From 7b1485bab9c49b0d3811d72beb0de60c7b8b337d Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Mon, 15 Dec 2014 12:56:59 +1100
Subject: [PATCH] md/raid5: use ->lock to protect accessing raid5 sysfs
 attributes.

It is important that mddev->private isn't freed while
a sysfs attribute function is accessing it.

So use mddev->lock to protect the setting of ->private to NULL, and
take that lock when checking ->private for NULL and de-referencing it
in the sysfs access functions.

This only applies to the read ('show') side of access.  Write
access will be handled separately.

Signed-off-by: NeilBrown <neilb@suse.de>
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