In full dynticks idle mode, the timekeeper should never be set to another
CPU than 0.
Lets enforce that through a dedicated mutator.
Acked-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Nicolas Pitre <nicolas.pi...@linaro.org>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Viresh Kumar <viresh.ku...@linaro.org>
Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
---
kernel/time/tick-common.c | 9 ++++-----
kernel/time/tick-internal.h | 7 +++++++
kernel/time/tick-sched.c | 7 +++----
3 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index cb57bce..72ccaf2 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -180,9 +180,9 @@ static void tick_setup_device(struct tick_device *td,
*/
if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
if (tick_nohz_full_enabled())
- tick_do_timer_cpu = TICK_DO_TIMER_DEFAULT;
+ tick_do_timer_cpu_set(TICK_DO_TIMER_DEFAULT);
else
- tick_do_timer_cpu = cpu;
+ tick_do_timer_cpu_set(cpu);
tick_next_period = ktime_get();
tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
}
@@ -341,9 +341,8 @@ void tick_handover_do_timer(int *cpup)
{
if (*cpup == tick_do_timer_cpu) {
int cpu = cpumask_first(cpu_online_mask);
-
- tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
- TICK_DO_TIMER_NONE;
+ tick_do_timer_cpu_set((cpu < nr_cpu_ids) ? cpu :
+ TICK_DO_TIMER_NONE);
}
}
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 6b592a8..eadfd89 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -23,6 +23,13 @@ extern void tick_setup_periodic(struct clock_event_device
*dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);
extern void tick_check_new_device(struct clock_event_device *dev);
extern void tick_handover_do_timer(int *cpup);
+
+static inline void tick_do_timer_cpu_set(int cpu)
+{
+ WARN_ON_ONCE(tick_nohz_full_enabled() && cpu != TICK_DO_TIMER_DEFAULT);
+ tick_do_timer_cpu = cpu;
+}
+
extern void tick_shutdown(unsigned int *cpup);
extern void tick_suspend(void);
extern void tick_resume(void);
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 845aaff..3b5102a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -123,7 +123,7 @@ static void tick_sched_do_timer(ktime_t now)
*/
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)
&& !tick_nohz_full_cpu(cpu))
- tick_do_timer_cpu = cpu;
+ tick_do_timer_cpu_set(cpu);
#endif
/* Check, if the jiffies need an update */
@@ -550,7 +550,7 @@ static u64 timekeeping_deferment(struct tick_sched *ts, int
cpu)
ts->do_timer_last = 1;
/* In full dynticks mode, CPU 0 always keeps the duty */
if (!tick_nohz_full_enabled())
- tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+ tick_do_timer_cpu_set(TICK_DO_TIMER_NONE);
} else if (ts->do_timer_last) {
if (tick_do_timer_cpu == TICK_DO_TIMER_NONE)
time_delta = timekeeping_max_deferment();
@@ -600,7 +600,6 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched
*ts,
/* Schedule the tick, if we are at least one jiffie off */
if ((long)delta_jiffies >= 1) {
u64 time_delta = timekeeping_deferment(ts, cpu);
-
#ifdef CONFIG_NO_HZ_FULL
if (!ts->inidle) {
time_delta = min(time_delta,
@@ -717,7 +716,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched
*ts)
*/
if (unlikely(!cpu_online(cpu))) {
if (cpu == tick_do_timer_cpu)
- tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+ tick_do_timer_cpu_set(TICK_DO_TIMER_NONE);
return false;
}
--
1.8.3.1
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