[ofa-general] [PATCH v2] ipoib: do not join broadcast group if interface is brought down

[Roland Dreier]

 > @@ -587,8 +589,10 @@ void ipoib_mcast_join_task(struct work_s
 > 		__ipoib_mcast_add(dev, priv->broadcast);
 > 		spin_unlock_irq(&priv->lock);
 > 	}
 > +	rtnl_unlock();
 > 
 > -	if (!test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {
 > +	if (priv->broadcast &&
 > +	    !test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {

I'm trying to understand this patch.  What protects access to
priv->broadcast here and prevents it from becoming NULL right after the
test?

 - R.