Re: [PATCH 1/4] tracing: Consolidate some synth_event_trace code

[Tom Zanussi]

On Fri, 2020-01-31 at 17:43 -0500, Steven Rostedt wrote:
> On Fri, 31 Jan 2020 15:55:31 -0600
> Tom Zanussi <zanussi@xxxxxxxxxx> wrote:
> 
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct
> > trace_event_file *file,
> >  }
> >  EXPORT_SYMBOL_GPL(synth_event_trace_start);
> >  
> > -static int save_synth_val(struct synth_field *field, u64 val,
> > +int __synth_event_add_val(const char *field_name, u64 val,
> 
> Hmm, shouldn't __synth_event_add_val() still be static?
> 
> -- Steve
> 
> >  			  struct synth_event_trace_state
> > *trace_state)
> >  {
> > -	struct synth_trace_event *entry = trace_state->entry;
> > +	struct synth_field *field = NULL;
> > +	struct synth_trace_event *entry;
> > +	struct synth_event *event;
> > +	int i, ret = 0;
> > +

Here's the patch with __synth_event_add_val() made static.  Let me know
if you want me to just do a v2 of this series..

Thanks,

Tom

[PATCH] tracing: Consolidate some synth_event_trace code

The synth_event trace code contains some almost identical functions
and some small functions that are called only once - consolidate the
common code into single functions and fold in the small functions to
simplify the code overall.

Signed-off-by: Tom Zanussi <zanussi@xxxxxxxxxx>
---
 kernel/trace/trace_events_hist.c | 141 ++++++++++++++++-----------------------
 1 file changed, 57 insertions(+), 84 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 5b4e04780411..42058a1b5146 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct trace_event_file *file,
 }
 EXPORT_SYMBOL_GPL(synth_event_trace_start);
 
-static int save_synth_val(struct synth_field *field, u64 val,
-			  struct synth_event_trace_state *trace_state)
+static int __synth_event_add_val(const char *field_name, u64 val,
+				 struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry = trace_state->entry;
+	struct synth_field *field = NULL;
+	struct synth_trace_event *entry;
+	struct synth_event *event;
+	int i, ret = 0;
+
+	if (!trace_state) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* can't mix add_next_synth_val() with add_synth_val() */
+	if (field_name) {
+		if (trace_state->add_next) {
+			ret = -EINVAL;
+			goto out;
+		}
+		trace_state->add_name = true;
+	} else {
+		if (trace_state->add_name) {
+			ret = -EINVAL;
+			goto out;
+		}
+		trace_state->add_next = true;
+	}
+
+	if (!trace_state->enabled)
+		goto out;
+
+	event = trace_state->event;
+	if (trace_state->add_name) {
+		for (i = 0; i < event->n_fields; i++) {
+			field = event->fields[i];
+			if (strcmp(field->name, field_name) == 0)
+				break;
+		}
+		if (!field) {
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		if (trace_state->cur_field >= event->n_fields) {
+			ret = -EINVAL;
+			goto out;
+		}
+		field = event->fields[trace_state->cur_field++];
+	}
 
+	entry = trace_state->entry;
 	if (field->is_string) {
 		char *str_val = (char *)(long)val;
 		char *str_field;
 
-		if (!str_val)
-			return -EINVAL;
+		if (!str_val) {
+			ret = -EINVAL;
+			goto out;
+		}
 
 		str_field = (char *)&entry->fields[field->offset];
 		strscpy(str_field, str_val, STR_VAR_LEN_MAX);
 	} else
 		entry->fields[field->offset] = val;
-
-	return 0;
+ out:
+	return ret;
 }
 
 /**
@@ -2104,54 +2152,10 @@ static int save_synth_val(struct synth_field *field, u64 val,
 int synth_event_add_next_val(u64 val,
 			     struct synth_event_trace_state *trace_state)
 {
-	struct synth_field *field;
-	struct synth_event *event;
-	int ret = 0;
-
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* can't mix add_next_synth_val() with add_synth_val() */
-	if (trace_state->add_name) {
-		ret = -EINVAL;
-		goto out;
-	}
-	trace_state->add_next = true;
-
-	if (!trace_state->enabled)
-		goto out;
-
-	event = trace_state->event;
-
-	if (trace_state->cur_field >= event->n_fields) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	field = event->fields[trace_state->cur_field++];
-	ret = save_synth_val(field, val, trace_state);
- out:
-	return ret;
+	return __synth_event_add_val(NULL, val, trace_state);
 }
 EXPORT_SYMBOL_GPL(synth_event_add_next_val);
 
-static struct synth_field *find_synth_field(struct synth_event *event,
-					    const char *field_name)
-{
-	struct synth_field *field = NULL;
-	unsigned int i;
-
-	for (i = 0; i < event->n_fields; i++) {
-		field = event->fields[i];
-		if (strcmp(field->name, field_name) == 0)
-			return field;
-	}
-
-	return NULL;
-}
-
 /**
  * synth_event_add_val - Add a named field's value to an open synth trace
  * @field_name: The name of the synthetic event field value to set
@@ -2183,38 +2187,7 @@ static struct synth_field *find_synth_field(struct synth_event *event,
 int synth_event_add_val(const char *field_name, u64 val,
 			struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry;
-	struct synth_event *event;
-	struct synth_field *field;
-	int ret = 0;
-
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* can't mix add_next_synth_val() with add_synth_val() */
-	if (trace_state->add_next) {
-		ret = -EINVAL;
-		goto out;
-	}
-	trace_state->add_name = true;
-
-	if (!trace_state->enabled)
-		goto out;
-
-	event = trace_state->event;
-	entry = trace_state->entry;
-
-	field = find_synth_field(event, field_name);
-	if (!field) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = save_synth_val(field, val, trace_state);
- out:
-	return ret;
+	return __synth_event_add_val(field_name, val, trace_state);
 }
 EXPORT_SYMBOL_GPL(synth_event_add_val);
 
-- 
2.14.1