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Date: Thu, 29 Jun 2006 02:18:00 -0700
From: Andrew Morton <akpm@osdl.org>
To: Keith Owens <kaos@ocs.com.au>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: i386 IPI handlers running with hardirq_count == 0
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On Thu, 29 Jun 2006 19:01:17 +1000
Keith Owens <kaos@ocs.com.au> wrote:

> Macro arch/i386/kernel/entry.S::BUILD_INTERRUPT generates the code to
> handle an IPI and call the corresponding smp_<name> C code.
> BUILD_INTERRUPT does not update the hardirq_count for the interrupted
> task, that is left to the C code.  Some of the C IPI handlers do not
> call irq_enter(), so they are running in IRQ context but the
> hardirq_count field does not reflect this.  For example,
> smp_invalidate_interrupt does not set the hardirq count.
> 
> What is the best fix, change BUILD_INTERRUPT to adjust the hardirq
> count or audit all the C handlers to ensure that they call irq_enter()?
> 

The IPI handlers run with IRQs disabled.  Do we need a fix?