[ofa-general] [PATCH] ipiob: fix rtnl deadlock

[Roland Dreier]

 > ipoib_stop is called with rtnl_lock, and flushes ipoib_workqueue.
 > the flush operation might wait for mcast_join_task to finish, which
 > in turn might wait for rtnl_lock.

when did we introduce this bug?

 > +		/* Avoid deadlock with ipoib_stop */
 > +		while (!(ret = rtnl_trylock()) &&
 > +		       test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
 > +			yield();
 > +
 > +		if (ret) {
 > +			dev_set_mtu(dev, min(priv->mcast_mtu, priv->admin_mtu));
 > +			rtnl_unlock();
 > +		} else
 > +			ipoib_dbg_mcast(priv, "ignoring mtu setup because device is down\n");

this is rather horrible looking... is there any way we can avoid the
loop on trylock?

 - R.