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Date: Fri, 14 Jan 2005 23:40:26 -0800
From: Andrew Morton <akpm@osdl.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: ak@suse.de, manpreet@fabric7.com, linux-kernel@vger.kernel.org,
       discuss@x86-64.org
Subject: Re: [PATCH] i386/x86-64: Fix timer SMP bootup race
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Rusty Russell <rusty@rustcorp.com.au> wrote:
>
>   static inline void do_timer_interrupt_hook(struct pt_regs *regs)
>   {
>  -	do_timer(regs);
>  +	/* i386 brings up CPU before core is setup. */
>  +	if (unlikely(!cpu_online(smp_processor_id())))
>  +		jiffies64++;
>  +	else
>  +		do_timer(regs);

I thik I preferred Andi's approach - it adds code which is largely dropped
from the memory.  This patch adds a test-n-branch to every timer interrupt..