m_apply
error = m_apply(m, src_offset, src_len, cdce_m_crc32_cb, &crc);
(void) m_apply(m, src_offset, src_len, &usbd_m_copy_in_cb, &arg);
m_apply(m, doff, len, tcpsignature_apply, &ctx);
int m_apply(struct mbuf *, int, int,