FreeBSD/Linux Kernel Cross Reference
sys/sys/mbuf.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * 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
     * $FreeBSD$
     */
    
    #ifndef _SYS_MBUF_H_
    #define _SYS_MBUF_H_
    
    /* XXX: These includes suck. Sorry! */
    #include <sys/queue.h>
    #ifdef _KERNEL
    #include <sys/systm.h>
    #include <vm/uma.h>
    #ifdef WITNESS
    #include <sys/lock.h>
    #endif
    #endif
    
    #ifdef _KERNEL
    #include <sys/sdt.h>
    
    #define MBUF_PROBE1(probe, arg0)                                        \
            SDT_PROBE1(sdt, , , probe, arg0)
    #define MBUF_PROBE2(probe, arg0, arg1)                                  \
            SDT_PROBE2(sdt, , , probe, arg0, arg1)
    #define MBUF_PROBE3(probe, arg0, arg1, arg2)                            \
            SDT_PROBE3(sdt, , , probe, arg0, arg1, arg2)
    #define MBUF_PROBE4(probe, arg0, arg1, arg2, arg3)                      \
            SDT_PROBE4(sdt, , , probe, arg0, arg1, arg2, arg3)
    #define MBUF_PROBE5(probe, arg0, arg1, arg2, arg3, arg4)                \
            SDT_PROBE5(sdt, , , probe, arg0, arg1, arg2, arg3, arg4)
    
    SDT_PROBE_DECLARE(sdt, , , m__init);
    SDT_PROBE_DECLARE(sdt, , , m__gethdr);
    SDT_PROBE_DECLARE(sdt, , , m__get);
    SDT_PROBE_DECLARE(sdt, , , m__getcl);
    SDT_PROBE_DECLARE(sdt, , , m__getjcl);
    SDT_PROBE_DECLARE(sdt, , , m__clget);
    SDT_PROBE_DECLARE(sdt, , , m__cljget);
    SDT_PROBE_DECLARE(sdt, , , m__cljset);
    SDT_PROBE_DECLARE(sdt, , , m__free);
    SDT_PROBE_DECLARE(sdt, , , m__freem);
    
    #endif /* _KERNEL */
    
    /*
     * Mbufs are of a single size, MSIZE (sys/param.h), which includes overhead.
     * An mbuf may add a single "mbuf cluster" of size MCLBYTES (also in
     * sys/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.
     *
     * NB: These calculation do not take actual compiler-induced alignment and
     * padding inside the complete struct mbuf into account.  Appropriate
     * attention is required when changing members of struct mbuf.
     *
     * MLEN is data length in a normal mbuf.
     * MHLEN is data length in an mbuf with pktheader.
     * MINCLSIZE is a smallest amount of data that should be put into cluster.
     *
     * Compile-time assertions in uipc_mbuf.c test these values to ensure that
     * they are sensible.
     */
    struct mbuf;
    #define MHSIZE          offsetof(struct mbuf, m_dat)
    #define MPKTHSIZE       offsetof(struct mbuf, m_pktdat)
    #define MLEN            ((int)(MSIZE - MHSIZE))
   #define MHLEN           ((int)(MSIZE - MPKTHSIZE))
   #define MINCLSIZE       (MHLEN + 1)
   
   #ifdef _KERNEL
   /*-
    * Macro for type conversion: convert mbuf pointer to data pointer of correct
    * type:
    *
    * mtod(m, t)   -- Convert mbuf pointer to data pointer of correct type.
    * mtodo(m, o) -- Same as above but with offset 'o' into data.
    */
   #define mtod(m, t)      ((t)((m)->m_data))
   #define mtodo(m, o)     ((void *)(((m)->m_data) + (o)))
   
   /*
    * Argument structure passed to UMA routines during mbuf and packet
    * allocations.
    */
   struct mb_args {
           int     flags;  /* Flags for mbuf being allocated */
           short   type;   /* Type of mbuf being allocated */
   };
   #endif /* _KERNEL */
   
   /*
    * 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 */
           void                    (*m_tag_free)(struct m_tag *);
   };
   
   /*
    * Static network interface owned tag.
    * Allocated through ifp->if_snd_tag_alloc().
    */
   struct m_snd_tag {
           struct ifnet *ifp;              /* network interface tag belongs to */
   };
   
   /*
    * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
    * Size ILP32: 48
    *       LP64: 56
    * Compile-time assertions in uipc_mbuf.c test these values to ensure that
    * they are correct.
    */
   struct pkthdr {
           union {
                   struct m_snd_tag *snd_tag;      /* send tag, if any */
                   struct ifnet    *rcvif;         /* rcv interface */
           };
           SLIST_HEAD(packet_tags, m_tag) tags; /* list of packet tags */
           int32_t          len;           /* total packet length */
   
           /* Layer crossing persistent information. */
           uint32_t         flowid;        /* packet's 4-tuple system */
           uint32_t         csum_flags;    /* checksum and offload features */
           uint16_t         fibnum;        /* this packet should use this fib */
           uint8_t          cosqos;        /* class/quality of service */
           uint8_t          rsstype;       /* hash type */
           union {
                   uint64_t        rcv_tstmp;      /* timestamp in ns */
                   struct {
                           uint8_t          l2hlen;        /* layer 2 hdr len */
                           uint8_t          l3hlen;        /* layer 3 hdr len */
                           uint8_t          l4hlen;        /* layer 4 hdr len */
                           uint8_t          l5hlen;        /* layer 5 hdr len */
                           uint8_t          inner_l2hlen;
                           uint8_t          inner_l3hlen;
                           uint8_t          inner_l4hlen;
                           uint8_t          inner_l5hlen;
                   };
           };
           union {
                   uint8_t  eight[8];
                   uint16_t sixteen[4];
                   uint32_t thirtytwo[2];
                   uint64_t sixtyfour[1];
                   uintptr_t unintptr[1];
                   void    *ptr;
           } PH_per;
   
           /* Layer specific non-persistent local storage for reassembly, etc. */
           union {
                   uint8_t  eight[8];
                   uint16_t sixteen[4];
                   uint32_t thirtytwo[2];
                   uint64_t sixtyfour[1];
                   uintptr_t unintptr[1];
                   void    *ptr;
           } PH_loc;
   };
   #define ether_vtag      PH_per.sixteen[0]
   #define PH_vt           PH_per
   #define vt_nrecs        sixteen[0]
   #define tso_segsz       PH_per.sixteen[1]
   #define lro_nsegs       tso_segsz
   #define csum_phsum      PH_per.sixteen[2]
   #define csum_data       PH_per.thirtytwo[1]
   #define pace_thoff      PH_loc.sixteen[0]
   #define pace_tlen       PH_loc.sixteen[1]
   #define pace_drphdrlen  PH_loc.sixteen[2]
   #define pace_tos        PH_loc.eight[6]
   #define pace_lock       PH_loc.eight[7]
   
   /*
    * Description of external storage mapped into mbuf; valid only if M_EXT is
    * set.
    * Size ILP32: 28
    *       LP64: 48
    * Compile-time assertions in uipc_mbuf.c test these values to ensure that
    * they are correct.
    */
   typedef void m_ext_free_t(struct mbuf *);
   struct m_ext {
           union {
                   /*
                    * If EXT_FLAG_EMBREF is set, then we use refcount in the
                    * mbuf, the 'ext_count' member.  Otherwise, we have a
                    * shadow copy and we use pointer 'ext_cnt'.  The original
                    * mbuf is responsible to carry the pointer to free routine
                    * and its arguments.  They aren't copied into shadows in
                    * mb_dupcl() to avoid dereferencing next cachelines.
                    */
                   volatile u_int   ext_count;
                   volatile u_int  *ext_cnt;
           };
           char            *ext_buf;       /* start of buffer */
           uint32_t         ext_size;      /* size of buffer, for ext_free */
           uint32_t         ext_type:8,    /* type of external storage */
                            ext_flags:24;  /* external storage mbuf flags */
           /*
            * Fields below store the free context for the external storage.
            * They are valid only in the refcount carrying mbuf, the one with
            * EXT_FLAG_EMBREF flag, with exclusion for EXT_EXTREF type, where
            * the free context is copied into all mbufs that use same external
            * storage.
            */
   #define m_ext_copylen   offsetof(struct m_ext, ext_free)
           m_ext_free_t    *ext_free;      /* free routine if not the usual */
           void            *ext_arg1;      /* optional argument pointer */
           void            *ext_arg2;      /* optional argument pointer */
   };
   
   /*
    * The core of the mbuf object along with some shortcut defines for practical
    * purposes.
    */
   struct mbuf {
           /*
            * Header present at the beginning of every mbuf.
            * Size ILP32: 24
            *      LP64: 32
            * Compile-time assertions in uipc_mbuf.c test these values to ensure
            * that they are correct.
            */
           union { /* next buffer in chain */
                   struct mbuf             *m_next;
                   SLIST_ENTRY(mbuf)       m_slist;
                   STAILQ_ENTRY(mbuf)      m_stailq;
           };
           union { /* next chain in queue/record */
                   struct mbuf             *m_nextpkt;
                   SLIST_ENTRY(mbuf)       m_slistpkt;
                   STAILQ_ENTRY(mbuf)      m_stailqpkt;
           };
           caddr_t          m_data;        /* location of data */
           int32_t          m_len;         /* amount of data in this mbuf */
           uint32_t         m_type:8,      /* type of data in this mbuf */
                            m_flags:24;    /* flags; see below */
   #if !defined(__LP64__)
           uint32_t         m_pad;         /* pad for 64bit alignment */
   #endif
   
           /*
            * A set of optional headers (packet header, external storage header)
            * and internal data storage.  Historically, these arrays were sized
            * to MHLEN (space left after a packet header) and MLEN (space left
            * after only a regular mbuf header); they are now variable size in
            * order to support future work on variable-size mbufs.
            */
           union {
                   struct {
                           struct pkthdr   m_pkthdr;       /* M_PKTHDR set */
                           union {
                                   struct m_ext    m_ext;  /* M_EXT set */
                                   char            m_pktdat[0];
                           };
                   };
                   char    m_dat[0];                       /* !M_PKTHDR, !M_EXT */
           };
   };
   
   /*
    * mbuf flags of global significance and layer crossing.
    * Those of only protocol/layer specific significance are to be mapped
    * to M_PROTO[1-12] and cleared at layer handoff boundaries.
    * NB: Limited to the lower 24 bits.
    */
   #define M_EXT           0x00000001 /* has associated external storage */
   #define M_PKTHDR        0x00000002 /* start of record */
   #define M_EOR           0x00000004 /* end of record */
   #define M_RDONLY        0x00000008 /* associated data is marked read-only */
   #define M_BCAST         0x00000010 /* send/received as link-level broadcast */
   #define M_MCAST         0x00000020 /* send/received as link-level multicast */
   #define M_PROMISC       0x00000040 /* packet was not for us */
   #define M_VLANTAG       0x00000080 /* ether_vtag is valid */
   #define M_NOMAP         0x00000100 /* mbuf data is unmapped (soon from Drew) */
   #define M_NOFREE        0x00000200 /* do not free mbuf, embedded in cluster */
   #define M_TSTMP         0x00000400 /* rcv_tstmp field is valid */
   #define M_TSTMP_HPREC   0x00000800 /* rcv_tstmp is high-prec, typically
                                         hw-stamped on port (useful for IEEE 1588
                                         and 802.1AS) */
   #define M_TSTMP_LRO     0x00001000 /* Time LRO pushed in pkt is valid in (PH_loc) */
   
   #define M_PROTO1        0x00001000 /* protocol-specific */
   #define M_PROTO2        0x00002000 /* protocol-specific */
   #define M_PROTO3        0x00004000 /* protocol-specific */
   #define M_PROTO4        0x00008000 /* protocol-specific */
   #define M_PROTO5        0x00010000 /* protocol-specific */
   #define M_PROTO6        0x00020000 /* protocol-specific */
   #define M_PROTO7        0x00040000 /* protocol-specific */
   #define M_PROTO8        0x00080000 /* protocol-specific */
   #define M_PROTO9        0x00100000 /* protocol-specific */
   #define M_PROTO10       0x00200000 /* protocol-specific */
   #define M_PROTO11       0x00400000 /* protocol-specific */
   #define M_PROTO12       0x00800000 /* protocol-specific */
   
   #define MB_DTOR_SKIP    0x1     /* don't pollute the cache by touching a freed mbuf */
   
   /*
    * Flags to purge when crossing layers.
    */
   #define M_PROTOFLAGS \
       (M_PROTO1|M_PROTO2|M_PROTO3|M_PROTO4|M_PROTO5|M_PROTO6|M_PROTO7|M_PROTO8|\
        M_PROTO9|M_PROTO10|M_PROTO11|M_PROTO12)
   
   /*
    * Flags preserved when copying m_pkthdr.
    */
   #define M_COPYFLAGS \
       (M_PKTHDR|M_EOR|M_RDONLY|M_BCAST|M_MCAST|M_PROMISC|M_VLANTAG|M_TSTMP| \
        M_TSTMP_HPREC|M_PROTOFLAGS)
   
   /*
    * Mbuf flag description for use with printf(9) %b identifier.
    */
   #define M_FLAG_BITS \
       "\2\1M_EXT\2M_PKTHDR\3M_EOR\4M_RDONLY\5M_BCAST\6M_MCAST" \
       "\7M_PROMISC\10M_VLANTAG\13M_TSTMP\14M_TSTMP_HPREC"
   #define M_FLAG_PROTOBITS \
       "\15M_PROTO1\16M_PROTO2\17M_PROTO3\20M_PROTO4\21M_PROTO5" \
       "\22M_PROTO6\23M_PROTO7\24M_PROTO8\25M_PROTO9\26M_PROTO10" \
       "\27M_PROTO11\30M_PROTO12"
   #define M_FLAG_PRINTF (M_FLAG_BITS M_FLAG_PROTOBITS)
   
   /*
    * Network interface cards are able to hash protocol fields (such as IPv4
    * addresses and TCP port numbers) classify packets into flows.  These flows
    * can then be used to maintain ordering while delivering packets to the OS
    * via parallel input queues, as well as to provide a stateless affinity
    * model.  NIC drivers can pass up the hash via m->m_pkthdr.flowid, and set
    * m_flag fields to indicate how the hash should be interpreted by the
    * network stack.
    *
    * Most NICs support RSS, which provides ordering and explicit affinity, and
    * use the hash m_flag bits to indicate what header fields were covered by
    * the hash.  M_HASHTYPE_OPAQUE and M_HASHTYPE_OPAQUE_HASH can be set by non-
    * RSS cards or configurations that provide an opaque flow identifier, allowing
    * for ordering and distribution without explicit affinity.  Additionally,
    * M_HASHTYPE_OPAQUE_HASH indicates that the flow identifier has hash
    * properties.
    *
    * The meaning of the IPV6_EX suffix:
    * "o  Home address from the home address option in the IPv6 destination
    *     options header.  If the extension header is not present, use the Source
    *     IPv6 Address.
    *  o  IPv6 address that is contained in the Routing-Header-Type-2 from the
    *     associated extension header.  If the extension header is not present,
    *     use the Destination IPv6 Address."
    * Quoted from:
    * https://docs.microsoft.com/en-us/windows-hardware/drivers/network/rss-hashing-types#ndishashipv6ex
    */
   #define M_HASHTYPE_HASHPROP             0x80    /* has hash properties */
   #define M_HASHTYPE_INNER                0x40    /* calculated from inner headers */
   #define M_HASHTYPE_HASH(t)              (M_HASHTYPE_HASHPROP | (t))
   /* Microsoft RSS standard hash types */
   #define M_HASHTYPE_NONE                 0
   #define M_HASHTYPE_RSS_IPV4             M_HASHTYPE_HASH(1) /* IPv4 2-tuple */
   #define M_HASHTYPE_RSS_TCP_IPV4         M_HASHTYPE_HASH(2) /* TCPv4 4-tuple */
   #define M_HASHTYPE_RSS_IPV6             M_HASHTYPE_HASH(3) /* IPv6 2-tuple */
   #define M_HASHTYPE_RSS_TCP_IPV6         M_HASHTYPE_HASH(4) /* TCPv6 4-tuple */
   #define M_HASHTYPE_RSS_IPV6_EX          M_HASHTYPE_HASH(5) /* IPv6 2-tuple +
                                                               * ext hdrs */
   #define M_HASHTYPE_RSS_TCP_IPV6_EX      M_HASHTYPE_HASH(6) /* TCPv6 4-tuple +
                                                               * ext hdrs */
   #define M_HASHTYPE_RSS_UDP_IPV4         M_HASHTYPE_HASH(7) /* IPv4 UDP 4-tuple*/
   #define M_HASHTYPE_RSS_UDP_IPV6         M_HASHTYPE_HASH(9) /* IPv6 UDP 4-tuple*/
   #define M_HASHTYPE_RSS_UDP_IPV6_EX      M_HASHTYPE_HASH(10)/* IPv6 UDP 4-tuple +
                                                               * ext hdrs */
   
   #define M_HASHTYPE_OPAQUE               0x3f    /* ordering, not affinity */
   #define M_HASHTYPE_OPAQUE_HASH          M_HASHTYPE_HASH(M_HASHTYPE_OPAQUE)
                                                   /* ordering+hash, not affinity*/
   
   #define M_HASHTYPE_CLEAR(m)     ((m)->m_pkthdr.rsstype = 0)
   #define M_HASHTYPE_GET(m)       ((m)->m_pkthdr.rsstype & ~M_HASHTYPE_INNER)
   #define M_HASHTYPE_SET(m, v)    ((m)->m_pkthdr.rsstype = (v))
   #define M_HASHTYPE_TEST(m, v)   (M_HASHTYPE_GET(m) == (v))
   #define M_HASHTYPE_ISHASH(m)    \
       (((m)->m_pkthdr.rsstype & M_HASHTYPE_HASHPROP) != 0)
   #define M_HASHTYPE_SETINNER(m)  do {                    \
           (m)->m_pkthdr.rsstype |= M_HASHTYPE_INNER;      \
       } while (0)
   
   /*
    * COS/QOS class and quality of service tags.
    * It uses DSCP code points as base.
    */
   #define QOS_DSCP_CS0            0x00
   #define QOS_DSCP_DEF            QOS_DSCP_CS0
   #define QOS_DSCP_CS1            0x20
   #define QOS_DSCP_AF11           0x28
   #define QOS_DSCP_AF12           0x30
   #define QOS_DSCP_AF13           0x38
   #define QOS_DSCP_CS2            0x40
   #define QOS_DSCP_AF21           0x48
   #define QOS_DSCP_AF22           0x50
   #define QOS_DSCP_AF23           0x58
   #define QOS_DSCP_CS3            0x60
   #define QOS_DSCP_AF31           0x68
   #define QOS_DSCP_AF32           0x70
   #define QOS_DSCP_AF33           0x78
   #define QOS_DSCP_CS4            0x80
   #define QOS_DSCP_AF41           0x88
   #define QOS_DSCP_AF42           0x90
   #define QOS_DSCP_AF43           0x98
   #define QOS_DSCP_CS5            0xa0
   #define QOS_DSCP_EF             0xb8
   #define QOS_DSCP_CS6            0xc0
   #define QOS_DSCP_CS7            0xe0
   
   /*
    * External mbuf storage buffer types.
    */
   #define EXT_CLUSTER     1       /* mbuf cluster */
   #define EXT_SFBUF       2       /* sendfile(2)'s sf_buf */
   #define EXT_JUMBOP      3       /* jumbo cluster page sized */
   #define EXT_JUMBO9      4       /* jumbo cluster 9216 bytes */
   #define EXT_JUMBO16     5       /* jumbo cluster 16184 bytes */
   #define EXT_PACKET      6       /* mbuf+cluster from packet zone */
   #define EXT_MBUF        7       /* external mbuf reference */
   
   #define EXT_VENDOR1     224     /* for vendor-internal use */
   #define EXT_VENDOR2     225     /* for vendor-internal use */
   #define EXT_VENDOR3     226     /* for vendor-internal use */
   #define EXT_VENDOR4     227     /* for vendor-internal use */
   
   #define EXT_EXP1        244     /* for experimental use */
   #define EXT_EXP2        245     /* for experimental use */
   #define EXT_EXP3        246     /* for experimental use */
   #define EXT_EXP4        247     /* for experimental use */
   
   #define EXT_NET_DRV     252     /* custom ext_buf provided by net driver(s) */
   #define EXT_MOD_TYPE    253     /* custom module's ext_buf type */
   #define EXT_DISPOSABLE  254     /* can throw this buffer away w/page flipping */
   #define EXT_EXTREF      255     /* has externally maintained ext_cnt ptr */
   
   /*
    * Flags for external mbuf buffer types.
    * NB: limited to the lower 24 bits.
    */
   #define EXT_FLAG_EMBREF         0x000001        /* embedded ext_count */
   #define EXT_FLAG_EXTREF         0x000002        /* external ext_cnt, notyet */
   
   #define EXT_FLAG_NOFREE         0x000010        /* don't free mbuf to pool, notyet */
   
   #define EXT_FLAG_VENDOR1        0x010000        /* These flags are vendor */
   #define EXT_FLAG_VENDOR2        0x020000        /* or submodule specific, */
   #define EXT_FLAG_VENDOR3        0x040000        /* not used by mbuf code. */
   #define EXT_FLAG_VENDOR4        0x080000        /* Set/read by submodule. */
   
   #define EXT_FLAG_EXP1           0x100000        /* for experimental use */
   #define EXT_FLAG_EXP2           0x200000        /* for experimental use */
   #define EXT_FLAG_EXP3           0x400000        /* for experimental use */
   #define EXT_FLAG_EXP4           0x800000        /* for experimental use */
   
   /*
    * EXT flag description for use with printf(9) %b identifier.
    */
   #define EXT_FLAG_BITS \
       "\2\1EXT_FLAG_EMBREF\2EXT_FLAG_EXTREF\5EXT_FLAG_NOFREE" \
       "\21EXT_FLAG_VENDOR1\22EXT_FLAG_VENDOR2\23EXT_FLAG_VENDOR3" \
       "\24EXT_FLAG_VENDOR4\25EXT_FLAG_EXP1\26EXT_FLAG_EXP2\27EXT_FLAG_EXP3" \
       "\30EXT_FLAG_EXP4"
   
   /*
    * Flags indicating checksum, segmentation and other offload work to be
    * done, or already done, by hardware or lower layers.  It is split into
    * separate inbound and outbound flags.
    *
    * Outbound flags that are set by upper protocol layers requesting lower
    * layers, or ideally the hardware, to perform these offloading tasks.
    * For outbound packets this field and its flags can be directly tested
    * against ifnet if_hwassist.  Note that the outbound and the inbound flags do
    * not collide right now but they could be allowed to (as long as the flags are
    * scrubbed appropriately when the direction of an mbuf changes).  CSUM_BITS
    * would also have to split into CSUM_BITS_TX and CSUM_BITS_RX.
    *
    * CSUM_INNER_<x> is the same as CSUM_<x> but it applies to the inner frame.
    * The CSUM_ENCAP_<x> bits identify the outer encapsulation.
    */
   #define CSUM_IP                 0x00000001      /* IP header checksum offload */
   #define CSUM_IP_UDP             0x00000002      /* UDP checksum offload */
   #define CSUM_IP_TCP             0x00000004      /* TCP checksum offload */
   #define CSUM_IP_SCTP            0x00000008      /* SCTP checksum offload */
   #define CSUM_IP_TSO             0x00000010      /* TCP segmentation offload */
   #define CSUM_IP_ISCSI           0x00000020      /* iSCSI checksum offload */
   
   #define CSUM_INNER_IP6_UDP      0x00000040
   #define CSUM_INNER_IP6_TCP      0x00000080
   #define CSUM_INNER_IP6_TSO      0x00000100
   #define CSUM_IP6_UDP            0x00000200      /* UDP checksum offload */
   #define CSUM_IP6_TCP            0x00000400      /* TCP checksum offload */
   #define CSUM_IP6_SCTP           0x00000800      /* SCTP checksum offload */
   #define CSUM_IP6_TSO            0x00001000      /* TCP segmentation offload */
   #define CSUM_IP6_ISCSI          0x00002000      /* iSCSI checksum offload */
   
   #define CSUM_INNER_IP           0x00004000
   #define CSUM_INNER_IP_UDP       0x00008000
   #define CSUM_INNER_IP_TCP       0x00010000
   #define CSUM_INNER_IP_TSO       0x00020000
   
   #define CSUM_ENCAP_VXLAN        0x00040000      /* VXLAN outer encapsulation */
   #define CSUM_ENCAP_RSVD1        0x00080000
   
   /* Inbound checksum support where the checksum was verified by hardware. */
   #define CSUM_INNER_L3_CALC      0x00100000
   #define CSUM_INNER_L3_VALID     0x00200000
   #define CSUM_INNER_L4_CALC      0x00400000
   #define CSUM_INNER_L4_VALID     0x00800000
   #define CSUM_L3_CALC            0x01000000      /* calculated layer 3 csum */
   #define CSUM_L3_VALID           0x02000000      /* checksum is correct */
   #define CSUM_L4_CALC            0x04000000      /* calculated layer 4 csum */
   #define CSUM_L4_VALID           0x08000000      /* checksum is correct */
   #define CSUM_L5_CALC            0x10000000      /* calculated layer 5 csum */
   #define CSUM_L5_VALID           0x20000000      /* checksum is correct */
   #define CSUM_COALESCED          0x40000000      /* contains merged segments */
   
   #define CSUM_SND_TAG            0x80000000      /* Packet header has send tag */
   
   #define CSUM_FLAGS_TX (CSUM_IP | CSUM_IP_UDP | CSUM_IP_TCP | CSUM_IP_SCTP | \
       CSUM_IP_TSO | CSUM_IP_ISCSI | CSUM_INNER_IP6_UDP | CSUM_INNER_IP6_TCP | \
       CSUM_INNER_IP6_TSO | CSUM_IP6_UDP | CSUM_IP6_TCP | CSUM_IP6_SCTP | \
       CSUM_IP6_TSO | CSUM_IP6_ISCSI | CSUM_INNER_IP | CSUM_INNER_IP_UDP | \
       CSUM_INNER_IP_TCP | CSUM_INNER_IP_TSO | CSUM_ENCAP_VXLAN | \
       CSUM_ENCAP_RSVD1 | CSUM_SND_TAG)
   
   #define CSUM_FLAGS_RX (CSUM_INNER_L3_CALC | CSUM_INNER_L3_VALID | \
       CSUM_INNER_L4_CALC | CSUM_INNER_L4_VALID | CSUM_L3_CALC | CSUM_L3_VALID | \
       CSUM_L4_CALC | CSUM_L4_VALID | CSUM_L5_CALC | CSUM_L5_VALID | \
       CSUM_COALESCED)
   
   /*
    * CSUM flag description for use with printf(9) %b identifier.
    */
   #define CSUM_BITS \
       "\2\1CSUM_IP\2CSUM_IP_UDP\3CSUM_IP_TCP\4CSUM_IP_SCTP\5CSUM_IP_TSO" \
       "\6CSUM_IP_ISCSI\7CSUM_INNER_IP6_UDP\10CSUM_INNER_IP6_TCP" \
       "\11CSUM_INNER_IP6_TSO\12CSUM_IP6_UDP\13CSUM_IP6_TCP\14CSUM_IP6_SCTP" \
       "\15CSUM_IP6_TSO\16CSUM_IP6_ISCSI\17CSUM_INNER_IP\20CSUM_INNER_IP_UDP" \
       "\21CSUM_INNER_IP_TCP\22CSUM_INNER_IP_TSO\23CSUM_ENCAP_VXLAN" \
       "\24CSUM_ENCAP_RSVD1\25CSUM_INNER_L3_CALC\26CSUM_INNER_L3_VALID" \
       "\27CSUM_INNER_L4_CALC\30CSUM_INNER_L4_VALID\31CSUM_L3_CALC" \
       "\32CSUM_L3_VALID\33CSUM_L4_CALC\34CSUM_L4_VALID\35CSUM_L5_CALC" \
       "\36CSUM_L5_VALID\37CSUM_COALESCED\40CSUM_SND_TAG"
   
   /* CSUM flags compatibility mappings. */
   #define CSUM_IP_CHECKED         CSUM_L3_CALC
   #define CSUM_IP_VALID           CSUM_L3_VALID
   #define CSUM_DATA_VALID         CSUM_L4_VALID
   #define CSUM_PSEUDO_HDR         CSUM_L4_CALC
   #define CSUM_SCTP_VALID         CSUM_L4_VALID
   #define CSUM_DELAY_DATA         (CSUM_TCP|CSUM_UDP)
   #define CSUM_DELAY_IP           CSUM_IP         /* Only v4, no v6 IP hdr csum */
   #define CSUM_DELAY_DATA_IPV6    (CSUM_TCP_IPV6|CSUM_UDP_IPV6)
   #define CSUM_DATA_VALID_IPV6    CSUM_DATA_VALID
   #define CSUM_TCP                CSUM_IP_TCP
   #define CSUM_UDP                CSUM_IP_UDP
   #define CSUM_SCTP               CSUM_IP_SCTP
   #define CSUM_TSO                (CSUM_IP_TSO|CSUM_IP6_TSO)
   #define CSUM_INNER_TSO          (CSUM_INNER_IP_TSO|CSUM_INNER_IP6_TSO)
   #define CSUM_UDP_IPV6           CSUM_IP6_UDP
   #define CSUM_TCP_IPV6           CSUM_IP6_TCP
   #define CSUM_SCTP_IPV6          CSUM_IP6_SCTP
   
   /*
    * mbuf types describing the content of the mbuf (including external storage).
    */
   #define MT_NOTMBUF      0       /* USED INTERNALLY ONLY! Object is not mbuf */
   #define MT_DATA         1       /* dynamic (data) allocation */
   #define MT_HEADER       MT_DATA /* packet header, use M_PKTHDR instead */
   
   #define MT_VENDOR1      4       /* for vendor-internal use */
   #define MT_VENDOR2      5       /* for vendor-internal use */
   #define MT_VENDOR3      6       /* for vendor-internal use */
   #define MT_VENDOR4      7       /* for vendor-internal use */
   
   #define MT_SONAME       8       /* socket name */
   
   #define MT_EXP1         9       /* for experimental use */
   #define MT_EXP2         10      /* for experimental use */
   #define MT_EXP3         11      /* for experimental use */
   #define MT_EXP4         12      /* for experimental use */
   
   #define MT_CONTROL      14      /* extra-data protocol message */
   #define MT_EXTCONTROL   15      /* control message with externalized contents */
   #define MT_OOBDATA      16      /* expedited data  */
   
   #define MT_NOINIT       255     /* Not a type but a flag to allocate
                                      a non-initialized mbuf */
   
   /*
    * String names of mbuf-related UMA(9) and malloc(9) types.  Exposed to
    * !_KERNEL so that monitoring tools can look up the zones with
    * libmemstat(3).
    */
   #define MBUF_MEM_NAME           "mbuf"
   #define MBUF_CLUSTER_MEM_NAME   "mbuf_cluster"
   #define MBUF_PACKET_MEM_NAME    "mbuf_packet"
   #define MBUF_JUMBOP_MEM_NAME    "mbuf_jumbo_page"
   #define MBUF_JUMBO9_MEM_NAME    "mbuf_jumbo_9k"
   #define MBUF_JUMBO16_MEM_NAME   "mbuf_jumbo_16k"
   #define MBUF_TAG_MEM_NAME       "mbuf_tag"
   #define MBUF_EXTREFCNT_MEM_NAME "mbuf_ext_refcnt"
   
   #ifdef _KERNEL
   
   #ifdef WITNESS
   #define MBUF_CHECKSLEEP(how) do {                                       \
           if (how == M_WAITOK)                                            \
                   WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,         \
                       "Sleeping in \"%s\"", __func__);                    \
   } while (0)
   #else
   #define MBUF_CHECKSLEEP(how)
   #endif
   
   /*
    * Network buffer allocation API
    *
    * The rest of it is defined in kern/kern_mbuf.c
    */
   extern uma_zone_t       zone_mbuf;
   extern uma_zone_t       zone_clust;
   extern uma_zone_t       zone_pack;
   extern uma_zone_t       zone_jumbop;
   extern uma_zone_t       zone_jumbo9;
   extern uma_zone_t       zone_jumbo16;
   
   void             mb_dupcl(struct mbuf *, struct mbuf *);
   void             mb_free_ext(struct mbuf *);
   void             m_adj(struct mbuf *, int);
   void             m_adj_decap(struct mbuf *, int);
   int              m_apply(struct mbuf *, int, int,
                       int (*)(void *, void *, u_int), void *);
   int              m_append(struct mbuf *, int, c_caddr_t);
   void             m_cat(struct mbuf *, struct mbuf *);
   void             m_catpkt(struct mbuf *, struct mbuf *);
   int              m_clget(struct mbuf *m, int how);
   void            *m_cljget(struct mbuf *m, int how, int size);
   struct mbuf     *m_collapse(struct mbuf *, int, int);
   void             m_copyback(struct mbuf *, int, int, c_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_copyup(struct mbuf *, int, int);
   struct mbuf     *m_defrag(struct mbuf *, int);
   void             m_demote_pkthdr(struct mbuf *);
   void             m_demote(struct mbuf *, int, int);
   struct mbuf     *m_devget(char *, int, int, struct ifnet *,
                       void (*)(char *, caddr_t, u_int));
   void             m_dispose_extcontrolm(struct mbuf *m);
   struct mbuf     *m_dup(const struct mbuf *, int);
   int              m_dup_pkthdr(struct mbuf *, const struct mbuf *, int);
   void             m_extadd(struct mbuf *, char *, u_int, m_ext_free_t,
                       void *, void *, int, int);
   u_int            m_fixhdr(struct mbuf *);
   struct mbuf     *m_fragment(struct mbuf *, int, int);
   void             m_freem(struct mbuf *);
   struct mbuf     *m_get2(int, int, short, int);
   struct mbuf     *m_getjcl(int, short, int, int);
   struct mbuf     *m_getm2(struct mbuf *, int, int, short, int);
   struct mbuf     *m_getptr(struct mbuf *, int, int *);
   u_int            m_length(struct mbuf *, struct mbuf **);
   int              m_mbuftouio(struct uio *, const struct mbuf *, int);
   void             m_move_pkthdr(struct mbuf *, struct mbuf *);
   int              m_pkthdr_init(struct mbuf *, int);
   struct mbuf     *m_prepend(struct mbuf *, int, int);
   void             m_print(const struct mbuf *, int);
   struct mbuf     *m_pulldown(struct mbuf *, int, int, int *);
   struct mbuf     *m_pullup(struct mbuf *, int);
   int              m_sanity(struct mbuf *, int);
   struct mbuf     *m_split(struct mbuf *, int, int);
   struct mbuf     *m_uiotombuf(struct uio *, int, int, int, int);
   struct mbuf     *m_unshare(struct mbuf *, int);
   
   static __inline int
   m_gettype(int size)
   {
           int type;
   
           switch (size) {
           case MSIZE:
                   type = EXT_MBUF;
                   break;
           case MCLBYTES:
                   type = EXT_CLUSTER;
                   break;
   #if MJUMPAGESIZE != MCLBYTES
           case MJUMPAGESIZE:
                   type = EXT_JUMBOP;
                   break;
   #endif
           case MJUM9BYTES:
                   type = EXT_JUMBO9;
                   break;
           case MJUM16BYTES:
                   type = EXT_JUMBO16;
                   break;
           default:
                   panic("%s: invalid cluster size %d", __func__, size);
           }
   
           return (type);
   }
   
   /*
    * Associated an external reference counted buffer with an mbuf.
    */
   static __inline void
   m_extaddref(struct mbuf *m, char *buf, u_int size, u_int *ref_cnt,
       m_ext_free_t freef, void *arg1, void *arg2)
   {
   
           KASSERT(ref_cnt != NULL, ("%s: ref_cnt not provided", __func__));
   
           atomic_add_int(ref_cnt, 1);
           m->m_flags |= M_EXT;
           m->m_ext.ext_buf = buf;
           m->m_ext.ext_cnt = ref_cnt;
           m->m_data = m->m_ext.ext_buf;
           m->m_ext.ext_size = size;
           m->m_ext.ext_free = freef;
           m->m_ext.ext_arg1 = arg1;
           m->m_ext.ext_arg2 = arg2;
           m->m_ext.ext_type = EXT_EXTREF;
           m->m_ext.ext_flags = 0;
   }
   
   static __inline uma_zone_t
   m_getzone(int size)
   {
           uma_zone_t zone;
   
           switch (size) {
           case MCLBYTES:
                   zone = zone_clust;
                   break;
   #if MJUMPAGESIZE != MCLBYTES
           case MJUMPAGESIZE:
                   zone = zone_jumbop;
                   break;
   #endif
           case MJUM9BYTES:
                   zone = zone_jumbo9;
                   break;
           case MJUM16BYTES:
                   zone = zone_jumbo16;
                   break;
           default:
                   panic("%s: invalid cluster size %d", __func__, size);
           }
   
           return (zone);
   }
   
   /*
    * Initialize an mbuf with linear storage.
    *
    * Inline because the consumer text overhead will be roughly the same to
    * initialize or call a function with this many parameters and M_PKTHDR
    * should go away with constant propagation for !MGETHDR.
    */
   static __inline int
   m_init(struct mbuf *m, int how, short type, int flags)
   {
           int error;
   
           m->m_next = NULL;
           m->m_nextpkt = NULL;
           m->m_data = m->m_dat;
           m->m_len = 0;
           m->m_flags = flags;
           m->m_type = type;
           if (flags & M_PKTHDR)
                   error = m_pkthdr_init(m, how);
           else
                   error = 0;
   
           MBUF_PROBE5(m__init, m, how, type, flags, error);
           return (error);
   }
   
   static __inline struct mbuf *
   m_get(int how, short type)
   {
           struct mbuf *m;
           struct mb_args args;
   
           args.flags = 0;
           args.type = type;
           m = uma_zalloc_arg(zone_mbuf, &args, how);
           MBUF_PROBE3(m__get, how, type, m);
           return (m);
   }
   
   static __inline struct mbuf *
   m_gethdr(int how, short type)
   {
           struct mbuf *m;
           struct mb_args args;
   
           args.flags = M_PKTHDR;
           args.type = type;
           m = uma_zalloc_arg(zone_mbuf, &args, how);
           MBUF_PROBE3(m__gethdr, how, type, m);
           return (m);
   }
   
   static __inline struct mbuf *
   m_getcl(int how, short type, int flags)
   {
           struct mbuf *m;
           struct mb_args args;
   
           args.flags = flags;
           args.type = type;
           m = uma_zalloc_arg(zone_pack, &args, how);
           MBUF_PROBE4(m__getcl, how, type, flags, m);
           return (m);
   }
   
   /*
    * XXX: m_cljset() is a dangerous API.  One must attach only a new,
    * unreferenced cluster to an mbuf(9).  It is not possible to assert
    * that, so care can be taken only by users of the API.
    */
   static __inline void
   m_cljset(struct mbuf *m, void *cl, int type)
   {
           int size;
   
           switch (type) {
           case EXT_CLUSTER:
                   size = MCLBYTES;
                   break;
   #if MJUMPAGESIZE != MCLBYTES
           case EXT_JUMBOP:
                   size = MJUMPAGESIZE;
                   break;
   #endif
           case EXT_JUMBO9:
                   size = MJUM9BYTES;
                   break;
           case EXT_JUMBO16:
                   size = MJUM16BYTES;
                   break;
           default:
                   panic("%s: unknown cluster type %d", __func__, type);
                   break;
           }
   
           m->m_data = m->m_ext.ext_buf = cl;
           m->m_ext.ext_free = m->m_ext.ext_arg1 = m->m_ext.ext_arg2 = NULL;
           m->m_ext.ext_size = size;
           m->m_ext.ext_type = type;
           m->m_ext.ext_flags = EXT_FLAG_EMBREF;
           m->m_ext.ext_count = 1;
           m->m_flags |= M_EXT;
           MBUF_PROBE3(m__cljset, m, cl, type);
   }
   
   static __inline void
   m_chtype(struct mbuf *m, short new_type)
   {
   
           m->m_type = new_type;
   }
   
   static __inline void
   m_clrprotoflags(struct mbuf *m)
   {
   
           while (m) {
                   m->m_flags &= ~M_PROTOFLAGS;
                   m = m->m_next;
           }
   }
   
   static __inline struct mbuf *
   m_last(struct mbuf *m)
   {
   
           while (m->m_next)
                   m = m->m_next;
           return (m);
   }
   
   static inline u_int
   m_extrefcnt(struct mbuf *m)
   {
   
           KASSERT(m->m_flags & M_EXT, ("%s: M_EXT missing", __func__));
   
           return ((m->m_ext.ext_flags & EXT_FLAG_EMBREF) ? m->m_ext.ext_count :
               *m->m_ext.ext_cnt);
   }
   
   /*
    * mbuf, cluster, and external object allocation macros (for compatibility
    * purposes).
    */
   #define M_MOVE_PKTHDR(to, from) m_move_pkthdr((to), (from))
   #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, arg1, arg2, flags, type)            \
       m_extadd((m), (char *)(buf), (size), (free), (arg1), (arg2),        \
       (flags), (type))
   #define m_getm(m, len, how, type)                                       \
       m_getm2((m), (len), (how), (type), M_PKTHDR)
   
   /*
    * 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)) ||                  \
                            (m_extrefcnt(m) == 1)))
   
   /* Check if the supplied mbuf has a packet header, or else panic. */
   #define M_ASSERTPKTHDR(m)                                               \
           KASSERT((m) != NULL && (m)->m_flags & M_PKTHDR,                 \
               ("%s: no mbuf packet header!", __func__))
   
   /*
    * Ensure that the supplied mbuf is a valid, non-free mbuf.
    *
    * XXX: Broken at the moment.  Need some UMA magic to make it work again.
    */
   #define M_ASSERTVALID(m)                                                \
           KASSERT((((struct mbuf *)m)->m_flags & 0) == 0,                 \
               ("%s: attempted use of a free mbuf!", __func__))
   
   /*
    * Return the address of the start of the buffer associated with an mbuf,
    * handling external storage, packet-header mbufs, and regular data mbufs.
    */
   #define M_START(m)                                                      \
           (((m)->m_flags & M_EXT) ? (m)->m_ext.ext_buf :                  \
            ((m)->m_flags & M_PKTHDR) ? &(m)->m_pktdat[0] :                \
            &(m)->m_dat[0])
   
   /*
    * Return the size of the buffer associated with an mbuf, handling external
    * storage, packet-header mbufs, and regular data mbufs.
    */
   #define M_SIZE(m)                                                       \
           (((m)->m_flags & M_EXT) ? (m)->m_ext.ext_size :                 \
            ((m)->m_flags & M_PKTHDR) ? MHLEN :                            \
            MLEN)
   
   /*
    * Set the m_data pointer of a newly allocated mbuf to place an object of the
    * specified size at the end of the mbuf, longword aligned.
    *
    * NB: Historically, we had M_ALIGN(), MH_ALIGN(), and MEXT_ALIGN() as
    * separate macros, each asserting that it was called at the proper moment.
    * This required callers to themselves test the storage type and call the
    * right one.  Rather than require callers to be aware of those layout
    * decisions, we centralize here.
    */
   static __inline void
  m_align(struct mbuf *m, int len)
  {
  #ifdef INVARIANTS
          const char *msg = "%s: not a virgin mbuf";
  #endif
          int adjust;
  
          KASSERT(m->m_data == M_START(m), (msg, __func__));
  
          adjust = M_SIZE(m) - len;
          m->m_data += adjust &~ (sizeof(long)-1);
  }
  
  #define M_ALIGN(m, len)         m_align(m, len)
  #define MH_ALIGN(m, len)        m_align(m, len)
  #define MEXT_ALIGN(m, len)      m_align(m, len)
  
  /*
   * 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.
   *
   * NB: In previous versions, M_LEADINGSPACE() would only check M_WRITABLE()
   * for mbufs with external storage.  We now allow mbuf-embedded data to be
   * read-only as well.
   */
  #define M_LEADINGSPACE(m)                                               \
          (M_WRITABLE(m) ? ((m)->m_data - M_START(m)) : 0)
  
  /*
   * 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.
   *
   * NB: In previous versions, M_TRAILINGSPACE() would only check M_WRITABLE()
   * for mbufs with external storage.  We now allow mbuf-embedded data to be
   * read-only as well.
   */
  #define M_TRAILINGSPACE(m)                                              \
          (M_WRITABLE(m) ?                                                \
              ((M_START(m) + M_SIZE(m)) - ((m)->m_data + (m)->m_len)) : 0)
  
  /*
   * 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);                                             \
                                                                          \
          MBUF_CHECKSLEEP(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
  
  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 int              nmbclusters;    /* Maximum number of clusters */
  
  /*-
   * Network 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 chosen 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_alloc has the default memory
   * alignment implemented by malloc.  To reference private data one can use a
   * construct like:
   *
   *      struct m_tag *mtag = m_tag_alloc(...);
   *      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_alloc(...);
   *      struct m_tag *mtag = &p->tag;
   */
  
  /*
   * Persistent tags stay with an mbuf until the mbuf is reclaimed.  Otherwise
   * tags are expected to ``vanish'' when they pass through a network
   * interface.  For most interfaces this happens normally as the tags are
   * reclaimed when the mbuf is free'd.  However in some special cases
   * reclaiming must be done manually.  An example is packets that pass through
   * the loopback interface.  Also, one must be careful to do this when
   * ``turning around'' packets (e.g., icmp_reflect).
   *
   * To mark a tag persistent bit-or this flag in when defining the tag id.
   * The tag will then be treated as described above.
   */
  #define MTAG_PERSISTENT                         0x800
  
  #define PACKET_TAG_NONE                         0  /* Nadda */
  
  /* Packet tags 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 */
  #define PACKET_TAG_DUMMYNET                     15 /* dummynet info */
  #define PACKET_TAG_DIVERT                       17 /* divert info */
  #define PACKET_TAG_IPFORWARD                    18 /* ipforward info */
  #define PACKET_TAG_MACLABEL     (19 | MTAG_PERSISTENT) /* MAC label */
  #define PACKET_TAG_PF                           21 /* PF/ALTQ information */
  #define PACKET_TAG_RTSOCKFAM                    25 /* rtsock sa family */
  #define PACKET_TAG_IPOPTIONS                    27 /* Saved IP options */
  #define PACKET_TAG_CARP                         28 /* CARP info */
  #define PACKET_TAG_IPSEC_NAT_T_PORTS            29 /* two uint16_t */
  #define PACKET_TAG_ND_OUTGOING                  30 /* ND outgoing */
  
  /* Specific cookies and tags. */
  
  /* Packet tag routines. */
  struct m_tag    *m_tag_alloc(u_int32_t, int, int, int);
  void             m_tag_delete(struct mbuf *, struct m_tag *);
  void             m_tag_delete_chain(struct mbuf *, struct m_tag *);
  void             m_tag_free_default(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 *, const struct mbuf *, int);
  void             m_tag_delete_nonpersistent(struct mbuf *);
  
  /*
   * Initialize the list of tags associated with an mbuf.
   */
  static __inline void
  m_tag_init(struct mbuf *m)
  {
  
          SLIST_INIT(&m->m_pkthdr.tags);
  }
  
  /*
   * Set up the contents of a tag.  Note that this does not fill in the free
   * method; the caller is expected to do that.
   *
   * XXX probably should be called m_tag_init, but that was already taken.
   */
  static __inline void
  m_tag_setup(struct m_tag *t, u_int32_t cookie, int type, int len)
  {
  
          t->m_tag_id = type;
          t->m_tag_len = len;
          t->m_tag_cookie = cookie;
  }
  
  /*
   * Reclaim resources associated with a tag.
   */
  static __inline void
  m_tag_free(struct m_tag *t)
  {
  
          (*t->m_tag_free)(t);
  }
  
  /*
   * Return the first tag associated with an mbuf.
   */
  static __inline struct m_tag *
  m_tag_first(struct mbuf *m)
  {
  
          return (SLIST_FIRST(&m->m_pkthdr.tags));
  }
  
  /*
   * Return the next tag in the list of tags associated with an mbuf.
   */
  static __inline struct m_tag *
  m_tag_next(struct mbuf *m __unused, struct m_tag *t)
  {
  
          return (SLIST_NEXT(t, m_tag_link));
  }
  
  /*
   * Prepend a tag to the list of tags associated with an mbuf.
   */
  static __inline void
  m_tag_prepend(struct mbuf *m, struct m_tag *t)
  {
  
          SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
  }
  
  /*
   * Unlink a tag from the list of tags associated with an mbuf.
   */
  static __inline void
  m_tag_unlink(struct mbuf *m, struct m_tag *t)
  {
  
          SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
  }
  
  /* 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 (SLIST_EMPTY(&m->m_pkthdr.tags) ? (struct m_tag *)NULL :
              m_tag_locate(m, MTAG_ABI_COMPAT, type, start));
  }
  
  static __inline struct mbuf *
  m_free(struct mbuf *m)
  {
          struct mbuf *n = m->m_next;
  
          MBUF_PROBE1(m__free, m);
          if ((m->m_flags & (M_PKTHDR|M_NOFREE)) == (M_PKTHDR|M_NOFREE))
                  m_tag_delete_chain(m, NULL);
          if (m->m_flags & M_EXT)
                  mb_free_ext(m);
          else if ((m->m_flags & M_NOFREE) == 0)
                  uma_zfree(zone_mbuf, m);
          return (n);
  }
  
  static __inline int
  rt_m_getfib(struct mbuf *m)
  {
          KASSERT(m->m_flags & M_PKTHDR , ("Attempt to get FIB from non header mbuf."));
          return (m->m_pkthdr.fibnum);
  }
  
  #define M_GETFIB(_m)   rt_m_getfib(_m)
  
  #define M_SETFIB(_m, _fib) do {                                         \
          KASSERT((_m)->m_flags & M_PKTHDR, ("Attempt to set FIB on non header mbuf."));  \
          ((_m)->m_pkthdr.fibnum) = (_fib);                               \
  } while (0)
  
  /* flags passed as first argument for "m_xxx_tcpip_hash()" */
  #define MBUF_HASHFLAG_L2        (1 << 2)
  #define MBUF_HASHFLAG_L3        (1 << 3)
  #define MBUF_HASHFLAG_L4        (1 << 4)
  
  /* mbuf hashing helper routines */
  uint32_t        m_ether_tcpip_hash_init(void);
  uint32_t        m_ether_tcpip_hash(const uint32_t, const struct mbuf *, uint32_t);
  uint32_t        m_infiniband_tcpip_hash_init(void);
  uint32_t        m_infiniband_tcpip_hash(const uint32_t, const struct mbuf *, uint32_t);
  
  #ifdef MBUF_PROFILING
   void m_profile(struct mbuf *m);
   #define M_PROFILE(m) m_profile(m)
  #else
   #define M_PROFILE(m)
  #endif
  
  struct mbufq {
          STAILQ_HEAD(, mbuf)     mq_head;
          int                     mq_len;
          int                     mq_maxlen;
  };
  
  static inline void
  mbufq_init(struct mbufq *mq, int maxlen)
  {
  
          STAILQ_INIT(&mq->mq_head);
          mq->mq_maxlen = maxlen;
          mq->mq_len = 0;
  }
  
  static inline struct mbuf *
  mbufq_flush(struct mbufq *mq)
  {
          struct mbuf *m;
  
          m = STAILQ_FIRST(&mq->mq_head);
          STAILQ_INIT(&mq->mq_head);
          mq->mq_len = 0;
          return (m);
  }
  
  static inline void
  mbufq_drain(struct mbufq *mq)
  {
          struct mbuf *m, *n;
  
          n = mbufq_flush(mq);
          while ((m = n) != NULL) {
                  n = STAILQ_NEXT(m, m_stailqpkt);
                  m_freem(m);
          }
  }
  
  static inline struct mbuf *
  mbufq_first(const struct mbufq *mq)
  {
  
          return (STAILQ_FIRST(&mq->mq_head));
  }
  
  static inline struct mbuf *
  mbufq_last(const struct mbufq *mq)
  {
  
          return (STAILQ_LAST(&mq->mq_head, mbuf, m_stailqpkt));
  }
  
  static inline int
  mbufq_full(const struct mbufq *mq)
  {
  
          return (mq->mq_len >= mq->mq_maxlen);
  }
  
  static inline int
  mbufq_len(const struct mbufq *mq)
  {
  
          return (mq->mq_len);
  }
  
  static inline int
  mbufq_enqueue(struct mbufq *mq, struct mbuf *m)
  {
  
          if (mbufq_full(mq))
                  return (ENOBUFS);
          STAILQ_INSERT_TAIL(&mq->mq_head, m, m_stailqpkt);
          mq->mq_len++;
          return (0);
  }
  
  static inline struct mbuf *
  mbufq_dequeue(struct mbufq *mq)
  {
          struct mbuf *m;
  
          m = STAILQ_FIRST(&mq->mq_head);
          if (m) {
                  STAILQ_REMOVE_HEAD(&mq->mq_head, m_stailqpkt);
                  m->m_nextpkt = NULL;
                  mq->mq_len--;
          }
          return (m);
  }
  
  static inline void
  mbufq_prepend(struct mbufq *mq, struct mbuf *m)
  {
  
          STAILQ_INSERT_HEAD(&mq->mq_head, m, m_stailqpkt);
          mq->mq_len++;
  }
  
  /*
   * Note: this doesn't enforce the maximum list size for dst.
   */
  static inline void
  mbufq_concat(struct mbufq *mq_dst, struct mbufq *mq_src)
  {
  
          mq_dst->mq_len += mq_src->mq_len;
          STAILQ_CONCAT(&mq_dst->mq_head, &mq_src->mq_head);
          mq_src->mq_len = 0;
  }
  
  #ifdef _SYS_TIMESPEC_H_
  static inline void
  mbuf_tstmp2timespec(struct mbuf *m, struct timespec *ts)
  {
  
          KASSERT((m->m_flags & M_PKTHDR) != 0, ("mbuf %p no M_PKTHDR", m));
          KASSERT((m->m_flags & M_TSTMP) != 0, ("mbuf %p no M_TSTMP", m));
          ts->tv_sec = m->m_pkthdr.rcv_tstmp / 1000000000;
          ts->tv_nsec = m->m_pkthdr.rcv_tstmp % 1000000000;
  }
  #endif
  
  #ifdef NETDUMP
  /* Invoked from the netdump client code. */
  void    netdump_mbuf_drain(void);
  void    netdump_mbuf_dump(void);
  void    netdump_mbuf_reinit(int nmbuf, int nclust, int clsize);
  #endif
  
  #endif /* _KERNEL */
  #endif /* !_SYS_MBUF_H_ */

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