diff options
| -rw-r--r-- | drivers/usb/core/driver.c | 23 | ||||
| -rw-r--r-- | drivers/usb/core/hub.c | 43 | ||||
| -rw-r--r-- | drivers/usb/core/message.c | 41 | ||||
| -rw-r--r-- | include/linux/usb.h | 8 |
4 files changed, 113 insertions, 2 deletions
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index 23b3c7e79d4..7e26fb3c275 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -184,6 +184,20 @@ static int usb_unbind_device(struct device *dev) return 0; } +/* + * Cancel any pending scheduled resets + * + * [see usb_queue_reset_device()] + * + * Called after unconfiguring / when releasing interfaces. See + * comments in __usb_queue_reset_device() regarding + * udev->reset_running. + */ +static void usb_cancel_queued_reset(struct usb_interface *iface) +{ + if (iface->reset_running == 0) + cancel_work_sync(&iface->reset_ws); +} /* called from driver core with dev locked */ static int usb_probe_interface(struct device *dev) @@ -242,6 +256,7 @@ static int usb_probe_interface(struct device *dev) mark_quiesced(intf); intf->needs_remote_wakeup = 0; intf->condition = USB_INTERFACE_UNBOUND; + usb_cancel_queued_reset(intf); } else intf->condition = USB_INTERFACE_BOUND; @@ -272,6 +287,7 @@ static int usb_unbind_interface(struct device *dev) usb_disable_interface(udev, intf); driver->disconnect(intf); + usb_cancel_queued_reset(intf); /* Reset other interface state. * We cannot do a Set-Interface if the device is suspended or @@ -380,8 +396,10 @@ void usb_driver_release_interface(struct usb_driver *driver, if (device_is_registered(dev)) { iface->condition = USB_INTERFACE_UNBINDING; device_release_driver(dev); + } else { + iface->condition = USB_INTERFACE_UNBOUND; + usb_cancel_queued_reset(iface); } - dev->driver = NULL; usb_set_intfdata(iface, NULL); @@ -942,7 +960,8 @@ static int usb_suspend_interface(struct usb_device *udev, if (udev->state == USB_STATE_NOTATTACHED || !is_active(intf)) goto done; - if (intf->condition == USB_INTERFACE_UNBOUND) /* This can't happen */ + /* This can happen; see usb_driver_release_interface() */ + if (intf->condition == USB_INTERFACE_UNBOUND) goto done; driver = to_usb_driver(intf->dev.driver); 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); diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index cc47d36798b..aadf29f09c4 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -1441,6 +1441,46 @@ static struct usb_interface_assoc_descriptor *find_iad(struct usb_device *dev, return retval; } + +/* + * Internal function to queue a device reset + * + * This is initialized into the workstruct in 'struct + * usb_device->reset_ws' that is launched by + * message.c:usb_set_configuration() when initializing each 'struct + * usb_interface'. + * + * It is safe to get the USB device without reference counts because + * the life cycle of @iface is bound to the life cycle of @udev. Then, + * this function will be ran only if @iface is alive (and before + * freeing it any scheduled instances of it will have been cancelled). + * + * We need to set a flag (usb_dev->reset_running) because when we call + * the reset, the interfaces might be unbound. The current interface + * cannot try to remove the queued work as it would cause a deadlock + * (you cannot remove your work from within your executing + * workqueue). This flag lets it know, so that + * usb_cancel_queued_reset() doesn't try to do it. + * + * See usb_queue_reset_device() for more details + */ +void __usb_queue_reset_device(struct work_struct *ws) +{ + int rc; + struct usb_interface *iface = + container_of(ws, struct usb_interface, reset_ws); + struct usb_device *udev = interface_to_usbdev(iface); + + rc = usb_lock_device_for_reset(udev, iface); + if (rc >= 0) { + iface->reset_running = 1; + usb_reset_device(udev); + iface->reset_running = 0; + usb_unlock_device(udev); + } +} + + /* * usb_set_configuration - Makes a particular device setting be current * @dev: the device whose configuration is being updated @@ -1611,6 +1651,7 @@ free_interfaces: intf->dev.type = &usb_if_device_type; intf->dev.groups = usb_interface_groups; intf->dev.dma_mask = dev->dev.dma_mask; + INIT_WORK(&intf->reset_ws, __usb_queue_reset_device); device_initialize(&intf->dev); mark_quiesced(intf); dev_set_name(&intf->dev, "%d-%s:%d.%d", diff --git a/include/linux/usb.h b/include/linux/usb.h index 859a88e6ce9..c8e55aa979d 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -120,6 +120,11 @@ enum usb_interface_condition { * to the sysfs representation for that device. * @pm_usage_cnt: PM usage counter for this interface; autosuspend is not * allowed unless the counter is 0. + * @reset_ws: Used for scheduling resets from atomic context. + * @reset_running: set to 1 if the interface is currently running a + * queued reset so that usb_cancel_queued_reset() doesn't try to + * remove from the workqueue when running inside the worker + * thread. See __usb_queue_reset_device(). * * USB device drivers attach to interfaces on a physical device. Each * interface encapsulates a single high level function, such as feeding @@ -168,10 +173,12 @@ struct usb_interface { unsigned needs_remote_wakeup:1; /* driver requires remote wakeup */ unsigned needs_altsetting0:1; /* switch to altsetting 0 is pending */ unsigned needs_binding:1; /* needs delayed unbind/rebind */ + unsigned reset_running:1; struct device dev; /* interface specific device info */ struct device *usb_dev; int pm_usage_cnt; /* usage counter for autosuspend */ + struct work_struct reset_ws; /* for resets in atomic context */ }; #define to_usb_interface(d) container_of(d, struct usb_interface, dev) #define interface_to_usbdev(intf) \ @@ -507,6 +514,7 @@ extern int usb_lock_device_for_reset(struct usb_device *udev, /* USB port reset for device reinitialization */ extern int usb_reset_device(struct usb_device *dev); +extern void usb_queue_reset_device(struct usb_interface *dev); extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id); |