From: Artem Savkov <asavkov@redhat.com>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Song Liu <song@kernel.org>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, martin.lau@linux.dev, yonghong.song@linux.dev,
dan.carpenter@linaro.org, olsajiri@gmail.com
Subject: Re: [PATCH bpf-next v4 1/3] bpf: Relax tracing prog recursive attach rules
Date: Fri, 1 Dec 2023 10:55:09 +0100 [thread overview]
Message-ID: <ZWmtfZlTq2hBn5zp@wtfbox.lan> (raw)
In-Reply-To: <20231130204134.4i4tloaylxrkrnrt@erthalion.local>
On Thu, Nov 30, 2023 at 09:41:34PM +0100, Dmitry Dolgov wrote:
> > On Thu, Nov 30, 2023 at 12:19:31PM -0800, Song Liu wrote:
> > > All in all I've decided that more elaborated approach is slightly
> > > better. But if everyone in the community agrees that less
> > > "defensiveness" is not an issue and verifier could be simply made less
> > > restrictive, I'm fine with that. What do you think?
> >
> > I think the follower_cnt check is not necessary, and may cause confusions.
> > For tracing programs, we are very specific on "which function(s) are we
> > tracing". So I don't think circular attachment can be a real issue. Do we
> > have potential use cases that make the circular attach possible?
>
> At the moment no, nothing like that in sight. Ok, you've convinced me --
> plus since nobody has yet actively mentioned that potential cycle
> prevention is nice to have, I can drop follower_cnt and the
> corresponding check in the verifier.
If you are worried about potential future situations where cyclic
attaches are possible would it make sense to add a test that checks if
this fails?
--
Regards,
Artem
next prev parent reply other threads:[~2023-12-01 9:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-29 19:52 [PATCH bpf-next v4 0/3] Relax tracing prog recursive attach rules Dmitrii Dolgov
2023-11-29 19:52 ` [PATCH bpf-next v4 1/3] bpf: " Dmitrii Dolgov
2023-11-29 23:58 ` Song Liu
2023-11-30 10:08 ` Dmitry Dolgov
2023-11-30 20:19 ` Song Liu
2023-11-30 20:41 ` Dmitry Dolgov
2023-12-01 9:55 ` Artem Savkov [this message]
2023-12-01 14:29 ` Dmitry Dolgov
2023-11-30 14:30 ` Jiri Olsa
2023-11-30 18:57 ` Dmitry Dolgov
2023-11-30 22:34 ` Jiri Olsa
2023-11-29 19:52 ` [PATCH bpf-next v4 2/3] selftests/bpf: Add test for recursive attachment of tracing progs Dmitrii Dolgov
2023-11-30 14:47 ` Jiri Olsa
2023-11-29 19:52 ` [PATCH bpf-next v4 3/3] bpf, selftest/bpf: Fix re-attachment branch in bpf_tracing_prog_attach Dmitrii Dolgov
2023-11-30 15:14 ` Jiri Olsa
2023-11-30 22:30 ` Jiri Olsa
2023-12-01 14:21 ` Dmitry Dolgov
2023-12-01 14:52 ` Jiri Olsa
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