[PATCH 5.15 219/244] watchdog: export lockup_detector_reconfigure

Greg Kroah-Hartman
2022-08-23T10:32:48Z

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 ad912511a0c0..1cfa269bd448 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)
+static void __lockup_detector_reconfigure(void)
{
cpus_read_lock();
watchdog_nmi_stop();
@@ -557,6 +557,13 @@ 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).
*/
@@ -573,13 +580,13 @@ 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();
@@ -587,9 +594,13 @@ 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 */

@@ -629,7 +640,7 @@ 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();
}

/*
--
2.35.1