On 06/27/2012 03:06 PM, Thomas Renninger wrote:
> Hi,
>
> I agree that such a dependency between 2 modules is not
> nice. But your patch will have bad side-effects (see comments
> embedded below).
>
> On Wednesday, June 27, 2012 11:07:48 AM Daniel Lezcano wrote:
>> When the system is booted with some cpus offline, the idle
>> driver is not initialized. When a cpu is set online, the
>> acpi code call the intel idle init function. Unfortunately
>> this code introduce a dependency between intel_idle and acpi.
>>
>> This patch is intended to remove this dependency by using the
>> notifier of intel_idle. In order to make it work, the notifier
>> must be initialized in the right order, acpi then intel_idle.
>> This is done in the Makefile. This patch has the benefit of
>> encapsulating the intel_idle driver and remove some exported
>> functions.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
>> ---
>> drivers/Makefile | 3 ++-
>> drivers/acpi/processor_driver.c | 7 -------
>> drivers/idle/intel_idle.c | 22 ++++++++++++++--------
>> include/linux/cpuidle.h | 7 -------
>> 4 files changed, 16 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/Makefile b/drivers/Makefile
>> index 2ba29ff..a2454b8 100644
>> --- a/drivers/Makefile
>> +++ b/drivers/Makefile
>> @@ -12,8 +12,9 @@ obj-$(CONFIG_PCI) += pci/
>> obj-$(CONFIG_PARISC) += parisc/
>> obj-$(CONFIG_RAPIDIO) += rapidio/
>> obj-y += video/
>> -obj-y += idle/
>> +# acpi must come before idle for initialization
>> obj-$(CONFIG_ACPI) += acpi/
>> +obj-y += idle/
> This breaks intel_idle.
> Loading order defines which one comes first and is used: intel_idle
> or ACPI processor cpuidle driver.
> With above, one would get acpi_idle cpuidle driver if both are
> compiled in, instead of the intel_idle one.
>
> Why exactly is this necessary, couldn't it just work?
[...]
I just wanted to keep same order. If it is not necessary, I won't invert
the compilation order in the next patch.
>> -static int setup_broadcast_cpuhp_notify(struct notifier_block *n,
>> - unsigned long action, void *hcpu)
>> +static int cpu_hotplug_notify(struct notifier_block *n,
>> + unsigned long action, void *hcpu)
>> {
>> int hotcpu = (unsigned long)hcpu;
>> + struct cpuidle_device *dev;
>>
>> switch (action & 0xf) {
>> case CPU_ONLINE:
>> smp_call_function_single(hotcpu, __setup_broadcast_timer,
>> (void *)true, 1);
>> +
>> + dev = per_cpu_ptr(intel_idle_cpuidle_devices, hotcpu);
>> + if (!dev->registered)
>> + intel_idle_cpu_init(hotcpu);
>> +
> A small comment why this can happen and needs to be done
> (real hotplugged cpu case) might help here later.
Yes, that makes sense.
[...]
>> static void auto_demotion_disable(void *dummy)
>> @@ -407,7 +414,7 @@ static int intel_idle_probe(void)
>> lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
>> else {
>> on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
>> - register_cpu_notifier(&setup_broadcast_notifier);
>> + register_cpu_notifier(&cpu_hotplug_notifier);
>
> The notifier always has to be registered now, not only in:
> if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
> case.
Oops, right.
>> pr_debug(PREFIX "v" INTEL_IDLE_VERSION
>> @@ -494,7 +501,7 @@ static int intel_idle_cpuidle_driver_init(void)
>> * allocate, initialize, register cpuidle_devices
>> * @cpu: cpu/core to initialize
>> */
>> -int intel_idle_cpu_init(int cpu)
>> +static int intel_idle_cpu_init(int cpu)
>> {
>> int cstate;
>> struct cpuidle_device *dev;
>> @@ -539,7 +546,6 @@ int intel_idle_cpu_init(int cpu)
>>
>> return 0;
>> }
>> -EXPORT_SYMBOL_GPL(intel_idle_cpu_init);
>>
>> static int __init intel_idle_init(void)
>> {
>> @@ -583,7 +589,7 @@ static void __exit intel_idle_exit(void)
>>
>> if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) {
>> on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
>> - unregister_cpu_notifier(&setup_broadcast_notifier);
>> + unregister_cpu_notifier(&cpu_hotplug_notifier);
> Same.
Thanks for the review !
-- Daniel
--
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