[ACPI] create kacpid thread to handle ACPI work in process context.

Also will be needed for cpu hot-unplug.
from Anil S Keshavamurthy and David Shaohua Li
http://bugzilla.kernel.org/show_bug.cgi?id=2515

drivers/acpi/acpi_ksyms.c

@@ -106,7 +106,7 @@ EXPORT_SYMBOL(acpi_os_signal_semaphore);
 EXPORT_SYMBOL(acpi_os_create_semaphore);
 EXPORT_SYMBOL(acpi_os_delete_semaphore);
 EXPORT_SYMBOL(acpi_os_wait_semaphore);
-
+EXPORT_SYMBOL(acpi_os_wait_events_complete);
 EXPORT_SYMBOL(acpi_os_read_pci_configuration);
 
 /* ACPI Utilities (acpi_utils.c) */

drivers/acpi/events/evxface.c

@@ -406,6 +406,15 @@ acpi_remove_notify_handler (
 			goto unlock_and_exit;
 		}
 
+		/* Make sure all deferred tasks are completed */
+
+		(void) acpi_ut_release_mutex (ACPI_MTX_NAMESPACE);
+		acpi_os_wait_events_complete(NULL);
+		status = acpi_ut_acquire_mutex (ACPI_MTX_NAMESPACE);
+		if (ACPI_FAILURE (status)) {
+			return_ACPI_STATUS (status);
+ 		}
+
 		if (handler_type == ACPI_SYSTEM_NOTIFY) {
 			acpi_gbl_system_notify.node  = NULL;
 			acpi_gbl_system_notify.handler = NULL;
@@ -452,6 +461,15 @@ acpi_remove_notify_handler (
 			goto unlock_and_exit;
 		}
 
+		/* Make sure all deferred tasks are completed */
+
+		(void) acpi_ut_release_mutex (ACPI_MTX_NAMESPACE);
+		acpi_os_wait_events_complete(NULL);
+		status = acpi_ut_acquire_mutex (ACPI_MTX_NAMESPACE);
+		if (ACPI_FAILURE (status)) {
+			return_ACPI_STATUS (status);
+ 		}
+
 		/* Remove the handler */
 
 		if (handler_type == ACPI_SYSTEM_NOTIFY) {
@@ -614,6 +632,15 @@ acpi_remove_gpe_handler (
 		goto unlock_and_exit;
 	}
 
+	/* Make sure all deferred tasks are completed */
+
+	(void) acpi_ut_release_mutex (ACPI_MTX_EVENTS);
+	acpi_os_wait_events_complete(NULL);
+	status = acpi_ut_acquire_mutex (ACPI_MTX_EVENTS);
+	if (ACPI_FAILURE (status)) {
+		return_ACPI_STATUS (status);
+ 	}
+
 	/* Remove the handler */
 
 	acpi_os_acquire_lock (acpi_gbl_gpe_lock, ACPI_NOT_ISR);

drivers/acpi/osl.c

@@ -66,6 +66,7 @@ extern char line_buf[80];
 static unsigned int acpi_irq_irq;
 static OSD_HANDLER acpi_irq_handler;
 static void *acpi_irq_context;
+static struct workqueue_struct *kacpid_wq;
 
 acpi_status
 acpi_os_initialize(void)
@@ -80,6 +81,8 @@ acpi_os_initialize(void)
 		return AE_NULL_ENTRY;
 	}
 #endif
+	kacpid_wq = create_singlethread_workqueue("kacpid");
+	BUG_ON(!kacpid_wq);
 
 	return AE_OK;
 }
@@ -92,6 +95,8 @@ acpi_os_terminate(void)
 						 acpi_irq_handler);
 	}
 
+	destroy_workqueue(kacpid_wq);
+
 	return AE_OK;
 }
 
@@ -654,8 +659,8 @@ acpi_os_queue_for_execution(
 	task = (void *)(dpc+1);
 	INIT_WORK(task, acpi_os_execute_deferred, (void*)dpc);
 
-	if (!schedule_work(task)) {
-		ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Call to schedule_work() failed.\n"));
+	if (!queue_work(kacpid_wq, task)) {
+		ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Call to queue_work() failed.\n"));
 		kfree(dpc);
 		status = AE_ERROR;
 	}
@@ -663,6 +668,13 @@ acpi_os_queue_for_execution(
 	return_ACPI_STATUS (status);
 }
 
+void
+acpi_os_wait_events_complete(
+	void *context)
+{
+	flush_workqueue(kacpid_wq);
+}
+
 /*
  * Allocate the memory for a spinlock and initialize it.
  */

drivers/acpi/scan.c

@@ -318,8 +318,10 @@ static int acpi_driver_detach(struct acpi_driver * drv)
 		struct acpi_device * dev = container_of(node,struct acpi_device,g_list);
 
 		if (dev->driver == drv) {
+			spin_unlock(&acpi_device_lock);
 			if (drv->ops.remove)
 				drv->ops.remove(dev,ACPI_BUS_REMOVAL_NORMAL);
+			spin_lock(&acpi_device_lock);
 			dev->driver = NULL;
 			dev->driver_data = NULL;
 			atomic_dec(&drv->references);

include/acpi/acpiosxf.h

@@ -212,6 +212,10 @@ acpi_os_queue_for_execution (
 	OSD_EXECUTION_CALLBACK  function,
 	void                            *context);
 
+void
+acpi_os_wait_events_complete(
+	void * context);
+
 void
 acpi_os_sleep (
 	u32                             seconds,