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)