linux-kernel - Re: [PATCH 5.10 105/299] crypto: stm32/cryp - Fix PM reference leak on stm32-cryp.c

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Date:   Mon, 10 May 2021 14:07:42 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Shixin Liu <liushixin2@...wei.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.10 105/299] crypto: stm32/cryp - Fix PM reference leak
 on stm32-cryp.c

On Mon 2021-05-10 12:18:22, Greg Kroah-Hartman wrote:
> From: Shixin Liu <liushixin2@...wei.com>
> 
> [ Upstream commit 747bf30fd944f02f341b5f3bc7d97a13f2ae2fbe ]
> 
> pm_runtime_get_sync will increment pm usage counter even it failed.
> Forgetting to putting operation will result in reference leak here.
> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
> counter balanced.

Yes, but that only works when code checks the return value.

> +++ b/drivers/crypto/stm32/stm32-cryp.c
> @@ -542,7 +542,7 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
>  	int ret;
>  	u32 cfg, hw_mode;
>  
> -	pm_runtime_get_sync(cryp->dev);
> +	pm_runtime_resume_and_get(cryp->dev);
>  
>  	/* Disable interrupt */
>  	stm32_cryp_write(cryp, CRYP_IMSCR, 0);

Again, this is wrong.

> @@ -2043,7 +2043,7 @@ static int stm32_cryp_remove(struct platform_device *pdev)
>  	if (!cryp)
>  		return -ENODEV;
>  
> -	ret = pm_runtime_get_sync(cryp->dev);
> +	ret = pm_runtime_resume_and_get(cryp->dev);
>  	if (ret < 0)
>  		return ret;
>  

But this may be right.

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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