netdev - Re: [PATCH v2 bpf-next 0/3] Introduce pinnable bpf

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Date:   Mon, 2 Mar 2020 22:15:16 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Andrii Nakryiko <andriin@...com>
Cc:     bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v2 bpf-next 0/3] Introduce pinnable bpf_link kernel abstraction

On Mon, Mar 2, 2020 at 8:32 PM Andrii Nakryiko <andriin@...com> wrote:
>
> This patch series adds bpf_link abstraction, analogous to libbpf's already
> existing bpf_link abstraction. This formalizes and makes more uniform existing
> bpf_link-like BPF program link (attachment) types (raw tracepoint and tracing
> links), which are FD-based objects that are automatically detached when last
> file reference is closed. These types of BPF program links are switched to
> using bpf_link framework.
>
> FD-based bpf_link approach provides great safety guarantees, by ensuring there
> is not going to be an abandoned BPF program attached, if user process suddenly
> exits or forgets to clean up after itself. This is especially important in
> production environment and is what all the recent new BPF link types followed.
>
> One of the previously existing  inconveniences of FD-based approach, though,
> was the scenario in which user process wants to install BPF link and exit, but
> let attached BPF program run. Now, with bpf_link abstraction in place, it's
> easy to support pinning links in BPF FS, which is done as part of the same
> patch #1. This allows FD-based BPF program links to survive exit of a user
> process and original file descriptor being closed, by creating an file entry
> in BPF FS. This provides great safety by default, with simple way to opt out
> for cases where it's needed.
>
> Corresponding libbpf APIs are added in the same patch set, as well as
> selftests for this functionality.
>
> Other types of BPF program attachments (XDP, cgroup, perf_event, etc) are
> going to be converted in subsequent patches to follow similar approach.

Applied. Thanks.