From a67a46af4ad6342378e332b7420c1d1a2818c53f Mon Sep 17 00:00:00 2001 From: Daniel Lezcano Date: Tue, 19 Oct 2021 18:35:06 +0200 Subject: thermal/core: Deprecate changing cooling device state from userspace The cooling devices have their cooling device set_cur_state read-writable all the time in the sysfs directory, thus allowing the userspace to act on it. The thermal framework is wrongly used by userspace as a power capping framework by acting on the cooling device opaque state. This one then competes with the in-kernel governor decision. We have seen in out-of-tree kernels, a big number of devices which are abusely declaring themselves as cooling device just to act on their power. The role of the thermal framework is to protect the junction temperature of the silicon. Letting the userspace to play with a cooling device is invalid and potentially dangerous. The powercap framework is the right framework to do power capping and moreover it deals with the aggregation via the dev pm qos. As the userspace governor is marked deprecated and about to be removed, there is no point to keep this file writable also in the future. Emit a warning and deprecate the interface. Signed-off-by: Daniel Lezcano Acked-by: Rafael J. Wysocki Reviewed-by: Lukasz Luba Link: https://lore.kernel.org/r/20211019163506.2831454-2-daniel.lezcano@linaro.org --- drivers/thermal/thermal_sysfs.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/thermal') diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c index 1c4aac8464a7..f154bada2906 100644 --- a/drivers/thermal/thermal_sysfs.c +++ b/drivers/thermal/thermal_sysfs.c @@ -610,6 +610,9 @@ cur_state_store(struct device *dev, struct device_attribute *attr, unsigned long state; int result; + dev_warn_once(&cdev->device, + "Setting cooling device state is deprecated\n"); + if (sscanf(buf, "%ld\n", &state) != 1) return -EINVAL; -- cgit