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Subject[patch V2 03/29] lockup_detector: Provide interface to stop from poweroff()
PARISC has a a busy looping power off routine. If the watchdog is enabled
the watchdog timer will still fire, but the thread is not running, which
causes the softlockup watchdog to trigger.

Provide a interface which allows to turn the watchdog off.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-parisc@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Helge Deller <deller@gmx.de>
Link: http://lkml.kernel.org/r/20170831073053.202164272@linutronix.de

---
include/linux/nmi.h | 6 +++---
kernel/watchdog.c | 14 +++++++++++++-
2 files changed, 16 insertions(+), 4 deletions(-)

--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -12,10 +12,10 @@

#ifdef CONFIG_LOCKUP_DETECTOR
void lockup_detector_init(void);
+void lockup_detector_soft_poweroff(void);
#else
-static inline void lockup_detector_init(void)
-{
-}
+static inline void lockup_detector_init(void) { }
+static inline void lockup_detector_soft_poweroff(void) { }
#endif

#ifdef CONFIG_SOFTLOCKUP_DETECTOR
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -333,7 +333,8 @@ static enum hrtimer_restart watchdog_tim
int duration;
int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;

- if (atomic_read(&watchdog_park_in_progress) != 0)
+ if (!watchdog_enabled ||
+ atomic_read(&watchdog_park_in_progress) != 0)
return HRTIMER_NORESTART;

/* kick the hardlockup detector */
@@ -660,6 +661,17 @@ static void set_sample_period(void)
}
#endif /* SOFTLOCKUP */

+/**
+ * lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
+ *
+ * Special interface for parisc. It prevents lockup detector warnings from
+ * the default pm_poweroff() function which busy loops forever.
+ */
+void lockup_detector_soft_poweroff(void)
+{
+ watchdog_enabled = 0;
+}
+
/*
* Suspend the hard and soft lockup detector by parking the watchdog threads.
*/

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