linux-kernel - Re: [PATCH] hwmon: (amc6821) Fix unsigned expression compared with zero

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Message-ID: <20221103141727.GA145042@roeck-us.net>
Date:   Thu, 3 Nov 2022 07:17:27 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     wangkailong@...i.cn, jdelvare@...e.com,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (amc6821) Fix unsigned expression compared with
 zero

On Wed, Nov 02, 2022 at 07:59:06PM -0700, Randy Dunlap wrote:
> 
> 
> On 11/2/22 19:27, wangkailong@...i.cn wrote:
> > Fix the following coccicheck warning:
> > 
> > drivers/hwmon/amc6821.c:215: WARNING: Unsigned expression compared
> > with zero: reg > 0
> > drivers/hwmon/amc6821.c:228: WARNING: Unsigned expression compared
> > with zero: reg > 0
> > 
> > Signed-off-by: KaiLong Wang <wangkailong@...i.cn>
> 
> Hm. IDGI. What's wrong with comparing an unsigned value to > 0?
> I mean, it could be == 0 or > 0.
> Please explain.

I don't get it either. The real problem with this driver is that error
returns from i2c functions are not checked. However, that problem is not
fixed by this patch. That means the patch would change behavior without
fixing the actual problem.

I wonder what kind of (broken) compiler or analyzer produces above errors.
We'll have to watch out for similar broken "fixes".

Guenter