Re: [PATCH net-next 15/15] net/mlx5: LAG, enable LAG over functions that do not represent a physical port

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] net/mlx5: LAG, empty debugfs member list in members_show() for virt_lag
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commit a1292895cfa07137f4fbbaafed6d7e85d7e486bc
Author: Shay Drory <shayd@nvidia.com>

net/mlx5: LAG, enable LAG over functions that do not represent a physical port

This commit enables LAG over virtual functions (VFs/SFs) sitting behind a
multi_uplink_eswitch that do not represent a physical port. It skips setting
MLX5_LAG_XA_MARK_PORT on these functions, avoids registering the netdev
notifier or adding netdevs, and reports at least one port in
mlx5_lag_get_num_ports().

> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
> index 4e15e16ae6e84..5532b2505161c 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c

[ ... ]

> @@ -2399,7 +2402,7 @@ int mlx5_ldev_add_mdev(struct mlx5_lag *ldev,
>  	fn->group_id = group_id;
>  	dev->priv.lag = ldev;
>  
> -	if (group_id)
> +	if (group_id || ldev->virt_lag)
>  		return 0;
>  
>  	xa_set_mark(&ldev->fns, idx, MLX5_LAG_XA_MARK_PORT);

[Severity: Medium]
When a virt_lag device is added in mlx5_lag_add_mdev(), it registers the lag
debugfs entries via mlx5_ldev_add_debugfs(), including the members file backed
by members_show().

Since mlx5_ldev_add_mdev() returns early when ldev->virt_lag is set before
marking the xarray entry with MLX5_LAG_XA_MARK_PORT, no member in ldev->fns
has the port mark. However, members_show() iterates with mlx5_ldev_for_each(),
which uses MLX5_LAG_FILTER_PORTS:

drivers/net/ethernet/mellanox/mlx5/core/lag/debugfs.c:members_show() {
	ldev = mlx5_lag_dev(dev);
	mutex_lock(&ldev->lock);
	mlx5_ldev_for_each(i, 0, ldev)
		seq_printf(file, "%s\n",
			   dev_name(mlx5_lag_fn(ldev, i)->dev->device));
	mutex_unlock(&ldev->lock);
}

Won't reading the lag/members debugfs file on a virt_lag device always
produce empty output?

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Sashiko AI review · https://sashiko.dev/#/patchset/20261103171009.563034-1-tariqt@nvidia.com?part=15