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MFC r306441 and r306634:

Description

MFC r306441 and r306634:
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

Details

Provenance
hselaskyAuthored on
Reviewer
kib
Differential Revision
D8012: Fix race in taskqueue_drain_timeout()
Parents
rS306946: MFC r306441 and r306634:
Branches
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Tags
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