Write the system time back to the RTC every 30 minutes.

This fixes the problem that long-running machines which were not
shut down properly would reboot with a badly offset system time.

hints and ok kettenis@

1 files changed, 37 insertions, 1 deletions

diff --git a/sys/kern/kern_time.c b/sys/kern/kern_time.c
index 1477ad53d78..64083f9ccde 100644
--- a/sys/kern/kern_time.c
+++ b/sys/kern/kern_time.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_time.c,v 1.97 2016/04/28 20:11:20 tedu Exp $	*/
+/*	$OpenBSD: kern_time.c,v 1.98 2016/09/03 14:46:56 naddy Exp $	*/
 /*	$NetBSD: kern_time.c,v 1.20 1996/02/18 11:57:06 fvdl Exp $	*/
 
 /*
@@ -41,6 +41,8 @@
 #include <sys/vnode.h>
 #include <sys/signalvar.h>
 #include <sys/pledge.h>
+#include <sys/task.h>
+#include <sys/timeout.h>
 #include <sys/timetc.h>
 
 #include <sys/mount.h>
@@ -785,3 +787,37 @@ ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
 	return (rv);
 }
 
+
+#define RESETTODR_PERIOD	1800
+
+void periodic_resettodr(void *);
+void perform_resettodr(void *);
+
+struct timeout resettodr_to = TIMEOUT_INITIALIZER(periodic_resettodr, NULL);
+struct task resettodr_task = TASK_INITIALIZER(perform_resettodr, NULL);
+
+void
+periodic_resettodr(void *arg __unused)
+{
+	task_add(systq, &resettodr_task);
+}
+
+void
+perform_resettodr(void *arg __unused)
+{
+	resettodr();
+	timeout_add_sec(&resettodr_to, RESETTODR_PERIOD);
+}
+
+void
+start_periodic_resettodr(void)
+{
+	timeout_add_sec(&resettodr_to, RESETTODR_PERIOD);
+}
+
+void
+stop_periodic_resettodr(void)
+{
+	timeout_del(&resettodr_to);
+	task_del(systq, &resettodr_task);
+}