linux-kernel - [PATCH 7/7] tracing: Add tracing_event_time

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Message-ID: <20210312211505.818683162@goodmis.org>
Date:   Fri, 12 Mar 2021 16:14:00 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Zanussi, Tom" <tom.zanussi@...ux.intel.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Yordan Karadzhov" <y.karadz@...il.com>
Subject: [PATCH 7/7] tracing: Add tracing_event_time_stamp() API

From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>

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.

Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/trace.c | 10 ++++++++++
 kernel/trace/trace.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8cf7397f3f56..a8d5356ed327 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7120,6 +7120,16 @@ static int tracing_time_stamp_mode_open(struct inode *inode, struct file *file)
 	return ret;
 }
 
+u64 tracing_event_time_stamp(struct trace_array *tr, struct ring_buffer_event *rbe)
+{
+	struct trace_buffer *buffer = tr->array_buffer.buffer;
+
+	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 de717706e863..23d85e78bef4 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_array *tr, 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