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ACPI: fix a deadlock in hotplug case

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we used to run the hotplug code in keventd_wq.
But when hot removing the ACPI battery device,
power_supply_unregister invokes flush_scheduled_work.
This causes a deadlock. i.e
1. When dock is unplugged, all the hotplug code is run on kevent_wq.
2. the hotplug code removes all the child devices of dock device.
3. removing the child device may invoke flush_scheduled_work
4. flush_scheduled_work waits until all the work on kevent_wq to be
   finished, while this will never be true because the hotplug code
   is running on keventd_wq...

Introduce a new workqueue for hotplug in this patch.
http://bugzilla.kernel.org/show_bug.cgi?id=13533

Tested-by: Paul Martin <pm@debian.org>
Tested-by: Vojtech Gondzala <vojtech.gondzala@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Zhang Rui 2009-06-23 10:20:29 +08:00 committed by Len Brown
parent 07a2039b8e
commit c02256be79
1 changed files with 16 additions and 9 deletions
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23
drivers/acpi/osl.c
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@ -79,6 +79,7 @@ static acpi_osd_handler acpi_irq_handler;
static void *acpi_irq_context;
static struct workqueue_struct *kacpid_wq;
static struct workqueue_struct *kacpi_notify_wq;
static struct workqueue_struct *kacpi_hotplug_wq;
struct acpi_res_list {
resource_size_t start;
@ -192,8 +193,10 @@ acpi_status acpi_os_initialize1(void)
{
kacpid_wq = create_singlethread_workqueue("kacpid");
kacpi_notify_wq = create_singlethread_workqueue("kacpi_notify");
kacpi_hotplug_wq = create_singlethread_workqueue("kacpi_hotplug");
BUG_ON(!kacpid_wq);
BUG_ON(!kacpi_notify_wq);
BUG_ON(!kacpi_hotplug_wq);
return AE_OK;
}
@ -206,6 +209,7 @@ acpi_status acpi_os_terminate(void)
destroy_workqueue(kacpid_wq);
destroy_workqueue(kacpi_notify_wq);
destroy_workqueue(kacpi_hotplug_wq);
return AE_OK;
}
@ -716,6 +720,7 @@ static acpi_status __acpi_os_execute(acpi_execute_type type,
acpi_status status = AE_OK;
struct acpi_os_dpc *dpc;
struct workqueue_struct *queue;
work_func_t func;
int ret;
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
"Scheduling function [%p(%p)] for deferred execution.\n",
@ -740,15 +745,17 @@ static acpi_status __acpi_os_execute(acpi_execute_type type,
dpc->function = function;
dpc->context = context;
if (!hp) {
INIT_WORK(&dpc->work, acpi_os_execute_deferred);
queue = (type == OSL_NOTIFY_HANDLER) ?
kacpi_notify_wq : kacpid_wq;
/*
* 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.
*/
queue = hp ? kacpi_hotplug_wq :
(type == OSL_NOTIFY_HANDLER ? kacpi_notify_wq : kacpid_wq);
func = hp ? acpi_os_execute_hp_deferred : acpi_os_execute_deferred;
INIT_WORK(&dpc->work, func);
ret = queue_work(queue, &dpc->work);
} else {
INIT_WORK(&dpc->work, acpi_os_execute_hp_deferred);
ret = schedule_work(&dpc->work);
}
if (!ret) {
printk(KERN_ERR PREFIX