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Mon, 29 Jun 2020 18:23:03 +0000 Subject: Re: [PATCH v4 bpf-next 4/4] selftests/bpf: add bpf_iter test with bpf_get_task_stack() To: Song Liu CC: bpf , Networking , open list , Peter Zijlstra , Alexei Starovoitov , Daniel Borkmann , Kernel Team , "john.fastabend@gmail.com" , "kpsingh@chromium.org" References: <20200629055530.3244342-1-songliubraving@fb.com> <20200629055530.3244342-5-songliubraving@fb.com> From: Yonghong Song Message-ID: <30cafbac-723b-c5a2-84aa-b9899d3c8997@fb.com> Date: Mon, 29 Jun 2020 11:22:59 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR05CA0029.namprd05.prod.outlook.com (2603:10b6:a03:c0::42) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2620:10d:c085:21d6::17d3] (2620:10d:c090:400::5:40c) by BYAPR05CA0029.namprd05.prod.outlook.com (2603:10b6:a03:c0::42) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3153.12 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: WL97Ol1JVhWA5Rl/MWw7XdCgGolqMU3ezO3FpNckGZYuOYqKZczdWnvJGlt3oCVbii58s4Y+MC4MBE0A0lmmIyDDE69WjTe7xsMXYYFER28la9rhhpgLlGP3wuSyVQspoQYv4KAlJdbbWhUmSVIeO26AkQfEHcMKJQWuZiek7iEsl+IqJQDpxwzkf+nGca0t8y8sheJK2T8Zv1lvT43ZQqCXBfQrt+0Z/75bjHXwdi8ueNcpmV5bxljpTbr8yS+Kx87LsKiKU8IM/tUa01FjlH2FRSkFFGaT7GpWBJDyt9IJSpn0gB90miE3/NrEfoEhHrw2BV722TpxX4ZUlsra12gWuKJbm329W+QesxhWvDvaWuUMHWZDxfc3G/cZww3Rm8DZbljUYjL6+CaZkeLrTL7Tfe/2ba8zRRJtxBb6c7wgPxWril3uHRg9bLdNNBmn9rlDJF2t4LbTntZosTZbpPe62cp3Us/D0w7xdOw1iZIQiPKTxlsvD4NSs+3nUAt5PGLEURdOWKWUklFglZHlkg== X-MS-Exchange-CrossTenant-Network-Message-Id: c9971c23-f702-4c3f-fba0-08d81c5975c0 X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4088.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jun 2020 18:23:02.9232 (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: 3wvT5m2UsbY9CfFhegA+m9KVGTQoUdjvC8oY1TrF/Iql60ykIUq2enYHOVfZ9BdO X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2376 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-06-29_21:2020-06-29,2020-06-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 cotscore=-2147483648 lowpriorityscore=0 mlxscore=0 clxscore=1015 bulkscore=0 spamscore=0 suspectscore=0 impostorscore=0 priorityscore=1501 adultscore=0 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006290115 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 6/29/20 9:56 AM, Song Liu wrote: > > >> On Jun 29, 2020, at 8:06 AM, Yonghong Song wrote: >> >> >> >> On 6/28/20 10:55 PM, Song Liu wrote: >>> The new test is similar to other bpf_iter tests. It dumps all >>> /proc//stack to a seq_file. Here is some example output: >>> pid: 2873 num_entries: 3 >>> [<0>] worker_thread+0xc6/0x380 >>> [<0>] kthread+0x135/0x150 >>> [<0>] ret_from_fork+0x22/0x30 >>> pid: 2874 num_entries: 9 >>> [<0>] __bpf_get_stack+0x15e/0x250 >>> [<0>] bpf_prog_22a400774977bb30_dump_task_stack+0x4a/0xb3c >>> [<0>] bpf_iter_run_prog+0x81/0x170 >>> [<0>] __task_seq_show+0x58/0x80 >>> [<0>] bpf_seq_read+0x1c3/0x3b0 >>> [<0>] vfs_read+0x9e/0x170 >>> [<0>] ksys_read+0xa7/0xe0 >>> [<0>] do_syscall_64+0x4c/0xa0 >>> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >>> Note: To print the output, it is necessary to modify the selftest. >> >> I do not know what this sentence means. It seems confusing >> and probably not needed. > > It means current do_dummy_read() doesn't check/print the contents of the > seq_file: > > /* not check contents, but ensure read() ends without error */ > while ((len = read(iter_fd, buf, sizeof(buf))) > 0) > ; I see. Thanks. It could be great if the commit message is more explicit about what 'modify' is. >> >>> Signed-off-by: Song Liu >> >> Acked-by: Yonghong Song > > Thanks! > > [...] >