From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B291ECE562 for ; Tue, 25 Sep 2018 18:51:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 225F92086B for ; Tue, 25 Sep 2018 18:51:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 225F92086B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=deltatee.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727581AbeIZBAS (ORCPT ); Tue, 25 Sep 2018 21:00:18 -0400 Received: from ale.deltatee.com ([207.54.116.67]:44166 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727083AbeIZBAR (ORCPT ); Tue, 25 Sep 2018 21:00:17 -0400 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.89) (envelope-from ) id 1g4sQP-0004TR-Sc; Tue, 25 Sep 2018 12:51:10 -0600 To: Bart Van Assche , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org Cc: Stephen Bates , Christoph Hellwig , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , Alex Williamson , =?UTF-8?Q?Christian_K=c3=b6nig?= , Jens Axboe References: <20180925162231.4354-1-logang@deltatee.com> <20180925162231.4354-3-logang@deltatee.com> <1537896555.11137.22.camel@acm.org> <9241a6af-9826-d1ff-c13b-882cb3b6a34a@deltatee.com> <1537900280.11137.30.camel@acm.org> From: Logan Gunthorpe Message-ID: <834b26a8-545c-98e0-fd95-231b701abae6@deltatee.com> Date: Tue, 25 Sep 2018 12:51:09 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <1537900280.11137.30.camel@acm.org> Content-Type: text/plain; charset=UTF-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: axboe@kernel.dk, christian.koenig@amd.com, alex.williamson@redhat.com, benh@kernel.crashing.org, jglisse@redhat.com, dan.j.williams@intel.com, maxg@mellanox.com, jgg@mellanox.com, bhelgaas@google.com, sagi@grimberg.me, keith.busch@intel.com, hch@lst.de, sbates@raithlin.com, linux-block@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, bvanassche@acm.org X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 02/13] PCI/P2PDMA: Add sysfs group to display p2pmem stats X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-09-25 12:31 p.m., Bart Van Assche wrote: > On Tue, 2018-09-25 at 12:15 -0600, Logan Gunthorpe wrote: >> On 2018-09-25 11:29 a.m., Bart Van Assche wrote: >>> On Tue, 2018-09-25 at 10:22 -0600, Logan Gunthorpe wrote: >>>> @@ -83,9 +132,14 @@ static int pci_p2pdma_setup(struct pci_dev *pdev) >>>> >>>> pdev->p2pdma = p2p; >>>> >>>> + error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); >>>> + if (error) >>>> + goto out_pool_destroy; >>>> + >>>> return 0; >>>> >>>> out_pool_destroy: >>>> + pdev->p2pdma = NULL; >>>> gen_pool_destroy(p2p->pool); >>>> out: >>>> devm_kfree(&pdev->dev, p2p); >>> >>> This doesn't look right to me. Shouldn't devm_remove_action() be called instead >>> of devm_kfree() if sysfs_create_group() fails? >> >> That makes no sense to me. We are reversing a devm_kzalloc() not a >> custom action.... > > In case what I wrote was not clear: both devm_kzalloc() and > devm_add_action_or_reset() have to be reversed if sysfs_create_group() fails. > devm_add_action_or_reset() calls devres_add(). The latter function adds an > element to the dev->devres_head list. So I think that only calling devm_kfree() > if sysfs_create_group() fails will lead to corruption of the dev->devres_head > list. I don't see how it would corrupt the list. devres_remove() uses list_del_init() which doesn't require that you only remove the tail from the list... The way I read the code, you can remove any devm action at any time. Logan