michael@0: /*-
michael@0:  * Copyright (c) 1982, 1986, 1988, 1993
michael@0:  *      The Regents of the University of California.
michael@0:  * All rights reserved.
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  * 3. Neither the name of the University nor the names of its contributors
michael@0:  *    may be used to endorse or promote products derived from this software
michael@0:  *    without specific prior written permission.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
michael@0:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
michael@0:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
michael@0:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
michael@0:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
michael@0:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
michael@0:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
michael@0:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
michael@0:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
michael@0:  * SUCH DAMAGE.
michael@0:  *
michael@0:  */
michael@0: 
michael@0: #ifndef _USER_MBUF_H_
michael@0: #define _USER_MBUF_H_
michael@0: 
michael@0: /* __Userspace__ header file for mbufs */
michael@0: #include <stdio.h>
michael@0: #if !defined(SCTP_SIMPLE_ALLOCATOR)
michael@0: #include "umem.h"
michael@0: #endif
michael@0: #include "user_malloc.h"
michael@0: #include "netinet/sctp_os_userspace.h"
michael@0: 
michael@0: #define USING_MBUF_CONSTRUCTOR 0
michael@0: 
michael@0: /* For Linux */
michael@0: #ifndef MSIZE
michael@0: #define MSIZE 256
michael@0: /* #define MSIZE 1024 */
michael@0: #endif
michael@0: #ifndef MCLBYTES
michael@0: #define MCLBYTES 2048
michael@0: #endif
michael@0: 
michael@0: struct mbuf * m_gethdr(int how, short type);
michael@0: struct mbuf * m_get(int how, short type);
michael@0: struct mbuf * m_free(struct mbuf *m);
michael@0: void m_clget(struct mbuf *m, int how);
michael@0: 
michael@0: 
michael@0: /* mbuf initialization function */
michael@0: void mbuf_init(void *);
michael@0: 
michael@0: #define	M_MOVE_PKTHDR(to, from)	m_move_pkthdr((to), (from))
michael@0: #define	MGET(m, how, type)	((m) = m_get((how), (type)))
michael@0: #define	MGETHDR(m, how, type)	((m) = m_gethdr((how), (type)))
michael@0: #define	MCLGET(m, how)		m_clget((m), (how))
michael@0: 
michael@0: 
michael@0: #define M_HDR_PAD ((sizeof(intptr_t)==4) ? 2 : 6) /* modified for __Userspace__ */
michael@0: 
michael@0: /* Length to m_copy to copy all. */
michael@0: #define	M_COPYALL	1000000000
michael@0: 
michael@0: /* umem_cache_t is defined in user_include/umem.h as
michael@0:  * typedef struct umem_cache umem_cache_t;
michael@0:  * Note:umem_zone_t is a pointer.
michael@0:  */
michael@0: #if defined(SCTP_SIMPLE_ALLOCATOR)
michael@0: typedef size_t sctp_zone_t;
michael@0: #else
michael@0: typedef umem_cache_t *sctp_zone_t;
michael@0: #endif
michael@0: 
michael@0: extern sctp_zone_t zone_mbuf;
michael@0: extern sctp_zone_t zone_clust;
michael@0: extern sctp_zone_t zone_ext_refcnt;
michael@0: 
michael@0: /*-
michael@0:  * Macros for type conversion:
michael@0:  * mtod(m, t)	-- Convert mbuf pointer to data pointer of correct type.
michael@0:  * dtom(x)	-- Convert data pointer within mbuf to mbuf pointer (XXX).
michael@0:  */
michael@0: #define	mtod(m, t)	((t)((m)->m_data))
michael@0: #define	dtom(x)		((struct mbuf *)((intptr_t)(x) & ~(MSIZE-1)))
michael@0: 
michael@0: struct mb_args {
michael@0: 	int	flags;	/* Flags for mbuf being allocated */
michael@0: 	short	type;	/* Type of mbuf being allocated */
michael@0: };
michael@0: 
michael@0: struct clust_args {
michael@0: 	struct mbuf * parent_mbuf;
michael@0: };
michael@0: 
michael@0: struct mbuf *    m_split(struct mbuf *, int, int);
michael@0: void             m_cat(struct mbuf *m, struct mbuf *n);
michael@0: void		 m_adj(struct mbuf *, int);
michael@0: void  mb_free_ext(struct mbuf *);
michael@0: void  m_freem(struct mbuf *);
michael@0: struct m_tag	*m_tag_alloc(u_int32_t, int, int, int);
michael@0: struct mbuf	*m_copym(struct mbuf *, int, int, int);
michael@0: void		 m_copyback(struct mbuf *, int, int, caddr_t);
michael@0: struct mbuf	*m_pullup(struct mbuf *, int);
michael@0: struct mbuf	*m_pulldown(struct mbuf *, int off, int len, int *offp);
michael@0: int		 m_dup_pkthdr(struct mbuf *, struct mbuf *, int);
michael@0: struct m_tag	*m_tag_copy(struct m_tag *, int);
michael@0: int		 m_tag_copy_chain(struct mbuf *, struct mbuf *, int);
michael@0: struct mbuf	*m_prepend(struct mbuf *, int, int);
michael@0: void		 m_copydata(const struct mbuf *, int, int, caddr_t);
michael@0: 
michael@0: #define MBUF_MEM_NAME "mbuf"
michael@0: #define MBUF_CLUSTER_MEM_NAME "mbuf_cluster"
michael@0: #define	MBUF_EXTREFCNT_MEM_NAME	"mbuf_ext_refcnt"
michael@0: 
michael@0: #define	MT_NOINIT	255	/* Not a type but a flag to allocate
michael@0: 				   a non-initialized mbuf */
michael@0: 
michael@0: /*
michael@0:  * General mbuf allocator statistics structure.
michael@0:  * __Userspace__ mbstat may be useful for gathering statistics.
michael@0:  * In the kernel many of these statistics are no longer used as
michael@0:  * they track allocator statistics through kernel UMA's built in statistics mechanism.
michael@0:  */
michael@0: struct mbstat {
michael@0: 	u_long	m_mbufs;	/* XXX */
michael@0: 	u_long	m_mclusts;	/* XXX */
michael@0: 
michael@0: 	u_long	m_drain;	/* times drained protocols for space */
michael@0: 	u_long	m_mcfail;	/* XXX: times m_copym failed */
michael@0: 	u_long	m_mpfail;	/* XXX: times m_pullup failed */
michael@0: 	u_long	m_msize;	/* length of an mbuf */
michael@0: 	u_long	m_mclbytes;	/* length of an mbuf cluster */
michael@0: 	u_long	m_minclsize;	/* min length of data to allocate a cluster */
michael@0: 	u_long	m_mlen;		/* length of data in an mbuf */
michael@0: 	u_long	m_mhlen;	/* length of data in a header mbuf */
michael@0: 
michael@0: 	/* Number of mbtypes (gives # elems in mbtypes[] array: */
michael@0: 	short	m_numtypes;
michael@0: 
michael@0: 	/* XXX: Sendfile stats should eventually move to their own struct */
michael@0: 	u_long	sf_iocnt;	/* times sendfile had to do disk I/O */
michael@0: 	u_long	sf_allocfail;	/* times sfbuf allocation failed */
michael@0: 	u_long	sf_allocwait;	/* times sfbuf allocation had to wait */
michael@0: };
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Mbufs are of a single size, MSIZE (sys/param.h), which includes overhead.
michael@0:  * An mbuf may add a single "mbuf cluster" of size MCLBYTES (also in
michael@0:  * sys/param.h), which has no additional overhead and is used instead of the
michael@0:  * internal data area; this is done when at least MINCLSIZE of data must be
michael@0:  * stored.  Additionally, it is possible to allocate a separate buffer
michael@0:  * externally and attach it to the mbuf in a way similar to that of mbuf
michael@0:  * clusters.
michael@0:  */
michael@0: #define	MLEN		((int)(MSIZE - sizeof(struct m_hdr)))	/* normal data len */
michael@0: #define	MHLEN		((int)(MLEN - sizeof(struct pkthdr)))	/* data len w/pkthdr */
michael@0: #define	MINCLSIZE	((int)(MHLEN + 1))	/* smallest amount to put in cluster */
michael@0: #define	M_MAXCOMPRESS	(MHLEN / 2)	/* max amount to copy for compression */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Header present at the beginning of every mbuf.
michael@0:  */
michael@0: struct m_hdr {
michael@0: 	struct mbuf	*mh_next;	/* next buffer in chain */
michael@0: 	struct mbuf	*mh_nextpkt;	/* next chain in queue/record */
michael@0: 	caddr_t		 mh_data;	/* location of data */
michael@0: 	int		 mh_len;	/* amount of data in this mbuf */
michael@0: 	int		 mh_flags;	/* flags; see below */
michael@0: 	short		 mh_type;	/* type of data in this mbuf */
michael@0: 	uint8_t          pad[M_HDR_PAD];/* word align                  */
michael@0: };
michael@0: 
michael@0: /*
michael@0:  * Packet tag structure (see below for details).
michael@0:  */
michael@0: struct m_tag {
michael@0: 	SLIST_ENTRY(m_tag)	m_tag_link;	/* List of packet tags */
michael@0: 	u_int16_t		m_tag_id;	/* Tag ID */
michael@0: 	u_int16_t		m_tag_len;	/* Length of data */
michael@0: 	u_int32_t		m_tag_cookie;	/* ABI/Module ID */
michael@0: 	void			(*m_tag_free)(struct m_tag *);
michael@0: };
michael@0: 
michael@0: /*
michael@0:  * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
michael@0:  */
michael@0: struct pkthdr {
michael@0: 	struct ifnet	*rcvif;		/* rcv interface */
michael@0: 	/* variables for ip and tcp reassembly */
michael@0: 	void		*header;	/* pointer to packet header */
michael@0: 	int		 len;		/* total packet length */
michael@0: 	/* variables for hardware checksum */
michael@0: 	int		 csum_flags;	/* flags regarding checksum */
michael@0: 	int		 csum_data;	/* data field used by csum routines */
michael@0: 	u_int16_t	 tso_segsz;	/* TSO segment size */
michael@0: 	u_int16_t	 ether_vtag;	/* Ethernet 802.1p+q vlan tag */
michael@0: 	SLIST_HEAD(packet_tags, m_tag) tags; /* list of packet tags */
michael@0: };
michael@0: 
michael@0: /*
michael@0:  * Description of external storage mapped into mbuf; valid only if M_EXT is
michael@0:  * set.
michael@0:  */
michael@0: struct m_ext {
michael@0: 	caddr_t		 ext_buf;	/* start of buffer */
michael@0: 	void		(*ext_free)	/* free routine if not the usual */
michael@0: 			    (void *, void *);
michael@0: 	void		*ext_args;	/* optional argument pointer */
michael@0: 	u_int		 ext_size;	/* size of buffer, for ext_free */
michael@0: 	volatile u_int	*ref_cnt;	/* pointer to ref count info */
michael@0: 	int		 ext_type;	/* type of external storage */
michael@0: };
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * The core of the mbuf object along with some shortcut defined for practical
michael@0:  * purposes.
michael@0:  */
michael@0: struct mbuf {
michael@0: 	struct m_hdr	m_hdr;
michael@0: 	union {
michael@0: 		struct {
michael@0: 			struct pkthdr	MH_pkthdr;	/* M_PKTHDR set */
michael@0: 			union {
michael@0: 				struct m_ext	MH_ext;	/* M_EXT set */
michael@0: 				char		MH_databuf[MHLEN];
michael@0: 			} MH_dat;
michael@0: 		} MH;
michael@0: 		char	M_databuf[MLEN];		/* !M_PKTHDR, !M_EXT */
michael@0: 	} M_dat;
michael@0: };
michael@0: 
michael@0: #define	m_next		m_hdr.mh_next
michael@0: #define	m_len		m_hdr.mh_len
michael@0: #define	m_data		m_hdr.mh_data
michael@0: #define	m_type		m_hdr.mh_type
michael@0: #define	m_flags		m_hdr.mh_flags
michael@0: #define	m_nextpkt	m_hdr.mh_nextpkt
michael@0: #define	m_act		m_nextpkt
michael@0: #define	m_pkthdr	M_dat.MH.MH_pkthdr
michael@0: #define	m_ext		M_dat.MH.MH_dat.MH_ext
michael@0: #define	m_pktdat	M_dat.MH.MH_dat.MH_databuf
michael@0: #define	m_dat		M_dat.M_databuf
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * mbuf flags.
michael@0:  */
michael@0: #define	M_EXT		0x0001	/* has associated external storage */
michael@0: #define	M_PKTHDR	0x0002	/* start of record */
michael@0: #define	M_EOR		0x0004	/* end of record */
michael@0: #define	M_RDONLY	0x0008	/* associated data is marked read-only */
michael@0: #define	M_PROTO1	0x0010	/* protocol-specific */
michael@0: #define	M_PROTO2	0x0020	/* protocol-specific */
michael@0: #define	M_PROTO3	0x0040	/* protocol-specific */
michael@0: #define	M_PROTO4	0x0080	/* protocol-specific */
michael@0: #define	M_PROTO5	0x0100	/* protocol-specific */
michael@0: #define	M_SKIP_FIREWALL	0x4000	/* skip firewall processing */
michael@0: #define	M_FREELIST	0x8000	/* mbuf is on the free list */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Flags copied when copying m_pkthdr.
michael@0:  */
michael@0: #define	M_COPYFLAGS	(M_PKTHDR|M_EOR|M_RDONLY|M_PROTO1|M_PROTO1|M_PROTO2|\
michael@0: 			    M_PROTO3|M_PROTO4|M_PROTO5|M_SKIP_FIREWALL|\
michael@0: 			    M_BCAST|M_MCAST|M_FRAG|M_FIRSTFRAG|M_LASTFRAG|\
michael@0: 			    M_VLANTAG|M_PROMISC)
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * mbuf pkthdr flags (also stored in m_flags).
michael@0:  */
michael@0: #define	M_BCAST		0x0200	/* send/received as link-level broadcast */
michael@0: #define	M_MCAST		0x0400	/* send/received as link-level multicast */
michael@0: #define	M_FRAG		0x0800	/* packet is a fragment of a larger packet */
michael@0: #define	M_FIRSTFRAG	0x1000	/* packet is first fragment */
michael@0: #define	M_LASTFRAG	0x2000	/* packet is last fragment */
michael@0: #define	M_VLANTAG	0x10000	/* ether_vtag is valid */
michael@0: #define	M_PROMISC	0x20000	/* packet was not for us */
michael@0: #define	M_NOFREE	0x40000	/* do not free mbuf - it is embedded in the cluster */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * External buffer types: identify ext_buf type.
michael@0:  */
michael@0: #define	EXT_CLUSTER	1	/* mbuf cluster */
michael@0: #define	EXT_SFBUF	2	/* sendfile(2)'s sf_bufs */
michael@0: #define	EXT_JUMBOP	3	/* jumbo cluster 4096 bytes */
michael@0: #define	EXT_JUMBO9	4	/* jumbo cluster 9216 bytes */
michael@0: #define	EXT_JUMBO16	5	/* jumbo cluster 16184 bytes */
michael@0: #define	EXT_PACKET	6	/* mbuf+cluster from packet zone */
michael@0: #define	EXT_MBUF	7	/* external mbuf reference (M_IOVEC) */
michael@0: #define	EXT_NET_DRV	100	/* custom ext_buf provided by net driver(s) */
michael@0: #define	EXT_MOD_TYPE	200	/* custom module's ext_buf type */
michael@0: #define	EXT_DISPOSABLE	300	/* can throw this buffer away w/page flipping */
michael@0: #define	EXT_EXTREF	400	/* has externally maintained ref_cnt ptr */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * mbuf types.
michael@0:  */
michael@0: #define	MT_NOTMBUF	0	/* USED INTERNALLY ONLY! Object is not mbuf */
michael@0: #define	MT_DATA		1	/* dynamic (data) allocation */
michael@0: #define	MT_HEADER	MT_DATA	/* packet header, use M_PKTHDR instead */
michael@0: #define	MT_SONAME	8	/* socket name */
michael@0: #define	MT_CONTROL	14	/* extra-data protocol message */
michael@0: #define	MT_OOBDATA	15	/* expedited data  */
michael@0: #define	MT_NTYPES	16	/* number of mbuf types for mbtypes[] */
michael@0: 
michael@0: #define	MT_NOINIT	255	/* Not a type but a flag to allocate
michael@0: 				   a non-initialized mbuf */
michael@0: 
michael@0: /*
michael@0:  * __Userspace__ flags like M_NOWAIT are defined in malloc.h
michael@0:  * Flags like these are used in functions like uma_zalloc()
michael@0:  * but don't have an equivalent in userland umem
michael@0:  * Flags specifying how an allocation should be made.
michael@0:  *
michael@0:  * The flag to use is as follows:
michael@0:  * - M_DONTWAIT or M_NOWAIT from an interrupt handler to not block allocation.
michael@0:  * - M_WAIT or M_WAITOK or M_TRYWAIT from wherever it is safe to block.
michael@0:  *
michael@0:  * M_DONTWAIT/M_NOWAIT means that we will not block the thread explicitly and
michael@0:  * if we cannot allocate immediately we may return NULL, whereas
michael@0:  * M_WAIT/M_WAITOK/M_TRYWAIT means that if we cannot allocate resources we
michael@0:  * will block until they are available, and thus never return NULL.
michael@0:  *
michael@0:  * XXX Eventually just phase this out to use M_WAITOK/M_NOWAIT.
michael@0:  */
michael@0: #define	MBTOM(how)	(how)
michael@0: 
michael@0: void		 m_tag_delete(struct mbuf *, struct m_tag *);
michael@0: void		 m_tag_delete_chain(struct mbuf *, struct m_tag *);
michael@0: void		 m_move_pkthdr(struct mbuf *, struct mbuf *);
michael@0: void		 m_tag_free_default(struct m_tag *);
michael@0: 
michael@0: extern int max_linkhdr;    /* Largest link-level header */
michael@0: extern int max_protohdr; /* Size of largest protocol layer header. See user_mbuf.c */
michael@0: 
michael@0: extern struct mbstat	mbstat;		/* General mbuf stats/infos */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Evaluate TRUE if it's safe to write to the mbuf m's data region (this can
michael@0:  * be both the local data payload, or an external buffer area, depending on
michael@0:  * whether M_EXT is set).
michael@0:  */
michael@0: #define	M_WRITABLE(m)	(!((m)->m_flags & M_RDONLY) &&			\
michael@0: 			 (!(((m)->m_flags & M_EXT)) ||			\
michael@0: 			 (*((m)->m_ext.ref_cnt) == 1)) )		\
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Compute the amount of space available before the current start of data in
michael@0:  * an mbuf.
michael@0:  *
michael@0:  * The M_WRITABLE() is a temporary, conservative safety measure: the burden
michael@0:  * of checking writability of the mbuf data area rests solely with the caller.
michael@0:  */
michael@0: #define	M_LEADINGSPACE(m)						\
michael@0: 	((m)->m_flags & M_EXT ?						\
michael@0: 	    (M_WRITABLE(m) ? (m)->m_data - (m)->m_ext.ext_buf : 0):	\
michael@0: 	    (m)->m_flags & M_PKTHDR ? (m)->m_data - (m)->m_pktdat :	\
michael@0: 	    (m)->m_data - (m)->m_dat)
michael@0: 
michael@0: /*
michael@0:  * Compute the amount of space available after the end of data in an mbuf.
michael@0:  *
michael@0:  * The M_WRITABLE() is a temporary, conservative safety measure: the burden
michael@0:  * of checking writability of the mbuf data area rests solely with the caller.
michael@0:  */
michael@0: #define	M_TRAILINGSPACE(m)						\
michael@0: 	((m)->m_flags & M_EXT ?						\
michael@0: 	    (M_WRITABLE(m) ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size	\
michael@0: 		- ((m)->m_data + (m)->m_len) : 0) :			\
michael@0: 	    &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len))
michael@0: 
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Arrange to prepend space of size plen to mbuf m.  If a new mbuf must be
michael@0:  * allocated, how specifies whether to wait.  If the allocation fails, the
michael@0:  * original mbuf chain is freed and m is set to NULL.
michael@0:  */
michael@0: #define	M_PREPEND(m, plen, how) do {					\
michael@0: 	struct mbuf **_mmp = &(m);					\
michael@0: 	struct mbuf *_mm = *_mmp;					\
michael@0: 	int _mplen = (plen);						\
michael@0: 	int __mhow = (how);						\
michael@0: 									\
michael@0: 	if (M_LEADINGSPACE(_mm) >= _mplen) {				\
michael@0: 		_mm->m_data -= _mplen;					\
michael@0: 		_mm->m_len += _mplen;					\
michael@0: 	} else								\
michael@0: 		_mm = m_prepend(_mm, _mplen, __mhow);			\
michael@0: 	if (_mm != NULL && _mm->m_flags & M_PKTHDR)			\
michael@0: 		_mm->m_pkthdr.len += _mplen;				\
michael@0: 	*_mmp = _mm;							\
michael@0: } while (0)
michael@0: 
michael@0: /*
michael@0:  * Set the m_data pointer of a newly-allocated mbuf (m_get/MGET) to place an
michael@0:  * object of the specified size at the end of the mbuf, longword aligned.
michael@0:  */
michael@0: #define	M_ALIGN(m, len) do {						\
michael@0:         KASSERT(!((m)->m_flags & (M_PKTHDR|M_EXT)),                     \
michael@0:                 ("%s: M_ALIGN not normal mbuf", __func__));             \
michael@0:         KASSERT((m)->m_data == (m)->m_dat,                              \
michael@0:                 ("%s: M_ALIGN not a virgin mbuf", __func__));           \
michael@0: 	(m)->m_data += (MLEN - (len)) & ~(sizeof(long) - 1);		\
michael@0: } while (0)
michael@0: 
michael@0: /*
michael@0:  * As above, for mbufs allocated with m_gethdr/MGETHDR or initialized by
michael@0:  * M_DUP/MOVE_PKTHDR.
michael@0:  */
michael@0: #define	MH_ALIGN(m, len) do {						\
michael@0:         KASSERT((m)->m_flags & M_PKTHDR && !((m)->m_flags & M_EXT),     \
michael@0:                 ("%s: MH_ALIGN not PKTHDR mbuf", __func__));            \
michael@0:         KASSERT((m)->m_data == (m)->m_pktdat,                           \
michael@0:                 ("%s: MH_ALIGN not a virgin mbuf", __func__));          \
michael@0: 	(m)->m_data += (MHLEN - (len)) & ~(sizeof(long) - 1);		\
michael@0: } while (0)
michael@0: 
michael@0: #endif