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References: <20210616144210.278662-1-sxwjean@me.com> <20210616144210.278662-2-sxwjean@me.com>
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From:   Xiongwei Song <sxwjean@gmail.com>
Date:   Thu, 17 Jun 2021 10:22:30 +0800
Message-ID: <CAEVVKH8n5ntPVOP=X9bPGoK4xdE-Z-XHKSFsoGOaLpke+uZoqg@mail.gmail.com>
Subject: Re: [PATCH] locking/lockdep: print possible warning after counting deps
To:     Xiongwei Song <sxwjean@me.com>
Cc:     peterz@infradead.org, mingo@redhat.com, will@kernel.org,
        longman@redhat.com, Boqun Feng <boqun.feng@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Please ignore this patch. I will resend as  Longman's suggestions.
Please see https://lkml.org/lkml/2021/6/16/949.

Regards,
Xiongwei


On Wed, Jun 16, 2021 at 10:42 PM Xiongwei Song <sxwjean@me.com> wrote:
>
> From: Xiongwei Song <sxwjean@gmail.com>
>
> The graph walk might hit error when counting dependencies. Once the
> return value is negative, print a warning to reminder users.
>
> Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
> ---
>  kernel/locking/lockdep.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 7641bd407239..074fd6418c20 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -2028,8 +2028,12 @@ static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
>  {
>         unsigned long  count = 0;
>         struct lock_list *target_entry;
> +       enum bfs_result ret;
> +
> +       ret = __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
>
> -       __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
> +       if (unlikely(bfs_error(ret)))
> +               print_bfs_bug(ret);
>
>         return count;
>  }
> @@ -2053,8 +2057,12 @@ static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
>  {
>         unsigned long  count = 0;
>         struct lock_list *target_entry;
> +       enum bfs_result ret;
> +
> +       ret = __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
>
> -       __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
> +       if (unlikely(bfs_error(ret)))
> +               print_bfs_bug(ret);
>
>         return count;
>  }
> --
> 2.30.2
>