linux-kernel - Re: [PATCH v2] platform/x86: drop unneeded assignment in host_control

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Date:   Wed, 19 May 2021 15:42:34 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Yang Li <yang.lee@...ux.alibaba.com>
Cc:     stuart.w.hayes@...il.com, mgross@...ux.intel.com,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] platform/x86: drop unneeded assignment in
 host_control_smi()

Hi,

On 5/12/21 10:57 AM, Yang Li wrote:
> Making '==' operation with ESM_STATUS_CMD_UNSUCCESSFUL directly
> after calling the function inb() is more efficient, so assignment
> to 'cmd_status' is redundant.
> 
> Eliminate the following clang_analyzer warning:
> drivers/platform/x86/dell/dcdbas.c:397:11: warning: Although the value
> stored to 'cmd_status' is used in the enclosing expression, the value
> is never actually read from 'cmd_status'
> 
> No functional change.
> 
> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Yang Li <yang.lee@...ux.alibaba.com>

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans

> ---
> 
> Change in v2
> --According to Hans's suggestion, store the inb() value into the s8.
> https://lore.kernel.org/patchwork/patch/1419026/
> 
>  drivers/platform/x86/dell/dcdbas.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell/dcdbas.c b/drivers/platform/x86/dell/dcdbas.c
> index d513a59..28447c1 100644
> --- a/drivers/platform/x86/dell/dcdbas.c
> +++ b/drivers/platform/x86/dell/dcdbas.c
> @@ -394,8 +394,7 @@ static int host_control_smi(void)
>  
>  		/* wait a few to see if it executed */
>  		num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING;
> -		while ((cmd_status = inb(PCAT_APM_STATUS_PORT))
> -		       == ESM_STATUS_CMD_UNSUCCESSFUL) {
> +		while ((s8)inb(PCAT_APM_STATUS_PORT) == ESM_STATUS_CMD_UNSUCCESSFUL) {
>  			num_ticks--;
>  			if (num_ticks == EXPIRED_TIMER)
>  				return -ETIME;
>