On 22.09.2019 21:56, Sasha Levin wrote:
> From: Leonard Crestez <leonard.crestez@xxxxxxx>
>
> [ Upstream commit 0ef7c7cce43f6ecc2b96d447e69b2900a9655f7c ]
This will introduce an "unused variable warning" unless you also
cherry-pick commit 0465814831a9 ("PM / devfreq: passive: fix compiler
warning").
> 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: 996133119f57 ("PM / devfreq: Add new passive governor")
> Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
> Acked-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> drivers/devfreq/governor_passive.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 3bc29acbd54e8..22fd41b4c1098 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -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;
>
