IB/ipoib: replace local_irq_disable() with proper locking

In ipoib_mcast_restart_task() the netif_addr_lock() is invoked prior
local_irq_save(). netif_addr_lock() should not be invoked in interrupt disabled
section, only in BH disabled sections.
The priv->lock is always acquired with disabled interrupts. The only place
where netif_addr_lock() and priv->lock nest ist ipoib_mcast_restart_task().

Drop the local_irq_save() and acquire priv->lock with spin_lock_irq() inside
the netif_addr locked section. It's safe to do so because the caller is either
a worker function or __ipoib_ib_dev_flush() which are both calling with
interrupts enabled (and since BH is enabled here, too so
netif_addr_lock_bh() needs to be used).

Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

@@ -886,7 +886,6 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 	struct netdev_hw_addr *ha;
 	struct ipoib_mcast *mcast, *tmcast;
 	LIST_HEAD(remove_list);
-	unsigned long flags;
 	struct ib_sa_mcmember_rec rec;
 
 	if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
@@ -898,9 +897,8 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 
 	ipoib_dbg_mcast(priv, "restarting multicast task\n");
 
-	local_irq_save(flags);
-	netif_addr_lock(dev);
-	spin_lock(&priv->lock);
+	netif_addr_lock_bh(dev);
+	spin_lock_irq(&priv->lock);
 
 	/*
 	 * Unfortunately, the networking core only gives us a list of all of
@@ -978,9 +976,8 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 		}
 	}
 
-	spin_unlock(&priv->lock);
-	netif_addr_unlock(dev);
-	local_irq_restore(flags);
+	spin_unlock_irq(&priv->lock);
+	netif_addr_unlock_bh(dev);
 
 	ipoib_mcast_remove_list(&remove_list);
 
@@ -988,9 +985,9 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 	 * Double check that we are still up
 	 */
 	if (test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) {
-		spin_lock_irqsave(&priv->lock, flags);
+		spin_lock_irq(&priv->lock);
 		__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
-		spin_unlock_irqrestore(&priv->lock, flags);
+		spin_unlock_irq(&priv->lock);
 	}
 }