tracing: x86, mmiotrace: only register for die notifier when tracer active

Follow up to afcfe024aebd74b0984a41af9a34e009cf5badaf in Linus' tree
("x86: mmiotrace: quieten spurious warning message")

Signed-off-by: Stuart Bennett <stuart@freedesktop.org>
Acked-by: Pekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1240946271-7083-5-git-send-email-stuart@freedesktop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index c9342ed..132772a 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -451,6 +451,7 @@
 
 	if (nommiotrace)
 		pr_info(NAME "MMIO tracing disabled.\n");
+	kmmio_init();
 	enter_uniprocessor();
 	spin_lock_irq(&trace_lock);
 	atomic_inc(&mmiotrace_enabled);
@@ -473,6 +474,7 @@
 
 	clear_trace_list(); /* guarantees: no more kmmio callbacks */
 	leave_uniprocessor();
+	kmmio_cleanup();
 	pr_info(NAME "disabled.\n");
 out:
 	mutex_unlock(&mmiotrace_mutex);