@@ -1116,7 +1116,7 @@ static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
}
/* Ignore duplicate packets */
- if (less(oseqno, rcv_nxt))
+ if ((usr != LINK_PROTOCOL) && less(oseqno, rcv_nxt))
return true;
/* Initiate or update failover mode if applicable */
@@ -1146,8 +1146,8 @@ static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
if (!pl || !tipc_link_is_up(pl))
return true;
- /* Initiate or update synch mode if applicable */
- if ((usr == TUNNEL_PROTOCOL) && (mtyp == SYNCH_MSG)) {
+ /* Initiate synch mode if applicable */
+ if ((usr == TUNNEL_PROTOCOL) && (mtyp == SYNCH_MSG) && (oseqno == 1)) {
syncpt = iseqno + exp_pkts - 1;
if (!tipc_link_is_up(l)) {
tipc_link_fsm_evt(l, LINK_ESTABLISH_EVT);
In commit 6e498158a827 ("tipc: move link synch and failover to link aggregation level") we introduced a new mechanism for performing link failover and synchronization. We have now detected a bug in this mechanism. During link synchronization we use the arrival of any packet on the tunnel link to trig a check for whether it has reached the synchronization point or not. This has turned out to be too permissive, since it may cause an arriving non-last SYNCH packet to end the synch state, just to see the next SYNCH packet initiate a new synch state with a new, higher synch point. This is not fatal, but should be avoided, because it may significantly extend the synchronization period, while at the same time we are not allowed to send NACKs if packets are lost. In the worst case, a low-traffic user may see its traffic stall until a LINK_PROTOCOL state message trigs the link to leave synchronization state. At the same time, LINK_PROTOCOL packets which happen to have a (non- valid) sequence number lower than the tunnel link's rcv_nxt value will be consistently dropped, and will never be able to resolve the situation described above. We fix this by exempting LINK_PROTOCOL packets from the sequence number check, as they should be. We also reduce (but don't completely eliminate) the risk of entering multiple synchronization states by only allowing the (logically) first SYNCH packet to initiate a synchronization state. This works independently of actual packet arrival order. Fixes: commit 6e498158a827 ("tipc: move link synch and failover to link aggregation level") Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Acked-by: Ying Xue <ying.xue@windriver.com> --- net/tipc/node.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)