s390/pci: improve pci hotplug

PCI hotplug events basically notify about the new state of a
function. Unfortunately some hypervisors implement hotplug
events in a way where it is not clear what the new state of
the function should be.

Use clp_get_state to find the current state of the function
and handle accordingly.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/pci.h

@@ -158,6 +158,7 @@ extern const struct attribute_group *zpci_attr_groups[];
 ----------------------------------------------------------------------------- */
 /* Base stuff */
 int zpci_create_device(struct zpci_dev *);
+void zpci_remove_device(struct zpci_dev *zdev);
 int zpci_enable_device(struct zpci_dev *);
 int zpci_disable_device(struct zpci_dev *);
 void zpci_stop_device(struct zpci_dev *);

arch/s390/pci/pci.c

@@ -855,6 +855,15 @@ void zpci_stop_device(struct zpci_dev *zdev)
 }
 EXPORT_SYMBOL_GPL(zpci_stop_device);
 
+void zpci_remove_device(struct zpci_dev *zdev)
+{
+	if (!zdev->bus)
+		return;
+
+	pci_stop_root_bus(zdev->bus);
+	pci_remove_root_bus(zdev->bus);
+}
+
 int zpci_report_error(struct pci_dev *pdev,
 		      struct zpci_report_error_header *report)
 {

arch/s390/pci/pci_event.c

@@ -74,6 +74,7 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 {
 	struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid);
 	struct pci_dev *pdev = NULL;
+	enum zpci_state state;
 	int ret;
 
 	if (zdev)
@@ -108,6 +109,8 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 			clp_add_pci_device(ccdf->fid, ccdf->fh, 0);
 		break;
 	case 0x0303: /* Deconfiguration requested */
+		if (!zdev)
+			break;
 		if (pdev)
 			pci_stop_and_remove_bus_device_locked(pdev);
 
@@ -121,7 +124,9 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 			zdev->state = ZPCI_FN_STATE_STANDBY;
 
 		break;
-	case 0x0304: /* Configured -> Standby */
+	case 0x0304: /* Configured -> Standby|Reserved */
+		if (!zdev)
+			break;
 		if (pdev) {
 			/* Give the driver a hint that the function is
 			 * already unusable. */
@@ -132,6 +137,10 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 		zdev->fh = ccdf->fh;
 		zpci_disable_device(zdev);
 		zdev->state = ZPCI_FN_STATE_STANDBY;
+		if (!clp_get_state(ccdf->fid, &state) &&
+		    state == ZPCI_FN_STATE_RESERVED) {
+			zpci_remove_device(zdev);
+		}
 		break;
 	case 0x0306: /* 0x308 or 0x302 for multiple devices */
 		clp_rescan_pci_devices();
@@ -139,8 +148,7 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 	case 0x0308: /* Standby -> Reserved */
 		if (!zdev)
 			break;
-		pci_stop_root_bus(zdev->bus);
+		zpci_remove_device(zdev);
-		pci_remove_root_bus(zdev->bus);
 		break;
 	default:
 		break;