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Date:   Fri, 26 May 2023 15:04:49 -0400
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Subject: Re: [RFC][PATCH 1/2] locking: Introduce __cleanup__ based guards
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To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Peter Zijlstra <peterz@infradead.org>,
        torvalds@linux-foundation.org, keescook@chromium.org,
        gregkh@linuxfoundation.org, pbonzini@redhat.com
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        ndesaulniers@google.com, mingo@redhat.com, will@kernel.org,
        boqun.feng@gmail.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, vschneid@redhat.com, paulmck@kernel.org,
        frederic@kernel.org, quic_neeraju@quicinc.com,
        joel@joelfernandes.org, josh@joshtriplett.org,
        jiangshanlai@gmail.com, qiang1.zhang@intel.com,
        rcu@vger.kernel.org, tj@kernel.org, tglx@linutronix.de
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From:   Waiman Long <longman@redhat.com>
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On 5/26/23 14:58, Mathieu Desnoyers wrote:
> On 5/26/23 14:49, Waiman Long wrote:
> [...]
>>
>> BTW, do we have a use case for double_lock_guard/double_lock_scope? I 
>> can envision a nested lock_scope inside a lock_scope, but taking 2 
>> auto locks of the same type at init time and then unlock them at exit 
>> just doesn't make sense to me.
>
> AFAIU taking both runqueue locks for source and destination runqueues 
> on migration is one use-case for double_lock_guard/scope.
>
I see. Thanks for the clarification. I forgot about that special case.

Cheers,
Longman