[PATCH v3 09/11] libtracefs: Use the internal dynamic events API when creating synthetic events

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

Synthetic events are type of ftrace dynamic events. The tracefs library
has dedicated APIs to manage dynamic events of all types. In order the
code to be consistent, the creation of synthetic events inside the
library is reimplemented with these new dynamic events APIs.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 src/tracefs-hist.c | 103 +++++++++++++++++++++------------------------
 1 file changed, 47 insertions(+), 56 deletions(-)

diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index 9009dba..08bb2da 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -661,6 +661,7 @@ struct tracefs_synth {
 	struct tep_event	*end_event;
 	struct action		*actions;
 	struct action		**next_action;
+	struct tracefs_dynevent	*dyn_event;
 	char			*name;
 	char			**synthetic_fields;
 	char			**synthetic_args;
@@ -719,6 +720,7 @@ void tracefs_synth_free(struct tracefs_synth *synth)
 		synth->actions = action->next;
 		action_free(action);
 	}
+	tracefs_dynevent_free(synth->dyn_event);
 
 	free(synth);
 }
@@ -889,6 +891,28 @@ synth_init_from(struct tep_handle *tep, const char *start_system,
 	return synth;
 }
 
+static int alloc_synthetic_event(struct tracefs_synth *synth)
+{
+	char *synthetic_format;
+	const char *field;
+	int i;
+
+	synthetic_format = strdup("");
+	if (!synthetic_format)
+		return -1;
+
+	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
+		field = synth->synthetic_fields[i];
+		synthetic_format = append_string(synthetic_format, " ", field);
+	}
+
+	synth->dyn_event = dynevent_alloc(TRACEFS_DYNEVENT_SYNTH, NULL,
+					  synth->name, NULL, synthetic_format);
+	free(synthetic_format);
+
+	return synth->dyn_event ? 0 : -1;
+}
+
 /**
  * tracefs_synth_alloc - create a new tracefs_synth instance
  * @tep: The tep handle that holds the events to work on
@@ -1609,38 +1633,6 @@ int tracefs_synth_save(struct tracefs_synth *synth,
 	return 0;
 }
 
-static char *create_synthetic_event(struct tracefs_synth *synth)
-{
-	char *synthetic_event;
-	const char *field;
-	int i;
-
-	synthetic_event = strdup(synth->name);
-	if (!synthetic_event)
-		return NULL;
-
-	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
-		field = synth->synthetic_fields[i];
-		synthetic_event = append_string(synthetic_event, " ", field);
-	}
-
-	return synthetic_event;
-}
-
-static int remove_synthetic(const char *synthetic)
-{
-	char *str;
-	int ret;
-
-	ret = asprintf(&str, "!%s", synthetic);
-	if (ret < 0)
-		return -1;
-
-	ret = tracefs_instance_file_append(NULL, "synthetic_events", str);
-	free(str);
-	return ret < 0 ? -1 : 0;
-}
-
 static int remove_hist(struct tracefs_instance *instance,
 		       struct tep_event *event, const char *hist)
 {
@@ -1919,7 +1911,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
 int tracefs_synth_create(struct tracefs_instance *instance,
 			 struct tracefs_synth *synth)
 {
-	char *synthetic_event;
 	char *start_hist = NULL;
 	char *end_hist = NULL;
 	int ret;
@@ -1937,14 +1928,10 @@ int tracefs_synth_create(struct tracefs_instance *instance,
 	if (verify_state(synth) < 0)
 		return -1;
 
-	synthetic_event = create_synthetic_event(synth);
-	if (!synthetic_event)
+	if (!synth->dyn_event && alloc_synthetic_event(synth))
+		return -1;
+	if (!tracefs_dynevent_create(synth->dyn_event))
 		return -1;
-
-	ret = tracefs_instance_file_append(NULL, "synthetic_events",
-					   synthetic_event);
-	if (ret < 0)
-		goto free_synthetic;
 
 	start_hist = create_hist(synth->start_keys, synth->start_vars);
 	start_hist = append_filter(start_hist, synth->start_filter,
@@ -1980,9 +1967,7 @@ int tracefs_synth_create(struct tracefs_instance *instance,
  remove_synthetic:
 	free(end_hist);
 	free(start_hist);
-	remove_synthetic(synthetic_event);
- free_synthetic:
-	free(synthetic_event);
+	tracefs_dynevent_destroy(synth->dyn_event, false);
 	return -1;
 }
 
@@ -2007,7 +1992,6 @@ int tracefs_synth_create(struct tracefs_instance *instance,
 int tracefs_synth_destroy(struct tracefs_instance *instance,
 			  struct tracefs_synth *synth)
 {
-	char *synthetic_event;
 	char *hist;
 	int ret;
 
@@ -2041,11 +2025,7 @@ int tracefs_synth_destroy(struct tracefs_instance *instance,
 	ret = remove_hist(instance, synth->start_event, hist);
 	free(hist);
 
-	synthetic_event = create_synthetic_event(synth);
-	if (!synthetic_event)
-		return -1;
-
-	ret = remove_synthetic(synthetic_event);
+	ret = tracefs_dynevent_destroy(synth->dyn_event, false);
 
 	return ret ? -1 : 0;
 }
@@ -2067,7 +2047,7 @@ int tracefs_synth_show(struct trace_seq *seq,
 		       struct tracefs_instance *instance,
 		       struct tracefs_synth *synth)
 {
-	char *synthetic_event = NULL;
+	bool new_event = false;
 	char *hist = NULL;
 	char *path;
 	int ret = -1;
@@ -2082,16 +2062,19 @@ int tracefs_synth_show(struct trace_seq *seq,
 		return -1;
 	}
 
-	synthetic_event = create_synthetic_event(synth);
-	if (!synthetic_event)
-		return -1;
+	if (!synth->dyn_event) {
+		if (alloc_synthetic_event(synth))
+			return -1;
+		new_event = true;
+	}
 
 	path = trace_find_tracing_dir();
 	if (!path)
 		goto out_free;
 
-	trace_seq_printf(seq, "echo '%s' > %s/synthetic_events\n",
-			 synthetic_event, path);
+	trace_seq_printf(seq, "echo '%s%s %s' > %s/%s\n",
+			 synth->dyn_event->prefix, synth->dyn_event->event,
+			 synth->dyn_event->format, path, synth->dyn_event->trace_file);
 
 	tracefs_put_tracing_file(path);
 	path = tracefs_instance_get_dir(instance);
@@ -2116,10 +2099,18 @@ int tracefs_synth_show(struct trace_seq *seq,
 			 hist, path, synth->end_event->system,
 			 synth->end_event->name);
 
+	if (new_event) {
+		tracefs_dynevent_free(synth->dyn_event);
+		synth->dyn_event = NULL;
+	}
+
 	ret = 0;
  out_free:
-	free(synthetic_event);
 	free(hist);
 	tracefs_put_tracing_file(path);
+	if (new_event) {
+		tracefs_dynevent_free(synth->dyn_event);
+		synth->dyn_event = NULL;
+	}
 	return ret;
 }
-- 
2.31.1