commit d8354e621df66fa68d42b36acc6e30ed36d7d26f
author Olav Haugan <ohaugan@codeaurora.org> Thu Aug 18 16:49:44 2016 -0700
committer Syed Rameez Mustafa <rameezmustafa@codeaurora.org> Tue Feb 07 14:50:23 2017 -0800
tree 4e03de547c149b56ee4de544ba4841080f99a680
parent d584e82ab1d6ddc5c8ef8b6649f0ea4039d6632b

watchdog: Add support for cpu isolation

Open up interface to allow external subsystem to enable and disable hard
lockup detector.

Change-Id: I88a728ee1d54aaa887fab52e5e40d1d4e4fc69ca
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>

kernel/watchdog.c

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index a1f78d4..3c3898d 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -13,6 +13,7 @@
 
 #include <linux/mm.h>
 #include <linux/cpu.h>
+#include <linux/device.h>
 #include <linux/nmi.h>
 #include <linux/init.h>
 #include <linux/module.h>
@@ -95,6 +96,7 @@
 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
 static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
 static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
+static DEFINE_PER_CPU(unsigned int, watchdog_en);
 static DEFINE_PER_CPU(bool, softlockup_touch_sync);
 static DEFINE_PER_CPU(bool, soft_watchdog_warn);
 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
@@ -584,9 +586,17 @@
 	sched_setscheduler(current, policy, &param);
 }
 
-static void watchdog_enable(unsigned int cpu)
+/* Must be called with hotplug lock (lock_device_hotplug()) held. */
+void watchdog_enable(unsigned int cpu)
 {
 	struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);
+	unsigned int *enabled = raw_cpu_ptr(&watchdog_en);
+
+	lock_device_hotplug_assert();
+
+	if (*enabled)
+		return;
+	*enabled = 1;
 
 	/* kick off the timer for the hardlockup detector */
 	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
@@ -604,9 +614,17 @@
 	__touch_watchdog();
 }
 
-static void watchdog_disable(unsigned int cpu)
+/* Must be called with hotplug lock (lock_device_hotplug()) held. */
+void watchdog_disable(unsigned int cpu)
 {
 	struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);
+	unsigned int *enabled = raw_cpu_ptr(&watchdog_en);
+
+	lock_device_hotplug_assert();
+
+	if (!*enabled)
+		return;
+	*enabled = 0;
 
 	watchdog_set_prio(SCHED_NORMAL, 0);
 	hrtimer_cancel(hrtimer);