RDMA/rxe: Enforce IBA C11-17

Add a counter to keep track of the number of WQs connected to a CQ and
return an error if destroy_cq() is called while the counter is non zero.

Link: https://lore.kernel.org/r/20220421014042.26985-8-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/sw/rxe/rxe_qp.c

@@ -322,6 +322,9 @@ int rxe_qp_from_init(struct rxe_dev *rxe, struct rxe_qp *qp, struct rxe_pd *pd,
 	qp->scq			= scq;
 	qp->srq			= srq;
 
+	atomic_inc(&rcq->num_wq);
+	atomic_inc(&scq->num_wq);
+
 	rxe_qp_init_misc(rxe, qp, init);
 
 	err = rxe_qp_init_req(rxe, qp, init, udata, uresp);
@@ -341,6 +344,9 @@ int rxe_qp_from_init(struct rxe_dev *rxe, struct rxe_qp *qp, struct rxe_pd *pd,
 	rxe_queue_cleanup(qp->sq.queue);
 	qp->sq.queue = NULL;
 err1:
+	atomic_dec(&rcq->num_wq);
+	atomic_dec(&scq->num_wq);
+
 	qp->pd = NULL;
 	qp->rcq = NULL;
 	qp->scq = NULL;
@@ -798,10 +804,14 @@ static void rxe_qp_do_cleanup(struct work_struct *work)
 	if (qp->rq.queue)
 		rxe_queue_cleanup(qp->rq.queue);
 
+	atomic_dec(&qp->scq->num_wq);
 	if (qp->scq)
 		rxe_put(qp->scq);
+
+	atomic_dec(&qp->rcq->num_wq);
 	if (qp->rcq)
 		rxe_put(qp->rcq);
+
 	if (qp->pd)
 		rxe_put(qp->pd);
 

drivers/infiniband/sw/rxe/rxe_verbs.c

@@ -795,6 +795,12 @@ static int rxe_destroy_cq(struct ib_cq *ibcq, struct ib_udata *udata)
 {
 	struct rxe_cq *cq = to_rcq(ibcq);
 
+	/* See IBA C11-17: The CI shall return an error if this Verb is
+	 * invoked while a Work Queue is still associated with the CQ.
+	 */
+	if (atomic_read(&cq->num_wq))
+		return -EINVAL;
+
 	rxe_cq_disable(cq);
 
 	rxe_put(cq);

drivers/infiniband/sw/rxe/rxe_verbs.h

@@ -67,6 +67,7 @@ struct rxe_cq {
 	bool			is_dying;
 	bool			is_user;
 	struct tasklet_struct	comp_task;
+	atomic_t		num_wq;
 };
 
 enum wqe_state {