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From: Kent Overstreet <koverstreet@google.com>
To: Tejun Heo <theo@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Rusty Russell <rusty@rustcorp.com.au>,
	Oleg Nesterov <oleg@redhat.com>,
	Christoph Lameter <cl@linux-foundation.org>
Subject: Re: [PATCH percpu/for-3.11] percpu-refcount: consistently use plain (non-sched) RCU
Date: Wed, 12 Jun 2013 13:55:00 -0700	[thread overview]
Message-ID: <20130612205500.GE6151@google.com> (raw)
In-Reply-To: <20130612204031.GA15092@htj.dyndns.org>

On Wed, Jun 12, 2013 at 01:40:32PM -0700, Tejun Heo wrote:
> From e96262150a513ce3d54ff221d4ace8aeec96e0bf Mon Sep 17 00:00:00 2001
> From: Tejun Heo <tj@kernel.org>
> Date: Wed, 12 Jun 2013 13:37:42 -0700
> 
> percpu_ref_get/put() are using preempt_disable/enable() while
> percpu_ref_kill() is using plain call_rcu() instead of
> call_rcu_sched().  This is buggy as grace periods of the two may not
> match.  Fix it by using plain RCU in percpu_ref_get/put().
> 
> (I suggested using sched RCU in the first place but there's no actual
>  benefit in doing so unless we're gonna introduce different variants
>  of get/put to be called while preemption is alredy disabled, which we
>  definitely shouldn't.)
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Rusty Russell <rusty@rustcorp.com.au>

Acked-by: Kent Overstreet <koverstreet@google.com>

  reply	other threads:[~2013-06-12 20:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-12 20:40 [PATCH percpu/for-3.11] percpu-refcount: consistently use plain (non-sched) RCU Tejun Heo
2013-06-12 20:55 ` Kent Overstreet [this message]
2013-06-13  3:48 ` Tejun Heo

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