ieee1394: run high-level updates before high-level probes

After a bus reset, let nodemgr call high-level update hooks first for nodes
which do not need to be probed.  The main benefit is for a bus with more
than one SBP-2 device:  SBP-2 reconnects will be performed before SBP-2
logins, thus have a much higher chance to succeed, and their SCSI devices
will not be blocked much longer than necessary.  This was demonstrated for
Linux 2.4 by Dave Cinege a while ago.

A better approach would be to perform time-consuming probes in parallel by a
subthread.  I actually plan to implement this for sbp2 but it may take a
while to get that done and tested.  Until then, this tweak is a huge
improvement for users with multiple SBP-2 devices.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Jody McIntyre <scjody@modernduck.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 01ab2bf..0ec2987 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/drivers/ieee1394/nodemgr.c
@@ -1407,14 +1407,28 @@ static void nodemgr_node_probe(struct host_info *hi, int generation)
 	struct hpsb_host *host = hi->host;
 	struct class *class = &nodemgr_ne_class;
 	struct class_device *cdev;
+	struct node_entry *ne;
 
 	/* 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. */
+	 * unit-directories.
+	 *
+	 * Run updates before probes. Usually, updates are time-critical
+	 * while probes are time-consuming. (Well, those probes need some
+	 * improvement...) */
+
 	down_read(&class->subsys.rwsem);
-	list_for_each_entry(cdev, &class->children, node)
-		nodemgr_probe_ne(hi, container_of(cdev, struct node_entry, class_dev), generation);
+	list_for_each_entry(cdev, &class->children, node) {
+		ne = container_of(cdev, struct node_entry, class_dev);
+		if (!ne->needs_probe)
+			nodemgr_probe_ne(hi, ne, generation);
+	}
+	list_for_each_entry(cdev, &class->children, node) {
+		ne = container_of(cdev, struct node_entry, class_dev);
+		if (ne->needs_probe)
+			nodemgr_probe_ne(hi, ne, generation);
+	}
         up_read(&class->subsys.rwsem);