centos man page for usb_block_urb

USB_BLOCK_URB(9)						   USB Core APIs						  USB_BLOCK_URB(9)

NAME
       usb_block_urb - reliably prevent further use of an URB

SYNOPSIS
       void usb_block_urb(struct urb * urb);

ARGUMENTS
       urb
	   pointer to URB to be blocked, may be NULL

DESCRIPTION
       After the routine has run, attempts to resubmit the URB will fail with error -EPERM. Thus even if the URB's completion handler always tries
       to resubmit, it will not succeed and the URB will become idle.

       The URB must not be deallocated while this routine is running. In particular, when a driver calls this routine, it must insure that the
       completion handler cannot deallocate the URB.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							  USB_BLOCK_URB(9)