linux-kernel - Re: [PATCH v2] ARM: imx: fix error handling

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Message-ID: <5375FB36.8020004@bfs.de>
Date:	Fri, 16 May 2014 13:49:10 +0200
From:	walter harms <wharms@....de>
To:	Emil Goode <emilgoode@...il.com>
CC:	Shawn Guo <shawn.guo@...escale.com>,
	Sascha Hauer <kernel@...gutronix.de>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] ARM: imx: fix error handling



Am 16.05.2014 13:16, schrieb Emil Goode:
> Hello Walter,
> 
> On Fri, May 16, 2014 at 12:40:19PM +0200, walter harms wrote:
>>
>>
>> Am 16.05.2014 11:54, schrieb Emil Goode:
>>> If we fail to allocate struct platform_device pdev we
>>> dereference it after the goto label err.
>>>
>>> I have rearranged the error handling a bit to fix the issue
>>> and also make it more clear.
>>>
>>> Signed-off-by: Emil Goode <emilgoode@...il.com>
>>> ---
>>> v2: Changed to return -ENOMEM instead of ret where possible and
>>>     updated the subject line.
>>>
>>>  arch/arm/mach-imx/devices/platform-ipu-core.c |   22 +++++++++++++---------
>>>  1 file changed, 13 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-imx/devices/platform-ipu-core.c b/arch/arm/mach-imx/devices/platform-ipu-core.c
>>> index fc4dd7c..68f2a4a 100644
>>> --- a/arch/arm/mach-imx/devices/platform-ipu-core.c
>>> +++ b/arch/arm/mach-imx/devices/platform-ipu-core.c
>>> @@ -77,34 +77,38 @@ struct platform_device *__init imx_alloc_mx3_camera(
>>>  
>>>  	pdev = platform_device_alloc("mx3-camera", 0);
>>>  	if (!pdev)
>>> -		goto err;
>>> +		return ERR_PTR(-ENOMEM);
>>>  
>>>  	pdev->dev.dma_mask = kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL);
>>>  	if (!pdev->dev.dma_mask)
>>> -		goto err;
>>> +		goto put_pdev;
>>>  
>>>  	*pdev->dev.dma_mask = DMA_BIT_MASK(32);
>>>  	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
>>>  
>>>  	ret = platform_device_add_resources(pdev, res, ARRAY_SIZE(res));
>>>  	if (ret)
>>> -		goto err;
>>> +		goto free_dma_mask;
>>>  
>>>  	if (pdata) {
>>>  		struct mx3_camera_pdata *copied_pdata;
>>>  
>>>  		ret = platform_device_add_data(pdev, pdata, sizeof(*pdata));
>>> -		if (ret) {
>>> -err:
>>> -			kfree(pdev->dev.dma_mask);
>>> -			platform_device_put(pdev);
>>> -			return ERR_PTR(-ENODEV);
>>> -		}
>>> +		if (ret)
>>> +			goto free_dma_mask;
>>> +
>>>  		copied_pdata = dev_get_platdata(&pdev->dev);
>>>  		copied_pdata->dma_dev = &imx_ipu_coredev->dev;
>>
>>
>> the patch is fine, but what use is this copied_pdata ?
>> It scope ends next line ?
>>
>> re,
>>  wh
> 
> I also thought that looked a bit odd, but copied_pdata is a temporary
> pointer to platform_data of the dev struct.
> 
> dev_get_platdata looks like this:
> 
> static inline void *dev_get_platdata(const struct device *dev)
> {
>         return dev->platform_data;
> }
> 
> So I believe it's a more compact way of writing:
> 
> pdev->dev->platform_data->dma_dev = &imx_ipu_coredev->dev;

ok i see ...

Both ways are horrible to read, but the second is at least
understandable. fortunately i am not the maintainer.

thx,

re,
 wh

> Best regards,
> 
> Emil Goode
> 
>>
>>>  	}
>>>  
>>>  	return pdev;
>>> +
>>> +free_dma_mask:
>>> +	kfree(pdev->dev.dma_mask);
>>> +put_pdev:
>>> +	platform_device_put(pdev);
>>> +
>>> +	return ERR_PTR(ret);
>>>  }
>>>  
>>>  struct platform_device *__init imx_add_mx3_sdc_fb(
> 
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