Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20190930112636.vx2qxo4hdysvxibl@willie-the-truck>
 <CAK7LNASQZ82KSOrQW7+Wq1vFDCg2__maBEAPMLqUDqZMLuj1rA@mail.gmail.com>
 <20190930121803.n34i63scet2ec7ll@willie-the-truck> <CAKwvOdnqn=0LndrX+mUrtSAQqoT1JWRMOJCA5t3e=S=T7zkcCQ@mail.gmail.com>
 <20191001092823.z4zhlbwvtwnlotwc@willie-the-truck> <CAKwvOdk0h2A6=fb7Yepf+oKbZfq_tqwpGq8EBmHVu1j4mo-a-A@mail.gmail.com>
 <20191001170142.x66orounxuln7zs3@willie-the-truck> <CAKwvOdnFJqipp+G5xLDRBcOrQRcvMQmn+n8fufWyzyt2QL_QkA@mail.gmail.com>
 <20191001175512.GK25745@shell.armlinux.org.uk> <CAKwvOdmw_xmTGZLeK8-+Q4nUpjs-UypJjHWks-3jHA670Dxa1A@mail.gmail.com>
 <20191001181438.GL25745@shell.armlinux.org.uk> <CAKwvOdmBnBVU7F-a6DqPU6QM-BRc8LNn6YRmhTsuGLauCWKUOg@mail.gmail.com>
 <CAMuHMdWPhE1nNkmL1nj3vpQhB7fP3uDs2i_ZVi0Gf9qij4W2CA@mail.gmail.com>
 <CAHk-=wgFODvdFBHzgVf3JjoBz0z6LZhOm8xvMntsvOr66ASmZQ@mail.gmail.com>
 <CAK7LNARM2jVSdgCDJWDbvVxYLiUR_CFgTPg0nxzbCszSKcx+pg@mail.gmail.com> <CAHk-=wiMm3rN15WmiAqMHjC-pakL_b8qgWsPPri0+YLFORT-ZA@mail.gmail.com>
In-Reply-To: <CAHk-=wiMm3rN15WmiAqMHjC-pakL_b8qgWsPPri0+YLFORT-ZA@mail.gmail.com>
From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Fri, 4 Oct 2019 02:23:36 +0900
Message-ID: <CAK7LNATSoOD0g=Aarui6Y26E_YB035NsaPpHxqtBNyw0K0UXVw@mail.gmail.com>
Subject: Re: [PATCH] compiler: enable CONFIG_OPTIMIZE_INLINING forcibly
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Russell King - ARM Linux admin <linux@armlinux.org.uk>,
        Will Deacon <will@kernel.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        linux-arch <linux-arch@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Stefan Wahren <wahrenst@gmx.net>,
        Kees Cook <keescook@google.com>, Arnd Bergmann <arnd@arndb.de>,
        clang-built-linux <clang-built-linux@googlegroups.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Oct 4, 2019 at 2:02 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, Oct 2, 2019 at 7:11 PM Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
> >
> > Macrofying the 'inline' is a horrid mistake that makes incorrect code work.
> > It would eternally prevent people from writing portable, correct code.
> > Please do not encourage to hide problems.
>
> Honestly, if the alternative to hiding problems is "use a macro", then
> I'd rather hide the problems and just make "inline" means "inline".
>
> If "inline" means "it's just a hint, use macros", then inline is useless.

For clarification,
I am not saying "use macros" at all.


I just want to annotate __always_inline for the case
"2. code that if not inlined is somehow not correct."


> If "inline" means "using this means that there are known compiler
> bugs, but we don't know where they trigger", then inline is _worse_
> than useless.
>
> I do not see the big advantage of letting the compiler say "yeah, I'm
> not going to do that, Dave".
>
> And I see a *huge* disadvantage when people are ignoring compiler
> bugs, and are saying "use a macro". Seriously.


Again, not saying "use a macro".


>
> Right now we see the obvious compiler bugs that cause build breakages.
> How many non-obvious compiler bugs do we have? And how sure are you
> that our code is "correct" after fixing a couple of obvious cases?
>
> As to "portable", nobody cares. We're a kernel. We aren't portable,
> and never were.
>
> If this is purely about the fact that x86 is different from other
> architectures, then let's remove the "compiler can do stupid things"
> option on x86 too. It was never clear that it was a huge advantage.
>
>                Linus


-- 
Best Regards
Masahiro Yamada