mei: bus: make a client pointer always available

Change life time of the client pointer, allocate it upon client device
creation and free it upon device destruction, instead of upon
connection and disconnection.
This helps to eliminate racy NULL checks in the bus code.

Signed-off-by: Alexander Usyskin <[e-mail]>
Signed-off-by: Tomas Winkler <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/mei/bus.c

···
 {
 	struct mei_cl *cl = cldev->cl;
 
-	if (cl == NULL)
-		return -ENODEV;
-
 	return __mei_cl_send(cl, buf, length, MEI_CL_IO_TX_BLOCKING);
 }
 EXPORT_SYMBOL_GPL(mei_cldev_send);
···
 ssize_t mei_cldev_recv(struct mei_cl_device *cldev, u8 *buf, size_t length)
 {
 	struct mei_cl *cl = cldev->cl;
-
-	if (cl == NULL)
-		return -ENODEV;
 
 	return __mei_cl_recv(cl, buf, length);
 }
···
  */
 bool mei_cldev_enabled(struct mei_cl_device *cldev)
 {
-	return cldev->cl && mei_cl_is_connected(cldev->cl);
+	return mei_cl_is_connected(cldev->cl);
 }
 EXPORT_SYMBOL_GPL(mei_cldev_enabled);
 
···
 
 	cl = cldev->cl;
 
-	if (!cl) {
+	if (cl->state == MEI_FILE_UNINITIALIZED) {
 		mutex_lock(&bus->device_lock);
-		cl = mei_cl_alloc_linked(bus);
+		ret = mei_cl_link(cl);
 		mutex_unlock(&bus->device_lock);
-		if (IS_ERR(cl))
-			return PTR_ERR(cl);
+		if (ret)
+			return ret;
 		/* update pointers */
-		cldev->cl = cl;
 		cl->cldev = cldev;
 	}
 
···
 	struct mei_cl *cl;
 	int err;
 
-	if (!cldev || !cldev->cl)
+	if (!cldev)
 		return -ENODEV;
 
 	cl = cldev->cl;
···
 	/* Flush queues and remove any pending read */
 	mei_cl_flush_queues(cl, NULL);
 	mei_cl_unlink(cl);
-
-	kfree(cl);
-	cldev->cl = NULL;
 
 	mutex_unlock(&bus->device_lock);
 	return err;
···
 
 	mei_me_cl_put(cldev->me_cl);
 	mei_dev_bus_put(cldev->bus);
+	kfree(cldev->cl);
 	kfree(cldev);
 }
 
···
 						  struct mei_me_client *me_cl)
 {
 	struct mei_cl_device *cldev;
+	struct mei_cl *cl;
 
 	cldev = kzalloc(sizeof(struct mei_cl_device), GFP_KERNEL);
 	if (!cldev)
 		return NULL;
+
+	cl = mei_cl_allocate(bus);
+	if (!cl) {
+		kfree(cldev);
+		return NULL;
+	}
 
 	device_initialize(&cldev->dev);
 	cldev->dev.parent = bus->dev;
···
 	cldev->dev.type   = &mei_cl_device_type;
 	cldev->bus        = mei_dev_bus_get(bus);
 	cldev->me_cl      = mei_me_cl_get(me_cl);
+	cldev->cl         = cl;
 	mei_cl_bus_set_name(cldev);
 	cldev->is_added   = 0;
 	INIT_LIST_HEAD(&cldev->bus_list);