Re: [PATCH] USB: add USB test and measurement class driver - round 2

Alan Stern
2008-08-27T19:16:29Z

On Wed, 27 Aug 2008, Oliver Neukum wrote:

> Am Mittwoch 27 August 2008 20:58:08 schrieb Alan Stern:
> > > And this rule depends on sharing the USB major or not. This needs
> > > a big fat mention in Documentation.
> >
> > You mean that the open/disconnect locking rule applies only to drivers
> > that call usb_register_dev, i.e, drivers using the USB major.  Right?
>
> Yes. In fact drivers not using the USB major but their own char devices
> will need such a lock. This is tricky.

IMO all char-device registration/deregistration routines should use a
similar rwsem. Then device drivers wouldn't need to worry about it.

> > I agree that it deserves to be mentioned in the documentation
> > somewhere.  Where would be a good place?  None of the existing files in
> > Documentation/usb seem appropriate.
>
> The USB major merits a file of its own.

I don't feel competent to start writing such a file. Greg, what do you
think? Maybe all that's needed to get going is to "borrow" some of the
material in LDD3. :-)

Alan Stern