releases/4.6.1/md-md.c-fix-oops-in-mddev_suspend-for-raid0.patch

   1 From 092398dce8c2406bfb0c9eebc3e764ff2ddb62a8 Mon Sep 17 00:00:00 2001
   2 From: Heinz Mauelshagen <heinzm@redhat.com>
   3 Date: Tue, 3 May 2016 19:43:57 +0200
   4 Subject: md: md.c: fix oops in mddev_suspend for raid0
   5
   6 From: Heinz Mauelshagen <heinzm@redhat.com>
   7
   8 commit 092398dce8c2406bfb0c9eebc3e764ff2ddb62a8 upstream.
   9
  10 Introduced by upstream commit 70d9798b95562abac005d4ba71d28820f9a201eb
  11
  12 The raid0 personality does not create mddev->thread as oposed to
  13 other personalities leading to its unconditional access in
  14 mddev_suspend() causing an oops.
  15
  16 Patch checks for mddev->thread in order to keep the
  17 intention of aforementioned commit.
  18
  19 Fixes: 70d9798b9556 ("MD: warn for potential deadlock")
  20 Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
  21 Signed-off-by: Shaohua Li <shli@fb.com>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  23
  24 ---
  25  drivers/md/md.c |    2 +-
  26  1 file changed, 1 insertion(+), 1 deletion(-)
  27
  28 --- a/drivers/md/md.c
  29 +++ b/drivers/md/md.c
  30 @@ -307,7 +307,7 @@ static blk_qc_t md_make_request(struct r
  31   */
  32  void mddev_suspend(struct mddev *mddev)
  33  {
  34 -       WARN_ON_ONCE(current == mddev->thread->tsk);
  35 +       WARN_ON_ONCE(mddev->thread && current == mddev->thread->tsk);
  36         if (mddev->suspended++)
  37                 return;
  38         synchronize_rcu();