[PATCH 2/8] powerpc/pci: Don't scan empty slot

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

In hotplug case, function pcibios_add_pci_devices() is called to
rescan the specified PCI bus, which possibly doesn't have any child
devices. Access to the PCI bus's child device node will cause kernel
crash without exception. The patch adds two more conditions to avoid
the kernel crash.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/pci-hotplug.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
index 6e2b4e3..ea5513b 100644
--- a/arch/powerpc/kernel/pci-hotplug.c
+++ b/arch/powerpc/kernel/pci-hotplug.c
@@ -105,7 +105,7 @@ EXPORT_SYMBOL_GPL(pcibios_remove_pci_devices);
  * is how this routine differs from other, similar pcibios
  * routines.)
  */
-void pcibios_add_pci_devices(struct pci_bus * bus)
+void pcibios_add_pci_devices(struct pci_bus *bus)
 {
 	int slotno, mode, pass, max;
 	struct pci_dev *dev;
@@ -120,7 +120,8 @@ void pcibios_add_pci_devices(struct pci_bus * bus)
 	if (mode == PCI_PROBE_DEVTREE) {
 		/* use ofdt-based probe */
 		of_rescan_bus(dn, bus);
-	} else if (mode == PCI_PROBE_NORMAL) {
+	} else if (mode == PCI_PROBE_NORMAL &&
+		   dn->child && PCI_DN(dn->child)) {
 		/*
 		 * Use legacy probe. In the partial hotplug case, we
 		 * probably have grandchildren devices unplugged. So
-- 
1.8.3.2