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Date:   Tue, 8 Feb 2022 20:03:01 +0100
From:   David Sterba <dsterba@suse.cz>
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        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>, Chris Mason <clm@fb.com>,
        Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 06/12] btrfs: change lockdep class size check using
 ks->names
Message-ID: <20220208190301.GF12643@twin.jikos.cz>
Reply-To: dsterba@suse.cz
Mail-Followup-To: dsterba@suse.cz, Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        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>, Chris Mason <clm@fb.com>,
        Josef Bacik <josef@toxicpanda.com>, David Sterba <dsterba@suse.com>,
        linux-btrfs@vger.kernel.org
References: <20220208184208.79303-1-namhyung@kernel.org>
 <20220208184208.79303-7-namhyung@kernel.org>
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On Tue, Feb 08, 2022 at 10:42:02AM -0800, Namhyung Kim wrote:
> With upcoming lock tracepoints config, it'd allow some lockdep
> annotation code without enabling CONFIG_LOCKDEP actually.  In that
> config, size of the struct lock_class_key would be 0.
> 
> But it'd cause divide-by-zero in btrfs_set_buffer_lockdep_class() due
> to ARRAY_SIZE macro.  Let's change it to use ks->names[] instead.  It
> should have the same size as with ks->keys[].
> 
> Cc: Chris Mason <clm@fb.com>
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: David Sterba <dsterba@suse.com>
> Cc: linux-btrfs@vger.kernel.org
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Acked-by: David Sterba <dsterba@suse.com>