Linux Virtualization - Apr 2020 - [PATCH] virtio-balloon: Avoid using the word 'report' when referring to free page hinting

From: Alexander Duyck <alexander.h.duyck at linux.intel.com>

It can be confusing to have multiple features within the same driver that
are using the same verbage. As such this patch is creating a union of
free_page_report_cmd_id with free_page_hint_cmd_id so that we can clean-up
the userspace code a bit in terms of readability while maintaining the
functionality of legacy code.

Signed-off-by: Alexander Duyck <alexander.h.duyck at linux.intel.com>
---
 drivers/virtio/virtio_balloon.c     |    2 +-
 include/uapi/linux/virtio_balloon.h |   11 +++++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 0ef16566c3f3..95d9c2f0a7be 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -580,7 +580,7 @@ static u32 virtio_balloon_cmd_id_received(struct
virtio_balloon *vb)
 	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
 			       &vb->config_read_bitmap))
 		virtio_cread(vb->vdev, struct virtio_balloon_config,
-			     free_page_report_cmd_id,
+			     free_page_hint_cmd_id,
 			     &vb->cmd_id_received_cache);
 
 	return vb->cmd_id_received_cache;
diff --git a/include/uapi/linux/virtio_balloon.h
b/include/uapi/linux/virtio_balloon.h
index 19974392d324..dc3e656470dd 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -48,8 +48,15 @@ struct virtio_balloon_config {
 	__u32 num_pages;
 	/* Number of pages we've actually got in balloon. */
 	__u32 actual;
-	/* Free page report command id, readonly by guest */
-	__u32 free_page_report_cmd_id;
+	/*
+	 * Free page hint command id, readonly by guest.
+	 * Was previously named free_page_report_cmd_id so we
+	 * need to carry that name for legacy support.
+	 */
+	union {
+		__u32 free_page_hint_cmd_id;
+		__u32 free_page_report_cmd_id;	/* deprecated */
+	};
 	/* Stores PAGE_POISON if page poisoning is in use */
 	__u32 poison_val;
 };

On 15.04.20 19:44, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck at linux.intel.com>
> 
> It can be confusing to have multiple features within the same driver that
> are using the same verbage. As such this patch is creating a union of
> free_page_report_cmd_id with free_page_hint_cmd_id so that we can clean-up
> the userspace code a bit in terms of readability while maintaining the
> functionality of legacy code.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck at linux.intel.com>
> ---
>  drivers/virtio/virtio_balloon.c     |    2 +-
>  include/uapi/linux/virtio_balloon.h |   11 +++++++++--
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c
b/drivers/virtio/virtio_balloon.c
> index 0ef16566c3f3..95d9c2f0a7be 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -580,7 +580,7 @@ static u32 virtio_balloon_cmd_id_received(struct
virtio_balloon *vb)
>  	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
>  			       &vb->config_read_bitmap))
>  		virtio_cread(vb->vdev, struct virtio_balloon_config,
> -			     free_page_report_cmd_id,
> +			     free_page_hint_cmd_id,
>  			     &vb->cmd_id_received_cache);
>  
>  	return vb->cmd_id_received_cache;
> diff --git a/include/uapi/linux/virtio_balloon.h
b/include/uapi/linux/virtio_balloon.h
> index 19974392d324..dc3e656470dd 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -48,8 +48,15 @@ struct virtio_balloon_config {
>  	__u32 num_pages;
>  	/* Number of pages we've actually got in balloon. */
>  	__u32 actual;
> -	/* Free page report command id, readonly by guest */
> -	__u32 free_page_report_cmd_id;
> +	/*
> +	 * Free page hint command id, readonly by guest.
> +	 * Was previously named free_page_report_cmd_id so we
> +	 * need to carry that name for legacy support.
> +	 */
> +	union {
> +		__u32 free_page_hint_cmd_id;
> +		__u32 free_page_report_cmd_id;	/* deprecated */
> +	};
>  	/* Stores PAGE_POISON if page poisoning is in use */
>  	__u32 poison_val;
>  };
> 
Can we also change the comment of

#define VIRTIO_BALLOON_F_FREE_PAGE_HINT	 /* VQ to report free pages */

?

Thanks!

-- 
Thanks,

David / dhildenb

On Wed, Apr 15, 2020 at 10:46 AM David Hildenbrand <david at redhat.com>
wrote:
> Can we also change the comment of
>
> #define VIRTIO_BALLOON_F_FREE_PAGE_HINT  /* VQ to report free pages */
>
> ?
>
> Thanks!
No problem. I will update and submit a v2.

Thanks.

- Alex