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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Wed, 9 Feb 2022 12:15:19 -0800
Message-ID: <CAM9d7cgg9dUP0hqYfrDmXT7q2T9GiJt9uthKB7wEWNnKkMPisA@mail.gmail.com>
Subject: Re: [PATCH 11/12] locking/mutex: Revive fast functions for CONFIG_LOCK_TRACEPOINTS
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Ingo Molnar <mingo@kernel.org>, Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Byungchul Park <byungchul.park@lge.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Radoslaw Burny <rburny@google.com>,
        "Paul E. McKenney" <paulmck@kernel.org>
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Hi Peter,

On Wed, Feb 9, 2022 at 12:41 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Tue, Feb 08, 2022 at 10:42:07AM -0800, Namhyung Kim wrote:
> > I'm not entirely sure why it removed the fast versions when lockdep is
> > on.  It seems easy to add the required annotation when the fast
> > version is succeeded as far as the tracpoints are concerned.
>
> IIRC it was something like, lockdep depends on MUTEX_DEBUG and that in
> turn relied on not having the fast path enabled. MUTEX_DEBUG used to
> always take the wait_lock to ensure the debug state is consistent with
> the lock state.

I see.  Thanks for the explanation!

Namhyung