[PATCH] PowerNV/PCI: Fix NULL PCI controller

[Mike Qiu <qiudayu@linux.vnet.ibm.com>]

In pnv_pci_read_config() or pnv_pci_write_config(), we never check if
the PCI controller is valid before converting that into platform
dependent one, this is very dangerous. 

To avoid this potential risks, the patch check PCI controller first
before use it.

Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index b8b8e0b..e7b7f1a 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -286,11 +286,11 @@ static int pnv_pci_read_config(struct pci_bus *bus,
 			       int where, int size, u32 *val)
 {
 	struct pci_controller *hose = pci_bus_to_host(bus);
-	struct pnv_phb *phb = hose->private_data;
+	struct pnv_phb *phb = hose ? hose->private_data : NULL;
 	u32 bdfn = (((uint64_t)bus->number) << 8) | devfn;
 	s64 rc;
 
-	if (hose == NULL)
+	if (!phb)
 		return PCIBIOS_DEVICE_NOT_FOUND;
 
 	switch (size) {
@@ -330,10 +330,10 @@ static int pnv_pci_write_config(struct pci_bus *bus,
 				int where, int size, u32 val)
 {
 	struct pci_controller *hose = pci_bus_to_host(bus);
-	struct pnv_phb *phb = hose->private_data;
+	struct pnv_phb *phb = hose ? hose->private_data : NULL;
 	u32 bdfn = (((uint64_t)bus->number) << 8) | devfn;
 
-	if (hose == NULL)
+	if (!phb)
 		return PCIBIOS_DEVICE_NOT_FOUND;
 
 	cfg_dbg("pnv_pci_write_config bus: %x devfn: %x +%x/%x -> %08x\n",
-- 
1.7.10.1