ACPI / hotplug / PCI: Store acpi_device pointer in acpiphp_context

After recent modifications of the ACPI core making it create a struct
acpi_device object for every namespace node representing a device
regardless of the current status of that device the ACPIPHP code
can store a struct acpi_device pointer instead of an ACPI handle
in struct acpiphp_context.  This immediately makes it possible to
avoid making potentially costly calls to acpi_bus_get_device() in
two places and allows some more simplifications to be made going
forward.

The reason why that is correct is because ACPIPHP only installs
hotify handlers for namespace nodes that exist when
acpiphp_enumerate_slots() is called for their parent bridge.
That only happens if the parent bridge has an ACPI companion
associated with it, which means that the ACPI namespace scope
in question has been scanned already at that point.  That, in
turn, means that struct acpi_device objects have been created
for all namespace nodes in that scope and pointers to those
objects can be stored directly instead of their ACPI handles.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/pci/hotplug/acpiphp.h

@@ -117,8 +117,8 @@ struct acpiphp_func {
 };
 
 struct acpiphp_context {
-	acpi_handle handle;
 	struct acpiphp_func func;
+	struct acpi_device *adev;
 	struct acpiphp_bridge *bridge;
 	unsigned int refcount;
 };
@@ -128,9 +128,14 @@ static inline struct acpiphp_context *func_to_context(struct acpiphp_func *func)
 	return container_of(func, struct acpiphp_context, func);
 }
 
+static inline struct acpi_device *func_to_acpi_device(struct acpiphp_func *func)
+{
+	return func_to_context(func)->adev;
+}
+
 static inline acpi_handle func_to_handle(struct acpiphp_func *func)
 {
-	return func_to_context(func)->handle;
+	return func_to_acpi_device(func)->handle;
 }
 
 /*

drivers/pci/hotplug/acpiphp_glue.c

@@ -73,11 +73,11 @@ static void acpiphp_context_handler(acpi_handle handle, void *context)
 
 /**
  * acpiphp_init_context - Create hotplug context and grab a reference to it.
- * @handle: ACPI object handle to create the context for.
+ * @adev: ACPI device object to create the context for.
  *
  * Call under acpiphp_context_lock.
  */
-static struct acpiphp_context *acpiphp_init_context(acpi_handle handle)
+static struct acpiphp_context *acpiphp_init_context(struct acpi_device *adev)
 {
 	struct acpiphp_context *context;
 	acpi_status status;
@@ -86,9 +86,9 @@ static struct acpiphp_context *acpiphp_init_context(acpi_handle handle)
 	if (!context)
 		return NULL;
 
-	context->handle = handle;
+	context->adev = adev;
 	context->refcount = 1;
-	status = acpi_attach_data(handle, acpiphp_context_handler, context);
+	status = acpi_attach_data(adev->handle, acpiphp_context_handler, context);
 	if (ACPI_FAILURE(status)) {
 		kfree(context);
 		return NULL;
@@ -118,7 +118,7 @@ static struct acpiphp_context *acpiphp_get_context(acpi_handle handle)
 
 /**
  * acpiphp_put_context - Drop a reference to ACPI hotplug context.
- * @handle: ACPI object handle to put the context for.
+ * @context: ACPI hotplug context to drop a reference to.
  *
  * The context object is removed if there are no more references to it.
  *
@@ -130,7 +130,7 @@ static void acpiphp_put_context(struct acpiphp_context *context)
 		return;
 
 	WARN_ON(context->bridge);
-	acpi_detach_data(context->handle, acpiphp_context_handler);
+	acpi_detach_data(context->adev->handle, acpiphp_context_handler);
 	kfree(context);
 }
 
@@ -216,7 +216,7 @@ static void dock_event(acpi_handle handle, u32 type, void *data)
 
 	mutex_lock(&acpiphp_context_lock);
 	context = acpiphp_get_context(handle);
-	if (!context || WARN_ON(context->handle != handle)
+	if (!context || WARN_ON(context->adev->handle != handle)
 	    || context->func.parent->is_going_away) {
 		mutex_unlock(&acpiphp_context_lock);
 		return;
@@ -284,6 +284,7 @@ static acpi_status register_slot(acpi_handle handle, u32 lvl, void *data,
 {
 	struct acpiphp_bridge *bridge = data;
 	struct acpiphp_context *context;
+	struct acpi_device *adev;
 	struct acpiphp_slot *slot;
 	struct acpiphp_func *newfunc;
 	acpi_status status = AE_OK;
@@ -303,12 +304,14 @@ static acpi_status register_slot(acpi_handle handle, u32 lvl, void *data,
 				"can't evaluate _ADR (%#x)\n", status);
 		return AE_OK;
 	}
+	if (acpi_bus_get_device(handle, &adev))
+		return AE_OK;
 
 	device = (adr >> 16) & 0xffff;
 	function = adr & 0xffff;
 
 	mutex_lock(&acpiphp_context_lock);
-	context = acpiphp_init_context(handle);
+	context = acpiphp_init_context(adev);
 	if (!context) {
 		mutex_unlock(&acpiphp_context_lock);
 		acpi_handle_err(handle, "No hotplug context\n");
@@ -628,12 +631,8 @@ static void disable_slot(struct acpiphp_slot *slot)
 		if (PCI_SLOT(dev->devfn) == slot->device)
 			pci_stop_and_remove_bus_device(dev);
 
-	list_for_each_entry(func, &slot->funcs, sibling) {
-		struct acpi_device *adev;
-
-		if (!acpi_bus_get_device(func_to_handle(func), &adev))
-			acpi_bus_trim(adev);
-	}
+	list_for_each_entry(func, &slot->funcs, sibling)
+		acpi_bus_trim(func_to_acpi_device(func));
 
 	slot->flags &= (~SLOT_ENABLED);
 }
@@ -647,13 +646,10 @@ static bool slot_no_hotplug(struct acpiphp_slot *slot)
 {
 	struct acpiphp_func *func;
 
-	list_for_each_entry(func, &slot->funcs, sibling) {
-		struct acpi_device *adev = NULL;
-
-		acpi_bus_get_device(func_to_handle(func), &adev);
-		if (acpiphp_no_hotplug(adev))
+	list_for_each_entry(func, &slot->funcs, sibling)
+		if (acpiphp_no_hotplug(func_to_acpi_device(func)))
 			return true;
-	}
+
 	return false;
 }
 
@@ -908,7 +904,7 @@ static void hotplug_event(acpi_handle handle, u32 type, void *data)
 static void hotplug_event_work(void *data, u32 type)
 {
 	struct acpiphp_context *context = data;
-	acpi_handle handle = context->handle;
+	acpi_handle handle = context->adev->handle;
 
 	acpi_scan_lock_acquire();
 
@@ -967,7 +963,7 @@ static void handle_hotplug_event(acpi_handle handle, u32 type, void *data)
 
 	mutex_lock(&acpiphp_context_lock);
 	context = acpiphp_get_context(handle);
-	if (!context || WARN_ON(context->handle != handle)
+	if (!context || WARN_ON(context->adev->handle != handle)
 	    || context->func.parent->is_going_away)
 		goto err_out;
 
@@ -998,16 +994,18 @@ static void handle_hotplug_event(acpi_handle handle, u32 type, void *data)
 void acpiphp_enumerate_slots(struct pci_bus *bus)
 {
 	struct acpiphp_bridge *bridge;
+	struct acpi_device *adev;
 	acpi_handle handle;
 	acpi_status status;
 
 	if (acpiphp_disabled)
 		return;
 
-	handle = ACPI_HANDLE(bus->bridge);
-	if (!handle)
+	adev = ACPI_COMPANION(bus->bridge);
+	if (!adev)
 		return;
 
+	handle = adev->handle;
 	bridge = kzalloc(sizeof(struct acpiphp_bridge), GFP_KERNEL);
 	if (!bridge) {
 		acpi_handle_err(handle, "No memory for bridge object\n");