[PATCH 4/4] Driver core: bus_rescan_devices improper locking

[Dmitry Torokhov <dtor_core@ameritech.net>]

===================================================================


ChangeSet@1.1958, 2004-10-30 03:13:25-05:00, dtor_core@ameritech.net
  Driver core: bus_rescan_devices() should take write lock to guarantee
               that 2 threads will not probe same device and therefore
               can not be implemented with bus_for_each_dev().
  
  Signed-off-by: Dmitry Torokhov <dtor@mail.ru>


 bus.c |   24 +++++++++++-------------
 1 files changed, 11 insertions(+), 13 deletions(-)


===================================================================



diff -Nru a/drivers/base/bus.c b/drivers/base/bus.c
--- a/drivers/base/bus.c	2004-10-30 03:15:58 -05:00
+++ b/drivers/base/bus.c	2004-10-30 03:15:58 -05:00
@@ -571,18 +571,6 @@
 }
 
 
-/* Helper for bus_rescan_devices's iter */
-static int bus_rescan_devices_helper(struct device *dev, void *data)
-{
-	int *count = data;
-
-	if (!dev->driver && device_attach(dev))
-		(*count)++;
-
-	return 0;
-}
-
-
 /**
  *	bus_rescan_devices - rescan devices on the bus for possible drivers
  *	@bus:	the bus to scan.
@@ -594,9 +582,19 @@
  */
 int bus_rescan_devices(struct bus_type * bus)
 {
+	struct device *dev;
 	int count = 0;
 
-	bus_for_each_dev(bus, NULL, &count, bus_rescan_devices_helper);
+	if (!(bus = get_bus(bus)))
+		return 0;
+
+	down_write(&bus->subsys.rwsem);
+	list_for_each_entry(dev, &bus->devices.list, bus_list) {
+		if (!dev->driver && device_attach(dev))
+			count++;
+	}
+	up_write(&bus->subsys.rwsem);
+	put_bus(bus);
 
 	return count;
 }