Commit eacf078c authored by Xin Long's avatar Xin Long Committed by David S. Miller
Browse files

sctp: send pmtu probe only if packet loss in Search Complete state 



This patch is to introduce last_rtx_chunks into sctp_transport to detect
if there's any packet retransmission/loss happened by checking against
asoc's rtx_data_chunks in sctp_transport_pl_send().

If there is, namely, transport->last_rtx_chunks != asoc->rtx_data_chunks,
the pmtu probe will be sent out. Otherwise, increment the pl.raise_count
and return when it's in Search Complete state.

With this patch, if in Search Complete state, which is a long period, it
doesn't need to keep probing the current pmtu unless there's data packet
loss. This will save quite some traffic.

v1->v2:
  - add the missing Fixes tag.

Fixes: 0dac127c ("sctp: do black hole detection in search complete state")
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 058e6e0e

include/net/sctp/structs.h

+1 −0
Original line number Diff line number Diff line
@@ -984,6 +984,7 @@ struct sctp_transport { 
	} cacc;



	struct {

		__u32 last_rtx_chunks;

		__u16 pmtu;

		__u16 probe_size;

		__u16 probe_high;

net/sctp/transport.c

+5 −1
Original line number Diff line number Diff line
@@ -263,6 +263,7 @@ bool sctp_transport_pl_send(struct sctp_transport *t) 
	if (t->pl.probe_count < SCTP_MAX_PROBES)

		goto out;



	t->pl.last_rtx_chunks = t->asoc->rtx_data_chunks;

	t->pl.probe_count = 0;

	if (t->pl.state == SCTP_PL_BASE) {

		if (t->pl.probe_size == SCTP_BASE_PLPMTU) { /* BASE_PLPMTU Confirmation Failed */
@@ -298,8 +299,10 @@ bool sctp_transport_pl_send(struct sctp_transport *t) 


out:

	if (t->pl.state == SCTP_PL_COMPLETE && t->pl.raise_count < 30 &&

	    !t->pl.probe_count)

	    !t->pl.probe_count && t->pl.last_rtx_chunks == t->asoc->rtx_data_chunks) {

		t->pl.raise_count++;

		return false;

	}



	pr_debug("%s: PLPMTUD: transport: %p, state: %d, pmtu: %d, size: %d, high: %d\n",

		 __func__, t, t->pl.state, t->pl.pmtu, t->pl.probe_size, t->pl.probe_high);
@@ -313,6 +316,7 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) 
	pr_debug("%s: PLPMTUD: transport: %p, state: %d, pmtu: %d, size: %d, high: %d\n",

		 __func__, t, t->pl.state, t->pl.pmtu, t->pl.probe_size, t->pl.probe_high);



	t->pl.last_rtx_chunks = t->asoc->rtx_data_chunks;

	t->pl.pmtu = t->pl.probe_size;

	t->pl.probe_count = 0;

	if (t->pl.state == SCTP_PL_BASE) {