linux-kernel - [PATCH] watchdog: Allow touch_nmi_watchdog() to be called by acpi_os

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Message-Id: <201008260058.17876.rjw@sisk.pl>
Date:	Thu, 26 Aug 2010 00:58:17 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Len Brown <lenb@...nel.org>
Subject: [PATCH] watchdog: Allow touch_nmi_watchdog() to be called by acpi_os_stall()

From: Rafael J. Wysocki <rjw@...k.pl>

acpi_os_stall() executes touch_nmi_watchdog() that, if
CONFIG_HARDLOCKUP_DETECTOR is set,
uses __get_cpu_var() to access per-CPU variables.  This triggers the
stack dump in debug_smp_processor_id().

One way to avoid that is to use __raw_get_cpu_var() to access the
per-CPU variables in touch_nmi_watchdog().

Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 kernel/watchdog.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/kernel/watchdog.c
===================================================================
--- linux-2.6.orig/kernel/watchdog.c
+++ linux-2.6/kernel/watchdog.c
@@ -142,8 +142,8 @@ void touch_all_softlockup_watchdogs(void
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 void touch_nmi_watchdog(void)
 {
-	__get_cpu_var(watchdog_nmi_touch) = true;
-	touch_softlockup_watchdog();
+	__raw_get_cpu_var(watchdog_nmi_touch) = true;
+	__raw_get_cpu_var(watchdog_touch_ts) = 0;
 }
 EXPORT_SYMBOL(touch_nmi_watchdog);
 
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