of: Make of_fwnode_handle() safer

On the expense of a little bit more complexity in the of_fwnode_handle()
macro, make the macro result in NULL in case its argument is NULL while
still referencing it only once.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/include/linux/of.h b/include/linux/of.h
index 50fcdb5..f05c87f 100644 (file)
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -159,7 +159,13 @@ static inline struct device_node *to_of_node(struct fwnode_handle *fwnode)
                container_of(fwnode, struct device_node, fwnode) : NULL;
 }
 
-#define of_fwnode_handle(node) (&(node)->fwnode)
+#define of_fwnode_handle(node)                                         \
+       ({                                                              \
+               typeof(node) __of_fwnode_handle_node = (node);          \
+                                                                       \
+               __of_fwnode_handle_node ?                               \
+                       &__of_fwnode_handle_node->fwnode : NULL;        \
+       })
 
 static inline bool of_have_populated_dt(void)
 {