[PATCH] ppc64: bugfix: crash on PHB add

19-rpaphp-crashing.patch

This patch fixes a bug related to dlpar PHB add, after a PHB removal.

-- The crash was due to the PHB not having a pci_dn structure yet,
   when the phb is being added.

This code survived testing, of adding and removeig the PHB and all slots
underneath it, 17 times so far, as of this writing.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

drivers/pci/hotplug/rpadlpar_core.c

@@ -306,7 +306,7 @@ static int dlpar_add_phb(char *drc_name, struct device_node *dn)
 {
 	struct pci_controller *phb;
 
-	if (PCI_DN(dn)->phb) {
+	if (PCI_DN(dn) && PCI_DN(dn)->phb) {
 		/* PHB already exists */
 		return -EINVAL;
 	}