Re: [Qemu-devel] [PATCH v3 06/16] vhost: use variable arguments for vhost_call()

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Aug 06, 2015 at 02:40:42PM +0200, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> It is useful to pass extra arguments to the funtions, for
> various backend needs.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Let's not do this.
It's probably time to replace vhost_call with an ops struct of functions.
This will solve this in a clean way.


> ---
>  hw/virtio/vhost-backend.c         | 4 ++--
>  hw/virtio/vhost-user.c            | 4 ++--
>  include/hw/virtio/vhost-backend.h | 6 ++++--
>  3 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index 4d68a27..7255089 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -14,8 +14,8 @@
>  
>  #include <sys/ioctl.h>
>  
> -static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
> -                             void *arg)
> +static int vhost_kernel_call(struct vhost_dev *dev,
> +                             unsigned long int request, void *arg, ...)
>  {
>      int fd = (uintptr_t) dev->opaque;
>  
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 4993b63..8b6d7e7 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -190,8 +190,8 @@ static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
>              0 : -1;
>  }
>  
> -static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
> -        void *arg)
> +static int vhost_user_call(struct vhost_dev *dev,
> +                           unsigned long int request, void *arg, ...)
>  {
>      VhostUserMsg msg;
>      VhostUserRequest msg_request;
> diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
> index e472f29..36fa0f7 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -11,6 +11,8 @@
>  #ifndef VHOST_BACKEND_H_
>  #define VHOST_BACKEND_H_
>  
> +#include <stdarg.h>
> +
>  typedef enum VhostBackendType {
>      VHOST_BACKEND_TYPE_NONE = 0,
>      VHOST_BACKEND_TYPE_KERNEL = 1,
> @@ -20,8 +22,8 @@ typedef enum VhostBackendType {
>  
>  struct vhost_dev;
>  
> -typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request,
> -             void *arg);
> +typedef int (*vhost_call)(struct vhost_dev *dev,
> +                          unsigned long int request, void *arg, ...);
>  typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
>  typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
>  
> -- 
> 2.4.3