1 files changed, 35 insertions, 29 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 22fa55696760..0e9f9eaade2f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -367,9 +367,6 @@ static int remove_ftrace_list_ops(struct ftrace_ops **list,
 
 static int __register_ftrace_function(struct ftrace_ops *ops)
 {
-        if (unlikely(ftrace_disabled))
-                return -ENODEV;
-
         if (FTRACE_WARN_ON(ops == &global_ops))
                 return -EINVAL;
 
@@ -428,9 +425,6 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
 {
         int ret;
 
-        if (ftrace_disabled)
-                return -ENODEV;
-
         if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
                 return -EBUSY;
 
@@ -2088,10 +2082,15 @@ static void ftrace_startup_enable(int command)
 static int ftrace_startup(struct ftrace_ops *ops, int command)
 {
         bool hash_enable = true;
+        int ret;
 
         if (unlikely(ftrace_disabled))
                 return -ENODEV;
 
+        ret = __register_ftrace_function(ops);
+        if (ret)
+                return ret;
+
         ftrace_start_up++;
         command |= FTRACE_UPDATE_CALLS;
 
@@ -2113,12 +2112,17 @@ static int ftrace_startup(struct ftrace_ops *ops, int command)
         return 0;
 }
 
-static void ftrace_shutdown(struct ftrace_ops *ops, int command)
+static int ftrace_shutdown(struct ftrace_ops *ops, int command)
 {
         bool hash_disable = true;
+        int ret;
 
         if (unlikely(ftrace_disabled))
-                return;
+                return -ENODEV;
+
+        ret = __unregister_ftrace_function(ops);
+        if (ret)
+                return ret;
 
         ftrace_start_up--;
         /*
@@ -2153,9 +2157,10 @@ static void ftrace_shutdown(struct ftrace_ops *ops, int command)
         }
 
         if (!command || !ftrace_enabled)
-                return;
+                return 0;
 
         ftrace_run_update_code(command);
+        return 0;
 }
 
 static void ftrace_startup_sysctl(void)
@@ -3060,16 +3065,13 @@ static void __enable_ftrace_function_probe(void)
         if (i == FTRACE_FUNC_HASHSIZE)
                 return;
 
-        ret = __register_ftrace_function(&trace_probe_ops);
-        if (!ret)
-                ret = ftrace_startup(&trace_probe_ops, 0);
+        ret = ftrace_startup(&trace_probe_ops, 0);
 
         ftrace_probe_registered = 1;
 }
 
 static void __disable_ftrace_function_probe(void)
 {
-        int ret;
         int i;
 
         if (!ftrace_probe_registered)
@@ -3082,9 +3084,7 @@ static void __disable_ftrace_function_probe(void)
         }
 
         /* no more funcs left */
-        ret = __unregister_ftrace_function(&trace_probe_ops);
-        if (!ret)
-                ftrace_shutdown(&trace_probe_ops, 0);
+        ftrace_shutdown(&trace_probe_ops, 0);
 
         ftrace_probe_registered = 0;
 }
@@ -4366,12 +4366,15 @@ core_initcall(ftrace_nodyn_init);
 static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
 static inline void ftrace_startup_enable(int command) { }
 /* Keep as macros so we do not need to define the commands */
-# define ftrace_startup(ops, command)                   \
-        ({                                              \
-                (ops)->flags |= FTRACE_OPS_FL_ENABLED;  \
-                0;                                      \
+# define ftrace_startup(ops, command)                                   \
+        ({                                                              \
+                int ___ret = __register_ftrace_function(ops);           \
+                if (!___ret)                                            \
+                        (ops)->flags |= FTRACE_OPS_FL_ENABLED;          \
+                ___ret;                                                 \
         })
-# define ftrace_shutdown(ops, command)  do { } while (0)
+# define ftrace_shutdown(ops, command) __unregister_ftrace_function(ops)
+
 # define ftrace_startup_sysctl()        do { } while (0)
 # define ftrace_shutdown_sysctl()       do { } while (0)
 
@@ -4780,9 +4783,7 @@ int register_ftrace_function(struct ftrace_ops *ops)
 
         mutex_lock(&ftrace_lock);
 
-        ret = __register_ftrace_function(ops);
-        if (!ret)
-                ret = ftrace_startup(ops, 0);
+        ret = ftrace_startup(ops, 0);
 
         mutex_unlock(&ftrace_lock);
 
@@ -4801,9 +4802,7 @@ int unregister_ftrace_function(struct ftrace_ops *ops)
         int ret;
 
         mutex_lock(&ftrace_lock);
-        ret = __unregister_ftrace_function(ops);
-        if (!ret)
-                ftrace_shutdown(ops, 0);
+        ret = ftrace_shutdown(ops, 0);
         mutex_unlock(&ftrace_lock);
 
         return ret;
@@ -4997,6 +4996,13 @@ ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
         return NOTIFY_DONE;
 }
 
+/* Just a place holder for function graph */
+static struct ftrace_ops fgraph_ops __read_mostly = {
+        .func           = ftrace_stub,
+        .flags          = FTRACE_OPS_FL_STUB | FTRACE_OPS_FL_GLOBAL |
+                                FTRACE_OPS_FL_RECURSION_SAFE,
+};
+
 int register_ftrace_graph(trace_func_graph_ret_t retfunc,
                         trace_func_graph_ent_t entryfunc)
 {
@@ -5023,7 +5029,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
         ftrace_graph_return = retfunc;
         ftrace_graph_entry = entryfunc;
 
-        ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
+        ret = ftrace_startup(&fgraph_ops, FTRACE_START_FUNC_RET);
 
 out:
         mutex_unlock(&ftrace_lock);
@@ -5040,7 +5046,7 @@ void unregister_ftrace_graph(void)
         ftrace_graph_active--;
         ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
         ftrace_graph_entry = ftrace_graph_entry_stub;
-        ftrace_shutdown(&global_ops, FTRACE_STOP_FUNC_RET);
+        ftrace_shutdown(&fgraph_ops, FTRACE_STOP_FUNC_RET);
         unregister_pm_notifier(&ftrace_suspend_notifier);
         unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);