X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=lib%2Flibrte_mbuf%2Frte_mbuf.h;h=62740254d98734f9bb5236317da3da38ddc2b77b;hb=6aa0fe344c1e8116cfa340401345ac6d629d1a28;hp=fe605c7a48a4b359a7f4911ed47d82892ec689e3;hpb=c0583d98a9153549383d236e5cc5464bbbe8dd89;p=dpdk.git diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h index fe605c7a48..62740254d9 100644 --- a/lib/librte_mbuf/rte_mbuf.h +++ b/lib/librte_mbuf/rte_mbuf.h @@ -1,35 +1,6 @@ -/*- - * 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. +/* SPDX-License-Identifier: BSD-3-Clause + * Copyright(c) 2010-2014 Intel Corporation. + * Copyright 2014 6WIND S.A. */ #ifndef _RTE_MBUF_H_ @@ -61,7 +32,9 @@ */ #include +#include #include +#include #include #include #include @@ -89,12 +62,13 @@ extern "C" { */ /** - * RX packet is a 802.1q VLAN packet. This flag was set by PMDs when - * the packet is recognized as a VLAN, but the behavior between PMDs - * was not the same. This flag is kept for some time to avoid breaking - * applications and should be replaced by PKT_RX_VLAN_STRIPPED. + * The RX packet is a 802.1q VLAN packet, and the tci has been + * saved in in mbuf->vlan_tci. + * If the flag PKT_RX_VLAN_STRIPPED is also present, the VLAN + * header has been stripped from mbuf data, else it is still + * present. */ -#define PKT_RX_VLAN_PKT (1ULL << 0) +#define PKT_RX_VLAN (1ULL << 0) #define PKT_RX_RSS_HASH (1ULL << 1) /**< RX packet with RSS hash result. */ #define PKT_RX_FDIR (1ULL << 2) /**< RX packet with FDIR match indicate. */ @@ -123,6 +97,7 @@ extern "C" { * A vlan has been stripped by the hardware and its tci is saved in * mbuf->vlan_tci. This can only happen if vlan stripping is enabled * in the RX configuration of the PMD. + * When PKT_RX_VLAN_STRIPPED is set, PKT_RX_VLAN must also be set. */ #define PKT_RX_VLAN_STRIPPED (1ULL << 6) @@ -165,18 +140,12 @@ extern "C" { * The 2 vlans have been stripped by the hardware and their tci are * saved in mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer). * This can only happen if vlan stripping is enabled in the RX - * configuration of the PMD. If this flag is set, PKT_RX_VLAN_STRIPPED - * must also be set. + * configuration of the PMD. If this flag is set, + * When PKT_RX_QINQ_STRIPPED is set, the flags (PKT_RX_VLAN | + * PKT_RX_VLAN_STRIPPED | PKT_RX_QINQ) must also be set. */ #define PKT_RX_QINQ_STRIPPED (1ULL << 15) -/** - * Deprecated. - * RX packet with double VLAN stripped. - * This flag is replaced by PKT_RX_QINQ_STRIPPED. - */ -#define PKT_RX_QINQ_PKT PKT_RX_QINQ_STRIPPED - /** * When packets are coalesced by a hardware or virtual driver, this flag * can be set in the RX mbuf, meaning that the m->tso_segsz field is @@ -189,10 +158,41 @@ extern "C" { */ #define PKT_RX_TIMESTAMP (1ULL << 17) +/** + * Indicate that security offload processing was applied on the RX packet. + */ +#define PKT_RX_SEC_OFFLOAD (1ULL << 18) + +/** + * Indicate that security offload processing failed on the RX packet. + */ +#define PKT_RX_SEC_OFFLOAD_FAILED (1ULL << 19) + +/** + * The RX packet is a double VLAN, and the outer tci has been + * saved in in mbuf->vlan_tci_outer. + * If the flag PKT_RX_QINQ_STRIPPED is also present, both VLANs + * headers have been stripped from mbuf data, else they are still + * present. + */ +#define PKT_RX_QINQ (1ULL << 20) + /* add new RX flags here */ /* add new TX flags here */ +/** + * UDP Fragmentation Offload flag. This flag is used for enabling UDP + * fragmentation in SW or in HW. When use UFO, mbuf->tso_segsz is used + * to store the MSS of UDP fragments. + */ +#define PKT_TX_UDP_SEG (1ULL << 42) + +/** + * Request security offload processing on the TX packet. + */ +#define PKT_TX_SEC_OFFLOAD (1ULL << 43) + /** * Offload the MACsec. This flag must be set by the application to enable * this offload feature for a packet to be transmitted. @@ -208,13 +208,17 @@ extern "C" { #define PKT_TX_TUNNEL_GRE (0x2ULL << 45) #define PKT_TX_TUNNEL_IPIP (0x3ULL << 45) #define PKT_TX_TUNNEL_GENEVE (0x4ULL << 45) +/**< TX packet with MPLS-in-UDP RFC 7510 header. */ +#define PKT_TX_TUNNEL_MPLSINUDP (0x5ULL << 45) /* add new TX TUNNEL type here */ #define PKT_TX_TUNNEL_MASK (0xFULL << 45) /** * Second VLAN insertion (QinQ) flag. */ -#define PKT_TX_QINQ_PKT (1ULL << 49) /**< TX packet with double VLAN inserted. */ +#define PKT_TX_QINQ (1ULL << 49) /**< TX packet with double VLAN inserted. */ +/* this old name is deprecated */ +#define PKT_TX_QINQ_PKT PKT_TX_QINQ /** * TCP segmentation offload. To enable this offload feature for a @@ -275,7 +279,12 @@ extern "C" { */ #define PKT_TX_IPV6 (1ULL << 56) -#define PKT_TX_VLAN_PKT (1ULL << 57) /**< TX packet is a 802.1q VLAN packet. */ +/** + * TX packet is a 802.1q VLAN packet. + */ +#define PKT_TX_VLAN (1ULL << 57) +/* this old name is deprecated */ +#define PKT_TX_VLAN_PKT PKT_TX_VLAN /** * Offload the IP checksum of an external header in the hardware. The @@ -314,7 +323,8 @@ extern "C" { PKT_TX_QINQ_PKT | \ PKT_TX_VLAN_PKT | \ PKT_TX_TUNNEL_MASK | \ - PKT_TX_MACSEC) + PKT_TX_MACSEC | \ + PKT_TX_SEC_OFFLOAD) #define __RESERVED (1ULL << 61) /**< reserved for future mbuf use */ @@ -409,7 +419,11 @@ struct rte_mbuf { * same mbuf cacheline0 layout for 32-bit and 64-bit. This makes * working on vector drivers easier. */ - phys_addr_t buf_physaddr __rte_aligned(sizeof(phys_addr_t)); + RTE_STD_C11 + union { + rte_iova_t buf_iova; + rte_iova_t buf_physaddr; /**< deprecated */ + } __rte_aligned(sizeof(rte_iova_t)); /* next 8 bytes are initialised on RX descriptor rearm */ MARKER64 rearm_data; @@ -454,15 +468,28 @@ struct rte_mbuf { uint32_t l3_type:4; /**< (Outer) L3 type. */ uint32_t l4_type:4; /**< (Outer) L4 type. */ uint32_t tun_type:4; /**< Tunnel type. */ - uint32_t inner_l2_type:4; /**< Inner L2 type. */ - uint32_t inner_l3_type:4; /**< Inner L3 type. */ + RTE_STD_C11 + union { + uint8_t inner_esp_next_proto; + /**< ESP next protocol type, valid if + * RTE_PTYPE_TUNNEL_ESP tunnel type is set + * on both Tx and Rx. + */ + __extension__ + struct { + uint8_t inner_l2_type:4; + /**< Inner L2 type. */ + uint8_t inner_l3_type:4; + /**< Inner L3 type. */ + }; + }; uint32_t inner_l4_type:4; /**< Inner L4 type. */ }; }; uint32_t pkt_len; /**< Total pkt len: sum of all segments. */ uint16_t data_len; /**< Amount of data in segment buffer. */ - /** VLAN TCI (CPU order), valid if PKT_RX_VLAN_STRIPPED is set. */ + /** VLAN TCI (CPU order), valid if PKT_RX_VLAN is set. */ uint16_t vlan_tci; union { @@ -488,7 +515,7 @@ struct rte_mbuf { uint32_t usr; /**< User defined tags. See rte_distributor_process() */ } hash; /**< hash information */ - /** Outer VLAN TCI (CPU order), valid if PKT_RX_QINQ_STRIPPED is set. */ + /** Outer VLAN TCI (CPU order), valid if PKT_RX_QINQ is set. */ uint16_t vlan_tci_outer; uint16_t buf_len; /**< Length of segment buffer. */ @@ -544,6 +571,9 @@ struct rte_mbuf { } __rte_cache_aligned; +/**< Maximum number of nb_segs allowed. */ +#define RTE_MBUF_MAX_NB_SEGS UINT16_MAX + /** * Prefetch the first part of the mbuf * @@ -585,21 +615,28 @@ rte_mbuf_prefetch_part2(struct rte_mbuf *m) static inline uint16_t rte_pktmbuf_priv_size(struct rte_mempool *mp); /** - * Return the DMA address of the beginning of the mbuf data + * Return the IO address of the beginning of the mbuf data * * @param mb * The pointer to the mbuf. * @return - * The physical address of the beginning of the mbuf data + * The IO address of the beginning of the mbuf data */ +static inline rte_iova_t +rte_mbuf_data_iova(const struct rte_mbuf *mb) +{ + return mb->buf_iova + mb->data_off; +} + +__rte_deprecated static inline phys_addr_t rte_mbuf_data_dma_addr(const struct rte_mbuf *mb) { - return mb->buf_physaddr + mb->data_off; + return rte_mbuf_data_iova(mb); } /** - * Return the default DMA address of the beginning of the mbuf data + * Return the default IO address of the beginning of the mbuf data * * This function is used by drivers in their receive function, as it * returns the location where data should be written by the NIC, taking @@ -608,12 +645,19 @@ rte_mbuf_data_dma_addr(const struct rte_mbuf *mb) * @param mb * The pointer to the mbuf. * @return - * The physical address of the beginning of the mbuf data + * The IO address of the beginning of the mbuf data */ +static inline rte_iova_t +rte_mbuf_data_iova_default(const struct rte_mbuf *mb) +{ + return mb->buf_iova + RTE_PKTMBUF_HEADROOM; +} + +__rte_deprecated static inline phys_addr_t rte_mbuf_data_dma_addr_default(const struct rte_mbuf *mb) { - return mb->buf_physaddr + RTE_PKTMBUF_HEADROOM; + return rte_mbuf_data_iova_default(mb); } /** @@ -707,6 +751,13 @@ rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value) rte_atomic16_set(&m->refcnt_atomic, new_value); } +/* internal */ +static inline uint16_t +__rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) +{ + return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value)); +} + /** * Adds given value to an mbuf's refcnt and returns its new value. * @param m @@ -731,19 +782,26 @@ rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) return 1 + value; } - return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value)); + return __rte_mbuf_refcnt_update(m, value); } #else /* ! RTE_MBUF_REFCNT_ATOMIC */ +/* internal */ +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; +} + /** * Adds given value to an mbuf's refcnt and returns its new value. */ 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; + return __rte_mbuf_refcnt_update(m, value); } /** @@ -796,15 +854,15 @@ rte_mbuf_sanity_check(const struct rte_mbuf *m, int is_header); } while (0) /** - * Allocate an unitialized mbuf from mempool *mp*. + * Allocate an uninitialized mbuf from mempool *mp*. * * This function can be used by PMDs (especially in RX functions) to - * allocate an unitialized mbuf. The driver is responsible of + * allocate an uninitialized mbuf. The driver is responsible of * initializing all the required fields. See rte_pktmbuf_reset(). * For standard needs, prefer rte_pktmbuf_alloc(). * * The caller can expect that the following fields of the mbuf structure - * are initialized: buf_addr, buf_physaddr, buf_len, refcnt=1, nb_segs=1, + * are initialized: buf_addr, buf_iova, buf_len, refcnt=1, nb_segs=1, * next=NULL, pool, priv_size. The other fields must be initialized * by the caller. * @@ -817,11 +875,9 @@ 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) + if (rte_mempool_get(mp, (void **)&m) < 0) return NULL; - m = (struct rte_mbuf *)mb; MBUF_RAW_ALLOC_CHECK(m); return m; } @@ -1023,6 +1079,48 @@ rte_pktmbuf_pool_create(const char *name, unsigned n, unsigned cache_size, uint16_t priv_size, uint16_t data_room_size, int socket_id); +/** + * Create a mbuf pool with a given mempool ops name + * + * This function creates and initializes a packet mbuf pool. It is + * a wrapper to rte_mempool functions. + * + * @param name + * The name of the mbuf pool. + * @param n + * The number of elements in the mbuf pool. The optimum size (in terms + * of memory usage) for a mempool is when n is a power of two minus one: + * n = (2^q - 1). + * @param cache_size + * Size of the per-core object cache. See rte_mempool_create() for + * details. + * @param priv_size + * Size of application private are between the rte_mbuf structure + * and the data buffer. This value must be aligned to RTE_MBUF_PRIV_ALIGN. + * @param data_room_size + * Size of data buffer in each mbuf, including RTE_PKTMBUF_HEADROOM. + * @param socket_id + * The socket identifier where the memory should be allocated. The + * value can be *SOCKET_ID_ANY* if there is no NUMA constraint for the + * reserved zone. + * @param ops_name + * The mempool ops name to be used for this mempool instead of + * default mempool. The value can be *NULL* to use default mempool. + * @return + * The pointer to the new allocated mempool, on success. NULL on error + * with rte_errno set appropriately. Possible rte_errno values include: + * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure + * - E_RTE_SECONDARY - function was called from a secondary process instance + * - EINVAL - cache size provided is too large, or priv_size is not aligned. + * - ENOSPC - the maximum number of memzones has already been allocated + * - EEXIST - a memzone with the same name already exists + * - ENOMEM - no appropriate memory area found in which to create memzone + */ +struct rte_mempool * __rte_experimental +rte_pktmbuf_pool_create_by_ops(const char *name, unsigned int n, + unsigned int cache_size, uint16_t priv_size, uint16_t data_room_size, + int socket_id, const char *ops_name); + /** * Get the data room size of mbufs stored in a pktmbuf_pool * @@ -1085,6 +1183,8 @@ static inline void rte_pktmbuf_reset_headroom(struct rte_mbuf *m) * @param m * The packet mbuf to be resetted. */ +#define MBUF_INVALID_PORT UINT16_MAX + static inline void rte_pktmbuf_reset(struct rte_mbuf *m) { m->next = NULL; @@ -1093,7 +1193,7 @@ static inline void rte_pktmbuf_reset(struct rte_mbuf *m) m->vlan_tci = 0; m->vlan_tci_outer = 0; m->nb_segs = 1; - m->port = 0xff; + m->port = MBUF_INVALID_PORT; m->ol_flags = 0; m->packet_type = 0; @@ -1136,6 +1236,7 @@ static inline struct rte_mbuf *rte_pktmbuf_alloc(struct rte_mempool *mp) * Array size * @return * - 0: Success + * - -ENOENT: Not enough entries in the mempool; no mbufs are retrieved. */ static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool, struct rte_mbuf **mbufs, unsigned count) @@ -1211,7 +1312,7 @@ static inline void rte_pktmbuf_attach(struct rte_mbuf *mi, struct rte_mbuf *m) rte_mbuf_refcnt_update(md, 1); mi->priv_size = m->priv_size; - mi->buf_physaddr = m->buf_physaddr; + mi->buf_iova = m->buf_iova; mi->buf_addr = m->buf_addr; mi->buf_len = m->buf_len; @@ -1259,7 +1360,7 @@ static inline void rte_pktmbuf_detach(struct rte_mbuf *m) m->priv_size = priv_size; m->buf_addr = (char *)m + mbuf_size; - m->buf_physaddr = rte_mempool_virt2phy(mp, m) + mbuf_size; + m->buf_iova = rte_mempool_virt2iova(m) + mbuf_size; m->buf_len = (uint16_t)buf_len; rte_pktmbuf_reset_headroom(m); m->data_len = 0; @@ -1304,8 +1405,7 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) return m; - } else if (rte_atomic16_add_return(&m->refcnt_atomic, -1) == 0) { - + } else if (__rte_mbuf_refcnt_update(m, -1) == 0) { if (RTE_MBUF_INDIRECT(m)) rte_pktmbuf_detach(m); @@ -1353,13 +1453,14 @@ rte_pktmbuf_free_seg(struct rte_mbuf *m) * segment is added back into its original mempool. * * @param m - * The packet mbuf to be freed. + * The packet mbuf to be freed. If NULL, the function does nothing. */ static inline void rte_pktmbuf_free(struct rte_mbuf *m) { struct rte_mbuf *m_next; - __rte_mbuf_sanity_check(m, 1); + if (m != NULL) + __rte_mbuf_sanity_check(m, 1); while (m != NULL) { m_next = m->next; @@ -1390,7 +1491,7 @@ static inline struct rte_mbuf *rte_pktmbuf_clone(struct rte_mbuf *md, { struct rte_mbuf *mc, *mi, **prev; uint32_t pktlen; - uint8_t nseg; + uint16_t nseg; if (unlikely ((mc = rte_pktmbuf_alloc(mp)) == NULL)) return NULL; @@ -1452,7 +1553,7 @@ static inline void rte_pktmbuf_refcnt_update(struct rte_mbuf *m, int16_t v) */ static inline uint16_t rte_pktmbuf_headroom(const struct rte_mbuf *m) { - __rte_mbuf_sanity_check(m, 1); + __rte_mbuf_sanity_check(m, 0); return m->data_off; } @@ -1466,7 +1567,7 @@ static inline uint16_t rte_pktmbuf_headroom(const struct rte_mbuf *m) */ static inline uint16_t rte_pktmbuf_tailroom(const struct rte_mbuf *m) { - __rte_mbuf_sanity_check(m, 1); + __rte_mbuf_sanity_check(m, 0); return (uint16_t)(m->buf_len - rte_pktmbuf_headroom(m) - m->data_len); } @@ -1481,12 +1582,10 @@ static inline uint16_t rte_pktmbuf_tailroom(const struct rte_mbuf *m) */ static inline struct rte_mbuf *rte_pktmbuf_lastseg(struct rte_mbuf *m) { - struct rte_mbuf *m2 = (struct rte_mbuf *)m; - __rte_mbuf_sanity_check(m, 1); - while (m2->next != NULL) - m2 = m2->next; - return m2; + while (m->next != NULL) + m = m->next; + return m; } /** @@ -1521,7 +1620,7 @@ static inline struct rte_mbuf *rte_pktmbuf_lastseg(struct rte_mbuf *m) #define rte_pktmbuf_mtod(m, t) rte_pktmbuf_mtod_offset(m, t, 0) /** - * A macro that returns the physical address that points to an offset of the + * A macro that returns the IO address that points to an offset of the * start of the data in the mbuf * * @param m @@ -1529,17 +1628,24 @@ static inline struct rte_mbuf *rte_pktmbuf_lastseg(struct rte_mbuf *m) * @param o * The offset into the data to calculate address from. */ +#define rte_pktmbuf_iova_offset(m, o) \ + (rte_iova_t)((m)->buf_iova + (m)->data_off + (o)) + +/* deprecated */ #define rte_pktmbuf_mtophys_offset(m, o) \ - (phys_addr_t)((m)->buf_physaddr + (m)->data_off + (o)) + rte_pktmbuf_iova_offset(m, o) /** - * A macro that returns the physical address that points to the start of the + * A macro that returns the IO address that points to the start of the * data in the mbuf * * @param m * The packet mbuf. */ -#define rte_pktmbuf_mtophys(m) rte_pktmbuf_mtophys_offset(m, 0) +#define rte_pktmbuf_iova(m) rte_pktmbuf_iova_offset(m, 0) + +/* deprecated */ +#define rte_pktmbuf_mtophys(m) rte_pktmbuf_iova(m) /** * A macro that returns the length of the packet. @@ -1714,7 +1820,7 @@ const void *__rte_pktmbuf_read(const struct rte_mbuf *m, uint32_t off, * @param len * The amount of bytes to read. * @param buf - * The buffer where data is copied if it is not contigous in mbuf + * The buffer where data is copied if it is not contiguous in mbuf * data. Its length should be at least equal to the len parameter. * @return * The pointer to the data, either in the mbuf if it is contiguous, @@ -1743,14 +1849,14 @@ static inline const void *rte_pktmbuf_read(const struct rte_mbuf *m, * * @return * - 0, on success. - * - -EOVERFLOW, if the chain is full (256 entries) + * - -EOVERFLOW, if the chain segment limit exceeded */ 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)) + if (head->nb_segs + tail->nb_segs > RTE_MBUF_MAX_NB_SEGS) return -EOVERFLOW; /* Chain 'tail' onto the old tail */ @@ -1758,7 +1864,7 @@ static inline int rte_pktmbuf_chain(struct rte_mbuf *head, struct rte_mbuf *tail cur_tail->next = tail; /* accumulate number of segments and total length. */ - head->nb_segs = (uint8_t)(head->nb_segs + tail->nb_segs); + head->nb_segs += tail->nb_segs; head->pkt_len += tail->pkt_len; /* pkt_len is only set in the head */