linux-kernel - Re: [GIT PULL] core kernel fixes

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Message-ID: <CA+55aFy+w_T2RB+wO6KhT=ocwYUJvyC=zjkuoQQLfCTWmozsLg@mail.gmail.com>
Date:   Sun, 5 Nov 2017 10:09:59 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] core kernel fixes

On Sun, Nov 5, 2017 at 6:33 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> Please note that this pull request is RFC due to the top commit:
>
>   ec1e1b610917: objtool: Prevent GCC from merging annotate_unreachable(), take 2
>
> ... which is admittedly somewhat of an ad-hoc workaround for something the
> compiler should have done - if there's another solution we can try that.

So I'm certainly ok with that workaround since apparently "asm
volatile" doesn't do it.

That said, I think that if that asm needs to not be merged, it should
_also_ be marked as "volatile" - since that's the documented bit for
"not moved significantly". Of course, then because apparently that
isn't enough, the __COUNTER__ games are ok, but might really mention
an explicit comment in the code as to why they exist. Because right
now they look just odd and nonsensical.

               Linus