Due to possible deadlock issues we need to use a schedule work to
kobject_del an 'rdev' object from a different thread.

A recent change means that kobject_add no longer gets a refernce, and
kobject_del doesn't put a reference.  Consequently, we need to
explicitly hold a reference to ensure that the last reference isn't
dropped before the scheduled work get a chance to call kobject_del.

Also, rename delayed_delete to md_delayed_delete to that it is more
obvious in a stack trace which code is to blame.

Cc: Al Viro <[EMAIL PROTECTED]>
Signed-off-by: Neil Brown <[EMAIL PROTECTED]>

### Diffstat output
 ./drivers/md/md.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c       2008-01-14 12:23:53.000000000 +1100
+++ ./drivers/md/md.c   2008-01-14 12:24:17.000000000 +1100
@@ -1421,10 +1421,11 @@ static int bind_rdev_to_array(mdk_rdev_t
        return err;
 }
 
-static void delayed_delete(struct work_struct *ws)
+static void md_delayed_delete(struct work_struct *ws)
 {
        mdk_rdev_t *rdev = container_of(ws, mdk_rdev_t, del_work);
        kobject_del(&rdev->kobj);
+       kobject_put(&rdev->kobj);
 }
 
 static void unbind_rdev_from_array(mdk_rdev_t * rdev)
@@ -1443,7 +1444,8 @@ static void unbind_rdev_from_array(mdk_r
        /* We need to delay this, otherwise we can deadlock when
         * writing to 'remove' to "dev/state"
         */
-       INIT_WORK(&rdev->del_work, delayed_delete);
+       INIT_WORK(&rdev->del_work, md_delayed_delete);
+       kobject_get(&rdev->kobj);
        schedule_work(&rdev->del_work);
 }
 
@@ -3688,7 +3690,7 @@ static int do_md_stop(mddev_t * mddev, i
                                sysfs_remove_link(&mddev->kobj, nm);
                        }
 
-               /* make sure all delayed_delete calls have finished */
+               /* make sure all md_delayed_delete calls have finished */
                flush_scheduled_work();
 
                export_array(mddev);
-
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