PCI: Add for_each_pci_bridge() helper

The following pattern is often used:

  list_for_each_entry(dev, &bus->devices, bus_list) {
    if (pci_is_bridge(dev)) {
      ...
    }
  }

Add a for_each_pci_bridge() helper to make that code easier to write and
read by reducing indentation level.  It also saves one or few lines of code
in each occurrence.

Convert PCI core parts here at the same time.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[bhelgaas: fold in http://lkml.kernel.org/r/20171013165352.25550-1-andriy.shevchenko@linux.intel.com]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/hotplug/acpiphp_glue.c

@@ -462,18 +462,15 @@ static void enable_slot(struct acpiphp_slot *slot)
 	acpiphp_rescan_slot(slot);
 	max = acpiphp_max_busnr(bus);
 	for (pass = 0; pass < 2; pass++) {
-		list_for_each_entry(dev, &bus->devices, bus_list) {
+		for_each_pci_bridge(dev, bus) {
 			if (PCI_SLOT(dev->devfn) != slot->device)
 				continue;
 
-			if (pci_is_bridge(dev)) {
-				max = pci_scan_bridge(bus, dev, max, pass);
-				if (pass && dev->subordinate) {
-					check_hotplug_bridge(slot, dev);
-					pcibios_resource_survey_bus(dev->subordinate);
-					__pci_bus_size_bridges(dev->subordinate,
-							       &add_list);
-				}
+			max = pci_scan_bridge(bus, dev, max, pass);
+			if (pass && dev->subordinate) {
+				check_hotplug_bridge(slot, dev);
+				pcibios_resource_survey_bus(dev->subordinate);
+				__pci_bus_size_bridges(dev->subordinate, &add_list);
 			}
 		}
 	}

drivers/pci/hotplug/cpci_hotplug_pci.c

@@ -286,14 +286,11 @@ int cpci_configure_slot(struct slot *slot)
 	}
 	parent = slot->dev->bus;
 
-	list_for_each_entry(dev, &parent->devices, bus_list) {
-		if (PCI_SLOT(dev->devfn) != PCI_SLOT(slot->devfn))
-			continue;
-		if (pci_is_bridge(dev))
+	for_each_pci_bridge(dev, parent) {
+		if (PCI_SLOT(dev->devfn) == PCI_SLOT(slot->devfn))
 			pci_hp_add_bridge(dev);
 	}
 
-
 	pci_assign_unassigned_bridge_resources(parent->self);
 
 	pci_bus_add_devices(parent);

drivers/pci/hotplug/pciehp_pci.c

@@ -60,9 +60,8 @@ int pciehp_configure_device(struct slot *p_slot)
 		goto out;
 	}
 
-	list_for_each_entry(dev, &parent->devices, bus_list)
-		if (pci_is_bridge(dev))
-			pci_hp_add_bridge(dev);
+	for_each_pci_bridge(dev, parent)
+		pci_hp_add_bridge(dev);
 
 	pci_assign_unassigned_bridge_resources(bridge);
 	pcie_bus_configure_settings(parent);

drivers/pci/hotplug/shpchp_pci.c

@@ -61,10 +61,8 @@ int shpchp_configure_device(struct slot *p_slot)
 		goto out;
 	}
 
-	list_for_each_entry(dev, &parent->devices, bus_list) {
-		if (PCI_SLOT(dev->devfn) != p_slot->device)
-			continue;
-		if (pci_is_bridge(dev))
+	for_each_pci_bridge(dev, parent) {
+		if (PCI_SLOT(dev->devfn) == p_slot->device)
 			pci_hp_add_bridge(dev);
 	}
 

drivers/pci/probe.c

@@ -2421,10 +2421,8 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
 	}
 
 	for (pass = 0; pass < 2; pass++)
-		list_for_each_entry(dev, &bus->devices, bus_list) {
-			if (pci_is_bridge(dev))
-				max = pci_scan_bridge(bus, dev, max, pass);
-		}
+		for_each_pci_bridge(dev, bus)
+			max = pci_scan_bridge(bus, dev, max, pass);
 
 	/*
 	 * Make sure a hotplug bridge has at least the minimum requested

drivers/pci/setup-bus.c

@@ -1921,10 +1921,9 @@ void pci_assign_unassigned_bus_resources(struct pci_bus *bus)
 					want additional resources */
 
 	down_read(&pci_bus_sem);
-	list_for_each_entry(dev, &bus->devices, bus_list)
-		if (pci_is_bridge(dev) && pci_has_subordinate(dev))
-				__pci_bus_size_bridges(dev->subordinate,
-							 &add_list);
+	for_each_pci_bridge(dev, bus)
+		if (pci_has_subordinate(dev))
+			__pci_bus_size_bridges(dev->subordinate, &add_list);
 	up_read(&pci_bus_sem);
 	__pci_bus_assign_resources(bus, &add_list, NULL);
 	BUG_ON(!list_empty(&add_list));

drivers/pcmcia/cardbus.c

@@ -77,9 +77,8 @@ int __ref cb_alloc(struct pcmcia_socket *s)
 
 	max = bus->busn_res.start;
 	for (pass = 0; pass < 2; pass++)
-		list_for_each_entry(dev, &bus->devices, bus_list)
-			if (pci_is_bridge(dev))
-				max = pci_scan_bridge(bus, dev, max, pass);
+		for_each_pci_bridge(dev, bus)
+			max = pci_scan_bridge(bus, dev, max, pass);
 
 	/*
 	 * Size all resources below the CardBus controller.

include/linux/pci.h

@@ -596,6 +596,10 @@ static inline bool pci_is_bridge(struct pci_dev *dev)
 		dev->hdr_type == PCI_HEADER_TYPE_CARDBUS;
 }
 
+#define for_each_pci_bridge(dev, bus)				\
+	list_for_each_entry(dev, &bus->devices, bus_list)	\
+		if (!pci_is_bridge(dev)) {} else
+
 static inline struct pci_dev *pci_upstream_bridge(struct pci_dev *dev)
 {
 	dev = pci_physfn(dev);