[RFC PATCH v4 14/22] tracing: Add NULL trace-array check in print_synth_event()

[Masami Hiramatsu]

Add NULL trace-array check in print_synth_event(), because
if we enable tp_printk option, iter->tr can be NULL.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 kernel/trace/trace_events_hist.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 06d91bb59297..d902a61775c4 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -833,7 +833,7 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
 		fmt = synth_field_fmt(se->fields[i]->type);
 
 		/* parameter types */
-		if (tr->trace_flags & TRACE_ITER_VERBOSE)
+		if (tr && tr->trace_flags & TRACE_ITER_VERBOSE)
 			trace_seq_printf(s, "%s ", fmt);
 
 		snprintf(print_fmt, sizeof(print_fmt), "%%s=%s%%s", fmt);