svcrdma: Clean up handling of get_rw_ctx errors

Clean up: Replace two dprintk call sites with a tracepoint.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/trace/events/rpcrdma.h

@@ -1612,6 +1612,31 @@ TRACE_EVENT(svcrdma_dma_map_rw_err,
 	)
 );
 
+TRACE_EVENT(svcrdma_no_rwctx_err,
+	TP_PROTO(
+		const struct svcxprt_rdma *rdma,
+		unsigned int num_sges
+	),
+
+	TP_ARGS(rdma, num_sges),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, num_sges)
+		__string(device, rdma->sc_cm_id->device->name)
+		__string(addr, rdma->sc_xprt.xpt_remotebuf)
+	),
+
+	TP_fast_assign(
+		__entry->num_sges = num_sges;
+		__assign_str(device, rdma->sc_cm_id->device->name);
+		__assign_str(addr, rdma->sc_xprt.xpt_remotebuf);
+	),
+
+	TP_printk("addr=%s device=%s num_sges=%d",
+		__get_str(addr), __get_str(device), __entry->num_sges
+	)
+);
+
 TRACE_EVENT(svcrdma_send_pullup,
 	TP_PROTO(
 		unsigned int len

net/sunrpc/xprtrdma/svc_rdma_rw.c

@@ -67,19 +67,22 @@ svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
 		ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
 			       GFP_KERNEL);
 		if (!ctxt)
-			goto out;
+			goto out_noctx;
 		INIT_LIST_HEAD(&ctxt->rw_list);
 	}
 
 	ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl;
 	if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges,
 				   ctxt->rw_sg_table.sgl,
-				   SG_CHUNK_SIZE)) {
-		kfree(ctxt);
-		ctxt = NULL;
-	}
-out:
+				   SG_CHUNK_SIZE))
+		goto out_free;
 	return ctxt;
+
+out_free:
+	kfree(ctxt);
+out_noctx:
+	trace_svcrdma_no_rwctx_err(rdma, sges);
+	return NULL;
 }
 
 static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
@@ -456,7 +459,7 @@ svc_rdma_build_writes(struct svc_rdma_write_info *info,
 		ctxt = svc_rdma_get_rw_ctxt(rdma,
 					    (write_len >> PAGE_SHIFT) + 2);
 		if (!ctxt)
-			goto out_noctx;
+			return -ENOMEM;
 
 		constructor(info, write_len, ctxt);
 		ret = svc_rdma_rw_ctx_init(rdma, ctxt, seg_offset, seg_handle,
@@ -484,10 +487,6 @@ svc_rdma_build_writes(struct svc_rdma_write_info *info,
 	dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
 		info->wi_nsegs);
 	return -E2BIG;
-
-out_noctx:
-	dprintk("svcrdma: no R/W ctxs available\n");
-	return -ENOMEM;
 }
 
 /* Send one of an xdr_buf's kvecs by itself. To send a Reply
@@ -637,7 +636,7 @@ static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
 	sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT;
 	ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no);
 	if (!ctxt)
-		goto out_noctx;
+		return -ENOMEM;
 	ctxt->rw_nents = sge_no;
 
 	sg = ctxt->rw_sg_table.sgl;
@@ -676,10 +675,6 @@ static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
 	cc->cc_sqecount += ret;
 	return 0;
 
-out_noctx:
-	dprintk("svcrdma: no R/W ctxs available\n");
-	return -ENOMEM;
-
 out_overrun:
 	dprintk("svcrdma: request overruns rq_pages\n");
 	return -EINVAL;