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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>
This commit is contained in:
Deepthi Dharwar 2012-07-03 20:07:22 +00:00 committed by Benjamin Herrenschmidt
parent 8bf8385b9c
commit 852d8cb1ff
1 changed files with 18 additions and 5 deletions
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23
arch/powerpc/platforms/pseries/processor_idle.c
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@ -197,13 +197,25 @@ static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
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 int __init pseries_processor_idle_init(void)
static void __exit pseries_processor_idle_exit(void)
{
unregister_cpu_notifier(&setup_hotplug_notifier);
pseries_idle_devices_uninit();
cpuidle_unregister_driver(&pseries_idle_driver);