Re: [Xen-devel] [PATCH v2] xen-blkfront: remove type check from blkfront_setup_discard

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.01.14 at 11:14, Olaf Hering <olaf@xxxxxxxxx> wrote:
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -1634,37 +1634,22 @@ blkfront_closing(struct blkfront_info *info)
>  
>  static void blkfront_setup_discard(struct blkfront_info *info)
>  {
> -     int err;
> -     char *type;
>       unsigned int discard_granularity;
>       unsigned int discard_alignment;
>       unsigned int discard_secure;
>  
> -     type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
> -     if (IS_ERR(type))
> +     if (xenbus_gather(XBT_NIL, info->xbdev->otherend,
> +             "discard-granularity", "%u", &discard_granularity,
> +             "discard-alignment", "%u", &discard_alignment,
> +             "discard-secure", "%u", &discard_secure,
> +             NULL))
>               return;

You can't do this in one go - the first two and the last one may be
set independently (and are independent in their meaning), and
hence need to be queried independently (xenbus_gather() fails
on the first absent value).

Jan


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