tracing: Update *ppos instead of filp->f_pos

Instead of directly updating filp->f_pos we should update the *ppos
argument. The filp->f_pos gets updated within the file_pos_write()
function called from sys_write().

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091023233646.399670810@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 37ba67e..9c451a1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -740,7 +740,7 @@
  out:
 	mutex_unlock(&ftrace_profile_lock);
 
-	filp->f_pos += cnt;
+	*ppos += cnt;
 
 	return cnt;
 }