netdev - Re: [PATCH v2 bpf-next 3/7] libbpf: add kprobe/uprobe attach API

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Message-ID: <44d3b02d-b0fb-b0cb-a0d3-e7dd4bde0b92@iogearbox.net>
Date:   Thu, 27 Jun 2019 23:16:55 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Andrii Nakryiko <andriin@...com>, Alexei Starovoitov <ast@...com>,
        Stanislav Fomichev <sdf@...ichev.me>,
        bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v2 bpf-next 3/7] libbpf: add kprobe/uprobe attach API

On 06/27/2019 12:15 AM, Andrii Nakryiko wrote:
> On Wed, Jun 26, 2019 at 7:25 AM Daniel Borkmann <daniel@...earbox.net> wrote:
[...]
>> What this boils down to is that this should get a proper abstraction, e.g. as
>> in struct libbpf_event which holds the event object. There should be helper
>> functions like libbpf_event_create_{kprobe,uprobe,tracepoint,raw_tracepoint} returning
>> such an struct libbpf_event object on success, and a single libbpf_event_destroy()
>> that does the event specific teardown. bpf_program__attach_event() can then take
>> care of only attaching the program to it. Having an object for this is also more
>> extensible than just a fd number. Nice thing is that this can also be completely
>> internal to libbpf.c as with struct bpf_program and other abstractions where we
>> don't expose the internals in the public header.
> 
> Yeah, I totally agree, I think this is a great idea! I don't
> particularly like "event" name, that seems very overloaded term. Do
> you mind if I call this "bpf_hook" instead of "libbpf_event"? I've
> always thought about these different points in the system to which one
> can attach BPF program as hooks exposed from kernel :)
> 
> Would it also make sense to do attaching to non-tracing hooks using
> the same mechanism (e.g., all the per-cgroup stuff, sysctl, etc)? Not
> sure how people do that today, will check to see how it's done, but I
> think nothing should conceptually prevent doing that using the same
> abstract bpf_hook way, right?

I think if we abstract it this way, then absolutely. If I grok the naming conventions
from the README right, then this would be under 'bpf_hook__' prefix. :)

Thanks,
Daniel