[PATCH] device_shutdown can loop if the driver frees itself

This patch changes device_shutdown() to use the newly introduced safe
reverse list traversal. We experienced loops on system reboot if we had
removed and re-inserted our device from the device list.

We noticed this problem on PPC405. Our PCI IDE device comes and goes a lot.

Our hypothesis was that there was a loop caused by the driver->shutdown
freeing memory. It is possible that we do something wrong as well, but
being unable to reboot is kind of nasty.

Signed-off-by: Michael Richardson <[e-mail]>
Cc: Patrick Mochel <[e-mail]>
Cc: David Howells <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/base/power/shutdown.c

···
  */
 void device_shutdown(void)
 {
-	struct device * dev;
+	struct device * dev, *devn;
 
 	down_write(&devices_subsys.rwsem);
-	list_for_each_entry_reverse(dev, &devices_subsys.kset.list,
+	list_for_each_entry_safe_reverse(dev, devn, &devices_subsys.kset.list,
 				kobj.entry) {
 		if (dev->bus && dev->bus->shutdown) {
 			dev_dbg(dev, "shutdown\n");