Re: [PATCH net-next v6 10/12] net/mlx5e: Implement queue mgmt ops and single channel swap

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2025/6/16 7:14, Mark Bloch 写道:
> From: Saeed Mahameed <saeedm@nvidia.com>
> 
> The bulk of the work is done in mlx5e_queue_mem_alloc, where we allocate
> and create the new channel resources, similar to
> mlx5e_safe_switch_params, but here we do it for a single channel using
> existing params, sort of a clone channel.
> To swap the old channel with the new one, we deactivate and close the
> old channel then replace it with the new one, since the swap procedure
> doesn't fail in mlx5, we do it all in one place (mlx5e_queue_start).
> 
> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
> Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
> Signed-off-by: Mark Bloch <mbloch@nvidia.com>
> ---
>   .../net/ethernet/mellanox/mlx5/core/en_main.c | 98 +++++++++++++++++++
>   1 file changed, 98 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index a51e204bd364..873a42b4a82d 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -5494,6 +5494,103 @@ static const struct netdev_stat_ops mlx5e_stat_ops = {
>   	.get_base_stats      = mlx5e_get_base_stats,
>   };
>   
> +struct mlx5_qmgmt_data {
> +	struct mlx5e_channel *c;
> +	struct mlx5e_channel_param cparam;
> +};
> +
> +static int mlx5e_queue_mem_alloc(struct net_device *dev, void *newq,
> +				 int queue_index)
> +{
> +	struct mlx5_qmgmt_data *new = (struct mlx5_qmgmt_data *)newq;
> +	struct mlx5e_priv *priv = netdev_priv(dev);
> +	struct mlx5e_channels *chs = &priv->channels;
> +	struct mlx5e_params params = chs->params;

RCT (Reverse Christmas Tree) ?

Yanjun.Zhu

> +	struct mlx5_core_dev *mdev;
> +	int err;
> +
> +	mutex_lock(&priv->state_lock);
> +	if (!test_bit(MLX5E_STATE_OPENED, &priv->state)) {
> +		err = -ENODEV;
> +		goto unlock;
> +	}
> +
> +	if (queue_index >= chs->num) {
> +		err = -ERANGE;
> +		goto unlock;
> +	}
> +
> +	if (MLX5E_GET_PFLAG(&chs->params, MLX5E_PFLAG_TX_PORT_TS) ||
> +	    chs->params.ptp_rx   ||
> +	    chs->params.xdp_prog ||
> +	    priv->htb) {
> +		netdev_err(priv->netdev,
> +			   "Cloning channels with Port/rx PTP, XDP or HTB is not supported\n");
> +		err = -EOPNOTSUPP;
> +		goto unlock;
> +	}
> +
> +	mdev = mlx5_sd_ch_ix_get_dev(priv->mdev, queue_index);
> +	err = mlx5e_build_channel_param(mdev, &params, &new->cparam);
> +	if (err)
> +		goto unlock;
> +
> +	err = mlx5e_open_channel(priv, queue_index, &params, NULL, &new->c);
> +unlock:
> +	mutex_unlock(&priv->state_lock);
> +	return err;
> +}
> +
> +static void mlx5e_queue_mem_free(struct net_device *dev, void *mem)
> +{
> +	struct mlx5_qmgmt_data *data = (struct mlx5_qmgmt_data *)mem;
> +
> +	/* not supposed to happen since mlx5e_queue_start never fails
> +	 * but this is how this should be implemented just in case
> +	 */
> +	if (data->c)
> +		mlx5e_close_channel(data->c);
> +}
> +
> +static int mlx5e_queue_stop(struct net_device *dev, void *oldq, int queue_index)
> +{
> +	/* In mlx5 a txq cannot be simply stopped in isolation, only restarted.
> +	 * mlx5e_queue_start does not fail, we stop the old queue there.
> +	 * TODO: Improve this.
> +	 */
> +	return 0;
> +}
> +
> +static int mlx5e_queue_start(struct net_device *dev, void *newq,
> +			     int queue_index)
> +{
> +	struct mlx5_qmgmt_data *new = (struct mlx5_qmgmt_data *)newq;
> +	struct mlx5e_priv *priv = netdev_priv(dev);
> +	struct mlx5e_channel *old;
> +
> +	mutex_lock(&priv->state_lock);
> +
> +	/* stop and close the old */
> +	old = priv->channels.c[queue_index];
> +	mlx5e_deactivate_priv_channels(priv);
> +	/* close old before activating new, to avoid napi conflict */
> +	mlx5e_close_channel(old);
> +
> +	/* start the new */
> +	priv->channels.c[queue_index] = new->c;
> +	mlx5e_activate_priv_channels(priv);
> +	mutex_unlock(&priv->state_lock);
> +	return 0;
> +}
> +
> +static const struct netdev_queue_mgmt_ops mlx5e_queue_mgmt_ops = {
> +	.ndo_queue_mem_size	=	sizeof(struct mlx5_qmgmt_data),
> +	.ndo_queue_mem_alloc	=	mlx5e_queue_mem_alloc,
> +	.ndo_queue_mem_free	=	mlx5e_queue_mem_free,
> +	.ndo_queue_start	=	mlx5e_queue_start,
> +	.ndo_queue_stop		=	mlx5e_queue_stop,
> +};
> +
>   static void mlx5e_build_nic_netdev(struct net_device *netdev)
>   {
>   	struct mlx5e_priv *priv = netdev_priv(netdev);
> @@ -5504,6 +5601,7 @@ static void mlx5e_build_nic_netdev(struct net_device *netdev)
>   	SET_NETDEV_DEV(netdev, mdev->device);
>   
>   	netdev->netdev_ops = &mlx5e_netdev_ops;
> +	netdev->queue_mgmt_ops = &mlx5e_queue_mgmt_ops;
>   	netdev->xdp_metadata_ops = &mlx5e_xdp_metadata_ops;
>   	netdev->xsk_tx_metadata_ops = &mlx5e_xsk_tx_metadata_ops;
>   	netdev->request_ops_lock = true;