Commit b6157d8e authored by Vlad Yasevich's avatar Vlad Yasevich
Browse files

SCTP: Fix difference cases of retransmit. 



Commit d0ce9291 broke several retransmit
cases including fast retransmit.  The reason is that we should
only delay by rto while doing retranmists as a result of a timeout.
Retransmit as a result of path mtu discover, fast retransmit, or
other evernts that should trigger immidiate retransmissions got broken.

Also, since rto is doubled prior to marking of packets elegable for
retransmission, we never marked correct chunks anyway.

The fix is provide a reason for a given retransmission so that we
can mark chunks appropriately and to save the old rto value to do
comparisons against.

All regressions tests passed with this code.

Spotted by Wei Yongjun <yjwei@cn.fujitsu.com>

Signed-off-by: default avatarVlad Yasevich <vladislav.yasevich@hp.com>
parent f3830ccc

include/net/sctp/command.h

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ typedef enum { 
	SCTP_CMD_ASSOC_CHANGE,	 /* generate and send assoc_change event */

	SCTP_CMD_ADAPTATION_IND, /* generate and send adaptation event */

	SCTP_CMD_ASSOC_SHKEY,    /* generate the association shared keys */

	SCTP_CMD_T1_RETRAN,	 /* Mark for retransmission after T1 timeout  */

	SCTP_CMD_LAST

} sctp_verb_t;

include/net/sctp/constants.h

+1 −0
Original line number Diff line number Diff line
@@ -407,6 +407,7 @@ typedef enum { 
	SCTP_RTXR_T3_RTX,

	SCTP_RTXR_FAST_RTX,

	SCTP_RTXR_PMTUD,

	SCTP_RTXR_T1_RTX,

} sctp_retransmit_reason_t;



/* Reasons to lower cwnd. */

include/net/sctp/sctp.h

+1 −0
Original line number Diff line number Diff line
@@ -267,6 +267,7 @@ enum 
	SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS,

	SCTP_MIB_DELAY_SACK_EXPIREDS,

	SCTP_MIB_AUTOCLOSE_EXPIREDS,

	SCTP_MIB_T1_RETRANSMITS,

	SCTP_MIB_T3_RETRANSMITS,

	SCTP_MIB_PMTUD_RETRANSMITS,

	SCTP_MIB_FAST_RETRANSMITS,

include/net/sctp/structs.h

+3 −2
Original line number Diff line number Diff line
@@ -873,10 +873,11 @@ struct sctp_transport { 
	 * address list derived from the INIT or INIT ACK chunk, a

	 * number of data elements needs to be maintained including:

	 */

	__u32 rtt;		/* This is the most recent RTT.	 */



	/* RTO	       : The current retransmission timeout value.  */

	unsigned long rto;

	unsigned long last_rto;



	__u32 rtt;		/* This is the most recent RTT.	 */



	/* RTTVAR      : The current RTT variation.  */

	__u32 rttvar;

net/sctp/outqueue.c

+17 −16
Original line number Diff line number Diff line
@@ -382,7 +382,7 @@ static void sctp_insert_list(struct list_head *head, struct list_head *new) 
/* Mark all the eligible packets on a transport for retransmission.  */

void sctp_retransmit_mark(struct sctp_outq *q,

			  struct sctp_transport *transport,

			  __u8 fast_retransmit)

			  __u8 reason)

{

	struct list_head *lchunk, *ltemp;

	struct sctp_chunk *chunk;
@@ -412,20 +412,20 @@ void sctp_retransmit_mark(struct sctp_outq *q, 
			continue;

		}



		/* If we are doing retransmission due to a fast retransmit,

		 * only the chunk's that are marked for fast retransmit

		 * should be added to the retransmit queue.  If we are doing

		 * retransmission due to a timeout or pmtu discovery, only the

		 * chunks that are not yet acked should be added to the

		 * retransmit queue.

		/* If we are doing  retransmission due to a timeout or pmtu

		 * discovery, only the  chunks that are not yet acked should

		 * be added to the retransmit queue.

		 */

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

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

		if ((reason == SCTP_RTXR_FAST_RTX  &&

			    (chunk->fast_retransmit > 0)) ||

		    (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {

			/* If this chunk was sent less then 1 rto ago, do not

			 * retransmit this chunk, but give the peer time

			 * to acknowlege it.

			 * to acknowlege it.  Do this only when

			 * retransmitting due to T3 timeout.

			 */

			if ((jiffies - chunk->sent_at) < transport->rto)

			if (reason == SCTP_RTXR_T3_RTX &&

			    (jiffies - chunk->sent_at) < transport->last_rto)

				continue;



			/* RFC 2960 6.2.1 Processing a Received SACK
@@ -467,10 +467,10 @@ void sctp_retransmit_mark(struct sctp_outq *q, 
		}

	}



	SCTP_DEBUG_PRINTK("%s: transport: %p, fast_retransmit: %d, "

	SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "

			  "cwnd: %d, ssthresh: %d, flight_size: %d, "

			  "pba: %d\n", __FUNCTION__,

			  transport, fast_retransmit,

			  transport, reason,

			  transport->cwnd, transport->ssthresh,

			  transport->flight_size,

			  transport->partial_bytes_acked);
@@ -484,7 +484,6 @@ void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport, 
		     sctp_retransmit_reason_t reason)

{

	int error = 0;

	__u8 fast_retransmit = 0;



	switch(reason) {

	case SCTP_RTXR_T3_RTX:
@@ -499,16 +498,18 @@ 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);

		fast_retransmit = 1;

		break;

	case SCTP_RTXR_PMTUD:

		SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);

		break;

	case SCTP_RTXR_T1_RTX:

		SCTP_INC_STATS(SCTP_MIB_T1_RETRANSMITS);

		break;

	default:

		BUG();

	}



	sctp_retransmit_mark(q, transport, fast_retransmit);

	sctp_retransmit_mark(q, transport, reason);



	/* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,

	 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by

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