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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Implementation of the Transmission Control Protocol(TCP). | |
7 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
12 | * Florian La Roche, <flla@stud.uni-sb.de> | |
13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
16 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
18 | * Jorge Cwik, <jorge@laser.satlink.net> | |
19 | */ | |
20 | ||
21 | /* | |
22 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
23 | * : Fragmentation on mtu decrease | |
24 | * : Segment collapse on retransmit | |
25 | * : AF independence | |
26 | * | |
27 | * Linus Torvalds : send_delayed_ack | |
28 | * David S. Miller : Charge memory using the right skb | |
29 | * during syn/ack processing. | |
30 | * David S. Miller : Output engine completely rewritten. | |
31 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
32 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
33 | * J Hadi Salim : ECN support | |
34 | * | |
35 | */ | |
36 | ||
91df42be JP |
37 | #define pr_fmt(fmt) "TCP: " fmt |
38 | ||
1da177e4 LT |
39 | #include <net/tcp.h> |
40 | ||
41 | #include <linux/compiler.h> | |
5a0e3ad6 | 42 | #include <linux/gfp.h> |
1da177e4 | 43 | #include <linux/module.h> |
1da177e4 LT |
44 | |
45 | /* People can turn this off for buggy TCP's found in printers etc. */ | |
ab32ea5d | 46 | int sysctl_tcp_retrans_collapse __read_mostly = 1; |
1da177e4 | 47 | |
09cb105e | 48 | /* People can turn this on to work with those rare, broken TCPs that |
15d99e02 RJ |
49 | * interpret the window field as a signed quantity. |
50 | */ | |
ab32ea5d | 51 | int sysctl_tcp_workaround_signed_windows __read_mostly = 0; |
15d99e02 | 52 | |
46d3ceab ED |
53 | /* Default TSQ limit of two TSO segments */ |
54 | int sysctl_tcp_limit_output_bytes __read_mostly = 131072; | |
55 | ||
1da177e4 LT |
56 | /* This limits the percentage of the congestion window which we |
57 | * will allow a single TSO frame to consume. Building TSO frames | |
58 | * which are too large can cause TCP streams to be bursty. | |
59 | */ | |
ab32ea5d | 60 | int sysctl_tcp_tso_win_divisor __read_mostly = 3; |
1da177e4 | 61 | |
ab32ea5d | 62 | int sysctl_tcp_mtu_probing __read_mostly = 0; |
97b1ce25 | 63 | int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS; |
5d424d5a | 64 | |
35089bb2 | 65 | /* By default, RFC2861 behavior. */ |
ab32ea5d | 66 | int sysctl_tcp_slow_start_after_idle __read_mostly = 1; |
35089bb2 | 67 | |
519855c5 | 68 | int sysctl_tcp_cookie_size __read_mostly = 0; /* TCP_COOKIE_MAX */ |
e6b09cca | 69 | EXPORT_SYMBOL_GPL(sysctl_tcp_cookie_size); |
519855c5 | 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 | |
25985edc | 84 | /* Don't override Nagle indefinitely with F-RTO */ |
8512430e IJ |
85 | if (tp->frto_counter == 2) |
86 | tp->frto_counter = 3; | |
66f5fe62 IJ |
87 | |
88 | tp->packets_out += tcp_skb_pcount(skb); | |
6ba8a3b1 ND |
89 | if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || |
90 | icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) | |
750ea2ba | 91 | tcp_rearm_rto(sk); |
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; | |
1da177e4 | 169 | |
35089bb2 DM |
170 | if (sysctl_tcp_slow_start_after_idle && |
171 | (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) | |
463c84b9 | 172 | tcp_cwnd_restart(sk, __sk_dst_get(sk)); |
1da177e4 LT |
173 | |
174 | tp->lsndtime = now; | |
175 | ||
176 | /* If it is a reply for ato after last received | |
177 | * packet, enter pingpong mode. | |
178 | */ | |
463c84b9 ACM |
179 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
180 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
181 | } |
182 | ||
67edfef7 | 183 | /* Account for an ACK we sent. */ |
40efc6fa | 184 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 185 | { |
463c84b9 ACM |
186 | tcp_dec_quickack_mode(sk, pkts); |
187 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
188 | } |
189 | ||
190 | /* Determine a window scaling and initial window to offer. | |
191 | * Based on the assumption that the given amount of space | |
192 | * will be offered. Store the results in the tp structure. | |
193 | * NOTE: for smooth operation initial space offering should | |
194 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
195 | * This MUST be enforced by all callers. | |
196 | */ | |
197 | void tcp_select_initial_window(int __space, __u32 mss, | |
198 | __u32 *rcv_wnd, __u32 *window_clamp, | |
31d12926 | 199 | int wscale_ok, __u8 *rcv_wscale, |
200 | __u32 init_rcv_wnd) | |
1da177e4 LT |
201 | { |
202 | unsigned int space = (__space < 0 ? 0 : __space); | |
203 | ||
204 | /* If no clamp set the clamp to the max possible scaled window */ | |
205 | if (*window_clamp == 0) | |
206 | (*window_clamp) = (65535 << 14); | |
207 | space = min(*window_clamp, space); | |
208 | ||
209 | /* Quantize space offering to a multiple of mss if possible. */ | |
210 | if (space > mss) | |
211 | space = (space / mss) * mss; | |
212 | ||
213 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
214 | * will break some buggy TCP stacks. If the admin tells us |
215 | * it is likely we could be speaking with such a buggy stack | |
216 | * we will truncate our initial window offering to 32K-1 | |
217 | * unless the remote has sent us a window scaling option, | |
218 | * which we interpret as a sign the remote TCP is not | |
219 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 220 | */ |
15d99e02 RJ |
221 | if (sysctl_tcp_workaround_signed_windows) |
222 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
223 | else | |
224 | (*rcv_wnd) = space; | |
225 | ||
1da177e4 LT |
226 | (*rcv_wscale) = 0; |
227 | if (wscale_ok) { | |
228 | /* Set window scaling on max possible window | |
e905a9ed | 229 | * See RFC1323 for an explanation of the limit to 14 |
1da177e4 LT |
230 | */ |
231 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
316c1592 | 232 | space = min_t(u32, space, *window_clamp); |
1da177e4 LT |
233 | while (space > 65535 && (*rcv_wscale) < 14) { |
234 | space >>= 1; | |
235 | (*rcv_wscale)++; | |
236 | } | |
237 | } | |
238 | ||
356f0398 ND |
239 | /* Set initial window to a value enough for senders starting with |
240 | * initial congestion window of TCP_DEFAULT_INIT_RCVWND. Place | |
241 | * a limit on the initial window when mss is larger than 1460. | |
242 | */ | |
056834d9 | 243 | if (mss > (1 << *rcv_wscale)) { |
356f0398 ND |
244 | int init_cwnd = TCP_DEFAULT_INIT_RCVWND; |
245 | if (mss > 1460) | |
246 | init_cwnd = | |
247 | max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2); | |
31d12926 | 248 | /* when initializing use the value from init_rcv_wnd |
249 | * rather than the default from above | |
250 | */ | |
b1afde60 ND |
251 | if (init_rcv_wnd) |
252 | *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); | |
253 | else | |
254 | *rcv_wnd = min(*rcv_wnd, init_cwnd * mss); | |
1da177e4 LT |
255 | } |
256 | ||
257 | /* Set the clamp no higher than max representable value */ | |
258 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
259 | } | |
4bc2f18b | 260 | EXPORT_SYMBOL(tcp_select_initial_window); |
1da177e4 LT |
261 | |
262 | /* Chose a new window to advertise, update state in tcp_sock for the | |
263 | * socket, and return result with RFC1323 scaling applied. The return | |
264 | * value can be stuffed directly into th->window for an outgoing | |
265 | * frame. | |
266 | */ | |
40efc6fa | 267 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
268 | { |
269 | struct tcp_sock *tp = tcp_sk(sk); | |
270 | u32 cur_win = tcp_receive_window(tp); | |
271 | u32 new_win = __tcp_select_window(sk); | |
272 | ||
273 | /* Never shrink the offered window */ | |
2de979bd | 274 | if (new_win < cur_win) { |
1da177e4 LT |
275 | /* Danger Will Robinson! |
276 | * Don't update rcv_wup/rcv_wnd here or else | |
277 | * we will not be able to advertise a zero | |
278 | * window in time. --DaveM | |
279 | * | |
280 | * Relax Will Robinson. | |
281 | */ | |
607bfbf2 | 282 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
283 | } |
284 | tp->rcv_wnd = new_win; | |
285 | tp->rcv_wup = tp->rcv_nxt; | |
286 | ||
287 | /* Make sure we do not exceed the maximum possible | |
288 | * scaled window. | |
289 | */ | |
15d99e02 | 290 | if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) |
1da177e4 LT |
291 | new_win = min(new_win, MAX_TCP_WINDOW); |
292 | else | |
293 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
294 | ||
295 | /* RFC1323 scaling applied */ | |
296 | new_win >>= tp->rx_opt.rcv_wscale; | |
297 | ||
298 | /* If we advertise zero window, disable fast path. */ | |
299 | if (new_win == 0) | |
300 | tp->pred_flags = 0; | |
301 | ||
302 | return new_win; | |
303 | } | |
304 | ||
67edfef7 | 305 | /* Packet ECN state for a SYN-ACK */ |
cf533ea5 | 306 | static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb) |
bdf1ee5d | 307 | { |
4de075e0 | 308 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
056834d9 | 309 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
4de075e0 | 310 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
bdf1ee5d IJ |
311 | } |
312 | ||
67edfef7 | 313 | /* Packet ECN state for a SYN. */ |
bdf1ee5d IJ |
314 | static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) |
315 | { | |
316 | struct tcp_sock *tp = tcp_sk(sk); | |
317 | ||
318 | tp->ecn_flags = 0; | |
5d134f1c | 319 | if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1) { |
4de075e0 | 320 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
bdf1ee5d IJ |
321 | tp->ecn_flags = TCP_ECN_OK; |
322 | } | |
323 | } | |
324 | ||
325 | static __inline__ void | |
cf533ea5 | 326 | TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th) |
bdf1ee5d IJ |
327 | { |
328 | if (inet_rsk(req)->ecn_ok) | |
329 | th->ece = 1; | |
330 | } | |
331 | ||
67edfef7 AK |
332 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
333 | * be sent. | |
334 | */ | |
bdf1ee5d IJ |
335 | static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, |
336 | int tcp_header_len) | |
337 | { | |
338 | struct tcp_sock *tp = tcp_sk(sk); | |
339 | ||
340 | if (tp->ecn_flags & TCP_ECN_OK) { | |
341 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
342 | if (skb->len != tcp_header_len && | |
343 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
344 | INET_ECN_xmit(sk); | |
056834d9 | 345 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d IJ |
346 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
347 | tcp_hdr(skb)->cwr = 1; | |
348 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; | |
349 | } | |
350 | } else { | |
351 | /* ACK or retransmitted segment: clear ECT|CE */ | |
352 | INET_ECN_dontxmit(sk); | |
353 | } | |
354 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
355 | tcp_hdr(skb)->ece = 1; | |
356 | } | |
357 | } | |
358 | ||
e870a8ef IJ |
359 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
360 | * auto increment end seqno. | |
361 | */ | |
362 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
363 | { | |
2e8e18ef | 364 | skb->ip_summed = CHECKSUM_PARTIAL; |
e870a8ef IJ |
365 | skb->csum = 0; |
366 | ||
4de075e0 | 367 | TCP_SKB_CB(skb)->tcp_flags = flags; |
e870a8ef IJ |
368 | TCP_SKB_CB(skb)->sacked = 0; |
369 | ||
370 | skb_shinfo(skb)->gso_segs = 1; | |
371 | skb_shinfo(skb)->gso_size = 0; | |
372 | skb_shinfo(skb)->gso_type = 0; | |
373 | ||
374 | TCP_SKB_CB(skb)->seq = seq; | |
a3433f35 | 375 | if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
e870a8ef IJ |
376 | seq++; |
377 | TCP_SKB_CB(skb)->end_seq = seq; | |
378 | } | |
379 | ||
a2a385d6 | 380 | static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
33f5f57e IJ |
381 | { |
382 | return tp->snd_una != tp->snd_up; | |
383 | } | |
384 | ||
33ad798c AL |
385 | #define OPTION_SACK_ADVERTISE (1 << 0) |
386 | #define OPTION_TS (1 << 1) | |
387 | #define OPTION_MD5 (1 << 2) | |
89e95a61 | 388 | #define OPTION_WSCALE (1 << 3) |
bd0388ae | 389 | #define OPTION_COOKIE_EXTENSION (1 << 4) |
2100c8d2 | 390 | #define OPTION_FAST_OPEN_COOKIE (1 << 8) |
33ad798c AL |
391 | |
392 | struct tcp_out_options { | |
2100c8d2 YC |
393 | u16 options; /* bit field of OPTION_* */ |
394 | u16 mss; /* 0 to disable */ | |
33ad798c AL |
395 | u8 ws; /* window scale, 0 to disable */ |
396 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 397 | u8 hash_size; /* bytes in hash_location */ |
bd0388ae | 398 | __u8 *hash_location; /* temporary pointer, overloaded */ |
2100c8d2 YC |
399 | __u32 tsval, tsecr; /* need to include OPTION_TS */ |
400 | struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ | |
33ad798c AL |
401 | }; |
402 | ||
bd0388ae WAS |
403 | /* The sysctl int routines are generic, so check consistency here. |
404 | */ | |
405 | static u8 tcp_cookie_size_check(u8 desired) | |
406 | { | |
f1987257 ED |
407 | int cookie_size; |
408 | ||
409 | if (desired > 0) | |
bd0388ae WAS |
410 | /* previously specified */ |
411 | return desired; | |
f1987257 ED |
412 | |
413 | cookie_size = ACCESS_ONCE(sysctl_tcp_cookie_size); | |
414 | if (cookie_size <= 0) | |
bd0388ae WAS |
415 | /* no default specified */ |
416 | return 0; | |
f1987257 ED |
417 | |
418 | if (cookie_size <= TCP_COOKIE_MIN) | |
bd0388ae WAS |
419 | /* value too small, specify minimum */ |
420 | return TCP_COOKIE_MIN; | |
f1987257 ED |
421 | |
422 | if (cookie_size >= TCP_COOKIE_MAX) | |
bd0388ae WAS |
423 | /* value too large, specify maximum */ |
424 | return TCP_COOKIE_MAX; | |
f1987257 ED |
425 | |
426 | if (cookie_size & 1) | |
bd0388ae | 427 | /* 8-bit multiple, illegal, fix it */ |
f1987257 ED |
428 | cookie_size++; |
429 | ||
430 | return (u8)cookie_size; | |
bd0388ae WAS |
431 | } |
432 | ||
67edfef7 AK |
433 | /* Write previously computed TCP options to the packet. |
434 | * | |
435 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
436 | * TCP options, we learned this through the hard way, so be careful here. |
437 | * Luckily we can at least blame others for their non-compliance but from | |
438 | * inter-operatibility perspective it seems that we're somewhat stuck with | |
439 | * the ordering which we have been using if we want to keep working with | |
440 | * those broken things (not that it currently hurts anybody as there isn't | |
441 | * particular reason why the ordering would need to be changed). | |
442 | * | |
443 | * At least SACK_PERM as the first option is known to lead to a disaster | |
444 | * (but it may well be that other scenarios fail similarly). | |
445 | */ | |
33ad798c | 446 | static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
bd0388ae WAS |
447 | struct tcp_out_options *opts) |
448 | { | |
2100c8d2 | 449 | u16 options = opts->options; /* mungable copy */ |
bd0388ae WAS |
450 | |
451 | /* Having both authentication and cookies for security is redundant, | |
452 | * and there's certainly not enough room. Instead, the cookie-less | |
453 | * extension variant is proposed. | |
454 | * | |
455 | * Consider the pessimal case with authentication. The options | |
456 | * could look like: | |
457 | * COOKIE|MD5(20) + MSS(4) + SACK|TS(12) + WSCALE(4) == 40 | |
458 | */ | |
459 | if (unlikely(OPTION_MD5 & options)) { | |
460 | if (unlikely(OPTION_COOKIE_EXTENSION & options)) { | |
461 | *ptr++ = htonl((TCPOPT_COOKIE << 24) | | |
462 | (TCPOLEN_COOKIE_BASE << 16) | | |
463 | (TCPOPT_MD5SIG << 8) | | |
464 | TCPOLEN_MD5SIG); | |
465 | } else { | |
466 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
467 | (TCPOPT_NOP << 16) | | |
468 | (TCPOPT_MD5SIG << 8) | | |
469 | TCPOLEN_MD5SIG); | |
470 | } | |
471 | options &= ~OPTION_COOKIE_EXTENSION; | |
472 | /* overload cookie hash location */ | |
473 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 474 | ptr += 4; |
40efc6fa | 475 | } |
33ad798c | 476 | |
fd6149d3 IJ |
477 | if (unlikely(opts->mss)) { |
478 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
479 | (TCPOLEN_MSS << 16) | | |
480 | opts->mss); | |
481 | } | |
482 | ||
bd0388ae WAS |
483 | if (likely(OPTION_TS & options)) { |
484 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
485 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
486 | (TCPOLEN_SACK_PERM << 16) | | |
487 | (TCPOPT_TIMESTAMP << 8) | | |
488 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 489 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
490 | } else { |
491 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
492 | (TCPOPT_NOP << 16) | | |
493 | (TCPOPT_TIMESTAMP << 8) | | |
494 | TCPOLEN_TIMESTAMP); | |
495 | } | |
496 | *ptr++ = htonl(opts->tsval); | |
497 | *ptr++ = htonl(opts->tsecr); | |
498 | } | |
499 | ||
bd0388ae WAS |
500 | /* Specification requires after timestamp, so do it now. |
501 | * | |
502 | * Consider the pessimal case without authentication. The options | |
503 | * could look like: | |
504 | * MSS(4) + SACK|TS(12) + COOKIE(20) + WSCALE(4) == 40 | |
505 | */ | |
506 | if (unlikely(OPTION_COOKIE_EXTENSION & options)) { | |
507 | __u8 *cookie_copy = opts->hash_location; | |
508 | u8 cookie_size = opts->hash_size; | |
509 | ||
510 | /* 8-bit multiple handled in tcp_cookie_size_check() above, | |
511 | * and elsewhere. | |
512 | */ | |
513 | if (0x2 & cookie_size) { | |
514 | __u8 *p = (__u8 *)ptr; | |
515 | ||
516 | /* 16-bit multiple */ | |
517 | *p++ = TCPOPT_COOKIE; | |
518 | *p++ = TCPOLEN_COOKIE_BASE + cookie_size; | |
519 | *p++ = *cookie_copy++; | |
520 | *p++ = *cookie_copy++; | |
521 | ptr++; | |
522 | cookie_size -= 2; | |
523 | } else { | |
524 | /* 32-bit multiple */ | |
525 | *ptr++ = htonl(((TCPOPT_NOP << 24) | | |
526 | (TCPOPT_NOP << 16) | | |
527 | (TCPOPT_COOKIE << 8) | | |
528 | TCPOLEN_COOKIE_BASE) + | |
529 | cookie_size); | |
530 | } | |
531 | ||
532 | if (cookie_size > 0) { | |
533 | memcpy(ptr, cookie_copy, cookie_size); | |
534 | ptr += (cookie_size / 4); | |
535 | } | |
536 | } | |
537 | ||
538 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
539 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
540 | (TCPOPT_NOP << 16) | | |
541 | (TCPOPT_SACK_PERM << 8) | | |
542 | TCPOLEN_SACK_PERM); | |
543 | } | |
544 | ||
bd0388ae | 545 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
546 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
547 | (TCPOPT_WINDOW << 16) | | |
548 | (TCPOLEN_WINDOW << 8) | | |
549 | opts->ws); | |
550 | } | |
551 | ||
552 | if (unlikely(opts->num_sack_blocks)) { | |
553 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
554 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
555 | int this_sack; |
556 | ||
557 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
558 | (TCPOPT_NOP << 16) | | |
559 | (TCPOPT_SACK << 8) | | |
33ad798c | 560 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 561 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 562 | |
33ad798c AL |
563 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
564 | ++this_sack) { | |
40efc6fa SH |
565 | *ptr++ = htonl(sp[this_sack].start_seq); |
566 | *ptr++ = htonl(sp[this_sack].end_seq); | |
567 | } | |
2de979bd | 568 | |
5861f8e5 | 569 | tp->rx_opt.dsack = 0; |
40efc6fa | 570 | } |
2100c8d2 YC |
571 | |
572 | if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { | |
573 | struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; | |
574 | ||
575 | *ptr++ = htonl((TCPOPT_EXP << 24) | | |
576 | ((TCPOLEN_EXP_FASTOPEN_BASE + foc->len) << 16) | | |
577 | TCPOPT_FASTOPEN_MAGIC); | |
578 | ||
579 | memcpy(ptr, foc->val, foc->len); | |
580 | if ((foc->len & 3) == 2) { | |
581 | u8 *align = ((u8 *)ptr) + foc->len; | |
582 | align[0] = align[1] = TCPOPT_NOP; | |
583 | } | |
584 | ptr += (foc->len + 3) >> 2; | |
585 | } | |
33ad798c AL |
586 | } |
587 | ||
67edfef7 AK |
588 | /* Compute TCP options for SYN packets. This is not the final |
589 | * network wire format yet. | |
590 | */ | |
95c96174 | 591 | static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 592 | struct tcp_out_options *opts, |
cf533ea5 ED |
593 | struct tcp_md5sig_key **md5) |
594 | { | |
33ad798c | 595 | struct tcp_sock *tp = tcp_sk(sk); |
bd0388ae | 596 | struct tcp_cookie_values *cvp = tp->cookie_values; |
95c96174 | 597 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
bd0388ae WAS |
598 | u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ? |
599 | tcp_cookie_size_check(cvp->cookie_desired) : | |
600 | 0; | |
783237e8 | 601 | struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
33ad798c | 602 | |
cfb6eeb4 | 603 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
604 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
605 | if (*md5) { | |
606 | opts->options |= OPTION_MD5; | |
bd0388ae | 607 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
cfb6eeb4 | 608 | } |
33ad798c AL |
609 | #else |
610 | *md5 = NULL; | |
cfb6eeb4 | 611 | #endif |
33ad798c AL |
612 | |
613 | /* We always get an MSS option. The option bytes which will be seen in | |
614 | * normal data packets should timestamps be used, must be in the MSS | |
615 | * advertised. But we subtract them from tp->mss_cache so that | |
616 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
617 | * fact here if necessary. If we don't do this correctly, as a | |
618 | * receiver we won't recognize data packets as being full sized when we | |
619 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
620 | * SACKs don't matter, we never delay an ACK when we have any of those | |
621 | * going out. */ | |
622 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 623 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 624 | |
bb5b7c11 | 625 | if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { |
33ad798c | 626 | opts->options |= OPTION_TS; |
ee684b6f | 627 | opts->tsval = TCP_SKB_CB(skb)->when + tp->tsoffset; |
33ad798c | 628 | opts->tsecr = tp->rx_opt.ts_recent; |
bd0388ae | 629 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 630 | } |
bb5b7c11 | 631 | if (likely(sysctl_tcp_window_scaling)) { |
33ad798c | 632 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 633 | opts->options |= OPTION_WSCALE; |
bd0388ae | 634 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 635 | } |
bb5b7c11 | 636 | if (likely(sysctl_tcp_sack)) { |
33ad798c | 637 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 638 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 639 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
640 | } |
641 | ||
783237e8 YC |
642 | if (fastopen && fastopen->cookie.len >= 0) { |
643 | u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len; | |
644 | need = (need + 3) & ~3U; /* Align to 32 bits */ | |
645 | if (remaining >= need) { | |
646 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
647 | opts->fastopen_cookie = &fastopen->cookie; | |
648 | remaining -= need; | |
649 | tp->syn_fastopen = 1; | |
650 | } | |
651 | } | |
bd0388ae WAS |
652 | /* Note that timestamps are required by the specification. |
653 | * | |
654 | * Odd numbers of bytes are prohibited by the specification, ensuring | |
655 | * that the cookie is 16-bit aligned, and the resulting cookie pair is | |
656 | * 32-bit aligned. | |
657 | */ | |
658 | if (*md5 == NULL && | |
659 | (OPTION_TS & opts->options) && | |
660 | cookie_size > 0) { | |
661 | int need = TCPOLEN_COOKIE_BASE + cookie_size; | |
662 | ||
663 | if (0x2 & need) { | |
664 | /* 32-bit multiple */ | |
665 | need += 2; /* NOPs */ | |
666 | ||
667 | if (need > remaining) { | |
668 | /* try shrinking cookie to fit */ | |
669 | cookie_size -= 2; | |
670 | need -= 4; | |
671 | } | |
672 | } | |
673 | while (need > remaining && TCP_COOKIE_MIN <= cookie_size) { | |
674 | cookie_size -= 4; | |
675 | need -= 4; | |
676 | } | |
677 | if (TCP_COOKIE_MIN <= cookie_size) { | |
678 | opts->options |= OPTION_COOKIE_EXTENSION; | |
679 | opts->hash_location = (__u8 *)&cvp->cookie_pair[0]; | |
680 | opts->hash_size = cookie_size; | |
681 | ||
682 | /* Remember for future incarnations. */ | |
683 | cvp->cookie_desired = cookie_size; | |
684 | ||
685 | if (cvp->cookie_desired != cvp->cookie_pair_size) { | |
686 | /* Currently use random bytes as a nonce, | |
687 | * assuming these are completely unpredictable | |
688 | * by hostile users of the same system. | |
689 | */ | |
690 | get_random_bytes(&cvp->cookie_pair[0], | |
691 | cookie_size); | |
692 | cvp->cookie_pair_size = cookie_size; | |
693 | } | |
694 | ||
695 | remaining -= need; | |
696 | } | |
697 | } | |
698 | return MAX_TCP_OPTION_SPACE - remaining; | |
40efc6fa SH |
699 | } |
700 | ||
67edfef7 | 701 | /* Set up TCP options for SYN-ACKs. */ |
95c96174 | 702 | static unsigned int tcp_synack_options(struct sock *sk, |
33ad798c | 703 | struct request_sock *req, |
95c96174 | 704 | unsigned int mss, struct sk_buff *skb, |
33ad798c | 705 | struct tcp_out_options *opts, |
4957faad | 706 | struct tcp_md5sig_key **md5, |
8336886f JC |
707 | struct tcp_extend_values *xvp, |
708 | struct tcp_fastopen_cookie *foc) | |
4957faad | 709 | { |
33ad798c | 710 | struct inet_request_sock *ireq = inet_rsk(req); |
95c96174 | 711 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
4957faad WAS |
712 | u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ? |
713 | xvp->cookie_plus : | |
714 | 0; | |
33ad798c | 715 | |
cfb6eeb4 | 716 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
717 | *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); |
718 | if (*md5) { | |
719 | opts->options |= OPTION_MD5; | |
4957faad WAS |
720 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
721 | ||
722 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
723 | * options. There was discussion about disabling SACK | |
724 | * rather than TS in order to fit in better with old, | |
725 | * buggy kernels, but that was deemed to be unnecessary. | |
726 | */ | |
de213e5e | 727 | ireq->tstamp_ok &= !ireq->sack_ok; |
cfb6eeb4 | 728 | } |
33ad798c AL |
729 | #else |
730 | *md5 = NULL; | |
cfb6eeb4 | 731 | #endif |
33ad798c | 732 | |
4957faad | 733 | /* We always send an MSS option. */ |
33ad798c | 734 | opts->mss = mss; |
4957faad | 735 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
736 | |
737 | if (likely(ireq->wscale_ok)) { | |
738 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 739 | opts->options |= OPTION_WSCALE; |
4957faad | 740 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 741 | } |
de213e5e | 742 | if (likely(ireq->tstamp_ok)) { |
33ad798c AL |
743 | opts->options |= OPTION_TS; |
744 | opts->tsval = TCP_SKB_CB(skb)->when; | |
745 | opts->tsecr = req->ts_recent; | |
4957faad | 746 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
747 | } |
748 | if (likely(ireq->sack_ok)) { | |
749 | opts->options |= OPTION_SACK_ADVERTISE; | |
de213e5e | 750 | if (unlikely(!ireq->tstamp_ok)) |
4957faad | 751 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c | 752 | } |
8336886f JC |
753 | if (foc != NULL) { |
754 | u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; | |
755 | need = (need + 3) & ~3U; /* Align to 32 bits */ | |
756 | if (remaining >= need) { | |
757 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
758 | opts->fastopen_cookie = foc; | |
759 | remaining -= need; | |
760 | } | |
761 | } | |
4957faad WAS |
762 | /* Similar rationale to tcp_syn_options() applies here, too. |
763 | * If the <SYN> options fit, the same options should fit now! | |
764 | */ | |
765 | if (*md5 == NULL && | |
de213e5e | 766 | ireq->tstamp_ok && |
4957faad WAS |
767 | cookie_plus > TCPOLEN_COOKIE_BASE) { |
768 | int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */ | |
769 | ||
770 | if (0x2 & need) { | |
771 | /* 32-bit multiple */ | |
772 | need += 2; /* NOPs */ | |
773 | } | |
774 | if (need <= remaining) { | |
775 | opts->options |= OPTION_COOKIE_EXTENSION; | |
776 | opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE; | |
777 | remaining -= need; | |
778 | } else { | |
779 | /* There's no error return, so flag it. */ | |
780 | xvp->cookie_out_never = 1; /* true */ | |
781 | opts->hash_size = 0; | |
782 | } | |
783 | } | |
784 | return MAX_TCP_OPTION_SPACE - remaining; | |
33ad798c AL |
785 | } |
786 | ||
67edfef7 AK |
787 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
788 | * final wire format yet. | |
789 | */ | |
95c96174 | 790 | static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 791 | struct tcp_out_options *opts, |
cf533ea5 ED |
792 | struct tcp_md5sig_key **md5) |
793 | { | |
33ad798c AL |
794 | struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; |
795 | struct tcp_sock *tp = tcp_sk(sk); | |
95c96174 | 796 | unsigned int size = 0; |
cabeccbd | 797 | unsigned int eff_sacks; |
33ad798c AL |
798 | |
799 | #ifdef CONFIG_TCP_MD5SIG | |
800 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
801 | if (unlikely(*md5)) { | |
802 | opts->options |= OPTION_MD5; | |
803 | size += TCPOLEN_MD5SIG_ALIGNED; | |
804 | } | |
805 | #else | |
806 | *md5 = NULL; | |
807 | #endif | |
808 | ||
809 | if (likely(tp->rx_opt.tstamp_ok)) { | |
810 | opts->options |= OPTION_TS; | |
ee684b6f | 811 | opts->tsval = tcb ? tcb->when + tp->tsoffset : 0; |
33ad798c AL |
812 | opts->tsecr = tp->rx_opt.ts_recent; |
813 | size += TCPOLEN_TSTAMP_ALIGNED; | |
814 | } | |
815 | ||
cabeccbd IJ |
816 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
817 | if (unlikely(eff_sacks)) { | |
95c96174 | 818 | const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
33ad798c | 819 | opts->num_sack_blocks = |
95c96174 | 820 | min_t(unsigned int, eff_sacks, |
33ad798c AL |
821 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
822 | TCPOLEN_SACK_PERBLOCK); | |
823 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
824 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
825 | } | |
826 | ||
827 | return size; | |
40efc6fa | 828 | } |
1da177e4 | 829 | |
46d3ceab ED |
830 | |
831 | /* TCP SMALL QUEUES (TSQ) | |
832 | * | |
833 | * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) | |
834 | * to reduce RTT and bufferbloat. | |
835 | * We do this using a special skb destructor (tcp_wfree). | |
836 | * | |
837 | * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb | |
838 | * needs to be reallocated in a driver. | |
839 | * The invariant being skb->truesize substracted from sk->sk_wmem_alloc | |
840 | * | |
841 | * Since transmit from skb destructor is forbidden, we use a tasklet | |
842 | * to process all sockets that eventually need to send more skbs. | |
843 | * We use one tasklet per cpu, with its own queue of sockets. | |
844 | */ | |
845 | struct tsq_tasklet { | |
846 | struct tasklet_struct tasklet; | |
847 | struct list_head head; /* queue of tcp sockets */ | |
848 | }; | |
849 | static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); | |
850 | ||
6f458dfb ED |
851 | static void tcp_tsq_handler(struct sock *sk) |
852 | { | |
853 | if ((1 << sk->sk_state) & | |
854 | (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | | |
855 | TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) | |
856 | tcp_write_xmit(sk, tcp_current_mss(sk), 0, 0, GFP_ATOMIC); | |
857 | } | |
46d3ceab ED |
858 | /* |
859 | * One tasklest per cpu tries to send more skbs. | |
860 | * We run in tasklet context but need to disable irqs when | |
861 | * transfering tsq->head because tcp_wfree() might | |
862 | * interrupt us (non NAPI drivers) | |
863 | */ | |
864 | static void tcp_tasklet_func(unsigned long data) | |
865 | { | |
866 | struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; | |
867 | LIST_HEAD(list); | |
868 | unsigned long flags; | |
869 | struct list_head *q, *n; | |
870 | struct tcp_sock *tp; | |
871 | struct sock *sk; | |
872 | ||
873 | local_irq_save(flags); | |
874 | list_splice_init(&tsq->head, &list); | |
875 | local_irq_restore(flags); | |
876 | ||
877 | list_for_each_safe(q, n, &list) { | |
878 | tp = list_entry(q, struct tcp_sock, tsq_node); | |
879 | list_del(&tp->tsq_node); | |
880 | ||
881 | sk = (struct sock *)tp; | |
882 | bh_lock_sock(sk); | |
883 | ||
884 | if (!sock_owned_by_user(sk)) { | |
6f458dfb | 885 | tcp_tsq_handler(sk); |
46d3ceab ED |
886 | } else { |
887 | /* defer the work to tcp_release_cb() */ | |
6f458dfb | 888 | set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags); |
46d3ceab ED |
889 | } |
890 | bh_unlock_sock(sk); | |
891 | ||
892 | clear_bit(TSQ_QUEUED, &tp->tsq_flags); | |
893 | sk_free(sk); | |
894 | } | |
895 | } | |
896 | ||
6f458dfb ED |
897 | #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) | \ |
898 | (1UL << TCP_WRITE_TIMER_DEFERRED) | \ | |
563d34d0 ED |
899 | (1UL << TCP_DELACK_TIMER_DEFERRED) | \ |
900 | (1UL << TCP_MTU_REDUCED_DEFERRED)) | |
46d3ceab ED |
901 | /** |
902 | * tcp_release_cb - tcp release_sock() callback | |
903 | * @sk: socket | |
904 | * | |
905 | * called from release_sock() to perform protocol dependent | |
906 | * actions before socket release. | |
907 | */ | |
908 | void tcp_release_cb(struct sock *sk) | |
909 | { | |
910 | struct tcp_sock *tp = tcp_sk(sk); | |
6f458dfb | 911 | unsigned long flags, nflags; |
46d3ceab | 912 | |
6f458dfb ED |
913 | /* perform an atomic operation only if at least one flag is set */ |
914 | do { | |
915 | flags = tp->tsq_flags; | |
916 | if (!(flags & TCP_DEFERRED_ALL)) | |
917 | return; | |
918 | nflags = flags & ~TCP_DEFERRED_ALL; | |
919 | } while (cmpxchg(&tp->tsq_flags, flags, nflags) != flags); | |
920 | ||
921 | if (flags & (1UL << TCP_TSQ_DEFERRED)) | |
922 | tcp_tsq_handler(sk); | |
923 | ||
144d56e9 | 924 | if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED)) { |
6f458dfb | 925 | tcp_write_timer_handler(sk); |
144d56e9 ED |
926 | __sock_put(sk); |
927 | } | |
928 | if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED)) { | |
6f458dfb | 929 | tcp_delack_timer_handler(sk); |
144d56e9 ED |
930 | __sock_put(sk); |
931 | } | |
932 | if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED)) { | |
563d34d0 | 933 | sk->sk_prot->mtu_reduced(sk); |
144d56e9 ED |
934 | __sock_put(sk); |
935 | } | |
46d3ceab ED |
936 | } |
937 | EXPORT_SYMBOL(tcp_release_cb); | |
938 | ||
939 | void __init tcp_tasklet_init(void) | |
940 | { | |
941 | int i; | |
942 | ||
943 | for_each_possible_cpu(i) { | |
944 | struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); | |
945 | ||
946 | INIT_LIST_HEAD(&tsq->head); | |
947 | tasklet_init(&tsq->tasklet, | |
948 | tcp_tasklet_func, | |
949 | (unsigned long)tsq); | |
950 | } | |
951 | } | |
952 | ||
953 | /* | |
954 | * Write buffer destructor automatically called from kfree_skb. | |
955 | * We cant xmit new skbs from this context, as we might already | |
956 | * hold qdisc lock. | |
957 | */ | |
8e7dfbc8 | 958 | static void tcp_wfree(struct sk_buff *skb) |
46d3ceab ED |
959 | { |
960 | struct sock *sk = skb->sk; | |
961 | struct tcp_sock *tp = tcp_sk(sk); | |
962 | ||
963 | if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && | |
964 | !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { | |
965 | unsigned long flags; | |
966 | struct tsq_tasklet *tsq; | |
967 | ||
968 | /* Keep a ref on socket. | |
969 | * This last ref will be released in tcp_tasklet_func() | |
970 | */ | |
971 | atomic_sub(skb->truesize - 1, &sk->sk_wmem_alloc); | |
972 | ||
973 | /* queue this socket to tasklet queue */ | |
974 | local_irq_save(flags); | |
975 | tsq = &__get_cpu_var(tsq_tasklet); | |
976 | list_add(&tp->tsq_node, &tsq->head); | |
977 | tasklet_schedule(&tsq->tasklet); | |
978 | local_irq_restore(flags); | |
979 | } else { | |
980 | sock_wfree(skb); | |
981 | } | |
982 | } | |
983 | ||
1da177e4 LT |
984 | /* This routine actually transmits TCP packets queued in by |
985 | * tcp_do_sendmsg(). This is used by both the initial | |
986 | * transmission and possible later retransmissions. | |
987 | * All SKB's seen here are completely headerless. It is our | |
988 | * job to build the TCP header, and pass the packet down to | |
989 | * IP so it can do the same plus pass the packet off to the | |
990 | * device. | |
991 | * | |
992 | * We are working here with either a clone of the original | |
993 | * SKB, or a fresh unique copy made by the retransmit engine. | |
994 | */ | |
056834d9 IJ |
995 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
996 | gfp_t gfp_mask) | |
1da177e4 | 997 | { |
dfb4b9dc DM |
998 | const struct inet_connection_sock *icsk = inet_csk(sk); |
999 | struct inet_sock *inet; | |
1000 | struct tcp_sock *tp; | |
1001 | struct tcp_skb_cb *tcb; | |
33ad798c | 1002 | struct tcp_out_options opts; |
95c96174 | 1003 | unsigned int tcp_options_size, tcp_header_size; |
cfb6eeb4 | 1004 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 1005 | struct tcphdr *th; |
dfb4b9dc DM |
1006 | int err; |
1007 | ||
1008 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
1009 | ||
1010 | /* If congestion control is doing timestamping, we must | |
1011 | * take such a timestamp before we potentially clone/copy. | |
1012 | */ | |
164891aa | 1013 | if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) |
dfb4b9dc DM |
1014 | __net_timestamp(skb); |
1015 | ||
1016 | if (likely(clone_it)) { | |
1017 | if (unlikely(skb_cloned(skb))) | |
1018 | skb = pskb_copy(skb, gfp_mask); | |
1019 | else | |
1020 | skb = skb_clone(skb, gfp_mask); | |
1021 | if (unlikely(!skb)) | |
1022 | return -ENOBUFS; | |
1023 | } | |
1da177e4 | 1024 | |
dfb4b9dc DM |
1025 | inet = inet_sk(sk); |
1026 | tp = tcp_sk(sk); | |
1027 | tcb = TCP_SKB_CB(skb); | |
33ad798c | 1028 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 1029 | |
4de075e0 | 1030 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) |
33ad798c AL |
1031 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
1032 | else | |
1033 | tcp_options_size = tcp_established_options(sk, skb, &opts, | |
1034 | &md5); | |
1035 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); | |
e905a9ed | 1036 | |
3853b584 | 1037 | if (tcp_packets_in_flight(tp) == 0) { |
dfb4b9dc | 1038 | tcp_ca_event(sk, CA_EVENT_TX_START); |
3853b584 TH |
1039 | skb->ooo_okay = 1; |
1040 | } else | |
1041 | skb->ooo_okay = 0; | |
dfb4b9dc | 1042 | |
aa8223c7 ACM |
1043 | skb_push(skb, tcp_header_size); |
1044 | skb_reset_transport_header(skb); | |
46d3ceab ED |
1045 | |
1046 | skb_orphan(skb); | |
1047 | skb->sk = sk; | |
1048 | skb->destructor = (sysctl_tcp_limit_output_bytes > 0) ? | |
1049 | tcp_wfree : sock_wfree; | |
1050 | atomic_add(skb->truesize, &sk->sk_wmem_alloc); | |
dfb4b9dc DM |
1051 | |
1052 | /* Build TCP header and checksum it. */ | |
aa8223c7 | 1053 | th = tcp_hdr(skb); |
c720c7e8 ED |
1054 | th->source = inet->inet_sport; |
1055 | th->dest = inet->inet_dport; | |
dfb4b9dc DM |
1056 | th->seq = htonl(tcb->seq); |
1057 | th->ack_seq = htonl(tp->rcv_nxt); | |
df7a3b07 | 1058 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
4de075e0 | 1059 | tcb->tcp_flags); |
dfb4b9dc | 1060 | |
4de075e0 | 1061 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
dfb4b9dc DM |
1062 | /* RFC1323: The window in SYN & SYN/ACK segments |
1063 | * is never scaled. | |
1064 | */ | |
600ff0c2 | 1065 | th->window = htons(min(tp->rcv_wnd, 65535U)); |
dfb4b9dc DM |
1066 | } else { |
1067 | th->window = htons(tcp_select_window(sk)); | |
1068 | } | |
1069 | th->check = 0; | |
1070 | th->urg_ptr = 0; | |
1da177e4 | 1071 | |
33f5f57e | 1072 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
1073 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
1074 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
1075 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
1076 | th->urg = 1; | |
1077 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
0eae88f3 | 1078 | th->urg_ptr = htons(0xFFFF); |
7691367d HX |
1079 | th->urg = 1; |
1080 | } | |
dfb4b9dc | 1081 | } |
1da177e4 | 1082 | |
bd0388ae | 1083 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
4de075e0 | 1084 | if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) |
9e412ba7 | 1085 | TCP_ECN_send(sk, skb, tcp_header_size); |
1da177e4 | 1086 | |
cfb6eeb4 YH |
1087 | #ifdef CONFIG_TCP_MD5SIG |
1088 | /* Calculate the MD5 hash, as we have all we need now */ | |
1089 | if (md5) { | |
a465419b | 1090 | sk_nocaps_add(sk, NETIF_F_GSO_MASK); |
bd0388ae | 1091 | tp->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 1092 | md5, sk, NULL, skb); |
cfb6eeb4 YH |
1093 | } |
1094 | #endif | |
1095 | ||
bb296246 | 1096 | icsk->icsk_af_ops->send_check(sk, skb); |
1da177e4 | 1097 | |
4de075e0 | 1098 | if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
dfb4b9dc | 1099 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); |
1da177e4 | 1100 | |
dfb4b9dc | 1101 | if (skb->len != tcp_header_size) |
cf533ea5 | 1102 | tcp_event_data_sent(tp, sk); |
1da177e4 | 1103 | |
bd37a088 | 1104 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
aa2ea058 TH |
1105 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
1106 | tcp_skb_pcount(skb)); | |
1da177e4 | 1107 | |
d9d8da80 | 1108 | err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl); |
83de47cd | 1109 | if (likely(err <= 0)) |
dfb4b9dc DM |
1110 | return err; |
1111 | ||
3cfe3baa | 1112 | tcp_enter_cwr(sk, 1); |
dfb4b9dc | 1113 | |
b9df3cb8 | 1114 | return net_xmit_eval(err); |
1da177e4 LT |
1115 | } |
1116 | ||
67edfef7 | 1117 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
1118 | * |
1119 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
1120 | * otherwise socket can stall. | |
1121 | */ | |
1122 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
1123 | { | |
1124 | struct tcp_sock *tp = tcp_sk(sk); | |
1125 | ||
1126 | /* Advance write_seq and place onto the write_queue. */ | |
1127 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
1128 | skb_header_release(skb); | |
fe067e8a | 1129 | tcp_add_write_queue_tail(sk, skb); |
3ab224be HA |
1130 | sk->sk_wmem_queued += skb->truesize; |
1131 | sk_mem_charge(sk, skb->truesize); | |
1da177e4 LT |
1132 | } |
1133 | ||
67edfef7 | 1134 | /* Initialize TSO segments for a packet. */ |
cf533ea5 | 1135 | static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, |
056834d9 | 1136 | unsigned int mss_now) |
f6302d1d | 1137 | { |
8e5b9dda HX |
1138 | if (skb->len <= mss_now || !sk_can_gso(sk) || |
1139 | skb->ip_summed == CHECKSUM_NONE) { | |
f6302d1d DM |
1140 | /* Avoid the costly divide in the normal |
1141 | * non-TSO case. | |
1142 | */ | |
7967168c HX |
1143 | skb_shinfo(skb)->gso_segs = 1; |
1144 | skb_shinfo(skb)->gso_size = 0; | |
c9af6db4 | 1145 | skb_shinfo(skb)->gso_type = 0; |
f6302d1d | 1146 | } else { |
356f89e1 | 1147 | skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now); |
7967168c | 1148 | skb_shinfo(skb)->gso_size = mss_now; |
c9af6db4 | 1149 | skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
1da177e4 LT |
1150 | } |
1151 | } | |
1152 | ||
91fed7a1 | 1153 | /* When a modification to fackets out becomes necessary, we need to check |
68f8353b | 1154 | * skb is counted to fackets_out or not. |
91fed7a1 | 1155 | */ |
cf533ea5 | 1156 | static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, |
91fed7a1 IJ |
1157 | int decr) |
1158 | { | |
a47e5a98 IJ |
1159 | struct tcp_sock *tp = tcp_sk(sk); |
1160 | ||
dc86967b | 1161 | if (!tp->sacked_out || tcp_is_reno(tp)) |
91fed7a1 IJ |
1162 | return; |
1163 | ||
6859d494 | 1164 | if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) |
91fed7a1 | 1165 | tp->fackets_out -= decr; |
91fed7a1 IJ |
1166 | } |
1167 | ||
797108d1 IJ |
1168 | /* Pcount in the middle of the write queue got changed, we need to do various |
1169 | * tweaks to fix counters | |
1170 | */ | |
cf533ea5 | 1171 | static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
797108d1 IJ |
1172 | { |
1173 | struct tcp_sock *tp = tcp_sk(sk); | |
1174 | ||
1175 | tp->packets_out -= decr; | |
1176 | ||
1177 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
1178 | tp->sacked_out -= decr; | |
1179 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
1180 | tp->retrans_out -= decr; | |
1181 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
1182 | tp->lost_out -= decr; | |
1183 | ||
1184 | /* Reno case is special. Sigh... */ | |
1185 | if (tcp_is_reno(tp) && decr > 0) | |
1186 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
1187 | ||
1188 | tcp_adjust_fackets_out(sk, skb, decr); | |
1189 | ||
1190 | if (tp->lost_skb_hint && | |
1191 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
52cf3cc8 | 1192 | (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) |
797108d1 IJ |
1193 | tp->lost_cnt_hint -= decr; |
1194 | ||
1195 | tcp_verify_left_out(tp); | |
1196 | } | |
1197 | ||
1da177e4 LT |
1198 | /* Function to create two new TCP segments. Shrinks the given segment |
1199 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 1200 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
1201 | * Remember, these are still headerless SKBs at this point. |
1202 | */ | |
056834d9 IJ |
1203 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, |
1204 | unsigned int mss_now) | |
1da177e4 LT |
1205 | { |
1206 | struct tcp_sock *tp = tcp_sk(sk); | |
1207 | struct sk_buff *buff; | |
6475be16 | 1208 | int nsize, old_factor; |
b60b49ea | 1209 | int nlen; |
9ce01461 | 1210 | u8 flags; |
1da177e4 | 1211 | |
2fceec13 IJ |
1212 | if (WARN_ON(len > skb->len)) |
1213 | return -EINVAL; | |
6a438bbe | 1214 | |
1da177e4 LT |
1215 | nsize = skb_headlen(skb) - len; |
1216 | if (nsize < 0) | |
1217 | nsize = 0; | |
1218 | ||
1219 | if (skb_cloned(skb) && | |
1220 | skb_is_nonlinear(skb) && | |
1221 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
1222 | return -ENOMEM; | |
1223 | ||
1224 | /* Get a new skb... force flag on. */ | |
1225 | buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); | |
1226 | if (buff == NULL) | |
1227 | return -ENOMEM; /* We'll just try again later. */ | |
ef5cb973 | 1228 | |
3ab224be HA |
1229 | sk->sk_wmem_queued += buff->truesize; |
1230 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea HX |
1231 | nlen = skb->len - len - nsize; |
1232 | buff->truesize += nlen; | |
1233 | skb->truesize -= nlen; | |
1da177e4 LT |
1234 | |
1235 | /* Correct the sequence numbers. */ | |
1236 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1237 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1238 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1239 | ||
1240 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1241 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1242 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1243 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
e14c3caf | 1244 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 | 1245 | |
84fa7933 | 1246 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { |
1da177e4 | 1247 | /* Copy and checksum data tail into the new buffer. */ |
056834d9 IJ |
1248 | buff->csum = csum_partial_copy_nocheck(skb->data + len, |
1249 | skb_put(buff, nsize), | |
1da177e4 LT |
1250 | nsize, 0); |
1251 | ||
1252 | skb_trim(skb, len); | |
1253 | ||
1254 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
1255 | } else { | |
84fa7933 | 1256 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1257 | skb_split(skb, buff, len); |
1258 | } | |
1259 | ||
1260 | buff->ip_summed = skb->ip_summed; | |
1261 | ||
1262 | /* Looks stupid, but our code really uses when of | |
1263 | * skbs, which it never sent before. --ANK | |
1264 | */ | |
1265 | TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; | |
a61bbcf2 | 1266 | buff->tstamp = skb->tstamp; |
1da177e4 | 1267 | |
6475be16 DM |
1268 | old_factor = tcp_skb_pcount(skb); |
1269 | ||
1da177e4 | 1270 | /* Fix up tso_factor for both original and new SKB. */ |
846998ae DM |
1271 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1272 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
1da177e4 | 1273 | |
6475be16 DM |
1274 | /* If this packet has been sent out already, we must |
1275 | * adjust the various packet counters. | |
1276 | */ | |
cf0b450c | 1277 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1278 | int diff = old_factor - tcp_skb_pcount(skb) - |
1279 | tcp_skb_pcount(buff); | |
1da177e4 | 1280 | |
797108d1 IJ |
1281 | if (diff) |
1282 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1283 | } |
1284 | ||
1285 | /* Link BUFF into the send queue. */ | |
f44b5271 | 1286 | skb_header_release(buff); |
fe067e8a | 1287 | tcp_insert_write_queue_after(skb, buff, sk); |
1da177e4 LT |
1288 | |
1289 | return 0; | |
1290 | } | |
1291 | ||
1292 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
1293 | * eventually). The difference is that pulled data not copied, but | |
1294 | * immediately discarded. | |
1295 | */ | |
f2911969 | 1296 | static void __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 LT |
1297 | { |
1298 | int i, k, eat; | |
1299 | ||
4fa48bf3 ED |
1300 | eat = min_t(int, len, skb_headlen(skb)); |
1301 | if (eat) { | |
1302 | __skb_pull(skb, eat); | |
22b4a4f2 | 1303 | skb->avail_size -= eat; |
4fa48bf3 ED |
1304 | len -= eat; |
1305 | if (!len) | |
1306 | return; | |
1307 | } | |
1da177e4 LT |
1308 | eat = len; |
1309 | k = 0; | |
056834d9 | 1310 | for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { |
9e903e08 ED |
1311 | int size = skb_frag_size(&skb_shinfo(skb)->frags[i]); |
1312 | ||
1313 | if (size <= eat) { | |
aff65da0 | 1314 | skb_frag_unref(skb, i); |
9e903e08 | 1315 | eat -= size; |
1da177e4 LT |
1316 | } else { |
1317 | skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; | |
1318 | if (eat) { | |
1319 | skb_shinfo(skb)->frags[k].page_offset += eat; | |
9e903e08 | 1320 | skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat); |
1da177e4 LT |
1321 | eat = 0; |
1322 | } | |
1323 | k++; | |
1324 | } | |
1325 | } | |
1326 | skb_shinfo(skb)->nr_frags = k; | |
1327 | ||
27a884dc | 1328 | skb_reset_tail_pointer(skb); |
1da177e4 LT |
1329 | skb->data_len -= len; |
1330 | skb->len = skb->data_len; | |
1da177e4 LT |
1331 | } |
1332 | ||
67edfef7 | 1333 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1334 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1335 | { | |
14bbd6a5 | 1336 | if (skb_unclone(skb, GFP_ATOMIC)) |
1da177e4 LT |
1337 | return -ENOMEM; |
1338 | ||
4fa48bf3 | 1339 | __pskb_trim_head(skb, len); |
1da177e4 LT |
1340 | |
1341 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 1342 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1343 | |
1344 | skb->truesize -= len; | |
1345 | sk->sk_wmem_queued -= len; | |
3ab224be | 1346 | sk_mem_uncharge(sk, len); |
1da177e4 LT |
1347 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); |
1348 | ||
5b35e1e6 | 1349 | /* Any change of skb->len requires recalculation of tso factor. */ |
1da177e4 | 1350 | if (tcp_skb_pcount(skb) > 1) |
5b35e1e6 | 1351 | tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); |
1da177e4 LT |
1352 | |
1353 | return 0; | |
1354 | } | |
1355 | ||
1b63edd6 YC |
1356 | /* Calculate MSS not accounting any TCP options. */ |
1357 | static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
5d424d5a | 1358 | { |
cf533ea5 ED |
1359 | const struct tcp_sock *tp = tcp_sk(sk); |
1360 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1361 | int mss_now; |
1362 | ||
1363 | /* Calculate base mss without TCP options: | |
1364 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1365 | */ | |
1366 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1367 | ||
67469601 ED |
1368 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1369 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1370 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1371 | ||
1372 | if (dst && dst_allfrag(dst)) | |
1373 | mss_now -= icsk->icsk_af_ops->net_frag_header_len; | |
1374 | } | |
1375 | ||
5d424d5a JH |
1376 | /* Clamp it (mss_clamp does not include tcp options) */ |
1377 | if (mss_now > tp->rx_opt.mss_clamp) | |
1378 | mss_now = tp->rx_opt.mss_clamp; | |
1379 | ||
1380 | /* Now subtract optional transport overhead */ | |
1381 | mss_now -= icsk->icsk_ext_hdr_len; | |
1382 | ||
1383 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
1384 | if (mss_now < 48) | |
1385 | mss_now = 48; | |
5d424d5a JH |
1386 | return mss_now; |
1387 | } | |
1388 | ||
1b63edd6 YC |
1389 | /* Calculate MSS. Not accounting for SACKs here. */ |
1390 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
1391 | { | |
1392 | /* Subtract TCP options size, not including SACKs */ | |
1393 | return __tcp_mtu_to_mss(sk, pmtu) - | |
1394 | (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); | |
1395 | } | |
1396 | ||
5d424d5a | 1397 | /* Inverse of above */ |
67469601 | 1398 | int tcp_mss_to_mtu(struct sock *sk, int mss) |
5d424d5a | 1399 | { |
cf533ea5 ED |
1400 | const struct tcp_sock *tp = tcp_sk(sk); |
1401 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1402 | int mtu; |
1403 | ||
1404 | mtu = mss + | |
1405 | tp->tcp_header_len + | |
1406 | icsk->icsk_ext_hdr_len + | |
1407 | icsk->icsk_af_ops->net_header_len; | |
1408 | ||
67469601 ED |
1409 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1410 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1411 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1412 | ||
1413 | if (dst && dst_allfrag(dst)) | |
1414 | mtu += icsk->icsk_af_ops->net_frag_header_len; | |
1415 | } | |
5d424d5a JH |
1416 | return mtu; |
1417 | } | |
1418 | ||
67edfef7 | 1419 | /* MTU probing init per socket */ |
5d424d5a JH |
1420 | void tcp_mtup_init(struct sock *sk) |
1421 | { | |
1422 | struct tcp_sock *tp = tcp_sk(sk); | |
1423 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1424 | ||
1425 | icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; | |
1426 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + | |
e905a9ed | 1427 | icsk->icsk_af_ops->net_header_len; |
5d424d5a JH |
1428 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); |
1429 | icsk->icsk_mtup.probe_size = 0; | |
1430 | } | |
4bc2f18b | 1431 | EXPORT_SYMBOL(tcp_mtup_init); |
5d424d5a | 1432 | |
1da177e4 LT |
1433 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1434 | ||
1435 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1436 | for TCP options, but includes only bare TCP header. | |
1437 | ||
1438 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1439 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1440 | It also does not include TCP options. |
1441 | ||
d83d8461 | 1442 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1443 | |
1444 | tp->mss_cache is current effective sending mss, including | |
1445 | all tcp options except for SACKs. It is evaluated, | |
1446 | taking into account current pmtu, but never exceeds | |
1447 | tp->rx_opt.mss_clamp. | |
1448 | ||
1449 | NOTE1. rfc1122 clearly states that advertised MSS | |
1450 | DOES NOT include either tcp or ip options. | |
1451 | ||
d83d8461 ACM |
1452 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1453 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1454 | */ |
1da177e4 LT |
1455 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1456 | { | |
1457 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1458 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1459 | int mss_now; |
1da177e4 | 1460 | |
5d424d5a JH |
1461 | if (icsk->icsk_mtup.search_high > pmtu) |
1462 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1463 | |
5d424d5a | 1464 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1465 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1466 | |
1467 | /* And store cached results */ | |
d83d8461 | 1468 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1469 | if (icsk->icsk_mtup.enabled) |
1470 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1471 | tp->mss_cache = mss_now; |
1da177e4 LT |
1472 | |
1473 | return mss_now; | |
1474 | } | |
4bc2f18b | 1475 | EXPORT_SYMBOL(tcp_sync_mss); |
1da177e4 LT |
1476 | |
1477 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1478 | * and even PMTU discovery events into account. | |
1da177e4 | 1479 | */ |
0c54b85f | 1480 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 | 1481 | { |
cf533ea5 ED |
1482 | const struct tcp_sock *tp = tcp_sk(sk); |
1483 | const struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1484 | u32 mss_now; |
95c96174 | 1485 | unsigned int header_len; |
33ad798c AL |
1486 | struct tcp_out_options opts; |
1487 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1488 | |
1489 | mss_now = tp->mss_cache; | |
1490 | ||
1da177e4 LT |
1491 | if (dst) { |
1492 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1493 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1494 | mss_now = tcp_sync_mss(sk, mtu); |
1495 | } | |
1496 | ||
33ad798c AL |
1497 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1498 | sizeof(struct tcphdr); | |
1499 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1500 | * some common options. If this is an odd packet (because we have SACK | |
1501 | * blocks etc) then our calculated header_len will be different, and | |
1502 | * we have to adjust mss_now correspondingly */ | |
1503 | if (header_len != tp->tcp_header_len) { | |
1504 | int delta = (int) header_len - tp->tcp_header_len; | |
1505 | mss_now -= delta; | |
1506 | } | |
cfb6eeb4 | 1507 | |
1da177e4 LT |
1508 | return mss_now; |
1509 | } | |
1510 | ||
a762a980 | 1511 | /* Congestion window validation. (RFC2861) */ |
9e412ba7 | 1512 | static void tcp_cwnd_validate(struct sock *sk) |
a762a980 | 1513 | { |
9e412ba7 | 1514 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1515 | |
d436d686 | 1516 | if (tp->packets_out >= tp->snd_cwnd) { |
a762a980 DM |
1517 | /* Network is feed fully. */ |
1518 | tp->snd_cwnd_used = 0; | |
1519 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1520 | } else { | |
1521 | /* Network starves. */ | |
1522 | if (tp->packets_out > tp->snd_cwnd_used) | |
1523 | tp->snd_cwnd_used = tp->packets_out; | |
1524 | ||
15d33c07 DM |
1525 | if (sysctl_tcp_slow_start_after_idle && |
1526 | (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) | |
a762a980 DM |
1527 | tcp_cwnd_application_limited(sk); |
1528 | } | |
1529 | } | |
1530 | ||
0e3a4803 IJ |
1531 | /* Returns the portion of skb which can be sent right away without |
1532 | * introducing MSS oddities to segment boundaries. In rare cases where | |
1533 | * mss_now != mss_cache, we will request caller to create a small skb | |
1534 | * per input skb which could be mostly avoided here (if desired). | |
5ea3a748 IJ |
1535 | * |
1536 | * We explicitly want to create a request for splitting write queue tail | |
1537 | * to a small skb for Nagle purposes while avoiding unnecessary modulos, | |
1538 | * thus all the complexity (cwnd_len is always MSS multiple which we | |
1539 | * return whenever allowed by the other factors). Basically we need the | |
1540 | * modulo only when the receiver window alone is the limiting factor or | |
1541 | * when we would be allowed to send the split-due-to-Nagle skb fully. | |
0e3a4803 | 1542 | */ |
cf533ea5 | 1543 | static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb, |
1485348d | 1544 | unsigned int mss_now, unsigned int max_segs) |
c1b4a7e6 | 1545 | { |
cf533ea5 | 1546 | const struct tcp_sock *tp = tcp_sk(sk); |
1485348d | 1547 | u32 needed, window, max_len; |
c1b4a7e6 | 1548 | |
90840def | 1549 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
1485348d | 1550 | max_len = mss_now * max_segs; |
0e3a4803 | 1551 | |
1485348d BH |
1552 | if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
1553 | return max_len; | |
0e3a4803 | 1554 | |
5ea3a748 IJ |
1555 | needed = min(skb->len, window); |
1556 | ||
1485348d BH |
1557 | if (max_len <= needed) |
1558 | return max_len; | |
0e3a4803 | 1559 | |
0e3a4803 | 1560 | return needed - needed % mss_now; |
c1b4a7e6 DM |
1561 | } |
1562 | ||
1563 | /* Can at least one segment of SKB be sent right now, according to the | |
1564 | * congestion window rules? If so, return how many segments are allowed. | |
1565 | */ | |
cf533ea5 ED |
1566 | static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
1567 | const struct sk_buff *skb) | |
c1b4a7e6 DM |
1568 | { |
1569 | u32 in_flight, cwnd; | |
1570 | ||
1571 | /* Don't be strict about the congestion window for the final FIN. */ | |
4de075e0 ED |
1572 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
1573 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
1574 | return 1; |
1575 | ||
1576 | in_flight = tcp_packets_in_flight(tp); | |
1577 | cwnd = tp->snd_cwnd; | |
1578 | if (in_flight < cwnd) | |
1579 | return (cwnd - in_flight); | |
1580 | ||
1581 | return 0; | |
1582 | } | |
1583 | ||
b595076a | 1584 | /* Initialize TSO state of a skb. |
67edfef7 | 1585 | * This must be invoked the first time we consider transmitting |
c1b4a7e6 DM |
1586 | * SKB onto the wire. |
1587 | */ | |
cf533ea5 | 1588 | static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, |
056834d9 | 1589 | unsigned int mss_now) |
c1b4a7e6 DM |
1590 | { |
1591 | int tso_segs = tcp_skb_pcount(skb); | |
1592 | ||
f8269a49 | 1593 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
846998ae | 1594 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
1595 | tso_segs = tcp_skb_pcount(skb); |
1596 | } | |
1597 | return tso_segs; | |
1598 | } | |
1599 | ||
67edfef7 | 1600 | /* Minshall's variant of the Nagle send check. */ |
a2a385d6 | 1601 | static inline bool tcp_minshall_check(const struct tcp_sock *tp) |
c1b4a7e6 | 1602 | { |
09cb105e | 1603 | return after(tp->snd_sml, tp->snd_una) && |
c1b4a7e6 DM |
1604 | !after(tp->snd_sml, tp->snd_nxt); |
1605 | } | |
1606 | ||
a2a385d6 | 1607 | /* Return false, if packet can be sent now without violation Nagle's rules: |
c1b4a7e6 DM |
1608 | * 1. It is full sized. |
1609 | * 2. Or it contains FIN. (already checked by caller) | |
6d67e9be | 1610 | * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. |
c1b4a7e6 DM |
1611 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. |
1612 | * With Minshall's modification: all sent small packets are ACKed. | |
1613 | */ | |
a2a385d6 | 1614 | static inline bool tcp_nagle_check(const struct tcp_sock *tp, |
e905a9ed | 1615 | const struct sk_buff *skb, |
95c96174 | 1616 | unsigned int mss_now, int nonagle) |
c1b4a7e6 | 1617 | { |
a02cec21 | 1618 | return skb->len < mss_now && |
056834d9 | 1619 | ((nonagle & TCP_NAGLE_CORK) || |
a02cec21 | 1620 | (!nonagle && tp->packets_out && tcp_minshall_check(tp))); |
c1b4a7e6 DM |
1621 | } |
1622 | ||
a2a385d6 | 1623 | /* Return true if the Nagle test allows this packet to be |
c1b4a7e6 DM |
1624 | * sent now. |
1625 | */ | |
a2a385d6 ED |
1626 | static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
1627 | unsigned int cur_mss, int nonagle) | |
c1b4a7e6 DM |
1628 | { |
1629 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
1630 | * write_queue (they have no chances to get new data). | |
1631 | * | |
1632 | * This is implemented in the callers, where they modify the 'nonagle' | |
1633 | * argument based upon the location of SKB in the send queue. | |
1634 | */ | |
1635 | if (nonagle & TCP_NAGLE_PUSH) | |
a2a385d6 | 1636 | return true; |
c1b4a7e6 | 1637 | |
d551e454 IJ |
1638 | /* Don't use the nagle rule for urgent data (or for the final FIN). |
1639 | * Nagle can be ignored during F-RTO too (see RFC4138). | |
1640 | */ | |
33f5f57e | 1641 | if (tcp_urg_mode(tp) || (tp->frto_counter == 2) || |
4de075e0 | 1642 | (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) |
a2a385d6 | 1643 | return true; |
c1b4a7e6 DM |
1644 | |
1645 | if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) | |
a2a385d6 | 1646 | return true; |
c1b4a7e6 | 1647 | |
a2a385d6 | 1648 | return false; |
c1b4a7e6 DM |
1649 | } |
1650 | ||
1651 | /* Does at least the first segment of SKB fit into the send window? */ | |
a2a385d6 ED |
1652 | static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
1653 | const struct sk_buff *skb, | |
1654 | unsigned int cur_mss) | |
c1b4a7e6 DM |
1655 | { |
1656 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
1657 | ||
1658 | if (skb->len > cur_mss) | |
1659 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
1660 | ||
90840def | 1661 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
1662 | } |
1663 | ||
fe067e8a | 1664 | /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) |
c1b4a7e6 DM |
1665 | * should be put on the wire right now. If so, it returns the number of |
1666 | * packets allowed by the congestion window. | |
1667 | */ | |
cf533ea5 | 1668 | static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, |
c1b4a7e6 DM |
1669 | unsigned int cur_mss, int nonagle) |
1670 | { | |
cf533ea5 | 1671 | const struct tcp_sock *tp = tcp_sk(sk); |
c1b4a7e6 DM |
1672 | unsigned int cwnd_quota; |
1673 | ||
846998ae | 1674 | tcp_init_tso_segs(sk, skb, cur_mss); |
c1b4a7e6 DM |
1675 | |
1676 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
1677 | return 0; | |
1678 | ||
1679 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
056834d9 | 1680 | if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) |
c1b4a7e6 DM |
1681 | cwnd_quota = 0; |
1682 | ||
1683 | return cwnd_quota; | |
1684 | } | |
1685 | ||
67edfef7 | 1686 | /* Test if sending is allowed right now. */ |
a2a385d6 | 1687 | bool tcp_may_send_now(struct sock *sk) |
c1b4a7e6 | 1688 | { |
cf533ea5 | 1689 | const struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 1690 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 | 1691 | |
a02cec21 | 1692 | return skb && |
0c54b85f | 1693 | tcp_snd_test(sk, skb, tcp_current_mss(sk), |
c1b4a7e6 | 1694 | (tcp_skb_is_last(sk, skb) ? |
a02cec21 | 1695 | tp->nonagle : TCP_NAGLE_PUSH)); |
c1b4a7e6 DM |
1696 | } |
1697 | ||
1698 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet | |
1699 | * which is put after SKB on the list. It is very much like | |
1700 | * tcp_fragment() except that it may make several kinds of assumptions | |
1701 | * in order to speed up the splitting operation. In particular, we | |
1702 | * know that all the data is in scatter-gather pages, and that the | |
1703 | * packet has never been sent out before (and thus is not cloned). | |
1704 | */ | |
056834d9 | 1705 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
c4ead4c5 | 1706 | unsigned int mss_now, gfp_t gfp) |
c1b4a7e6 DM |
1707 | { |
1708 | struct sk_buff *buff; | |
1709 | int nlen = skb->len - len; | |
9ce01461 | 1710 | u8 flags; |
c1b4a7e6 DM |
1711 | |
1712 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 HX |
1713 | if (skb->len != skb->data_len) |
1714 | return tcp_fragment(sk, skb, len, mss_now); | |
c1b4a7e6 | 1715 | |
c4ead4c5 | 1716 | buff = sk_stream_alloc_skb(sk, 0, gfp); |
c1b4a7e6 DM |
1717 | if (unlikely(buff == NULL)) |
1718 | return -ENOMEM; | |
1719 | ||
3ab224be HA |
1720 | sk->sk_wmem_queued += buff->truesize; |
1721 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea | 1722 | buff->truesize += nlen; |
c1b4a7e6 DM |
1723 | skb->truesize -= nlen; |
1724 | ||
1725 | /* Correct the sequence numbers. */ | |
1726 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1727 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1728 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1729 | ||
1730 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1731 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1732 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1733 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
c1b4a7e6 DM |
1734 | |
1735 | /* This packet was never sent out yet, so no SACK bits. */ | |
1736 | TCP_SKB_CB(buff)->sacked = 0; | |
1737 | ||
84fa7933 | 1738 | buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; |
c1b4a7e6 DM |
1739 | skb_split(skb, buff, len); |
1740 | ||
1741 | /* Fix up tso_factor for both original and new SKB. */ | |
846998ae DM |
1742 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1743 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
c1b4a7e6 DM |
1744 | |
1745 | /* Link BUFF into the send queue. */ | |
1746 | skb_header_release(buff); | |
fe067e8a | 1747 | tcp_insert_write_queue_after(skb, buff, sk); |
c1b4a7e6 DM |
1748 | |
1749 | return 0; | |
1750 | } | |
1751 | ||
1752 | /* Try to defer sending, if possible, in order to minimize the amount | |
1753 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1754 | * | |
1755 | * This algorithm is from John Heffner. | |
1756 | */ | |
a2a385d6 | 1757 | static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) |
c1b4a7e6 | 1758 | { |
9e412ba7 | 1759 | struct tcp_sock *tp = tcp_sk(sk); |
6687e988 | 1760 | const struct inet_connection_sock *icsk = inet_csk(sk); |
c1b4a7e6 | 1761 | u32 send_win, cong_win, limit, in_flight; |
ad9f4f50 | 1762 | int win_divisor; |
c1b4a7e6 | 1763 | |
4de075e0 | 1764 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) |
ae8064ac | 1765 | goto send_now; |
c1b4a7e6 | 1766 | |
6687e988 | 1767 | if (icsk->icsk_ca_state != TCP_CA_Open) |
ae8064ac JH |
1768 | goto send_now; |
1769 | ||
1770 | /* Defer for less than two clock ticks. */ | |
bd515c3e | 1771 | if (tp->tso_deferred && |
a2acde07 | 1772 | (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) |
ae8064ac | 1773 | goto send_now; |
908a75c1 | 1774 | |
c1b4a7e6 DM |
1775 | in_flight = tcp_packets_in_flight(tp); |
1776 | ||
056834d9 | 1777 | BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); |
c1b4a7e6 | 1778 | |
90840def | 1779 | send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 DM |
1780 | |
1781 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1782 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1783 | ||
1784 | limit = min(send_win, cong_win); | |
1785 | ||
ba244fe9 | 1786 | /* If a full-sized TSO skb can be sent, do it. */ |
1485348d BH |
1787 | if (limit >= min_t(unsigned int, sk->sk_gso_max_size, |
1788 | sk->sk_gso_max_segs * tp->mss_cache)) | |
ae8064ac | 1789 | goto send_now; |
ba244fe9 | 1790 | |
62ad2761 IJ |
1791 | /* Middle in queue won't get any more data, full sendable already? */ |
1792 | if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) | |
1793 | goto send_now; | |
1794 | ||
ad9f4f50 ED |
1795 | win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); |
1796 | if (win_divisor) { | |
c1b4a7e6 DM |
1797 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
1798 | ||
1799 | /* If at least some fraction of a window is available, | |
1800 | * just use it. | |
1801 | */ | |
ad9f4f50 | 1802 | chunk /= win_divisor; |
c1b4a7e6 | 1803 | if (limit >= chunk) |
ae8064ac | 1804 | goto send_now; |
c1b4a7e6 DM |
1805 | } else { |
1806 | /* Different approach, try not to defer past a single | |
1807 | * ACK. Receiver should ACK every other full sized | |
1808 | * frame, so if we have space for more than 3 frames | |
1809 | * then send now. | |
1810 | */ | |
6b5a5c0d | 1811 | if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
ae8064ac | 1812 | goto send_now; |
c1b4a7e6 DM |
1813 | } |
1814 | ||
1815 | /* Ok, it looks like it is advisable to defer. */ | |
056834d9 | 1816 | tp->tso_deferred = 1 | (jiffies << 1); |
ae8064ac | 1817 | |
a2a385d6 | 1818 | return true; |
ae8064ac JH |
1819 | |
1820 | send_now: | |
1821 | tp->tso_deferred = 0; | |
a2a385d6 | 1822 | return false; |
c1b4a7e6 DM |
1823 | } |
1824 | ||
5d424d5a | 1825 | /* Create a new MTU probe if we are ready. |
67edfef7 AK |
1826 | * MTU probe is regularly attempting to increase the path MTU by |
1827 | * deliberately sending larger packets. This discovers routing | |
1828 | * changes resulting in larger path MTUs. | |
1829 | * | |
5d424d5a JH |
1830 | * Returns 0 if we should wait to probe (no cwnd available), |
1831 | * 1 if a probe was sent, | |
056834d9 IJ |
1832 | * -1 otherwise |
1833 | */ | |
5d424d5a JH |
1834 | static int tcp_mtu_probe(struct sock *sk) |
1835 | { | |
1836 | struct tcp_sock *tp = tcp_sk(sk); | |
1837 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1838 | struct sk_buff *skb, *nskb, *next; | |
1839 | int len; | |
1840 | int probe_size; | |
91cc17c0 | 1841 | int size_needed; |
5d424d5a JH |
1842 | int copy; |
1843 | int mss_now; | |
1844 | ||
1845 | /* Not currently probing/verifying, | |
1846 | * not in recovery, | |
1847 | * have enough cwnd, and | |
1848 | * not SACKing (the variable headers throw things off) */ | |
1849 | if (!icsk->icsk_mtup.enabled || | |
1850 | icsk->icsk_mtup.probe_size || | |
1851 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
1852 | tp->snd_cwnd < 11 || | |
cabeccbd | 1853 | tp->rx_opt.num_sacks || tp->rx_opt.dsack) |
5d424d5a JH |
1854 | return -1; |
1855 | ||
1856 | /* Very simple search strategy: just double the MSS. */ | |
0c54b85f | 1857 | mss_now = tcp_current_mss(sk); |
056834d9 | 1858 | probe_size = 2 * tp->mss_cache; |
91cc17c0 | 1859 | size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
5d424d5a JH |
1860 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { |
1861 | /* TODO: set timer for probe_converge_event */ | |
1862 | return -1; | |
1863 | } | |
1864 | ||
1865 | /* Have enough data in the send queue to probe? */ | |
7f9c33e5 | 1866 | if (tp->write_seq - tp->snd_nxt < size_needed) |
5d424d5a JH |
1867 | return -1; |
1868 | ||
91cc17c0 IJ |
1869 | if (tp->snd_wnd < size_needed) |
1870 | return -1; | |
90840def | 1871 | if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
91cc17c0 | 1872 | return 0; |
5d424d5a | 1873 | |
d67c58e9 IJ |
1874 | /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
1875 | if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { | |
1876 | if (!tcp_packets_in_flight(tp)) | |
5d424d5a JH |
1877 | return -1; |
1878 | else | |
1879 | return 0; | |
1880 | } | |
1881 | ||
1882 | /* We're allowed to probe. Build it now. */ | |
1883 | if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) | |
1884 | return -1; | |
3ab224be HA |
1885 | sk->sk_wmem_queued += nskb->truesize; |
1886 | sk_mem_charge(sk, nskb->truesize); | |
5d424d5a | 1887 | |
fe067e8a | 1888 | skb = tcp_send_head(sk); |
5d424d5a JH |
1889 | |
1890 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
1891 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
4de075e0 | 1892 | TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
5d424d5a JH |
1893 | TCP_SKB_CB(nskb)->sacked = 0; |
1894 | nskb->csum = 0; | |
84fa7933 | 1895 | nskb->ip_summed = skb->ip_summed; |
5d424d5a | 1896 | |
50c4817e IJ |
1897 | tcp_insert_write_queue_before(nskb, skb, sk); |
1898 | ||
5d424d5a | 1899 | len = 0; |
234b6860 | 1900 | tcp_for_write_queue_from_safe(skb, next, sk) { |
5d424d5a JH |
1901 | copy = min_t(int, skb->len, probe_size - len); |
1902 | if (nskb->ip_summed) | |
1903 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); | |
1904 | else | |
1905 | nskb->csum = skb_copy_and_csum_bits(skb, 0, | |
056834d9 IJ |
1906 | skb_put(nskb, copy), |
1907 | copy, nskb->csum); | |
5d424d5a JH |
1908 | |
1909 | if (skb->len <= copy) { | |
1910 | /* We've eaten all the data from this skb. | |
1911 | * Throw it away. */ | |
4de075e0 | 1912 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
fe067e8a | 1913 | tcp_unlink_write_queue(skb, sk); |
3ab224be | 1914 | sk_wmem_free_skb(sk, skb); |
5d424d5a | 1915 | } else { |
4de075e0 | 1916 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
a3433f35 | 1917 | ~(TCPHDR_FIN|TCPHDR_PSH); |
5d424d5a JH |
1918 | if (!skb_shinfo(skb)->nr_frags) { |
1919 | skb_pull(skb, copy); | |
84fa7933 | 1920 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
056834d9 IJ |
1921 | skb->csum = csum_partial(skb->data, |
1922 | skb->len, 0); | |
5d424d5a JH |
1923 | } else { |
1924 | __pskb_trim_head(skb, copy); | |
1925 | tcp_set_skb_tso_segs(sk, skb, mss_now); | |
1926 | } | |
1927 | TCP_SKB_CB(skb)->seq += copy; | |
1928 | } | |
1929 | ||
1930 | len += copy; | |
234b6860 IJ |
1931 | |
1932 | if (len >= probe_size) | |
1933 | break; | |
5d424d5a JH |
1934 | } |
1935 | tcp_init_tso_segs(sk, nskb, nskb->len); | |
1936 | ||
1937 | /* We're ready to send. If this fails, the probe will | |
1938 | * be resegmented into mss-sized pieces by tcp_write_xmit(). */ | |
1939 | TCP_SKB_CB(nskb)->when = tcp_time_stamp; | |
1940 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { | |
1941 | /* Decrement cwnd here because we are sending | |
056834d9 | 1942 | * effectively two packets. */ |
5d424d5a | 1943 | tp->snd_cwnd--; |
66f5fe62 | 1944 | tcp_event_new_data_sent(sk, nskb); |
5d424d5a JH |
1945 | |
1946 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
1947 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
1948 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
1949 | |
1950 | return 1; | |
1951 | } | |
1952 | ||
1953 | return -1; | |
1954 | } | |
1955 | ||
1da177e4 LT |
1956 | /* This routine writes packets to the network. It advances the |
1957 | * send_head. This happens as incoming acks open up the remote | |
1958 | * window for us. | |
1959 | * | |
f8269a49 IJ |
1960 | * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
1961 | * snd_up-64k-mss .. snd_up cannot be large. However, taking into | |
1962 | * account rare use of URG, this is not a big flaw. | |
1963 | * | |
6ba8a3b1 ND |
1964 | * Send at most one packet when push_one > 0. Temporarily ignore |
1965 | * cwnd limit to force at most one packet out when push_one == 2. | |
1966 | ||
a2a385d6 ED |
1967 | * Returns true, if no segments are in flight and we have queued segments, |
1968 | * but cannot send anything now because of SWS or another problem. | |
1da177e4 | 1969 | */ |
a2a385d6 ED |
1970 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
1971 | int push_one, gfp_t gfp) | |
1da177e4 LT |
1972 | { |
1973 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 1974 | struct sk_buff *skb; |
c1b4a7e6 DM |
1975 | unsigned int tso_segs, sent_pkts; |
1976 | int cwnd_quota; | |
5d424d5a | 1977 | int result; |
1da177e4 | 1978 | |
92df7b51 | 1979 | sent_pkts = 0; |
5d424d5a | 1980 | |
d5dd9175 IJ |
1981 | if (!push_one) { |
1982 | /* Do MTU probing. */ | |
1983 | result = tcp_mtu_probe(sk); | |
1984 | if (!result) { | |
a2a385d6 | 1985 | return false; |
d5dd9175 IJ |
1986 | } else if (result > 0) { |
1987 | sent_pkts = 1; | |
1988 | } | |
5d424d5a JH |
1989 | } |
1990 | ||
fe067e8a | 1991 | while ((skb = tcp_send_head(sk))) { |
c8ac3774 HX |
1992 | unsigned int limit; |
1993 | ||
46d3ceab | 1994 | |
b68e9f85 | 1995 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 | 1996 | BUG_ON(!tso_segs); |
aa93466b | 1997 | |
ec342325 AV |
1998 | if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) |
1999 | goto repair; /* Skip network transmission */ | |
2000 | ||
b68e9f85 | 2001 | cwnd_quota = tcp_cwnd_test(tp, skb); |
6ba8a3b1 ND |
2002 | if (!cwnd_quota) { |
2003 | if (push_one == 2) | |
2004 | /* Force out a loss probe pkt. */ | |
2005 | cwnd_quota = 1; | |
2006 | else | |
2007 | break; | |
2008 | } | |
b68e9f85 HX |
2009 | |
2010 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) | |
2011 | break; | |
2012 | ||
c1b4a7e6 DM |
2013 | if (tso_segs == 1) { |
2014 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, | |
2015 | (tcp_skb_is_last(sk, skb) ? | |
2016 | nonagle : TCP_NAGLE_PUSH)))) | |
2017 | break; | |
2018 | } else { | |
d5dd9175 | 2019 | if (!push_one && tcp_tso_should_defer(sk, skb)) |
c1b4a7e6 DM |
2020 | break; |
2021 | } | |
aa93466b | 2022 | |
46d3ceab ED |
2023 | /* TSQ : sk_wmem_alloc accounts skb truesize, |
2024 | * including skb overhead. But thats OK. | |
2025 | */ | |
2026 | if (atomic_read(&sk->sk_wmem_alloc) >= sysctl_tcp_limit_output_bytes) { | |
2027 | set_bit(TSQ_THROTTLED, &tp->tsq_flags); | |
2028 | break; | |
2029 | } | |
c8ac3774 | 2030 | limit = mss_now; |
f8269a49 | 2031 | if (tso_segs > 1 && !tcp_urg_mode(tp)) |
0e3a4803 | 2032 | limit = tcp_mss_split_point(sk, skb, mss_now, |
1485348d BH |
2033 | min_t(unsigned int, |
2034 | cwnd_quota, | |
2035 | sk->sk_gso_max_segs)); | |
1da177e4 | 2036 | |
c8ac3774 | 2037 | if (skb->len > limit && |
c4ead4c5 | 2038 | unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) |
c8ac3774 HX |
2039 | break; |
2040 | ||
92df7b51 | 2041 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
c1b4a7e6 | 2042 | |
d5dd9175 | 2043 | if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
92df7b51 | 2044 | break; |
1da177e4 | 2045 | |
ec342325 | 2046 | repair: |
92df7b51 DM |
2047 | /* Advance the send_head. This one is sent out. |
2048 | * This call will increment packets_out. | |
2049 | */ | |
66f5fe62 | 2050 | tcp_event_new_data_sent(sk, skb); |
1da177e4 | 2051 | |
92df7b51 | 2052 | tcp_minshall_update(tp, mss_now, skb); |
a262f0cd | 2053 | sent_pkts += tcp_skb_pcount(skb); |
d5dd9175 IJ |
2054 | |
2055 | if (push_one) | |
2056 | break; | |
92df7b51 | 2057 | } |
1da177e4 | 2058 | |
aa93466b | 2059 | if (likely(sent_pkts)) { |
684bad11 YC |
2060 | if (tcp_in_cwnd_reduction(sk)) |
2061 | tp->prr_out += sent_pkts; | |
6ba8a3b1 ND |
2062 | |
2063 | /* Send one loss probe per tail loss episode. */ | |
2064 | if (push_one != 2) | |
2065 | tcp_schedule_loss_probe(sk); | |
9e412ba7 | 2066 | tcp_cwnd_validate(sk); |
a2a385d6 | 2067 | return false; |
1da177e4 | 2068 | } |
6ba8a3b1 ND |
2069 | return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); |
2070 | } | |
2071 | ||
2072 | bool tcp_schedule_loss_probe(struct sock *sk) | |
2073 | { | |
2074 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2075 | struct tcp_sock *tp = tcp_sk(sk); | |
2076 | u32 timeout, tlp_time_stamp, rto_time_stamp; | |
2077 | u32 rtt = tp->srtt >> 3; | |
2078 | ||
2079 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS)) | |
2080 | return false; | |
2081 | /* No consecutive loss probes. */ | |
2082 | if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) { | |
2083 | tcp_rearm_rto(sk); | |
2084 | return false; | |
2085 | } | |
2086 | /* Don't do any loss probe on a Fast Open connection before 3WHS | |
2087 | * finishes. | |
2088 | */ | |
2089 | if (sk->sk_state == TCP_SYN_RECV) | |
2090 | return false; | |
2091 | ||
2092 | /* TLP is only scheduled when next timer event is RTO. */ | |
2093 | if (icsk->icsk_pending != ICSK_TIME_RETRANS) | |
2094 | return false; | |
2095 | ||
2096 | /* Schedule a loss probe in 2*RTT for SACK capable connections | |
2097 | * in Open state, that are either limited by cwnd or application. | |
2098 | */ | |
2099 | if (sysctl_tcp_early_retrans < 3 || !rtt || !tp->packets_out || | |
2100 | !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open) | |
2101 | return false; | |
2102 | ||
2103 | if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) && | |
2104 | tcp_send_head(sk)) | |
2105 | return false; | |
2106 | ||
2107 | /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account | |
2108 | * for delayed ack when there's one outstanding packet. | |
2109 | */ | |
2110 | timeout = rtt << 1; | |
2111 | if (tp->packets_out == 1) | |
2112 | timeout = max_t(u32, timeout, | |
2113 | (rtt + (rtt >> 1) + TCP_DELACK_MAX)); | |
2114 | timeout = max_t(u32, timeout, msecs_to_jiffies(10)); | |
2115 | ||
2116 | /* If RTO is shorter, just schedule TLP in its place. */ | |
2117 | tlp_time_stamp = tcp_time_stamp + timeout; | |
2118 | rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout; | |
2119 | if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) { | |
2120 | s32 delta = rto_time_stamp - tcp_time_stamp; | |
2121 | if (delta > 0) | |
2122 | timeout = delta; | |
2123 | } | |
2124 | ||
2125 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, | |
2126 | TCP_RTO_MAX); | |
2127 | return true; | |
2128 | } | |
2129 | ||
2130 | /* When probe timeout (PTO) fires, send a new segment if one exists, else | |
2131 | * retransmit the last segment. | |
2132 | */ | |
2133 | void tcp_send_loss_probe(struct sock *sk) | |
2134 | { | |
9b717a8d | 2135 | struct tcp_sock *tp = tcp_sk(sk); |
6ba8a3b1 ND |
2136 | struct sk_buff *skb; |
2137 | int pcount; | |
2138 | int mss = tcp_current_mss(sk); | |
2139 | int err = -1; | |
2140 | ||
2141 | if (tcp_send_head(sk) != NULL) { | |
2142 | err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); | |
2143 | goto rearm_timer; | |
2144 | } | |
2145 | ||
9b717a8d ND |
2146 | /* At most one outstanding TLP retransmission. */ |
2147 | if (tp->tlp_high_seq) | |
2148 | goto rearm_timer; | |
2149 | ||
6ba8a3b1 ND |
2150 | /* Retransmit last segment. */ |
2151 | skb = tcp_write_queue_tail(sk); | |
2152 | if (WARN_ON(!skb)) | |
2153 | goto rearm_timer; | |
2154 | ||
2155 | pcount = tcp_skb_pcount(skb); | |
2156 | if (WARN_ON(!pcount)) | |
2157 | goto rearm_timer; | |
2158 | ||
2159 | if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { | |
2160 | if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss))) | |
2161 | goto rearm_timer; | |
2162 | skb = tcp_write_queue_tail(sk); | |
2163 | } | |
2164 | ||
2165 | if (WARN_ON(!skb || !tcp_skb_pcount(skb))) | |
2166 | goto rearm_timer; | |
2167 | ||
2168 | /* Probe with zero data doesn't trigger fast recovery. */ | |
2169 | if (skb->len > 0) | |
2170 | err = __tcp_retransmit_skb(sk, skb); | |
2171 | ||
9b717a8d ND |
2172 | /* Record snd_nxt for loss detection. */ |
2173 | if (likely(!err)) | |
2174 | tp->tlp_high_seq = tp->snd_nxt; | |
2175 | ||
6ba8a3b1 ND |
2176 | rearm_timer: |
2177 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
2178 | inet_csk(sk)->icsk_rto, | |
2179 | TCP_RTO_MAX); | |
2180 | ||
2181 | if (likely(!err)) | |
2182 | NET_INC_STATS_BH(sock_net(sk), | |
2183 | LINUX_MIB_TCPLOSSPROBES); | |
2184 | return; | |
1da177e4 LT |
2185 | } |
2186 | ||
a762a980 DM |
2187 | /* Push out any pending frames which were held back due to |
2188 | * TCP_CORK or attempt at coalescing tiny packets. | |
2189 | * The socket must be locked by the caller. | |
2190 | */ | |
9e412ba7 IJ |
2191 | void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
2192 | int nonagle) | |
a762a980 | 2193 | { |
726e07a8 IJ |
2194 | /* If we are closed, the bytes will have to remain here. |
2195 | * In time closedown will finish, we empty the write queue and | |
2196 | * all will be happy. | |
2197 | */ | |
2198 | if (unlikely(sk->sk_state == TCP_CLOSE)) | |
2199 | return; | |
2200 | ||
99a1dec7 MG |
2201 | if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
2202 | sk_gfp_atomic(sk, GFP_ATOMIC))) | |
726e07a8 | 2203 | tcp_check_probe_timer(sk); |
a762a980 DM |
2204 | } |
2205 | ||
c1b4a7e6 DM |
2206 | /* Send _single_ skb sitting at the send head. This function requires |
2207 | * true push pending frames to setup probe timer etc. | |
2208 | */ | |
2209 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
2210 | { | |
fe067e8a | 2211 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
2212 | |
2213 | BUG_ON(!skb || skb->len < mss_now); | |
2214 | ||
d5dd9175 | 2215 | tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
c1b4a7e6 DM |
2216 | } |
2217 | ||
1da177e4 LT |
2218 | /* This function returns the amount that we can raise the |
2219 | * usable window based on the following constraints | |
e905a9ed | 2220 | * |
1da177e4 LT |
2221 | * 1. The window can never be shrunk once it is offered (RFC 793) |
2222 | * 2. We limit memory per socket | |
2223 | * | |
2224 | * RFC 1122: | |
2225 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
2226 | * RECV.NEXT + RCV.WIN fixed until: | |
2227 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
2228 | * | |
2229 | * i.e. don't raise the right edge of the window until you can raise | |
2230 | * it at least MSS bytes. | |
2231 | * | |
2232 | * Unfortunately, the recommended algorithm breaks header prediction, | |
2233 | * since header prediction assumes th->window stays fixed. | |
2234 | * | |
2235 | * Strictly speaking, keeping th->window fixed violates the receiver | |
2236 | * side SWS prevention criteria. The problem is that under this rule | |
2237 | * a stream of single byte packets will cause the right side of the | |
2238 | * window to always advance by a single byte. | |
e905a9ed | 2239 | * |
1da177e4 LT |
2240 | * Of course, if the sender implements sender side SWS prevention |
2241 | * then this will not be a problem. | |
e905a9ed | 2242 | * |
1da177e4 | 2243 | * BSD seems to make the following compromise: |
e905a9ed | 2244 | * |
1da177e4 LT |
2245 | * If the free space is less than the 1/4 of the maximum |
2246 | * space available and the free space is less than 1/2 mss, | |
2247 | * then set the window to 0. | |
2248 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
2249 | * Otherwise, just prevent the window from shrinking | |
2250 | * and from being larger than the largest representable value. | |
2251 | * | |
2252 | * This prevents incremental opening of the window in the regime | |
2253 | * where TCP is limited by the speed of the reader side taking | |
2254 | * data out of the TCP receive queue. It does nothing about | |
2255 | * those cases where the window is constrained on the sender side | |
2256 | * because the pipeline is full. | |
2257 | * | |
2258 | * BSD also seems to "accidentally" limit itself to windows that are a | |
2259 | * multiple of MSS, at least until the free space gets quite small. | |
2260 | * This would appear to be a side effect of the mbuf implementation. | |
2261 | * Combining these two algorithms results in the observed behavior | |
2262 | * of having a fixed window size at almost all times. | |
2263 | * | |
2264 | * Below we obtain similar behavior by forcing the offered window to | |
2265 | * a multiple of the mss when it is feasible to do so. | |
2266 | * | |
2267 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
2268 | * Regular options like TIMESTAMP are taken into account. | |
2269 | */ | |
2270 | u32 __tcp_select_window(struct sock *sk) | |
2271 | { | |
463c84b9 | 2272 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 2273 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 2274 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
2275 | * here. I don't know if the value based on our guesses |
2276 | * of peer's MSS is better for the performance. It's more correct | |
2277 | * but may be worse for the performance because of rcv_mss | |
2278 | * fluctuations. --SAW 1998/11/1 | |
2279 | */ | |
463c84b9 | 2280 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 LT |
2281 | int free_space = tcp_space(sk); |
2282 | int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); | |
2283 | int window; | |
2284 | ||
2285 | if (mss > full_space) | |
e905a9ed | 2286 | mss = full_space; |
1da177e4 | 2287 | |
b92edbe0 | 2288 | if (free_space < (full_space >> 1)) { |
463c84b9 | 2289 | icsk->icsk_ack.quick = 0; |
1da177e4 | 2290 | |
180d8cd9 | 2291 | if (sk_under_memory_pressure(sk)) |
056834d9 IJ |
2292 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, |
2293 | 4U * tp->advmss); | |
1da177e4 LT |
2294 | |
2295 | if (free_space < mss) | |
2296 | return 0; | |
2297 | } | |
2298 | ||
2299 | if (free_space > tp->rcv_ssthresh) | |
2300 | free_space = tp->rcv_ssthresh; | |
2301 | ||
2302 | /* Don't do rounding if we are using window scaling, since the | |
2303 | * scaled window will not line up with the MSS boundary anyway. | |
2304 | */ | |
2305 | window = tp->rcv_wnd; | |
2306 | if (tp->rx_opt.rcv_wscale) { | |
2307 | window = free_space; | |
2308 | ||
2309 | /* Advertise enough space so that it won't get scaled away. | |
2310 | * Import case: prevent zero window announcement if | |
2311 | * 1<<rcv_wscale > mss. | |
2312 | */ | |
2313 | if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) | |
2314 | window = (((window >> tp->rx_opt.rcv_wscale) + 1) | |
2315 | << tp->rx_opt.rcv_wscale); | |
2316 | } else { | |
2317 | /* Get the largest window that is a nice multiple of mss. | |
2318 | * Window clamp already applied above. | |
2319 | * If our current window offering is within 1 mss of the | |
2320 | * free space we just keep it. This prevents the divide | |
2321 | * and multiply from happening most of the time. | |
2322 | * We also don't do any window rounding when the free space | |
2323 | * is too small. | |
2324 | */ | |
2325 | if (window <= free_space - mss || window > free_space) | |
056834d9 | 2326 | window = (free_space / mss) * mss; |
84565070 | 2327 | else if (mss == full_space && |
b92edbe0 | 2328 | free_space > window + (full_space >> 1)) |
84565070 | 2329 | window = free_space; |
1da177e4 LT |
2330 | } |
2331 | ||
2332 | return window; | |
2333 | } | |
2334 | ||
4a17fc3a IJ |
2335 | /* Collapses two adjacent SKB's during retransmission. */ |
2336 | static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) | |
1da177e4 LT |
2337 | { |
2338 | struct tcp_sock *tp = tcp_sk(sk); | |
fe067e8a | 2339 | struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); |
058dc334 | 2340 | int skb_size, next_skb_size; |
1da177e4 | 2341 | |
058dc334 IJ |
2342 | skb_size = skb->len; |
2343 | next_skb_size = next_skb->len; | |
1da177e4 | 2344 | |
058dc334 | 2345 | BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
a6963a6b | 2346 | |
058dc334 | 2347 | tcp_highest_sack_combine(sk, next_skb, skb); |
1da177e4 | 2348 | |
058dc334 | 2349 | tcp_unlink_write_queue(next_skb, sk); |
1da177e4 | 2350 | |
058dc334 IJ |
2351 | skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), |
2352 | next_skb_size); | |
1da177e4 | 2353 | |
058dc334 IJ |
2354 | if (next_skb->ip_summed == CHECKSUM_PARTIAL) |
2355 | skb->ip_summed = CHECKSUM_PARTIAL; | |
1da177e4 | 2356 | |
058dc334 IJ |
2357 | if (skb->ip_summed != CHECKSUM_PARTIAL) |
2358 | skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); | |
1da177e4 | 2359 | |
058dc334 IJ |
2360 | /* Update sequence range on original skb. */ |
2361 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1da177e4 | 2362 | |
e6c7d085 | 2363 | /* Merge over control information. This moves PSH/FIN etc. over */ |
4de075e0 | 2364 | TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
058dc334 IJ |
2365 | |
2366 | /* All done, get rid of second SKB and account for it so | |
2367 | * packet counting does not break. | |
2368 | */ | |
2369 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; | |
058dc334 IJ |
2370 | |
2371 | /* changed transmit queue under us so clear hints */ | |
ef9da47c IJ |
2372 | tcp_clear_retrans_hints_partial(tp); |
2373 | if (next_skb == tp->retransmit_skb_hint) | |
2374 | tp->retransmit_skb_hint = skb; | |
058dc334 | 2375 | |
797108d1 IJ |
2376 | tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
2377 | ||
058dc334 | 2378 | sk_wmem_free_skb(sk, next_skb); |
1da177e4 LT |
2379 | } |
2380 | ||
67edfef7 | 2381 | /* Check if coalescing SKBs is legal. */ |
a2a385d6 | 2382 | static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
4a17fc3a IJ |
2383 | { |
2384 | if (tcp_skb_pcount(skb) > 1) | |
a2a385d6 | 2385 | return false; |
4a17fc3a IJ |
2386 | /* TODO: SACK collapsing could be used to remove this condition */ |
2387 | if (skb_shinfo(skb)->nr_frags != 0) | |
a2a385d6 | 2388 | return false; |
4a17fc3a | 2389 | if (skb_cloned(skb)) |
a2a385d6 | 2390 | return false; |
4a17fc3a | 2391 | if (skb == tcp_send_head(sk)) |
a2a385d6 | 2392 | return false; |
4a17fc3a IJ |
2393 | /* Some heurestics for collapsing over SACK'd could be invented */ |
2394 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
a2a385d6 | 2395 | return false; |
4a17fc3a | 2396 | |
a2a385d6 | 2397 | return true; |
4a17fc3a IJ |
2398 | } |
2399 | ||
67edfef7 AK |
2400 | /* Collapse packets in the retransmit queue to make to create |
2401 | * less packets on the wire. This is only done on retransmission. | |
2402 | */ | |
4a17fc3a IJ |
2403 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
2404 | int space) | |
2405 | { | |
2406 | struct tcp_sock *tp = tcp_sk(sk); | |
2407 | struct sk_buff *skb = to, *tmp; | |
a2a385d6 | 2408 | bool first = true; |
4a17fc3a IJ |
2409 | |
2410 | if (!sysctl_tcp_retrans_collapse) | |
2411 | return; | |
4de075e0 | 2412 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
4a17fc3a IJ |
2413 | return; |
2414 | ||
2415 | tcp_for_write_queue_from_safe(skb, tmp, sk) { | |
2416 | if (!tcp_can_collapse(sk, skb)) | |
2417 | break; | |
2418 | ||
2419 | space -= skb->len; | |
2420 | ||
2421 | if (first) { | |
a2a385d6 | 2422 | first = false; |
4a17fc3a IJ |
2423 | continue; |
2424 | } | |
2425 | ||
2426 | if (space < 0) | |
2427 | break; | |
2428 | /* Punt if not enough space exists in the first SKB for | |
2429 | * the data in the second | |
2430 | */ | |
a21d4572 | 2431 | if (skb->len > skb_availroom(to)) |
4a17fc3a IJ |
2432 | break; |
2433 | ||
2434 | if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) | |
2435 | break; | |
2436 | ||
2437 | tcp_collapse_retrans(sk, to); | |
2438 | } | |
2439 | } | |
2440 | ||
1da177e4 LT |
2441 | /* This retransmits one SKB. Policy decisions and retransmit queue |
2442 | * state updates are done by the caller. Returns non-zero if an | |
2443 | * error occurred which prevented the send. | |
2444 | */ | |
93b174ad | 2445 | int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) |
1da177e4 LT |
2446 | { |
2447 | struct tcp_sock *tp = tcp_sk(sk); | |
5d424d5a | 2448 | struct inet_connection_sock *icsk = inet_csk(sk); |
7d227cd2 | 2449 | unsigned int cur_mss; |
1da177e4 | 2450 | |
5d424d5a JH |
2451 | /* Inconslusive MTU probe */ |
2452 | if (icsk->icsk_mtup.probe_size) { | |
2453 | icsk->icsk_mtup.probe_size = 0; | |
2454 | } | |
2455 | ||
1da177e4 | 2456 | /* Do not sent more than we queued. 1/4 is reserved for possible |
caa20d9a | 2457 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 LT |
2458 | */ |
2459 | if (atomic_read(&sk->sk_wmem_alloc) > | |
2460 | min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) | |
2461 | return -EAGAIN; | |
2462 | ||
2463 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { | |
2464 | if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
2465 | BUG(); | |
1da177e4 LT |
2466 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
2467 | return -ENOMEM; | |
2468 | } | |
2469 | ||
7d227cd2 SS |
2470 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
2471 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
2472 | ||
0c54b85f | 2473 | cur_mss = tcp_current_mss(sk); |
7d227cd2 | 2474 | |
1da177e4 LT |
2475 | /* If receiver has shrunk his window, and skb is out of |
2476 | * new window, do not retransmit it. The exception is the | |
2477 | * case, when window is shrunk to zero. In this case | |
2478 | * our retransmit serves as a zero window probe. | |
2479 | */ | |
9d4fb27d JP |
2480 | if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && |
2481 | TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1da177e4 LT |
2482 | return -EAGAIN; |
2483 | ||
2484 | if (skb->len > cur_mss) { | |
846998ae | 2485 | if (tcp_fragment(sk, skb, cur_mss, cur_mss)) |
1da177e4 | 2486 | return -ENOMEM; /* We'll try again later. */ |
02276f3c | 2487 | } else { |
9eb9362e IJ |
2488 | int oldpcount = tcp_skb_pcount(skb); |
2489 | ||
2490 | if (unlikely(oldpcount > 1)) { | |
2491 | tcp_init_tso_segs(sk, skb, cur_mss); | |
2492 | tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); | |
2493 | } | |
1da177e4 LT |
2494 | } |
2495 | ||
4a17fc3a | 2496 | tcp_retrans_try_collapse(sk, skb, cur_mss); |
1da177e4 | 2497 | |
1da177e4 LT |
2498 | /* Some Solaris stacks overoptimize and ignore the FIN on a |
2499 | * retransmit when old data is attached. So strip it off | |
2500 | * since it is cheap to do so and saves bytes on the network. | |
2501 | */ | |
2de979bd | 2502 | if (skb->len > 0 && |
4de075e0 | 2503 | (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
2de979bd | 2504 | tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { |
1da177e4 | 2505 | if (!pskb_trim(skb, 0)) { |
e870a8ef IJ |
2506 | /* Reuse, even though it does some unnecessary work */ |
2507 | tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1, | |
4de075e0 | 2508 | TCP_SKB_CB(skb)->tcp_flags); |
1da177e4 | 2509 | skb->ip_summed = CHECKSUM_NONE; |
1da177e4 LT |
2510 | } |
2511 | } | |
2512 | ||
2513 | /* Make a copy, if the first transmission SKB clone we made | |
2514 | * is still in somebody's hands, else make a clone. | |
2515 | */ | |
2516 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
1da177e4 | 2517 | |
117632e6 ED |
2518 | /* make sure skb->data is aligned on arches that require it */ |
2519 | if (unlikely(NET_IP_ALIGN && ((unsigned long)skb->data & 3))) { | |
2520 | struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, | |
2521 | GFP_ATOMIC); | |
93b174ad YC |
2522 | return nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : |
2523 | -ENOBUFS; | |
117632e6 | 2524 | } else { |
93b174ad | 2525 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
117632e6 | 2526 | } |
93b174ad YC |
2527 | } |
2528 | ||
2529 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) | |
2530 | { | |
2531 | struct tcp_sock *tp = tcp_sk(sk); | |
2532 | int err = __tcp_retransmit_skb(sk, skb); | |
1da177e4 LT |
2533 | |
2534 | if (err == 0) { | |
2535 | /* Update global TCP statistics. */ | |
81cc8a75 | 2536 | TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); |
1da177e4 LT |
2537 | |
2538 | tp->total_retrans++; | |
2539 | ||
2540 | #if FASTRETRANS_DEBUG > 0 | |
056834d9 | 2541 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
e87cc472 | 2542 | net_dbg_ratelimited("retrans_out leaked\n"); |
1da177e4 LT |
2543 | } |
2544 | #endif | |
b08d6cb2 IJ |
2545 | if (!tp->retrans_out) |
2546 | tp->lost_retrans_low = tp->snd_nxt; | |
1da177e4 LT |
2547 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; |
2548 | tp->retrans_out += tcp_skb_pcount(skb); | |
2549 | ||
2550 | /* Save stamp of the first retransmit. */ | |
2551 | if (!tp->retrans_stamp) | |
2552 | tp->retrans_stamp = TCP_SKB_CB(skb)->when; | |
2553 | ||
c24f691b | 2554 | tp->undo_retrans += tcp_skb_pcount(skb); |
1da177e4 LT |
2555 | |
2556 | /* snd_nxt is stored to detect loss of retransmitted segment, | |
2557 | * see tcp_input.c tcp_sacktag_write_queue(). | |
2558 | */ | |
2559 | TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; | |
2560 | } | |
2561 | return err; | |
2562 | } | |
2563 | ||
67edfef7 AK |
2564 | /* Check if we forward retransmits are possible in the current |
2565 | * window/congestion state. | |
2566 | */ | |
a2a385d6 | 2567 | static bool tcp_can_forward_retransmit(struct sock *sk) |
b5afe7bc IJ |
2568 | { |
2569 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
cf533ea5 | 2570 | const struct tcp_sock *tp = tcp_sk(sk); |
b5afe7bc IJ |
2571 | |
2572 | /* Forward retransmissions are possible only during Recovery. */ | |
2573 | if (icsk->icsk_ca_state != TCP_CA_Recovery) | |
a2a385d6 | 2574 | return false; |
b5afe7bc IJ |
2575 | |
2576 | /* No forward retransmissions in Reno are possible. */ | |
2577 | if (tcp_is_reno(tp)) | |
a2a385d6 | 2578 | return false; |
b5afe7bc IJ |
2579 | |
2580 | /* Yeah, we have to make difficult choice between forward transmission | |
2581 | * and retransmission... Both ways have their merits... | |
2582 | * | |
2583 | * For now we do not retransmit anything, while we have some new | |
2584 | * segments to send. In the other cases, follow rule 3 for | |
2585 | * NextSeg() specified in RFC3517. | |
2586 | */ | |
2587 | ||
2588 | if (tcp_may_send_now(sk)) | |
a2a385d6 | 2589 | return false; |
b5afe7bc | 2590 | |
a2a385d6 | 2591 | return true; |
b5afe7bc IJ |
2592 | } |
2593 | ||
1da177e4 LT |
2594 | /* This gets called after a retransmit timeout, and the initially |
2595 | * retransmitted data is acknowledged. It tries to continue | |
2596 | * resending the rest of the retransmit queue, until either | |
2597 | * we've sent it all or the congestion window limit is reached. | |
2598 | * If doing SACK, the first ACK which comes back for a timeout | |
2599 | * based retransmit packet might feed us FACK information again. | |
2600 | * If so, we use it to avoid unnecessarily retransmissions. | |
2601 | */ | |
2602 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
2603 | { | |
6687e988 | 2604 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2605 | struct tcp_sock *tp = tcp_sk(sk); |
2606 | struct sk_buff *skb; | |
0e1c54c2 | 2607 | struct sk_buff *hole = NULL; |
618d9f25 | 2608 | u32 last_lost; |
61eb55f4 | 2609 | int mib_idx; |
0e1c54c2 | 2610 | int fwd_rexmitting = 0; |
6a438bbe | 2611 | |
45e77d31 IJ |
2612 | if (!tp->packets_out) |
2613 | return; | |
2614 | ||
08ebd172 IJ |
2615 | if (!tp->lost_out) |
2616 | tp->retransmit_high = tp->snd_una; | |
2617 | ||
618d9f25 | 2618 | if (tp->retransmit_skb_hint) { |
6a438bbe | 2619 | skb = tp->retransmit_skb_hint; |
618d9f25 IJ |
2620 | last_lost = TCP_SKB_CB(skb)->end_seq; |
2621 | if (after(last_lost, tp->retransmit_high)) | |
2622 | last_lost = tp->retransmit_high; | |
2623 | } else { | |
fe067e8a | 2624 | skb = tcp_write_queue_head(sk); |
618d9f25 IJ |
2625 | last_lost = tp->snd_una; |
2626 | } | |
1da177e4 | 2627 | |
08ebd172 IJ |
2628 | tcp_for_write_queue_from(skb, sk) { |
2629 | __u8 sacked = TCP_SKB_CB(skb)->sacked; | |
1da177e4 | 2630 | |
08ebd172 IJ |
2631 | if (skb == tcp_send_head(sk)) |
2632 | break; | |
2633 | /* we could do better than to assign each time */ | |
0e1c54c2 IJ |
2634 | if (hole == NULL) |
2635 | tp->retransmit_skb_hint = skb; | |
08ebd172 IJ |
2636 | |
2637 | /* Assume this retransmit will generate | |
2638 | * only one packet for congestion window | |
2639 | * calculation purposes. This works because | |
2640 | * tcp_retransmit_skb() will chop up the | |
2641 | * packet to be MSS sized and all the | |
2642 | * packet counting works out. | |
2643 | */ | |
2644 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
2645 | return; | |
1da177e4 | 2646 | |
0e1c54c2 IJ |
2647 | if (fwd_rexmitting) { |
2648 | begin_fwd: | |
2649 | if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) | |
2650 | break; | |
2651 | mib_idx = LINUX_MIB_TCPFORWARDRETRANS; | |
6a438bbe | 2652 | |
0e1c54c2 | 2653 | } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { |
618d9f25 | 2654 | tp->retransmit_high = last_lost; |
0e1c54c2 IJ |
2655 | if (!tcp_can_forward_retransmit(sk)) |
2656 | break; | |
2657 | /* Backtrack if necessary to non-L'ed skb */ | |
2658 | if (hole != NULL) { | |
2659 | skb = hole; | |
2660 | hole = NULL; | |
2661 | } | |
2662 | fwd_rexmitting = 1; | |
2663 | goto begin_fwd; | |
1da177e4 | 2664 | |
0e1c54c2 | 2665 | } else if (!(sacked & TCPCB_LOST)) { |
ac11ba75 | 2666 | if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
0e1c54c2 IJ |
2667 | hole = skb; |
2668 | continue; | |
1da177e4 | 2669 | |
0e1c54c2 | 2670 | } else { |
618d9f25 | 2671 | last_lost = TCP_SKB_CB(skb)->end_seq; |
0e1c54c2 IJ |
2672 | if (icsk->icsk_ca_state != TCP_CA_Loss) |
2673 | mib_idx = LINUX_MIB_TCPFASTRETRANS; | |
2674 | else | |
2675 | mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; | |
2676 | } | |
1da177e4 | 2677 | |
0e1c54c2 | 2678 | if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
1da177e4 LT |
2679 | continue; |
2680 | ||
09e9b813 ED |
2681 | if (tcp_retransmit_skb(sk, skb)) { |
2682 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); | |
0e1c54c2 | 2683 | return; |
09e9b813 | 2684 | } |
0e1c54c2 | 2685 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 | 2686 | |
684bad11 | 2687 | if (tcp_in_cwnd_reduction(sk)) |
a262f0cd ND |
2688 | tp->prr_out += tcp_skb_pcount(skb); |
2689 | ||
fe067e8a | 2690 | if (skb == tcp_write_queue_head(sk)) |
3f421baa ACM |
2691 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
2692 | inet_csk(sk)->icsk_rto, | |
2693 | TCP_RTO_MAX); | |
1da177e4 LT |
2694 | } |
2695 | } | |
2696 | ||
1da177e4 LT |
2697 | /* Send a fin. The caller locks the socket for us. This cannot be |
2698 | * allowed to fail queueing a FIN frame under any circumstances. | |
2699 | */ | |
2700 | void tcp_send_fin(struct sock *sk) | |
2701 | { | |
e905a9ed | 2702 | struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 2703 | struct sk_buff *skb = tcp_write_queue_tail(sk); |
1da177e4 | 2704 | int mss_now; |
e905a9ed | 2705 | |
1da177e4 LT |
2706 | /* Optimization, tack on the FIN if we have a queue of |
2707 | * unsent frames. But be careful about outgoing SACKS | |
2708 | * and IP options. | |
2709 | */ | |
0c54b85f | 2710 | mss_now = tcp_current_mss(sk); |
1da177e4 | 2711 | |
fe067e8a | 2712 | if (tcp_send_head(sk) != NULL) { |
4de075e0 | 2713 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; |
1da177e4 LT |
2714 | TCP_SKB_CB(skb)->end_seq++; |
2715 | tp->write_seq++; | |
2716 | } else { | |
2717 | /* Socket is locked, keep trying until memory is available. */ | |
2718 | for (;;) { | |
aa133076 WF |
2719 | skb = alloc_skb_fclone(MAX_TCP_HEADER, |
2720 | sk->sk_allocation); | |
1da177e4 LT |
2721 | if (skb) |
2722 | break; | |
2723 | yield(); | |
2724 | } | |
2725 | ||
2726 | /* Reserve space for headers and prepare control bits. */ | |
2727 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 | 2728 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
e870a8ef | 2729 | tcp_init_nondata_skb(skb, tp->write_seq, |
a3433f35 | 2730 | TCPHDR_ACK | TCPHDR_FIN); |
1da177e4 LT |
2731 | tcp_queue_skb(sk, skb); |
2732 | } | |
9e412ba7 | 2733 | __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); |
1da177e4 LT |
2734 | } |
2735 | ||
2736 | /* We get here when a process closes a file descriptor (either due to | |
2737 | * an explicit close() or as a byproduct of exit()'ing) and there | |
2738 | * was unread data in the receive queue. This behavior is recommended | |
65bb723c | 2739 | * by RFC 2525, section 2.17. -DaveM |
1da177e4 | 2740 | */ |
dd0fc66f | 2741 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 | 2742 | { |
1da177e4 LT |
2743 | struct sk_buff *skb; |
2744 | ||
2745 | /* NOTE: No TCP options attached and we never retransmit this. */ | |
2746 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
2747 | if (!skb) { | |
4e673444 | 2748 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
1da177e4 LT |
2749 | return; |
2750 | } | |
2751 | ||
2752 | /* Reserve space for headers and prepare control bits. */ | |
2753 | skb_reserve(skb, MAX_TCP_HEADER); | |
e870a8ef | 2754 | tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
a3433f35 | 2755 | TCPHDR_ACK | TCPHDR_RST); |
1da177e4 | 2756 | /* Send it off. */ |
1da177e4 | 2757 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
dfb4b9dc | 2758 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
4e673444 | 2759 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
26af65cb | 2760 | |
81cc8a75 | 2761 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
1da177e4 LT |
2762 | } |
2763 | ||
67edfef7 AK |
2764 | /* Send a crossed SYN-ACK during socket establishment. |
2765 | * WARNING: This routine must only be called when we have already sent | |
1da177e4 LT |
2766 | * a SYN packet that crossed the incoming SYN that caused this routine |
2767 | * to get called. If this assumption fails then the initial rcv_wnd | |
2768 | * and rcv_wscale values will not be correct. | |
2769 | */ | |
2770 | int tcp_send_synack(struct sock *sk) | |
2771 | { | |
056834d9 | 2772 | struct sk_buff *skb; |
1da177e4 | 2773 | |
fe067e8a | 2774 | skb = tcp_write_queue_head(sk); |
4de075e0 | 2775 | if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
91df42be | 2776 | pr_debug("%s: wrong queue state\n", __func__); |
1da177e4 LT |
2777 | return -EFAULT; |
2778 | } | |
4de075e0 | 2779 | if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
1da177e4 LT |
2780 | if (skb_cloned(skb)) { |
2781 | struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); | |
2782 | if (nskb == NULL) | |
2783 | return -ENOMEM; | |
fe067e8a | 2784 | tcp_unlink_write_queue(skb, sk); |
1da177e4 | 2785 | skb_header_release(nskb); |
fe067e8a | 2786 | __tcp_add_write_queue_head(sk, nskb); |
3ab224be HA |
2787 | sk_wmem_free_skb(sk, skb); |
2788 | sk->sk_wmem_queued += nskb->truesize; | |
2789 | sk_mem_charge(sk, nskb->truesize); | |
1da177e4 LT |
2790 | skb = nskb; |
2791 | } | |
2792 | ||
4de075e0 | 2793 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
1da177e4 LT |
2794 | TCP_ECN_send_synack(tcp_sk(sk), skb); |
2795 | } | |
2796 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2797 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2798 | } |
2799 | ||
4aea39c1 ED |
2800 | /** |
2801 | * tcp_make_synack - Prepare a SYN-ACK. | |
2802 | * sk: listener socket | |
2803 | * dst: dst entry attached to the SYNACK | |
2804 | * req: request_sock pointer | |
2805 | * rvp: request_values pointer | |
2806 | * | |
2807 | * Allocate one skb and build a SYNACK packet. | |
2808 | * @dst is consumed : Caller should not use it again. | |
2809 | */ | |
056834d9 | 2810 | struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, |
e6b4d113 | 2811 | struct request_sock *req, |
8336886f JC |
2812 | struct request_values *rvp, |
2813 | struct tcp_fastopen_cookie *foc) | |
1da177e4 | 2814 | { |
bd0388ae | 2815 | struct tcp_out_options opts; |
4957faad | 2816 | struct tcp_extend_values *xvp = tcp_xv(rvp); |
2e6599cb | 2817 | struct inet_request_sock *ireq = inet_rsk(req); |
1da177e4 | 2818 | struct tcp_sock *tp = tcp_sk(sk); |
28b2774a | 2819 | const struct tcp_cookie_values *cvp = tp->cookie_values; |
1da177e4 | 2820 | struct tcphdr *th; |
1da177e4 | 2821 | struct sk_buff *skb; |
cfb6eeb4 | 2822 | struct tcp_md5sig_key *md5; |
bd0388ae | 2823 | int tcp_header_size; |
f5fff5dc | 2824 | int mss; |
28b2774a | 2825 | int s_data_desired = 0; |
1da177e4 | 2826 | |
28b2774a ED |
2827 | if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired) |
2828 | s_data_desired = cvp->s_data_desired; | |
99a1dec7 MG |
2829 | skb = alloc_skb(MAX_TCP_HEADER + 15 + s_data_desired, |
2830 | sk_gfp_atomic(sk, 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); |
1da177e4 | 2839 | |
0dbaee3b | 2840 | mss = dst_metric_advmss(dst); |
f5fff5dc TQ |
2841 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) |
2842 | mss = tp->rx_opt.user_mss; | |
2843 | ||
33ad798c AL |
2844 | if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ |
2845 | __u8 rcv_wscale; | |
2846 | /* Set this up on the first call only */ | |
2847 | req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); | |
e88c64f0 HPP |
2848 | |
2849 | /* limit the window selection if the user enforce a smaller rx buffer */ | |
2850 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
2851 | (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0)) | |
2852 | req->window_clamp = tcp_full_space(sk); | |
2853 | ||
33ad798c AL |
2854 | /* tcp_full_space because it is guaranteed to be the first packet */ |
2855 | tcp_select_initial_window(tcp_full_space(sk), | |
f5fff5dc | 2856 | mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
33ad798c AL |
2857 | &req->rcv_wnd, |
2858 | &req->window_clamp, | |
2859 | ireq->wscale_ok, | |
31d12926 | 2860 | &rcv_wscale, |
2861 | dst_metric(dst, RTAX_INITRWND)); | |
33ad798c AL |
2862 | ireq->rcv_wscale = rcv_wscale; |
2863 | } | |
2864 | ||
2865 | memset(&opts, 0, sizeof(opts)); | |
8b5f12d0 FW |
2866 | #ifdef CONFIG_SYN_COOKIES |
2867 | if (unlikely(req->cookie_ts)) | |
2868 | TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); | |
2869 | else | |
2870 | #endif | |
33ad798c | 2871 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
f5fff5dc | 2872 | tcp_header_size = tcp_synack_options(sk, req, mss, |
8336886f | 2873 | skb, &opts, &md5, xvp, foc) |
4957faad | 2874 | + sizeof(*th); |
cfb6eeb4 | 2875 | |
aa8223c7 ACM |
2876 | skb_push(skb, tcp_header_size); |
2877 | skb_reset_transport_header(skb); | |
1da177e4 | 2878 | |
aa8223c7 | 2879 | th = tcp_hdr(skb); |
1da177e4 LT |
2880 | memset(th, 0, sizeof(struct tcphdr)); |
2881 | th->syn = 1; | |
2882 | th->ack = 1; | |
1da177e4 | 2883 | TCP_ECN_make_synack(req, th); |
a3116ac5 | 2884 | th->source = ireq->loc_port; |
2e6599cb | 2885 | th->dest = ireq->rmt_port; |
e870a8ef IJ |
2886 | /* Setting of flags are superfluous here for callers (and ECE is |
2887 | * not even correctly set) | |
2888 | */ | |
2889 | tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, | |
a3433f35 | 2890 | TCPHDR_SYN | TCPHDR_ACK); |
4957faad WAS |
2891 | |
2892 | if (OPTION_COOKIE_EXTENSION & opts.options) { | |
28b2774a ED |
2893 | if (s_data_desired) { |
2894 | u8 *buf = skb_put(skb, s_data_desired); | |
4957faad WAS |
2895 | |
2896 | /* copy data directly from the listening socket. */ | |
28b2774a ED |
2897 | memcpy(buf, cvp->s_data_payload, s_data_desired); |
2898 | TCP_SKB_CB(skb)->end_seq += s_data_desired; | |
4957faad WAS |
2899 | } |
2900 | ||
2901 | if (opts.hash_size > 0) { | |
2902 | __u32 workspace[SHA_WORKSPACE_WORDS]; | |
2903 | u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS]; | |
2904 | u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1]; | |
2905 | ||
2906 | /* Secret recipe depends on the Timestamp, (future) | |
2907 | * Sequence and Acknowledgment Numbers, Initiator | |
2908 | * Cookie, and others handled by IP variant caller. | |
2909 | */ | |
2910 | *tail-- ^= opts.tsval; | |
2911 | *tail-- ^= tcp_rsk(req)->rcv_isn + 1; | |
2912 | *tail-- ^= TCP_SKB_CB(skb)->seq + 1; | |
2913 | ||
2914 | /* recommended */ | |
0eae88f3 | 2915 | *tail-- ^= (((__force u32)th->dest << 16) | (__force u32)th->source); |
f9a2e69e | 2916 | *tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */ |
4957faad WAS |
2917 | |
2918 | sha_transform((__u32 *)&xvp->cookie_bakery[0], | |
2919 | (char *)mess, | |
2920 | &workspace[0]); | |
2921 | opts.hash_location = | |
2922 | (__u8 *)&xvp->cookie_bakery[0]; | |
2923 | } | |
2924 | } | |
2925 | ||
1da177e4 | 2926 | th->seq = htonl(TCP_SKB_CB(skb)->seq); |
8336886f JC |
2927 | /* XXX data is queued and acked as is. No buffer/window check */ |
2928 | th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); | |
1da177e4 LT |
2929 | |
2930 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
600ff0c2 | 2931 | th->window = htons(min(req->rcv_wnd, 65535U)); |
bd0388ae | 2932 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
1da177e4 | 2933 | th->doff = (tcp_header_size >> 2); |
aa2ea058 | 2934 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb)); |
cfb6eeb4 YH |
2935 | |
2936 | #ifdef CONFIG_TCP_MD5SIG | |
2937 | /* Okay, we have all we need - do the md5 hash if needed */ | |
2938 | if (md5) { | |
bd0388ae | 2939 | tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 2940 | md5, NULL, req, skb); |
cfb6eeb4 YH |
2941 | } |
2942 | #endif | |
2943 | ||
1da177e4 LT |
2944 | return skb; |
2945 | } | |
4bc2f18b | 2946 | EXPORT_SYMBOL(tcp_make_synack); |
1da177e4 | 2947 | |
67edfef7 | 2948 | /* Do all connect socket setups that can be done AF independent. */ |
370816ae | 2949 | void tcp_connect_init(struct sock *sk) |
1da177e4 | 2950 | { |
cf533ea5 | 2951 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
2952 | struct tcp_sock *tp = tcp_sk(sk); |
2953 | __u8 rcv_wscale; | |
2954 | ||
2955 | /* We'll fix this up when we get a response from the other end. | |
2956 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
2957 | */ | |
2958 | tp->tcp_header_len = sizeof(struct tcphdr) + | |
bb5b7c11 | 2959 | (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); |
1da177e4 | 2960 | |
cfb6eeb4 YH |
2961 | #ifdef CONFIG_TCP_MD5SIG |
2962 | if (tp->af_specific->md5_lookup(sk, sk) != NULL) | |
2963 | tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; | |
2964 | #endif | |
2965 | ||
1da177e4 LT |
2966 | /* If user gave his TCP_MAXSEG, record it to clamp */ |
2967 | if (tp->rx_opt.user_mss) | |
2968 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
2969 | tp->max_window = 0; | |
5d424d5a | 2970 | tcp_mtup_init(sk); |
1da177e4 LT |
2971 | tcp_sync_mss(sk, dst_mtu(dst)); |
2972 | ||
2973 | if (!tp->window_clamp) | |
2974 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
0dbaee3b | 2975 | tp->advmss = dst_metric_advmss(dst); |
f5fff5dc TQ |
2976 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) |
2977 | tp->advmss = tp->rx_opt.user_mss; | |
2978 | ||
1da177e4 | 2979 | tcp_initialize_rcv_mss(sk); |
1da177e4 | 2980 | |
e88c64f0 HPP |
2981 | /* limit the window selection if the user enforce a smaller rx buffer */ |
2982 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
2983 | (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) | |
2984 | tp->window_clamp = tcp_full_space(sk); | |
2985 | ||
1da177e4 LT |
2986 | tcp_select_initial_window(tcp_full_space(sk), |
2987 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), | |
2988 | &tp->rcv_wnd, | |
2989 | &tp->window_clamp, | |
bb5b7c11 | 2990 | sysctl_tcp_window_scaling, |
31d12926 | 2991 | &rcv_wscale, |
2992 | dst_metric(dst, RTAX_INITRWND)); | |
1da177e4 LT |
2993 | |
2994 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
2995 | tp->rcv_ssthresh = tp->rcv_wnd; | |
2996 | ||
2997 | sk->sk_err = 0; | |
2998 | sock_reset_flag(sk, SOCK_DONE); | |
2999 | tp->snd_wnd = 0; | |
ee7537b6 | 3000 | tcp_init_wl(tp, 0); |
1da177e4 LT |
3001 | tp->snd_una = tp->write_seq; |
3002 | tp->snd_sml = tp->write_seq; | |
33f5f57e | 3003 | tp->snd_up = tp->write_seq; |
370816ae | 3004 | tp->snd_nxt = tp->write_seq; |
ee995283 PE |
3005 | |
3006 | if (likely(!tp->repair)) | |
3007 | tp->rcv_nxt = 0; | |
3008 | tp->rcv_wup = tp->rcv_nxt; | |
3009 | tp->copied_seq = tp->rcv_nxt; | |
1da177e4 | 3010 | |
463c84b9 ACM |
3011 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
3012 | inet_csk(sk)->icsk_retransmits = 0; | |
1da177e4 LT |
3013 | tcp_clear_retrans(tp); |
3014 | } | |
3015 | ||
783237e8 YC |
3016 | static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
3017 | { | |
3018 | struct tcp_sock *tp = tcp_sk(sk); | |
3019 | struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); | |
3020 | ||
3021 | tcb->end_seq += skb->len; | |
3022 | skb_header_release(skb); | |
3023 | __tcp_add_write_queue_tail(sk, skb); | |
3024 | sk->sk_wmem_queued += skb->truesize; | |
3025 | sk_mem_charge(sk, skb->truesize); | |
3026 | tp->write_seq = tcb->end_seq; | |
3027 | tp->packets_out += tcp_skb_pcount(skb); | |
3028 | } | |
3029 | ||
3030 | /* Build and send a SYN with data and (cached) Fast Open cookie. However, | |
3031 | * queue a data-only packet after the regular SYN, such that regular SYNs | |
3032 | * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges | |
3033 | * only the SYN sequence, the data are retransmitted in the first ACK. | |
3034 | * If cookie is not cached or other error occurs, falls back to send a | |
3035 | * regular SYN with Fast Open cookie request option. | |
3036 | */ | |
3037 | static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) | |
3038 | { | |
3039 | struct tcp_sock *tp = tcp_sk(sk); | |
3040 | struct tcp_fastopen_request *fo = tp->fastopen_req; | |
aab48743 | 3041 | int syn_loss = 0, space, i, err = 0, iovlen = fo->data->msg_iovlen; |
783237e8 | 3042 | struct sk_buff *syn_data = NULL, *data; |
aab48743 YC |
3043 | unsigned long last_syn_loss = 0; |
3044 | ||
67da22d2 | 3045 | tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
aab48743 YC |
3046 | tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, |
3047 | &syn_loss, &last_syn_loss); | |
3048 | /* Recurring FO SYN losses: revert to regular handshake temporarily */ | |
3049 | if (syn_loss > 1 && | |
3050 | time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { | |
3051 | fo->cookie.len = -1; | |
3052 | goto fallback; | |
3053 | } | |
783237e8 | 3054 | |
67da22d2 YC |
3055 | if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) |
3056 | fo->cookie.len = -1; | |
3057 | else if (fo->cookie.len <= 0) | |
783237e8 YC |
3058 | goto fallback; |
3059 | ||
3060 | /* MSS for SYN-data is based on cached MSS and bounded by PMTU and | |
3061 | * user-MSS. Reserve maximum option space for middleboxes that add | |
3062 | * private TCP options. The cost is reduced data space in SYN :( | |
3063 | */ | |
3064 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp) | |
3065 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
1b63edd6 | 3066 | space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - |
783237e8 YC |
3067 | MAX_TCP_OPTION_SPACE; |
3068 | ||
3069 | syn_data = skb_copy_expand(syn, skb_headroom(syn), space, | |
3070 | sk->sk_allocation); | |
3071 | if (syn_data == NULL) | |
3072 | goto fallback; | |
3073 | ||
3074 | for (i = 0; i < iovlen && syn_data->len < space; ++i) { | |
3075 | struct iovec *iov = &fo->data->msg_iov[i]; | |
3076 | unsigned char __user *from = iov->iov_base; | |
3077 | int len = iov->iov_len; | |
3078 | ||
3079 | if (syn_data->len + len > space) | |
3080 | len = space - syn_data->len; | |
3081 | else if (i + 1 == iovlen) | |
3082 | /* No more data pending in inet_wait_for_connect() */ | |
3083 | fo->data = NULL; | |
3084 | ||
3085 | if (skb_add_data(syn_data, from, len)) | |
3086 | goto fallback; | |
3087 | } | |
3088 | ||
3089 | /* Queue a data-only packet after the regular SYN for retransmission */ | |
3090 | data = pskb_copy(syn_data, sk->sk_allocation); | |
3091 | if (data == NULL) | |
3092 | goto fallback; | |
3093 | TCP_SKB_CB(data)->seq++; | |
3094 | TCP_SKB_CB(data)->tcp_flags &= ~TCPHDR_SYN; | |
3095 | TCP_SKB_CB(data)->tcp_flags = (TCPHDR_ACK|TCPHDR_PSH); | |
3096 | tcp_connect_queue_skb(sk, data); | |
3097 | fo->copied = data->len; | |
3098 | ||
3099 | if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) { | |
67da22d2 | 3100 | tp->syn_data = (fo->copied > 0); |
783237e8 YC |
3101 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVE); |
3102 | goto done; | |
3103 | } | |
3104 | syn_data = NULL; | |
3105 | ||
3106 | fallback: | |
3107 | /* Send a regular SYN with Fast Open cookie request option */ | |
3108 | if (fo->cookie.len > 0) | |
3109 | fo->cookie.len = 0; | |
3110 | err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); | |
3111 | if (err) | |
3112 | tp->syn_fastopen = 0; | |
3113 | kfree_skb(syn_data); | |
3114 | done: | |
3115 | fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ | |
3116 | return err; | |
3117 | } | |
3118 | ||
67edfef7 | 3119 | /* Build a SYN and send it off. */ |
1da177e4 LT |
3120 | int tcp_connect(struct sock *sk) |
3121 | { | |
3122 | struct tcp_sock *tp = tcp_sk(sk); | |
3123 | struct sk_buff *buff; | |
ee586811 | 3124 | int err; |
1da177e4 LT |
3125 | |
3126 | tcp_connect_init(sk); | |
3127 | ||
2b916477 AV |
3128 | if (unlikely(tp->repair)) { |
3129 | tcp_finish_connect(sk, NULL); | |
3130 | return 0; | |
3131 | } | |
3132 | ||
d179cd12 | 3133 | buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); |
1da177e4 LT |
3134 | if (unlikely(buff == NULL)) |
3135 | return -ENOBUFS; | |
3136 | ||
3137 | /* Reserve space for headers. */ | |
3138 | skb_reserve(buff, MAX_TCP_HEADER); | |
3139 | ||
a3433f35 | 3140 | tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
783237e8 YC |
3141 | tp->retrans_stamp = TCP_SKB_CB(buff)->when = tcp_time_stamp; |
3142 | tcp_connect_queue_skb(sk, buff); | |
e870a8ef | 3143 | TCP_ECN_send_syn(sk, buff); |
1da177e4 | 3144 | |
783237e8 YC |
3145 | /* Send off SYN; include data in Fast Open. */ |
3146 | err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : | |
3147 | tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); | |
ee586811 EP |
3148 | if (err == -ECONNREFUSED) |
3149 | return err; | |
bd37a088 WY |
3150 | |
3151 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
3152 | * in order to make this packet get counted in tcpOutSegs. | |
3153 | */ | |
3154 | tp->snd_nxt = tp->write_seq; | |
3155 | tp->pushed_seq = tp->write_seq; | |
81cc8a75 | 3156 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
1da177e4 LT |
3157 | |
3158 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
3159 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3160 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
3161 | return 0; |
3162 | } | |
4bc2f18b | 3163 | EXPORT_SYMBOL(tcp_connect); |
1da177e4 LT |
3164 | |
3165 | /* Send out a delayed ack, the caller does the policy checking | |
3166 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
3167 | * for details. | |
3168 | */ | |
3169 | void tcp_send_delayed_ack(struct sock *sk) | |
3170 | { | |
463c84b9 ACM |
3171 | struct inet_connection_sock *icsk = inet_csk(sk); |
3172 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
3173 | unsigned long timeout; |
3174 | ||
3175 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 3176 | const struct tcp_sock *tp = tcp_sk(sk); |
056834d9 | 3177 | int max_ato = HZ / 2; |
1da177e4 | 3178 | |
056834d9 IJ |
3179 | if (icsk->icsk_ack.pingpong || |
3180 | (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) | |
1da177e4 LT |
3181 | max_ato = TCP_DELACK_MAX; |
3182 | ||
3183 | /* Slow path, intersegment interval is "high". */ | |
3184 | ||
3185 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 3186 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
3187 | * directly. |
3188 | */ | |
3189 | if (tp->srtt) { | |
056834d9 | 3190 | int rtt = max(tp->srtt >> 3, TCP_DELACK_MIN); |
1da177e4 LT |
3191 | |
3192 | if (rtt < max_ato) | |
3193 | max_ato = rtt; | |
3194 | } | |
3195 | ||
3196 | ato = min(ato, max_ato); | |
3197 | } | |
3198 | ||
3199 | /* Stay within the limit we were given */ | |
3200 | timeout = jiffies + ato; | |
3201 | ||
3202 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 3203 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
3204 | /* If delack timer was blocked or is about to expire, |
3205 | * send ACK now. | |
3206 | */ | |
463c84b9 ACM |
3207 | if (icsk->icsk_ack.blocked || |
3208 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
3209 | tcp_send_ack(sk); |
3210 | return; | |
3211 | } | |
3212 | ||
463c84b9 ACM |
3213 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
3214 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 3215 | } |
463c84b9 ACM |
3216 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
3217 | icsk->icsk_ack.timeout = timeout; | |
3218 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
3219 | } |
3220 | ||
3221 | /* This routine sends an ack and also updates the window. */ | |
3222 | void tcp_send_ack(struct sock *sk) | |
3223 | { | |
058dc334 | 3224 | struct sk_buff *buff; |
1da177e4 | 3225 | |
058dc334 IJ |
3226 | /* If we have been reset, we may not send again. */ |
3227 | if (sk->sk_state == TCP_CLOSE) | |
3228 | return; | |
1da177e4 | 3229 | |
058dc334 IJ |
3230 | /* We are not putting this on the write queue, so |
3231 | * tcp_transmit_skb() will set the ownership to this | |
3232 | * sock. | |
3233 | */ | |
99a1dec7 | 3234 | buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); |
058dc334 IJ |
3235 | if (buff == NULL) { |
3236 | inet_csk_schedule_ack(sk); | |
3237 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3238 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, | |
3239 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
3240 | return; | |
1da177e4 | 3241 | } |
058dc334 IJ |
3242 | |
3243 | /* Reserve space for headers and prepare control bits. */ | |
3244 | skb_reserve(buff, MAX_TCP_HEADER); | |
a3433f35 | 3245 | tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
058dc334 IJ |
3246 | |
3247 | /* Send it off, this clears delayed acks for us. */ | |
058dc334 | 3248 | TCP_SKB_CB(buff)->when = tcp_time_stamp; |
99a1dec7 | 3249 | tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); |
1da177e4 LT |
3250 | } |
3251 | ||
3252 | /* This routine sends a packet with an out of date sequence | |
3253 | * number. It assumes the other end will try to ack it. | |
3254 | * | |
3255 | * Question: what should we make while urgent mode? | |
3256 | * 4.4BSD forces sending single byte of data. We cannot send | |
3257 | * out of window data, because we have SND.NXT==SND.MAX... | |
3258 | * | |
3259 | * Current solution: to send TWO zero-length segments in urgent mode: | |
3260 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
3261 | * out-of-date with SND.UNA-1 to probe window. | |
3262 | */ | |
3263 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent) | |
3264 | { | |
3265 | struct tcp_sock *tp = tcp_sk(sk); | |
3266 | struct sk_buff *skb; | |
3267 | ||
3268 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
99a1dec7 | 3269 | skb = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC)); |
e905a9ed | 3270 | if (skb == NULL) |
1da177e4 LT |
3271 | return -1; |
3272 | ||
3273 | /* Reserve space for headers and set control bits. */ | |
3274 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 LT |
3275 | /* Use a previous sequence. This should cause the other |
3276 | * end to send an ack. Don't queue or clone SKB, just | |
3277 | * send it. | |
3278 | */ | |
a3433f35 | 3279 | tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
1da177e4 | 3280 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
dfb4b9dc | 3281 | return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); |
1da177e4 LT |
3282 | } |
3283 | ||
ee995283 PE |
3284 | void tcp_send_window_probe(struct sock *sk) |
3285 | { | |
3286 | if (sk->sk_state == TCP_ESTABLISHED) { | |
3287 | tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; | |
c0e88ff0 | 3288 | tcp_sk(sk)->snd_nxt = tcp_sk(sk)->write_seq; |
ee995283 PE |
3289 | tcp_xmit_probe_skb(sk, 0); |
3290 | } | |
3291 | } | |
3292 | ||
67edfef7 | 3293 | /* Initiate keepalive or window probe from timer. */ |
1da177e4 LT |
3294 | int tcp_write_wakeup(struct sock *sk) |
3295 | { | |
058dc334 IJ |
3296 | struct tcp_sock *tp = tcp_sk(sk); |
3297 | struct sk_buff *skb; | |
1da177e4 | 3298 | |
058dc334 IJ |
3299 | if (sk->sk_state == TCP_CLOSE) |
3300 | return -1; | |
3301 | ||
3302 | if ((skb = tcp_send_head(sk)) != NULL && | |
3303 | before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { | |
3304 | int err; | |
0c54b85f | 3305 | unsigned int mss = tcp_current_mss(sk); |
058dc334 IJ |
3306 | unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
3307 | ||
3308 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
3309 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
3310 | ||
3311 | /* We are probing the opening of a window | |
3312 | * but the window size is != 0 | |
3313 | * must have been a result SWS avoidance ( sender ) | |
3314 | */ | |
3315 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
3316 | skb->len > mss) { | |
3317 | seg_size = min(seg_size, mss); | |
4de075e0 | 3318 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3319 | if (tcp_fragment(sk, skb, seg_size, mss)) |
3320 | return -1; | |
3321 | } else if (!tcp_skb_pcount(skb)) | |
3322 | tcp_set_skb_tso_segs(sk, skb, mss); | |
3323 | ||
4de075e0 | 3324 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
3325 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
3326 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); | |
3327 | if (!err) | |
3328 | tcp_event_new_data_sent(sk, skb); | |
3329 | return err; | |
3330 | } else { | |
33f5f57e | 3331 | if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
058dc334 IJ |
3332 | tcp_xmit_probe_skb(sk, 1); |
3333 | return tcp_xmit_probe_skb(sk, 0); | |
1da177e4 | 3334 | } |
1da177e4 LT |
3335 | } |
3336 | ||
3337 | /* A window probe timeout has occurred. If window is not closed send | |
3338 | * a partial packet else a zero probe. | |
3339 | */ | |
3340 | void tcp_send_probe0(struct sock *sk) | |
3341 | { | |
463c84b9 | 3342 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
3343 | struct tcp_sock *tp = tcp_sk(sk); |
3344 | int err; | |
3345 | ||
3346 | err = tcp_write_wakeup(sk); | |
3347 | ||
fe067e8a | 3348 | if (tp->packets_out || !tcp_send_head(sk)) { |
1da177e4 | 3349 | /* Cancel probe timer, if it is not required. */ |
6687e988 | 3350 | icsk->icsk_probes_out = 0; |
463c84b9 | 3351 | icsk->icsk_backoff = 0; |
1da177e4 LT |
3352 | return; |
3353 | } | |
3354 | ||
3355 | if (err <= 0) { | |
463c84b9 ACM |
3356 | if (icsk->icsk_backoff < sysctl_tcp_retries2) |
3357 | icsk->icsk_backoff++; | |
6687e988 | 3358 | icsk->icsk_probes_out++; |
e905a9ed | 3359 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
3f421baa ACM |
3360 | min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), |
3361 | TCP_RTO_MAX); | |
1da177e4 LT |
3362 | } else { |
3363 | /* If packet was not sent due to local congestion, | |
6687e988 | 3364 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
3365 | * Let local senders to fight for local resources. |
3366 | * | |
3367 | * Use accumulated backoff yet. | |
3368 | */ | |
6687e988 ACM |
3369 | if (!icsk->icsk_probes_out) |
3370 | icsk->icsk_probes_out = 1; | |
e905a9ed | 3371 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
463c84b9 | 3372 | min(icsk->icsk_rto << icsk->icsk_backoff, |
3f421baa ACM |
3373 | TCP_RESOURCE_PROBE_INTERVAL), |
3374 | TCP_RTO_MAX); | |
1da177e4 LT |
3375 | } |
3376 | } |