linux-kernel - Re: [PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

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Date:	Thu, 25 Oct 2012 09:24:39 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	Toshi Kani <toshi.kani@...com>
CC:	yinghai@...nel.org, bhelgaas@...gle.com, lenb@...nel.org,
	jiang.liu@...wei.com, izumi.taku@...fujitsu.com,
	isimatu.yasuaki@...fujitsu.com, linux-acpi@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplug
 event.

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@...fujitsu.com>
>> ---
>>   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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