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@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/serial/generic.c | 17 +++------
drivers/usb/serial/usb-serial.c | 75 ++++++++++++++++++++++++++++++++++++++++
include/linux/usb/serial.h | 9 ++++
3 files changed, 90 insertions(+), 11 deletions(-)
Index: usb-3.3/include/linux/usb/serial.h
===================================================================
--- usb-3.3.orig/include/linux/usb/serial.h
+++ usb-3.3/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,
Index: usb-3.3/drivers/usb/serial/usb-serial.c
===================================================================
--- usb-3.3.orig/drivers/usb/serial/usb-serial.c
+++ usb-3.3/drivers/usb/serial/usb-serial.c
@@ -1338,6 +1338,11 @@ static void fixup_generic(struct usb_ser
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_se
}
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);
Index: usb-3.3/drivers/usb/serial/generic.c
===================================================================
--- usb-3.3.orig/drivers/usb/serial/generic.c
+++ usb-3.3/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_gene
.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_gene
.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 _deb
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
}
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