Re: [Qemu-devel] [PATCH] virtio-balloon: don't hardcode config size value

[Michael Tokarev]

09.01.2014 18:58, Luiz Capitulino wrote:
> Use sizeof(strucy virtio_balloon_config) instead.
> 
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -263,7 +263,7 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, 
> uint8_t *config_data)
>      config.num_pages = cpu_to_le32(dev->num_pages);
>      config.actual = cpu_to_le32(dev->actual);
>  
> -    memcpy(config_data, &config, 8);
> +    memcpy(config_data, &config, sizeof(struct virtio_balloon_config));

I'm not sure any of those is better than another.

This is a published guest <=> host interface, the config _must_ be 8 bytes
long and must contain 2 4-byte words in it.

We may use assert(sizeof(struct virtio_balloon_config) == 8) somewhere,
but to my taste it is a bit overkill.  No?

Thanks,

/mjt