FASYNC
if (error == 0 && ((nflags ^ oflags) & FASYNC)) {
tmp = nflags & FASYNC;
atomic_set_int(&fp->f_flag, FASYNC);
atomic_clear_int(&fp->f_flag, FASYNC);
fflag &= ~(FASYNC | FNONBLOCK);
tmp = fflag & FASYNC;
#define FMASK (FREAD|FWRITE|FAPPEND|FASYNC|FFSYNC|FNONBLOCK|\
#define FCNTLFLAGS (FAPPEND|FASYNC|FFSYNC|FNONBLOCK|FPOSIXSHM|\
if (fp->f_flag & FASYNC)