rte_mbuf.h

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/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   Copyright 2014 6WIND S.A.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of Intel Corporation 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 COPYRIGHT HOLDERS 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 COPYRIGHT
 *   OWNER 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.
 */

#ifndef _RTE_MBUF_H_
#define _RTE_MBUF_H_

#include <stdint.h>
#include <rte_common.h>
#include <rte_mempool.h>
#include <rte_memory.h>
#include <rte_atomic.h>
#include <rte_prefetch.h>
#include <rte_branch_prediction.h>
#include <rte_mbuf_ptype.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Packet Offload Features Flags. It also carry packet type information.
 * Critical resources. Both rx/tx shared these bits. Be cautious on any change
 *
 * - RX flags start at bit position zero, and get added to the left of previous
 *   flags.
 * - The most-significant 3 bits are reserved for generic mbuf flags
 * - TX flags therefore start at bit position 60 (i.e. 63-3), and new flags get
 *   added to the right of the previously defined flags i.e. they should count
 *   downwards, not upwards.
 *
 * Keep these flags synchronized with rte_get_rx_ol_flag_name() and
 * rte_get_tx_ol_flag_name().
 */

#define PKT_RX_VLAN_PKT      (1ULL << 0)

#define PKT_RX_RSS_HASH      (1ULL << 1)  
#define PKT_RX_FDIR          (1ULL << 2)  
#define PKT_RX_L4_CKSUM_BAD  (1ULL << 3)

#define PKT_RX_IP_CKSUM_BAD  (1ULL << 4)

#define PKT_RX_EIP_CKSUM_BAD (1ULL << 5)  
#define PKT_RX_VLAN_STRIPPED (1ULL << 6)

#define PKT_RX_IP_CKSUM_MASK ((1ULL << 4) | (1ULL << 7))

#define PKT_RX_IP_CKSUM_UNKNOWN 0
#define PKT_RX_IP_CKSUM_BAD     (1ULL << 4)
#define PKT_RX_IP_CKSUM_GOOD    (1ULL << 7)
#define PKT_RX_IP_CKSUM_NONE    ((1ULL << 4) | (1ULL << 7))

#define PKT_RX_L4_CKSUM_MASK ((1ULL << 3) | (1ULL << 8))

#define PKT_RX_L4_CKSUM_UNKNOWN 0
#define PKT_RX_L4_CKSUM_BAD     (1ULL << 3)
#define PKT_RX_L4_CKSUM_GOOD    (1ULL << 8)
#define PKT_RX_L4_CKSUM_NONE    ((1ULL << 3) | (1ULL << 8))

#define PKT_RX_IEEE1588_PTP  (1ULL << 9)  
#define PKT_RX_IEEE1588_TMST (1ULL << 10) 
#define PKT_RX_FDIR_ID       (1ULL << 13) 
#define PKT_RX_FDIR_FLX      (1ULL << 14) 
#define PKT_RX_QINQ_STRIPPED (1ULL << 15)

#define PKT_RX_QINQ_PKT      PKT_RX_QINQ_STRIPPED

#define PKT_RX_LRO           (1ULL << 16)

/* add new RX flags here */

/* add new TX flags here */

#define PKT_TX_TUNNEL_VXLAN   (0x1ULL << 45)
#define PKT_TX_TUNNEL_GRE     (0x2ULL << 45)
#define PKT_TX_TUNNEL_IPIP    (0x3ULL << 45)
#define PKT_TX_TUNNEL_GENEVE  (0x4ULL << 45)
/* add new TX TUNNEL type here */
#define PKT_TX_TUNNEL_MASK    (0xFULL << 45)

#define PKT_TX_QINQ_PKT    (1ULL << 49)   
#define PKT_TX_TCP_SEG       (1ULL << 50)

#define PKT_TX_IEEE1588_TMST (1ULL << 51) 
#define PKT_TX_L4_NO_CKSUM   (0ULL << 52) 
#define PKT_TX_TCP_CKSUM     (1ULL << 52) 
#define PKT_TX_SCTP_CKSUM    (2ULL << 52) 
#define PKT_TX_UDP_CKSUM     (3ULL << 52) 
#define PKT_TX_L4_MASK       (3ULL << 52) 
#define PKT_TX_IP_CKSUM      (1ULL << 54)

#define PKT_TX_IPV4          (1ULL << 55)

#define PKT_TX_IPV6          (1ULL << 56)

#define PKT_TX_VLAN_PKT      (1ULL << 57) 
#define PKT_TX_OUTER_IP_CKSUM   (1ULL << 58)

#define PKT_TX_OUTER_IPV4   (1ULL << 59)

#define PKT_TX_OUTER_IPV6    (1ULL << 60)

#define __RESERVED           (1ULL << 61) 
#define IND_ATTACHED_MBUF    (1ULL << 62) 
/* Use final bit of flags to indicate a control mbuf */
#define CTRL_MBUF_FLAG       (1ULL << 63) 
#define RTE_MBUF_PRIV_ALIGN 8

const char *rte_get_rx_ol_flag_name(uint64_t mask);

int rte_get_rx_ol_flag_list(uint64_t mask, char *buf, size_t buflen);

const char *rte_get_tx_ol_flag_name(uint64_t mask);

int rte_get_tx_ol_flag_list(uint64_t mask, char *buf, size_t buflen);

#define RTE_MBUF_DEFAULT_DATAROOM   2048
#define RTE_MBUF_DEFAULT_BUF_SIZE   \
    (RTE_MBUF_DEFAULT_DATAROOM + RTE_PKTMBUF_HEADROOM)

/* define a set of marker types that can be used to refer to set points in the
 * mbuf */
__extension__
typedef void    *MARKER[0];   
__extension__
typedef uint8_t  MARKER8[0];  
__extension__
typedef uint64_t MARKER64[0]; 
struct rte_mbuf {
    MARKER cacheline0;

    void *buf_addr;           
    phys_addr_t buf_physaddr; 
    uint16_t buf_len;         
    /* next 6 bytes are initialised on RX descriptor rearm */
    MARKER8 rearm_data;
    uint16_t data_off;

    RTE_STD_C11
    union {
        rte_atomic16_t refcnt_atomic; 
        uint16_t refcnt;              
    };
    uint8_t nb_segs;          
    uint8_t port;             
    uint64_t ol_flags;        
    /* remaining bytes are set on RX when pulling packet from descriptor */
    MARKER rx_descriptor_fields1;

    /*
     * The packet type, which is the combination of outer/inner L2, L3, L4
     * and tunnel types. The packet_type is about data really present in the
     * mbuf. Example: if vlan stripping is enabled, a received vlan packet
     * would have RTE_PTYPE_L2_ETHER and not RTE_PTYPE_L2_VLAN because the
     * vlan is stripped from the data.
     */
    RTE_STD_C11
    union {
        uint32_t packet_type; 
        struct {
            uint32_t l2_type:4; 
            uint32_t l3_type:4; 
            uint32_t l4_type:4; 
            uint32_t tun_type:4; 
            uint32_t inner_l2_type:4; 
            uint32_t inner_l3_type:4; 
            uint32_t inner_l4_type:4; 
        };
    };

    uint32_t pkt_len;         
    uint16_t data_len;        
    uint16_t vlan_tci;

    union {
        uint32_t rss;     
        struct {
            RTE_STD_C11
            union {
                struct {
                    uint16_t hash;
                    uint16_t id;
                };
                uint32_t lo;
            };
            uint32_t hi;
        } fdir;           
        struct {
            uint32_t lo;
            uint32_t hi;
        } sched;          
        uint32_t usr;     
    } hash;                   
    uint32_t seqn; 
    uint16_t vlan_tci_outer;

    /* second cache line - fields only used in slow path or on TX */
    MARKER cacheline1 __rte_cache_min_aligned;

    RTE_STD_C11
    union {
        void *userdata;   
        uint64_t udata64; 
    };

    struct rte_mempool *pool; 
    struct rte_mbuf *next;    
    /* fields to support TX offloads */
    RTE_STD_C11
    union {
        uint64_t tx_offload;       
        __extension__
        struct {
            uint64_t l2_len:7;
            uint64_t l3_len:9; 
            uint64_t l4_len:8; 
            uint64_t tso_segsz:16; 
            /* fields for TX offloading of tunnels */
            uint64_t outer_l3_len:9; 
            uint64_t outer_l2_len:7; 
            /* uint64_t unused:8; */
        };
    };

    uint16_t priv_size;

    uint16_t timesync;
} __rte_cache_aligned;

static inline void
rte_mbuf_prefetch_part1(struct rte_mbuf *m)
{
    rte_prefetch0(&m->cacheline0);
}

static inline void
rte_mbuf_prefetch_part2(struct rte_mbuf *m)
{
#if RTE_CACHE_LINE_SIZE == 64
    rte_prefetch0(&m->cacheline1);
#else
    RTE_SET_USED(m);
#endif
}


static inline uint16_t rte_pktmbuf_priv_size(struct rte_mempool *mp);

static inline phys_addr_t
rte_mbuf_data_dma_addr(const struct rte_mbuf *mb)
{
    return mb->buf_physaddr + mb->data_off;
}

static inline phys_addr_t
rte_mbuf_data_dma_addr_default(const struct rte_mbuf *mb)
{
    return mb->buf_physaddr + RTE_PKTMBUF_HEADROOM;
}

static inline struct rte_mbuf *
rte_mbuf_from_indirect(struct rte_mbuf *mi)
{
    return (struct rte_mbuf *)RTE_PTR_SUB(mi->buf_addr, sizeof(*mi) + mi->priv_size);
}

static inline char *
rte_mbuf_to_baddr(struct rte_mbuf *md)
{
    char *buffer_addr;
    buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
    return buffer_addr;
}

#define RTE_MBUF_INDIRECT(mb)   ((mb)->ol_flags & IND_ATTACHED_MBUF)

#define RTE_MBUF_DIRECT(mb)     (!RTE_MBUF_INDIRECT(mb))

struct rte_pktmbuf_pool_private {
    uint16_t mbuf_data_room_size; 
    uint16_t mbuf_priv_size;      
};

#ifdef RTE_LIBRTE_MBUF_DEBUG

#define __rte_mbuf_sanity_check(m, is_h) rte_mbuf_sanity_check(m, is_h)

#else /*  RTE_LIBRTE_MBUF_DEBUG */

#define __rte_mbuf_sanity_check(m, is_h) do { } while (0)

#endif /*  RTE_LIBRTE_MBUF_DEBUG */

#ifdef RTE_MBUF_REFCNT_ATOMIC

static inline uint16_t
rte_mbuf_refcnt_read(const struct rte_mbuf *m)
{
    return (uint16_t)(rte_atomic16_read(&m->refcnt_atomic));
}

static inline void
rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
{
    rte_atomic16_set(&m->refcnt_atomic, (int16_t)new_value);
}

static inline uint16_t
rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value)
{
    /*
     * The atomic_add is an expensive operation, so we don't want to
     * call it in the case where we know we are the uniq holder of
     * this mbuf (i.e. ref_cnt == 1). Otherwise, an atomic
     * operation has to be used because concurrent accesses on the
     * reference counter can occur.
     */
    if (likely(rte_mbuf_refcnt_read(m) == 1)) {
        ++value;
        rte_mbuf_refcnt_set(m, (uint16_t)value);
        return (uint16_t)value;
    }

    return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value));
}

#else /* ! RTE_MBUF_REFCNT_ATOMIC */

static inline uint16_t
rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value)
{
    m->refcnt = (uint16_t)(m->refcnt + value);
    return m->refcnt;
}

static inline uint16_t
rte_mbuf_refcnt_read(const struct rte_mbuf *m)
{
    return m->refcnt;
}

static inline void
rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
{
    m->refcnt = new_value;
}

#endif /* RTE_MBUF_REFCNT_ATOMIC */

#define RTE_MBUF_PREFETCH_TO_FREE(m) do {       \
    if ((m) != NULL)                        \
        rte_prefetch0(m);               \
} while (0)


void
rte_mbuf_sanity_check(const struct rte_mbuf *m, int is_header);

static inline struct rte_mbuf *rte_mbuf_raw_alloc(struct rte_mempool *mp)
{
    struct rte_mbuf *m;
    void *mb = NULL;

    if (rte_mempool_get(mp, &mb) < 0)
        return NULL;
    m = (struct rte_mbuf *)mb;
    RTE_ASSERT(rte_mbuf_refcnt_read(m) == 0);
    rte_mbuf_refcnt_set(m, 1);
    __rte_mbuf_sanity_check(m, 0);

    return m;
}

static inline void __attribute__((always_inline))
__rte_mbuf_raw_free(struct rte_mbuf *m)
{
    RTE_ASSERT(rte_mbuf_refcnt_read(m) == 0);
    rte_mempool_put(m->pool, m);
}

/* Operations on ctrl mbuf */

void rte_ctrlmbuf_init(struct rte_mempool *mp, void *opaque_arg,
        void *m, unsigned i);

#define rte_ctrlmbuf_alloc(mp) rte_pktmbuf_alloc(mp)

#define rte_ctrlmbuf_free(m) rte_pktmbuf_free(m)

#define rte_ctrlmbuf_data(m) ((char *)((m)->buf_addr) + (m)->data_off)

#define rte_ctrlmbuf_len(m) rte_pktmbuf_data_len(m)

static inline int
rte_is_ctrlmbuf(struct rte_mbuf *m)
{
    return !!(m->ol_flags & CTRL_MBUF_FLAG);
}

/* Operations on pkt mbuf */

void rte_pktmbuf_init(struct rte_mempool *mp, void *opaque_arg,
              void *m, unsigned i);


void rte_pktmbuf_pool_init(struct rte_mempool *mp, void *opaque_arg);

struct rte_mempool *
rte_pktmbuf_pool_create(const char *name, unsigned n,
    unsigned cache_size, uint16_t priv_size, uint16_t data_room_size,
    int socket_id);

static inline uint16_t
rte_pktmbuf_data_room_size(struct rte_mempool *mp)
{
    struct rte_pktmbuf_pool_private *mbp_priv;

    mbp_priv = (struct rte_pktmbuf_pool_private *)rte_mempool_get_priv(mp);
    return mbp_priv->mbuf_data_room_size;
}

static inline uint16_t
rte_pktmbuf_priv_size(struct rte_mempool *mp)
{
    struct rte_pktmbuf_pool_private *mbp_priv;

    mbp_priv = (struct rte_pktmbuf_pool_private *)rte_mempool_get_priv(mp);
    return mbp_priv->mbuf_priv_size;
}

static inline void rte_pktmbuf_reset_headroom(struct rte_mbuf *m)
{
    m->data_off = (uint16_t)RTE_MIN((uint16_t)RTE_PKTMBUF_HEADROOM,
                    (uint16_t)m->buf_len);
}

static inline void rte_pktmbuf_reset(struct rte_mbuf *m)
{
    m->next = NULL;
    m->pkt_len = 0;
    m->tx_offload = 0;
    m->vlan_tci = 0;
    m->vlan_tci_outer = 0;
    m->nb_segs = 1;
    m->port = 0xff;

    m->ol_flags = 0;
    m->packet_type = 0;
    rte_pktmbuf_reset_headroom(m);

    m->data_len = 0;
    __rte_mbuf_sanity_check(m, 1);
}

static inline struct rte_mbuf *rte_pktmbuf_alloc(struct rte_mempool *mp)
{
    struct rte_mbuf *m;
    if ((m = rte_mbuf_raw_alloc(mp)) != NULL)
        rte_pktmbuf_reset(m);
    return m;
}

static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool,
     struct rte_mbuf **mbufs, unsigned count)
{
    unsigned idx = 0;
    int rc;

    rc = rte_mempool_get_bulk(pool, (void **)mbufs, count);
    if (unlikely(rc))
        return rc;

    /* To understand duff's device on loop unwinding optimization, see
     * https://en.wikipedia.org/wiki/Duff's_device.
     * Here while() loop is used rather than do() while{} to avoid extra
     * check if count is zero.
     */
    switch (count % 4) {
    case 0:
        while (idx != count) {
            RTE_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
            rte_mbuf_refcnt_set(mbufs[idx], 1);
            rte_pktmbuf_reset(mbufs[idx]);
            idx++;
    case 3:
            RTE_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
            rte_mbuf_refcnt_set(mbufs[idx], 1);
            rte_pktmbuf_reset(mbufs[idx]);
            idx++;
    case 2:
            RTE_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
            rte_mbuf_refcnt_set(mbufs[idx], 1);
            rte_pktmbuf_reset(mbufs[idx]);
            idx++;
    case 1:
            RTE_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
            rte_mbuf_refcnt_set(mbufs[idx], 1);
            rte_pktmbuf_reset(mbufs[idx]);
            idx++;
        }
    }
    return 0;
}

static inline void rte_pktmbuf_attach(struct rte_mbuf *mi, struct rte_mbuf *m)
{
    struct rte_mbuf *md;

    RTE_ASSERT(RTE_MBUF_DIRECT(mi) &&
        rte_mbuf_refcnt_read(mi) == 1);

    /* if m is not direct, get the mbuf that embeds the data */
    if (RTE_MBUF_DIRECT(m))
        md = m;
    else
        md = rte_mbuf_from_indirect(m);

    rte_mbuf_refcnt_update(md, 1);
    mi->priv_size = m->priv_size;
    mi->buf_physaddr = m->buf_physaddr;
    mi->buf_addr = m->buf_addr;
    mi->buf_len = m->buf_len;

    mi->next = m->next;
    mi->data_off = m->data_off;
    mi->data_len = m->data_len;
    mi->port = m->port;
    mi->vlan_tci = m->vlan_tci;
    mi->vlan_tci_outer = m->vlan_tci_outer;
    mi->tx_offload = m->tx_offload;
    mi->hash = m->hash;

    mi->next = NULL;
    mi->pkt_len = mi->data_len;
    mi->nb_segs = 1;
    mi->ol_flags = m->ol_flags | IND_ATTACHED_MBUF;
    mi->packet_type = m->packet_type;

    __rte_mbuf_sanity_check(mi, 1);
    __rte_mbuf_sanity_check(m, 0);
}

static inline void rte_pktmbuf_detach(struct rte_mbuf *m)
{
    struct rte_mbuf *md = rte_mbuf_from_indirect(m);
    struct rte_mempool *mp = m->pool;
    uint32_t mbuf_size, buf_len;
    uint16_t priv_size;

    priv_size = rte_pktmbuf_priv_size(mp);
    mbuf_size = (uint32_t)(sizeof(struct rte_mbuf) + priv_size);
    buf_len = rte_pktmbuf_data_room_size(mp);

    m->priv_size = priv_size;
    m->buf_addr = (char *)m + mbuf_size;
    m->buf_physaddr = rte_mempool_virt2phy(mp, m) + mbuf_size;
    m->buf_len = (uint16_t)buf_len;
    rte_pktmbuf_reset_headroom(m);
    m->data_len = 0;
    m->ol_flags = 0;

    if (rte_mbuf_refcnt_update(md, -1) == 0)
        __rte_mbuf_raw_free(md);
}

static inline struct rte_mbuf* __attribute__((always_inline))
__rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
{
    __rte_mbuf_sanity_check(m, 0);

    if (likely(rte_mbuf_refcnt_update(m, -1) == 0)) {
        /* if this is an indirect mbuf, it is detached. */
        if (RTE_MBUF_INDIRECT(m))
            rte_pktmbuf_detach(m);
        return m;
    }
    return NULL;
}

static inline void __attribute__((always_inline))
rte_pktmbuf_free_seg(struct rte_mbuf *m)
{
    if (likely(NULL != (m = __rte_pktmbuf_prefree_seg(m)))) {
        m->next = NULL;
        __rte_mbuf_raw_free(m);
    }
}

static inline void rte_pktmbuf_free(struct rte_mbuf *m)
{
    struct rte_mbuf *m_next;

    if (m != NULL)
        __rte_mbuf_sanity_check(m, 1);

    while (m != NULL) {
        m_next = m->next;
        rte_pktmbuf_free_seg(m);
        m = m_next;
    }
}

static inline struct rte_mbuf *rte_pktmbuf_clone(struct rte_mbuf *md,
        struct rte_mempool *mp)
{
    struct rte_mbuf *mc, *mi, **prev;
    uint32_t pktlen;
    uint8_t nseg;

    if (unlikely ((mc = rte_pktmbuf_alloc(mp)) == NULL))
        return NULL;

    mi = mc;
    prev = &mi->next;
    pktlen = md->pkt_len;
    nseg = 0;

    do {
        nseg++;
        rte_pktmbuf_attach(mi, md);
        *prev = mi;
        prev = &mi->next;
    } while ((md = md->next) != NULL &&
        (mi = rte_pktmbuf_alloc(mp)) != NULL);

    *prev = NULL;
    mc->nb_segs = nseg;
    mc->pkt_len = pktlen;

    /* Allocation of new indirect segment failed */
    if (unlikely (mi == NULL)) {
        rte_pktmbuf_free(mc);
        return NULL;
    }

    __rte_mbuf_sanity_check(mc, 1);
    return mc;
}

static inline void rte_pktmbuf_refcnt_update(struct rte_mbuf *m, int16_t v)
{
    __rte_mbuf_sanity_check(m, 1);

    do {
        rte_mbuf_refcnt_update(m, v);
    } while ((m = m->next) != NULL);
}

static inline uint16_t rte_pktmbuf_headroom(const struct rte_mbuf *m)
{
    __rte_mbuf_sanity_check(m, 0);
    return m->data_off;
}

static inline uint16_t rte_pktmbuf_tailroom(const struct rte_mbuf *m)
{
    __rte_mbuf_sanity_check(m, 0);
    return (uint16_t)(m->buf_len - rte_pktmbuf_headroom(m) -
              m->data_len);
}

static inline struct rte_mbuf *rte_pktmbuf_lastseg(struct rte_mbuf *m)
{
    __rte_mbuf_sanity_check(m, 1);
    while (m->next != NULL)
        m = m->next;
    return m;
}

#define rte_pktmbuf_mtod_offset(m, t, o)    \
    ((t)((char *)(m)->buf_addr + (m)->data_off + (o)))

#define rte_pktmbuf_mtod(m, t) rte_pktmbuf_mtod_offset(m, t, 0)

#define rte_pktmbuf_mtophys_offset(m, o) \
    (phys_addr_t)((m)->buf_physaddr + (m)->data_off + (o))

#define rte_pktmbuf_mtophys(m) rte_pktmbuf_mtophys_offset(m, 0)

#define rte_pktmbuf_pkt_len(m) ((m)->pkt_len)

#define rte_pktmbuf_data_len(m) ((m)->data_len)

static inline char *rte_pktmbuf_prepend(struct rte_mbuf *m,
                    uint16_t len)
{
    __rte_mbuf_sanity_check(m, 1);

    if (unlikely(len > rte_pktmbuf_headroom(m)))
        return NULL;

    /* NB: elaborating the subtraction like this instead of using
     *     -= allows us to ensure the result type is uint16_t
     *     avoiding compiler warnings on gcc 8.1 at least */
    m->data_off = (uint16_t)(m->data_off - len);
    m->data_len = (uint16_t)(m->data_len + len);
    m->pkt_len  = (m->pkt_len + len);

    return (char *)m->buf_addr + m->data_off;
}

static inline char *rte_pktmbuf_append(struct rte_mbuf *m, uint16_t len)
{
    void *tail;
    struct rte_mbuf *m_last;

    __rte_mbuf_sanity_check(m, 1);

    m_last = rte_pktmbuf_lastseg(m);
    if (unlikely(len > rte_pktmbuf_tailroom(m_last)))
        return NULL;

    tail = (char *)m_last->buf_addr + m_last->data_off + m_last->data_len;
    m_last->data_len = (uint16_t)(m_last->data_len + len);
    m->pkt_len  = (m->pkt_len + len);
    return (char*) tail;
}

static inline char *rte_pktmbuf_adj(struct rte_mbuf *m, uint16_t len)
{
    __rte_mbuf_sanity_check(m, 1);

    if (unlikely(len > m->data_len))
        return NULL;

    /* NB: elaborating the addition like this instead of using
     *     += allows us to ensure the result type is uint16_t
     *     avoiding compiler warnings on gcc 8.1 at least */
    m->data_len = (uint16_t)(m->data_len - len);
    m->data_off = (uint16_t)(m->data_off + len);
    m->pkt_len  = (m->pkt_len - len);
    return (char *)m->buf_addr + m->data_off;
}

static inline int rte_pktmbuf_trim(struct rte_mbuf *m, uint16_t len)
{
    struct rte_mbuf *m_last;

    __rte_mbuf_sanity_check(m, 1);

    m_last = rte_pktmbuf_lastseg(m);
    if (unlikely(len > m_last->data_len))
        return -1;

    m_last->data_len = (uint16_t)(m_last->data_len - len);
    m->pkt_len  = (m->pkt_len - len);
    return 0;
}

static inline int rte_pktmbuf_is_contiguous(const struct rte_mbuf *m)
{
    __rte_mbuf_sanity_check(m, 1);
    return !!(m->nb_segs == 1);
}

const void *__rte_pktmbuf_read(const struct rte_mbuf *m, uint32_t off,
    uint32_t len, void *buf);

static inline const void *rte_pktmbuf_read(const struct rte_mbuf *m,
    uint32_t off, uint32_t len, void *buf)
{
    if (likely(off + len <= rte_pktmbuf_data_len(m)))
        return rte_pktmbuf_mtod_offset(m, char *, off);
    else
        return __rte_pktmbuf_read(m, off, len, buf);
}

static inline int rte_pktmbuf_chain(struct rte_mbuf *head, struct rte_mbuf *tail)
{
    struct rte_mbuf *cur_tail;

    /* Check for number-of-segments-overflow */
    if (head->nb_segs + tail->nb_segs >= 1 << (sizeof(head->nb_segs) * 8))
        return -EOVERFLOW;

    /* Chain 'tail' onto the old tail */
    cur_tail = rte_pktmbuf_lastseg(head);
    cur_tail->next = tail;

    /* accumulate number of segments and total length.
     * NB: elaborating the addition like this instead of using
     *     -= allows us to ensure the result type is uint16_t
     *     avoiding compiler warnings on gcc 8.1 at least */
    head->nb_segs = (uint8_t)(head->nb_segs + tail->nb_segs);
    head->pkt_len += tail->pkt_len;

    /* pkt_len is only set in the head */
    tail->pkt_len = tail->data_len;

    return 0;
}

void rte_pktmbuf_dump(FILE *f, const struct rte_mbuf *m, unsigned dump_len);

#ifdef __cplusplus
}
#endif

#endif /* _RTE_MBUF_H_ */