Re: [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested()

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@redhat.com>,
	John Ogness <john.ogness@linutronix.de>,
	Mel Gorman <mgorman@techsingularity.net>,
	Michal Hocko <mhocko@suse.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Petr Mladek <pmladek@suse.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Waiman Long <longman@redhat.co>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested()
Date: Sat, 24 Jun 2023 15:54:12 +0900	[thread overview]
Message-ID: <d9b7c170-ed0d-5d37-e099-20d233115943@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20230623171232.892937-2-bigeasy@linutronix.de>

On 2023/06/24 2:12, Sebastian Andrzej Siewior wrote:
>  include/linux/seqlock.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
> index 3926e90279477..d778af83c8f36 100644
> --- a/include/linux/seqlock.h
> +++ b/include/linux/seqlock.h
> @@ -512,8 +512,8 @@ do {									\
>  
>  static inline void do_write_seqcount_begin_nested(seqcount_t *s, int subclass)
>  {
> -	do_raw_write_seqcount_begin(s);
>  	seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_);
> +	do_raw_write_seqcount_begin(s);
>  }
>  
>  /**

Why not to do the same on the end side?

 static inline void do_write_seqcount_end(seqcount_t *s)
 {
- 	seqcount_release(&s->dep_map, _RET_IP_);
 	do_raw_write_seqcount_end(s);
+	seqcount_release(&s->dep_map, _RET_IP_);
 }