[S390] correct ktime to tod clock comparator conversion

The conversion of the ktime to a value suitable for the clock comparator
does not take changes to wall_to_monotonic into account. In fact the
conversion just needs the boot clock (sched_clock_base_cc) and the
total_sleep_time.

This is applicable to 3.2+ kernels.

CC: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index fa02f443f5f6..14da278febbf 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -113,11 +113,14 @@ static void fixup_clock_comparator(unsigned long long delta)
 static int s390_next_ktime(ktime_t expires,
                            struct clock_event_device *evt)
 {
+        struct timespec ts;
         u64 nsecs;
 
-        nsecs = ktime_to_ns(ktime_sub(expires, ktime_get_monotonic_offset()));
+        ts.tv_sec = ts.tv_nsec = 0;
+        monotonic_to_bootbased(&ts);
+        nsecs = ktime_to_ns(ktime_add(timespec_to_ktime(ts), expires));
         do_div(nsecs, 125);
-        S390_lowcore.clock_comparator = TOD_UNIX_EPOCH + (nsecs << 9);
+        S390_lowcore.clock_comparator = sched_clock_base_cc + (nsecs << 9);
         set_clock_comparator(S390_lowcore.clock_comparator);
         return 0;
 }