linux-kernel - Re: [PATCH 3/3] lib/percpu-refcount: drain ->release() in perpcu_ref

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Message-ID: <Y5tRNoL5lbwy91Xs@slm.duckdns.org>
Date:   Thu, 15 Dec 2022 06:54:14 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Zhong Jinghua <zhongjinghua@...wei.com>,
        Yu Kuai <yukuai3@...wei.com>, Dennis Zhou <dennis@...nel.org>
Subject: Re: [PATCH 3/3] lib/percpu-refcount: drain ->release() in
 perpcu_ref_exit()

On Wed, Dec 14, 2022 at 10:51:01AM +0800, Ming Lei wrote:
> The pattern of wait_event(percpu_ref_is_zero()) has been used in several
> kernel components, and this way actually has the following risk:

I'd much rather see those components updated to wait for notification from
->release rather than doing this or update percpu_ref_is_zero() to wait for
->release() to finish.

Thanks.

-- 
tejun