[PATCH] 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 x86_64.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 97115e6..9dd15d1 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -1039,8 +1039,16 @@
unsigned long flags;
unsigned long sec;
unsigned long ctime = get_cmos_time();
- unsigned long sleep_length = (ctime - sleep_start) * HZ;
+ long sleep_length = (ctime - sleep_start) * HZ;
+ if (sleep_length < 0) {
+ printk(KERN_WARNING "Time 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;
+ }
if (vxtime.hpet_address)
hpet_reenable();
else