Re: [PATCH] cgroups: fix API thinko

From: Paul Menage
Date: Wed Aug 25 2010 - 22:08:58 EST


On Wed, Aug 25, 2010 at 2:35 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> So am I correct to assume that this change is now needed in 2.6.36, and
> unneeded in 2.6.35?
>
> Can it affect the userspace<->kernel API in amy manner?  If so, it
> should be backported into earlier kernels to reduce the number of
> incompatible kernels out there.

AFAICS it shouldn't affect any existing APIs, either in-kernel or to
userspace - it just makes the existing function
cgroup_attach_task_current_cg() a specialization of a more generic new
function.

>
> Paul, did you have any comments?

Other than the language being a bit confusing, it seems fine. I'd
probably word the patch description as:

Add cgroup_attach_task_all()

The existing cgroup_attach_task_current_cg() API is called by a thread
to attach another thread to all of its cgroups; this is unsuitable for
cases where a privileged task wants to attach itself to the cgroups
of a less privileged one, since the call must be made from the context
of the target task.

This patch adds a more generic cgroup_attach_task_all() API that
allows both the source task and to-be-moved task to be specified.
cgroup_attach_task_current_cg() becomes a specialization of the more
generic new function.

Acked-by: Paul Menage <menage@xxxxxxxxxx>
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