From: Guenter Roeck <linux@roeck-us.net>
To: Joe Perches <joe@perches.com>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
Zhang Rui <rui.zhang@intel.com>,
Eduardo Valentin <eduardo.valentin@ti.com>
Subject: Re: [PATCH] thermal: Fix KELVIN_TO_CELSIUS macro
Date: Sun, 23 Mar 2014 22:30:47 -0700 [thread overview]
Message-ID: <532FC307.7050202@roeck-us.net> (raw)
In-Reply-To: <1395635132.13968.40.camel@joe-AO722>
On 03/23/2014 09:25 PM, Joe Perches wrote:
> On Sun, 2014-03-23 at 21:14 -0700, Guenter Roeck wrote:
>> It is always a good idea to use paranthesis around macro parameters
>> to avoid undesired side effects.
>>
>> In this specific case, KELVIN_TO_CELSIUS() is used in
>> drivers/platform/x86/asus-wmi.c with parameter "value & 0xFFFF",
>> which due to operator evaluation order causes more or less random
>> results.
>
> Maybe it's better to use a statement expression to avoid
> multiple calculations of t
>
> Maybe;
>
> #define KELVIN_TO_CELSIUS(t) \
> ({ \
> long _t = (long)(t) - 2732; \
> _t >= 0 ? (_t + 5) / 10 : (_t - 5) / 10; \
> })
>
>
Possibly, but I only want to have a bug fixed which should possibly be applied
to -stable at some point. As such, I prefer the minimalistic approach.
Anything more fancy on top of that can be submitted as separate patch.
Guenter
next prev parent reply other threads:[~2014-03-24 5:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-24 4:14 [PATCH] thermal: Fix KELVIN_TO_CELSIUS macro Guenter Roeck
2014-03-24 4:25 ` Joe Perches
2014-03-24 5:30 ` Guenter Roeck [this message]
2014-04-03 2:40 ` Zhang Rui
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=532FC307.7050202@roeck-us.net \
--to=linux@roeck-us.net \
--cc=eduardo.valentin@ti.com \
--cc=joe@perches.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rui.zhang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).