From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date: Thu, 13 Dec 2018 18:27:47 +0000 (+0100)
Subject: driver core: Add missing dev->bus->need_parent_lock checks
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=e121a833745b4708b660e3fe6776129c2956b041;p=openwrt%2Fstaging%2Fblogic.git

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 88713f182086..8ac10af17c00 100644
--- 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);