FreeBSD/Linux Kernel Cross Reference
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: src/sys/sys/mbuf.h,v 1.18.2.1 1999/09/05 08:22:35 peter 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 *)((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 */
                    __P((caddr_t, u_int));
            u_int   ext_size;               /* size of buffer, for ext_free */
            void    (*ext_ref)              /* add a reference to the ext object */
                    __P((caddr_t, u_int));
    };
    
    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 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  */
   
   /* 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) \
           { (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
   
   /* compatibility 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 */
   extern struct mbstat mbstat;
   extern int      nmbclusters;
   extern int      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 */
   extern int      mbtypes[];              /* XXX */
   
   struct  mbuf *m_copym __P((struct mbuf *, int, int, int));
   struct  mbuf *m_copypacket __P((struct mbuf *, int));
   struct  mbuf *m_devget __P((char *, int, int, struct ifnet *,
                               void (*copy)(char *, caddr_t, u_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));
   struct  mbuf *m_split __P((struct mbuf *,int,int));
   void    m_adj __P((struct mbuf *, int));
   void    m_cat __P((struct mbuf *,struct mbuf *));
   int     m_mballoc __P((int, int));
   int     m_clalloc __P((int, int));
   void    m_copyback __P((struct mbuf *, int, int, caddr_t));
   void    m_copydata __P((struct mbuf *,int,int,caddr_t));
   void    m_freem __P((struct mbuf *));
   
   #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
   
   #endif /* !_SYS_MBUF_H_ */

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