Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3462BC7619A for ; Tue, 21 Mar 2023 14:48:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231272AbjCUOsX (ORCPT ); Tue, 21 Mar 2023 10:48:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229687AbjCUOsV (ORCPT ); Tue, 21 Mar 2023 10:48:21 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B9213FB80; Tue, 21 Mar 2023 07:48:19 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4PgvZb3h7Mz6J6vG; Tue, 21 Mar 2023 22:47:03 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Tue, 21 Mar 2023 14:48:14 +0000 Date: Tue, 21 Mar 2023 14:48:13 +0000 From: Jonathan Cameron To: Davidlohr Bueso CC: , , , , , , , , , , , , , Subject: Re: [PATCH 2/4] cxl/pci: Find and register CXL PMU devices Message-ID: <20230321144813.00002c19@Huawei.com> In-Reply-To: <20230307023656.cyntxctzqgpam5u3@offworld> References: <20230303175022.10806-1-Jonathan.Cameron@huawei.com> <20230303175022.10806-3-Jonathan.Cameron@huawei.com> <20230307023656.cyntxctzqgpam5u3@offworld> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100006.china.huawei.com (7.191.160.224) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 6 Mar 2023 18:36:56 -0800 Davidlohr Bueso wrote: > On Fri, 03 Mar 2023, Jonathan Cameron wrote: > > >+int devm_cxl_cpmu_add(struct device *parent, struct cxl_cpmu_regs *regs, int index) > >+{ > >+ struct cxl_cpmu *cpmu; > >+ struct device *dev; > >+ int rc; > >+ > >+ cpmu = kzalloc(sizeof(*cpmu), GFP_KERNEL); > >+ if (!cpmu) > >+ return -ENOMEM; > >+ > >+ cpmu->base = regs->cpmu; > >+ dev = &cpmu->dev; > >+ device_initialize(dev); > >+ device_set_pm_not_required(dev); > >+ dev->parent = parent; > >+ dev->bus = &cxl_bus_type; > >+ dev->type = &cxl_cpmu_type; > >+ rc = ida_alloc(&cpmu_ida, GFP_KERNEL); > >+ if (rc < 0) > >+ goto err; > > Probably better to do the ida_alloc after the cpmu allocation above, before > arming the dev. Hi Davidlohr, There was a bug hiding here I think as the device_put() could cause the ida to be freed even though the ida_alloc() failed. Good you pointed out this oddity. Moving the ida_alloc earlier requires an explicit free of the cpmu but that's easy enough to locally to that if (rc < 0) Thanks, Jonathan