[S390] cio: move device unregistration to dedicated work queue

Use dedicated slow path work queue when unregistering a device due to
a user action. This ensures serialialization of other register/
unregister requests.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 28221030b886cfa5ae8d794fdf176bdbfe401845..38a79ecfc743edff2eaee6b746c4a16c2ec18796 100644 (file)
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -296,36 +296,33 @@ static void ccw_device_unregister(struct ccw_device *cdev)
                device_del(&cdev->dev);
 }
 
-static void ccw_device_remove_orphan_cb(struct device *dev)
+static void ccw_device_remove_orphan_cb(struct work_struct *work)
 {
-       struct ccw_device *cdev = to_ccwdev(dev);
+       struct ccw_device_private *priv;
+       struct ccw_device *cdev;
 
+       priv = container_of(work, struct ccw_device_private, kick_work);
+       cdev = priv->cdev;
        ccw_device_unregister(cdev);
        put_device(&cdev->dev);
+       /* Release cdev reference for workqueue processing. */
+       put_device(&cdev->dev);
 }
 
-static void ccw_device_remove_sch_cb(struct device *dev)
-{
-       struct subchannel *sch;
-
-       sch = to_subchannel(dev);
-       css_sch_device_unregister(sch);
-       /* Reset intparm to zeroes. */
-       sch->schib.pmcw.intparm = 0;
-       cio_modify(sch);
-       put_device(&sch->dev);
-}
+static void ccw_device_call_sch_unregister(struct work_struct *work);
 
 static void
 ccw_device_remove_disconnected(struct ccw_device *cdev)
 {
        unsigned long flags;
-       int rc;
 
        /*
         * Forced offline in disconnected state means
         * 'throw away device'.
         */
+       /* Get cdev reference for workqueue processing. */
+       if (!get_device(&cdev->dev))
+               return;
        if (ccw_device_is_orphan(cdev)) {
                /*
                 * Deregister ccw device.
@@ -335,23 +332,13 @@ ccw_device_remove_disconnected(struct ccw_device *cdev)
                spin_lock_irqsave(cdev->ccwlock, flags);
                cdev->private->state = DEV_STATE_NOT_OPER;
                spin_unlock_irqrestore(cdev->ccwlock, flags);
-               rc = device_schedule_callback(&cdev->dev,
-                                             ccw_device_remove_orphan_cb);
-               if (rc)
-                       CIO_MSG_EVENT(0, "Couldn't unregister orphan "
-                                     "0.%x.%04x\n",
-                                     cdev->private->dev_id.ssid,
-                                     cdev->private->dev_id.devno);
-               return;
-       }
-       /* Deregister subchannel, which will kill the ccw device. */
-       rc = device_schedule_callback(cdev->dev.parent,
-                                     ccw_device_remove_sch_cb);
-       if (rc)
-               CIO_MSG_EVENT(0, "Couldn't unregister disconnected device "
-                             "0.%x.%04x\n",
-                             cdev->private->dev_id.ssid,
-                             cdev->private->dev_id.devno);
+               PREPARE_WORK(&cdev->private->kick_work,
+                               ccw_device_remove_orphan_cb);
+       } else
+               /* Deregister subchannel, which will kill the ccw device. */
+               PREPARE_WORK(&cdev->private->kick_work,
+                               ccw_device_call_sch_unregister);
+       queue_work(slow_path_wq, &cdev->private->kick_work);
 }
 
 /**
@@ -970,12 +957,17 @@ static void ccw_device_call_sch_unregister(struct work_struct *work)
 
        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
+       /* Get subchannel reference for local processing. */
+       if (!get_device(cdev->dev.parent))
+               return;
        sch = to_subchannel(cdev->dev.parent);
        css_sch_device_unregister(sch);
        /* Reset intparm to zeroes. */
        sch->schib.pmcw.intparm = 0;
        cio_modify(sch);
+       /* Release cdev reference for workqueue processing.*/
        put_device(&cdev->dev);
+       /* Release subchannel reference for local processing. */
        put_device(&sch->dev);
 }
 
@@ -1001,6 +993,8 @@ io_subchannel_recog_done(struct ccw_device *cdev)
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_call_sch_unregister);
                queue_work(slow_path_wq, &cdev->private->kick_work);
+               /* Release subchannel reference for asynchronous recognition. */
+               put_device(&sch->dev);
                if (atomic_dec_and_test(&ccw_device_init_count))
                        wake_up(&ccw_device_init_wq);
                break;