Re: [RFC/PATCH] of: Mark property::value as const

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From	Rob Herring <robh+dt@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [RFC/PATCH] of: Mark property::value as const
Date	Thu, 23 Feb 2017 23:20:02 +0100
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On Thu, Feb 23, 2017 at 2:58 PM, Frank Rowand <frowand.list@gmail.com> wrote:
> On 02/23/17 11:54, Frank Rowand wrote:
>> On 02/13/17 18:50, Stephen Boyd wrote:
>>> The 'blob' we pass into populate_properties() is marked as const,
>>> but we cast that const away when we assign the result of
>>> fdt_getprop_by_offset() to pp->value. Let's mark value as const
>>> instead, so that code can't mistakenly write to the value of the
>>> property that we've so far advertised as const.
>>>
>>> Unfortunately, this exposes a problem with the fdt resolver code,
>>> where we overwrite the value member of properties of phandles to
>>> update them with their final value. Add a comment for now to
>>> indicate where we're potentially writing over const data.
>>
>> The resolver should not be over writing anything in the FDT.  I'll
>> look at what is going on there.
>>
>> The FDT we expose to user space should be the FDT we booted with,
>> not something later modified.
>
> It seems that /sys/firmware/fdt is not documented.  I'll look into
> fixing that.

That's because the "official" interface is /proc/device-tree/ which is
now a symlink. IIRC, it is documented to use /proc/device-tree, not
the sysfs path.

Rob

Thread

[RFC/PATCH] of: Mark property::value as const Stephen Boyd <stephen.boyd@linaro.org> - 2017-02-14 04:00 +0100
  Re: [RFC/PATCH] of: Mark property::value as const Rob Herring <robh+dt@kernel.org> - 2017-02-23 14:50 +0100
  Re: [RFC/PATCH] of: Mark property::value as const Frank Rowand <frowand.list@gmail.com> - 2017-02-23 21:00 +0100
    Re: [RFC/PATCH] of: Mark property::value as const Frank Rowand <frowand.list@gmail.com> - 2017-02-23 22:00 +0100
      Re: [RFC/PATCH] of: Mark property::value as const Rob Herring <robh+dt@kernel.org> - 2017-02-23 23:20 +0100
        Re: [RFC/PATCH] of: Mark property::value as const Frank Rowand <frowand.list@gmail.com> - 2017-02-24 00:30 +0100
    Re: [RFC/PATCH] of: Mark property::value as const Frank Rowand <frowand.list@gmail.com> - 2017-02-23 22:50 +0100
  Re: [RFC/PATCH] of: Mark property::value as const Frank Rowand <frowand.list@gmail.com> - 2017-02-24 00:10 +0100
    Re: [RFC/PATCH] of: Mark property::value as const Frank Rowand <frowand.list@gmail.com> - 2017-02-24 00:30 +0100
    Re: [RFC/PATCH] of: Mark property::value as const Rob Herring <robh+dt@kernel.org> - 2017-02-24 00:40 +0100

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