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[209.85.208.181]) by smtp.gmail.com with ESMTPSA id n133sm467360lfd.152.2021.01.12.09.28.48 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Jan 2021 09:28:48 -0800 (PST) Received: by mail-lj1-f181.google.com with SMTP id w26so3746317ljo.4 for ; Tue, 12 Jan 2021 09:28:48 -0800 (PST) X-Received: by 2002:a2e:9d89:: with SMTP id c9mr149709ljj.220.1610472527992; Tue, 12 Jan 2021 09:28:47 -0800 (PST) MIME-Version: 1.0 References: <20210106172033.GA2165@willie-the-truck> <20210106223223.GM1551@shell.armlinux.org.uk> <20210107111841.GN1551@shell.armlinux.org.uk> <20210107124506.GO1551@shell.armlinux.org.uk> <20210107133747.GP1551@shell.armlinux.org.uk> <20210108092655.GA4031@willie-the-truck> <20210112132049.GA26096@wunner.de> In-Reply-To: <20210112132049.GA26096@wunner.de> From: Linus Torvalds Date: Tue, 12 Jan 2021 09:28:32 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Aarch64 EXT4FS inode checksum failures - seems to be weak memory ordering issues To: Lukas Wunner Cc: Will Deacon , Peter Zijlstra , Arnd Bergmann , Russell King - ARM Linux admin , linux-toolchains@vger.kernel.org, Mark Rutland , "Theodore Ts'o" , "linux-kernel@vger.kernel.org" , Andreas Dilger , Ext4 Developers List , Linux ARM Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 12, 2021 at 5:20 AM Lukas Wunner wrote: > > > 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. We use anonymous structs/unions extensively and all over the place already. We've had a couple of special cases where some versions of gcc didn't do things right iirc (it was something like "nested anonymous struct" or similar), but those weren't actually about the feature itself. Was it perhaps the nested case you were thinking of? If so, I think that's not really a --std=gun11 thing, it's more of a "certain versions of gcc didn't do it at all". Linus