tracing: Consolidate trace() functions

Move the checking, buffer reserve and buffer commit code in
synth_event_trace_start/end() into inline functions
__synth_event_trace_start/end() so they can also be used by
synth_event_trace() and synth_event_trace_array(), and then have all
those functions use them.

Also, change synth_event_trace_state.enabled to disabled so it only
needs to be set if the event is disabled, which is not normally the
case.

Link: http://lkml.kernel.org/r/b1f3108d0f450e58192955a300e31d0405ab4149.1581374549.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

Author: Tom Zanussi

include/linux/trace_events.h

@@ -424,7 +424,7 @@ struct synth_event_trace_state {
 	struct synth_event *event;
 	unsigned int cur_field;
 	unsigned int n_u64;
-	bool enabled;
+	bool disabled;
 	bool add_next;
 	bool add_name;
 };

kernel/trace/trace_events_hist.c

@@ -1791,6 +1791,60 @@ void synth_event_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen)
 }
 EXPORT_SYMBOL_GPL(synth_event_cmd_init);
 
+static inline int
+__synth_event_trace_start(struct trace_event_file *file,
+			  struct synth_event_trace_state *trace_state)
+{
+	int entry_size, fields_size = 0;
+	int ret = 0;
+
+	/*
+	 * Normal event tracing doesn't get called at all unless the
+	 * ENABLED bit is set (which attaches the probe thus allowing
+	 * this code to be called, etc).  Because this is called
+	 * directly by the user, we don't have that but we still need
+	 * to honor not logging when disabled.  For the the iterated
+	 * trace case, we save the enabed state upon start and just
+	 * ignore the following data calls.
+	 */
+	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
+	    trace_trigger_soft_disabled(file)) {
+		trace_state->disabled = true;
+		ret = -ENOENT;
+		goto out;
+	}
+
+	trace_state->event = file->event_call->data;
+
+	fields_size = trace_state->event->n_u64 * sizeof(u64);
+
+	/*
+	 * Avoid ring buffer recursion detection, as this event
+	 * is being performed within another event.
+	 */
+	trace_state->buffer = file->tr->array_buffer.buffer;
+	ring_buffer_nest_start(trace_state->buffer);
+
+	entry_size = sizeof(*trace_state->entry) + fields_size;
+	trace_state->entry = trace_event_buffer_reserve(&trace_state->fbuffer,
+							file,
+							entry_size);
+	if (!trace_state->entry) {
+		ring_buffer_nest_end(trace_state->buffer);
+		ret = -EINVAL;
+	}
+out:
+	return ret;
+}
+
+static inline void
+__synth_event_trace_end(struct synth_event_trace_state *trace_state)
+{
+	trace_event_buffer_commit(&trace_state->fbuffer);
+
+	ring_buffer_nest_end(trace_state->buffer);
+}
+
 /**
  * synth_event_trace - Trace a synthetic event
  * @file: The trace_event_file representing the synthetic event
@@ -1812,69 +1866,38 @@ EXPORT_SYMBOL_GPL(synth_event_cmd_init);
  */
 int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
 {
-	struct trace_event_buffer fbuffer;
-	struct synth_trace_event *entry;
-	struct trace_buffer *buffer;
-	struct synth_event *event;
+	struct synth_event_trace_state state;
 	unsigned int i, n_u64;
-	int fields_size = 0;
 	va_list args;
-	int ret = 0;
-
-	/*
-	 * Normal event generation doesn't get called at all unless
-	 * the ENABLED bit is set (which attaches the probe thus
-	 * allowing this code to be called, etc).  Because this is
-	 * called directly by the user, we don't have that but we
-	 * still need to honor not logging when disabled.
-	 */
-	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
-	    trace_trigger_soft_disabled(file))
-		return 0;
-
-	event = file->event_call->data;
-
-	if (n_vals != event->n_fields)
-		return -EINVAL;
-
-	fields_size = event->n_u64 * sizeof(u64);
-
-	/*
-	 * Avoid ring buffer recursion detection, as this event
-	 * is being performed within another event.
-	 */
-	buffer = file->tr->array_buffer.buffer;
-	ring_buffer_nest_start(buffer);
+	int ret;
 
-	entry = trace_event_buffer_reserve(&fbuffer, file,
-					   sizeof(*entry) + fields_size);
-	if (!entry) {
-		ret = -EINVAL;
-		goto out;
+	ret = __synth_event_trace_start(file, &state);
+	if (ret) {
+		if (ret == -ENOENT)
+			ret = 0; /* just disabled, not really an error */
+		return ret;
 	}
 
 	va_start(args, n_vals);
-	for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
+	for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
 		u64 val;
 
 		val = va_arg(args, u64);
 
-		if (event->fields[i]->is_string) {
+		if (state.event->fields[i]->is_string) {
 			char *str_val = (char *)(long)val;
-			char *str_field = (char *)&entry->fields[n_u64];
+			char *str_field = (char *)&state.entry->fields[n_u64];
 
 			strscpy(str_field, str_val, STR_VAR_LEN_MAX);
 			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
 		} else {
-			entry->fields[n_u64] = val;
+			state.entry->fields[n_u64] = val;
 			n_u64++;
 		}
 	}
 	va_end(args);
 
-	trace_event_buffer_commit(&fbuffer);
-out:
-	ring_buffer_nest_end(buffer);
+	__synth_event_trace_end(&state);
 
 	return ret;
 }
@@ -1901,62 +1924,31 @@ EXPORT_SYMBOL_GPL(synth_event_trace);
 int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
 			    unsigned int n_vals)
 {
-	struct trace_event_buffer fbuffer;
-	struct synth_trace_event *entry;
-	struct trace_buffer *buffer;
-	struct synth_event *event;
+	struct synth_event_trace_state state;
 	unsigned int i, n_u64;
-	int fields_size = 0;
-	int ret = 0;
-
-	/*
-	 * Normal event generation doesn't get called at all unless
-	 * the ENABLED bit is set (which attaches the probe thus
-	 * allowing this code to be called, etc).  Because this is
-	 * called directly by the user, we don't have that but we
-	 * still need to honor not logging when disabled.
-	 */
-	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
-	    trace_trigger_soft_disabled(file))
-		return 0;
-
-	event = file->event_call->data;
-
-	if (n_vals != event->n_fields)
-		return -EINVAL;
-
-	fields_size = event->n_u64 * sizeof(u64);
-
-	/*
-	 * Avoid ring buffer recursion detection, as this event
-	 * is being performed within another event.
-	 */
-	buffer = file->tr->array_buffer.buffer;
-	ring_buffer_nest_start(buffer);
+	int ret;
 
-	entry = trace_event_buffer_reserve(&fbuffer, file,
-					   sizeof(*entry) + fields_size);
-	if (!entry) {
-		ret = -EINVAL;
-		goto out;
+	ret = __synth_event_trace_start(file, &state);
+	if (ret) {
+		if (ret == -ENOENT)
+			ret = 0; /* just disabled, not really an error */
+		return ret;
 	}
 
-	for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
-		if (event->fields[i]->is_string) {
+	for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
+		if (state.event->fields[i]->is_string) {
 			char *str_val = (char *)(long)vals[i];
-			char *str_field = (char *)&entry->fields[n_u64];
+			char *str_field = (char *)&state.entry->fields[n_u64];
 
 			strscpy(str_field, str_val, STR_VAR_LEN_MAX);
 			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
 		} else {
-			entry->fields[n_u64] = vals[i];
+			state.entry->fields[n_u64] = vals[i];
 			n_u64++;
 		}
 	}
 
-	trace_event_buffer_commit(&fbuffer);
-out:
-	ring_buffer_nest_end(buffer);
+	__synth_event_trace_end(&state);
 
 	return ret;
 }
@@ -1993,55 +1985,17 @@ EXPORT_SYMBOL_GPL(synth_event_trace_array);
 int synth_event_trace_start(struct trace_event_file *file,
 			    struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry;
-	int fields_size = 0;
-	int ret = 0;
+	int ret;
 
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (!trace_state)
+		return -EINVAL;
 
 	memset(trace_state, '\0', sizeof(*trace_state));
 
-	/*
-	 * Normal event tracing doesn't get called at all unless the
-	 * ENABLED bit is set (which attaches the probe thus allowing
-	 * this code to be called, etc).  Because this is called
-	 * directly by the user, we don't have that but we still need
-	 * to honor not logging when disabled.  For the the iterated
-	 * trace case, we save the enabed state upon start and just
-	 * ignore the following data calls.
-	 */
-	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
-	    trace_trigger_soft_disabled(file)) {
-		trace_state->enabled = false;
-		goto out;
-	}
-
-	trace_state->enabled = true;
+	ret = __synth_event_trace_start(file, trace_state);
+	if (ret == -ENOENT)
+		ret = 0; /* just disabled, not really an error */
 
-	trace_state->event = file->event_call->data;
-
-	fields_size = trace_state->event->n_u64 * sizeof(u64);
-
-	/*
-	 * Avoid ring buffer recursion detection, as this event
-	 * is being performed within another event.
-	 */
-	trace_state->buffer = file->tr->array_buffer.buffer;
-	ring_buffer_nest_start(trace_state->buffer);
-
-	entry = trace_event_buffer_reserve(&trace_state->fbuffer, file,
-					   sizeof(*entry) + fields_size);
-	if (!entry) {
-		ring_buffer_nest_end(trace_state->buffer);
-		ret = -EINVAL;
-		goto out;
-	}
-
-	trace_state->entry = entry;
-out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(synth_event_trace_start);
@@ -2074,7 +2028,7 @@ static int __synth_event_add_val(const char *field_name, u64 val,
 		trace_state->add_next = true;
 	}
 
-	if (!trace_state->enabled)
+	if (trace_state->disabled)
 		goto out;
 
 	event = trace_state->event;
@@ -2209,9 +2163,7 @@ int synth_event_trace_end(struct synth_event_trace_state *trace_state)
 	if (!trace_state)
 		return -EINVAL;
 
-	trace_event_buffer_commit(&trace_state->fbuffer);
-
-	ring_buffer_nest_end(trace_state->buffer);
+	__synth_event_trace_end(trace_state);
 
 	return 0;
 }