[PATCH] driver core: Add missing dev->bus->need_parent_lock checks

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wyso...@intel.com>

__device_release_driver() has to check dev->bus->need_parent_lock
before dropping the parent lock and acquiring it again as it may
attempt to drop a lock that hasn't been acquired or lock a device
that shouldn't be locked and create a lock imbalance.

Fixes: 8c97a46af04b (driver core: hold dev's parent lock when needed)
Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
---

This should go into -stable for everything over 4.18 methinks.

---
 drivers/base/dd.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/base/dd.c
===================================================================
--- linux-pm.orig/drivers/base/dd.c
+++ linux-pm/drivers/base/dd.c
@@ -933,11 +933,11 @@ static void __device_release_driver(stru
 
                while (device_links_busy(dev)) {
                        device_unlock(dev);
-                       if (parent)
+                       if (parent && dev->bus->need_parent_lock)
                                device_unlock(parent);
 
                        device_links_unbind_consumers(dev);
-                       if (parent)
+                       if (parent && dev->bus->need_parent_lock)
                                device_lock(parent);
 
                        device_lock(dev);