function trace(entry_p) {
   if(tid() in trace)
       printf("%s%s%s\n",thread_indent(entry_p),
		       	 (entry_p>0?"->":"<-"),
		         probefunc())
}

global trace
probe kernel.function(@1).call {
   if (execname() == "staprun") next # skip our own helper process
   trace[tid()] = 1
   trace(1)
}
probe kernel.function(@1).return {
   trace(-1)
   delete trace[tid()]
}

probe kernel.function(@2).call { trace(1) }
probe kernel.function(@2).return { trace(-1) }