IB/mlx4: Fix spinlock order to avoid lockdep warnings

lockdep warns about taking a hard-irq-unsafe lock (sriov->id_map_lock)
inside a hard-irq-safe lock (sriov->going_down_lock).

Since id_map_lock is never taken in the interrupt context, we can
simply reverse the order of taking the two spinlocks, thus avoiding
the warning and the depencency.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/mlx4/cm.c

@@ -268,15 +268,15 @@ static void schedule_delayed(struct ib_device *ibdev, struct id_map_entry *id)
 	struct mlx4_ib_sriov *sriov = &to_mdev(ibdev)->sriov;
 	unsigned long flags;
 
-	spin_lock_irqsave(&sriov->going_down_lock, flags);
 	spin_lock(&sriov->id_map_lock);
+	spin_lock_irqsave(&sriov->going_down_lock, flags);
 	/*make sure that there is no schedule inside the scheduled work.*/
 	if (!sriov->is_going_down) {
 		id->scheduled_delete = 1;
 		schedule_delayed_work(&id->timeout, CM_CLEANUP_CACHE_TIMEOUT);
 	}
-	spin_unlock(&sriov->id_map_lock);
 	spin_unlock_irqrestore(&sriov->going_down_lock, flags);
+	spin_unlock(&sriov->id_map_lock);
 }
 
 int mlx4_ib_multiplex_cm_handler(struct ib_device *ibdev, int port, int slave_id,