Re: [PATCH] virtio_balloon: add array of stat names

[Jonathan Helman]

On 04/13/2018 06:44 AM, Michael S. Tsirkin wrote:
> Jason Wang points out that it's vary hard for users to build an array of

s/vary/very

> stat names. The naive thing is to use VIRTIO_BALLOON_S_NR but that
> breaks if we add more stats.
>
> Let's add an array of reasonably readable names.

Thanks for doing this, this is goodness. Clients of this interface will 
now only require a modification to their internal copy of the header 
file (if they have one), rather than updating their string array as well.

> Fixes: 6c64fe7f2 ("virtio_balloon: export hugetlb page allocation counts")

I think this is a tad bit confusing since the only way you'd know why 
this patch "fixes" 6c64fe7f2 is by reading the LKML archives and finding 
Jason's comment.

> Cc: Jason Wang <jasowang@xxxxxxxxxx>
> Cc: Jonathan Helman <jonathan.helman@xxxxxxxxxx>, > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

Reviewed-by: Jonathan Helman <jonathan.helman@xxxxxxxxxx>

> ---
>   include/uapi/linux/virtio_balloon.h | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
>
> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
> index 9e02137..1477c17 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -64,6 +64,21 @@ struct virtio_balloon_config {
>   #define VIRTIO_BALLOON_S_HTLB_PGFAIL   9  /* Hugetlb page allocation failures */
>   #define VIRTIO_BALLOON_S_NR       10
>   
> +#define VIRTIO_BALLOON_S_NAMES_WITH_PREFIX(VIRTIO_BALLOON_S_NAMES_prefix) { \
> +	VIRTIO_BALLOON_S_NAMES_prefix "swap-in", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "swap-out", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "major-faults", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "minor-faults", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "free-memory", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "total-memory", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "available-memory", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "disk-caches", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "hugetlb-allocations", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "hugetlb-failures" \ > +}
> +
> +#define VIRTIO_BALLOON_S_NAMES VIRTIO_BALLOON_S_NAMES_WITH_PREFIX("")
> +
>   /*
>    * Memory statistics structure.
>    * Driver fills an array of these structures and passes to device.