tracing: Fix initialization failure path in tracing_set_tracer()
If tracer->init() fails, current code will leave current_tracer pointing
to an unusable tracer, which at best makes 'current_tracer' report
inaccurate value.
Fix the issue by pointing current_tracer to nop tracer, and only update
current_tracer with the new one after all the initialization succeeds.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 49249c2..44ee11e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3172,10 +3172,10 @@
}
destroy_trace_option_files(topts);
- current_trace = t;
+ current_trace = &nop_trace;
- topts = create_trace_option_files(current_trace);
- if (current_trace->use_max_tr) {
+ topts = create_trace_option_files(t);
+ if (t->use_max_tr) {
int cpu;
/* we need to make per cpu buffer sizes equivalent */
for_each_tracing_cpu(cpu) {
@@ -3195,6 +3195,7 @@
goto out;
}
+ current_trace = t;
trace_branch_enable(tr);
out:
mutex_unlock(&trace_types_lock);
