From: Laurent Dufour ldufour@linux.ibm.com
[ Upstream commit 7c56a8733d0a2a4be2438a7512566e5ce552fccf ]
In some circumstances it may be interesting to reconfigure the watchdog from inside the kernel.
On PowerPC, this may helpful before and after a LPAR migration (LPM) is initiated, because it implies some latencies, watchdog, and especially NMI watchdog is expected to be triggered during this operation. Reconfiguring the watchdog with a factor, would prevent it to happen too frequently during LPM.
Rename lockup_detector_reconfigure() as __lockup_detector_reconfigure() and create a new function lockup_detector_reconfigure() calling __lockup_detector_reconfigure() under the protection of watchdog_mutex.
Signed-off-by: Laurent Dufour ldufour@linux.ibm.com [mpe: Squash in build fix from Laurent, reported by Sachin] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220713154729.80789-3-ldufour@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/nmi.h | 2 ++ kernel/watchdog.c | 21 ++++++++++++++++----- 2 files changed, 18 insertions(+), 5 deletions(-)
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 750c7f395ca9..f700ff2df074 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -122,6 +122,8 @@ int watchdog_nmi_probe(void); int watchdog_nmi_enable(unsigned int cpu); void watchdog_nmi_disable(unsigned int cpu);
+void lockup_detector_reconfigure(void); + /** * touch_nmi_watchdog - restart NMI watchdog timeout. * diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 01bf977090dc..ec34d9f2eab2 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -518,7 +518,7 @@ int lockup_detector_offline_cpu(unsigned int cpu) return 0; }
-static void lockup_detector_reconfigure(void) +static void __lockup_detector_reconfigure(void) { cpus_read_lock(); watchdog_nmi_stop(); @@ -538,6 +538,13 @@ static void lockup_detector_reconfigure(void) __lockup_detector_cleanup(); }
+void lockup_detector_reconfigure(void) +{ + mutex_lock(&watchdog_mutex); + __lockup_detector_reconfigure(); + mutex_unlock(&watchdog_mutex); +} + /* * Create the watchdog thread infrastructure and configure the detector(s). * @@ -558,13 +565,13 @@ static __init void lockup_detector_setup(void) return;
mutex_lock(&watchdog_mutex); - lockup_detector_reconfigure(); + __lockup_detector_reconfigure(); softlockup_initialized = true; mutex_unlock(&watchdog_mutex); }
#else /* CONFIG_SOFTLOCKUP_DETECTOR */ -static void lockup_detector_reconfigure(void) +static void __lockup_detector_reconfigure(void) { cpus_read_lock(); watchdog_nmi_stop(); @@ -572,9 +579,13 @@ static void lockup_detector_reconfigure(void) watchdog_nmi_start(); cpus_read_unlock(); } +void lockup_detector_reconfigure(void) +{ + __lockup_detector_reconfigure(); +} static inline void lockup_detector_setup(void) { - lockup_detector_reconfigure(); + __lockup_detector_reconfigure(); } #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
@@ -614,7 +625,7 @@ static void proc_watchdog_update(void) { /* Remove impossible cpus to keep sysctl output clean. */ cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask); - lockup_detector_reconfigure(); + __lockup_detector_reconfigure(); }
/*