VBI_OPEN
if (bktr->vbiflags & VBI_OPEN) /* device is busy */
bktr->vbiflags |= VBI_OPEN;
bktr->vbiflags &= ~VBI_OPEN;
if ((bktr->vbiflags & VBI_OPEN)
&&(bktr->vbiflags & VBI_OPEN)