Re: Aarch64 EXT4FS inode checksum failures - seems to be weak memory ordering issues

From: Lukas Wunner <lukas@wunner.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Arnd Bergmann <arnd@kernel.org>,
	Russell King - ARM Linux admin <linux@armlinux.org.uk>,
	linux-toolchains@vger.kernel.org,
	Mark Rutland <mark.rutland@arm.com>,
	Theodore Ts'o <tytso@mit.edu>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: Aarch64 EXT4FS inode checksum failures - seems to be weak memory ordering issues
Date: Tue, 12 Jan 2021 14:20:49 +0100	[thread overview]
Message-ID: <20210112132049.GA26096@wunner.de> (raw)
In-Reply-To: <CAHk-=whnKkj5CSbj-uG_MVVUsPZ6ppd_MFhZf_kpXDkh2MAVRA@mail.gmail.com>

On Fri, Jan 08, 2021 at 12:02:53PM -0800, Linus Torvalds wrote:
> I appreciate Arnd pointing out "--std=gnu11", though. What are the
> actual relevant language improvements?
> 
> Variable declarations in for-loops is the only one I can think of. I
> think that would clean up some code (and some macros), but might not
> be compelling on its own.

Anonymous structs/unions.  I used to have a use case for that in
struct efi_dev_path in include/linux/efi.h, but Ard Biesheuvel
refactored it in a gnu89-compatible way for v5.7 with db8952e7094f.

[The above was copy-pasted from last time this discussion came up
in July 2020.  Back then, Kirill Shutemov likewise mentioned the
local variables in loops feature:
https://lore.kernel.org/lkml/20200710111724.m4jaci73pykalxys@wunner.de/
]

Thanks,

Lukas