From: Jiri Olsa <jolsa@redhat.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>
Subject: Re: [RFC PATCH bpf-next 1/4] bpf: Allow trampoline re-attach
Date: Mon, 5 Apr 2021 23:58:25 +0200 [thread overview]
Message-ID: <YGuIAWA4kRJCfI4U@krava> (raw)
In-Reply-To: <87ft04rf51.fsf@toke.dk>
On Mon, Apr 05, 2021 at 04:15:54PM +0200, Toke Høiland-Jørgensen wrote:
> Jiri Olsa <jolsa@redhat.com> writes:
>
> > On Sat, Apr 03, 2021 at 11:21:55AM -0700, Alexei Starovoitov wrote:
> >> On Sat, Apr 03, 2021 at 01:24:12PM +0200, Toke Høiland-Jørgensen wrote:
> >> > > if (!prog->aux->dst_trampoline && !tgt_prog) {
> >> > > - err = -ENOENT;
> >> > > - goto out_unlock;
> >> > > + /*
> >> > > + * Allow re-attach for tracing programs, if it's currently
> >> > > + * linked, bpf_trampoline_link_prog will fail.
> >> > > + */
> >> > > + if (prog->type != BPF_PROG_TYPE_TRACING) {
> >> > > + err = -ENOENT;
> >> > > + goto out_unlock;
> >> > > + }
> >> > > + if (!prog->aux->attach_btf) {
> >> > > + err = -EINVAL;
> >> > > + goto out_unlock;
> >> > > + }
> >> >
> >> > I'm wondering about the two different return codes here. Under what
> >> > circumstances will aux->attach_btf be NULL, and why is that not an
> >> > ENOENT error? :)
> >>
> >> The feature makes sense to me as well.
> >> I don't quite see how it would get here with attach_btf == NULL.
> >> Maybe WARN_ON then?
> >
> > right, that should be always there
> >
> >> Also if we're allowing re-attach this way why exclude PROG_EXT and LSM?
> >>
> >
> > I was enabling just what I needed for the test, which is so far
> > the only use case.. I'll see if I can enable that for all of them
>
> How would that work? For PROG_EXT we clear the destination on the first
> attach (to avoid keeping a ref on it), so re-attach can only be done
> with an explicit target (which already works just fine)...
right, I'm just looking on it ;-) extensions already seem allow for that,
I'll check LSM
jirka
next prev parent reply other threads:[~2021-04-05 21:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-28 11:26 [RFC PATCH bpf-next 0/4] bpf: Tracing programs re-attach Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 1/4] bpf: Allow trampoline re-attach Jiri Olsa
2021-03-30 1:18 ` Song Liu
2021-04-03 11:24 ` Toke Høiland-Jørgensen
2021-04-03 18:21 ` Alexei Starovoitov
2021-04-05 14:08 ` Jiri Olsa
2021-04-05 14:15 ` Toke Høiland-Jørgensen
2021-04-05 21:58 ` Jiri Olsa [this message]
2021-04-05 14:06 ` Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 2/4] selftests/bpf: Add re-attach test to fentry_test Jiri Olsa
2021-03-30 1:23 ` Song Liu
2021-03-30 20:02 ` Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 3/4] selftests/bpf: Add re-attach test to fexit_test Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 4/4] selftests/bpf: Test that module can't be unloaded with attached trampoline Jiri Olsa
2021-03-30 6:12 ` Song Liu
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