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

[Jason Gunthorpe <jgg@nvidia.com>]

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 {