linux-kernel - Re: [(RT RFC) PATCH v2 5/9] adaptive real-time lock support

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Date:	Tue, 26 Feb 2008 19:06:43 +0100
From:	Pavel Machek <pavel@....cz>
To:	Gregory Haskins <ghaskins@...ell.com>
Cc:	a.p.zijlstra@...llo.nl, mingo@...e.hu, bill.huey@...il.com,
	rostedt@...dmis.org, kevin@...man.org, tglx@...utronix.de,
	cminyard@...sta.com, dsingleton@...sta.com, dwalker@...sta.com,
	Moiz Kohari <MKohari@...ell.com>,
	Peter Morreale <PMorreale@...ell.com>,
	Sven Dietrich <SDietrich@...ell.com>, dsaxena@...xity.net,
	acme@...hat.com, ak@...e.de, gregkh@...e.de, npiggin@...e.de,
	linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: [(RT RFC) PATCH v2 5/9] adaptive real-time lock support

On Tue 2008-02-26 08:03:43, Gregory Haskins wrote:
> >>> On Mon, Feb 25, 2008 at  5:03 PM, in message
> <20080225220313.GG2659@....ucw.cz>, Pavel Machek <pavel@....cz> wrote: 
> 
> >> +static inline void
> >> +prepare_adaptive_wait(struct rt_mutex *lock, struct adaptive_waiter 
> > *adaptive)
> > ...
> >> +#define prepare_adaptive_wait(lock, busy) {}
> > 
> > This is evil. Use empty inline function instead (same for the other
> > function, there you can maybe get away with it).
> > 
> 
> I went to implement your suggested change and I remembered why I did it this way:  I wanted a macro so that the "struct adaptive_waiter" local variable will fall away without an #ifdef in the main body of code.  So I have left this logic alone for now.

Hmm, but inline function will allow dead code elimination,  too, no?

Anyway non-evil way to do it with macro is 

#define prepare_adaptive_wait(lock, busy) do {} while (0)

...that behaves properly in complex statements.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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