When selecting PREEMPT_RT, cpufreq_driver->stop_cpu(policy) might got
stuck due to irq_work_sync() pending for work on lazy_list. That’s
because lazy_list may have no chance to be served in softirq context
sometimes. Below is one of scenarios that was captured:
...
ret_from_fork
kthread
smpboot_thread_fn
cpuhp_thread_fun
cpuhp_invoke_callback: state: 193
cpuhp_cpufreq_online
cpufreq_online
cpufreq_driver->stop_cpu(policy);
cpufreq_dbs_governor_stop
sugov_stop // kernel/sched/cpufreq_schedutil.c
irq_work_sync(&sg_policy->irq_work);
This is observed on LX2160ARDB (16 A72 cores) with cpufreq governor of
‘schedutil’ or ‘ondemand’.
Configure related irqwork to run on raw-irq context could fix this.
Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
---
drivers/cpufreq/cpufreq_governor.c | 2 +-
kernel/sched/cpufreq_schedutil.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 63f7c219062b..731a7b1434df 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -360,7 +360,7 @@ static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *poli
policy_dbs->policy = policy;
mutex_init(&policy_dbs->update_mutex);
atomic_set(&policy_dbs->work_count, 0);
- init_irq_work(&policy_dbs->irq_work, dbs_irq_work);
+ policy_dbs->irq_work = IRQ_WORK_INIT_HARD(dbs_irq_work);
INIT_WORK(&policy_dbs->work, dbs_work_handler);
/* Set policy_dbs for all CPUs, online+offline */
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 6931f0cdeb80..054a01ef4f57 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -719,7 +719,7 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
sg_policy->thread = thread;
kthread_bind_mask(thread, policy->related_cpus);
- init_irq_work(&sg_policy->irq_work, sugov_irq_work);
+ sg_policy->irq_work = IRQ_WORK_INIT_HARD(sugov_irq_work);
mutex_init(&sg_policy->work_lock);
wake_up_process(thread);
--
2.25.1
