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Fri, 21 Aug 2020 15:14:21 +0000 Subject: Re: [PATCH bpf-next 3/5] libbpf: Add BPF_PROG_BIND_MAP syscall and use it on .metadata section To: YiFei Zhu CC: YiFei Zhu , , Alexei Starovoitov , Daniel Borkmann , Stanislav Fomichev , Mahesh Bandewar References: From: Yonghong Song Message-ID: <98fe7ba3-a15b-7414-39f2-8a2243132726@fb.com> Date: Fri, 21 Aug 2020 08:14:15 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MN2PR08CA0017.namprd08.prod.outlook.com (2603:10b6:208:239::22) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from 255.255.255.255 (255.255.255.255) by MN2PR08CA0017.namprd08.prod.outlook.com (2603:10b6:208:239::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3305.24 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 1128080f-815a-4610-13f7-08d845e4e137 X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4088.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Aug 2020 15:14:20.9696 (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: UsHzz0BNzRQany4HxLqghgohodcD/dSHwA2l6ivR/JAGmlmozpySLLPn7u3zCNGe X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB4088 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-21_08:2020-08-21,2020-08-21 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 suspectscore=0 lowpriorityscore=0 priorityscore=1501 malwarescore=0 spamscore=0 impostorscore=0 bulkscore=0 mlxlogscore=734 phishscore=0 mlxscore=0 clxscore=1015 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008210143 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 8/21/20 12:52 AM, YiFei Zhu wrote: > On Thu, Aug 20, 2020 at 3:38 PM Yonghong Song wrote: >> >>> + int fd = ret; >>> + >>> + ret = -errno; >> >> libbpf_strerror_r understands positive and negative errno, so no need >> "ret = -errno". > > I don't understand this one. The use of ret = -errno here is that when > we goto out later we return a -errno. If this line is removed then fd > is returned after fd is closed, in the case of a bind map failure, > without writing to *pfd. Am I misunderstanding something? Aha, sorry. My bad. I missed that 'ret' is used later for the negative code return value. Yes, your code looks fine. > > YiFei Zhu >