ftrace: Remove global function list and call function directly

Instead of having a list of global functions that are called,
as only one global function is allow to be enabled at a time, there's
no reason to have a list.

Instead, simply have all the users of the global ops, use the global ops
directly, instead of registering their own ftrace_ops. Just switch what
function is used before enabling the function tracer.

This removes a lot of code as well as the complexity involved with it.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 16 insertions, 17 deletions

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 8ff02cbb892f..b5cb047df3e9 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -151,12 +151,6 @@ irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
 
 	atomic_dec(&data->disabled);
 }
-
-static struct ftrace_ops trace_ops __read_mostly =
-{
-	.func = irqsoff_tracer_call,
-	.flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
-};
 #endif /* CONFIG_FUNCTION_TRACER */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -531,7 +525,7 @@ void trace_preempt_off(unsigned long a0, unsigned long a1)
 }
 #endif /* CONFIG_PREEMPT_TRACER */
 
-static int register_irqsoff_function(int graph, int set)
+static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
 {
 	int ret;
 
@@ -543,7 +537,7 @@ static int register_irqsoff_function(int graph, int set)
 		ret = register_ftrace_graph(&irqsoff_graph_return,
 					    &irqsoff_graph_entry);
 	else
-		ret = register_ftrace_function(&trace_ops);
+		ret = register_ftrace_function(tr->ops);
 
 	if (!ret)
 		function_enabled = true;
@@ -551,7 +545,7 @@ static int register_irqsoff_function(int graph, int set)
 	return ret;
 }
 
-static void unregister_irqsoff_function(int graph)
+static void unregister_irqsoff_function(struct trace_array *tr, int graph)
 {
 	if (!function_enabled)
 		return;
@@ -559,17 +553,17 @@ static void unregister_irqsoff_function(int graph)
 	if (graph)
 		unregister_ftrace_graph();
 	else
-		unregister_ftrace_function(&trace_ops);
+		unregister_ftrace_function(tr->ops);
 
 	function_enabled = false;
 }
 
-static void irqsoff_function_set(int set)
+static void irqsoff_function_set(struct trace_array *tr, int set)
 {
 	if (set)
-		register_irqsoff_function(is_graph(), 1);
+		register_irqsoff_function(tr, is_graph(), 1);
 	else
-		unregister_irqsoff_function(is_graph());
+		unregister_irqsoff_function(tr, is_graph());
 }
 
 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
@@ -577,7 +571,7 @@ static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
 	struct tracer *tracer = tr->current_trace;
 
 	if (mask & TRACE_ITER_FUNCTION)
-		irqsoff_function_set(set);
+		irqsoff_function_set(tr, set);
 
 	return trace_keep_overwrite(tracer, mask, set);
 }
@@ -586,7 +580,7 @@ static int start_irqsoff_tracer(struct trace_array *tr, int graph)
 {
 	int ret;
 
-	ret = register_irqsoff_function(graph, 0);
+	ret = register_irqsoff_function(tr, graph, 0);
 
 	if (!ret && tracing_is_enabled())
 		tracer_enabled = 1;
@@ -600,7 +594,7 @@ static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
 {
 	tracer_enabled = 0;
 
-	unregister_irqsoff_function(graph);
+	unregister_irqsoff_function(tr, graph);
 }
 
 static void __irqsoff_tracer_init(struct trace_array *tr)
@@ -617,7 +611,11 @@ static void __irqsoff_tracer_init(struct trace_array *tr)
 	smp_wmb();
 	tracing_reset_online_cpus(&tr->trace_buffer);
 
-	if (start_irqsoff_tracer(tr, is_graph()))
+	ftrace_init_array_ops(tr, irqsoff_tracer_call);
+
+	/* Only toplevel instance supports graph tracing */
+	if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
+				      is_graph())))
 		printk(KERN_ERR "failed to start irqsoff tracer\n");
 }
 
@@ -630,6 +628,7 @@ static void irqsoff_tracer_reset(struct trace_array *tr)
 
 	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
+	ftrace_reset_array_ops(tr);
 }
 
 static void irqsoff_tracer_start(struct trace_array *tr)