Re: [PATCH 1/2] cgroup allow subsys to set default mode of its own file

[Dhaval Giani <dhaval@linux.vnet.ibm.com>]

On Fri, Feb 27, 2009 at 09:20:31AM +0900, KAMEZAWA Hiroyuki wrote:
> On Thu, 26 Feb 2009 13:00:05 -0800
> Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > On Wed, 25 Feb 2009 16:35:55 +0900
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > 
> > >  When I wrote tools for maintain cgroup, I can't find which file is
> > >  writable intarfece or not via cgroup file systems. (finally, I did
> > >  dirty approach.)
> > >  IMHO, showing "this file is read-only" in explicit way is useful
> > >  for user-land (tools). In other story, a file whose name sounds read-only
> > >  may have "trigger" operation and support reseting. In this case,
> > >  "writable" is informative.
> > 
> > Well, we have compatibility issues here.  If we make this change, and
> > people write tools which depend upon that change then those tools might
> > break when run upon older kernels.  Or they need back-compatibility
> > additions, which increases the testing burden of those tools.
> > 
> > One way in which we could improve this situation is to backport these
> > changes into earlier kernels, although I don't know which versions.
> > 
> > What do we think?
> > 
> It sounds problem to me.
> 
> Hmm..1st commit to kernel/cgroup.c is 2007-10-19, then 2.6.24 is the oldest one.
> But I think distro's tools for cgroup is not as old as...
> Hmm, backport to 2.6.25 is enough ?
> Balbir, how do you think ? I think you are familiar with libcgroup.
> 

I would like to have this backported to at least the distro kernels.

thanks,
-- 
regards,
Dhaval