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From: Tejun Heo <tj@kernel.org>
To: Roman Penyaev <roman.penyaev@profitbricks.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/1] percpu-refcount: do not forget to rcu_barrier() just before freeing
Date: Thu, 11 Aug 2016 12:29:01 -0400	[thread overview]
Message-ID: <20160811162901.GC2695@mtj.duckdns.org> (raw)
In-Reply-To: <CAJrWOzCjXQ8D=OprqHCH7NXn81-rVqZyjbz6+8mAP=GHgV3_vg@mail.gmail.com>

Hello, Roman.

On Thu, Aug 11, 2016 at 11:07:14AM +0200, Roman Penyaev wrote:
> Yes, exactly, this is an illegal operation.  But it is not more illegal
> than calling kill() twice or reinit() when counter is not yet zero.
> And those illegals are covered with warnings, which can be observed
> for example with this freeze/unfreeze blk-mq bug.

I have no objections about adding warnings for these conditions;
however, adding rcu barrier to mask illegal usages is a very different
thing.  That adds a lot of unnecessary latency to the exit function
and makes it unusable from non-sleepable contexts.

Thanks.

-- 
tejun

  reply	other threads:[~2016-08-11 16:29 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-10 19:55 Roman Pen
2016-08-10 22:09 ` Tejun Heo
2016-08-11  9:07   ` Roman Penyaev
2016-08-11 16:29     ` Tejun Heo [this message]
2016-08-11 17:29       ` Roman Penyaev
2016-08-15  4:34 ` [lkp] [percpu] e1bd8275fa: xfstests.generic.323.fail kernel test robot

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