commit: 3935e89505a1c3ab3f3b0c7ef0eae54124f48905
From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <[email protected]>
Date: Wed, 19 Dec 2012 20:51:31 +0100
Subject: watchdog: Fix disable/enable regression
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Commit 8d4516904b39 ("watchdog: Fix CPU hotplug regression") causes an
oops or hard lockup when doing
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /proc/sys/kernel/nmi_watchdog
and the kernel is booted with nmi_watchdog=1 (default)
Running laptop-mode-tools and disconnecting/connecting AC power will
cause this to trigger, making it a common failure scenario on laptops.
Instead of bailing out of watchdog_disable() when !watchdog_enabled we
can initialize the hrtimer regardless of watchdog_enabled status. This
makes it safe to call watchdog_disable() in the nmi_watchdog=0 case,
without the negative effect on the enabled => disabled => enabled case.
All these tests pass with this patch:
- nmi_watchdog=1
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /proc/sys/kernel/nmi_watchdog
- nmi_watchdog=0
echo 0 > /sys/devices/system/cpu/cpu1/online
- nmi_watchdog=0
echo mem > /sys/power/state
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=51661
Cc: <[email protected]> # v3.7
Cc: Norbert Warmuth <[email protected]>
Cc: Joseph Salisbury <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Bjørn Mork <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
---
kernel/watchdog.c | 11 ++++-------
1 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 997c6a1..75a2ab3 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -344,6 +344,10 @@ static void watchdog_enable(unsigned int cpu)
{
struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
+ /* kick off the timer for the hardlockup detector */
+ hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ hrtimer->function = watchdog_timer_fn;
+
if (!watchdog_enabled) {
kthread_park(current);
return;
@@ -352,10 +356,6 @@ static void watchdog_enable(unsigned int cpu)
/* Enable the perf event */
watchdog_nmi_enable(cpu);
- /* kick off the timer for the hardlockup detector */
- hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
- hrtimer->function = watchdog_timer_fn;
-
/* done here because hrtimer_start can only pin to smp_processor_id() */
hrtimer_start(hrtimer, ns_to_ktime(sample_period),
HRTIMER_MODE_REL_PINNED);
@@ -369,9 +369,6 @@ static void watchdog_disable(unsigned int cpu)
{
struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
- if (!watchdog_enabled)
- return;
-
watchdog_set_prio(SCHED_NORMAL, 0);
hrtimer_cancel(hrtimer);
/* disable the perf event */
--
1.7.3.4
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