SSB_STOP
atomic_clear_int(&so2->so_snd.ssb_flags, SSB_STOP);
atomic_set_int(&so->so_snd.ssb_flags, SSB_STOP);
#define SSB_CLEAR_MASK (SSB_ASYNC | SSB_UPCALL | SSB_STOP | \
if (ssb->ssb_flags & SSB_STOP)
if (ssb->ssb_flags & SSB_STOP)