linux-kernel - Re: [PATCH v2 3/9] bitops: Introduce a more generic BITMASK macro

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Message-ID: <1382000112.22110.103.camel@joe-AO722>
Date:	Thu, 17 Oct 2013 01:55:12 -0700
From:	Joe Perches <joe@...ches.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Chen Gong <gong.chen@...ux.intel.com>, tony.luck@...el.com,
	naveen.n.rao@...ux.vnet.ibm.com, m.chehab@...sung.com,
	arozansk@...hat.com, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Thomas Winischhofer <thomas@...ischhofer.net>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>
Subject: Re: [PATCH v2 3/9] bitops: Introduce a more generic BITMASK macro

On Thu, 2013-10-17 at 10:40 +0200, Borislav Petkov wrote:
> On Thu, Oct 17, 2013 at 01:32:30AM -0700, Joe Perches wrote:
> > On Thu, 2013-10-17 at 03:38 -0400, Chen Gong wrote:
> > > the point is we can use GENMASK like GENMASK(end_bit, start_bit) but
> > > we don't know the value of end_bit/start_bit at compile-time.
> > 
> > True.
> > 
> > The BUILD_BUG_ON idea is just to avoid people using
> > 	GENMASK(1, 2)
> 
> They'll notice the 0 pretty quickly when they test their code.
> 
> Let's add those checks only when it is really necessary and people have
> actually made that mistake repeatedly.

It's cost free to add the BUILD_BUG_ON
and perhaps you underestimate the runtime
bug checking effort,

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