driver core: remove polling for driver_probe_done(v5)

This patch removes 100ms polling for driver_probe_done in
wait_for_device_probe(), and uses wait_event() instead.
Removing polling in fs initialization may lead to
a faster boot.

This patch also changes the return type of wait_for_device_done()
from int to void.

This patch is against Arjan's patch in linux-next tree.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/dd.c

@@ -172,16 +172,12 @@ int driver_probe_done(void)
 /**
  * wait_for_device_probe
  * Wait for device probing to be completed.
- *
- * Note: this function polls at 100 msec intervals.
  */
-int wait_for_device_probe(void)
+void wait_for_device_probe(void)
 {
 	/* wait for the known devices to complete their probing */
-	while (driver_probe_done() != 0)
-		msleep(100);
+	wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 	async_synchronize_full();
-	return 0;
 }
 
 /**

include/linux/device.h

@@ -147,7 +147,7 @@ extern void put_driver(struct device_driver *drv);
 extern struct device_driver *driver_find(const char *name,
 					 struct bus_type *bus);
 extern int driver_probe_done(void);
-extern int wait_for_device_probe(void);
+extern void wait_for_device_probe(void);
 
 
 /* sysfs interface for exporting driver attributes */