IPoIB: reinitialize mcast structs' completions for every query

Make sure mcast->done is initialized to uncompleted value before we
submit a new query, so that it's safe to wait on.

Signed-off-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

···
 	if (!mcast)
 		return NULL;
 
-	init_completion(&mcast->done);
-
 	mcast->dev = dev;
 	mcast->created = jiffies;
 	mcast->backoff = 1;
···
 	rec.port_gid = priv->local_gid;
 	rec.pkey     = cpu_to_be16(priv->pkey);
 
+	init_completion(&mcast->done);
+
 	ret = ib_sa_mcmember_rec_set(priv->ca, priv->port, &rec,
 				     IB_SA_MCMEMBER_REC_MGID		|
 				     IB_SA_MCMEMBER_REC_PORT_GID	|
···
 		rec.flow_label	  = priv->broadcast->mcmember.flow_label;
 		rec.traffic_class = priv->broadcast->mcmember.traffic_class;
 	}
+
+	init_completion(&mcast->done);
 
 	ret = ib_sa_mcmember_rec_set(priv->ca, priv->port, &rec, comp_mask,
 				     mcast->backoff * 1000, GFP_ATOMIC,