nondata_skb(skb, tp->write_seq, |
a3433f35 | 2882 | TCPHDR_ACK | TCPHDR_FIN); |
1da177e4 LT |
2883 | tcp_queue_skb(sk, skb); |
2884 | } | |
845704a5 | 2885 | __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); |
1da177e4 LT |
2886 | } |
2887 | ||
2888 | /* We get here when a process closes a file descriptor (either due to | |
2889 | * an explicit close() or as a byproduct of exit()'ing) and there | |
2890 | * was unread data in the receive queue. This behavior is recommended | |
65bb723c | 2891 | * by RFC 2525, section 2.17. -DaveM |
1da177e4 | 2892 | */ |
dd0fc66f | 2893 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 | 2894 | { |
1da177e4 LT |
2895 | struct sk_buff *skb; |
2896 | ||
2897 | /* NOTE: No TCP options attached and we never retransmit this. */ | |
2898 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
2899 | if (!skb) { | |
4e673444 | 2900 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
1da177e4 LT |
2901 | return; |
2902 | } | |
2903 | ||
2904 | /* Reserve space for headers and prepare control bits. */ | |
2905 | skb_reserve(skb, MAX_TCP_HEADER); | |
e870a8ef | 2906 | tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
a3433f35 | 2907 | TCPHDR_ACK | TCPHDR_RST); |
675ee231 | 2908 | skb_mstamp_get(&skb->skb_mstamp); |
1da177e4 | 2909 | /* Send it off. */ |
dfb4b9dc | 2910 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
4e673444 | 2911 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
26af65cb | 2912 | |
81cc8a75 | 2913 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
1da177e4 LT |
2914 | } |
2915 | ||
67edfef7 AK |
2916 | /* Send a crossed SYN-ACK during socket establishment. |
2917 | * WARNING: This routine must only be called when we have already sent | |
1da177e4 LT |
2918 | * a SYN packet that crossed the incoming SYN that caused this routine |
2919 | * to get called. If this assumption fails then the initial rcv_wnd | |
2920 | * and rcv_wscale values will not be correct. | |
2921 | */ | |
2922 | int tcp_send_synack(struct sock *sk) | |
2923 | { | |
056834d9 | 2924 | struct sk_buff *skb; |
1da177e4 | 2925 | |
fe067e8a | 2926 | skb = tcp_write_queue_head(sk); |
51456b29 | 2927 | if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
91df42be | 2928 | pr_debug("%s: wrong queue state\n", __func__); |
1da177e4 LT |
2929 | return -EFAULT; |
2930 | } | |
4de075e0 | 2931 | if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
1da177e4 LT |
2932 | if (skb_cloned(skb)) { |
2933 | struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); | |
51456b29 | 2934 | if (!nskb) |
1da177e4 | 2935 | return -ENOMEM; |
fe067e8a | 2936 | tcp_unlink_write_queue(skb, sk); |
f4a775d1 | 2937 | __skb_header_release(nskb); |
fe067e8a | 2938 | __tcp_add_write_queue_head(sk, nskb); |
3ab224be HA |
2939 | sk_wmem_free_skb(sk, skb); |
2940 | sk->sk_wmem_queued += nskb->truesize; | |
2941 | sk_mem_charge(sk, nskb->truesize); | |
1da177e4 LT |
2942 | skb = nskb; |
2943 | } | |
2944 | ||
4de075e0 | 2945 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
735d3831 | 2946 | tcp_ecn_send_synack(sk, skb); |
1da177e4 | 2947 | } |
dfb4b9dc | 2948 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2949 | } |
2950 | ||
4aea39c1 ED |
2951 | /** |
2952 | * tcp_make_synack - Prepare a SYN-ACK. | |
2953 | * sk: listener socket | |
2954 | * dst: dst entry attached to the SYNACK | |
2955 | * req: request_sock pointer | |
4aea39c1 ED |
2956 | * |
2957 | * Allocate one skb and build a SYNACK packet. | |
2958 | * @dst is consumed : Caller should not use it again. | |
2959 | */ | |
5d062de7 | 2960 | struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, |
e6b4d113 | 2961 | struct request_sock *req, |
ca6fb065 ED |
2962 | struct tcp_fastopen_cookie *foc, |
2963 | bool attach_req) | |
1da177e4 | 2964 | { |
2e6599cb | 2965 | struct inet_request_sock *ireq = inet_rsk(req); |
5d062de7 | 2966 | const struct tcp_sock *tp = tcp_sk(sk); |
80f03e27 | 2967 | struct tcp_md5sig_key *md5 = NULL; |
5d062de7 ED |
2968 | struct tcp_out_options opts; |
2969 | struct sk_buff *skb; | |
bd0388ae | 2970 | int tcp_header_size; |
5d062de7 ED |
2971 | struct tcphdr *th; |
2972 | u16 user_mss; | |
f5fff5dc | 2973 | int mss; |
1da177e4 | 2974 | |
ca6fb065 | 2975 | skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); |
4aea39c1 ED |
2976 | if (unlikely(!skb)) { |
2977 | dst_release(dst); | |
1da177e4 | 2978 | return NULL; |
4aea39c1 | 2979 | } |
1da177e4 LT |
2980 | /* Reserve space for headers. */ |
2981 | skb_reserve(skb, MAX_TCP_HEADER); | |
2982 | ||
ca6fb065 | 2983 | if (attach_req) { |
9e17f8a4 | 2984 | skb_set_owner_w(skb, req_to_sk(req)); |
ca6fb065 ED |
2985 | } else { |
2986 | /* sk is a const pointer, because we want to express multiple | |
2987 | * cpu might call us concurrently. | |
2988 | * sk->sk_wmem_alloc in an atomic, we can promote to rw. | |
2989 | */ | |
2990 | skb_set_owner_w(skb, (struct sock *)sk); | |
2991 | } | |
4aea39c1 | 2992 | skb_dst_set(skb, dst); |
1da177e4 | 2993 | |
0dbaee3b | 2994 | mss = dst_metric_advmss(dst); |
5d062de7 ED |
2995 | user_mss = READ_ONCE(tp->rx_opt.user_mss); |
2996 | if (user_mss && user_mss < mss) | |
2997 | mss = user_mss; | |
f5fff5dc | 2998 | |
33ad798c | 2999 | memset(&opts, 0, sizeof(opts)); |
8b5f12d0 FW |
3000 | #ifdef CONFIG_SYN_COOKIES |
3001 | if (unlikely(req->cookie_ts)) | |
7faee5c0 | 3002 | skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); |
8b5f12d0 FW |
3003 | else |
3004 | #endif | |
7faee5c0 | 3005 | skb_mstamp_get(&skb->skb_mstamp); |
80f03e27 ED |
3006 | |
3007 | #ifdef CONFIG_TCP_MD5SIG | |
3008 | rcu_read_lock(); | |
fd3a154a | 3009 | md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); |
80f03e27 | 3010 | #endif |
58d607d3 | 3011 | skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); |
37bfbdda ED |
3012 | tcp_header_size = tcp_synack_options(req, mss, skb, &opts, md5, foc) + |
3013 | sizeof(*th); | |
cfb6eeb4 | 3014 | |
aa8223c7 ACM |
3015 | skb_push(skb, tcp_header_size); |
3016 | skb_reset_transport_header(skb); | |
1da177e4 | 3017 | |
aa8223c7 | 3018 | th = tcp_hdr(skb); |
1da177e4 LT |
3019 | memset(th, 0, sizeof(struct tcphdr)); |
3020 | th->syn = 1; | |
3021 | th->ack = 1; | |
6ac705b1 | 3022 | tcp_ecn_make_synack(req, th); |
b44084c2 | 3023 | th->source = htons(ireq->ir_num); |
634fb979 | 3024 | th->dest = ireq->ir_rmt_port; |
e870a8ef IJ |
3025 | /* Setting of flags are superfluous here for callers (and ECE is |
3026 | * not even correctly set) | |
3027 | */ | |
3028 | tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, | |
a3433f35 | 3029 | TCPHDR_SYN | TCPHDR_ACK); |
4957faad | 3030 | |
1da177e4 | 3031 | th->seq = htonl(TCP_SKB_CB(skb)->seq); |
8336886f JC |
3032 | /* XXX data is queued and acked as is. No buffer/window check */ |
3033 | th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); | |
1da177e4 LT |
3034 | |
3035 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
ed53d0ab | 3036 | th->window = htons(min(req->rsk_rcv_wnd, 65535U)); |
5d062de7 | 3037 | tcp_options_write((__be32 *)(th + 1), NULL, &opts); |
1da177e4 | 3038 | th->doff = (tcp_header_size >> 2); |
a0b8486c | 3039 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_OUTSEGS); |
cfb6eeb4 YH |
3040 | |
3041 | #ifdef CONFIG_TCP_MD5SIG | |
3042 | /* Okay, we have all we need - do the md5 hash if needed */ | |
80f03e27 | 3043 | if (md5) |
bd0388ae | 3044 | tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
39f8e58e | 3045 | md5, req_to_sk(req), skb); |
80f03e27 | 3046 | rcu_read_unlock(); |
cfb6eeb4 YH |
3047 | #endif |
3048 | ||
b50edd78 ED |
3049 | /* Do not fool tcpdump (if any), clean our debris */ |
3050 | skb->tstamp.tv64 = 0; | |
1da177e4 LT |
3051 | return skb; |
3052 | } | |
4bc2f18b | 3053 | EXPORT_SYMBOL(tcp_make_synack); |
1da177e4 | 3054 | |
81164413 DB |
3055 | static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) |
3056 | { | |
3057 | struct inet_connection_sock *icsk = inet_csk(sk); | |
3058 | const struct tcp_congestion_ops *ca; | |
3059 | u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); | |
3060 | ||
3061 | if (ca_key == TCP_CA_UNSPEC) | |
3062 | return; | |
3063 | ||
3064 | rcu_read_lock(); | |
3065 | ca = tcp_ca_find_key(ca_key); | |
3066 | if (likely(ca && try_module_get(ca->owner))) { | |
3067 | module_put(icsk->icsk_ca_ops->owner); | |
3068 | icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); | |
3069 | icsk->icsk_ca_ops = ca; | |
3070 | } | |
3071 | rcu_read_unlock(); | |
3072 | } | |
3073 | ||
67edfef7 | 3074 | /* Do all connect socket setups that can be done AF independent. */ |
f7e56a76 | 3075 | static void tcp_connect_init(struct sock *sk) |
1da177e4 | 3076 | { |
cf533ea5 | 3077 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
3078 | struct tcp_sock *tp = tcp_sk(sk); |
3079 | __u8 rcv_wscale; | |
3080 | ||
3081 | /* We'll fix this up when we get a response from the other end. | |
3082 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
3083 | */ | |
3084 | tp->tcp_header_len = sizeof(struct tcphdr) + | |
bb5b7c11 | 3085 | (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); |
1da177e4 | 3086 | |
cfb6eeb4 | 3087 | #ifdef CONFIG_TCP_MD5SIG |
00db4124 | 3088 | if (tp->af_specific->md5_lookup(sk, sk)) |
cfb6eeb4 YH |
3089 | tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; |
3090 | #endif | |
3091 | ||
1da177e4 LT |
3092 | /* If user gave his TCP_MAXSEG, record it to clamp */ |
3093 | if (tp->rx_opt.user_mss) | |
3094 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
3095 | tp->max_window = 0; | |
5d424d5a | 3096 | tcp_mtup_init(sk); |
1da177e4 LT |
3097 | tcp_sync_mss(sk, dst_mtu(dst)); |
3098 | ||
81164413 DB |
3099 | tcp_ca_dst_init(sk, dst); |
3100 | ||
1da177e4 LT |
3101 | if (!tp->window_clamp) |
3102 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
0dbaee3b | 3103 | tp->advmss = dst_metric_advmss(dst); |
f5fff5dc TQ |
3104 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) |
3105 | tp->advmss = tp->rx_opt.user_mss; | |
3106 | ||
1da177e4 | 3107 | tcp_initialize_rcv_mss(sk); |
1da177e4 | 3108 | |
e88c64f0 HPP |
3109 | /* limit the window selection if the user enforce a smaller rx buffer */ |
3110 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
3111 | (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) | |
3112 | tp->window_clamp = tcp_full_space(sk); | |
3113 | ||
1da177e4 LT |
3114 | tcp_select_initial_window(tcp_full_space(sk), |
3115 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), | |
3116 | &tp->rcv_wnd, | |
3117 | &tp->window_clamp, | |
bb5b7c11 | 3118 | sysctl_tcp_window_scaling, |
31d12926 | 3119 | &rcv_wscale, |
3120 | dst_metric(dst, RTAX_INITRWND)); | |
1da177e4 LT |
3121 | |
3122 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
3123 | tp->rcv_ssthresh = tp->rcv_wnd; | |
3124 | ||
3125 | sk->sk_err = 0; | |
3126 | sock_reset_flag(sk, SOCK_DONE); | |
3127 | tp->snd_wnd = 0; | |
ee7537b6 | 3128 | tcp_init_wl(tp, 0); |
1da177e4 LT |
3129 | tp->snd_una = tp->write_seq; |
3130 | tp->snd_sml = tp->write_seq; | |
33f5f57e | 3131 | tp->snd_up = tp->write_seq; |
370816ae | 3132 | tp->snd_nxt = tp->write_seq; |
ee995283 PE |
3133 | |
3134 | if (likely(!tp->repair)) | |
3135 | tp->rcv_nxt = 0; | |
c7781a6e AV |
3136 | else |
3137 | tp->rcv_tstamp = tcp_time_stamp; | |
ee995283 PE |
3138 | tp->rcv_wup = tp->rcv_nxt; |
3139 | tp->copied_seq = tp->rcv_nxt; | |
1da177e4 | 3140 | |
463c84b9 ACM |
3141 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
3142 | inet_csk(sk)->icsk_retransmits = 0; | |
1da177e4 LT |
3143 | tcp_clear_retrans(tp); |
3144 | } | |
3145 | ||
783237e8 YC |
3146 | static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
3147 | { | |
3148 | struct tcp_sock *tp = tcp_sk(sk); | |
3149 | struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); | |
3150 | ||
3151 | tcb->end_seq += skb->len; | |
f4a775d1 | 3152 | __skb_header_release(skb); |
783237e8 YC |
3153 | __tcp_add_write_queue_tail(sk, skb); |
3154 | sk->sk_wmem_queued += skb->truesize; | |
3155 | sk_mem_charge(sk, skb->truesize); | |
3156 | tp->write_seq = tcb->end_seq; | |
3157 | tp->packets_out += tcp_skb_pcount(skb); | |
3158 | } | |
3159 | ||
3160 | /* Build and send a SYN with data and (cached) Fast Open cookie. However, | |
3161 | * queue a data-only packet after the regular SYN, such that regular SYNs | |
3162 | * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges | |
3163 | * only the SYN sequence, the data are retransmitted in the first ACK. | |
3164 | * If cookie is not cached or other error occurs, falls back to send a | |
3165 | * regular SYN with Fast Open cookie request option. | |
3166 | */ | |
3167 | static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) | |
3168 | { | |
3169 | struct tcp_sock *tp = tcp_sk(sk); | |
3170 | struct tcp_fastopen_request *fo = tp->fastopen_req; | |
07e100f9 | 3171 | int syn_loss = 0, space, err = 0; |
aab48743 | 3172 | unsigned long last_syn_loss = 0; |
355a901e | 3173 | struct sk_buff *syn_data; |
aab48743 | 3174 | |
67da22d2 | 3175 | tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
aab48743 YC |
3176 | tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, |
3177 | &syn_loss, &last_syn_loss); | |
3178 | /* Recurring FO SYN losses: revert to regular handshake temporarily */ | |
3179 | if (syn_loss > 1 && | |
3180 | time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { | |
3181 | fo->cookie.len = -1; | |
3182 | goto fallback; | |
3183 | } | |
783237e8 | 3184 | |
67da22d2 YC |
3185 | if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) |
3186 | fo->cookie.len = -1; | |
3187 | else if (fo->cookie.len <= 0) | |
783237e8 YC |
3188 | goto fallback; |
3189 | ||
3190 | /* MSS for SYN-data is based on cached MSS and bounded by PMTU and | |
3191 | * user-MSS. Reserve maximum option space for middleboxes that add | |
3192 | * private TCP options. The cost is reduced data space in SYN :( | |
3193 | */ | |
3194 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) | |
3195 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
1b63edd6 | 3196 | space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - |
783237e8 YC |
3197 | MAX_TCP_OPTION_SPACE; |
3198 | ||
f5ddcbbb ED |
3199 | space = min_t(size_t, space, fo->size); |
3200 | ||
3201 | /* limit to order-0 allocations */ | |
3202 | space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); | |
3203 | ||
eb934478 | 3204 | syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); |
355a901e | 3205 | if (!syn_data) |
783237e8 | 3206 | goto fallback; |
355a901e ED |
3207 | syn_data->ip_summed = CHECKSUM_PARTIAL; |
3208 | memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); | |
07e100f9 ED |
3209 | if (space) { |
3210 | int copied = copy_from_iter(skb_put(syn_data, space), space, | |
3211 | &fo->data->msg_iter); | |
3212 | if (unlikely(!copied)) { | |
3213 | kfree_skb(syn_data); | |
3214 | goto fallback; | |
3215 | } | |
3216 | if (copied != space) { | |
3217 | skb_trim(syn_data, copied); | |
3218 | space = copied; | |
3219 | } | |
57be5bda | 3220 | } |
355a901e ED |
3221 | /* No more data pending in inet_wait_for_connect() */ |
3222 | if (space == fo->size) | |
3223 | fo->data = NULL; | |
3224 | fo->copied = space; | |
783237e8 | 3225 | |
355a901e | 3226 | tcp_connect_queue_skb(sk, syn_data); |
783237e8 | 3227 | |
355a901e | 3228 | err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); |
783237e8 | 3229 | |
355a901e | 3230 | syn->skb_mstamp = syn_data->skb_mstamp; |
431a9124 | 3231 | |
355a901e ED |
3232 | /* Now full SYN+DATA was cloned and sent (or not), |
3233 | * remove the SYN from the original skb (syn_data) | |
3234 | * we keep in write queue in case of a retransmit, as we | |
3235 | * also have the SYN packet (with no data) in the same queue. | |
3236 | */ | |
3237 | TCP_SKB_CB(syn_data)->seq++; | |
3238 | TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; | |
3239 | if (!err) { | |
67da22d2 | 3240 | tp->syn_data = (fo->copied > 0); |
f19c29e3 | 3241 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); |
783237e8 YC |
3242 | goto done; |
3243 | } | |
783237e8 YC |
3244 | |
3245 | fallback: | |
3246 | /* Send a regular SYN with Fast Open cookie request option */ | |
3247 | if (fo->cookie.len > 0) | |
3248 | fo->cookie.len = 0; | |
3249 | err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); | |
3250 | if (err) | |
3251 | tp->syn_fastopen = 0; | |
783237e8 YC |
3252 | done: |
3253 | fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ | |
3254 | return err; | |
3255 | } | |
3256 | ||
67edfef7 | 3257 | /* Build a SYN and send it off. */ |
1da177e4 LT |
3258 | int tcp_connect(struct sock *sk) |
3259 | { | |
3260 | struct tcp_sock *tp = tcp_sk(sk); | |
3261 | struct sk_buff *buff; | |
ee586811 | 3262 | int err; |
1da177e4 LT |
3263 | |
3264 | tcp_connect_init(sk); | |
3265 | ||
2b916477 AV |
3266 | if (unlikely(tp->repair)) { |
3267 | tcp_finish_connect(sk, NULL); | |
3268 | return 0; | |
3269 | } | |
3270 | ||
eb934478 | 3271 | buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); |
355a901e | 3272 | if (unlikely(!buff)) |
1da177e4 LT |
3273 | return -ENOBUFS; |
3274 | ||
a3433f35 | 3275 | tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
7faee5c0 | 3276 | tp->retrans_stamp = tcp_time_stamp; |
783237e8 | 3277 | tcp_connect_queue_skb(sk, buff); |
735d3831 | 3278 | tcp_ecn_send_syn(sk, buff); |
1da177e4 | 3279 | |
783237e8 YC |
3280 | /* Send off SYN; include data in Fast Open. */ |
3281 | err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : | |
3282 | tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); | |
ee586811 EP |
3283 | if (err == -ECONNREFUSED) |
3284 | return err; | |
bd37a088 WY |
3285 | |
3286 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
3287 | * in order to make this packet get counted in tcpOutSegs. | |
3288 | */ | |
3289 | tp->snd_nxt = tp->write_seq; | |
3290 | tp->pushed_seq = tp->write_seq; | |
81cc8a75 | 3291 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
1da177e4 LT |
3292 | |
3293 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
3294 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3295 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
3296 | return 0; |
3297 | } | |
4bc2f18b | 3298 | EXPORT_SYMBOL(tcp_connect); |
1da177e4 LT |
3299 | |
3300 | /* Send out a delayed ack, the caller does the policy checking | |
3301 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
3302 | * for details. | |
3303 | */ | |
3304 | void tcp_send_delayed_ack(struct sock *sk) | |
3305 | { | |
463c84b9 ACM |
3306 | struct inet_connection_sock *icsk = inet_csk(sk); |
3307 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
3308 | unsigned long timeout; |
3309 | ||
9890092e FW |
3310 | tcp_ca_event(sk, CA_EVENT_DELAYED_ACK); |
3311 | ||
1da177e4 | 3312 | if (ato > TCP_DELACK_MIN) { |
463c84b9 | 3313 | const struct tcp_sock *tp = tcp_sk(sk); |
056834d9 | 3314 | int max_ato = HZ / 2; |
1da177e4 | 3315 | |
056834d9 IJ |
3316 | if (icsk->icsk_ack.pingpong || |
3317 | (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) | |
1da177e4 LT |
3318 | max_ato = TCP_DELACK_MAX; |
3319 | ||
3320 | /* Slow path, intersegment interval is "high". */ | |
3321 | ||
3322 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 3323 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
3324 | * directly. |
3325 | */ | |
740b0f18 ED |
3326 | if (tp->srtt_us) { |
3327 | int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), | |
3328 | TCP_DELACK_MIN); | |
1da177e4 LT |
3329 | |
3330 | if (rtt < max_ato) | |
3331 | max_ato = rtt; | |
3332 | } | |
3333 | ||
3334 | ato = min(ato, max_ato); | |
3335 | } | |
3336 | ||
3337 | /* Stay within the limit we were given */ | |
3338 | timeout = jiffies + ato; | |
3339 | ||
3340 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 3341 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
3342 | /* If delack timer was blocked or is about to expire, |
3343 | * send ACK now. | |
3344 | */ | |
463c84b9 ACM |
3345 | if (icsk->icsk_ack.blocked || |
3346 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
3347 | tcp_send_ack(sk); |
3348 | return; | |
3349 | } | |
3350 | ||
463c84b9 ACM |
3351 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
3352 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 3353 | } |
463c84b9 ACM |
3354 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
3355 | icsk->icsk_ack.timeout = timeout; | |
3356 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
3357 | } |
3358 | ||
3359 | /* This routine sends an ack and also updates the window. */ | |
3360 | void tcp_send_ack(struct sock *sk) | |
3361 | { | |
058dc334 | 3362 | struct sk_buff *buff; |
1da177e4 | 3363 | |
058dc334 IJ |
3364 | /* If we have been reset, we may not send again. */ |
3365 | if (sk->sk_state == TCP_CLOSE) | |
3366 | return; | |
1da177e4 | 3367 | |
9890092e FW |
3368 | tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK); |
3369 | ||
058dc334 IJ |
3370 | /* We are not putting this on the write queue, so |
3371 | * tcp_transmit_skb() will set the ownership to this | |
3372 | * sock. | |
3373 | */ | |
7450aaf6 ED |
3374 | buff = alloc_skb(MAX_TCP_HEADER, |
3375 | sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); | |
3376 | if (unlikely(!buff)) { | |
058dc334 IJ |
3377 | inet_csk_schedule_ack(sk); |
3378 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3379 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, | |
3380 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
3381 | return; | |
1da177e4 | 3382 | } |
058dc334 IJ |
3383 | |
3384 | /* Reserve space for headers and prepare control bits. */ | |
3385 | skb_reserve(buff, MAX_TCP_HEADER); | |
a3433f35 | 3386 | tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
058dc334 | 3387 | |
98781965 ED |
3388 | /* We do not want pure acks influencing TCP Small Queues or fq/pacing |
3389 | * too much. | |
3390 | * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 | |
3391 | * We also avoid tcp_wfree() overhead (cache line miss accessing | |
3392 | * tp->tsq_flags) by using regular sock_wfree() | |
3393 | */ | |
3394 | skb_set_tcp_pure_ack(buff); | |
3395 | ||
058dc334 | 3396 | /* Send it off, this clears delayed acks for us. */ |
7faee5c0 | 3397 | skb_mstamp_get(&buff->skb_mstamp); |
7450aaf6 | 3398 | tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0); |
1da177e4 | 3399 | } |
e3118e83 | 3400 | EXPORT_SYMBOL_GPL(tcp_send_ack); |
1da177e4 LT |
3401 | |
3402 | /* This routine sends a packet with an out of date sequence | |
3403 | * number. It assumes the other end will try to ack it. | |
3404 | * | |
3405 | * Question: what should we make while urgent mode? | |
3406 | * 4.4BSD forces sending single byte of data. We cannot send | |
3407 | * out of window data, because we have SND.NXT==SND.MAX... | |
3408 | * | |
3409 | * Current solution: to send TWO zero-length segments in urgent mode: | |
3410 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
3411 | * out-of-date with SND.UNA-1 to probe window. | |
3412 | */ | |
e520af48 | 3413 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) |
1da177e4 LT |
3414 | { |
3415 | struct tcp_sock *tp = tcp_sk(sk); | |
3416 | struct sk_buff *skb; | |
3417 | ||
3418 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
7450aaf6 ED |
3419 | skb = alloc_skb(MAX_TCP_HEADER, |
3420 | sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); | |
51456b29 | 3421 | if (!skb) |
1da177e4 LT |
3422 | return -1; |
3423 | ||
3424 | /* Reserve space for headers and set control bits. */ | |
3425 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 LT |
3426 | /* Use a previous sequence. This should cause the other |
3427 | * end to send an ack. Don't queue or clone SKB, just | |
3428 | * send it. | |
3429 | */ | |
a3433f35 | 3430 | tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
7faee5c0 | 3431 | skb_mstamp_get(&skb->skb_mstamp); |
e2e8009f | 3432 | NET_INC_STATS(sock_net(sk), mib); |
7450aaf6 | 3433 | return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); |
1da177e4 LT |
3434 | } |
3435 | ||
ee995283 PE |
3436 | void tcp_send_window_probe(struct sock *sk) |
3437 | { | |
3438 | if (sk->sk_state == TCP_ESTABLISHED) { | |
3439 | tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; | |
e520af48 | 3440 | tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); |
ee995283 PE |
3441 | } |
3442 | } | |
3443 | ||
67edfef7 | 3444 | /* Initiate keepalive or window probe from timer. */ |
e520af48 | 3445 | int tcp_write_wakeup(struct sock *sk, int mib) |
1da177e4 | 3446 | { |
058dc334 IJ |
3447 | struct tcp_sock *tp = tcp_sk(sk); |
3448 | struct sk_buff *skb; | |
1da177e4 | 3449 | |
058dc334 IJ |
3450 | if (sk->sk_state == TCP_CLOSE) |
3451 | return -1; | |
3452 | ||
00db4124 IM |
3453 | skb = tcp_send_head(sk); |
3454 | if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { | |
058dc334 | 3455 | int err; |
0c54b85f | 3456 | unsigned int mss = tcp_current_mss(sk); |
058dc334 IJ |
3457 | unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
3458 | ||
3459 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
3460 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
3461 | ||
3462 | /* We are probing the opening of a window | |
3463 | * but the window size is != 0 | |
3464 | * must have been a result SWS avoidance ( sender ) | |
3465 | */ | |
3466 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
3467 | skb->len > mss) { | |
3468 | seg_size = min(seg_size, mss); | |
4de075e0 | 3469 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
6cc55e09 | 3470 | if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) |
058dc334 IJ |
3471 | return -1; |
3472 | } else if (!tcp_skb_pcount(skb)) | |
5bbb432c | 3473 | tcp_set_skb_tso_segs(skb, mss); |
058dc334 | 3474 | |
4de075e0 | 3475 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3476 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
3477 | if (!err) | |
3478 | tcp_event_new_data_sent(sk, skb); | |
3479 | return err; | |
3480 | } else { | |
33f5f57e | 3481 | if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
e520af48 ED |
3482 | tcp_xmit_probe_skb(sk, 1, mib); |
3483 | return tcp_xmit_probe_skb(sk, 0, mib); | |
1da177e4 | 3484 | } |
1da177e4 LT |
3485 | } |
3486 | ||
3487 | /* A window probe timeout has occurred. If window is not closed send | |
3488 | * a partial packet else a zero probe. | |
3489 | */ | |
3490 | void tcp_send_probe0(struct sock *sk) | |
3491 | { | |
463c84b9 | 3492 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 3493 | struct tcp_sock *tp = tcp_sk(sk); |
c6214a97 | 3494 | struct net *net = sock_net(sk); |
fcdd1cf4 | 3495 | unsigned long probe_max; |
1da177e4 LT |
3496 | int err; |
3497 | ||
e520af48 | 3498 | err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); |
1da177e4 | 3499 | |
fe067e8a | 3500 | if (tp->packets_out || !tcp_send_head(sk)) { |
1da177e4 | 3501 | /* Cancel probe timer, if it is not required. */ |
6687e988 | 3502 | icsk->icsk_probes_out = 0; |
463c84b9 | 3503 | icsk->icsk_backoff = 0; |
1da177e4 LT |
3504 | return; |
3505 | } | |
3506 | ||
3507 | if (err <= 0) { | |
c6214a97 | 3508 | if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) |
463c84b9 | 3509 | icsk->icsk_backoff++; |
6687e988 | 3510 | icsk->icsk_probes_out++; |
fcdd1cf4 | 3511 | probe_max = TCP_RTO_MAX; |
1da177e4 LT |
3512 | } else { |
3513 | /* If packet was not sent due to local congestion, | |
6687e988 | 3514 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
3515 | * Let local senders to fight for local resources. |
3516 | * | |
3517 | * Use accumulated backoff yet. | |
3518 | */ | |
6687e988 ACM |
3519 | if (!icsk->icsk_probes_out) |
3520 | icsk->icsk_probes_out = 1; | |
fcdd1cf4 | 3521 | probe_max = TCP_RESOURCE_PROBE_INTERVAL; |
1da177e4 | 3522 | } |
fcdd1cf4 | 3523 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
21c8fe99 | 3524 | tcp_probe0_when(sk, probe_max), |
fcdd1cf4 | 3525 | TCP_RTO_MAX); |
1da177e4 | 3526 | } |
5db92c99 | 3527 | |
ea3bea3a | 3528 | int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) |
5db92c99 OP |
3529 | { |
3530 | const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; | |
3531 | struct flowi fl; | |
3532 | int res; | |
3533 | ||
58d607d3 | 3534 | tcp_rsk(req)->txhash = net_tx_rndhash(); |
dc6ef6be | 3535 | res = af_ops->send_synack(sk, NULL, &fl, req, NULL, true); |
5db92c99 OP |
3536 | if (!res) { |
3537 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS); | |
3538 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
3539 | } | |
3540 | return res; | |
3541 | } | |
3542 | EXPORT_SYMBOL(tcp_rtx_synack); |