linux-kernel - Re: [PATCH] btrfs: optimize barrier usage for Rmw atomics

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Message-ID: <25e3abe7-5e86-2180-424a-ceef7402c257@suse.com>
Date:   Wed, 29 Jan 2020 21:07:29 +0200
From:   Nikolay Borisov <nborisov@...e.com>
To:     Davidlohr Bueso <dave@...olabs.net>, dsterba@...e.com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH] btrfs: optimize barrier usage for Rmw atomics



On 29.01.20 г. 20:03 ч., Davidlohr Bueso wrote:
> Use smp_mb__after_atomic() instead of smp_mb() and avoid the
> unnecessary barrier for non LL/SC architectures, such as x86.
> 
> Signed-off-by: Davidlohr Bueso <dbueso@...e.de>


While on the topic of this I've been sitting on the following local
patch for about a year, care to review the barriers:




View attachment "0001-btrfs-Fix-memory-ordering-of-unlocked-dio-reads-vs-t.patch" of type "text/x-patch" (3764 bytes)