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IPoIB: Don't drop multicast sends when they can be queued 

When set_multicast_list() is called the multicast task is restarted
and the IPOIB_MCAST_STARTED bit is cleared.  As a result for some
window of time, multicast packets are not transmitted nor queued but
rather dropped by ipoib_mcast_send().  These dropped packets are
painful in two cases:

 - bonding fail-over which both calls set_multicast_list() on the new
   active slave and sends Gratuitous ARP through that slave.

 - IP_DROP_MEMBERSHIP code which both calls set_multicast_list() on the
   device and issues IGMP leave.

In both these cases, depending on the scheduling of the IPoIB
multicast task, the packets would be dropped.  As a result, in the
bonding case, the failover would not be detected by the peers until
their neighbour is renewed the neighbour (which takes a few tens of
seconds).  In the IGMP case, the IP router doesn't get an IGMP leave
and would only learn on that from further probes on the group (also a
delay of at least a few tens of seconds).

Fix this by allowing transmission (or queuing) depending on the
IPOIB_FLAG_OPER_UP flag instead of the IPOIB_MCAST_STARTED flag.

Signed-off-by: Olga Shern <olgas@voltaire.com>
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Or Gerlitz 2008-03-11 16:10:02 +02:00 committed by Roland Dreier
parent 450bb3875f
commit b3e2749bf3
1 changed files with 1 additions and 1 deletions
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2
drivers/infiniband/ulp/ipoib/ipoib_multicast.c
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@ -650,7 +650,7 @@ void ipoib_mcast_send(struct net_device *dev, void *mgid, struct sk_buff *skb)
*/
spin_lock(&priv->lock);
if (!test_bit(IPOIB_MCAST_STARTED, &priv->flags) ||
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags) ||
!priv->broadcast ||
!test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {
++dev->stats.tx_dropped;