Re: [PATCH 2/8] raw: Add missing annotations to raw_seq_start() and raw_seq_stop()

From: Eric Dumazet <eric.dumazet@gmail.com>
To: Jules Irenge <jbi.octave@gmail.com>, boqun.feng@gmail.com
Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Jakub Kicinski <kuba@kernel.org>
Subject: Re: [PATCH 2/8] raw: Add missing annotations to raw_seq_start() and raw_seq_stop()
Date: Tue, 10 Mar 2020 18:15:12 -0700	[thread overview]
Message-ID: <af9016d1-c224-ea61-3290-330ed0fe8d60@gmail.com> (raw)
In-Reply-To: <20200311010908.42366-3-jbi.octave@gmail.com>

On 3/10/20 6:09 PM, Jules Irenge wrote:
> Sparse reports warnings at raw_seq_start() and raw_seq_stop()
> 
> warning: context imbalance in raw_seq_start() - wrong count at exit
> warning: context imbalance in raw_seq_stop() - unexpected unlock
> 
> The root cause is the missing annotations at raw_seq_start()
> 	and raw_seq_stop()
> Add the missing __acquires(&h->lock) annotation
> Add the missing __releases(&h->lock) annotation
> 
> Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
> ---
>  net/ipv4/raw.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index 3183413ebc6c..47665919048f 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -1034,6 +1034,7 @@ static struct sock *raw_get_idx(struct seq_file *seq, loff_t pos)
>  }
>  
>  void *raw_seq_start(struct seq_file *seq, loff_t *pos)
> +	__acquires(&h->lock)

I dunno, h variable is not yet defined/declared at this point,
this looks weird.

>  {
>  	struct raw_hashinfo *h = PDE_DATA(file_inode(seq->file));
>  
> @@ -1056,6 +1057,7 @@ void *raw_seq_next(struct seq_file *seq, void *v, loff_t *pos)
>  EXPORT_SYMBOL_GPL(raw_seq_next);
>  
>  void raw_seq_stop(struct seq_file *seq, void *v)
> +	__releases(&h->lock)
>  {
>  	struct raw_hashinfo *h = PDE_DATA(file_inode(seq->file));
>  
> 