--- 0afddc21b69673ac1034ecc94f3914fa86ccf59e
+++ 0cccb6c460da74d4f8e03214002baf41b8577ca9
@@ -369,18 +369,11 @@ static int function_stat_show(struct seq
 {
 	struct ftrace_profile *rec = v;
 	char str[KSYM_SYMBOL_LEN];
-	int ret = 0;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	static DEFINE_MUTEX(mutex);
 	static struct trace_seq s;
 	unsigned long long avg;
 #endif
-	mutex_lock(&ftrace_profile_lock);
-
-	/* we raced with function_profile_reset() */
-	if (unlikely(rec->counter == 0)) {
-		ret = -EBUSY;
-		goto out;
-	}
 
 	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
 	seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);
@@ -390,17 +383,17 @@ static int function_stat_show(struct seq
 	avg = rec->time;
 	do_div(avg, rec->counter);
 
+	mutex_lock(&mutex);
 	trace_seq_init(&s);
 	trace_print_graph_duration(rec->time, &s);
 	trace_seq_puts(&s, "    ");
 	trace_print_graph_duration(avg, &s);
 	trace_print_seq(m, &s);
+	mutex_unlock(&mutex);
 #endif
 	seq_putc(m, '\n');
-out:
-	mutex_unlock(&ftrace_profile_lock);
 
-	return ret;
+	return 0;
 }
 
 static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
@@ -1480,8 +1473,6 @@ static void *t_start(struct seq_file *m,
 		if (*pos > 0)
 			return t_hash_start(m, pos);
 		iter->flags |= FTRACE_ITER_PRINTALL;
-		/* reset in case of seek/pread */
-		iter->flags &= ~FTRACE_ITER_HASH;
 		return iter;
 	}
 
@@ -2402,7 +2393,7 @@ static const struct file_operations ftra
 	.open = ftrace_filter_open,
 	.read = seq_read,
 	.write = ftrace_filter_write,
-	.llseek = no_llseek,
+	.llseek = ftrace_regex_lseek,
 	.release = ftrace_filter_release,
 };
 
@@ -3172,7 +3163,7 @@ static int start_graph_tracing(void)
 	/* The cpu_boot init_task->ret_stack will never be freed */
 	for_each_online_cpu(cpu) {
 		if (!idle_task(cpu)->ret_stack)
-			ftrace_graph_init_idle_task(idle_task(cpu), cpu);
+			ftrace_graph_init_task(idle_task(cpu));
 	}
 
 	do {
@@ -3262,49 +3253,6 @@ void unregister_ftrace_graph(void)
 	mutex_unlock(&ftrace_lock);
 }
 
-static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);
-
-static void
-graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
-{
-	atomic_set(&t->tracing_graph_pause, 0);
-	atomic_set(&t->trace_overrun, 0);
-	t->ftrace_timestamp = 0;
-	/* make curr_ret_stack visable before we add the ret_stack */
-	smp_wmb();
-	t->ret_stack = ret_stack;
-}
-
-/*
- * Allocate a return stack for the idle task. May be the first
- * time through, or it may be done by CPU hotplug online.
- */
-void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
-{
-	t->curr_ret_stack = -1;
-	/*
-	 * The idle task has no parent, it either has its own
-	 * stack or no stack at all.
-	 */
-	if (t->ret_stack)
-		WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));
-
-	if (ftrace_graph_active) {
-		struct ftrace_ret_stack *ret_stack;
-
-		ret_stack = per_cpu(idle_ret_stack, cpu);
-		if (!ret_stack) {
-			ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
-					    * sizeof(struct ftrace_ret_stack),
-					    GFP_KERNEL);
-			if (!ret_stack)
-				return;
-			per_cpu(idle_ret_stack, cpu) = ret_stack;
-		}
-		graph_init_task(t, ret_stack);
-	}
-}
-
 /* Allocate a return stack for newly created task */
 void ftrace_graph_init_task(struct task_struct *t)
 {
@@ -3320,7 +3268,12 @@ void ftrace_graph_init_task(struct task_
 				GFP_KERNEL);
 		if (!ret_stack)
 			return;
-		graph_init_task(t, ret_stack);
+		atomic_set(&t->tracing_graph_pause, 0);
+		atomic_set(&t->trace_overrun, 0);
+		t->ftrace_timestamp = 0;
+		/* make curr_ret_stack visable before we add the ret_stack */
+		smp_wmb();
+		t->ret_stack = ret_stack;
 	}
 }