net/mlx5: Check for error in mlx5_attach_interface

Currently, mlx5_attach_interface does not check for error
after calling intf->attach or intf->add. When these two calls
fails, the client is not initialized and will cause issues such as
kernel panic on invalid address in the teardown path (mlx5_detach_interface)

Fixes: 737a234 ("net/mlx5: Introduce attach/detach to interface API")
Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/dev.c

@@ -132,11 +132,11 @@ void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 	delayed_event_start(priv);
 
 	dev_ctx->context = intf->add(dev);
-	set_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
-	if (intf->attach)
-		set_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state);
-
 	if (dev_ctx->context) {
+		set_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
+		if (intf->attach)
+			set_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state);
+
 		spin_lock_irq(&priv->ctx_lock);
 		list_add_tail(&dev_ctx->list, &priv->ctx_list);
 
@@ -211,12 +211,17 @@ static void mlx5_attach_interface(struct mlx5_interface *intf, struct mlx5_priv
 	if (intf->attach) {
 		if (test_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state))
 			goto out;
-		intf->attach(dev, dev_ctx->context);
+		if (intf->attach(dev, dev_ctx->context))
+			goto out;
+
 		set_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state);
 	} else {
 		if (test_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state))
 			goto out;
 		dev_ctx->context = intf->add(dev);
+		if (!dev_ctx->context)
+			goto out;
+
 		set_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
 	}