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

Jonathan Cameron
2024-11-09T13:41:01Z

On Fri, 8 Nov 2024 20:09:00 +0000
Jiasheng Jiang <jiashengjiangcool@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@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.

> + 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);