diff --git a/drivers/infiniband/hw/mlx4/mcg.c b/drivers/infiniband/hw/mlx4/mcg.c
index ed327e6..a0559a8 100644
--- a/drivers/infiniband/hw/mlx4/mcg.c
+++ b/drivers/infiniband/hw/mlx4/mcg.c
@@ -206,15 +206,16 @@
 {
 	struct mlx4_ib_dev *dev = ctx->dev;
 	struct ib_ah_attr	ah_attr;
+	unsigned long flags;
 
-	spin_lock(&dev->sm_lock);
+	spin_lock_irqsave(&dev->sm_lock, flags);
 	if (!dev->sm_ah[ctx->port - 1]) {
 		/* port is not yet Active, sm_ah not ready */
-		spin_unlock(&dev->sm_lock);
+		spin_unlock_irqrestore(&dev->sm_lock, flags);
 		return -EAGAIN;
 	}
 	mlx4_ib_query_ah(dev->sm_ah[ctx->port - 1], &ah_attr);
-	spin_unlock(&dev->sm_lock);
+	spin_unlock_irqrestore(&dev->sm_lock, flags);
 	return mlx4_ib_send_to_wire(dev, mlx4_master_func_num(dev->dev),
 				    ctx->port, IB_QPT_GSI, 0, 1, IB_QP1_QKEY,
 				    &ah_attr, NULL, mad);