Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c
index 44a2593..246efc7 100644
--- a/kernel/cpu_pm.c
+++ b/kernel/cpu_pm.c
@@ -13,20 +13,46 @@
#include <linux/spinlock.h>
#include <linux/syscore_ops.h>
-static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain);
+/*
+ * atomic_notifiers use a spinlock_t, which can block under PREEMPT_RT.
+ * Notifications for cpu_pm will be issued by the idle task itself, which can
+ * never block, IOW it requires using a raw_spinlock_t.
+ */
+static struct {
+ struct raw_notifier_head chain;
+ raw_spinlock_t lock;
+} cpu_pm_notifier = {
+ .chain = RAW_NOTIFIER_INIT(cpu_pm_notifier.chain),
+ .lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock),
+};
-static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
+static int cpu_pm_notify(enum cpu_pm_event event)
{
int ret;
/*
- * __atomic_notifier_call_chain has a RCU read critical section, which
- * could be disfunctional in cpu idle. Copy RCU_NONIDLE code to let
- * RCU know this.
+ * This introduces a RCU read critical section, which could be
+ * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
+ * this.
*/
rcu_irq_enter_irqson();
- ret = __atomic_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
- nr_to_call, nr_calls);
+ rcu_read_lock();
+ ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
+ rcu_read_unlock();
+ rcu_irq_exit_irqson();
+
+ return notifier_to_errno(ret);
+}
+
+static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
+{
+ unsigned long flags;
+ int ret;
+
+ rcu_irq_enter_irqson();
+ raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
+ ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
+ raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
rcu_irq_exit_irqson();
return notifier_to_errno(ret);
@@ -39,12 +65,17 @@
* Add a driver to a list of drivers that are notified about
* CPU and CPU cluster low power entry and exit.
*
- * This function may sleep, and has the same return conditions as
- * raw_notifier_chain_register.
+ * This function has the same return conditions as raw_notifier_chain_register.
*/
int cpu_pm_register_notifier(struct notifier_block *nb)
{
- return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb);
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
+ ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
+ raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
+ return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
@@ -54,12 +85,17 @@
*
* Remove a driver from the CPU PM notifier list.
*
- * This function may sleep, and has the same return conditions as
- * raw_notifier_chain_unregister.
+ * This function has the same return conditions as raw_notifier_chain_unregister.
*/
int cpu_pm_unregister_notifier(struct notifier_block *nb)
{
- return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
+ ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
+ raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
+ return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
@@ -80,18 +116,7 @@
*/
int cpu_pm_enter(void)
{
- int nr_calls = 0;
- int ret = 0;
-
- ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
- if (ret)
- /*
- * Inform listeners (nr_calls - 1) about failure of CPU PM
- * PM entry who are notified earlier to prepare for it.
- */
- cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
-
- return ret;
+ return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
}
EXPORT_SYMBOL_GPL(cpu_pm_enter);
@@ -109,7 +134,7 @@
*/
int cpu_pm_exit(void)
{
- return cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
+ return cpu_pm_notify(CPU_PM_EXIT);
}
EXPORT_SYMBOL_GPL(cpu_pm_exit);
@@ -131,18 +156,7 @@
*/
int cpu_cluster_pm_enter(void)
{
- int nr_calls = 0;
- int ret = 0;
-
- ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
- if (ret)
- /*
- * Inform listeners (nr_calls - 1) about failure of CPU cluster
- * PM entry who are notified earlier to prepare for it.
- */
- cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
-
- return ret;
+ return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
}
EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
@@ -163,7 +177,7 @@
*/
int cpu_cluster_pm_exit(void)
{
- return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
+ return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
}
EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);