Subject: Re: [PATCH 24/33] virtio_net: xsk: stop disable tx napi

From: "Michael S. Tsirkin" <[email-masked]>
Date: Thu, 2 Feb 2023 12:25:59 -0500

On Thu, Feb 02, 2023 at 07:00:49PM +0800, Xuan Zhuo wrote:
> Since xsk's TX queue is consumed by TX NAPI, if sq is bound to xsk, then
> we must stop tx napi from being disabled.
> 
> Signed-off-by: Xuan Zhuo <[email-masked]>
> ---
>  drivers/net/virtio/main.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
> index ed79e750bc6c..232cf151abff 100644
> --- a/drivers/net/virtio/main.c
> +++ b/drivers/net/virtio/main.c
> @@ -2728,8 +2728,15 @@ static int virtnet_set_coalesce(struct net_device *dev,
>  		return ret;
>  
>  	if (update_napi) {
> -		for (i = 0; i < vi->max_queue_pairs; i++)
> +		for (i = 0; i < vi->max_queue_pairs; i++) {
> +			/* xsk xmit depend on the tx napi. So if xsk is active,

depends.

> +			 * prevent modifications to tx napi.
> +			 */
> +			if (rtnl_dereference(vi->sq[i].xsk.pool))
> +				continue;
> +
>  			vi->sq[i].napi.weight = napi_weight;

I don't get it.
changing napi weight does not work then.
why is this ok?

> +		}
>  	}
>  	return ret;
> -- 
> 2.32.0.3.g01195cf9f