When there are more than one implementation of the NMI watchdog, there may
be situations in which switching from one to another is needed. For
if the time-stamp counter becomes unstable, the HPET-based NMI watchdog
an no longer be used.
Switching to another hardlockup detector can be done cleanly by updating
the arch-specific stub and then reconfiguring the whole lockup detector.
Expose lockup_detector_reconfigure() to achieve this goal.
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Ashok Raj <ashok....@intel.com>
Cc: Andi Kleen <andi.kl...@intel.com>
Cc: Tony Luck <tony.l...@intel.com>
Cc: Nicholas Piggin <npig...@gmail.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
Cc: "Ravi V. Shankar" <ravi.v.shan...@intel.com>
Cc: x...@kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>
---
Changes since v4:
* Switching to the perf-based lockup detector under the hood is hacky.
Instead, reconfigure the whole lockup detector.
Changes since v3:
* None
Changes since v2:
* Introduced this patch.
Changes since v1:
* N/A
---
include/linux/nmi.h | 2 ++
kernel/watchdog.c | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index cf12380e51b3..73827a477288 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -16,6 +16,7 @@ void lockup_detector_init(void);
void lockup_detector_soft_poweroff(void);
void lockup_detector_cleanup(void);
bool is_hardlockup(void);
+void lockup_detector_reconfigure(void);
extern int watchdog_user_enabled;
extern int nmi_watchdog_user_enabled;
@@ -37,6 +38,7 @@ extern int sysctl_hardlockup_all_cpu_backtrace;
static inline void lockup_detector_init(void) { }
static inline void lockup_detector_soft_poweroff(void) { }
static inline void lockup_detector_cleanup(void) { }
+static inline void lockup_detector_reconfigure(void) { }
#endif /* !CONFIG_LOCKUP_DETECTOR */
#ifdef CONFIG_SOFTLOCKUP_DETECTOR
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 4615064ee282..96f06938dc83 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -531,7 +531,7 @@ int lockup_detector_offline_cpu(unsigned int cpu)
return 0;
}
-static void lockup_detector_reconfigure(void)
+void lockup_detector_reconfigure(void)
{
cpus_read_lock();
watchdog_nmi_stop();
@@ -577,7 +577,7 @@ static __init void lockup_detector_setup(void)
}
#else /* CONFIG_SOFTLOCKUP_DETECTOR */
-static void lockup_detector_reconfigure(void)
+void lockup_detector_reconfigure(void)
{
cpus_read_lock();
watchdog_nmi_stop();
--
2.17.1
