2 * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
4 * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
6 * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 * This implementation should follow RFC 4341
26 #include <linux/slab.h>
31 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
32 static bool ccid2_debug;
33 #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
35 #define ccid2_pr_debug(format, a...)
38 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc)
40 struct ccid2_seq *seqp;
43 /* check if we have space to preserve the pointer to the buffer */
44 if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) /
45 sizeof(struct ccid2_seq *)))
48 /* allocate buffer and initialize linked list */
49 seqp = kmalloc_array(CCID2_SEQBUF_LEN, sizeof(struct ccid2_seq),
54 for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
55 seqp[i].ccid2s_next = &seqp[i + 1];
56 seqp[i + 1].ccid2s_prev = &seqp[i];
58 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
59 seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
61 /* This is the first allocation. Initiate the head and tail. */
62 if (hc->tx_seqbufc == 0)
63 hc->tx_seqh = hc->tx_seqt = seqp;
65 /* link the existing list with the one we just created */
66 hc->tx_seqh->ccid2s_next = seqp;
67 seqp->ccid2s_prev = hc->tx_seqh;
69 hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
70 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt;
73 /* store the original pointer to the buffer so we can free it */
74 hc->tx_seqbuf[hc->tx_seqbufc] = seqp;
80 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
82 if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk)))
83 return CCID_PACKET_WILL_DEQUEUE_LATER;
84 return CCID_PACKET_SEND_AT_ONCE;
87 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
89 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2);
92 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
93 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
94 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
95 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
97 if (val == 0 || val > max_ratio) {
98 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
101 dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO,
102 min_t(u32, val, DCCPF_ACK_RATIO_MAX));
105 static void ccid2_check_l_ack_ratio(struct sock *sk)
107 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
110 * After a loss, idle period, application limited period, or RTO we
111 * need to check that the ack ratio is still less than the congestion
112 * window. Otherwise, we will send an entire congestion window of
113 * packets and got no response because we haven't sent ack ratio
115 * If the ack ratio does need to be reduced, we reduce it to half of
116 * the congestion window (or 1 if that's zero) instead of to the
117 * congestion window. This prevents problems if one ack is lost.
119 if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd)
120 ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U);
123 static void ccid2_change_l_seq_window(struct sock *sk, u64 val)
125 dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW,
126 clamp_val(val, DCCPF_SEQ_WMIN,
130 static void dccp_tasklet_schedule(struct sock *sk)
132 struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet;
134 if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
136 __tasklet_schedule(t);
140 static void ccid2_hc_tx_rto_expire(struct timer_list *t)
142 struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer);
143 struct sock *sk = hc->sk;
144 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
147 if (sock_owned_by_user(sk)) {
148 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5);
152 ccid2_pr_debug("RTO_EXPIRE\n");
154 if (sk->sk_state == DCCP_CLOSED)
159 if (hc->tx_rto > DCCP_RTO_MAX)
160 hc->tx_rto = DCCP_RTO_MAX;
162 /* adjust pipe, cwnd etc */
163 hc->tx_ssthresh = hc->tx_cwnd / 2;
164 if (hc->tx_ssthresh < 2)
169 /* clear state about stuff we sent */
170 hc->tx_seqt = hc->tx_seqh;
171 hc->tx_packets_acked = 0;
173 /* clear ack ratio state. */
175 hc->tx_rpdupack = -1;
176 ccid2_change_l_ack_ratio(sk, 1);
178 /* if we were blocked before, we may now send cwnd=1 packet */
179 if (sender_was_blocked)
180 dccp_tasklet_schedule(sk);
181 /* restart backed-off timer */
182 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
189 * Congestion window validation (RFC 2861).
191 static bool ccid2_do_cwv = true;
192 module_param(ccid2_do_cwv, bool, 0644);
193 MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation");
196 * ccid2_update_used_window - Track how much of cwnd is actually used
197 * This is done in addition to CWV. The sender needs to have an idea of how many
198 * packets may be in flight, to set the local Sequence Window value accordingly
199 * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the
200 * maximum-used window. We use an EWMA low-pass filter to filter out noise.
202 static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd)
204 hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4;
207 /* This borrows the code of tcp_cwnd_application_limited() */
208 static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now)
210 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
211 /* don't reduce cwnd below the initial window (IW) */
212 u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache),
213 win_used = max(hc->tx_cwnd_used, init_win);
215 if (win_used < hc->tx_cwnd) {
216 hc->tx_ssthresh = max(hc->tx_ssthresh,
217 (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2));
218 hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1;
220 hc->tx_cwnd_used = 0;
221 hc->tx_cwnd_stamp = now;
223 ccid2_check_l_ack_ratio(sk);
226 /* This borrows the code of tcp_cwnd_restart() */
227 static void ccid2_cwnd_restart(struct sock *sk, const u32 now)
229 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
230 u32 cwnd = hc->tx_cwnd, restart_cwnd,
231 iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache);
233 hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2));
235 /* don't reduce cwnd below the initial window (IW) */
236 restart_cwnd = min(cwnd, iwnd);
237 cwnd >>= (now - hc->tx_lsndtime) / hc->tx_rto;
238 hc->tx_cwnd = max(cwnd, restart_cwnd);
240 hc->tx_cwnd_stamp = now;
241 hc->tx_cwnd_used = 0;
243 ccid2_check_l_ack_ratio(sk);
246 static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
248 struct dccp_sock *dp = dccp_sk(sk);
249 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
250 const u32 now = ccid2_jiffies32;
251 struct ccid2_seq *next;
253 /* slow-start after idle periods (RFC 2581, RFC 2861) */
254 if (ccid2_do_cwv && !hc->tx_pipe &&
255 (s32)(now - hc->tx_lsndtime) >= hc->tx_rto)
256 ccid2_cwnd_restart(sk, now);
258 hc->tx_lsndtime = now;
261 /* see whether cwnd was fully used (RFC 2861), update expected window */
262 if (ccid2_cwnd_network_limited(hc)) {
263 ccid2_update_used_window(hc, hc->tx_cwnd);
264 hc->tx_cwnd_used = 0;
265 hc->tx_cwnd_stamp = now;
267 if (hc->tx_pipe > hc->tx_cwnd_used)
268 hc->tx_cwnd_used = hc->tx_pipe;
270 ccid2_update_used_window(hc, hc->tx_cwnd_used);
272 if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto)
273 ccid2_cwnd_application_limited(sk, now);
276 hc->tx_seqh->ccid2s_seq = dp->dccps_gss;
277 hc->tx_seqh->ccid2s_acked = 0;
278 hc->tx_seqh->ccid2s_sent = now;
280 next = hc->tx_seqh->ccid2s_next;
281 /* check if we need to alloc more space */
282 if (next == hc->tx_seqt) {
283 if (ccid2_hc_tx_alloc_seq(hc)) {
284 DCCP_CRIT("packet history - out of memory!");
285 /* FIXME: find a more graceful way to bail out */
288 next = hc->tx_seqh->ccid2s_next;
289 BUG_ON(next == hc->tx_seqt);
293 ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe);
296 * FIXME: The code below is broken and the variables have been removed
297 * from the socket struct. The `ackloss' variable was always set to 0,
298 * and with arsent there are several problems:
299 * (i) it doesn't just count the number of Acks, but all sent packets;
300 * (ii) it is expressed in # of packets, not # of windows, so the
301 * comparison below uses the wrong formula: Appendix A of RFC 4341
302 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
303 * of data with no lost or marked Ack packets. If arsent were the # of
304 * consecutive Acks received without loss, then Ack Ratio needs to be
305 * decreased by 1 when
306 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
307 * where cwnd / R is the number of Acks received per window of data
308 * (cf. RFC 4341, App. A). The problems are that
309 * - arsent counts other packets as well;
310 * - the comparison uses a formula different from RFC 4341;
311 * - computing a cubic/quadratic equation each time is too complicated.
312 * Hence a different algorithm is needed.
315 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
317 /* We had an ack loss in this window... */
318 if (hc->tx_ackloss) {
319 if (hc->tx_arsent >= hc->tx_cwnd) {
324 /* No acks lost up to now... */
325 /* decrease ack ratio if enough packets were sent */
326 if (dp->dccps_l_ack_ratio > 1) {
327 /* XXX don't calculate denominator each time */
328 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
329 dp->dccps_l_ack_ratio;
331 denom = hc->tx_cwnd * hc->tx_cwnd / denom;
333 if (hc->tx_arsent >= denom) {
334 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
338 /* we can't increase ack ratio further [1] */
339 hc->tx_arsent = 0; /* or maybe set it to cwnd*/
344 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
346 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
348 struct ccid2_seq *seqp = hc->tx_seqt;
350 while (seqp != hc->tx_seqh) {
351 ccid2_pr_debug("out seq=%llu acked=%d time=%u\n",
352 (unsigned long long)seqp->ccid2s_seq,
353 seqp->ccid2s_acked, seqp->ccid2s_sent);
354 seqp = seqp->ccid2s_next;
357 ccid2_pr_debug("=========\n");
362 * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm
363 * This code is almost identical with TCP's tcp_rtt_estimator(), since
364 * - it has a higher sampling frequency (recommended by RFC 1323),
365 * - the RTO does not collapse into RTT due to RTTVAR going towards zero,
366 * - it is simple (cf. more complex proposals such as Eifel timer or research
367 * which suggests that the gain should be set according to window size),
368 * - in tests it was found to work well with CCID2 [gerrit].
370 static void ccid2_rtt_estimator(struct sock *sk, const long mrtt)
372 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
375 if (hc->tx_srtt == 0) {
376 /* First measurement m */
377 hc->tx_srtt = m << 3;
378 hc->tx_mdev = m << 1;
380 hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk));
381 hc->tx_rttvar = hc->tx_mdev_max;
383 hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss;
385 /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */
386 m -= (hc->tx_srtt >> 3);
389 /* Similarly, update scaled mdev with regard to |m| */
392 m -= (hc->tx_mdev >> 2);
394 * This neutralises RTO increase when RTT < SRTT - mdev
395 * (see P. Sarolahti, A. Kuznetsov,"Congestion Control
396 * in Linux TCP", USENIX 2002, pp. 49-62).
401 m -= (hc->tx_mdev >> 2);
405 if (hc->tx_mdev > hc->tx_mdev_max) {
406 hc->tx_mdev_max = hc->tx_mdev;
407 if (hc->tx_mdev_max > hc->tx_rttvar)
408 hc->tx_rttvar = hc->tx_mdev_max;
412 * Decay RTTVAR at most once per flight, exploiting that
413 * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2)
414 * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1)
415 * GAR is a useful bound for FlightSize = pipe.
416 * AWL is probably too low here, as it over-estimates pipe.
418 if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) {
419 if (hc->tx_mdev_max < hc->tx_rttvar)
420 hc->tx_rttvar -= (hc->tx_rttvar -
421 hc->tx_mdev_max) >> 2;
422 hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss;
423 hc->tx_mdev_max = tcp_rto_min(sk);
428 * Set RTO from SRTT and RTTVAR
429 * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms.
430 * This agrees with RFC 4341, 5:
431 * "Because DCCP does not retransmit data, DCCP does not require
432 * TCP's recommended minimum timeout of one second".
434 hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar;
436 if (hc->tx_rto > DCCP_RTO_MAX)
437 hc->tx_rto = DCCP_RTO_MAX;
440 static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
441 unsigned int *maxincr)
443 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
444 struct dccp_sock *dp = dccp_sk(sk);
445 int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio;
447 if (hc->tx_cwnd < dp->dccps_l_seq_win &&
448 r_seq_used < dp->dccps_r_seq_win) {
449 if (hc->tx_cwnd < hc->tx_ssthresh) {
450 if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) {
453 hc->tx_packets_acked = 0;
455 } else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
457 hc->tx_packets_acked = 0;
462 * Adjust the local sequence window and the ack ratio to allow about
463 * 5 times the number of packets in the network (RFC 4340 7.5.2)
465 if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win)
466 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2);
467 else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2)
468 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U);
470 if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win)
471 ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2);
472 else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2)
473 ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2);
476 * FIXME: RTT is sampled several times per acknowledgment (for each
477 * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).
478 * This causes the RTT to be over-estimated, since the older entries
479 * in the Ack Vector have earlier sending times.
480 * The cleanest solution is to not use the ccid2s_sent field at all
481 * and instead use DCCP timestamps: requires changes in other places.
483 ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent);
486 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
488 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
490 if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) {
491 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
495 hc->tx_last_cong = ccid2_jiffies32;
497 hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U;
498 hc->tx_ssthresh = max(hc->tx_cwnd, 2U);
500 ccid2_check_l_ack_ratio(sk);
503 static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
504 u8 option, u8 *optval, u8 optlen)
506 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
509 case DCCPO_ACK_VECTOR_0:
510 case DCCPO_ACK_VECTOR_1:
511 return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen,
512 option - DCCPO_ACK_VECTOR_0);
517 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
519 struct dccp_sock *dp = dccp_sk(sk);
520 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
521 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
522 struct dccp_ackvec_parsed *avp;
524 struct ccid2_seq *seqp;
526 unsigned int maxincr = 0;
528 /* check reverse path congestion */
529 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
531 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
532 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
535 /* need to bootstrap */
536 if (hc->tx_rpdupack == -1) {
538 hc->tx_rpseq = seqno;
540 /* check if packet is consecutive */
541 if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1)
542 hc->tx_rpseq = seqno;
543 /* it's a later packet */
544 else if (after48(seqno, hc->tx_rpseq)) {
547 /* check if we got enough dupacks */
548 if (hc->tx_rpdupack >= NUMDUPACK) {
549 hc->tx_rpdupack = -1; /* XXX lame */
551 #ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__
553 * FIXME: Ack Congestion Control is broken; in
554 * the current state instabilities occurred with
555 * Ack Ratios greater than 1; causing hang-ups
556 * and long RTO timeouts. This needs to be fixed
557 * before opening up dynamic changes. -- gerrit
559 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
565 /* check forward path congestion */
566 if (dccp_packet_without_ack(skb))
569 /* still didn't send out new data packets */
570 if (hc->tx_seqh == hc->tx_seqt)
573 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
574 if (after48(ackno, hc->tx_high_ack))
575 hc->tx_high_ack = ackno;
578 while (before48(seqp->ccid2s_seq, ackno)) {
579 seqp = seqp->ccid2s_next;
580 if (seqp == hc->tx_seqh) {
581 seqp = hc->tx_seqh->ccid2s_prev;
587 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
588 * packets per acknowledgement. Rounding up avoids that cwnd is not
589 * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
591 if (hc->tx_cwnd < hc->tx_ssthresh)
592 maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
594 /* go through all ack vectors */
595 list_for_each_entry(avp, &hc->tx_av_chunks, node) {
596 /* go through this ack vector */
597 for (; avp->len--; avp->vec++) {
598 u64 ackno_end_rl = SUB48(ackno,
599 dccp_ackvec_runlen(avp->vec));
601 ccid2_pr_debug("ackvec %llu |%u,%u|\n",
602 (unsigned long long)ackno,
603 dccp_ackvec_state(avp->vec) >> 6,
604 dccp_ackvec_runlen(avp->vec));
605 /* if the seqno we are analyzing is larger than the
606 * current ackno, then move towards the tail of our
609 while (after48(seqp->ccid2s_seq, ackno)) {
610 if (seqp == hc->tx_seqt) {
614 seqp = seqp->ccid2s_prev;
619 /* check all seqnos in the range of the vector
622 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
623 const u8 state = dccp_ackvec_state(avp->vec);
625 /* new packet received or marked */
626 if (state != DCCPAV_NOT_RECEIVED &&
627 !seqp->ccid2s_acked) {
628 if (state == DCCPAV_ECN_MARKED)
629 ccid2_congestion_event(sk,
632 ccid2_new_ack(sk, seqp,
635 seqp->ccid2s_acked = 1;
636 ccid2_pr_debug("Got ack for %llu\n",
637 (unsigned long long)seqp->ccid2s_seq);
640 if (seqp == hc->tx_seqt) {
644 seqp = seqp->ccid2s_prev;
649 ackno = SUB48(ackno_end_rl, 1);
655 /* The state about what is acked should be correct now
656 * Check for NUMDUPACK
659 while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) {
660 seqp = seqp->ccid2s_next;
661 if (seqp == hc->tx_seqh) {
662 seqp = hc->tx_seqh->ccid2s_prev;
668 if (seqp->ccid2s_acked) {
670 if (done == NUMDUPACK)
673 if (seqp == hc->tx_seqt)
675 seqp = seqp->ccid2s_prev;
678 /* If there are at least 3 acknowledgements, anything unacknowledged
679 * below the last sequence number is considered lost
681 if (done == NUMDUPACK) {
682 struct ccid2_seq *last_acked = seqp;
684 /* check for lost packets */
686 if (!seqp->ccid2s_acked) {
687 ccid2_pr_debug("Packet lost: %llu\n",
688 (unsigned long long)seqp->ccid2s_seq);
689 /* XXX need to traverse from tail -> head in
690 * order to detect multiple congestion events in
693 ccid2_congestion_event(sk, seqp);
696 if (seqp == hc->tx_seqt)
698 seqp = seqp->ccid2s_prev;
701 hc->tx_seqt = last_acked;
704 /* trim acked packets in tail */
705 while (hc->tx_seqt != hc->tx_seqh) {
706 if (!hc->tx_seqt->ccid2s_acked)
709 hc->tx_seqt = hc->tx_seqt->ccid2s_next;
712 /* restart RTO timer if not all outstanding data has been acked */
713 if (hc->tx_pipe == 0)
714 sk_stop_timer(sk, &hc->tx_rtotimer);
716 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
718 /* check if incoming Acks allow pending packets to be sent */
719 if (sender_was_blocked && !ccid2_cwnd_network_limited(hc))
720 dccp_tasklet_schedule(sk);
721 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
724 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
726 struct ccid2_hc_tx_sock *hc = ccid_priv(ccid);
727 struct dccp_sock *dp = dccp_sk(sk);
730 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
731 hc->tx_ssthresh = ~0U;
733 /* Use larger initial windows (RFC 4341, section 5). */
734 hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache);
735 hc->tx_expected_wnd = hc->tx_cwnd;
737 /* Make sure that Ack Ratio is enabled and within bounds. */
738 max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2);
739 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
740 dp->dccps_l_ack_ratio = max_ratio;
742 /* XXX init ~ to window size... */
743 if (ccid2_hc_tx_alloc_seq(hc))
746 hc->tx_rto = DCCP_TIMEOUT_INIT;
747 hc->tx_rpdupack = -1;
748 hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32;
749 hc->tx_cwnd_used = 0;
751 timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0);
752 INIT_LIST_HEAD(&hc->tx_av_chunks);
756 static void ccid2_hc_tx_exit(struct sock *sk)
758 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
761 sk_stop_timer(sk, &hc->tx_rtotimer);
763 for (i = 0; i < hc->tx_seqbufc; i++)
764 kfree(hc->tx_seqbuf[i]);
766 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
769 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
771 struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk);
773 if (!dccp_data_packet(skb))
776 if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) {
778 hc->rx_num_data_pkts = 0;
782 struct ccid_operations ccid2_ops = {
783 .ccid_id = DCCPC_CCID2,
784 .ccid_name = "TCP-like",
785 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
786 .ccid_hc_tx_init = ccid2_hc_tx_init,
787 .ccid_hc_tx_exit = ccid2_hc_tx_exit,
788 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
789 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
790 .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options,
791 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
792 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
793 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
796 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
797 module_param(ccid2_debug, bool, 0644);
798 MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages");