sys/sys/mbuf.h

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * %sccs.include.redist.c%
 *
 *	@(#)mbuf.h	8.5 (Berkeley) 02/19/95
 */

#ifndef M_WAITOK
#include <sys/malloc.h>
#endif

/*
 * Mbufs are of a single size, MSIZE (machine/machparam.h), which
 * includes overhead.  An mbuf may add a single "mbuf cluster" of size
 * MCLBYTES (also in machine/machparam.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.
 */

#define	MLEN		(MSIZE - sizeof(struct m_hdr))	/* normal data len */
#define	MHLEN		(MLEN - sizeof(struct pkthdr))	/* data len w/pkthdr */

#define	MINCLSIZE	(MHLEN + MLEN)	/* smallest amount to put in cluster */
#define	M_MAXCOMPRESS	(MHLEN / 2)	/* max amount to copy for compression */

/*
 * 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)
 * mtocl(x) -	convert pointer within cluster to cluster index #
 * cltom(x) -	convert cluster # to ptr to beginning of cluster
 */
#define	mtod(m,t)	((t)((m)->m_data))
#define	dtom(x)		((struct mbuf *)((long)(x) & ~(MSIZE-1)))
#define	mtocl(x)	(((u_long)(x) - (u_long)mbutl) >> MCLSHIFT)
#define	cltom(x)	((caddr_t)((u_long)mbutl + ((u_long)(x) << MCLSHIFT)))

/* header at beginning of each 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 */
	short	mh_type;		/* type of data in this mbuf */
	short	mh_flags;		/* flags; see below */
};

/* record/packet header in first mbuf of chain; valid if M_PKTHDR set */
struct	pkthdr {
	struct	ifnet *rcvif;		/* rcv interface */
	int	len;			/* total packet length */
};

/* description of external storage mapped into mbuf, valid if M_EXT set */
struct m_ext {
	caddr_t	ext_buf;		/* start of buffer */
	void	(*ext_free)();		/* free routine if not the usual */
	u_int	ext_size;		/* size of buffer, for ext_free */
};

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 */

/* mbuf pkthdr flags, also in m_flags */
#define	M_BCAST		0x0100	/* send/received as link-level broadcast */
#define	M_MCAST		0x0200	/* send/received as link-level multicast */

/* flags copied when copying m_pkthdr */
#define	M_COPYFLAGS	(M_PKTHDR|M_EOR|M_BCAST|M_MCAST)

/* mbuf types */
#define	MT_FREE		0	/* should be on free list */
#define	MT_DATA		1	/* dynamic (data) allocation */
#define	MT_HEADER	2	/* packet header */
#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 */
#define	MT_SONAME	8	/* socket name */
#define	MT_SOOPTS	10	/* socket options */
#define	MT_FTABLE	11	/* fragment reassembly header */
#define	MT_RIGHTS	12	/* access rights */
#define	MT_IFADDR	13	/* interface address */
#define MT_CONTROL	14	/* extra-data protocol message */
#define MT_OOBDATA	15	/* expedited data  */

/* flags to m_get/MGET */
#define	M_DONTWAIT	M_NOWAIT
#define	M_WAIT		M_WAITOK

/*
 * mbuf utility macros:
 *
 *	MBUFLOCK(code)
 * prevents a section of code from from being interrupted by network
 * drivers.
 */
#define	MBUFLOCK(code) \
	{ int ms = splimp(); \
	  { code } \
	  splx(ms); \
	}

/*
 * mbuf allocation/deallocation macros:
 *
 *	MGET(struct mbuf *m, int how, int type)
 * allocates an mbuf and initializes it to contain internal data.
 *
 *	MGETHDR(struct mbuf *m, int how, int type)
 * allocates an mbuf and initializes it to contain a packet header
 * and internal data.
 */
#define	MGET(m, how, type) { \
	MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
	if (m) { \
		(m)->m_type = (type); \
		MBUFLOCK(mbstat.m_mtypes[type]++;) \
		(m)->m_next = (struct mbuf *)NULL; \
		(m)->m_nextpkt = (struct mbuf *)NULL; \
		(m)->m_data = (m)->m_dat; \
		(m)->m_flags = 0; \
	} else \
		(m) = m_retry((how), (type)); \
}

#define	MGETHDR(m, how, type) { \
	MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
	if (m) { \
		(m)->m_type = (type); \
		MBUFLOCK(mbstat.m_mtypes[type]++;) \
		(m)->m_next = (struct mbuf *)NULL; \
		(m)->m_nextpkt = (struct mbuf *)NULL; \
		(m)->m_data = (m)->m_pktdat; \
		(m)->m_flags = M_PKTHDR; \
	} else \
		(m) = m_retryhdr((how), (type)); \
}

/*
 * Mbuf cluster macros.
 * MCLALLOC(caddr_t p, int how) allocates an mbuf cluster.
 * MCLGET adds such clusters to a normal mbuf;
 * the flag M_EXT is set upon success.
 * MCLFREE releases a reference to a cluster allocated by MCLALLOC,
 * freeing the cluster if the reference count has reached 0.
 *
 * Normal mbuf clusters are normally treated as character arrays
 * after allocation, but use the first word of the buffer as a free list
 * pointer while on the free list.
 */
union mcluster {
	union	mcluster *mcl_next;
	char	mcl_buf[MCLBYTES];
};

#define	MCLALLOC(p, how) \
	MBUFLOCK( \
	  if (mclfree == 0) \
		(void)m_clalloc(1, (how)); \
	  if (((p) = (caddr_t)mclfree) != 0) { \
		++mclrefcnt[mtocl(p)]; \
		mbstat.m_clfree--; \
		mclfree = ((union mcluster *)(p))->mcl_next; \
	  } \
	)

#define	MCLGET(m, how) \
	{ MCLALLOC((m)->m_ext.ext_buf, (how)); \
	  if ((m)->m_ext.ext_buf != NULL) { \
		(m)->m_data = (m)->m_ext.ext_buf; \
		(m)->m_flags |= M_EXT; \
		(m)->m_ext.ext_size = MCLBYTES;  \
	  } \
	}

#define	MCLFREE(p) \
	MBUFLOCK ( \
	  if (--mclrefcnt[mtocl(p)] == 0) { \
		((union mcluster *)(p))->mcl_next = mclfree; \
		mclfree = (union mcluster *)(p); \
		mbstat.m_clfree++; \
	  } \
	)

/*
 * MFREE(struct mbuf *m, struct mbuf *n)
 * Free a single mbuf and associated external storage.
 * Place the successor, if any, in n.
 */
#ifdef notyet
#define	MFREE(m, n) \
	{ MBUFLOCK(mbstat.m_mtypes[(m)->m_type]--;) \
	  if ((m)->m_flags & M_EXT) { \
		if ((m)->m_ext.ext_free) \
			(*((m)->m_ext.ext_free))((m)->m_ext.ext_buf, \
			    (m)->m_ext.ext_size); \
		else \
			MCLFREE((m)->m_ext.ext_buf); \
	  } \
	  (n) = (m)->m_next; \
	  FREE((m), mbtypes[(m)->m_type]); \
	}
#else /* notyet */
#define	MFREE(m, nn) \
	{ MBUFLOCK(mbstat.m_mtypes[(m)->m_type]--;) \
	  if ((m)->m_flags & M_EXT) { \
		MCLFREE((m)->m_ext.ext_buf); \
	  } \
	  (nn) = (m)->m_next; \
	  FREE((m), mbtypes[(m)->m_type]); \
	}
#endif

/*
 * Copy mbuf pkthdr from from to to.
 * from must have M_PKTHDR set, and to must be empty.
 */
#define	M_COPY_PKTHDR(to, from) { \
	(to)->m_pkthdr = (from)->m_pkthdr; \
	(to)->m_flags = (from)->m_flags & M_COPYFLAGS; \
	(to)->m_data = (to)->m_pktdat; \
}

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

/*
 * Compute the amount of space available
 * before the current start of data in an mbuf.
 */
#define	M_LEADINGSPACE(m) \
	((m)->m_flags & M_EXT ? /* (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.
 */
#define	M_TRAILINGSPACE(m) \
	((m)->m_flags & M_EXT ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size - \
	    ((m)->m_data + (m)->m_len) : \
	    &(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 how is M_DONTWAIT and allocation fails, the original mbuf chain
 * is freed and m is set to NULL.
 */
#define	M_PREPEND(m, plen, how) { \
	if (M_LEADINGSPACE(m) >= (plen)) { \
		(m)->m_data -= (plen); \
		(m)->m_len += (plen); \
	} else \
		(m) = m_prepend((m), (plen), (how)); \
	if ((m) && (m)->m_flags & M_PKTHDR) \
		(m)->m_pkthdr.len += (plen); \
}

/* change mbuf to new type */
#define MCHTYPE(m, t) { \
	MBUFLOCK(mbstat.m_mtypes[(m)->m_type]--; mbstat.m_mtypes[t]++;) \
	(m)->m_type = t;\
}

/* length to m_copy to copy all */
#define	M_COPYALL	1000000000

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

/*
 * Mbuf statistics.
 */
struct mbstat {
	u_long	m_mbufs;	/* mbufs obtained from page pool */
	u_long	m_clusters;	/* clusters obtained from page pool */
	u_long	m_spare;	/* spare field */
	u_long	m_clfree;	/* free clusters */
	u_long	m_drops;	/* times failed to find space */
	u_long	m_wait;		/* times waited for space */
	u_long	m_drain;	/* times drained protocols for space */
	u_short	m_mtypes[256];	/* type specific mbuf allocations */
};

#ifdef	KERNEL
extern	struct mbuf *mbutl;		/* virtual address of mclusters */
extern	char *mclrefcnt;		/* cluster reference counts */
struct	mbstat mbstat;
extern	int nmbclusters;
union	mcluster *mclfree;
int	max_linkhdr;			/* largest link-level header */
int	max_protohdr;			/* largest protocol header */
int	max_hdr;			/* largest link+protocol header */
int	max_datalen;			/* MHLEN - max_hdr */
extern	int mbtypes[];			/* XXX */

struct	mbuf *m_copym __P((struct mbuf *, int, int, int));
struct	mbuf *m_free __P((struct mbuf *));
struct	mbuf *m_get __P((int, int));
struct	mbuf *m_getclr __P((int, int));
struct	mbuf *m_gethdr __P((int, int));
struct	mbuf *m_prepend __P((struct mbuf *, int, int));
struct	mbuf *m_pullup __P((struct mbuf *, int));
struct	mbuf *m_retry __P((int, int));
struct	mbuf *m_retryhdr __P((int, int));
void	m_adj __P((struct mbuf *, int));
int	m_clalloc __P((int, int));
void	m_copyback __P((struct mbuf *, int, int, caddr_t));
void	m_freem __P((struct mbuf *));
void	m_reclaim __P((void));

#ifdef MBTYPES
int mbtypes[] = {				/* XXX */
	M_FREE,		/* MT_FREE	0	   should be on free list */
	M_MBUF,		/* MT_DATA	1	   dynamic (data) allocation */
	M_MBUF,		/* MT_HEADER	2	   packet header */
	M_SOCKET,	/* MT_SOCKET	3	   socket structure */
	M_PCB,		/* MT_PCB	4	   protocol control block */
	M_RTABLE,	/* MT_RTABLE	5	   routing tables */
	M_HTABLE,	/* MT_HTABLE	6	   IMP host tables */
	0,		/* MT_ATABLE	7	   address resolution tables */
	M_MBUF,		/* MT_SONAME	8	   socket name */
	0,		/* 		9 */
	M_SOOPTS,	/* MT_SOOPTS	10	   socket options */
	M_FTABLE,	/* MT_FTABLE	11	   fragment reassembly header */
	M_MBUF,		/* MT_RIGHTS	12	   access rights */
	M_IFADDR,	/* MT_IFADDR	13	   interface address */
	M_MBUF,		/* MT_CONTROL	14	   extra-data protocol message */
	M_MBUF,		/* MT_OOBDATA	15	   expedited data  */
#ifdef DATAKIT
	25, 26, 27, 28, 29, 30, 31, 32		/* datakit ugliness */
#endif
};
#endif
#endif