linux-kernel - Re: [PATCH 1/5] lib: introduce call

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Date:	Tue, 11 Mar 2008 12:11:07 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Joe Perches <joe@...ches.com>
Cc:	akinobu.mita@...il.com, nickpiggin@...oo.com.au,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] lib: introduce call_once()

On Tue, 11 Mar 2008 11:56:55 -0700
Joe Perches <joe@...ches.com> wrote:

> On Tue, 2008-03-11 at 10:35 -0700, Andrew Morton wrote:
> > #define ONCE()                                              \
> >     ({                                              \
> >             static long flag;                       \
> >                                                     \
> >             return !test_and_set_bit(0, flag);      \
> >     })
> 
> test_and_set_bit takes an address

duh.

> Perhaps:
> 
> #define DO_ONCE(x) \
> 	({ static long flag; if (test_and_set_bit(0, &flag)) x; 1; })
> 
> DO_ONCE(foo);

No, that's completely unnecessary and would produce nasty-looking code. 
Take a look at some of the wait_event monstrosities we have.


I'm not sure that we need any of this once() stuff really.
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