linux-kernel - Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng

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Date:   Fri, 27 Nov 2020 15:26:22 +0100
From:   Lukasz Stelmach <l.stelmach@...sung.com>
To:     Qinglang Miao <miaoqinglang@...wei.com>
Cc:     "Krzysztof Kozlowski" <krzk@...nel.org>,
        <linux-samsung-soc@...r.kernel.org>,
        <linux-crypto@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

It was <2020-11-27 pią 17:44>, when Qinglang Miao wrote:
> pm_runtime_get_sync will increment pm usage counter even it
> failed. Forgetting to putting operation will result in a
> reference leak here.
>
> A new function pm_runtime_resume_and_get is introduced in
> [0] to keep usage counter balanced. So We fix the reference
> leak by replacing it with new funtion.
>
> [0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")
>
> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Qinglang Miao <miaoqinglang@...wei.com>
> ---
>  drivers/char/hw_random/exynos-trng.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
> index 8e1fe3f8d..666246bc8 100644
> --- a/drivers/char/hw_random/exynos-trng.c
> +++ b/drivers/char/hw_random/exynos-trng.c
> @@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
>  		return PTR_ERR(trng->mem);
>  
>  	pm_runtime_enable(&pdev->dev);
> -	ret = pm_runtime_get_sync(&pdev->dev);
> +	ret = pm_runtime_resume_and_get(&pdev->dev);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "Could not get runtime PM.\n");
>  		goto err_pm_get;

Thanks. I suppose you may use the new function exynos_trng_resume(),
remove everything and leave only

return pm_runtime_resume_and_get(dev);

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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