net/mlx5: E-Switch, Change mode lock from mutex to rw semaphore

E-Switch mode change routine will take the write lock to prevent any
consumer to access the E-Switch resources while E-Switch is going
through a mode change.

In the next patch
E-Switch consumers (e.g vport representors) will take read_lock prior to
accessing E-Switch resources to prevent E-Switch mode changing in the
middle of the operation.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -1720,7 +1720,7 @@ int mlx5_eswitch_enable(struct mlx5_eswitch *esw, int num_vfs)
 	if (!ESW_ALLOWED(esw))
 		return 0;
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	if (esw->mode == MLX5_ESWITCH_NONE) {
 		ret = mlx5_eswitch_enable_locked(esw, MLX5_ESWITCH_LEGACY, num_vfs);
 	} else {
@@ -1732,7 +1732,7 @@ int mlx5_eswitch_enable(struct mlx5_eswitch *esw, int num_vfs)
 		if (!ret)
 			esw->esw_funcs.num_vfs = num_vfs;
 	}
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return ret;
 }
 
@@ -1780,10 +1780,10 @@ void mlx5_eswitch_disable(struct mlx5_eswitch *esw, bool clear_vf)
 	if (!ESW_ALLOWED(esw))
 		return;
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	mlx5_eswitch_disable_locked(esw, clear_vf);
 	esw->esw_funcs.num_vfs = 0;
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 }
 
 int mlx5_eswitch_init(struct mlx5_core_dev *dev)
@@ -1840,7 +1840,7 @@ int mlx5_eswitch_init(struct mlx5_core_dev *dev)
 	ida_init(&esw->offloads.vport_metadata_ida);
 	xa_init_flags(&esw->offloads.vhca_map, XA_FLAGS_ALLOC);
 	mutex_init(&esw->state_lock);
-	mutex_init(&esw->mode_lock);
+	init_rwsem(&esw->mode_lock);
 
 	mlx5_esw_for_all_vports(esw, i, vport) {
 		vport->vport = mlx5_eswitch_index_to_vport_num(esw, i);
@@ -1876,7 +1876,6 @@ void mlx5_eswitch_cleanup(struct mlx5_eswitch *esw)
 	esw->dev->priv.eswitch = NULL;
 	destroy_workqueue(esw->work_queue);
 	esw_offloads_cleanup_reps(esw);
-	mutex_destroy(&esw->mode_lock);
 	mutex_destroy(&esw->state_lock);
 	WARN_ON(!xa_empty(&esw->offloads.vhca_map));
 	xa_destroy(&esw->offloads.vhca_map);

drivers/net/ethernet/mellanox/mlx5/core/eswitch.h

@@ -271,7 +271,7 @@ struct mlx5_eswitch {
 	/* Protects eswitch mode change that occurs via one or more
 	 * user commands, i.e. sriov state change, devlink commands.
 	 */
-	struct mutex mode_lock;
+	struct rw_semaphore mode_lock;
 
 	struct {
 		bool            enabled;

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

@@ -2925,7 +2925,7 @@ int mlx5_devlink_eswitch_mode_set(struct devlink *devlink, u16 mode,
 	if (esw_mode_from_devlink(mode, &mlx5_mode))
 		return -EINVAL;
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	cur_mlx5_mode = esw->mode;
 	if (cur_mlx5_mode == mlx5_mode)
 		goto unlock;
@@ -2938,7 +2938,7 @@ int mlx5_devlink_eswitch_mode_set(struct devlink *devlink, u16 mode,
 		err = -EINVAL;
 
 unlock:
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return err;
 }
 
@@ -2951,14 +2951,14 @@ int mlx5_devlink_eswitch_mode_get(struct devlink *devlink, u16 *mode)
 	if (IS_ERR(esw))
 		return PTR_ERR(esw);
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	err = eswitch_devlink_esw_mode_check(esw);
 	if (err)
 		goto unlock;
 
 	err = esw_mode_to_devlink(esw->mode, mode);
 unlock:
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return err;
 }
 
@@ -2974,7 +2974,7 @@ int mlx5_devlink_eswitch_inline_mode_set(struct devlink *devlink, u8 mode,
 	if (IS_ERR(esw))
 		return PTR_ERR(esw);
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	err = eswitch_devlink_esw_mode_check(esw);
 	if (err)
 		goto out;
@@ -3013,7 +3013,7 @@ int mlx5_devlink_eswitch_inline_mode_set(struct devlink *devlink, u8 mode,
 	}
 
 	esw->offloads.inline_mode = mlx5_mode;
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return 0;
 
 revert_inline_mode:
@@ -3023,7 +3023,7 @@ int mlx5_devlink_eswitch_inline_mode_set(struct devlink *devlink, u8 mode,
 						 vport,
 						 esw->offloads.inline_mode);
 out:
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return err;
 }
 
@@ -3036,14 +3036,14 @@ int mlx5_devlink_eswitch_inline_mode_get(struct devlink *devlink, u8 *mode)
 	if (IS_ERR(esw))
 		return PTR_ERR(esw);
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	err = eswitch_devlink_esw_mode_check(esw);
 	if (err)
 		goto unlock;
 
 	err = esw_inline_mode_to_devlink(esw->offloads.inline_mode, mode);
 unlock:
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return err;
 }
 
@@ -3059,7 +3059,7 @@ int mlx5_devlink_eswitch_encap_mode_set(struct devlink *devlink,
 	if (IS_ERR(esw))
 		return PTR_ERR(esw);
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	err = eswitch_devlink_esw_mode_check(esw);
 	if (err)
 		goto unlock;
@@ -3105,7 +3105,7 @@ int mlx5_devlink_eswitch_encap_mode_set(struct devlink *devlink,
 	}
 
 unlock:
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return err;
 }
 
@@ -3120,14 +3120,14 @@ int mlx5_devlink_eswitch_encap_mode_get(struct devlink *devlink,
 		return PTR_ERR(esw);
 
 
-	mutex_lock(&esw->mode_lock);
+	down_write(&esw->mode_lock);
 	err = eswitch_devlink_esw_mode_check(esw);
 	if (err)
 		goto unlock;
 
 	*encap = esw->offloads.encap;
 unlock:
-	mutex_unlock(&esw->mode_lock);
+	up_write(&esw->mode_lock);
 	return 0;
 }