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);
232 s32 delta = now - hc->tx_lsndtime;
234 hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2));
236 /* don't reduce cwnd below the initial window (IW) */
237 restart_cwnd = min(cwnd, iwnd);
239 while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd)
241 hc->tx_cwnd = max(cwnd, restart_cwnd);
242 hc->tx_cwnd_stamp = now;
243 hc->tx_cwnd_used = 0;
245 ccid2_check_l_ack_ratio(sk);
248 static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
250 struct dccp_sock *dp = dccp_sk(sk);
251 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
252 const u32 now = ccid2_jiffies32;
253 struct ccid2_seq *next;
255 /* slow-start after idle periods (RFC 2581, RFC 2861) */
256 if (ccid2_do_cwv && !hc->tx_pipe &&
257 (s32)(now - hc->tx_lsndtime) >= hc->tx_rto)
258 ccid2_cwnd_restart(sk, now);
260 hc->tx_lsndtime = now;
263 /* see whether cwnd was fully used (RFC 2861), update expected window */
264 if (ccid2_cwnd_network_limited(hc)) {
265 ccid2_update_used_window(hc, hc->tx_cwnd);
266 hc->tx_cwnd_used = 0;
267 hc->tx_cwnd_stamp = now;
269 if (hc->tx_pipe > hc->tx_cwnd_used)
270 hc->tx_cwnd_used = hc->tx_pipe;
272 ccid2_update_used_window(hc, hc->tx_cwnd_used);
274 if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto)
275 ccid2_cwnd_application_limited(sk, now);
278 hc->tx_seqh->ccid2s_seq = dp->dccps_gss;
279 hc->tx_seqh->ccid2s_acked = 0;
280 hc->tx_seqh->ccid2s_sent = now;
282 next = hc->tx_seqh->ccid2s_next;
283 /* check if we need to alloc more space */
284 if (next == hc->tx_seqt) {
285 if (ccid2_hc_tx_alloc_seq(hc)) {
286 DCCP_CRIT("packet history - out of memory!");
287 /* FIXME: find a more graceful way to bail out */
290 next = hc->tx_seqh->ccid2s_next;
291 BUG_ON(next == hc->tx_seqt);
295 ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe);
298 * FIXME: The code below is broken and the variables have been removed
299 * from the socket struct. The `ackloss' variable was always set to 0,
300 * and with arsent there are several problems:
301 * (i) it doesn't just count the number of Acks, but all sent packets;
302 * (ii) it is expressed in # of packets, not # of windows, so the
303 * comparison below uses the wrong formula: Appendix A of RFC 4341
304 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
305 * of data with no lost or marked Ack packets. If arsent were the # of
306 * consecutive Acks received without loss, then Ack Ratio needs to be
307 * decreased by 1 when
308 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
309 * where cwnd / R is the number of Acks received per window of data
310 * (cf. RFC 4341, App. A). The problems are that
311 * - arsent counts other packets as well;
312 * - the comparison uses a formula different from RFC 4341;
313 * - computing a cubic/quadratic equation each time is too complicated.
314 * Hence a different algorithm is needed.
317 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
319 /* We had an ack loss in this window... */
320 if (hc->tx_ackloss) {
321 if (hc->tx_arsent >= hc->tx_cwnd) {
326 /* No acks lost up to now... */
327 /* decrease ack ratio if enough packets were sent */
328 if (dp->dccps_l_ack_ratio > 1) {
329 /* XXX don't calculate denominator each time */
330 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
331 dp->dccps_l_ack_ratio;
333 denom = hc->tx_cwnd * hc->tx_cwnd / denom;
335 if (hc->tx_arsent >= denom) {
336 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
340 /* we can't increase ack ratio further [1] */
341 hc->tx_arsent = 0; /* or maybe set it to cwnd*/
346 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
348 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
350 struct ccid2_seq *seqp = hc->tx_seqt;
352 while (seqp != hc->tx_seqh) {
353 ccid2_pr_debug("out seq=%llu acked=%d time=%u\n",
354 (unsigned long long)seqp->ccid2s_seq,
355 seqp->ccid2s_acked, seqp->ccid2s_sent);
356 seqp = seqp->ccid2s_next;
359 ccid2_pr_debug("=========\n");
364 * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm
365 * This code is almost identical with TCP's tcp_rtt_estimator(), since
366 * - it has a higher sampling frequency (recommended by RFC 1323),
367 * - the RTO does not collapse into RTT due to RTTVAR going towards zero,
368 * - it is simple (cf. more complex proposals such as Eifel timer or research
369 * which suggests that the gain should be set according to window size),
370 * - in tests it was found to work well with CCID2 [gerrit].
372 static void ccid2_rtt_estimator(struct sock *sk, const long mrtt)
374 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
377 if (hc->tx_srtt == 0) {
378 /* First measurement m */
379 hc->tx_srtt = m << 3;
380 hc->tx_mdev = m << 1;
382 hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk));
383 hc->tx_rttvar = hc->tx_mdev_max;
385 hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss;
387 /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */
388 m -= (hc->tx_srtt >> 3);
391 /* Similarly, update scaled mdev with regard to |m| */
394 m -= (hc->tx_mdev >> 2);
396 * This neutralises RTO increase when RTT < SRTT - mdev
397 * (see P. Sarolahti, A. Kuznetsov,"Congestion Control
398 * in Linux TCP", USENIX 2002, pp. 49-62).
403 m -= (hc->tx_mdev >> 2);
407 if (hc->tx_mdev > hc->tx_mdev_max) {
408 hc->tx_mdev_max = hc->tx_mdev;
409 if (hc->tx_mdev_max > hc->tx_rttvar)
410 hc->tx_rttvar = hc->tx_mdev_max;
414 * Decay RTTVAR at most once per flight, exploiting that
415 * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2)
416 * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1)
417 * GAR is a useful bound for FlightSize = pipe.
418 * AWL is probably too low here, as it over-estimates pipe.
420 if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) {
421 if (hc->tx_mdev_max < hc->tx_rttvar)
422 hc->tx_rttvar -= (hc->tx_rttvar -
423 hc->tx_mdev_max) >> 2;
424 hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss;
425 hc->tx_mdev_max = tcp_rto_min(sk);
430 * Set RTO from SRTT and RTTVAR
431 * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms.
432 * This agrees with RFC 4341, 5:
433 * "Because DCCP does not retransmit data, DCCP does not require
434 * TCP's recommended minimum timeout of one second".
436 hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar;
438 if (hc->tx_rto > DCCP_RTO_MAX)
439 hc->tx_rto = DCCP_RTO_MAX;
442 static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
443 unsigned int *maxincr)
445 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
446 struct dccp_sock *dp = dccp_sk(sk);
447 int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio;
449 if (hc->tx_cwnd < dp->dccps_l_seq_win &&
450 r_seq_used < dp->dccps_r_seq_win) {
451 if (hc->tx_cwnd < hc->tx_ssthresh) {
452 if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) {
455 hc->tx_packets_acked = 0;
457 } else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
459 hc->tx_packets_acked = 0;
464 * Adjust the local sequence window and the ack ratio to allow about
465 * 5 times the number of packets in the network (RFC 4340 7.5.2)
467 if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win)
468 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2);
469 else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2)
470 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U);
472 if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win)
473 ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2);
474 else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2)
475 ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2);
478 * FIXME: RTT is sampled several times per acknowledgment (for each
479 * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).
480 * This causes the RTT to be over-estimated, since the older entries
481 * in the Ack Vector have earlier sending times.
482 * The cleanest solution is to not use the ccid2s_sent field at all
483 * and instead use DCCP timestamps: requires changes in other places.
485 ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent);
488 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
490 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
492 if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) {
493 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
497 hc->tx_last_cong = ccid2_jiffies32;
499 hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U;
500 hc->tx_ssthresh = max(hc->tx_cwnd, 2U);
502 ccid2_check_l_ack_ratio(sk);
505 static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
506 u8 option, u8 *optval, u8 optlen)
508 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
511 case DCCPO_ACK_VECTOR_0:
512 case DCCPO_ACK_VECTOR_1:
513 return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen,
514 option - DCCPO_ACK_VECTOR_0);
519 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
521 struct dccp_sock *dp = dccp_sk(sk);
522 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
523 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
524 struct dccp_ackvec_parsed *avp;
526 struct ccid2_seq *seqp;
528 unsigned int maxincr = 0;
530 /* check reverse path congestion */
531 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
533 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
534 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
537 /* need to bootstrap */
538 if (hc->tx_rpdupack == -1) {
540 hc->tx_rpseq = seqno;
542 /* check if packet is consecutive */
543 if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1)
544 hc->tx_rpseq = seqno;
545 /* it's a later packet */
546 else if (after48(seqno, hc->tx_rpseq)) {
549 /* check if we got enough dupacks */
550 if (hc->tx_rpdupack >= NUMDUPACK) {
551 hc->tx_rpdupack = -1; /* XXX lame */
553 #ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__
555 * FIXME: Ack Congestion Control is broken; in
556 * the current state instabilities occurred with
557 * Ack Ratios greater than 1; causing hang-ups
558 * and long RTO timeouts. This needs to be fixed
559 * before opening up dynamic changes. -- gerrit
561 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
567 /* check forward path congestion */
568 if (dccp_packet_without_ack(skb))
571 /* still didn't send out new data packets */
572 if (hc->tx_seqh == hc->tx_seqt)
575 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
576 if (after48(ackno, hc->tx_high_ack))
577 hc->tx_high_ack = ackno;
580 while (before48(seqp->ccid2s_seq, ackno)) {
581 seqp = seqp->ccid2s_next;
582 if (seqp == hc->tx_seqh) {
583 seqp = hc->tx_seqh->ccid2s_prev;
589 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
590 * packets per acknowledgement. Rounding up avoids that cwnd is not
591 * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
593 if (hc->tx_cwnd < hc->tx_ssthresh)
594 maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
596 /* go through all ack vectors */
597 list_for_each_entry(avp, &hc->tx_av_chunks, node) {
598 /* go through this ack vector */
599 for (; avp->len--; avp->vec++) {
600 u64 ackno_end_rl = SUB48(ackno,
601 dccp_ackvec_runlen(avp->vec));
603 ccid2_pr_debug("ackvec %llu |%u,%u|\n",
604 (unsigned long long)ackno,
605 dccp_ackvec_state(avp->vec) >> 6,
606 dccp_ackvec_runlen(avp->vec));
607 /* if the seqno we are analyzing is larger than the
608 * current ackno, then move towards the tail of our
611 while (after48(seqp->ccid2s_seq, ackno)) {
612 if (seqp == hc->tx_seqt) {
616 seqp = seqp->ccid2s_prev;
621 /* check all seqnos in the range of the vector
624 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
625 const u8 state = dccp_ackvec_state(avp->vec);
627 /* new packet received or marked */
628 if (state != DCCPAV_NOT_RECEIVED &&
629 !seqp->ccid2s_acked) {
630 if (state == DCCPAV_ECN_MARKED)
631 ccid2_congestion_event(sk,
634 ccid2_new_ack(sk, seqp,
637 seqp->ccid2s_acked = 1;
638 ccid2_pr_debug("Got ack for %llu\n",
639 (unsigned long long)seqp->ccid2s_seq);
642 if (seqp == hc->tx_seqt) {
646 seqp = seqp->ccid2s_prev;
651 ackno = SUB48(ackno_end_rl, 1);
657 /* The state about what is acked should be correct now
658 * Check for NUMDUPACK
661 while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) {
662 seqp = seqp->ccid2s_next;
663 if (seqp == hc->tx_seqh) {
664 seqp = hc->tx_seqh->ccid2s_prev;
670 if (seqp->ccid2s_acked) {
672 if (done == NUMDUPACK)
675 if (seqp == hc->tx_seqt)
677 seqp = seqp->ccid2s_prev;
680 /* If there are at least 3 acknowledgements, anything unacknowledged
681 * below the last sequence number is considered lost
683 if (done == NUMDUPACK) {
684 struct ccid2_seq *last_acked = seqp;
686 /* check for lost packets */
688 if (!seqp->ccid2s_acked) {
689 ccid2_pr_debug("Packet lost: %llu\n",
690 (unsigned long long)seqp->ccid2s_seq);
691 /* XXX need to traverse from tail -> head in
692 * order to detect multiple congestion events in
695 ccid2_congestion_event(sk, seqp);
698 if (seqp == hc->tx_seqt)
700 seqp = seqp->ccid2s_prev;
703 hc->tx_seqt = last_acked;
706 /* trim acked packets in tail */
707 while (hc->tx_seqt != hc->tx_seqh) {
708 if (!hc->tx_seqt->ccid2s_acked)
711 hc->tx_seqt = hc->tx_seqt->ccid2s_next;
714 /* restart RTO timer if not all outstanding data has been acked */
715 if (hc->tx_pipe == 0)
716 sk_stop_timer(sk, &hc->tx_rtotimer);
718 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
720 /* check if incoming Acks allow pending packets to be sent */
721 if (sender_was_blocked && !ccid2_cwnd_network_limited(hc))
722 dccp_tasklet_schedule(sk);
723 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
726 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
728 struct ccid2_hc_tx_sock *hc = ccid_priv(ccid);
729 struct dccp_sock *dp = dccp_sk(sk);
732 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
733 hc->tx_ssthresh = ~0U;
735 /* Use larger initial windows (RFC 4341, section 5). */
736 hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache);
737 hc->tx_expected_wnd = hc->tx_cwnd;
739 /* Make sure that Ack Ratio is enabled and within bounds. */
740 max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2);
741 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
742 dp->dccps_l_ack_ratio = max_ratio;
744 /* XXX init ~ to window size... */
745 if (ccid2_hc_tx_alloc_seq(hc))
748 hc->tx_rto = DCCP_TIMEOUT_INIT;
749 hc->tx_rpdupack = -1;
750 hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32;
751 hc->tx_cwnd_used = 0;
753 timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0);
754 INIT_LIST_HEAD(&hc->tx_av_chunks);
758 static void ccid2_hc_tx_exit(struct sock *sk)
760 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
763 sk_stop_timer(sk, &hc->tx_rtotimer);
765 for (i = 0; i < hc->tx_seqbufc; i++)
766 kfree(hc->tx_seqbuf[i]);
768 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
771 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
773 struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk);
775 if (!dccp_data_packet(skb))
778 if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) {
780 hc->rx_num_data_pkts = 0;
784 struct ccid_operations ccid2_ops = {
785 .ccid_id = DCCPC_CCID2,
786 .ccid_name = "TCP-like",
787 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
788 .ccid_hc_tx_init = ccid2_hc_tx_init,
789 .ccid_hc_tx_exit = ccid2_hc_tx_exit,
790 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
791 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
792 .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options,
793 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
794 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
795 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
798 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
799 module_param(ccid2_debug, bool, 0644);
800 MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages");