This patch resolves a process hang in which a PCI card with a PCI-to-PCI
bridge is removed via the acpiphp driver.
The issue is that during the remove of the card an ACPI event occurs
which is erroneously added the kacpi_notify_wq queue. This add is done in
acpi_ev_queue_notify_request() via a call to acpi_os_execute().
Eventually, the event runs on the kacpi_notify_wq and the code attempts to
remove the card. During the hotplug remove of the device, the following
call sequence happens
cleanup_p2p_bridge()
-> cleanup_bridge()
-> acpi_remove_notify_handler()
-> acpi_os_wait_events_complete()
-> flush_workqueue(kacpi_notify_wq)
which is the queue we are currently executing on and the process will hang.
The problem is that the event is placed on the wrong queue. The code already
contains a kacpi_hotplug_wq queue for hotplug events to be added to in order
to prevent hangs like this.
In acpi_ev_queue_notify_request() the code should check to see if this is a
Ejection Request and if it is, add it the kacpi_hotplug_wq via a call to
acpi_os_hotplug_execute().
Cc: mjg@xxxxxxxxxx
Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
---
drivers/acpi/acpica/evmisc.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/acpi/acpica/evmisc.c b/drivers/acpi/acpica/evmisc.c
index d0b3318..a78aecc 100644
--- a/drivers/acpi/acpica/evmisc.c
+++ b/drivers/acpi/acpica/evmisc.c
@@ -181,9 +181,16 @@ acpi_ev_queue_notify_request(struct acpi_namespace_node * node,
notify_info->notify.value = (u16) notify_value;
notify_info->notify.handler_obj = handler_obj;
- status =
- acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_ev_notify_dispatch,
- notify_info);
+ /* Is this an Ejection Request? */
+ if (notify_value == 0x03)
+ status =
+ acpi_os_hotplug_execute(acpi_ev_notify_dispatch,
+ notify_info);
+ else
+ status = acpi_os_execute(OSL_NOTIFY_HANDLER,
+ acpi_ev_notify_dispatch,
+ notify_info);
+
if (ACPI_FAILURE(status)) {
acpi_ut_delete_generic_state(notify_info);
}
--
1.6.5.2
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