[PATCH v12 05/13] trace-cmd: Add buffer instance flags for tracing in guest and agent context

["Slavomir Kaslev (VMware)" <slavomir.kaslev@gmail.com>]

From: Slavomir Kaslev <kaslevs@vmware.com>

Add BUFFER_FL_GUEST and BUFFER_FL_AGENT flags to differentiate when
trace-record.c is being called to trace guest or the VM tracing agent.

Also disable functions talking to the local tracefs when called in recording
guest instances context.

Signed-off-by: Slavomir Kaslev <kaslevs@vmware.com>
---
 tracecmd/include/trace-local.h |  5 +++
 tracecmd/trace-record.c        | 58 ++++++++++++++++++++++++++++++++--
 2 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 1cad3cc..302f749 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -149,6 +149,8 @@ char *strstrip(char *str);
 enum buffer_instance_flags {
 	BUFFER_FL_KEEP		= 1 << 0,
 	BUFFER_FL_PROFILE	= 1 << 1,
+	BUFFER_FL_GUEST		= 1 << 2,
+	BUFFER_FL_AGENT		= 1 << 3,
 };
 
 struct func_list {
@@ -200,6 +202,9 @@ extern struct buffer_instance *first_instance;
 #define for_all_instances(i) for (i = first_instance; i; \
 				  i = i == &top_instance ? buffer_instances : (i)->next)
 
+#define is_agent(instance)	((instance)->flags & BUFFER_FL_AGENT)
+#define is_guest(instance)	((instance)->flags & BUFFER_FL_GUEST)
+
 struct buffer_instance *create_instance(const char *name);
 void add_instance(struct buffer_instance *instance, int cpu_count);
 char *get_instance_file(struct buffer_instance *instance, const char *file);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 5dc6f17..4198db7 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -822,6 +822,9 @@ static void __clear_trace(struct buffer_instance *instance)
 	FILE *fp;
 	char *path;
 
+	if (is_guest(instance))
+		return;
+
 	/* reset the trace */
 	path = get_instance_file(instance, "trace");
 	fp = fopen(path, "w");
@@ -1339,6 +1342,9 @@ set_plugin_instance(struct buffer_instance *instance, const char *name)
 	char *path;
 	char zero = '0';
 
+	if (is_guest(instance))
+		return;
+
 	path = get_instance_file(instance, "current_tracer");
 	fp = fopen(path, "w");
 	if (!fp) {
@@ -1435,6 +1441,9 @@ static void disable_func_stack_trace_instance(struct buffer_instance *instance)
 	int size;
 	int ret;
 
+	if (is_guest(instance))
+		return;
+
 	path = get_instance_file(instance, "current_tracer");
 	ret = stat(path, &st);
 	tracecmd_put_tracing_file(path);
@@ -1628,6 +1637,9 @@ reset_events_instance(struct buffer_instance *instance)
 	int i;
 	int ret;
 
+	if (is_guest(instance))
+		return;
+
 	if (use_old_event_method()) {
 		/* old way only had top instance */
 		if (!is_top_instance(instance))
@@ -1940,6 +1952,9 @@ static void write_tracing_on(struct buffer_instance *instance, int on)
 	int ret;
 	int fd;
 
+	if (is_guest(instance))
+		return;
+
 	fd = open_tracing_on(instance);
 	if (fd < 0)
 		return;
@@ -1959,6 +1974,9 @@ static int read_tracing_on(struct buffer_instance *instance)
 	char buf[10];
 	int ret;
 
+	if (is_guest(instance))
+		return -1;
+
 	fd = open_tracing_on(instance);
 	if (fd < 0)
 		return fd;
@@ -2105,6 +2123,9 @@ static void update_pid_filters(struct buffer_instance *instance)
 	int ret;
 	int fd;
 
+	if (is_guest(instance))
+		return;
+
 	fd = open_instance_fd(instance, "set_event_pid",
 			      O_WRONLY | O_CLOEXEC | O_TRUNC);
 	if (fd < 0)
@@ -2200,6 +2221,9 @@ static void set_mask(struct buffer_instance *instance)
 	int fd;
 	int ret;
 
+	if (is_guest(instance))
+		return;
+
 	if (!instance->cpumask)
 		return;
 
@@ -2230,6 +2254,9 @@ static void enable_events(struct buffer_instance *instance)
 {
 	struct event_list *event;
 
+	if (is_guest(instance))
+		return;
+
 	for (event = instance->events; event; event = event->next) {
 		if (!event->neg)
 			update_event(event, event->filter, 0, '1');
@@ -2253,6 +2280,9 @@ static void set_clock(struct buffer_instance *instance)
 	char *content;
 	char *str;
 
+	if (is_guest(instance))
+		return;
+
 	if (!instance->clock)
 		return;
 
@@ -2282,6 +2312,9 @@ static void set_max_graph_depth(struct buffer_instance *instance, char *max_grap
 	char *path;
 	int ret;
 
+	if (is_guest(instance))
+		return;
+
 	path = get_instance_file(instance, "max_graph_depth");
 	reset_save_file(path, RESET_DEFAULT_PRIO);
 	tracecmd_put_tracing_file(path);
@@ -2507,6 +2540,9 @@ static void expand_event_instance(struct buffer_instance *instance)
 	struct event_list *compressed_list = instance->events;
 	struct event_list *event;
 
+	if (is_guest(instance))
+		return;
+
 	reset_event_list(instance);
 
 	while (compressed_list) {
@@ -3394,6 +3430,9 @@ static void set_funcs(struct buffer_instance *instance)
 	int set_notrace = 0;
 	int ret;
 
+	if (is_guest(instance))
+		return;
+
 	ret = write_func_file(instance, "set_ftrace_filter", &instance->filter_funcs);
 	if (ret < 0)
 		die("set_ftrace_filter does not exist. Can not filter functions");
@@ -3690,6 +3729,9 @@ static void set_buffer_size_instance(struct buffer_instance *instance)
 	int ret;
 	int fd;
 
+	if (is_guest(instance))
+		return;
+
 	if (!buffer_size)
 		return;
 
@@ -3900,6 +3942,9 @@ static void make_instances(void)
 	int ret;
 
 	for_each_instance(instance) {
+		if (is_guest(instance))
+			continue;
+
 		path = get_instance_dir(instance);
 		ret = stat(path, &st);
 		if (ret < 0) {
@@ -3921,7 +3966,7 @@ void tracecmd_remove_instances(void)
 
 	for_each_instance(instance) {
 		/* Only delete what we created */
-		if (instance->flags & BUFFER_FL_KEEP)
+		if (is_guest(instance) || (instance->flags & BUFFER_FL_KEEP))
 			continue;
 		if (instance->tracing_on_fd > 0) {
 			close(instance->tracing_on_fd);
@@ -4003,7 +4048,7 @@ static void check_function_plugin(void)
 
 static int __check_doing_something(struct buffer_instance *instance)
 {
-	return (instance->flags & BUFFER_FL_PROFILE) ||
+	return is_guest(instance) || (instance->flags & BUFFER_FL_PROFILE) ||
 		instance->plugin || instance->events;
 }
 
@@ -4025,6 +4070,9 @@ update_plugin_instance(struct buffer_instance *instance,
 {
 	const char *plugin = instance->plugin;
 
+	if (is_guest(instance))
+		return;
+
 	if (!plugin)
 		return;
 
@@ -4124,6 +4172,9 @@ static void record_stats(void)
 	int cpu;
 
 	for_all_instances(instance) {
+		if (is_guest(instance))
+			continue;
+
 		s_save = instance->s_save;
 		s_print = instance->s_print;
 		for (cpu = 0; cpu < instance->cpu_count; cpu++) {
@@ -4150,6 +4201,9 @@ static void destroy_stats(void)
 	int cpu;
 
 	for_all_instances(instance) {
+		if (is_guest(instance))
+			continue;
+
 		for (cpu = 0; cpu < instance->cpu_count; cpu++) {
 			trace_seq_destroy(&instance->s_save[cpu]);
 			trace_seq_destroy(&instance->s_print[cpu]);
-- 
2.20.1