1 files changed, 34 insertions, 18 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 02bece4a99ea..eb11011b5292 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -98,6 +98,13 @@ struct ftrace_pid {
         struct pid *pid;
 };
 
+static bool ftrace_pids_enabled(void)
+{
+        return !list_empty(&ftrace_pids);
+}
+
+static void ftrace_update_trampoline(struct ftrace_ops *ops);
+
 /*
  * ftrace_disabled is set when an anomaly is discovered.
  * ftrace_disabled is much stronger than ftrace_enabled.
@@ -109,7 +116,6 @@ static DEFINE_MUTEX(ftrace_lock);
 static struct ftrace_ops *ftrace_control_list __read_mostly = &ftrace_list_end;
 static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
-ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
 static struct ftrace_ops global_ops;
 static struct ftrace_ops control_ops;
 
@@ -183,14 +189,7 @@ static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
         if (!test_tsk_trace_trace(current))
                 return;
 
-        ftrace_pid_function(ip, parent_ip, op, regs);
-}
-
-static void set_ftrace_pid_function(ftrace_func_t func)
-{
-        /* do not set ftrace_pid_function to itself! */
-        if (func != ftrace_pid_func)
-                ftrace_pid_function = func;
+        op->saved_func(ip, parent_ip, op, regs);
 }
 
 /**
@@ -202,7 +201,6 @@ static void set_ftrace_pid_function(ftrace_func_t func)
 void clear_ftrace_function(void)
 {
         ftrace_trace_function = ftrace_stub;
-        ftrace_pid_function = ftrace_stub;
 }
 
 static void control_ops_disable_all(struct ftrace_ops *ops)
@@ -436,6 +434,12 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
         } else
                 add_ftrace_ops(&ftrace_ops_list, ops);
 
+        /* Always save the function, and reset at unregistering */
+        ops->saved_func = ops->func;
+
+        if (ops->flags & FTRACE_OPS_FL_PID && ftrace_pids_enabled())
+                ops->func = ftrace_pid_func;
+
         ftrace_update_trampoline(ops);
 
         if (ftrace_enabled)
@@ -463,15 +467,28 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
         if (ftrace_enabled)
                 update_ftrace_function();
 
+        ops->func = ops->saved_func;
+
         return 0;
 }
 
 static void ftrace_update_pid_func(void)
 {
+        bool enabled = ftrace_pids_enabled();
+        struct ftrace_ops *op;
+
         /* Only do something if we are tracing something */
         if (ftrace_trace_function == ftrace_stub)
                 return;
 
+        do_for_each_ftrace_op(op, ftrace_ops_list) {
+                if (op->flags & FTRACE_OPS_FL_PID) {
+                        op->func = enabled ? ftrace_pid_func :
+                                op->saved_func;
+                        ftrace_update_trampoline(op);
+                }
+        } while_for_each_ftrace_op(op);
+
         update_ftrace_function();
 }
 
@@ -1133,7 +1150,8 @@ static struct ftrace_ops global_ops = {
         .local_hash.filter_hash         = EMPTY_HASH,
         INIT_OPS_HASH(global_ops)
         .flags                          = FTRACE_OPS_FL_RECURSION_SAFE |
-                                          FTRACE_OPS_FL_INITIALIZED,
+                                          FTRACE_OPS_FL_INITIALIZED |
+                                          FTRACE_OPS_FL_PID,
 };
 
 /*
@@ -5023,7 +5041,9 @@ static void ftrace_update_trampoline(struct ftrace_ops *ops)
 
 static struct ftrace_ops global_ops = {
         .func                   = ftrace_stub,
-        .flags                  = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_INITIALIZED,
+        .flags                  = FTRACE_OPS_FL_RECURSION_SAFE |
+                                  FTRACE_OPS_FL_INITIALIZED |
+                                  FTRACE_OPS_FL_PID,
 };
 
 static int __init ftrace_nodyn_init(void)
@@ -5080,11 +5100,6 @@ void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
                 if (WARN_ON(tr->ops->func != ftrace_stub))
                         printk("ftrace ops had %pS for function\n",
                                tr->ops->func);
-                /* Only the top level instance does pid tracing */
-                if (!list_empty(&ftrace_pids)) {
-                        set_ftrace_pid_function(func);
-                        func = ftrace_pid_func;
-                }
         }
         tr->ops->func = func;
         tr->ops->private = tr;
@@ -5371,7 +5386,7 @@ static void *fpid_start(struct seq_file *m, loff_t *pos)
 {
         mutex_lock(&ftrace_lock);
 
-        if (list_empty(&ftrace_pids) && (!*pos))
+        if (!ftrace_pids_enabled() && (!*pos))
                 return (void *) 1;
 
         return seq_list_start(&ftrace_pids, *pos);
@@ -5610,6 +5625,7 @@ static struct ftrace_ops graph_ops = {
         .func                   = ftrace_stub,
         .flags                  = FTRACE_OPS_FL_RECURSION_SAFE |
                                    FTRACE_OPS_FL_INITIALIZED |
+                                   FTRACE_OPS_FL_PID |
                                    FTRACE_OPS_FL_STUB,
 #ifdef FTRACE_GRAPH_TRAMP_ADDR
         .trampoline             = FTRACE_GRAPH_TRAMP_ADDR,