On 8/30/23 15:40, Laszlo Ersek wrote:
> Cc: "Michael S. Tsirkin" <mst@redhat.com> (supporter:vhost)
> Cc: Eugenio Perez Martin <eperezma@redhat.com>
> Cc: German Maglione <gmaglione@redhat.com>
> Cc: Liu Jiang <gerry@linux.alibaba.com>
> Cc: Sergio Lopez Pascual <slp@redhat.com>
> Cc: Stefano Garzarella <sgarzare@redhat.com>
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> Reviewed-by: Stefano Garzarella <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>
under the (identical) v1 posting:
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:
BR,
Albert