On Tuesday, July 30, 2013 01:19:46 PM Daniel Lezcano wrote:

On 07/30/2013 12:48 PM, Wang Dongsheng-B40534 wrote:

quoted

quoted

-----Original Message-----
From: Daniel Lezcano [mailto:daniel.lezcano@linaro.org]
Sent: Tuesday, July 30, 2013 5:28 PM
To: Wang Dongsheng-B40534
Cc: rjw@sisk.pl; linux-pm@vger.kernel.org; linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] cpuidle: fix unremovable issue for module driver

On 07/30/2013 08:55 AM, Dongsheng Wang wrote:

quoted

From: Wang Dongsheng <redacted>

After __cpuidle_register_device, the cpu incs are added up, but decs
are not, thus the module refcount is not match. So the module "exit"
function can not be executed when we do remove operation. Move
module_put into __cpuidle_register_device to fix it.

Sorry, I still don't get it :/

register->module_get
unregister->module_put

you change it by:

register->module_get
register->module_put
unregister->none

which is wrong.

module_get->set per cpu incs=1
module_put->set per cpu decs=1

module_refcount-> incs - decs;

"unregister" usually call in module->exit function. 
But if module_refcount is not zero, the module->exit() cannot be executed.

Ok, IIUC, the refcount is decremented in the unregister function but
this one is never called because the refcount is not zero.

Funny, that means the module format was *never* used at all as it does
not work.

I am wondering if we shouldn't just remove the module support for
cpuidle. Rafael ?

That would be the simplest thing to do and possibly the most correct one too,
but I need to double check how inte_idle/ACPI idle interactions depend on that.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.