To ease changes to underlying mbuf structure and the mbuf allocator, reduce

the knowledge of mbuf layout, and in particular constants such as M_EXT,
MLEN, MHLEN, and so on, in mbuf consumers by unifying various alignment
utility functions (M_ALIGN(), MH_ALIGN(), MEXT_ALIGN() in a single
M_ALIGN() macro, implemented by a now-inlined m_align() function:

- Move m_align() from uipc_mbuf.c to mbuf.h; mark as __inline.
- Reimplement M_ALIGN(), MH_ALIGN(), and MEXT_ALIGN() using m_align().
- Update consumers around the tree to simply use M_ALIGN().

This change eliminates a number of cases where mbuf consumers must be aware
of whether or not mbufs returned by the allocator use external storage, but
also assumptions about the size of the returned mbuf. This will make it
easier to introduce changes in how we use external storage, as well as
features such as variable-size mbufs.

Differential Revision:	https://reviews.freebsd.org/D1436
Reviewed by:	glebius, trasz, gnn, bz
Sponsored by:	EMC / Isilon Storage Division

3 files changed, 5 insertions, 5 deletions

diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index 74eb72ed5075..ce68381e5628 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -2940,7 +2940,7 @@ ip6_splithdr(struct mbuf *m, struct ip6_exthdrs *exthdrs)
 			return ENOBUFS;
 		}
 		m_move_pkthdr(mh, m);
-		MH_ALIGN(mh, sizeof(*ip6));
+		M_ALIGN(mh, sizeof(*ip6));
 		m->m_len -= sizeof(*ip6);
 		m->m_data += sizeof(*ip6);
 		mh->m_next = m;
diff --git a/sys/netinet6/mld6.c b/sys/netinet6/mld6.c
index 8805edac9d86..d992d57de207 100644
--- a/sys/netinet6/mld6.c
+++ b/sys/netinet6/mld6.c
@@ -1818,7 +1818,7 @@ mld_v1_transmit_report(struct in6_multi *in6m, const int type)
 	 * that ether_output() does not need to allocate another mbuf
 	 * for the header in the most common case.
 	 */
-	MH_ALIGN(mh, sizeof(struct ip6_hdr));
+	M_ALIGN(mh, sizeof(struct ip6_hdr));
 	mh->m_pkthdr.len = sizeof(struct ip6_hdr) + sizeof(struct mld_hdr);
 	mh->m_len = sizeof(struct ip6_hdr);
 
@@ -3179,7 +3179,7 @@ mld_v2_encap_report(struct ifnet *ifp, struct mbuf *m)
 		m_freem(m);
 		return (NULL);
 	}
-	MH_ALIGN(mh, sizeof(struct ip6_hdr) + sizeof(struct mldv2_report));
+	M_ALIGN(mh, sizeof(struct ip6_hdr) + sizeof(struct mldv2_report));
 
 	mldreclen = m_length(m, NULL);
 	CTR2(KTR_MLD, "%s: mldreclen is %d", __func__, mldreclen);
diff --git a/sys/netinet6/nd6_nbr.c b/sys/netinet6/nd6_nbr.c
index 39a36e875c23..4841d72eef77 100644
--- a/sys/netinet6/nd6_nbr.c
+++ b/sys/netinet6/nd6_nbr.c
@@ -431,7 +431,7 @@ nd6_ns_output(struct ifnet *ifp, const struct in6_addr *daddr6,
 
 	icmp6len = sizeof(*nd_ns);
 	m->m_pkthdr.len = m->m_len = sizeof(*ip6) + icmp6len;
-	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */
+	m->m_data += max_linkhdr;	/* or M_ALIGN() equivalent? */
 
 	/* fill neighbor solicitation packet */
 	ip6 = mtod(m, struct ip6_hdr *);
@@ -1003,7 +1003,7 @@ nd6_na_output_fib(struct ifnet *ifp, const struct in6_addr *daddr6_0,
 
 	icmp6len = sizeof(*nd_na);
 	m->m_pkthdr.len = m->m_len = sizeof(struct ip6_hdr) + icmp6len;
-	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */
+	m->m_data += max_linkhdr;	/* or M_ALIGN() equivalent? */
 
 	/* fill neighbor advertisement packet */
 	ip6 = mtod(m, struct ip6_hdr *);