[openib-general] Re: ipoib_mcast_send.patch

[Roland Dreier]

I think we might want to be even more paranoid and wait until the
broadcast join succeeds before allowing send-only joins.  Otherwise
we could create a send-only MCG with the wrong Q_Key, SL, etc.

something like this maybe?

--- infiniband/ulp/ipoib/ipoib_multicast.c	(revision 5337)
+++ infiniband/ulp/ipoib/ipoib_multicast.c	(working copy)
@@ -222,6 +222,13 @@ static int ipoib_mcast_join_finish(struc
 		    sizeof (union ib_gid))) {
 		priv->qkey = be32_to_cpu(priv->broadcast->mcmember.qkey);
 		priv->tx_wr.wr.ud.remote_qkey = priv->qkey;
+
+		/*
+		 * Make sure that all the attributes are visible
+		 * before we set the attached bit, so that send-only
+		 * joins don't get started with incorrect attributes.
+		 */
+		smp_wmb();
 	}
 
 	if (!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)) {
@@ -533,8 +540,10 @@ void ipoib_mcast_join_task(void *dev_ptr
 	}
 
 	if (!priv->broadcast) {
-		priv->broadcast = ipoib_mcast_alloc(dev, 1);
-		if (!priv->broadcast) {
+		struct ipoib_mcast *broadcast;
+
+		broadcast = ipoib_mcast_alloc(dev, 1);
+		if (!broadcast) {
 			ipoib_warn(priv, "failed to allocate broadcast group\n");
 			mutex_lock(&mcast_mutex);
 			if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
@@ -544,10 +553,11 @@ void ipoib_mcast_join_task(void *dev_ptr
 			return;
 		}
 
-		memcpy(priv->broadcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
+		spin_lock_irq(&priv->lock);
+		memcpy(broadcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
 		       sizeof (union ib_gid));
+		priv->broadcast = broadcast;
 
-		spin_lock_irq(&priv->lock);
 		__ipoib_mcast_add(dev, priv->broadcast);
 		spin_unlock_irq(&priv->lock);
 	}