readopen           18 kernel/pipe.c    int readopen;  // read fd is still open
readopen           33 kernel/pipe.c    pi->readopen = 1;
readopen           66 kernel/pipe.c      pi->readopen = 0;
readopen           69 kernel/pipe.c    if (pi->readopen == 0 && pi->writeopen == 0) {
readopen           84 kernel/pipe.c      if (pi->readopen == 0 || killed(pr)) {