Re: [PATCH 06/10] thermal: exynos: remove redundant threshold_code checks from exynos_tmu_initialize()

Bartlomiej Zolnierkiewicz
2014-05-15T16:57:34Z

On Thursday, May 15, 2014 10:55:52 AM Eduardo Valentin wrote:
> Hello Bartlomiej,

Hi,

> On Mon, May 05, 2014 at 01:15:35PM +0200, Bartlomiej Zolnierkiewicz wrote:
> > Remove runtime checks for negative return values of temp_to_code()
> > from exynos_tmu_initialize(). The current level temperature data
> > hardcoded in pdata will never cause a negative temp_to_code()
> > return values and for the new code potential mistakes should be
> > caught during development/review phases.
> >
> > Theres should be no functional changes caused by this patch.
> >
>
> Same question as in previous patch. Removing defensive code must

Simirarly like in a previous case. Such verification should not be done
at runtime in a production code because it is already too late for such
checking. It should be done during development and review phases.

> be done carefully.

BTW In case of temp_to_code() its users should be audited to pass only
input values that give positive results and later the function itself
may be modified to catch wrong input values by using WARN_ON (or even
BUG_ON).

> > Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> > ---
> > drivers/thermal/samsung/exynos_tmu.c | 16 +---------------
> > 1 file changed, 1 insertion(+), 15 deletions(-)
> >
> > diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> > index 789d745..a415829 100644
> > --- a/drivers/thermal/samsung/exynos_tmu.c
> > +++ b/drivers/thermal/samsung/exynos_tmu.c
> > @@ -170,10 +170,6 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
> > if (data->soc == SOC_ARCH_EXYNOS4210) {
> > /* Write temperature code for threshold */
> > threshold_code = temp_to_code(data, pdata->threshold);
> > - if (threshold_code < 0) {
> > - ret = threshold_code;
> > - goto out;
> > - }
> > writeb(threshold_code,
> > data->base + reg->threshold_temp);
> > for (i = 0; i < trigger_levs; i++)
> > @@ -187,18 +183,12 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
> > i < trigger_levs && i < EXYNOS_MAX_TRIGGER_PER_REG; i++) {
> > threshold_code = temp_to_code(data,
> > pdata->trigger_levels[i]);
> > - if (threshold_code < 0) {
> > - ret = threshold_code;
> > - goto out;
> > - }
> > rising_threshold |= threshold_code << 8 * i;
> > if (pdata->threshold_falling) {
> > threshold_code = temp_to_code(data,
> > pdata->trigger_levels[i] -
> > pdata->threshold_falling);
> > - if (threshold_code > 0)
> > - falling_threshold |=
> > - threshold_code << 8 * i;
> > + falling_threshold |= threshold_code << 8 * i;
> > }
> > }
> >
> > @@ -217,10 +207,6 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
> > (pdata->trigger_type[i] == HW_TRIP)) {
> > threshold_code = temp_to_code(data,
> > pdata->trigger_levels[i]);
> > - if (threshold_code < 0) {
> > - ret = threshold_code;
> > - goto out;
> > - }
> > if (i == EXYNOS_MAX_TRIGGER_PER_REG - 1) {
> > /* 1-4 level to be assigned in th0 reg */
> > rising_threshold |= threshold_code << 8 * i;

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