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Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Nikolay Aleksandrov , netdev@vger.kernel.org, eric.dumazet@gmail.com Subject: Re: [PATCH v2 net-next 06/11] bridge: provide lockless access to p->designated_cost Message-ID: <20260604105030.GA775294@shredder> References: <20260603062043.3911278-1-edumazet@google.com> <20260603062043.3911278-7-edumazet@google.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260603062043.3911278-7-edumazet@google.com> X-ClientProxiedBy: FR2P281CA0136.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:9e::18) To SA3PR12MB7901.namprd12.prod.outlook.com (2603:10b6:806:306::12) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA3PR12MB7901:EE_|IA1PR12MB6041:EE_ X-MS-Office365-Filtering-Correlation-Id: 497a55c2-a004-41dc-822c-08dec2271e86 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|1800799024|18002099003|22082099003|56012099006|4143699003|11063799006; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?qF4uil+y61AsXPpr9u93tFnBR6rxKDDpetLK3K9VFllLYjgI2iYCUwf+HkZO?= =?us-ascii?Q?g2DHjrfPf6EEuRtxUMUT2MlPGMcIzpoS2x5SGp4arrJjuJ1NmIxiGMTfpLX0?= =?us-ascii?Q?tIiorwuz6sfLmSvCnyKCo1kfGiNL3PJU049NdXS789sKMRl8xsIUNBuIfeQj?= =?us-ascii?Q?V80uFUxgzcbKsU0i7X6avDXsKa/D3+CYq48MC9VwXWWxjfrQBndAFkOsecPm?= =?us-ascii?Q?usSCwCOJ4dQzD5wkqk4YeDwflgrgJxr7jG3Rh1jqkhmsfTRoCwq2CIyT8IlS?= =?us-ascii?Q?Dp4CquYtfOJ3333RpSkekFUDA4aCqg3sMNOwHMAItxKZV9Tx6eq5YOVoJJix?= =?us-ascii?Q?WSmEZb5VhhqhvJ5JxUbFZS5o7w1U0oac60nLivqewOLbqBEXjipQ2FGwu3o4?= =?us-ascii?Q?/oW4m40TOaP/0fCKL3/eXivKZCh6xbifxo4xmb5Jr5CyGKvANJGg+qKWoOau?= =?us-ascii?Q?V0jqUQcJneAuBUUmV+ZuYzZxOGQAYClTk90IU2jvtOoJ8+y7exyYqjSUc+Nd?= =?us-ascii?Q?g1PHi1u2a9fvAxTksB++kvl0CBshUPEn1zY+Neh3W1j8sbDyO5K7MpOo/gyL?= =?us-ascii?Q?e/GLJ9TJ7qdCk4I3iCWwXK4LJ8PeizQ6bNCeZsHGoXvG1dIMcXmUioXIxh13?= =?us-ascii?Q?PDWwQe/L1VQ5hwhEn4kkTCbixHx2WqaJNC2F6xmopjY0+WI9vGl8VDrVvNTf?= =?us-ascii?Q?u/nGeW0heMGKYrkPkZzCwk0N1QGiwxU72vFh6B/9H9DUFcq+4kRF/6qcMlJC?= =?us-ascii?Q?oeMyqBB27CEykIY2pfytEvg8/ZbPPrR763SD8SReyJaN72EIqwfbYt4CyRoF?= =?us-ascii?Q?YlshTLY49g0Fjr1or6YuNB+YQ373XaHNAVTT9jXZutpoiDJNSapLhXJvYfVl?= =?us-ascii?Q?iWi92RfsXB1qQgZTU9gk5FJgD+Y8/rKNNv+WxpZyjojNs2Le+xkHbg51KaCl?= =?us-ascii?Q?72IXOuBFyWdLugtNqdYacT1FOuthVEoYxOkDNTo77z4G4I367ao9Z6bOfCX6?= =?us-ascii?Q?MWZnR1SF46wisjykcvSrMJGA0637A3mJrQGOt3adGX1dP1bPXP+qSfTqRQDI?= =?us-ascii?Q?jkQULLUBKUv4KqgZkQva+DpnENZNK1Zh/4LI4QK1HAvlZefyAigeAKDKAgby?= =?us-ascii?Q?jDYGXB8UsDw4gT+qxiJAJdKGjd5ew213Qa2vFsT89pJB7vbHkQNpl1dSpZrz?= =?us-ascii?Q?rU1KkwAubjqfj8jpoxOHs7kLTj7l0JpqRd+hPVe/UBQ70upetoikJVlHT/77?= =?us-ascii?Q?YTOcdYp6xvxyT/vVXFtf1gZ4T0tinI1opvdAl6LdrYLy1k26yKRJrPyWVq/U?= =?us-ascii?Q?STXom4htPODn7ZxTkRSDA/m+7QnkuqjPNK7AQ7Y9dBRTEnIz1WW1s5yDMnQU?= =?us-ascii?Q?l2/LZxMo/h9JZJ+b0DPHHsRursMbIrSs0hoK94+yb/IfkkxHis7orHSA4oAy?= =?us-ascii?Q?SW9CL7/LImyXxiZ9lHVILw/N4rlEopDRZkOics/OvwVeZIc8h+/vw+oQa+zD?= =?us-ascii?Q?vPQTG7ZsxL4hrH0uAVOJ/jYyIMWy04uVH6nveo209WM5U4A1ROqnTl14UepI?= =?us-ascii?Q?o72LL+gdevQ7uFANCKSCxAf/NdQmf/TcEg6RHP1JYvWDv4RG+YzR9mqRjkhD?= =?us-ascii?Q?UUElRjUmqT3QHy6AKo/NnnI7xhgxt1KPuPCVAJtNYBozE5OzhFfqGaIw+BqS?= =?us-ascii?Q?rDuBQ/Q0KtZtvKoSKF1NfXnP4l6brbbS6qSkLCNS8Q/R/TDT5RhE5jwnlYN1?= =?us-ascii?Q?BpJBcDWOpg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 497a55c2-a004-41dc-822c-08dec2271e86 X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Jun 2026 10:50:40.6723 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: R5LaZq8ciPTIGvl6hyvMcuIOxW8LJVyfSnzKzy69mis4Ve7iRtGGk9yRI9Z+RIOz+GRNQq9gWuUlw0d4s3eEBA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6041 On Wed, Jun 03, 2026 at 06:20:38AM +0000, Eric Dumazet wrote: > @@ -302,9 +304,10 @@ static int br_should_become_designated_port(const struct net_bridge_port *p) > if (memcmp(&p->designated_root, &br->designated_root, 8)) > return 1; > > - if (br->root_path_cost < p->designated_cost) > + t = br->root_path_cost - READ_ONCE(p->designated_cost); > + if (t < 0) > return 1; > - else if (br->root_path_cost > p->designated_cost) > + else if (t > 0) > return 0; Eric, I think you meant: p_designated_cost = READ_ONCE(p->designated_cost); if (br->root_path_cost < p_designated_cost) return 1; else if (br->root_path_cost > p_designated_cost) return 0; ? > > t = memcmp(&br->bridge_id, &p->designated_bridge, 8); > @@ -344,9 +347,10 @@ static int br_supersedes_port_info(const struct net_bridge_port *p, > else if (t > 0) > return 0; > > - if (bpdu->root_path_cost < p->designated_cost) > + t = bpdu->root_path_cost < READ_ONCE(p->designated_cost); > + if (t < 0) > return 1; > - else if (bpdu->root_path_cost > p->designated_cost) > + else if (t > 0) > return 0; Similarly here?