tracing/ftrace: types and naming corrections for sched tracer

Impact: cleanup

This patch applies some corrections suggested by Steven Rostedt.

Change the type of shed_ref into int since it is used
into a Mutex, we don't need it anymore as an atomic
variable in the sched_switch tracer.
Also change the name of the register mutex.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 17 deletions

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 9d7bdac331dd..969953bf678f 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -16,8 +16,8 @@
 
 static struct trace_array       *ctx_trace;
 static int __read_mostly        tracer_enabled;
-static atomic_t                 sched_ref;
-static DEFINE_MUTEX(tracepoint_mutex);
+static int                      sched_ref;
+static DEFINE_MUTEX(sched_register_mutex);
 
 static void
 probe_sched_switch(struct rq *__rq, struct task_struct *prev,
@@ -28,7 +28,7 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
         int cpu;
         int pc;
 
-        if (!atomic_read(&sched_ref))
+        if (!sched_ref)
                 return;
 
         tracing_record_cmdline(prev);
@@ -124,26 +124,22 @@ static void tracing_sched_unregister(void)
 
 static void tracing_start_sched_switch(void)
 {
-        long ref;
-
-        mutex_lock(&tracepoint_mutex);
-        tracer_enabled = 1;
-        ref = atomic_inc_return(&sched_ref);
-        if (ref == 1)
+        mutex_lock(&sched_register_mutex);
+        if (!(sched_ref++)) {
+                tracer_enabled = 1;
                 tracing_sched_register();
-        mutex_unlock(&tracepoint_mutex);
+        }
+        mutex_unlock(&sched_register_mutex);
 }
 
 static void tracing_stop_sched_switch(void)
 {
-        long ref;
-
-        mutex_lock(&tracepoint_mutex);
-        tracer_enabled = 0;
-        ref = atomic_dec_and_test(&sched_ref);
-        if (ref)
+        mutex_lock(&sched_register_mutex);
+        if (!(--sched_ref)) {
                 tracing_sched_unregister();
-        mutex_unlock(&tracepoint_mutex);
+                tracer_enabled = 0;
+        }
+        mutex_unlock(&sched_register_mutex);
 }
 
 void tracing_start_cmdline_record(void)