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Thu, 14 May 2020 17:42:39 +0000 Date: Thu, 14 May 2020 10:42:38 -0700 From: Andrey Ignatov To: Yonghong Song CC: , , , Subject: Re: [PATCH v2 bpf-next 4/5] selftests/bpf: Add connect_fd_to_fd, connect_wait net helpers Message-ID: <20200514174238.GB22366@rdna-mbp> References: <3f5d4625-32ee-7739-ccfb-53c19e38778b@fb.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <3f5d4625-32ee-7739-ccfb-53c19e38778b@fb.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-ClientProxiedBy: BYAPR07CA0106.namprd07.prod.outlook.com (2603:10b6:a03:12b::47) To BYAPR15MB4119.namprd15.prod.outlook.com (2603:10b6:a02:cd::20) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from localhost (2620:10d:c090:400::5:2555) by BYAPR07CA0106.namprd07.prod.outlook.com (2603:10b6:a03:12b::47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3000.24 via Frontend Transport; Thu, 14 May 2020 17:42:38 +0000 X-Originating-IP: [2620:10d:c090:400::5:2555] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 6cd74043-4735-4fae-010c-08d7f82e320f X-MS-TrafficTypeDiagnostic: BYAPR15MB3413: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:227; 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X-MS-Exchange-AntiSpam-MessageData: bfPdShS8yoOZdPDnbEaV+9uu+Mq2+1MMLLO9848Y0uJpa093Yxw9DkZ+8J8PP+RAu9hHo0gsmFU8TFnj2WmC44IcRpEx1XlB7N01k5dEvX1xOar67X5NKdsQHcRYRDPpSZYLOEWI/rc2uXstcx4ps045IMU+b2TDT8rAPfZzqYS5mB0G3LdKuoAG3qSd8Q7MWaSnFGl2CIernxqjQHhThfyGqrB8XX3hPa4Mf+ijTCAtlk1Ln303Ah3+L75bzRZtb3s4iCt1ZKsCZTC9RwDVk0Yac8hXpWGEcH9MG0ZjyQfEAsspHsgVzX4l+Lj+zFpMlW2Tnd+iFNExaY/VhXRoeBo0gpqmeX2ZAlA9fhtwVV5gYxQN28SHqbaxTPje6Gtg43de9iHkRUGmAULDKvoU4teqRFuUJqTZorO7a/nJ+vfrJPDy6KKf42k6YBY3ytcD+irGaMvc6Vd627dfmzdCh++4NezZ6kdKgx33frRbEXWDAjKMeZqeb7Wv6JcMvBov4yjwK8KIuNj4uOjA8tVFSw== X-MS-Exchange-CrossTenant-Network-Message-Id: 6cd74043-4735-4fae-010c-08d7f82e320f X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 May 2020 17:42:39.0991 (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: Hkp/YSg8+6cforMrdJom8OvK6OC5D4J2gqiFeVgU7cNe1CaXwf3YN7QNMgMDaDdx X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB3413 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-14_05:2020-05-14,2020-05-14 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 malwarescore=0 impostorscore=0 suspectscore=0 cotscore=-2147483648 priorityscore=1501 spamscore=0 adultscore=0 mlxscore=0 phishscore=0 mlxlogscore=999 lowpriorityscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005140157 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Yonghong Song [Thu, 2020-05-14 08:56 -0700]: > On 5/13/20 2:38 PM, Andrey Ignatov wrote: > > @@ -77,8 +81,6 @@ static const size_t timeo_optlen = sizeof(timeo_sec); > > int connect_to_fd(int family, int type, int server_fd) > > { > > - struct sockaddr_storage addr; > > - socklen_t len = sizeof(addr); > > int fd; > > fd = socket(family, type, 0); > > @@ -87,24 +89,64 @@ int connect_to_fd(int family, int type, int server_fd) > > return -1; > > } > > - if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeo_sec, timeo_optlen)) { > > + if (connect_fd_to_fd(fd, server_fd) < 0 && errno != EINPROGRESS) { > > + close(fd); > > Remote possibility. close(fd) may change error code? It can in some cases that are rather theoritical in this case (e.g. buggy multi-threaded program closes fd from another thread right before this close()). But I can save/restore it before/after close just in case. > In my opinion, maybe convert the original syscall failure errno to return > value and carrying on might be a simpler choice? I wanted to preserve semantics of connect(2) here: return -1 on error, or fd >= 0 on success. I guess if I save/restore errno it should be fine. > > + return -1; > > + } > > + > > + return fd; > > +} > > + > > +int connect_fd_to_fd(int client_fd, int server_fd) > > +{ > > + struct sockaddr_storage addr; > > + socklen_t len = sizeof(addr); > > + > > + if (setsockopt(client_fd, SOL_SOCKET, SO_RCVTIMEO, &timeo_sec, > > + timeo_optlen)) { > > log_err("Failed to set SO_RCVTIMEO"); > > - goto out; > > + return -1; > > } > > if (getsockname(server_fd, (struct sockaddr *)&addr, &len)) { > > log_err("Failed to get server addr"); > > - goto out; > > + return -1; > > } > > - if (connect(fd, (const struct sockaddr *)&addr, len) < 0) { > > - log_err("Fail to connect to server with family %d", family); > > - goto out; > > + if (connect(client_fd, (const struct sockaddr *)&addr, len) < 0) { > > + if (errno != EINPROGRESS) > > + log_err("Failed to connect to server"); > > Not saying it is possible, but any remote possibility log_err() > may change error code to EINPROGRESS? To my best knowledge, neither fprintf(3) nor strerror(3) use EINPROGRESS, but since in this case having a reliable way to communicate EINPROGRESS from connect is rather required, I'll save/restore errno for caling log_err. -- Andrey Ignatov