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>

1 files changed, 21 insertions, 19 deletions

diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 2ebd09a89427..16240a789650 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/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);
@@ -1582,42 +1585,41 @@ 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))
-                        HPSB_DEBUG("bus_rescan_devices had an error");
+         * just removed.
+         */
+        if (bus_rescan_devices(&ieee1394_bus_type) != 0)
+                HPSB_DEBUG("bus_rescan_devices had an error");
 }
 
 static int nodemgr_send_resume_packet(struct hpsb_host *host)