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

[Sascha Hauer <s.hauer@pengutronix.de>]

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.

Sascha

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