retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
if (retval >= 0)
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
if (retval >= 0)
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));