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usb-serial: new API for driver registration

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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>
This commit is contained in:
Alan Stern 2012-02-23 14:55:59 -05:00 committed by Greg Kroah-Hartman
parent c69263c66e
commit 765e0ba626
3 changed files with 90 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

17
drivers/usb/serial/generic.c
View file

@ -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
}

75
drivers/usb/serial/usb-serial.c
View file

@ -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);

9
include/linux/usb/serial.h
View file

@ -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,