Commit f2a230bd authored Aug 02, 2013 by Wei Yang Committed by Bjorn Helgaas Aug 02, 2013

PCI: Enumerate subordinate buses, not devices, in pci_bus_get_depth()

Normally, on one PCI bus there would be more devices than bridges. When
calculating the depth of a PCI bus, it would be more time efficient to
enumerating through the child buses instead of the child devices.

Also by doing so, the code seems more self explaining. Previously, it went
through the devices and checked whether a bridge introduced a child bus or
not, which needs more background knowledge to understand it.

This patch calculates the depth by enumerating the bus hierarchy.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

parent 3b2f64d0

drivers/pci/setup-bus.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -1300,15 +1300,12 @@ static void pci_bus_dump_resources(struct pci_bus *bus)
		static int __init pci_bus_get_depth(struct pci_bus *bus)
		{
		int depth = 0;
		struct pci_dev *dev;
		struct pci_bus *child_bus;

		list_for_each_entry(dev, &bus->devices, bus_list) {
		list_for_each_entry(child_bus, &bus->children, node){
		int ret;
		struct pci_bus *b = dev->subordinate;
		if (!b)
		continue;

		ret = pci_bus_get_depth(b);
		ret = pci_bus_get_depth(child_bus);
		if (ret + 1 > depth)
		depth = ret + 1;
		}

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