linux-kernel - Re: [PATCH 13/14] iopoll: avoid -Wint-in-bool-context warning

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Date:   Fri, 14 Jul 2017 02:55:23 -0700
From:   Joe Perches <joe@...ches.com>
To:     Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        Mark Brown <broonie@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>, Guenter Roeck <linux@...ck-us.net>,
        linux-ide@...r.kernel.org, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Subject: Re: [PATCH 13/14] iopoll: avoid -Wint-in-bool-context warning

On Fri, 2017-07-14 at 11:31 +0200, Arnd Bergmann wrote:
> When we pass the result of a multiplication as the timeout, we
> can get a warning:
> 
> drivers/mmc/host/bcm2835.c:596:149: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]
> drivers/mfd/arizona-core.c:247:195: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]
> 
> This is easy to avoid by comparing the timeout to zero instead,
> making it a boolean expression.

Perhaps this is better as != 0 if the multiply is signed.

> diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
[]
> @@ -48,7 +48,8 @@
>  		(val) = op(addr); \
>  		if (cond) \
>  			break; \
> -		if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \
> +		if ((timeout_us) > 0 && \
> +		    ktime_compare(ktime_get(), timeout) > 0) { \
>  			(val) = op(addr); \
>  			break; \
>  		} \

etc...