[PATCH net-next 1/5] net/mlx5: Rework esw qos domain init and cleanup

[Tariq Toukan <tariqt@nvidia.com>]

From: Cosmin Ratiu <cratiu@nvidia.com>

The first approach was flawed, because there are situations where the
esw mode change fails, leaving the qos domain as NULL. Various calls
into the QoS infra then trigger a NULL pointer access and unhappiness.

Improve that by a combination of:
- Allocating the QoS domain on esw init and cleaning it up on teardown.
- Refactoring mode change to only call qos domain init but not cleanup.
- Making qos domain init idempotent - not change anything if nothing
  needs changing.

Together, these should guarantee that, as long as the memory allocations
succeed, there should always be a valid qos domain until the esw
cleanup, no matter what mode changes happen (or failures thereof).

Fixes: 107a034d5c1e ("net/mlx5: qos: Store rate groups in a qos domain")
Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/esw/qos.c    |  3 +++
 .../net/ethernet/mellanox/mlx5/core/eswitch.c    | 16 +++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c b/drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c
index 7e7f99b38a37..940e1c2d1e39 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/esw/qos.c
@@ -951,6 +951,9 @@ static int esw_qos_devlink_rate_to_mbps(struct mlx5_core_dev *mdev, const char *
 
 int mlx5_esw_qos_init(struct mlx5_eswitch *esw)
 {
+	if (esw->qos.domain)
+		return 0;  /* Nothing to change. */
+
 	return esw_qos_domain_init(esw);
 }
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
index 09719e9b8611..cead41ddbc38 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
@@ -1485,7 +1485,7 @@ int mlx5_eswitch_enable_locked(struct mlx5_eswitch *esw, int num_vfs)
 
 	err = mlx5_esw_qos_init(esw);
 	if (err)
-		goto err_qos_init;
+		goto err_esw_init;
 
 	if (esw->mode == MLX5_ESWITCH_LEGACY) {
 		err = esw_legacy_enable(esw);
@@ -1495,7 +1495,7 @@ int mlx5_eswitch_enable_locked(struct mlx5_eswitch *esw, int num_vfs)
 	}
 
 	if (err)
-		goto err_esw_enable;
+		goto err_esw_init;
 
 	esw->fdb_table.flags |= MLX5_ESW_FDB_CREATED;
 
@@ -1509,9 +1509,7 @@ int mlx5_eswitch_enable_locked(struct mlx5_eswitch *esw, int num_vfs)
 
 	return 0;
 
-err_esw_enable:
-	mlx5_esw_qos_cleanup(esw);
-err_qos_init:
+err_esw_init:
 	mlx5_eq_notifier_unregister(esw->dev, &esw->nb);
 	mlx5_esw_acls_ns_cleanup(esw);
 	return err;
@@ -1640,7 +1638,6 @@ void mlx5_eswitch_disable_locked(struct mlx5_eswitch *esw)
 
 	if (esw->mode == MLX5_ESWITCH_OFFLOADS)
 		devl_rate_nodes_destroy(devlink);
-	mlx5_esw_qos_cleanup(esw);
 }
 
 void mlx5_eswitch_disable(struct mlx5_eswitch *esw)
@@ -1884,6 +1881,11 @@ int mlx5_eswitch_init(struct mlx5_core_dev *dev)
 	if (err)
 		goto reps_err;
 
+	esw->mode = MLX5_ESWITCH_LEGACY;
+	err = mlx5_esw_qos_init(esw);
+	if (err)
+		goto reps_err;
+
 	mutex_init(&esw->offloads.encap_tbl_lock);
 	hash_init(esw->offloads.encap_tbl);
 	mutex_init(&esw->offloads.decap_tbl_lock);
@@ -1897,7 +1899,6 @@ int mlx5_eswitch_init(struct mlx5_core_dev *dev)
 	refcount_set(&esw->qos.refcnt, 0);
 
 	esw->enabled_vports = 0;
-	esw->mode = MLX5_ESWITCH_LEGACY;
 	esw->offloads.inline_mode = MLX5_INLINE_MODE_NONE;
 	if (MLX5_CAP_ESW_FLOWTABLE_FDB(dev, reformat) &&
 	    MLX5_CAP_ESW_FLOWTABLE_FDB(dev, decap))
@@ -1934,6 +1935,7 @@ void mlx5_eswitch_cleanup(struct mlx5_eswitch *esw)
 
 	esw_info(esw->dev, "cleanup\n");
 
+	mlx5_esw_qos_cleanup(esw);
 	destroy_workqueue(esw->work_queue);
 	WARN_ON(refcount_read(&esw->qos.refcnt));
 	mutex_destroy(&esw->state_lock);
-- 
2.44.0