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Wed, 13 May 2020 16:57:19 +0000 Subject: Re: [PATCH bpf-next v3 03/21] bpf: support bpf tracing/iter programs for BPF_LINK_CREATE To: Andrii Nakryiko CC: Andrii Nakryiko , bpf , Martin KaFai Lau , Networking , Alexei Starovoitov , Daniel Borkmann , Kernel Team References: <20200507053915.1542140-1-yhs@fb.com> <20200507053918.1542509-1-yhs@fb.com> <849a051d-5c42-a61c-91ef-15a2bdb2b509@fb.com> From: Yonghong Song Message-ID: Date: Wed, 13 May 2020 09:57:16 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR01CA0017.prod.exchangelabs.com (2603:10b6:a02:80::30) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from macbook-pro-52.local.dhcp.thefacebook.com (2620:10d:c090:400::5:86c3) by BYAPR01CA0017.prod.exchangelabs.com (2603:10b6:a02:80::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3000.25 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 5d33f81c-3bd2-4ce6-9988-08d7f75eb2bb X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 May 2020 16:57:19.7537 (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: Wsudg7ZF/QU0/J1znpratJkQy5VAA7O45zlcOZzvzoL8zAmiQLAdXxXZWbSwih9H X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2536 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-13_08:2020-05-13,2020-05-13 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 lowpriorityscore=0 suspectscore=2 phishscore=0 cotscore=-2147483648 mlxscore=0 spamscore=0 malwarescore=0 bulkscore=0 adultscore=0 mlxlogscore=999 clxscore=1015 impostorscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005130148 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 5/11/20 8:15 PM, Andrii Nakryiko wrote: > On Fri, May 8, 2020 at 6:36 PM Yonghong Song wrote: >> >> >> >> On 5/8/20 11:24 AM, Andrii Nakryiko wrote: >>> On Wed, May 6, 2020 at 10:41 PM Yonghong Song wrote: >>>> >>>> Given a bpf program, the step to create an anonymous bpf iterator is: >>>> - create a bpf_iter_link, which combines bpf program and the target. >>>> In the future, there could be more information recorded in the link. >>>> A link_fd will be returned to the user space. >>>> - create an anonymous bpf iterator with the given link_fd. >>>> >>>> The bpf_iter_link can be pinned to bpffs mount file system to >>>> create a file based bpf iterator as well. >>>> >>>> The benefit to use of bpf_iter_link: >>>> - using bpf link simplifies design and implementation as bpf link >>>> is used for other tracing bpf programs. >>>> - for file based bpf iterator, bpf_iter_link provides a standard >>>> way to replace underlying bpf programs. >>>> - for both anonymous and free based iterators, bpf link query >>>> capability can be leveraged. >>>> >>>> The patch added support of tracing/iter programs for BPF_LINK_CREATE. >>>> A new link type BPF_LINK_TYPE_ITER is added to facilitate link >>>> querying. Currently, only prog_id is needed, so there is no >>>> additional in-kernel show_fdinfo() and fill_link_info() hook >>>> is needed for BPF_LINK_TYPE_ITER link. >>>> >>>> Acked-by: Andrii Nakryiko >>>> Signed-off-by: Yonghong Song >>>> --- >>> >>> still looks good, but I realized show_fdinfo and fill_link_info is >>> missing, see request for a follow-up below :) >>> >>> >>>> include/linux/bpf.h | 1 + >>>> include/linux/bpf_types.h | 1 + >>>> include/uapi/linux/bpf.h | 1 + >>>> kernel/bpf/bpf_iter.c | 62 ++++++++++++++++++++++++++++++++++ >>>> kernel/bpf/syscall.c | 14 ++++++++ >>>> tools/include/uapi/linux/bpf.h | 1 + >>>> 6 files changed, 80 insertions(+) >>>> >>> >>> [...] >>> >>>> +static const struct bpf_link_ops bpf_iter_link_lops = { >>>> + .release = bpf_iter_link_release, >>>> + .dealloc = bpf_iter_link_dealloc, >>>> +}; >>> >>> Link infra supports .show_fdinfo and .fill_link_info methods, there is >>> no need to block on this, but it would be great to implement them from >>> BPF_LINK_TYPE_ITER as well in the same release as a follow-up. Thanks! >> >> The reason I did not implement is due to we do not have additional >> information beyond prog_id to present. The prog_id itself gives all >> information about this link. I looked at tracing program > > Not all, e.g., bpf_iter target is invisible right now. It's good to > have this added in a follow up, but certainly not a blocker. Indeed, bpf_iter target is not visible now. We can add it to program or to link. Adding to link is a reasonable idea as link itself is the concept to merge program and target. Will have a follow up patch for this later. > > >> show_fdinfo/fill_link_info, the additional attach_type is printed. >> But attach_type is obvious for BPF_LINK_TYPE_ITER which does not >> need print. >> >> In the future when we add more stuff to parameterize the bpf_iter, >> will need to implement these two callbacks as well as bpftool. > > yep > >> >>> >>> >>> [...] >>>