Re: [Qemu-devel] [PATCH v2] vhost-user: pass message as a pointer to process_message_reply()

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

On Wed, May 24, 2017 at 11:05:20AM +0200, Maxime Coquelin wrote:
> process_message_reply() was recently updated to get full message
> content instead of only its request field.
> 
> There is no need to copy all the struct content into the stack,
> so just pass its pointer as const.
> 
> Cc: Zhiyong Yang <zhiyong.yang@intel.com>
> Fixes: 60cd11024f41 ("hw/virtio: fix vhost user fails to startup when MQ")
> Reviewed-by: Jens Freimann <jfreiman@redhat.com>
> Reviewed-by: Zhiyong Yang <zhiyong.yang@intel.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Why "Fixes"? It's not a bugfix, is it? Passing a pointer is
slightly cleaner but it's not a big deal IMHO. I'll apply
but would like to get clarification on this tag.

> ---
> V2:
>  - Make msg pointer const (Marc-Andre)
>  - Apply R-b's
> 
>  hw/virtio/vhost-user.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index b87a176..dde094a 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -162,11 +162,11 @@ fail:
>  }
>  
>  static int process_message_reply(struct vhost_dev *dev,
> -                                 VhostUserMsg msg)
> +                                 const VhostUserMsg *msg)
>  {
>      VhostUserMsg msg_reply;
>  
> -    if ((msg.flags & VHOST_USER_NEED_REPLY_MASK) == 0) {
> +    if ((msg->flags & VHOST_USER_NEED_REPLY_MASK) == 0) {
>          return 0;
>      }
>  
> @@ -174,10 +174,10 @@ static int process_message_reply(struct vhost_dev *dev,
>          return -1;
>      }
>  
> -    if (msg_reply.request != msg.request) {
> +    if (msg_reply.request != msg->request) {
>          error_report("Received unexpected msg type."
>                       "Expected %d received %d",
> -                     msg.request, msg_reply.request);
> +                     msg->request, msg_reply.request);
>          return -1;
>      }
>  
> @@ -324,7 +324,7 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev,
>      }
>  
>      if (reply_supported) {
> -        return process_message_reply(dev, msg);
> +        return process_message_reply(dev, &msg);
>      }
>  
>      return 0;
> @@ -716,7 +716,7 @@ static int vhost_user_net_set_mtu(struct vhost_dev *dev, uint16_t mtu)
>  
>      /* If reply_ack supported, slave has to ack specified MTU is valid */
>      if (reply_supported) {
> -        return process_message_reply(dev, msg);
> +        return process_message_reply(dev, &msg);
>      }
>  
>      return 0;
> -- 
> 2.9.4