From: Hans-Joachim Picht <hpicht@redhat.com>
Date: Tue, 22 Sep 2009 22:09:10 +0200
Subject: [s390] cio: failing set online/offline processing
Message-id: 20090922200910.GA32244@blc4eb509856389.ibm.com
O-Subject: [RHEL5 U5 PATCH 1/1] s390 - cio: failing set online/offline processing
Bugzilla: 523323
RH-Acked-by: Pete Zaitcev <zaitcev@redhat.com>

Description
===========
A set online or set offline fails for a DASD device.
Afterwards this device can neither be set online nor offline.

When unit checks trigger sensing the device state is set to W4SENSE
until sense completion; then the device state is set back to ONLINE.
If a unit check occurs while set online or set offline requests are
processed then it might happen that the device's temporary W4SENSE
state causes these functions to terminate, leaving the device in an
inconsistent state when the state is set back to ONLINE later on so
that the device cannot be set online or offline any longer.

To solve this, set online/offline and related rollback or error
routines are processed only if the device is in a final or
DISCONNECTED state.

Bugzilla
========

BZ 523323
https://bugzilla.redhat.com/show_bug.cgi?id=523323

Upstream status of the patch
============================

The patch will be  upstream as of kernel version 2.6.32

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=217ee6c64a9589bc5ad4d1c88136fc359d17930b

Test status
===========

The patch has been tested and fixes the problem.
The fix has been verified by the IBM test department.

Please ACK.

With best regards,

        Hans

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 5166e67..1366749 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -331,30 +331,36 @@ ccw_device_set_offline(struct ccw_device *cdev)
 	}
 	cdev->online = 0;
 	spin_lock_irq(cdev->ccwlock);
-	ret = ccw_device_offline(cdev);
-	if (ret == -ENODEV) {
-		if (cdev->private->state != DEV_STATE_NOT_OPER) {
-			cdev->private->state = DEV_STATE_OFFLINE;
-			dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
-		}
+	/* Wait until a final state or DISCONNECTED is reached */
+	while (!dev_fsm_final_state(cdev) &&
+	       cdev->private->state != DEV_STATE_DISCONNECTED) {
 		spin_unlock_irq(cdev->ccwlock);
-		return ret;
+		wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
+			   cdev->private->state == DEV_STATE_DISCONNECTED));
+		spin_lock_irq(cdev->ccwlock);
 	}
+	ret = ccw_device_offline(cdev);
+	if (ret)
+		goto error;
 	spin_unlock_irq(cdev->ccwlock);
-	if (ret == 0)
-		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
-	else {
-		pr_debug("ccw_device_offline returned %d, device %s\n",
-			 ret, cdev->dev.bus_id);
-		cdev->online = 1;
-	}
- 	return ret;
+	wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
+		   cdev->private->state == DEV_STATE_DISCONNECTED));
+	return 0;
+
+error:
+	pr_debug("ccw_device_offline returned %d, device %s\n",
+		 ret, cdev->dev.bus_id);
+	cdev->private->state = DEV_STATE_OFFLINE;
+	dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
+	spin_unlock_irq(cdev->ccwlock);
+	return -ENODEV;
 }
 
 int
 ccw_device_set_online(struct ccw_device *cdev)
 {
 	int ret;
+	int ret2;
 
 	if (!cdev)
 		return -ENODEV;
@@ -371,21 +377,45 @@ ccw_device_set_online(struct ccw_device *cdev)
 			 ret, cdev->dev.bus_id);
 		return ret;
 	}
-	if (cdev->private->state != DEV_STATE_ONLINE)
+	spin_lock_irq(cdev->ccwlock);
+	/* Check if online processing was successful */
+	if ((cdev->private->state != DEV_STATE_ONLINE) &&
+	    (cdev->private->state != DEV_STATE_W4SENSE)) {
+		spin_unlock_irq(cdev->ccwlock);
 		return -ENODEV;
-	if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) {
-		cdev->online = 1;
-		return 0;
 	}
+	spin_unlock_irq(cdev->ccwlock);
+	if (cdev->drv->set_online)
+		ret = cdev->drv->set_online(cdev);
+	if (ret)
+		goto rollback;
+	cdev->online = 1;
+	return 0;
+
+rollback:
 	spin_lock_irq(cdev->ccwlock);
-	ret = ccw_device_offline(cdev);
+	/* Wait until a final state or DISCONNECTED is reached */
+	while (!dev_fsm_final_state(cdev) &&
+	       cdev->private->state != DEV_STATE_DISCONNECTED) {
+		spin_unlock_irq(cdev->ccwlock);
+		wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
+			   cdev->private->state == DEV_STATE_DISCONNECTED));
+		spin_lock_irq(cdev->ccwlock);
+	}
+	ret2 = ccw_device_offline(cdev);
+	if (ret2)
+		goto error;
 	spin_unlock_irq(cdev->ccwlock);
-	if (ret == 0)
-		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
-	else 
-		pr_debug("ccw_device_offline returned %d, device %s\n",
-			 ret, cdev->dev.bus_id);
-	return (ret == 0) ? -ENODEV : ret;
+	wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
+		   cdev->private->state == DEV_STATE_DISCONNECTED));
+	return ret;
+
+error:
+	pr_debug("rollback ccw_device_offline returned %d, device %s\n",
+		 ret2, cdev->dev.bus_id);
+	cdev->private->state = DEV_STATE_OFFLINE;
+	spin_unlock_irq(cdev->ccwlock);
+	return ret;
 }
 
 static ssize_t
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index 4531340..9feab04 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -960,6 +960,8 @@ ccw_device_w4sense(struct ccw_device *cdev, enum dev_event dev_event)
 	}
 call_handler:
 	cdev->private->state = DEV_STATE_ONLINE;
+	/* In case sensing interfered with setting the device online */
+	wake_up(&cdev->private->wait_q);
 	/* Call the handler. */
 	if (ccw_device_call_handler(cdev) && cdev->private->flags.doverify)
 		/* Start delayed path verification. */