Introduce underlying __TRAILING_OVERLAP() macro to let callers apply
atributes to trailing overlapping members.
For instance, the code below:
| struct flex {
| size_t count;
| int data[];
| };
| struct {
| struct flex f;
| struct foo a;
| struct boo b;
| } __packed instance;
can now be changed to the following, and preserve the __packed
attribute:
| __TRAILING_OVERLAP(struct flex, f, data, __packed,
| struct foo a;
| struct boo b;
| ) instance;
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
include/linux/stddef.h | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/linux/stddef.h b/include/linux/stddef.h
index 701099c67c24..80b6bfb944f0 100644
--- a/include/linux/stddef.h
+++ b/include/linux/stddef.h
@@ -94,7 +94,8 @@ enum {
__DECLARE_FLEX_ARRAY(TYPE, NAME)
/**
- * TRAILING_OVERLAP() - Overlap a flexible-array member with trailing members.
+ * __TRAILING_OVERLAP() - Overlap a flexible-array member with trailing
+ * members.
*
* Creates a union between a flexible-array member (FAM) in a struct and a set
* of additional members that would otherwise follow it.
@@ -102,15 +103,30 @@ enum {
* @TYPE: Flexible structure type name, including "struct" keyword.
* @NAME: Name for a variable to define.
* @FAM: The flexible-array member within @TYPE
+ * @ATTRS: Any struct attributes (usually empty)
* @MEMBERS: Trailing overlapping members.
*/
-#define TRAILING_OVERLAP(TYPE, NAME, FAM, MEMBERS)
\
+#define __TRAILING_OVERLAP(TYPE, NAME, FAM, ATTRS, MEMBERS)
\
union {
\
TYPE NAME;
\
struct {
\
unsigned char __offset_to_FAM[offsetof(TYPE, FAM)];
\
MEMBERS
\
- };
\
+ } ATTRS;
\
}
+/**
+ * TRAILING_OVERLAP() - Overlap a flexible-array member with trailing members.
+ *
+ * Creates a union between a flexible-array member (FAM) in a struct and a set
+ * of additional members that would otherwise follow it.
+ *
+ * @TYPE: Flexible structure type name, including "struct" keyword.
+ * @NAME: Name for a variable to define.
+ * @FAM: The flexible-array member within @TYPE
+ * @MEMBERS: Trailing overlapping members.
+ */
+#define TRAILING_OVERLAP(TYPE, NAME, FAM, MEMBERS)
\
+ __TRAILING_OVERLAP(TYPE, NAME, FAM, /* no attrs */, MEMBERS)
+
#endif
--
2.43.0
