IB/{rdmavt, qib, hfi1}: Convert to new completion API

Convert all completions to use the new completion routine that
fixes a race between post send and completion where fields from
a SWQE can be read after SWQE has been freed.

This patch also addresses issues reported in
https://marc.info/?l=linux-kernel&m=155656897409107&w=2.

The reserved operation path has no need for any barrier.

The barrier for the other path is addressed by the
smp_load_acquire() barrier.

Cc: Andrea Parri <andrea.parri@amarulasolutions.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/qib/qib_rc.c

@@ -921,20 +921,11 @@ void qib_rc_send_complete(struct rvt_qp *qp, struct ib_header *hdr)
 		rvt_add_retry_timer(qp);
 
 	while (qp->s_last != qp->s_acked) {
-		u32 s_last;
-
 		wqe = rvt_get_swqe_ptr(qp, qp->s_last);
 		if (qib_cmp24(wqe->lpsn, qp->s_sending_psn) >= 0 &&
 		    qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) <= 0)
 			break;
-		s_last = qp->s_last;
-		if (++s_last >= qp->s_size)
-			s_last = 0;
-		qp->s_last = s_last;
-		/* see post_send() */
-		barrier();
-		rvt_put_qp_swqe(qp, wqe);
-		rvt_qp_swqe_complete(qp,
+		rvt_qp_complete_swqe(qp,
 				     wqe,
 				     ib_qib_wc_opcode[wqe->wr.opcode],
 				     IB_WC_SUCCESS);
@@ -972,21 +963,12 @@ static struct rvt_swqe *do_rc_completion(struct rvt_qp *qp,
 	 * is finished.
 	 */
 	if (qib_cmp24(wqe->lpsn, qp->s_sending_psn) < 0 ||
-	    qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) > 0) {
-		u32 s_last;
-
-		rvt_put_qp_swqe(qp, wqe);
-		s_last = qp->s_last;
-		if (++s_last >= qp->s_size)
-			s_last = 0;
-		qp->s_last = s_last;
-		/* see post_send() */
-		barrier();
-		rvt_qp_swqe_complete(qp,
+	    qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) > 0)
+		rvt_qp_complete_swqe(qp,
 				     wqe,
 				     ib_qib_wc_opcode[wqe->wr.opcode],
 				     IB_WC_SUCCESS);
-	} else
+	else
 		this_cpu_inc(*ibp->rvp.rc_delayed_comp);
 
 	qp->s_retry = qp->s_retry_cnt;