From: Ingo Molnar <mingo@kernel.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"David S. Miller" <davem@davemloft.net>,
Ard Biesheuvel <ardb@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
llvm@lists.linux.dev
Subject: Re: [PATCH] headers/deps: dcache: Move the ____cacheline_aligned attribute to the head of the definition
Date: Wed, 5 Jan 2022 01:20:32 +0100 [thread overview]
Message-ID: <YdTkUBSLCQv7++FN@gmail.com> (raw)
In-Reply-To: <YdSJH7empIUq9vbE@archlinux-ax161>
* Nathan Chancellor <nathan@kernel.org> wrote:
> Nowhere does it mention that it accepts the attribute before the type
> keyword and neither compiler respects the attribute if it comes before
> the keyword but at least clang warns: https://godbolt.org/z/E9fTecKPv
>
> $ cat test.c
> #include <stdio.h>
>
> struct foo {
> int a;
> int b;
> };
>
> struct __attribute__ ((aligned (64))) bar {
> int a;
> int b;
> };
>
> __attribute__ ((aligned (64))) struct baz {
> int a;
> int b;
> };
>
> int main(void)
> {
> printf("struct foo alignment: %zd\n", _Alignof(struct foo));
> printf("struct bar alignment: %zd\n", _Alignof(struct bar));
> printf("struct baz alignment: %zd\n", _Alignof(struct baz));
> return 0;
> }
>
> $ gcc --version | head -1
> gcc (GCC) 11.2.1 20211231
>
> $ gcc -std=gnu89 -Wall -Wextra test.c; and ./a.out
> struct foo alignment: 4
> struct bar alignment: 64
> struct baz alignment: 4
Ugh - so my changes there are outright buggy.
I'm reverting all those attribute position changes as we speak ...
I'm actually happy about this in a way, as it settles the issue nicely. :-)
Thanks,
Ingo
next prev parent reply other threads:[~2022-01-05 0:20 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-02 21:57 [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-03 10:11 ` Greg Kroah-Hartman
2022-01-03 11:12 ` Ingo Molnar
2022-01-03 13:46 ` Greg Kroah-Hartman
2022-01-03 16:29 ` Ingo Molnar
2022-01-10 10:28 ` Peter Zijlstra
2022-01-04 14:10 ` [PATCH] per_task: Remove the PER_TASK_BYTES hard-coded constant Ingo Molnar
2022-01-04 15:14 ` Andy Shevchenko
2022-01-04 23:27 ` Ingo Molnar
2022-01-04 17:51 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Arnd Bergmann
2022-01-05 0:05 ` Ingo Molnar
2022-01-05 1:37 ` Arnd Bergmann
2022-01-05 9:37 ` Andy Shevchenko
2022-01-04 14:05 ` [PATCH] per_task: Implement single template to define 'struct task_struct_per_task' fields and offsets Ingo Molnar
2022-01-03 13:54 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Kirill A. Shutemov
2022-01-04 10:54 ` Ingo Molnar
2022-01-04 13:34 ` Greg Kroah-Hartman
2022-01-04 13:54 ` [PATCH] headers/uninline: Uninline single-use function: kobject_has_children() Ingo Molnar
2022-01-04 15:09 ` Greg Kroah-Hartman
2022-01-04 15:14 ` Greg Kroah-Hartman
2022-01-05 0:11 ` Ingo Molnar
2022-01-05 15:23 ` Greg Kroah-Hartman
2022-01-06 11:26 ` Ingo Molnar
2022-01-03 17:54 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nathan Chancellor
2022-01-04 10:47 ` Ingo Molnar
2022-01-04 10:56 ` [DEBUG PATCH] DO NOT MERGE: Enable SHADOW_CALL_STACK on GCC builds, for build testing Ingo Molnar
2022-01-04 11:02 ` [PATCH] headers/deps: dcache: Move the ____cacheline_aligned attribute to the head of the definition Ingo Molnar
2022-01-04 15:05 ` kernel test robot
2022-01-04 17:51 ` Nathan Chancellor
2022-01-05 0:20 ` Ingo Molnar [this message]
2022-01-05 0:26 ` [PATCH] headers/deps: Attribute placement fixes for Clang & GCC Ingo Molnar
2022-01-04 11:19 ` [TREE] "Fast Kernel Headers" Tree WIP/development branch Ingo Molnar
2022-01-04 17:25 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nick Desaulniers
2022-01-05 0:43 ` Ingo Molnar
2022-01-04 17:50 ` Nathan Chancellor
2022-01-05 0:35 ` [PATCH] x86/kbuild: Enable CONFIG_KALLSYMS_ALL=y in the defconfigs Ingo Molnar
2022-01-08 21:57 ` [tip: x86/build] " tip-bot2 for Ingo Molnar
2022-01-05 0:40 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-05 1:07 ` Ingo Molnar
2022-01-05 5:20 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel'\''s "Dependency Hell Paul Zimmerman
2022-01-05 21:42 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nathan Chancellor
2022-01-08 10:32 ` [PATCH] headers/deps: Add header dependencies to .c files: <linux/ptrace_api.h> Ingo Molnar
2022-01-08 11:08 ` [PATCH] FIX: headers/deps: uapi/headers: Create usr/include/uapi symbolic link Ingo Molnar
2022-01-08 11:18 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-08 11:38 ` [PATCH] x86/bitops: Remove unused __sw_hweight64() assembly implementation Ingo Molnar
2022-01-08 11:49 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-08 12:17 ` Ingo Molnar
2022-01-10 20:03 ` Nathan Chancellor
2022-01-10 20:05 ` Nathan Chancellor
2022-01-05 22:33 ` Nathan Chancellor
2022-01-08 15:16 ` Ingo Molnar
2022-01-07 0:29 ` Nathan Chancellor
2022-01-08 11:54 ` Ingo Molnar
2022-01-04 12:36 ` Willy Tarreau
2022-01-04 16:05 ` Andy Shevchenko
2022-01-04 16:18 ` Andy Shevchenko
2022-01-15 0:42 ` Paul E. McKenney
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