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authorJon Paul Maloy <jon.maloy@ericsson.com>2015-04-28 16:59:04 -0400
committerDavid S. Miller <davem@davemloft.net>2015-04-29 15:08:59 -0400
commit0d699f28ee5d0641470a603ab5904e463cb1532a (patch)
tree597955a870c0228131cb61bac200423b275033ba /net
parentf2f67390a4b961dae83733732e96e1a394a53c4e (diff)
downloadkernel-0d699f28ee5d0641470a603ab5904e463cb1532a.tar.gz
tipc: fix problem with parallel link synchronization mechanism
Currently, we try to accumulate arrived packets in the links's 'deferred' queue during the parallel link syncronization phase. This entails two problems: - With an unlucky combination of arriving packets the algorithm may go into a lockstep with the out-of-sequence handling function, where the synch mechanism is adding a packet to the deferred queue, while the out-of-sequence handling is retrieving it again, thus ending up in a loop inside the node_lock scope. - Even if this is avoided, the link will very often send out unnecessary protocol messages, in the worst case leading to redundant retransmissions. We fix this by just dropping arriving packets on the upcoming link during the synchronization phase, thus relying on the retransmission protocol to resolve the situation once the two links have arrived to a synchronized state. Reviewed-by: Erik Hugne <erik.hugne@ericsson.com> Reviewed-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/tipc/link.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/net/tipc/link.c b/net/tipc/link.c
index a11cc5e5e0ae..43a515dc97b0 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1145,11 +1145,8 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
}
/* Synchronize with parallel link if applicable */
if (unlikely((l_ptr->flags & LINK_SYNCHING) && !msg_dup(msg))) {
- link_handle_out_of_seq_msg(l_ptr, skb);
- if (link_synch(l_ptr))
- link_retrieve_defq(l_ptr, &head);
- skb = NULL;
- goto unlock;
+ if (!link_synch(l_ptr))
+ goto unlock;
}
l_ptr->next_in_no++;
if (unlikely(!skb_queue_empty(&l_ptr->deferdq)))