> -----Original Message-----
> From: Daniel Lezcano [mailto:daniel.lezc...@linaro.org]
> Sent: Tuesday, July 30, 2013 5:28 PM
> To: Wang Dongsheng-B40534
> Cc: r...@sisk.pl; linux...@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:
> > From: Wang Dongsheng <dongsheng.w...@freescale.com>
> >
> > 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.
See, kernel/module.c +874
delete_module()-->try_stop_module();
Test Log:
root:~# rmmod cpuidle-e500
module_refcount: incs[9], decs[1]
rmmod: can't unload 'cpuidle_e500': Resource temporarily unavailable
> Can you describe the problem you are facing ? (a bit more than "I can't
> unload the module").
>
> > Signed-off-by: Wang Dongsheng <dongsheng.w...@freescale.com>
> >
> > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> > index d75040d..e964ada 100644
> > --- a/drivers/cpuidle/cpuidle.c
> > +++ b/drivers/cpuidle/cpuidle.c
> > @@ -351,11 +351,8 @@ EXPORT_SYMBOL_GPL(cpuidle_disable_device);
> >
> > static void __cpuidle_unregister_device(struct cpuidle_device *dev)
> > {
> > - struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> > -
> > list_del(&dev->device_list);
> > per_cpu(cpuidle_devices, dev->cpu) = NULL;
> > - module_put(drv->owner);
> > }
> >
> > static int __cpuidle_device_init(struct cpuidle_device *dev) @@
> > -384,6 +381,8 @@ static int __cpuidle_register_device(struct
> cpuidle_device *dev)
> > per_cpu(cpuidle_devices, dev->cpu) = dev;
> > list_add(&dev->device_list, &cpuidle_detected_devices);
> >
> > + module_put(drv->owner);
> > +
> > ret = cpuidle_coupled_register_device(dev);
> > if (ret) {
> > __cpuidle_unregister_device(dev);
> >
>
>
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