[PATCH v2] iio: trigger: stm32-timer-trigger: Add check for clk_enable()

[Jiasheng Jiang]

On Sat, Nov 9, 2024 at 8:38 AM Jonathan Cameron <jic23 at kernel.org> wrote:
>
> On Fri,  8 Nov 2024 20:09:00 +0000
> Jiasheng Jiang <jiashengjiangcool at gmail.com> wrote:
>
> > Add check for the return value of clk_enable() in order to catch the
> > potential exception.
> >
> > Signed-off-by: Jiasheng Jiang <jiashengjiangcool at gmail.com>
> Hi,
>
> In principle this is fine, but I'd rather we made use of guard()
> / scoped_guard() rather than adding the explicit unlocks.
>
> If you do that as a precursor patch in appropriate places
> in the driver then this will be a little cleaner.
>
> Note I'll not be taking this until next cycle now anyway.
>
> Jonathan
>
> > ---
> > Changelog:
> >
> > v1 -> v2:
> >
> > 1. Remove unsuitable dev_err_probe().
> > ---
> >  drivers/iio/trigger/stm32-timer-trigger.c | 32 ++++++++++++++++++-----
> >  1 file changed, 25 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> > index 0684329956d9..e1e077122f73 100644
> > --- a/drivers/iio/trigger/stm32-timer-trigger.c
> > +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> > @@ -119,7 +119,7 @@ static int stm32_timer_start(struct stm32_timer_trigger *priv,
> >                            unsigned int frequency)
> >  {
> >       unsigned long long prd, div;
> > -     int prescaler = 0;
> > +     int prescaler = 0, ret;
> >       u32 ccer;
> >
> >       /* Period and prescaler values depends of clock rate */
> > @@ -153,7 +153,11 @@ static int stm32_timer_start(struct stm32_timer_trigger *priv,
> >       mutex_lock(&priv->lock);
> >       if (!priv->enabled) {
> >               priv->enabled = true;
> > -             clk_enable(priv->clk);
> > +             ret = clk_enable(priv->clk);
> > +             if (ret) {
> > +                     mutex_unlock(&priv->lock);
>
> as below guard() for when the mutex is locked is cleaner.
>
> > +                     return ret;
> > +             }
> >       }
> >
> >       regmap_write(priv->regmap, TIM_PSC, prescaler);
> > @@ -307,7 +311,7 @@ static ssize_t stm32_tt_store_master_mode(struct device *dev,
> >       struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
> >       struct iio_trigger *trig = to_iio_trigger(dev);
> >       u32 mask, shift, master_mode_max;
> > -     int i;
> > +     int i, ret;
> >
> >       if (stm32_timer_is_trgo2_name(trig->name)) {
> >               mask = TIM_CR2_MMS2;
> > @@ -326,7 +330,11 @@ static ssize_t stm32_tt_store_master_mode(struct device *dev,
> >                       if (!priv->enabled) {
> >                               /* Clock should be enabled first */
> >                               priv->enabled = true;
> > -                             clk_enable(priv->clk);
> > +                             ret = clk_enable(priv->clk);
> > +                             if (ret) {
> > +                                     mutex_unlock(&priv->lock);
> As below. Prefer use of guard() so we don't have to handle the unlock manually.
> > +                                     return ret;
> > +                             }
> >                       }
> >                       regmap_update_bits(priv->regmap, TIM_CR2, mask,
> >                                          i << shift);
> > @@ -482,6 +490,7 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
> >                                  int val, int val2, long mask)
> >  {
> >       struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> > +     int ret;
> >
> >       switch (mask) {
> >       case IIO_CHAN_INFO_RAW:
> > @@ -496,7 +505,11 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
> >               if (val) {
> >                       if (!priv->enabled) {
> >                               priv->enabled = true;
> > -                             clk_enable(priv->clk);
> > +                             ret = clk_enable(priv->clk);
> > +                             if (ret) {
> > +                                     mutex_unlock(&priv->lock);
> Add include of cleanup.h and swithch the place where the mutex is locked to
> guard(mutex)(&priv->lock);
> then remember to drop the explicit unlocks.

I found that cleanup.h is already included.

Moreover, since labels cannot be followed by declarations,
I encountered a compilation error when using guard().
Therefore, I switched to using scoped_guard().
>
> > +                                     return ret;
> > +                             }
> >                       }
> >                       regmap_set_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN);
> >               } else {
> > @@ -601,7 +614,7 @@ static int stm32_set_enable_mode(struct iio_dev *indio_dev,
> >                                unsigned int mode)
> >  {
> >       struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> > -     int sms = stm32_enable_mode2sms(mode);
> > +     int sms = stm32_enable_mode2sms(mode), ret;
> >
> >       if (sms < 0)
> >               return sms;
> > @@ -611,7 +624,12 @@ static int stm32_set_enable_mode(struct iio_dev *indio_dev,
> >        */
> >       mutex_lock(&priv->lock);
>
> Perhaps scoped_guard() is  appropriate here.
>
> >       if (sms == 6 && !priv->enabled) {
> > -             clk_enable(priv->clk);
> > +             ret = clk_enable(priv->clk);
> > +             if (ret) {
> > +                     mutex_unlock(&priv->lock);
> > +                     return ret;
> > +             }
> > +
> >               priv->enabled = true;
> >       }
> >       mutex_unlock(&priv->lock);
>

Thanks, I will submit a v2 to simplify code with cleanup helpers.

-Jiasheng