staging: fsl-mc: Fix crash in fsl_mc_device_remove()

Only call fsl_mc_io_destroy() if the DPRC being removed
actually had an mc_io object associated with. Child DPRCs
that have not been bound to the DPRC driver or the VFIO driver
will not have an mc_io associated with them.
Signed-off-by: J. German Rivera <German.Rivera@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fsl-mc/bus/dprc-driver.c

@@ -167,7 +167,6 @@ static void dprc_add_new_devices(struct fsl_mc_device *mc_bus_dev,
 
 	for (i = 0; i < num_child_objects_in_mc; i++) {
 		struct fsl_mc_device *child_dev;
-		struct fsl_mc_io *mc_io = NULL;
 		struct dprc_obj_desc *obj_desc = &obj_desc_array[i];
 
 		if (strlen(obj_desc->type) == 0)
@@ -182,15 +181,11 @@ static void dprc_add_new_devices(struct fsl_mc_device *mc_bus_dev,
 			continue;
 		}
 
-		error = fsl_mc_device_add(obj_desc, mc_io, &mc_bus_dev->dev,
+		error = fsl_mc_device_add(obj_desc, NULL, &mc_bus_dev->dev,
 					  &child_dev);
-		if (error < 0) {
-			if (mc_io)
-				fsl_destroy_mc_io(mc_io);
-
+		if (error < 0)
 			continue;
 	}
-	}
 }
 
 static void dprc_init_all_resource_pools(struct fsl_mc_device *mc_bus_dev)

drivers/staging/fsl-mc/bus/mc-bus.c

@@ -444,15 +444,16 @@ void fsl_mc_device_remove(struct fsl_mc_device *mc_dev)
 	put_device(&mc_dev->dev);
 
 	if (strcmp(mc_dev->obj_desc.type, "dprc") == 0) {
-		struct fsl_mc_io *mc_io = mc_dev->mc_io;
-
 		mc_bus = to_fsl_mc_bus(mc_dev);
-		fsl_destroy_mc_io(mc_io);
+		if (mc_dev->mc_io) {
+			fsl_destroy_mc_io(mc_dev->mc_io);
+			mc_dev->mc_io = NULL;
+		}
+
 		if (&mc_dev->dev == fsl_mc_bus_type.dev_root)
 			fsl_mc_bus_type.dev_root = NULL;
 	}
 
-	mc_dev->mc_io = NULL;
 	if (mc_bus)
 		devm_kfree(mc_dev->dev.parent, mc_bus);
 	else