Re: [PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplugevent.

[Tang Chen]

On 10/25/2012 01:33 AM, Toshi Kani wrote:
> On Tue, 2012-10-23 at 21:10 +0800, Tang Chen wrote:
> > As the comments in __acpi_os_execute() said:
> >
> > 	We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
> > 	because the hotplug code may call driver .remove() functions,
> > 	which invoke flush_scheduled_work/acpi_os_wait_events_complete
> > 	to flush these workqueues.
> >
> > we should keep the hotplug code in kacpi_hotplug_wq.
> >
> > But we have the following call series in kernel now:
> > 	acpi_ev_queue_notify_request()
> > 	|-->  acpi_os_execute()
> > 	     |-->  __acpi_os_execute(type, function, context, 0)
> >
> > The last parameter 0 makes the container_notify_cb() executed in
> > kacpi_notify_wq or kacpid_wq. So, we need to put the real hotplug code
> > into kacpi_hotplug_wq.
>
> Hi Tang,
>
> I am curious; is there a particular reason why you use
> alloc_acpi_container_hp_work() instead of acpi_os_hotplug_execute(),
> which is already there in the tree?

Hi Toshi,

Thanks for telling me this. I didn't realize this function. :)
And yes, it is better.

Thanks. :)

> Thanks,
> -Toshi
>
>
> > Signed-off-by: Tang Chen<tangchen@xxxxxxxxxxxxxx>
> > ---
> >   drivers/acpi/container.c |   44 +++++++++++++++++++++++++++++++++++++++++++-
> >   1 files changed, 43 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
> > index 1f9f7d7..643657a 100644
> > --- a/drivers/acpi/container.c
> > +++ b/drivers/acpi/container.c
> > @@ -72,8 +72,36 @@ static struct acpi_driver acpi_container_driver = {
> >   		},
> >   };
> >
> > +struct acpi_container_hp_work {
> > +	struct work_struct work;
> > +	acpi_handle handle;
> > +	u32 type;
> > +	void *context;
> > +};
> > +
> >   /*******************************************************************/
> >
> > +static void alloc_acpi_container_hp_work(acpi_handle handle, u32 type,
> > +					void *context,
> > +					void (*func)(struct work_struct *work))
> > +{
> > +	struct acpi_container_hp_work *hp_work;
> > +	int ret;
> > +
> > +	hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
> > +	if (!hp_work)
> > +		return;
> > +
> > +	hp_work->handle = handle;
> > +	hp_work->type = type;
> > +	hp_work->context = context;
> > +
> > +	INIT_WORK(&hp_work->work, func);
> > +	ret = queue_work(kacpi_hotplug_wq,&hp_work->work);
> > +	if (!ret)
> > +		kfree(hp_work);
> > +}
> > +
> >   static int is_device_present(acpi_handle handle)
> >   {
> >   	acpi_handle temp;
> > @@ -152,14 +180,21 @@ static int container_device_add(struct acpi_device **device, acpi_handle handle)
> >   	return result;
> >   }
> >
> > -static void container_notify_cb(acpi_handle handle, u32 type, void *context)
> > +static void __container_notify_cb(struct work_struct *work)
> >   {
> >   	struct acpi_device *device = NULL;
> >   	int result;
> >   	int present;
> >   	acpi_status status;
> > +	struct acpi_container_hp_work *hp_work;
> > +	acpi_handle handle;
> > +	u32 type;
> >   	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
> >
> > +	hp_work = container_of(work, struct acpi_container_hp_work, work);
> > +	handle = hp_work->handle;
> > +	type = hp_work->type;
> > +
> >   	switch (type) {
> >   	case ACPI_NOTIFY_BUS_CHECK:
> >   		/* Fall through */
> > @@ -211,6 +246,13 @@ static void container_notify_cb(acpi_handle handle, u32 type, void *context)
> >   	return;
> >   }
> >
> > +static void container_notify_cb(acpi_handle handle, u32 type,
> > +				void *context)
> > +{
> > +	alloc_acpi_container_hp_work(handle, type, context,
> > +				__container_notify_cb);
> > +}
> > +
> >   static acpi_status
> >   container_walk_namespace_cb(acpi_handle handle,
> >   			    u32 lvl, void *context, void **rv)
>
>
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