Re: [PATCH v2 09/13] xenstore: make use of the "xenstore domain" flag

[Ian Campbell <ian.campbell@citrix.com>]

On Fri, 2015-12-18 at 14:14 +0100, Juergen Gross wrote:
> Create the xenstore domain with the xs_domain flag specified. This
> enables us to test whether such a domain is already running before
> we create it. As there ought to be only one xenstore in the system
> we don't need to start another one.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>  tools/helpers/init-xenstore-domain.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/helpers/init-xenstore-domain.c b/tools/helpers/init-
> xenstore-domain.c
> index 17f0151..4cd9e0f 100644
> --- a/tools/helpers/init-xenstore-domain.c
> +++ b/tools/helpers/init-xenstore-domain.c
> @@ -66,7 +66,8 @@ static int build(xc_interface *xch)
>      } else {
>          ssid = SECINITSID_DOMU;
>      }
> -    rv = xc_domain_create(xch, ssid, handle, 0, &domid, NULL);
> +    rv = xc_domain_create(xch, ssid, handle, XEN_DOMCTL_CDF_xs_domain,
> +                  &domid, NULL);
>      if (rv) {
>          fprintf(stderr, "xc_domain_create failed\n");
>          goto err;
> @@ -165,6 +166,21 @@ err:
>      return rv;
>  }
>  
> +static int check_domain(xc_interface *xch)
> +{
> +    xc_dominfo_t info;
> +    uint32_t dom;
> +
> +    dom = 0;

You can pretty safely skip dom0 I think?

> +    while (xc_domain_getinfo(xch, dom, 1, &info) == 1) {

Logging errors (i.e. on return < 0) would be nice I think.

> +        if (info.xs_domain)
> +            return 1;
> +        dom = info.domid + 1;
> +    }
> +
> +    return 0;
> +}
> +
>  int main(int argc, char** argv)
>  {
>      int opt;
> @@ -204,7 +220,12 @@ int main(int argc, char** argv)
>          return 1;
>      }
>  
> -    rv = build(xch);
> +    rv = check_domain(xch);
> +
> +    if (!rv)
> +        rv = build(xch);
> +    else
> +        fprintf(stderr, "xenstore domain already present.\n");
>  
>      xc_interface_close(xch);
>  
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