This is a note to let you know that I've just added the patch titled
drivers: base: Free devm resources when unregistering a device
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drivers-base-free-devm-resources-when-unregistering-.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a23e370b7109a6d47d01e78213bf4579d1ac45bf
Author: David Gow <davidgow@xxxxxxxxxx>
Date: Thu Jul 20 14:45:09 2023 +0200
drivers: base: Free devm resources when unregistering a device
[ Upstream commit 699fb50d99039a50e7494de644f96c889279aca3 ]
In the current code, devres_release_all() only gets called if the device
has a bus and has been probed.
This leads to issues when using bus-less or driver-less devices where
the device might never get freed if a managed resource holds a reference
to the device. This is happening in the DRM framework for example.
We should thus call devres_release_all() in the device_del() function to
make sure that the device-managed actions are properly executed when the
device is unregistered, even if it has neither a bus nor a driver.
This is effectively the same change than commit 2f8d16a996da ("devres:
release resources on device_del()") that got reverted by commit
a525a3ddeaca ("driver core: free devres in device_release") over
memory leaks concerns.
This patch effectively combines the two commits mentioned above to
release the resources both on device_del() and device_release() and get
the best of both worlds.
Fixes: a525a3ddeaca ("driver core: free devres in device_release")
Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230720-kunit-devm-inconsistencies-test-v3-3-6aa7e074f373@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/base/core.c b/drivers/base/core.c
index e30223c2672fc..af90bfb0cc3d8 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3855,6 +3855,17 @@ void device_del(struct device *dev)
device_platform_notify_remove(dev);
device_links_purge(dev);
+ /*
+ * If a device does not have a driver attached, we need to clean
+ * up any managed resources. We do this in device_release(), but
+ * it's never called (and we leak the device) if a managed
+ * resource holds a reference to the device. So release all
+ * managed resources here, like we do in driver_detach(). We
+ * still need to do so again in device_release() in case someone
+ * adds a new resource after this point, though.
+ */
+ devres_release_all(dev);
+
if (dev->bus)
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_REMOVED_DEVICE, dev);
