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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux into akpm

Pull s390 regression fix from Martin Schwidefsky:
 "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."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/timer: avoid overflow when programming clock comparator
Linus Torvalds 12 years ago
parent
commit
a0e5056e3b
1 changed files with 3 additions and 0 deletions
  1. 3 0
      arch/s390/kernel/time.c

+ 3 - 0
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;
 }