IPoIB: Always initialize poll_timer to avoid crash on unload

ipoib_ib_dev_stop() does del_timer_sync(&priv->poll_timer), but if a
P_key for an interface is not found, poll_timer is not initialized, so
this leads to a crash or hang.  Fix this by moving where poll_timer is
initialized to ipoib_ib_dev_init(), which is always called.

This fixes <https://bugs.openfabrics.org/show_bug.cgi?id=1172>.
Debugged-by: Yosef Etigin <yosefe@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/ulp/ipoib/ipoib_ib.c

@@ -685,10 +685,6 @@ int ipoib_ib_dev_open(struct net_device *dev)
 	queue_delayed_work(ipoib_workqueue, &priv->ah_reap_task,
 			   round_jiffies_relative(HZ));
 
-	init_timer(&priv->poll_timer);
-	priv->poll_timer.function = ipoib_ib_tx_timer_func;
-	priv->poll_timer.data = (unsigned long)dev;
-
 	set_bit(IPOIB_FLAG_INITIALIZED, &priv->flags);
 
 	return 0;
@@ -906,6 +902,9 @@ int ipoib_ib_dev_init(struct net_device *dev, struct ib_device *ca, int port)
 		return -ENODEV;
 	}
 
+	setup_timer(&priv->poll_timer, ipoib_ib_tx_timer_func,
+		    (unsigned long) dev);
+
 	if (dev->flags & IFF_UP) {
 		if (ipoib_ib_dev_open(dev)) {
 			ipoib_transport_dev_cleanup(dev);