mei: bus: stop wait for read during cl state transition

Bus layer omitted check for client state transition while waiting
for read completion
The client state transition may occur for example as result
of firmware initiated reset

Add mei_cl_is_transitioning wrapper to reduce the code
repetition.:

Cc:  <stable@vger.kernel.org> # 3.9+
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/bus.c

@@ -297,10 +297,13 @@ int __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length)
 
 	if (cl->reading_state != MEI_READ_COMPLETE &&
 	    !waitqueue_active(&cl->rx_wait)) {
+
 		mutex_unlock(&dev->device_lock);
 
 		if (wait_event_interruptible(cl->rx_wait,
-				(MEI_READ_COMPLETE == cl->reading_state))) {
+				cl->reading_state == MEI_READ_COMPLETE  ||
+				mei_cl_is_transitioning(cl))) {
+
 			if (signal_pending(current))
 				return -EINTR;
 			return -ERESTARTSYS;

drivers/misc/mei/client.h

@@ -90,6 +90,12 @@ static inline bool mei_cl_is_connected(struct mei_cl *cl)
 		cl->dev->dev_state == MEI_DEV_ENABLED &&
 		cl->state == MEI_FILE_CONNECTED);
 }
+static inline bool mei_cl_is_transitioning(struct mei_cl *cl)
+{
+	return (MEI_FILE_INITIALIZING == cl->state ||
+		MEI_FILE_DISCONNECTED == cl->state ||
+		MEI_FILE_DISCONNECTING == cl->state);
+}
 
 bool mei_cl_is_other_connecting(struct mei_cl *cl);
 int mei_cl_disconnect(struct mei_cl *cl);

drivers/misc/mei/main.c

@@ -249,19 +249,16 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
 		mutex_unlock(&dev->device_lock);
 
 		if (wait_event_interruptible(cl->rx_wait,
-			(MEI_READ_COMPLETE == cl->reading_state ||
-			 MEI_FILE_INITIALIZING == cl->state ||
-			 MEI_FILE_DISCONNECTED == cl->state ||
-			 MEI_FILE_DISCONNECTING == cl->state))) {
+				MEI_READ_COMPLETE == cl->reading_state ||
+				mei_cl_is_transitioning(cl))) {
+
 			if (signal_pending(current))
 				return -EINTR;
 			return -ERESTARTSYS;
 		}
 
 		mutex_lock(&dev->device_lock);
-		if (MEI_FILE_INITIALIZING == cl->state ||
-		    MEI_FILE_DISCONNECTED == cl->state ||
-		    MEI_FILE_DISCONNECTING == cl->state) {
+		if (mei_cl_is_transitioning(cl)) {
 			rets = -EBUSY;
 			goto out;
 		}