PCI: enumerate the PCI device only removed out PCI hieratchy of OS when re-scanning PCI

When hot-plugging a root bridge, we always prevent assigning a bus number
that already exists. This makes sure we don't step over an existing bus.
But sometimes we only remove PCI device in PCI hieratchy of OS, i,e.

echo 1 > /sys/bus/pci/devices/.../remove

but actually don't hotplug this device out the platform, so in this case
we still should re-scan this bus to enumerate this device when re-scanning
PCI again.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/probe.c

@@ -724,12 +724,14 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 		pci_write_config_word(dev, PCI_STATUS, 0xffff);
 
 		/* Prevent assigning a bus number that already exists.
-		 * This can happen when a bridge is hot-plugged */
-		if (pci_find_bus(pci_domain_nr(bus), max+1))
-			goto out;
+		 * This can happen when a bridge is hot-plugged, so in
+		 * this case we only re-scan this bus. */
+		child = pci_find_bus(pci_domain_nr(bus), max+1);
+		if (!child) {
 			child = pci_add_new_bus(bus, dev, ++max);
 			if (!child)
 				goto out;
+		}
 		buses = (buses & 0xff000000)
 		      | ((unsigned int)(child->primary)     <<  0)
 		      | ((unsigned int)(child->secondary)   <<  8)