Currently, to statically initialize the struct members of the `type`
object created by _DEFINE_FLEX(), the internal `obj` member must be
explicitly referenced at the call site. See:
struct flex {
int a;
int b;
struct foo flex_array[];
};
_DEFINE_FLEX(struct flex, instance, flex_array,
FIXED_SIZE, = {
.obj = {
.a = 0,
.b = 1,
},
});
This leaks _DEFINE_FLEX() internal implementation details and make
the helper harder to use and read.
Fix this and allow for a more natural and intuitive C99 init-style:
_DEFINE_FLEX(struct flex, instance, flex_array,
FIXED_SIZE, = {
.a = 0,
.b = 1,
});
Note that before these changes, the `initializer` argument was optional,
but now it's required.
Also, update "counter" member initialization in DEFINE_FLEX().
Fixes: 26dd68d293fd ("overflow: add DEFINE_FLEX() for on-stack allocs")
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
Changes in v3:
- Fix changelog text: s/_DEFINE_RAW_FLEX/_DEFINE_FLEX
Changes in v2:
- Update kernel-doc block for _DEFINE_FLEX(). (Kees)
- Update changelog text - `initializer` argument is now required.
- Link: https://lore.kernel.org/all/aBP0b3gfurLFDlwY@kspp/
v1:
- Link: https://lore.kernel.org/linux-hardening/aBK2TUEeQfCFop9Y@kspp/
include/linux/overflow.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index 69533e703be5..b50c8b30a14a 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -396,7 +396,7 @@ static inline size_t __must_check size_sub(size_t minuend,
size_t subtrahend)
* @name: Name for a variable to define.
* @member: Name of the array member.
* @count: Number of elements in the array; must be compile-time const.
- * @initializer: initializer expression (could be empty for no init).
+ * @initializer: Initializer expression (e.g., pass `= { }` at minimum).
*/
#define _DEFINE_FLEX(type, name, member, count, initializer...)
\
_Static_assert(__builtin_constant_p(count),
\
@@ -404,7 +404,7 @@ static inline size_t __must_check size_sub(size_t minuend,
size_t subtrahend)
union {
\
u8 bytes[struct_size_t(type, member, count)];
\
type obj;
\
- } name##_u initializer;
\
+ } name##_u = { .obj initializer };
\
type *name = (type *)&name##_u
/**
@@ -444,7 +444,7 @@ static inline size_t __must_check size_sub(size_t minuend,
size_t subtrahend)
* elements in array @member.
*/
#define DEFINE_FLEX(TYPE, NAME, MEMBER, COUNTER, COUNT) \
- _DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .obj.COUNTER = COUNT, })
+ _DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .COUNTER = COUNT, })
/**
* STACK_FLEX_ARRAY_SIZE() - helper macro for DEFINE_FLEX() family.
--
2.43.0
