linux-kernel - Re: [PATCH] add function spin_event

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Message-ID: <adaiqmmf87v.fsf@cisco.com>
Date:	Fri, 06 Mar 2009 17:11:00 -0800
From:	Roland Dreier <rdreier@...co.com>
To:	Timur Tabi <timur@...escale.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] add function spin_event_timeout()

 > The function spin_event_timeout() takes a condition and timeout value
 > (in jiffies) as parameters.  It spins until either the condition is true
 > or the timeout expires.  It returns non-zero if the condition is true,
 > zero otherwise.

What's the motivation for this?  Where do you plan to use it?

 > + * The function returns non-zero if the @condition evaluated to true, or

It's not a function but rather a macro.

 > +#define spin_event_timeout(condition, timeout)		\
 > +({							\
 > +	long __timeout = jiffies + (timeout);		\
 > +	while (!(condition) && (jiffies < __timeout));	\
 > +	(condition);					\
 > +})

If we're going to make this core infrastructure, it seems we should
implement it with all best practices... eg I would think the while loop
should include cpu_relax().
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