if b != 0 {
		// timeout signal from caller
		return -1, -1
	}
	return mp.id, gotM
}

// waitForSigusr1Callback is called from the signal handler during
// WaitForSigusr1. It must not have write barriers because there may
// not be a P.
//
//go:nowritebarrierrec
func waitForSigusr1Callback(gp *g) bool {
	if gp == nil || gp.m == nil {
		waitForSigusr1.mID = -1
	} else {
		waitForSigusr1.mID = gp.m.id
	}