linux-kernel - Re: [PATCH] hpet: Drop unused variable 'm' in hpet

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Date:   Thu, 25 Jul 2019 14:34:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     Clemens Ladisch <clemens@...isch.de>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hpet: Drop unused variable 'm' in hpet_interrupt()

On Thu, Jul 11, 2019 at 09:32:38PM +0800, Kefeng Wang wrote:
> ../drivers/char/hpet.c:159:17: warning: variable ‘m’ set but not used
> [-Wunused-but-set-variable]
>    unsigned long m, t, mc, base, k;
>                  ^
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> ---
>  drivers/char/hpet.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
> index 9ac6671bb514..039398cb14aa 100644
> --- a/drivers/char/hpet.c
> +++ b/drivers/char/hpet.c
> @@ -156,12 +156,11 @@ static irqreturn_t hpet_interrupt(int irq, void *data)
>  	 * This has the effect of treating non-periodic like periodic.
>  	 */
>  	if ((devp->hd_flags & (HPET_IE | HPET_PERIODIC)) == HPET_IE) {
> -		unsigned long m, t, mc, base, k;
> +		unsigned long t, mc, base, k;
>  		struct hpet __iomem *hpet = devp->hd_hpet;
>  		struct hpets *hpetp = devp->hd_hpets;
>  
>  		t = devp->hd_ireqfreq;
> -		m = read_counter(&devp->hd_timer->hpet_compare);

Are you sure this is ok to remove?  You are reading from the hardware
here, and often times that is required in order to achive something
else.

So this function does not "do nothing", be careful and you will have to
test this before I can take it.

thanks,

greg k-h