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Linux 2.6.25.20
[linux/fpc-iii.git] / net / dccp / ccids / ccid2.c
blobb5b52ebb2693d308d46deee5e6c5f6a5e27d7199
1 /*
2 * net/dccp/ccids/ccid2.c
3 *
4 * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
5 *
6 * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
7 *
8 * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 */
24
25 /*
26 * This implementation should follow RFC 4341
27 */
28
29 #include "../ccid.h"
30 #include "../dccp.h"
31 #include "ccid2.h"
32
33
34 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
35 static int ccid2_debug;
36 #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
37
38 static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
39 {
40 int len = 0;
41 int pipe = 0;
42 struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
43
44 /* there is data in the chain */
45 if (seqp != hctx->ccid2hctx_seqt) {
46 seqp = seqp->ccid2s_prev;
47 len++;
48 if (!seqp->ccid2s_acked)
49 pipe++;
50
51 while (seqp != hctx->ccid2hctx_seqt) {
52 struct ccid2_seq *prev = seqp->ccid2s_prev;
53
54 len++;
55 if (!prev->ccid2s_acked)
56 pipe++;
57
58 /* packets are sent sequentially */
59 BUG_ON(dccp_delta_seqno(seqp->ccid2s_seq,
60 prev->ccid2s_seq ) >= 0);
61 BUG_ON(time_before(seqp->ccid2s_sent,
62 prev->ccid2s_sent));
63
64 seqp = prev;
65 }
66 }
67
68 BUG_ON(pipe != hctx->ccid2hctx_pipe);
69 ccid2_pr_debug("len of chain=%d\n", len);
70
71 do {
72 seqp = seqp->ccid2s_prev;
73 len++;
74 } while (seqp != hctx->ccid2hctx_seqh);
75
76 ccid2_pr_debug("total len=%d\n", len);
77 BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
78 }
79 #else
80 #define ccid2_pr_debug(format, a...)
81 #define ccid2_hc_tx_check_sanity(hctx)
82 #endif
83
84 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
85 {
86 struct ccid2_seq *seqp;
87 int i;
88
89 /* check if we have space to preserve the pointer to the buffer */
90 if (hctx->ccid2hctx_seqbufc >= (sizeof(hctx->ccid2hctx_seqbuf) /
91 sizeof(struct ccid2_seq*)))
92 return -ENOMEM;
93
94 /* allocate buffer and initialize linked list */
95 seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any());
96 if (seqp == NULL)
97 return -ENOMEM;
98
99 for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
100 seqp[i].ccid2s_next = &seqp[i + 1];
101 seqp[i + 1].ccid2s_prev = &seqp[i];
102 }
103 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
104 seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
105
106 /* This is the first allocation. Initiate the head and tail. */
107 if (hctx->ccid2hctx_seqbufc == 0)
108 hctx->ccid2hctx_seqh = hctx->ccid2hctx_seqt = seqp;
109 else {
110 /* link the existing list with the one we just created */
111 hctx->ccid2hctx_seqh->ccid2s_next = seqp;
112 seqp->ccid2s_prev = hctx->ccid2hctx_seqh;
113
114 hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
115 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
116 }
117
118 /* store the original pointer to the buffer so we can free it */
119 hctx->ccid2hctx_seqbuf[hctx->ccid2hctx_seqbufc] = seqp;
120 hctx->ccid2hctx_seqbufc++;
121
122 return 0;
123 }
124
125 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
126 {
127 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
128
129 if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd)
130 return 0;
131
132 return 1; /* XXX CCID should dequeue when ready instead of polling */
133 }
134
135 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
136 {
137 struct dccp_sock *dp = dccp_sk(sk);
138 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
139
140 /*
141 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
142 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
143 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
144 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
145 */
146 if (val == 0 || val > max_ratio) {
147 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
148 val = max_ratio;
149 }
150 if (val > 0xFFFF) /* RFC 4340, 11.3 */
151 val = 0xFFFF;
152
153 if (val == dp->dccps_l_ack_ratio)
154 return;
155
156 ccid2_pr_debug("changing local ack ratio to %u\n", val);
157 dp->dccps_l_ack_ratio = val;
158 }
159
160 static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
161 {
162 ccid2_pr_debug("change SRTT to %ld\n", val);
163 hctx->ccid2hctx_srtt = val;
164 }
165
166 static void ccid2_start_rto_timer(struct sock *sk);
167
168 static void ccid2_hc_tx_rto_expire(unsigned long data)
169 {
170 struct sock *sk = (struct sock *)data;
171 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
172 long s;
173
174 bh_lock_sock(sk);
175 if (sock_owned_by_user(sk)) {
176 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
177 jiffies + HZ / 5);
178 goto out;
179 }
180
181 ccid2_pr_debug("RTO_EXPIRE\n");
182
183 ccid2_hc_tx_check_sanity(hctx);
184
185 /* back-off timer */
186 hctx->ccid2hctx_rto <<= 1;
187
188 s = hctx->ccid2hctx_rto / HZ;
189 if (s > 60)
190 hctx->ccid2hctx_rto = 60 * HZ;
191
192 ccid2_start_rto_timer(sk);
193
194 /* adjust pipe, cwnd etc */
195 hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
196 if (hctx->ccid2hctx_ssthresh < 2)
197 hctx->ccid2hctx_ssthresh = 2;
198 hctx->ccid2hctx_cwnd = 1;
199 hctx->ccid2hctx_pipe = 0;
200
201 /* clear state about stuff we sent */
202 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
203 hctx->ccid2hctx_packets_acked = 0;
204
205 /* clear ack ratio state. */
206 hctx->ccid2hctx_rpseq = 0;
207 hctx->ccid2hctx_rpdupack = -1;
208 ccid2_change_l_ack_ratio(sk, 1);
209 ccid2_hc_tx_check_sanity(hctx);
210 out:
211 bh_unlock_sock(sk);
212 sock_put(sk);
213 }
214
215 static void ccid2_start_rto_timer(struct sock *sk)
216 {
217 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
218
219 ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
220
221 BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
222 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
223 jiffies + hctx->ccid2hctx_rto);
224 }
225
226 static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
227 {
228 struct dccp_sock *dp = dccp_sk(sk);
229 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
230 struct ccid2_seq *next;
231
232 hctx->ccid2hctx_pipe++;
233
234 hctx->ccid2hctx_seqh->ccid2s_seq = dp->dccps_gss;
235 hctx->ccid2hctx_seqh->ccid2s_acked = 0;
236 hctx->ccid2hctx_seqh->ccid2s_sent = jiffies;
237
238 next = hctx->ccid2hctx_seqh->ccid2s_next;
239 /* check if we need to alloc more space */
240 if (next == hctx->ccid2hctx_seqt) {
241 if (ccid2_hc_tx_alloc_seq(hctx)) {
242 DCCP_CRIT("packet history - out of memory!");
243 /* FIXME: find a more graceful way to bail out */
244 return;
245 }
246 next = hctx->ccid2hctx_seqh->ccid2s_next;
247 BUG_ON(next == hctx->ccid2hctx_seqt);
248 }
249 hctx->ccid2hctx_seqh = next;
250
251 ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
252 hctx->ccid2hctx_pipe);
253
254 /*
255 * FIXME: The code below is broken and the variables have been removed
256 * from the socket struct. The `ackloss' variable was always set to 0,
257 * and with arsent there are several problems:
258 * (i) it doesn't just count the number of Acks, but all sent packets;
259 * (ii) it is expressed in # of packets, not # of windows, so the
260 * comparison below uses the wrong formula: Appendix A of RFC 4341
261 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
262 * of data with no lost or marked Ack packets. If arsent were the # of
263 * consecutive Acks received without loss, then Ack Ratio needs to be
264 * decreased by 1 when
265 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
266 * where cwnd / R is the number of Acks received per window of data
267 * (cf. RFC 4341, App. A). The problems are that
268 * - arsent counts other packets as well;
269 * - the comparison uses a formula different from RFC 4341;
270 * - computing a cubic/quadratic equation each time is too complicated.
271 * Hence a different algorithm is needed.
272 */
273 #if 0
274 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
275 hctx->ccid2hctx_arsent++;
276 /* We had an ack loss in this window... */
277 if (hctx->ccid2hctx_ackloss) {
278 if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
279 hctx->ccid2hctx_arsent = 0;
280 hctx->ccid2hctx_ackloss = 0;
281 }
282 } else {
283 /* No acks lost up to now... */
284 /* decrease ack ratio if enough packets were sent */
285 if (dp->dccps_l_ack_ratio > 1) {
286 /* XXX don't calculate denominator each time */
287 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
288 dp->dccps_l_ack_ratio;
289
290 denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
291
292 if (hctx->ccid2hctx_arsent >= denom) {
293 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
294 hctx->ccid2hctx_arsent = 0;
295 }
296 } else {
297 /* we can't increase ack ratio further [1] */
298 hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
299 }
300 }
301 #endif
302
303 /* setup RTO timer */
304 if (!timer_pending(&hctx->ccid2hctx_rtotimer))
305 ccid2_start_rto_timer(sk);
306
307 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
308 do {
309 struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
310
311 while (seqp != hctx->ccid2hctx_seqh) {
312 ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
313 (unsigned long long)seqp->ccid2s_seq,
314 seqp->ccid2s_acked, seqp->ccid2s_sent);
315 seqp = seqp->ccid2s_next;
316 }
317 } while (0);
318 ccid2_pr_debug("=========\n");
319 ccid2_hc_tx_check_sanity(hctx);
320 #endif
321 }
322
323 /* XXX Lame code duplication!
324 * returns -1 if none was found.
325 * else returns the next offset to use in the function call.
326 */
327 static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
328 unsigned char **vec, unsigned char *veclen)
329 {
330 const struct dccp_hdr *dh = dccp_hdr(skb);
331 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
332 unsigned char *opt_ptr;
333 const unsigned char *opt_end = (unsigned char *)dh +
334 (dh->dccph_doff * 4);
335 unsigned char opt, len;
336 unsigned char *value;
337
338 BUG_ON(offset < 0);
339 options += offset;
340 opt_ptr = options;
341 if (opt_ptr >= opt_end)
342 return -1;
343
344 while (opt_ptr != opt_end) {
345 opt = *opt_ptr++;
346 len = 0;
347 value = NULL;
348
349 /* Check if this isn't a single byte option */
350 if (opt > DCCPO_MAX_RESERVED) {
351 if (opt_ptr == opt_end)
352 goto out_invalid_option;
353
354 len = *opt_ptr++;
355 if (len < 3)
356 goto out_invalid_option;
357 /*
358 * Remove the type and len fields, leaving
359 * just the value size
360 */
361 len -= 2;
362 value = opt_ptr;
363 opt_ptr += len;
364
365 if (opt_ptr > opt_end)
366 goto out_invalid_option;
367 }
368
369 switch (opt) {
370 case DCCPO_ACK_VECTOR_0:
371 case DCCPO_ACK_VECTOR_1:
372 *vec = value;
373 *veclen = len;
374 return offset + (opt_ptr - options);
375 }
376 }
377
378 return -1;
379
380 out_invalid_option:
381 DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
382 return -1;
383 }
384
385 static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
386 {
387 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
388
389 sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
390 ccid2_pr_debug("deleted RTO timer\n");
391 }
392
393 static inline void ccid2_new_ack(struct sock *sk,
394 struct ccid2_seq *seqp,
395 unsigned int *maxincr)
396 {
397 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
398
399 if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
400 if (*maxincr > 0 && ++hctx->ccid2hctx_packets_acked == 2) {
401 hctx->ccid2hctx_cwnd += 1;
402 *maxincr -= 1;
403 hctx->ccid2hctx_packets_acked = 0;
404 }
405 } else if (++hctx->ccid2hctx_packets_acked >= hctx->ccid2hctx_cwnd) {
406 hctx->ccid2hctx_cwnd += 1;
407 hctx->ccid2hctx_packets_acked = 0;
408 }
409
410 /* update RTO */
411 if (hctx->ccid2hctx_srtt == -1 ||
412 time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
413 unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
414 int s;
415
416 /* first measurement */
417 if (hctx->ccid2hctx_srtt == -1) {
418 ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
419 r, jiffies,
420 (unsigned long long)seqp->ccid2s_seq);
421 ccid2_change_srtt(hctx, r);
422 hctx->ccid2hctx_rttvar = r >> 1;
423 } else {
424 /* RTTVAR */
425 long tmp = hctx->ccid2hctx_srtt - r;
426 long srtt;
427
428 if (tmp < 0)
429 tmp *= -1;
430
431 tmp >>= 2;
432 hctx->ccid2hctx_rttvar *= 3;
433 hctx->ccid2hctx_rttvar >>= 2;
434 hctx->ccid2hctx_rttvar += tmp;
435
436 /* SRTT */
437 srtt = hctx->ccid2hctx_srtt;
438 srtt *= 7;
439 srtt >>= 3;
440 tmp = r >> 3;
441 srtt += tmp;
442 ccid2_change_srtt(hctx, srtt);
443 }
444 s = hctx->ccid2hctx_rttvar << 2;
445 /* clock granularity is 1 when based on jiffies */
446 if (!s)
447 s = 1;
448 hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
449
450 /* must be at least a second */
451 s = hctx->ccid2hctx_rto / HZ;
452 /* DCCP doesn't require this [but I like it cuz my code sux] */
453 #if 1
454 if (s < 1)
455 hctx->ccid2hctx_rto = HZ;
456 #endif
457 /* max 60 seconds */
458 if (s > 60)
459 hctx->ccid2hctx_rto = HZ * 60;
460
461 hctx->ccid2hctx_lastrtt = jiffies;
462
463 ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
464 hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
465 hctx->ccid2hctx_rto, HZ, r);
466 }
467
468 /* we got a new ack, so re-start RTO timer */
469 ccid2_hc_tx_kill_rto_timer(sk);
470 ccid2_start_rto_timer(sk);
471 }
472
473 static void ccid2_hc_tx_dec_pipe(struct sock *sk)
474 {
475 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
476
477 if (hctx->ccid2hctx_pipe == 0)
478 DCCP_BUG("pipe == 0");
479 else
480 hctx->ccid2hctx_pipe--;
481
482 if (hctx->ccid2hctx_pipe == 0)
483 ccid2_hc_tx_kill_rto_timer(sk);
484 }
485
486 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
487 {
488 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
489
490 if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
491 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
492 return;
493 }
494
495 hctx->ccid2hctx_last_cong = jiffies;
496
497 hctx->ccid2hctx_cwnd = hctx->ccid2hctx_cwnd / 2 ? : 1U;
498 hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
499
500 /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
501 if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
502 ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
503 }
504
505 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
506 {
507 struct dccp_sock *dp = dccp_sk(sk);
508 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
509 u64 ackno, seqno;
510 struct ccid2_seq *seqp;
511 unsigned char *vector;
512 unsigned char veclen;
513 int offset = 0;
514 int done = 0;
515 unsigned int maxincr = 0;
516
517 ccid2_hc_tx_check_sanity(hctx);
518 /* check reverse path congestion */
519 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
520
521 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
522 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
523 * -sorbo.
524 */
525 /* need to bootstrap */
526 if (hctx->ccid2hctx_rpdupack == -1) {
527 hctx->ccid2hctx_rpdupack = 0;
528 hctx->ccid2hctx_rpseq = seqno;
529 } else {
530 /* check if packet is consecutive */
531 if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
532 hctx->ccid2hctx_rpseq = seqno;
533 /* it's a later packet */
534 else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
535 hctx->ccid2hctx_rpdupack++;
536
537 /* check if we got enough dupacks */
538 if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
539 hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
540 hctx->ccid2hctx_rpseq = 0;
541
542 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
543 }
544 }
545 }
546
547 /* check forward path congestion */
548 /* still didn't send out new data packets */
549 if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
550 return;
551
552 switch (DCCP_SKB_CB(skb)->dccpd_type) {
553 case DCCP_PKT_ACK:
554 case DCCP_PKT_DATAACK:
555 break;
556 default:
557 return;
558 }
559
560 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
561 if (after48(ackno, hctx->ccid2hctx_high_ack))
562 hctx->ccid2hctx_high_ack = ackno;
563
564 seqp = hctx->ccid2hctx_seqt;
565 while (before48(seqp->ccid2s_seq, ackno)) {
566 seqp = seqp->ccid2s_next;
567 if (seqp == hctx->ccid2hctx_seqh) {
568 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
569 break;
570 }
571 }
572
573 /*
574 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
575 * packets per acknowledgement. Rounding up avoids that cwnd is not
576 * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
577 */
578 if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh)
579 maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
580
581 /* go through all ack vectors */
582 while ((offset = ccid2_ackvector(sk, skb, offset,
583 &vector, &veclen)) != -1) {
584 /* go through this ack vector */
585 while (veclen--) {
586 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
587 u64 ackno_end_rl = SUB48(ackno, rl);
588
589 ccid2_pr_debug("ackvec start:%llu end:%llu\n",
590 (unsigned long long)ackno,
591 (unsigned long long)ackno_end_rl);
592 /* if the seqno we are analyzing is larger than the
593 * current ackno, then move towards the tail of our
594 * seqnos.
595 */
596 while (after48(seqp->ccid2s_seq, ackno)) {
597 if (seqp == hctx->ccid2hctx_seqt) {
598 done = 1;
599 break;
600 }
601 seqp = seqp->ccid2s_prev;
602 }
603 if (done)
604 break;
605
606 /* check all seqnos in the range of the vector
607 * run length
608 */
609 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
610 const u8 state = *vector &
611 DCCP_ACKVEC_STATE_MASK;
612
613 /* new packet received or marked */
614 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
615 !seqp->ccid2s_acked) {
616 if (state ==
617 DCCP_ACKVEC_STATE_ECN_MARKED) {
618 ccid2_congestion_event(sk,
619 seqp);
620 } else
621 ccid2_new_ack(sk, seqp,
622 &maxincr);
623
624 seqp->ccid2s_acked = 1;
625 ccid2_pr_debug("Got ack for %llu\n",
626 (unsigned long long)seqp->ccid2s_seq);
627 ccid2_hc_tx_dec_pipe(sk);
628 }
629 if (seqp == hctx->ccid2hctx_seqt) {
630 done = 1;
631 break;
632 }
633 seqp = seqp->ccid2s_prev;
634 }
635 if (done)
636 break;
637
638 ackno = SUB48(ackno_end_rl, 1);
639 vector++;
640 }
641 if (done)
642 break;
643 }
644
645 /* The state about what is acked should be correct now
646 * Check for NUMDUPACK
647 */
648 seqp = hctx->ccid2hctx_seqt;
649 while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
650 seqp = seqp->ccid2s_next;
651 if (seqp == hctx->ccid2hctx_seqh) {
652 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
653 break;
654 }
655 }
656 done = 0;
657 while (1) {
658 if (seqp->ccid2s_acked) {
659 done++;
660 if (done == NUMDUPACK)
661 break;
662 }
663 if (seqp == hctx->ccid2hctx_seqt)
664 break;
665 seqp = seqp->ccid2s_prev;
666 }
667
668 /* If there are at least 3 acknowledgements, anything unacknowledged
669 * below the last sequence number is considered lost
670 */
671 if (done == NUMDUPACK) {
672 struct ccid2_seq *last_acked = seqp;
673
674 /* check for lost packets */
675 while (1) {
676 if (!seqp->ccid2s_acked) {
677 ccid2_pr_debug("Packet lost: %llu\n",
678 (unsigned long long)seqp->ccid2s_seq);
679 /* XXX need to traverse from tail -> head in
680 * order to detect multiple congestion events in
681 * one ack vector.
682 */
683 ccid2_congestion_event(sk, seqp);
684 ccid2_hc_tx_dec_pipe(sk);
685 }
686 if (seqp == hctx->ccid2hctx_seqt)
687 break;
688 seqp = seqp->ccid2s_prev;
689 }
690
691 hctx->ccid2hctx_seqt = last_acked;
692 }
693
694 /* trim acked packets in tail */
695 while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
696 if (!hctx->ccid2hctx_seqt->ccid2s_acked)
697 break;
698
699 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
700 }
701
702 ccid2_hc_tx_check_sanity(hctx);
703 }
704
705 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
706 {
707 struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
708 struct dccp_sock *dp = dccp_sk(sk);
709 u32 max_ratio;
710
711 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
712 hctx->ccid2hctx_ssthresh = ~0U;
713
714 /*
715 * RFC 4341, 5: "The cwnd parameter is initialized to at most four
716 * packets for new connections, following the rules from [RFC3390]".
717 * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
718 */
719 hctx->ccid2hctx_cwnd = min(4U, max(2U, 4380U / dp->dccps_mss_cache));
720
721 /* Make sure that Ack Ratio is enabled and within bounds. */
722 max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
723 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
724 dp->dccps_l_ack_ratio = max_ratio;
725
726 /* XXX init ~ to window size... */
727 if (ccid2_hc_tx_alloc_seq(hctx))
728 return -ENOMEM;
729
730 hctx->ccid2hctx_rto = 3 * HZ;
731 ccid2_change_srtt(hctx, -1);
732 hctx->ccid2hctx_rttvar = -1;
733 hctx->ccid2hctx_rpdupack = -1;
734 hctx->ccid2hctx_last_cong = jiffies;
735 setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
736 (unsigned long)sk);
737
738 ccid2_hc_tx_check_sanity(hctx);
739 return 0;
740 }
741
742 static void ccid2_hc_tx_exit(struct sock *sk)
743 {
744 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
745 int i;
746
747 ccid2_hc_tx_kill_rto_timer(sk);
748
749 for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
750 kfree(hctx->ccid2hctx_seqbuf[i]);
751 hctx->ccid2hctx_seqbufc = 0;
752 }
753
754 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
755 {
756 const struct dccp_sock *dp = dccp_sk(sk);
757 struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
758
759 switch (DCCP_SKB_CB(skb)->dccpd_type) {
760 case DCCP_PKT_DATA:
761 case DCCP_PKT_DATAACK:
762 hcrx->ccid2hcrx_data++;
763 if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
764 dccp_send_ack(sk);
765 hcrx->ccid2hcrx_data = 0;
766 }
767 break;
768 }
769 }
770
771 static struct ccid_operations ccid2 = {
772 .ccid_id = DCCPC_CCID2,
773 .ccid_name = "TCP-like",
774 .ccid_owner = THIS_MODULE,
775 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
776 .ccid_hc_tx_init = ccid2_hc_tx_init,
777 .ccid_hc_tx_exit = ccid2_hc_tx_exit,
778 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
779 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
780 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
781 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
782 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
783 };
784
785 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
786 module_param(ccid2_debug, bool, 0444);
787 MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
788 #endif
789
790 static __init int ccid2_module_init(void)
791 {
792 return ccid_register(&ccid2);
793 }
794 module_init(ccid2_module_init);
795
796 static __exit void ccid2_module_exit(void)
797 {
798 ccid_unregister(&ccid2);
799 }
800 module_exit(ccid2_module_exit);
801
802 MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
803 MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
804 MODULE_LICENSE("GPL");
805 MODULE_ALIAS("net-dccp-ccid-2");
Linux with added FPC-III support