ZT_MAGIC
__put_user_error(ZT_MAGIC, &ctx->head.magic, err);
case ZT_MAGIC:
case ZT_MAGIC:
head = get_header(head, ZT_MAGIC, GET_BUF_RESV_SIZE(context), &offset);
head = get_header(head, ZT_MAGIC, GET_BUF_RESV_SIZE(context), &offset);