linux-kernel - Re: [PATCH] locking/lockdep: Correct calling tracepoints

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Date:   Wed, 12 May 2021 14:37:12 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] locking/lockdep: Correct calling tracepoints

On Wed, May 12, 2021 at 08:09:37PM +0800, Leo Yan wrote:
> The commit eb1f00237aca ("lockdep,trace: Expose tracepoints") reverses
> tracepoints for lock_contended() and lock_acquired(), thus the ftrace
> log shows the wrong locking sequence that "acquired" event is prior to
> "contended" event:
> 
>   <idle>-0       [001] d.s3 20803.501685: lock_acquire: 0000000008b91ab4 &sg_policy->update_lock
>   <idle>-0       [001] d.s3 20803.501686: lock_acquired: 0000000008b91ab4 &sg_policy->update_lock
>   <idle>-0       [001] d.s3 20803.501689: lock_contended: 0000000008b91ab4 &sg_policy->update_lock
>   <idle>-0       [001] d.s3 20803.501690: lock_release: 0000000008b91ab4 &sg_policy->update_lock
> 
> This patch fixes calling tracepoints for lock_contended() and
> lock_acquired().
> 
> Fixes: eb1f00237aca ("lockdep,trace: Expose tracepoints")
> Signed-off-by: Leo Yan <leo.yan@...aro.org>

No idea how that happened, curious. Thanks for fixing though!