[PATCH] i386: Detect clock skew during suspend
Detect the situations in which the time after a resume from disk would be
earlier than the time before the suspend and prevent them from happening on
i386.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: John Stultz <johnstul@us.ibm.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index 6f333e7..1302e4a 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -270,16 +270,19 @@
mod_timer(&sync_cmos_timer, jiffies + 1);
}
-static long clock_cmos_diff, sleep_start;
+static long clock_cmos_diff;
+static unsigned long sleep_start;
static int timer_suspend(struct sys_device *dev, pm_message_t state)
{
/*
* Estimate time zone so that set_time can update the clock
*/
- clock_cmos_diff = -get_cmos_time();
+ unsigned long ctime = get_cmos_time();
+
+ clock_cmos_diff = -ctime;
clock_cmos_diff += get_seconds();
- sleep_start = get_cmos_time();
+ sleep_start = ctime;
return 0;
}
@@ -287,16 +290,25 @@
{
unsigned long flags;
unsigned long sec;
- unsigned long sleep_length;
+ unsigned long ctime = get_cmos_time();
+ long sleep_length = (ctime - sleep_start) * HZ;
struct timespec ts;
+
+ if (sleep_length < 0) {
+ printk(KERN_WARNING "CMOS clock skew detected in timer resume!\n");
+ /* The time after the resume must not be earlier than the time
+ * before the suspend or some nasty things will happen
+ */
+ sleep_length = 0;
+ ctime = sleep_start;
+ }
#ifdef CONFIG_HPET_TIMER
if (is_hpet_enabled())
hpet_reenable();
#endif
setup_pit_timer();
- sec = get_cmos_time() + clock_cmos_diff;
- sleep_length = (get_cmos_time() - sleep_start) * HZ;
+ sec = ctime + clock_cmos_diff;
ts.tv_sec = sec;
ts.tv_nsec = 0;
do_settimeofday(&ts);