tree b90fbcb954eb71bae7f9344c9668bb9f0e5f189a
parent 8520f38099ccfdac2147a0852f84ee7a8ee5e197
author Arjan van de Ven <arjan@linux.intel.com> 1222120810 -0700
committer Greg Kroah-Hartman <gregkh@suse.de> 1224279657 -0700

usbmon: fix tiny race exposed by the fastboot patches

usbmon registers the notifier chain, takes the bus lock and then goes to
scan the existing devices for hooking up.

Unfortunately, if usb_mon gets initialized while USB bus discovery is
going on, it's possible that usbmon gets a notifier on one cpu (which runs
without USB locks), and the scan is going on and also finds the new bus,
resulting in a double sysfs registration, which then produces a WARNING.

Pete Zaitcev did the bug diagnostics on this one

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>