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Date:   Wed, 9 Feb 2022 09:40:41 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Namhyung Kim <namhyung@kernel.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>,
        "Paul E. McKenney" <paul.mckenney@linaro.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Radoslaw Burny <rburny@google.com>
Subject: Re: [PATCH 11/12] locking/mutex: Revive fast functions for
 CONFIG_LOCK_TRACEPOINTS
Message-ID: <20220209084041.GJ23216@worktop.programming.kicks-ass.net>
References: <20220208184208.79303-1-namhyung@kernel.org>
 <20220208184208.79303-12-namhyung@kernel.org>
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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.