[patch 34/52] [PATCH] cio: ensure proper locking during device recognition

[Martin Schwidefsky]

From: Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>

Device recognition needs to be started with the ccw device lock
held to prevent race conditions between I/O starting and interrupt
reception.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---

 drivers/s390/cio/device.c |    2 ++
 1 file changed, 2 insertions(+)

Index: quilt-2.6/drivers/s390/cio/device.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device.c	2009-11-13 16:08:18.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device.c	2009-11-13 16:08:19.000000000 +0100
@@ -488,7 +488,9 @@
 {
 	/* Do device recognition, if needed. */
 	if (cdev->private->state == DEV_STATE_BOXED) {
+		spin_lock_irq(cdev->ccwlock);
 		ccw_device_recognition(cdev);
+		spin_unlock_irq(cdev->ccwlock);
 		wait_event(cdev->private->wait_q,
 			   cdev->private->flags.recog_done);
 		if (cdev->private->state != DEV_STATE_OFFLINE)

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