Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Tue, 19 Oct 2021 17:43:28 +0200 | Subject | Re: [PATCH v2 2/2] thermal/core: Make deprecated cooling device state change from userspace |
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On Tue, Oct 19, 2021 at 5:40 PM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Tue, Oct 19, 2021 at 5:02 PM Daniel Lezcano > <daniel.lezcano@linaro.org> wrote: > > > > 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 <daniel.lezcano@linaro.org> > > --- > > drivers/thermal/thermal_sysfs.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c > > index 1c4aac8464a7..730f1361dbef 100644 > > --- a/drivers/thermal/thermal_sysfs.c > > +++ b/drivers/thermal/thermal_sysfs.c > > @@ -610,6 +610,8 @@ cur_state_store(struct device *dev, struct device_attribute *attr, > > unsigned long state; > > int result; > > > > + pr_warn_once("Setting cooling device state is deprecated\n"); > > Maybe dev_warn_once() even? I guess it won\t hurt to print it once > per the affected device? > > > + > > if (sscanf(buf, "%ld\n", &state) != 1) > > return -EINVAL; > > > > --
Also I think that changing the subject to something like "Deprecate changing cooling device state from userspace" would help.
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