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watchdog: export lockup_detector_reconfigure 

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
This commit is contained in:
Laurent Dufour 2022-07-13 17:47:27 +02:00 committed by Michael Ellerman
parent 882c0d1704
commit 7c56a8733d
2 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/nmi.h
View File

@ -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.
*

21
kernel/watchdog.c
View File

@ -541,7 +541,7 @@ 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();
@ -561,6 +561,13 @@ 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 infrastructure and configure the detector(s).
*/
@ -577,13 +584,13 @@ 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();
@ -591,9 +598,13 @@ 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 */
@ -633,7 +644,7 @@ 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();
}
/*