IPoIB: Retry failed send-only multicast group joins

When a send-only multicast group join fails, mcast->query must be set
to NULL.  Otherwise, IPoIB will never retry the join and the multicast
group will never be reachable.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

@@ -326,6 +326,7 @@ ipoib_mcast_sendonly_join_complete(int status,
 
 		/* Clear the busy flag so we try again */
 		clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+		mcast->query = NULL;
 	}
 
 	complete(&mcast->done);