linux-kernel - Re: [PATCH v2] rtc: amlogic-a4: fix double free caused by devm

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Message-ID: <126bce2b-d899-40e8-ae45-07dfd1e3f8c7@amlogic.com>
Date: Wed, 22 Oct 2025 13:48:02 +0800
From: Xianwei Zhao <xianwei.zhao@...ogic.com>
To: Haotian Zhang <vulab@...as.ac.cn>, alexandre.belloni@...tlin.com,
 yiting.deng@...ogic.com
Cc: linux-amlogic@...ts.infradead.org, linux-rtc@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] rtc: amlogic-a4: fix double free caused by devm

Reviewed-by: Xianwei Zhao <xianwei.zhao@...ogic.com>
On 2025/10/21 18:35, Haotian Zhang wrote:
> [Some people who received this message don't often get email from vulab@...as.ac.cn. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> [ EXTERNAL EMAIL ]
> 
> The clock obtained via devm_clk_get_enabled() is automatically managed
> by devres and will be disabled and freed on driver detach. Manually
> calling clk_disable_unprepare() in error path and remove function
> causes double free.
> 
> Remove the redundant clk_disable_unprepare() calls from the probe
> error path and aml_rtc_remove(), allowing the devm framework to
> automatically manage the clock lifecycle.
> 
> Fixes: c89ac9182ee2 ("rtc: support for the Amlogic on-chip RTC")
> Signed-off-by: Haotian Zhang <vulab@...as.ac.cn>
> ---
> v2: Also remove the now-unused local variable 'rtc' in aml_rtc_remove()
> ---
>   drivers/rtc/rtc-amlogic-a4.c | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-amlogic-a4.c b/drivers/rtc/rtc-amlogic-a4.c
> index 1928b29c1045..a993d35e1d6b 100644
> --- a/drivers/rtc/rtc-amlogic-a4.c
> +++ b/drivers/rtc/rtc-amlogic-a4.c
> @@ -390,7 +390,6 @@ static int aml_rtc_probe(struct platform_device *pdev)
> 
>          return 0;
>   err_clk:
> -       clk_disable_unprepare(rtc->sys_clk);
>          device_init_wakeup(dev, false);
> 
>          return ret;
> @@ -423,9 +422,6 @@ static SIMPLE_DEV_PM_OPS(aml_rtc_pm_ops,
> 
>   static void aml_rtc_remove(struct platform_device *pdev)
>   {
> -       struct aml_rtc_data *rtc = dev_get_drvdata(&pdev->dev);
> -
> -       clk_disable_unprepare(rtc->sys_clk);
>          device_init_wakeup(&pdev->dev, false);
>   }
> 
> --
> 2.25.1
>