[openib-general] Re: ipoib_mcast_send.patch

[Michael S. Tsirkin]

Quoting r. Roland Dreier <rdreier at cisco.com>:
> Subject: Re: ipoib_mcast_send.patch
> 
>     Michael> I agree. Do you want to fix it or should I?
> 
> If you get a chance that would be great.  I'm at the OpenIB workshop
> now so I probably can't seriously look at it until tomorrow at the
> earliest.

Here you are. The following is in ipoib_broadcast_gid.patch in svn.

---

The way priv->broadcast is initialized in ipoib_mcast_join_task() is somewhat
unsafe, since there's no lock and conceivably a send-only join could complete
before priv->broadcast is fully set up.

Signed-off-by: Michael S. Tsirkin <mst at mellanox.co.il>

Index: openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
===================================================================
--- openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c	(revision 5336)
+++ openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c	(working copy)
@@ -533,8 +533,9 @@ 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 +545,11 @@ void ipoib_mcast_join_task(void *dev_ptr
 			return;
 		}
 
-		memcpy(priv->broadcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
+		spin_lock_irq(&priv->lock);
+		priv->broadcast = broadcast;
+		memcpy(broadcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
 		       sizeof (union ib_gid));
 
-		spin_lock_irq(&priv->lock);
 		__ipoib_mcast_add(dev, priv->broadcast);
 		spin_unlock_irq(&priv->lock);
 	}

-- 
Michael S. Tsirkin
Staff Engineer, Mellanox Technologies