ukbd locking update

[Andriy Gapon]

on 20/12/2011 16:00 Attilio Rao said the following:
> 2011/12/20 Andriy Gapon <avg at freebsd.org>:
>>
>> I completing a patch that changes some locking in ukbd to account for
>> SCHEDULER_STOPPED and for other realities of the code.
>>
>> As a preview I would like to share couple of observations that had their effect
>> on the patch.
>>
>> 1. Acquiring Giant in device_attach, _detach in similar newbus method
>> implementations should be redundant because those are already executed with
>> Giant held.  That's done either by the general newbus code or via
>> usbd_enum_lock() when the operations are executed in the USB explore thread.
> 
> That's right, however, if you plan to axe those because of the newbus
> assumption I'd prefer you add a comment for every function you touch
> saying that it needs to be Giant protected (in order to cope with them
> once newbus is made MPSAFE).

I put mtx_assert there.  I think that that should be sufficiently
self-documenting and self-protecting too.

-- 
Andriy Gapon