On 22.09.2019 21:56, Sasha Levin wrote:
From: Leonard Crestez leonard.crestez@nxp.com
[ 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@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
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);
devm_devfreq_unregister_notifier(dev, parent, nb,DEVFREQ_TRANSITION_NOTIFIER);
WARN_ON(devfreq_unregister_notifier(parent, nb,DEVFREQ_TRANSITION_NOTIFIER));