/*
* XXX these functions are ghastly hacks for when the submission
* XXX routines discover a request that was not CBIMM is already
* XXX done, and must be yanked from the retq (where _done) put it
* XXX as cryptoret won't get the chance. The queue is walked backwards
* XXX as the request is generally the last one queued.
*
* call with the lock held, or else.
*/