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Wed, 5 Aug 2020 03:59:13 +0000 From: Song Liu To: Andrii Nakryiko CC: open list , bpf , Networking , Alexei Starovoitov , Daniel Borkmann , Kernel Team , john fastabend , KP Singh , Jesper Dangaard Brouer , Daniel Xu Subject: Re: [PATCH bpf-next 2/5] libbpf: support BPF_PROG_TYPE_USER programs Thread-Topic: [PATCH bpf-next 2/5] libbpf: support BPF_PROG_TYPE_USER programs Thread-Index: AQHWZ+C4tQwFkmvi20aNhPcONSrEz6klnl6AgAGMFwCAAZgFAIAAJ1IA Date: Wed, 5 Aug 2020 03:59:13 +0000 Message-ID: <5BC1D7AD-32C1-4CDC-BA99-F4DABE61EEA3@fb.com> References: <20200801084721.1812607-1-songliubraving@fb.com> <20200801084721.1812607-3-songliubraving@fb.com> <9C1285C1-ECD6-46BD-BA95-3E9E81C00EF0@fb.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.80.23.2.2) authentication-results: gmail.com; dkim=none (message not signed) header.d=none;gmail.com; dmarc=none action=none header.from=fb.com; x-originating-ip: [2620:10d:c090:400::5:8f7] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 364af8d9-ee68-4070-9d2e-08d838f3ea71 x-ms-traffictypediagnostic: BYAPR15MB3304: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-fb-source: Internal x-ms-oob-tlc-oobclassifiers: OLM:6108; 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charset="us-ascii" Content-ID: <807257139EBEDF4199E1EB2BD2128796@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB2999.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 364af8d9-ee68-4070-9d2e-08d838f3ea71 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Aug 2020 03:59:13.4108 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: iSUCFO2Mwd1tGr30BctY4CGlhacpNIu8izloVbatHErLI71NcivvSkOmDYs00R/V2uHGWMthUpl1lhLedf+S8A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB3304 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-05_03:2020-08-03,2020-08-05 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 phishscore=0 priorityscore=1501 mlxlogscore=999 bulkscore=0 suspectscore=0 impostorscore=0 adultscore=0 clxscore=1015 mlxscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008050035 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Aug 4, 2020, at 6:38 PM, Andrii Nakryiko w= rote: >=20 > On Mon, Aug 3, 2020 at 6:18 PM Song Liu wrote: >>=20 >>=20 >>=20 >>> On Aug 2, 2020, at 6:40 PM, Andrii Nakryiko = wrote: >>>=20 >>> On Sat, Aug 1, 2020 at 1:50 AM Song Liu wrote: >>>>=20 >>=20 >> [...] >>=20 >>>=20 >>>> }; >>>>=20 >>>> LIBBPF_API int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *= test_attr); >>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >>>> index b9f11f854985b..9ce175a486214 100644 >>>> --- a/tools/lib/bpf/libbpf.c >>>> +++ b/tools/lib/bpf/libbpf.c >>>> @@ -6922,6 +6922,7 @@ static const struct bpf_sec_def section_defs[] = =3D { >>>> BPF_PROG_SEC("lwt_out", BPF_PROG_TYPE_LWT_OUT), >>>> BPF_PROG_SEC("lwt_xmit", BPF_PROG_TYPE_LWT_XMIT), >>>> BPF_PROG_SEC("lwt_seg6local", BPF_PROG_TYPE_LWT_SEG6LO= CAL), >>>> + BPF_PROG_SEC("user", BPF_PROG_TYPE_USER), >>>=20 >>> let's do "user/" for consistency with most other prog types (and nice >>> separation between prog type and custom user name) >>=20 >> About "user" vs. "user/", I still think "user" is better. >>=20 >> Unlike kprobe and tracepoint, user prog doesn't use the part after "/". >> This is similar to "perf_event" for BPF_PROG_TYPE_PERF_EVENT, "xdl" for >> BPF_PROG_TYPE_XDP, etc. If we specify "user" here, "user/" and "user/xxx= " >> would also work. However, if we specify "user/" here, programs that used >> "user" by accident will fail to load, with a message like: >>=20 >> libbpf: failed to load program 'user' >>=20 >> which is confusing. >=20 > xdp, perf_event and a bunch of others don't enforce it, that's true, > they are a bit of a legacy, I don't see w/o "/" is a legacy thing. BPF_PROG_TYPE_STRUCT_OPS just uses "struct_ops".=20 > unfortunately. But all the recent ones do, > and we explicitly did that for xdp_dev/xdp_cpu, for instance. > Specifying just "user" in the spec would allow something nonsensical > like "userargh", for instance, due to this being treated as a prefix. > There is no harm to require users to do "user/my_prog", though. I don't see why allowing "userargh" is a problem. Failing "user" is=20 more confusing. We can probably improve that by a hint like: libbpf: failed to load program 'user', do you mean "user/"? But it is pretty silly. "user/something_never_used" also looks weird. > Alternatively, we could introduce a new convention in the spec, > something like "user?", which would accept either "user" or > "user/something", but not "user/" nor "userblah". We can try that as > well. Again, I don't really understand why allowing "userblah" is a problem.=20 We already have "xdp", "xdp_devmap/", and "xdp_cpumap/", they all work=20 fine so far.=20 Thanks, Song=