linux-kernel - Re: [PATCH v5 03/18] rcu/tree: Use READ_ONCE() for lockless read of rnp->qsmask

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Message-ID: <ecd0497e-5623-0bf9-0160-79dca921a0a7@joelfernandes.org>
Date:   Tue, 6 Sep 2022 18:31:59 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Boqun Feng <boqun.feng@...il.com>
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
        rushikesh.s.kadam@...el.com, urezki@...il.com,
        neeraj.iitr10@...il.com, frederic@...nel.org, paulmck@...nel.org,
        rostedt@...dmis.org, vineeth@...byteword.org
Subject: Re: [PATCH v5 03/18] rcu/tree: Use READ_ONCE() for lockless read of
 rnp->qsmask



On 9/6/2022 6:26 PM, Boqun Feng wrote:
> On Thu, Sep 01, 2022 at 10:17:05PM +0000, Joel Fernandes (Google) wrote:
>> The rnp->qsmask is locklessly accessed from rcutree_dying_cpu(). This
>> may help avoid load/store tearing due to concurrent access, KCSAN
> 
> Nit: you can avoid only load tearing with READ_ONCE().
> 

I modified it as you suggested for the next revision, thanks.