From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko 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> References: <20230330162434.35055-1-andriy.shevchenko@linux.intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: 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==; In-Reply-To: <20230330162434.35055-1-andriy.shevchenko@linux.intel.com> List-ID: Content-Type: text/plain; charset="us-ascii" To: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Andy Shevchenko , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Mika Westerberg , Michael Ellerman , Randy Dunlap , Arnd Bergmann , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Niklas Schnelle , Bjorn Helgaas , "Rafael J. Wysocki" , =?UTF-8?q?Pali=20Roh=C3=A1r?= , "Maciej W. Rozycki" , Juergen Gross , Dominik Brodowski , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@list 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 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; \ -- 2.40.0.1.gaa8946217a0b