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Mon, 22 Jun 2020 13:05:25 +0000 Date: Mon, 22 Jun 2020 10:05:20 -0300 From: Jason Gunthorpe To: Maor Gottlieb Cc: Leon Romanovsky , Doug Ledford , linux-rdma@vger.kernel.org Subject: Re: [PATCH rdma-next 2/2] RDMA/core: Optimize XRC target lookup Message-ID: <20200622130520.GE2590509@mellanox.com> References: <20200621104110.53509-1-leon@kernel.org> <20200621104110.53509-3-leon@kernel.org> <20200622122910.GB2590509@mellanox.com> <3ee325e8-6872-22a8-4f2b-e1740d15a194@mellanox.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3ee325e8-6872-22a8-4f2b-e1740d15a194@mellanox.com> X-ClientProxiedBy: MN2PR22CA0007.namprd22.prod.outlook.com (2603:10b6:208:238::12) 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 (156.34.48.30) by MN2PR22CA0007.namprd22.prod.outlook.com (2603:10b6:208:238::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3109.22 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: P9npKMQajmBaM6kYIj8P0St25XNd8X+oYmVuXqbXSPTWpPeGNlZPImFS8vJc5j/cBukX2Ep0JhYksDiSQTf3Cxp/dJT/bpw/fly+kLuo5GO2nRpb7tM6vpXWndpv2QA6RVNT6gqgDq3g60obVSuFnDFT+/QQd8tdDYKqgboE/aPLMqdS8FsyZIWvMnSKiWcXua/rRRo/XQNedsBJErLlFH1LljGPq8OjyVgaW/bxs904UrUiHadZwNNHyvOCQqvK4gLFYVjH/vwTeSYDXoXcbhIGxrRX34aFWrH4Y2EclDpWACfwloMx/EXk6Z5+9hxFDeOlQuEKqp3zgog7fm1huHwPYpbmcFSem1cjt5mE9vCzBBOB09sEW/9zyDAA8XSZlteXs71jZBpZE57P95bEy4c1OcJo2NEYau4/2XcUdqbF43Egr/B8QtRcIHhAX/GaQGyXp3nWJiJALEhrvg3zFZif7Jmq20F+zTksTudckc8= X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: 161f7f13-7aa6-4654-7bfc-08d816aced58 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jun 2020 13:05:25.1216 (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: dEIhMpk3UKmkV6PoT5t9HpzJYwV3Vn+d95AWt9ecuzXH+7FEQxkE+m6PyQBYLdfIxby1JIlhT8DfYaFVMxlqDw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR05MB3486 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Mon, Jun 22, 2020 at 03:57:29PM +0300, Maor Gottlieb wrote: > > On 6/22/2020 3:29 PM, Jason Gunthorpe wrote: > > On Sun, Jun 21, 2020 at 01:41:10PM +0300, Leon Romanovsky wrote: > > > @@ -2318,19 +2313,18 @@ EXPORT_SYMBOL(ib_alloc_xrcd_user); > > > int ib_dealloc_xrcd_user(struct ib_xrcd *xrcd, struct ib_udata *udata) > > > { > > > + unsigned long index; > > > struct ib_qp *qp; > > > int ret; > > > if (atomic_read(&xrcd->usecnt)) > > > return -EBUSY; > > > - while (!list_empty(&xrcd->tgt_qp_list)) { > > > - qp = list_entry(xrcd->tgt_qp_list.next, struct ib_qp, xrcd_list); > > > + xa_for_each(&xrcd->tgt_qps, index, qp) { > > > ret = ib_destroy_qp(qp); > > > if (ret) > > > return ret; > > > } > > Why doesn't this need to hold the tgt_qps_rwsem? > > > > Jason > > Actually, we don't need this part of code. if usecnt is zero so we don't > have any tgt qp in the list. I guess it is leftovers of ib_release_qp which > was already deleted. Then have a WARN_ON that the xarray is empty Jason