tree 8cc85208970ba0c9adf533903243e28c506f23ae
parent 972fa1c5316d18c8297123e08e9b6930ca34f888
author Tejun Heo <tj@kernel.org> 1282652567 +0200
committer Tejun Heo <tj@kernel.org> 1282665692 +0200

workqueue: improve destroy_workqueue() debuggability

Now that the worklist is global, having works pending after wq
destruction can easily lead to oops and destroy_workqueue() have
several BUG_ON()s to catch these cases.  Unfortunately, BUG_ON()
doesn't tell much about how the work became pending after the final
flush_workqueue().

This patch adds WQ_DYING which is set before the final flush begins.
If a work is requested to be queued on a dying workqueue,
WARN_ON_ONCE() is triggered and the request is ignored.  This clearly
indicates which caller is trying to queue a work on a dying workqueue
and keeps the system working in most cases.

Locking rule comment is updated such that the 'I' rule includes
modifying the field from destruction path.

Signed-off-by: Tejun Heo <tj@kernel.org>