From f8b5035b9abd01b52ec6416f0c6bade7e603742c Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 16 Feb 2007 01:28:09 -0800
Subject: [PATCH] [PATCH] i386 prepare nmi watchdog for dynticks
The NMI watchdog implementation assumes that the local APIC timer interrupt is
happening. This assumption is not longer true when high resolution timers and
dynamic ticks come into play, as they may switch off the local APIC timer
completely. Take the PIT/HPET interrupts into account too, to avoid false
positives.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/i386/kernel/nmi.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index 5d8a07c202817..821df34d2b3a3 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -23,6 +23,7 @@
#include <linux/dmi.h>
#include <linux/kprobes.h>
#include <linux/cpumask.h>
+#include <linux/kernel_stat.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -973,9 +974,13 @@ __kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
cpu_clear(cpu, backtrace_mask);
}
- sum = per_cpu(irq_stat, cpu).apic_timer_irqs;
+ /*
+ * Take the local apic timer and PIT/HPET into account. We don't
+ * know which one is active, when we have highres/dyntick on
+ */
+ sum = per_cpu(irq_stat, cpu).apic_timer_irqs + kstat_irqs(0);
- /* if the apic timer isn't firing, this cpu isn't doing much */
+ /* if the none of the timers isn't firing, this cpu isn't doing much */
if (!touched && last_irq_sums[cpu] == sum) {
/*
* Ayiee, looks like this CPU is stuck ...
--
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