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Date: Sun, 6 Apr 2003 18:21:23 -0700
From: Andrew Morton <akpm@digeo.com>
To: Zwane Mwaikambo <zwane@linuxpower.ca>
Cc: felipe_alfaro@linuxmail.org, linux-kernel@vger.kernel.org,
       andrew.grover@intel.com
Subject: Re: 2.5.66-bk12: acpi_power_off: sleeping function called from
 illegal context
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Zwane Mwaikambo <zwane@linuxpower.ca> wrote:
>
> -	if (in_atomic())
> +	if (in_atomic() || irqs_disabled())
>  		timeout = 0;

Andy, why does the ACPI code have this test?

Is it to determine whether a caller of this functon is currently holding a
spinlock?  If so then it will only work on a preemptible kernel.

A non-preempt kernel will not increment preempt_count() when it takes a
spinlock and ACPI could mistakenly schedule away and cause a system deadlock.