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authorNeil Horman <nhorman@tuxdriver.com>2012-06-30 03:04:26 +0000
committerDavid S. Miller <davem@davemloft.net>2012-06-30 22:44:35 -0700
commit4244854d22bf8f782698c5224b9191c8d2d42610 (patch)
tree1c6d81517625a33e427a183587783a966960e135 /include/net/sctp
parent0e90b49ca4b891f085b57559a3071a4feefb496c (diff)
downloadop-kernel-dev-4244854d22bf8f782698c5224b9191c8d2d42610.zip
op-kernel-dev-4244854d22bf8f782698c5224b9191c8d2d42610.tar.gz
sctp: be more restrictive in transport selection on bundled sacks
It was noticed recently that when we send data on a transport, its possible that we might bundle a sack that arrived on a different transport. While this isn't a major problem, it does go against the SHOULD requirement in section 6.4 of RFC 2960: An endpoint SHOULD transmit reply chunks (e.g., SACK, HEARTBEAT ACK, etc.) to the same destination transport address from which it received the DATA or control chunk to which it is replying. This rule should also be followed if the endpoint is bundling DATA chunks together with the reply chunk. This patch seeks to correct that. It restricts the bundling of sack operations to only those transports which have moved the ctsn of the association forward since the last sack. By doing this we guarantee that we only bundle outbound saks on a transport that has received a chunk since the last sack. This brings us into stricter compliance with the RFC. Vlad had initially suggested that we strictly allow only sack bundling on the transport that last moved the ctsn forward. While this makes sense, I was concerned that doing so prevented us from bundling in the case where we had received chunks that moved the ctsn on multiple transports. In those cases, the RFC allows us to select any of the transports having received chunks to bundle the sack on. so I've modified the approach to allow for that, by adding a state variable to each transport that tracks weather it has moved the ctsn since the last sack. This I think keeps our behavior (and performance), close enough to our current profile that I think we can do this without a sysctl knob to enable/disable it. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> CC: Vlad Yaseivch <vyasevich@gmail.com> CC: David S. Miller <davem@davemloft.net> CC: linux-sctp@vger.kernel.org Reported-by: Michele Baldessari <michele@redhat.com> Reported-by: sorin serban <sserban@redhat.com> Acked-by: Vlad Yasevich <vyasevich@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/sctp')
-rw-r--r--include/net/sctp/structs.h4
-rw-r--r--include/net/sctp/tsnmap.h3
2 files changed, 6 insertions, 1 deletions
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index e4652fe..fecdf31 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -912,6 +912,9 @@ struct sctp_transport {
/* Is this structure kfree()able? */
malloced:1;
+ /* Has this transport moved the ctsn since we last sacked */
+ __u32 sack_generation;
+
struct flowi fl;
/* This is the peer's IP address and port. */
@@ -1584,6 +1587,7 @@ struct sctp_association {
*/
__u8 sack_needed; /* Do we need to sack the peer? */
__u32 sack_cnt;
+ __u32 sack_generation;
/* These are capabilities which our peer advertised. */
__u8 ecn_capable:1, /* Can peer do ECN? */
diff --git a/include/net/sctp/tsnmap.h b/include/net/sctp/tsnmap.h
index e7728bc..2c5d2b4 100644
--- a/include/net/sctp/tsnmap.h
+++ b/include/net/sctp/tsnmap.h
@@ -117,7 +117,8 @@ void sctp_tsnmap_free(struct sctp_tsnmap *map);
int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
/* Mark this TSN as seen. */
-int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn);
+int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn,
+ struct sctp_transport *trans);
/* Mark this TSN and all lower as seen. */
void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
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