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

From: Tang Chen
Date: Tue Oct 23 2012 - 09:11:46 EST


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.

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)
--
1.7.1

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