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Commit 27852c26 authored by Vlad Yasevich's avatar Vlad Yasevich Committed by David S. Miller
Browse files

[SCTP]: Fix 'fast retransmit' to send a TSN only once. 



SCTP used to "fast retransmit" a TSN every time we hit the number
of missing reports for the TSN.  However the Implementers Guide
specifies that we should only "fast retransmit" a given TSN once.
Subsequent retransmits should be timeouts only. Also change the
number of missing reports to 3 as per the latest IG(similar to TCP).

Signed-off-by: default avatarVlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: default avatarSridhar Samudrala <sri@us.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4641e7a3

include/net/sctp/structs.h

+1 −1
Original line number Diff line number Diff line
@@ -700,7 +700,7 @@ struct sctp_chunk { 
	__u8 ecn_ce_done;	/* Have we processed the ECN CE bit? */

	__u8 pdiscard;		/* Discard the whole packet now? */

	__u8 tsn_gap_acked;	/* Is this chunk acked by a GAP ACK? */

	__u8 fast_retransmit;	 /* Is this chunk fast retransmitted? */

	__s8 fast_retransmit;	 /* Is this chunk fast retransmitted? */

	__u8 tsn_missing_report; /* Data chunk missing counter. */

};

net/sctp/output.c

+1 −1
Original line number Diff line number Diff line
@@ -608,7 +608,7 @@ static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, 
	 *    When a Fast Retransmit is being performed the sender SHOULD

	 *    ignore the value of cwnd and SHOULD NOT delay retransmission.

	 */

	if (!chunk->fast_retransmit)

	if (chunk->fast_retransmit <= 0)

		if (transport->flight_size >= transport->cwnd) {

			retval = SCTP_XMIT_RWND_FULL;

			goto finish;

net/sctp/outqueue.c

+7 −5
Original line number Diff line number Diff line
@@ -406,7 +406,7 @@ void sctp_retransmit_mark(struct sctp_outq *q, 
		 * chunks that are not yet acked should be added to the

		 * retransmit queue.

		 */

		if ((fast_retransmit && chunk->fast_retransmit) ||

		if ((fast_retransmit && (chunk->fast_retransmit > 0)) ||

		   (!fast_retransmit && !chunk->tsn_gap_acked)) {

			/* RFC 2960 6.2.1 Processing a Received SACK

			 *
@@ -603,7 +603,8 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt, 
			/* Mark the chunk as ineligible for fast retransmit 

			 * after it is retransmitted.

			 */

			chunk->fast_retransmit = 0;

			if (chunk->fast_retransmit > 0)

				chunk->fast_retransmit = -1;



			*start_timer = 1;

			q->empty = 0;
@@ -621,7 +622,8 @@ static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt, 
			list_for_each(lchunk1, lqueue) {

				chunk1 = list_entry(lchunk1, struct sctp_chunk,

						    transmitted_list);

				chunk1->fast_retransmit = 0;

				if (chunk1->fast_retransmit > 0)

					chunk1->fast_retransmit = -1;

			}

		}

	}
@@ -1562,11 +1564,11 @@ static void sctp_mark_missing(struct sctp_outq *q, 
		/*

		 * M4) If any DATA chunk is found to have a

		 * 'TSN.Missing.Report'

		 * value larger than or equal to 4, mark that chunk for

		 * value larger than or equal to 3, mark that chunk for

		 * retransmission and start the fast retransmit procedure.

		 */



		if (chunk->tsn_missing_report >= 4) {

		if (chunk->tsn_missing_report >= 3) {

			chunk->fast_retransmit = 1;

			do_fast_retransmit = 1;

		}