On 11/03/2012 09:38 AM, Tejun Heo wrote:

Currently, there's no way for a controller to find out whether a new
cgroup finished all ->create() allocatinos successfully and is
considered "live" by cgroup.

This becomes a problem later when we add generic descendants walking
to cgroup which can be used by controllers as controllers don't have a
synchronization point where it can synchronize against new cgroups
appearing in such walks.

This patch adds ->post_create().  It's called after all ->create()
succeeded and the cgroup is linked into the generic cgroup hierarchy.
This plays the counterpart of ->pre_destroy().

Signed-off-by: Tejun Heo <redacted>
Cc: Glauber Costa <redacted>

Tejun, If we do it this way, we end up with two callbacks that are
called after create: post_clone and post_create. I myself prefer the
approach I took, that convert post_clone into post_create, and would
prefer if you would pick that up.

For me, post_clone is totally a glitch that should not exist. Merging
this with post_create gives the following semantics:

* A while after cgroup creation, you will get a callback. In that
callback, you do whatever initialization you may need that you could not
in create. Why is reacting to a flag being set any different?