linux-kernel - Re: [PATCH] media: hantro: Fix PM reference leak in device

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Message-ID: <YKInrIMZYGI1VKdl@hovoldconsulting.com>
Date:   Mon, 17 May 2021 10:22:04 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Yu Kuai <yukuai3@...wei.com>
Cc:     ezequiel@...labora.com, p.zabel@...gutronix.de, mchehab@...nel.org,
        gregkh@...uxfoundation.org, linux-media@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com
Subject: Re: [PATCH] media: hantro: Fix PM reference leak in device_run()

On Mon, May 17, 2021 at 04:15:16PM +0800, Yu Kuai wrote:
> 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.
> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>  drivers/staging/media/hantro/hantro_drv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
> index eea2009fa17b..7a6d3ef22096 100644
> --- a/drivers/staging/media/hantro/hantro_drv.c
> +++ b/drivers/staging/media/hantro/hantro_drv.c
> @@ -160,7 +160,7 @@ static void device_run(void *priv)
>  	src = hantro_get_src_buf(ctx);
>  	dst = hantro_get_dst_buf(ctx);
>  
> -	ret = pm_runtime_get_sync(ctx->dev->dev);
> +	ret = pm_runtime_resume_and_get(ctx->dev->dev);
>  	if (ret < 0) {
>  		pm_runtime_put_noidle(ctx->dev->dev);

This is clearly broken as there is no PM usage count leak here.

Please try to understand the code you're changing before submitting any
more patches based on "robot" feedback.

>  		goto err_cancel_job;

Johan