From patchwork Thu Mar 30 16:24:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 13194553 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 A587BC77B6F for ; Thu, 30 Mar 2023 16:28:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231590AbjC3Q2m (ORCPT ); Thu, 30 Mar 2023 12:28:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231700AbjC3Q2f (ORCPT ); Thu, 30 Mar 2023 12:28:35 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 432A8BB9C; Thu, 30 Mar 2023 09:28:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1680193712; x=1711729712; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=mMeyztJwnpsG6WpiZZE3Wzd++aYBpdo5TdtsAUuwHek=; b=UeetYP0z4KQE3eGjgEb1rZcZdEKa4Zt/lw25k6ICMVHP/gr5WLpuWQOv vHX230IkzboLjCyY0SQaC5V2mklJtqcbYRk2INBRiPU+nUZ2ThENiWsQl QjVZ5ibEfB6QA9H2UxZ8Z3lAFcYb+cVp+jJSkiiHMmVkMr1XHd/axlD3J 3JHxWBMqslYXAnMN15EbgPmZAp1alUykAZS6TnuASxRudTBpBTdr4LXG/ 0kqpNQWr3EUMkEcrs+OLeQYpHrCj5mOTQr8ShpTdUC6iUyfiIoVSwlr14 MPiOzkt1azTtcvTJEyW41A0oyLudH1otqOsj8j/Ds4aW4rMZ3DlizoKzE g==; X-IronPort-AV: E=McAfee;i="6600,9927,10665"; a="427496059" X-IronPort-AV: E=Sophos;i="5.98,305,1673942400"; d="scan'208";a="427496059" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Mar 2023 09:28:31 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10665"; a="684762351" X-IronPort-AV: E=Sophos;i="5.98,305,1673942400"; d="scan'208";a="684762351" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga002.jf.intel.com with ESMTP; 30 Mar 2023 09:28:19 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 43047238; Thu, 30 Mar 2023 19:24:51 +0300 (EEST) From: Andy Shevchenko To: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Andy Shevchenko , =?utf-8?q?Krzysztof_Wi?= =?utf-8?q?lczy=C5=84ski?= , Mika Westerberg , Michael Ellerman , Randy Dunlap , Arnd Bergmann , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Niklas Schnelle , Bjorn Helgaas , "Rafael J. Wysocki" , =?utf-8?q?Pali_Roh=C3=A1r?= , "Maciej W. Rozycki" , Juergen Gross , Dominik Brodowski , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org Cc: Miguel Ojeda , Richard Henderson , Ivan Kokshaysky , Matt Turner , Russell King , Andrew Lunn , Sebastian Hesselbarth , Gregory Clement , Thomas Bogendoerfer , Nicholas Piggin , Christophe Leroy , Anatolij Gustschin , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , "David S. Miller" , Bjorn Helgaas , Stefano Stabellini , Oleksandr Tyshchenko Subject: [PATCH v8 4/7] PCI: Document pci_bus_for_each_resource() to avoid confusion Date: Thu, 30 Mar 2023 19:24:31 +0300 Message-Id: <20230330162434.35055-5-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.40.0.1.gaa8946217a0b In-Reply-To: <20230330162434.35055-1-andriy.shevchenko@linux.intel.com> References: <20230330162434.35055-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org There might be a confusion with the implementation of the pci_bus_for_each_resources() due to side effect of Logical OR. Document entire macro and explain how it works and why the conditional needs to be like that. Signed-off-by: Andy Shevchenko --- include/linux/pci.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/include/linux/pci.h b/include/linux/pci.h index 5cacd9e4c8cd..e3b3af606280 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1446,6 +1446,26 @@ int devm_request_pci_bus_resources(struct device *dev, /* Temporary until new and working PCI SBR API in place */ int pci_bridge_secondary_bus_reset(struct pci_dev *dev); +/** + * pci_bus_for_each_resource - iterate over PCI bus resources + * @bus: the PCI bus + * @res: a varible to keep a pointer to the current resource + * @i: a variable to keep the index of the current resource + * + * Iterate over PCI bus resources. The first part is to go over PCI bus + * resource array, which has at most the %PCI_BRIDGE_RESOURCE_NUM entries. + * After that continue with the separate list of the additional resources, + * if not empty. That's why the Logical OR is being used. + * + * Possible usage: + * + * struct pci_bus *bus = ...; + * struct resource *res; + * unsigned int i; + * + * pci_bus_for_each_resource(bus, res, i) + * pr_info("PCI bus resource[%u]: %pR\n", i, res); + */ #define pci_bus_for_each_resource(bus, res, i) \ for (i = 0; \ (res = pci_bus_resource_n(bus, i)) || i < PCI_BRIDGE_RESOURCE_NUM; \