From patchwork Fri Apr 22 13:28:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Niklas Schnelle X-Patchwork-Id: 12823425 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 0F87FC4332F for ; Fri, 22 Apr 2022 13:29:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1447980AbiDVNcC (ORCPT ); Fri, 22 Apr 2022 09:32:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33234 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1447856AbiDVNcB (ORCPT ); Fri, 22 Apr 2022 09:32:01 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1C69583BB; Fri, 22 Apr 2022 06:29:08 -0700 (PDT) Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 23MDLuN2020821; 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Fri, 22 Apr 2022 13:28:58 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 22 Apr 2022 13:28:58 +0000 (GMT) From: Niklas Schnelle To: Bjorn Helgaas , Jan Kiszka , Matthew Rosato , Pierre Morel Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, linux-pci@vger.kernel.org Subject: [PATCH v4 1/4] PCI: Clean up pci_scan_slot() Date: Fri, 22 Apr 2022 15:28:55 +0200 Message-Id: <20220422132858.1213022-2-schnelle@linux.ibm.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220422132858.1213022-1-schnelle@linux.ibm.com> References: <20220422132858.1213022-1-schnelle@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: dnp3dCls5ZVMednp3QkN4U9N-PXrMb3n X-Proofpoint-GUID: Grp4JBmf5BJNU_Q_4dhxkQKcUMT2FlVT X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-04-22_03,2022-04-22_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 mlxscore=0 spamscore=0 malwarescore=0 mlxlogscore=826 adultscore=0 bulkscore=0 clxscore=1015 phishscore=0 impostorscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2204220058 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org While determining the next PCI function is factored out of pci_scan_slot() into next_fn() the former still handles the first function as a special case. This duplicates the code from the scan loop. Furthermore the non ARI branch of next_fn() is generally hard to understand and especially the check for multifunction devices is hidden in the handling of NULL devices for non-contiguous multifunction. It also signals that no further functions need to be scanned by returning 0 via wraparound and this is a valid function number. Improve upon this by transforming the conditions in next_fn() to be easier to understand. By changing next_fn() to return -ENODEV instead of 0 when there is no next function we can then handle the initial function inside the loop and deduplicate the shared handling. This also makes it more explicit that only function 0 must exist. No functional change is intended. Cc: Jan Kiszka Signed-off-by: Niklas Schnelle --- drivers/pci/probe.c | 39 ++++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 17a969942d37..2000e9858f12 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2579,8 +2579,7 @@ struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn) } EXPORT_SYMBOL(pci_scan_single_device); -static unsigned int next_fn(struct pci_bus *bus, struct pci_dev *dev, - unsigned int fn) +static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn) { int pos; u16 cap = 0; @@ -2588,24 +2587,27 @@ static unsigned int next_fn(struct pci_bus *bus, struct pci_dev *dev, if (pci_ari_enabled(bus)) { if (!dev) - return 0; + return -ENODEV; + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI); if (!pos) - return 0; + return -ENODEV; pci_read_config_word(dev, pos + PCI_ARI_CAP, &cap); next_fn = PCI_ARI_CAP_NFN(cap); if (next_fn <= fn) - return 0; /* protect against malformed list */ + return -ENODEV; /* protect against malformed list */ return next_fn; } + if (fn >= 7) + return -ENODEV; - /* dev may be NULL for non-contiguous multifunction devices */ - if (!dev || dev->multifunction) - return (fn + 1) % 8; + /* only multifunction devices may have more functions */ + if (dev && !dev->multifunction) + return -ENODEV; - return 0; + return fn + 1; } static int only_one_child(struct pci_bus *bus) @@ -2643,26 +2645,25 @@ static int only_one_child(struct pci_bus *bus) */ int pci_scan_slot(struct pci_bus *bus, int devfn) { - unsigned int fn, nr = 0; struct pci_dev *dev; + int fn = 0, nr = 0; if (only_one_child(bus) && (devfn > 0)) return 0; /* Already scanned the entire slot */ - dev = pci_scan_single_device(bus, devfn); - if (!dev) - return 0; - if (!pci_dev_is_added(dev)) - nr++; - - for (fn = next_fn(bus, dev, 0); fn > 0; fn = next_fn(bus, dev, fn)) { + do { dev = pci_scan_single_device(bus, devfn + fn); if (dev) { if (!pci_dev_is_added(dev)) nr++; - dev->multifunction = 1; + if (fn > 0) + dev->multifunction = 1; + } else if (fn == 0) { + /* function 0 is required */ + break; } - } + fn = next_fn(bus, dev, fn); + } while (fn >= 0); /* Only one slot has PCIe device */ if (bus->self && nr)