linux-kernel - Re: drivers: Probable misuses of ||

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Message-ID: <20120504221333.GU14230@opensource.wolfsonmicro.com>
Date:	Fri, 4 May 2012 23:13:33 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Mauro Carvalho Chehab <mchehab@...radead.org>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: drivers: Probable misuses of ||

On Fri, May 04, 2012 at 03:09:38PM -0700, Joe Perches wrote:
> On Fri, 2012-05-04 at 23:02 +0100, Mark Brown wrote:
> > On Fri, May 04, 2012 at 02:54:37PM -0700, Joe Perches wrote:

> > > > drivers/media/rc/fintek-cir.c:	if ((chip != 0x0408) || (chip != 0x0804))

> > It'd probably help if you were to supply more analysis as to what the
> > issues you think you're seeing are - in the cases quoted above
> > (especially the last one) there's no obvious bug without further
> > analysis.

> Likely the || should be &&.

> 	if (val != foo || test != bar)

> is always true when foo != bar

Right, but you need to look at the code and explain why this is a
problem.  For example, the case I've left quoted above reads to me like
the intention is "If the chip isn't one I know doesn't like this then
let's do it" which is a perfectly sensible thing to write.

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