powerpc/eeh: Make EEH device add/remove more robust

To properly fix PCI hotplug, it's useful to be able to make the fixup
passes on all devices whether they were just hot plugged or already
there.

The EEH code however used to not be very friendly with calling
eeh_add_device_late() multiple time, and not very rebust in the way it
generally tests whether a device is in the expected state vs. the EEH
code.

This improves it, along with cleaning up a couple of debug printk's.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/eeh.c

@@ -21,6 +21,8 @@
  * Please address comments and feedback to Linas Vepstas <linas@austin.ibm.com>
  */
 
+#undef DEBUG
+
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/list.h>
@@ -488,10 +490,8 @@ int eeh_dn_check_failure(struct device_node *dn, struct pci_dev *dev)
 	if (!(pdn->eeh_mode & EEH_MODE_SUPPORTED) ||
 	    pdn->eeh_mode & EEH_MODE_NOCHECK) {
 		ignored_check++;
-#ifdef DEBUG
-		printk ("EEH:ignored check (%x) for %s %s\n", 
+		pr_debug("EEH: Ignored check (%x) for %s %s\n",
 			 pdn->eeh_mode, pci_name (dev), dn->full_name);
-#endif
 		return 0;
 	}
 
@@ -1014,10 +1014,9 @@ static void *early_enable_eeh(struct device_node *dn, void *data)
 			eeh_subsystem_enabled = 1;
 			pdn->eeh_mode |= EEH_MODE_SUPPORTED;
 
-#ifdef DEBUG
-			printk(KERN_DEBUG "EEH: %s: eeh enabled, config=%x pe_config=%x\n",
-			       dn->full_name, pdn->eeh_config_addr, pdn->eeh_pe_config_addr);
-#endif
+			pr_debug("EEH: %s: eeh enabled, config=%x pe_config=%x\n",
+				 dn->full_name, pdn->eeh_config_addr,
+				 pdn->eeh_pe_config_addr);
 		} else {
 
 			/* This device doesn't support EEH, but it may have an
@@ -1161,13 +1160,17 @@ static void eeh_add_device_late(struct pci_dev *dev)
 	if (!dev || !eeh_subsystem_enabled)
 		return;
 
-#ifdef DEBUG
-	printk(KERN_DEBUG "EEH: adding device %s\n", pci_name(dev));
-#endif
+	pr_debug("EEH: Adding device %s\n", pci_name(dev));
 
-	pci_dev_get (dev);
 	dn = pci_device_to_OF_node(dev);
 	pdn = PCI_DN(dn);
+	if (pdn->pcidev == dev) {
+		pr_debug("EEH: Already referenced !\n");
+		return;
+	}
+	WARN_ON(pdn->pcidev);
+
+	pci_dev_get (dev);
 	pdn->pcidev = dev;
 
 	pci_addr_cache_insert_device(dev);
@@ -1206,17 +1209,18 @@ static void eeh_remove_device(struct pci_dev *dev)
 		return;
 
 	/* Unregister the device with the EEH/PCI address search system */
-#ifdef DEBUG
-	printk(KERN_DEBUG "EEH: remove device %s\n", pci_name(dev));
-#endif
-	pci_addr_cache_remove_device(dev);
-	eeh_sysfs_remove_device(dev);
+	pr_debug("EEH: Removing device %s\n", pci_name(dev));
 
 	dn = pci_device_to_OF_node(dev);
-	if (PCI_DN(dn)->pcidev) {
+	if (PCI_DN(dn)->pcidev == NULL) {
+		pr_debug("EEH: Not referenced !\n");
+		return;
+	}
 	PCI_DN(dn)->pcidev = NULL;
 	pci_dev_put (dev);
-	}
+
+	pci_addr_cache_remove_device(dev);
+	eeh_sysfs_remove_device(dev);
 }
 
 void eeh_remove_bus_device(struct pci_dev *dev)