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Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , David Ahern , netdev@vger.kernel.org, eric.dumazet@gmail.com Subject: Re: [PATCH net] ip6_tunnel: do not use dst6_mtu() in ip4ip6_err() and ip6erspan_tunnel_xmit() Message-ID: <20260611062739.GC836457@shredder> References: <20260609091337.2672441-1-edumazet@google.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260609091337.2672441-1-edumazet@google.com> X-ClientProxiedBy: TL0P290CA0010.ISRP290.PROD.OUTLOOK.COM (2603:1096:950:5::14) 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_|MW4PR12MB6778:EE_ X-MS-Office365-Filtering-Correlation-Id: 7a35315b-292a-4e1d-bd8f-08dec7828f4e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|23010399003|376014|18002099003|22082099003|11063799006|56012099006; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Cl56jPYY2+IbGU/1PpTb2RMS+/0nbuvAIIYrDhL94VRc8xbBxz2Va2meS9WE?= =?us-ascii?Q?MZw+2FlxrZH2H8XMA+owqUGKeY1Z0uTkS+k8+pWyUBgmt6ciPpSlPKmPy4N+?= =?us-ascii?Q?mYohhTdqZ+OTKVnA5WB9dwgluOx+IJH15mC7EZfnHmcSXuHVBw3V10l2vF+J?= =?us-ascii?Q?aPjbjcNcK0sqw2lggoovcyao2mralc6ertqkTQkVK45NtdKSP7O4Sbh+nfup?= =?us-ascii?Q?0UycFHYRgNcP4wnDvwbKTWWhKYoO3o1/vg3B+6cuQjjphpoPxLNHxTRcWjcG?= =?us-ascii?Q?jaPvFgc0g+sIaYsRKBm79TqWUW8o8q3S09lboF0V+M41gxZ5zRe9pxuXdn/n?= =?us-ascii?Q?eWfz1rJFON+MG6ixtPAgQuHAKW/KUuq6jxZC/ajKbVrQ3JyOBc890dlAbtrt?= =?us-ascii?Q?A4zIAfnZQ479SV3DfuRGPgy4ZaydQ38YmO6hqugvD8MdVrGtLnzIm2jHTimj?= =?us-ascii?Q?Qel4uL01ZFXN74lSFF40TI43cc++h8scoyo9ihIlek8fcRIOOpVJN+RpXMNb?= =?us-ascii?Q?+f7WUQ0fQ6ugkJTRE0NzJieCo8SzFwqOrH5Im4+pUJLbiZKELLijCehI4xj4?= =?us-ascii?Q?gHygrrEgOAudC7svIxGvb4Y6Ev1/FeUjrmpPzpEnHDaoa23Juzv1wNZgZt8q?= =?us-ascii?Q?KmQCrvtQaz4lyWMr3cDLUYwa5TBSiwokXUk1y7ZBx6uRtiiD47dnSIzagloA?= =?us-ascii?Q?dRciRtgqYpNbf7GVjSM4bE7RbjGbkUe0MLx1X0x2zY9Mne72egjOlz4gGOd8?= =?us-ascii?Q?FZAzALRNcvgEUamtmKvdk6CCPW8xnfWudpOlDZN9teKgLCnKuniUGHoO4HuY?= =?us-ascii?Q?ZzBR9tL95RqsovbOttdINBx9oZU+2/ClK0p6yFGdWkSds5Grsh7N3fPlm7ob?= =?us-ascii?Q?4bduQMI8cPwjflk/tM5zWenjAq+E30DopcMFc7rPbkSHXGRAY0PuTeUFcJcs?= =?us-ascii?Q?CZX3t0gOm6tnDyHMuTBcalyZ3CV3I83JYbjd+EPDEiKjoYtXFFkYk0535v9h?= =?us-ascii?Q?2nfa/y0xXYuBT2kWi7c+qK/1ZQyT144RXu6CgGXylmeiIo5G1PlyJ7IznjHt?= =?us-ascii?Q?xd1lMqBD2b3GW96c85re3C/ViK8jeTaIG9Wkn5oasw4nO/F+7u2S8cU1iBQB?= =?us-ascii?Q?OomcwPs53SQycvqgxCATtcvsY0I+ZsGEcKxGaTGGEZKo0Mlfckx0i1fSflVz?= =?us-ascii?Q?686Gs2fgiXdiGag1ObIN08Y5mfNRxscfedK6xexmP1kvxXCZ0VE0PSOZ9WQj?= =?us-ascii?Q?0nxPfzCsGsQ3ftxltErOUZzzDdVRVp1lCZQENlKiTi6wzbekSoHcb3VWp3Kb?= =?us-ascii?Q?aAynuMFKsXHmWKpoLRrKUU9NGtoxy45jnbIGBaGhUBo410ACM7tJ33gSgwZX?= =?us-ascii?Q?1r3SR+TIrAmOErh3FdhsYd1Z8F93fCd+8E7llEZjX34ATQgbDVm4j/jNOY7w?= =?us-ascii?Q?8K4LtranJCpzpsk3dXUnSRBUTUoRYdivEUCZ8FZ0mSac9h0whkDSMNc/2wYx?= =?us-ascii?Q?hnTnq2Ol+4+460v21Ge+FZNNeai9e1Z5P88v5ZsyMfT7C0ojtPnkijrxN/ay?= =?us-ascii?Q?YhrE5IDwfKMa9olq7SfvjukB+kZ+mO2RElZuE2MZX07veJuJAQP3PUAp3hpB?= =?us-ascii?Q?w72j2yY0MRXlmngB/nz6Uph/QVSzQke04wmI/Dlw3UyaMc+E9WkCQZktPzZG?= =?us-ascii?Q?vgNGTAugZn9j7YB3KpWPb+/8Li5j4nYDblCIEEbhR2LckNmI?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7a35315b-292a-4e1d-bd8f-08dec7828f4e X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jun 2026 06:27:49.8815 (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: zCA6TGPGgu24B2jqcsRtAK/+4s37wDZYTZRldNjPAl9ZjF7XckG7eD/PCEOOR75QLbfOmb7uNvX0mucxV8lAwQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB6778 On Tue, Jun 09, 2026 at 09:13:37AM +0000, Eric Dumazet wrote: > This is a minor performance / conceptual fix. > > 1) ip6erspan_tunnel_xmit() > > ERSPAN tunnel can mirror both IPv4 and IPv6 traffic, skb > (the packet being mirrored) can be an IPv4 packet, > and thus dst can be an IPv4 destination entry > > Use dst_mtu() which contains generic logic for both families. > > 2) ip4ip6_err() > > skb2 has been prepared as an IPv4 packet, and its destination > is an IPv4 route. > > dst6_mtu() is optimized for IPv6 destinations and uses INDIRECT_CALL_1 > to call ip6_mtu() directly if the ops match. > > We should use dst4_mtu() instead. > > Fixes: b40f0130a23b ("ipv6: use dst6_mtu() instead of dst_mtu()") > Signed-off-by: Eric Dumazet Reviewed-by: Ido Schimmel