ftrace: only have ftrace_kill atomic

When an anomaly is detected, we need a way to completely disable
ftrace. Right now we have two functions: ftrace_kill and ftrace_kill_atomic.
The ftrace_kill tries to do it in a "nice" way by converting everything
back to a nop.

The "nice" way is dangerous itself, so this patch removes it and only
has the "atomic" version, which is all that is needed.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index aeb2f25..333a516 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3097,7 +3097,7 @@
 	dump_ran = 1;
 
 	/* No turning back! */
-	ftrace_kill_atomic();
+	ftrace_kill();
 
 	for_each_tracing_cpu(cpu) {
 		atomic_inc(&global_trace.data[cpu]->disabled);