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Subject: Re: [PATCH] [RFC] io_uring: warning about unused-but-set parameter
To:     Arnd Bergmann <arnd@kernel.org>,
        Pavel Begunkov <asml.silence@gmail.com>
Cc:     Arnd Bergmann <arnd@arndb.de>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20210920121352.93063-1-arnd@kernel.org>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <5458ee0e-573c-fbc4-5cdd-5f319f78e3cb@kernel.dk>
Date:   Mon, 20 Sep 2021 17:08:05 -0600
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On 9/20/21 6:13 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When enabling -Wunused warnings by building with W=1, I get an
> instance of the -Wunused-but-set-parameter warning in the io_uring code:
> 
> fs/io_uring.c: In function 'io_queue_async_work':
> fs/io_uring.c:1445:61: error: parameter 'locked' set but not used [-Werror=unused-but-set-parameter]
>  1445 | static void io_queue_async_work(struct io_kiocb *req, bool *locked)
>       |                                                       ~~~~~~^~~~~~
> 
> There are very few warnings of this type, so it would be nice to enable
> this by default and fix all the existing instances. I was almost
> done, but this was added recently as a precaution to prevent code
> from using the parameter, which could be done by either removing
> the initialization, or by adding a (fake) use of the variable, which
> I do here with the cast to void.

I would just rename the argument here 'dont_use' or something like that,
that should be enough of a signal for future cases that it should need
extra consideration.

-- 
Jens Axboe