mbuf.h

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/*
 * 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. 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: src/sys/sys/mbuf.h,v 1.169 2005/03/17 19:34:57 jmg Exp $
 */

 
#ifndef _SYS_MBUF_H_
#define _SYS_MBUF_H_

#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 *)((intptr_t)(x) & ~(MSIZE-1)))
#define mtocl(x)        (((uintptr_t)(x) - (uintptr_t)mbutl) >> MCLSHIFT)
#define cltom(x)        ((caddr_t)((u_long)mbutl + ((u_long)(x) << MCLSHIFT)))

/*
 * 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 */
};

/*
 * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
 */
struct  pkthdr {
        struct  ifnet *rcvif;           /* rcv interface */
        int32_t len;                    /* total packet length */
};

/*
 * 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 */
                (caddr_t, u_int);
        u_int   ext_size;               /* size of buffer, for ext_free */
        void    (*ext_ref)              /* add a reference to the ext object */
                (caddr_t, u_int);
};

/*
 * 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_PROTO1        0x0008  /* protocol-specific */

/*
 * mbuf pkthdr flags (also stored 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_PROTO1|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  */

/*
 * General mbuf allocator statistics structure.
 */
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 */
};


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

/* Freelists:
 *
 * 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];
};

/*
 * 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) { \
          int _ms = splimp(); \
          if (mmbfree == 0) \
                (void)m_mballoc(1, (how)); \
          if (((m) = mmbfree) != 0) { \
                mmbfree = (m)->m_next; \
                mbstat.m_mtypes[MT_FREE]--; \
                (m)->m_type = (type); \
                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; \
                splx(_ms); \
        } else { \
                splx(_ms); \
                (m) = m_retry((how), (type)); \
        } \
}

#define MGETHDR(m, how, type) { \
          int _ms = splimp(); \
          if (mmbfree == 0) \
                (void)m_mballoc(1, (how)); \
          if (((m) = mmbfree) != 0) { \
                mmbfree = (m)->m_next; \
                mbstat.m_mtypes[MT_FREE]--; \
                (m)->m_type = (type); \
                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; \
                splx(_ms); \
        } else { \
                splx(_ms); \
                (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.
 */
#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_free = NULL;  \
                (m)->m_ext.ext_ref = NULL;  \
                (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.
 */
#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 { \
                        char *p = (m)->m_ext.ext_buf; \
                        if (--mclrefcnt[mtocl(p)] == 0) { \
                                ((union mcluster *)(p))->mcl_next = mclfree; \
                                mclfree = (union mcluster *)(p); \
                                mbstat.m_clfree++; \
                        } \
                } \
          } \
          (n) = (m)->m_next; \
          (m)->m_type = MT_FREE; \
          mbstat.m_mtypes[MT_FREE]++; \
          (m)->m_next = mmbfree; \
          mmbfree = (m); \
        )

/*
 * 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) 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.
 */
#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.
 * This is a relatively expensive operation and should be avoided.
 */
#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       (uint32_t)1000000000L

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

#ifdef  _KERNEL
extern struct mbuf *mbutl;              /* virtual address of mclusters */
extern char     *mclrefcnt;             /* cluster reference counts */
extern struct mbstat mbstat;
extern uint32_t nmbclusters;
extern uint32_t nmbufs;
extern struct mbuf *mmbfree;
extern union mcluster *mclfree;
extern int      max_linkhdr;            /* largest link-level header */
extern int      max_protohdr;           /* largest protocol header */
extern int      max_hdr;                /* largest link+protocol header */
extern int      max_datalen;            /* MHLEN - max_hdr */

struct  mbuf *m_copym(struct mbuf *, int, uint32_t, int);
struct  mbuf *m_copypacket(struct mbuf *, int);
struct  mbuf *m_devget(char *, int, int, struct ifnet *,
                            void (*copy)(char *, caddr_t, u_int));
struct  mbuf *m_free(struct mbuf *);
struct  mbuf *m_get(int, int);
struct  mbuf *m_getclr(int, int);
struct  mbuf *m_gethdr(int, int);
struct  mbuf *m_prepend(struct mbuf *,int,int);
struct  mbuf *m_pullup(struct mbuf *, int);
struct  mbuf *m_retry(int, int);
struct  mbuf *m_retryhdr(int, int);
struct  mbuf *m_split(struct mbuf *,int,int);
void    m_adj(struct mbuf *, int);
void    m_cat(struct mbuf *,struct mbuf *);
int     m_mballoc(int, int);
int     m_clalloc(int, int);
int     m_copyback(struct mbuf *, int, int, caddr_t);
int     m_copydata(const struct mbuf *, int, int, caddr_t);
void    m_freem(struct mbuf *);
void    m_reclaim(void);

#endif /* _KERNEL */

#endif /* !_SYS_MBUF_H_ */