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Commit d805397c authored by Xin Long's avatar Xin Long Committed by David S. Miller
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sctp: use the pmtu from the icmp packet to update transport pathmtu 



Other than asoc pmtu sync from all transports, sctp_assoc_sync_pmtu
is also processing transport pmtu_pending by icmp packets. But it's
meaningless to use sctp_dst_mtu(t->dst) as new pmtu for a transport.

The right pmtu value should come from the icmp packet, and it would
be saved into transport->mtu_info in this patch and used later when
the pmtu sync happens in sctp_sendmsg_to_asoc or sctp_packet_config.

Besides, without this patch, as pmtu can only be updated correctly
when receiving a icmp packet and no place is holding sock lock, it
will take long time if the sock is busy with sending packets.

Note that it doesn't process transport->mtu_info in .release_cb(),
as there is no enough information for pmtu update, like for which
asoc or transport. It is not worth traversing all asocs to check
pmtu_pending. So unlike tcp, sctp does this in tx path, for which
mtu_info needs to be atomic_t.

Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Acked-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ec20a63a

include/net/sctp/structs.h

+2 −0
Original line number Diff line number Diff line
@@ -876,6 +876,8 @@ struct sctp_transport { 
	unsigned long sackdelay;

	__u32 sackfreq;



	atomic_t mtu_info;



	/* When was the last time that we heard from this transport? We use

	 * this to pick new active and retran paths.

	 */

net/sctp/associola.c

+2 −1
Original line number Diff line number Diff line
@@ -1450,7 +1450,8 @@ void sctp_assoc_sync_pmtu(struct sctp_association *asoc) 
	/* Get the lowest pmtu of all the transports. */

	list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {

		if (t->pmtu_pending && t->dst) {

			sctp_transport_update_pmtu(t, sctp_dst_mtu(t->dst));

			sctp_transport_update_pmtu(t,

						   atomic_read(&t->mtu_info));

			t->pmtu_pending = 0;

		}

		if (!pmtu || (t->pathmtu < pmtu))

net/sctp/input.c

+1 −0
Original line number Diff line number Diff line
@@ -395,6 +395,7 @@ void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 
		return;



	if (sock_owned_by_user(sk)) {

		atomic_set(&t->mtu_info, pmtu);

		asoc->pmtu_pending = 1;

		t->pmtu_pending = 1;

		return;

net/sctp/output.c

+6 −0
Original line number Diff line number Diff line
@@ -120,6 +120,12 @@ void sctp_packet_config(struct sctp_packet *packet, __u32 vtag, 
			sctp_assoc_sync_pmtu(asoc);

	}



	if (asoc->pmtu_pending) {

		if (asoc->param_flags & SPP_PMTUD_ENABLE)

			sctp_assoc_sync_pmtu(asoc);

		asoc->pmtu_pending = 0;

	}



	/* If there a is a prepend chunk stick it on the list before

	 * any other chunks get appended.

	 */