USB: add extension of anchor API, usb_unlink_anchored_urbs
This adds the ability to trigger asynchronous unlinks of anchored URBs. This
is needed for error handling in the comntext of completion handlers, which
cannot sleep.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 9d7e632..1d3ed13 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -590,6 +590,30 @@
EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
/**
+ * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse
+ * @anchor: anchor the requests are bound to
+ *
+ * this allows all outstanding URBs to be unlinked starting
+ * from the back of the queue. This function is asynchronous.
+ * The unlinking is just tiggered. It may happen after this
+ * function has returned.
+ */
+void usb_unlink_anchored_urbs(struct usb_anchor *anchor)
+{
+ struct urb *victim;
+
+ spin_lock_irq(&anchor->lock);
+ while (!list_empty(&anchor->urb_list)) {
+ victim = list_entry(anchor->urb_list.prev, struct urb,
+ anchor_list);
+ /* this will unanchor the URB */
+ usb_unlink_urb(victim);
+ }
+ spin_unlock_irq(&anchor->lock);
+}
+EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
+
+/**
* usb_wait_anchor_empty_timeout - wait for an anchor to be unused
* @anchor: the anchor you want to become unused
* @timeout: how long you are willing to wait in milliseconds