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Fri, 4 Dec 2020 05:02:50 +0000 Subject: Re: [PATCH bpf-next v3 07/14] bpf: Add BPF_FETCH field / create atomic_fetch_add instruction To: Brendan Jackman , CC: Alexei Starovoitov , Daniel Borkmann , KP Singh , Florent Revest , , Jann Horn References: <20201203160245.1014867-1-jackmanb@google.com> <20201203160245.1014867-8-jackmanb@google.com> From: Yonghong Song Message-ID: <9e19c8e7-7d46-0dbe-619a-1b6547fc7f73@fb.com> Date: Thu, 3 Dec 2020 21:02:49 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 In-Reply-To: <20201203160245.1014867-8-jackmanb@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [2620:10d:c090:400::5:86b1] X-ClientProxiedBy: BYAPR05CA0070.namprd05.prod.outlook.com (2603:10b6:a03:74::47) 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:c085:21c8::12b3] (2620:10d:c090:400::5:86b1) by BYAPR05CA0070.namprd05.prod.outlook.com (2603:10b6:a03:74::47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3654.5 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?TERja0swL05JRjVxTERINy9oOUQya25LK2VpUkdlQTNCM3JaTkdUWWF2c2Rz?= =?utf-8?B?cWEwd3pmUlN0aHJRRjNybEh6VjB2Y1gvVjhGSEwwNUErd2FXMmphVFFRMzhp?= =?utf-8?B?eFAzRWRQbGd1NVJhdWV6MDVlWXVxTjdlNXBjaVdqZXNqK3pKRFNsMEozaG44?= =?utf-8?B?SWhXOXVENlRnQ0pXSzVWd2puR0wydFRXNHZqUEpjSG9OT3hmbUo4dEVqVFdD?= =?utf-8?B?RGJNSElnTkcvSnArRzZIcTViTHpSMjRzc1dwemNsajZNM3NLYXNBMHBIRWZH?= =?utf-8?B?OXp1dkdobmpLc2JmK0EvSzQwUGVlSW5kNXhDaTFvRVlvVG1yU0Z1RWNWNnNS?= =?utf-8?B?N25EeERLb0J6ektucUJMSlNnbVdpQlpMdmVmYXp5Z1ZhVXlCaWl0cWVrSEVh?= =?utf-8?B?MHNReXlXTVJFdkJVS3o5ajYzSGpSZkpabWpxVzRkazR1U2xtUXZid1NzTVh1?= =?utf-8?B?NjNVU3oxNWVEU0pWUGlZdHpiamRmcEZ3UEJycGtFTlV4eXhIMVV1S0JpbnVU?= =?utf-8?B?RkhBSG9JUGFMazFLVDQxVkpzemVxcVFJdVZVNXFCTGFKeTREUEZOY2hERC9C?= =?utf-8?B?WjAwSXBndGNXblNBTHZ2VlhJNFgxSnNIV05lNnl5dTdnczFmR25UNzd2Y3RR?= =?utf-8?B?TVRsUXZYU0UzWDZyNXRzbi83VmZUYW5GMDllN1ovMEw4WVYxcTcvYithZzU3?= =?utf-8?B?bll1Sis0VkthNlNxL0lLaWltUHdmaWNCTTNJT3F1K2RyanV2bFFOa1UyRlJ3?= =?utf-8?B?RTQ1RFd1NmNtUnUvWlQwTTI2RUk2ZFJ3elhXUENobEw4VytqS1R3aDdUckVa?= =?utf-8?B?cGNlMWZYcUU4YlZZbWNRclE3YmVsak0xcklVc2xrb080OEdLMW94RTNiQjBN?= =?utf-8?B?a1hrUUxRUzJDTkZDUFVsbGt5MVV1dHluMktGajJaRCtLYk1GTW1YZm9YSW05?= =?utf-8?B?ZVB0eUViTE8zVU1pQXBJQllESVJ6Nk1XVTFUb3ExK0ptMjdyOFpYanhaM2hR?= =?utf-8?B?ck5ZNk9ILzI2Mnc4K0VuejRlUEs0anBCV1V1M0w0OTNOdDdJdmpjR2FJU1Rk?= =?utf-8?B?T1JUOUxqdjJ5VFdVRzlMZnMyTHpXeVl6ZTVPWnVVYXF3a05Rb3V4cGZubTkr?= =?utf-8?B?aUtucjRVWkRjUGttcnhUQ1RyMHhMd2I1WTRad3Vldk4xR1d3TjZXWG5FVUt0?= =?utf-8?B?VVhUOTlSTk9PMWQvcDZwbHZ4NkxXUHVudUhQdnFuTGFXNVNnaW4zOUQ5TXFF?= =?utf-8?B?NWF1NWxLUzR4anhnczY4bjNZTUx0eG5NUCt4ZUgwdnA4T0VrR1daV2xUeFpj?= =?utf-8?B?QVRIenh1cHBEc2xUbEh6NTR1QWdMZ1EvQ2pFTzAyM2o0cWc3bnI1eE1wbUpp?= =?utf-8?B?WUYxeHBIUWtrZFE9PQ==?= X-MS-Exchange-CrossTenant-Network-Message-Id: d472dd04-4a27-4e16-2deb-08d89811d9b2 X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4088.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Dec 2020 05:02:50.8273 (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: 0vVvZJgku9WSXIMNB+E0heCQ3Qk2tgwp5SK1Hwp3g3KQEdUz/Kc41T+2vNCON9/G X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR15MB3713 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-12-04_01:2020-12-04,2020-12-04 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 spamscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 clxscore=1015 adultscore=0 mlxlogscore=754 suspectscore=0 lowpriorityscore=0 phishscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012040028 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/3/20 8:02 AM, Brendan Jackman wrote: > This value can be set in bpf_insn.imm, for BPF_ATOMIC instructions, it is not clear what "this value" means here. Maybe more specific using "The BPF_FETCH field"? > in order to have the previous value of the atomically-modified memory > location loaded into the src register after an atomic op is carried > out. > > Suggested-by: Yonghong Song > Signed-off-by: Brendan Jackman Ack with the above nit. Acked-by: Yonghong Song