Containers: css_put() dilemma

Paul (宝瑠) Menage menage at
Tue Jul 17 10:44:08 PDT 2007

On 7/17/07, Balbir Singh <balbir at> wrote:
> That sounds correct. I wonder now if the solution should be some form
> of delegation for deletion of unreferenced containers (HINT: work queue
> or kernel threads).

What a great idea. In fact, that's exactly what the release agent
patch already does.

> > Adding a synchronize_rcu in container_diput() guarantees that the
> > container structure won't be freed while someone may still be
> > accessing it.
> >
> Do we take rcu_read_lock() in css_put() path or use call_rcu() to
> free the container?

Good point, we ought to add rcu_read_lock() (even though it doesn't
actually do anything on architectures other than alpha, right?)

Using call_rcu to do the container kfree rather than synchronize_rcu()
would be a possible future optimization, yes.


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