linux-kernel - Re: [PATCH 13/25] media: rcar_fdp1: fix pm_runtime_get

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Date:   Wed, 5 May 2021 13:31:15 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
CC:     <linuxarm@...wei.com>, <mauro.chehab@...wei.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 13/25] media: rcar_fdp1: fix pm_runtime_get_sync() usage
 count

On Wed, 5 May 2021 11:42:03 +0200
Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:

> The pm_runtime_get_sync() internally increments the
> dev->power.usage_count without decrementing it, even on errors.
> Replace it by the new pm_runtime_resume_and_get(), introduced by:
> commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> in order to properly decrement the usage counter, avoiding
> a potential PM usage counter leak.
> 
> Also, right now, the driver is ignoring any troubles when
> trying to do PM resume. So, add the proper error handling
> for the code.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
>  drivers/media/platform/rcar_fdp1.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar_fdp1.c b/drivers/media/platform/rcar_fdp1.c
> index d26413fa5205..89aac60066d9 100644
> --- a/drivers/media/platform/rcar_fdp1.c
> +++ b/drivers/media/platform/rcar_fdp1.c
> @@ -2135,7 +2135,9 @@ static int fdp1_open(struct file *file)
>  	}
>  
>  	/* Perform any power management required */
> -	pm_runtime_get_sync(fdp1->dev);
> +	ret = pm_runtime_resume_and_get(fdp1->dev);
> +	if (ret < 0)
> +		goto error_pm;
>  
>  	v4l2_fh_add(&ctx->fh);
>  
> @@ -2145,6 +2147,8 @@ static int fdp1_open(struct file *file)
>  	mutex_unlock(&fdp1->dev_mutex);
>  	return 0;
>  
> +error_pm:
> +       v4l2_m2m_ctx_release(ctx->fh.m2m_ctx);
>  error_ctx:
>  	v4l2_ctrl_handler_free(&ctx->hdl);
>  	kfree(ctx);
> @@ -2352,7 +2356,9 @@ static int fdp1_probe(struct platform_device *pdev)
>  
>  	/* Power up the cells to read HW */
>  	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_get_sync(fdp1->dev);
> +	ret = pm_runtime_resume_and_get(fdp1->dev);
> +	if (ret < 0)
> +		goto disable_pm;
>  
>  	hw_version = fdp1_read(fdp1, FD1_IP_INTDATA);
>  	switch (hw_version) {
> @@ -2381,6 +2387,9 @@ static int fdp1_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> +disable_pm:
> +	pm_runtime_disable(fdp1->dev);
> +
>  release_m2m:
>  	v4l2_m2m_release(fdp1->m2m_dev);
>