3 files changed, 25 insertions, 0 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c3e4575e7829..077d85387908 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3863,6 +3863,14 @@ void ftrace_kill(void)
 }
 
 /**
+ * Test if ftrace is dead or not.
+ */
+int ftrace_is_dead(void)
+{
+        return ftrace_disabled;
+}
+
+/**
  * register_ftrace_function - register a function for profiling
  * @ops - ops structure that holds the function for profiling.
  *
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4b8df0dc9358..13f2b8472fed 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2160,6 +2160,14 @@ void trace_default_header(struct seq_file *m)
         }
 }
 
+static void test_ftrace_alive(struct seq_file *m)
+{
+        if (!ftrace_is_dead())
+                return;
+        seq_printf(m, "# WARNING: FUNCTION TRACING IS CORRUPTED\n");
+        seq_printf(m, "#          MAY BE MISSING FUNCTION EVENTS\n");
+}
+
 static int s_show(struct seq_file *m, void *v)
 {
         struct trace_iterator *iter = v;
@@ -2169,6 +2177,7 @@ static int s_show(struct seq_file *m, void *v)
                 if (iter->tr) {
                         seq_printf(m, "# tracer: %s\n", iter->trace->name);
                         seq_puts(m, "#\n");
+                        test_ftrace_alive(m);
                 }
                 if (iter->trace && iter->trace->print_header)
                         iter->trace->print_header(m);
@@ -4613,6 +4622,12 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
 
         tracing_off();
 
+        /* Did function tracer already get disabled? */
+        if (ftrace_is_dead()) {
+                printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
+                printk("#          MAY BE MISSING FUNCTION EVENTS\n");
+        }
+
         if (disable_tracing)
                 ftrace_kill();
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 4c7540ad5dcb..092e1f8d18dc 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -579,11 +579,13 @@ static inline int ftrace_trace_task(struct task_struct *task)
 
         return test_tsk_trace_trace(task);
 }
+extern int ftrace_is_dead(void);
 #else
 static inline int ftrace_trace_task(struct task_struct *task)
 {
         return 1;
 }
+static inline int ftrace_is_dead(void) { return 0; }
 #endif
 
 /*