powerpc/cpuidle: Fixes for pseries_idle hotplug notifier
Currently the call to pseries_notify_cpuidle_add_cpu(), that takes
action on the cpuidle front when a cpu is added/removed
is being made from smp_xics_setup_cpu().
This caused lockdep issues as
reported https://lkml.org/lkml/2012/5/17/2
On addition of each cpu,
resources were cleared and re-allocated each time, all in critical
section as part of start_secondary() call were interrupts are disabled.
To resolve this issue, the pseries_notify_cpuidle_add_cpu() call is
is being replaced by a hotplug notifier which
would prevent cpuidle resources from being
released and allocated each time cpu is onlined in the critical code path.
It was fixed in https://lkml.org/lkml/2012/5/18/174.
Also it is essential to call cpuidle_enable/disable_device
between cpuidle_pause_and_lock() and
cpuidle_resume_and_unlock() when used externally
to avoid race conditions. Add support for CPU_ONLINE_FROZEN
and CPU_DEAD_FROZEN as part of hotplug notify event for
pseries_idle and unregister hotplug notifier
while exiting out. The above mentioned issues
are fixed as part of this patch.
Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c
index 7f5668b..455760b 100644
--- a/arch/powerpc/platforms/pseries/processor_idle.c
+++ b/arch/powerpc/platforms/pseries/processor_idle.c
@@ -197,13 +197,25 @@
struct cpuidle_device *dev =
per_cpu_ptr(pseries_cpuidle_devices, hotcpu);
- switch (action & 0xf) {
- case CPU_ONLINE:
- if (dev && cpuidle_get_driver()) {
- cpuidle_disable_device(dev);
+ if (dev && cpuidle_get_driver()) {
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ cpuidle_pause_and_lock();
cpuidle_enable_device(dev);
+ cpuidle_resume_and_unlock();
+ break;
+
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ cpuidle_pause_and_lock();
+ cpuidle_disable_device(dev);
+ cpuidle_resume_and_unlock();
+ break;
+
+ default:
+ return NOTIFY_DONE;
}
- break;
}
return NOTIFY_OK;
}
@@ -345,6 +357,7 @@
static void __exit pseries_processor_idle_exit(void)
{
+ unregister_cpu_notifier(&setup_hotplug_notifier);
pseries_idle_devices_uninit();
cpuidle_unregister_driver(&pseries_idle_driver);