Commit 765e0ba6 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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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: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c69263c6

drivers/usb/serial/generic.c

+6 −11
Original line number Diff line number Diff line
@@ -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

}

drivers/usb/serial/usb-serial.c

+75 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/usb/serial.h

+9 −0
Original line number Diff line number Diff line
@@ -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,

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