function-graph: use int instead of atomic for ftrace_graph_active

Impact: cleanup

The variable ftrace_graph_active is only modified under the
ftrace_lock mutex, thus an atomic is not necessary for modification.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6ea5a1ae6a98764b0a49c2f37e075e0c89c3c47d..8e6a0b5c99405862963d8fbac3ce3c79fffc943e 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3092,7 +3092,7 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
-static atomic_t ftrace_graph_active;
+static int ftrace_graph_active;
 static struct notifier_block ftrace_suspend_notifier;
 
 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
@@ -3244,7 +3244,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
        mutex_lock(&ftrace_lock);
 
        /* we currently allow only one tracer registered at a time */
-       if (atomic_read(&ftrace_graph_active)) {
+       if (ftrace_graph_active) {
                ret = -EBUSY;
                goto out;
        }
@@ -3252,10 +3252,10 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
        ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
        register_pm_notifier(&ftrace_suspend_notifier);
 
-       atomic_inc(&ftrace_graph_active);
+       ftrace_graph_active++;
        ret = start_graph_tracing();
        if (ret) {
-               atomic_dec(&ftrace_graph_active);
+               ftrace_graph_active--;
                goto out;
        }
 
@@ -3273,10 +3273,10 @@ void unregister_ftrace_graph(void)
 {
        mutex_lock(&ftrace_lock);
 
-       if (!unlikely(atomic_read(&ftrace_graph_active)))
+       if (unlikely(!ftrace_graph_active))
                goto out;
 
-       atomic_dec(&ftrace_graph_active);
+       ftrace_graph_active--;
        unregister_trace_sched_switch(ftrace_graph_probe_sched_switch);
        ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
        ftrace_graph_entry = ftrace_graph_entry_stub;
@@ -3290,7 +3290,7 @@ void unregister_ftrace_graph(void)
 /* Allocate a return stack for newly created task */
 void ftrace_graph_init_task(struct task_struct *t)
 {
-       if (atomic_read(&ftrace_graph_active)) {
+       if (ftrace_graph_active) {
                t->ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
                                * sizeof(struct ftrace_ret_stack),
                                GFP_KERNEL);