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Thu, 16 Apr 2020 18:55:26 +0000 Date: Thu, 16 Apr 2020 15:55:22 -0300 From: Jason Gunthorpe To: =?utf-8?B?SMOla29u?= Bugge Cc: Doug Ledford , OFED mailing list , george kennedy Subject: Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route Message-ID: <20200416185522.GA11945@mellanox.com> References: <20200403193656.GF8514@mellanox.com> <20200406173149.GH11616@mellanox.com> <09A6E613-AA59-4C5F-889A-EF45722B7F69@oracle.com> <20200406181032.GI11616@mellanox.com> <20200414125012.GK11945@mellanox.com> <20200414161141.GL11945@mellanox.com> <3168883E-169E-4D96-A4F5-8FF882B164BC@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3168883E-169E-4D96-A4F5-8FF882B164BC@oracle.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: MN2PR01CA0011.prod.exchangelabs.com (2603:10b6:208:10c::24) To VI1PR05MB4141.eurprd05.prod.outlook.com (2603:10a6:803:44::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mlx.ziepe.ca (142.68.57.212) by MN2PR01CA0011.prod.exchangelabs.com (2603:10b6:208:10c::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2921.25 via Frontend Transport; Thu, 16 Apr 2020 18:55:26 +0000 Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jP9fW-00072j-UB; Thu, 16 Apr 2020 15:55:22 -0300 X-Originating-IP: [142.68.57.212] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: b33f88f7-131a-49fb-6f4c-08d7e237b9ed X-MS-TrafficTypeDiagnostic: VI1PR05MB4302: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:4303; X-Forefront-PRVS: 0375972289 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:VI1PR05MB4141.eurprd05.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(10009020)(4636009)(366004)(136003)(346002)(376002)(396003)(39860400002)(1076003)(33656002)(52116002)(2616005)(4744005)(86362001)(66574012)(2906002)(5660300002)(8676002)(81156014)(26005)(9786002)(186003)(8936002)(9746002)(316002)(6916009)(36756003)(4326008)(54906003)(66556008)(66476007)(478600001)(66946007)(24400500001);DIR:OUT;SFP:1101; Received-SPF: None (protection.outlook.com: mellanox.com does not designate permitted sender hosts) X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-MS-Exchange-AntiSpam-MessageData: GLvfY+qjmiB5arTs2KERIhlneyHEm4gB9tPLrOEXWBtAuC5FwbuKPCLV3fPxkOs511UwaikNxYlkLqIj9RSy7hR6lDa56elyxmYbhud2FSjMUTgNzGXM824P93/w+21iq40fRncXOed2YjFW0xXxnQ== X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: b33f88f7-131a-49fb-6f4c-08d7e237b9ed X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Apr 2020 18:55:26.8647 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: DsOQ9XafqVuS0tP6S9vvs66xuZcQYNuX78im8foBpdq4SYvYVBUJCnY/ytJG3aVGnFhQZqwNyehjVJW4kR3x3g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR05MB4302 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thu, Apr 16, 2020 at 03:33:28PM +0200, Håkon Bugge wrote: > > I think the trick is that ucma_event_handler never returns failure > > unless RDMA_CM_EVENT_CONNECT_REQUEST, which means the cm_id isn't in > > the xarray yet? > > Sure does. 1 or -ENOMEM. But the ULP's event handlers isn't that > polite. But a different issue from this syzkaller one. Seems like a crazy and difficult API to me.. > >> I assume the refcounting takes care of this. > > > > There is no refcounting for destroy, it must be called once. > > I was thinking about the "cma_deref_id(id_priv);" stuff, but I may have misunderstood. This just causes destroy_id to pause while a ref is held, there can still be only one call to destroy_id Jason