FASYNC
tmp = fp->f_flag & FASYNC;
atomic_setbits_int(&fp->f_flag, FASYNC);
atomic_clearbits_int(&fp->f_flag, FASYNC);
#define FMASK (FREAD|FWRITE|FAPPEND|FASYNC|FFSYNC|FNONBLOCK)
#define FCNTLFLAGS (FAPPEND|FASYNC|FFSYNC|FNONBLOCK)
if (kf->f_flag & FASYNC)