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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 23716C54FD0 for ; Tue, 21 Apr 2020 11:11:18 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 97946206E9 for ; Tue, 21 Apr 2020 11:11:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97946206E9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 49618g45tpzDqrM for ; Tue, 21 Apr 2020 21:11:15 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=fbarrat@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 49613l0kzQzDql9 for ; Tue, 21 Apr 2020 21:06:58 +1000 (AEST) Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 03LB2G5U006017 for ; Tue, 21 Apr 2020 07:06:56 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 30gmu7ysr8-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 21 Apr 2020 07:06:56 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 21 Apr 2020 12:06:45 +0100 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 03LB6opL36307070 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Apr 2020 11:06:50 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1EAADA4065; Tue, 21 Apr 2020 11:06:50 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D60F3A4060; Tue, 21 Apr 2020 11:06:49 +0000 (GMT) Received: from pic2.home (unknown [9.145.42.232]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 21 Apr 2020 11:06:49 +0000 (GMT) Subject: Re: [PATCH AUTOSEL 4.19 41/47] powerpc/powernv/ioda: Fix ref count for devices with their own PE To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20200418144227.9802-1-sashal@kernel.org> <20200418144227.9802-41-sashal@kernel.org> From: Frederic Barrat Date: Tue, 21 Apr 2020 13:06:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200418144227.9802-41-sashal@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 20042111-0028-0000-0000-000003FC42BE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20042111-0029-0000-0000-000024C205FC Message-Id: <132624ab-a9ce-cde2-a99c-e86f341195fb@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-21_03:2020-04-20, 2020-04-21 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 priorityscore=1501 spamscore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 mlxscore=0 malwarescore=0 suspectscore=0 mlxlogscore=999 clxscore=1031 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004210084 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, Andrew Donnellan Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 18/04/2020 à 16:42, Sasha Levin a écrit : > From: Frederic Barrat > > [ Upstream commit 05dd7da76986937fb288b4213b1fa10dbe0d1b33 ] Like for kernel 5.4, the patches 41, 42, 43 of this series are not desirable for stable. Fred > The pci_dn structure used to store a pointer to the struct pci_dev, so > taking a reference on the device was required. However, the pci_dev > pointer was later removed from the pci_dn structure, but the reference > was kept for the npu device. > See commit 902bdc57451c ("powerpc/powernv/idoa: Remove unnecessary > pcidev from pci_dn"). > > We don't need to take a reference on the device when assigning the PE > as the struct pnv_ioda_pe is cleaned up at the same time as > the (physical) device is released. Doing so prevents the device from > being released, which is a problem for opencapi devices, since we want > to be able to remove them through PCI hotplug. > > Now the ugly part: nvlink npu devices are not meant to be > released. Because of the above, we've always leaked a reference and > simply removing it now is dangerous and would likely require more > work. There's currently no release device callback for nvlink devices > for example. So to be safe, this patch leaks a reference on the npu > device, but only for nvlink and not opencapi. > > Signed-off-by: Frederic Barrat > Reviewed-by: Andrew Donnellan > Signed-off-by: Michael Ellerman > Link: https://lore.kernel.org/r/20191121134918.7155-2-fbarrat@linux.ibm.com > Signed-off-by: Sasha Levin > --- > arch/powerpc/platforms/powernv/pci-ioda.c | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c > index ecd211c5f24a5..19cd6affdd5fb 100644 > --- a/arch/powerpc/platforms/powernv/pci-ioda.c > +++ b/arch/powerpc/platforms/powernv/pci-ioda.c > @@ -1071,14 +1071,13 @@ static struct pnv_ioda_pe *pnv_ioda_setup_dev_PE(struct pci_dev *dev) > return NULL; > } > > - /* NOTE: We get only one ref to the pci_dev for the pdn, not for the > - * pointer in the PE data structure, both should be destroyed at the > - * same time. However, this needs to be looked at more closely again > - * once we actually start removing things (Hotplug, SR-IOV, ...) > + /* NOTE: We don't get a reference for the pointer in the PE > + * data structure, both the device and PE structures should be > + * destroyed at the same time. However, removing nvlink > + * devices will need some work. > * > * At some point we want to remove the PDN completely anyways > */ > - pci_dev_get(dev); > pdn->pe_number = pe->pe_number; > pe->flags = PNV_IODA_PE_DEV; > pe->pdev = dev; > @@ -1093,7 +1092,6 @@ static struct pnv_ioda_pe *pnv_ioda_setup_dev_PE(struct pci_dev *dev) > pnv_ioda_free_pe(pe); > pdn->pe_number = IODA_INVALID_PE; > pe->pdev = NULL; > - pci_dev_put(dev); > return NULL; > } > > @@ -1213,6 +1211,14 @@ static struct pnv_ioda_pe *pnv_ioda_setup_npu_PE(struct pci_dev *npu_pdev) > struct pci_controller *hose = pci_bus_to_host(npu_pdev->bus); > struct pnv_phb *phb = hose->private_data; > > + /* > + * Intentionally leak a reference on the npu device (for > + * nvlink only; this is not an opencapi path) to make sure it > + * never goes away, as it's been the case all along and some > + * work is needed otherwise. > + */ > + pci_dev_get(npu_pdev); > + > /* > * Due to a hardware errata PE#0 on the NPU is reserved for > * error handling. This means we only have three PEs remaining > @@ -1236,7 +1242,6 @@ static struct pnv_ioda_pe *pnv_ioda_setup_npu_PE(struct pci_dev *npu_pdev) > */ > dev_info(&npu_pdev->dev, > "Associating to existing PE %x\n", pe_num); > - pci_dev_get(npu_pdev); > npu_pdn = pci_get_pdn(npu_pdev); > rid = npu_pdev->bus->number << 8 | npu_pdn->devfn; > npu_pdn->pe_number = pe_num; >