IPoIB: Don't turn on carrier for a non-active port

Multicast joins can succeed even if the IB port is down.  This happens
when the SM runs on the same port with the requesting port.  However,
IPoIB calls netif_carrier_on() when the join of the broadcast group
succeeds, without caring about the state of the IB port.  The result
is an IPoIB interface in RUNNING state but without an active IB port
to support it.

If a bonding interface uses this IPoIB interface as a slave it might
not detect that this slave is almost useless and failover
functionality will be damaged.  The fix checks the state of the IB
port in the carrier_task before calling netif_carrier_on().

Adresses: https://bugs.openfabrics.org/show_bug.cgi?id=1726
Signed-off-by: Moni Shoua <monis@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

@@ -362,12 +362,19 @@ void ipoib_mcast_carrier_on_task(struct work_struct *work)
 {
 	struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,
 						   carrier_on_task);
+	struct ib_port_attr attr;
 
 	/*
 	 * Take rtnl_lock to avoid racing with ipoib_stop() and
 	 * turning the carrier back on while a device is being
 	 * removed.
 	 */
+	if (ib_query_port(priv->ca, priv->port, &attr) ||
+	    attr.state != IB_PORT_ACTIVE) {
+		ipoib_dbg(priv, "Keeping carrier off until IB port is active\n");
+		return;
+	}
+
 	rtnl_lock();
 	netif_carrier_on(priv->dev);
 	rtnl_unlock();