[patch 097/108] dm mpath: flush keventd queue in destructor

Greg KH
2009-07-01T01:15:51Z

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2.6.30-stable review patch. If anyone has any objections, please let us know.

------------------

From: Mikulas Patocka <mpatocka@redhat.com>

commit 53b351f972a882ea8b6cdb19602535f1057c884a upstream.

The commit fe9cf30eb8186ef267d1868dc9f12f2d0f40835a moves dm table event
submission from kmultipath queue to kernel kevent queue to avoid a
deadlock.

There is a possibility of race condition because kevent queue is not flushed
in the multipath destructor. The scenario is:
- some event happens and is queued to keventd
- keventd thread is delayed due to scheuling latency or some other work
- multipath device is destroyed
- keventd now attempts to process work_struct that is residing in already
released memory.

The patch flushes the keventd queue in multipath constructor.
I've already fixed similar bug in dm-raid1.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/dm-mpath.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -847,6 +847,7 @@ static void multipath_dtr(struct dm_targ

flush_workqueue(kmpath_handlerd);
flush_workqueue(kmultipathd);
+ flush_scheduled_work();
free_multipath(m);
}