linux-kernel - Re: [PATCH] pcmcia/cm4000: remove useless variable tmp

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Date:   Tue, 21 Jan 2020 17:24:59 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Alex Shi <alex.shi@...ux.alibaba.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Harald Welte <laforge@...monks.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pcmcia/cm4000: remove useless variable tmp

On Tue, Jan 21, 2020 at 05:53:53PM +0800, Alex Shi wrote:
> 
> 
> 在 2020/1/21 下午5:08, Arnd Bergmann 写道:
> > On Tue, Jan 21, 2020 at 9:50 AM Alex Shi <alex.shi@...ux.alibaba.com> wrote:
> >>
> >> No one care the value of 'tmp' in func cmm_write. better to remove it.
> > 
> > Hi Alex,
> > 
> >> @@ -1146,7 +1145,7 @@ static ssize_t cmm_write(struct file *filp, const char __user *buf,
> >>         set_cardparameter(dev);
> >>
> >>         /* dummy read, reset flag procedure received */
> >> -       tmp = inb(REG_FLAGS1(iobase));
> >> +       inb(REG_FLAGS1(iobase));
> > 
> > I think this may cause warnings on some architectures, when inb() is a macro
> > that just turns into a pointer dereference. You could write it as
> > 
> >      (void)inb(REG_FLAGS1(iobase));
> > 
> > which would not warn anywhere.
> > 
> >       Arnd
> > 
> 
> Thanks a lot Arnd!
> 
> 
> >From 9e54770c6911ae7da7d2f74774bbef019e459bc9 Mon Sep 17 00:00:00 2001
> From: Alex Shi <alex.shi@...ux.alibaba.com>
> Date: Fri, 17 Jan 2020 09:10:47 +0800
> Subject: [PATCH v2] pcmcia/cm4000: remove useless variable tmp
> 
> No one care the value of 'tmp' in func cmm_write. better to remove it.
> 
> Arnd Bergmann pointed just remove may cause warning in some arch where 
> inb is macro, and suggest add a cast '(void)' for this. Thanks!
> 
> Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
> Cc: Harald Welte <laforge@...monks.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/char/pcmcia/cm4000_cs.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/char/pcmcia/cm4000_cs.c b/drivers/char/pcmcia/cm4000_cs.c
> index 15bf585af5d3..0f55bed6c71f 100644
> --- a/drivers/char/pcmcia/cm4000_cs.c
> +++ b/drivers/char/pcmcia/cm4000_cs.c
> @@ -1048,7 +1048,6 @@ static ssize_t cmm_write(struct file *filp, const char __user *buf,
>  	struct cm4000_dev *dev = filp->private_data;
>  	unsigned int iobase = dev->p_dev->resource[0]->start;
>  	unsigned short s;
> -	unsigned char tmp;
>  	unsigned char infolen;
>  	unsigned char sendT0;
>  	unsigned short nsend;
> @@ -1146,7 +1145,7 @@ static ssize_t cmm_write(struct file *filp, const char __user *buf,
>  	set_cardparameter(dev);
>  
>  	/* dummy read, reset flag procedure received */
> -	tmp = inb(REG_FLAGS1(iobase));
> +	(void)inb(REG_FLAGS1(iobase));

That's horrid, just keep tmp :)