linux-kernel - Re: [GIT PULL] Device properties framework update for v4.18-rc1

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Date:   Wed, 6 Jun 2018 00:33:38 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] Device properties framework update for v4.18-rc1

On Tue, Jun 5, 2018 at 7:39 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Tue, Jun 5, 2018 at 10:30 AM Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
>>
>> Honestly, this looks questionable to me.
>>
>> I'm not talking about the changes themselves - I can live with them.
>> But the _rationale_ is pure and utter garbage, and dangerously so.
>
> Side note: I've merged it, and it's going through my build tests, so
> it's really not that I hate the code.
>
> But I really find that kind of one-sided rationale that ignores
> reality unacceptable.
>
> And I find it dangerous, because it *sounds* so "obviously correct" to
> people who don't know any better. If you don't know that gcc
> explicitly says that you should use unions to do type punning to avoid
> aliasing issues, you might believe that union type punning is a bad
> thing from that commit message.
>
> So it's dangerously misleading, because lots of people have a
> dangerous reverence for paper over reality.
>
> In programming, "Appeal to Standards" should be considered a potential
> logical fallacy. Standards have their place, but they definitely have
> their caveats too.

Well, AFAICS the point was that the union aliasing was not
particularly useful in this case and it clearly was avoidable.  The
changelog could do a better job at explaining that, though, sorry
about that.

And thanks for merging it in spite of your concerns!

Rafael