driver core: add BUS_NOTIFY_UNBOUND_DRIVER event

This patch adds a new bus notifier event which is emitted _after_ a
device is removed from its driver. This event will be used by the
dma-api debug code to check if a driver has released all dma allocations
for that device.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/base/dd.c

@@ -320,6 +320,10 @@ static void __device_release_driver(struct device *dev)
 		devres_release_all(dev);
 		dev->driver = NULL;
 		klist_remove(&dev->p->knode_driver);
+		if (dev->bus)
+			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
+						     BUS_NOTIFY_UNBOUND_DRIVER,
+						     dev);
 	}
 }
 

include/linux/device.h

@@ -114,6 +114,8 @@ extern int bus_unregister_notifier(struct bus_type *bus,
 #define BUS_NOTIFY_BOUND_DRIVER		0x00000003 /* driver bound to device */
 #define BUS_NOTIFY_UNBIND_DRIVER	0x00000004 /* driver about to be
 						      unbound */
+#define BUS_NOTIFY_UNBOUND_DRIVER	0x00000005 /* driver is unbound
+						      from the device */
 
 extern struct kset *bus_get_kset(struct bus_type *bus);
 extern struct klist *bus_get_device_klist(struct bus_type *bus);