Re: [PATCH 1/2 iptables] libxt_cgroup: prepare for multi revisions

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Sat, Nov 21, 2015 at 11:18:46AM -0500, Tejun Heo wrote:
> libxt_cgroup will grow cgroup2 path based match.  Postfix existing
> symbols with _v0 and prepare for multi revision registration.  While
> at it, rename O_CGROUP to O_CLASSID and fwid to classid.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Daniel Borkmann <dborkman@redhat.com>
> Cc: Jan Engelhardt <jengelh@inai.de>
> Cc: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  extensions/libxt_cgroup.c           |   51 +++++++++++++++++++-----------------
>  include/linux/netfilter/xt_cgroup.h |    2 -
>  2 files changed, 28 insertions(+), 25 deletions(-)
> 
> --- a/extensions/libxt_cgroup.c
> +++ b/extensions/libxt_cgroup.c
> @@ -3,30 +3,30 @@
>  #include <linux/netfilter/xt_cgroup.h>
>  
>  enum {
> -	O_CGROUP = 0,
> +	O_CLASSID = 0,
>  };
>  
> -static void cgroup_help(void)
> +static void cgroup_help_v0(void)
>  {
>  	printf(
>  "cgroup match options:\n"
> -"[!] --cgroup fwid  Match cgroup fwid\n");
> +"[!] --cgroup classid            Match cgroup classid\n");

We have to keep the old cgroup integer ID around for a while,
otherwise we'll break users with old kernels and new iptables
utilities.