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usb-serial: new API for driver registration
This patch (as1522) adds two new routines to the usb-serial core, for registering and unregistering serial drivers. Instead of registering the usb_driver and usb_serial_drivers separately, with error checking for each one, the drivers can all be registered and unregistered by a single function call. This reduces duplicated code. More importantly, the new core routines change the order in which the drivers are registered. Currently the usb-serial drivers are all registered first and the usb_driver is done last, which leaves a window for problems. A udev script may quickly add a new dynamic-ID for a usb-serial driver, causing the corresponding usb_driver to be probed. If the usb_driver hasn't been registered yet then an oops will occur. The new routine prevents such problems by registering the usb_driver first. To insure that it gets probed properly for already-attached serial devices, we call driver_attach() after all the usb-serial drivers have been registered. Along with adding the new routines, the patch modifies the "generic" serial driver to use them. Further patches will similarly modify all the other in-tree USB serial drivers. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -54,7 +54,6 @@ static struct usb_driver generic_driver = {
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.probe = generic_probe,
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.disconnect = usb_serial_disconnect,
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.id_table = generic_serial_ids,
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.no_dynamic_id = 1,
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};
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/* All of the device info needed for the Generic Serial Converter */
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@ -64,7 +63,6 @@ struct usb_serial_driver usb_serial_generic_device = {
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.name = "generic",
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},
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.id_table = generic_device_ids,
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.usb_driver = &generic_driver,
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.num_ports = 1,
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.disconnect = usb_serial_generic_disconnect,
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.release = usb_serial_generic_release,
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@ -73,6 +71,10 @@ struct usb_serial_driver usb_serial_generic_device = {
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.resume = usb_serial_generic_resume,
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};
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static struct usb_serial_driver * const serial_drivers[] = {
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&usb_serial_generic_device, NULL
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};
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static int generic_probe(struct usb_interface *interface,
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const struct usb_device_id *id)
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{
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@ -97,13 +99,7 @@ int usb_serial_generic_register(int _debug)
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USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT;
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/* register our generic driver with ourselves */
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retval = usb_serial_register(&usb_serial_generic_device);
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if (retval)
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goto exit;
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retval = usb_register(&generic_driver);
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if (retval)
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usb_serial_deregister(&usb_serial_generic_device);
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exit:
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retval = usb_serial_register_drivers(&generic_driver, serial_drivers);
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#endif
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return retval;
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}
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@ -112,8 +108,7 @@ void usb_serial_generic_deregister(void)
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{
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#ifdef CONFIG_USB_SERIAL_GENERIC
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/* remove our generic driver */
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usb_deregister(&generic_driver);
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usb_serial_deregister(&usb_serial_generic_device);
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usb_serial_deregister_drivers(&generic_driver, serial_drivers);
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#endif
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}
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@ -1338,6 +1338,11 @@ static void fixup_generic(struct usb_serial_driver *device)
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set_to_generic_if_null(device, prepare_write_buffer);
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}
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/*
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* The next two routines are mainly for internal use.
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* They are exported only for out-of-tree modules.
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* New drivers should call usb_serial_{de}register_drivers() instead.
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*/
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int usb_serial_register(struct usb_serial_driver *driver)
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{
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int retval;
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@ -1386,6 +1391,76 @@ void usb_serial_deregister(struct usb_serial_driver *device)
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}
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EXPORT_SYMBOL_GPL(usb_serial_deregister);
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/**
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* usb_serial_register_drivers - register drivers for a usb-serial module
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* @udriver: usb_driver used for matching devices/interfaces
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* @serial_drivers: NULL-terminated array of pointers to drivers to be registered
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*
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* Registers @udriver and all the drivers in the @serial_drivers array.
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* Automatically fills in the .no_dynamic_id field in @udriver and
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* the .usb_driver field in each serial driver.
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*/
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int usb_serial_register_drivers(struct usb_driver *udriver,
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struct usb_serial_driver * const serial_drivers[])
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{
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int rc;
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const struct usb_device_id *saved_id_table;
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struct usb_serial_driver * const *sd;
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/*
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* udriver must be registered before any of the serial drivers,
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* because the store_new_id() routine for the serial drivers (in
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* bus.c) probes udriver.
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*
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* Performance hack: We don't want udriver to be probed until
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* the serial drivers are registered, because the probe would
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* simply fail for lack of a matching serial driver.
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* Therefore save off udriver's id_table until we are all set.
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*/
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saved_id_table = udriver->id_table;
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udriver->id_table = NULL;
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udriver->no_dynamic_id = 1;
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rc = usb_register(udriver);
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if (rc)
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return rc;
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for (sd = serial_drivers; *sd; ++sd) {
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(*sd)->usb_driver = udriver;
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rc = usb_serial_register(*sd);
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if (rc)
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goto failed;
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}
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/* Now restore udriver's id_table and look for matches */
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udriver->id_table = saved_id_table;
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rc = driver_attach(&udriver->drvwrap.driver);
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return 0;
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failed:
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while (sd-- > serial_drivers)
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usb_serial_deregister(*sd);
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usb_deregister(udriver);
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return rc;
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}
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EXPORT_SYMBOL_GPL(usb_serial_register_drivers);
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/**
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* usb_serial_deregister_drivers - deregister drivers for a usb-serial module
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* @udriver: usb_driver to unregister
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* @serial_drivers: NULL-terminated array of pointers to drivers to be deregistered
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*
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* Deregisters @udriver and all the drivers in the @serial_drivers array.
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*/
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void usb_serial_deregister_drivers(struct usb_driver *udriver,
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struct usb_serial_driver * const serial_drivers[])
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{
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for (; *serial_drivers; ++serial_drivers)
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usb_serial_deregister(*serial_drivers);
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usb_deregister(udriver);
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}
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EXPORT_SYMBOL_GPL(usb_serial_deregister_drivers);
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/* Module information */
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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@ -300,8 +300,17 @@ struct usb_serial_driver {
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#define to_usb_serial_driver(d) \
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container_of(d, struct usb_serial_driver, driver)
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/*
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* These two routines are kept only for backward compatibility.
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* Don't use them; call usb_serial_{de}register_drivers() instead.
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*/
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extern int usb_serial_register(struct usb_serial_driver *driver);
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extern void usb_serial_deregister(struct usb_serial_driver *driver);
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extern int usb_serial_register_drivers(struct usb_driver *udriver,
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struct usb_serial_driver * const serial_drivers[]);
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extern void usb_serial_deregister_drivers(struct usb_driver *udriver,
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struct usb_serial_driver * const serial_drivers[]);
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extern void usb_serial_port_softint(struct usb_serial_port *port);
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extern int usb_serial_probe(struct usb_interface *iface,
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