SUNRPC: Update debugging instrumentation in xprt_do_reserve()

Replace a dprintk() with a tracepoint. The tracepoint marks the
point where an RPC request is assigned an XID.

Additional clean up: Remove trace_xprt_enq_xmit, which reports much
the same thing. That tracepoint was added for debugging commit
918f3c1f ("SUNRPC: Improve latency for interactive tasks").
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/trace/events/sunrpc.h

@@ -1031,37 +1031,6 @@ TRACE_EVENT(xprt_transmit,
 		__entry->seqno, __entry->status)
 );
 
-TRACE_EVENT(xprt_enq_xmit,
-	TP_PROTO(
-		const struct rpc_task *task,
-		int stage
-	),
-
-	TP_ARGS(task, stage),
-
-	TP_STRUCT__entry(
-		__field(unsigned int, task_id)
-		__field(unsigned int, client_id)
-		__field(u32, xid)
-		__field(u32, seqno)
-		__field(int, stage)
-	),
-
-	TP_fast_assign(
-		__entry->task_id = task->tk_pid;
-		__entry->client_id = task->tk_client ?
-			task->tk_client->cl_clid : -1;
-		__entry->xid = be32_to_cpu(task->tk_rqstp->rq_xid);
-		__entry->seqno = task->tk_rqstp->rq_seqno;
-		__entry->stage = stage;
-	),
-
-	TP_printk(
-		"task:%u@%u xid=0x%08x seqno=%u stage=%d",
-		__entry->task_id, __entry->client_id, __entry->xid,
-		__entry->seqno, __entry->stage)
-);
-
 TRACE_EVENT(xprt_ping,
 	TP_PROTO(const struct rpc_xprt *xprt, int status),
 
@@ -1176,6 +1145,30 @@ DEFINE_CONG_EVENT(release_cong);
 DEFINE_CONG_EVENT(get_cong);
 DEFINE_CONG_EVENT(put_cong);
 
+TRACE_EVENT(xprt_reserve,
+	TP_PROTO(
+		const struct rpc_rqst *rqst
+	),
+
+	TP_ARGS(rqst),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, task_id)
+		__field(unsigned int, client_id)
+		__field(u32, xid)
+	),
+
+	TP_fast_assign(
+		__entry->task_id = rqst->rq_task->tk_pid;
+		__entry->client_id = rqst->rq_task->tk_client->cl_clid;
+		__entry->xid = be32_to_cpu(rqst->rq_xid);
+	),
+
+	TP_printk("task:%u@%u xid=0x%08x",
+		__entry->task_id, __entry->client_id, __entry->xid
+	)
+);
+
 TRACE_EVENT(xs_stream_read_data,
 	TP_PROTO(struct rpc_xprt *xprt, ssize_t err, size_t total),
 

net/sunrpc/xprt.c

@@ -1267,7 +1267,6 @@ xprt_request_enqueue_transmit(struct rpc_task *task)
 				/* Note: req is added _before_ pos */
 				list_add_tail(&req->rq_xmit, &pos->rq_xmit);
 				INIT_LIST_HEAD(&req->rq_xmit2);
-				trace_xprt_enq_xmit(task, 1);
 				goto out;
 			}
 		} else if (RPC_IS_SWAPPER(task)) {
@@ -1279,7 +1278,6 @@ xprt_request_enqueue_transmit(struct rpc_task *task)
 				/* Note: req is added _before_ pos */
 				list_add_tail(&req->rq_xmit, &pos->rq_xmit);
 				INIT_LIST_HEAD(&req->rq_xmit2);
-				trace_xprt_enq_xmit(task, 2);
 				goto out;
 			}
 		} else if (!req->rq_seqno) {
@@ -1288,13 +1286,11 @@ xprt_request_enqueue_transmit(struct rpc_task *task)
 					continue;
 				list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
 				INIT_LIST_HEAD(&req->rq_xmit);
-				trace_xprt_enq_xmit(task, 3);
 				goto out;
 			}
 		}
 		list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
 		INIT_LIST_HEAD(&req->rq_xmit2);
-		trace_xprt_enq_xmit(task, 4);
 out:
 		set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
 		spin_unlock(&xprt->queue_lock);
@@ -1745,8 +1741,8 @@ xprt_request_init(struct rpc_task *task)
 	req->rq_rcv_buf.bvec = NULL;
 	req->rq_release_snd_buf = NULL;
 	xprt_init_majortimeo(task, req);
-	dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
-			req, ntohl(req->rq_xid));
+
+	trace_xprt_reserve(req);
 }
 
 static void