[PATCH 2/2] ppc64: Crash in DLPAR code on remove operation

[linas]

This patch fixes two bugs related to dlpar slot removal and add.

-- Both crashes are due to the fact the some children 
   of pci nodes are not pci nodes themselves, and thus do not 
   have pci_dn structures.  For example:
        /pci at 800000020000002/pci at 2,3/usb at 1/hub at 1
        /pci at 800000020000002/pci at 2,3/usb at 1,1/hub at 1

   Strangely, though, sometimes the following appears, 
   and I don't quite understand why.
        /interrupt-controller at 3fe0000a400

   A typical stack trace:
        Vector: 300 (Data Access) at [c0000000555637d0]
         pc: c000000000202a50: .dlpar_add_slot+0x108/0x410
             c000000000202e78 .add_slot_store+0x7c/0xac
             c000000000202da0 .dlpar_attr_store+0x48/0x64
             c0000000000f8ee4 .sysfs_write_file+0x100/0x1a0

   A similar stack trace is involved for the slot remove.

This code survived testing, of adding and removing different slots,
23 times each, so far, as of this writing.

Signed-off-by: Linas Vepstas <linas at austin.ibm.com>


Index: linux-2.6.14-rc2-git6/arch/ppc64/kernel/pSeries_iommu.c
===================================================================
--- linux-2.6.14-rc2-git6.orig/arch/ppc64/kernel/pSeries_iommu.c	2005-10-04 16:47:09.175705100 -0500
+++ linux-2.6.14-rc2-git6/arch/ppc64/kernel/pSeries_iommu.c	2005-10-04 17:12:54.123928903 -0500
@@ -478,10 +478,13 @@
 {
 	int err = NOTIFY_OK;
 	struct device_node *np = node;
-	struct pci_dn *pci = np->data;
+	struct pci_dn *pci;
 
 	switch (action) {
 	case PSERIES_RECONFIG_REMOVE:
+		pci = PCI_DN(np);
+		if (!pci)
+			return NOTIFY_OK;
 		if (pci->iommu_table &&
 		    get_property(np, "ibm,dma-window", NULL))
 			iommu_free_table(np);
Index: linux-2.6.14-rc2-git6/arch/ppc64/kernel/pci_dn.c
===================================================================
--- linux-2.6.14-rc2-git6.orig/arch/ppc64/kernel/pci_dn.c	2005-10-04 15:37:49.761245845 -0500
+++ linux-2.6.14-rc2-git6/arch/ppc64/kernel/pci_dn.c	2005-10-04 17:58:47.344628793 -0500
@@ -195,7 +195,10 @@
 
 	switch (action) {
 	case PSERIES_RECONFIG_ADD:
-		pci = np->parent->data;
+		pci = PCI_DN(np->parent);
+		if (!pci)
+			return NOTIFY_OK;
+
 		update_dn_pci_info(np, pci->phb);
 		break;
 	default: