Date: Tue, 19 Sep 2023 23:35:44 -0700
From: Saeed Mahameed <saeed@...nel.org>
To: "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>
Cc: Saeed Mahameed <saeedm@...dia.com>,
	netdev@...r.kernel.org,
	Tariq Toukan <tariqt@...dia.com>,
	Jiri Pirko <jiri@...dia.com>,
	Shay Drory <shayd@...dia.com>
Subject: [net-next 07/15] net/mlx5: Remove SF table reference counting

From: Jiri Pirko <jiri@...dia.com>

Historically, the SF table reference counting was present in order to
protect parallel executions of devlink ops. However, since currently
this is protected with devlink instance lock, the SF table reference
counting is no longer needed. Remove it entirely.

Signed-off-by: Jiri Pirko <jiri@...dia.com>
Reviewed-by: Shay Drory <shayd@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 .../ethernet/mellanox/mlx5/core/sf/devlink.c  | 120 ++++--------------
 1 file changed, 23 insertions(+), 97 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/sf/devlink.c b/drivers/net/ethernet/mellanox/mlx5/core/sf/devlink.c
index c8a043b2a8e0..6c11e075cab0 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/sf/devlink.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/sf/devlink.c
@@ -30,8 +30,6 @@ static void *mlx5_sf_by_dl_port(struct devlink_port *dl_port)
 struct mlx5_sf_table {
 	struct mlx5_core_dev *dev; /* To refer from notifier context. */
 	struct xarray function_ids; /* function id based lookup. */
-	refcount_t refcount;
-	struct completion disable_complete;
 	struct mutex sf_state_lock; /* Serializes sf state among user cmds & vhca event handler. */
 	struct notifier_block esw_nb;
 	struct notifier_block vhca_nb;
@@ -111,22 +109,6 @@ static void mlx5_sf_free(struct mlx5_sf_table *table, struct mlx5_sf *sf)
 	kfree(sf);
 }
 
-static struct mlx5_sf_table *mlx5_sf_table_try_get(struct mlx5_core_dev *dev)
-{
-	struct mlx5_sf_table *table = dev->priv.sf_table;
-
-	if (!table)
-		return NULL;
-
-	return refcount_inc_not_zero(&table->refcount) ? table : NULL;
-}
-
-static void mlx5_sf_table_put(struct mlx5_sf_table *table)
-{
-	if (refcount_dec_and_test(&table->refcount))
-		complete(&table->disable_complete);
-}
-
 static enum devlink_port_fn_state mlx5_sf_to_devlink_state(u8 hw_state)
 {
 	switch (hw_state) {
@@ -166,18 +148,13 @@ int mlx5_devlink_sf_port_fn_state_get(struct devlink_port *dl_port,
 				      struct netlink_ext_ack *extack)
 {
 	struct mlx5_core_dev *dev = devlink_priv(dl_port->devlink);
+	struct mlx5_sf_table *table = dev->priv.sf_table;
 	struct mlx5_sf *sf = mlx5_sf_by_dl_port(dl_port);
-	struct mlx5_sf_table *table;
-
-	table = mlx5_sf_table_try_get(dev);
-	if (!table)
-		return -EOPNOTSUPP;
 
 	mutex_lock(&table->sf_state_lock);
 	*state = mlx5_sf_to_devlink_state(sf->hw_state);
 	*opstate = mlx5_sf_to_devlink_opstate(sf->hw_state);
 	mutex_unlock(&table->sf_state_lock);
-	mlx5_sf_table_put(table);
 	return 0;
 }
 
@@ -244,19 +221,10 @@ int mlx5_devlink_sf_port_fn_state_set(struct devlink_port *dl_port,
 				      struct netlink_ext_ack *extack)
 {
 	struct mlx5_core_dev *dev = devlink_priv(dl_port->devlink);
+	struct mlx5_sf_table *table = dev->priv.sf_table;
 	struct mlx5_sf *sf = mlx5_sf_by_dl_port(dl_port);
-	struct mlx5_sf_table *table;
-	int err;
 
-	table = mlx5_sf_table_try_get(dev);
-	if (!table) {
-		NL_SET_ERR_MSG_MOD(extack,
-				   "Port state set is only supported in eswitch switchdev mode or SF ports are disabled.");
-		return -EOPNOTSUPP;
-	}
-	err = mlx5_sf_state_set(dev, table, sf, state, extack);
-	mlx5_sf_table_put(table);
-	return err;
+	return mlx5_sf_state_set(dev, table, sf, state, extack);
 }
 
 static int mlx5_sf_add(struct mlx5_core_dev *dev, struct mlx5_sf_table *table,
@@ -315,28 +283,37 @@ mlx5_sf_new_check_attr(struct mlx5_core_dev *dev, const struct devlink_port_new_
 	return 0;
 }
 
+static bool mlx5_sf_table_supported(const struct mlx5_core_dev *dev)
+{
+	return dev->priv.eswitch && MLX5_ESWITCH_MANAGER(dev) &&
+	       mlx5_sf_hw_table_supported(dev);
+}
+
 int mlx5_devlink_sf_port_new(struct devlink *devlink,
 			     const struct devlink_port_new_attrs *new_attr,
 			     struct netlink_ext_ack *extack,
 			     struct devlink_port **dl_port)
 {
 	struct mlx5_core_dev *dev = devlink_priv(devlink);
-	struct mlx5_sf_table *table;
+	struct mlx5_sf_table *table = dev->priv.sf_table;
 	int err;
 
 	err = mlx5_sf_new_check_attr(dev, new_attr, extack);
 	if (err)
 		return err;
 
-	table = mlx5_sf_table_try_get(dev);
-	if (!table) {
+	if (!mlx5_sf_table_supported(dev)) {
+		NL_SET_ERR_MSG_MOD(extack, "SF ports are not supported.");
+		return -EOPNOTSUPP;
+	}
+
+	if (!is_mdev_switchdev_mode(dev)) {
 		NL_SET_ERR_MSG_MOD(extack,
-				   "Port add is only supported in eswitch switchdev mode or SF ports are disabled.");
+				   "SF ports are only supported in eswitch switchdev mode.");
 		return -EOPNOTSUPP;
 	}
-	err = mlx5_sf_add(dev, table, new_attr, extack, dl_port);
-	mlx5_sf_table_put(table);
-	return err;
+
+	return mlx5_sf_add(dev, table, new_attr, extack, dl_port);
 }
 
 static void mlx5_sf_dealloc(struct mlx5_sf_table *table, struct mlx5_sf *sf)
@@ -377,18 +354,10 @@ int mlx5_devlink_sf_port_del(struct devlink *devlink,
 			     struct netlink_ext_ack *extack)
 {
 	struct mlx5_core_dev *dev = devlink_priv(devlink);
+	struct mlx5_sf_table *table = dev->priv.sf_table;
 	struct mlx5_sf *sf = mlx5_sf_by_dl_port(dl_port);
-	struct mlx5_sf_table *table;
-
-	table = mlx5_sf_table_try_get(dev);
-	if (!table) {
-		NL_SET_ERR_MSG_MOD(extack,
-				   "Port del is only supported in eswitch switchdev mode or SF ports are disabled.");
-		return -EOPNOTSUPP;
-	}
 
 	mlx5_sf_del(table, sf);
-	mlx5_sf_table_put(table);
 	return 0;
 }
 
@@ -414,14 +383,10 @@ static int mlx5_sf_vhca_event(struct notifier_block *nb, unsigned long opcode, v
 	bool update = false;
 	struct mlx5_sf *sf;
 
-	table = mlx5_sf_table_try_get(table->dev);
-	if (!table)
-		return 0;
-
 	mutex_lock(&table->sf_state_lock);
 	sf = mlx5_sf_lookup_by_function_id(table, event->function_id);
 	if (!sf)
-		goto sf_err;
+		goto unlock;
 
 	/* When driver is attached or detached to a function, an event
 	 * notifies such state change.
@@ -431,55 +396,28 @@ static int mlx5_sf_vhca_event(struct notifier_block *nb, unsigned long opcode, v
 		sf->hw_state = event->new_vhca_state;
 	trace_mlx5_sf_update_state(table->dev, sf->port_index, sf->controller,
 				   sf->hw_fn_id, sf->hw_state);
-sf_err:
+unlock:
 	mutex_unlock(&table->sf_state_lock);
-	mlx5_sf_table_put(table);
 	return 0;
 }
 
-static void mlx5_sf_table_enable(struct mlx5_sf_table *table)
-{
-	init_completion(&table->disable_complete);
-	refcount_set(&table->refcount, 1);
-}
-
 static void mlx5_sf_del_all(struct mlx5_sf_table *table)
 {
 	unsigned long index;
 	struct mlx5_sf *sf;
 
-	/* At this point, no new user commands can start and no vhca event can
-	 * arrive. It is safe to destroy all user created SFs.
-	 */
 	xa_for_each(&table->function_ids, index, sf)
 		mlx5_sf_del(table, sf);
 }
 
-static void mlx5_sf_table_disable(struct mlx5_sf_table *table)
-{
-	if (!refcount_read(&table->refcount))
-		return;
-
-	/* Balances with refcount_set; drop the reference so that new user cmd cannot start
-	 * and new vhca event handler cannot run.
-	 */
-	mlx5_sf_table_put(table);
-	wait_for_completion(&table->disable_complete);
-
-	mlx5_sf_del_all(table);
-}
-
 static int mlx5_sf_esw_event(struct notifier_block *nb, unsigned long event, void *data)
 {
 	struct mlx5_sf_table *table = container_of(nb, struct mlx5_sf_table, esw_nb);
 	const struct mlx5_esw_event_info *mode = data;
 
 	switch (mode->new_mode) {
-	case MLX5_ESWITCH_OFFLOADS:
-		mlx5_sf_table_enable(table);
-		break;
 	case MLX5_ESWITCH_LEGACY:
-		mlx5_sf_table_disable(table);
+		mlx5_sf_del_all(table);
 		break;
 	default:
 		break;
@@ -498,9 +436,6 @@ static int mlx5_sf_mdev_event(struct notifier_block *nb, unsigned long event, vo
 	if (event != MLX5_DRIVER_EVENT_SF_PEER_DEVLINK)
 		return NOTIFY_DONE;
 
-	table = mlx5_sf_table_try_get(table->dev);
-	if (!table)
-		return NOTIFY_DONE;
 
 	mutex_lock(&table->sf_state_lock);
 	sf = mlx5_sf_lookup_by_function_id(table, event_ctx->fn_id);
@@ -513,16 +448,9 @@ static int mlx5_sf_mdev_event(struct notifier_block *nb, unsigned long event, vo
 	ret = NOTIFY_OK;
 out:
 	mutex_unlock(&table->sf_state_lock);
-	mlx5_sf_table_put(table);
 	return ret;
 }
 
-static bool mlx5_sf_table_supported(const struct mlx5_core_dev *dev)
-{
-	return dev->priv.eswitch && MLX5_ESWITCH_MANAGER(dev) &&
-	       mlx5_sf_hw_table_supported(dev);
-}
-
 int mlx5_sf_table_init(struct mlx5_core_dev *dev)
 {
 	struct mlx5_sf_table *table;
@@ -539,7 +467,6 @@ int mlx5_sf_table_init(struct mlx5_core_dev *dev)
 	table->dev = dev;
 	xa_init(&table->function_ids);
 	dev->priv.sf_table = table;
-	refcount_set(&table->refcount, 0);
 	table->esw_nb.notifier_call = mlx5_sf_esw_event;
 	err = mlx5_esw_event_notifier_register(dev->priv.eswitch, &table->esw_nb);
 	if (err)
@@ -574,7 +501,6 @@ void mlx5_sf_table_cleanup(struct mlx5_core_dev *dev)
 	mlx5_blocking_notifier_unregister(dev, &table->mdev_nb);
 	mlx5_vhca_event_notifier_unregister(table->dev, &table->vhca_nb);
 	mlx5_esw_event_notifier_unregister(dev->priv.eswitch, &table->esw_nb);
-	WARN_ON(refcount_read(&table->refcount));
 	mutex_destroy(&table->sf_state_lock);
 	WARN_ON(!xa_empty(&table->function_ids));
 	kfree(table);
-- 
2.41.0

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