linux-kernel - [PATCH 1/4] watchdog: introduce watchdog_park_threads() and watchdog_unpark

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Date:	Sat,  1 Aug 2015 14:49:22 +0200
From:	Ulrich Obergfell <uobergfe@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, dzickus@...hat.com, atomlin@...hat.com,
	uobergfe@...hat.com, jolsa@...nel.org, mhocko@...e.cz,
	eranian@...gle.com, cmetcalf@...hip.com, fweisbec@...il.com
Subject: [PATCH 1/4] watchdog: introduce watchdog_park_threads() and watchdog_unpark_threads()

These functions are intended to be used only from inside kernel/watchdog.c
to park/unpark all watchdog threads that are specified in watchdog_cpumask.

Signed-off-by: Ulrich Obergfell <uobergfe@...hat.com>
---
 kernel/watchdog.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index a6ffa43..5571f20 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -24,6 +24,7 @@
 #include <asm/irq_regs.h>
 #include <linux/kvm_para.h>
 #include <linux/perf_event.h>
+#include <linux/kthread.h>
 
 /*
  * The run state of the lockup detectors is controlled by the content of the
@@ -666,6 +667,41 @@ static struct smp_hotplug_thread watchdog_threads = {
 	.unpark			= watchdog_enable,
 };
 
+/*
+ * park all watchdog threads that are specified in 'watchdog_cpumask'
+ */
+static int watchdog_park_threads(void)
+{
+	int cpu, ret = 0;
+
+	get_online_cpus();
+	for_each_watchdog_cpu(cpu) {
+		ret = kthread_park(per_cpu(softlockup_watchdog, cpu));
+		if (ret)
+			break;
+	}
+	if (ret) {
+		for_each_watchdog_cpu(cpu)
+			kthread_unpark(per_cpu(softlockup_watchdog, cpu));
+	}
+	put_online_cpus();
+
+	return ret;
+}
+
+/*
+ * unpark all watchdog threads that are specified in 'watchdog_cpumask'
+ */
+static void watchdog_unpark_threads(void)
+{
+	int cpu;
+
+	get_online_cpus();
+	for_each_watchdog_cpu(cpu)
+		kthread_unpark(per_cpu(softlockup_watchdog, cpu));
+	put_online_cpus();
+}
+
 static void restart_watchdog_hrtimer(void *info)
 {
 	struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);
-- 
1.7.11.7

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