linux-kernel - Re: [PATCH 6/7] cpufreq: intel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2859027.TirvIA2s2c@vostro.rjw.lan>
Date:	Wed, 11 Jun 2014 02:23:27 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Joe Perches <joe@...ches.com>
Cc:	Stratos Karafotis <stratosk@...aphore.gr>,
	Dirk Brandewie <dirk.brandewie@...il.com>,
	dirk.j.brandewie@...el.com, Viresh Kumar <viresh.kumar@...aro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/7] cpufreq: intel_pstate: Trivial code cleanup

On Tuesday, June 10, 2014 02:26:45 PM Joe Perches wrote:
> On Tue, 2014-06-10 at 23:38 +0200, Rafael J. Wysocki wrote:
> 
> > > > is.  And the result of (a * 100) / b may generally be different from
> > > > a * 100 / b for integers (if the division is carried out first).
> > > 
> > > I thought that (a * 100) / b is always equivalent to a * 100 / b.
> > 
> > I'm not actually sure if that's guaranteed by C standards.
> 
> It is.  left to right, same precedence.
> 
> > It surely
> > wasn't some time ago (when there was no formal C standard).
> 
> c89 is 25 years ago now.

Apparently, I'm old.

> > Either way, in my opinion it's better to put the parens into the expression
> > in this particular case to clearly state the intention.
> 
> I don't think so.

Of course, you're free to disagree, but I guess you'll admit that
a * b / c is generally different from b / c * a and if you see something
like this it is hard to say at first sight whether or not this is intentional
or an expression ordering bug.

Rafael

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/