linux-kernel - RE: [PATCH] staging: pi433: using div64_u64() instead of do

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Date:   Fri, 21 Jan 2022 13:34:19 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Jiapeng Chong' <jiapeng.chong@...ux.alibaba.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-staging@...ts.linux.dev" <linux-staging@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Abaci Robot <abaci@...ux.alibaba.com>
Subject: RE: [PATCH] staging: pi433: using div64_u64() instead of do_div()

From: Jiapeng Chong
> Sent: 21 January 2022 11:50
> Subject: [PATCH] staging: pi433: using div64_u64() instead of do_div()
> 
> Clean the following coccicheck warning:
> 
> ./drivers/staging/pi433/rf69.c:286:1-7: WARNING: do_div() does a
> 64-by-32 division, please consider using div64_u64 instead.

That is one of patchcheck's worse warnings.

You need to check the domain of the divisor, not its type.

do_div() exists to avoid expensive 64bit divides when the
divisor is small.

	David

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