ChangeLog:

        * bus/usb/ohci.c: Link struct only after initialising controller.
        * bus/usb/uhci.c: Likewise.

Index: bus/usb/ohci.c
===================================================================
--- bus/usb/ohci.c	(revision 2216)
+++ bus/usb/ohci.c	(working copy)
@@ -153,9 +153,6 @@ grub_ohci_pci_iter (int bus, int device, int func,
   if (! o)
     return 1;
 
-  /* Link in the OHCI.  */
-  o->next = ohci;
-  ohci = o;
   o->iobase = (grub_uint32_t *) base;
 
   /* Reserve memory for the HCCA.  */
@@ -189,6 +186,10 @@ grub_ohci_pci_iter (int bus, int device, int func,
   grub_dprintf ("ohci", "OHCI enable: 0x%02x\n",
 		(grub_ohci_readreg32 (o, GRUB_OHCI_REG_CONTROL) >> 6) & 3);
  
+  /* link to ohci now that initialisation is successful. */
+  o->next = ohci;
+  ohci = o;
+
   return 0;
 
  fail:
Index: bus/usb/uhci.c
===================================================================
--- bus/usb/uhci.c	(revision 2216)
+++ bus/usb/uhci.c	(working copy)
@@ -173,8 +173,6 @@ grub_uhci_pci_iter (int bus, int device, int func,
   if (! u)
     return 1;
 
-  u->next = uhci;
-  uhci = u;
   u->iobase = base & GRUB_UHCI_IOMASK;
   u->framelist = 0;
   u->qh = 0;
@@ -287,6 +285,10 @@ grub_uhci_pci_iter (int bus, int device, int func,
   }
 #endif
 
+  /* link to uhci now that initialisation is successful. */
+  u->next = uhci;
+  uhci = u;
+
   return 0;
 
  fail: