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, -- 2.20.0