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Miller" , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: Re: [PATCH][net-next] net: vrf: switch to synchronize_net() when releasing routes Message-ID: <20260311152613.GA2441293@shredder> References: <20260310105331.2371-1-lirongqing@baidu.com> <20260311131935.GA2415888@shredder> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: TL2P290CA0002.ISRP290.PROD.OUTLOOK.COM (2603:1096:950:2::12) To DS0PR12MB7900.namprd12.prod.outlook.com (2603:10b6:8:14e::10) 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: DS0PR12MB7900:EE_|BL1PR12MB5732:EE_ X-MS-Office365-Filtering-Correlation-Id: 52e0b812-65b7-431b-0675-08de7f828ec1 X-LD-Processed: 43083d15-7273-40c1-b7db-39efd9ccc17a,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|22082099003|18002099003|56012099003; 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> > > > > > RCU_INIT_POINTER(vrf->rt6, NULL); > > > - synchronize_rcu(); > > > + synchronize_net(); > > > > I might be missing something, but why do we need synchronize_rcu() here? > > The code below calls dst_release() which will only free the dst entry > > after an RCU grace period (assuming we dropped the last reference). > > Agreed, this could/should have been removed after > > commit 4f04256c983a4f115417d2009b44dcb7d70a6375 > Author: David Ahern > Date: Fri Aug 11 17:11:14 2017 -0700 > > net: vrf: Drop local rtable and rt6_info > > The VRF cached rtable and rt6_info for local traffic are no longer > needed and actually prevent local traffic through enslaved devices. > Remove them. > > > > > > > Also, I think that instead of using net->loopback_dev the code can be > > converted to use dst_dev_put() before dst_release(). > > > > Maybe in a separate patch ;) Yes, separate patch. Another thing that can be simplified in this area is the NULL check in vrf_rtable_release(). I don't see how that can happen. It is necessary in the case of vrf_rt6_release() due to 'ipv6.disable=1'. Li RongQing, can you take care of these changes? 1. Remove NULL check in vrf_rtable_release(). 2. Convert vrf_rtable_release() and vrf_rt6_release() to use dst_dev_put() before dst_release(), instead of using 'net->loopback_dev'. 3. Remove synchronize_rcu() from both vrf_rtable_release() and vrf_rt6_release(). Thanks