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Miller" , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, eric.dumazet@gmail.com Subject: Re: [PATCH net-next 04/13] ipv6: use xarray iterator to implement inet6_dump_ifinfo() Message-ID: References: <20240221105915.829140-1-edumazet@google.com> <20240221105915.829140-5-edumazet@google.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240221105915.829140-5-edumazet@google.com> X-ClientProxiedBy: LNXP265CA0034.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:5c::22) To CY5PR12MB6179.namprd12.prod.outlook.com (2603:10b6:930:24::22) 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: CY5PR12MB6179:EE_|CH0PR12MB8549:EE_ X-MS-Office365-Filtering-Correlation-Id: 07925608-524e-466e-535b-08dc330c6e1c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CY5PR12MB6179.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(230273577357003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?iQAjRzzHb8XL7eDbMtHzPbyCjUZqcKG6Fgq/SdPxX6afhgAHuT4I7k6A/giC?= =?us-ascii?Q?Um/nUqgjzsiQRUTvS6NzTFhksKHsdu2B0b5yPrkiicV3mL8DGYCX2iQswe97?= =?us-ascii?Q?H5stPeYrGhHFbTKbcAlNjwNymoGgc3Xg+lmUXlAF1D1arXp062JRhfVWfA/Q?= =?us-ascii?Q?Xi3dzHHesUIPSwjJlaR1RUBXiPJP3jwkTRULreN+uZyHYJ3B0e6RhrMIkpsB?= =?us-ascii?Q?+ITRng7fWj7TGNB8LEFTSC8diIR9V/WKuTsxw9PdhGfKeCLxL1/lDOMkFsmg?= =?us-ascii?Q?AGdULVHQKKRMw09FaTP/pO5CJbrwnofnmmWiTpofttyQE5TJ1LggGezuH5O1?= =?us-ascii?Q?ZYisgsw7lmspFgb5Ng+2nY4DAAp6Rkm2RCel99tUA1qd3sYukuJhadIkhoYn?= =?us-ascii?Q?sVBodj5xQD7aEvYXh+G4BZDwk0zvA5ShHGnlVVTKRbIOPbyq2QjJhRTeFbfR?= =?us-ascii?Q?Iis/2GgH6fJJT6TN3UT2hZ/+59/jWvre/OhDBfjXgVjg1xMhjF9hUZdhPlE0?= =?us-ascii?Q?STwommZmJj4yMXPM4r6jG/hANdPz/oRKsV/cMydUwJqDi5iLjc95x751WLop?= =?us-ascii?Q?jKI5W9+WPuu+/qxAgaFa/ogv+16hjHNy+3QGi58icSpoMg+NXiMaPuorY14p?= =?us-ascii?Q?ER1TJWLyHlWMgv8PGkdtHBGCWXO15ffPHyZqtG1rfj+xwuX81Ti5f1LKlaoD?= =?us-ascii?Q?0uqSzGA9GlmAK6t72rHZCpRUp/9piDRy4N4s599xsO7Df2lJkRixajGmq9pD?= =?us-ascii?Q?Cw/iBMnO1tsmp6+3Dd2esrnadcwbSpwQaW1v3ZsuXGaCOOc3W83HyCkGodEQ?= =?us-ascii?Q?cSZ5wwqMjkjswdnipIKPjkeXWfLNW3lYkW3Nvo0IbKM3CW9U4wfC4N+J6fk0?= =?us-ascii?Q?NOTq7bpKywRRmq4xRTNntoF8mriLmQuRhByaolrzrt3d8Fakqatw+7RfDDAR?= =?us-ascii?Q?MeaS10z17nCedZUKJ1oKVCw0YJie0zu+WqKvCD/krOp4y0KLqcHbD3csH4D+?= =?us-ascii?Q?C6qkTQ6jZG1mfIt8ZAyMvwxImctjlGNt8bKeae468VydCoVlKOpKThDTKLdQ?= =?us-ascii?Q?jTYQTFCNsJZG6xmBl6oCRT10uZQCNRiTPEZxFCnIdpTCFZF/WnZcIW8prUlj?= =?us-ascii?Q?3Mbz3Qn01VXfuCXTeJXs7LnXGooRr7PzNQXJy1O3mTVdDvd3UjjEfsmR3ufv?= =?us-ascii?Q?E6v9VcPCmYkXBQGAbv11UQwKzoO7XKxjWAJoEjpTFGW93fv4FgUcetUsQchJ?= =?us-ascii?Q?xrE8g+BJfYBye01iYaDCnhccUQxajRTjtcPmcnrl6vvn5ElC3cFXV5GY/gxO?= =?us-ascii?Q?hg9dj/lU0U2d17pEI6UEeMLL5uc6aur5Nwb+ZIhuY66cgZKz7HWOWbR7MvY5?= =?us-ascii?Q?BiCJdemB0CFcpdKf9PiAXzd8nd5vE5mt+LsHE/eVilv5O0WDYuNsypiHd/vN?= =?us-ascii?Q?rgNeJ9G62x2B5uognr5DOH5CsGowy/wXoRTl0q+CBbSUfkqkq9h84NSEE+2P?= =?us-ascii?Q?ZWT0pfc8q+LPSWP+6sC0bIySdTCwNm6l171p3aD0jnsgtT43eFUIfrRxhthr?= =?us-ascii?Q?mzlCbxGQY8kfYxNv0Or+Itcv4aq/HceV2/zbrta/?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 07925608-524e-466e-535b-08dc330c6e1c X-MS-Exchange-CrossTenant-AuthSource: CY5PR12MB6179.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Feb 2024 18:39:26.3388 (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: GO+f/O94y4BBgBcBDotcemYrP5tSpP+jqjV8wWBXNSdXIK4gdv9KI215LgFqGkAlcX1m42wHTkh41j1mx4HQdg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR12MB8549 On Wed, Feb 21, 2024 at 10:59:06AM +0000, Eric Dumazet wrote: > Prepare inet6_dump_ifinfo() to run with RCU protection > instead of RTNL and use for_each_netdev_dump() interface. > > Also properly return 0 at the end of a dump, avoiding > an extra recvmsg() system call and RTNL acquisition. > > Note that RTNL-less dumps need core changes, yet to come. > > Signed-off-by: Eric Dumazet > Cc: Ido Schimmel Reviewed-by: Ido Schimmel BTW, not sure if you saw, but there's a failure in the fib_nexthops test in Jakub's CI due to a lockdep splat [1]. Reproducer: # ip link add name dummy1 up type dummy # ip nexthop add id 1 dev dummy1 # ip nexthop add id 2 dev dummy1 # ip nexthop add id 10 group 1/2 # ip route add 198.51.100.0/24 nhid 10 # ip -4 r s Seems like an oversight in nexthop code and fixed by: diff --git a/include/net/nexthop.h b/include/net/nexthop.h index 6647ad509faa..77e99cba60ad 100644 --- a/include/net/nexthop.h +++ b/include/net/nexthop.h @@ -317,7 +317,7 @@ static inline int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh, u8 rt_family) { - struct nh_group *nhg = rtnl_dereference(nh->nh_grp); + struct nh_group *nhg = rcu_dereference_rtnl(nh->nh_grp); int i; for (i = 0; i < nhg->num_nh; i++) { [1] ============================= WARNING: suspicious RCU usage 6.8.0-rc4-custom-g85d71c2cf96e #20 Not tainted ----------------------------- include/net/nexthop.h:320 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by ip/668: #0: ffff88801c1a3eb0 (nlk_cb_mutex-ROUTE){+.+.}-{3:3}, at: __netlink_dump_start+0x155/0x9e0 #1: ffffffff85d4fba0 (rcu_read_lock){....}-{1:2}, at: inet_dump_fib+0x133/0xab0 stack backtrace: CPU: 19 PID: 668 Comm: ip Not tainted 6.8.0-rc4-custom-g85d71c2cf96e #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014 Call Trace: dump_stack_lvl+0xbd/0xe0 lockdep_rcu_suspicious+0x211/0x3b0 fib_dump_info+0x1ae2/0x1e10 fib_table_dump+0xc2e/0xf70 inet_dump_fib+0x7fa/0xab0 netlink_dump+0xd47/0x10f0 __netlink_dump_start+0x702/0x9e0 rtnetlink_rcv_msg+0xb6e/0xf20 netlink_rcv_skb+0x170/0x440 netlink_unicast+0x540/0x820 netlink_sendmsg+0x8d8/0xda0 __sys_sendto+0x27a/0x3f0 __x64_sys_sendto+0xe5/0x1c0 do_syscall_64+0xc5/0x1d0 entry_SYSCALL_64_after_hwframe+0x63/0x6b