diff options
| author | Zhang Rui <rui.zhang@intel.com> | 2009-06-23 10:20:29 +0800 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2009-06-23 23:23:14 -0400 |
| commit | c02256be79a1a3557332ac51e653d574a2a7d2b5 (patch) | |
| tree | cad4af410464c14f0641148929b32bf3ab82ebd6 /drivers | |
| parent | 07a2039b8eb0af4ff464efd3dfd95de5c02648c6 (diff) | |
| download | lwn-c02256be79a1a3557332ac51e653d574a2a7d2b5.tar.gz lwn-c02256be79a1a3557332ac51e653d574a2a7d2b5.zip | |
ACPI: fix a deadlock in hotplug case
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/acpi/osl.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index d916bea729f1..71670719d61a 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -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; - ret = queue_work(queue, &dpc->work); - } else { - INIT_WORK(&dpc->work, acpi_os_execute_hp_deferred); - ret = schedule_work(&dpc->work); - } + /* + * 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); if (!ret) { printk(KERN_ERR PREFIX |