2 * net/dccp/ccids/ccid2.c
4 * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
6 * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
8 * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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.
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.
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.
26 * This implementation should follow RFC 4341
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)
38 static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
42 struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
44 /* there is data in the chain */
45 if (seqp != hctx->ccid2hctx_seqt) {
46 seqp = seqp->ccid2s_prev;
48 if (!seqp->ccid2s_acked)
51 while (seqp != hctx->ccid2hctx_seqt) {
52 struct ccid2_seq *prev = seqp->ccid2s_prev;
55 if (!prev->ccid2s_acked)
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,
68 BUG_ON(pipe != hctx->ccid2hctx_pipe);
69 ccid2_pr_debug("len of chain=%d\n", len);
72 seqp = seqp->ccid2s_prev;
74 } while (seqp != hctx->ccid2hctx_seqh);
76 ccid2_pr_debug("total len=%d\n", len);
77 BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
80 #define ccid2_pr_debug(format, a...)
81 #define ccid2_hc_tx_check_sanity(hctx)
84 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
86 struct ccid2_seq *seqp;
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*)))
94 /* allocate buffer and initialize linked list */
95 seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any());
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];
103 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
104 seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
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;
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;
114 hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
115 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
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++;
125 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
127 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
129 ccid2_pr_debug("pipe=%d cwnd=%d\n", hctx->ccid2hctx_pipe,
130 hctx->ccid2hctx_cwnd);
132 if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd) {
133 /* OK we can send... make sure previous packet was sent off */
134 if (!hctx->ccid2hctx_sendwait) {
135 hctx->ccid2hctx_sendwait = 1;
140 return 1; /* XXX CCID should dequeue when ready instead of polling */
143 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
145 struct dccp_sock *dp = dccp_sk(sk);
146 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
149 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
150 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
151 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
152 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
154 if (val == 0 || val > max_ratio) {
155 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
158 if (val > 0xFFFF) /* RFC 4340, 11.3 */
161 if (val == dp->dccps_l_ack_ratio)
164 ccid2_pr_debug("changing local ack ratio to %u\n", val);
165 dp->dccps_l_ack_ratio = val;
168 static void ccid2_change_cwnd(struct ccid2_hc_tx_sock *hctx, u32 val)
170 hctx->ccid2hctx_cwnd = val? : 1;
171 ccid2_pr_debug("changed cwnd to %u\n", hctx->ccid2hctx_cwnd);
174 static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
176 ccid2_pr_debug("change SRTT to %ld\n", val);
177 hctx->ccid2hctx_srtt = val;
180 static void ccid2_change_pipe(struct ccid2_hc_tx_sock *hctx, long val)
182 hctx->ccid2hctx_pipe = val;
185 static void ccid2_start_rto_timer(struct sock *sk);
187 static void ccid2_hc_tx_rto_expire(unsigned long data)
189 struct sock *sk = (struct sock *)data;
190 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
194 if (sock_owned_by_user(sk)) {
195 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
200 ccid2_pr_debug("RTO_EXPIRE\n");
202 ccid2_hc_tx_check_sanity(hctx);
205 hctx->ccid2hctx_rto <<= 1;
207 s = hctx->ccid2hctx_rto / HZ;
209 hctx->ccid2hctx_rto = 60 * HZ;
211 ccid2_start_rto_timer(sk);
213 /* adjust pipe, cwnd etc */
214 ccid2_change_pipe(hctx, 0);
215 hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd >> 1;
216 if (hctx->ccid2hctx_ssthresh < 2)
217 hctx->ccid2hctx_ssthresh = 2;
218 ccid2_change_cwnd(hctx, 1);
220 /* clear state about stuff we sent */
221 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
222 hctx->ccid2hctx_ssacks = 0;
223 hctx->ccid2hctx_acks = 0;
225 /* clear ack ratio state. */
226 hctx->ccid2hctx_rpseq = 0;
227 hctx->ccid2hctx_rpdupack = -1;
228 ccid2_change_l_ack_ratio(sk, 1);
229 ccid2_hc_tx_check_sanity(hctx);
235 static void ccid2_start_rto_timer(struct sock *sk)
237 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
239 ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
241 BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
242 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
243 jiffies + hctx->ccid2hctx_rto);
246 static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
248 struct dccp_sock *dp = dccp_sk(sk);
249 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
250 struct ccid2_seq *next;
253 ccid2_hc_tx_check_sanity(hctx);
255 BUG_ON(!hctx->ccid2hctx_sendwait);
256 hctx->ccid2hctx_sendwait = 0;
257 ccid2_change_pipe(hctx, hctx->ccid2hctx_pipe + 1);
258 BUG_ON(hctx->ccid2hctx_pipe < 0);
260 /* There is an issue. What if another packet is sent between
261 * packet_send() and packet_sent(). Then the sequence number would be
267 hctx->ccid2hctx_seqh->ccid2s_seq = seq;
268 hctx->ccid2hctx_seqh->ccid2s_acked = 0;
269 hctx->ccid2hctx_seqh->ccid2s_sent = jiffies;
271 next = hctx->ccid2hctx_seqh->ccid2s_next;
272 /* check if we need to alloc more space */
273 if (next == hctx->ccid2hctx_seqt) {
274 if (ccid2_hc_tx_alloc_seq(hctx)) {
275 DCCP_CRIT("packet history - out of memory!");
276 /* FIXME: find a more graceful way to bail out */
279 next = hctx->ccid2hctx_seqh->ccid2s_next;
280 BUG_ON(next == hctx->ccid2hctx_seqt);
282 hctx->ccid2hctx_seqh = next;
284 ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
285 hctx->ccid2hctx_pipe);
288 * FIXME: The code below is broken and the variables have been removed
289 * from the socket struct. The `ackloss' variable was always set to 0,
290 * and with arsent there are several problems:
291 * (i) it doesn't just count the number of Acks, but all sent packets;
292 * (ii) it is expressed in # of packets, not # of windows, so the
293 * comparison below uses the wrong formula: Appendix A of RFC 4341
294 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
295 * of data with no lost or marked Ack packets. If arsent were the # of
296 * consecutive Acks received without loss, then Ack Ratio needs to be
297 * decreased by 1 when
298 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
299 * where cwnd / R is the number of Acks received per window of data
300 * (cf. RFC 4341, App. A). The problems are that
301 * - arsent counts other packets as well;
302 * - the comparison uses a formula different from RFC 4341;
303 * - computing a cubic/quadratic equation each time is too complicated.
304 * Hence a different algorithm is needed.
307 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
308 hctx->ccid2hctx_arsent++;
309 /* We had an ack loss in this window... */
310 if (hctx->ccid2hctx_ackloss) {
311 if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
312 hctx->ccid2hctx_arsent = 0;
313 hctx->ccid2hctx_ackloss = 0;
316 /* No acks lost up to now... */
317 /* decrease ack ratio if enough packets were sent */
318 if (dp->dccps_l_ack_ratio > 1) {
319 /* XXX don't calculate denominator each time */
320 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
321 dp->dccps_l_ack_ratio;
323 denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
325 if (hctx->ccid2hctx_arsent >= denom) {
326 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
327 hctx->ccid2hctx_arsent = 0;
330 /* we can't increase ack ratio further [1] */
331 hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
336 /* setup RTO timer */
337 if (!timer_pending(&hctx->ccid2hctx_rtotimer))
338 ccid2_start_rto_timer(sk);
340 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
341 ccid2_pr_debug("pipe=%d\n", hctx->ccid2hctx_pipe);
342 ccid2_pr_debug("Sent: seq=%llu\n", (unsigned long long)seq);
344 struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
346 while (seqp != hctx->ccid2hctx_seqh) {
347 ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
348 (unsigned long long)seqp->ccid2s_seq,
349 seqp->ccid2s_acked, seqp->ccid2s_sent);
350 seqp = seqp->ccid2s_next;
353 ccid2_pr_debug("=========\n");
354 ccid2_hc_tx_check_sanity(hctx);
358 /* XXX Lame code duplication!
359 * returns -1 if none was found.
360 * else returns the next offset to use in the function call.
362 static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
363 unsigned char **vec, unsigned char *veclen)
365 const struct dccp_hdr *dh = dccp_hdr(skb);
366 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
367 unsigned char *opt_ptr;
368 const unsigned char *opt_end = (unsigned char *)dh +
369 (dh->dccph_doff * 4);
370 unsigned char opt, len;
371 unsigned char *value;
376 if (opt_ptr >= opt_end)
379 while (opt_ptr != opt_end) {
384 /* Check if this isn't a single byte option */
385 if (opt > DCCPO_MAX_RESERVED) {
386 if (opt_ptr == opt_end)
387 goto out_invalid_option;
391 goto out_invalid_option;
393 * Remove the type and len fields, leaving
394 * just the value size
400 if (opt_ptr > opt_end)
401 goto out_invalid_option;
405 case DCCPO_ACK_VECTOR_0:
406 case DCCPO_ACK_VECTOR_1:
409 return offset + (opt_ptr - options);
416 DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
420 static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
422 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
424 sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
425 ccid2_pr_debug("deleted RTO timer\n");
428 static inline void ccid2_new_ack(struct sock *sk,
429 struct ccid2_seq *seqp,
430 unsigned int *maxincr)
432 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
435 if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
436 hctx->ccid2hctx_acks = 0;
438 /* We can increase cwnd at most maxincr [ack_ratio/2] */
440 /* increase every 2 acks */
441 hctx->ccid2hctx_ssacks++;
442 if (hctx->ccid2hctx_ssacks == 2) {
443 ccid2_change_cwnd(hctx, hctx->ccid2hctx_cwnd+1);
444 hctx->ccid2hctx_ssacks = 0;
445 *maxincr = *maxincr - 1;
448 /* increased cwnd enough for this single ack */
449 hctx->ccid2hctx_ssacks = 0;
452 hctx->ccid2hctx_ssacks = 0;
453 hctx->ccid2hctx_acks++;
455 if (hctx->ccid2hctx_acks >= hctx->ccid2hctx_cwnd) {
456 ccid2_change_cwnd(hctx, hctx->ccid2hctx_cwnd + 1);
457 hctx->ccid2hctx_acks = 0;
462 if (hctx->ccid2hctx_srtt == -1 ||
463 time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
464 unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
467 /* first measurement */
468 if (hctx->ccid2hctx_srtt == -1) {
469 ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
471 (unsigned long long)seqp->ccid2s_seq);
472 ccid2_change_srtt(hctx, r);
473 hctx->ccid2hctx_rttvar = r >> 1;
476 long tmp = hctx->ccid2hctx_srtt - r;
483 hctx->ccid2hctx_rttvar *= 3;
484 hctx->ccid2hctx_rttvar >>= 2;
485 hctx->ccid2hctx_rttvar += tmp;
488 srtt = hctx->ccid2hctx_srtt;
493 ccid2_change_srtt(hctx, srtt);
495 s = hctx->ccid2hctx_rttvar << 2;
496 /* clock granularity is 1 when based on jiffies */
499 hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
501 /* must be at least a second */
502 s = hctx->ccid2hctx_rto / HZ;
503 /* DCCP doesn't require this [but I like it cuz my code sux] */
506 hctx->ccid2hctx_rto = HZ;
510 hctx->ccid2hctx_rto = HZ * 60;
512 hctx->ccid2hctx_lastrtt = jiffies;
514 ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
515 hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
516 hctx->ccid2hctx_rto, HZ, r);
519 /* we got a new ack, so re-start RTO timer */
520 ccid2_hc_tx_kill_rto_timer(sk);
521 ccid2_start_rto_timer(sk);
524 static void ccid2_hc_tx_dec_pipe(struct sock *sk)
526 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
528 ccid2_change_pipe(hctx, hctx->ccid2hctx_pipe-1);
529 BUG_ON(hctx->ccid2hctx_pipe < 0);
531 if (hctx->ccid2hctx_pipe == 0)
532 ccid2_hc_tx_kill_rto_timer(sk);
535 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
537 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
539 if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
540 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
544 hctx->ccid2hctx_last_cong = jiffies;
546 ccid2_change_cwnd(hctx, hctx->ccid2hctx_cwnd >> 1);
547 hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd;
548 if (hctx->ccid2hctx_ssthresh < 2)
549 hctx->ccid2hctx_ssthresh = 2;
551 /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
552 if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
553 ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
556 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
558 struct dccp_sock *dp = dccp_sk(sk);
559 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
561 struct ccid2_seq *seqp;
562 unsigned char *vector;
563 unsigned char veclen;
566 unsigned int maxincr = 0;
568 ccid2_hc_tx_check_sanity(hctx);
569 /* check reverse path congestion */
570 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
572 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
573 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
576 /* need to bootstrap */
577 if (hctx->ccid2hctx_rpdupack == -1) {
578 hctx->ccid2hctx_rpdupack = 0;
579 hctx->ccid2hctx_rpseq = seqno;
581 /* check if packet is consecutive */
582 if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
583 hctx->ccid2hctx_rpseq = seqno;
584 /* it's a later packet */
585 else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
586 hctx->ccid2hctx_rpdupack++;
588 /* check if we got enough dupacks */
589 if (hctx->ccid2hctx_rpdupack >=
590 hctx->ccid2hctx_numdupack) {
591 hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
592 hctx->ccid2hctx_rpseq = 0;
594 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
599 /* check forward path congestion */
600 /* still didn't send out new data packets */
601 if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
604 switch (DCCP_SKB_CB(skb)->dccpd_type) {
606 case DCCP_PKT_DATAACK:
612 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
613 if (after48(ackno, hctx->ccid2hctx_high_ack))
614 hctx->ccid2hctx_high_ack = ackno;
616 seqp = hctx->ccid2hctx_seqt;
617 while (before48(seqp->ccid2s_seq, ackno)) {
618 seqp = seqp->ccid2s_next;
619 if (seqp == hctx->ccid2hctx_seqh) {
620 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
625 /* If in slow-start, cwnd can increase at most Ack Ratio / 2 packets for
626 * this single ack. I round up.
629 maxincr = dp->dccps_l_ack_ratio >> 1;
632 /* go through all ack vectors */
633 while ((offset = ccid2_ackvector(sk, skb, offset,
634 &vector, &veclen)) != -1) {
635 /* go through this ack vector */
637 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
638 u64 ackno_end_rl = SUB48(ackno, rl);
640 ccid2_pr_debug("ackvec start:%llu end:%llu\n",
641 (unsigned long long)ackno,
642 (unsigned long long)ackno_end_rl);
643 /* if the seqno we are analyzing is larger than the
644 * current ackno, then move towards the tail of our
647 while (after48(seqp->ccid2s_seq, ackno)) {
648 if (seqp == hctx->ccid2hctx_seqt) {
652 seqp = seqp->ccid2s_prev;
657 /* check all seqnos in the range of the vector
660 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
661 const u8 state = *vector &
662 DCCP_ACKVEC_STATE_MASK;
664 /* new packet received or marked */
665 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
666 !seqp->ccid2s_acked) {
668 DCCP_ACKVEC_STATE_ECN_MARKED) {
669 ccid2_congestion_event(sk,
672 ccid2_new_ack(sk, seqp,
675 seqp->ccid2s_acked = 1;
676 ccid2_pr_debug("Got ack for %llu\n",
677 (unsigned long long)seqp->ccid2s_seq);
678 ccid2_hc_tx_dec_pipe(sk);
680 if (seqp == hctx->ccid2hctx_seqt) {
684 seqp = seqp->ccid2s_prev;
689 ackno = SUB48(ackno_end_rl, 1);
696 /* The state about what is acked should be correct now
697 * Check for NUMDUPACK
699 seqp = hctx->ccid2hctx_seqt;
700 while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
701 seqp = seqp->ccid2s_next;
702 if (seqp == hctx->ccid2hctx_seqh) {
703 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
709 if (seqp->ccid2s_acked) {
711 if (done == hctx->ccid2hctx_numdupack)
714 if (seqp == hctx->ccid2hctx_seqt)
716 seqp = seqp->ccid2s_prev;
719 /* If there are at least 3 acknowledgements, anything unacknowledged
720 * below the last sequence number is considered lost
722 if (done == hctx->ccid2hctx_numdupack) {
723 struct ccid2_seq *last_acked = seqp;
725 /* check for lost packets */
727 if (!seqp->ccid2s_acked) {
728 ccid2_pr_debug("Packet lost: %llu\n",
729 (unsigned long long)seqp->ccid2s_seq);
730 /* XXX need to traverse from tail -> head in
731 * order to detect multiple congestion events in
734 ccid2_congestion_event(sk, seqp);
735 ccid2_hc_tx_dec_pipe(sk);
737 if (seqp == hctx->ccid2hctx_seqt)
739 seqp = seqp->ccid2s_prev;
742 hctx->ccid2hctx_seqt = last_acked;
745 /* trim acked packets in tail */
746 while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
747 if (!hctx->ccid2hctx_seqt->ccid2s_acked)
750 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
753 ccid2_hc_tx_check_sanity(hctx);
756 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
758 struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
759 struct dccp_sock *dp = dccp_sk(sk);
762 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
763 hctx->ccid2hctx_ssthresh = ~0;
764 hctx->ccid2hctx_numdupack = 3;
767 * RFC 4341, 5: "The cwnd parameter is initialized to at most four
768 * packets for new connections, following the rules from [RFC3390]".
769 * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
771 hctx->ccid2hctx_cwnd = min(4U, max(2U, 4380U / dp->dccps_mss_cache));
773 /* Make sure that Ack Ratio is enabled and within bounds. */
774 max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
775 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
776 dp->dccps_l_ack_ratio = max_ratio;
778 /* XXX init ~ to window size... */
779 if (ccid2_hc_tx_alloc_seq(hctx))
782 hctx->ccid2hctx_rto = 3 * HZ;
783 ccid2_change_srtt(hctx, -1);
784 hctx->ccid2hctx_rttvar = -1;
785 hctx->ccid2hctx_rpdupack = -1;
786 hctx->ccid2hctx_last_cong = jiffies;
787 setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
790 ccid2_hc_tx_check_sanity(hctx);
794 static void ccid2_hc_tx_exit(struct sock *sk)
796 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
799 ccid2_hc_tx_kill_rto_timer(sk);
801 for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
802 kfree(hctx->ccid2hctx_seqbuf[i]);
803 hctx->ccid2hctx_seqbufc = 0;
806 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
808 const struct dccp_sock *dp = dccp_sk(sk);
809 struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
811 switch (DCCP_SKB_CB(skb)->dccpd_type) {
813 case DCCP_PKT_DATAACK:
814 hcrx->ccid2hcrx_data++;
815 if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
817 hcrx->ccid2hcrx_data = 0;
823 static struct ccid_operations ccid2 = {
824 .ccid_id = DCCPC_CCID2,
825 .ccid_name = "ccid2",
826 .ccid_owner = THIS_MODULE,
827 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
828 .ccid_hc_tx_init = ccid2_hc_tx_init,
829 .ccid_hc_tx_exit = ccid2_hc_tx_exit,
830 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
831 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
832 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
833 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
834 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
837 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
838 module_param(ccid2_debug, bool, 0444);
839 MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
842 static __init int ccid2_module_init(void)
844 return ccid_register(&ccid2);
846 module_init(ccid2_module_init);
848 static __exit void ccid2_module_exit(void)
850 ccid_unregister(&ccid2);
852 module_exit(ccid2_module_exit);
854 MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
855 MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
856 MODULE_LICENSE("GPL");
857 MODULE_ALIAS("net-dccp-ccid-2");