linux-kernel - Re: [PATCH 6/6] percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is

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Date:	Thu, 19 Jun 2014 15:06:00 -0400
From:	Tejun Heo <tj@...nel.org>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	Lai Jiangshan <laijs@...fujitsu.com>, cl@...ux-foundation.org,
	kmo@...erainc.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] percpu-refcount: implement percpu_ref_reinit() and
 percpu_ref_is_zero()

Hello,

On Thu, Jun 19, 2014 at 10:05:49AM -0700, Paul E. McKenney wrote:
> If you mean what I think you mean by load_acquire_depends(), it is spelled
> "rcu_dereference()" or, in this case, where you are never removing anything
> that has been added, "rcu_dereference_raw()".  Because you are never
> removing anything, you don't need rcu_read_lock() or rcu_read_unlock(),
> thus you don't want lockdep yelling at you about not having RCU read-side
> critical sections, thus rcu_dereference_raw().

Yeah, along that line but it's kinda weird to use rcu_dereference()
when RCU isn't involved.  It'd be clearer to have something like
load_acquire_depends() and then define RCU deref in terms of it.

This is purely notational and clarifiying in the documentation is
probably enough.

Thanks.

-- 
tejun
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