[tip:perf/core] tools lib traceevent: Add way to find sub buffer boundary

["tip-bot for Steven Rostedt (Red Hat)" <tipbot@zytor.com>]

Commit-ID:  82ac952be6348dc072dcfd80a2dcb511d0cd6bea
Gitweb:     http://git.kernel.org/tip/82ac952be6348dc072dcfd80a2dcb511d0cd6bea
Author:     Steven Rostedt (Red Hat) <rostedt@goodmis.org>
AuthorDate: Tue, 24 Mar 2015 09:57:56 -0400
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 24 Mar 2015 12:22:09 -0300

tools lib traceevent: Add way to find sub buffer boundary

For debugging purposes, it may be helpful for the kbuffer library to flag
when crossing a sub buffer.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20150324135923.650983637@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/lib/traceevent/kbuffer-parse.c | 11 +++++++++++
 tools/lib/traceevent/kbuffer.h       |  1 +
 2 files changed, 12 insertions(+)

diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
index deb3569..3bcada3 100644
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/tools/lib/traceevent/kbuffer-parse.c
@@ -729,3 +729,14 @@ void kbuffer_set_old_format(struct kbuffer *kbuf)
 
 	kbuf->next_event = __old_next_event;
 }
+
+/**
+ * kbuffer_start_of_data - return offset of where data starts on subbuffer
+ * @kbuf:	The kbuffer
+ *
+ * Returns the location on the subbuffer where the data starts.
+ */
+int kbuffer_start_of_data(struct kbuffer *kbuf)
+{
+	return kbuf->start;
+}
diff --git a/tools/lib/traceevent/kbuffer.h b/tools/lib/traceevent/kbuffer.h
index c831f64..03dce75 100644
--- a/tools/lib/traceevent/kbuffer.h
+++ b/tools/lib/traceevent/kbuffer.h
@@ -63,5 +63,6 @@ int kbuffer_missed_events(struct kbuffer *kbuf);
 int kbuffer_subbuffer_size(struct kbuffer *kbuf);
 
 void kbuffer_set_old_format(struct kbuffer *kbuf);
+int kbuffer_start_of_data(struct kbuffer *kbuf);
 
 #endif /* _K_BUFFER_H */