svcrdma: Split the svcrdma_wc_receive() tracepoint

There are currently three separate purposes being served by a single
tracepoint here. They need to be split up.

svcrdma_wc_recv:
 - status is always zero, so there's no value in recording it.
 - vendor_err is meaningless unless status is not zero, so
   there's no value in recording it.
 - This tracepoint is needed only when developing modifications,
   so it should be left disabled most of the time.

svcrdma_wc_recv_flush:
 - As above, needed only rarely, and not an error.

svcrdma_wc_recv_err:
 - received is always zero, so there's no value in recording it.
 - This tracepoint can be left enabled because completion
   errors are run-time problems (except for FLUSHED_ERR).
 - Tracepoint name now ends in _err to reflect its purpose.

Signed-off-by: Chuck Lever <[email protected]>
Signed-off-by: J. Bruce Fields <[email protected]>

Author: chucklever

include/trace/events/rpcrdma.h

@@ -145,6 +145,77 @@ DECLARE_EVENT_CLASS(rpcrdma_receive_completion_class,
 				),					\
 				TP_ARGS(wc, cid))
 
+DECLARE_EVENT_CLASS(rpcrdma_receive_success_class,
+	TP_PROTO(
+		const struct ib_wc *wc,
+		const struct rpc_rdma_cid *cid
+	),
+
+	TP_ARGS(wc, cid),
+
+	TP_STRUCT__entry(
+		__field(u32, cq_id)
+		__field(int, completion_id)
+		__field(u32, received)
+	),
+
+	TP_fast_assign(
+		__entry->cq_id = cid->ci_queue_id;
+		__entry->completion_id = cid->ci_completion_id;
+		__entry->received = wc->byte_len;
+	),
+
+	TP_printk("cq.id=%u cid=%d received=%u",
+		__entry->cq_id, __entry->completion_id,
+		__entry->received
+	)
+);
+
+#define DEFINE_RECEIVE_SUCCESS_EVENT(name)				\
+		DEFINE_EVENT(rpcrdma_receive_success_class, name,	\
+				TP_PROTO(				\
+					const struct ib_wc *wc,		\
+					const struct rpc_rdma_cid *cid	\
+				),					\
+				TP_ARGS(wc, cid))
+
+DECLARE_EVENT_CLASS(rpcrdma_receive_flush_class,
+	TP_PROTO(
+		const struct ib_wc *wc,
+		const struct rpc_rdma_cid *cid
+	),
+
+	TP_ARGS(wc, cid),
+
+	TP_STRUCT__entry(
+		__field(u32, cq_id)
+		__field(int, completion_id)
+		__field(unsigned long, status)
+		__field(unsigned int, vendor_err)
+	),
+
+	TP_fast_assign(
+		__entry->cq_id = cid->ci_queue_id;
+		__entry->completion_id = cid->ci_completion_id;
+		__entry->status = wc->status;
+		__entry->vendor_err = wc->vendor_err;
+	),
+
+	TP_printk("cq.id=%u cid=%d status=%s (%lu/0x%x)",
+		__entry->cq_id, __entry->completion_id,
+		rdma_show_wc_status(__entry->status),
+		__entry->status, __entry->vendor_err
+	)
+);
+
+#define DEFINE_RECEIVE_FLUSH_EVENT(name)				\
+		DEFINE_EVENT(rpcrdma_receive_flush_class, name,		\
+				TP_PROTO(				\
+					const struct ib_wc *wc,		\
+					const struct rpc_rdma_cid *cid	\
+				),					\
+				TP_ARGS(wc, cid))
+
 DECLARE_EVENT_CLASS(xprtrdma_reply_class,
 	TP_PROTO(
 		const struct rpcrdma_rep *rep
@@ -1892,7 +1963,9 @@ TRACE_EVENT(svcrdma_post_recv,
 	)
 );
 
-DEFINE_RECEIVE_COMPLETION_EVENT(svcrdma_wc_receive);
+DEFINE_RECEIVE_SUCCESS_EVENT(svcrdma_wc_recv);
+DEFINE_RECEIVE_FLUSH_EVENT(svcrdma_wc_recv_flush);
+DEFINE_RECEIVE_FLUSH_EVENT(svcrdma_wc_recv_err);
 
 TRACE_EVENT(svcrdma_rq_post_err,
 	TP_PROTO(

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

@@ -330,9 +330,9 @@ static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
 	/* WARNING: Only wc->wr_cqe and wc->status are reliable */
 	ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe);
 
-	trace_svcrdma_wc_receive(wc, &ctxt->rc_cid);
 	if (wc->status != IB_WC_SUCCESS)
 		goto flushed;
+	trace_svcrdma_wc_recv(wc, &ctxt->rc_cid);
 
 	/* If receive posting fails, the connection is about to be
 	 * lost anyway. The server will not be able to send a reply
@@ -345,7 +345,7 @@ static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
 	 */
 	if (rdma->sc_pending_recvs < rdma->sc_max_requests)
 		if (!svc_rdma_refresh_recvs(rdma, rdma->sc_recv_batch, false))
-			goto flushed;
+			goto dropped;
 
 	/* All wc fields are now known to be valid */
 	ctxt->rc_byte_len = wc->byte_len;
@@ -360,6 +360,11 @@ static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
 	return;
 
 flushed:
+	if (wc->status == IB_WC_WR_FLUSH_ERR)
+		trace_svcrdma_wc_recv_flush(wc, &ctxt->rc_cid);
+	else
+		trace_svcrdma_wc_recv_err(wc, &ctxt->rc_cid);
+dropped:
 	svc_rdma_recv_ctxt_put(rdma, ctxt);
 	svc_xprt_deferred_close(&rdma->sc_xprt);
 }