4.9.65-rt57-rc2 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
We must not wake any process (and thus acquire the pi->lock) while
holding the hrtimer's base lock. This does not happen usually because
the hrtimer-callback is invoked in IRQ-context and so
raise_softirq_irqoff() does not wakeup a process.
However during CPU-hotplug it might get called from hrtimers_dead_cpu()
which would wakeup the thread immediately.
Reported-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
kernel/time/hrtimer.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 39e4435b8451..8a20ef6919d9 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1440,7 +1440,7 @@ static inline int hrtimer_rt_defer(struct hrtimer *timer) { return 0; }
static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer);
-static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
+static int __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
{
struct hrtimer_clock_base *base = cpu_base->clock_base;
unsigned int active = cpu_base->active_bases;
@@ -1490,8 +1490,7 @@ static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
raise = 1;
}
}
- if (raise)
- raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+ return raise;
}
#ifdef CONFIG_HIGH_RES_TIMERS
@@ -1505,6 +1504,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
ktime_t expires_next, now, entry_time, delta;
int retries = 0;
+ int raise;
BUG_ON(!cpu_base->hres_active);
cpu_base->nr_events++;
@@ -1523,7 +1523,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
*/
cpu_base->expires_next.tv64 = KTIME_MAX;
- __hrtimer_run_queues(cpu_base, now);
+ raise = __hrtimer_run_queues(cpu_base, now);
/* Reevaluate the clock bases for the next expiry */
expires_next = __hrtimer_get_next_event(cpu_base);
@@ -1534,6 +1534,8 @@ void hrtimer_interrupt(struct clock_event_device *dev)
cpu_base->expires_next = expires_next;
cpu_base->in_hrtirq = 0;
raw_spin_unlock(&cpu_base->lock);
+ if (raise)
+ raise_softirq_irqoff(HRTIMER_SOFTIRQ);
/* Reprogramming necessary ? */
if (!tick_program_event(expires_next, 0)) {
@@ -1613,6 +1615,7 @@ void hrtimer_run_queues(void)
{
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
ktime_t now;
+ int raise;
if (__hrtimer_hres_active(cpu_base))
return;
@@ -1631,8 +1634,10 @@ void hrtimer_run_queues(void)
raw_spin_lock(&cpu_base->lock);
now = hrtimer_update_base(cpu_base);
- __hrtimer_run_queues(cpu_base, now);
+ raise = __hrtimer_run_queues(cpu_base, now);
raw_spin_unlock(&cpu_base->lock);
+ if (raise)
+ raise_softirq_irqoff(HRTIMER_SOFTIRQ);
}
/*
--
2.13.2
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