linux-kernel - [PATCH 4.4 097/342] s390/dasd: fix refcount for PAV reassignment

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Message-Id: <20160301234531.109381316@linuxfoundation.org>
Date:	Tue, 01 Mar 2016 23:54:15 +0000
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	<linux-kernel@...r.kernel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<stable@...r.kernel.org>,
	Stefan Haberland <stefan.haberland@...ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: [PATCH 4.4 097/342] s390/dasd: fix refcount for PAV reassignment

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Haberland <stefan.haberland@...ibm.com>

commit 9d862ababb609439c5d6987f6d3ddd09e703aa0b upstream.

Add refcount to the DASD device when a summary unit check worker is
scheduled. This prevents that the device is set offline with worker
in place.

Signed-off-by: Stefan Haberland <stefan.haberland@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/s390/block/dasd_alias.c |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

--- a/drivers/s390/block/dasd_alias.c
+++ b/drivers/s390/block/dasd_alias.c
@@ -264,8 +264,10 @@ void dasd_alias_disconnect_device_from_l
 		spin_unlock_irqrestore(&lcu->lock, flags);
 		cancel_work_sync(&lcu->suc_data.worker);
 		spin_lock_irqsave(&lcu->lock, flags);
-		if (device == lcu->suc_data.device)
+		if (device == lcu->suc_data.device) {
+			dasd_put_device(device);
 			lcu->suc_data.device = NULL;
+		}
 	}
 	was_pending = 0;
 	if (device == lcu->ruac_data.device) {
@@ -273,8 +275,10 @@ void dasd_alias_disconnect_device_from_l
 		was_pending = 1;
 		cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 		spin_lock_irqsave(&lcu->lock, flags);
-		if (device == lcu->ruac_data.device)
+		if (device == lcu->ruac_data.device) {
+			dasd_put_device(device);
 			lcu->ruac_data.device = NULL;
+		}
 	}
 	private->lcu = NULL;
 	spin_unlock_irqrestore(&lcu->lock, flags);
@@ -549,8 +553,10 @@ static void lcu_update_work(struct work_
 	if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) {
 		DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 			    " alias data in lcu (rc = %d), retry later", rc);
-		schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
+		if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ))
+			dasd_put_device(device);
 	} else {
+		dasd_put_device(device);
 		lcu->ruac_data.device = NULL;
 		lcu->flags &= ~UPDATE_PENDING;
 	}
@@ -593,8 +599,10 @@ static int _schedule_lcu_update(struct a
 	 */
 	if (!usedev)
 		return -EINVAL;
+	dasd_get_device(usedev);
 	lcu->ruac_data.device = usedev;
-	schedule_delayed_work(&lcu->ruac_data.dwork, 0);
+	if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0))
+		dasd_put_device(usedev);
 	return 0;
 }
 
@@ -930,6 +938,7 @@ static void summary_unit_check_handling_
 	/* 3. read new alias configuration */
 	_schedule_lcu_update(lcu, device);
 	lcu->suc_data.device = NULL;
+	dasd_put_device(device);
 	spin_unlock_irqrestore(&lcu->lock, flags);
 }
 
@@ -989,6 +998,8 @@ void dasd_alias_handle_summary_unit_chec
 	}
 	lcu->suc_data.reason = reason;
 	lcu->suc_data.device = device;
+	dasd_get_device(device);
 	spin_unlock(&lcu->lock);
-	schedule_work(&lcu->suc_data.worker);
+	if (!schedule_work(&lcu->suc_data.worker))
+		dasd_put_device(device);
 };