linux-kernel - Re: [PATCH linux-next] cdrom: Remove redundant variable and its assignment.

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Message-ID: <YW4C4A5S+mjHzKN2@KernelVM>
Date:   Tue, 19 Oct 2021 00:29:46 +0100
From:   Phillip Potter <phil@...lpotter.co.uk>
To:     luo penghao <cgel.zte@...il.com>
Cc:     linux-kernel@...r.kernel.org, penghao luo <luo.penghao@....com.cn>,
        Zeal Robot <zealci@....com.cn>, linux-block@...r.kernel.org
Subject: Re: [PATCH linux-next] cdrom: Remove redundant variable and its
 assignment.

On Mon, Oct 18, 2021 at 09:08:34AM +0000, luo penghao wrote:
> From: penghao luo <luo.penghao@....com.cn>
> 
> Variable is not used in functions, and its assignment is redundant too.
> So it should be deleted.
> 
> The clang_analyzer complains as follows:
> 
> drivers/cdrom/cdrom.c:877: warning:
> 
> Although the value stored to 'ret' is used in the enclosing expression,
> the value is never actually read from 'retâ€™.
> 
> Reported-by: Zeal Robot <zealci@....com.cn>
> Signed-off-by: penghao luo <luo.penghao@....com.cn>
> ---

Dear Penghao,

Thank you for the patch, looks good, but please could I ask for a small
tweak:

>  drivers/cdrom/cdrom.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> index 89a6845..393acf4 100644
> --- a/drivers/cdrom/cdrom.c
> +++ b/drivers/cdrom/cdrom.c
> @@ -871,7 +871,7 @@ static void cdrom_mmc3_profile(struct cdrom_device_info *cdi)
>  {
>  	struct packet_command cgc;
>  	char buffer[32];
> -	int ret, mmc3_profile;
> +	int mmc3_profile;
>  
>  	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
>  
> @@ -881,7 +881,7 @@ static void cdrom_mmc3_profile(struct cdrom_device_info *cdi)
>  	cgc.cmd[8] = sizeof(buffer);		/* Allocation Length */
>  	cgc.quiet = 1;
>  
> -	if ((ret = cdi->ops->generic_packet(cdi, &cgc)))
> +	if ((cdi->ops->generic_packet(cdi, &cgc)))

We no longer need the inner-most set of parentheses now, as we are
checking the result of the expression:
cdi->ops->generic_packet(cdi, &cgc)

rather than the result of the assignment expression:
(ret = cdi->ops->generic_packet(cdi, &cgc))

Please resubmit with this change and I'd be happy to approve the patch.
Many thanks.

Regards,
Phil