nl_buf_alloc
copy = nl_buf_alloc(nb->buflen, M_NOWAIT);
nb = nl_buf_alloc(len, M_WAITOK);
new = nl_buf_alloc(new_len, nw->malloc_flag | M_ZERO);
nw->buf = nl_buf_alloc(len, mflag);
struct nl_buf *nl_buf_alloc(size_t len, int mflag);