On Friday, April 13, 2018 01:00:09 PM Daniel Lezcano wrote:
> The latest driver cleanup introduced a compilation warning
>
> drivers/thermal/samsung/exynos_tmu.c: In function ‘exynos_get_temp’:
> drivers/thermal/samsung/exynos_tmu.c:931:37: warning: ‘temp’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> *temp = code_to_temp(data, value) * MCELSIUS;
> ^
>
> drivers/thermal/samsung/exynos_tmu.c: In function ‘temp_to_code’
> drivers/thermal/samsung/exynos_tmu.c:304:9: warning: ‘temp_code’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> return temp_code;
> ^~~~~~~~~
>
> The compiler gives a warning because semantically speaking the
> function has no default value. However the code path, were the
> variable is never initialized is a dead branch because the switch
> statement always choose one of the two cases as the data->cal_type is
> initialized in the init function to one of both values.
>
> This is unclear as it adds a dependency on the initialization function
> and it is prone to error. Make things clearer by converting the
> functions with if ... return statements, thus showing we are expecting
> the values to be correctly filled before calling this function.
>
> This change fixes the couple of function warnings.
>
> Signed-off-by: Daniel Lezcano <[email protected]>

Thanks Daniel, this is much better fix.

Acked-by: Bartlomiej Zolnierkiewicz <[email protected]>

> ---
> drivers/thermal/samsung/exynos_tmu.c | 46 ++++++++++--------------------------
> 1 file changed, 12 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> index 2ec8548..197f267 100644
> --- a/drivers/thermal/samsung/exynos_tmu.c
> +++ b/drivers/thermal/samsung/exynos_tmu.c
> @@ -284,24 +284,13 @@ static void exynos_report_trigger(struct exynos_tmu_data *p)
> */
> static int temp_to_code(struct exynos_tmu_data *data, u8 temp)
> {
> - int temp_code;
> -
> - switch (data->cal_type) {
> - case TYPE_TWO_POINT_TRIMMING:
> - temp_code = (temp - EXYNOS_FIRST_POINT_TRIM) *
> - (data->temp_error2 - data->temp_error1) /
> - (EXYNOS_SECOND_POINT_TRIM - EXYNOS_FIRST_POINT_TRIM) +
> - data->temp_error1;
> - break;
> - case TYPE_ONE_POINT_TRIMMING:
> - temp_code = temp + data->temp_error1 - EXYNOS_FIRST_POINT_TRIM;
> - break;
> - default:
> - WARN_ON(1);
> - break;
> - }
> + if (data->cal_type == TYPE_ONE_POINT_TRIMMING)
> + return temp + data->temp_error1 - EXYNOS_FIRST_POINT_TRIM;
>
> - return temp_code;
> + return (temp - EXYNOS_FIRST_POINT_TRIM) *
> + (data->temp_error2 - data->temp_error1) /
> + (EXYNOS_SECOND_POINT_TRIM - EXYNOS_FIRST_POINT_TRIM) +
> + data->temp_error1;
> }
>
> /*
> @@ -310,24 +299,13 @@ static int temp_to_code(struct exynos_tmu_data *data, u8 temp)
> */
> static int code_to_temp(struct exynos_tmu_data *data, u16 temp_code)
> {
> - int temp;
> -
> - switch (data->cal_type) {
> - case TYPE_TWO_POINT_TRIMMING:
> - temp = (temp_code - data->temp_error1) *
> - (EXYNOS_SECOND_POINT_TRIM - EXYNOS_FIRST_POINT_TRIM) /
> - (data->temp_error2 - data->temp_error1) +
> - EXYNOS_FIRST_POINT_TRIM;
> - break;
> - case TYPE_ONE_POINT_TRIMMING:
> - temp = temp_code - data->temp_error1 + EXYNOS_FIRST_POINT_TRIM;
> - break;
> - default:
> - WARN_ON(1);
> - break;
> - }
> + if (data->cal_type == TYPE_ONE_POINT_TRIMMING)
> + return temp_code - data->temp_error1 + EXYNOS_FIRST_POINT_TRIM;
>
> - return temp;
> + return (temp_code - data->temp_error1) *
> + (EXYNOS_SECOND_POINT_TRIM - EXYNOS_FIRST_POINT_TRIM) /
> + (data->temp_error2 - data->temp_error1) +
> + EXYNOS_FIRST_POINT_TRIM;
> }
>
> static void sanitize_temp_error(struct exynos_tmu_data *data, u32 trim_info)

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

2018-04-15 08:53:20

by Eduardo Valentin

[permalink] [raw]

Subject: Re: [GIT PULL] Thermal management updates for v4.17-rc1

On Fri, Apr 13, 2018 at 12:27:17PM +0200, Bartlomiej Zolnierkiewicz wrote:
> On Friday, April 13, 2018 03:08:03 AM Eduardo Valentin wrote:
> > On Fri, Apr 13, 2018 at 01:39:05PM +0800, Zhang Rui wrote:
> > > Hi, Eduardo,
> > >
> > > On 四, 2018-04-12 at 21:08 -0700, Eduardo Valentin wrote:
> > > > Hello,
> > > >
> > > > On Thu, Apr 12, 2018 at 09:55:19AM -0700, Linus Torvalds wrote:
> > > > >
> > > > > On Wed, Apr 11, 2018 at 10:08 PM, Zhang Rui <[email protected]>
> > > > > wrote:
> > > > > >
> > > > > >
> > > > > > could you please illustrate me what the kconfig & warning is?
> > > > > Just "make allmodconfig" and the warning is about a uninitialized
> > > > > variable.
> > > > >
> > > > > Line 304 in drivers/thermal/samsung/exynos_tmu.c if my shell
> > > > > history
> > > > > is to be believed.
> > > > >
> > > > > Linus
> > > > Yeah, this has also passed my local compilation error. Somehow my
> > > > gcc4.9
> > > > is not catching it. Using an older gcc (gcc4.6) does catch it.
> > > >
> > > > Anyways, given that the conversion functions are written to cover
> > > > for unexpected cal_type, the right way of fixing this is to rewrite
> > > > the conversion functions to allow for returning error codes and
> > > > adjusting the callers as expected.
> > > >
> > > > Rui, bzolnier, please consider the following fix:
> > > >
> > > as it is late in this merge window, I'd prefer to
> > > 1. drop all the thermal-soc material in the first pull request which I
> > > will send out soon.
> > > 2. you can prepare another pull request containing the thermal-soc
> > > materials except the exynos fixes
> > > 3. exynos fixes with the problem solved can be queued for -rc2 or
> > > later.
> > >
> >
> > Agreed
>
> What should I do now to help resolve the issue?

Please resend your series with the patches without the warnings..

Thanks,

Eduardo