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

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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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