ACPI / hotplug: Consolidate deferred execution of ACPI hotplug routines

There are two different interfaces for queuing up work items on the
ACPI hotplug workqueue, alloc_acpi_hp_work() used by PCI and PCI host
bridge hotplug code and acpi_os_hotplug_execute() used by the common
ACPI hotplug code and docking stations.  They both are somewhat
cumbersome to use and work slightly differently.

The users of alloc_acpi_hp_work() have to submit a work function that
will extract the necessary data items from a struct acpi_hp_work
object allocated by alloc_acpi_hp_work() and then will free that
object, while it would be more straightforward to simply use a work
function with one more argument and let the interface take care of
the execution details.

The users of acpi_os_hotplug_execute() also have to deal with the
fact that it takes only one argument in addition to the work function
pointer, although acpi_os_execute_deferred() actually takes care of
the allocation and freeing of memory, so it would have been able to
pass more arguments to the work function if it hadn't been
constrained by the connection with acpi_os_execute().

Moreover, while alloc_acpi_hp_work() makes GFP_KERNEL memory
allocations, which is correct, because hotplug work items are
always queued up from process context, acpi_os_hotplug_execute()
uses GFP_ATOMIC, as that is needed by acpi_os_execute().  Also,
acpi_os_execute_deferred() queued up by it waits for the ACPI event
workqueues to flush before executing the work function, whereas
alloc_acpi_hp_work() can't do anything similar.  That leads to
somewhat arbitrary differences in behavior between various ACPI
hotplug code paths and has to be straightened up.

For this reason, replace both alloc_acpi_hp_work() and
acpi_os_hotplug_execute() with a single interface,
acpi_hotplug_execute(), combining their behavior and being more
friendly to its users than any of the two.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 46 insertions, 50 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index e5f416c7f66e..cfc3e260a688 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -61,7 +61,6 @@ struct acpi_os_dpc {
 	acpi_osd_exec_callback function;
 	void *context;
 	struct work_struct work;
-	int wait;
 };
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -1067,9 +1066,6 @@ static void acpi_os_execute_deferred(struct work_struct *work)
 {
 	struct acpi_os_dpc *dpc = container_of(work, struct acpi_os_dpc, work);
 
-	if (dpc->wait)
-		acpi_os_wait_events_complete();
-
 	dpc->function(dpc->context);
 	kfree(dpc);
 }
@@ -1089,8 +1085,8 @@ static void acpi_os_execute_deferred(struct work_struct *work)
  *
  ******************************************************************************/
 
-static acpi_status __acpi_os_execute(acpi_execute_type type,
-	acpi_osd_exec_callback function, void *context, int hp)
+acpi_status acpi_os_execute(acpi_execute_type type,
+			    acpi_osd_exec_callback function, void *context)
 {
 	acpi_status status = AE_OK;
 	struct acpi_os_dpc *dpc;
@@ -1117,20 +1113,11 @@ static acpi_status __acpi_os_execute(acpi_execute_type type,
 	dpc->context = context;
 
 	/*
-	 * 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.
-	 *
 	 * To prevent lockdep from complaining unnecessarily, make sure that
 	 * there is a different static lockdep key for each workqueue by using
 	 * INIT_WORK() for each of them separately.
 	 */
-	if (hp) {
-		queue = kacpi_hotplug_wq;
-		dpc->wait = 1;
-		INIT_WORK(&dpc->work, acpi_os_execute_deferred);
-	} else if (type == OSL_NOTIFY_HANDLER) {
+	if (type == OSL_NOTIFY_HANDLER) {
 		queue = kacpi_notify_wq;
 		INIT_WORK(&dpc->work, acpi_os_execute_deferred);
 	} else {
@@ -1155,28 +1142,59 @@ static acpi_status __acpi_os_execute(acpi_execute_type type,
 	}
 	return status;
 }
+EXPORT_SYMBOL(acpi_os_execute);
 
-acpi_status acpi_os_execute(acpi_execute_type type,
-			    acpi_osd_exec_callback function, void *context)
+void acpi_os_wait_events_complete(void)
 {
-	return __acpi_os_execute(type, function, context, 0);
+	flush_workqueue(kacpid_wq);
+	flush_workqueue(kacpi_notify_wq);
 }
-EXPORT_SYMBOL(acpi_os_execute);
 
-acpi_status acpi_os_hotplug_execute(acpi_osd_exec_callback function,
-	void *context)
+struct acpi_hp_work {
+	struct work_struct work;
+	acpi_hp_callback func;
+	void *data;
+	u32 src;
+};
+
+static void acpi_hotplug_work_fn(struct work_struct *work)
 {
-	return __acpi_os_execute(0, function, context, 1);
+	struct acpi_hp_work *hpw = container_of(work, struct acpi_hp_work, work);
+
+	acpi_os_wait_events_complete();
+	hpw->func(hpw->data, hpw->src);
+	kfree(hpw);
 }
-EXPORT_SYMBOL(acpi_os_hotplug_execute);
 
-void acpi_os_wait_events_complete(void)
+acpi_status acpi_hotplug_execute(acpi_hp_callback func, void *data, u32 src)
 {
-	flush_workqueue(kacpid_wq);
-	flush_workqueue(kacpi_notify_wq);
+	struct acpi_hp_work *hpw;
+
+	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
+		  "Scheduling function [%p(%p, %u)] for deferred execution.\n",
+		  func, data, src));
+
+	hpw = kmalloc(sizeof(*hpw), GFP_KERNEL);
+	if (!hpw)
+		return AE_NO_MEMORY;
+
+	INIT_WORK(&hpw->work, acpi_hotplug_work_fn);
+	hpw->func = func;
+	hpw->data = data;
+	hpw->src = src;
+	/*
+	 * We can't run hotplug code in kacpid_wq/kacpid_notify_wq etc., because
+	 * the hotplug code may call driver .remove() functions, which may
+	 * invoke flush_scheduled_work()/acpi_os_wait_events_complete() to flush
+	 * these workqueues.
+	 */
+	if (!queue_work(kacpi_hotplug_wq, &hpw->work)) {
+		kfree(hpw);
+		return AE_ERROR;
+	}
+	return AE_OK;
 }
 
-EXPORT_SYMBOL(acpi_os_wait_events_complete);
 
 acpi_status
 acpi_os_create_semaphore(u32 max_units, u32 initial_units, acpi_handle * handle)
@@ -1825,25 +1843,3 @@ void acpi_os_set_prepare_extended_sleep(int (*func)(u8 sleep_state,
 {
 	__acpi_os_prepare_extended_sleep = func;
 }
-
-
-void alloc_acpi_hp_work(acpi_handle handle, u32 type, void *context,
-			void (*func)(struct work_struct *work))
-{
-	struct acpi_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);
-}
-EXPORT_SYMBOL_GPL(alloc_acpi_hp_work);