Re: [PATCH V4 1/1] rcu: introduce kfree_rcu()

Lai Jiangshan
2011-03-16T02:48:53Z

On 03/15/2011 07:30 PM, Paul E. McKenney wrote:
> On Tue, Mar 15, 2011 at 05:46:20PM +0800, Lai Jiangshan wrote:
>> kfree_rcu() which was original proposed by Lai 2.5 years ago is one of
>> the most important RCU TODO list entries, Lai and Manfred have worked on
>> patches for this. This V4 patch is based on the Manfred's patch and
>> the V1 of Lai's patch. (These two patches are almost the same
>> in implementation, and this patch is mainly based on the Manfred's).
>>
>> Lai's V1 patch: http://lkml.org/lkml/2008/9/18/1
>> Manfred's patch: http://lkml.org/lkml/2009/1/2/115
>> RCU TODO list: http://www.kernel.org/pub/linux/kernel/people/paulmck/rcutodo.html
>>
>> This new introduced API kfree_rcu() primitive kfree()s the specified memory
>> after a RCU grace period elapses.
>>
>> It replaces many simple "call_rcu(head, simple_kfree_callback)";
>> These many simple_kfree_callback() instances just does
>>
>> kfree(containerof(head,struct whatever_struct,rcu_member));
>>
>> These simple_kfree_callback() instances are just duplicate code, we need
>> a generic function for them.
>>
>> And kfree_rcu() is also help for unloadable modules, kfree_rcu() does not
>> queue any function which belong to the module, so a rcu_barrier() can
>> be avoid when module exit. (If we queue any other function by call_rcu(),
>> rcu_barrier() is still needed.)
>
> Thank you for putting this together! It does represent a nice
> reduction in code size.
>
> Once it settles out a bit, I intend to queue this patch. It would be
> best if the subsystems queue their own patches using kfree_rcu() once
> this patch reaches mainline.
>

It seems that the subsystems maintainers just Ack the patches.
I hope Ingo queue the Acked using kfree_rcu() patches into -tip,
it will help the kfree_rcu() reaches mainline earlier.

Thanks,
Lai