On Thu, Jan 05, 2012 at 03:48:19PM -0500, Alan Stern wrote: > On Thu, 5 Jan 2012, Dmitry Torokhov wrote: > > > So I looked at the users of device_attach(): > > > > - we call it from generic bus code when adding a new driver so naturally > > driver is valid there; > > - serio and gameport call it by hand but they ensure that the driver is > > valid because they protected by subsystem-private mutex; > > - PCI, PCMCI, HID and USB new_id handling is tied to the driver itself > > and attributes are removed when driver is unregistered so there is no > > chance driver will be attached through newid after it has been > > unregistered; > > - agp_amd64_init calls it once immediately after registering the driver; > > - pci-stub driver is safe as well. > > Okay, that's all good. > > > That leaves only usb-serial which is problematic exactly as you > > described below. So I think we should remove get_driver() and > > put_driver(); document that caller if driver_attach() should ensure > > that driver is live and let usb-serial code solve this issue as this > > is the only code that plays games with drivers it does not own. > > If Greg confirms that there's nothing with registering the usb driver > before the usb_serial driver, I can fix the usb-serial code easily. > > Greg, do you know offhand whether this will break anything? It really > seems like the right thing to do, because the usb_serial driver uses > the usb driver but not vice versa. Hm, there was a reason I ordered the way I did, as I remember having to go fix up a number of drivers that did it in the reverse order. Give me a day or so to dig it up and figure out what is going on here, and to review this thread. 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
