path: root/sys/sys/mbuf.h

/*-
 * Copyright (c) 1982, 1986, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)mbuf.h	8.5 (Berkeley) 2/19/95
 * $FreeBSD$
 */

#ifndef _SYS_MBUF_H_
#define	_SYS_MBUF_H_

#include <sys/_label.h>
#include <sys/queue.h>

/*
 * Mbufs are of a single size, MSIZE (machine/param.h), which
 * includes overhead.  An mbuf may add a single "mbuf cluster" of size
 * MCLBYTES (also in machine/param.h), which has no additional overhead
 * and is used instead of the internal data area; this is done when
 * at least MINCLSIZE of data must be stored.  Additionally, it is possible
 * to allocate a separate buffer externally and attach it to the mbuf in
 * a way similar to that of mbuf clusters.
 */
#define	MLEN		(MSIZE - sizeof(struct m_hdr))	/* normal data len */
#define	MHLEN		(MLEN - sizeof(struct pkthdr))	/* data len w/pkthdr */
#define	MINCLSIZE	(MHLEN + 1)	/* smallest amount to put in cluster */
#define	M_MAXCOMPRESS	(MHLEN / 2)	/* max amount to copy for compression */

#ifdef _KERNEL
/*-
 * Macros for type conversion:
 * mtod(m, t)	-- Convert mbuf pointer to data pointer of correct type.
 * dtom(x)	-- Convert data pointer within mbuf to mbuf pointer (XXX).
 */
#define	mtod(m, t)	((t)((m)->m_data))
#define	dtom(x)		((struct mbuf *)((intptr_t)(x) & ~(MSIZE-1)))
#endif /* _KERNEL */

/*
 * Header present at the beginning of every mbuf.
 */
struct m_hdr {
	struct	mbuf *mh_next;		/* next buffer in chain */
	struct	mbuf *mh_nextpkt;	/* next chain in queue/record */
	caddr_t	mh_data;		/* location of data */
	int	mh_len;			/* amount of data in this mbuf */
	int	mh_flags;		/* flags; see below */
	short	mh_type;		/* type of data in this mbuf */
};

/*
 * Packet tag structure (see below for details).
 */
struct m_tag {
	SLIST_ENTRY(m_tag)	m_tag_link;	/* List of packet tags */
	u_int16_t		m_tag_id;	/* Tag ID */
	u_int16_t		m_tag_len;	/* Length of data */
	u_int32_t		m_tag_cookie;	/* ABI/Module ID */
};

/*
 * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
 */
struct pkthdr {
	struct	ifnet *rcvif;		/* rcv interface */
	int	len;			/* total packet length */
	/* variables for ip and tcp reassembly */
	void	*header;		/* pointer to packet header */
	/* variables for hardware checksum */
	int	csum_flags;		/* flags regarding checksum */
	int	csum_data;		/* data field used by csum routines */
	SLIST_HEAD(packet_tags, m_tag) tags; /* list of packet tags */
	struct	label label;		/* MAC label of data in packet */
};

/*
 * Description of external storage mapped into mbuf; valid only if M_EXT is set.
 */
struct m_ext {
	caddr_t	ext_buf;		/* start of buffer */
	void	(*ext_free)		/* free routine if not the usual */
		    (void *, void *);
	void	*ext_args;		/* optional argument pointer */
	u_int	ext_size;		/* size of buffer, for ext_free */
	u_int	*ref_cnt;		/* pointer to ref count info */
	int	ext_type;		/* type of external storage */
};

/*
 * The core of the mbuf object along with some shortcut defines for
 * practical purposes.
 */
struct mbuf {
	struct	m_hdr m_hdr;
	union {
		struct {
			struct	pkthdr MH_pkthdr;	/* M_PKTHDR set */
			union {
				struct	m_ext MH_ext;	/* M_EXT set */
				char	MH_databuf[MHLEN];
			} MH_dat;
		} MH;
		char	M_databuf[MLEN];		/* !M_PKTHDR, !M_EXT */
	} M_dat;
};
#define	m_next		m_hdr.mh_next
#define	m_len		m_hdr.mh_len
#define	m_data		m_hdr.mh_data
#define	m_type		m_hdr.mh_type
#define	m_flags		m_hdr.mh_flags
#define	m_nextpkt	m_hdr.mh_nextpkt
#define	m_act		m_nextpkt
#define	m_pkthdr	M_dat.MH.MH_pkthdr
#define	m_ext		M_dat.MH.MH_dat.MH_ext
#define	m_pktdat	M_dat.MH.MH_dat.MH_databuf
#define	m_dat		M_dat.M_databuf

/*
 * mbuf flags.
 */
#define	M_EXT		0x0001	/* has associated external storage */
#define	M_PKTHDR	0x0002	/* start of record */
#define	M_EOR		0x0004	/* end of record */
#define	M_RDONLY	0x0008	/* associated data is marked read-only */
#define	M_PROTO1	0x0010	/* protocol-specific */
#define	M_PROTO2	0x0020	/* protocol-specific */
#define	M_PROTO3	0x0040	/* protocol-specific */
#define	M_PROTO4	0x0080	/* protocol-specific */
#define	M_PROTO5	0x0100	/* protocol-specific */

/*
 * mbuf pkthdr flags (also stored in m_flags).
 */
#define	M_BCAST		0x0200	/* send/received as link-level broadcast */
#define	M_MCAST		0x0400	/* send/received as link-level multicast */
#define	M_FRAG		0x0800	/* packet is a fragment of a larger packet */
#define	M_FIRSTFRAG	0x1000	/* packet is first fragment */
#define	M_LASTFRAG	0x2000	/* packet is last fragment */

/*
 * External buffer types: identify ext_buf type.
 */
#define	EXT_CLUSTER	1	/* mbuf cluster */
#define	EXT_SFBUF	2	/* sendfile(2)'s sf_bufs */
#define	EXT_NET_DRV	100	/* custom ext_buf provided by net driver(s) */
#define	EXT_MOD_TYPE	200	/* custom module's ext_buf type */
#define	EXT_DISPOSABLE	300	/* can throw this buffer away w/page flipping */
#define	EXT_EXTREF	400	/* has externally maintained ref_cnt ptr*/

/*
 * Flags copied when copying m_pkthdr.
 */
#define	M_COPYFLAGS	(M_PKTHDR|M_EOR|M_RDONLY|M_PROTO1|M_PROTO1|M_PROTO2|\
			    M_PROTO3|M_PROTO4|M_PROTO5|M_BCAST|M_MCAST|\
			    M_FRAG|M_FIRSTFRAG|M_LASTFRAG)

/*
 * Flags indicating hw checksum support and sw checksum requirements.
 */
#define	CSUM_IP			0x0001		/* will csum IP */
#define	CSUM_TCP		0x0002		/* will csum TCP */
#define	CSUM_UDP		0x0004		/* will csum UDP */
#define	CSUM_IP_FRAGS		0x0008		/* will csum IP fragments */
#define	CSUM_FRAGMENT		0x0010		/* will do IP fragmentation */

#define	CSUM_IP_CHECKED		0x0100		/* did csum IP */
#define	CSUM_IP_VALID		0x0200		/*   ... the csum is valid */
#define	CSUM_DATA_VALID		0x0400		/* csum_data field is valid */
#define	CSUM_PSEUDO_HDR		0x0800		/* csum_data has pseudo hdr */

#define	CSUM_DELAY_DATA		(CSUM_TCP | CSUM_UDP)
#define	CSUM_DELAY_IP		(CSUM_IP)	/* XXX add ipv6 here too? */

/*
 * mbuf types.
 */
#define	MT_NOTMBUF	0	/* USED INTERNALLY ONLY! Object is not mbuf */
#define	MT_DATA		1	/* dynamic (data) allocation */
#define	MT_HEADER	2	/* packet header */
#if 0
#define	MT_SOCKET	3	/* socket structure */
#define	MT_PCB		4	/* protocol control block */
#define	MT_RTABLE	5	/* routing tables */
#define	MT_HTABLE	6	/* IMP host tables */
#define	MT_ATABLE	7	/* address resolution tables */
#endif
#define	MT_SONAME	8	/* socket name */
#if 0
#define	MT_SOOPTS	10	/* socket options */
#endif
#define	MT_FTABLE	11	/* fragment reassembly header */
#if 0
#define	MT_RIGHTS	12	/* access rights */
#define	MT_IFADDR	13	/* interface address */
#endif
#define	MT_TAG		13	/* volatile metadata associated to pkts */
#define	MT_CONTROL	14	/* extra-data protocol message */
#define	MT_OOBDATA	15	/* expedited data  */
#define	MT_NTYPES	16	/* number of mbuf types for mbtypes[] */

/*
 * Mbuf and cluster allocation statistics PCPU structure.
 */
struct mbpstat {
	u_long	mb_mbfree;
	u_long	mb_mbpgs;
	u_long	mb_clfree;
	u_long	mb_clpgs;
	long	mb_mbtypes[MT_NTYPES];
	short	mb_active;
};

/*
 * General mbuf allocator statistics structure.
 * XXX: Modifications of these are not protected by any mutex locks nor by
 * any atomic() manipulations.  As a result, we may occasionally lose
 * a count or two.  Luckily, not all of these fields are modified at all
 * and remain static, and those that are manipulated are only manipulated
 * in failure situations, which do not occur (hopefully) very often.
 */
struct mbstat {
	u_long	m_drops;	/* times failed to allocate */
	u_long	m_wait;		/* times succesfully returned from wait */
	u_long	m_drain;	/* times drained protocols for space */
	u_long	m_mcfail;	/* XXX: times m_copym failed */
	u_long	m_mpfail;	/* XXX: times m_pullup failed */
	u_long	m_msize;	/* length of an mbuf */
	u_long	m_mclbytes;	/* length of an mbuf cluster */
	u_long	m_minclsize;	/* min length of data to allocate a cluster */
	u_long	m_mlen;		/* length of data in an mbuf */
	u_long	m_mhlen;	/* length of data in a header mbuf */
	/* Number of mbtypes (gives # elems in mbpstat's mb_mbtypes[] array: */
	short	m_numtypes;
};

/*
 * Flags specifying how an allocation should be made.
 * M_DONTWAIT means "don't block if nothing is available" whereas
 * M_TRYWAIT means "block for mbuf_wait ticks at most if nothing is
 * available."
 */
#define	M_DONTWAIT	1
#define	M_TRYWAIT	0
#define	M_WAIT		M_TRYWAIT	/* XXX: Deprecated. */

#ifdef _KERNEL
/*-
 * mbuf external reference count management macros.
 *
 * MEXT_IS_REF(m): true if (m) is not the only mbuf referencing
 *     the external buffer ext_buf.
 *
 * MEXT_REM_REF(m): remove reference to m_ext object.
 *
 * MEXT_ADD_REF(m): add reference to m_ext object already
 *     referred to by (m).
 */
#define	MEXT_IS_REF(m)	(*((m)->m_ext.ref_cnt) > 1)

#define	MEXT_REM_REF(m) do {						\
	KASSERT(*((m)->m_ext.ref_cnt) > 0, ("m_ext refcnt < 0"));	\
	atomic_subtract_int((m)->m_ext.ref_cnt, 1);			\
} while(0)

#define	MEXT_ADD_REF(m)	atomic_add_int((m)->m_ext.ref_cnt, 1)

/*
 * mbuf, cluster, and external object allocation macros
 * (for compatibility purposes).
 */
/* NB: M_COPY_PKTHDR is deprecated, use M_MOVE_PKTHDR or m_dup_pktdr */
#define	M_MOVE_PKTHDR(to, from)	m_move_pkthdr((to), (from))
#define	m_getclr(how, type)	m_get_clrd((how), (type))
#define	MGET(m, how, type)	((m) = m_get((how), (type)))
#define	MGETHDR(m, how, type)	((m) = m_gethdr((how), (type)))
#define	MCLGET(m, how)		m_clget((m), (how))
#define	MEXTADD(m, buf, size, free, args, flags, type) 			\
    m_extadd((m), (caddr_t)(buf), (size), (free), (args), (flags), (type))

/*
 * MEXTFREE(m): disassociate (and possibly free) an external object from (m).
 * 
 * If the atomic_cmpset_int() returns 0, then we effectively do nothing
 * in terms of "cleaning up" (freeing the ext buf and ref. counter) as
 * this means that either there are still references, or another thread
 * is taking care of the clean-up.
 */
#define	MEXTFREE(m) do {						\
	struct mbuf *_mb = (m);						\
									\
	MEXT_REM_REF(_mb);						\
	if (atomic_cmpset_int(_mb->m_ext.ref_cnt, 0, 1))		\
		_mext_free(_mb);					\
	_mb->m_flags &= ~M_EXT;						\
} while (0)

/*
 * Evaluate TRUE if it's safe to write to the mbuf m's data region (this
 * can be both the local data payload, or an external buffer area,
 * depending on whether M_EXT is set).
 */
#define	M_WRITABLE(m)	(!((m)->m_flags & M_RDONLY) && (!((m)->m_flags  \
			    & M_EXT) || !MEXT_IS_REF(m)))

/*
 * Set the m_data pointer of a newly-allocated mbuf (m_get/MGET) to place
 * an object of the specified size at the end of the mbuf, longword aligned.
 */
#define	M_ALIGN(m, len) do {						\
	(m)->m_data += (MLEN - (len)) & ~(sizeof(long) - 1);		\
} while (0)

/*
 * As above, for mbufs allocated with m_gethdr/MGETHDR
 * or initialized by M_COPY_PKTHDR.
 */
#define	MH_ALIGN(m, len) do {						\
	(m)->m_data += (MHLEN - (len)) & ~(sizeof(long) - 1);		\
} while (0)

/*
 * Compute the amount of space available
 * before the current start of data in an mbuf.
 *
 * The M_WRITABLE() is a temporary, conservative safety measure: the burden
 * of checking writability of the mbuf data area rests solely with the caller.
 */
#define	M_LEADINGSPACE(m)						\
	((m)->m_flags & M_EXT ?						\
	    (M_WRITABLE(m) ? (m)->m_data - (m)->m_ext.ext_buf : 0):	\
	    (m)->m_flags & M_PKTHDR ? (m)->m_data - (m)->m_pktdat :	\
	    (m)->m_data - (m)->m_dat)

/*
 * Compute the amount of space available
 * after the end of data in an mbuf.
 *
 * The M_WRITABLE() is a temporary, conservative safety measure: the burden
 * of checking writability of the mbuf data area rests solely with the caller.
 */
#define	M_TRAILINGSPACE(m)						\
	((m)->m_flags & M_EXT ?						\
	    (M_WRITABLE(m) ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size	\
		- ((m)->m_data + (m)->m_len) : 0) :			\
	    &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len))

/*
 * Arrange to prepend space of size plen to mbuf m.
 * If a new mbuf must be allocated, how specifies whether to wait.
 * If the allocation fails, the original mbuf chain is freed and m is
 * set to NULL.
 */
#define	M_PREPEND(m, plen, how) do {					\
	struct mbuf **_mmp = &(m);					\
	struct mbuf *_mm = *_mmp;					\
	int _mplen = (plen);						\
	int __mhow = (how);						\
									\
	if (M_LEADINGSPACE(_mm) >= _mplen) {				\
		_mm->m_data -= _mplen;					\
		_mm->m_len += _mplen;					\
	} else								\
		_mm = m_prepend(_mm, _mplen, __mhow);			\
	if (_mm != NULL && _mm->m_flags & M_PKTHDR)			\
		_mm->m_pkthdr.len += _mplen;				\
	*_mmp = _mm;							\
} while (0)

/*
 * Change mbuf to new type.
 * This is a relatively expensive operation and should be avoided.
 */
#define	MCHTYPE(m, t)	m_chtype((m), (t))

/* Length to m_copy to copy all. */
#define	M_COPYALL	1000000000

/* Compatibility with 4.3. */
#define	m_copy(m, o, l)	m_copym((m), (o), (l), M_DONTWAIT)

extern	int max_datalen;		/* MHLEN - max_hdr */
extern	int max_hdr;			/* Largest link + protocol header */
extern	int max_linkhdr;		/* Largest link-level header */
extern	int max_protohdr;		/* Largest protocol header */
extern	struct mbstat mbstat;		/* General mbuf stats/infos */
extern	int nmbclusters;		/* Maximum number of clusters */
extern	int nmbcnt;			/* Scale kmem_map for counter space */
extern	int nmbufs;			/* Maximum number of mbufs */
extern	int nsfbufs;			/* Number of sendfile(2) bufs */

void		 _mext_free(struct mbuf *);
void		 m_adj(struct mbuf *, int);
void		 m_cat(struct mbuf *, struct mbuf *);
void		 m_chtype(struct mbuf *, short);
void		 m_clget(struct mbuf *, int);
void		 m_extadd(struct mbuf *, caddr_t, u_int,
		    void (*)(void *, void *), void *, int, int);
void		 m_copyback(struct mbuf *, int, int, caddr_t);
void		 m_copydata(const struct mbuf *, int, int, caddr_t);
struct	mbuf	*m_copym(struct mbuf *, int, int, int);
struct	mbuf	*m_copypacket(struct mbuf *, int);
void		 m_copy_pkthdr(struct mbuf *, struct mbuf *);
struct	mbuf	*m_devget(char *, int, int, struct ifnet *,
		    void (*)(char *, caddr_t, u_int));
struct	mbuf	*m_dup(struct mbuf *, int);
int		 m_dup_pkthdr(struct mbuf *, struct mbuf *, int);
u_int		 m_fixhdr(struct mbuf *);
struct	mbuf	*m_free(struct mbuf *);
void		 m_freem(struct mbuf *);
struct	mbuf	*m_get(int, short);
struct	mbuf	*m_get_clrd(int, short);
struct	mbuf	*m_getcl(int, short, int);
struct	mbuf	*m_gethdr(int, short);
struct	mbuf	*m_gethdr_clrd(int, short);
struct	mbuf	*m_getm(struct mbuf *, int, int, short);
u_int		 m_length(struct mbuf *, struct mbuf **);
void		 m_move_pkthdr(struct mbuf *, struct mbuf *);
struct	mbuf	*m_prepend(struct mbuf *, int, int);
void		 m_print(const struct mbuf *);
struct	mbuf	*m_pulldown(struct mbuf *, int, int, int *);
struct	mbuf	*m_pullup(struct mbuf *, int);
struct	mbuf	*m_split(struct mbuf *, int, int);

/*
 * Packets may have annotations attached by affixing a list
 * of "packet tags" to the pkthdr structure.  Packet tags are
 * dynamically allocated semi-opaque data structures that have
 * a fixed header (struct m_tag) that specifies the size of the
 * memory block and a <cookie,type> pair that identifies it.
 * The cookie is a 32-bit unique unsigned value used to identify
 * a module or ABI.  By convention this value is chose as the
 * date+time that the module is created, expressed as the number of
 * seconds since the epoch (e.g. using date -u +'%s').  The type value
 * is an ABI/module-specific value that identifies a particular annotation
 * and is private to the module.  For compatibility with systems
 * like openbsd that define packet tags w/o an ABI/module cookie,
 * the value PACKET_ABI_COMPAT is used to implement m_tag_get and
 * m_tag_find compatibility shim functions and several tag types are
 * defined below.  Users that do not require compatibility should use
 * a private cookie value so that packet tag-related definitions
 * can be maintained privately.
 *
 * Note that the packet tag returned by m_tag_allocate has the default
 * memory alignment implemented by malloc.  To reference private data
 * one can use a construct like:
 *
 *	struct m_tag *mtag = m_tag_allocate(...);
 *	struct foo *p = (struct foo *)(mtag+1);
 *
 * if the alignment of struct m_tag is sufficient for referencing members
 * of struct foo.  Otherwise it is necessary to embed struct m_tag within
 * the private data structure to insure proper alignment; e.g.
 *
 *	struct foo {
 *		struct m_tag	tag;
 *		...
 *	};
 *	struct foo *p = (struct foo *) m_tag_allocate(...);
 *	struct m_tag *mtag = &p->tag;
 */

#define	PACKET_TAG_NONE				0  /* Nadda */

/* Packet tag for use with PACKET_ABI_COMPAT */
#define	PACKET_TAG_IPSEC_IN_DONE		1  /* IPsec applied, in */
#define	PACKET_TAG_IPSEC_OUT_DONE		2  /* IPsec applied, out */
#define	PACKET_TAG_IPSEC_IN_CRYPTO_DONE		3  /* NIC IPsec crypto done */
#define	PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED	4  /* NIC IPsec crypto req'ed */
#define	PACKET_TAG_IPSEC_IN_COULD_DO_CRYPTO	5  /* NIC notifies IPsec */
#define	PACKET_TAG_IPSEC_PENDING_TDB		6  /* Reminder to do IPsec */
#define	PACKET_TAG_BRIDGE			7  /* Bridge processing done */
#define	PACKET_TAG_GIF				8  /* GIF processing done */
#define	PACKET_TAG_GRE				9  /* GRE processing done */
#define	PACKET_TAG_IN_PACKET_CHECKSUM		10 /* NIC checksumming done */
#define	PACKET_TAG_ENCAP			11 /* Encap.  processing */
#define	PACKET_TAG_IPSEC_SOCKET			12 /* IPSEC socket ref */
#define	PACKET_TAG_IPSEC_HISTORY		13 /* IPSEC history */
#define	PACKET_TAG_IPV6_INPUT			14 /* IPV6 input processing */

/*
 * As a temporary and low impact solution to replace the even uglier
 * approach used so far in some parts of the network stack (which relies
 * on global variables), packet tag-like annotations are stored in MT_TAG
 * mbufs (or lookalikes) prepended to the actual mbuf chain.
 *
 *	m_type	= MT_TAG
 *	m_flags = m_tag_id
 *	m_next	= next buffer in chain.
 *
 * BE VERY CAREFUL not to pass these blocks to the mbuf handling routines.
 */
#define	_m_tag_id	m_hdr.mh_flags

/* Packet tags used in the FreeBSD network stack */
#define	PACKET_TAG_DUMMYNET			15 /* dummynet info */
#define	PACKET_TAG_IPFW				16 /* ipfw classification */
#define	PACKET_TAG_DIVERT			17 /* divert info */
#define	PACKET_TAG_IPFORWARD			18 /* ipforward info */

/* Packet tag routines */
struct	m_tag 	*m_tag_alloc(u_int32_t, int, int, int);
void		 m_tag_free(struct m_tag *);
void		 m_tag_prepend(struct mbuf *, struct m_tag *);
void		 m_tag_unlink(struct mbuf *, struct m_tag *);
void		 m_tag_delete(struct mbuf *, struct m_tag *);
void		 m_tag_delete_chain(struct mbuf *, struct m_tag *);
struct	m_tag	*m_tag_locate(struct mbuf *, u_int32_t, int, struct m_tag *);
struct	m_tag	*m_tag_copy(struct m_tag *, int);
int		 m_tag_copy_chain(struct mbuf *, struct mbuf *, int);
void		 m_tag_init(struct mbuf *);
struct	m_tag	*m_tag_first(struct mbuf *);
struct	m_tag	*m_tag_next(struct mbuf *, struct m_tag *);

/* these are for openbsd compatibility */
#define	MTAG_ABI_COMPAT		0		/* compatibility ABI */

static __inline struct m_tag *
m_tag_get(int type, int length, int wait)
{
	return m_tag_alloc(MTAG_ABI_COMPAT, type, length, wait);
}

static __inline struct m_tag *
m_tag_find(struct mbuf *m, int type, struct m_tag *start)
{
	return m_tag_locate(m, MTAG_ABI_COMPAT, type, start);
}
#endif /* _KERNEL */

#endif /* !_SYS_MBUF_H_ */