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From: Keith Owens <kaos@ocs.com.au>
To: linux-kernel@vger.kernel.org
Subject: i386 IPI handlers running with hardirq_count == 0
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Date: Thu, 29 Jun 2006 19:01:17 +1000
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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()?