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From:   Yuyang Du <duyuyang@gmail.com>
Date:   Wed, 17 Jul 2019 13:32:58 +0800
Message-ID: <CAHttsrb+vg-E2HpQDTKnf7Xkg03-wd2YEOAWaVCDzdeOASPcPQ@mail.gmail.com>
Subject: Re: [PATCH] locking/lockdep: hide unused 'class' variable
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Qian Cai <cai@lca.pw>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Bart Van Assche <bvanassche@acm.org>,
        Waiman Long <longman@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>
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Whoops..... Thanks.

On Mon, 15 Jul 2019 at 17:28, Arnd Bergmann <arnd@arndb.de> wrote:
>
> The usage is now hidden in an #ifdef, so we need to move
> the variable itself in there as well to avoid this warning:
>
> kernel/locking/lockdep_proc.c:203:21: error: unused variable 'class' [-Werror,-Wunused-variable]
>
> Fixes: 68d41d8c94a3 ("locking/lockdep: Fix lock used or unused stats error")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  kernel/locking/lockdep_proc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
> index 65b6a1600c8f..bda006f8a88b 100644
> --- a/kernel/locking/lockdep_proc.c
> +++ b/kernel/locking/lockdep_proc.c
> @@ -200,7 +200,6 @@ static void lockdep_stats_debug_show(struct seq_file *m)
>
>  static int lockdep_stats_show(struct seq_file *m, void *v)
>  {
> -       struct lock_class *class;
>         unsigned long nr_unused = 0, nr_uncategorized = 0,
>                       nr_irq_safe = 0, nr_irq_unsafe = 0,
>                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
> @@ -211,6 +210,8 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
>                       sum_forward_deps = 0;
>
>  #ifdef CONFIG_PROVE_LOCKING
> +       struct lock_class *class;
> +
>         list_for_each_entry(class, &all_lock_classes, lock_entry) {
>
>                 if (class->usage_mask == 0)
> --
> 2.20.0
>