libusual interface [was Re: libusual and ub]

[Bill Nottingham]

Pete Zaitcev (zaitcev at redhat.com) said: 
> Hi, Dave, Jeremy, and others:
> 
> I think now may be the time to enable ub in Rawhide and see if it sticks.
> The problem it is trying to address is to have fewer oopses and/or lockups
> related to the usb-storage. I have to say, I do not see all that many
> these days, but when they do happen, it always happens as if on purpose
> to break our schedule.
> 
> Since ub does not support all storage devices, and never will, I developed
> a way for it to coexist with usb-storage. A patch called "libusual"
> provides the necessary routing. It is attached at the bottom of this
> message, and I think is necessary if we are to have ub at all.

Coming in late to the party (as usual), I'd have to say that, outside
of any concerns about ub or usb-storage, I don't think libusual is the
right interface.

1) It breaks all 'normal' probing for devices, as the device tables
   are removed from the module. You have to hardcode one module or
   the other if you're running in an environment where the modules
   aren't in 'normal' locations
2) It circumvents the normal hotplug mechanisms... while you're still
   getting events to userspace about the USB device add, the kernel
   is (effectively) handling the event behind your back.
3) If you want to change which one you use, since libusual is built-in,
   you have to reboot. This seems to be sort of a non-starter.

I'd rather have the ids in the module as normal, and either:

a) we blacklist one of the drivers
b) we don't build one of the drivers
c) we turn off automatic binding, and use the bind/unbind features
   to handle it

Bill