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 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 9260EC433EF for ; Wed, 13 Jun 2018 12:12:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45E2F20020 for ; Wed, 13 Jun 2018 12:12:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45E2F20020 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 S935454AbeFMMM3 (ORCPT ); Wed, 13 Jun 2018 08:12:29 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49164 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S935261AbeFMMM1 (ORCPT ); Wed, 13 Jun 2018 08:12:27 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1F8F54000D0B; Wed, 13 Jun 2018 12:12:27 +0000 (UTC) Received: from gondolin (dhcp-192-215.str.redhat.com [10.33.192.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id A1964202322E; Wed, 13 Jun 2018 12:12:23 +0000 (UTC) Date: Wed, 13 Jun 2018 14:12:21 +0200 From: Cornelia Huck To: Pierre Morel Cc: Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com Subject: Re: [PATCH v5 04/13] s390: vfio-ap: base implementation of VFIO AP device driver Message-ID: <20180613141221.5b924348.cohuck@redhat.com> In-Reply-To: <7237751c-66b5-d14c-5b71-cc1cfc79db87@linux.ibm.com> References: <1525705912-12815-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1525705912-12815-5-git-send-email-akrowiak@linux.vnet.ibm.com> <889b8d41-e08c-0eb5-2de0-a1d6669a03b3@linux.ibm.com> <20180613094812.1fd1846d.cohuck@redhat.com> <41e7ccbd-f6f5-ba20-f236-7824c682994d@linux.ibm.com> <20180613131402.0305d092.cohuck@redhat.com> <7237751c-66b5-d14c-5b71-cc1cfc79db87@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 13 Jun 2018 12:12:27 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 13 Jun 2018 12:12:27 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'cohuck@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 Jun 2018 14:01:54 +0200 Pierre Morel wrote: > On 13/06/2018 13:14, Cornelia Huck wrote: > > On Wed, 13 Jun 2018 12:54:40 +0200 > > Pierre Morel wrote: > > > >> On 13/06/2018 09:48, Cornelia Huck wrote: > >>> On Wed, 13 Jun 2018 09:41:16 +0200 > >>> Pierre Morel wrote: > >>> > >>>> On 07/05/2018 17:11, Tony Krowiak wrote: > >>>>> Introduces a new AP device driver. This device driver > >>>>> is built on the VFIO mediated device framework. The framework > >>>>> provides sysfs interfaces that facilitate passthrough > >>>>> access by guests to devices installed on the linux host. > >>>> ...snip... > >>>> > >>>>> +static int vfio_ap_matrix_dev_create(void) > >>>>> +{ > >>>>> + int ret; > >>>>> + > >>>>> + vfio_ap_root_device = root_device_register(VFIO_AP_ROOT_NAME); > >>>>> + > >>>>> + if (IS_ERR(vfio_ap_root_device)) { > >>>>> + ret = PTR_ERR(vfio_ap_root_device); > >>>>> + goto done; > >>>>> + } > >>>>> + > >>>>> + ap_matrix = kzalloc(sizeof(*ap_matrix), GFP_KERNEL); > >>>>> + if (!ap_matrix) { > >>>>> + ret = -ENOMEM; > >>>>> + goto matrix_alloc_err; > >>>>> + } > >>>>> + > >>>>> + ap_matrix->device.type = &vfio_ap_dev_type; > >>>>> + dev_set_name(&ap_matrix->device, "%s", VFIO_AP_DEV_NAME); > >>>>> + ap_matrix->device.parent = vfio_ap_root_device; > >>>>> + ap_matrix->device.release = vfio_ap_matrix_dev_release; > >>>>> + ap_matrix->device.driver = &vfio_ap_drv.driver; > >>>>> + > >>>>> + ret = device_register(&ap_matrix->device); > >>>>> + if (ret) > >>>>> + goto matrix_reg_err; > >>>>> + > >>>>> + goto done; > >>>>> + > >>>>> +matrix_reg_err: > >>>>> + put_device(&ap_matrix->device); > >>>> Did not see this before but here you certainly want to > >>>> do a kfree and not a put_device. > >>> No, this must not be a kfree. Once you've tried to register something > >>> embedding a struct device with the driver core, you need to use > >>> put_device, as another path may have acquired a reference, even if > >>> registering ultimately failed. See the comment for device_register(). > >>> IOW, the code is correct. > >> learned something again :) , > >> but still, a kfree is needed for the kzalloc. > >> Does'nt it? > > No, the put callback for the embedding structure needs to take care of > > freeing things. Otherwise it is buggy. > > Seems buggy to me. > How does the put_device knows if it is embedded and then in what it is > embedded ? It does not need to know; the code registering the structure needs to set up device->release correctly. > > > > >>> > >>>> > >>>>> + > >>>>> +matrix_alloc_err: > >>>>> + root_device_unregister(vfio_ap_root_device); > >>>>> + > >>>>> +done: > >>>>> + return ret; > >>>>> +} > >>>>> + > >>>>> +static void vfio_ap_matrix_dev_destroy(struct ap_matrix *ap_matrix) > >>>>> +{ > >>>>> + device_unregister(&ap_matrix->device); > >>>>> + root_device_unregister(vfio_ap_root_device); > >>>> Also here you need a kfree(ap_matrix) too . > >>> Same here. > >>> > >