do_account_vtime() runs always with interrupts disabled, therefore use
__this_cpu_read() instead of this_cpu_read() to get rid of a pointless
preempt_disable() / preempt_enable() pair.
Also there are no concurrent writers to the cpu time accounting fields
in lowcore. Therefore get rid of READ_ONCE() usages.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
arch/s390/kernel/vtime.c | 21 +++++++--------------
1 file changed, 7 insertions(+), 14 deletions(-)
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 122d30b10440..4111ff4d727c 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -137,23 +137,16 @@ static int do_account_vtime(struct task_struct *tsk)
lc->system_timer += timer;
/* Update MT utilization calculation */
- if (smp_cpu_mtid &&
- time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
+ if (smp_cpu_mtid && time_after64(jiffies_64, __this_cpu_read(mt_scaling_jiffies)))
update_mt_scaling();
/* Calculate cputime delta */
- user = update_tsk_timer(&tsk->thread.user_timer,
- READ_ONCE(lc->user_timer));
- guest = update_tsk_timer(&tsk->thread.guest_timer,
- READ_ONCE(lc->guest_timer));
- system = update_tsk_timer(&tsk->thread.system_timer,
- READ_ONCE(lc->system_timer));
- hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
- READ_ONCE(lc->hardirq_timer));
- softirq = update_tsk_timer(&tsk->thread.softirq_timer,
- READ_ONCE(lc->softirq_timer));
- lc->steal_timer +=
- clock - user - guest - system - hardirq - softirq;
+ user = update_tsk_timer(&tsk->thread.user_timer, lc->user_timer);
+ guest = update_tsk_timer(&tsk->thread.guest_timer, lc->guest_timer);
+ system = update_tsk_timer(&tsk->thread.system_timer, lc->system_timer);
+ hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, lc->hardirq_timer);
+ softirq = update_tsk_timer(&tsk->thread.softirq_timer, lc->softirq_timer);
+ lc->steal_timer += clock - user - guest - system - hardirq - softirq;
/* Push account value */
if (user) {
--
2.51.0