[PATCH v5 30/42] 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 might not have any child devices.
Access to the PCI bus's child device node will cause kernel crash
without exception. The patch adds condition of skipping scanning
PCI bus without child devices, in order to avoid kernel crash.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
v5:
  * Derived from PATCH[v4 11/21]
---
 arch/powerpc/kernel/pci-hotplug.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
index 21973e7..ca392fc 100644
--- a/arch/powerpc/kernel/pci-hotplug.c
+++ b/arch/powerpc/kernel/pci-hotplug.c
@@ -92,7 +92,8 @@ 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
-- 
2.1.0