[PATCH v3 3/6] trace: support expression for blob length

[David Marchand]

Support any expression as a blob length by using an intermediate
variable in the trace point emitter itself.
This also avoids any side effect on the passed variable.

On the "register" side, prefix the length variable in the trace metadata
with the name of the emitted argument.

With this, we can update ethdev traces and avoid intermediate variables.

Signed-off-by: David Marchand <david.marchand at redhat.com>
---
Changes since v2:
- fixed length field in CTF metadata,

Changes since v1:
- removed code relying on arguments in "registering"
  rte_trace_point_emit_blob implementation (see patch 3),
- moved build check in non registering __rte_trace_point_emit,

---
 lib/eal/common/eal_common_trace_ctf.c      |  1 +
 lib/eal/include/rte_trace_point.h          | 12 ++++++----
 lib/eal/include/rte_trace_point_register.h |  7 ++++--
 lib/ethdev/ethdev_trace.h                  | 27 ++++++----------------
 4 files changed, 20 insertions(+), 27 deletions(-)

diff --git a/lib/eal/common/eal_common_trace_ctf.c b/lib/eal/common/eal_common_trace_ctf.c
index 3e4228ee7f..6bc8bb9036 100644
--- a/lib/eal/common/eal_common_trace_ctf.c
+++ b/lib/eal/common/eal_common_trace_ctf.c
@@ -377,6 +377,7 @@ char *trace_metadata_fixup_field(const char *field)
 		".",
 		"->",
 		"*",
+		" ",
 	};
 	const char *ctf_reserved_words[] = {
 		"align",
diff --git a/lib/eal/include/rte_trace_point.h b/lib/eal/include/rte_trace_point.h
index b24db3b6da..a162502002 100644
--- a/lib/eal/include/rte_trace_point.h
+++ b/lib/eal/include/rte_trace_point.h
@@ -378,6 +378,7 @@ do { \
 
 #define __rte_trace_point_emit(in, type) \
 do { \
+	RTE_BUILD_BUG_ON(sizeof(type) != sizeof(typeof(in))); \
 	memcpy(mem, &(in), sizeof(in)); \
 	mem = RTE_PTR_ADD(mem, sizeof(in)); \
 } while (0)
@@ -392,13 +393,14 @@ do { \
 
 #define rte_trace_point_emit_blob(in, len) \
 do { \
+	uint8_t size = len; \
 	if (unlikely(in == NULL)) \
 		return; \
-	if (len > RTE_TRACE_BLOB_LEN_MAX) \
-		len = RTE_TRACE_BLOB_LEN_MAX; \
-	__rte_trace_point_emit(len, uint8_t); \
-	memcpy(mem, in, len); \
-	memset(RTE_PTR_ADD(mem, len), 0, RTE_TRACE_BLOB_LEN_MAX - len); \
+	if (size > RTE_TRACE_BLOB_LEN_MAX) \
+		size = RTE_TRACE_BLOB_LEN_MAX; \
+	__rte_trace_point_emit(size, uint8_t); \
+	memcpy(mem, in, size); \
+	memset(RTE_PTR_ADD(mem, size), 0, RTE_TRACE_BLOB_LEN_MAX - size); \
 	mem = RTE_PTR_ADD(mem, RTE_TRACE_BLOB_LEN_MAX); \
 } while (0)
 
diff --git a/lib/eal/include/rte_trace_point_register.h b/lib/eal/include/rte_trace_point_register.h
index 748c931830..8d0959c403 100644
--- a/lib/eal/include/rte_trace_point_register.h
+++ b/lib/eal/include/rte_trace_point_register.h
@@ -37,7 +37,7 @@ RTE_INIT(trace##_init) \
 
 #define __rte_trace_point_emit(in, type) \
 do { \
-	RTE_BUILD_BUG_ON(sizeof(type) != sizeof(typeof(in))); \
+	RTE_SET_USED(in); \
 	__rte_trace_point_emit_field(sizeof(type), RTE_STR(in), \
 		RTE_STR(type)); \
 } while (0)
@@ -52,7 +52,10 @@ do { \
 #define rte_trace_point_emit_blob(in, len) \
 do { \
 	RTE_SET_USED(in); \
-	__rte_trace_point_emit(len, uint8_t); \
+	RTE_SET_USED(len); \
+	__rte_trace_point_emit_field(sizeof(uint8_t), \
+		RTE_STR(in) "_" RTE_STR(len), \
+		RTE_STR(uint8_t)); \
 	__rte_trace_point_emit_field(RTE_TRACE_BLOB_LEN_MAX, \
 		RTE_STR(in)"[" RTE_STR(RTE_TRACE_BLOB_LEN_MAX)"]", \
 		RTE_STR(uint8_t)); \
diff --git a/lib/ethdev/ethdev_trace.h b/lib/ethdev/ethdev_trace.h
index 5951ae2d99..c65b78590a 100644
--- a/lib/ethdev/ethdev_trace.h
+++ b/lib/ethdev/ethdev_trace.h
@@ -860,10 +860,8 @@ RTE_TRACE_POINT(
 	rte_ethdev_trace_mac_addr_add,
 	RTE_TRACE_POINT_ARGS(uint16_t port_id,
 		const struct rte_ether_addr *addr, uint32_t pool, int ret),
-	uint8_t len = RTE_ETHER_ADDR_LEN;
-
 	rte_trace_point_emit_u16(port_id);
-	rte_trace_point_emit_blob(addr->addr_bytes, len);
+	rte_trace_point_emit_blob(addr->addr_bytes, RTE_ETHER_ADDR_LEN);
 	rte_trace_point_emit_u32(pool);
 	rte_trace_point_emit_int(ret);
 )
@@ -872,20 +870,16 @@ RTE_TRACE_POINT(
 	rte_ethdev_trace_mac_addr_remove,
 	RTE_TRACE_POINT_ARGS(uint16_t port_id,
 		const struct rte_ether_addr *addr),
-	uint8_t len = RTE_ETHER_ADDR_LEN;
-
 	rte_trace_point_emit_u16(port_id);
-	rte_trace_point_emit_blob(addr->addr_bytes, len);
+	rte_trace_point_emit_blob(addr->addr_bytes, RTE_ETHER_ADDR_LEN);
 )
 
 RTE_TRACE_POINT(
 	rte_ethdev_trace_default_mac_addr_set,
 	RTE_TRACE_POINT_ARGS(uint16_t port_id,
 		const struct rte_ether_addr *addr),
-	uint8_t len = RTE_ETHER_ADDR_LEN;
-
 	rte_trace_point_emit_u16(port_id);
-	rte_trace_point_emit_blob(addr->addr_bytes, len);
+	rte_trace_point_emit_blob(addr->addr_bytes, RTE_ETHER_ADDR_LEN);
 )
 
 RTE_TRACE_POINT(
@@ -1102,11 +1096,9 @@ RTE_TRACE_POINT(
 	RTE_TRACE_POINT_ARGS(uint16_t port_id,
 		const struct rte_ether_addr *mc_addr_set, uint32_t nb_mc_addr,
 		int ret),
-	uint8_t len = nb_mc_addr * RTE_ETHER_ADDR_LEN;
-
 	rte_trace_point_emit_u16(port_id);
 	rte_trace_point_emit_u32(nb_mc_addr);
-	rte_trace_point_emit_blob(mc_addr_set, len);
+	rte_trace_point_emit_blob(mc_addr_set, nb_mc_addr * RTE_ETHER_ADDR_LEN);
 	rte_trace_point_emit_int(ret);
 )
 
@@ -1214,13 +1206,10 @@ RTE_TRACE_POINT(
 	rte_ethdev_trace_get_dcb_info,
 	RTE_TRACE_POINT_ARGS(uint16_t port_id,
 		const struct rte_eth_dcb_info *dcb_info, int ret),
-	uint8_t num_user_priorities = RTE_ETH_DCB_NUM_USER_PRIORITIES;
-	uint8_t num_tcs = RTE_ETH_DCB_NUM_TCS;
-
 	rte_trace_point_emit_u16(port_id);
 	rte_trace_point_emit_u8(dcb_info->nb_tcs);
-	rte_trace_point_emit_blob(dcb_info->prio_tc, num_user_priorities);
-	rte_trace_point_emit_blob(dcb_info->tc_bws, num_tcs);
+	rte_trace_point_emit_blob(dcb_info->prio_tc, RTE_ETH_DCB_NUM_USER_PRIORITIES);
+	rte_trace_point_emit_blob(dcb_info->tc_bws, RTE_ETH_DCB_NUM_TCS);
 	rte_trace_point_emit_int(ret);
 )
 
@@ -2126,10 +2115,8 @@ RTE_TRACE_POINT_FP(
 	rte_eth_trace_macaddr_get,
 	RTE_TRACE_POINT_ARGS(uint16_t port_id,
 		const struct rte_ether_addr *mac_addr),
-	uint8_t len = RTE_ETHER_ADDR_LEN;
-
 	rte_trace_point_emit_u16(port_id);
-	rte_trace_point_emit_blob(mac_addr->addr_bytes, len);
+	rte_trace_point_emit_blob(mac_addr->addr_bytes, RTE_ETHER_ADDR_LEN);
 )
 
 /* Called in loop in examples/ip_pipeline */
-- 
2.48.1