linux-kernel - [PATCH] tracing: Skip software disabled event at __synth_event_trace

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Date:   Wed, 12 Feb 2020 14:54:19 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Tom Zanussi <zanussi@...nel.org>,
        artem.bityutskiy@...ux.intel.com, linux-kernel@...r.kernel.org,
        linux-rt-users@...r.kernel.org
Subject: [PATCH] tracing: Skip software disabled event at __synth_event_trace_end()

When the synthetic event is software disabled,
__synth_event_trace_start() does not allocate an event buffer.
In this case __synth_event_trace_end() also should not commit
the buffer.

Check the trace_state->disabled at __synth_event_trace_end()
and if it is disabled, skip it.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 kernel/trace/trace_events_hist.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 483b3fd1094f..781e4b55e117 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1847,6 +1847,9 @@ __synth_event_trace_start(struct trace_event_file *file,
 static inline void
 __synth_event_trace_end(struct synth_event_trace_state *trace_state)
 {
+	if (trace_state->disabled)
+		return;
+
 	trace_event_buffer_commit(&trace_state->fbuffer);
 
 	ring_buffer_nest_end(trace_state->buffer);