1 files changed, 26 insertions, 4 deletions

diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
index f12401e485fe..1d747f72298b 100644
--- a/include/linux/flex_array.h
+++ b/include/linux/flex_array.h
@@ -31,10 +31,32 @@ struct flex_array {
         };
 };
 
-#define FLEX_ARRAY_INIT(size, total) { { {\
-        .element_size = (size),         \
-        .total_nr_elements = (total),   \
-} } }
+/* Number of bytes left in base struct flex_array, excluding metadata */
+#define FLEX_ARRAY_BASE_BYTES_LEFT                                      \
+        (FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))
+
+/* Number of pointers in base to struct flex_array_part pages */
+#define FLEX_ARRAY_NR_BASE_PTRS                                         \
+        (FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))
+
+/* Number of elements of size that fit in struct flex_array_part */
+#define FLEX_ARRAY_ELEMENTS_PER_PART(size)                              \
+        (FLEX_ARRAY_PART_SIZE / size)
+
+/*
+ * Defines a statically allocated flex array and ensures its parameters are
+ * valid.
+ */
+#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total)         \
+        struct flex_array __arrayname = { { {                           \
+                .element_size = (__element_size),                       \
+                .total_nr_elements = (__total),                         \
+        } } };                                                          \
+        static inline void __arrayname##_invalid_parameter(void)        \
+        {                                                               \
+                BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS *      \
+                        FLEX_ARRAY_ELEMENTS_PER_PART(__element_size));  \
+        }
 
 struct flex_array *flex_array_alloc(int element_size, unsigned int total,
                 gfp_t flags);