[PATCH net-next 03/12] eth: mlx5: allow disabling queues when RSS contexts exist

[PATCH net-next 03/12] eth: mlx5: allow disabling queues when RSS contexts exist

[Jakub Kicinski]

Since commit 24ac7e544081 ("ethtool: use the rss context XArray
in ring deactivation safety-check") core will prevent queues from
being disabled while being used by additional RSS contexts.
The safety check is no longer necessary, and core will do a more
accurate job of only rejecting changes which can actually break
things.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: saeedm@nvidia.com
CC: tariqt@nvidia.com
CC: leon@kernel.org
CC: linux-rdma@vger.kernel.org
---
 drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index 36845872ae94..0b941482db30 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -445,7 +445,6 @@ int mlx5e_ethtool_set_channels(struct mlx5e_priv *priv,
 	unsigned int count = ch->combined_count;
 	struct mlx5e_params new_params;
 	bool arfs_enabled;
-	int rss_cnt;
 	bool opened;
 	int err = 0;
 
@@ -499,17 +498,6 @@ int mlx5e_ethtool_set_channels(struct mlx5e_priv *priv,
 		goto out;
 	}
 
-	/* Don't allow changing the number of channels if non-default RSS contexts exist,
-	 * the kernel doesn't protect against set_channels operations that break them.
-	 */
-	rss_cnt = mlx5e_rx_res_rss_cnt(priv->rx_res) - 1;
-	if (rss_cnt) {
-		err = -EINVAL;
-		netdev_err(priv->netdev, "%s: Non-default RSS contexts exist (%d), cannot change the number of channels\n",
-			   __func__, rss_cnt);
-		goto out;
-	}
-
 	/* Don't allow changing the number of channels if MQPRIO mode channel offload is active,
 	 * because it defines a partition over the channels queues.
 	 */
-- 
2.45.2

Re: [PATCH net-next 03/12] eth: mlx5: allow disabling queues when RSS contexts exist

[Joe Damato]

On Thu, Aug 01, 2024 at 05:17:52PM -0700, Jakub Kicinski wrote:
> Since commit 24ac7e544081 ("ethtool: use the rss context XArray
> in ring deactivation safety-check") core will prevent queues from
> being disabled while being used by additional RSS contexts.
> The safety check is no longer necessary, and core will do a more
> accurate job of only rejecting changes which can actually break
> things.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: saeedm@nvidia.com
> CC: tariqt@nvidia.com
> CC: leon@kernel.org
> CC: linux-rdma@vger.kernel.org
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c | 12 ------------
>  1 file changed, 12 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> index 36845872ae94..0b941482db30 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> @@ -445,7 +445,6 @@ int mlx5e_ethtool_set_channels(struct mlx5e_priv *priv,
>  	unsigned int count = ch->combined_count;
>  	struct mlx5e_params new_params;
>  	bool arfs_enabled;
> -	int rss_cnt;
>  	bool opened;
>  	int err = 0;
>  
> @@ -499,17 +498,6 @@ int mlx5e_ethtool_set_channels(struct mlx5e_priv *priv,
>  		goto out;
>  	}
>  
> -	/* Don't allow changing the number of channels if non-default RSS contexts exist,
> -	 * the kernel doesn't protect against set_channels operations that break them.
> -	 */
> -	rss_cnt = mlx5e_rx_res_rss_cnt(priv->rx_res) - 1;
> -	if (rss_cnt) {
> -		err = -EINVAL;
> -		netdev_err(priv->netdev, "%s: Non-default RSS contexts exist (%d), cannot change the number of channels\n",
> -			   __func__, rss_cnt);
> -		goto out;
> -	}
> -
>  	/* Don't allow changing the number of channels if MQPRIO mode channel offload is active,
>  	 * because it defines a partition over the channels queues.
>  	 */
> -- 
> 2.45.2

Reviewed-by: Joe Damato <jdamato@fastly.com>