xprtrdma: Add xprtrdma_post_recvs_err() tracepoint

In the vast majority of cases, rc=0. Don't record that in the
post_recvs tracepoint. Instead, add a separate tracepoint that can
be left enabled all the time to capture the very rare immediate
errors returned by ib_post_recv().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/trace/events/rpcrdma.h

@@ -818,16 +818,14 @@ TRACE_EVENT(xprtrdma_post_recv,
 TRACE_EVENT(xprtrdma_post_recvs,
 	TP_PROTO(
 		const struct rpcrdma_xprt *r_xprt,
-		unsigned int count,
-		int status
+		unsigned int count
 	),
 
-	TP_ARGS(r_xprt, count, status),
+	TP_ARGS(r_xprt, count),
 
 	TP_STRUCT__entry(
 		__field(u32, cq_id)
 		__field(unsigned int, count)
-		__field(int, status)
 		__field(int, posted)
 		__string(addr, rpcrdma_addrstr(r_xprt))
 		__string(port, rpcrdma_portstr(r_xprt))
@@ -838,15 +836,44 @@ TRACE_EVENT(xprtrdma_post_recvs,
 
 		__entry->cq_id = ep->re_attr.recv_cq->res.id;
 		__entry->count = count;
-		__entry->status = status;
 		__entry->posted = ep->re_receive_count;
 		__assign_str(addr, rpcrdma_addrstr(r_xprt));
 		__assign_str(port, rpcrdma_portstr(r_xprt));
 	),
 
-	TP_printk("peer=[%s]:%s cq.id=%d %u new recvs, %d active (rc %d)",
+	TP_printk("peer=[%s]:%s cq.id=%d %u new recvs, %d active",
+		__get_str(addr), __get_str(port), __entry->cq_id,
+		__entry->count, __entry->posted
+	)
+);
+
+TRACE_EVENT(xprtrdma_post_recvs_err,
+	TP_PROTO(
+		const struct rpcrdma_xprt *r_xprt,
+		int status
+	),
+
+	TP_ARGS(r_xprt, status),
+
+	TP_STRUCT__entry(
+		__field(u32, cq_id)
+		__field(int, status)
+		__string(addr, rpcrdma_addrstr(r_xprt))
+		__string(port, rpcrdma_portstr(r_xprt))
+	),
+
+	TP_fast_assign(
+		const struct rpcrdma_ep *ep = r_xprt->rx_ep;
+
+		__entry->cq_id = ep->re_attr.recv_cq->res.id;
+		__entry->status = status;
+		__assign_str(addr, rpcrdma_addrstr(r_xprt));
+		__assign_str(port, rpcrdma_portstr(r_xprt));
+	),
+
+	TP_printk("peer=[%s]:%s cq.id=%d rc=%d",
 		__get_str(addr), __get_str(port), __entry->cq_id,
-		__entry->count, __entry->posted, __entry->status
+		__entry->status
 	)
 );
 

net/sunrpc/xprtrdma/verbs.c

@@ -1417,6 +1417,7 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp)
 	rc = ib_post_recv(ep->re_id->qp, wr,
 			  (const struct ib_recv_wr **)&bad_wr);
 	if (rc) {
+		trace_xprtrdma_post_recvs_err(r_xprt, rc);
 		for (wr = bad_wr; wr;) {
 			struct rpcrdma_rep *rep;
 
@@ -1430,7 +1431,7 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp)
 		complete(&ep->re_done);
 
 out:
-	trace_xprtrdma_post_recvs(r_xprt, count, rc);
+	trace_xprtrdma_post_recvs(r_xprt, count);
 	ep->re_receive_count += count;
 	return;
 }