[PATCH 3.19.y-ckt 005/102] md: flush ->event_work before stopping array.

[Kamal Mostafa]

3.19.8-ckt7 -stable review patch.  If anyone has any objections, please let me know.

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

From: NeilBrown <neilb@xxxxxxxx>

commit ee5d004fd0591536a061451eba2b187092e9127c upstream.

The 'event_work' worker used by dm-raid may still be running
when the array is stopped.  This can result in an oops.

So flush the workqueue on which it is run after detaching
and before destroying the device.

Reported-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Fixes: 9d09e663d550 ("dm: raid456 basic support")
[kamal: backport to 3.19-stable: context]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 drivers/md/md.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index a31e15b..d7f0a56 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5076,6 +5076,8 @@ EXPORT_SYMBOL_GPL(md_stop_writes);
 
 static void __md_stop(struct mddev *mddev)
 {
+	/* Ensure ->event_work is done */
+	flush_workqueue(md_misc_wq);
 	mddev->ready = 0;
 	mddev->pers->stop(mddev);
 	if (mddev->pers->sync_request && mddev->to_remove == NULL)
-- 
1.9.1

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