From: Alan Stern Date: Thu, 23 Feb 2012 19:55:59 +0000 (-0500) Subject: usb-serial: new API for driver registration X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=765e0ba62613fb90f09c1b5926750df0aa56f349;p=linux-beck.git 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 --- diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index 2a2fa2d0489d..664deb63807c 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -54,7 +54,6 @@ static struct usb_driver generic_driver = { .probe = generic_probe, .disconnect = usb_serial_disconnect, .id_table = generic_serial_ids, - .no_dynamic_id = 1, }; /* All of the device info needed for the Generic Serial Converter */ @@ -64,7 +63,6 @@ struct usb_serial_driver usb_serial_generic_device = { .name = "generic", }, .id_table = generic_device_ids, - .usb_driver = &generic_driver, .num_ports = 1, .disconnect = usb_serial_generic_disconnect, .release = usb_serial_generic_release, @@ -73,6 +71,10 @@ struct usb_serial_driver usb_serial_generic_device = { .resume = usb_serial_generic_resume, }; +static struct usb_serial_driver * const serial_drivers[] = { + &usb_serial_generic_device, NULL +}; + static int generic_probe(struct usb_interface *interface, const struct usb_device_id *id) { @@ -97,13 +99,7 @@ int usb_serial_generic_register(int _debug) USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT; /* register our generic driver with ourselves */ - retval = usb_serial_register(&usb_serial_generic_device); - if (retval) - goto exit; - retval = usb_register(&generic_driver); - if (retval) - usb_serial_deregister(&usb_serial_generic_device); -exit: + retval = usb_serial_register_drivers(&generic_driver, serial_drivers); #endif return retval; } @@ -112,8 +108,7 @@ void usb_serial_generic_deregister(void) { #ifdef CONFIG_USB_SERIAL_GENERIC /* remove our generic driver */ - usb_deregister(&generic_driver); - usb_serial_deregister(&usb_serial_generic_device); + usb_serial_deregister_drivers(&generic_driver, serial_drivers); #endif } diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 611b206591cb..45b3658c601f 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); diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h index 10cb74d2ad1d..8c8dbf9c5b89 100644 --- a/include/linux/usb/serial.h +++ b/include/linux/usb/serial.h @@ -300,8 +300,17 @@ struct usb_serial_driver { #define to_usb_serial_driver(d) \ container_of(d, struct usb_serial_driver, driver) +/* + * These two routines are kept only for backward compatibility. + * Don't use them; call usb_serial_{de}register_drivers() instead. + */ extern int usb_serial_register(struct usb_serial_driver *driver); extern void usb_serial_deregister(struct usb_serial_driver *driver); + +extern int usb_serial_register_drivers(struct usb_driver *udriver, + struct usb_serial_driver * const serial_drivers[]); +extern void usb_serial_deregister_drivers(struct usb_driver *udriver, + struct usb_serial_driver * const serial_drivers[]); extern void usb_serial_port_softint(struct usb_serial_port *port); extern int usb_serial_probe(struct usb_interface *iface,