When there are multiple implementations of the NMI watchdog, there may be
situations in which switching from one to another is needed. If the time-
stamp counter becomes unstable, the HPET-based NMI watchdog can no longer
be used. Similarly, the HPET-based NMI watchdog relies on tsc_khz and
needs to be informed when it is refined.
Reloading the NMI watchdog or 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: Andi Kleen <a...@linux.intel.com>
Cc: Nicholas Piggin <npig...@gmail.com>
Cc: Stephane Eranian <eran...@google.com>
Cc: "Ravi V. Shankar" <ravi.v.shan...@intel.com>
Cc: io...@lists.linux-foundation.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: x...@kernel.org
Reviewed-by: Tony Luck <tony.l...@intel.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>
---
Changes since v5:
* None
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 6443841a755f..e5b67544f8c8 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -537,7 +537,7 @@ 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();
@@ -579,7 +579,7 @@ 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
