Re: [PATCH V5 1/1] rcu: introduce kfree_rcu()

[Arnd Bergmann <arnd@arndb.de>]

On Friday 18 March 2011, 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.)
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> Signed-off-by: Manfred Spraul <manfred@colorfullife.com>

Acked-by: Arnd Bergmann <arnd@arndb.de>