[GIT PULL] s390 regression patch for 3.8-rc8

[GIT PULL] s390 regression patch for 3.8-rc8

[Martin Schwidefsky]

Hi Linus,

please pull from the 'for-linus' branch of

	git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git for-linus

to receive the following updates:
The recent fix for the s390 sched_clock() function uncovered yet
another bug in s390_next_ktime which causes an endless loop in KVM.
This regression should be fixed before v3.8.

I keep the fingers crossed that this is the last one for v3.8.

Heiko Carstens (1):
      s390/timer: avoid overflow when programming clock comparator

 arch/s390/kernel/time.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index a5f4f5a..0aa98db 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -120,6 +120,9 @@ static int s390_next_ktime(ktime_t expires,
 	nsecs = ktime_to_ns(ktime_add(timespec_to_ktime(ts), expires));
 	do_div(nsecs, 125);
 	S390_lowcore.clock_comparator = sched_clock_base_cc + (nsecs << 9);
+	/* Program the maximum value if we have an overflow (== year 2042) */
+	if (unlikely(S390_lowcore.clock_comparator < sched_clock_base_cc))
+		S390_lowcore.clock_comparator = -1ULL;
 	set_clock_comparator(S390_lowcore.clock_comparator);
 	return 0;
 }