net/mlx5: Devcom, serialize devcom registration

From one hand, mlx5 driver is allowing to probe PFs in parallel.
From the other hand, devcom, which is a share resource between PFs, is
registered without any lock. This might resulted in memory problems.

Hence, use the global mlx5_dev_list_lock in order to serialize devcom
registration.

Fixes: fadd59f ("net/mlx5: Introduce inter-device communication mechanism")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c

@@ -3,6 +3,7 @@
 
 #include <linux/mlx5/vport.h>
 #include "lib/devcom.h"
+#include "mlx5_core.h"
 
 static LIST_HEAD(devcom_list);
 
@@ -77,6 +78,7 @@ struct mlx5_devcom *mlx5_devcom_register_device(struct mlx5_core_dev *dev)
 	if (MLX5_CAP_GEN(dev, num_lag_ports) != MLX5_DEVCOM_PORTS_SUPPORTED)
 		return NULL;
 
+	mlx5_dev_list_lock();
 	sguid0 = mlx5_query_nic_system_image_guid(dev);
 	list_for_each_entry(iter, &devcom_list, list) {
 		struct mlx5_core_dev *tmp_dev = NULL;
@@ -102,8 +104,10 @@ struct mlx5_devcom *mlx5_devcom_register_device(struct mlx5_core_dev *dev)
 
 	if (!priv) {
 		priv = mlx5_devcom_list_alloc();
-		if (!priv)
-			return ERR_PTR(-ENOMEM);
+		if (!priv) {
+			devcom = ERR_PTR(-ENOMEM);
+			goto out;
+		}
 
 		idx = 0;
 		new_priv = true;
@@ -114,12 +118,14 @@ struct mlx5_devcom *mlx5_devcom_register_device(struct mlx5_core_dev *dev)
 	if (!devcom) {
 		if (new_priv)
 			kfree(priv);
-		return ERR_PTR(-ENOMEM);
+		devcom = ERR_PTR(-ENOMEM);
+		goto out;
 	}
 
 	if (new_priv)
 		list_add(&priv->list, &devcom_list);
-
+out:
+	mlx5_dev_list_unlock();
 	return devcom;
 }
 
@@ -132,6 +138,7 @@ void mlx5_devcom_unregister_device(struct mlx5_devcom *devcom)
 	if (IS_ERR_OR_NULL(devcom))
 		return;
 
+	mlx5_dev_list_lock();
 	priv = devcom->priv;
 	priv->devs[devcom->idx] = NULL;
 
@@ -142,10 +149,12 @@ void mlx5_devcom_unregister_device(struct mlx5_devcom *devcom)
 			break;
 
 	if (i != MLX5_DEVCOM_PORTS_SUPPORTED)
-		return;
+		goto out;
 
 	list_del(&priv->list);
 	kfree(priv);
+out:
+	mlx5_dev_list_unlock();
 }
 
 void mlx5_devcom_register_component(struct mlx5_devcom *devcom,