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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Cong Wang , Nicolas Dichtel , Jason Wang , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH net-next] flow_dissector: save computed hash in __skb_get_hash_symmetric_net() Message-ID: References: <20251125181930.1192165-1-jon@nutanix.com> <8EA496BE-669B-44C1-A3D7-AF7BD7E866ED@nutanix.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: TL0P290CA0013.ISRP290.PROD.OUTLOOK.COM (2603:1096:950:5::20) 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_|BY5PR12MB4163:EE_ X-MS-Office365-Filtering-Correlation-Id: 676df16e-02d4-4686-500a-08de324700b9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|366016; 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Yes, for some reason I thought that the flow dissector always sets it in this case. > How about another helper, that only tun consumes, which does all of these > things, such that the code still stays clean on the flow dissector side > and we don’t have to mess with any other callers? > > That would be the middle ground between what you suggested and what I did > > Thoughts? Not sure. We already have __skb_get_hash_symmetric_net() and __skb_get_hash_symmetric() and now we will have a third variant. In this case, maybe adding a 'save_hash' argument is better. It also means that the next time someone needs to calculate a symmetric hash they will pause to think if it needs to be set in the skb. I believe that when skb_get_hash() was replaced with __skb_get_hash_symmetric() in tun the assumption was that the hash will be stored in the skb as with skb_get_hash().