linux-kernel - Re: [PATCH linux-next] s390:fix Coccinelle warnings

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Date:   Mon, 23 Aug 2021 20:07:57 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     jing yangyang <cgel.zte@...il.com>
Cc:     Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Vineeth Vijayan <vneethv@...ux.ibm.com>,
        Jiapeng Zhong <abaci-bugfix@...ux.alibaba.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        jing yangyang <jing.yangyang@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: Re: [PATCH linux-next] s390:fix Coccinelle warnings

On Thu, Aug 19, 2021 at 07:51:59PM -0700, jing yangyang wrote:
> WARNING !A || A && B is equivalent to !A || B
> 
> This issue was detected with the help of Coccinelle.
> 
> Reported-by: Zeal Robot <zealci@....com.cn>
> Signed-off-by: jing yangyang <jing.yangyang@....com.cn>
> ---
>  arch/s390/include/asm/scsw.h | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/include/asm/scsw.h b/arch/s390/include/asm/scsw.h
> index a7c3ccf..754122d 100644
> --- a/arch/s390/include/asm/scsw.h
> +++ b/arch/s390/include/asm/scsw.h
> @@ -691,9 +691,8 @@ static inline int scsw_tm_is_valid_pno(union scsw *scsw)
>  {
>  	return (scsw->tm.fctl != 0) &&
>  	       (scsw->tm.stctl & SCSW_STCTL_STATUS_PEND) &&
> -	       (!(scsw->tm.stctl & SCSW_STCTL_INTER_STATUS) ||
> -		 ((scsw->tm.stctl & SCSW_STCTL_INTER_STATUS) &&
> -		  (scsw->tm.actl & SCSW_ACTL_SUSPENDED)));
> +		(!(scsw->tm.stctl & SCSW_STCTL_INTER_STATUS) ||
> +		(scsw->tm.actl & SCSW_ACTL_SUSPENDED));

This turns something unreadable into something else which is
unreadable. It's up to Vineeth to decide what to do with this.

However I'd prefer if this would be changed into something readable,
maybe as addon patch, like e.g.:

static inline bool scsw_tm_is_valid_pno(union scsw *scsw)
{
	if (scsw->tm.fctl == 0)
		return false;
	if (!(scsw->tm.stctl & SCSW_STCTL_STATUS_PEND))
		return false;
	if (!(scsw->tm.stctl & SCSW_STCTL_INTER_STATUS))
		return false;
	if (scsw->tm.actl & SCSW_ACTL_SUSPENDED)
		return false;
	return true;
}

Chances are that the above is wrong... it's just to illustrate ;)