diff options
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/cputime.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 49b7cfe98f7a..2b57031afc19 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -602,9 +602,12 @@ static void cputime_adjust(struct task_cputime *curr, * If the tick based count grows faster than the scheduler one, * the result of the scaling may go backward. * Let's enforce monotonicity. + * Atomic exchange protects against concurrent cputime_adjust(). */ - prev->stime = max(prev->stime, stime); - prev->utime = max(prev->utime, utime); + while (stime > (rtime = ACCESS_ONCE(prev->stime))) + cmpxchg(&prev->stime, rtime, stime); + while (utime > (rtime = ACCESS_ONCE(prev->utime))) + cmpxchg(&prev->utime, rtime, utime); out: *ut = prev->utime; |