linux-kernel - Re: [PATCH 1/4] media: nuvoton: Fix reference handling of ece

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Message-ID: <dffc8e0b-2603-4e7e-ba64-15691c11ff7e@xs4all.nl>
Date: Fri, 21 Feb 2025 10:18:27 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Ricardo Ribalda <ribalda@...omium.org>, Joseph Liu <kwliu@...oton.com>,
 Marvin Lin <kflin@...oton.com>, Mauro Carvalho Chehab <mchehab@...nel.org>,
 Philipp Zabel <p.zabel@...gutronix.de>
Cc: Marvin Lin <milkfafa@...il.com>, linux-media@...r.kernel.org,
 openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH 1/4] media: nuvoton: Fix reference handling of ece_pdev

On 21/02/2025 10:04, Hans Verkuil wrote:
> Hi Ricardo,
> 
> On 21/01/2025 22:14, Ricardo Ribalda wrote:
>> When we obtain a reference to of a platform_device, we need to release
>> it via put_device.
>>
>> Found by cocci:
>> ./platform/nuvoton/npcm-video.c:1677:3-9: ERROR: missing put_device; call of_find_device_by_node on line 1667, but without a corresponding object release within this function.
>> ./platform/nuvoton/npcm-video.c:1684:3-9: ERROR: missing put_device; call of_find_device_by_node on line 1667, but without a corresponding object release within this function.
>> ./platform/nuvoton/npcm-video.c:1690:3-9: ERROR: missing put_device; call of_find_device_by_node on line 1667, but without a corresponding object release within this function.
>> ./platform/nuvoton/npcm-video.c:1694:1-7: ERROR: missing put_device; call of_find_device_by_node on line 1667, but without a corresponding object release within this function.
> 
> This driver uses this construct:
> 
>                 struct device *ece_dev __free(put_device) = &ece_pdev->dev;
> 
> to automatically call put_device. So this patch would 'put' the device twice.
> 
> Does cocci understand constructs like this? If I hadn't looked closely at the
> code first, I would just have merged it.

Oh wait, now that I am reading the following patches I see that it was those later
patches that add the __free code.

This is far too confusing. Please post a v2 that just combines the 'fix references'
and 'use cleanup.h macros' in a single patch. It makes no sense to have this two-phase
approach.

Regards,

	Hans

> 
> Regards,
> 
> 	Hans
> 
>>
>> Cc: stable@...r.kernel.org
>> Fixes: 46c15a4ff1f4 ("media: nuvoton: Add driver for NPCM video capture and encoding engine")
>> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
>> ---
>>  drivers/media/platform/nuvoton/npcm-video.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/media/platform/nuvoton/npcm-video.c b/drivers/media/platform/nuvoton/npcm-video.c
>> index 024cd8ee1709..7b4c23dbe709 100644
>> --- a/drivers/media/platform/nuvoton/npcm-video.c
>> +++ b/drivers/media/platform/nuvoton/npcm-video.c
>> @@ -1673,6 +1673,7 @@ static int npcm_video_ece_init(struct npcm_video *video)
>>  
>>  		regs = devm_platform_ioremap_resource(ece_pdev, 0);
>>  		if (IS_ERR(regs)) {
>> +			put_device(&ece_pdev->dev);
>>  			dev_err(dev, "Failed to parse ECE reg in DTS\n");
>>  			return PTR_ERR(regs);
>>  		}
>> @@ -1680,11 +1681,13 @@ static int npcm_video_ece_init(struct npcm_video *video)
>>  		video->ece.regmap = devm_regmap_init_mmio(dev, regs,
>>  							  &npcm_video_ece_regmap_cfg);
>>  		if (IS_ERR(video->ece.regmap)) {
>> +			put_device(&ece_pdev->dev);
>>  			dev_err(dev, "Failed to initialize ECE regmap\n");
>>  			return PTR_ERR(video->ece.regmap);
>>  		}
>>  
>>  		video->ece.reset = devm_reset_control_get(&ece_pdev->dev, NULL);
>> +		put_device(&ece_pdev->dev);
>>  		if (IS_ERR(video->ece.reset)) {
>>  			dev_err(dev, "Failed to get ECE reset control in DTS\n");
>>  			return PTR_ERR(video->ece.reset);
>>
> 
>