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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-09-04 01:30:19 -0400
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2008-09-04 01:45:38 -0400
commite9803c0104564698d3b8e84ccdb0b8b0e65427e2 (patch)
tree2bdc72974473e43d48366b7484615d723a782e05
parentc6f0f2e71f3088a0f05502d6adb0f667b84028c3 (diff)
dccp ccid-2: Simplify dec_pipe and rearming of RTO timer
This removes the dec_pipe function and improves the way the RTO timer is rearmed when a new acknowledgment comes in. Details and justification for removal: -------------------------------------- 1) The BUG_ON in dec_pipe is never triggered: pipe is only decremented for TX history entries between tail and head, for which it had previously been incremented in tx_packet_sent; and it is not decremented twice for the same entry, since it is - either decremented when a corresponding Ack Vector cell in state 0 or 1 was received (and then ccid2s_acked==1), - or it is decremented when ccid2s_acked==0, as part of the loss detection in tx_packet_recv (and hence it can not have been decremented earlier). 2) Restarting the RTO timer happens for every single entry in each Ack Vector parsed by tx_packet_recv (according to RFC 4340, 11.4 this can happen up to 16192 times per Ack Vector). 3) The RTO timer should not be restarted when all outstanding data has been acknowledged. This is currently done similar to (2), in dec_pipe, when pipe has reached 0. The patch onsolidates the code which rearms the RTO timer, combining the segments from new_ack and dec_pipe. As a result, the code becomes clearer (compare with tcp_rearm_rto()). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
-rw-r--r--net/dccp/ccids/ccid2.c27
1 files changed, 8 insertions, 19 deletions
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 3b2548bd73f3..fa074d442065 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -353,23 +353,6 @@ static inline void ccid2_new_ack(struct sock *sk,
353 hctx->srtt, hctx->rttvar, 353 hctx->srtt, hctx->rttvar,
354 hctx->rto, HZ, r); 354 hctx->rto, HZ, r);
355 } 355 }
356
357 /* we got a new ack, so re-start RTO timer */
358 ccid2_hc_tx_kill_rto_timer(sk);
359 ccid2_start_rto_timer(sk);
360}
361
362static void ccid2_hc_tx_dec_pipe(struct sock *sk)
363{
364 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
365
366 if (hctx->pipe == 0)
367 DCCP_BUG("pipe == 0");
368 else
369 hctx->pipe--;
370
371 if (hctx->pipe == 0)
372 ccid2_hc_tx_kill_rto_timer(sk);
373} 356}
374 357
375static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) 358static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
@@ -518,7 +501,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
518 seqp->ccid2s_acked = 1; 501 seqp->ccid2s_acked = 1;
519 ccid2_pr_debug("Got ack for %llu\n", 502 ccid2_pr_debug("Got ack for %llu\n",
520 (unsigned long long)seqp->ccid2s_seq); 503 (unsigned long long)seqp->ccid2s_seq);
521 ccid2_hc_tx_dec_pipe(sk); 504 hctx->pipe--;
522 } 505 }
523 if (seqp == hctx->seqt) { 506 if (seqp == hctx->seqt) {
524 done = 1; 507 done = 1;
@@ -574,7 +557,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
574 * one ack vector. 557 * one ack vector.
575 */ 558 */
576 ccid2_congestion_event(sk, seqp); 559 ccid2_congestion_event(sk, seqp);
577 ccid2_hc_tx_dec_pipe(sk); 560 hctx->pipe--;
578 } 561 }
579 if (seqp == hctx->seqt) 562 if (seqp == hctx->seqt)
580 break; 563 break;
@@ -592,6 +575,12 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
592 hctx->seqt = hctx->seqt->ccid2s_next; 575 hctx->seqt = hctx->seqt->ccid2s_next;
593 } 576 }
594 577
578 /* restart RTO timer if not all outstanding data has been acked */
579 if (hctx->pipe == 0)
580 sk_stop_timer(sk, &hctx->rtotimer);
581 else
582 sk_reset_timer(sk, &hctx->rtotimer,
583 jiffies + hctx->rto);
595done: 584done:
596 /* check if incoming Acks allow pending packets to be sent */ 585 /* check if incoming Acks allow pending packets to be sent */
597 if (sender_was_blocked && !ccid2_cwnd_network_limited(hctx)) 586 if (sender_was_blocked && !ccid2_cwnd_network_limited(hctx))