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

[Joe Damato <jdamato@fastly.com>]

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@fastly.com> 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 ?

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.