Linux Virtualization - Oct 2021 - [PATCH] virtio-ring: fix DMA metadata flags

The flags are currently overwritten, leading to the wrong direction
being passed to the DMA unmap functions.

Fixes: 72b5e8958738aaa4 ("virtio-ring: store DMA metadata in desc_extra for
split virtqueue")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch at axis.com>
---
 drivers/virtio/virtio_ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index dd95dfd85e98..3035bb6f5458 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -576,7 +576,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	/* Last one doesn't continue. */
 	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
 	if (!indirect && vq->use_dma_api)
-		vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags +	
vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags & 		
~VRING_DESC_F_NEXT;
 
 	if (indirect) {
-- 
2.28.0

On Tue, Oct 26, 2021 at 9:31 PM Vincent Whitchurch
<vincent.whitchurch at axis.com> wrote:
>
> The flags are currently overwritten, leading to the wrong direction
> being passed to the DMA unmap functions.
>
> Fixes: 72b5e8958738aaa4 ("virtio-ring: store DMA metadata in
desc_extra for split virtqueue")
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch at axis.com>
Acked-by: Jason Wang <jasowang at redhat.com>

Thanks
> ---
>  drivers/virtio/virtio_ring.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index dd95dfd85e98..3035bb6f5458 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -576,7 +576,7 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
>         /* Last one doesn't continue. */
>         desc[prev].flags &= cpu_to_virtio16(_vq->vdev,
~VRING_DESC_F_NEXT);
>         if (!indirect && vq->use_dma_api)
> -               vq->split.desc_extra[prev & (vq->split.vring.num
- 1)].flags > +               vq->split.desc_extra[prev &
(vq->split.vring.num - 1)].flags &>                        
~VRING_DESC_F_NEXT;
>
>         if (indirect) {
> --
> 2.28.0
>