RDMA/cma: Revert INIT-INIT patch

The net/sunrpc/xprtrdma module creates its QP using rdma_create_qp() and
immediately post receives, implicitly assuming the QP is in the INIT state
and thus valid for ib_post_recv().

The patch noted in Fixes: removed the RESET->INIT modifiy from
rdma_create_qp(), breaking NFS rdma for verbs providers that fail the
ib_post_recv() for a bad state.

This situation was proven using kprobes in rvt_post_recv() and
rvt_modify_qp(). The traces showed that the rvt_post_recv() failed before
ANY modify QP and that the current state was RESET.

Fix by reverting the patch below.

Fixes: dc70f7c3 ("RDMA/cma: Remove unnecessary INIT->INIT transition")
Link: https://lore.kernel.org/r/1627583182-81330-1-git-send-email-mike.marciniszyn@cornelisnetworks.com
Cc: Haakon Bugge <haakon.bugge@oracle.com>
Cc: Chuck Lever III <chuck.lever@oracle.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/cma.c

@@ -926,12 +926,25 @@ static int cma_init_ud_qp(struct rdma_id_private *id_priv, struct ib_qp *qp)
 	return ret;
 }
 
+static int cma_init_conn_qp(struct rdma_id_private *id_priv, struct ib_qp *qp)
+{
+	struct ib_qp_attr qp_attr;
+	int qp_attr_mask, ret;
+
+	qp_attr.qp_state = IB_QPS_INIT;
+	ret = rdma_init_qp_attr(&id_priv->id, &qp_attr, &qp_attr_mask);
+	if (ret)
+		return ret;
+
+	return ib_modify_qp(qp, &qp_attr, qp_attr_mask);
+}
+
 int rdma_create_qp(struct rdma_cm_id *id, struct ib_pd *pd,
 		   struct ib_qp_init_attr *qp_init_attr)
 {
 	struct rdma_id_private *id_priv;
 	struct ib_qp *qp;
-	int ret = 0;
+	int ret;
 
 	id_priv = container_of(id, struct rdma_id_private, id);
 	if (id->device != pd->device) {
@@ -948,6 +961,8 @@ int rdma_create_qp(struct rdma_cm_id *id, struct ib_pd *pd,
 
 	if (id->qp_type == IB_QPT_UD)
 		ret = cma_init_ud_qp(id_priv, qp);
+	else
+		ret = cma_init_conn_qp(id_priv, qp);
 	if (ret)
 		goto out_destroy;