Re: [PATCH 3/3] virtio_ring: Use const to annotate read-only pointer params

[David Edmondson <david.edmondson@oracle.com>]

Feng Liu via Virtualization <virtualization@lists.linux-foundation.org>
writes:

> Add const to make the read-only pointer parameters clear, similar to
> many existing functions.

In many of the modified functions the local variable that is a cast of
the argument could also be const. Is there a reason not to do both at
the same time?

> Signed-off-by: Feng Liu <feliu@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
> Reviewed-by: Parav Pandit <parav@nvidia.com>
> Reviewed-by: Gavin Li <gavinl@nvidia.com>
> Reviewed-by: Bodong Wang <bodong@nvidia.com>
> ---
>  drivers/virtio/virtio_ring.c | 25 ++++++++++++-------------
>  include/linux/virtio.h       | 12 ++++++------
>  2 files changed, 18 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 806cc44eae64..8010fd1d2047 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -233,7 +233,7 @@ static void vring_free(struct virtqueue *_vq);
>  
>  #define to_vvq(_vq) container_of(_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;
>  
> @@ -2786,7 +2786,7 @@ 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);
> @@ -2819,7 +2819,7 @@ 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);
>  
> @@ -2827,8 +2827,7 @@ bool virtqueue_is_broken(struct virtqueue *_vq)
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_is_broken);
>  
> -/*
> - * This should prevent the device from being used, allowing drivers to
> +/ This should prevent the device from being used, allowing drivers to
>   * recover.  You may need to grab appropriate locks to flush.
>   */
>  void virtio_break_device(struct virtio_device *dev)
> @@ -2881,7 +2880,7 @@ 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);
>  
> @@ -2895,7 +2894,7 @@ 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);
>  
> @@ -2910,7 +2909,7 @@ 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..36a79374e735 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));
> -- 
> 2.34.1
>
> _______________________________________________
> Virtualization mailing list
> Virtualization@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/virtualization
-- 
Woke up in my clothes again this morning, don't know exactly where I am.
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization