From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Common i/o layer fixes:
 - Add atomic onoff variable to ccw devices and ccw-group devices to
   avoid races during online/offline.
 - Fix pr_debug calls.
 - A lot of path fixes:
   + Set device to disconnected state after no path event.
   + Fix chpid vary on/off for single path devices.
   + Make logical vary on/off consistent with physical vary on/off.
   + Don't update subchannel schib if the device is gone (dnv not set).
   + Add code to recover lost chpids after machine checks.
   + Avoid processing link incidents, resource accessability events and
     chpid machine checks for logically offline chpids.
   + Recover disconnected devices after chsc machine checks.
   + Delay de-registering of no path devices to avoid deadlocks.
   + Don't redo ssd for known subchannels - the info is static.
   + Introduce a second, "slow" machine check handler thread for new devices.
     The "fast" machine check handler only recovers disconnected devices.
 - Deregister subchannel rather than ccw device on not oper events.
 - Fix calling sequence of notify function vs. path verification.
 - Reset timeout for disconnected devices.
 - Fix problem with debug feature and %s arguments.
 - Fix __get_subchannel_by_stsch to deal with "zombie" subchannels.
 - Avoid "zombie" subchannels if device is not operational during sense id.
 - Handle call to the io_subchannel remove function if the ccw device
   is not registered yet.
 - Add availability attribute for ccw devices: "good", "no device",
   "no path", "boxed".
 - Export ccw_device_work for qdio as module.
 - Retry sense id for tape devices which present intervention required.
 - Don't check the activity control to decide if the device driver interrupt
   handler needs to be called but use the bits in status control.
 - Fix race in ccw_device_stlck.
 - Accumulate deferred condition code.
 - Fix setting_up_sema locking.
 - Call qdio_shutdown instead of qdio_cleanup on failed establish.
 - Fix problem when 64 FCP adapters are initialized simultaneously.
 - Fix problem with >64 adapter interrupt capable devices.
 - Reduce stack usage in qdio.