linux-kernel - Re: [PATCH -next] drm: Fix PM reference leak

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Date:   Fri, 21 May 2021 17:32:09 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Zou Wei <zou_wei@...wei.com>
Cc:     a.hajda@...sung.com, narmstrong@...libre.com,
        robert.foss@...aro.org, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...il.com, airlied@...ux.ie,
        daniel@...ll.ch, emma@...olt.net, mripard@...nel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] drm: Fix PM reference leak

On Fri, May 21, 2021 at 09:03:06PM +0800, Zou Wei 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: Zou Wei <zou_wei@...wei.com>

Looks good, but can you pls split this up into a patch per driver (vc and
bridge/cdns-dsi here)?

Thanks, Daniel

> ---
>  drivers/gpu/drm/bridge/cdns-dsi.c | 2 +-
>  drivers/gpu/drm/vc4/vc4_hdmi.c    | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/cdns-dsi.c b/drivers/gpu/drm/bridge/cdns-dsi.c
> index 76373e3..b31281f 100644
> --- a/drivers/gpu/drm/bridge/cdns-dsi.c
> +++ b/drivers/gpu/drm/bridge/cdns-dsi.c
> @@ -1028,7 +1028,7 @@ static ssize_t cdns_dsi_transfer(struct mipi_dsi_host *host,
>  	struct mipi_dsi_packet packet;
>  	int ret, i, tx_len, rx_len;
>  
> -	ret = pm_runtime_get_sync(host->dev);
> +	ret = pm_runtime_resume_and_get(host->dev);
>  	if (ret < 0)
>  		return ret;
>  
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index c27b287..f20a65b 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -798,7 +798,7 @@ static void vc4_hdmi_encoder_pre_crtc_configure(struct drm_encoder *encoder,
>  	unsigned long pixel_rate, hsm_rate;
>  	int ret;
>  
> -	ret = pm_runtime_get_sync(&vc4_hdmi->pdev->dev);
> +	ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);
>  	if (ret < 0) {
>  		DRM_ERROR("Failed to retain power domain: %d\n", ret);
>  		return;
> -- 
> 2.6.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch