bridge: do not call setup_timer() multiple times

commit 9f00b2e7cf24 ("bridge: only expire the mdb entry when query is
received") added a nasty bug as an active timer can be reinitialized.

setup_timer() must be done once, no matter how many time mod_timer()
is called. br_multicast_new_group() is the right place to do this.

Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Diagnosed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 69af490cce44..4b99c9a27044 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -619,6 +619,9 @@ rehash:
         mp->br = br;
         mp->addr = *group;
 
+        setup_timer(&mp->timer, br_multicast_group_expired,
+                    (unsigned long)mp);
+
         hlist_add_head_rcu(&mp->hlist[mdb->ver], &mdb->mhash[hash]);
         mdb->size++;
 
@@ -1126,7 +1129,6 @@ static int br_ip4_multicast_query(struct net_bridge *br,
         if (!mp)
                 goto out;
 
-        setup_timer(&mp->timer, br_multicast_group_expired, (unsigned long)mp);
         mod_timer(&mp->timer, now + br->multicast_membership_interval);
         mp->timer_armed = true;
 
@@ -1204,7 +1206,6 @@ static int br_ip6_multicast_query(struct net_bridge *br,
         if (!mp)
                 goto out;
 
-        setup_timer(&mp->timer, br_multicast_group_expired, (unsigned long)mp);
         mod_timer(&mp->timer, now + br->multicast_membership_interval);
         mp->timer_armed = true;