mtx_lock_flags
mtx_lock_flags(_l, MTX_DUPOK); \
mtx_lock_flags(&sema_mtx[i], LOP_DUPOK);
#define mtx_lock(m) mtx_lock_flags((m), 0)
#define VI_LOCK_FLAGS(vp, flags) mtx_lock_flags(&(vp)->v_interlock, (flags))