sctp: Flush the queue only once during fast retransmit.

When fast retransmit is triggered by a sack, we should flush the queue
only once so that only 1 retransmit happens.  Also, since we could
potentially have non-fast-rtx chunks on the retransmit queue, we need
make sure any chunks eligable for fast retransmit are sent first
during fast retransmission.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Tested-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 5d3c441..ace6770 100644 (file)
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -520,9 +520,15 @@ void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
         * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
         * following the procedures outlined in C1 - C5.
         */
-       sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
+       if (reason == SCTP_RTXR_T3_RTX)
+               sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 
-       error = sctp_outq_flush(q, /* rtx_timeout */ 1);
+       /* Flush the queues only on timeout, since fast_rtx is only
+        * triggered during sack processing and the queue
+        * will be flushed at the end.
+        */
+       if (reason != SCTP_RTXR_FAST_RTX)
+               error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 
        if (error)
                q->asoc->base.sk->sk_err = -error;
@@ -540,7 +546,6 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                               int rtx_timeout, int *start_timer)
 {
        struct list_head *lqueue;
-       struct list_head *lchunk;
        struct sctp_transport *transport = pkt->transport;
        sctp_xmit_t status;
        struct sctp_chunk *chunk, *chunk1;
@@ -548,12 +553,16 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
        int fast_rtx;
        int error = 0;
        int timer = 0;
+       int done = 0;
 
        asoc = q->asoc;
        lqueue = &q->retransmit;
        fast_rtx = q->fast_rtx;
 
-       /* RFC 2960 6.3.3 Handle T3-rtx Expiration
+       /* This loop handles time-out retransmissions, fast retransmissions,
+        * and retransmissions due to opening of whindow.
+        *
+        * RFC 2960 6.3.3 Handle T3-rtx Expiration
         *
         * E3) Determine how many of the earliest (i.e., lowest TSN)
         * outstanding DATA chunks for the address for which the
@@ -568,12 +577,12 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
         * [Just to be painfully clear, if we are retransmitting
         * because a timeout just happened, we should send only ONE
         * packet of retransmitted data.]
+        *
+        * For fast retransmissions we also send only ONE packet.  However,
+        * if we are just flushing the queue due to open window, we'll
+        * try to send as much as possible.
         */
-       lchunk = sctp_list_dequeue(lqueue);
-
-       while (lchunk) {
-               chunk = list_entry(lchunk, struct sctp_chunk,
-                                  transmitted_list);
+       list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 
                /* Make sure that Gap Acked TSNs are not retransmitted.  A
                 * simple approach is just to move such TSNs out of the
@@ -581,11 +590,18 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                 * next chunk.
                 */
                if (chunk->tsn_gap_acked) {
-                       list_add_tail(lchunk, &transport->transmitted);
-                       lchunk = sctp_list_dequeue(lqueue);
+                       list_del(&chunk->transmitted_list);
+                       list_add_tail(&chunk->transmitted_list,
+                                       &transport->transmitted);
                        continue;
                }
 
+               /* If we are doing fast retransmit, ignore non-fast_rtransmit
+                * chunks
+                */
+               if (fast_rtx && !chunk->fast_retransmit)
+                       continue;
+
                /* Attempt to append this chunk to the packet. */
                status = sctp_packet_append_chunk(pkt, chunk);
 
@@ -597,12 +613,10 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                        /* If we are retransmitting, we should only
                         * send a single packet.
                         */
-                       if (rtx_timeout || fast_rtx) {
-                               list_add(lchunk, lqueue);
-                               lchunk = NULL;
-                       }
+                       if (rtx_timeout || fast_rtx)
+                               done = 1;
 
-                       /* Bundle lchunk in the next round.  */
+                       /* Bundle next chunk in the next round.  */
                        break;
 
                case SCTP_XMIT_RWND_FULL:
@@ -612,8 +626,7 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                        /* Stop sending DATA as there is no more room
                         * at the receiver.
                         */
-                       list_add(lchunk, lqueue);
-                       lchunk = NULL;
+                       done = 1;
                        break;
 
                case SCTP_XMIT_NAGLE_DELAY:
@@ -621,15 +634,16 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                        error = sctp_packet_transmit(pkt);
 
                        /* Stop sending DATA because of nagle delay. */
-                       list_add(lchunk, lqueue);
-                       lchunk = NULL;
+                       done = 1;
                        break;
 
                default:
                        /* The append was successful, so add this chunk to
                         * the transmitted list.
                         */
-                       list_add_tail(lchunk, &transport->transmitted);
+                       list_del(&chunk->transmitted_list);
+                       list_add_tail(&chunk->transmitted_list,
+                                       &transport->transmitted);
 
                        /* Mark the chunk as ineligible for fast retransmit
                         * after it is retransmitted.
@@ -646,9 +660,6 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                                timer = 2;
 
                        q->empty = 0;
-
-                       /* Retrieve a new chunk to bundle. */
-                       lchunk = sctp_list_dequeue(lqueue);
                        break;
                }
 
@@ -656,16 +667,19 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                if (!error && !timer)
                        timer = 1;
 
-               /* If we are here due to a retransmit timeout or a fast
-                * retransmit and if there are any chunks left in the retransmit
-                * queue that could not fit in the PMTU sized packet, they need
-                * to be marked as ineligible for a subsequent fast retransmit.
-                */
-               if (rtx_timeout && fast_rtx) {
-                       list_for_each_entry(chunk1, lqueue, transmitted_list) {
-                               if (chunk1->fast_retransmit > 0)
-                                       chunk1->fast_retransmit = -1;
-                       }
+               if (done)
+                       break;
+       }
+
+       /* If we are here due to a retransmit timeout or a fast
+        * retransmit and if there are any chunks left in the retransmit
+        * queue that could not fit in the PMTU sized packet, they need
+        * to be marked as ineligible for a subsequent fast retransmit.
+        */
+       if (rtx_timeout || fast_rtx) {
+               list_for_each_entry(chunk1, lqueue, transmitted_list) {
+                       if (chunk1->fast_retransmit > 0)
+                               chunk1->fast_retransmit = -1;
                }
        }