Re: [RFC bpf-next 0/3] libbpf: name-based u[ret]probe attach

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alan Maguire <alan.maguire@oracle.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@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@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Yucong Sun <sunyucong@gmail.com>,
	Network Development <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>
Subject: Re: [RFC bpf-next 0/3] libbpf: name-based u[ret]probe attach
Date: Fri, 21 Jan 2022 10:27:04 -0800	[thread overview]
Message-ID: <CAEf4BzYPncQpbjbyh9XA4qdMqerWtcfgaMEiQYmdXcby+wUnXQ@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQL0nq_jHY7Js3FN2bFBy4eo-7=4cfurkt5xQmU_yJGCvA@mail.gmail.com>

On Fri, Jan 21, 2022 at 10:20 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Fri, Jan 21, 2022 at 10:15 AM Andrii Nakryiko
> <andrii.nakryiko@gmail.com> wrote:
> >
> > On Thu, Jan 20, 2022 at 5:44 PM Alexei Starovoitov
> > <alexei.starovoitov@gmail.com> wrote:
> > >
> > > On Thu, Jan 20, 2022 at 3:43 AM Alan Maguire <alan.maguire@oracle.com> wrote:
> > > >
> > > > This patch series is a refinement of the RFC patchset [1], focusing
> > > > on support for attach by name for uprobes and uretprobes.  Still
> > > > marked RFC as there are unresolved questions.
> > > >
> > > > Currently attach for such probes is done by determining the offset
> > > > manually, so the aim is to try and mimic the simplicity of kprobe
> > > > attach, making use of uprobe opts to specify a name string.
> > > >
> > > > uprobe attach is done by specifying a binary path, a pid (where
> > > > 0 means "this process" and -1 means "all processes") and an
> > > > offset.  Here a 'func_name' option is added to 'struct uprobe_opts'
> > > > and that name is searched for in symbol tables.  If the binary
> > > > is a program, relative offset calcuation must be done to the
> > > > symbol address as described in [2].
> > >
> > > I think the pid discussion here and in the patches only causes
> > > confusion. I think it's best to remove pid from the api.
> >
> > It's already part of the uprobe API in libbpf
> > (bpf_program__attach_uprobe), but nothing really changes there.
> > API-wise Alan just added an optional func_name option. I think it
> > makes sense overall.
>
> Technically it can be deprecated.
> So "it's already part of api" isn't really an excuse to keep
> confusing the users.

... but I don't find it confusing and no one really ever complained?..
So it doesn't seem like we need to remove this.