[PATCH] rtc: ma35d1: fix permanent clock reference/enable-count leak in probe

[PATCH] rtc: ma35d1: fix permanent clock reference/enable-count leak in probe

[Cong Nguyen]

ma35d1_rtc_probe() gets the RTC clock via of_clk_get() and enables it
via clk_prepare_enable(), but the struct clk * is a local variable --
never stored anywhere, and the driver has no .remove. So on every
probe, success or failure, there's no way to ever call
clk_disable_unprepare()/clk_put() on it -- a permanent leak, and since
CONFIG_RTC_DRV_MA35D1 is tristate, each module load/unload leaks
another one.

Replace of_clk_get() + clk_prepare_enable() with
devm_clk_get_enabled() -- same clock (both route through
__of_clk_get(np, 0, ...)) but devm-managed, so it's released
automatically on unbind or any probe-failure return.

Fixes: dc0684adf3b6 ("rtc: Add driver for Nuvoton ma35d1 rtc controller")
Assisted-by: Claude:claude-opus-4
Signed-off-by: Cong Nguyen <congnt264@gmail.com>
---
 drivers/rtc/rtc-ma35d1.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/rtc/rtc-ma35d1.c b/drivers/rtc/rtc-ma35d1.c
index cfcfc28060f6..43358d68565a 100644
--- a/drivers/rtc/rtc-ma35d1.c
+++ b/drivers/rtc/rtc-ma35d1.c
@@ -221,14 +221,10 @@ static int ma35d1_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(rtc->rtc_reg))
 		return PTR_ERR(rtc->rtc_reg);
 
-	clk = of_clk_get(pdev->dev.of_node, 0);
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(clk))
 		return dev_err_probe(&pdev->dev, PTR_ERR(clk), "failed to find rtc clock\n");
 
-	ret = clk_prepare_enable(clk);
-	if (ret)
-		return ret;
-
 	if (!(rtc_reg_read(rtc, MA35_REG_RTC_INIT) & RTC_INIT_ACTIVE)) {
 		ret = ma35d1_rtc_init(rtc, RTC_INIT_TIMEOUT);
 		if (ret)
-- 
2.25.1

Re: [PATCH] rtc: ma35d1: fix permanent clock reference/enable-count leak in probe

[Jacky Huang]

> diff --git a/drivers/rtc/rtc-ma35d1.c b/drivers/rtc/rtc-ma35d1.c
> index cfcfc28060f6..43358d68565a 100644
> --- a/drivers/rtc/rtc-ma35d1.c
> +++ b/drivers/rtc/rtc-ma35d1.c
> @@ -221,14 +221,10 @@ static int ma35d1_rtc_probe(struct platform_device *pdev)
>          if (IS_ERR(rtc->rtc_reg))
>                  return PTR_ERR(rtc->rtc_reg);
>
> -       clk = of_clk_get(pdev->dev.of_node, 0);
> +       clk = devm_clk_get_enabled(&pdev->dev, NULL);
>          if (IS_ERR(clk))
>                  return dev_err_probe(&pdev->dev, PTR_ERR(clk), "failed to find rtc clock\n");
>
> -       ret = clk_prepare_enable(clk);
> -       if (ret)
> -               return ret;
> -
>          if (!(rtc_reg_read(rtc, MA35_REG_RTC_INIT) & RTC_INIT_ACTIVE)) {
>                  ret = ma35d1_rtc_init(rtc, RTC_INIT_TIMEOUT);
>                  if (ret)
> --
> 2.25.1
>

Hi Cong,

Thanks for fixing this.

The conversion to devm_clk_get_enabled() correctly fixes the
clock reference and enable-count leak while preserving the RTC
clock behavior during the device lifetime.

Reviewed-by: Jacky Huang <ychuang3@nuvoton.com>

Best regards,
Jacky Huang