netdev - Re: [PATCH] xdp: auto off xdp by bond fd

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Date:   Fri, 6 Nov 2020 09:22:14 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc:     Netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>
Subject: Re: [PATCH] xdp: auto off xdp by bond fd

On Fri, 6 Nov 2020 at 08:41, Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> By default, off xdp is implemented by actively calling netlink on the
> command line or in the program. This is very inconvenient for apps based
> on xdp. For example, an app based on xdp + xsk exits abnormally, but xdp
> is still working, which may cause some exceptions. And xsk cannot be
> automatically recycled. We need to bind xdp to the process in some
> cases, so that xdp can always be automatically released when the process exits.
>
> Although the signal can be used to handle this problem, it cannot handle
> some signals that cannot be captured. At the same time, it is
> inconvenient to use the signal to process in some cases. For example, a
> library based on xdp + xsk is not very convenient to use the signal solve
> this problem.
>
> This patch requires the app to actively call RTM_GETLINK after setting
> xdp and use RTEXT_FILTER_XDPFD flags to let the kernel generate an fd,
> and return it to the app through netlink. In this way, when the app
> closes fd or the process exits, the release callback of fd can trigger
> to off xdp.
>

Hi Xuan,

You'd like a "process scoped XDP attachment", right? I believe the
mechanism you're looking for is Andrii's bpf_link. Have look at commit
aa8d3a716b59 ("bpf, xdp: Add bpf_link-based XDP attachment API").


Cheers,
Björn