[PATCH 4.4 42/86] mei: bus: call mei_cl_read_start under device lock

[Greg Kroah-Hartman]

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

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

From: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>

commit bc46b45a421a64a0895dd41a34d3d2086e1ac7f6 upstream.

Ensure that mei_cl_read_start is called under the device lock
also in the bus layer. The function updates global ctrl_wr_list
which should be locked.

Signed-off-by: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/misc/mei/bus.c |   15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -222,17 +222,23 @@ EXPORT_SYMBOL_GPL(mei_cldev_recv);
 static void mei_cl_bus_event_work(struct work_struct *work)
 {
 	struct mei_cl_device *cldev;
+	struct mei_device *bus;
 
 	cldev = container_of(work, struct mei_cl_device, event_work);
 
+	bus = cldev->bus;
+
 	if (cldev->event_cb)
 		cldev->event_cb(cldev, cldev->events, cldev->event_context);
 
 	cldev->events = 0;
 
 	/* Prepare for the next read */
-	if (cldev->events_mask & BIT(MEI_CL_EVENT_RX))
+	if (cldev->events_mask & BIT(MEI_CL_EVENT_RX)) {
+		mutex_lock(&bus->device_lock);
 		mei_cl_read_start(cldev->cl, 0, NULL);
+		mutex_unlock(&bus->device_lock);
+	}
 }
 
 /**
@@ -296,6 +302,7 @@ int mei_cldev_register_event_cb(struct m
 				unsigned long events_mask,
 				mei_cldev_event_cb_t event_cb, void *context)
 {
+	struct mei_device *bus = cldev->bus;
 	int ret;
 
 	if (cldev->event_cb)
@@ -308,15 +315,17 @@ int mei_cldev_register_event_cb(struct m
 	INIT_WORK(&cldev->event_work, mei_cl_bus_event_work);
 
 	if (cldev->events_mask & BIT(MEI_CL_EVENT_RX)) {
+		mutex_lock(&bus->device_lock);
 		ret = mei_cl_read_start(cldev->cl, 0, NULL);
+		mutex_unlock(&bus->device_lock);
 		if (ret && ret != -EBUSY)
 			return ret;
 	}
 
 	if (cldev->events_mask & BIT(MEI_CL_EVENT_NOTIF)) {
-		mutex_lock(&cldev->cl->dev->device_lock);
+		mutex_lock(&bus->device_lock);
 		ret = mei_cl_notify_request(cldev->cl, NULL, event_cb ? 1 : 0);
-		mutex_unlock(&cldev->cl->dev->device_lock);
+		mutex_unlock(&bus->device_lock);
 		if (ret)
 			return ret;
 	}