Commit cf9b4812 authored by Vlad Yasevich's avatar Vlad Yasevich
Browse files

sctp: fast recovery algorithm is per association. 



SCTP fast recovery algorithm really applies per association
and impacts all transports.

Signed-off-by: default avatarVlad Yasevich <vladislav.yasevich@hp.com>
parent b2cf9b6b

include/net/sctp/structs.h

+6 −6
Original line number Diff line number Diff line
@@ -895,9 +895,6 @@ struct sctp_transport { 
		 */

		hb_sent:1,



		/* Flag to track the current fast recovery state */

		fast_recovery:1,



		/* Is the Path MTU update pending on this tranport */

		pmtu_pending:1,
@@ -952,9 +949,6 @@ struct sctp_transport { 


	__u32 burst_limited;	/* Holds old cwnd when max.burst is applied */



	/* TSN marking the fast recovery exit point */

	__u32 fast_recovery_exit;



	/* Destination */

	struct dst_entry *dst;

	/* Source address. */
@@ -1723,6 +1717,12 @@ struct sctp_association { 
	/* Highest TSN that is acknowledged by incoming SACKs. */

	__u32 highest_sacked;



	/* TSN marking the fast recovery exit point */

	__u32 fast_recovery_exit;



	/* Flag to track the current fast recovery state */

	__u8 fast_recovery;



	/* The number of unacknowledged data chunks.  Reported through

	 * the SCTP_STATUS sockopt.

	 */

net/sctp/transport.c

+17 −15
Original line number Diff line number Diff line
@@ -378,15 +378,16 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) 
void sctp_transport_raise_cwnd(struct sctp_transport *transport,

			       __u32 sack_ctsn, __u32 bytes_acked)

{

	struct sctp_association *asoc = transport->asoc;

	__u32 cwnd, ssthresh, flight_size, pba, pmtu;



	cwnd = transport->cwnd;

	flight_size = transport->flight_size;



	/* See if we need to exit Fast Recovery first */

	if (transport->fast_recovery &&

	    TSN_lte(transport->fast_recovery_exit, sack_ctsn))

		transport->fast_recovery = 0;

	if (asoc->fast_recovery &&

	    TSN_lte(asoc->fast_recovery_exit, sack_ctsn))

		asoc->fast_recovery = 0;



	/* The appropriate cwnd increase algorithm is performed if, and only

	 * if the cumulative TSN whould advanced and the congestion window is
@@ -415,7 +416,7 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport, 
		 *    2) the destination's path MTU.  This upper bound protects

		 *    against the ACK-Splitting attack outlined in [SAVAGE99].

		 */

		if (transport->fast_recovery)

		if (asoc->fast_recovery)

			return;



		if (bytes_acked > pmtu)
@@ -466,6 +467,8 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport, 
void sctp_transport_lower_cwnd(struct sctp_transport *transport,

			       sctp_lower_cwnd_t reason)

{

	struct sctp_association *asoc = transport->asoc;



	switch (reason) {

	case SCTP_LOWER_CWND_T3_RTX:

		/* RFC 2960 Section 7.2.3, sctpimpguide
@@ -476,11 +479,11 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport, 
		 *      partial_bytes_acked = 0

		 */

		transport->ssthresh = max(transport->cwnd/2,

					  4*transport->asoc->pathmtu);

		transport->cwnd = transport->asoc->pathmtu;

					  4*asoc->pathmtu);

		transport->cwnd = asoc->pathmtu;



		/* T3-rtx also clears fast recovery on the transport */

		transport->fast_recovery = 0;

		/* T3-rtx also clears fast recovery */

		asoc->fast_recovery = 0;

		break;



	case SCTP_LOWER_CWND_FAST_RTX:
@@ -496,15 +499,15 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport, 
		 *      cwnd = ssthresh

		 *      partial_bytes_acked = 0

		 */

		if (transport->fast_recovery)

		if (asoc->fast_recovery)

			return;



		/* Mark Fast recovery */

		transport->fast_recovery = 1;

		transport->fast_recovery_exit = transport->asoc->next_tsn - 1;

		asoc->fast_recovery = 1;

		asoc->fast_recovery_exit = asoc->next_tsn - 1;



		transport->ssthresh = max(transport->cwnd/2,

					  4*transport->asoc->pathmtu);

					  4*asoc->pathmtu);

		transport->cwnd = transport->ssthresh;

		break;
@@ -524,7 +527,7 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport, 
		if (time_after(jiffies, transport->last_time_ecne_reduced +

					transport->rtt)) {

			transport->ssthresh = max(transport->cwnd/2,

						  4*transport->asoc->pathmtu);

						  4*asoc->pathmtu);

			transport->cwnd = transport->ssthresh;

			transport->last_time_ecne_reduced = jiffies;

		}
@@ -540,7 +543,7 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport, 
		 * interval.

		 */

		transport->cwnd = max(transport->cwnd/2,

					 4*transport->asoc->pathmtu);

					 4*asoc->pathmtu);

		break;

	}
@@ -625,7 +628,6 @@ void sctp_transport_reset(struct sctp_transport *t) 
	t->error_count = 0;

	t->rto_pending = 0;

	t->hb_sent = 0;

	t->fast_recovery = 0;



	/* Initialize the state information for SFR-CACC */

	t->cacc.changeover_active = 0;