Re: [PATCH] vhost: silence an unused-variable warning

[Jason Wang]

On 2019/3/6 äå7:05, Arnd Bergmann wrote:
> On some architectures, the MMU can be disabled, leading to access_ok()
> becoming an empty macro that does not evaluate its size argument,
> which in turn produces an unused-variable warning:
>
> drivers/vhost/vhost.c:1191:9: error: unused variable 's' [-Werror,-Wunused-variable]
>          size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
>
> Mark the variable as __maybe_unused to shut up that warning.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>   drivers/vhost/vhost.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index a2e5dc7716e2..5ace833de746 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1188,7 +1188,7 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
>   			 struct vring_used __user *used)
>   
>   {
> -	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> +	size_t s __maybe_unused = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
>   
>   	return access_ok(desc, num * sizeof *desc) &&
>   	       access_ok(avail,


Acked-by: Jason Wang <jasowang@xxxxxxxxxx>