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Date: Sat, 23 Feb 2002 15:56:36 -0800
From: Andrew Morton <akpm@zip.com.au>
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To: Robert Love <rml@tech9.net>
CC: Roman Zippel <zippel@linux-m68k.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] only irq-safe atomic ops
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Robert Love wrote:
> 
> On Sat, 2002-02-23 at 18:13, Robert Love wrote:
> > On Sat, 2002-02-23 at 17:10, Andrew Morton wrote:
> >
> > > ooh.  me likee.
> > >
> > > #define smp_get_cpuid() ({ preempt_disable(); smp_processor_id(); })
> > > #define smp_put_cpuid() preempt_enable()
> > >
> > > Does rml likee?
> >
> > Yah, that works.
> 
> OK, I still likee, but I was just thinking, if we are going to add have
> to add something why not consider the irq-safe atomic ops?  It is
> certainly the most optimal.
> 

For the situation Victor described:

	const int cpu = smp_get_cpuid();

	per_cpu_array_foo[cpu] = per_cpu_array_bar[cpu] +
					per_cpu_array_zot[cpu];

	smp_put_cpuid();

It's a nice interface - it says "pin down and return the current
CPU ID".

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