Commit d1e9aa3c authored Aug 08, 2019 by Leonard Crestez Committed by Greg Kroah-Hartman Oct 05, 2019

PM / devfreq: passive: Use non-devm notifiers



[ Upstream commit 0ef7c7cce43f6ecc2b96d447e69b2900a9655f7c ]

The devfreq passive governor registers and unregisters devfreq
transition notifiers on DEVFREQ_GOV_START/GOV_STOP using devm wrappers.

If devfreq itself is registered with devm then a warning is triggered on
rmmod from devm_devfreq_unregister_notifier. Call stack looks like this:

	devm_devfreq_unregister_notifier+0x30/0x40
	devfreq_passive_event_handler+0x4c/0x88
	devfreq_remove_device.part.8+0x6c/0x9c
	devm_devfreq_dev_release+0x18/0x20
	release_nodes+0x1b0/0x220
	devres_release_all+0x78/0x84
	device_release_driver_internal+0x100/0x1c0
	driver_detach+0x4c/0x90
	bus_remove_driver+0x7c/0xd0
	driver_unregister+0x2c/0x58
	platform_driver_unregister+0x10/0x18
	imx_devfreq_platdrv_exit+0x14/0xd40 [imx_devfreq]

This happens because devres_release_all will first remove all the nodes
into a separate todo list so the nested devres_release from
devm_devfreq_unregister_notifier won't find anything.

Fix the warning by calling the non-devm APIS for frequency notification.
Using devm wrappers is not actually useful for a governor anyway: it
relies on the devfreq core to correctly match the GOV_START/GOV_STOP
notifications.

Fixes: 99613311 ("PM / devfreq: Add new passive governor")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 9db28659

drivers/devfreq/governor_passive.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -168,12 +168,12 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq,
		p_data->this = devfreq;

		nb->notifier_call = devfreq_passive_notifier_call;
		ret = devm_devfreq_register_notifier(dev, parent, nb,
		ret = devfreq_register_notifier(parent, nb,
		DEVFREQ_TRANSITION_NOTIFIER);
		break;
		case DEVFREQ_GOV_STOP:
		devm_devfreq_unregister_notifier(dev, parent, nb,
		DEVFREQ_TRANSITION_NOTIFIER);
		WARN_ON(devfreq_unregister_notifier(parent, nb,
		DEVFREQ_TRANSITION_NOTIFIER));
		break;
		default:
		break;