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

1 files changed, 1 insertions, 5 deletions

diff --git a/sys/netinet/sctp_os_bsd.h b/sys/netinet/sctp_os_bsd.h
index 9d5466307f50..53427ce85bc7 100644
--- a/sys/netinet/sctp_os_bsd.h
+++ b/sys/netinet/sctp_os_bsd.h
@@ -304,11 +304,7 @@ typedef struct callout sctp_os_timer_t;
 #define SCTP_BUF_RECVIF(m) (m->m_pkthdr.rcvif)
 #define SCTP_BUF_PREPEND	M_PREPEND
 
-#define SCTP_ALIGN_TO_END(m, len) if(m->m_flags & M_PKTHDR) { \
-                                     MH_ALIGN(m, len); \
-                                  } else if ((m->m_flags & M_EXT) == 0) { \
-                                     M_ALIGN(m, len); \
-                                  }
+#define SCTP_ALIGN_TO_END(m, len) M_ALIGN(m, len)
 
 /* We make it so if you have up to 4 threads
  * writing based on the default size of