Re: [PATCHv3] 1/3] libxc: prefer using privcmd character device

[Wei Liu <wei.liu2@citrix.com>]

On Tue, Dec 01, 2015 at 01:27:53PM -0600, Doug Goldstein wrote:
> Prefer using the character device over the proc file if the character
> device exists. This follows similar conversions of xenbus to avoid
> issues with FMODE_ATOMIC_POS added in Linux 3.14 and newer.
> 
> CC: Ian Jackson <ian.jackson@eu.citrix.com>
> CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> CC: Ian Campbell <ian.campbell@citrix.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> Signed-off-by: Doug Goldstein <cardoe@cardoe.com>

Acked-by: Wei Liu <wei.liu2@citrix.com>

> ---
>  tools/libxc/xc_linux_osdep.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
> index 76c55ff..c3a3a14 100644
> --- a/tools/libxc/xc_linux_osdep.c
> +++ b/tools/libxc/xc_linux_osdep.c
> @@ -46,7 +46,13 @@
>  static xc_osdep_handle linux_privcmd_open(xc_interface *xch)
>  {
>      int flags, saved_errno;
> -    int fd = open("/proc/xen/privcmd", O_RDWR);
> +    int fd = open("/dev/xen/privcmd", O_RDWR); /* prefer this newer interface */
> +
> +    if ( fd == -1 && ( errno == ENOENT || errno == ENXIO || errno == ENODEV ))
> +    {
> +        /* Fallback to /proc/xen/privcmd */
> +        fd = open("/proc/xen/privcmd", O_RDWR);
> +    }
>  
>      if ( fd == -1 )
>      {
> -- 
> 2.4.10
>