[PATCH] softdog: Add options 'soft_reboot_target' and 'soft_active_on_boot'

[Woody Lin <woodylin@google.com>]

Add module parameters 'soft_reboot_target' and 'soft_active_on_boot' for
customizing softdog configuration; config reboot target by assigning
soft_reboot_target, and set soft_active_on_boot to start up softdog
timer at module initialization stage.

Signed-off-by: Woody Lin <woodylin@google.com>
---
 drivers/watchdog/softdog.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/watchdog/softdog.c b/drivers/watchdog/softdog.c
index 3e4885c1545e..f5027acddbbb 100644
--- a/drivers/watchdog/softdog.c
+++ b/drivers/watchdog/softdog.c
@@ -20,11 +20,13 @@
 #include <linux/hrtimer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/reboot.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
+#include <linux/workqueue.h>
 
 #define TIMER_MARGIN	60		/* Default is 60 seconds */
 static unsigned int soft_margin = TIMER_MARGIN;	/* in seconds */
@@ -49,9 +51,32 @@ module_param(soft_panic, int, 0);
 MODULE_PARM_DESC(soft_panic,
 	"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
 
+static char *soft_reboot_target;
+module_param(soft_reboot_target, charp, 0000);
+MODULE_PARM_DESC(soft_reboot_target,
+	"Softdog action, set reboot target (default=emergency)");
+
+static bool soft_active_on_boot;
+module_param(soft_active_on_boot, bool, 0000);
+MODULE_PARM_DESC(soft_active_on_boot,
+	"Set to true to active Softdog on boot (default=false)");
+
 static struct hrtimer softdog_ticktock;
 static struct hrtimer softdog_preticktock;
 
+static int reboot_kthread_fn(void *data)
+{
+	kernel_restart(soft_reboot_target);
+	emergency_restart(); /* Should not reach here */
+	return -EPERM;       /* Should not reach here */
+}
+
+static void reboot_work_fn(struct work_struct *unused)
+{
+	if (IS_ERR(kthread_run(reboot_kthread_fn, NULL, "softdog_reboot")))
+		emergency_restart();
+}
+
 static enum hrtimer_restart softdog_fire(struct hrtimer *timer)
 {
 	module_put(THIS_MODULE);
@@ -62,6 +87,12 @@ static enum hrtimer_restart softdog_fire(struct hrtimer *timer)
 		panic("Software Watchdog Timer expired");
 	} else {
 		pr_crit("Initiating system reboot\n");
+		if (soft_reboot_target != NULL) {
+			static DECLARE_WORK(reboot_work, reboot_work_fn);
+
+			schedule_work(&reboot_work);
+			return HRTIMER_NORESTART;
+		}
 		emergency_restart();
 		pr_crit("Reboot didn't ?????\n");
 	}
@@ -145,12 +176,19 @@ static int __init softdog_init(void)
 		softdog_preticktock.function = softdog_pretimeout;
 	}
 
+	if (soft_active_on_boot) {
+		set_bit(WDOG_HW_RUNNING, &softdog_dev.status);
+		set_bit(WDOG_ACTIVE, &softdog_dev.status);
+	}
+
 	ret = watchdog_register_device(&softdog_dev);
 	if (ret)
 		return ret;
 
 	pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
 		soft_noboot, softdog_dev.timeout, soft_panic, nowayout);
+	pr_info("             soft_reboot_target=%s soft_active_on_boot=%d\n",
+		soft_reboot_target, soft_active_on_boot);
 
 	return 0;
 }
-- 
2.27.0.rc2.251.g90737beb825-goog