tracing: Use the ring-buffer nesting to allow synthetic events to be traced
Synthetic events can be done within the recording of other events. Notify
the ring buffer via ring_buffer_nest_start() and ring_buffer_nest_end() that
this is intended and not to block it due to its recursion protection.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index f7d0da2..4f02764 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -640,6 +640,7 @@ static notrace void trace_event_raw_event_synth(void *__data,
struct trace_event_file *trace_file = __data;
struct synth_trace_event *entry;
struct trace_event_buffer fbuffer;
+ struct ring_buffer *buffer;
struct synth_event *event;
unsigned int i, n_u64;
int fields_size = 0;
@@ -651,10 +652,17 @@ static notrace void trace_event_raw_event_synth(void *__data,
fields_size = event->n_u64 * sizeof(u64);
+ /*
+ * Avoid ring buffer recursion detection, as this event
+ * is being performed within another event.
+ */
+ buffer = trace_file->tr->trace_buffer.buffer;
+ ring_buffer_nest_start(buffer);
+
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + fields_size);
if (!entry)
- return;
+ goto out;
for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
if (event->fields[i]->is_string) {
@@ -670,6 +678,8 @@ static notrace void trace_event_raw_event_synth(void *__data,
}
trace_event_buffer_commit(&fbuffer);
+out:
+ ring_buffer_nest_end(buffer);
}
static void free_synth_event_print_fmt(struct trace_event_call *call)