Please merge; the CONFIG_USB_SUSPEND patch depends on it.

This hub patch:

 - updates internal docs about locking, matching current usage
   for device state spinlock and dev->serialize semaphore

 - adds locktree() to use with signaling that affect everything
   downstream of a given device ... right now just khubd uses it,
   but usb_reset_device() should too (not just with hub resets...)

 - adds hub_quiesce()/hub_reactivate() ... former is used now
   during shutdown, both are needed in suspend/resume paths

Net change in behavior for current systems should be nothing.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>