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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] tun: use pskb_may_pull_reason() and remove SKB_DROP_REASON_HDR_TRUNC Message-ID: <20261001172459.GA1660921@shredder> References: <20261001093925.3529772-1-littlesmilingcloud@gmail.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261001093925.3529772-1-littlesmilingcloud@gmail.com> X-ClientProxiedBy: FR5P281CA0049.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:f0::8) To PH0PR12MB7957.namprd12.prod.outlook.com (2603:10b6:510:281::22) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR12MB7957:EE_|CH3PR12MB9080:EE_ X-MS-Office365-Filtering-Correlation-Id: fd984925-775f-4bdf-5650-08df1fe0f23c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024|23010399003|10067099003|11063799006|56012099006|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?e/i+4WTl1Sn2w1Lyd8371shCKajJmdtFB1jv+K3Kyd5eq9mB/f53ba3oKGcM?= =?us-ascii?Q?3lkqkCipmpNS1DfmU8IpDPkQEveI51OxrKpf4G0QbPBUEHG9jW3AErleVKQC?= =?us-ascii?Q?CYRN5mYtRGzb9gfxdfTrKC4J3xGpXW6lxzJ5X0ohU9Tvpf/qv/j75Zbh6AOz?= =?us-ascii?Q?bmtxBpsxWf0VQmGSu5Jt76HyqWnUYRlUB4tu5X986BakcqhMoMD/LwMKlpsM?= =?us-ascii?Q?k7TTcExWBF0JHQj6Lv7vysf/LHDTS/uW+1apYKq+504D85UGgtVyn4Imc/bS?= =?us-ascii?Q?WRtKAY1jpenoneZx+XSqAdsxFbubzMlqGNa/vsROwJD7x4b974JmNmGVFSLB?= =?us-ascii?Q?17V5AY1NiC46t50u1PhcWvaTGe3S12BQWA38OeR2kUIq1mF9dkPiuMKgUfnr?= =?us-ascii?Q?y92puM+Y0QP2ewzxbN5RVyCI5Av6HEWn84W6WbxiXA7TtIsgvn5r1Q3nmcxs?= =?us-ascii?Q?Lmck/AZYC8Z+Ep6ZRoY+QNzcXL6rTtWKO5X4R7ZcrWk3EeJgmA2sLS2XJNpI?= =?us-ascii?Q?7VCfhMt4tkuXtgX0WValeHdxq+OYZ3c1bUXuyGj2gFnmD836AQpircU1clcS?= =?us-ascii?Q?M+mxtTMzAKiSMqHJnJdGRM9yIrlV+/F+bVpH5qDcIzrk80a2Mqy67GBmQ/26?= =?us-ascii?Q?yAySgJ8zkpc4OVO2Z3no648yrI9XetkTp3vw3EqxWx9M/RqqRi0Fkmohw6oU?= =?us-ascii?Q?KDY+VBIPR/nn99FkkWtRN4Rm3nR40H/6HUmKQ2yGkVETgIhVkuUH5YIHJvVQ?= =?us-ascii?Q?BzEjy8i/F8uqhT4EPW2j632TEpwXV8j3OcWZVymYgPQME2Cr3EQxaa8L0uNz?= =?us-ascii?Q?+iOs8Z8N4vHb8O4MAhP3uRtsfheF3jsTxHxhgc0qZKWjIxiEnoQ/e5JBc7mj?= =?us-ascii?Q?fFmUqLn1utV+eSt262R4HUqFjBcsqebdBD1aj3FpMgwsOAOsXFqiQL2mYgYB?= =?us-ascii?Q?wJCP5Jck0juYwhf9UbiuhdwMV5kmkD6hUQopNVnHnWxPAZ32cslv8wKrvjST?= =?us-ascii?Q?tbtWcl2ni6UtBtMLGIMo1rp06c0cVvTZR6COhDsLp19JeNW5ihbb9UNxqiPE?= =?us-ascii?Q?9GUgOe99YDucDHyE1nXEQAz9SvX9hQvJ5BTK70JYLutaky3wLaCHXjGSg8PW?= =?us-ascii?Q?77f6TYi7g3+4tobjAUtRWIlyZHvUDbIqFGinU0KSr/efPlXSX4Keac1S+b4W?= =?us-ascii?Q?T5T5xaTneebbSWDb2HUO0CNrID81OJuQhwQDdOQn2g3Xo2y+NFxNntlEUcT4?= =?us-ascii?Q?8RjqlLgyAOqw6s0U/2zzunU7LjpZ7j0LvcyGGGDGFXfpIk4gL1i4KMUotDR3?= =?us-ascii?Q?d7fIiZmamQxKxKDsOSSRtfiagkTM0ZEkRuiLKX4MpsCewAWrehdZ97F7Gn2x?= =?us-ascii?Q?i7F8Q8WArMxc5clEejl4xaQFROv9kMefcA8XVPct8lrBiEHRWoCX8CwxEOh1?= =?us-ascii?Q?4SvBSJoAPu+NfWqdMXOvVgDxs5DGVi98/TptKvXqJLcdAyRz4zGTVoCSHxjc?= =?us-ascii?Q?TYgcBZuG+KjMBMFRMJ2wUCaYPzrkZG14cq5zyQgDvoB7c/QyzDHKrGoo5p1u?= =?us-ascii?Q?JSpSisqFE6G9uonetMQpJHPEYpLZ94InrHA+EbD+Sh7MZLizhA5uLiiTg8A9?= =?us-ascii?Q?foQrHSrKTPGE1AvlQR3DnkJ+IM5ChyM6yqfVXfbxHWpP+lOjWQwB3y2ygoGF?= =?us-ascii?Q?BF1Hg7IQP0+35tv7a2G8teaw/4DtgwW673mMi1CjBPxVvvyXClJYDKYzr6ru?= =?us-ascii?Q?Edvul/jr3w=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: fd984925-775f-4bdf-5650-08df1fe0f23c X-MS-Exchange-CrossTenant-AuthSource: PH0PR12MB7957.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Oct 2026 17:25:10.8035 (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: xXo9gFPm+p6HrJZAF/ZmFIipJkme/6RWjGPe5fxbALnfuoaprWIBkqkhg+gq67D6LNngFPwn11wRQxb0YgF1ig== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9080 On Thu, Oct 01, 2026 at 12:39:25PM +0300, Anton Danilov wrote: > tun_get_user() is the only user of SKB_DROP_REASON_HDR_TRUNC. It sets > it when pskb_may_pull() fails to pull the Ethernet header of a frame > written to a TAP device. > > pskb_may_pull_reason() reports why the pull failed: PKT_TOO_SMALL if > the packet is shorter than requested, NOMEM if pulling the data into > the linear area fails. Use it for the Ethernet header pull in > tun_get_user() and remove the now unused SKB_DROP_REASON_HDR_TRUNC. > > After a successful pull drop_reason is SKB_NOT_DROPPED_YET. The path > that later finds the queue detached has no reason of its own and relied > on the SKB_DROP_REASON_NOT_SPECIFIED initializer. Fall back to > SKB_DROP_REASON_NOT_SPECIFIED at the free_skb label, as vxlan_rcv() > does, so that this path, and any later one without a reason of its own, > keeps reporting it. > > The error returned to user space does not change. > > Suggested-by: Ido Schimmel > Link: https://lore.kernel.org/netdev/20260923145931.GA2859441@shredder/ > Assisted-by: LLM > Signed-off-by: Anton Danilov Reviewed-by: Ido Schimmel I will check the other series next week.