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 <gustavoars@xxxxxxxxxx> --- 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
