net/mlx5: Notify on trap action by blocking event

In order to allow mlx5 core driver to trigger synchronous operations to
its consumers, add a blocking events handler. Add wrappers to
blocking_notifier_[call_chain/chain_register/chain_unregister]. Add trap
callback for action set and notify about this change. Following patches
in the set add a listener for this event.

Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: ayalevin

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

@@ -218,6 +218,41 @@ static void mlx5_devlink_trap_fini(struct devlink *devlink, const struct devlink
 	kfree(dl_trap);
 }
 
+static int mlx5_devlink_trap_action_set(struct devlink *devlink,
+					const struct devlink_trap *trap,
+					enum devlink_trap_action action,
+					struct netlink_ext_ack *extack)
+{
+	struct mlx5_core_dev *dev = devlink_priv(devlink);
+	enum devlink_trap_action action_orig;
+	struct mlx5_devlink_trap *dl_trap;
+	int err = 0;
+
+	dl_trap = mlx5_find_trap_by_id(dev, trap->id);
+	if (!dl_trap) {
+		mlx5_core_err(dev, "Devlink trap: Set action on invalid trap id 0x%x", trap->id);
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (action != DEVLINK_TRAP_ACTION_DROP && action != DEVLINK_TRAP_ACTION_TRAP) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (action == dl_trap->trap.action)
+		goto out;
+
+	action_orig = dl_trap->trap.action;
+	dl_trap->trap.action = action;
+	err = mlx5_blocking_notifier_call_chain(dev, MLX5_DRIVER_EVENT_TYPE_TRAP,
+						&dl_trap->trap);
+	if (err)
+		dl_trap->trap.action = action_orig;
+out:
+	return err;
+}
+
 static const struct devlink_ops mlx5_devlink_ops = {
 #ifdef CONFIG_MLX5_ESWITCH
 	.eswitch_mode_set = mlx5_devlink_eswitch_mode_set,
@@ -238,6 +273,7 @@ static const struct devlink_ops mlx5_devlink_ops = {
 	.reload_up = mlx5_devlink_reload_up,
 	.trap_init = mlx5_devlink_trap_init,
 	.trap_fini = mlx5_devlink_trap_fini,
+	.trap_action_set = mlx5_devlink_trap_action_set,
 };
 
 void mlx5_devlink_trap_report(struct mlx5_core_dev *dev, int trap_id, struct sk_buff *skb,

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

@@ -61,6 +61,8 @@ struct mlx5_events {
 	struct mlx5_pme_stats pme_stats;
 	/*pcie_core*/
 	struct work_struct pcie_core_work;
+	/* driver notifier chain for sw events */
+	struct blocking_notifier_head sw_nh;
 };
 
 static const char *eqe_type_str(u8 type)
@@ -351,6 +353,7 @@ int mlx5_events_init(struct mlx5_core_dev *dev)
 		return -ENOMEM;
 	}
 	INIT_WORK(&events->pcie_core_work, mlx5_pcie_event);
+	BLOCKING_INIT_NOTIFIER_HEAD(&events->sw_nh);
 
 	return 0;
 }
@@ -406,3 +409,28 @@ int mlx5_notifier_call_chain(struct mlx5_events *events, unsigned int event, voi
 {
 	return atomic_notifier_call_chain(&events->fw_nh, event, data);
 }
+
+/* This API is used only for processing and forwarding driver-specific
+ * events to mlx5 consumers.
+ */
+int mlx5_blocking_notifier_register(struct mlx5_core_dev *dev, struct notifier_block *nb)
+{
+	struct mlx5_events *events = dev->priv.events;
+
+	return blocking_notifier_chain_register(&events->sw_nh, nb);
+}
+
+int mlx5_blocking_notifier_unregister(struct mlx5_core_dev *dev, struct notifier_block *nb)
+{
+	struct mlx5_events *events = dev->priv.events;
+
+	return blocking_notifier_chain_unregister(&events->sw_nh, nb);
+}
+
+int mlx5_blocking_notifier_call_chain(struct mlx5_core_dev *dev, unsigned int event,
+				      void *data)
+{
+	struct mlx5_events *events = dev->priv.events;
+
+	return blocking_notifier_call_chain(&events->sw_nh, event, data);
+}

include/linux/mlx5/device.h

@@ -359,6 +359,10 @@ enum mlx5_event {
 	MLX5_EVENT_TYPE_MAX                = 0x100,
 };
 
+enum mlx5_driver_event {
+	MLX5_DRIVER_EVENT_TYPE_TRAP = 0,
+};
+
 enum {
 	MLX5_TRACER_SUBTYPE_OWNERSHIP_CHANGE = 0x0,
 	MLX5_TRACER_SUBTYPE_TRACES_AVAILABLE = 0x1,

include/linux/mlx5/driver.h

@@ -1073,11 +1073,26 @@ enum {
 	MAX_MR_CACHE_ENTRIES
 };
 
+/* Async-atomic event notifier used by mlx5 core to forward FW
+ * evetns recived from event queue to mlx5 consumers.
+ * Optimise event queue dipatching.
+ */
 int mlx5_notifier_register(struct mlx5_core_dev *dev, struct notifier_block *nb);
 int mlx5_notifier_unregister(struct mlx5_core_dev *dev, struct notifier_block *nb);
+
+/* Async-atomic event notifier used for forwarding
+ * evetns from the event queue into the to mlx5 events dispatcher,
+ * eswitch, clock and others.
+ */
 int mlx5_eq_notifier_register(struct mlx5_core_dev *dev, struct mlx5_nb *nb);
 int mlx5_eq_notifier_unregister(struct mlx5_core_dev *dev, struct mlx5_nb *nb);
 
+/* Blocking event notifier used to forward SW events, used for slow path */
+int mlx5_blocking_notifier_register(struct mlx5_core_dev *dev, struct notifier_block *nb);
+int mlx5_blocking_notifier_unregister(struct mlx5_core_dev *dev, struct notifier_block *nb);
+int mlx5_blocking_notifier_call_chain(struct mlx5_core_dev *dev, unsigned int event,
+				      void *data);
+
 int mlx5_core_query_vendor_id(struct mlx5_core_dev *mdev, u32 *vendor_id);
 
 int mlx5_cmd_create_vport_lag(struct mlx5_core_dev *dev);