tracing/kprobes: Fix to increment return event probe hit-count

Fix to increment probe hit-count for function return event.

Link: http://lkml.kernel.org/r/20130509054424.30398.34058.stgit@mhiramat-M0-7522

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_kprobe.c

@@ -767,6 +767,8 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
 	unsigned long irq_flags;
 	struct ftrace_event_call *call = &tp->call;
 
+	tp->nhit++;
+
 	local_save_flags(irq_flags);
 	pc = preempt_count();