[PATCH v1 7/7] svcrdma: Add tracepoints to report ->xpo_accept failures

[Chuck Lever <chuck.lever@xxxxxxxxxx>]

Failure to accept a connection is typically due to a problem
specific to a transport type. Also, ->xpo_accept returns NULL
on error rather than reporting a specific problem.

So, add failure-specific tracepoints in svc_rdma_accept().

Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 include/trace/events/rpcrdma.h           |   37 ++++++++++++++++++++++++++++++
 net/sunrpc/xprtrdma/svc_rdma_transport.c |   25 +++++++++-----------
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/include/trace/events/rpcrdma.h b/include/trace/events/rpcrdma.h
index 6de7a9202a68..c25e11564598 100644
--- a/include/trace/events/rpcrdma.h
+++ b/include/trace/events/rpcrdma.h
@@ -1283,6 +1283,43 @@ TRACE_EVENT(xprtrdma_leaked_rep,
  ** Server-side RPC/RDMA events
  **/
 
+DECLARE_EVENT_CLASS(svcrdma_accept_class,
+	TP_PROTO(
+		const struct svcxprt_rdma *rdma,
+		long status
+	),
+
+	TP_ARGS(rdma, status),
+
+	TP_STRUCT__entry(
+		__field(long, status)
+		__string(addr, rdma->sc_xprt.xpt_remotebuf)
+	),
+
+	TP_fast_assign(
+		__entry->status = status;
+		__assign_str(addr, rdma->sc_xprt.xpt_remotebuf);
+	),
+
+	TP_printk("addr=%s status=%ld",
+		__get_str(addr), __entry->status
+	)
+);
+
+#define DEFINE_ACCEPT_EVENT(name)					\
+		DEFINE_EVENT(svcrdma_accept_class, svcrdma_##name##_err,	\
+				TP_PROTO(				\
+					const struct svcxprt_rdma *rdma,	\
+					long status			\
+				),					\
+				TP_ARGS(rdma, status))
+
+DEFINE_ACCEPT_EVENT(pd);
+DEFINE_ACCEPT_EVENT(qp);
+DEFINE_ACCEPT_EVENT(fabric);
+DEFINE_ACCEPT_EVENT(initdepth);
+DEFINE_ACCEPT_EVENT(accept);
+
 TRACE_DEFINE_ENUM(RDMA_MSG);
 TRACE_DEFINE_ENUM(RDMA_NOMSG);
 TRACE_DEFINE_ENUM(RDMA_MSGP);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index aa68dc706006..d38be57b00ed 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -400,9 +400,6 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	if (!newxprt)
 		return NULL;
 
-	dprintk("svcrdma: newxprt from accept queue = %p, cm_id=%p\n",
-		newxprt, newxprt->sc_cm_id);
-
 	dev = newxprt->sc_cm_id->device;
 	newxprt->sc_port_num = newxprt->sc_cm_id->port_num;
 
@@ -438,21 +435,17 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 
 	newxprt->sc_pd = ib_alloc_pd(dev, 0);
 	if (IS_ERR(newxprt->sc_pd)) {
-		dprintk("svcrdma: error creating PD for connect request\n");
+		trace_svcrdma_pd_err(newxprt, PTR_ERR(newxprt->sc_pd));
 		goto errout;
 	}
 	newxprt->sc_sq_cq = ib_alloc_cq_any(dev, newxprt, newxprt->sc_sq_depth,
 					    IB_POLL_WORKQUEUE);
-	if (IS_ERR(newxprt->sc_sq_cq)) {
-		dprintk("svcrdma: error creating SQ CQ for connect request\n");
+	if (IS_ERR(newxprt->sc_sq_cq))
 		goto errout;
-	}
 	newxprt->sc_rq_cq =
 		ib_alloc_cq_any(dev, newxprt, rq_depth, IB_POLL_WORKQUEUE);
-	if (IS_ERR(newxprt->sc_rq_cq)) {
-		dprintk("svcrdma: error creating RQ CQ for connect request\n");
+	if (IS_ERR(newxprt->sc_rq_cq))
 		goto errout;
-	}
 
 	memset(&qp_attr, 0, sizeof qp_attr);
 	qp_attr.event_handler = qp_event_handler;
@@ -476,7 +469,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 
 	ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd, &qp_attr);
 	if (ret) {
-		dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
+		trace_svcrdma_qp_err(newxprt, ret);
 		goto errout;
 	}
 	newxprt->sc_qp = newxprt->sc_cm_id->qp;
@@ -484,8 +477,10 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	if (!(dev->attrs.device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS))
 		newxprt->sc_snd_w_inv = false;
 	if (!rdma_protocol_iwarp(dev, newxprt->sc_port_num) &&
-	    !rdma_ib_or_roce(dev, newxprt->sc_port_num))
+	    !rdma_ib_or_roce(dev, newxprt->sc_port_num)) {
+		trace_svcrdma_fabric_err(newxprt, -EINVAL);
 		goto errout;
+	}
 
 	if (!svc_rdma_post_recvs(newxprt))
 		goto errout;
@@ -507,15 +502,17 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	conn_param.initiator_depth = min_t(int, newxprt->sc_ord,
 					   dev->attrs.max_qp_init_rd_atom);
 	if (!conn_param.initiator_depth) {
-		dprintk("svcrdma: invalid ORD setting\n");
 		ret = -EINVAL;
+		trace_svcrdma_initdepth_err(newxprt, ret);
 		goto errout;
 	}
 	conn_param.private_data = &pmsg;
 	conn_param.private_data_len = sizeof(pmsg);
 	ret = rdma_accept(newxprt->sc_cm_id, &conn_param);
-	if (ret)
+	if (ret) {
+		trace_svcrdma_accept_err(newxprt, ret);
 		goto errout;
+	}
 
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 	dprintk("svcrdma: new connection %p accepted:\n", newxprt);