PCI: Assign resources before drivers claim devices (pci_scan_root_bus())

Previously, pci_scan_root_bus() created a root PCI bus, enumerated the
devices on it, and called pci_bus_add_devices(), which made the devices
available for drivers to claim them.

Most callers assigned resources to devices after pci_scan_root_bus()
returns, which may be after drivers have claimed the devices. This is
incorrect; the PCI core should not change device resources while a driver
is managing the device.

Remove pci_bus_add_devices() from pci_scan_root_bus() and do it after any
resource assignment in the callers.

Note that ARM's pci_common_init_dev() already called pci_bus_add_devices()
after pci_scan_root_bus(), so we only need to remove the first call:

pci_common_init_dev
pcibios_init_hw
pci_scan_root_bus
pci_bus_add_devices # first call
pci_bus_assign_resources
pci_bus_add_devices # second call

[bhelgaas: changelog, drop "root_bus" var in alpha common_init_pci(),
return failure earlier in mn10300, add "return" in x86 pcibios_scan_root(),
return early if xtensa platform_pcibios_fixup() fails]
Signed-off-by: Yijing Wang <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
CC: Richard Henderson <[e-mail]>
CC: Ivan Kokshaysky <[e-mail]>
CC: Matt Turner <[e-mail]>
CC: David Howells <[e-mail]>
CC: Tony Luck <[e-mail]>
CC: Michal Simek <[e-mail]>
CC: Ralf Baechle <[e-mail]>
CC: Koichi Yasutake <[e-mail]>
CC: Sebastian Ott <[e-mail]>
CC: "David S. Miller" <[e-mail]>
CC: Chris Metcalf <[e-mail]>
CC: Chris Zankel <[e-mail]>
CC: Max Filippov <[e-mail]>
CC: Thomas Gleixner <[e-mail]>

arch/alpha/kernel/pci.c

···
 
 		bus = pci_scan_root_bus(NULL, next_busno, alpha_mv.pci_ops,
 					hose, &resources);
+		if (!bus)
+			continue;
 		hose->bus = bus;
 		hose->need_domain_info = need_domain_info;
 		next_busno = bus->busn_res.end + 1;
···
 
 	pci_assign_unassigned_resources();
 	pci_fixup_irqs(alpha_mv.pci_swizzle, alpha_mv.pci_map_irq);
+	for (hose = hose_head; hose; hose = hose->next) {
+		bus = hose->bus;
+		if (bus)
+			pci_bus_add_devices(bus);
+	}
 }
 
 

arch/frv/mb93090-mb00/pci-vdk.c

···
 
 int __init pcibios_init(void)
 {
+	struct pci_bus *bus;
 	struct pci_ops *dir = NULL;
 	LIST_HEAD(resources);
 
···
 	printk("PCI: Probing PCI hardware\n");
 	pci_add_resource(&resources, &pci_ioport_resource);
 	pci_add_resource(&resources, &pci_iomem_resource);
-	pci_scan_root_bus(NULL, 0, pci_root_ops, NULL, &resources);
+	bus = pci_scan_root_bus(NULL, 0, pci_root_ops, NULL, &resources);
 
 	pcibios_irq_init();
 	pcibios_fixup_irqs();
 	pcibios_resource_survey();
+	if (!bus)
+		return 0;
 
+	pci_bus_add_devices(bus);
 	return 0;
 }
 

arch/ia64/sn/kernel/io_init.c

···
  	if (bus == NULL) {
 		kfree(res);
 		kfree(controller);
+		return;
 	}
+	pci_bus_add_devices(bus);
 }
 
 /*

arch/microblaze/pci/pci-common.c

···
 
 	/* Call common code to handle resource allocation */
 	pcibios_resource_survey();
+	list_for_each_entry_safe(hose, tmp, &hose_list, list_node) {
+		if (hose->bus)
+			pci_bus_add_devices(hose->bus);
+	}
 
 	return 0;
 }

arch/mips/pci/pci.c

···
 			pci_bus_size_bridges(bus);
 			pci_bus_assign_resources(bus);
 		}
+		pci_bus_add_devices(bus);
 	}
 }
 

arch/mn10300/unit-asb2305/pci.c

···
 {
 	resource_size_t io_offset, mem_offset;
 	LIST_HEAD(resources);
+	struct pci_bus *bus;
 
 	ioport_resource.start	= 0xA0000000;
 	ioport_resource.end	= 0xDFFFFFFF;
···
 
 	pci_add_resource_offset(&resources, &pci_ioport_resource, io_offset);
 	pci_add_resource_offset(&resources, &pci_iomem_resource, mem_offset);
-	pci_scan_root_bus(NULL, 0, &pci_direct_ampci, NULL, &resources);
+	bus = pci_scan_root_bus(NULL, 0, &pci_direct_ampci, NULL, &resources);
+	if (!bus)
+		return 0;
 
 	pcibios_irq_init();
 	pcibios_fixup_irqs();
 	pcibios_resource_survey();
+	pci_bus_add_devices(bus);
 	return 0;
 }
 

arch/s390/pci/pci.c

···
 		zpci_cleanup_bus_resources(zdev);
 		return -EIO;
 	}
-
 	zdev->bus->max_bus_speed = zdev->max_bus_speed;
+	pci_bus_add_devices(zdev->bus);
 	return 0;
 }
 

arch/sh/drivers/pci/pci.c

···
 
 		pci_bus_size_bridges(bus);
 		pci_bus_assign_resources(bus);
+		pci_bus_add_devices(bus);
 	} else {
 		pci_free_resource_list(&resources);
 	}

arch/sparc/kernel/leon_pci.c

···
 
 		/* Assign devices with resources */
 		pci_assign_unassigned_resources();
+		pci_bus_add_devices(root_bus);
 	} else {
 		pci_free_resource_list(&resources);
 	}

arch/tile/kernel/pci.c

···
 			struct pci_bus *next_bus;
 			struct pci_dev *dev;
 
+			pci_bus_add_devices(root_bus);
+
 			list_for_each_entry(dev, &root_bus->devices, bus_list) {
 				/*
 				 * Find the PCI host controller, ie. the 1st

arch/tile/kernel/pci_gx.c

···
 alloc_mem_map_failed:
 			break;
 		}
+
+		pci_bus_add_devices(root_bus);
 	}
 
 	return 0;

arch/x86/pci/common.c

···
 	if (!bus) {
 		pci_free_resource_list(&resources);
 		kfree(sd);
+		return;
 	}
+	pci_bus_add_devices(bus);
 }
 
 void __init pcibios_set_cache_line_size(void)

arch/xtensa/kernel/pci.c

···
 	struct pci_controller *pci_ctrl;
 	struct list_head resources;
 	struct pci_bus *bus;
-	int next_busno = 0;
+	int next_busno = 0, ret;
 
 	printk("PCI: Probing PCI hardware\n");
 
···
 		pci_controller_apertures(pci_ctrl, &resources);
 		bus = pci_scan_root_bus(NULL, pci_ctrl->first_busno,
 					pci_ctrl->ops, pci_ctrl, &resources);
+		if (!bus)
+			continue;
+
 		pci_ctrl->bus = bus;
 		pci_ctrl->last_busno = bus->busn_res.end;
 		if (next_busno <= pci_ctrl->last_busno)
 			next_busno = pci_ctrl->last_busno+1;
 	}
 	pci_bus_count = next_busno;
+	ret = platform_pcibios_fixup();
+	if (ret)
+		return ret;
 
-	return platform_pcibios_fixup();
+	for (pci_ctrl = pci_ctrl_head; pci_ctrl; pci_ctrl = pci_ctrl->next) {
+		if (pci_ctrl->bus)
+			pci_bus_add_devices(pci_ctrl->bus);
+	}
+
+	return 0;
 }
 
 subsys_initcall(pcibios_init);

drivers/pci/host/pci-versatile.c

···
 
 	pci_fixup_irqs(pci_common_swizzle, of_irq_parse_and_map_pci);
 	pci_assign_unassigned_bus_resources(bus);
+	pci_bus_add_devices(bus);
 
 	return 0;
 }

drivers/pci/probe.c

···
 	if (!found)
 		pci_bus_update_busn_res_end(b, max);
 
-	pci_bus_add_devices(b);
 	return b;
 }
 EXPORT_SYMBOL(pci_scan_root_bus);