[PATCH][next] RDMA/rxe: Avoid -Wflex-array-member-not-at-end warnings

Gustavo A. R. Silva
2025-11-11T03:35:07Z

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Use the new TRAILING_OVERLAP() helper to fix the following warning:

21 drivers/infiniband/sw/rxe/rxe_verbs.h:271:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

This helper creates a union between a flexible-array member (FAM) and a
set of MEMBERS that would otherwise follow it.

This overlays the trailing MEMBER struct ib_sge sge[RXE_MAX_SGE]; onto
the FAM struct rxe_recv_wqe::dma.sge, while keeping the FAM and the
start of MEMBER aligned.

The static_assert() ensures this alignment remains, and it's
intentionally placed inmediately after the related structure --no
blank line in between.

Lastly, move the conflicting declaration struct rxe_resp_info resp;
to the end of the corresponding structure.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/infiniband/sw/rxe/rxe_verbs.h | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
index fd48075810dd..6498d61e8956 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.h
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
@@ -219,12 +219,6 @@ struct rxe_resp_info {
u32 rkey;
u32 length;

- /* SRQ only */
- struct {
- struct rxe_recv_wqe wqe;
- struct ib_sge sge[RXE_MAX_SGE];
- } srq_wqe;
-
/* Responder resources. It's a circular list where the oldest
* resource is dropped first.
*/
@@ -232,7 +226,15 @@ struct rxe_resp_info {
unsigned int res_head;
unsigned int res_tail;
struct resp_res *res;
+
+ /* SRQ only */
+ /* Must be last as it ends in a flexible-array member. */
+ TRAILING_OVERLAP(struct rxe_recv_wqe, wqe, dma.sge,
+ struct ib_sge sge[RXE_MAX_SGE];
+ ) srq_wqe;
};
+static_assert(offsetof(struct rxe_resp_info, srq_wqe.wqe.dma.sge) ==
+ offsetof(struct rxe_resp_info, srq_wqe.sge));

struct rxe_qp {
struct ib_qp ibqp;
@@ -269,7 +271,6 @@ struct rxe_qp {

struct rxe_req_info req;
struct rxe_comp_info comp;
- struct rxe_resp_info resp;

atomic_t ssn;
atomic_t skb_out;
@@ -289,6 +290,9 @@ struct rxe_qp {
spinlock_t state_lock; /* guard requester and completer */

struct execute_work cleanup_work;
+
+ /* Must be last as it ends in a flexible-array member. */
+ struct rxe_resp_info resp;
};

enum {
--
2.43.0