Containers: css_put() dilemma

Balbir Singh balbir at
Tue Jul 17 22:30:39 PDT 2007

Balbir Singh wrote:
> Paul (??) Menage wrote:
>> On 7/17/07, Balbir Singh <balbir at> wrote:
>>> without too much knowledge of each other. BTW, what are the semantics
>>> of css_put() is it expected to free the container/run the release agent
>>> when the reference count of the container_subsys_state drops to zero?
>> If you css_put() the last reference on a subsystem state object and
>> the associated container is marked as notify_on_release, then
>> check_for_release() is called which does a more full check of whether
>> the container is releasable. If it is, a workqueue task is scheduled
>> to run the userspace release agent, which can then do anything it
>> wants, including potentially deleting the empty container.
> Ok.. so my problem still remains, how do I get a non-blocking atomic
> reference increment/decrement routine, that would prevent my
> container from being deleted?
> I don't find cpusets using css_put(). I was hoping that we could
> alter css_* would provide the functionality I need.

Thinking out loud again, can we add can_destory() callbacks?

	Warm Regards,
	Balbir Singh
	Linux Technology Center

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