From: Peter Oberparleiter

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
Signed-off-by: Martin Schwidefsky
---

drivers/s390/cio/device.c | 56 ++++++++++++++++++++--------------------------
1 file changed, 25 insertions(+), 31 deletions(-)

Index: quilt-2.6/drivers/s390/cio/device.c
================================================== =================
--- quilt-2.6.orig/drivers/s390/cio/device.c
+++ quilt-2.6/drivers/s390/cio/device.c
@@ -296,36 +296,33 @@ static void ccw_device_unregister(struct
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 cc
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_unregist

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_devi
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;

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.

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