xprtrdma: Clean up Receive trace points

For clarity, report the posting and completion of Receive CQEs.

Also, the wc->byte_len field contains garbage if wc->status is
non-zero, and the vendor error field contains garbage if wc->status
is zero. For readability, don't save those fields in those cases.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/trace/events/rpcrdma.h

@@ -528,24 +528,21 @@ TRACE_EVENT(xprtrdma_post_send,
 
 TRACE_EVENT(xprtrdma_post_recv,
 	TP_PROTO(
-		const struct rpcrdma_rep *rep,
-		int status
+		const struct ib_cqe *cqe
 	),
 
-	TP_ARGS(rep, status),
+	TP_ARGS(cqe),
 
 	TP_STRUCT__entry(
-		__field(const void *, rep)
-		__field(int, status)
+		__field(const void *, cqe)
 	),
 
 	TP_fast_assign(
-		__entry->rep = rep;
-		__entry->status = status;
+		__entry->cqe = cqe;
 	),
 
-	TP_printk("rep=%p status=%d",
-		__entry->rep, __entry->status
+	TP_printk("cqe=%p",
+		__entry->cqe
 	)
 );
 
@@ -584,28 +581,32 @@ TRACE_EVENT(xprtrdma_wc_send,
 
 TRACE_EVENT(xprtrdma_wc_receive,
 	TP_PROTO(
-		const struct rpcrdma_rep *rep,
 		const struct ib_wc *wc
 	),
 
-	TP_ARGS(rep, wc),
+	TP_ARGS(wc),
 
 	TP_STRUCT__entry(
-		__field(const void *, rep)
-		__field(unsigned int, byte_len)
+		__field(const void *, cqe)
+		__field(u32, byte_len)
 		__field(unsigned int, status)
-		__field(unsigned int, vendor_err)
+		__field(u32, vendor_err)
 	),
 
 	TP_fast_assign(
-		__entry->rep = rep;
-		__entry->byte_len = wc->byte_len;
+		__entry->cqe = wc->wr_cqe;
 		__entry->status = wc->status;
-		__entry->vendor_err = __entry->status ? wc->vendor_err : 0;
+		if (wc->status) {
+			__entry->byte_len = 0;
+			__entry->vendor_err = wc->vendor_err;
+		} else {
+			__entry->byte_len = wc->byte_len;
+			__entry->vendor_err = 0;
+		}
 	),
 
-	TP_printk("rep=%p, %u bytes: %s (%u/0x%x)",
-		__entry->rep, __entry->byte_len,
+	TP_printk("cqe=%p %u bytes: %s (%u/0x%x)",
+		__entry->cqe, __entry->byte_len,
 		rdma_show_wc_status(__entry->status),
 		__entry->status, __entry->vendor_err
 	)

net/sunrpc/xprtrdma/verbs.c

@@ -160,7 +160,7 @@ rpcrdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
 					       rr_cqe);
 
 	/* WARNING: Only wr_id and status are reliable at this point */
-	trace_xprtrdma_wc_receive(rep, wc);
+	trace_xprtrdma_wc_receive(wc);
 	if (wc->status != IB_WC_SUCCESS)
 		goto out_fail;
 
@@ -1570,7 +1570,7 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
 	if (!rpcrdma_dma_map_regbuf(ia, rep->rr_rdmabuf))
 		goto out_map;
 	rc = ib_post_recv(ia->ri_id->qp, &rep->rr_recv_wr, &recv_wr_fail);
-	trace_xprtrdma_post_recv(rep, rc);
+	trace_xprtrdma_post_recv(rep->rr_recv_wr.wr_cqe);
 	if (rc)
 		return -ENOTCONN;
 	return 0;