powerpc/eeh: Reduce use of pci_dn::node

The pci_dn struct caches a OF device node pointer in order to access
the "ibm,loc-code" property when EEH is recovering.

However, when this happens in eeh_dev_check_failure(), we also have
a pci_dev pointer which should have a valid pointer to the device node
when pci_dn has one (both pointers are not NULL for physical functions
and are NULL for virtual functions).

This changes pci_remove_device_node_info() to look for a parent of
the node being removed, just like pci_add_device_node_info() does when it
references the parent node.

This is the first step to get rid of pci_dn::node.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/eeh.c

@@ -435,7 +435,7 @@ int eeh_dev_check_failure(struct eeh_dev *edev)
 	int ret;
 	int active_flags = (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE);
 	unsigned long flags;
-	struct pci_dn *pdn;
+	struct device_node *dn;
 	struct pci_dev *dev;
 	struct eeh_pe *pe, *parent_pe, *phb_pe;
 	int rc = 0;
@@ -493,9 +493,10 @@ int eeh_dev_check_failure(struct eeh_dev *edev)
 	if (pe->state & EEH_PE_ISOLATED) {
 		pe->check_count++;
 		if (pe->check_count % EEH_MAX_FAILS == 0) {
-			pdn = eeh_dev_to_pdn(edev);
-			if (pdn->node)
-				location = of_get_property(pdn->node, "ibm,loc-code", NULL);
+			dn = pci_device_to_OF_node(dev);
+			if (dn)
+				location = of_get_property(dn, "ibm,loc-code",
+						NULL);
 			printk(KERN_ERR "EEH: %d reads ignored for recovering device at "
 				"location=%s driver=%s pci addr=%s\n",
 				pe->check_count,

arch/powerpc/kernel/pci_dn.c

@@ -342,6 +342,7 @@ EXPORT_SYMBOL_GPL(pci_add_device_node_info);
 void pci_remove_device_node_info(struct device_node *dn)
 {
 	struct pci_dn *pdn = dn ? PCI_DN(dn) : NULL;
+	struct device_node *parent;
 #ifdef CONFIG_EEH
 	struct eeh_dev *edev = pdn_to_eeh_dev(pdn);
 
@@ -354,8 +355,10 @@ void pci_remove_device_node_info(struct device_node *dn)
 
 	WARN_ON(!list_empty(&pdn->child_list));
 	list_del(&pdn->list);
-	if (pdn->parent)
-		of_node_put(pdn->parent->node);
+
+	parent = of_get_parent(dn);
+	if (parent)
+		of_node_put(parent);
 
 	dn->data = NULL;
 	kfree(pdn);