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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
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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,