K 10
svn:author
V 8
hselasky
K 8
svn:date
V 27
2016-09-29T10:38:20.819096Z
K 7
svn:log
V 841
While draining a timeout task prevent the taskqueue_enqueue_timeout()
function from restarting the timer.

Commonly taskqueue_enqueue_timeout() is called from within the task
function itself without any checks for teardown. Then it can happen
the timer stays active after the return of taskqueue_drain_timeout(),
because the timeout and task is drained separately.

This patch factors out the teardown flag into the timeout task itself,
allowing existing code to stay as-is instead of applying a teardown
flag to each and every of the timeout task consumers.

Add assert to taskqueue_drain_timeout() which prevents parallel
execution on the same timeout task.

Update manual page documenting the return value of
taskqueue_enqueue_timeout().

Differential Revision:	https://reviews.freebsd.org/D8012
Reviewed by:	kib, trasz
MFC after:	1 week

END