PCI: Enable upstream bridges even for VFs on virtual buses

Previously we enabled the upstream PCI-to-PCI bridge only when
"dev->bus->self != NULL".  In the case of a VF on a virtual bus, where
"bus->self == NULL", we didn't enable the upstream bridge.

This fixes that by enabling the upstream bridge of the PF corresponding to
the VF.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>

drivers/pci/pci.c

@@ -1148,12 +1148,12 @@ int pci_reenable_device(struct pci_dev *dev)
 
 static void pci_enable_bridge(struct pci_dev *dev)
 {
+	struct pci_dev *bridge;
 	int retval;
 
-	if (!dev)
-		return;
-
-	pci_enable_bridge(dev->bus->self);
+	bridge = pci_upstream_bridge(dev);
+	if (bridge)
+		pci_enable_bridge(bridge);
 
 	if (pci_is_enabled(dev)) {
 		if (!dev->is_busmaster)
@@ -1170,6 +1170,7 @@ static void pci_enable_bridge(struct pci_dev *dev)
 
 static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
 {
+	struct pci_dev *bridge;
 	int err;
 	int i, bars = 0;
 
@@ -1188,7 +1189,9 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
 	if (atomic_inc_return(&dev->enable_cnt) > 1)
 		return 0;		/* already enabled */
 
-	pci_enable_bridge(dev->bus->self);
+	bridge = pci_upstream_bridge(dev);
+	if (bridge)
+		pci_enable_bridge(bridge);
 
 	/* only skip sriov related */
 	for (i = 0; i <= PCI_ROM_RESOURCE; i++)