From: Martin Lau <kafai@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
David Miller <davem@davemloft.net>,
"Kernel Team" <Kernel-team@fb.com>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next v2 11/11] bpf: Add bpf_dctcp example
Date: Tue, 24 Dec 2019 16:50:07 +0000 [thread overview]
Message-ID: <20191224165003.oi4kvxad6mlsg5kw@kafai-mbp> (raw)
In-Reply-To: <CAEf4Bzb2fRZJsccx2CG_pASy+2eMMWPXk6m3d6SbN+o0MSdQPg@mail.gmail.com>
On Mon, Dec 23, 2019 at 11:01:55PM -0800, Andrii Nakryiko wrote:
> On Mon, Dec 23, 2019 at 5:31 PM Martin Lau <kafai@fb.com> wrote:
> >
> > On Mon, Dec 23, 2019 at 03:26:50PM -0800, Andrii Nakryiko wrote:
> > > On Fri, Dec 20, 2019 at 10:26 PM Martin KaFai Lau <kafai@fb.com> wrote:
> > > >
> > > > This patch adds a bpf_dctcp example. It currently does not do
> > > > no-ECN fallback but the same could be done through the cgrp2-bpf.
> > > >
> > > > Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> > > > ---
> > > > tools/testing/selftests/bpf/bpf_tcp_helpers.h | 228 ++++++++++++++++++
> > > > .../selftests/bpf/prog_tests/bpf_tcp_ca.c | 218 +++++++++++++++++
> > > > tools/testing/selftests/bpf/progs/bpf_dctcp.c | 210 ++++++++++++++++
> > > > 3 files changed, 656 insertions(+)
> > > > create mode 100644 tools/testing/selftests/bpf/bpf_tcp_helpers.h
> > > > create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
> > > > create mode 100644 tools/testing/selftests/bpf/progs/bpf_dctcp.c
> > > >
> > > > diff --git a/tools/testing/selftests/bpf/bpf_tcp_helpers.h b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
> > > > new file mode 100644
> > > > index 000000000000..7ba8c1b4157a
> > > > --- /dev/null
> > > > +++ b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
> > > > @@ -0,0 +1,228 @@
> > > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > > +#ifndef __BPF_TCP_HELPERS_H
> > > > +#define __BPF_TCP_HELPERS_H
> > > > +
> > > > +#include <stdbool.h>
> > > > +#include <linux/types.h>
> > > > +#include <bpf_helpers.h>
> > > > +#include <bpf_core_read.h>
> > > > +#include "bpf_trace_helpers.h"
> > > > +
> > > > +#define BPF_TCP_OPS_0(fname, ret_type, ...) BPF_TRACE_x(0, #fname"_sec", fname, ret_type, __VA_ARGS__)
> > > > +#define BPF_TCP_OPS_1(fname, ret_type, ...) BPF_TRACE_x(1, #fname"_sec", fname, ret_type, __VA_ARGS__)
> > > > +#define BPF_TCP_OPS_2(fname, ret_type, ...) BPF_TRACE_x(2, #fname"_sec", fname, ret_type, __VA_ARGS__)
> > > > +#define BPF_TCP_OPS_3(fname, ret_type, ...) BPF_TRACE_x(3, #fname"_sec", fname, ret_type, __VA_ARGS__)
> > > > +#define BPF_TCP_OPS_4(fname, ret_type, ...) BPF_TRACE_x(4, #fname"_sec", fname, ret_type, __VA_ARGS__)
> > > > +#define BPF_TCP_OPS_5(fname, ret_type, ...) BPF_TRACE_x(5, #fname"_sec", fname, ret_type, __VA_ARGS__)
> > >
> > > Should we try to put those BPF programs into some section that would
> > > indicate they are used with struct opts? libbpf doesn't use or enforce
> > > that (even though it could to derive and enforce that they are
> > > STRUCT_OPS programs). So something like
> > > SEC("struct_ops/<ideally-operation-name-here>"). I think having this
> > > convention is very useful for consistency and to do a quick ELF dump
> > > and see what is where. WDYT?
> > I did not use it here because I don't want any misperception that it is
> > a required convention by libbpf.
> >
> > Sure, I can prefix it here and comment that it is just a
> > convention but not a libbpf's requirement.
>
> Well, we can actually make it a requirement of sorts. Currently your
> code expects that BPF program's type is UNSPEC and then it sets it to
> STRUCT_OPS. Alternatively we can say that any BPF program in
> SEC("struct_ops/<whatever>") will be automatically assigned
> STRUCT_OPTS BPF program type (which is done generically in
> bpf_object__open()), and then as .struct_ops section is parsed, all
> those programs will be "assembled" by the code you added into a
> struct_ops map.
Setting BPF_PROG_TYPE_STRUCT_OPS can be done automatically at open
phase (during collect_reloc time). I will make this change.
>
> It's a requirement "of sorts", because even if user doesn't do that,
> stuff will still work, if user manually will call
> bpf_program__set_struct_ops(prog). Which actually reminds me that it
> would be good to add bpf_program__set_struct_ops() and
Although there is BPF_PROG_TYPE_FNS macro,
I don't see moving bpf_prog__set_struct_ops(prog) to LIBBPF_API is useful
while actually may cause confusion and error. How could __set_struct_ops()
a prog to struct_ops prog_type help a program, which is not used in
SEC(".struct_ops"), to be loaded successfully as a struct_ops prog?
Assigning a bpf_prog to a function ptr under the SEC(".struct_ops")
is the only way for a program to be successfully loaded as
struct_ops prog type. Extra way to allow a prog to be changed to
struct_ops prog_type is either useless or redundant.
If it is really necessary to have __set_struct_ops() as a API
for completeness, it can be added...
> bpf_program__is_struct_ops() APIs for completeness, similarly to how
is_struct_ops() makes sense.
> BTW, libbpf will emit debug message for every single BPF program it
> doesn't recognize section for, so it is still nice to have it be
> something more or less standardized and recognizable by libbpf.
I can make this debug (not error) message go away too after
setting the BPF_PROG_TYPE_STRUCT_OPS automatically at open time.
next prev parent reply other threads:[~2019-12-24 16:50 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-21 6:25 [PATCH bpf-next v2 00/11] Introduce BPF STRUCT_OPS Martin KaFai Lau
2019-12-21 6:25 ` [PATCH bpf-next v2 01/11] bpf: Save PTR_TO_BTF_ID register state when spilling to stack Martin KaFai Lau
2019-12-21 6:25 ` [PATCH bpf-next v2 02/11] bpf: Avoid storing modifier to info->btf_id Martin KaFai Lau
2019-12-21 6:26 ` [PATCH bpf-next v2 03/11] bpf: Add enum support to btf_ctx_access() Martin KaFai Lau
2019-12-21 6:26 ` [PATCH bpf-next v2 04/11] bpf: Support bitfield read access in btf_struct_access Martin KaFai Lau
2019-12-23 7:49 ` Yonghong Song
2019-12-23 20:05 ` Andrii Nakryiko
2019-12-23 21:21 ` Yonghong Song
2019-12-21 6:26 ` [PATCH bpf-next v2 05/11] bpf: Introduce BPF_PROG_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-23 19:33 ` Yonghong Song
2019-12-23 20:29 ` Andrii Nakryiko
2019-12-23 22:29 ` Martin Lau
2019-12-23 22:55 ` Andrii Nakryiko
2019-12-24 11:46 ` kbuild test robot
2019-12-21 6:26 ` [PATCH bpf-next v2 06/11] bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-23 19:57 ` Yonghong Song
2019-12-23 21:44 ` Andrii Nakryiko
2019-12-23 22:15 ` Martin Lau
2019-12-27 6:16 ` Martin Lau
2019-12-23 23:05 ` Andrii Nakryiko
2019-12-28 1:47 ` Martin Lau
2019-12-28 2:24 ` Andrii Nakryiko
2019-12-28 5:16 ` Martin Lau
2019-12-24 12:28 ` kbuild test robot
2019-12-21 6:26 ` [PATCH bpf-next v2 07/11] bpf: tcp: Support tcp_congestion_ops in bpf Martin KaFai Lau
2019-12-23 20:18 ` Yonghong Song
2019-12-23 23:20 ` Andrii Nakryiko
2019-12-24 7:16 ` kbuild test robot
2019-12-24 13:06 ` kbuild test robot
2019-12-21 6:26 ` [PATCH bpf-next v2 08/11] bpf: Add BPF_FUNC_tcp_send_ack helper Martin KaFai Lau
2019-12-21 6:26 ` [PATCH bpf-next v2 09/11] bpf: Synch uapi bpf.h to tools/ Martin KaFai Lau
2019-12-21 6:26 ` [PATCH bpf-next v2 10/11] bpf: libbpf: Add STRUCT_OPS support Martin KaFai Lau
2019-12-23 19:54 ` Andrii Nakryiko
2019-12-26 22:47 ` Martin Lau
2019-12-21 6:26 ` [PATCH bpf-next v2 11/11] bpf: Add bpf_dctcp example Martin KaFai Lau
2019-12-23 23:26 ` Andrii Nakryiko
2019-12-24 1:31 ` Martin Lau
2019-12-24 7:01 ` Andrii Nakryiko
2019-12-24 7:32 ` Martin Lau
2019-12-24 16:50 ` Martin Lau [this message]
2019-12-26 19:02 ` Andrii Nakryiko
2019-12-26 20:25 ` Martin Lau
2019-12-26 20:48 ` Andrii Nakryiko
2019-12-26 22:20 ` Martin Lau
2019-12-26 22:25 ` Andrii Nakryiko
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