[patch 52/52] [PATCH] cio: dont unregister a busy device in ccw_device_set_offline

Martin Schwidefsky
2009-11-13T15:10:01Z

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[-- Type: text/plain, Size: 2845 bytes --]

From: Sebastian Ott <sebott@linux.vnet.ibm.com>

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>
---

drivers/s390/cio/device.c | 29 ++++++++++++++++++++---------
1 file changed, 20 insertions(+), 9 deletions(-)

Index: quilt-2.6/drivers/s390/cio/device.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device.c 2009-11-13 16:08:23.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device.c 2009-11-13 16:08:23.000000000 +0100
@@ -314,6 +314,8 @@
}
}

+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 @@
*/
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 @@
}
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 @@
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 @@
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 @@
return 0;
}

-static void io_subchannel_quiesce(struct subchannel *);
-
static int
io_subchannel_remove (struct subchannel *sch)
{