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

Previously, pci_scan_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_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_bus() and do it after any
resource assignment in the callers.

[bhelgaas: changelog, check for failure in mcf_pci_init()]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Geert Uytterhoeven <geert@linux-m68k.org>
CC: Guan Xuetao <gxt@mprc.pku.edu.cn>
CC: Richard Henderson <rth@twiddle.net>
CC: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
CC: Matt Turner <mattst88@gmail.com>

arch/alpha/kernel/sys_nautilus.c

@@ -207,6 +207,9 @@ nautilus_init_pci(void)
 
 	/* Scan our single hose.  */
 	bus = pci_scan_bus(0, alpha_mv.pci_ops, hose);
+	if (!bus)
+		return;
+
 	hose->bus = bus;
 	pcibios_claim_one_bus(bus);
 
@@ -253,6 +256,7 @@ nautilus_init_pci(void)
 	   for the root bus, so just clear it. */
 	bus->self = NULL;
 	pci_fixup_irqs(alpha_mv.pci_swizzle, alpha_mv.pci_map_irq);
+	pci_bus_add_devices(bus);
 }
 
 /*

arch/m68k/coldfire/pci.c

@@ -313,12 +313,16 @@ static int __init mcf_pci_init(void)
 	schedule_timeout(msecs_to_jiffies(200));
 
 	rootbus = pci_scan_bus(0, &mcf_pci_ops, NULL);
+	if (!rootbus)
+		return -ENODEV;
+
 	rootbus->resource[0] = &mcf_pci_io;
 	rootbus->resource[1] = &mcf_pci_mem;
 
 	pci_fixup_irqs(pci_common_swizzle, mcf_pci_map_irq);
 	pci_bus_size_bridges(rootbus);
 	pci_bus_assign_resources(rootbus);
+	pci_bus_add_devices(rootbus);
 	return 0;
 }
 

arch/sparc/kernel/pcic.c

@@ -391,12 +391,16 @@ static void __init pcic_pbm_scan_bus(struct linux_pcic *pcic)
 	struct linux_pbm_info *pbm = &pcic->pbm;
 
 	pbm->pci_bus = pci_scan_bus(pbm->pci_first_busno, &pcic_ops, pbm);
+	if (!pbm->pci_bus)
+		return;
+
 #if 0 /* deadwood transplanted from sparc64 */
 	pci_fill_in_pbm_cookies(pbm->pci_bus, pbm, pbm->prom_node);
 	pci_record_assignments(pbm, pbm->pci_bus);
 	pci_assign_unassigned(pbm, pbm->pci_bus);
 	pci_fixup_irq(pbm, pbm->pci_bus);
 #endif
+	pci_bus_add_devices(pbm->pci_bus);
 }
 
 /*

arch/unicore32/kernel/pci.c

@@ -266,17 +266,10 @@ static int __init pci_common_init(void)
 	pci_fixup_irqs(pci_common_swizzle, pci_puv3_map_irq);
 
 	if (!pci_has_flag(PCI_PROBE_ONLY)) {
-		/*
-		 * Size the bridge windows.
-		 */
 		pci_bus_size_bridges(puv3_bus);
-
-		/*
-		 * Assign resources.
-		 */
 		pci_bus_assign_resources(puv3_bus);
 	}
-
+	pci_bus_add_devices(puv3_bus);
 	return 0;
 }
 subsys_initcall(pci_common_init);

drivers/pci/hotplug/ibmphp_core.c

@@ -738,7 +738,7 @@ static void ibm_unconfigure_device(struct pci_func *func)
  */
 static u8 bus_structure_fixup(u8 busno)
 {
-	struct pci_bus *bus;
+	struct pci_bus *bus, *b;
 	struct pci_dev *dev;
 	u16 l;
 
@@ -765,7 +765,11 @@ static u8 bus_structure_fixup(u8 busno)
 					(l != 0x0000) && (l != 0xffff)) {
 			debug("%s - Inside bus_structure_fixup()\n",
 							__func__);
-			pci_scan_bus(busno, ibmphp_pci_bus->ops, NULL);
+			b = pci_scan_bus(busno, ibmphp_pci_bus->ops, NULL);
+			if (!b)
+				continue;
+
+			pci_bus_add_devices(b);
 			break;
 		}
 	}

drivers/pci/probe.c

@@ -2123,7 +2123,6 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
 	b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
 	if (b) {
 		pci_scan_child_bus(b);
-		pci_bus_add_devices(b);
 	} else {
 		pci_free_resource_list(&resources);
 	}