From: NeilBrown <neilb@suse.de>
Date: Tue, 11 Dec 2012 02:35:54 +0000 (+1100)
Subject: md: close race between removing and adding a device.
X-Git-Tag: v3.8-rc1~73^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a7a3f08dc24690ae00c75cfe4b4701a970dd0155;p=pandora-kernel.git

md: close race between removing and adding a device.

When we remove a device from an md array, the final removal of
the "dev-XX" sys entry is run asynchronously.
If we then re-add that device immediately before the worker thread
gets to run, we can end up trying to add the "dev-XX" sysfs entry back
before it has been removed.

So in both places where we add a device, call
  flush_workqueue(md_misc_wq);
before taking the md lock (as holding the md lock can prevent removal
to complete).

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

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