[PATCH vhost v5 2/6] virtio: remove support for names array entries being null.

[Xuan Zhuo]

On Tue, 26 Mar 2024 12:28:34 +0800, Jason Wang <jasowang at redhat.com> wrote:
> On Mon, Mar 25, 2024 at 5:04 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:
> >
> > commit 6457f126c888 ("virtio: support reserved vqs") introduced this
> > support. Multiqueue virtio-net use 2N as ctrl vq finally, so the logic
> > doesn't apply. And not one uses this.
> >
> > On the other side, that makes some trouble for us to refactor the
> > find_vqs() params.
> >
> > So I remove this support.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> > ---
> >  arch/um/drivers/virtio_uml.c             | 5 -----
> >  drivers/platform/mellanox/mlxbf-tmfifo.c | 4 ----
> >  drivers/remoteproc/remoteproc_virtio.c   | 5 -----
> >  drivers/s390/virtio/virtio_ccw.c         | 5 -----
> >  drivers/virtio/virtio_mmio.c             | 5 -----
> >  drivers/virtio/virtio_pci_common.c       | 9 ---------
> >  drivers/virtio/virtio_vdpa.c             | 5 -----
> >  include/linux/virtio_config.h            | 1 -
> >  8 files changed, 39 deletions(-)
> >
> > diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
> > index 8adca2000e51..1d1e8654b7fc 100644
> > --- a/arch/um/drivers/virtio_uml.c
> > +++ b/arch/um/drivers/virtio_uml.c
> > @@ -1031,11 +1031,6 @@ static int vu_find_vqs(struct virtio_device *vdev, unsigned nvqs,
> >                 return rc;
> >
> >         for (i = 0; i < nvqs; ++i) {
> > -               if (!names[i]) {
> > -                       vqs[i] = NULL;
> > -                       continue;
> > -               }
>
> Does this mean names[i] must not be NULL? If yes, should we fail or
> not? If not, do we need to change the doc?

I think we should make sure that the names[i] must not be NULL.
We should return fail.

>
> [...]
>
> > --- a/include/linux/virtio_config.h
> > +++ b/include/linux/virtio_config.h
> > @@ -56,7 +56,6 @@ typedef void vq_callback_t(struct virtqueue *);
> >   *     callbacks: array of callbacks, for each virtqueue
> >   *             include a NULL entry for vqs that do not need a callback
> >   *     names: array of virtqueue names (mainly for debugging)
> > - *             include a NULL entry for vqs unused by driver
> >   *     Returns 0 on success or error status
> >   * @del_vqs: free virtqueues found by find_vqs().
> >   * @synchronize_cbs: synchronize with the virtqueue callbacks (optional)
>
>
> Since we had other check for names[i] like:
>
>         if (per_vq_vectors) {
>                 /* Best option: one for change interrupt, one per vq. */
>                 nvectors = 1;
>                 for (i = 0; i < nvqs; ++i)
>                         if (names[i] && callbacks[i])
>                                 ++nvectors;
>
> in vp_find_vqs_msix() and maybe other places.

names[i] should always be true. I will check this.

Thanks


>
> > --
> > 2.32.0.3.g01195cf9f
> >
>