Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Implementation of the Transmission Control Protocol(TCP). | |
7 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
12 | * Florian La Roche, <flla@stud.uni-sb.de> | |
13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
16 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
18 | * Jorge Cwik, <jorge@laser.satlink.net> | |
19 | */ | |
20 | ||
21 | /* | |
22 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
23 | * : Fragmentation on mtu decrease | |
24 | * : Segment collapse on retransmit | |
25 | * : AF independence | |
26 | * | |
27 | * Linus Torvalds : send_delayed_ack | |
28 | * David S. Miller : Charge memory using the right skb | |
29 | * during syn/ack processing. | |
30 | * David S. Miller : Output engine completely rewritten. | |
31 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
32 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
33 | * J Hadi Salim : ECN support | |
34 | * | |
35 | */ | |
36 | ||
91df42be JP |
37 | #define pr_fmt(fmt) "TCP: " fmt |
38 | ||
1da177e4 LT |
39 | #include <net/tcp.h> |
40 | ||
41 | #include <linux/compiler.h> | |
5a0e3ad6 | 42 | #include <linux/gfp.h> |
1da177e4 | 43 | #include <linux/module.h> |
1da177e4 LT |
44 | |
45 | /* People can turn this off for buggy TCP's found in printers etc. */ | |
ab32ea5d | 46 | int sysctl_tcp_retrans_collapse __read_mostly = 1; |
1da177e4 | 47 | |
09cb105e | 48 | /* People can turn this on to work with those rare, broken TCPs that |
15d99e02 RJ |
49 | * interpret the window field as a signed quantity. |
50 | */ | |
ab32ea5d | 51 | int sysctl_tcp_workaround_signed_windows __read_mostly = 0; |
15d99e02 | 52 | |
46d3ceab ED |
53 | /* Default TSQ limit of two TSO segments */ |
54 | int sysctl_tcp_limit_output_bytes __read_mostly = 131072; | |
55 | ||
1da177e4 LT |
56 | /* This limits the percentage of the congestion window which we |
57 | * will allow a single TSO frame to consume. Building TSO frames | |
58 | * which are too large can cause TCP streams to be bursty. | |
59 | */ | |
ab32ea5d | 60 | int sysctl_tcp_tso_win_divisor __read_mostly = 3; |
1da177e4 | 61 | |
ab32ea5d | 62 | int sysctl_tcp_mtu_probing __read_mostly = 0; |
97b1ce25 | 63 | int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS; |
5d424d5a | 64 | |
35089bb2 | 65 | /* By default, RFC2861 behavior. */ |
ab32ea5d | 66 | int sysctl_tcp_slow_start_after_idle __read_mostly = 1; |
35089bb2 | 67 | |
c9bee3b7 ED |
68 | unsigned int sysctl_tcp_notsent_lowat __read_mostly = UINT_MAX; |
69 | EXPORT_SYMBOL(sysctl_tcp_notsent_lowat); | |
70 | ||
46d3ceab ED |
71 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
72 | int push_one, gfp_t gfp); | |
519855c5 | 73 | |
67edfef7 | 74 | /* Account for new data that has been sent to the network. */ |
cf533ea5 | 75 | static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) |
1da177e4 | 76 | { |
6ba8a3b1 | 77 | struct inet_connection_sock *icsk = inet_csk(sk); |
9e412ba7 | 78 | struct tcp_sock *tp = tcp_sk(sk); |
66f5fe62 | 79 | unsigned int prior_packets = tp->packets_out; |
9e412ba7 | 80 | |
fe067e8a | 81 | tcp_advance_send_head(sk, skb); |
1da177e4 | 82 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; |
8512430e | 83 | |
66f5fe62 | 84 | tp->packets_out += tcp_skb_pcount(skb); |
6ba8a3b1 | 85 | if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || |
6a5dc9e5 | 86 | icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { |
750ea2ba | 87 | tcp_rearm_rto(sk); |
6a5dc9e5 | 88 | } |
f19c29e3 | 89 | |
f7324acd DM |
90 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, |
91 | tcp_skb_pcount(skb)); | |
1da177e4 LT |
92 | } |
93 | ||
94 | /* SND.NXT, if window was not shrunk. | |
95 | * If window has been shrunk, what should we make? It is not clear at all. | |
96 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
97 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
98 | * invalid. OK, let's make this for now: | |
99 | */ | |
cf533ea5 | 100 | static inline __u32 tcp_acceptable_seq(const struct sock *sk) |
1da177e4 | 101 | { |
cf533ea5 | 102 | const struct tcp_sock *tp = tcp_sk(sk); |
9e412ba7 | 103 | |
90840def | 104 | if (!before(tcp_wnd_end(tp), tp->snd_nxt)) |
1da177e4 LT |
105 | return tp->snd_nxt; |
106 | else | |
90840def | 107 | return tcp_wnd_end(tp); |
1da177e4 LT |
108 | } |
109 | ||
110 | /* Calculate mss to advertise in SYN segment. | |
111 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
112 | * | |
113 | * 1. It is independent of path mtu. | |
114 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
115 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
116 | * attached devices, because some buggy hosts are confused by | |
117 | * large MSS. | |
118 | * 4. We do not make 3, we advertise MSS, calculated from first | |
119 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
120 | * This may be overridden via information stored in routing table. | |
121 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
122 | * probably even Jumbo". | |
123 | */ | |
124 | static __u16 tcp_advertise_mss(struct sock *sk) | |
125 | { | |
126 | struct tcp_sock *tp = tcp_sk(sk); | |
cf533ea5 | 127 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
128 | int mss = tp->advmss; |
129 | ||
0dbaee3b DM |
130 | if (dst) { |
131 | unsigned int metric = dst_metric_advmss(dst); | |
132 | ||
133 | if (metric < mss) { | |
134 | mss = metric; | |
135 | tp->advmss = mss; | |
136 | } | |
1da177e4 LT |
137 | } |
138 | ||
139 | return (__u16)mss; | |
140 | } | |
141 | ||
142 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
143 | * This is the first part of cwnd validation mechanism. */ | |
cf533ea5 | 144 | static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst) |
1da177e4 | 145 | { |
463c84b9 | 146 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
147 | s32 delta = tcp_time_stamp - tp->lsndtime; |
148 | u32 restart_cwnd = tcp_init_cwnd(tp, dst); | |
149 | u32 cwnd = tp->snd_cwnd; | |
150 | ||
6687e988 | 151 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 152 | |
6687e988 | 153 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
154 | restart_cwnd = min(restart_cwnd, cwnd); |
155 | ||
463c84b9 | 156 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
157 | cwnd >>= 1; |
158 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
159 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
160 | tp->snd_cwnd_used = 0; | |
161 | } | |
162 | ||
67edfef7 | 163 | /* Congestion state accounting after a packet has been sent. */ |
40efc6fa | 164 | static void tcp_event_data_sent(struct tcp_sock *tp, |
cf533ea5 | 165 | struct sock *sk) |
1da177e4 | 166 | { |
463c84b9 ACM |
167 | struct inet_connection_sock *icsk = inet_csk(sk); |
168 | const u32 now = tcp_time_stamp; | |
bcefe17c | 169 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 | 170 | |
35089bb2 DM |
171 | if (sysctl_tcp_slow_start_after_idle && |
172 | (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) | |
463c84b9 | 173 | tcp_cwnd_restart(sk, __sk_dst_get(sk)); |
1da177e4 LT |
174 | |
175 | tp->lsndtime = now; | |
176 | ||
177 | /* If it is a reply for ato after last received | |
178 | * packet, enter pingpong mode. | |
179 | */ | |
bcefe17c CW |
180 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato && |
181 | (!dst || !dst_metric(dst, RTAX_QUICKACK))) | |
182 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
183 | } |
184 | ||
67edfef7 | 185 | /* Account for an ACK we sent. */ |
40efc6fa | 186 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 187 | { |
463c84b9 ACM |
188 | tcp_dec_quickack_mode(sk, pkts); |
189 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
190 | } |
191 | ||
85f16525 YC |
192 | |
193 | u32 tcp_default_init_rwnd(u32 mss) | |
194 | { | |
195 | /* Initial receive window should be twice of TCP_INIT_CWND to | |
9ef71e0c | 196 | * enable proper sending of new unsent data during fast recovery |
85f16525 YC |
197 | * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a |
198 | * limit when mss is larger than 1460. | |
199 | */ | |
200 | u32 init_rwnd = TCP_INIT_CWND * 2; | |
201 | ||
202 | if (mss > 1460) | |
203 | init_rwnd = max((1460 * init_rwnd) / mss, 2U); | |
204 | return init_rwnd; | |
205 | } | |
206 | ||
1da177e4 LT |
207 | /* Determine a window scaling and initial window to offer. |
208 | * Based on the assumption that the given amount of space | |
209 | * will be offered. Store the results in the tp structure. | |
210 | * NOTE: for smooth operation initial space offering should | |
211 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
212 | * This MUST be enforced by all callers. | |
213 | */ | |
214 | void tcp_select_initial_window(int __space, __u32 mss, | |
215 | __u32 *rcv_wnd, __u32 *window_clamp, | |
31d12926 | 216 | int wscale_ok, __u8 *rcv_wscale, |
217 | __u32 init_rcv_wnd) | |
1da177e4 LT |
218 | { |
219 | unsigned int space = (__space < 0 ? 0 : __space); | |
220 | ||
221 | /* If no clamp set the clamp to the max possible scaled window */ | |
222 | if (*window_clamp == 0) | |
223 | (*window_clamp) = (65535 << 14); | |
224 | space = min(*window_clamp, space); | |
225 | ||
226 | /* Quantize space offering to a multiple of mss if possible. */ | |
227 | if (space > mss) | |
228 | space = (space / mss) * mss; | |
229 | ||
230 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
231 | * will break some buggy TCP stacks. If the admin tells us |
232 | * it is likely we could be speaking with such a buggy stack | |
233 | * we will truncate our initial window offering to 32K-1 | |
234 | * unless the remote has sent us a window scaling option, | |
235 | * which we interpret as a sign the remote TCP is not | |
236 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 237 | */ |
15d99e02 RJ |
238 | if (sysctl_tcp_workaround_signed_windows) |
239 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
240 | else | |
241 | (*rcv_wnd) = space; | |
242 | ||
1da177e4 LT |
243 | (*rcv_wscale) = 0; |
244 | if (wscale_ok) { | |
245 | /* Set window scaling on max possible window | |
e905a9ed | 246 | * See RFC1323 for an explanation of the limit to 14 |
1da177e4 LT |
247 | */ |
248 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
316c1592 | 249 | space = min_t(u32, space, *window_clamp); |
1da177e4 LT |
250 | while (space > 65535 && (*rcv_wscale) < 14) { |
251 | space >>= 1; | |
252 | (*rcv_wscale)++; | |
253 | } | |
254 | } | |
255 | ||
056834d9 | 256 | if (mss > (1 << *rcv_wscale)) { |
85f16525 YC |
257 | if (!init_rcv_wnd) /* Use default unless specified otherwise */ |
258 | init_rcv_wnd = tcp_default_init_rwnd(mss); | |
259 | *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); | |
1da177e4 LT |
260 | } |
261 | ||
262 | /* Set the clamp no higher than max representable value */ | |
263 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
264 | } | |
4bc2f18b | 265 | EXPORT_SYMBOL(tcp_select_initial_window); |
1da177e4 LT |
266 | |
267 | /* Chose a new window to advertise, update state in tcp_sock for the | |
268 | * socket, and return result with RFC1323 scaling applied. The return | |
269 | * value can be stuffed directly into th->window for an outgoing | |
270 | * frame. | |
271 | */ | |
40efc6fa | 272 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
273 | { |
274 | struct tcp_sock *tp = tcp_sk(sk); | |
8e165e20 | 275 | u32 old_win = tp->rcv_wnd; |
1da177e4 LT |
276 | u32 cur_win = tcp_receive_window(tp); |
277 | u32 new_win = __tcp_select_window(sk); | |
278 | ||
279 | /* Never shrink the offered window */ | |
2de979bd | 280 | if (new_win < cur_win) { |
1da177e4 LT |
281 | /* Danger Will Robinson! |
282 | * Don't update rcv_wup/rcv_wnd here or else | |
283 | * we will not be able to advertise a zero | |
284 | * window in time. --DaveM | |
285 | * | |
286 | * Relax Will Robinson. | |
287 | */ | |
8e165e20 FW |
288 | if (new_win == 0) |
289 | NET_INC_STATS(sock_net(sk), | |
290 | LINUX_MIB_TCPWANTZEROWINDOWADV); | |
607bfbf2 | 291 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
292 | } |
293 | tp->rcv_wnd = new_win; | |
294 | tp->rcv_wup = tp->rcv_nxt; | |
295 | ||
296 | /* Make sure we do not exceed the maximum possible | |
297 | * scaled window. | |
298 | */ | |
15d99e02 | 299 | if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) |
1da177e4 LT |
300 | new_win = min(new_win, MAX_TCP_WINDOW); |
301 | else | |
302 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
303 | ||
304 | /* RFC1323 scaling applied */ | |
305 | new_win >>= tp->rx_opt.rcv_wscale; | |
306 | ||
307 | /* If we advertise zero window, disable fast path. */ | |
8e165e20 | 308 | if (new_win == 0) { |
1da177e4 | 309 | tp->pred_flags = 0; |
8e165e20 FW |
310 | if (old_win) |
311 | NET_INC_STATS(sock_net(sk), | |
312 | LINUX_MIB_TCPTOZEROWINDOWADV); | |
313 | } else if (old_win == 0) { | |
314 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); | |
315 | } | |
1da177e4 LT |
316 | |
317 | return new_win; | |
318 | } | |
319 | ||
67edfef7 | 320 | /* Packet ECN state for a SYN-ACK */ |
30e502a3 | 321 | static inline void TCP_ECN_send_synack(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d | 322 | { |
30e502a3 DB |
323 | const struct tcp_sock *tp = tcp_sk(sk); |
324 | ||
4de075e0 | 325 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
056834d9 | 326 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
4de075e0 | 327 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
30e502a3 DB |
328 | else if (tcp_ca_needs_ecn(sk)) |
329 | INET_ECN_xmit(sk); | |
bdf1ee5d IJ |
330 | } |
331 | ||
67edfef7 | 332 | /* Packet ECN state for a SYN. */ |
bdf1ee5d IJ |
333 | static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) |
334 | { | |
335 | struct tcp_sock *tp = tcp_sk(sk); | |
336 | ||
337 | tp->ecn_flags = 0; | |
30e502a3 DB |
338 | if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || |
339 | tcp_ca_needs_ecn(sk)) { | |
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 | ||
347 | static __inline__ void | |
30e502a3 DB |
348 | TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th, |
349 | struct sock *sk) | |
bdf1ee5d | 350 | { |
30e502a3 | 351 | if (inet_rsk(req)->ecn_ok) { |
bdf1ee5d | 352 | th->ece = 1; |
30e502a3 DB |
353 | if (tcp_ca_needs_ecn(sk)) |
354 | INET_ECN_xmit(sk); | |
355 | } | |
bdf1ee5d IJ |
356 | } |
357 | ||
67edfef7 AK |
358 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
359 | * be sent. | |
360 | */ | |
bdf1ee5d IJ |
361 | static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, |
362 | int tcp_header_len) | |
363 | { | |
364 | struct tcp_sock *tp = tcp_sk(sk); | |
365 | ||
366 | if (tp->ecn_flags & TCP_ECN_OK) { | |
367 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
368 | if (skb->len != tcp_header_len && | |
369 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
370 | INET_ECN_xmit(sk); | |
056834d9 | 371 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d IJ |
372 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
373 | tcp_hdr(skb)->cwr = 1; | |
374 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; | |
375 | } | |
30e502a3 | 376 | } else if (!tcp_ca_needs_ecn(sk)) { |
bdf1ee5d IJ |
377 | /* ACK or retransmitted segment: clear ECT|CE */ |
378 | INET_ECN_dontxmit(sk); | |
379 | } | |
380 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
381 | tcp_hdr(skb)->ece = 1; | |
382 | } | |
383 | } | |
384 | ||
e870a8ef IJ |
385 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
386 | * auto increment end seqno. | |
387 | */ | |
388 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
389 | { | |
7b7fc97a ED |
390 | struct skb_shared_info *shinfo = skb_shinfo(skb); |
391 | ||
2e8e18ef | 392 | skb->ip_summed = CHECKSUM_PARTIAL; |
e870a8ef IJ |
393 | skb->csum = 0; |
394 | ||
4de075e0 | 395 | TCP_SKB_CB(skb)->tcp_flags = flags; |
e870a8ef IJ |
396 | TCP_SKB_CB(skb)->sacked = 0; |
397 | ||
cd7d8498 | 398 | tcp_skb_pcount_set(skb, 1); |
7b7fc97a ED |
399 | shinfo->gso_size = 0; |
400 | shinfo->gso_type = 0; | |
e870a8ef IJ |
401 | |
402 | TCP_SKB_CB(skb)->seq = seq; | |
a3433f35 | 403 | if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
e870a8ef IJ |
404 | seq++; |
405 | TCP_SKB_CB(skb)->end_seq = seq; | |
406 | } | |
407 | ||
a2a385d6 | 408 | static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
33f5f57e IJ |
409 | { |
410 | return tp->snd_una != tp->snd_up; | |
411 | } | |
412 | ||
33ad798c AL |
413 | #define OPTION_SACK_ADVERTISE (1 << 0) |
414 | #define OPTION_TS (1 << 1) | |
415 | #define OPTION_MD5 (1 << 2) | |
89e95a61 | 416 | #define OPTION_WSCALE (1 << 3) |
2100c8d2 | 417 | #define OPTION_FAST_OPEN_COOKIE (1 << 8) |
33ad798c AL |
418 | |
419 | struct tcp_out_options { | |
2100c8d2 YC |
420 | u16 options; /* bit field of OPTION_* */ |
421 | u16 mss; /* 0 to disable */ | |
33ad798c AL |
422 | u8 ws; /* window scale, 0 to disable */ |
423 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 424 | u8 hash_size; /* bytes in hash_location */ |
bd0388ae | 425 | __u8 *hash_location; /* temporary pointer, overloaded */ |
2100c8d2 YC |
426 | __u32 tsval, tsecr; /* need to include OPTION_TS */ |
427 | struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ | |
33ad798c AL |
428 | }; |
429 | ||
67edfef7 AK |
430 | /* Write previously computed TCP options to the packet. |
431 | * | |
432 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
433 | * TCP options, we learned this through the hard way, so be careful here. |
434 | * Luckily we can at least blame others for their non-compliance but from | |
8e3bff96 | 435 | * inter-operability perspective it seems that we're somewhat stuck with |
fd6149d3 IJ |
436 | * the ordering which we have been using if we want to keep working with |
437 | * those broken things (not that it currently hurts anybody as there isn't | |
438 | * particular reason why the ordering would need to be changed). | |
439 | * | |
440 | * At least SACK_PERM as the first option is known to lead to a disaster | |
441 | * (but it may well be that other scenarios fail similarly). | |
442 | */ | |
33ad798c | 443 | static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
bd0388ae WAS |
444 | struct tcp_out_options *opts) |
445 | { | |
2100c8d2 | 446 | u16 options = opts->options; /* mungable copy */ |
bd0388ae | 447 | |
bd0388ae | 448 | if (unlikely(OPTION_MD5 & options)) { |
1a2c6181 CP |
449 | *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
450 | (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); | |
bd0388ae WAS |
451 | /* overload cookie hash location */ |
452 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 453 | ptr += 4; |
40efc6fa | 454 | } |
33ad798c | 455 | |
fd6149d3 IJ |
456 | if (unlikely(opts->mss)) { |
457 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
458 | (TCPOLEN_MSS << 16) | | |
459 | opts->mss); | |
460 | } | |
461 | ||
bd0388ae WAS |
462 | if (likely(OPTION_TS & options)) { |
463 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
464 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
465 | (TCPOLEN_SACK_PERM << 16) | | |
466 | (TCPOPT_TIMESTAMP << 8) | | |
467 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 468 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
469 | } else { |
470 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
471 | (TCPOPT_NOP << 16) | | |
472 | (TCPOPT_TIMESTAMP << 8) | | |
473 | TCPOLEN_TIMESTAMP); | |
474 | } | |
475 | *ptr++ = htonl(opts->tsval); | |
476 | *ptr++ = htonl(opts->tsecr); | |
477 | } | |
478 | ||
bd0388ae | 479 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
33ad798c AL |
480 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
481 | (TCPOPT_NOP << 16) | | |
482 | (TCPOPT_SACK_PERM << 8) | | |
483 | TCPOLEN_SACK_PERM); | |
484 | } | |
485 | ||
bd0388ae | 486 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
487 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
488 | (TCPOPT_WINDOW << 16) | | |
489 | (TCPOLEN_WINDOW << 8) | | |
490 | opts->ws); | |
491 | } | |
492 | ||
493 | if (unlikely(opts->num_sack_blocks)) { | |
494 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
495 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
496 | int this_sack; |
497 | ||
498 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
499 | (TCPOPT_NOP << 16) | | |
500 | (TCPOPT_SACK << 8) | | |
33ad798c | 501 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 502 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 503 | |
33ad798c AL |
504 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
505 | ++this_sack) { | |
40efc6fa SH |
506 | *ptr++ = htonl(sp[this_sack].start_seq); |
507 | *ptr++ = htonl(sp[this_sack].end_seq); | |
508 | } | |
2de979bd | 509 | |
5861f8e5 | 510 | tp->rx_opt.dsack = 0; |
40efc6fa | 511 | } |
2100c8d2 YC |
512 | |
513 | if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { | |
514 | struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; | |
515 | ||
516 | *ptr++ = htonl((TCPOPT_EXP << 24) | | |
517 | ((TCPOLEN_EXP_FASTOPEN_BASE + foc->len) << 16) | | |
518 | TCPOPT_FASTOPEN_MAGIC); | |
519 | ||
520 | memcpy(ptr, foc->val, foc->len); | |
521 | if ((foc->len & 3) == 2) { | |
522 | u8 *align = ((u8 *)ptr) + foc->len; | |
523 | align[0] = align[1] = TCPOPT_NOP; | |
524 | } | |
525 | ptr += (foc->len + 3) >> 2; | |
526 | } | |
33ad798c AL |
527 | } |
528 | ||
67edfef7 AK |
529 | /* Compute TCP options for SYN packets. This is not the final |
530 | * network wire format yet. | |
531 | */ | |
95c96174 | 532 | static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 533 | struct tcp_out_options *opts, |
cf533ea5 ED |
534 | struct tcp_md5sig_key **md5) |
535 | { | |
33ad798c | 536 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 537 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
783237e8 | 538 | struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
33ad798c | 539 | |
cfb6eeb4 | 540 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
541 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
542 | if (*md5) { | |
543 | opts->options |= OPTION_MD5; | |
bd0388ae | 544 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
cfb6eeb4 | 545 | } |
33ad798c AL |
546 | #else |
547 | *md5 = NULL; | |
cfb6eeb4 | 548 | #endif |
33ad798c AL |
549 | |
550 | /* We always get an MSS option. The option bytes which will be seen in | |
551 | * normal data packets should timestamps be used, must be in the MSS | |
552 | * advertised. But we subtract them from tp->mss_cache so that | |
553 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
554 | * fact here if necessary. If we don't do this correctly, as a | |
555 | * receiver we won't recognize data packets as being full sized when we | |
556 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
557 | * SACKs don't matter, we never delay an ACK when we have any of those | |
558 | * going out. */ | |
559 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 560 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 561 | |
bb5b7c11 | 562 | if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { |
33ad798c | 563 | opts->options |= OPTION_TS; |
7faee5c0 | 564 | opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; |
33ad798c | 565 | opts->tsecr = tp->rx_opt.ts_recent; |
bd0388ae | 566 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 567 | } |
bb5b7c11 | 568 | if (likely(sysctl_tcp_window_scaling)) { |
33ad798c | 569 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 570 | opts->options |= OPTION_WSCALE; |
bd0388ae | 571 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 572 | } |
bb5b7c11 | 573 | if (likely(sysctl_tcp_sack)) { |
33ad798c | 574 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 575 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 576 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
577 | } |
578 | ||
783237e8 YC |
579 | if (fastopen && fastopen->cookie.len >= 0) { |
580 | u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len; | |
581 | need = (need + 3) & ~3U; /* Align to 32 bits */ | |
582 | if (remaining >= need) { | |
583 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
584 | opts->fastopen_cookie = &fastopen->cookie; | |
585 | remaining -= need; | |
586 | tp->syn_fastopen = 1; | |
587 | } | |
588 | } | |
bd0388ae | 589 | |
bd0388ae | 590 | return MAX_TCP_OPTION_SPACE - remaining; |
40efc6fa SH |
591 | } |
592 | ||
67edfef7 | 593 | /* Set up TCP options for SYN-ACKs. */ |
95c96174 | 594 | static unsigned int tcp_synack_options(struct sock *sk, |
33ad798c | 595 | struct request_sock *req, |
95c96174 | 596 | unsigned int mss, struct sk_buff *skb, |
33ad798c | 597 | struct tcp_out_options *opts, |
4957faad | 598 | struct tcp_md5sig_key **md5, |
8336886f | 599 | struct tcp_fastopen_cookie *foc) |
4957faad | 600 | { |
33ad798c | 601 | struct inet_request_sock *ireq = inet_rsk(req); |
95c96174 | 602 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
33ad798c | 603 | |
cfb6eeb4 | 604 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
605 | *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); |
606 | if (*md5) { | |
607 | opts->options |= OPTION_MD5; | |
4957faad WAS |
608 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
609 | ||
610 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
611 | * options. There was discussion about disabling SACK | |
612 | * rather than TS in order to fit in better with old, | |
613 | * buggy kernels, but that was deemed to be unnecessary. | |
614 | */ | |
de213e5e | 615 | ireq->tstamp_ok &= !ireq->sack_ok; |
cfb6eeb4 | 616 | } |
33ad798c AL |
617 | #else |
618 | *md5 = NULL; | |
cfb6eeb4 | 619 | #endif |
33ad798c | 620 | |
4957faad | 621 | /* We always send an MSS option. */ |
33ad798c | 622 | opts->mss = mss; |
4957faad | 623 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
624 | |
625 | if (likely(ireq->wscale_ok)) { | |
626 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 627 | opts->options |= OPTION_WSCALE; |
4957faad | 628 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 629 | } |
de213e5e | 630 | if (likely(ireq->tstamp_ok)) { |
33ad798c | 631 | opts->options |= OPTION_TS; |
7faee5c0 | 632 | opts->tsval = tcp_skb_timestamp(skb); |
33ad798c | 633 | opts->tsecr = req->ts_recent; |
4957faad | 634 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
635 | } |
636 | if (likely(ireq->sack_ok)) { | |
637 | opts->options |= OPTION_SACK_ADVERTISE; | |
de213e5e | 638 | if (unlikely(!ireq->tstamp_ok)) |
4957faad | 639 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c | 640 | } |
89278c9d | 641 | if (foc != NULL && foc->len >= 0) { |
8336886f JC |
642 | u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; |
643 | need = (need + 3) & ~3U; /* Align to 32 bits */ | |
644 | if (remaining >= need) { | |
645 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
646 | opts->fastopen_cookie = foc; | |
647 | remaining -= need; | |
648 | } | |
649 | } | |
1a2c6181 | 650 | |
4957faad | 651 | return MAX_TCP_OPTION_SPACE - remaining; |
33ad798c AL |
652 | } |
653 | ||
67edfef7 AK |
654 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
655 | * final wire format yet. | |
656 | */ | |
95c96174 | 657 | static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 658 | struct tcp_out_options *opts, |
cf533ea5 ED |
659 | struct tcp_md5sig_key **md5) |
660 | { | |
33ad798c | 661 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 662 | unsigned int size = 0; |
cabeccbd | 663 | unsigned int eff_sacks; |
33ad798c | 664 | |
5843ef42 AK |
665 | opts->options = 0; |
666 | ||
33ad798c AL |
667 | #ifdef CONFIG_TCP_MD5SIG |
668 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
669 | if (unlikely(*md5)) { | |
670 | opts->options |= OPTION_MD5; | |
671 | size += TCPOLEN_MD5SIG_ALIGNED; | |
672 | } | |
673 | #else | |
674 | *md5 = NULL; | |
675 | #endif | |
676 | ||
677 | if (likely(tp->rx_opt.tstamp_ok)) { | |
678 | opts->options |= OPTION_TS; | |
7faee5c0 | 679 | opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; |
33ad798c AL |
680 | opts->tsecr = tp->rx_opt.ts_recent; |
681 | size += TCPOLEN_TSTAMP_ALIGNED; | |
682 | } | |
683 | ||
cabeccbd IJ |
684 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
685 | if (unlikely(eff_sacks)) { | |
95c96174 | 686 | const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
33ad798c | 687 | opts->num_sack_blocks = |
95c96174 | 688 | min_t(unsigned int, eff_sacks, |
33ad798c AL |
689 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
690 | TCPOLEN_SACK_PERBLOCK); | |
691 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
692 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
693 | } | |
694 | ||
695 | return size; | |
40efc6fa | 696 | } |
1da177e4 | 697 | |
46d3ceab ED |
698 | |
699 | /* TCP SMALL QUEUES (TSQ) | |
700 | * | |
701 | * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) | |
702 | * to reduce RTT and bufferbloat. | |
703 | * We do this using a special skb destructor (tcp_wfree). | |
704 | * | |
705 | * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb | |
706 | * needs to be reallocated in a driver. | |
8e3bff96 | 707 | * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
46d3ceab ED |
708 | * |
709 | * Since transmit from skb destructor is forbidden, we use a tasklet | |
710 | * to process all sockets that eventually need to send more skbs. | |
711 | * We use one tasklet per cpu, with its own queue of sockets. | |
712 | */ | |
713 | struct tsq_tasklet { | |
714 | struct tasklet_struct tasklet; | |
715 | struct list_head head; /* queue of tcp sockets */ | |
716 | }; | |
717 | static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); | |
718 | ||
6f458dfb ED |
719 | static void tcp_tsq_handler(struct sock *sk) |
720 | { | |
721 | if ((1 << sk->sk_state) & | |
722 | (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | | |
723 | TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) | |
bf06200e JO |
724 | tcp_write_xmit(sk, tcp_current_mss(sk), tcp_sk(sk)->nonagle, |
725 | 0, GFP_ATOMIC); | |
6f458dfb | 726 | } |
46d3ceab | 727 | /* |
8e3bff96 | 728 | * One tasklet per cpu tries to send more skbs. |
46d3ceab | 729 | * We run in tasklet context but need to disable irqs when |
8e3bff96 | 730 | * transferring tsq->head because tcp_wfree() might |
46d3ceab ED |
731 | * interrupt us (non NAPI drivers) |
732 | */ | |
733 | static void tcp_tasklet_func(unsigned long data) | |
734 | { | |
735 | struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; | |
736 | LIST_HEAD(list); | |
737 | unsigned long flags; | |
738 | struct list_head *q, *n; | |
739 | struct tcp_sock *tp; | |
740 | struct sock *sk; | |
741 | ||
742 | local_irq_save(flags); | |
743 | list_splice_init(&tsq->head, &list); | |
744 | local_irq_restore(flags); | |
745 | ||
746 | list_for_each_safe(q, n, &list) { | |
747 | tp = list_entry(q, struct tcp_sock, tsq_node); | |
748 | list_del(&tp->tsq_node); | |
749 | ||
750 | sk = (struct sock *)tp; | |
751 | bh_lock_sock(sk); | |
752 | ||
753 | if (!sock_owned_by_user(sk)) { | |
6f458dfb | 754 | tcp_tsq_handler(sk); |
46d3ceab ED |
755 | } else { |
756 | /* defer the work to tcp_release_cb() */ | |
6f458dfb | 757 | set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); |
46d3ceab ED |
758 | } |
759 | bh_unlock_sock(sk); | |
760 | ||
761 | clear_bit(TSQ_QUEUED, &tp->tsq_flags); | |
762 | sk_free(sk); | |
763 | } | |
764 | } | |
765 | ||
6f458dfb ED |
766 | #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ |
767 | (1UL << TCP_WRITE_TIMER_DEFERRED) | \ | |
563d34d0 ED |
768 | (1UL << TCP_DELACK_TIMER_DEFERRED) | \ |
769 | (1UL << TCP_MTU_REDUCED_DEFERRED)) | |
46d3ceab ED |
770 | /** |
771 | * tcp_release_cb - tcp release_sock() callback | |
772 | * @sk: socket | |
773 | * | |
774 | * called from release_sock() to perform protocol dependent | |
775 | * actions before socket release. | |
776 | */ | |
777 | void tcp_release_cb(struct sock *sk) | |
778 | { | |
779 | struct tcp_sock *tp = tcp_sk(sk); | |
6f458dfb | 780 | unsigned long flags, nflags; |
46d3ceab | 781 | |
6f458dfb ED |
782 | /* perform an atomic operation only if at least one flag is set */ |
783 | do { | |
784 | flags = tp->tsq_flags; | |
785 | if (!(flags & TCP_DEFERRED_ALL)) | |
786 | return; | |
787 | nflags = flags & ~TCP_DEFERRED_ALL; | |
788 | } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); | |
789 | ||
790 | if (flags & (1UL << TCP_TSQ_DEFERRED)) | |
791 | tcp_tsq_handler(sk); | |
792 | ||
c3f9b018 ED |
793 | /* Here begins the tricky part : |
794 | * We are called from release_sock() with : | |
795 | * 1) BH disabled | |
796 | * 2) sk_lock.slock spinlock held | |
797 | * 3) socket owned by us (sk->sk_lock.owned == 1) | |
798 | * | |
799 | * But following code is meant to be called from BH handlers, | |
800 | * so we should keep BH disabled, but early release socket ownership | |
801 | */ | |
802 | sock_release_ownership(sk); | |
803 | ||
144d56e9 | 804 | if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { |
6f458dfb | 805 | tcp_write_timer_handler(sk); |
144d56e9 ED |
806 | __sock_put(sk); |
807 | } | |
808 | if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { | |
6f458dfb | 809 | tcp_delack_timer_handler(sk); |
144d56e9 ED |
810 | __sock_put(sk); |
811 | } | |
812 | if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { | |
4fab9071 | 813 | inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); |
144d56e9 ED |
814 | __sock_put(sk); |
815 | } | |
46d3ceab ED |
816 | } |
817 | EXPORT_SYMBOL(tcp_release_cb); | |
818 | ||
819 | void __init tcp_tasklet_init(void) | |
820 | { | |
821 | int i; | |
822 | ||
823 | for_each_possible_cpu(i) { | |
824 | struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); | |
825 | ||
826 | INIT_LIST_HEAD(&tsq->head); | |
827 | tasklet_init(&tsq->tasklet, | |
828 | tcp_tasklet_func, | |
829 | (unsigned long)tsq); | |
830 | } | |
831 | } | |
832 | ||
833 | /* | |
834 | * Write buffer destructor automatically called from kfree_skb. | |
8e3bff96 | 835 | * We can't xmit new skbs from this context, as we might already |
46d3ceab ED |
836 | * hold qdisc lock. |
837 | */ | |
d6a4a104 | 838 | void tcp_wfree(struct sk_buff *skb) |
46d3ceab ED |
839 | { |
840 | struct sock *sk = skb->sk; | |
841 | struct tcp_sock *tp = tcp_sk(sk); | |
842 | ||
843 | if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && | |
844 | !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { | |
845 | unsigned long flags; | |
846 | struct tsq_tasklet *tsq; | |
847 | ||
848 | /* Keep a ref on socket. | |
849 | * This last ref will be released in tcp_tasklet_func() | |
850 | */ | |
851 | atomic_sub(skb->truesize - 1, &sk->sk_wmem_alloc); | |
852 | ||
853 | /* queue this socket to tasklet queue */ | |
854 | local_irq_save(flags); | |
855 | tsq = &__get_cpu_var(tsq_tasklet); | |
856 | list_add(&tp->tsq_node, &tsq->head); | |
857 | tasklet_schedule(&tsq->tasklet); | |
858 | local_irq_restore(flags); | |
859 | } else { | |
860 | sock_wfree(skb); | |
861 | } | |
862 | } | |
863 | ||
1da177e4 LT |
864 | /* This routine actually transmits TCP packets queued in by |
865 | * tcp_do_sendmsg(). This is used by both the initial | |
866 | * transmission and possible later retransmissions. | |
867 | * All SKB's seen here are completely headerless. It is our | |
868 | * job to build the TCP header, and pass the packet down to | |
869 | * IP so it can do the same plus pass the packet off to the | |
870 | * device. | |
871 | * | |
872 | * We are working here with either a clone of the original | |
873 | * SKB, or a fresh unique copy made by the retransmit engine. | |
874 | */ | |
056834d9 IJ |
875 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
876 | gfp_t gfp_mask) | |
1da177e4 | 877 | { |
dfb4b9dc DM |
878 | const struct inet_connection_sock *icsk = inet_csk(sk); |
879 | struct inet_sock *inet; | |
880 | struct tcp_sock *tp; | |
881 | struct tcp_skb_cb *tcb; | |
33ad798c | 882 | struct tcp_out_options opts; |
95c96174 | 883 | unsigned int tcp_options_size, tcp_header_size; |
cfb6eeb4 | 884 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 885 | struct tcphdr *th; |
dfb4b9dc DM |
886 | int err; |
887 | ||
888 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
889 | ||
ccdbb6e9 | 890 | if (clone_it) { |
740b0f18 | 891 | skb_mstamp_get(&skb->skb_mstamp); |
ccdbb6e9 | 892 | |
dfb4b9dc DM |
893 | if (unlikely(skb_cloned(skb))) |
894 | skb = pskb_copy(skb, gfp_mask); | |
895 | else | |
896 | skb = skb_clone(skb, gfp_mask); | |
897 | if (unlikely(!skb)) | |
898 | return -ENOBUFS; | |
899 | } | |
1da177e4 | 900 | |
dfb4b9dc DM |
901 | inet = inet_sk(sk); |
902 | tp = tcp_sk(sk); | |
903 | tcb = TCP_SKB_CB(skb); | |
33ad798c | 904 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 905 | |
4de075e0 | 906 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) |
33ad798c AL |
907 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
908 | else | |
909 | tcp_options_size = tcp_established_options(sk, skb, &opts, | |
910 | &md5); | |
911 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); | |
e905a9ed | 912 | |
547669d4 | 913 | if (tcp_packets_in_flight(tp) == 0) |
dfb4b9dc | 914 | tcp_ca_event(sk, CA_EVENT_TX_START); |
547669d4 ED |
915 | |
916 | /* if no packet is in qdisc/device queue, then allow XPS to select | |
917 | * another queue. | |
918 | */ | |
919 | skb->ooo_okay = sk_wmem_alloc_get(sk) == 0; | |
dfb4b9dc | 920 | |
aa8223c7 ACM |
921 | skb_push(skb, tcp_header_size); |
922 | skb_reset_transport_header(skb); | |
46d3ceab ED |
923 | |
924 | skb_orphan(skb); | |
925 | skb->sk = sk; | |
c9eeec26 | 926 | skb->destructor = tcp_wfree; |
b73c3d0e | 927 | skb_set_hash_from_sk(skb, sk); |
46d3ceab | 928 | atomic_add(skb->truesize, &sk->sk_wmem_alloc); |
dfb4b9dc DM |
929 | |
930 | /* Build TCP header and checksum it. */ | |
aa8223c7 | 931 | th = tcp_hdr(skb); |
c720c7e8 ED |
932 | th->source = inet->inet_sport; |
933 | th->dest = inet->inet_dport; | |
dfb4b9dc DM |
934 | th->seq = htonl(tcb->seq); |
935 | th->ack_seq = htonl(tp->rcv_nxt); | |
df7a3b07 | 936 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
4de075e0 | 937 | tcb->tcp_flags); |
dfb4b9dc | 938 | |
4de075e0 | 939 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
dfb4b9dc DM |
940 | /* RFC1323: The window in SYN & SYN/ACK segments |
941 | * is never scaled. | |
942 | */ | |
600ff0c2 | 943 | th->window = htons(min(tp->rcv_wnd, 65535U)); |
dfb4b9dc DM |
944 | } else { |
945 | th->window = htons(tcp_select_window(sk)); | |
946 | } | |
947 | th->check = 0; | |
948 | th->urg_ptr = 0; | |
1da177e4 | 949 | |
33f5f57e | 950 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
951 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
952 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
953 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
954 | th->urg = 1; | |
955 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
0eae88f3 | 956 | th->urg_ptr = htons(0xFFFF); |
7691367d HX |
957 | th->urg = 1; |
958 | } | |
dfb4b9dc | 959 | } |
1da177e4 | 960 | |
bd0388ae | 961 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
4de075e0 | 962 | if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) |
9e412ba7 | 963 | TCP_ECN_send(sk, skb, tcp_header_size); |
1da177e4 | 964 | |
cfb6eeb4 YH |
965 | #ifdef CONFIG_TCP_MD5SIG |
966 | /* Calculate the MD5 hash, as we have all we need now */ | |
967 | if (md5) { | |
a465419b | 968 | sk_nocaps_add(sk, NETIF_F_GSO_MASK); |
bd0388ae | 969 | tp->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 970 | md5, sk, NULL, skb); |
cfb6eeb4 YH |
971 | } |
972 | #endif | |
973 | ||
bb296246 | 974 | icsk->icsk_af_ops->send_check(sk, skb); |
1da177e4 | 975 | |
4de075e0 | 976 | if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
dfb4b9dc | 977 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); |
1da177e4 | 978 | |
dfb4b9dc | 979 | if (skb->len != tcp_header_size) |
cf533ea5 | 980 | tcp_event_data_sent(tp, sk); |
1da177e4 | 981 | |
bd37a088 | 982 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
aa2ea058 TH |
983 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
984 | tcp_skb_pcount(skb)); | |
1da177e4 | 985 | |
cd7d8498 ED |
986 | /* OK, its time to fill skb_shinfo(skb)->gso_segs */ |
987 | skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); | |
988 | ||
7faee5c0 ED |
989 | /* Our usage of tstamp should remain private */ |
990 | skb->tstamp.tv64 = 0; | |
971f10ec ED |
991 | |
992 | /* Cleanup our debris for IP stacks */ | |
993 | memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), | |
994 | sizeof(struct inet6_skb_parm))); | |
995 | ||
b0270e91 | 996 | err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); |
7faee5c0 | 997 | |
83de47cd | 998 | if (likely(err <= 0)) |
dfb4b9dc DM |
999 | return err; |
1000 | ||
5ee2c941 | 1001 | tcp_enter_cwr(sk); |
dfb4b9dc | 1002 | |
b9df3cb8 | 1003 | return net_xmit_eval(err); |
1da177e4 LT |
1004 | } |
1005 | ||
67edfef7 | 1006 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
1007 | * |
1008 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
1009 | * otherwise socket can stall. | |
1010 | */ | |
1011 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
1012 | { | |
1013 | struct tcp_sock *tp = tcp_sk(sk); | |
1014 | ||
1015 | /* Advance write_seq and place onto the write_queue. */ | |
1016 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
f4a775d1 | 1017 | __skb_header_release(skb); |
fe067e8a | 1018 | tcp_add_write_queue_tail(sk, skb); |
3ab224be HA |
1019 | sk->sk_wmem_queued += skb->truesize; |
1020 | sk_mem_charge(sk, skb->truesize); | |
1da177e4 LT |
1021 | } |
1022 | ||
67edfef7 | 1023 | /* Initialize TSO segments for a packet. */ |
cf533ea5 | 1024 | static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, |
056834d9 | 1025 | unsigned int mss_now) |
f6302d1d | 1026 | { |
7b7fc97a ED |
1027 | struct skb_shared_info *shinfo = skb_shinfo(skb); |
1028 | ||
c52e2421 ED |
1029 | /* Make sure we own this skb before messing gso_size/gso_segs */ |
1030 | WARN_ON_ONCE(skb_cloned(skb)); | |
1031 | ||
8f26fb1c | 1032 | if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) { |
f6302d1d DM |
1033 | /* Avoid the costly divide in the normal |
1034 | * non-TSO case. | |
1035 | */ | |
cd7d8498 | 1036 | tcp_skb_pcount_set(skb, 1); |
7b7fc97a ED |
1037 | shinfo->gso_size = 0; |
1038 | shinfo->gso_type = 0; | |
f6302d1d | 1039 | } else { |
cd7d8498 | 1040 | tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); |
7b7fc97a ED |
1041 | shinfo->gso_size = mss_now; |
1042 | shinfo->gso_type = sk->sk_gso_type; | |
1da177e4 LT |
1043 | } |
1044 | } | |
1045 | ||
91fed7a1 | 1046 | /* When a modification to fackets out becomes necessary, we need to check |
68f8353b | 1047 | * skb is counted to fackets_out or not. |
91fed7a1 | 1048 | */ |
cf533ea5 | 1049 | static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, |
91fed7a1 IJ |
1050 | int decr) |
1051 | { | |
a47e5a98 IJ |
1052 | struct tcp_sock *tp = tcp_sk(sk); |
1053 | ||
dc86967b | 1054 | if (!tp->sacked_out || tcp_is_reno(tp)) |
91fed7a1 IJ |
1055 | return; |
1056 | ||
6859d494 | 1057 | if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) |
91fed7a1 | 1058 | tp->fackets_out -= decr; |
91fed7a1 IJ |
1059 | } |
1060 | ||
797108d1 IJ |
1061 | /* Pcount in the middle of the write queue got changed, we need to do various |
1062 | * tweaks to fix counters | |
1063 | */ | |
cf533ea5 | 1064 | static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
797108d1 IJ |
1065 | { |
1066 | struct tcp_sock *tp = tcp_sk(sk); | |
1067 | ||
1068 | tp->packets_out -= decr; | |
1069 | ||
1070 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
1071 | tp->sacked_out -= decr; | |
1072 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
1073 | tp->retrans_out -= decr; | |
1074 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
1075 | tp->lost_out -= decr; | |
1076 | ||
1077 | /* Reno case is special. Sigh... */ | |
1078 | if (tcp_is_reno(tp) && decr > 0) | |
1079 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
1080 | ||
1081 | tcp_adjust_fackets_out(sk, skb, decr); | |
1082 | ||
1083 | if (tp->lost_skb_hint && | |
1084 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
52cf3cc8 | 1085 | (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) |
797108d1 IJ |
1086 | tp->lost_cnt_hint -= decr; |
1087 | ||
1088 | tcp_verify_left_out(tp); | |
1089 | } | |
1090 | ||
490cc7d0 WB |
1091 | static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) |
1092 | { | |
1093 | struct skb_shared_info *shinfo = skb_shinfo(skb); | |
1094 | ||
1095 | if (unlikely(shinfo->tx_flags & SKBTX_ANY_TSTAMP) && | |
1096 | !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { | |
1097 | struct skb_shared_info *shinfo2 = skb_shinfo(skb2); | |
1098 | u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; | |
1099 | ||
1100 | shinfo->tx_flags &= ~tsflags; | |
1101 | shinfo2->tx_flags |= tsflags; | |
1102 | swap(shinfo->tskey, shinfo2->tskey); | |
1103 | } | |
1104 | } | |
1105 | ||
1da177e4 LT |
1106 | /* Function to create two new TCP segments. Shrinks the given segment |
1107 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 1108 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
1109 | * Remember, these are still headerless SKBs at this point. |
1110 | */ | |
056834d9 | 1111 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, |
6cc55e09 | 1112 | unsigned int mss_now, gfp_t gfp) |
1da177e4 LT |
1113 | { |
1114 | struct tcp_sock *tp = tcp_sk(sk); | |
1115 | struct sk_buff *buff; | |
6475be16 | 1116 | int nsize, old_factor; |
b60b49ea | 1117 | int nlen; |
9ce01461 | 1118 | u8 flags; |
1da177e4 | 1119 | |
2fceec13 IJ |
1120 | if (WARN_ON(len > skb->len)) |
1121 | return -EINVAL; | |
6a438bbe | 1122 | |
1da177e4 LT |
1123 | nsize = skb_headlen(skb) - len; |
1124 | if (nsize < 0) | |
1125 | nsize = 0; | |
1126 | ||
6cc55e09 | 1127 | if (skb_unclone(skb, gfp)) |
1da177e4 LT |
1128 | return -ENOMEM; |
1129 | ||
1130 | /* Get a new skb... force flag on. */ | |
6cc55e09 | 1131 | buff = sk_stream_alloc_skb(sk, nsize, gfp); |
1da177e4 LT |
1132 | if (buff == NULL) |
1133 | return -ENOMEM; /* We'll just try again later. */ | |
ef5cb973 | 1134 | |
3ab224be HA |
1135 | sk->sk_wmem_queued += buff->truesize; |
1136 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea HX |
1137 | nlen = skb->len - len - nsize; |
1138 | buff->truesize += nlen; | |
1139 | skb->truesize -= nlen; | |
1da177e4 LT |
1140 | |
1141 | /* Correct the sequence numbers. */ | |
1142 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1143 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1144 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1145 | ||
1146 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1147 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1148 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1149 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
e14c3caf | 1150 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 | 1151 | |
84fa7933 | 1152 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { |
1da177e4 | 1153 | /* Copy and checksum data tail into the new buffer. */ |
056834d9 IJ |
1154 | buff->csum = csum_partial_copy_nocheck(skb->data + len, |
1155 | skb_put(buff, nsize), | |
1da177e4 LT |
1156 | nsize, 0); |
1157 | ||
1158 | skb_trim(skb, len); | |
1159 | ||
1160 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
1161 | } else { | |
84fa7933 | 1162 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1163 | skb_split(skb, buff, len); |
1164 | } | |
1165 | ||
1166 | buff->ip_summed = skb->ip_summed; | |
1167 | ||
a61bbcf2 | 1168 | buff->tstamp = skb->tstamp; |
490cc7d0 | 1169 | tcp_fragment_tstamp(skb, buff); |
1da177e4 | 1170 | |
6475be16 DM |
1171 | old_factor = tcp_skb_pcount(skb); |
1172 | ||
1da177e4 | 1173 | /* Fix up tso_factor for both original and new SKB. */ |
846998ae DM |
1174 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1175 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
1da177e4 | 1176 | |
6475be16 DM |
1177 | /* If this packet has been sent out already, we must |
1178 | * adjust the various packet counters. | |
1179 | */ | |
cf0b450c | 1180 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1181 | int diff = old_factor - tcp_skb_pcount(skb) - |
1182 | tcp_skb_pcount(buff); | |
1da177e4 | 1183 | |
797108d1 IJ |
1184 | if (diff) |
1185 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1186 | } |
1187 | ||
1188 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1189 | __skb_header_release(buff); |
fe067e8a | 1190 | tcp_insert_write_queue_after(skb, buff, sk); |
1da177e4 LT |
1191 | |
1192 | return 0; | |
1193 | } | |
1194 | ||
1195 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
1196 | * eventually). The difference is that pulled data not copied, but | |
1197 | * immediately discarded. | |
1198 | */ | |
f2911969 | 1199 | static void __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 | 1200 | { |
7b7fc97a | 1201 | struct skb_shared_info *shinfo; |
1da177e4 LT |
1202 | int i, k, eat; |
1203 | ||
4fa48bf3 ED |
1204 | eat = min_t(int, len, skb_headlen(skb)); |
1205 | if (eat) { | |
1206 | __skb_pull(skb, eat); | |
1207 | len -= eat; | |
1208 | if (!len) | |
1209 | return; | |
1210 | } | |
1da177e4 LT |
1211 | eat = len; |
1212 | k = 0; | |
7b7fc97a ED |
1213 | shinfo = skb_shinfo(skb); |
1214 | for (i = 0; i < shinfo->nr_frags; i++) { | |
1215 | int size = skb_frag_size(&shinfo->frags[i]); | |
9e903e08 ED |
1216 | |
1217 | if (size <= eat) { | |
aff65da0 | 1218 | skb_frag_unref(skb, i); |
9e903e08 | 1219 | eat -= size; |
1da177e4 | 1220 | } else { |
7b7fc97a | 1221 | shinfo->frags[k] = shinfo->frags[i]; |
1da177e4 | 1222 | if (eat) { |
7b7fc97a ED |
1223 | shinfo->frags[k].page_offset += eat; |
1224 | skb_frag_size_sub(&shinfo->frags[k], eat); | |
1da177e4 LT |
1225 | eat = 0; |
1226 | } | |
1227 | k++; | |
1228 | } | |
1229 | } | |
7b7fc97a | 1230 | shinfo->nr_frags = k; |
1da177e4 | 1231 | |
27a884dc | 1232 | skb_reset_tail_pointer(skb); |
1da177e4 LT |
1233 | skb->data_len -= len; |
1234 | skb->len = skb->data_len; | |
1da177e4 LT |
1235 | } |
1236 | ||
67edfef7 | 1237 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1238 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1239 | { | |
14bbd6a5 | 1240 | if (skb_unclone(skb, GFP_ATOMIC)) |
1da177e4 LT |
1241 | return -ENOMEM; |
1242 | ||
4fa48bf3 | 1243 | __pskb_trim_head(skb, len); |
1da177e4 LT |
1244 | |
1245 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 1246 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1247 | |
1248 | skb->truesize -= len; | |
1249 | sk->sk_wmem_queued -= len; | |
3ab224be | 1250 | sk_mem_uncharge(sk, len); |
1da177e4 LT |
1251 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); |
1252 | ||
5b35e1e6 | 1253 | /* Any change of skb->len requires recalculation of tso factor. */ |
1da177e4 | 1254 | if (tcp_skb_pcount(skb) > 1) |
5b35e1e6 | 1255 | tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); |
1da177e4 LT |
1256 | |
1257 | return 0; | |
1258 | } | |
1259 | ||
1b63edd6 YC |
1260 | /* Calculate MSS not accounting any TCP options. */ |
1261 | static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
5d424d5a | 1262 | { |
cf533ea5 ED |
1263 | const struct tcp_sock *tp = tcp_sk(sk); |
1264 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1265 | int mss_now; |
1266 | ||
1267 | /* Calculate base mss without TCP options: | |
1268 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1269 | */ | |
1270 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1271 | ||
67469601 ED |
1272 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1273 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1274 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1275 | ||
1276 | if (dst && dst_allfrag(dst)) | |
1277 | mss_now -= icsk->icsk_af_ops->net_frag_header_len; | |
1278 | } | |
1279 | ||
5d424d5a JH |
1280 | /* Clamp it (mss_clamp does not include tcp options) */ |
1281 | if (mss_now > tp->rx_opt.mss_clamp) | |
1282 | mss_now = tp->rx_opt.mss_clamp; | |
1283 | ||
1284 | /* Now subtract optional transport overhead */ | |
1285 | mss_now -= icsk->icsk_ext_hdr_len; | |
1286 | ||
1287 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
1288 | if (mss_now < 48) | |
1289 | mss_now = 48; | |
5d424d5a JH |
1290 | return mss_now; |
1291 | } | |
1292 | ||
1b63edd6 YC |
1293 | /* Calculate MSS. Not accounting for SACKs here. */ |
1294 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
1295 | { | |
1296 | /* Subtract TCP options size, not including SACKs */ | |
1297 | return __tcp_mtu_to_mss(sk, pmtu) - | |
1298 | (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); | |
1299 | } | |
1300 | ||
5d424d5a | 1301 | /* Inverse of above */ |
67469601 | 1302 | int tcp_mss_to_mtu(struct sock *sk, int mss) |
5d424d5a | 1303 | { |
cf533ea5 ED |
1304 | const struct tcp_sock *tp = tcp_sk(sk); |
1305 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1306 | int mtu; |
1307 | ||
1308 | mtu = mss + | |
1309 | tp->tcp_header_len + | |
1310 | icsk->icsk_ext_hdr_len + | |
1311 | icsk->icsk_af_ops->net_header_len; | |
1312 | ||
67469601 ED |
1313 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1314 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1315 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1316 | ||
1317 | if (dst && dst_allfrag(dst)) | |
1318 | mtu += icsk->icsk_af_ops->net_frag_header_len; | |
1319 | } | |
5d424d5a JH |
1320 | return mtu; |
1321 | } | |
1322 | ||
67edfef7 | 1323 | /* MTU probing init per socket */ |
5d424d5a JH |
1324 | void tcp_mtup_init(struct sock *sk) |
1325 | { | |
1326 | struct tcp_sock *tp = tcp_sk(sk); | |
1327 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1328 | ||
1329 | icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; | |
1330 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + | |
e905a9ed | 1331 | icsk->icsk_af_ops->net_header_len; |
5d424d5a JH |
1332 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); |
1333 | icsk->icsk_mtup.probe_size = 0; | |
1334 | } | |
4bc2f18b | 1335 | EXPORT_SYMBOL(tcp_mtup_init); |
5d424d5a | 1336 | |
1da177e4 LT |
1337 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1338 | ||
1339 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1340 | for TCP options, but includes only bare TCP header. | |
1341 | ||
1342 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1343 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1344 | It also does not include TCP options. |
1345 | ||
d83d8461 | 1346 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1347 | |
1348 | tp->mss_cache is current effective sending mss, including | |
1349 | all tcp options except for SACKs. It is evaluated, | |
1350 | taking into account current pmtu, but never exceeds | |
1351 | tp->rx_opt.mss_clamp. | |
1352 | ||
1353 | NOTE1. rfc1122 clearly states that advertised MSS | |
1354 | DOES NOT include either tcp or ip options. | |
1355 | ||
d83d8461 ACM |
1356 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1357 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1358 | */ |
1da177e4 LT |
1359 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1360 | { | |
1361 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1362 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1363 | int mss_now; |
1da177e4 | 1364 | |
5d424d5a JH |
1365 | if (icsk->icsk_mtup.search_high > pmtu) |
1366 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1367 | |
5d424d5a | 1368 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1369 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1370 | |
1371 | /* And store cached results */ | |
d83d8461 | 1372 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1373 | if (icsk->icsk_mtup.enabled) |
1374 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1375 | tp->mss_cache = mss_now; |
1da177e4 LT |
1376 | |
1377 | return mss_now; | |
1378 | } | |
4bc2f18b | 1379 | EXPORT_SYMBOL(tcp_sync_mss); |
1da177e4 LT |
1380 | |
1381 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1382 | * and even PMTU discovery events into account. | |
1da177e4 | 1383 | */ |
0c54b85f | 1384 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 | 1385 | { |
cf533ea5 ED |
1386 | const struct tcp_sock *tp = tcp_sk(sk); |
1387 | const struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1388 | u32 mss_now; |
95c96174 | 1389 | unsigned int header_len; |
33ad798c AL |
1390 | struct tcp_out_options opts; |
1391 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1392 | |
1393 | mss_now = tp->mss_cache; | |
1394 | ||
1da177e4 LT |
1395 | if (dst) { |
1396 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1397 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1398 | mss_now = tcp_sync_mss(sk, mtu); |
1399 | } | |
1400 | ||
33ad798c AL |
1401 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1402 | sizeof(struct tcphdr); | |
1403 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1404 | * some common options. If this is an odd packet (because we have SACK | |
1405 | * blocks etc) then our calculated header_len will be different, and | |
1406 | * we have to adjust mss_now correspondingly */ | |
1407 | if (header_len != tp->tcp_header_len) { | |
1408 | int delta = (int) header_len - tp->tcp_header_len; | |
1409 | mss_now -= delta; | |
1410 | } | |
cfb6eeb4 | 1411 | |
1da177e4 LT |
1412 | return mss_now; |
1413 | } | |
1414 | ||
86fd14ad WP |
1415 | /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. |
1416 | * As additional protections, we do not touch cwnd in retransmission phases, | |
1417 | * and if application hit its sndbuf limit recently. | |
1418 | */ | |
1419 | static void tcp_cwnd_application_limited(struct sock *sk) | |
1420 | { | |
1421 | struct tcp_sock *tp = tcp_sk(sk); | |
1422 | ||
1423 | if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && | |
1424 | sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { | |
1425 | /* Limited by application or receiver window. */ | |
1426 | u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); | |
1427 | u32 win_used = max(tp->snd_cwnd_used, init_win); | |
1428 | if (win_used < tp->snd_cwnd) { | |
1429 | tp->snd_ssthresh = tcp_current_ssthresh(sk); | |
1430 | tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; | |
1431 | } | |
1432 | tp->snd_cwnd_used = 0; | |
1433 | } | |
1434 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1435 | } | |
1436 | ||
ca8a2263 | 1437 | static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) |
a762a980 | 1438 | { |
9e412ba7 | 1439 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1440 | |
ca8a2263 NC |
1441 | /* Track the maximum number of outstanding packets in each |
1442 | * window, and remember whether we were cwnd-limited then. | |
1443 | */ | |
1444 | if (!before(tp->snd_una, tp->max_packets_seq) || | |
1445 | tp->packets_out > tp->max_packets_out) { | |
1446 | tp->max_packets_out = tp->packets_out; | |
1447 | tp->max_packets_seq = tp->snd_nxt; | |
1448 | tp->is_cwnd_limited = is_cwnd_limited; | |
1449 | } | |
e114a710 | 1450 | |
24901551 | 1451 | if (tcp_is_cwnd_limited(sk)) { |
a762a980 DM |
1452 | /* Network is feed fully. */ |
1453 | tp->snd_cwnd_used = 0; | |
1454 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1455 | } else { | |
1456 | /* Network starves. */ | |
1457 | if (tp->packets_out > tp->snd_cwnd_used) | |
1458 | tp->snd_cwnd_used = tp->packets_out; | |
1459 | ||
15d33c07 DM |
1460 | if (sysctl_tcp_slow_start_after_idle && |
1461 | (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) | |
a762a980 DM |
1462 | tcp_cwnd_application_limited(sk); |
1463 | } | |
1464 | } | |
1465 | ||
d4589926 ED |
1466 | /* Minshall's variant of the Nagle send check. */ |
1467 | static bool tcp_minshall_check(const struct tcp_sock *tp) | |
1468 | { | |
1469 | return after(tp->snd_sml, tp->snd_una) && | |
1470 | !after(tp->snd_sml, tp->snd_nxt); | |
1471 | } | |
1472 | ||
1473 | /* Update snd_sml if this skb is under mss | |
1474 | * Note that a TSO packet might end with a sub-mss segment | |
1475 | * The test is really : | |
1476 | * if ((skb->len % mss) != 0) | |
1477 | * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1478 | * But we can avoid doing the divide again given we already have | |
1479 | * skb_pcount = skb->len / mss_now | |
0e3a4803 | 1480 | */ |
d4589926 ED |
1481 | static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
1482 | const struct sk_buff *skb) | |
1483 | { | |
1484 | if (skb->len < tcp_skb_pcount(skb) * mss_now) | |
1485 | tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1486 | } | |
1487 | ||
1488 | /* Return false, if packet can be sent now without violation Nagle's rules: | |
1489 | * 1. It is full sized. (provided by caller in %partial bool) | |
1490 | * 2. Or it contains FIN. (already checked by caller) | |
1491 | * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. | |
1492 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
1493 | * With Minshall's modification: all sent small packets are ACKed. | |
1494 | */ | |
1495 | static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, | |
cc93fc51 | 1496 | int nonagle) |
d4589926 ED |
1497 | { |
1498 | return partial && | |
1499 | ((nonagle & TCP_NAGLE_CORK) || | |
1500 | (!nonagle && tp->packets_out && tcp_minshall_check(tp))); | |
1501 | } | |
1502 | /* Returns the portion of skb which can be sent right away */ | |
1503 | static unsigned int tcp_mss_split_point(const struct sock *sk, | |
1504 | const struct sk_buff *skb, | |
1505 | unsigned int mss_now, | |
1506 | unsigned int max_segs, | |
1507 | int nonagle) | |
c1b4a7e6 | 1508 | { |
cf533ea5 | 1509 | const struct tcp_sock *tp = tcp_sk(sk); |
d4589926 | 1510 | u32 partial, needed, window, max_len; |
c1b4a7e6 | 1511 | |
90840def | 1512 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
1485348d | 1513 | max_len = mss_now * max_segs; |
0e3a4803 | 1514 | |
1485348d BH |
1515 | if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
1516 | return max_len; | |
0e3a4803 | 1517 | |
5ea3a748 IJ |
1518 | needed = min(skb->len, window); |
1519 | ||
1485348d BH |
1520 | if (max_len <= needed) |
1521 | return max_len; | |
0e3a4803 | 1522 | |
d4589926 ED |
1523 | partial = needed % mss_now; |
1524 | /* If last segment is not a full MSS, check if Nagle rules allow us | |
1525 | * to include this last segment in this skb. | |
1526 | * Otherwise, we'll split the skb at last MSS boundary | |
1527 | */ | |
cc93fc51 | 1528 | if (tcp_nagle_check(partial != 0, tp, nonagle)) |
d4589926 ED |
1529 | return needed - partial; |
1530 | ||
1531 | return needed; | |
c1b4a7e6 DM |
1532 | } |
1533 | ||
1534 | /* Can at least one segment of SKB be sent right now, according to the | |
1535 | * congestion window rules? If so, return how many segments are allowed. | |
1536 | */ | |
cf533ea5 ED |
1537 | static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
1538 | const struct sk_buff *skb) | |
c1b4a7e6 DM |
1539 | { |
1540 | u32 in_flight, cwnd; | |
1541 | ||
1542 | /* Don't be strict about the congestion window for the final FIN. */ | |
4de075e0 ED |
1543 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
1544 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
1545 | return 1; |
1546 | ||
1547 | in_flight = tcp_packets_in_flight(tp); | |
1548 | cwnd = tp->snd_cwnd; | |
1549 | if (in_flight < cwnd) | |
1550 | return (cwnd - in_flight); | |
1551 | ||
1552 | return 0; | |
1553 | } | |
1554 | ||
b595076a | 1555 | /* Initialize TSO state of a skb. |
67edfef7 | 1556 | * This must be invoked the first time we consider transmitting |
c1b4a7e6 DM |
1557 | * SKB onto the wire. |
1558 | */ | |
cf533ea5 | 1559 | static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, |
056834d9 | 1560 | unsigned int mss_now) |
c1b4a7e6 DM |
1561 | { |
1562 | int tso_segs = tcp_skb_pcount(skb); | |
1563 | ||
f8269a49 | 1564 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
846998ae | 1565 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
1566 | tso_segs = tcp_skb_pcount(skb); |
1567 | } | |
1568 | return tso_segs; | |
1569 | } | |
1570 | ||
c1b4a7e6 | 1571 | |
a2a385d6 | 1572 | /* Return true if the Nagle test allows this packet to be |
c1b4a7e6 DM |
1573 | * sent now. |
1574 | */ | |
a2a385d6 ED |
1575 | static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
1576 | unsigned int cur_mss, int nonagle) | |
c1b4a7e6 DM |
1577 | { |
1578 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
1579 | * write_queue (they have no chances to get new data). | |
1580 | * | |
1581 | * This is implemented in the callers, where they modify the 'nonagle' | |
1582 | * argument based upon the location of SKB in the send queue. | |
1583 | */ | |
1584 | if (nonagle & TCP_NAGLE_PUSH) | |
a2a385d6 | 1585 | return true; |
c1b4a7e6 | 1586 | |
9b44190d YC |
1587 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
1588 | if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) | |
a2a385d6 | 1589 | return true; |
c1b4a7e6 | 1590 | |
cc93fc51 | 1591 | if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) |
a2a385d6 | 1592 | return true; |
c1b4a7e6 | 1593 | |
a2a385d6 | 1594 | return false; |
c1b4a7e6 DM |
1595 | } |
1596 | ||
1597 | /* Does at least the first segment of SKB fit into the send window? */ | |
a2a385d6 ED |
1598 | static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
1599 | const struct sk_buff *skb, | |
1600 | unsigned int cur_mss) | |
c1b4a7e6 DM |
1601 | { |
1602 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
1603 | ||
1604 | if (skb->len > cur_mss) | |
1605 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
1606 | ||
90840def | 1607 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
1608 | } |
1609 | ||
fe067e8a | 1610 | /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) |
c1b4a7e6 DM |
1611 | * should be put on the wire right now. If so, it returns the number of |
1612 | * packets allowed by the congestion window. | |
1613 | */ | |
cf533ea5 | 1614 | static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, |
c1b4a7e6 DM |
1615 | unsigned int cur_mss, int nonagle) |
1616 | { | |
cf533ea5 | 1617 | const struct tcp_sock *tp = tcp_sk(sk); |
c1b4a7e6 DM |
1618 | unsigned int cwnd_quota; |
1619 | ||
846998ae | 1620 | tcp_init_tso_segs(sk, skb, cur_mss); |
c1b4a7e6 DM |
1621 | |
1622 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
1623 | return 0; | |
1624 | ||
1625 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
056834d9 | 1626 | if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) |
c1b4a7e6 DM |
1627 | cwnd_quota = 0; |
1628 | ||
1629 | return cwnd_quota; | |
1630 | } | |
1631 | ||
67edfef7 | 1632 | /* Test if sending is allowed right now. */ |
a2a385d6 | 1633 | bool tcp_may_send_now(struct sock *sk) |
c1b4a7e6 | 1634 | { |
cf533ea5 | 1635 | const struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 1636 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 | 1637 | |
a02cec21 | 1638 | return skb && |
0c54b85f | 1639 | tcp_snd_test(sk, skb, tcp_current_mss(sk), |
c1b4a7e6 | 1640 | (tcp_skb_is_last(sk, skb) ? |
a02cec21 | 1641 | tp->nonagle : TCP_NAGLE_PUSH)); |
c1b4a7e6 DM |
1642 | } |
1643 | ||
1644 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet | |
1645 | * which is put after SKB on the list. It is very much like | |
1646 | * tcp_fragment() except that it may make several kinds of assumptions | |
1647 | * in order to speed up the splitting operation. In particular, we | |
1648 | * know that all the data is in scatter-gather pages, and that the | |
1649 | * packet has never been sent out before (and thus is not cloned). | |
1650 | */ | |
056834d9 | 1651 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
c4ead4c5 | 1652 | unsigned int mss_now, gfp_t gfp) |
c1b4a7e6 DM |
1653 | { |
1654 | struct sk_buff *buff; | |
1655 | int nlen = skb->len - len; | |
9ce01461 | 1656 | u8 flags; |
c1b4a7e6 DM |
1657 | |
1658 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 | 1659 | if (skb->len != skb->data_len) |
6cc55e09 | 1660 | return tcp_fragment(sk, skb, len, mss_now, gfp); |
c1b4a7e6 | 1661 | |
c4ead4c5 | 1662 | buff = sk_stream_alloc_skb(sk, 0, gfp); |
c1b4a7e6 DM |
1663 | if (unlikely(buff == NULL)) |
1664 | return -ENOMEM; | |
1665 | ||
3ab224be HA |
1666 | sk->sk_wmem_queued += buff->truesize; |
1667 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea | 1668 | buff->truesize += nlen; |
c1b4a7e6 DM |
1669 | skb->truesize -= nlen; |
1670 | ||
1671 | /* Correct the sequence numbers. */ | |
1672 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1673 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1674 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1675 | ||
1676 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1677 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1678 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1679 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
c1b4a7e6 DM |
1680 | |
1681 | /* This packet was never sent out yet, so no SACK bits. */ | |
1682 | TCP_SKB_CB(buff)->sacked = 0; | |
1683 | ||
84fa7933 | 1684 | buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; |
c1b4a7e6 | 1685 | skb_split(skb, buff, len); |
490cc7d0 | 1686 | tcp_fragment_tstamp(skb, buff); |
c1b4a7e6 DM |
1687 | |
1688 | /* Fix up tso_factor for both original and new SKB. */ | |
846998ae DM |
1689 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1690 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
c1b4a7e6 DM |
1691 | |
1692 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1693 | __skb_header_release(buff); |
fe067e8a | 1694 | tcp_insert_write_queue_after(skb, buff, sk); |
c1b4a7e6 DM |
1695 | |
1696 | return 0; | |
1697 | } | |
1698 | ||
1699 | /* Try to defer sending, if possible, in order to minimize the amount | |
1700 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1701 | * | |
1702 | * This algorithm is from John Heffner. | |
1703 | */ | |
ca8a2263 NC |
1704 | static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, |
1705 | bool *is_cwnd_limited) | |
c1b4a7e6 | 1706 | { |
9e412ba7 | 1707 | struct tcp_sock *tp = tcp_sk(sk); |
6687e988 | 1708 | const struct inet_connection_sock *icsk = inet_csk(sk); |
c1b4a7e6 | 1709 | u32 send_win, cong_win, limit, in_flight; |
ad9f4f50 | 1710 | int win_divisor; |
c1b4a7e6 | 1711 | |
4de075e0 | 1712 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) |
ae8064ac | 1713 | goto send_now; |
c1b4a7e6 | 1714 | |
6687e988 | 1715 | if (icsk->icsk_ca_state != TCP_CA_Open) |
ae8064ac JH |
1716 | goto send_now; |
1717 | ||
1718 | /* Defer for less than two clock ticks. */ | |
bd515c3e | 1719 | if (tp->tso_deferred && |
a2acde07 | 1720 | (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) |
ae8064ac | 1721 | goto send_now; |
908a75c1 | 1722 | |
c1b4a7e6 DM |
1723 | in_flight = tcp_packets_in_flight(tp); |
1724 | ||
056834d9 | 1725 | BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); |
c1b4a7e6 | 1726 | |
90840def | 1727 | send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 DM |
1728 | |
1729 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1730 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1731 | ||
1732 | limit = min(send_win, cong_win); | |
1733 | ||
ba244fe9 | 1734 | /* If a full-sized TSO skb can be sent, do it. */ |
1485348d | 1735 | if (limit >= min_t(unsigned int, sk->sk_gso_max_size, |
95bd09eb | 1736 | tp->xmit_size_goal_segs * tp->mss_cache)) |
ae8064ac | 1737 | goto send_now; |
ba244fe9 | 1738 | |
62ad2761 IJ |
1739 | /* Middle in queue won't get any more data, full sendable already? */ |
1740 | if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) | |
1741 | goto send_now; | |
1742 | ||
ad9f4f50 ED |
1743 | win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); |
1744 | if (win_divisor) { | |
c1b4a7e6 DM |
1745 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
1746 | ||
1747 | /* If at least some fraction of a window is available, | |
1748 | * just use it. | |
1749 | */ | |
ad9f4f50 | 1750 | chunk /= win_divisor; |
c1b4a7e6 | 1751 | if (limit >= chunk) |
ae8064ac | 1752 | goto send_now; |
c1b4a7e6 DM |
1753 | } else { |
1754 | /* Different approach, try not to defer past a single | |
1755 | * ACK. Receiver should ACK every other full sized | |
1756 | * frame, so if we have space for more than 3 frames | |
1757 | * then send now. | |
1758 | */ | |
6b5a5c0d | 1759 | if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
ae8064ac | 1760 | goto send_now; |
c1b4a7e6 DM |
1761 | } |
1762 | ||
f4541d60 ED |
1763 | /* Ok, it looks like it is advisable to defer. |
1764 | * Do not rearm the timer if already set to not break TCP ACK clocking. | |
1765 | */ | |
1766 | if (!tp->tso_deferred) | |
1767 | tp->tso_deferred = 1 | (jiffies << 1); | |
ae8064ac | 1768 | |
ca8a2263 NC |
1769 | if (cong_win < send_win && cong_win < skb->len) |
1770 | *is_cwnd_limited = true; | |
1771 | ||
a2a385d6 | 1772 | return true; |
ae8064ac JH |
1773 | |
1774 | send_now: | |
1775 | tp->tso_deferred = 0; | |
a2a385d6 | 1776 | return false; |
c1b4a7e6 DM |
1777 | } |
1778 | ||
5d424d5a | 1779 | /* Create a new MTU probe if we are ready. |
67edfef7 AK |
1780 | * MTU probe is regularly attempting to increase the path MTU by |
1781 | * deliberately sending larger packets. This discovers routing | |
1782 | * changes resulting in larger path MTUs. | |
1783 | * | |
5d424d5a JH |
1784 | * Returns 0 if we should wait to probe (no cwnd available), |
1785 | * 1 if a probe was sent, | |
056834d9 IJ |
1786 | * -1 otherwise |
1787 | */ | |
5d424d5a JH |
1788 | static int tcp_mtu_probe(struct sock *sk) |
1789 | { | |
1790 | struct tcp_sock *tp = tcp_sk(sk); | |
1791 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1792 | struct sk_buff *skb, *nskb, *next; | |
1793 | int len; | |
1794 | int probe_size; | |
91cc17c0 | 1795 | int size_needed; |
5d424d5a JH |
1796 | int copy; |
1797 | int mss_now; | |
1798 | ||
1799 | /* Not currently probing/verifying, | |
1800 | * not in recovery, | |
1801 | * have enough cwnd, and | |
1802 | * not SACKing (the variable headers throw things off) */ | |
1803 | if (!icsk->icsk_mtup.enabled || | |
1804 | icsk->icsk_mtup.probe_size || | |
1805 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
1806 | tp->snd_cwnd < 11 || | |
cabeccbd | 1807 | tp->rx_opt.num_sacks || tp->rx_opt.dsack) |
5d424d5a JH |
1808 | return -1; |
1809 | ||
1810 | /* Very simple search strategy: just double the MSS. */ | |
0c54b85f | 1811 | mss_now = tcp_current_mss(sk); |
056834d9 | 1812 | probe_size = 2 * tp->mss_cache; |
91cc17c0 | 1813 | size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
5d424d5a JH |
1814 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { |
1815 | /* TODO: set timer for probe_converge_event */ | |
1816 | return -1; | |
1817 | } | |
1818 | ||
1819 | /* Have enough data in the send queue to probe? */ | |
7f9c33e5 | 1820 | if (tp->write_seq - tp->snd_nxt < size_needed) |
5d424d5a JH |
1821 | return -1; |
1822 | ||
91cc17c0 IJ |
1823 | if (tp->snd_wnd < size_needed) |
1824 | return -1; | |
90840def | 1825 | if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
91cc17c0 | 1826 | return 0; |
5d424d5a | 1827 | |
d67c58e9 IJ |
1828 | /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
1829 | if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { | |
1830 | if (!tcp_packets_in_flight(tp)) | |
5d424d5a JH |
1831 | return -1; |
1832 | else | |
1833 | return 0; | |
1834 | } | |
1835 | ||
1836 | /* We're allowed to probe. Build it now. */ | |
1837 | if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) | |
1838 | return -1; | |
3ab224be HA |
1839 | sk->sk_wmem_queued += nskb->truesize; |
1840 | sk_mem_charge(sk, nskb->truesize); | |
5d424d5a | 1841 | |
fe067e8a | 1842 | skb = tcp_send_head(sk); |
5d424d5a JH |
1843 | |
1844 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
1845 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
4de075e0 | 1846 | TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
5d424d5a JH |
1847 | TCP_SKB_CB(nskb)->sacked = 0; |
1848 | nskb->csum = 0; | |
84fa7933 | 1849 | nskb->ip_summed = skb->ip_summed; |
5d424d5a | 1850 | |
50c4817e IJ |
1851 | tcp_insert_write_queue_before(nskb, skb, sk); |
1852 | ||
5d424d5a | 1853 | len = 0; |
234b6860 | 1854 | tcp_for_write_queue_from_safe(skb, next, sk) { |
5d424d5a JH |
1855 | copy = min_t(int, skb->len, probe_size - len); |
1856 | if (nskb->ip_summed) | |
1857 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); | |
1858 | else | |
1859 | nskb->csum = skb_copy_and_csum_bits(skb, 0, | |
056834d9 IJ |
1860 | skb_put(nskb, copy), |
1861 | copy, nskb->csum); | |
5d424d5a JH |
1862 | |
1863 | if (skb->len <= copy) { | |
1864 | /* We've eaten all the data from this skb. | |
1865 | * Throw it away. */ | |
4de075e0 | 1866 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
fe067e8a | 1867 | tcp_unlink_write_queue(skb, sk); |
3ab224be | 1868 | sk_wmem_free_skb(sk, skb); |
5d424d5a | 1869 | } else { |
4de075e0 | 1870 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
a3433f35 | 1871 | ~(TCPHDR_FIN|TCPHDR_PSH); |
5d424d5a JH |
1872 | if (!skb_shinfo(skb)->nr_frags) { |
1873 | skb_pull(skb, copy); | |
84fa7933 | 1874 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
056834d9 IJ |
1875 | skb->csum = csum_partial(skb->data, |
1876 | skb->len, 0); | |
5d424d5a JH |
1877 | } else { |
1878 | __pskb_trim_head(skb, copy); | |
1879 | tcp_set_skb_tso_segs(sk, skb, mss_now); | |
1880 | } | |
1881 | TCP_SKB_CB(skb)->seq += copy; | |
1882 | } | |
1883 | ||
1884 | len += copy; | |
234b6860 IJ |
1885 | |
1886 | if (len >= probe_size) | |
1887 | break; | |
5d424d5a JH |
1888 | } |
1889 | tcp_init_tso_segs(sk, nskb, nskb->len); | |
1890 | ||
1891 | /* We're ready to send. If this fails, the probe will | |
7faee5c0 ED |
1892 | * be resegmented into mss-sized pieces by tcp_write_xmit(). |
1893 | */ | |
5d424d5a JH |
1894 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { |
1895 | /* Decrement cwnd here because we are sending | |
056834d9 | 1896 | * effectively two packets. */ |
5d424d5a | 1897 | tp->snd_cwnd--; |
66f5fe62 | 1898 | tcp_event_new_data_sent(sk, nskb); |
5d424d5a JH |
1899 | |
1900 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
1901 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
1902 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
1903 | |
1904 | return 1; | |
1905 | } | |
1906 | ||
1907 | return -1; | |
1908 | } | |
1909 | ||
1da177e4 LT |
1910 | /* This routine writes packets to the network. It advances the |
1911 | * send_head. This happens as incoming acks open up the remote | |
1912 | * window for us. | |
1913 | * | |
f8269a49 IJ |
1914 | * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
1915 | * snd_up-64k-mss .. snd_up cannot be large. However, taking into | |
1916 | * account rare use of URG, this is not a big flaw. | |
1917 | * | |
6ba8a3b1 ND |
1918 | * Send at most one packet when push_one > 0. Temporarily ignore |
1919 | * cwnd limit to force at most one packet out when push_one == 2. | |
1920 | ||
a2a385d6 ED |
1921 | * Returns true, if no segments are in flight and we have queued segments, |
1922 | * but cannot send anything now because of SWS or another problem. | |
1da177e4 | 1923 | */ |
a2a385d6 ED |
1924 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
1925 | int push_one, gfp_t gfp) | |
1da177e4 LT |
1926 | { |
1927 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 1928 | struct sk_buff *skb; |
c1b4a7e6 DM |
1929 | unsigned int tso_segs, sent_pkts; |
1930 | int cwnd_quota; | |
5d424d5a | 1931 | int result; |
ca8a2263 | 1932 | bool is_cwnd_limited = false; |
1da177e4 | 1933 | |
92df7b51 | 1934 | sent_pkts = 0; |
5d424d5a | 1935 | |
d5dd9175 IJ |
1936 | if (!push_one) { |
1937 | /* Do MTU probing. */ | |
1938 | result = tcp_mtu_probe(sk); | |
1939 | if (!result) { | |
a2a385d6 | 1940 | return false; |
d5dd9175 IJ |
1941 | } else if (result > 0) { |
1942 | sent_pkts = 1; | |
1943 | } | |
5d424d5a JH |
1944 | } |
1945 | ||
fe067e8a | 1946 | while ((skb = tcp_send_head(sk))) { |
c8ac3774 HX |
1947 | unsigned int limit; |
1948 | ||
b68e9f85 | 1949 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 | 1950 | BUG_ON(!tso_segs); |
aa93466b | 1951 | |
9d186cac | 1952 | if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { |
7faee5c0 ED |
1953 | /* "skb_mstamp" is used as a start point for the retransmit timer */ |
1954 | skb_mstamp_get(&skb->skb_mstamp); | |
ec342325 | 1955 | goto repair; /* Skip network transmission */ |
9d186cac | 1956 | } |
ec342325 | 1957 | |
b68e9f85 | 1958 | cwnd_quota = tcp_cwnd_test(tp, skb); |
6ba8a3b1 | 1959 | if (!cwnd_quota) { |
ca8a2263 | 1960 | is_cwnd_limited = true; |
6ba8a3b1 ND |
1961 | if (push_one == 2) |
1962 | /* Force out a loss probe pkt. */ | |
1963 | cwnd_quota = 1; | |
1964 | else | |
1965 | break; | |
1966 | } | |
b68e9f85 HX |
1967 | |
1968 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) | |
1969 | break; | |
1970 | ||
c1b4a7e6 DM |
1971 | if (tso_segs == 1) { |
1972 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, | |
1973 | (tcp_skb_is_last(sk, skb) ? | |
1974 | nonagle : TCP_NAGLE_PUSH)))) | |
1975 | break; | |
1976 | } else { | |
ca8a2263 NC |
1977 | if (!push_one && |
1978 | tcp_tso_should_defer(sk, skb, &is_cwnd_limited)) | |
c1b4a7e6 DM |
1979 | break; |
1980 | } | |
aa93466b | 1981 | |
c9eeec26 ED |
1982 | /* TCP Small Queues : |
1983 | * Control number of packets in qdisc/devices to two packets / or ~1 ms. | |
1984 | * This allows for : | |
1985 | * - better RTT estimation and ACK scheduling | |
1986 | * - faster recovery | |
1987 | * - high rates | |
98e09386 ED |
1988 | * Alas, some drivers / subsystems require a fair amount |
1989 | * of queued bytes to ensure line rate. | |
1990 | * One example is wifi aggregation (802.11 AMPDU) | |
46d3ceab | 1991 | */ |
98e09386 ED |
1992 | limit = max_t(unsigned int, sysctl_tcp_limit_output_bytes, |
1993 | sk->sk_pacing_rate >> 10); | |
c9eeec26 ED |
1994 | |
1995 | if (atomic_read(&sk->sk_wmem_alloc) > limit) { | |
46d3ceab | 1996 | set_bit(TSQ_THROTTLED, &tp->tsq_flags); |
bf06200e JO |
1997 | /* It is possible TX completion already happened |
1998 | * before we set TSQ_THROTTLED, so we must | |
1999 | * test again the condition. | |
bf06200e | 2000 | */ |
4e857c58 | 2001 | smp_mb__after_atomic(); |
bf06200e JO |
2002 | if (atomic_read(&sk->sk_wmem_alloc) > limit) |
2003 | break; | |
46d3ceab | 2004 | } |
c9eeec26 | 2005 | |
c8ac3774 | 2006 | limit = mss_now; |
f8269a49 | 2007 | if (tso_segs > 1 && !tcp_urg_mode(tp)) |
0e3a4803 | 2008 | limit = tcp_mss_split_point(sk, skb, mss_now, |
1485348d BH |
2009 | min_t(unsigned int, |
2010 | cwnd_quota, | |
d4589926 ED |
2011 | sk->sk_gso_max_segs), |
2012 | nonagle); | |
1da177e4 | 2013 | |
c8ac3774 | 2014 | if (skb->len > limit && |
c4ead4c5 | 2015 | unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) |
c8ac3774 HX |
2016 | break; |
2017 | ||
d5dd9175 | 2018 | if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
92df7b51 | 2019 | break; |
1da177e4 | 2020 | |
ec342325 | 2021 | repair: |
92df7b51 DM |
2022 | /* Advance the send_head. This one is sent out. |
2023 | * This call will increment packets_out. | |
2024 | */ | |
66f5fe62 | 2025 | tcp_event_new_data_sent(sk, skb); |
1da177e4 | 2026 | |
92df7b51 | 2027 | tcp_minshall_update(tp, mss_now, skb); |
a262f0cd | 2028 | sent_pkts += tcp_skb_pcount(skb); |
d5dd9175 IJ |
2029 | |
2030 | if (push_one) | |
2031 | break; | |
92df7b51 | 2032 | } |
1da177e4 | 2033 | |
aa93466b | 2034 | if (likely(sent_pkts)) { |
684bad11 YC |
2035 | if (tcp_in_cwnd_reduction(sk)) |
2036 | tp->prr_out += sent_pkts; | |
6ba8a3b1 ND |
2037 | |
2038 | /* Send one loss probe per tail loss episode. */ | |
2039 | if (push_one != 2) | |
2040 | tcp_schedule_loss_probe(sk); | |
ca8a2263 | 2041 | tcp_cwnd_validate(sk, is_cwnd_limited); |
a2a385d6 | 2042 | return false; |
1da177e4 | 2043 | } |
6ba8a3b1 ND |
2044 | return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); |
2045 | } | |
2046 | ||
2047 | bool tcp_schedule_loss_probe(struct sock *sk) | |
2048 | { | |
2049 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2050 | struct tcp_sock *tp = tcp_sk(sk); | |
2051 | u32 timeout, tlp_time_stamp, rto_time_stamp; | |
740b0f18 | 2052 | u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3); |
6ba8a3b1 ND |
2053 | |
2054 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) | |
2055 | return false; | |
2056 | /* No consecutive loss probes. */ | |
2057 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { | |
2058 | tcp_rearm_rto(sk); | |
2059 | return false; | |
2060 | } | |
2061 | /* Don't do any loss probe on a Fast Open connection before 3WHS | |
2062 | * finishes. | |
2063 | */ | |
2064 | if (sk->sk_state == TCP_SYN_RECV) | |
2065 | return false; | |
2066 | ||
2067 | /* TLP is only scheduled when next timer event is RTO. */ | |
2068 | if (icsk->icsk_pending != ICSK_TIME_RETRANS) | |
2069 | return false; | |
2070 | ||
2071 | /* Schedule a loss probe in 2*RTT for SACK capable connections | |
2072 | * in Open state, that are either limited by cwnd or application. | |
2073 | */ | |
740b0f18 | 2074 | if (sysctl_tcp_early_retrans < 3 || !tp->srtt_us || !tp->packets_out || |
6ba8a3b1 ND |
2075 | !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) |
2076 | return false; | |
2077 | ||
2078 | if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && | |
2079 | tcp_send_head(sk)) | |
2080 | return false; | |
2081 | ||
2082 | /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account | |
2083 | * for delayed ack when there's one outstanding packet. | |
2084 | */ | |
2085 | timeout = rtt << 1; | |
2086 | if (tp->packets_out == 1) | |
2087 | timeout = max_t(u32, timeout, | |
2088 | (rtt + (rtt >> 1) + TCP_DELACK_MAX)); | |
2089 | timeout = max_t(u32, timeout, msecs_to_jiffies(10)); | |
2090 | ||
2091 | /* If RTO is shorter, just schedule TLP in its place. */ | |
2092 | tlp_time_stamp = tcp_time_stamp + timeout; | |
2093 | rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; | |
2094 | if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { | |
2095 | s32 delta = rto_time_stamp - tcp_time_stamp; | |
2096 | if (delta > 0) | |
2097 | timeout = delta; | |
2098 | } | |
2099 | ||
2100 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, | |
2101 | TCP_RTO_MAX); | |
2102 | return true; | |
2103 | } | |
2104 | ||
1f3279ae ED |
2105 | /* Thanks to skb fast clones, we can detect if a prior transmit of |
2106 | * a packet is still in a qdisc or driver queue. | |
2107 | * In this case, there is very little point doing a retransmit ! | |
2108 | * Note: This is called from BH context only. | |
2109 | */ | |
2110 | static bool skb_still_in_host_queue(const struct sock *sk, | |
2111 | const struct sk_buff *skb) | |
2112 | { | |
2113 | const struct sk_buff *fclone = skb + 1; | |
2114 | ||
2115 | if (unlikely(skb->fclone == SKB_FCLONE_ORIG && | |
2116 | fclone->fclone == SKB_FCLONE_CLONE)) { | |
2117 | NET_INC_STATS_BH(sock_net(sk), | |
2118 | LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); | |
2119 | return true; | |
2120 | } | |
2121 | return false; | |
2122 | } | |
2123 | ||
6ba8a3b1 ND |
2124 | /* When probe timeout (PTO) fires, send a new segment if one exists, else |
2125 | * retransmit the last segment. | |
2126 | */ | |
2127 | void tcp_send_loss_probe(struct sock *sk) | |
2128 | { | |
9b717a8d | 2129 | struct tcp_sock *tp = tcp_sk(sk); |
6ba8a3b1 ND |
2130 | struct sk_buff *skb; |
2131 | int pcount; | |
2132 | int mss = tcp_current_mss(sk); | |
2133 | int err = -1; | |
2134 | ||
2135 | if (tcp_send_head(sk) != NULL) { | |
2136 | err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); | |
2137 | goto rearm_timer; | |
2138 | } | |
2139 | ||
9b717a8d ND |
2140 | /* At most one outstanding TLP retransmission. */ |
2141 | if (tp->tlp_high_seq) | |
2142 | goto rearm_timer; | |
2143 | ||
6ba8a3b1 ND |
2144 | /* Retransmit last segment. */ |
2145 | skb = tcp_write_queue_tail(sk); | |
2146 | if (WARN_ON(!skb)) | |
2147 | goto rearm_timer; | |
2148 | ||
1f3279ae ED |
2149 | if (skb_still_in_host_queue(sk, skb)) |
2150 | goto rearm_timer; | |
2151 | ||
6ba8a3b1 ND |
2152 | pcount = tcp_skb_pcount(skb); |
2153 | if (WARN_ON(!pcount)) | |
2154 | goto rearm_timer; | |
2155 | ||
2156 | if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { | |
6cc55e09 OP |
2157 | if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss, |
2158 | GFP_ATOMIC))) | |
6ba8a3b1 ND |
2159 | goto rearm_timer; |
2160 | skb = tcp_write_queue_tail(sk); | |
2161 | } | |
2162 | ||
2163 | if (WARN_ON(!skb || !tcp_skb_pcount(skb))) | |
2164 | goto rearm_timer; | |
2165 | ||
bef1909e | 2166 | err = __tcp_retransmit_skb(sk, skb); |
6ba8a3b1 | 2167 | |
9b717a8d ND |
2168 | /* Record snd_nxt for loss detection. */ |
2169 | if (likely(!err)) | |
2170 | tp->tlp_high_seq = tp->snd_nxt; | |
2171 | ||
6ba8a3b1 ND |
2172 | rearm_timer: |
2173 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
2174 | inet_csk(sk)->icsk_rto, | |
2175 | TCP_RTO_MAX); | |
2176 | ||
2177 | if (likely(!err)) | |
2178 | NET_INC_STATS_BH(sock_net(sk), | |
2179 | LINUX_MIB_TCPLOSSPROBES); | |
1da177e4 LT |
2180 | } |
2181 | ||
a762a980 DM |
2182 | /* Push out any pending frames which were held back due to |
2183 | * TCP_CORK or attempt at coalescing tiny packets. | |
2184 | * The socket must be locked by the caller. | |
2185 | */ | |
9e412ba7 IJ |
2186 | void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
2187 | int nonagle) | |
a762a980 | 2188 | { |
726e07a8 IJ |
2189 | /* If we are closed, the bytes will have to remain here. |
2190 | * In time closedown will finish, we empty the write queue and | |
2191 | * all will be happy. | |
2192 | */ | |
2193 | if (unlikely(sk->sk_state == TCP_CLOSE)) | |
2194 | return; | |
2195 | ||
99a1dec7 MG |
2196 | if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
2197 | sk_gfp_atomic(sk, GFP_ATOMIC))) | |
726e07a8 | 2198 | tcp_check_probe_timer(sk); |
a762a980 DM |
2199 | } |
2200 | ||
c1b4a7e6 DM |
2201 | /* Send _single_ skb sitting at the send head. This function requires |
2202 | * true push pending frames to setup probe timer etc. | |
2203 | */ | |
2204 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
2205 | { | |
fe067e8a | 2206 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
2207 | |
2208 | BUG_ON(!skb || skb->len < mss_now); | |
2209 | ||
d5dd9175 | 2210 | tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
c1b4a7e6 DM |
2211 | } |
2212 | ||
1da177e4 LT |
2213 | /* This function returns the amount that we can raise the |
2214 | * usable window based on the following constraints | |
e905a9ed | 2215 | * |
1da177e4 LT |
2216 | * 1. The window can never be shrunk once it is offered (RFC 793) |
2217 | * 2. We limit memory per socket | |
2218 | * | |
2219 | * RFC 1122: | |
2220 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
2221 | * RECV.NEXT + RCV.WIN fixed until: | |
2222 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
2223 | * | |
2224 | * i.e. don't raise the right edge of the window until you can raise | |
2225 | * it at least MSS bytes. | |
2226 | * | |
2227 | * Unfortunately, the recommended algorithm breaks header prediction, | |
2228 | * since header prediction assumes th->window stays fixed. | |
2229 | * | |
2230 | * Strictly speaking, keeping th->window fixed violates the receiver | |
2231 | * side SWS prevention criteria. The problem is that under this rule | |
2232 | * a stream of single byte packets will cause the right side of the | |
2233 | * window to always advance by a single byte. | |
e905a9ed | 2234 | * |
1da177e4 LT |
2235 | * Of course, if the sender implements sender side SWS prevention |
2236 | * then this will not be a problem. | |
e905a9ed | 2237 | * |
1da177e4 | 2238 | * BSD seems to make the following compromise: |
e905a9ed | 2239 | * |
1da177e4 LT |
2240 | * If the free space is less than the 1/4 of the maximum |
2241 | * space available and the free space is less than 1/2 mss, | |
2242 | * then set the window to 0. | |
2243 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
2244 | * Otherwise, just prevent the window from shrinking | |
2245 | * and from being larger than the largest representable value. | |
2246 | * | |
2247 | * This prevents incremental opening of the window in the regime | |
2248 | * where TCP is limited by the speed of the reader side taking | |
2249 | * data out of the TCP receive queue. It does nothing about | |
2250 | * those cases where the window is constrained on the sender side | |
2251 | * because the pipeline is full. | |
2252 | * | |
2253 | * BSD also seems to "accidentally" limit itself to windows that are a | |
2254 | * multiple of MSS, at least until the free space gets quite small. | |
2255 | * This would appear to be a side effect of the mbuf implementation. | |
2256 | * Combining these two algorithms results in the observed behavior | |
2257 | * of having a fixed window size at almost all times. | |
2258 | * | |
2259 | * Below we obtain similar behavior by forcing the offered window to | |
2260 | * a multiple of the mss when it is feasible to do so. | |
2261 | * | |
2262 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
2263 | * Regular options like TIMESTAMP are taken into account. | |
2264 | */ | |
2265 | u32 __tcp_select_window(struct sock *sk) | |
2266 | { | |
463c84b9 | 2267 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 2268 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 2269 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
2270 | * here. I don't know if the value based on our guesses |
2271 | * of peer's MSS is better for the performance. It's more correct | |
2272 | * but may be worse for the performance because of rcv_mss | |
2273 | * fluctuations. --SAW 1998/11/1 | |
2274 | */ | |
463c84b9 | 2275 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 | 2276 | int free_space = tcp_space(sk); |
86c1a045 FW |
2277 | int allowed_space = tcp_full_space(sk); |
2278 | int full_space = min_t(int, tp->window_clamp, allowed_space); | |
1da177e4 LT |
2279 | int window; |
2280 | ||
2281 | if (mss > full_space) | |
e905a9ed | 2282 | mss = full_space; |
1da177e4 | 2283 | |
b92edbe0 | 2284 | if (free_space < (full_space >> 1)) { |
463c84b9 | 2285 | icsk->icsk_ack.quick = 0; |
1da177e4 | 2286 | |
180d8cd9 | 2287 | if (sk_under_memory_pressure(sk)) |
056834d9 IJ |
2288 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, |
2289 | 4U * tp->advmss); | |
1da177e4 | 2290 | |
86c1a045 FW |
2291 | /* free_space might become our new window, make sure we don't |
2292 | * increase it due to wscale. | |
2293 | */ | |
2294 | free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); | |
2295 | ||
2296 | /* if free space is less than mss estimate, or is below 1/16th | |
2297 | * of the maximum allowed, try to move to zero-window, else | |
2298 | * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and | |
2299 | * new incoming data is dropped due to memory limits. | |
2300 | * With large window, mss test triggers way too late in order | |
2301 | * to announce zero window in time before rmem limit kicks in. | |
2302 | */ | |
2303 | if (free_space < (allowed_space >> 4) || free_space < mss) | |
1da177e4 LT |
2304 | return 0; |
2305 | } | |
2306 | ||
2307 | if (free_space > tp->rcv_ssthresh) | |
2308 | free_space = tp->rcv_ssthresh; | |
2309 | ||
2310 | /* Don't do rounding if we are using window scaling, since the | |
2311 | * scaled window will not line up with the MSS boundary anyway. | |
2312 | */ | |
2313 | window = tp->rcv_wnd; | |
2314 | if (tp->rx_opt.rcv_wscale) { | |
2315 | window = free_space; | |
2316 | ||
2317 | /* Advertise enough space so that it won't get scaled away. | |
2318 | * Import case: prevent zero window announcement if | |
2319 | * 1<<rcv_wscale > mss. | |
2320 | */ | |
2321 | if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) | |
2322 | window = (((window >> tp->rx_opt.rcv_wscale) + 1) | |
2323 | << tp->rx_opt.rcv_wscale); | |
2324 | } else { | |
2325 | /* Get the largest window that is a nice multiple of mss. | |
2326 | * Window clamp already applied above. | |
2327 | * If our current window offering is within 1 mss of the | |
2328 | * free space we just keep it. This prevents the divide | |
2329 | * and multiply from happening most of the time. | |
2330 | * We also don't do any window rounding when the free space | |
2331 | * is too small. | |
2332 | */ | |
2333 | if (window <= free_space - mss || window > free_space) | |
056834d9 | 2334 | window = (free_space / mss) * mss; |
84565070 | 2335 | else if (mss == full_space && |
b92edbe0 | 2336 | free_space > window + (full_space >> 1)) |
84565070 | 2337 | window = free_space; |
1da177e4 LT |
2338 | } |
2339 | ||
2340 | return window; | |
2341 | } | |
2342 | ||
4a17fc3a IJ |
2343 | /* Collapses two adjacent SKB's during retransmission. */ |
2344 | static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) | |
1da177e4 LT |
2345 | { |
2346 | struct tcp_sock *tp = tcp_sk(sk); | |
fe067e8a | 2347 | struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); |
058dc334 | 2348 | int skb_size, next_skb_size; |
1da177e4 | 2349 | |
058dc334 IJ |
2350 | skb_size = skb->len; |
2351 | next_skb_size = next_skb->len; | |
1da177e4 | 2352 | |
058dc334 | 2353 | BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
a6963a6b | 2354 | |
058dc334 | 2355 | tcp_highest_sack_combine(sk, next_skb, skb); |
1da177e4 | 2356 | |
058dc334 | 2357 | tcp_unlink_write_queue(next_skb, sk); |
1da177e4 | 2358 | |
058dc334 IJ |
2359 | skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), |
2360 | next_skb_size); | |
1da177e4 | 2361 | |
058dc334 IJ |
2362 | if (next_skb->ip_summed == CHECKSUM_PARTIAL) |
2363 | skb->ip_summed = CHECKSUM_PARTIAL; | |
1da177e4 | 2364 | |
058dc334 IJ |
2365 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
2366 | skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); | |
1da177e4 | 2367 | |
058dc334 IJ |
2368 | /* Update sequence range on original skb. */ |
2369 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1da177e4 | 2370 | |
e6c7d085 | 2371 | /* Merge over control information. This moves PSH/FIN etc. over */ |
4de075e0 | 2372 | TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
058dc334 IJ |
2373 | |
2374 | /* All done, get rid of second SKB and account for it so | |
2375 | * packet counting does not break. | |
2376 | */ | |
2377 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; | |
058dc334 IJ |
2378 | |
2379 | /* changed transmit queue under us so clear hints */ | |
ef9da47c IJ |
2380 | tcp_clear_retrans_hints_partial(tp); |
2381 | if (next_skb == tp->retransmit_skb_hint) | |
2382 | tp->retransmit_skb_hint = skb; | |
058dc334 | 2383 | |
797108d1 IJ |
2384 | tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
2385 | ||
058dc334 | 2386 | sk_wmem_free_skb(sk, next_skb); |
1da177e4 LT |
2387 | } |
2388 | ||
67edfef7 | 2389 | /* Check if coalescing SKBs is legal. */ |
a2a385d6 | 2390 | static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
4a17fc3a IJ |
2391 | { |
2392 | if (tcp_skb_pcount(skb) > 1) | |
a2a385d6 | 2393 | return false; |
4a17fc3a IJ |
2394 | /* TODO: SACK collapsing could be used to remove this condition */ |
2395 | if (skb_shinfo(skb)->nr_frags != 0) | |
a2a385d6 | 2396 | return false; |
4a17fc3a | 2397 | if (skb_cloned(skb)) |
a2a385d6 | 2398 | return false; |
4a17fc3a | 2399 | if (skb == tcp_send_head(sk)) |
a2a385d6 | 2400 | return false; |
4a17fc3a IJ |
2401 | /* Some heurestics for collapsing over SACK'd could be invented */ |
2402 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
a2a385d6 | 2403 | return false; |
4a17fc3a | 2404 | |
a2a385d6 | 2405 | return true; |
4a17fc3a IJ |
2406 | } |
2407 | ||
67edfef7 AK |
2408 | /* Collapse packets in the retransmit queue to make to create |
2409 | * less packets on the wire. This is only done on retransmission. | |
2410 | */ | |
4a17fc3a IJ |
2411 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
2412 | int space) | |
2413 | { | |
2414 | struct tcp_sock *tp = tcp_sk(sk); | |
2415 | struct sk_buff *skb = to, *tmp; | |
a2a385d6 | 2416 | bool first = true; |
4a17fc3a IJ |
2417 | |
2418 | if (!sysctl_tcp_retrans_collapse) | |
2419 | return; | |
4de075e0 | 2420 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
4a17fc3a IJ |
2421 | return; |
2422 | ||
2423 | tcp_for_write_queue_from_safe(skb, tmp, sk) { | |
2424 | if (!tcp_can_collapse(sk, skb)) | |
2425 | break; | |
2426 | ||
2427 | space -= skb->len; | |
2428 | ||
2429 | if (first) { | |
a2a385d6 | 2430 | first = false; |
4a17fc3a IJ |
2431 | continue; |
2432 | } | |
2433 | ||
2434 | if (space < 0) | |
2435 | break; | |
2436 | /* Punt if not enough space exists in the first SKB for | |
2437 | * the data in the second | |
2438 | */ | |
a21d4572 | 2439 | if (skb->len > skb_availroom(to)) |
4a17fc3a IJ |
2440 | break; |
2441 | ||
2442 | if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) | |
2443 | break; | |
2444 | ||
2445 | tcp_collapse_retrans(sk, to); | |
2446 | } | |
2447 | } | |
2448 | ||
1da177e4 LT |
2449 | /* This retransmits one SKB. Policy decisions and retransmit queue |
2450 | * state updates are done by the caller. Returns non-zero if an | |
2451 | * error occurred which prevented the send. | |
2452 | */ | |
93b174ad | 2453 | int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) |
1da177e4 LT |
2454 | { |
2455 | struct tcp_sock *tp = tcp_sk(sk); | |
5d424d5a | 2456 | struct inet_connection_sock *icsk = inet_csk(sk); |
7d227cd2 | 2457 | unsigned int cur_mss; |
c84a5711 | 2458 | int err; |
1da177e4 | 2459 | |
5d424d5a JH |
2460 | /* Inconslusive MTU probe */ |
2461 | if (icsk->icsk_mtup.probe_size) { | |
2462 | icsk->icsk_mtup.probe_size = 0; | |
2463 | } | |
2464 | ||
1da177e4 | 2465 | /* Do not sent more than we queued. 1/4 is reserved for possible |
caa20d9a | 2466 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 LT |
2467 | */ |
2468 | if (atomic_read(&sk->sk_wmem_alloc) > | |
2469 | min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) | |
2470 | return -EAGAIN; | |
2471 | ||
1f3279ae ED |
2472 | if (skb_still_in_host_queue(sk, skb)) |
2473 | return -EBUSY; | |
2474 | ||
1da177e4 LT |
2475 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { |
2476 | if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
2477 | BUG(); | |
1da177e4 LT |
2478 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
2479 | return -ENOMEM; | |
2480 | } | |
2481 | ||
7d227cd2 SS |
2482 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
2483 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
2484 | ||
0c54b85f | 2485 | cur_mss = tcp_current_mss(sk); |
7d227cd2 | 2486 | |
1da177e4 LT |
2487 | /* If receiver has shrunk his window, and skb is out of |
2488 | * new window, do not retransmit it. The exception is the | |
2489 | * case, when window is shrunk to zero. In this case | |
2490 | * our retransmit serves as a zero window probe. | |
2491 | */ | |
9d4fb27d JP |
2492 | if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && |
2493 | TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1da177e4 LT |
2494 | return -EAGAIN; |
2495 | ||
2496 | if (skb->len > cur_mss) { | |
6cc55e09 | 2497 | if (tcp_fragment(sk, skb, cur_mss, cur_mss, GFP_ATOMIC)) |
1da177e4 | 2498 | return -ENOMEM; /* We'll try again later. */ |
02276f3c | 2499 | } else { |
9eb9362e IJ |
2500 | int oldpcount = tcp_skb_pcount(skb); |
2501 | ||
2502 | if (unlikely(oldpcount > 1)) { | |
c52e2421 ED |
2503 | if (skb_unclone(skb, GFP_ATOMIC)) |
2504 | return -ENOMEM; | |
9eb9362e IJ |
2505 | tcp_init_tso_segs(sk, skb, cur_mss); |
2506 | tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); | |
2507 | } | |
1da177e4 LT |
2508 | } |
2509 | ||
4a17fc3a | 2510 | tcp_retrans_try_collapse(sk, skb, cur_mss); |
1da177e4 | 2511 | |
1da177e4 LT |
2512 | /* Make a copy, if the first transmission SKB clone we made |
2513 | * is still in somebody's hands, else make a clone. | |
2514 | */ | |
1da177e4 | 2515 | |
50bceae9 TG |
2516 | /* make sure skb->data is aligned on arches that require it |
2517 | * and check if ack-trimming & collapsing extended the headroom | |
2518 | * beyond what csum_start can cover. | |
2519 | */ | |
2520 | if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || | |
2521 | skb_headroom(skb) >= 0xFFFF)) { | |
117632e6 ED |
2522 | struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, |
2523 | GFP_ATOMIC); | |
c84a5711 YC |
2524 | err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : |
2525 | -ENOBUFS; | |
117632e6 | 2526 | } else { |
c84a5711 | 2527 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
117632e6 | 2528 | } |
c84a5711 | 2529 | |
fc9f3501 | 2530 | if (likely(!err)) { |
c84a5711 | 2531 | TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; |
fc9f3501 ED |
2532 | /* Update global TCP statistics. */ |
2533 | TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); | |
2534 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) | |
2535 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
2536 | tp->total_retrans++; | |
2537 | } | |
c84a5711 | 2538 | return err; |
93b174ad YC |
2539 | } |
2540 | ||
2541 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) | |
2542 | { | |
2543 | struct tcp_sock *tp = tcp_sk(sk); | |
2544 | int err = __tcp_retransmit_skb(sk, skb); | |
1da177e4 LT |
2545 | |
2546 | if (err == 0) { | |
1da177e4 | 2547 | #if FASTRETRANS_DEBUG > 0 |
056834d9 | 2548 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
e87cc472 | 2549 | net_dbg_ratelimited("retrans_out leaked\n"); |
1da177e4 LT |
2550 | } |
2551 | #endif | |
b08d6cb2 IJ |
2552 | if (!tp->retrans_out) |
2553 | tp->lost_retrans_low = tp->snd_nxt; | |
1da177e4 LT |
2554 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; |
2555 | tp->retrans_out += tcp_skb_pcount(skb); | |
2556 | ||
2557 | /* Save stamp of the first retransmit. */ | |
2558 | if (!tp->retrans_stamp) | |
7faee5c0 | 2559 | tp->retrans_stamp = tcp_skb_timestamp(skb); |
1da177e4 | 2560 | |
1da177e4 LT |
2561 | /* snd_nxt is stored to detect loss of retransmitted segment, |
2562 | * see tcp_input.c tcp_sacktag_write_queue(). | |
2563 | */ | |
2564 | TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; | |
1f3279ae | 2565 | } else if (err != -EBUSY) { |
24ab6bec | 2566 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); |
1da177e4 | 2567 | } |
6e08d5e3 YC |
2568 | |
2569 | if (tp->undo_retrans < 0) | |
2570 | tp->undo_retrans = 0; | |
2571 | tp->undo_retrans += tcp_skb_pcount(skb); | |
1da177e4 LT |
2572 | return err; |
2573 | } | |
2574 | ||
67edfef7 AK |
2575 | /* Check if we forward retransmits are possible in the current |
2576 | * window/congestion state. | |
2577 | */ | |
a2a385d6 | 2578 | static bool tcp_can_forward_retransmit(struct sock *sk) |
b5afe7bc IJ |
2579 | { |
2580 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
cf533ea5 | 2581 | const struct tcp_sock *tp = tcp_sk(sk); |
b5afe7bc IJ |
2582 | |
2583 | /* Forward retransmissions are possible only during Recovery. */ | |
2584 | if (icsk->icsk_ca_state != TCP_CA_Recovery) | |
a2a385d6 | 2585 | return false; |
b5afe7bc IJ |
2586 | |
2587 | /* No forward retransmissions in Reno are possible. */ | |
2588 | if (tcp_is_reno(tp)) | |
a2a385d6 | 2589 | return false; |
b5afe7bc IJ |
2590 | |
2591 | /* Yeah, we have to make difficult choice between forward transmission | |
2592 | * and retransmission... Both ways have their merits... | |
2593 | * | |
2594 | * For now we do not retransmit anything, while we have some new | |
2595 | * segments to send. In the other cases, follow rule 3 for | |
2596 | * NextSeg() specified in RFC3517. | |
2597 | */ | |
2598 | ||
2599 | if (tcp_may_send_now(sk)) | |
a2a385d6 | 2600 | return false; |
b5afe7bc | 2601 | |
a2a385d6 | 2602 | return true; |
b5afe7bc IJ |
2603 | } |
2604 | ||
1da177e4 LT |
2605 | /* This gets called after a retransmit timeout, and the initially |
2606 | * retransmitted data is acknowledged. It tries to continue | |
2607 | * resending the rest of the retransmit queue, until either | |
2608 | * we've sent it all or the congestion window limit is reached. | |
2609 | * If doing SACK, the first ACK which comes back for a timeout | |
2610 | * based retransmit packet might feed us FACK information again. | |
2611 | * If so, we use it to avoid unnecessarily retransmissions. | |
2612 | */ | |
2613 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
2614 | { | |
6687e988 | 2615 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2616 | struct tcp_sock *tp = tcp_sk(sk); |
2617 | struct sk_buff *skb; | |
0e1c54c2 | 2618 | struct sk_buff *hole = NULL; |
618d9f25 | 2619 | u32 last_lost; |
61eb55f4 | 2620 | int mib_idx; |
0e1c54c2 | 2621 | int fwd_rexmitting = 0; |
6a438bbe | 2622 | |
45e77d31 IJ |
2623 | if (!tp->packets_out) |
2624 | return; | |
2625 | ||
08ebd172 IJ |
2626 | if (!tp->lost_out) |
2627 | tp->retransmit_high = tp->snd_una; | |
2628 | ||
618d9f25 | 2629 | if (tp->retransmit_skb_hint) { |
6a438bbe | 2630 | skb = tp->retransmit_skb_hint; |
618d9f25 IJ |
2631 | last_lost = TCP_SKB_CB(skb)->end_seq; |
2632 | if (after(last_lost, tp->retransmit_high)) | |
2633 | last_lost = tp->retransmit_high; | |
2634 | } else { | |
fe067e8a | 2635 | skb = tcp_write_queue_head(sk); |
618d9f25 IJ |
2636 | last_lost = tp->snd_una; |
2637 | } | |
1da177e4 | 2638 | |
08ebd172 IJ |
2639 | tcp_for_write_queue_from(skb, sk) { |
2640 | __u8 sacked = TCP_SKB_CB(skb)->sacked; | |
1da177e4 | 2641 | |
08ebd172 IJ |
2642 | if (skb == tcp_send_head(sk)) |
2643 | break; | |
2644 | /* we could do better than to assign each time */ | |
0e1c54c2 IJ |
2645 | if (hole == NULL) |
2646 | tp->retransmit_skb_hint = skb; | |
08ebd172 IJ |
2647 | |
2648 | /* Assume this retransmit will generate | |
2649 | * only one packet for congestion window | |
2650 | * calculation purposes. This works because | |
2651 | * tcp_retransmit_skb() will chop up the | |
2652 | * packet to be MSS sized and all the | |
2653 | * packet counting works out. | |
2654 | */ | |
2655 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
2656 | return; | |
1da177e4 | 2657 | |
0e1c54c2 IJ |
2658 | if (fwd_rexmitting) { |
2659 | begin_fwd: | |
2660 | if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) | |
2661 | break; | |
2662 | mib_idx = LINUX_MIB_TCPFORWARDRETRANS; | |
6a438bbe | 2663 | |
0e1c54c2 | 2664 | } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { |
618d9f25 | 2665 | tp->retransmit_high = last_lost; |
0e1c54c2 IJ |
2666 | if (!tcp_can_forward_retransmit(sk)) |
2667 | break; | |
2668 | /* Backtrack if necessary to non-L'ed skb */ | |
2669 | if (hole != NULL) { | |
2670 | skb = hole; | |
2671 | hole = NULL; | |
2672 | } | |
2673 | fwd_rexmitting = 1; | |
2674 | goto begin_fwd; | |
1da177e4 | 2675 | |
0e1c54c2 | 2676 | } else if (!(sacked & TCPCB_LOST)) { |
ac11ba75 | 2677 | if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
0e1c54c2 IJ |
2678 | hole = skb; |
2679 | continue; | |
1da177e4 | 2680 | |
0e1c54c2 | 2681 | } else { |
618d9f25 | 2682 | last_lost = TCP_SKB_CB(skb)->end_seq; |
0e1c54c2 IJ |
2683 | if (icsk->icsk_ca_state != TCP_CA_Loss) |
2684 | mib_idx = LINUX_MIB_TCPFASTRETRANS; | |
2685 | else | |
2686 | mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; | |
2687 | } | |
1da177e4 | 2688 | |
0e1c54c2 | 2689 | if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
1da177e4 LT |
2690 | continue; |
2691 | ||
24ab6bec | 2692 | if (tcp_retransmit_skb(sk, skb)) |
0e1c54c2 | 2693 | return; |
24ab6bec | 2694 | |
0e1c54c2 | 2695 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 | 2696 | |
684bad11 | 2697 | if (tcp_in_cwnd_reduction(sk)) |
a262f0cd ND |
2698 | tp->prr_out += tcp_skb_pcount(skb); |
2699 | ||
fe067e8a | 2700 | if (skb == tcp_write_queue_head(sk)) |
3f421baa ACM |
2701 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
2702 | inet_csk(sk)->icsk_rto, | |
2703 | TCP_RTO_MAX); | |
1da177e4 LT |
2704 | } |
2705 | } | |
2706 | ||
1da177e4 LT |
2707 | /* Send a fin. The caller locks the socket for us. This cannot be |
2708 | * allowed to fail queueing a FIN frame under any circumstances. | |
2709 | */ | |
2710 | void tcp_send_fin(struct sock *sk) | |
2711 | { | |
e905a9ed | 2712 | struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 2713 | struct sk_buff *skb = tcp_write_queue_tail(sk); |
1da177e4 | 2714 | int mss_now; |
e905a9ed | 2715 | |
1da177e4 LT |
2716 | /* Optimization, tack on the FIN if we have a queue of |
2717 | * unsent frames. But be careful about outgoing SACKS | |
2718 | * and IP options. | |
2719 | */ | |
0c54b85f | 2720 | mss_now = tcp_current_mss(sk); |
1da177e4 | 2721 | |
fe067e8a | 2722 | if (tcp_send_head(sk) != NULL) { |
4de075e0 | 2723 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; |
1da177e4 LT |
2724 | TCP_SKB_CB(skb)->end_seq++; |
2725 | tp->write_seq++; | |
2726 | } else { | |
2727 | /* Socket is locked, keep trying until memory is available. */ | |
2728 | for (;;) { | |
aa133076 WF |
2729 | skb = alloc_skb_fclone(MAX_TCP_HEADER, |
2730 | sk->sk_allocation); | |
1da177e4 LT |
2731 | if (skb) |
2732 | break; | |
2733 | yield(); | |
2734 | } | |
2735 | ||
2736 | /* Reserve space for headers and prepare control bits. */ | |
2737 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 | 2738 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
e870a8ef | 2739 | tcp_init_nondata_skb(skb, tp->write_seq, |
a3433f35 | 2740 | TCPHDR_ACK | TCPHDR_FIN); |
1da177e4 LT |
2741 | tcp_queue_skb(sk, skb); |
2742 | } | |
9e412ba7 | 2743 | __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); |
1da177e4 LT |
2744 | } |
2745 | ||
2746 | /* We get here when a process closes a file descriptor (either due to | |
2747 | * an explicit close() or as a byproduct of exit()'ing) and there | |
2748 | * was unread data in the receive queue. This behavior is recommended | |
65bb723c | 2749 | * by RFC 2525, section 2.17. -DaveM |
1da177e4 | 2750 | */ |
dd0fc66f | 2751 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 | 2752 | { |
1da177e4 LT |
2753 | struct sk_buff *skb; |
2754 | ||
2755 | /* NOTE: No TCP options attached and we never retransmit this. */ | |
2756 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
2757 | if (!skb) { | |
4e673444 | 2758 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
1da177e4 LT |
2759 | return; |
2760 | } | |
2761 | ||
2762 | /* Reserve space for headers and prepare control bits. */ | |
2763 | skb_reserve(skb, MAX_TCP_HEADER); | |
e870a8ef | 2764 | tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
a3433f35 | 2765 | TCPHDR_ACK | TCPHDR_RST); |
1da177e4 | 2766 | /* Send it off. */ |
dfb4b9dc | 2767 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
4e673444 | 2768 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
26af65cb | 2769 | |
81cc8a75 | 2770 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
1da177e4 LT |
2771 | } |
2772 | ||
67edfef7 AK |
2773 | /* Send a crossed SYN-ACK during socket establishment. |
2774 | * WARNING: This routine must only be called when we have already sent | |
1da177e4 LT |
2775 | * a SYN packet that crossed the incoming SYN that caused this routine |
2776 | * to get called. If this assumption fails then the initial rcv_wnd | |
2777 | * and rcv_wscale values will not be correct. | |
2778 | */ | |
2779 | int tcp_send_synack(struct sock *sk) | |
2780 | { | |
056834d9 | 2781 | struct sk_buff *skb; |
1da177e4 | 2782 | |
fe067e8a | 2783 | skb = tcp_write_queue_head(sk); |
4de075e0 | 2784 | if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
91df42be | 2785 | pr_debug("%s: wrong queue state\n", __func__); |
1da177e4 LT |
2786 | return -EFAULT; |
2787 | } | |
4de075e0 | 2788 | if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
1da177e4 LT |
2789 | if (skb_cloned(skb)) { |
2790 | struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); | |
2791 | if (nskb == NULL) | |
2792 | return -ENOMEM; | |
fe067e8a | 2793 | tcp_unlink_write_queue(skb, sk); |
f4a775d1 | 2794 | __skb_header_release(nskb); |
fe067e8a | 2795 | __tcp_add_write_queue_head(sk, nskb); |
3ab224be HA |
2796 | sk_wmem_free_skb(sk, skb); |
2797 | sk->sk_wmem_queued += nskb->truesize; | |
2798 | sk_mem_charge(sk, nskb->truesize); | |
1da177e4 LT |
2799 | skb = nskb; |
2800 | } | |
2801 | ||
4de075e0 | 2802 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
30e502a3 | 2803 | TCP_ECN_send_synack(sk, skb); |
1da177e4 | 2804 | } |
dfb4b9dc | 2805 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2806 | } |
2807 | ||
4aea39c1 ED |
2808 | /** |
2809 | * tcp_make_synack - Prepare a SYN-ACK. | |
2810 | * sk: listener socket | |
2811 | * dst: dst entry attached to the SYNACK | |
2812 | * req: request_sock pointer | |
4aea39c1 ED |
2813 | * |
2814 | * Allocate one skb and build a SYNACK packet. | |
2815 | * @dst is consumed : Caller should not use it again. | |
2816 | */ | |
056834d9 | 2817 | struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, |
e6b4d113 | 2818 | struct request_sock *req, |
8336886f | 2819 | struct tcp_fastopen_cookie *foc) |
1da177e4 | 2820 | { |
bd0388ae | 2821 | struct tcp_out_options opts; |
2e6599cb | 2822 | struct inet_request_sock *ireq = inet_rsk(req); |
1da177e4 LT |
2823 | struct tcp_sock *tp = tcp_sk(sk); |
2824 | struct tcphdr *th; | |
1da177e4 | 2825 | struct sk_buff *skb; |
cfb6eeb4 | 2826 | struct tcp_md5sig_key *md5; |
bd0388ae | 2827 | int tcp_header_size; |
f5fff5dc | 2828 | int mss; |
1da177e4 | 2829 | |
a0b8486c | 2830 | skb = sock_wmalloc(sk, MAX_TCP_HEADER, 1, GFP_ATOMIC); |
4aea39c1 ED |
2831 | if (unlikely(!skb)) { |
2832 | dst_release(dst); | |
1da177e4 | 2833 | return NULL; |
4aea39c1 | 2834 | } |
1da177e4 LT |
2835 | /* Reserve space for headers. */ |
2836 | skb_reserve(skb, MAX_TCP_HEADER); | |
2837 | ||
4aea39c1 | 2838 | skb_dst_set(skb, dst); |
ca10b9e9 | 2839 | security_skb_owned_by(skb, sk); |
1da177e4 | 2840 | |
0dbaee3b | 2841 | mss = dst_metric_advmss(dst); |
f5fff5dc TQ |
2842 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) |
2843 | mss = tp->rx_opt.user_mss; | |
2844 | ||
33ad798c | 2845 | memset(&opts, 0, sizeof(opts)); |
8b5f12d0 FW |
2846 | #ifdef CONFIG_SYN_COOKIES |
2847 | if (unlikely(req->cookie_ts)) | |
7faee5c0 | 2848 | skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); |
8b5f12d0 FW |
2849 | else |
2850 | #endif | |
7faee5c0 | 2851 | skb_mstamp_get(&skb->skb_mstamp); |
1a2c6181 CP |
2852 | tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5, |
2853 | foc) + sizeof(*th); | |
cfb6eeb4 | 2854 | |
aa8223c7 ACM |
2855 | skb_push(skb, tcp_header_size); |
2856 | skb_reset_transport_header(skb); | |
1da177e4 | 2857 | |
aa8223c7 | 2858 | th = tcp_hdr(skb); |
1da177e4 LT |
2859 | memset(th, 0, sizeof(struct tcphdr)); |
2860 | th->syn = 1; | |
2861 | th->ack = 1; | |
30e502a3 | 2862 | TCP_ECN_make_synack(req, th, sk); |
b44084c2 | 2863 | th->source = htons(ireq->ir_num); |
634fb979 | 2864 | th->dest = ireq->ir_rmt_port; |
e870a8ef IJ |
2865 | /* Setting of flags are superfluous here for callers (and ECE is |
2866 | * not even correctly set) | |
2867 | */ | |
2868 | tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, | |
a3433f35 | 2869 | TCPHDR_SYN | TCPHDR_ACK); |
4957faad | 2870 | |
1da177e4 | 2871 | th->seq = htonl(TCP_SKB_CB(skb)->seq); |
8336886f JC |
2872 | /* XXX data is queued and acked as is. No buffer/window check */ |
2873 | th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); | |
1da177e4 LT |
2874 | |
2875 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
600ff0c2 | 2876 | th->window = htons(min(req->rcv_wnd, 65535U)); |
bd0388ae | 2877 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
1da177e4 | 2878 | th->doff = (tcp_header_size >> 2); |
a0b8486c | 2879 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_OUTSEGS); |
cfb6eeb4 YH |
2880 | |
2881 | #ifdef CONFIG_TCP_MD5SIG | |
2882 | /* Okay, we have all we need - do the md5 hash if needed */ | |
2883 | if (md5) { | |
bd0388ae | 2884 | tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 2885 | md5, NULL, req, skb); |
cfb6eeb4 YH |
2886 | } |
2887 | #endif | |
2888 | ||
1da177e4 LT |
2889 | return skb; |
2890 | } | |
4bc2f18b | 2891 | EXPORT_SYMBOL(tcp_make_synack); |
1da177e4 | 2892 | |
67edfef7 | 2893 | /* Do all connect socket setups that can be done AF independent. */ |
f7e56a76 | 2894 | static void tcp_connect_init(struct sock *sk) |
1da177e4 | 2895 | { |
cf533ea5 | 2896 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
2897 | struct tcp_sock *tp = tcp_sk(sk); |
2898 | __u8 rcv_wscale; | |
2899 | ||
2900 | /* We'll fix this up when we get a response from the other end. | |
2901 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
2902 | */ | |
2903 | tp->tcp_header_len = sizeof(struct tcphdr) + | |
bb5b7c11 | 2904 | (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); |
1da177e4 | 2905 | |
cfb6eeb4 YH |
2906 | #ifdef CONFIG_TCP_MD5SIG |
2907 | if (tp->af_specific->md5_lookup(sk, sk) != NULL) | |
2908 | tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; | |
2909 | #endif | |
2910 | ||
1da177e4 LT |
2911 | /* If user gave his TCP_MAXSEG, record it to clamp */ |
2912 | if (tp->rx_opt.user_mss) | |
2913 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
2914 | tp->max_window = 0; | |
5d424d5a | 2915 | tcp_mtup_init(sk); |
1da177e4 LT |
2916 | tcp_sync_mss(sk, dst_mtu(dst)); |
2917 | ||
2918 | if (!tp->window_clamp) | |
2919 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
0dbaee3b | 2920 | tp->advmss = dst_metric_advmss(dst); |
f5fff5dc TQ |
2921 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) |
2922 | tp->advmss = tp->rx_opt.user_mss; | |
2923 | ||
1da177e4 | 2924 | tcp_initialize_rcv_mss(sk); |
1da177e4 | 2925 | |
e88c64f0 HPP |
2926 | /* limit the window selection if the user enforce a smaller rx buffer */ |
2927 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
2928 | (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) | |
2929 | tp->window_clamp = tcp_full_space(sk); | |
2930 | ||
1da177e4 LT |
2931 | tcp_select_initial_window(tcp_full_space(sk), |
2932 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), | |
2933 | &tp->rcv_wnd, | |
2934 | &tp->window_clamp, | |
bb5b7c11 | 2935 | sysctl_tcp_window_scaling, |
31d12926 | 2936 | &rcv_wscale, |
2937 | dst_metric(dst, RTAX_INITRWND)); | |
1da177e4 LT |
2938 | |
2939 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
2940 | tp->rcv_ssthresh = tp->rcv_wnd; | |
2941 | ||
2942 | sk->sk_err = 0; | |
2943 | sock_reset_flag(sk, SOCK_DONE); | |
2944 | tp->snd_wnd = 0; | |
ee7537b6 | 2945 | tcp_init_wl(tp, 0); |
1da177e4 LT |
2946 | tp->snd_una = tp->write_seq; |
2947 | tp->snd_sml = tp->write_seq; | |
33f5f57e | 2948 | tp->snd_up = tp->write_seq; |
370816ae | 2949 | tp->snd_nxt = tp->write_seq; |
ee995283 PE |
2950 | |
2951 | if (likely(!tp->repair)) | |
2952 | tp->rcv_nxt = 0; | |
c7781a6e AV |
2953 | else |
2954 | tp->rcv_tstamp = tcp_time_stamp; | |
ee995283 PE |
2955 | tp->rcv_wup = tp->rcv_nxt; |
2956 | tp->copied_seq = tp->rcv_nxt; | |
1da177e4 | 2957 | |
463c84b9 ACM |
2958 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
2959 | inet_csk(sk)->icsk_retransmits = 0; | |
1da177e4 LT |
2960 | tcp_clear_retrans(tp); |
2961 | } | |
2962 | ||
783237e8 YC |
2963 | static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
2964 | { | |
2965 | struct tcp_sock *tp = tcp_sk(sk); | |
2966 | struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); | |
2967 | ||
2968 | tcb->end_seq += skb->len; | |
f4a775d1 | 2969 | __skb_header_release(skb); |
783237e8 YC |
2970 | __tcp_add_write_queue_tail(sk, skb); |
2971 | sk->sk_wmem_queued += skb->truesize; | |
2972 | sk_mem_charge(sk, skb->truesize); | |
2973 | tp->write_seq = tcb->end_seq; | |
2974 | tp->packets_out += tcp_skb_pcount(skb); | |
2975 | } | |
2976 | ||
2977 | /* Build and send a SYN with data and (cached) Fast Open cookie. However, | |
2978 | * queue a data-only packet after the regular SYN, such that regular SYNs | |
2979 | * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges | |
2980 | * only the SYN sequence, the data are retransmitted in the first ACK. | |
2981 | * If cookie is not cached or other error occurs, falls back to send a | |
2982 | * regular SYN with Fast Open cookie request option. | |
2983 | */ | |
2984 | static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) | |
2985 | { | |
2986 | struct tcp_sock *tp = tcp_sk(sk); | |
2987 | struct tcp_fastopen_request *fo = tp->fastopen_req; | |
aab48743 | 2988 | int syn_loss = 0, space, i, err = 0, iovlen = fo->data->msg_iovlen; |
783237e8 | 2989 | struct sk_buff *syn_data = NULL, *data; |
aab48743 YC |
2990 | unsigned long last_syn_loss = 0; |
2991 | ||
67da22d2 | 2992 | tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
aab48743 YC |
2993 | tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, |
2994 | &syn_loss, &last_syn_loss); | |
2995 | /* Recurring FO SYN losses: revert to regular handshake temporarily */ | |
2996 | if (syn_loss > 1 && | |
2997 | time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { | |
2998 | fo->cookie.len = -1; | |
2999 | goto fallback; | |
3000 | } | |
783237e8 | 3001 | |
67da22d2 YC |
3002 | if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) |
3003 | fo->cookie.len = -1; | |
3004 | else if (fo->cookie.len <= 0) | |
783237e8 YC |
3005 | goto fallback; |
3006 | ||
3007 | /* MSS for SYN-data is based on cached MSS and bounded by PMTU and | |
3008 | * user-MSS. Reserve maximum option space for middleboxes that add | |
3009 | * private TCP options. The cost is reduced data space in SYN :( | |
3010 | */ | |
3011 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) | |
3012 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
1b63edd6 | 3013 | space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - |
783237e8 YC |
3014 | MAX_TCP_OPTION_SPACE; |
3015 | ||
f5ddcbbb ED |
3016 | space = min_t(size_t, space, fo->size); |
3017 | ||
3018 | /* limit to order-0 allocations */ | |
3019 | space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); | |
3020 | ||
3021 | syn_data = skb_copy_expand(syn, MAX_TCP_HEADER, space, | |
783237e8 YC |
3022 | sk->sk_allocation); |
3023 | if (syn_data == NULL) | |
3024 | goto fallback; | |
3025 | ||
3026 | for (i = 0; i < iovlen && syn_data->len < space; ++i) { | |
3027 | struct iovec *iov = &fo->data->msg_iov[i]; | |
3028 | unsigned char __user *from = iov->iov_base; | |
3029 | int len = iov->iov_len; | |
3030 | ||
3031 | if (syn_data->len + len > space) | |
3032 | len = space - syn_data->len; | |
3033 | else if (i + 1 == iovlen) | |
3034 | /* No more data pending in inet_wait_for_connect() */ | |
3035 | fo->data = NULL; | |
3036 | ||
3037 | if (skb_add_data(syn_data, from, len)) | |
3038 | goto fallback; | |
3039 | } | |
3040 | ||
3041 | /* Queue a data-only packet after the regular SYN for retransmission */ | |
3042 | data = pskb_copy(syn_data, sk->sk_allocation); | |
3043 | if (data == NULL) | |
3044 | goto fallback; | |
3045 | TCP_SKB_CB(data)->seq++; | |
3046 | TCP_SKB_CB(data)->tcp_flags &= ~TCPHDR_SYN; | |
3047 | TCP_SKB_CB(data)->tcp_flags = (TCPHDR_ACK|TCPHDR_PSH); | |
3048 | tcp_connect_queue_skb(sk, data); | |
3049 | fo->copied = data->len; | |
3050 | ||
431a9124 ED |
3051 | /* syn_data is about to be sent, we need to take current time stamps |
3052 | * for the packets that are in write queue : SYN packet and DATA | |
3053 | */ | |
3054 | skb_mstamp_get(&syn->skb_mstamp); | |
3055 | data->skb_mstamp = syn->skb_mstamp; | |
3056 | ||
783237e8 | 3057 | if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) { |
67da22d2 | 3058 | tp->syn_data = (fo->copied > 0); |
f19c29e3 | 3059 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); |
783237e8 YC |
3060 | goto done; |
3061 | } | |
3062 | syn_data = NULL; | |
3063 | ||
3064 | fallback: | |
3065 | /* Send a regular SYN with Fast Open cookie request option */ | |
3066 | if (fo->cookie.len > 0) | |
3067 | fo->cookie.len = 0; | |
3068 | err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); | |
3069 | if (err) | |
3070 | tp->syn_fastopen = 0; | |
3071 | kfree_skb(syn_data); | |
3072 | done: | |
3073 | fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ | |
3074 | return err; | |
3075 | } | |
3076 | ||
67edfef7 | 3077 | /* Build a SYN and send it off. */ |
1da177e4 LT |
3078 | int tcp_connect(struct sock *sk) |
3079 | { | |
3080 | struct tcp_sock *tp = tcp_sk(sk); | |
3081 | struct sk_buff *buff; | |
ee586811 | 3082 | int err; |
1da177e4 LT |
3083 | |
3084 | tcp_connect_init(sk); | |
3085 | ||
2b916477 AV |
3086 | if (unlikely(tp->repair)) { |
3087 | tcp_finish_connect(sk, NULL); | |
3088 | return 0; | |
3089 | } | |
3090 | ||
d179cd12 | 3091 | buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); |
1da177e4 LT |
3092 | if (unlikely(buff == NULL)) |
3093 | return -ENOBUFS; | |
3094 | ||
3095 | /* Reserve space for headers. */ | |
3096 | skb_reserve(buff, MAX_TCP_HEADER); | |
3097 | ||
a3433f35 | 3098 | tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
7faee5c0 | 3099 | tp->retrans_stamp = tcp_time_stamp; |
783237e8 | 3100 | tcp_connect_queue_skb(sk, buff); |
e870a8ef | 3101 | TCP_ECN_send_syn(sk, buff); |
1da177e4 | 3102 | |
783237e8 YC |
3103 | /* Send off SYN; include data in Fast Open. */ |
3104 | err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : | |
3105 | tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); | |
ee586811 EP |
3106 | if (err == -ECONNREFUSED) |
3107 | return err; | |
bd37a088 WY |
3108 | |
3109 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
3110 | * in order to make this packet get counted in tcpOutSegs. | |
3111 | */ | |
3112 | tp->snd_nxt = tp->write_seq; | |
3113 | tp->pushed_seq = tp->write_seq; | |
81cc8a75 | 3114 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
1da177e4 LT |
3115 | |
3116 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
3117 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3118 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
3119 | return 0; |
3120 | } | |
4bc2f18b | 3121 | EXPORT_SYMBOL(tcp_connect); |
1da177e4 LT |
3122 | |
3123 | /* Send out a delayed ack, the caller does the policy checking | |
3124 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
3125 | * for details. | |
3126 | */ | |
3127 | void tcp_send_delayed_ack(struct sock *sk) | |
3128 | { | |
463c84b9 ACM |
3129 | struct inet_connection_sock *icsk = inet_csk(sk); |
3130 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
3131 | unsigned long timeout; |
3132 | ||
3133 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 3134 | const struct tcp_sock *tp = tcp_sk(sk); |
056834d9 | 3135 | int max_ato = HZ / 2; |
1da177e4 | 3136 | |
056834d9 IJ |
3137 | if (icsk->icsk_ack.pingpong || |
3138 | (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) | |
1da177e4 LT |
3139 | max_ato = TCP_DELACK_MAX; |
3140 | ||
3141 | /* Slow path, intersegment interval is "high". */ | |
3142 | ||
3143 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 3144 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
3145 | * directly. |
3146 | */ | |
740b0f18 ED |
3147 | if (tp->srtt_us) { |
3148 | int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), | |
3149 | TCP_DELACK_MIN); | |
1da177e4 LT |
3150 | |
3151 | if (rtt < max_ato) | |
3152 | max_ato = rtt; | |
3153 | } | |
3154 | ||
3155 | ato = min(ato, max_ato); | |
3156 | } | |
3157 | ||
3158 | /* Stay within the limit we were given */ | |
3159 | timeout = jiffies + ato; | |
3160 | ||
3161 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 3162 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
3163 | /* If delack timer was blocked or is about to expire, |
3164 | * send ACK now. | |
3165 | */ | |
463c84b9 ACM |
3166 | if (icsk->icsk_ack.blocked || |
3167 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
3168 | tcp_send_ack(sk); |
3169 | return; | |
3170 | } | |
3171 | ||
463c84b9 ACM |
3172 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
3173 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 3174 | } |
463c84b9 ACM |
3175 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
3176 | icsk->icsk_ack.timeout = timeout; | |
3177 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
3178 | } |
3179 | ||
3180 | /* This routine sends an ack and also updates the window. */ | |
3181 | void tcp_send_ack(struct sock *sk) | |
3182 | { | |
058dc334 | 3183 | struct sk_buff *buff; |
1da177e4 | 3184 | |
058dc334 IJ |
3185 | /* If we have been reset, we may not send again. */ |
3186 | if (sk->sk_state == TCP_CLOSE) | |
3187 | return; | |
1da177e4 | 3188 | |
058dc334 IJ |
3189 | /* We are not putting this on the write queue, so |
3190 | * tcp_transmit_skb() will set the ownership to this | |
3191 | * sock. | |
3192 | */ | |
99a1dec7 | 3193 | buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); |
058dc334 IJ |
3194 | if (buff == NULL) { |
3195 | inet_csk_schedule_ack(sk); | |
3196 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3197 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, | |
3198 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
3199 | return; | |
1da177e4 | 3200 | } |
058dc334 IJ |
3201 | |
3202 | /* Reserve space for headers and prepare control bits. */ | |
3203 | skb_reserve(buff, MAX_TCP_HEADER); | |
a3433f35 | 3204 | tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
058dc334 IJ |
3205 | |
3206 | /* Send it off, this clears delayed acks for us. */ | |
7faee5c0 | 3207 | skb_mstamp_get(&buff->skb_mstamp); |
99a1dec7 | 3208 | tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); |
1da177e4 LT |
3209 | } |
3210 | ||
3211 | /* This routine sends a packet with an out of date sequence | |
3212 | * number. It assumes the other end will try to ack it. | |
3213 | * | |
3214 | * Question: what should we make while urgent mode? | |
3215 | * 4.4BSD forces sending single byte of data. We cannot send | |
3216 | * out of window data, because we have SND.NXT==SND.MAX... | |
3217 | * | |
3218 | * Current solution: to send TWO zero-length segments in urgent mode: | |
3219 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
3220 | * out-of-date with SND.UNA-1 to probe window. | |
3221 | */ | |
3222 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent) | |
3223 | { | |
3224 | struct tcp_sock *tp = tcp_sk(sk); | |
3225 | struct sk_buff *skb; | |
3226 | ||
3227 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
99a1dec7 | 3228 | skb = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); |
e905a9ed | 3229 | if (skb == NULL) |
1da177e4 LT |
3230 | return -1; |
3231 | ||
3232 | /* Reserve space for headers and set control bits. */ | |
3233 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 LT |
3234 | /* Use a previous sequence. This should cause the other |
3235 | * end to send an ack. Don't queue or clone SKB, just | |
3236 | * send it. | |
3237 | */ | |
a3433f35 | 3238 | tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
7faee5c0 | 3239 | skb_mstamp_get(&skb->skb_mstamp); |
dfb4b9dc | 3240 | return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); |
1da177e4 LT |
3241 | } |
3242 | ||
ee995283 PE |
3243 | void tcp_send_window_probe(struct sock *sk) |
3244 | { | |
3245 | if (sk->sk_state == TCP_ESTABLISHED) { | |
3246 | tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; | |
3247 | tcp_xmit_probe_skb(sk, 0); | |
3248 | } | |
3249 | } | |
3250 | ||
67edfef7 | 3251 | /* Initiate keepalive or window probe from timer. */ |
1da177e4 LT |
3252 | int tcp_write_wakeup(struct sock *sk) |
3253 | { | |
058dc334 IJ |
3254 | struct tcp_sock *tp = tcp_sk(sk); |
3255 | struct sk_buff *skb; | |
1da177e4 | 3256 | |
058dc334 IJ |
3257 | if (sk->sk_state == TCP_CLOSE) |
3258 | return -1; | |
3259 | ||
3260 | if ((skb = tcp_send_head(sk)) != NULL && | |
3261 | before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { | |
3262 | int err; | |
0c54b85f | 3263 | unsigned int mss = tcp_current_mss(sk); |
058dc334 IJ |
3264 | unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
3265 | ||
3266 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
3267 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
3268 | ||
3269 | /* We are probing the opening of a window | |
3270 | * but the window size is != 0 | |
3271 | * must have been a result SWS avoidance ( sender ) | |
3272 | */ | |
3273 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
3274 | skb->len > mss) { | |
3275 | seg_size = min(seg_size, mss); | |
4de075e0 | 3276 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
6cc55e09 | 3277 | if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC)) |
058dc334 IJ |
3278 | return -1; |
3279 | } else if (!tcp_skb_pcount(skb)) | |
3280 | tcp_set_skb_tso_segs(sk, skb, mss); | |
3281 | ||
4de075e0 | 3282 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3283 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
3284 | if (!err) | |
3285 | tcp_event_new_data_sent(sk, skb); | |
3286 | return err; | |
3287 | } else { | |
33f5f57e | 3288 | if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
058dc334 IJ |
3289 | tcp_xmit_probe_skb(sk, 1); |
3290 | return tcp_xmit_probe_skb(sk, 0); | |
1da177e4 | 3291 | } |
1da177e4 LT |
3292 | } |
3293 | ||
3294 | /* A window probe timeout has occurred. If window is not closed send | |
3295 | * a partial packet else a zero probe. | |
3296 | */ | |
3297 | void tcp_send_probe0(struct sock *sk) | |
3298 | { | |
463c84b9 | 3299 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 3300 | struct tcp_sock *tp = tcp_sk(sk); |
fcdd1cf4 | 3301 | unsigned long probe_max; |
1da177e4 LT |
3302 | int err; |
3303 | ||
3304 | err = tcp_write_wakeup(sk); | |
3305 | ||
fe067e8a | 3306 | if (tp->packets_out || !tcp_send_head(sk)) { |
1da177e4 | 3307 | /* Cancel probe timer, if it is not required. */ |
6687e988 | 3308 | icsk->icsk_probes_out = 0; |
463c84b9 | 3309 | icsk->icsk_backoff = 0; |
1da177e4 LT |
3310 | return; |
3311 | } | |
3312 | ||
3313 | if (err <= 0) { | |
463c84b9 ACM |
3314 | if (icsk->icsk_backoff < sysctl_tcp_retries2) |
3315 | icsk->icsk_backoff++; | |
6687e988 | 3316 | icsk->icsk_probes_out++; |
fcdd1cf4 | 3317 | probe_max = TCP_RTO_MAX; |
1da177e4 LT |
3318 | } else { |
3319 | /* If packet was not sent due to local congestion, | |
6687e988 | 3320 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
3321 | * Let local senders to fight for local resources. |
3322 | * | |
3323 | * Use accumulated backoff yet. | |
3324 | */ | |
6687e988 ACM |
3325 | if (!icsk->icsk_probes_out) |
3326 | icsk->icsk_probes_out = 1; | |
fcdd1cf4 | 3327 | probe_max = TCP_RESOURCE_PROBE_INTERVAL; |
1da177e4 | 3328 | } |
fcdd1cf4 ED |
3329 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
3330 | inet_csk_rto_backoff(icsk, probe_max), | |
3331 | TCP_RTO_MAX); | |
1da177e4 | 3332 | } |
5db92c99 OP |
3333 | |
3334 | int tcp_rtx_synack(struct sock *sk, struct request_sock *req) | |
3335 | { | |
3336 | const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; | |
3337 | struct flowi fl; | |
3338 | int res; | |
3339 | ||
3340 | res = af_ops->send_synack(sk, NULL, &fl, req, 0, NULL); | |
3341 | if (!res) { | |
3342 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS); | |
3343 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
3344 | } | |
3345 | return res; | |
3346 | } | |
3347 | EXPORT_SYMBOL(tcp_rtx_synack); |