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From:   Waiman Long <llong@redhat.com>
Subject: Re: [PATCH] docs: lockdep-design: correct the notation for writer
To:     Xiongwei Song <sxwjean@me.com>, peterz@infradead.org,
        mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com,
        corbet@lwn.net
Cc:     linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        Xiongwei Song <sxwjean@gmail.com>
References: <1621578594-13237-1-git-send-email-sxwjean@me.com>
Message-ID: <e0c0302f-e63f-7eba-872b-85e21b0b1622@redhat.com>
Date:   Fri, 21 May 2021 11:17:32 -0400
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On 5/21/21 2:29 AM, Xiongwei Song wrote:
> From: Xiongwei Song <sxwjean@gmail.com>
>
> The block condition matrix is using 'E' as the writer noation here, so it
> would be better to use 'E' as the reminder rather than 'W'.
>
> Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
> ---
>   Documentation/locking/lockdep-design.rst | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/locking/lockdep-design.rst b/Documentation/locking/lockdep-design.rst
> index 9f3cfca..c3b923a 100644
> --- a/Documentation/locking/lockdep-design.rst
> +++ b/Documentation/locking/lockdep-design.rst
> @@ -462,7 +462,7 @@ Block condition matrix, Y means the row blocks the column, and N means otherwise
>   	| R | Y | Y | N |
>   	+---+---+---+---+
>   
> -	(W: writers, r: non-recursive readers, R: recursive readers)
> +	(E: writers, r: non-recursive readers, R: recursive readers)
>   
>   
>   acquired recursively. Unlike non-recursive read locks, recursive read locks

I would say it should be the other way around. Both W and E refer to the 
same type of lockers. W emphasizes writer aspect of it and E for 
exclusive. I think we should change the block condition matrix to use W 
instead of E.

Cheers,
Longman