sctp: Start T3-RTX timer when fast retransmitting lowest TSN

When we are trying to fast retransmit the lowest outstanding TSN, we
need to restart the T3-RTX timer, so that subsequent timeouts will
correctly tag all the packets necessary for retransmissions.

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/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 6759207..714dc43 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1051,7 +1051,7 @@ void sctp_transport_route(struct sctp_transport *, union sctp_addr *,
                          struct sctp_sock *);
 void sctp_transport_pmtu(struct sctp_transport *);
 void sctp_transport_free(struct sctp_transport *);
-void sctp_transport_reset_timers(struct sctp_transport *);
+void sctp_transport_reset_timers(struct sctp_transport *, int);
 void sctp_transport_hold(struct sctp_transport *);
 void sctp_transport_put(struct sctp_transport *);
 void sctp_transport_update_rto(struct sctp_transport *, __u32);
@@ -1141,6 +1141,9 @@ struct sctp_outq {
        /* How many unackd bytes do we have in-flight?  */
        __u32 outstanding_bytes;
 
+       /* Are we doing fast-rtx on this queue */
+       char fast_rtx;
+
        /* Corked? */
        char cork;
 

diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 59edfd2..5d3c441 100644 (file)
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -208,6 +208,7 @@ void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
        INIT_LIST_HEAD(&q->sacked);
        INIT_LIST_HEAD(&q->abandoned);
 
+       q->fast_rtx = 0;
        q->outstanding_bytes = 0;
        q->empty = 1;
        q->cork  = 0;
@@ -500,6 +501,7 @@ void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
        case SCTP_RTXR_FAST_RTX:
                SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);
                sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
+               q->fast_rtx = 1;
                break;
        case SCTP_RTXR_PMTUD:
                SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);
@@ -543,10 +545,13 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
        sctp_xmit_t status;
        struct sctp_chunk *chunk, *chunk1;
        struct sctp_association *asoc;
+       int fast_rtx;
        int error = 0;
+       int timer = 0;
 
        asoc = q->asoc;
        lqueue = &q->retransmit;
+       fast_rtx = q->fast_rtx;
 
        /* RFC 2960 6.3.3 Handle T3-rtx Expiration
         *
@@ -587,13 +592,12 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                switch (status) {
                case SCTP_XMIT_PMTU_FULL:
                        /* Send this packet.  */
-                       if ((error = sctp_packet_transmit(pkt)) == 0)
-                               *start_timer = 1;
+                       error = sctp_packet_transmit(pkt);
 
                        /* If we are retransmitting, we should only
                         * send a single packet.
                         */
-                       if (rtx_timeout) {
+                       if (rtx_timeout || fast_rtx) {
                                list_add(lchunk, lqueue);
                                lchunk = NULL;
                        }
@@ -603,8 +607,7 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 
                case SCTP_XMIT_RWND_FULL:
                        /* Send this packet. */
-                       if ((error = sctp_packet_transmit(pkt)) == 0)
-                               *start_timer = 1;
+                       error = sctp_packet_transmit(pkt);
 
                        /* Stop sending DATA as there is no more room
                         * at the receiver.
@@ -615,8 +618,7 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 
                case SCTP_XMIT_NAGLE_DELAY:
                        /* Send this packet. */
-                       if ((error = sctp_packet_transmit(pkt)) == 0)
-                               *start_timer = 1;
+                       error = sctp_packet_transmit(pkt);
 
                        /* Stop sending DATA because of nagle delay. */
                        list_add(lchunk, lqueue);
@@ -635,7 +637,14 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                        if (chunk->fast_retransmit > 0)
                                chunk->fast_retransmit = -1;
 
-                       *start_timer = 1;
+                       /* Force start T3-rtx timer when fast retransmitting
+                        * the earliest outstanding TSN
+                        */
+                       if (!timer && fast_rtx &&
+                           ntohl(chunk->subh.data_hdr->tsn) ==
+                                            asoc->ctsn_ack_point + 1)
+                               timer = 2;
+
                        q->empty = 0;
 
                        /* Retrieve a new chunk to bundle. */
@@ -643,12 +652,16 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                        break;
                }
 
+               /* Set the timer if there were no errors */
+               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 && !lchunk) {
+               if (rtx_timeout && fast_rtx) {
                        list_for_each_entry(chunk1, lqueue, transmitted_list) {
                                if (chunk1->fast_retransmit > 0)
                                        chunk1->fast_retransmit = -1;
@@ -656,6 +669,12 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
                }
        }
 
+       *start_timer = timer;
+
+       /* Clear fast retransmit hint */
+       if (fast_rtx)
+               q->fast_rtx = 0;
+
        return error;
 }
 
@@ -862,7 +881,8 @@ int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
                                                    rtx_timeout, &start_timer);
 
                        if (start_timer)
-                               sctp_transport_reset_timers(transport);
+                               sctp_transport_reset_timers(transport,
+                                                           start_timer-1);
 
                        /* This can happen on COOKIE-ECHO resend.  Only
                         * one chunk can get bundled with a COOKIE-ECHO.
@@ -977,7 +997,7 @@ int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
                        list_add_tail(&chunk->transmitted_list,
                                      &transport->transmitted);
 
-                       sctp_transport_reset_timers(transport);
+                       sctp_transport_reset_timers(transport, start_timer-1);
 
                        q->empty = 0;
 

diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 9647fb2..3f34f61 100644 (file)
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -191,7 +191,7 @@ static void sctp_transport_destroy(struct sctp_transport *transport)
 /* Start T3_rtx timer if it is not already running and update the heartbeat
  * timer.  This routine is called every time a DATA chunk is sent.
  */
-void sctp_transport_reset_timers(struct sctp_transport *transport)
+void sctp_transport_reset_timers(struct sctp_transport *transport, int force)
 {
        /* RFC 2960 6.3.2 Retransmission Timer Rules
         *
@@ -201,7 +201,7 @@ void sctp_transport_reset_timers(struct sctp_transport *transport)
         * address.
         */
 
-       if (!timer_pending(&transport->T3_rtx_timer))
+       if (force || !timer_pending(&transport->T3_rtx_timer))
                if (!mod_timer(&transport->T3_rtx_timer,
                               jiffies + transport->rto))
                        sctp_transport_hold(transport);