Re: [PATCH 2/4] virtio_ring: switch to use BAD_RING()

From: Michael S. Tsirkin
Date: Mon Dec 26 2022 - 18:37:46 EST


On Mon, Dec 26, 2022 at 03:49:06PM +0800, Jason Wang wrote:
> Switch to reuse BAD_RING() to allow common logic to be implemented in
> BAD_RING().
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> Changes since V1:
> - switch to use BAD_RING in virtio_break_device()
> ---
> drivers/virtio/virtio_ring.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 2e7689bb933b..5cfb2fa8abee 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -58,7 +58,8 @@
> do { \
> dev_err(&_vq->vq.vdev->dev, \
> "%s:"fmt, (_vq)->vq.name, ##args); \
> - (_vq)->broken = true; \
> + /* Pairs with READ_ONCE() in virtqueue_is_broken(). */ \

I don't think WRITE_ONCE/READ_ONCE pair as such. Can you point
me at documentation of such pairing?

> + WRITE_ONCE((_vq)->broken, true); \
> } while (0)
> #define START_USE(vq)
> #define END_USE(vq)
> @@ -2237,7 +2238,7 @@ bool virtqueue_notify(struct virtqueue *_vq)
>
> /* Prod other side to tell it about changes. */
> if (!vq->notify(_vq)) {
> - vq->broken = true;
> + BAD_RING(vq, "vq %d is broken\n", vq->vq.index);
> return false;
> }
> return true;
> @@ -2786,8 +2787,7 @@ void virtio_break_device(struct virtio_device *dev)
> list_for_each_entry(_vq, &dev->vqs, list) {
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> - /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> - WRITE_ONCE(vq->broken, true);
> + BAD_RING(vq, "Device break vq %d", _vq->index);
> }
> spin_unlock(&dev->vqs_list_lock);
> }
> --
> 2.25.1