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Date: Thu, 2 Jun 2005 14:19:55 -0600 (MDT)
From: Zwane Mwaikambo <zwane@arm.linux.org.uk>
To: Ashok Raj <ashok.raj@intel.com>
cc: Andi Kleen <ak@muc.de>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, discuss@x86-64.org,
       Rusty Russell <rusty@rustycorp.com.au>,
       Srivattsa Vaddagiri <vatsa@in.ibm.com>
Subject: Re: [patch 2/5] x86_64: CPU hotplug support.
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On Thu, 2 Jun 2005, Ashok Raj wrote:

> @@ -445,8 +477,10 @@ void __cpuinit start_secondary(void)
>  	/*
>  	 * Allow the master to continue.
>  	 */
> +	lock_ipi_call_lock();
>  	cpu_set(smp_processor_id(), cpu_online_map);
>  	mb();
> +	unlock_ipi_call_lock();

What's that? Is this another smp_call_function race workaround? I thought 
there was an additional patch to avoid the broadcast.

> +#include <asm/nmi.h>
> +/* We don't actually take CPU down, just spin without interrupts. */
> +static inline void play_dead(void)
> +{
> +	idle_task_exit();
> +	mb();
> +	/* Ack it */
> +	__get_cpu_var(cpu_state) = CPU_DEAD;
> +
> +	local_irq_disable();
> +	while (1)
> +		safe_halt();
> +}

Might as well drop the local_irq_disable since safe_halt enables 
interrupts.

	Zwane