Re: [RFC 0/4] clk/driver: platform: Fix kfree() of const memory on setting driver_override

On Mon, 18 Feb 2019 at 11:40, Geert Uytterhoeven [off-list ref] wrote:

Hi Krzysztof,

On Mon, Feb 18, 2019 at 11:27 AM Krzysztof Kozlowski [off-list ref] wrote:

quoted

The problem
===========
Several device types (platform, amba, spi etc.) provide a driver_override
field.  On sysfs store or during device removal, they kfree() the
existing value.

However the users are unaware of this and set the driver_override like:

        pdev->driver_override = "exynos5-subcmu";

which obviously leads to error.

IMHO driver_override is not meant to be set by a driver, only from userspace,
for binding the device to vfio (is there another use case?).

quoted

  clk: samsung: exynos5: Fix kfree() of const memory on setting
    driver_override
  slimbus: ngd: Fix kfree() of const memory on setting driver_override

I see all users set override immediately after allocating a platform device.
Can't they just allocate a platform device using the override name instead?
What am I missing?

For the clk-exynos5-subcmu.c case, driver registers several
sub-devices. Each sub-devices is a clock controller associated with
power domain. I guess the author wanted to have meaningful names of
these sub-devices (DISP, CAM etc. like names of power domains),
instead of just exynos5-subcmu.1, exynos5-subcmu.2 ...

If driver_override should not be used for such case, then I could
replace it with what you said.

For the other uses of driver_override (drivers/rpmsg/rpmsg_internal.h
and drivers/slimbus/qcom-ngd-ctrl.c) I don't know.

Best regards,
Krzysztof

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