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@google.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20230720-kunit-devm-inconsistencies-test-v3-3-6aa7e074f373@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 3dff5037943e02ddc8fa66a6f9c1468e6f93b812..6ceaf50f5a671e008a4b954002b6cc262624f10d 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3817,6 +3817,17 @@ 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);
+
        bus_notify(dev, BUS_NOTIFY_REMOVED_DEVICE);
        kobject_uevent(&dev->kobj, KOBJ_REMOVE);
        glue_dir = get_glue_dir(dev);