[S390] Support for disconnected devices reappearing on another subchannel.

- create a 'pseudo_subchannel' per channel subsystem (the 'orphanage')
- use the orphanage as a shelter for ccw_devices that can't remain on the same
  subchannel

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index a487fb0e7d3d..eed14572fc3b 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -186,13 +186,12 @@ ccw_device_handle_oper(struct ccw_device *cdev)
         /*
          * Check if cu type and device type still match. If
          * not, it is certainly another device and we have to
-         * de- and re-register. Also check here for non-matching devno.
+         * de- and re-register.
          */
         if (cdev->id.cu_type != cdev->private->senseid.cu_type ||
             cdev->id.cu_model != cdev->private->senseid.cu_model ||
             cdev->id.dev_type != cdev->private->senseid.dev_type ||
-            cdev->id.dev_model != cdev->private->senseid.dev_model ||
-            cdev->private->dev_id.devno != sch->schib.pmcw.dev) {
+            cdev->id.dev_model != cdev->private->senseid.dev_model) {
                 PREPARE_WORK(&cdev->private->kick_work,
                              ccw_device_do_unreg_rereg);
                 queue_work(ccw_device_work, &cdev->private->kick_work);
@@ -676,6 +675,10 @@ ccw_device_offline(struct ccw_device *cdev)
 {
         struct subchannel *sch;
 
+        if (ccw_device_is_orphan(cdev)) {
+                ccw_device_done(cdev, DEV_STATE_OFFLINE);
+                return 0;
+        }
         sch = to_subchannel(cdev->dev.parent);
         if (stsch(sch->schid, &sch->schib) || !sch->schib.pmcw.dnv)
                 return -ENODEV;
@@ -1121,7 +1124,13 @@ device_trigger_reprobe(struct subchannel *sch)
                 sch->schib.pmcw.mp = 1;
         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
         /* We should also udate ssd info, but this has to wait. */
-        ccw_device_start_id(cdev, 0);
+        /* Check if this is another device which appeared on the same sch. */
+        if (sch->schib.pmcw.dev != cdev->private->dev_id.devno) {
+                PREPARE_WORK(&cdev->private->kick_work,
+                             ccw_device_move_to_orphanage);
+                queue_work(ccw_device_work, &cdev->private->kick_work);
+        } else
+                ccw_device_start_id(cdev, 0);
 }
 
 static void