Hi,

In the patch attached to this e-mail I included Matthew Fleming's patch 
aswell.


1) I renamed taskqueue_cancel() into taskqueue_stop(), hence that resembles 
the words of the callout and USB API's terminology for doing the same.

2) I turns out I need to have code in subr_taskqueue.c to be able to make the 
operations atomic.

3) I did not update the manpage in this patch. Will do that before a commit.

4) My patch implements separate state keeping in "struct task_pair", which 
avoids having to change any KPI's for now, like suggested by John Baldwin I 
think.

5) In my implementation I hard-coded the priority argument to zero, so that 
enqueuing is fast.

Comments are welcome!

--HPS