linux-kernel - Re: [PATCH 1/1] spi: Remove unused definitions

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Message-ID: <20140820215618.GA744@amd>
Date:	Wed, 20 Aug 2014 23:56:18 +0200
From:	Pavel Machek <pavel@....cz>
To:	Valdis.Kletnieks@...edu
Cc:	linux-fsdevel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Nick Krause <xerofoiffy@...il.com>,
	Richard Weinberger <richard.weinberger@...il.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] spi: Remove unused definitions

On Wed 2014-08-20 17:12:42, Valdis.Kletnieks@...edu wrote:
> (Adding Al Viro and linux-fsdevel, dropping Mark Brown and the SPI list, because this is
> heading off in a different direction now)
> 
> On Wed, 20 Aug 2014 22:26:02 +0200, Pavel Machek said:
> > On Wed 2014-08-06 14:27:20, Valdis.Kletnieks@...edu wrote:
> > > On Wed, 06 Aug 2014 13:53:17 -0400, Nick Krause said:
> > > > Remove unused definition which cause the following warnings
> > > >
> > > > drivers/spi/spi-omap-100k.c:73:0: warning: "WRITE" redefined [enabled by default]
> > > > include/linux/fs.h:193:0: note: this is the location of the previous definition
> > > > drivers/spi/spi-omap-100k.c:74:0: warning: "READ" redefined [enabled by default]
> > > > include/linux/fs.h:192:0: note: this is the location of the previous definition
> > >
> > > > -#define WRITE 0
> > > > -#define READ  1
> > >
> > > NAK.  Full stop.  These are potentially used in an inner macro someplace, and by
> > > removing these, the conflicting values from fs.h will be used instead.
> > >
> > > #define READ                    0
> > > #define WRITE                   RW_MASK
> > >
> > > So if there *is* a use in an inner macro, you just screwed the pooch
> > > and introduced a bug in this "clean up" - somebody will be expecting to see
> > > a 0 for a READ, and will receive a 1 instead.  This can't end well.
> >
> > Actually.. having macros called READ and WRITE in fs.h is already something I'd say
> > can't end well. Can we rename those?
> 
> I had the same thought, but other than a test rename to XYZZY_READ and PLUGH_WRITE
> and doing a 'make allmodconfig' and seeing what throws an error, I'm not sure how
> to track down all the users.  On my fairly stripped-down .config, I have:
> 
> [/usr/src/linux-next] find * -name '.*.cmd' | wc -l
> 4671
> [/usr/src/linux-next] find * -name '.*.cmd' | xargs grep include/linux/fs.h | wc -l
> 2339
> 
> Which is telling me that pretty much half the world ends up including fs.h indirectly.

Yep.

I hope sh math emulator does not include fs.h.

arch/sh/math-emu/math.c:#define READ(d,a)       ({if(get_user(d, (typeof (d)*)a)

> Now for the mandatory bikeshedding:
> 
> What do we want to rename them to? :)

REQ_ prefix would fit there well, I'd say.
									Pavel


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