provides: add support for USDT tracing using libbpf/usdt

Default to providing lightweight USDT trace points when LTTng
is unavailable.  This piggybacks on the existing tracing code
added for LTTng for a minimal set of changes.

> $ sudo bpftrace -l usdt:build/lib/lib*.so:*
> usdt:build/lib/libefa-rdmav59.so:rdma_core_efa:post_recv
> usdt:build/lib/libefa-rdmav59.so:rdma_core_efa:post_send
> usdt:build/lib/libefa-rdmav59.so:rdma_core_efa:process_completion
> usdt:build/lib/libefa.so:rdma_core_efa:post_recv
> usdt:build/lib/libefa.so:rdma_core_efa:post_send
> usdt:build/lib/libefa.so:rdma_core_efa:process_completion
> usdt:build/lib/libhns-rdmav59.so:rdma_core_hns:poll_cq
> usdt:build/lib/libhns-rdmav59.so:rdma_core_hns:post_recv
> usdt:build/lib/libhns-rdmav59.so:rdma_core_hns:post_send
> usdt:build/lib/libhns.so:rdma_core_hns:poll_cq
> usdt:build/lib/libhns.so:rdma_core_hns:post_recv
> usdt:build/lib/libhns.so:rdma_core_hns:post_send
> usdt:build/lib/libmlx5-rdmav59.so:rdma_core_mlx5:post_send
> usdt:build/lib/libmlx5.so:rdma_core_mlx5:post_send
> usdt:build/lib/librxe-rdmav59.so:rdma_core_rxe:post_send

The USDT header used here is from the libbpf/usdt project at
https://github.com/libbpf/usdt.git

Further background discussion for this commit is included in
linux-rdma#1621

Signed-off-by: Nathan Scott <[email protected]>

Author: natoscott

providers/efa/efa_trace.h

@@ -114,7 +114,9 @@ LTTNG_UST_TRACEPOINT_EVENT(
 #ifndef __EFA_TRACE_H__
 #define __EFA_TRACE_H__
 
-#define rdma_tracepoint(arg...)
+#include <util/usdt.h>
+
+#define rdma_tracepoint(arg...) USDT(arg)
 
 #endif /* __EFA_TRACE_H__*/
 

providers/efa/verbs.c

@@ -2170,7 +2170,6 @@ static void efa_set_common_ctrl_flags(struct efa_io_tx_meta_desc *desc,
 	EFA_SET(&desc->ctrl2, EFA_IO_TX_META_DESC_COMP_REQ, 1);
 }
 
-#ifdef LTTNG_ENABLED
 static uint32_t efa_get_wqe_length(struct efa_io_tx_wqe *tx_wqe)
 {
 	enum efa_io_send_op_type op_type;
@@ -2194,7 +2193,6 @@ static uint32_t efa_get_wqe_length(struct efa_io_tx_wqe *tx_wqe)
 
 	return 0;
 }
-#endif
 
 static int efa_post_send_validate(struct efa_qp *qp,
 				  unsigned int wr_flags)

providers/hns/hns_roce_u_hw_v2.c

@@ -678,7 +678,6 @@ static int parse_cqe_for_cq(struct hns_roce_context *ctx, struct hns_roce_cq *cq
 	return 0;
 }
 
-#ifdef LTTNG_ENABLED
 static uint8_t read_wc_sl(struct hns_roce_qp *hr_qp,
 				   struct hns_roce_v2_cqe *cqe,
 				   struct ibv_wc *wc)
@@ -750,7 +749,6 @@ static uint8_t get_send_wr_tclass(struct ibv_send_wr *wr,
 	return qp_type == IBV_QPT_UD ?
 		to_hr_ah(wr->wr.ud.ah)->av.tclass : UINT8_MAX;
 }
-#endif
 
 static int hns_roce_poll_one(struct hns_roce_context *ctx,
 			     struct hns_roce_qp **cur_qp, struct hns_roce_cq *cq,

providers/hns/hns_roce_u_trace.h

@@ -126,7 +126,9 @@ LTTNG_UST_TRACEPOINT_EVENT(
 #ifndef __HNS_TRACE_H__
 #define __HNS_TRACE_H__
 
-#define rdma_tracepoint(arg...)
+#include <util/usdt.h>
+
+#define rdma_tracepoint(arg...) USDT(arg)
 
 #endif /* __HNS_TRACE_H__*/
 

providers/mlx5/mlx5_trace.h

@@ -52,7 +52,9 @@ LTTNG_UST_TRACEPOINT_EVENT(
 #ifndef __MLX5_TRACE_H__
 #define __MLX5_TRACE_H__
 
-#define rdma_tracepoint(arg...)
+#include <util/usdt.h>
+
+#define rdma_tracepoint(arg...) USDT(arg)
 
 #endif /* __MLX5_TRACE_H__*/
 

providers/rxe/rxe_trace.h

@@ -52,7 +52,9 @@ LTTNG_UST_TRACEPOINT_EVENT(
 #ifndef __RXE_TRACE_H__
 #define __RXE_TRACE_H__
 
-#define rdma_tracepoint(arg...)
+#include <util/usdt.h>
+
+#define rdma_tracepoint(arg...) USDT(arg)
 
 #endif /* __RXE_TRACE_H__*/
 

util/CMakeLists.txt

@@ -6,6 +6,7 @@ publish_internal_headers(util
   node_name_map.h
   rdma_nl.h
   symver.h
+  usdt.h
   util.h
   )