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

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Date:   Mon, 24 May 2021 14:37:30 +0800
From:   Samuel Zou <zou_wei@...wei.com>
To:     <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>,
        <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


Hi Daniel,

Thanks for your review, I will split the patch and resend.

On 2021/5/21 23:32, Daniel Vetter wrote:
> 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
>>
>