On 31/10/24 06:33, Jan Kara wrote:
On Fri 25-10-24 13:32:58, Gustavo A. R. Silva wrote:
-Wflex-array-member-not-at-end was introduced in GCC-14, and we
are getting ready to enable it, globally.
Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
a flexible structure (`struct shash_desc`) where the size of the
flexible-array member (`__ctx`) is known at compile-time, and
refactor the rest of the code, accordingly.
So, with this, fix 77 of the following warnings:
include/linux/jbd2.h:1800:35: warning: structure containing a flexible array
member is not at the end of another structure [-Wflex-array-member-not-at-end]
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
include/linux/jbd2.h | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 8aef9bb6ad57..ce4560e62d3b 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1796,22 +1796,19 @@ static inline unsigned long
jbd2_log_space_left(journal_t *journal)
static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
const void *address, unsigned int length)
{
- struct {
- struct shash_desc shash;
- char ctx[JBD_MAX_CHECKSUM_SIZE];
- } desc;
+ DEFINE_RAW_FLEX(struct shash_desc, desc, __ctx, 1);
Am I missing some magic here or the 1 above should be
JBD_MAX_CHECKSUM_SIZE?
This seems to be 32-bit code, and the element type of the flex-array
member `__ctx` is `void *`. Therefore, we have:
`sizeof(ctx) == 4` when `char ctx[JBD_MAX_CHECKSUM_SIZE];`
To maintain the same size, we tell `DEFINE_RAW_FLEX()` to allocate `1`
element for the flex array, as in 32-bit `sizeof(void *) == 4`.
--
Gustavo
