net/mlx5: Introduce attach/detach to interface API

Add attach/detach callbacks to interface API.
This is crucial for implementing seamless reset flow which releases the
hardware and it's resources upon detach while keeping software
structures and state (e.g netdev) then reset and reallocate the hardware
needed resources upon attach.
Signed-off-by: Mohamad Haj Yahia <mohamad@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -81,6 +81,7 @@ struct mlx5_device_context {
 	struct list_head	list;
 	struct mlx5_interface  *intf;
 	void		       *context;
+	unsigned long		state;
 };
 
 enum {
@@ -778,6 +779,11 @@ static int mlx5_core_set_issi(struct mlx5_core_dev *dev)
 	return -ENOTSUPP;
 }
 
+enum {
+	MLX5_INTERFACE_ADDED,
+	MLX5_INTERFACE_ATTACHED,
+};
+
 static void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 {
 	struct mlx5_device_context *dev_ctx;
@@ -786,12 +792,15 @@ static void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 	if (!mlx5_lag_intf_add(intf, priv))
 		return;
 
-	dev_ctx = kmalloc(sizeof(*dev_ctx), GFP_KERNEL);
+	dev_ctx = kzalloc(sizeof(*dev_ctx), GFP_KERNEL);
 	if (!dev_ctx)
 		return;
 
 	dev_ctx->intf = intf;
 	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) {
 		spin_lock_irq(&priv->ctx_lock);
@@ -802,23 +811,116 @@ static void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 	}
 }
 
+static struct mlx5_device_context *mlx5_get_device(struct mlx5_interface *intf,
+						   struct mlx5_priv *priv)
+{
+	struct mlx5_device_context *dev_ctx;
+
+	list_for_each_entry(dev_ctx, &priv->ctx_list, list)
+		if (dev_ctx->intf == intf)
+			return dev_ctx;
+	return NULL;
+}
+
 static void mlx5_remove_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 {
 	struct mlx5_device_context *dev_ctx;
 	struct mlx5_core_dev *dev = container_of(priv, struct mlx5_core_dev, priv);
 
-	list_for_each_entry(dev_ctx, &priv->ctx_list, list)
-		if (dev_ctx->intf == intf) {
+	dev_ctx = mlx5_get_device(intf, priv);
+	if (!dev_ctx)
+		return;
+
 	spin_lock_irq(&priv->ctx_lock);
 	list_del(&dev_ctx->list);
 	spin_unlock_irq(&priv->ctx_lock);
 
+	if (test_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state))
 		intf->remove(dev, dev_ctx->context);
+
 	kfree(dev_ctx);
+}
+
+static void mlx5_attach_interface(struct mlx5_interface *intf, struct mlx5_priv *priv)
+{
+	struct mlx5_device_context *dev_ctx;
+	struct mlx5_core_dev *dev = container_of(priv, struct mlx5_core_dev, priv);
+
+	dev_ctx = mlx5_get_device(intf, priv);
+	if (!dev_ctx)
+		return;
+
+	if (intf->attach) {
+		if (test_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state))
+			return;
+		intf->attach(dev, dev_ctx->context);
+		set_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state);
+	} else {
+		if (test_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state))
+			return;
+		dev_ctx->context = intf->add(dev);
+		set_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
+	}
+}
+
+static void mlx5_attach_device(struct mlx5_core_dev *dev)
+{
+	struct mlx5_priv *priv = &dev->priv;
+	struct mlx5_interface *intf;
+
+	mutex_lock(&mlx5_intf_mutex);
+	list_for_each_entry(intf, &intf_list, list)
+		mlx5_attach_interface(intf, priv);
+	mutex_unlock(&mlx5_intf_mutex);
+}
+
+static void mlx5_detach_interface(struct mlx5_interface *intf, struct mlx5_priv *priv)
+{
+	struct mlx5_device_context *dev_ctx;
+	struct mlx5_core_dev *dev = container_of(priv, struct mlx5_core_dev, priv);
+
+	dev_ctx = mlx5_get_device(intf, priv);
+	if (!dev_ctx)
 		return;
+
+	if (intf->detach) {
+		if (!test_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state))
+			return;
+		intf->detach(dev, dev_ctx->context);
+		clear_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state);
+	} else {
+		if (!test_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state))
+			return;
+		intf->remove(dev, dev_ctx->context);
+		clear_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
 	}
 }
 
+static void mlx5_detach_device(struct mlx5_core_dev *dev)
+{
+	struct mlx5_priv *priv = &dev->priv;
+	struct mlx5_interface *intf;
+
+	mutex_lock(&mlx5_intf_mutex);
+	list_for_each_entry(intf, &intf_list, list)
+		mlx5_detach_interface(intf, priv);
+	mutex_unlock(&mlx5_intf_mutex);
+}
+
+static bool mlx5_device_registered(struct mlx5_core_dev *dev)
+{
+	struct mlx5_priv *priv;
+	bool found = false;
+
+	mutex_lock(&mlx5_intf_mutex);
+	list_for_each_entry(priv, &mlx5_dev_list, dev_list)
+		if (priv == &dev->priv)
+			found = true;
+	mutex_unlock(&mlx5_intf_mutex);
+
+	return found;
+}
+
 static int mlx5_register_device(struct mlx5_core_dev *dev)
 {
 	struct mlx5_priv *priv = &dev->priv;
@@ -1162,15 +1264,15 @@ static int mlx5_load_one(struct mlx5_core_dev *dev, struct mlx5_priv *priv)
 		goto err_sriov;
 	}
 
+	if (mlx5_device_registered(dev)) {
+		mlx5_attach_device(dev);
+	} else {
 		err = mlx5_register_device(dev);
 		if (err) {
 			dev_err(&pdev->dev, "mlx5_register_device failed %d\n", err);
 			goto err_reg_dev;
 		}
-
-	err = request_module_nowait(MLX5_IB_MOD);
-	if (err)
-		pr_info("failed request module on %s\n", MLX5_IB_MOD);
+	}
 
 	clear_bit(MLX5_INTERFACE_STATE_DOWN, &dev->intf_state);
 	set_bit(MLX5_INTERFACE_STATE_UP, &dev->intf_state);
@@ -1247,12 +1349,13 @@ static int mlx5_unload_one(struct mlx5_core_dev *dev, struct mlx5_priv *priv)
 		goto out;
 	}
 
+	if (mlx5_device_registered(dev))
+		mlx5_detach_device(dev);
+
 	mlx5_sriov_cleanup(dev);
-	mlx5_unregister_device(dev);
 #ifdef CONFIG_MLX5_CORE_EN
 	mlx5_eswitch_cleanup(dev->priv.eswitch);
 #endif
-
 	mlx5_cleanup_rl_table(dev);
 	mlx5_cleanup_fs(dev);
 	mlx5_cleanup_mkey_table(dev);
@@ -1364,6 +1467,9 @@ static int init_one(struct pci_dev *pdev,
 		dev_err(&pdev->dev, "mlx5_load_one failed with error code %d\n", err);
 		goto clean_health;
 	}
+	err = request_module_nowait(MLX5_IB_MOD);
+	if (err)
+		pr_info("failed request module on %s\n", MLX5_IB_MOD);
 
 	err = devlink_register(devlink, &pdev->dev);
 	if (err)
@@ -1391,11 +1497,14 @@ static void remove_one(struct pci_dev *pdev)
 	struct mlx5_priv *priv = &dev->priv;
 
 	devlink_unregister(devlink);
+	mlx5_unregister_device(dev);
+
 	if (mlx5_unload_one(dev, priv)) {
 		dev_err(&dev->pdev->dev, "mlx5_unload_one failed\n");
 		mlx5_health_cleanup(dev);
 		return;
 	}
+
 	mlx5_health_cleanup(dev);
 	mlx5_pci_close(dev, priv);
 	pci_set_drvdata(pdev, NULL);

include/linux/mlx5/driver.h

@@ -930,6 +930,8 @@ enum {
 struct mlx5_interface {
 	void *			(*add)(struct mlx5_core_dev *dev);
 	void			(*remove)(struct mlx5_core_dev *dev, void *context);
+	int			(*attach)(struct mlx5_core_dev *dev, void *context);
+	void			(*detach)(struct mlx5_core_dev *dev, void *context);
 	void			(*event)(struct mlx5_core_dev *dev, void *context,
 					 enum mlx5_dev_event event, unsigned long param);
 	void *                  (*get_dev)(void *context);