Re: [PATCH v2 1/7] vhost-user: strip superfluous whitespace

[Laszlo Ersek <lersek@redhat.com>]

On 9/6/23 09:12, Albert Esteve wrote:
> 
> 
> On Thu, Aug 31, 2023 at 9:14 AM Laszlo Ersek <lersek@redhat.com
> <mailto:lersek@redhat.com>> wrote:
> 
>     On 8/30/23 15:40, Laszlo Ersek wrote:
>     > Cc: "Michael S. Tsirkin" <mst@redhat.com <mailto:mst@redhat.com>>
>     (supporter:vhost)
>     > Cc: Eugenio Perez Martin <eperezma@redhat.com
>     <mailto:eperezma@redhat.com>>
>     > Cc: German Maglione <gmaglione@redhat.com
>     <mailto:gmaglione@redhat.com>>
>     > Cc: Liu Jiang <gerry@linux.alibaba.com
>     <mailto:gerry@linux.alibaba.com>>
>     > Cc: Sergio Lopez Pascual <slp@redhat.com <mailto:slp@redhat.com>>
>     > Cc: Stefano Garzarella <sgarzare@redhat.com
>     <mailto:sgarzare@redhat.com>>
>     > Signed-off-by: Laszlo Ersek <lersek@redhat.com
>     <mailto:lersek@redhat.com>>
>     > Reviewed-by: Stefano Garzarella <sgarzare@redhat.com
>     <mailto:sgarzare@redhat.com>>
>     > ---
>     >
>     > Notes:
>     >     v2:
>     >     
>     >     - pick up Stefano's R-b
>     >
>     >  hw/virtio/vhost-user.c | 2 +-
>     >  1 file changed, 1 insertion(+), 1 deletion(-)
> 
>     This has been
> 
>     Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org
>     <mailto:philmd@linaro.org>>
> 
>     under the (identical) v1 posting:
> 
>     http://mid.mail-archive.com/cd0604a1-6826-ac6c-6c47-dcb6def64b28@linaro.org <http://mid.mail-archive.com/cd0604a1-6826-ac6c-6c47-dcb6def64b28@linaro.org>
> 
>     Thanks, Phil! (and sorry that I posted v2 too quickly -- I forgot that
>     sometimes reviewers split a review over multiple days.)
> 
>     Laszlo
> 
>     >
>     > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
>     > index 8dcf049d422b..b4b677c1ce66 100644
>     > --- a/hw/virtio/vhost-user.c
>     > +++ b/hw/virtio/vhost-user.c
>     > @@ -398,7 +398,7 @@ static int vhost_user_write(struct vhost_dev
>     *dev, VhostUserMsg *msg,
>     >       * operations such as configuring device memory mappings or
>     issuing device
>     >       * resets, which affect the whole device instead of
>     individual VQs,
>     >       * vhost-user messages should only be sent once.
>     > -     *
>     > +     *
>     >       * Devices with multiple vhost_devs are given an associated
>     dev->vq_index
>     >       * so per_device requests are only sent if vq_index is 0.
>     >       */
>     >
> 
> 
> Thanks for the series!
> I had a timeout problem with a virtio device I am developing, and I was
> not sure yet what was going on.
> Your description of the problem seemed to fit mine, in my case the
> driver sent a command through the data plane
> right after the feature negotiation that reached the backend too soon.
> Adding delays alleviated the issue, so it
> already hinted me to a race condition.
> 
> I tested using this patch series and according to my experiments, it
> really lowers the chances to get the deadlock.
> Sadly, I do still get the issue sometimes, though (not frequently)...
> However, I think probably the solution comes not
> from the Qemu side, but from the rust-vmm vhost-user-backend crate. I am
> looking for that solution on my side.
> 
> But that does not invalidate this patch, which I think is a necessary
> improvement, and in my tests it really
> helps a lot with the described issue. Therefore:
> 
> Tested-by: Albert Esteve <aesteve@redhat.com <mailto:aesteve@redhat.com>>

Thanks again -- I'm picking this up for the whole series.

Laszlo

> 
> BR,
> Albert