On Fri, Feb 24, 2012 at 05:25:42PM -0500, Alan Stern wrote: > On Fri, 24 Feb 2012, Greg KH wrote: > > > On Thu, Feb 23, 2012 at 02:55:34PM -0500, Alan Stern wrote: > > > Greg: > > > > > > This series of patches adds a new, simpler API to the usb-serial core > > > for registering drivers, and changes all the existing drivers to use > > > it. Instead of making separate calls to register the usb_driver and > > > one or more usb_serial drivers, everything can be done with a single > > > function call. Likewise for deregistration. > > > > > > In addition, the order of registration is changed; the new routine will > > > register the usb_driver first. Currently each of the serial drivers > > > registers its usb_driver last, which leaves a window for a bug: If a > > > new dynamic-ID is added to the usb_serial driver before its usb_driver > > > is registered (say by a udev script), it causes an oops. > > > > > > This doesn't seem to be a very serious problem; so far there has been > > > only one complaint about it. For that reason, and because this is a > > > somewhat lengthy set of changes, I'm not going to submit it for the > > > stable kernels. > > > > > > I have been able to test this only with the pl2303 driver. All the > > > other drivers are merely compile-tested. > > > > I'm trying to remember why the ordering was set up this way, there was a > > good reason (good enough that we had to fix drivers that were doing it > > backwards.) But I can't remember it at the moment. > > It has to do with binding of pre-existing devices. If you don't take > proper care when first registering the usb_driver, the core will try to > bind that driver to all the pre-existing serial devices it matches. > But the bindings will fail, because usb-serial won't be able to find > the appropriate usb_serial drivers. As a result, the devices won't get > bound at all. Ah, yeah, that was it, thanks for figuring it out. > > Worse case, we have to switch it back, or fix it up somehow differently, > > this patch series will make it easier to do so in the future, so I'll go > > queue it up. Thanks for doing this work, it's much appreciated. > > You're welcome. Overall, it removes a lot of lines of duplicated code > from the source tree. I think I can now create a module_usb_serial_driver() macro to clean things up even more, now that we have reduced the init/exit module functions to a single function call. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
