On Wed, Jun 13, 2018 at 01:20:29PM +0900, YASUOKA Masahiko wrote:
> > The MCLGET() cannot be called anymore. Can we remove it and add a
> > compile time assert instead?
> >
> > CTASSERT(sizeof(struct ip) + sizeof(struct tcphdr) <= MHLEN);
> > CTASSERT(sizeof(struct ip6_hdr) + sizeof(struct tcphdr) <= MHLEN);
>
> Yes, it's possible and it seems better.
>
> ok?
OK bluhm@
> Index: sys/netinet/tcp_subr.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/tcp_subr.c,v
> retrieving revision 1.171
> diff -u -p -r1.171 tcp_subr.c
> --- sys/netinet/tcp_subr.c 8 May 2018 15:10:33 -0000 1.171
> +++ sys/netinet/tcp_subr.c 13 Jun 2018 04:18:25 -0000
> @@ -191,6 +191,9 @@ tcp_template(struct tcpcb *tp)
> struct mbuf *m;
> struct tcphdr *th;
>
> + CTASSERT(sizeof(struct ip) + sizeof(struct tcphdr) <= MHLEN);
> + CTASSERT(sizeof(struct ip6_hdr) + sizeof(struct tcphdr) <= MHLEN);
> +
> if ((m = tp->t_template) == 0) {
> m = m_get(M_DONTWAIT, MT_HEADER);
> if (m == NULL)
> @@ -208,19 +211,6 @@ tcp_template(struct tcpcb *tp)
> #endif /* INET6 */
> }
> m->m_len += sizeof (struct tcphdr);
> -
> - /*
> - * The link header, network header, TCP header, and TCP options
> - * all must fit in this mbuf. For now, assume the worst case of
> - * TCP options size. Eventually, compute this from tp flags.
> - */
> - if (m->m_len + MAX_TCPOPTLEN + max_linkhdr >= MHLEN) {
> - MCLGET(m, M_DONTWAIT);
> - if ((m->m_flags & M_EXT) == 0) {
> - m_free(m);
> - return (0);
> - }
> - }
> }
>
> switch(tp->pf) {
