linux-kernel - Re: [GIT PULL] compiler-attributes for v5.3-rc8

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Message-ID: <CAKwvOdkodVFxUr_Xc-qeUHnpxEmofENDhNdvCuiRzcGXQ54QkQ@mail.gmail.com>
Date:   Fri, 6 Sep 2019 15:47:21 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Will Deacon <will@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Paul Burton <paul.burton@...s.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] compiler-attributes for v5.3-rc8

On Fri, Sep 6, 2019 at 1:11 PM Miguel Ojeda
<miguel.ojeda.sandonis@...il.com> wrote:
>
> On Thu, Sep 5, 2019 at 10:53 PM Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > That's probably what we should have done originally, avoiding all the
> > issues with "what if we have multi-part strings" etc.
> >
> > But it's not what we did, probably because it looked slightly simpler
> > to do the stringification in the macro for the usual case.
> >
> > So now we have (according to a quick grep) eight users that have a
> > constant string, and about one hundred users that use the unquoted
> > section name and expect the automatic stringification. I say "about",
> > because I didn't check if any of them might be doing tricks, I really
> > just did a stupid grep.
> >
> > And we have that _one_ insane KENTRY thing that was apparently never
> > actually used.
> >
> > So I think the minimal fix is to just accept that it's what it is,
> > remove the unnecessary quotes from the 8 existing users, and _if_
> > somebody wants to build the string  by hand (like the KENTRY code
> > did), then just use "__attribute__((section(x)))" for that.
> >
> > But yeah, we could just remove the stringification and make the users do it.
> >
> > But for the current late rc (and presumably -stable?), I definitely
> > want the absolute minimal thing that fixes the oops.
>
> Then I will send a PR with that patch only (Nick, do you know if the
> entire patch is needed or we could further reduce it?).

Sedat reported (https://github.com/ClangBuiltLinux/linux/issues/619#issuecomment-520042577,
https://github.com/ClangBuiltLinux/linux/issues/619#issuecomment-520065525)
that only the bottom two hunks of that patch
(https://github.com/ojeda/linux/commit/c97e82b97f4bba00304905fe7965f923abd2d755)

>
> Then for 5.4 I will prepare a new series moving to non-stringification
> (unless Nick wants to do it himself).

Technically, it's not a regression, just something that would be nice
to have sooner rather than later.  The whole series can wait for 5.4,
IMO.  I'll look into updating the patchset next week.
-- 
Thanks,
~Nick Desaulniers