[for-next][PATCH 07/13] tracing: Add tracing_event_time_stamp() API

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

Add a tracing_event_time_stamp() API that checks if the event passed in is
not on the ring buffer but a pointer to the per CPU trace_buffered_event
which does not have its time stamp set yet.

If it is a pointer to the trace_buffered_event, then just return the
current time stamp that the ring buffer would produce.

Otherwise, return the time stamp from the event.

Link: https://lkml.kernel.org/r/20210316164114.131996180@xxxxxxxxxxx

Reviewed-by: Tom Zanussi <zanussi@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace.c | 8 ++++++++
 kernel/trace/trace.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b15436ff85e8..90ae3140756e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6972,6 +6972,14 @@ static int tracing_time_stamp_mode_open(struct inode *inode, struct file *file)
 	return ret;
 }
 
+u64 tracing_event_time_stamp(struct trace_buffer *buffer, struct ring_buffer_event *rbe)
+{
+	if (rbe == this_cpu_read(trace_buffered_event))
+		return ring_buffer_time_stamp(buffer, smp_processor_id());
+
+	return ring_buffer_event_time_stamp(buffer, rbe);
+}
+
 /*
  * Set or disable using the per CPU trace_buffer_event when possible.
  */
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f2a7a72825c7..0d8f54f49a3a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -372,6 +372,7 @@ extern int tracing_check_open_get_tr(struct trace_array *tr);
 extern struct trace_array *trace_array_find(const char *instance);
 extern struct trace_array *trace_array_find_get(const char *instance);
 
+extern u64 tracing_event_time_stamp(struct trace_buffer *buffer, struct ring_buffer_event *rbe);
 extern int tracing_set_filter_buffering(struct trace_array *tr, bool set);
 extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);
 
-- 
2.30.1