From: Ben Gras <ben@minix3.org>
Date: Mon, 24 Jun 2013 13:46:20 +0000 (+0200)
Subject: kernel: high-hz workaround for do_settime
X-Git-Tag: v3.3.0~901
X-Git-Url: http://zhaoyanbai.com/repos/?a=commitdiff_plain;h=27f7fd3554a7b7c152029a608aa47d7b34f300d6;p=minix.git

kernel: high-hz workaround for do_settime

	. with hz=1000, clock_t only lasts a few years.
	  whenever we can't express the desired realtime
	  in ticks because the distance with boottime is
	  too high, simply adjust bootime like we do for
	  otherwise negative values.
	. fixes test 2 on ARM
---

diff --git a/kernel/system/do_settime.c b/kernel/system/do_settime.c
index bf408ce69..b9116331a 100644
--- a/kernel/system/do_settime.c
+++ b/kernel/system/do_settime.c
@@ -19,6 +19,7 @@ int do_settime(struct proc * caller, message * m_ptr)
 {
   clock_t newclock, ticks;
   time_t timediff;
+  signed long long timediff_ticks;
 
   if (m_ptr->T_CLOCK_ID != CLOCK_REALTIME) /* only realtime can change */
 	return EINVAL;
@@ -31,8 +32,12 @@ int do_settime(struct proc * caller, message * m_ptr)
 	return(OK);
   } /* else user wants to set the time */
 
+  timediff = m_ptr->T_TIME_SEC - boottime;
+  timediff_ticks = (signed long long) timediff * system_hz;
+
   /* prevent a negative value for realtime */
-  if (m_ptr->T_TIME_SEC <= boottime) {
+  if (m_ptr->T_TIME_SEC <= boottime ||
+      timediff_ticks < LONG_MIN/2 || timediff_ticks > LONG_MAX/2) {
   	/* boottime was likely wrong, try to correct it. */
 	boottime = m_ptr->T_TIME_SEC;
 	set_realtime(1);
@@ -40,8 +45,7 @@ int do_settime(struct proc * caller, message * m_ptr)
   }
 
   /* calculate the new value of realtime in ticks */
-  timediff = m_ptr->T_TIME_SEC - boottime;
-  newclock = (timediff*system_hz) + (m_ptr->T_TIME_NSEC/(1000000000/system_hz));
+  newclock = timediff_ticks + (m_ptr->T_TIME_NSEC/(1000000000/system_hz));
 
   set_realtime(newclock);