[PATCH 2/6] watchdog: boottime protection feature (requires 'keep on')

[Janusz Uzycki]

After the boot time active watchdog(s) have to be maintained
by userland.
The protection works only if boot time is non-zero
and keep on feature is enabled.

Signed-off-by: Janusz Uzycki <j.uzycki at elproma.com.pl>
---
 drivers/watchdog/watchdog_core.c |  4 ++++
 drivers/watchdog/watchdog_dev.c  | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index cec9b55..13f3d3a 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -43,6 +43,10 @@
 static DEFINE_IDA(watchdog_ida);
 static struct class *watchdog_class;
 
+unsigned int boottime = 0;
+module_param(boottime, uint, 0);
+MODULE_PARM_DESC(boottime, "After the boot time active watchdog(s) have to be maintained by userland. 0 disables the protection.");
+
 static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
 {
 	/*
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 51a65f6..d289eab 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -42,6 +42,7 @@
 #include <linux/init.h>		/* For __init/__exit/... */
 #include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
 #include <linux/jiffies.h>	/* for ping timer */
+#include <linux/time.h>		/* for uptime */
 
 #include "watchdog_core.h"
 
@@ -282,6 +283,16 @@ out_ioctl:
 static void watchdog_ping_timer_cb(unsigned long data)
 {
 	struct watchdog_device *wdd = (struct watchdog_device *)data;
+	extern unsigned int boottime;
+	if (boottime) {
+		struct timespec uptime;
+		get_monotonic_boottime(&uptime);
+		if (uptime.tv_sec > boottime) {
+			dev_info(wdd->dev,
+				 "Boottime for userland exceeded. Reboot expected!\n");
+			return;
+		}
+	}
 	watchdog_ping(wdd);
 	/* call next ping half the timeout value */
 	mod_timer(&wdd->ping_timer,
-- 
1.7.11.3