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>

4 files changed, 23 insertions, 21 deletions

diff --git a/drivers/infiniband/hw/mlx4/mad.c b/drivers/infiniband/hw/mlx4/mad.c
index 8d730a69793d..e5466d786bb1 100644
--- a/drivers/infiniband/hw/mlx4/mad.c
+++ b/drivers/infiniband/hw/mlx4/mad.c
@@ -506,7 +506,7 @@ int mlx4_ib_send_to_slave(struct mlx4_ib_dev *dev, int slave, u8 port,
 {
 	struct ib_sge list;
 	struct ib_ud_wr wr;
-	struct ib_send_wr *bad_wr;
+	const struct ib_send_wr *bad_wr;
 	struct mlx4_ib_demux_pv_ctx *tun_ctx;
 	struct mlx4_ib_demux_pv_qp *tun_qp;
 	struct mlx4_rcv_tunnel_mad *tun_mad;
@@ -1310,7 +1310,8 @@ static int mlx4_ib_post_pv_qp_buf(struct mlx4_ib_demux_pv_ctx *ctx,
 				  int index)
 {
 	struct ib_sge sg_list;
-	struct ib_recv_wr recv_wr, *bad_recv_wr;
+	struct ib_recv_wr recv_wr;
+	const struct ib_recv_wr *bad_recv_wr;
 	int size;
 
 	size = (tun_qp->qp->qp_type == IB_QPT_UD) ?
@@ -1361,7 +1362,7 @@ int mlx4_ib_send_to_wire(struct mlx4_ib_dev *dev, int slave, u8 port,
 {
 	struct ib_sge list;
 	struct ib_ud_wr wr;
-	struct ib_send_wr *bad_wr;
+	const struct ib_send_wr *bad_wr;
 	struct mlx4_ib_demux_pv_ctx *sqp_ctx;
 	struct mlx4_ib_demux_pv_qp *sqp;
 	struct mlx4_mad_snd_buf *sqp_mad;
diff --git a/drivers/infiniband/hw/mlx4/mlx4_ib.h b/drivers/infiniband/hw/mlx4/mlx4_ib.h
index 1a0fad30633b..e817a2f55546 100644
--- a/drivers/infiniband/hw/mlx4/mlx4_ib.h
+++ b/drivers/infiniband/hw/mlx4/mlx4_ib.h
@@ -775,8 +775,8 @@ int mlx4_ib_modify_srq(struct ib_srq *ibsrq, struct ib_srq_attr *attr,
 int mlx4_ib_query_srq(struct ib_srq *srq, struct ib_srq_attr *srq_attr);
 int mlx4_ib_destroy_srq(struct ib_srq *srq);
 void mlx4_ib_free_srq_wqe(struct mlx4_ib_srq *srq, int wqe_index);
-int mlx4_ib_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
-			  struct ib_recv_wr **bad_wr);
+int mlx4_ib_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
+			  const struct ib_recv_wr **bad_wr);
 
 struct ib_qp *mlx4_ib_create_qp(struct ib_pd *pd,
 				struct ib_qp_init_attr *init_attr,
@@ -788,10 +788,10 @@ int mlx4_ib_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
 		      int attr_mask, struct ib_udata *udata);
 int mlx4_ib_query_qp(struct ib_qp *ibqp, struct ib_qp_attr *qp_attr, int qp_attr_mask,
 		     struct ib_qp_init_attr *qp_init_attr);
-int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
-		      struct ib_send_wr **bad_wr);
-int mlx4_ib_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
-		      struct ib_recv_wr **bad_wr);
+int mlx4_ib_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
+		      const struct ib_send_wr **bad_wr);
+int mlx4_ib_post_recv(struct ib_qp *ibqp, const struct ib_recv_wr *wr,
+		      const struct ib_recv_wr **bad_wr);
 
 int mlx4_MAD_IFC(struct mlx4_ib_dev *dev, int mad_ifc_flags,
 		 int port, const struct ib_wc *in_wc, const struct ib_grh *in_grh,
diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index 44fc684b5e3a..b431757d4668 100644
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -3569,8 +3569,8 @@ static void add_zero_len_inline(void *wqe)
 	inl->byte_count = cpu_to_be32(1 << 31);
 }
 
-static int _mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
-			      struct ib_send_wr **bad_wr, bool drain)
+static int _mlx4_ib_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
+			      const struct ib_send_wr **bad_wr, bool drain)
 {
 	struct mlx4_ib_qp *qp = to_mqp(ibqp);
 	void *wqe;
@@ -3901,14 +3901,14 @@ out:
 	return err;
 }
 
-int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
-		      struct ib_send_wr **bad_wr)
+int mlx4_ib_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
+		      const struct ib_send_wr **bad_wr)
 {
 	return _mlx4_ib_post_send(ibqp, wr, bad_wr, false);
 }
 
-static int _mlx4_ib_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
-			      struct ib_recv_wr **bad_wr, bool drain)
+static int _mlx4_ib_post_recv(struct ib_qp *ibqp, const struct ib_recv_wr *wr,
+			      const struct ib_recv_wr **bad_wr, bool drain)
 {
 	struct mlx4_ib_qp *qp = to_mqp(ibqp);
 	struct mlx4_wqe_data_seg *scat;
@@ -3995,8 +3995,8 @@ out:
 	return err;
 }
 
-int mlx4_ib_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
-		      struct ib_recv_wr **bad_wr)
+int mlx4_ib_post_recv(struct ib_qp *ibqp, const struct ib_recv_wr *wr,
+		      const struct ib_recv_wr **bad_wr)
 {
 	return _mlx4_ib_post_recv(ibqp, wr, bad_wr, false);
 }
@@ -4536,7 +4536,7 @@ void mlx4_ib_drain_sq(struct ib_qp *qp)
 	struct ib_cq *cq = qp->send_cq;
 	struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR };
 	struct mlx4_ib_drain_cqe sdrain;
-	struct ib_send_wr *bad_swr;
+	const struct ib_send_wr *bad_swr;
 	struct ib_rdma_wr swr = {
 		.wr = {
 			.next = NULL,
@@ -4571,7 +4571,8 @@ void mlx4_ib_drain_rq(struct ib_qp *qp)
 	struct ib_cq *cq = qp->recv_cq;
 	struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR };
 	struct mlx4_ib_drain_cqe rdrain;
-	struct ib_recv_wr rwr = {}, *bad_rwr;
+	struct ib_recv_wr rwr = {};
+	const struct ib_recv_wr *bad_rwr;
 	int ret;
 	struct mlx4_ib_dev *dev = to_mdev(qp->device);
 	struct mlx4_dev *mdev = dev->dev;
diff --git a/drivers/infiniband/hw/mlx4/srq.c b/drivers/infiniband/hw/mlx4/srq.c
index ebee56cbc0e2..3731b31c3653 100644
--- a/drivers/infiniband/hw/mlx4/srq.c
+++ b/drivers/infiniband/hw/mlx4/srq.c
@@ -307,8 +307,8 @@ void mlx4_ib_free_srq_wqe(struct mlx4_ib_srq *srq, int wqe_index)
 	spin_unlock(&srq->lock);
 }
 
-int mlx4_ib_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
-			  struct ib_recv_wr **bad_wr)
+int mlx4_ib_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
+			  const struct ib_recv_wr **bad_wr)
 {
 	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
 	struct mlx4_wqe_srq_next_seg *next;