[PATCH] ftrace: allow dumping traces without tracking trace started cpus

[Sasha Levin <sasha.levin@oracle.com>]

We don't init iter->started when dumping the ftrace buffer, and there's no
real need to do so - so allow skipping that check if the iter doesn't have
an initialized ->started cpumask.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 kernel/trace/trace.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6e79408..0dc647f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2671,13 +2671,14 @@ static void test_cpu_buff_start(struct trace_iterator *iter)
 	if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
 		return;
 
-	if (cpumask_test_cpu(iter->cpu, iter->started))
+	if (iter->started && cpumask_test_cpu(iter->cpu, iter->started))
 		return;
 
 	if (per_cpu_ptr(iter->trace_buffer->data, iter->cpu)->skipped_entries)
 		return;
 
-	cpumask_set_cpu(iter->cpu, iter->started);
+	if (iter->started)
+		cpumask_set_cpu(iter->cpu, iter->started);
 
 	/* Don't print started cpu buffer for the first entry of the trace */
 	if (iter->idx > 1)
-- 
1.7.10.4