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

Jason Gunthorpe
2025-12-02T18:13:43Z

On Tue, Nov 11, 2025 at 12:35:02PM +0900, Gustavo A. R. Silva wrote:
> 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;

I think this existing is just a mess, can we fix it properly?

What this code wants to do is to have rxe_resp_info allocate a
rxe_recv_wqe and have a maximum size of its flex array pre-allocated.

Probably like this, though maybe we need a FLEX version of the
INIT_RDMA_OBJ_SIZE macro to make it safer.

Zhu, this seems like a good thing for you to look at?

diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
index 38d8c408320f11..189eaa59a5fb14 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -1524,7 +1524,8 @@ static const struct ib_device_ops rxe_dev_ops = {
INIT_RDMA_OBJ_SIZE(ib_ah, rxe_ah, ibah),
INIT_RDMA_OBJ_SIZE(ib_cq, rxe_cq, ibcq),
INIT_RDMA_OBJ_SIZE(ib_pd, rxe_pd, ibpd),
- INIT_RDMA_OBJ_SIZE(ib_qp, rxe_qp, ibqp),
+ /* For resp.srq_wqe.dma.sge */
+ INIT_RDMA_OBJ_SIZE(ib_qp, rxe_qp, ibqp) + RXE_MAX_SGE*sizeof(struct ib_sge),
INIT_RDMA_OBJ_SIZE(ib_srq, rxe_srq, ibsrq),
INIT_RDMA_OBJ_SIZE(ib_ucontext, rxe_ucontext, ibuc),
INIT_RDMA_OBJ_SIZE(ib_mw, rxe_mw, ibmw),
diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
index fd48075810dd10..dda741ec3ac701 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.
*/
@@ -232,6 +226,9 @@ struct rxe_resp_info {
unsigned int res_head;
unsigned int res_tail;
struct resp_res *res;
+
+ /* SRQ only. srq_wqe.dma.sge is a flex array */
+ struct rxe_recv_wqe srq_wqe;
};

struct rxe_qp {
@@ -269,7 +266,6 @@ 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 +285,7 @@ struct rxe_qp {
spinlock_t state_lock; /* guard requester and completer */

struct execute_work cleanup_work;
+ struct rxe_resp_info resp;
};

enum {