[52/54] tracing: Add __find_event_file() to find event files without restrictions

Commit Message

[e-mail] Aug. 29, 2018, 12:17 p.m. UTC

By adding the function __find_event_file() that can search for files without
restrictions, such as if the event associated with the file has a reg
function, or if it has the "ignore" flag set, the files that are associated
to ftrace internal events (like trace_marker and function events) can be
found and used.

find_event_file() still returns a "filtered" file, as most callers need a
valid trace event file. One created by the trace_events.h macros and not one
created for parsing ftrace specific events.

Reviewed-by: Namhyung Kim <[e-mail]>
Signed-off-by: Steven Rostedt (VMware) <[e-mail]>
(cherry picked from commit 3c96529c0739959e2aa235d44e47f5c68c1e40de)
Signed-off-by: Hirotaka MOTAI <[e-mail]>
---
 kernel/trace/trace.h        |  3 +++
 kernel/trace/trace_events.c | 22 +++++++++++++++++-----
 2 files changed, 20 insertions(+), 5 deletions(-)

Patch

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 0b8af849..267ffa24 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1456,16 +1456,19 @@  struct ftrace_event_field *
 trace_find_event_field(struct trace_event_call *call, char *name);
 
 extern void trace_event_enable_cmd_record(bool enable);
 extern void trace_event_enable_tgid_record(bool enable);
 
 extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
 extern int event_trace_del_tracer(struct trace_array *tr);
 
+extern struct trace_event_file *__find_event_file(struct trace_array *tr,
+						  const char *system,
+						  const char *event);
 extern struct trace_event_file *find_event_file(struct trace_array *tr,
 						const char *system,
 						const char *event);
 
 static inline void *event_file_data(struct file *filp)
 {
 	return ACCESS_ONCE(file_inode(filp)->i_private);
 }
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index d53268a4..4076f143 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2470,41 +2470,53 @@  __trace_add_event_dirs(struct trace_array *tr)
 	list_for_each_entry(call, &ftrace_events, list) {
 		ret = __trace_add_new_event(call, tr);
 		if (ret < 0)
 			pr_warn("Could not create directory for event %s\n",
 				trace_event_name(call));
 	}
 }
 
+/* Returns any file that matches the system and event */
 struct trace_event_file *
-find_event_file(struct trace_array *tr, const char *system,  const char *event)
+__find_event_file(struct trace_array *tr, const char *system, const char *event)
 {
 	struct trace_event_file *file;
 	struct trace_event_call *call;
 	const char *name;
 
 	list_for_each_entry(file, &tr->events, list) {
 
 		call = file->event_call;
 		name = trace_event_name(call);
 
-		if (!name || !call->class || !call->class->reg)
-			continue;
-
-		if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
+		if (!name || !call->class)
 			continue;
 
 		if (strcmp(event, name) == 0 &&
 		    strcmp(system, call->class->system) == 0)
 			return file;
 	}
 	return NULL;
 }
 
+/* Returns valid trace event files that match system and event */
+struct trace_event_file *
+find_event_file(struct trace_array *tr, const char *system, const char *event)
+{
+	struct trace_event_file *file;
+
+	file = __find_event_file(tr, system, event);
+	if (!file || !file->event_call->class->reg ||
+	    file->event_call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
+		return NULL;
+
+	return file;
+}
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 
 /* Avoid typos */
 #define ENABLE_EVENT_STR	"enable_event"
 #define DISABLE_EVENT_STR	"disable_event"
 
 struct event_probe_data {
 	struct trace_event_file	*file;