ieee1394: don't drop nodes during bus reset series

nodemgr_node_probe checked for generation increments too late and
therefore prematurely reported nodes as "suspended".

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=11349.  Reported and
tested by Damien Benoist.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/ieee1394/nodemgr.c

@@ -1574,6 +1574,9 @@ static int node_probe(struct device *dev, void *data)
 	struct probe_param *p = data;
 	struct node_entry *ne;
 
+	if (p->generation != get_hpsb_generation(p->hi->host))
+		return -EAGAIN;
+
 	ne = container_of(dev, struct node_entry, node_dev);
 	if (ne->needs_probe == p->probe_now)
 		nodemgr_probe_ne(p->hi, ne, p->generation);
@@ -1582,41 +1585,40 @@ static int node_probe(struct device *dev, void *data)
 
 static void nodemgr_node_probe(struct host_info *hi, int generation)
 {
-	struct hpsb_host *host = hi->host;
 	struct probe_param p;
 
 	p.hi = hi;
 	p.generation = generation;
-	/* Do some processing of the nodes we've probed. This pulls them
+	/*
+	 * Do some processing of the nodes we've probed. This pulls them
 	 * into the sysfs layer if needed, and can result in processing of
 	 * unit-directories, or just updating the node and it's
 	 * unit-directories.
 	 *
 	 * Run updates before probes. Usually, updates are time-critical
-	 * while probes are time-consuming. (Well, those probes need some
-	 * improvement...) */
-
+	 * while probes are time-consuming.
+	 *
+	 * Meanwhile, another bus reset may have happened. In this case we
+	 * skip everything here and let the next bus scan handle it.
+	 * Otherwise we may prematurely remove nodes which are still there.
+	 */
 	p.probe_now = false;
-	class_for_each_device(&nodemgr_ne_class, NULL, &p, node_probe);
-	p.probe_now = true;
-	class_for_each_device(&nodemgr_ne_class, NULL, &p, node_probe);
+	if (class_for_each_device(&nodemgr_ne_class, NULL, &p, node_probe) != 0)
+		return;
 
-	/* If we had a bus reset while we were scanning the bus, it is
-	 * possible that we did not probe all nodes.  In that case, we
-	 * skip the clean up for now, since we could remove nodes that
-	 * were still on the bus.  Another bus scan is pending which will
-	 * do the clean up eventually.
-	 *
+	p.probe_now = true;
+	if (class_for_each_device(&nodemgr_ne_class, NULL, &p, node_probe) != 0)
+		return;
+	/*
 	 * Now let's tell the bus to rescan our devices. This may seem
 	 * like overhead, but the driver-model core will only scan a
 	 * device for a driver when either the device is added, or when a
 	 * new driver is added. A bus reset is a good reason to rescan
 	 * devices that were there before.  For example, an sbp2 device
 	 * may become available for login, if the host that held it was
-	 * just removed.  */
-
-	if (generation == get_hpsb_generation(host))
-		if (bus_rescan_devices(&ieee1394_bus_type))
+	 * just removed.
+	 */
+	if (bus_rescan_devices(&ieee1394_bus_type) != 0)
 		HPSB_DEBUG("bus_rescan_devices had an error");
 }