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Date: Thu, 21 May 2009 16:36:41 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Joe Perches <joe@perches.com>
CC: Randy Dunlap <randy.dunlap@oracle.com>, linux-kernel@vger.kernel.org,
       cpufreq@vger.kernel.org, Dave Jones <davej@redhat.com>,
       Greg Kroah-Hartman <gregkh@suse.de>, Ingo Molnar <mingo@redhat.com>,
       x86@vger.kernel.org, Len Brown <len.brown@intel.com>,
       Mike Travis <travis@sgi.com>, Rusty Russell <rusty@rustcorp.com.au>,
       Thomas Gleixner <tglx@linutronix.de>,
       Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Subject: Re: [PATCH 1/3] kernel.h: Add DO_ONCE statement expression macro
References: <cover.1242943463.git.joe@perches.com>	 <7b063fda0675875d51a5da49f59e89520d025eee.1242943463.git.joe@perches.com>	 <4A15E36E.9080501@oracle.com> <1242948762.3373.143.camel@Joe-Laptop.home>
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Joe Perches wrote:
> 
> Add a DO_ONCE statement expression analogous to printk_once
> that executes any arbitrary statement exactly once.
> 

If you're truly going to make that guarantee you should use an atomic
test and set.

	-hpa