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authorJon Paul Maloy <jon.maloy@ericsson.com>2014-05-14 05:39:10 -0400
committerDavid S. Miller <davem@davemloft.net>2014-05-14 15:19:48 -0400
commitec37dcd382b4f3673bfbf36ccd348ef48f98ffe3 (patch)
tree36e531fe3602013d202ba7219b208c0c45ccda1e /net/tipc
parent4f4482dcd9a0606a30541ff165ddaca64748299b (diff)
downloadlinux-ec37dcd382b4f3673bfbf36ccd348ef48f98ffe3.tar.bz2
tipc: don't record link RESET or ACTIVATE messages as traffic
In the current code, all incoming LINK_PROTOCOL messages, irrespective of type, nudge the "last message received" checkpoint, informing the link state machine that a message was received from the peer since last supervision timeout event. This inhibits the link from starting probing the peer unnecessarily. However, not only STATE messages are recorded as legitimate incoming traffic this way, but even RESET and ACTIVATE messages, which in reality are there to inform the link that the peer endpoint has been reset. At the same time, some RESET messages may be dropped instead of causing a link reset. This happens when the link endpoint thinks it is fully up and working, and the session number of the RESET is lower than or equal to the current link session. In such cases the RESET is perceived as a delayed remnant from an earlier session, or the current one, and dropped. Now, if a TIPC module is removed and then immediately reinserted, e.g. when using a script, RESET messages may arrive at the peer link endpoint before this one has had time to discover the failure. The RESET may be dropped because of the session number, but only after it has been recorded as a legitimate traffic event. Hence, the receiving link will not start probing, and not discover that the peer endpoint is down, at the same time ignoring the periodic RESET messages coming from that endpoint. We have ended up in a stale state where a failed link cannot be re-established. In this commit, we remedy this by nudging the checkpoint only for received STATE messages, not for RESET or ACTIVATE messages. Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Reviewed-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
-rw-r--r--net/tipc/link.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/net/tipc/link.c b/net/tipc/link.c
index 2140837fbab9..6cf7938784c6 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1831,9 +1831,6 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr, struct sk_buff *buf)
if (l_ptr->exp_msg_count)
goto exit;
- /* record unnumbered packet arrival (force mismatch on next timeout) */
- l_ptr->checkpoint--;
-
if (l_ptr->net_plane != msg_net_plane(msg))
if (tipc_own_addr > msg_prevnode(msg))
l_ptr->net_plane = msg_net_plane(msg);
@@ -1909,6 +1906,10 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr, struct sk_buff *buf)
tipc_link_reset(l_ptr); /* Enforce change to take effect */
break;
}
+
+ /* Record reception; force mismatch at next timeout: */
+ l_ptr->checkpoint--;
+
link_state_event(l_ptr, TRAFFIC_MSG_EVT);
l_ptr->stats.recv_states++;
if (link_reset_unknown(l_ptr))