RDMA, core and ULPs: Declare ib_post_send() and ib_post_recv() arguments const

Since neither ib_post_send() nor ib_post_recv() modify the data structure
their second argument points at, declare that argument const. This change
makes it necessary to declare the 'bad_wr' argument const too and also to
modify all ULPs that call ib_post_send(), ib_post_recv() or
ib_post_srq_recv(). This patch does not change any functionality but makes
it possible for the compiler to verify whether the
ib_post_(send|recv|srq_recv) really do not modify the posted work request.

To make this possible, only one cast had to be introduce that casts away
constness, namely in rpcrdma_post_recvs(). The only way I can think of to
avoid that cast is to introduce an additional loop in that function or to
change the data type of bad_wr from struct ib_recv_wr ** into int
(an index that refers to an element in the work request list). However,
both approaches would require even more extensive changes than this
patch.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/ocrdma/ocrdma_verbs.c

@@ -2166,8 +2166,8 @@ static void ocrdma_ring_sq_db(struct ocrdma_qp *qp)
 	iowrite32(val, qp->sq_db);
 }
 
-int ocrdma_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
-		     struct ib_send_wr **bad_wr)
+int ocrdma_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
+		     const struct ib_send_wr **bad_wr)
 {
 	int status = 0;
 	struct ocrdma_qp *qp = get_ocrdma_qp(ibqp);
@@ -2278,8 +2278,8 @@ static void ocrdma_ring_rq_db(struct ocrdma_qp *qp)
 	iowrite32(val, qp->rq_db);
 }
 
-static void ocrdma_build_rqe(struct ocrdma_hdr_wqe *rqe, struct ib_recv_wr *wr,
-			     u16 tag)
+static void ocrdma_build_rqe(struct ocrdma_hdr_wqe *rqe,
+			     const struct ib_recv_wr *wr, u16 tag)
 {
 	u32 wqe_size = 0;
 	struct ocrdma_sge *sge;
@@ -2299,8 +2299,8 @@ static void ocrdma_build_rqe(struct ocrdma_hdr_wqe *rqe, struct ib_recv_wr *wr,
 	ocrdma_cpu_to_le32(rqe, wqe_size);
 }
 
-int ocrdma_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
-		     struct ib_recv_wr **bad_wr)
+int ocrdma_post_recv(struct ib_qp *ibqp, const struct ib_recv_wr *wr,
+		     const struct ib_recv_wr **bad_wr)
 {
 	int status = 0;
 	unsigned long flags;
@@ -2369,8 +2369,8 @@ static void ocrdma_ring_srq_db(struct ocrdma_srq *srq)
 	iowrite32(val, srq->db + OCRDMA_DB_GEN2_SRQ_OFFSET);
 }
 
-int ocrdma_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
-			 struct ib_recv_wr **bad_wr)
+int ocrdma_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
+			 const struct ib_recv_wr **bad_wr)
 {
 	int status = 0;
 	unsigned long flags;

drivers/infiniband/hw/ocrdma/ocrdma_verbs.h

@@ -43,10 +43,10 @@
 #ifndef __OCRDMA_VERBS_H__
 #define __OCRDMA_VERBS_H__
 
-int ocrdma_post_send(struct ib_qp *, struct ib_send_wr *,
-		     struct ib_send_wr **bad_wr);
-int ocrdma_post_recv(struct ib_qp *, struct ib_recv_wr *,
-		     struct ib_recv_wr **bad_wr);
+int ocrdma_post_send(struct ib_qp *, const struct ib_send_wr *,
+		     const struct ib_send_wr **bad_wr);
+int ocrdma_post_recv(struct ib_qp *, const struct ib_recv_wr *,
+		     const struct ib_recv_wr **bad_wr);
 
 int ocrdma_poll_cq(struct ib_cq *, int num_entries, struct ib_wc *wc);
 int ocrdma_arm_cq(struct ib_cq *, enum ib_cq_notify_flags flags);
@@ -100,8 +100,8 @@ int ocrdma_modify_srq(struct ib_srq *, struct ib_srq_attr *,
 		      enum ib_srq_attr_mask, struct ib_udata *);
 int ocrdma_query_srq(struct ib_srq *, struct ib_srq_attr *);
 int ocrdma_destroy_srq(struct ib_srq *);
-int ocrdma_post_srq_recv(struct ib_srq *, struct ib_recv_wr *,
-			 struct ib_recv_wr **bad_recv_wr);
+int ocrdma_post_srq_recv(struct ib_srq *, const struct ib_recv_wr *,
+			 const struct ib_recv_wr **bad_recv_wr);
 
 int ocrdma_dereg_mr(struct ib_mr *);
 struct ib_mr *ocrdma_get_dma_mr(struct ib_pd *, int acc);