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

Zhu Yanjun
2025-12-04T05:08:57Z

在 2025/12/2 10:13, Jason Gunthorpe 写道:
> 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;

drivers/infiniband/sw/rxe/rxe_resp.c: In function get_srq_wqe:
drivers/infiniband/sw/rxe/rxe_resp.c:289:41: error: struct rxe_recv_wqe
has no member named wqe
289 | qp->resp.wqe = &qp->resp.srq_wqe.wqe;
| ^

struct {
struct rxe_recv_wqe wqe;
struct ib_sge sge[RXE_MAX_SGE];
} srq_wqe;

IMO, it is better to move this struct to the end of the struct
rxe_resp_info.

Yanjun.Zhu

> };
>
> 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 {