netdev - Re: [PATCH bpf-next v2 0/2] load-acquire/store-release barriers for AF

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Message-ID: <87y2f1u2u0.fsf@toke.dk>
Date:   Fri, 05 Mar 2021 14:50:31 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Björn Töpel <bjorn.topel@...il.com>,
        ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        bjorn.topel@...el.com, magnus.karlsson@...el.com,
        jonathan.lemon@...il.com, maximmi@...dia.com, andrii@...nel.org,
        will@...nel.org, paulmck@...nel.org, stern@...land.harvard.edu
Subject: Re: [PATCH bpf-next v2 0/2] load-acquire/store-release barriers for
 AF_XDP rings

Björn Töpel <bjorn.topel@...il.com> writes:

> This two-patch series introduces load-acquire/store-release barriers
> for the AF_XDP rings.
>
> For most contemporary architectures, this is more effective than a
> SPSC ring based on smp_{r,w,}mb() barriers. More importantly,
> load-acquire/store-release semantics make the ring code easier to
> follow.
>
> This is effectively the change done in commit 6c43c091bdc5
> ("documentation: Update circular buffer for
> load-acquire/store-release"), but for the AF_XDP rings.
>
> Both libbpf and the kernel-side are updated.
>
> Full details are outlined in the commits!
>
> Thanks to the LKMM-folks (Paul/Alan/Will) for helping me out in this
> complicated matter!
>
> @Andrii I kept the barriers in libbpf_util.h to separate userfacing
>         APIs (xsk.h) from internals.
>
> @Toke I kept "barriers" but reworded. Acquire/release are also
>       barriers.

Right, that text is better - thanks!

Acked-by: Toke Høiland-Jørgensen <toke@...hat.com>