unlock(&trace.lock)
			trace.cpuBuf[gen%2] = nil
		})
	}
}

// traceCPUSample writes a CPU profile sample stack to the execution tracer's
// profiling buffer. It is called from a signal handler, so is limited in what
// it can do. mp must be the thread that is currently stopped in a signal.
func traceCPUSample(gp *g, mp *m, pp *p, stk []uintptr) {
	if !traceEnabled() {