[S390] cio: Use unbind/bind instead of unregister/register.

The common I/O layer may encounter a situation where the
device number of a ccw device has changed or a device
driver doesn't want to keep a formerly disconnected device
becoming operational again. Instead of using device_del()/
device_add() as now, we can just unbind the driver from the
device and rebind it to get the desired effect (rebinding)
with less overhead.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 10 insertions, 23 deletions

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 23d5752349b5..71b3b73e8ebe 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -681,35 +681,22 @@ get_orphaned_ccwdev_by_dev_id(struct channel_subsystem *css,
         return dev ? to_ccwdev(dev) : NULL;
 }
 
-static void
-ccw_device_add_changed(struct work_struct *work)
-{
-        struct ccw_device_private *priv;
-        struct ccw_device *cdev;
-
-        priv = container_of(work, struct ccw_device_private, kick_work);
-        cdev = priv->cdev;
-        if (device_add(&cdev->dev)) {
-                put_device(&cdev->dev);
-                return;
-        }
-        set_bit(1, &cdev->private->registered);
-}
-
-void ccw_device_do_unreg_rereg(struct work_struct *work)
+void ccw_device_do_unbind_bind(struct work_struct *work)
 {
         struct ccw_device_private *priv;
         struct ccw_device *cdev;
         struct subchannel *sch;
+        int ret;
 
         priv = container_of(work, struct ccw_device_private, kick_work);
         cdev = priv->cdev;
         sch = to_subchannel(cdev->dev.parent);
 
-        ccw_device_unregister(cdev);
-        PREPARE_WORK(&cdev->private->kick_work,
-                     ccw_device_add_changed);
-        queue_work(ccw_device_work, &cdev->private->kick_work);
+        if (test_bit(1, &cdev->private->registered)) {
+                device_release_driver(&cdev->dev);
+                ret = device_attach(&cdev->dev);
+                WARN_ON(ret == -ENODEV);
+        }
 }
 
 static void
diff --git a/drivers/s390/cio/device.h b/drivers/s390/cio/device.h
index 0f2e63ea48de..85e01846ca65 100644
--- a/drivers/s390/cio/device.h
+++ b/drivers/s390/cio/device.h
@@ -80,7 +80,7 @@ void io_subchannel_init_config(struct subchannel *sch);
 
 int ccw_device_cancel_halt_clear(struct ccw_device *);
 
-void ccw_device_do_unreg_rereg(struct work_struct *);
+void ccw_device_do_unbind_bind(struct work_struct *);
 void ccw_device_move_to_orphanage(struct work_struct *);
 int ccw_device_is_orphan(struct ccw_device *);
 
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index 8df5eaafc5ab..95f2f352cb9d 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -194,7 +194,7 @@ ccw_device_handle_oper(struct ccw_device *cdev)
             cdev->id.dev_type != cdev->private->senseid.dev_type ||
             cdev->id.dev_model != cdev->private->senseid.dev_model) {
                 PREPARE_WORK(&cdev->private->kick_work,
-                             ccw_device_do_unreg_rereg);
+                             ccw_device_do_unbind_bind);
                 queue_work(ccw_device_work, &cdev->private->kick_work);
                 return 0;
         }
@@ -366,7 +366,7 @@ static void ccw_device_oper_notify(struct ccw_device *cdev)
         }
         /* Driver doesn't want device back. */
         ccw_device_set_notoper(cdev);
-        PREPARE_WORK(&cdev->private->kick_work, ccw_device_do_unreg_rereg);
+        PREPARE_WORK(&cdev->private->kick_work, ccw_device_do_unbind_bind);
         queue_work(ccw_device_work, &cdev->private->kick_work);
 }