From 765e0ba62613fb90f09c1b5926750df0aa56f349 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 23 Feb 2012 14:55:59 -0500 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/usb-serial.c | 75 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) (limited to 'drivers/usb/serial/usb-serial.c') diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 611b206591c..45b3658c601 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -1338,6 +1338,11 @@ static void fixup_generic(struct usb_serial_driver *device) set_to_generic_if_null(device, prepare_write_buffer); } +/* + * The next two routines are mainly for internal use. + * They are exported only for out-of-tree modules. + * New drivers should call usb_serial_{de}register_drivers() instead. + */ int usb_serial_register(struct usb_serial_driver *driver) { int retval; @@ -1386,6 +1391,76 @@ void usb_serial_deregister(struct usb_serial_driver *device) } EXPORT_SYMBOL_GPL(usb_serial_deregister); +/** + * usb_serial_register_drivers - register drivers for a usb-serial module + * @udriver: usb_driver used for matching devices/interfaces + * @serial_drivers: NULL-terminated array of pointers to drivers to be registered + * + * Registers @udriver and all the drivers in the @serial_drivers array. + * Automatically fills in the .no_dynamic_id field in @udriver and + * the .usb_driver field in each serial driver. + */ +int usb_serial_register_drivers(struct usb_driver *udriver, + struct usb_serial_driver * const serial_drivers[]) +{ + int rc; + const struct usb_device_id *saved_id_table; + struct usb_serial_driver * const *sd; + + /* + * udriver must be registered before any of the serial drivers, + * because the store_new_id() routine for the serial drivers (in + * bus.c) probes udriver. + * + * Performance hack: We don't want udriver to be probed until + * the serial drivers are registered, because the probe would + * simply fail for lack of a matching serial driver. + * Therefore save off udriver's id_table until we are all set. + */ + saved_id_table = udriver->id_table; + udriver->id_table = NULL; + + udriver->no_dynamic_id = 1; + rc = usb_register(udriver); + if (rc) + return rc; + + for (sd = serial_drivers; *sd; ++sd) { + (*sd)->usb_driver = udriver; + rc = usb_serial_register(*sd); + if (rc) + goto failed; + } + + /* Now restore udriver's id_table and look for matches */ + udriver->id_table = saved_id_table; + rc = driver_attach(&udriver->drvwrap.driver); + return 0; + + failed: + while (sd-- > serial_drivers) + usb_serial_deregister(*sd); + usb_deregister(udriver); + return rc; +} +EXPORT_SYMBOL_GPL(usb_serial_register_drivers); + +/** + * usb_serial_deregister_drivers - deregister drivers for a usb-serial module + * @udriver: usb_driver to unregister + * @serial_drivers: NULL-terminated array of pointers to drivers to be deregistered + * + * Deregisters @udriver and all the drivers in the @serial_drivers array. + */ +void usb_serial_deregister_drivers(struct usb_driver *udriver, + struct usb_serial_driver * const serial_drivers[]) +{ + for (; *serial_drivers; ++serial_drivers) + usb_serial_deregister(*serial_drivers); + usb_deregister(udriver); +} +EXPORT_SYMBOL_GPL(usb_serial_deregister_drivers); + /* Module information */ MODULE_AUTHOR(DRIVER_AUTHOR); MODULE_DESCRIPTION(DRIVER_DESC); -- cgit v1.2.3