Author: delphij
Date: Wed May 8 17:45:22 2013
New Revision: 250374
URL: http://svnweb.freebsd.org/changeset/base/250374
Log:
According to the documentation, on Linux, cancel_delayed_work() does not
do drain (flush_workqueue() in Linux terms) but instead returns true if
the work was removed before it is run, or false otherwise.
Simulate this by removing the taskqueue_drain() and return the value
derived from taskqueue_cancel()'s return value.
This would solve a witness warning caused by calling taskqueue_drain()
with a non-sleepable lock held, like:
taskqueue_drain with the following non-sleepable locks held:
exclusive rw lle (lle) r = 0 (0xfffffe001450b410) locked @
/usr/src/sys/netinet/in.c:1484
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xffffff848d4f7690
kdb_backtrace() at kdb_backtrace+0x39/frame 0xffffff848d4f7740
witness_warn() at witness_warn+0x4a8/frame 0xffffff848d4f7800
taskqueue_drain() at taskqueue_drain+0x3a/frame 0xffffff848d4f7840
set_timeout() at set_timeout+0x4a/frame 0xffffff848d4f7860
netevent_callback() at netevent_callback+0x16/frame 0xffffff848d4f7870
arpintr() at arpintr+0x9b5/frame 0xffffff848d4f7930
This do not affect kernel without OFED compiled in.
Reported by: Garrett Cooper <yaneurabeya gmail com>
(who also tested an earlier version of this patch,
but bugs are mine)
MFC after: 2 weeks
Modified:
head/sys/ofed/include/linux/workqueue.h
Modified: head/sys/ofed/include/linux/workqueue.h
==============================================================================
--- head/sys/ofed/include/linux/workqueue.h Wed May 8 16:43:52 2013
(r250373)
+++ head/sys/ofed/include/linux/workqueue.h Wed May 8 17:45:22 2013
(r250374)
@@ -184,9 +184,9 @@ cancel_delayed_work(struct delayed_work
{
callout_stop(&work->timer);
- if (work->work.taskqueue &&
- taskqueue_cancel(work->work.taskqueue, &work->work.work_task, NULL))
- taskqueue_drain(work->work.taskqueue, &work->work.work_task);
+ if (work->work.taskqueue)
+ return (taskqueue_cancel(work->work.taskqueue,
+ &work->work.work_task, NULL) == 0);
return 0;
}
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