centos man page for usb_ep_dequeue

USB_EP_DEQUEUE(9)					      Kernel Mode Gadget API						 USB_EP_DEQUEUE(9)

NAME
       usb_ep_dequeue - dequeues (cancels, unlinks) an I/O request from an endpoint

SYNOPSIS
       int usb_ep_dequeue(struct usb_ep * ep, struct usb_request * req);

ARGUMENTS
       ep
	   the endpoint associated with the request

       req
	   the request being canceled

DESCRIPTION
       if the request is still active on the endpoint, it is dequeued and its completion routine is called (with status -ECONNRESET); else a
       negative error code is returned.

       note that some hardware can't clear out write fifos (to unlink the request at the head of the queue) except as part of disconnecting from
       usb. such restrictions prevent drivers from supporting configuration changes, even to configuration zero (a "chapter 9" requirement).

AUTHOR
       David Brownell <dbrownell@users.sourceforge.net>
	   Author.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							 USB_EP_DEQUEUE(9)