#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/smp_lock.h>
+#include <linux/rwsem.h>
#include <linux/usb.h>
#include <asm/io.h>
int nousb; /* Disable USB when built into kernel image */
/* Not honored on modular build */
+DECLARE_RWSEM(usb_all_devices_rwsem);
+EXPORT_SYMBOL(usb_all_devices_rwsem);
+
static int generic_probe (struct device *dev)
{
}
static struct device_driver usb_generic_driver = {
+ .owner = THIS_MODULE,
.name = "usb",
.bus = &usb_bus_type,
.probe = generic_probe,
if (!driver->probe)
return error;
+ /* FIXME we'd much prefer to just resume it ... */
if (interface_to_usbdev(intf)->state == USB_STATE_SUSPENDED)
return -EHOSTUNREACH;
id = usb_match_id (intf, driver->id_table);
if (id) {
dev_dbg (dev, "%s - got id\n", __FUNCTION__);
+ intf->condition = USB_INTERFACE_BINDING;
error = driver->probe (intf, id);
+ intf->condition = error ? USB_INTERFACE_UNBOUND :
+ USB_INTERFACE_BOUND;
}
return error;
struct usb_interface *intf = to_usb_interface(dev);
struct usb_driver *driver = to_usb_driver(intf->dev.driver);
+ intf->condition = USB_INTERFACE_UNBINDING;
+
/* release all urbs for this interface */
usb_disable_interface(interface_to_usbdev(intf), intf);
intf->altsetting[0].desc.bInterfaceNumber,
0);
usb_set_intfdata(intf, NULL);
+ intf->condition = USB_INTERFACE_UNBOUND;
return 0;
}
new_driver->driver.bus = &usb_bus_type;
new_driver->driver.probe = usb_probe_interface;
new_driver->driver.remove = usb_unbind_interface;
+ new_driver->driver.owner = new_driver->owner;
+ usb_lock_all_devices();
retval = driver_register(&new_driver->driver);
+ usb_unlock_all_devices();
if (!retval) {
pr_info("%s: registered new driver %s\n",
{
pr_info("%s: deregistering driver %s\n", usbcore_name, driver->name);
+ usb_lock_all_devices();
driver_unregister (&driver->driver);
+ usb_unlock_all_devices();
usbfs_update_special();
}
* alternate settings available for this interfaces.
*
* Don't call this function unless you are bound to one of the interfaces
- * on this device or you own the dev->serialize semaphore!
+ * on this device or you have locked the device!
*/
struct usb_interface *usb_ifnum_to_if(struct usb_device *dev, unsigned ifnum)
{
* drivers avoid such mistakes.
*
* Don't call this function unless you are bound to the intf interface
- * or you own the device's ->serialize semaphore!
+ * or you have locked the device!
*/
struct usb_host_interface *usb_altnum_to_altsetting(struct usb_interface *intf,
unsigned int altnum)
* way to bind to an interface is to return the private data from
* the driver's probe() method.
*
- * Callers must own the driver model's usb bus writelock. So driver
- * probe() entries don't need extra locking, but other call contexts
- * may need to explicitly claim that lock.
+ * Callers must own the device lock and the driver model's usb_bus_type.subsys
+ * writelock. So driver probe() entries don't need extra locking,
+ * but other call contexts may need to explicitly claim those locks.
*/
-int usb_driver_claim_interface(struct usb_driver *driver, struct usb_interface *iface, void* priv)
+int usb_driver_claim_interface(struct usb_driver *driver,
+ struct usb_interface *iface, void* priv)
{
struct device *dev = &iface->dev;
dev->driver = &driver->driver;
usb_set_intfdata(iface, priv);
+ iface->condition = USB_INTERFACE_BOUND;
/* if interface was already added, bind now; else let
* the future device_add() bind it, bypassing probe()
* also causes the driver disconnect() method to be called.
*
* This call is synchronous, and may not be used in an interrupt context.
- * Callers must own the usb_device serialize semaphore and the driver model's
- * usb bus writelock. So driver disconnect() entries don't need extra locking,
+ * Callers must own the device lock and the driver model's usb_bus_type.subsys
+ * writelock. So driver disconnect() entries don't need extra locking,
* but other call contexts may need to explicitly claim those locks.
*/
void usb_driver_release_interface(struct usb_driver *driver,
dev->driver = NULL;
usb_set_intfdata(iface, NULL);
+ iface->condition = USB_INTERFACE_UNBOUND;
}
/**
return 0;
intf = to_usb_interface(dev);
-
usb_drv = to_usb_driver(drv);
- id = usb_drv->id_table;
id = usb_match_id (intf, usb_drv->id_table);
if (id)
{
struct usb_interface *intf;
struct usb_device *usb_dev;
- char *scratch;
int i = 0;
int length = 0;
return -ENODEV;
}
- scratch = buffer;
-
#ifdef CONFIG_USB_DEVICEFS
/* If this is available, userspace programs can directly read
* all the device descriptors we don't tell them about. Or
*
* FIXME reduce hardwired intelligence here
*/
- envp [i++] = scratch;
- length += snprintf (scratch, buffer_size - length,
- "DEVICE=/proc/bus/usb/%03d/%03d",
- usb_dev->bus->busnum, usb_dev->devnum);
- if ((buffer_size - length <= 0) || (i >= num_envp))
+ if (add_hotplug_env_var(envp, num_envp, &i,
+ buffer, buffer_size, &length,
+ "DEVICE=/proc/bus/usb/%03d/%03d",
+ usb_dev->bus->busnum, usb_dev->devnum))
return -ENOMEM;
- ++length;
- scratch += length;
#endif
/* per-device configurations are common */
- envp [i++] = scratch;
- length += snprintf (scratch, buffer_size - length, "PRODUCT=%x/%x/%x",
- usb_dev->descriptor.idVendor,
- usb_dev->descriptor.idProduct,
- usb_dev->descriptor.bcdDevice);
- if ((buffer_size - length <= 0) || (i >= num_envp))
+ if (add_hotplug_env_var(envp, num_envp, &i,
+ buffer, buffer_size, &length,
+ "PRODUCT=%x/%x/%x",
+ usb_dev->descriptor.idVendor,
+ usb_dev->descriptor.idProduct,
+ usb_dev->descriptor.bcdDevice))
return -ENOMEM;
- ++length;
- scratch += length;
/* class-based driver binding models */
- envp [i++] = scratch;
- length += snprintf (scratch, buffer_size - length, "TYPE=%d/%d/%d",
- usb_dev->descriptor.bDeviceClass,
- usb_dev->descriptor.bDeviceSubClass,
- usb_dev->descriptor.bDeviceProtocol);
- if ((buffer_size - length <= 0) || (i >= num_envp))
+ if (add_hotplug_env_var(envp, num_envp, &i,
+ buffer, buffer_size, &length,
+ "TYPE=%d/%d/%d",
+ usb_dev->descriptor.bDeviceClass,
+ usb_dev->descriptor.bDeviceSubClass,
+ usb_dev->descriptor.bDeviceProtocol))
return -ENOMEM;
- ++length;
- scratch += length;
if (usb_dev->descriptor.bDeviceClass == 0) {
struct usb_host_interface *alt = intf->cur_altsetting;
* agents are called for all interfaces, and can use
* $DEVPATH/bInterfaceNumber if necessary.
*/
- envp [i++] = scratch;
- length += snprintf (scratch, buffer_size - length,
- "INTERFACE=%d/%d/%d",
- alt->desc.bInterfaceClass,
- alt->desc.bInterfaceSubClass,
- alt->desc.bInterfaceProtocol);
- if ((buffer_size - length <= 0) || (i >= num_envp))
+ if (add_hotplug_env_var(envp, num_envp, &i,
+ buffer, buffer_size, &length,
+ "INTERFACE=%d/%d/%d",
+ alt->desc.bInterfaceClass,
+ alt->desc.bInterfaceSubClass,
+ alt->desc.bInterfaceProtocol))
return -ENOMEM;
- ++length;
- scratch += length;
-
}
- envp[i++] = NULL;
+
+ envp[i] = NULL;
return 0;
}
init_MUTEX(&dev->serialize);
if (dev->bus->op->allocate)
- dev->bus->op->allocate(dev);
+ if (dev->bus->op->allocate(dev)) {
+ usb_bus_put(bus);
+ kfree(dev);
+ return NULL;
+ }
return dev;
}
put_device(&intf->dev);
}
+
+/* USB device locking
+ *
+ * Although locking USB devices should be straightforward, it is
+ * complicated by the way the driver-model core works. When a new USB
+ * driver is registered or unregistered, the core will automatically
+ * probe or disconnect all matching interfaces on all USB devices while
+ * holding the USB subsystem writelock. There's no good way for us to
+ * tell which devices will be used or to lock them beforehand; our only
+ * option is to effectively lock all the USB devices.
+ *
+ * We do that by using a private rw-semaphore, usb_all_devices_rwsem.
+ * When locking an individual device you must first acquire the rwsem's
+ * readlock. When a driver is registered or unregistered the writelock
+ * must be held. These actions are encapsulated in the subroutines
+ * below, so all a driver needs to do is call usb_lock_device() and
+ * usb_unlock_device().
+ *
+ * Complications arise when several devices are to be locked at the same
+ * time. Only hub-aware drivers that are part of usbcore ever have to
+ * do this; nobody else needs to worry about it. The problem is that
+ * usb_lock_device() must not be called to lock a second device since it
+ * would acquire the rwsem's readlock reentrantly, leading to deadlock if
+ * another thread was waiting for the writelock. The solution is simple:
+ *
+ * When locking more than one device, call usb_lock_device()
+ * to lock the first one. Lock the others by calling
+ * down(&udev->serialize) directly.
+ *
+ * When unlocking multiple devices, use up(&udev->serialize)
+ * to unlock all but the last one. Unlock the last one by
+ * calling usb_unlock_device().
+ *
+ * When locking both a device and its parent, always lock the
+ * the parent first.
+ */
+
+/**
+ * usb_lock_device - acquire the lock for a usb device structure
+ * @udev: device that's being locked
+ *
+ * Use this routine when you don't hold any other device locks;
+ * to acquire nested inner locks call down(&udev->serialize) directly.
+ * This is necessary for proper interaction with usb_lock_all_devices().
+ */
+void usb_lock_device(struct usb_device *udev)
+{
+ down_read(&usb_all_devices_rwsem);
+ down(&udev->serialize);
+}
+
+/**
+ * usb_trylock_device - attempt to acquire the lock for a usb device structure
+ * @udev: device that's being locked
+ *
+ * Don't use this routine if you already hold a device lock;
+ * use down_trylock(&udev->serialize) instead.
+ * This is necessary for proper interaction with usb_lock_all_devices().
+ *
+ * Returns 1 if successful, 0 if contention.
+ */
+int usb_trylock_device(struct usb_device *udev)
+{
+ if (!down_read_trylock(&usb_all_devices_rwsem))
+ return 0;
+ if (down_trylock(&udev->serialize)) {
+ up_read(&usb_all_devices_rwsem);
+ return 0;
+ }
+ return 1;
+}
+
+/**
+ * usb_lock_device_for_reset - cautiously acquire the lock for a
+ * usb device structure
+ * @udev: device that's being locked
+ * @iface: interface bound to the driver making the request (optional)
+ *
+ * Attempts to acquire the device lock, but fails if the device is
+ * NOTATTACHED or SUSPENDED, or if iface is specified and the interface
+ * is neither BINDING nor BOUND. Rather than sleeping to wait for the
+ * lock, the routine polls repeatedly. This is to prevent deadlock with
+ * disconnect; in some drivers (such as usb-storage) the disconnect()
+ * callback will block waiting for a device reset to complete.
+ *
+ * Returns a negative error code for failure, otherwise 1 or 0 to indicate
+ * that the device will or will not have to be unlocked. (0 can be
+ * returned when an interface is given and is BINDING, because in that
+ * case the driver already owns the device lock.)
+ */
+int usb_lock_device_for_reset(struct usb_device *udev,
+ struct usb_interface *iface)
+{
+ if (udev->state == USB_STATE_NOTATTACHED)
+ return -ENODEV;
+ if (udev->state == USB_STATE_SUSPENDED)
+ return -EHOSTUNREACH;
+ if (iface) {
+ switch (iface->condition) {
+ case USB_INTERFACE_BINDING:
+ return 0;
+ case USB_INTERFACE_BOUND:
+ break;
+ default:
+ return -EINTR;
+ }
+ }
+
+ while (!usb_trylock_device(udev)) {
+ msleep(15);
+ if (udev->state == USB_STATE_NOTATTACHED)
+ return -ENODEV;
+ if (udev->state == USB_STATE_SUSPENDED)
+ return -EHOSTUNREACH;
+ if (iface && iface->condition != USB_INTERFACE_BOUND)
+ return -EINTR;
+ }
+ return 1;
+}
+
+/**
+ * usb_unlock_device - release the lock for a usb device structure
+ * @udev: device that's being unlocked
+ *
+ * Use this routine when releasing the only device lock you hold;
+ * to release inner nested locks call up(&udev->serialize) directly.
+ * This is necessary for proper interaction with usb_lock_all_devices().
+ */
+void usb_unlock_device(struct usb_device *udev)
+{
+ up(&udev->serialize);
+ up_read(&usb_all_devices_rwsem);
+}
+
+/**
+ * usb_lock_all_devices - acquire the lock for all usb device structures
+ *
+ * This is necessary when registering a new driver or probing a bus,
+ * since the driver-model core may try to use any usb_device.
+ */
+void usb_lock_all_devices(void)
+{
+ down_write(&usb_all_devices_rwsem);
+}
+
+/**
+ * usb_unlock_all_devices - release the lock for all usb device structures
+ */
+void usb_unlock_all_devices(void)
+{
+ up_write(&usb_all_devices_rwsem);
+}
+
+
static struct usb_device *match_device(struct usb_device *dev,
u16 vendor_id, u16 product_id)
{
/* look through all of the children of this device */
for (child = 0; child < dev->maxchild; ++child) {
if (dev->children[child]) {
+ down(&dev->children[child]->serialize);
ret_dev = match_device(dev->children[child],
vendor_id, product_id);
+ up(&dev->children[child]->serialize);
if (ret_dev)
goto exit;
}
bus = container_of(buslist, struct usb_bus, bus_list);
if (!bus->root_hub)
continue;
+ usb_lock_device(bus->root_hub);
dev = match_device(bus->root_hub, vendor_id, product_id);
+ usb_unlock_device(bus->root_hub);
if (dev)
goto exit;
}
intf = to_usb_interface(dev);
driver = to_usb_driver(dev->driver);
+ /* there's only one USB suspend state */
+ if (intf->dev.power.power_state)
+ return 0;
+
if (driver->suspend)
return driver->suspend(intf, state);
return 0;
EXPORT_SYMBOL(usb_get_dev);
EXPORT_SYMBOL(usb_hub_tt_clear_buffer);
+EXPORT_SYMBOL(usb_lock_device);
+EXPORT_SYMBOL(usb_trylock_device);
+EXPORT_SYMBOL(usb_lock_device_for_reset);
+EXPORT_SYMBOL(usb_unlock_device);
+
EXPORT_SYMBOL(usb_driver_claim_interface);
EXPORT_SYMBOL(usb_driver_release_interface);
EXPORT_SYMBOL(usb_match_id);
git://git.onelab.eu / linux-2.6.git / blobdiff