USB-BKL: Remove BKL use for usb serial driver probing
The usb serial driver initialization tried to use the BKL to stop
driver modules from unloading, but that didn't work anyways.
There was already some code to do proper try_module_get,
but it was conditional on having a new probe interface.
I checked all the low level drivers and they all have proper
.owner = THIS_MODULE, so it's ok to always use.
The other problem was the usb_serial_driver_list needing
protection by a lock. This was broken anyways because unregister
did not necessarily have the BKL.
I extended the extending table_lock mutex to protect this case too.
With these changes the BKL can be removed here.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 941c2d4..443468e 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -653,6 +653,7 @@
return id;
}
+/* Caller must hold table_lock */
static struct usb_serial_driver *search_serial_device(
struct usb_interface *iface)
{
@@ -718,17 +719,23 @@
int num_ports = 0;
int max_endpoints;
- lock_kernel(); /* guard against unloading a serial driver module */
+ mutex_lock(&table_lock);
type = search_serial_device(interface);
if (!type) {
- unlock_kernel();
+ mutex_unlock(&table_lock);
dbg("none matched");
return -ENODEV;
}
+ if (!try_module_get(type->driver.owner)) {
+ mutex_unlock(&table_lock);
+ dev_err(&interface->dev, "module get failed, exiting\n");
+ return -EIO;
+ }
+ mutex_unlock(&table_lock);
+
serial = create_serial(dev, interface, type);
if (!serial) {
- unlock_kernel();
dev_err(&interface->dev, "%s - out of memory\n", __func__);
return -ENOMEM;
}
@@ -737,20 +744,11 @@
if (type->probe) {
const struct usb_device_id *id;
- if (!try_module_get(type->driver.owner)) {
- unlock_kernel();
- dev_err(&interface->dev,
- "module get failed, exiting\n");
- kfree(serial);
- return -EIO;
- }
-
id = get_iface_id(type, interface);
retval = type->probe(serial, id);
module_put(type->driver.owner);
if (retval) {
- unlock_kernel();
dbg("sub driver rejected device");
kfree(serial);
return retval;
@@ -822,7 +820,6 @@
* properly during a later invocation of usb_serial_probe
*/
if (num_bulk_in == 0 || num_bulk_out == 0) {
- unlock_kernel();
dev_info(&interface->dev, "PL-2303 hack: descriptors matched but endpoints did not\n");
kfree(serial);
return -ENODEV;
@@ -835,7 +832,6 @@
if (type == &usb_serial_generic_device) {
num_ports = num_bulk_out;
if (num_ports == 0) {
- unlock_kernel();
dev_err(&interface->dev,
"Generic device with no bulk out, not allowed.\n");
kfree(serial);
@@ -847,7 +843,6 @@
/* if this device type has a calc_num_ports function, call it */
if (type->calc_num_ports) {
if (!try_module_get(type->driver.owner)) {
- unlock_kernel();
dev_err(&interface->dev,
"module get failed, exiting\n");
kfree(serial);
@@ -878,7 +873,6 @@
max_endpoints = max(max_endpoints, num_interrupt_out);
max_endpoints = max(max_endpoints, (int)serial->num_ports);
serial->num_port_pointers = max_endpoints;
- unlock_kernel();
dbg("%s - setting up %d port structures for this device",
__func__, max_endpoints);
@@ -1349,6 +1343,7 @@
driver->description = driver->driver.name;
/* Add this device to our list of devices */
+ mutex_lock(&table_lock);
list_add(&driver->driver_list, &usb_serial_driver_list);
retval = usb_serial_bus_register(driver);
@@ -1360,6 +1355,7 @@
printk(KERN_INFO "USB Serial support registered for %s\n",
driver->description);
+ mutex_unlock(&table_lock);
return retval;
}
EXPORT_SYMBOL_GPL(usb_serial_register);
@@ -1370,8 +1366,10 @@
/* must be called with BKL held */
printk(KERN_INFO "USB Serial deregistering driver %s\n",
device->description);
+ mutex_lock(&table_lock);
list_del(&device->driver_list);
usb_serial_bus_deregister(device);
+ mutex_unlock(&table_lock);
}
EXPORT_SYMBOL_GPL(usb_serial_deregister);