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>

1 files changed, 48 insertions, 34 deletions

diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 5d3c441e84d3..ace6770e9048 100644
--- 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;
                 }
         }