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Tue, 14 Apr 2020 12:50:15 +0000 Date: Tue, 14 Apr 2020 09:50:12 -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: <20200414125012.GK11945@mellanox.com> References: <20200403184328.1154929-1-haakon.bugge@oracle.com> <20200403185707.GE8514@mellanox.com> <1720C7BF-D6E4-4779-B05D-203703042B36@oracle.com> <20200403193656.GF8514@mellanox.com> <20200406173149.GH11616@mellanox.com> <09A6E613-AA59-4C5F-889A-EF45722B7F69@oracle.com> <20200406181032.GI11616@mellanox.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: BL0PR0102CA0030.prod.exchangelabs.com (2603:10b6:207:18::43) 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 BL0PR0102CA0030.prod.exchangelabs.com (2603:10b6:207:18::43) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2900.17 via Frontend Transport; Tue, 14 Apr 2020 12:50:15 +0000 Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jOL12-00045O-5f; Tue, 14 Apr 2020 09:50:12 -0300 X-Originating-IP: [142.68.57.212] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 500b2187-d924-4360-f311-08d7e072610f X-MS-TrafficTypeDiagnostic: VI1PR05MB5359: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7691; X-Forefront-PRVS: 0373D94D15 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)(346002)(396003)(39850400004)(376002)(366004)(136003)(316002)(66556008)(86362001)(66476007)(33656002)(2906002)(5660300002)(66946007)(52116002)(186003)(54906003)(1076003)(26005)(478600001)(81156014)(6916009)(2616005)(9786002)(9746002)(36756003)(8676002)(8936002)(4326008)(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: QH9s/LBc5Nra4IzSrdJsaMkt5dMeB+yiyZlUV2bVS6voo0HOq2bVuS5hqvtShtUxZIxp+VJ/pf47677ahTrFuS3ynuUr9Gekqk463UH0ygbTfPDYbwkUGx0jitlFq+WFkm/191pVjPIO/NSv0z5MYg== X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: 500b2187-d924-4360-f311-08d7e072610f X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Apr 2020 12:50:15.6992 (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: BB/tvSxAsfhvWITnRBJPCc8hvB8NBDkv525wju8MXVzaoIT5GgUUFc142JTM8KiBdpn4shh+b9TKYuwsp+NEbA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR05MB5359 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Apr 14, 2020 at 12:34:35PM +0200, Håkon Bugge wrote: > >>>> Shall I make a v2 base on next based on this idea, or do you have > >>>> something coming? > >>> > >>> Sure, I have nothing :) > >>> > >>> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still > >>> retain pointers to the rdma_cm_id it destroys inside the struct > >>> ucma_context, don't we? > >> > >> On entry from user-space, we use the u32 id and looks it up in the > >> XArray. But if rdma_destoy_id() is called asynchronously called > >> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we > >> are toast. > > > > Is that what happens on the addr_handler path? > > No, there, the main problem is the revert of the state > transitions. The first transition enables rdma_resolve_route() to > pass its gate (i.e. state == ADDR_RESOLVED). Then it thinks the > address is resolved, but the addr_handler changes its mind > afterwards. That is a problem, but the call to rdma_destroy_id looks like another problem Jason