diff options
Diffstat (limited to 'drivers/usb/core/hub.c')
-rw-r--r-- | drivers/usb/core/hub.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 95fb3104ba4..e65881899c8 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -3518,3 +3518,46 @@ int usb_reset_device(struct usb_device *udev) return ret; } EXPORT_SYMBOL_GPL(usb_reset_device); + + +/** + * usb_queue_reset_device - Reset a USB device from an atomic context + * @iface: USB interface belonging to the device to reset + * + * This function can be used to reset a USB device from an atomic + * context, where usb_reset_device() won't work (as it blocks). + * + * Doing a reset via this method is functionally equivalent to calling + * usb_reset_device(), except for the fact that it is delayed to a + * workqueue. This means that any drivers bound to other interfaces + * might be unbound, as well as users from usbfs in user space. + * + * Corner cases: + * + * - Scheduling two resets at the same time from two different drivers + * attached to two different interfaces of the same device is + * possible; depending on how the driver attached to each interface + * handles ->pre_reset(), the second reset might happen or not. + * + * - If a driver is unbound and it had a pending reset, the reset will + * be cancelled. + * + * - This function can be called during .probe() or .disconnect() + * times. On return from .disconnect(), any pending resets will be + * cancelled. + * + * There is no no need to lock/unlock the @reset_ws as schedule_work() + * does its own. + * + * NOTE: We don't do any reference count tracking because it is not + * needed. The lifecycle of the work_struct is tied to the + * usb_interface. Before destroying the interface we cancel the + * work_struct, so the fact that work_struct is queued and or + * running means the interface (and thus, the device) exist and + * are referenced. + */ +void usb_queue_reset_device(struct usb_interface *iface) +{ + schedule_work(&iface->reset_ws); +} +EXPORT_SYMBOL_GPL(usb_queue_reset_device); |