[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>

1 files changed, 20 insertions, 9 deletions

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index dc97cb9f227f..9fecfb4223a8 100644
--- 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)
 {