Re: [PATCH net-next v5 3/4] virtio-net: Map NAPIs to queues

[Jason Wang]

On Thu, Mar 6, 2025 at 12:34 AM Joe Damato <jdamato@xxxxxxxxxx> wrote:
>
> On Wed, Mar 05, 2025 at 01:11:55PM +0800, Jason Wang wrote:
> > On Tue, Mar 4, 2025 at 11:09 PM Joe Damato <jdamato@xxxxxxxxxx> wrote:
> > >
> > > On Mon, Mar 03, 2025 at 04:03:55PM -0800, Jakub Kicinski wrote:
> > > > On Mon, 3 Mar 2025 13:33:10 -0500 Joe Damato wrote:
>
> [...]
>
> > > > Middle ground would be to do what you suggested above and just leave
> > > > a well worded comment somewhere that will show up in diffs adding queue
> > > > API support?
> > >
> > > Jason, Michael, et. al.:  what do you think ? I don't want to spin
> > > up a v6 if you are opposed to proceeding this way. Please let me
> > > know.
> > >
> >
> > Maybe, but need to make sure there's no use-after-free (etc.
> > virtnet_close() has several callers).
>
> Sorry, I think I am missing something. Can you say more?
>
> I was asking: if I add the following diff below to patch 3, will
> that be acceptable for you as a middle ground until a more idiomatic
> implementation can be done ?

Yes, I misunderstand you before.

>
> Since this diff leaves refill_work as it functioned before, it
> avoids the problem Jakub pointed out and shouldn't introduce any
> bugs since refill_work isn't changing from the original
> implementation ?
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 76dcd65ec0f2..d6c8fe670005 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2883,15 +2883,9 @@ static void refill_work(struct work_struct *work)
>         for (i = 0; i < vi->curr_queue_pairs; i++) {
>                 struct receive_queue *rq = &vi->rq[i];
>
> -               rtnl_lock();
> -               virtnet_napi_disable(rq);
> -               rtnl_unlock();
> -
> +               napi_disable(&rq->napi);
>                 still_empty = !try_fill_recv(vi, rq, GFP_KERNEL);
> -
> -               rtnl_lock();
> -               virtnet_napi_enable(rq);
> -               rtnl_unlock();
> +               virtnet_napi_do_enable(rq->vq, &rq->napi);
>
>                 /* In theory, this can happen: if we don't get any buffers in
>                  * we will *never* try to fill again.
>

Works for me.

Thanks