s390/cio: fix driver callback initialization for ccw consoles

ccw consoles are in use before they can be properly registered with
the driver core. For devices which are in use by a device driver we
rely on the ccw_device's pointer to the driver callbacks to be valid.
For ccw consoles this pointer is NULL until they are registered later
during boot and we dereferenced this pointer. This worked by
chance on 64 bit builds (cdev->drv was NULL but the optional callback
cdev->drv->path_event was also NULL by coincidence) and was unnoticed
until we received reports about boot failures on 31 bit systems.
Fix it by initializing the driver pointer for ccw consoles.

Cc: <stable@vger.kernel.org> # 3.10+
Reported-by: Mike Frysinger <vapier@gentoo.org>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

4 files changed, 12 insertions, 8 deletions

diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index eb5d227..bb86494 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -922,7 +922,7 @@ static int __init con3215_init(void)
 		raw3215_freelist = req;
 	}
 
-	cdev = ccw_device_probe_console();
+	cdev = ccw_device_probe_console(&raw3215_ccw_driver);
 	if (IS_ERR(cdev))
 		return -ENODEV;
 
diff --git a/drivers/s390/char/con3270.c b/drivers/s390/char/con3270.c
index 699fd3e..bb6b0df5 100644
--- a/drivers/s390/char/con3270.c
+++ b/drivers/s390/char/con3270.c
@@ -576,7 +576,6 @@ static struct console con3270 = {
 static int __init
 con3270_init(void)
 {
-	struct ccw_device *cdev;
 	struct raw3270 *rp;
 	void *cbuf;
 	int i;
@@ -591,10 +590,7 @@ con3270_init(void)
 		cpcmd("TERM AUTOCR OFF", NULL, 0, NULL);
 	}
 
-	cdev = ccw_device_probe_console();
-	if (IS_ERR(cdev))
-		return -ENODEV;
-	rp = raw3270_setup_console(cdev);
+	rp = raw3270_setup_console();
 	if (IS_ERR(rp))
 		return PTR_ERR(rp);
 
diff --git a/drivers/s390/char/raw3270.c b/drivers/s390/char/raw3270.c
index 2cdec21..de2c048 100644
--- a/drivers/s390/char/raw3270.c
+++ b/drivers/s390/char/raw3270.c
@@ -776,16 +776,24 @@ raw3270_setup_device(struct ccw_device *cdev, struct raw3270 *rp, char *ascebc)
 }
 
 #ifdef CONFIG_TN3270_CONSOLE
+/* Tentative definition - see below for actual definition. */
+static struct ccw_driver raw3270_ccw_driver;
+
 /*
  * Setup 3270 device configured as console.
  */
-struct raw3270 __init *raw3270_setup_console(struct ccw_device *cdev)
+struct raw3270 __init *raw3270_setup_console(void)
 {
+	struct ccw_device *cdev;
 	unsigned long flags;
 	struct raw3270 *rp;
 	char *ascebc;
 	int rc;
 
+	cdev = ccw_device_probe_console(&raw3270_ccw_driver);
+	if (IS_ERR(cdev))
+		return ERR_CAST(cdev);
+
 	rp = kzalloc(sizeof(struct raw3270), GFP_KERNEL | GFP_DMA);
 	ascebc = kzalloc(256, GFP_KERNEL);
 	rc = raw3270_setup_device(cdev, rp, ascebc);
diff --git a/drivers/s390/char/raw3270.h b/drivers/s390/char/raw3270.h
index 7b73ff8..359276a 100644
--- a/drivers/s390/char/raw3270.h
+++ b/drivers/s390/char/raw3270.h
@@ -190,7 +190,7 @@ raw3270_put_view(struct raw3270_view *view)
 		wake_up(&raw3270_wait_queue);
 }
 
-struct raw3270 *raw3270_setup_console(struct ccw_device *cdev);
+struct raw3270 *raw3270_setup_console(void);
 void raw3270_wait_cons_dev(struct raw3270 *);
 
 /* Notifier for device addition/removal */