Re: [PATCH] vhost-user: Fix backends without multiqueue support

[Raphael Norwitz <raphael.norwitz@nutanix.com>]

On Mon, Jul 05, 2021 at 07:14:29PM +0200, Kevin Wolf wrote:
> dev->max_queues was never initialised for backends that don't support
> VHOST_USER_PROTOCOL_F_MQ, so it would use 0 as the maximum number of
> queues to check against and consequently fail for any such backend.
> 
> Set it to 1 if the backend doesn't have multiqueue support.
> 
> Fixes: c90bd505a3e8210c23d69fecab9ee6f56ec4a161
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>

> ---
>  hw/virtio/vhost-user.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 1ac4a2ebec..29ea2b4fce 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -1913,7 +1913,10 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque,
>              if (err < 0) {
>                  return -EPROTO;
>              }
> +        } else {
> +            dev->max_queues = 1;
>          }
> +
>          if (dev->num_queues && dev->max_queues < dev->num_queues) {
>              error_setg(errp, "The maximum number of queues supported by the "
>                         "backend is %" PRIu64, dev->max_queues);
> -- 
> 2.31.1
>