Re: [PATCH] net:fec: fixed unaligned access and stack corruption

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 7/11/20 7:20 AM, Sascha Hauer wrote:
> On Sat, Jul 11, 2020 at 07:13:11AM +0200, Ahmad Fatoum wrote:
>>
>>
>> On 7/11/20 7:07 AM, Sascha Hauer wrote:
>>> On Tue, Jul 07, 2020 at 07:11:31PM +0200, Ahmad Fatoum wrote:
>>>> On 7/7/20 6:01 PM, Enrico Scholz wrote:
>>>>> on 64 bit architectures, the 'enum fec_type' might not be aligned and
>>>>> large enough to hold a pointer.  
>>>>
>>>> I am wondering if we couldn't just adopt the Linux prototype:
>>>> void *dev_get_drvdata(const struct device_d *dev);
>>>>
>>>> and do away with the error code and most of the casts.
>>>> Users won't be able to differentiate between NULL from id table
>>>> and NULL due to lack of drvdata, but I don't think this is
>>>> that much of a downside, compared with not having casts obscure
>>>> the more common pitfall (besides fec_imx.c, lm75.c, apbh_dma.c and nand_mxs.c
>>>> are affected as well of which probably only the first is an issue.)
>>>
>>> Sounds good. When we change this we should rename the function
>>> alongside, because dev_get_drvdata() does something different in Linux.
>>
>> Does it? I thought it does the same, with the difference that it can
>> be set with dev_set_drvdata as well. At the cost of one extra pointer
>> per device_d, we could have both of them.
> 
> dev_set_drvdata() in Linux allows you to store a pointer to private
> driver data in struct device. We don't have a function for that in
> barebox and use dev->priv instead.
> dev_get_drvdata() in barebox gets you the device type data (or however
> we want to call it). There's no function for that in Linux and we have
> to first find out if we probe from platform data or from device tree
> to pick the right function to get the data.

Ah, I thought the drvdata is pre-populated in Linux. I would rename
the new function to device_get_match_data then for alignment with
Linux, with the difference that it returns either platform data or
device tree driver_data as appropriate.

Thanks
Ahmad

> 
> Sascha
> 

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