Merge tag 'trace-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux...
[muen/linux.git] / kernel / trace / ftrace.c
index f46dbb5cdf762b8d8162551a7e9c9671aad9e1ef..b0623ac785a22287526327a021d81fe3eaf5fafb 100644 (file)
@@ -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();
 }
 
@@ -1138,7 +1155,8 @@ 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,
 };
 
 /*
@@ -5028,7 +5046,9 @@ 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)
@@ -5085,11 +5105,6 @@ 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;
@@ -5376,7 +5391,7 @@ 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);
@@ -5615,6 +5630,7 @@ 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,