[openib-general] Re: ipoib_mcast_send.patch

[Roland Dreier]

I started looking at IPoIB patches again.  In ipoib_mcast_send.patch,
we have:

 > --- linux-2.6.15.orig/drivers/infiniband/ulp/ipoib/ipoib_multicast.c	2006-01-23 21:24:10.000000000 +0200
 > +++ linux-2.6.15/drivers/infiniband/ulp/ipoib/ipoib_multicast.c	2006-01-23 21:25:19.000000000 +0200
 > @@ -600,6 +600,10 @@ int ipoib_mcast_start_thread(struct net_
 >  		queue_work(ipoib_workqueue, &priv->mcast_task);
 >  	mutex_unlock(&mcast_mutex);
 >  
 > +	spin_lock_irq(&priv->lock);
 > +	set_bit(IPOIB_MCAST_STARTED, &priv->flags);
 > +	spin_unlock_irq(&priv->lock);

This seems to leave a window where we set the IPOIB_MCAST_STARTED flag
but the multicast work hasn't run yet.  Then it seems we're still
susceptible to the issue you described here:

 > Further, there's an additional issue that I saw in testing:
 > ipoib_mcast_send may get called when priv->broadcast is NULL
 > (e.g. if the device was downed and then upped internally because
 > of a port event).
 > If this happends and the sendonly join request gets completed before
 > priv->broadcast is set, we get an oops

 - R.