From: Heinz Mauelshagen <heinzm@redhat.com>
Date: Tue, 3 May 2016 17:43:57 +0000 (+0200)
Subject: md: md.c: fix oops in mddev_suspend for raid0
X-Git-Tag: v4.6.1~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5269fcd77a7ec9a5ba26b47423d79eafba0210ff;p=thirdparty%2Fkernel%2Fstable.git

md: md.c: fix oops in mddev_suspend for raid0

commit 092398dce8c2406bfb0c9eebc3e764ff2ddb62a8 upstream.

Introduced by upstream commit 70d9798b95562abac005d4ba71d28820f9a201eb

The raid0 personality does not create mddev->thread as oposed to
other personalities leading to its unconditional access in
mddev_suspend() causing an oops.

Patch checks for mddev->thread in order to keep the
intention of aforementioned commit.

Fixes: 70d9798b9556 ("MD: warn for potential deadlock")
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 14d3b37944df0..85b16aadd459b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -307,7 +307,7 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
  */
 void mddev_suspend(struct mddev *mddev)
 {
-	WARN_ON_ONCE(current == mddev->thread->tsk);
+	WARN_ON_ONCE(mddev->thread && current == mddev->thread->tsk);
 	if (mddev->suspended++)
 		return;
 	synchronize_rcu();