Added new API for opening trace_marker file of given instance:
tracefs_trace_marker_get_fd();
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
---
Documentation/libtracefs-utils.txt | 20 +++++++++++++++++++-
include/tracefs.h | 13 +++++++++++++
2 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/Documentation/libtracefs-utils.txt b/Documentation/libtracefs-utils.txt
index 41544ab..0935199 100644
--- a/Documentation/libtracefs-utils.txt
+++ b/Documentation/libtracefs-utils.txt
@@ -3,7 +3,8 @@ libtracefs(3)
NAME
----
-tracefs_tracers, tracefs_get_clock, tracefs_list_free -
+tracefs_tracers, tracefs_get_clock, tracefs_list_free,
+tracefs_trace_marker_get_fd -
Helper functions for working with trace file system.
SYNOPSIS
@@ -15,6 +16,7 @@ SYNOPSIS
char pass:[*]pass:[*]*tracefs_tracers*(const char pass:[*]_tracing_dir_);
char pass:[*]*tracefs_get_clock*(struct tracefs_instance pass:[*]_instance_);
void *tracefs_list_free*(char pass:[*]pass:[*]_list_);
+int *tracefs_trace_marker_get_fd*(struct tracefs_instance pass:[*]_instance_);
--
DESCRIPTION
@@ -36,6 +38,10 @@ The _tracefs_list_free()_ function frees an array of strings, returned by
_tracefs_event_systems()_, _tracefs_system_events()_ and _tracefs_tracers()_
APIs.
+The _tracefs_trace_marker_get_fd()_ function returns a file deascriptor to the "trace_marker" file
+from the given _instance_. If _instance_ is NULL, the top trace instance is used. The returned
+descriptor can be used for writing trace markers in the trace buffer of the instance.
+
RETURN VALUE
------------
The _tracefs_tracers()_ returns array of strings. The last element in that
@@ -45,6 +51,10 @@ In case of an error, NULL is returned.
The _tracefs_get_clock()_ returns string, that must be freed with free(), or NULL
in case of an error.
+The _tracefs_trace_marker_get_fd()_ function returns a file descriptor to "trace_marker"
+file for reading and writing, which must be closed wuth close(). In case of an error -1 is returned.
+
+
EXAMPLE
-------
[source,c]
@@ -66,6 +76,14 @@ char *clock = tracefs_get_clock(NULL);
...
free(clock);
}
+...
+int marker_fd = tracefs_trace_marker_get_fd(NULL);
+char *my_marker = "User tarce event";
+ if (marker_fd < 0) {
+ /* Failed to open marker file */
+ }
+ write(marker_fd, my_marker, strlen(my_marker));
+ close(marker_fd);
--
FILES
-----
diff --git a/include/tracefs.h b/include/tracefs.h
index f3eec62..dff365a 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -63,6 +63,19 @@ static inline int tracefs_trace_on_get_fd(struct tracefs_instance *instance)
return tracefs_instance_file_open(instance, "tracing_on", O_RDWR);
}
+/**
+ * tracefs_trace_marker_get_fd - Get a file descriptor of "trace_marker" in
+ * given instance
+ * @instance: ftrace instance, can be NULL for the top instance
+ *
+ * Returns -1 in case of an error, or a valid file descriptor to "trace_marker"
+ * file for reading and writing. The returned FD must be closed with close().
+ */
+static inline int tracefs_trace_marker_get_fd(struct tracefs_instance *instance)
+{
+ return tracefs_instance_file_open(instance, "trace_marker", O_RDWR);
+}
+
/* events */
void tracefs_list_free(char **list);
char **tracefs_event_systems(const char *tracing_dir);
--
2.29.2
|