Re: [PATCH v3] rfkill: Add rfkill-any LED trigger

  - Handle the global mutex properly when rfkill_set_{hw,sw}_state()
or
    rfkill_set_states() is called from within an rfkill callback.  v2
    always tried to lock the global mutex in such a case, which led
to a
    deadlock when an rfkill driver called one of the above functions
    from its query or set_block callback.  This is solved by defining
a
    new bitfield, RFKILL_BLOCK_SW_HASLOCK, which is set before the
above
    callbacks are invoked and cleared afterwards; the functions
listed
    above use this bitfield to tell rfkill_any_led_trigger_event()
    whether the global mutex is currently held or not.
    RFKILL_BLOCK_SW_SETCALL cannot be reused for this purpose as
setting
    it before invoking the query callback would cause any calls to
    rfkill_set_sw_state() made from within that callback to work on
    RFKILL_BLOCK_SW_PREV instead of RFKILL_BLOCK_SW and thus change
the
    way rfkill_set_block() behaves.

I'm not super happy with this conditional locking - can't we instead
defer the necessary work to a workqueue, or so, for purposes of the
LED?

johannes