linux-kernel - Re: [PATCH] posix_acl: Use try_cmpxchg in get

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Message-ID: <20221223104724.uurfko6bqzpjv5n5@wittgenstein>
Date:   Fri, 23 Dec 2022 11:47:24 +0100
From:   Christian Brauner <brauner@...nel.org>
To:     Uros Bizjak <ubizjak@...il.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] posix_acl: Use try_cmpxchg in get_acl

On Wed, Dec 21, 2022 at 08:35:40PM +0100, Uros Bizjak wrote:
> Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old
> in get_acl. x86 CMPXCHG instruction returns success in ZF flag,
> so this change saves a compare after cmpxchg (and related move
> instruction in front of cmpxchg).
> 
> No functional change intended.
> 
> Signed-off-by: Uros Bizjak <ubizjak@...il.com>
> Cc: Christian Brauner <brauner@...nel.org>
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> ---

Looks ok to me. But it's not urgent so I'll circle back to this post
-rc1.

Thanks!
Christian