Commit ceb928be authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Bjorn Helgaas
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PCI: Document pci_bus_for_each_resource() 

There might be confusion about why pci_bus_for_each_resource() uses
Logical OR. Document the entire macro and explain how it works and why the
conditional needs to be like that.

Link: https://lore.kernel.org/r/20230330162434.35055-5-andriy.shevchenko@linux.intel.com


Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 09cc9006

include/linux/pci.h

+20 −0
Original line number Diff line number Diff line
@@ -1444,6 +1444,26 @@ 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: pointer to the current resource

 * @i: 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; \