driver core: Add missing dev->bus->need_parent_lock checks

__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.wysocki@intel.com>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 88713f1..8ac10af 100644 (file)
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -933,11 +933,11 @@ static void __device_release_driver(struct device *dev, struct device *parent)
        if (drv) {
                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);