On Thu, Mar 16, 2023 at 2:55 AM Feng Liu <feliu@xxxxxxxxxx> wrote:
>
> Add const to make the read-only pointer parameters clear, similar to
> many existing functions.
>
> Use `container_of_const` to implement `to_vvq`, which ensures the
> const-ness of read-only parameters and avoids accidental modification
> of their members.
>
> Signed-off-by: Feng Liu <feliu@xxxxxxxxxx>
> Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Thanks
>
> ---
> v0 -> v1
> feedbacks from Michael S. Tsirkin
> - use `container_of_const` to implement `to_vvq`
> ---
> drivers/virtio/virtio_ring.c | 36 ++++++++++++++++++------------------
> include/linux/virtio.h | 14 +++++++-------
> 2 files changed, 25 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index a26fab91c59f..4c3bb0ddeb9b 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -231,9 +231,9 @@ static void vring_free(struct virtqueue *_vq);
> * Helpers.
> */
>
> -#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
> +#define to_vvq(_vq) container_of_const(_vq, struct vring_virtqueue, vq)
>
> -static bool virtqueue_use_indirect(struct vring_virtqueue *vq,
> +static bool virtqueue_use_indirect(const struct vring_virtqueue *vq,
> unsigned int total_sg)
> {
> /*
> @@ -269,7 +269,7 @@ static bool virtqueue_use_indirect(struct vring_virtqueue *vq,
> * unconditionally on data path.
> */
>
> -static bool vring_use_dma_api(struct virtio_device *vdev)
> +static bool vring_use_dma_api(const struct virtio_device *vdev)
> {
> if (!virtio_has_dma_quirk(vdev))
> return true;
> @@ -289,7 +289,7 @@ static bool vring_use_dma_api(struct virtio_device *vdev)
> return false;
> }
>
> -size_t virtio_max_dma_size(struct virtio_device *vdev)
> +size_t virtio_max_dma_size(const struct virtio_device *vdev)
> {
> size_t max_segment_size = SIZE_MAX;
>
> @@ -423,7 +423,7 @@ static void virtqueue_init(struct vring_virtqueue *vq, u32 num)
> */
>
> static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq,
> - struct vring_desc *desc)
> + const struct vring_desc *desc)
> {
> u16 flags;
>
> @@ -1183,7 +1183,7 @@ static u16 packed_last_used(u16 last_used_idx)
> }
>
> static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
> - struct vring_desc_extra *extra)
> + const struct vring_desc_extra *extra)
> {
> u16 flags;
>
> @@ -1206,7 +1206,7 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
> }
>
> static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
> - struct vring_packed_desc *desc)
> + const struct vring_packed_desc *desc)
> {
> u16 flags;
>
> @@ -2786,10 +2786,10 @@ EXPORT_SYMBOL_GPL(vring_transport_features);
> * Returns the size of the vring. This is mainly used for boasting to
> * userspace. Unlike other operations, this need not be serialized.
> */
> -unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)
> +unsigned int virtqueue_get_vring_size(const struct virtqueue *_vq)
> {
>
> - struct vring_virtqueue *vq = to_vvq(_vq);
> + const struct vring_virtqueue *vq = to_vvq(_vq);
>
> return vq->packed_ring ? vq->packed.vring.num : vq->split.vring.num;
> }
> @@ -2819,9 +2819,9 @@ void __virtqueue_unbreak(struct virtqueue *_vq)
> }
> EXPORT_SYMBOL_GPL(__virtqueue_unbreak);
>
> -bool virtqueue_is_broken(struct virtqueue *_vq)
> +bool virtqueue_is_broken(const struct virtqueue *_vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> + const struct vring_virtqueue *vq = to_vvq(_vq);
>
> return READ_ONCE(vq->broken);
> }
> @@ -2868,9 +2868,9 @@ void __virtio_unbreak_device(struct virtio_device *dev)
> }
> EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
>
> -dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> +dma_addr_t virtqueue_get_desc_addr(const struct virtqueue *_vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> + const struct vring_virtqueue *vq = to_vvq(_vq);
>
> BUG_ON(!vq->we_own_ring);
>
> @@ -2881,9 +2881,9 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> }
> EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
>
> -dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
> +dma_addr_t virtqueue_get_avail_addr(const struct virtqueue *_vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> + const struct vring_virtqueue *vq = to_vvq(_vq);
>
> BUG_ON(!vq->we_own_ring);
>
> @@ -2895,9 +2895,9 @@ dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
> }
> EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
>
> -dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
> +dma_addr_t virtqueue_get_used_addr(const struct virtqueue *_vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> + const struct vring_virtqueue *vq = to_vvq(_vq);
>
> BUG_ON(!vq->we_own_ring);
>
> @@ -2910,7 +2910,7 @@ dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
> EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
>
> /* Only available for split ring */
> -const struct vring *virtqueue_get_vring(struct virtqueue *vq)
> +const struct vring *virtqueue_get_vring(const struct virtqueue *vq)
> {
> return &to_vvq(vq)->split.vring;
> }
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 2b472514c49b..c4225653f949 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -84,14 +84,14 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
>
> void *virtqueue_detach_unused_buf(struct virtqueue *vq);
>
> -unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
> +unsigned int virtqueue_get_vring_size(const struct virtqueue *vq);
>
> -bool virtqueue_is_broken(struct virtqueue *vq);
> +bool virtqueue_is_broken(const struct virtqueue *vq);
>
> -const struct vring *virtqueue_get_vring(struct virtqueue *vq);
> -dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq);
> -dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
> -dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);
> +const struct vring *virtqueue_get_vring(const struct virtqueue *vq);
> +dma_addr_t virtqueue_get_desc_addr(const struct virtqueue *vq);
> +dma_addr_t virtqueue_get_avail_addr(const struct virtqueue *vq);
> +dma_addr_t virtqueue_get_used_addr(const struct virtqueue *vq);
>
> int virtqueue_resize(struct virtqueue *vq, u32 num,
> void (*recycle)(struct virtqueue *vq, void *buf));
> @@ -147,7 +147,7 @@ int virtio_device_restore(struct virtio_device *dev);
> #endif
> void virtio_reset_device(struct virtio_device *dev);
>
> -size_t virtio_max_dma_size(struct virtio_device *vdev);
> +size_t virtio_max_dma_size(const struct virtio_device *vdev);
>
> #define virtio_device_for_each_vq(vdev, vq) \
> list_for_each_entry(vq, &vdev->vqs, list)
> --
> 2.34.1
>
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