2 files changed, 21 insertions, 3 deletions

diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
index e282c348dcde..53d0a8ee35d7 100644
--- a/arch/ia64/pci/pci.c
+++ b/arch/ia64/pci/pci.c
@@ -362,7 +362,12 @@ pci_acpi_scan_root(struct acpi_device *device, int domain, int bus)
         info.name = name;
         acpi_walk_resources(device->handle, METHOD_NAME__CRS, add_window,
                         &info);
-
+        /*
+         * See arch/x86/pci/acpi.c.
+         * The desired pci bus might already be scanned in a quirk. We
+         * should handle the case here, but it appears that IA64 hasn't
+         * such quirk. So we just ignore the case now.
+         */
         pbus = pci_scan_bus_parented(NULL, bus, &pci_root_ops, controller);
         if (pbus)
                 pcibios_setup_root_windows(pbus, controller);
diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 0234f2831bf3..378136fb5044 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -219,8 +219,21 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
         if (pxm >= 0)
                 sd->node = pxm_to_node(pxm);
 #endif
+        /*
+         * Maybe the desired pci bus has been already scanned. In such case
+         * it is unnecessary to scan the pci bus with the given domain,busnum.
+         */
+        bus = pci_find_bus(domain, busnum);
+        if (bus) {
+                /*
+                 * If the desired bus exits, the content of bus->sysdata will
+                 * be replaced by sd.
+                 */
+                memcpy(bus->sysdata, sd, sizeof(*sd));
+                kfree(sd);
+        } else
+                bus = pci_scan_bus_parented(NULL, busnum, &pci_root_ops, sd);
 
-        bus = pci_scan_bus_parented(NULL, busnum, &pci_root_ops, sd);
         if (!bus)
                 kfree(sd);
 
@@ -228,7 +241,7 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
         if (bus != NULL) {
                 if (pxm >= 0) {
                         printk("bus %d -> pxm %d -> node %d\n",
-                                busnum, pxm, sd->node);
+                                busnum, pxm, pxm_to_node(pxm));
                 }
         }
 #endif