[S390] cio: dont unregister a busy device in ccw_device_set_offline

If we detect a busy subchannel after the driver's set_offline
callback returned in ccw_device_set_offline, the current behavior
is to unregister the device, which may lead to undesired
consequences. Change this to just quiesce the subchannel and go on
with the offline processing.

Note: This is no excuse for not fixing these drivers -
after the set_offline callback they should have no running IO!

Signed-off-by: Sebastian Ott <sebott@linux.vnet.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 dc97cb9..9fecfb4 100644 (file)
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -314,6 +314,8 @@ static void ccw_device_unregister(struct ccw_device *cdev)
        }
 }
 
+static void io_subchannel_quiesce(struct subchannel *);
+
 /**
  * ccw_device_set_offline() - disable a ccw device for I/O
  * @cdev: target ccw device
@@ -327,7 +329,8 @@ static void ccw_device_unregister(struct ccw_device *cdev)
  */
 int ccw_device_set_offline(struct ccw_device *cdev)
 {
-       int ret;
+       struct subchannel *sch;
+       int ret, state;
 
        if (!cdev)
                return -ENODEV;
@@ -341,6 +344,7 @@ int ccw_device_set_offline(struct ccw_device *cdev)
        }
        cdev->online = 0;
        spin_lock_irq(cdev->ccwlock);
+       sch = to_subchannel(cdev->dev.parent);
        /* Wait until a final state or DISCONNECTED is reached */
        while (!dev_fsm_final_state(cdev) &&
               cdev->private->state != DEV_STATE_DISCONNECTED) {
@@ -349,9 +353,21 @@ int ccw_device_set_offline(struct ccw_device *cdev)
                           cdev->private->state == DEV_STATE_DISCONNECTED));
                spin_lock_irq(cdev->ccwlock);
        }
-       ret = ccw_device_offline(cdev);
-       if (ret)
-               goto error;
+       do {
+               ret = ccw_device_offline(cdev);
+               if (!ret)
+                       break;
+               CIO_MSG_EVENT(0, "ccw_device_offline returned %d, device "
+                             "0.%x.%04x\n", ret, cdev->private->dev_id.ssid,
+                             cdev->private->dev_id.devno);
+               if (ret != -EBUSY)
+                       goto error;
+               state = cdev->private->state;
+               spin_unlock_irq(cdev->ccwlock);
+               io_subchannel_quiesce(sch);
+               spin_lock_irq(cdev->ccwlock);
+               cdev->private->state = state;
+       } while (ret == -EBUSY);
        spin_unlock_irq(cdev->ccwlock);
        wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
                   cdev->private->state == DEV_STATE_DISCONNECTED));
@@ -368,9 +384,6 @@ int ccw_device_set_offline(struct ccw_device *cdev)
        return 0;
 
 error:
-       CIO_MSG_EVENT(0, "ccw_device_offline returned %d, device 0.%x.%04x\n",
-                     ret, cdev->private->dev_id.ssid,
-                     cdev->private->dev_id.devno);
        cdev->private->state = DEV_STATE_OFFLINE;
        dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
        spin_unlock_irq(cdev->ccwlock);
@@ -1059,8 +1072,6 @@ out_schedule:
        return 0;
 }
 
-static void io_subchannel_quiesce(struct subchannel *);
-
 static int
 io_subchannel_remove (struct subchannel *sch)
 {