linux/include/linux/skbuff.h
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   1/*
   2 *      Definitions for the 'struct sk_buff' memory handlers.
   3 *
   4 *      Authors:
   5 *              Alan Cox, <gw4pts@gw4pts.ampr.org>
   6 *              Florian La Roche, <rzsfl@rz.uni-sb.de>
   7 *
   8 *      This program is free software; you can redistribute it and/or
   9 *      modify it under the terms of the GNU General Public License
  10 *      as published by the Free Software Foundation; either version
  11 *      2 of the License, or (at your option) any later version.
  12 */
  13
  14#ifndef _LINUX_SKBUFF_H
  15#define _LINUX_SKBUFF_H
  16
  17#include <linux/kernel.h>
  18#include <linux/kmemcheck.h>
  19#include <linux/compiler.h>
  20#include <linux/time.h>
  21#include <linux/bug.h>
  22#include <linux/cache.h>
  23
  24#include <linux/atomic.h>
  25#include <asm/types.h>
  26#include <linux/spinlock.h>
  27#include <linux/net.h>
  28#include <linux/textsearch.h>
  29#include <net/checksum.h>
  30#include <linux/rcupdate.h>
  31#include <linux/dmaengine.h>
  32#include <linux/hrtimer.h>
  33#include <linux/dma-mapping.h>
  34#include <linux/netdev_features.h>
  35
  36/* Don't change this without changing skb_csum_unnecessary! */
  37#define CHECKSUM_NONE 0
  38#define CHECKSUM_UNNECESSARY 1
  39#define CHECKSUM_COMPLETE 2
  40#define CHECKSUM_PARTIAL 3
  41
  42#define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
  43                                 ~(SMP_CACHE_BYTES - 1))
  44#define SKB_WITH_OVERHEAD(X)    \
  45        ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
  46#define SKB_MAX_ORDER(X, ORDER) \
  47        SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
  48#define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
  49#define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
  50
  51/* return minimum truesize of one skb containing X bytes of data */
  52#define SKB_TRUESIZE(X) ((X) +                                          \
  53                         SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
  54                         SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
  55
  56/* A. Checksumming of received packets by device.
  57 *
  58 *      NONE: device failed to checksum this packet.
  59 *              skb->csum is undefined.
  60 *
  61 *      UNNECESSARY: device parsed packet and wouldbe verified checksum.
  62 *              skb->csum is undefined.
  63 *            It is bad option, but, unfortunately, many of vendors do this.
  64 *            Apparently with secret goal to sell you new device, when you
  65 *            will add new protocol to your host. F.e. IPv6. 8)
  66 *
  67 *      COMPLETE: the most generic way. Device supplied checksum of _all_
  68 *          the packet as seen by netif_rx in skb->csum.
  69 *          NOTE: Even if device supports only some protocols, but
  70 *          is able to produce some skb->csum, it MUST use COMPLETE,
  71 *          not UNNECESSARY.
  72 *
  73 *      PARTIAL: identical to the case for output below.  This may occur
  74 *          on a packet received directly from another Linux OS, e.g.,
  75 *          a virtualised Linux kernel on the same host.  The packet can
  76 *          be treated in the same way as UNNECESSARY except that on
  77 *          output (i.e., forwarding) the checksum must be filled in
  78 *          by the OS or the hardware.
  79 *
  80 * B. Checksumming on output.
  81 *
  82 *      NONE: skb is checksummed by protocol or csum is not required.
  83 *
  84 *      PARTIAL: device is required to csum packet as seen by hard_start_xmit
  85 *      from skb->csum_start to the end and to record the checksum
  86 *      at skb->csum_start + skb->csum_offset.
  87 *
  88 *      Device must show its capabilities in dev->features, set
  89 *      at device setup time.
  90 *      NETIF_F_HW_CSUM - it is clever device, it is able to checksum
  91 *                        everything.
  92 *      NETIF_F_IP_CSUM - device is dumb. It is able to csum only
  93 *                        TCP/UDP over IPv4. Sigh. Vendors like this
  94 *                        way by an unknown reason. Though, see comment above
  95 *                        about CHECKSUM_UNNECESSARY. 8)
  96 *      NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
  97 *
  98 *      UNNECESSARY: device will do per protocol specific csum. Protocol drivers
  99 *      that do not want net to perform the checksum calculation should use
 100 *      this flag in their outgoing skbs.
 101 *      NETIF_F_FCOE_CRC  this indicates the device can do FCoE FC CRC
 102 *                        offload. Correspondingly, the FCoE protocol driver
 103 *                        stack should use CHECKSUM_UNNECESSARY.
 104 *
 105 *      Any questions? No questions, good.              --ANK
 106 */
 107
 108struct net_device;
 109struct scatterlist;
 110struct pipe_inode_info;
 111
 112#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 113struct nf_conntrack {
 114        atomic_t use;
 115};
 116#endif
 117
 118#ifdef CONFIG_BRIDGE_NETFILTER
 119struct nf_bridge_info {
 120        atomic_t                use;
 121        unsigned int            mask;
 122        struct net_device       *physindev;
 123        struct net_device       *physoutdev;
 124        unsigned long           data[32 / sizeof(unsigned long)];
 125};
 126#endif
 127
 128struct sk_buff_head {
 129        /* These two members must be first. */
 130        struct sk_buff  *next;
 131        struct sk_buff  *prev;
 132
 133        __u32           qlen;
 134        spinlock_t      lock;
 135};
 136
 137struct sk_buff;
 138
 139/* To allow 64K frame to be packed as single skb without frag_list we
 140 * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
 141 * buffers which do not start on a page boundary.
 142 *
 143 * Since GRO uses frags we allocate at least 16 regardless of page
 144 * size.
 145 */
 146#if (65536/PAGE_SIZE + 1) < 16
 147#define MAX_SKB_FRAGS 16UL
 148#else
 149#define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
 150#endif
 151
 152typedef struct skb_frag_struct skb_frag_t;
 153
 154struct skb_frag_struct {
 155        struct {
 156                struct page *p;
 157        } page;
 158#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
 159        __u32 page_offset;
 160        __u32 size;
 161#else
 162        __u16 page_offset;
 163        __u16 size;
 164#endif
 165};
 166
 167static inline unsigned int skb_frag_size(const skb_frag_t *frag)
 168{
 169        return frag->size;
 170}
 171
 172static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
 173{
 174        frag->size = size;
 175}
 176
 177static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
 178{
 179        frag->size += delta;
 180}
 181
 182static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
 183{
 184        frag->size -= delta;
 185}
 186
 187#define HAVE_HW_TIME_STAMP
 188
 189/**
 190 * struct skb_shared_hwtstamps - hardware time stamps
 191 * @hwtstamp:   hardware time stamp transformed into duration
 192 *              since arbitrary point in time
 193 * @syststamp:  hwtstamp transformed to system time base
 194 *
 195 * Software time stamps generated by ktime_get_real() are stored in
 196 * skb->tstamp. The relation between the different kinds of time
 197 * stamps is as follows:
 198 *
 199 * syststamp and tstamp can be compared against each other in
 200 * arbitrary combinations.  The accuracy of a
 201 * syststamp/tstamp/"syststamp from other device" comparison is
 202 * limited by the accuracy of the transformation into system time
 203 * base. This depends on the device driver and its underlying
 204 * hardware.
 205 *
 206 * hwtstamps can only be compared against other hwtstamps from
 207 * the same device.
 208 *
 209 * This structure is attached to packets as part of the
 210 * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
 211 */
 212struct skb_shared_hwtstamps {
 213        ktime_t hwtstamp;
 214        ktime_t syststamp;
 215};
 216
 217/* Definitions for tx_flags in struct skb_shared_info */
 218enum {
 219        /* generate hardware time stamp */
 220        SKBTX_HW_TSTAMP = 1 << 0,
 221
 222        /* generate software time stamp */
 223        SKBTX_SW_TSTAMP = 1 << 1,
 224
 225        /* device driver is going to provide hardware time stamp */
 226        SKBTX_IN_PROGRESS = 1 << 2,
 227
 228        /* device driver supports TX zero-copy buffers */
 229        SKBTX_DEV_ZEROCOPY = 1 << 3,
 230
 231        /* generate wifi status information (where possible) */
 232        SKBTX_WIFI_STATUS = 1 << 4,
 233};
 234
 235/*
 236 * The callback notifies userspace to release buffers when skb DMA is done in
 237 * lower device, the skb last reference should be 0 when calling this.
 238 * The ctx field is used to track device context.
 239 * The desc field is used to track userspace buffer index.
 240 */
 241struct ubuf_info {
 242        void (*callback)(struct ubuf_info *);
 243        void *ctx;
 244        unsigned long desc;
 245};
 246
 247/* This data is invariant across clones and lives at
 248 * the end of the header data, ie. at skb->end.
 249 */
 250struct skb_shared_info {
 251        unsigned char   nr_frags;
 252        __u8            tx_flags;
 253        unsigned short  gso_size;
 254        /* Warning: this field is not always filled in (UFO)! */
 255        unsigned short  gso_segs;
 256        unsigned short  gso_type;
 257        struct sk_buff  *frag_list;
 258        struct skb_shared_hwtstamps hwtstamps;
 259        __be32          ip6_frag_id;
 260
 261        /*
 262         * Warning : all fields before dataref are cleared in __alloc_skb()
 263         */
 264        atomic_t        dataref;
 265
 266        /* Intermediate layers must ensure that destructor_arg
 267         * remains valid until skb destructor */
 268        void *          destructor_arg;
 269
 270        /* must be last field, see pskb_expand_head() */
 271        skb_frag_t      frags[MAX_SKB_FRAGS];
 272};
 273
 274/* We divide dataref into two halves.  The higher 16 bits hold references
 275 * to the payload part of skb->data.  The lower 16 bits hold references to
 276 * the entire skb->data.  A clone of a headerless skb holds the length of
 277 * the header in skb->hdr_len.
 278 *
 279 * All users must obey the rule that the skb->data reference count must be
 280 * greater than or equal to the payload reference count.
 281 *
 282 * Holding a reference to the payload part means that the user does not
 283 * care about modifications to the header part of skb->data.
 284 */
 285#define SKB_DATAREF_SHIFT 16
 286#define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
 287
 288
 289enum {
 290        SKB_FCLONE_UNAVAILABLE,
 291        SKB_FCLONE_ORIG,
 292        SKB_FCLONE_CLONE,
 293};
 294
 295enum {
 296        SKB_GSO_TCPV4 = 1 << 0,
 297        SKB_GSO_UDP = 1 << 1,
 298
 299        /* This indicates the skb is from an untrusted source. */
 300        SKB_GSO_DODGY = 1 << 2,
 301
 302        /* This indicates the tcp segment has CWR set. */
 303        SKB_GSO_TCP_ECN = 1 << 3,
 304
 305        SKB_GSO_TCPV6 = 1 << 4,
 306
 307        SKB_GSO_FCOE = 1 << 5,
 308};
 309
 310#if BITS_PER_LONG > 32
 311#define NET_SKBUFF_DATA_USES_OFFSET 1
 312#endif
 313
 314#ifdef NET_SKBUFF_DATA_USES_OFFSET
 315typedef unsigned int sk_buff_data_t;
 316#else
 317typedef unsigned char *sk_buff_data_t;
 318#endif
 319
 320#if defined(CONFIG_NF_DEFRAG_IPV4) || defined(CONFIG_NF_DEFRAG_IPV4_MODULE) || \
 321    defined(CONFIG_NF_DEFRAG_IPV6) || defined(CONFIG_NF_DEFRAG_IPV6_MODULE)
 322#define NET_SKBUFF_NF_DEFRAG_NEEDED 1
 323#endif
 324
 325/** 
 326 *      struct sk_buff - socket buffer
 327 *      @next: Next buffer in list
 328 *      @prev: Previous buffer in list
 329 *      @tstamp: Time we arrived
 330 *      @sk: Socket we are owned by
 331 *      @dev: Device we arrived on/are leaving by
 332 *      @cb: Control buffer. Free for use by every layer. Put private vars here
 333 *      @_skb_refdst: destination entry (with norefcount bit)
 334 *      @sp: the security path, used for xfrm
 335 *      @len: Length of actual data
 336 *      @data_len: Data length
 337 *      @mac_len: Length of link layer header
 338 *      @hdr_len: writable header length of cloned skb
 339 *      @csum: Checksum (must include start/offset pair)
 340 *      @csum_start: Offset from skb->head where checksumming should start
 341 *      @csum_offset: Offset from csum_start where checksum should be stored
 342 *      @priority: Packet queueing priority
 343 *      @local_df: allow local fragmentation
 344 *      @cloned: Head may be cloned (check refcnt to be sure)
 345 *      @ip_summed: Driver fed us an IP checksum
 346 *      @nohdr: Payload reference only, must not modify header
 347 *      @nfctinfo: Relationship of this skb to the connection
 348 *      @pkt_type: Packet class
 349 *      @fclone: skbuff clone status
 350 *      @ipvs_property: skbuff is owned by ipvs
 351 *      @peeked: this packet has been seen already, so stats have been
 352 *              done for it, don't do them again
 353 *      @nf_trace: netfilter packet trace flag
 354 *      @protocol: Packet protocol from driver
 355 *      @destructor: Destruct function
 356 *      @nfct: Associated connection, if any
 357 *      @nfct_reasm: netfilter conntrack re-assembly pointer
 358 *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
 359 *      @skb_iif: ifindex of device we arrived on
 360 *      @tc_index: Traffic control index
 361 *      @tc_verd: traffic control verdict
 362 *      @rxhash: the packet hash computed on receive
 363 *      @queue_mapping: Queue mapping for multiqueue devices
 364 *      @ndisc_nodetype: router type (from link layer)
 365 *      @ooo_okay: allow the mapping of a socket to a queue to be changed
 366 *      @l4_rxhash: indicate rxhash is a canonical 4-tuple hash over transport
 367 *              ports.
 368 *      @wifi_acked_valid: wifi_acked was set
 369 *      @wifi_acked: whether frame was acked on wifi or not
 370 *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
 371 *      @dma_cookie: a cookie to one of several possible DMA operations
 372 *              done by skb DMA functions
 373 *      @secmark: security marking
 374 *      @mark: Generic packet mark
 375 *      @dropcount: total number of sk_receive_queue overflows
 376 *      @vlan_tci: vlan tag control information
 377 *      @transport_header: Transport layer header
 378 *      @network_header: Network layer header
 379 *      @mac_header: Link layer header
 380 *      @tail: Tail pointer
 381 *      @end: End pointer
 382 *      @head: Head of buffer
 383 *      @data: Data head pointer
 384 *      @truesize: Buffer size
 385 *      @users: User count - see {datagram,tcp}.c
 386 */
 387
 388struct sk_buff {
 389        /* These two members must be first. */
 390        struct sk_buff          *next;
 391        struct sk_buff          *prev;
 392
 393        ktime_t                 tstamp;
 394
 395        struct sock             *sk;
 396        struct net_device       *dev;
 397
 398        /*
 399         * This is the control buffer. It is free to use for every
 400         * layer. Please put your private variables there. If you
 401         * want to keep them across layers you have to do a skb_clone()
 402         * first. This is owned by whoever has the skb queued ATM.
 403         */
 404        char                    cb[48] __aligned(8);
 405
 406        unsigned long           _skb_refdst;
 407#ifdef CONFIG_XFRM
 408        struct  sec_path        *sp;
 409#endif
 410        unsigned int            len,
 411                                data_len;
 412        __u16                   mac_len,
 413                                hdr_len;
 414        union {
 415                __wsum          csum;
 416                struct {
 417                        __u16   csum_start;
 418                        __u16   csum_offset;
 419                };
 420        };
 421        __u32                   priority;
 422        kmemcheck_bitfield_begin(flags1);
 423        __u8                    local_df:1,
 424                                cloned:1,
 425                                ip_summed:2,
 426                                nohdr:1,
 427                                nfctinfo:3;
 428        __u8                    pkt_type:3,
 429                                fclone:2,
 430                                ipvs_property:1,
 431                                peeked:1,
 432                                nf_trace:1;
 433        kmemcheck_bitfield_end(flags1);
 434        __be16                  protocol;
 435
 436        void                    (*destructor)(struct sk_buff *skb);
 437#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 438        struct nf_conntrack     *nfct;
 439#endif
 440#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
 441        struct sk_buff          *nfct_reasm;
 442#endif
 443#ifdef CONFIG_BRIDGE_NETFILTER
 444        struct nf_bridge_info   *nf_bridge;
 445#endif
 446
 447        int                     skb_iif;
 448
 449        __u32                   rxhash;
 450
 451        __u16                   vlan_tci;
 452
 453#ifdef CONFIG_NET_SCHED
 454        __u16                   tc_index;       /* traffic control index */
 455#ifdef CONFIG_NET_CLS_ACT
 456        __u16                   tc_verd;        /* traffic control verdict */
 457#endif
 458#endif
 459
 460        __u16                   queue_mapping;
 461        kmemcheck_bitfield_begin(flags2);
 462#ifdef CONFIG_IPV6_NDISC_NODETYPE
 463        __u8                    ndisc_nodetype:2;
 464#endif
 465        __u8                    pfmemalloc:1;
 466        __u8                    ooo_okay:1;
 467        __u8                    l4_rxhash:1;
 468        __u8                    wifi_acked_valid:1;
 469        __u8                    wifi_acked:1;
 470        __u8                    no_fcs:1;
 471        __u8                    head_frag:1;
 472        /* 8/10 bit hole (depending on ndisc_nodetype presence) */
 473        kmemcheck_bitfield_end(flags2);
 474
 475#ifdef CONFIG_NET_DMA
 476        dma_cookie_t            dma_cookie;
 477#endif
 478#ifdef CONFIG_NETWORK_SECMARK
 479        __u32                   secmark;
 480#endif
 481        union {
 482                __u32           mark;
 483                __u32           dropcount;
 484                __u32           avail_size;
 485        };
 486
 487        sk_buff_data_t          transport_header;
 488        sk_buff_data_t          network_header;
 489        sk_buff_data_t          mac_header;
 490        /* These elements must be at the end, see alloc_skb() for details.  */
 491        sk_buff_data_t          tail;
 492        sk_buff_data_t          end;
 493        unsigned char           *head,
 494                                *data;
 495        unsigned int            truesize;
 496        atomic_t                users;
 497};
 498
 499#ifdef __KERNEL__
 500/*
 501 *      Handling routines are only of interest to the kernel
 502 */
 503#include <linux/slab.h>
 504
 505
 506#define SKB_ALLOC_FCLONE        0x01
 507#define SKB_ALLOC_RX            0x02
 508
 509/* Returns true if the skb was allocated from PFMEMALLOC reserves */
 510static inline bool skb_pfmemalloc(const struct sk_buff *skb)
 511{
 512        return unlikely(skb->pfmemalloc);
 513}
 514
 515/*
 516 * skb might have a dst pointer attached, refcounted or not.
 517 * _skb_refdst low order bit is set if refcount was _not_ taken
 518 */
 519#define SKB_DST_NOREF   1UL
 520#define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
 521
 522/**
 523 * skb_dst - returns skb dst_entry
 524 * @skb: buffer
 525 *
 526 * Returns skb dst_entry, regardless of reference taken or not.
 527 */
 528static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
 529{
 530        /* If refdst was not refcounted, check we still are in a 
 531         * rcu_read_lock section
 532         */
 533        WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
 534                !rcu_read_lock_held() &&
 535                !rcu_read_lock_bh_held());
 536        return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
 537}
 538
 539/**
 540 * skb_dst_set - sets skb dst
 541 * @skb: buffer
 542 * @dst: dst entry
 543 *
 544 * Sets skb dst, assuming a reference was taken on dst and should
 545 * be released by skb_dst_drop()
 546 */
 547static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
 548{
 549        skb->_skb_refdst = (unsigned long)dst;
 550}
 551
 552extern void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst);
 553
 554/**
 555 * skb_dst_is_noref - Test if skb dst isn't refcounted
 556 * @skb: buffer
 557 */
 558static inline bool skb_dst_is_noref(const struct sk_buff *skb)
 559{
 560        return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
 561}
 562
 563static inline struct rtable *skb_rtable(const struct sk_buff *skb)
 564{
 565        return (struct rtable *)skb_dst(skb);
 566}
 567
 568extern void kfree_skb(struct sk_buff *skb);
 569extern void consume_skb(struct sk_buff *skb);
 570extern void            __kfree_skb(struct sk_buff *skb);
 571extern struct kmem_cache *skbuff_head_cache;
 572
 573extern void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
 574extern bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
 575                             bool *fragstolen, int *delta_truesize);
 576
 577extern struct sk_buff *__alloc_skb(unsigned int size,
 578                                   gfp_t priority, int flags, int node);
 579extern struct sk_buff *build_skb(void *data, unsigned int frag_size);
 580static inline struct sk_buff *alloc_skb(unsigned int size,
 581                                        gfp_t priority)
 582{
 583        return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
 584}
 585
 586static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
 587                                               gfp_t priority)
 588{
 589        return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
 590}
 591
 592extern void skb_recycle(struct sk_buff *skb);
 593extern bool skb_recycle_check(struct sk_buff *skb, int skb_size);
 594
 595extern struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
 596extern int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
 597extern struct sk_buff *skb_clone(struct sk_buff *skb,
 598                                 gfp_t priority);
 599extern struct sk_buff *skb_copy(const struct sk_buff *skb,
 600                                gfp_t priority);
 601extern struct sk_buff *__pskb_copy(struct sk_buff *skb,
 602                                 int headroom, gfp_t gfp_mask);
 603
 604extern int             pskb_expand_head(struct sk_buff *skb,
 605                                        int nhead, int ntail,
 606                                        gfp_t gfp_mask);
 607extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
 608                                            unsigned int headroom);
 609extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
 610                                       int newheadroom, int newtailroom,
 611                                       gfp_t priority);
 612extern int             skb_to_sgvec(struct sk_buff *skb,
 613                                    struct scatterlist *sg, int offset,
 614                                    int len);
 615extern int             skb_cow_data(struct sk_buff *skb, int tailbits,
 616                                    struct sk_buff **trailer);
 617extern int             skb_pad(struct sk_buff *skb, int pad);
 618#define dev_kfree_skb(a)        consume_skb(a)
 619
 620extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
 621                        int getfrag(void *from, char *to, int offset,
 622                        int len,int odd, struct sk_buff *skb),
 623                        void *from, int length);
 624
 625struct skb_seq_state {
 626        __u32           lower_offset;
 627        __u32           upper_offset;
 628        __u32           frag_idx;
 629        __u32           stepped_offset;
 630        struct sk_buff  *root_skb;
 631        struct sk_buff  *cur_skb;
 632        __u8            *frag_data;
 633};
 634
 635extern void           skb_prepare_seq_read(struct sk_buff *skb,
 636                                           unsigned int from, unsigned int to,
 637                                           struct skb_seq_state *st);
 638extern unsigned int   skb_seq_read(unsigned int consumed, const u8 **data,
 639                                   struct skb_seq_state *st);
 640extern void           skb_abort_seq_read(struct skb_seq_state *st);
 641
 642extern unsigned int   skb_find_text(struct sk_buff *skb, unsigned int from,
 643                                    unsigned int to, struct ts_config *config,
 644                                    struct ts_state *state);
 645
 646extern void __skb_get_rxhash(struct sk_buff *skb);
 647static inline __u32 skb_get_rxhash(struct sk_buff *skb)
 648{
 649        if (!skb->rxhash)
 650                __skb_get_rxhash(skb);
 651
 652        return skb->rxhash;
 653}
 654
 655#ifdef NET_SKBUFF_DATA_USES_OFFSET
 656static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
 657{
 658        return skb->head + skb->end;
 659}
 660
 661static inline unsigned int skb_end_offset(const struct sk_buff *skb)
 662{
 663        return skb->end;
 664}
 665#else
 666static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
 667{
 668        return skb->end;
 669}
 670
 671static inline unsigned int skb_end_offset(const struct sk_buff *skb)
 672{
 673        return skb->end - skb->head;
 674}
 675#endif
 676
 677/* Internal */
 678#define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
 679
 680static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
 681{
 682        return &skb_shinfo(skb)->hwtstamps;
 683}
 684
 685/**
 686 *      skb_queue_empty - check if a queue is empty
 687 *      @list: queue head
 688 *
 689 *      Returns true if the queue is empty, false otherwise.
 690 */
 691static inline int skb_queue_empty(const struct sk_buff_head *list)
 692{
 693        return list->next == (struct sk_buff *)list;
 694}
 695
 696/**
 697 *      skb_queue_is_last - check if skb is the last entry in the queue
 698 *      @list: queue head
 699 *      @skb: buffer
 700 *
 701 *      Returns true if @skb is the last buffer on the list.
 702 */
 703static inline bool skb_queue_is_last(const struct sk_buff_head *list,
 704                                     const struct sk_buff *skb)
 705{
 706        return skb->next == (struct sk_buff *)list;
 707}
 708
 709/**
 710 *      skb_queue_is_first - check if skb is the first entry in the queue
 711 *      @list: queue head
 712 *      @skb: buffer
 713 *
 714 *      Returns true if @skb is the first buffer on the list.
 715 */
 716static inline bool skb_queue_is_first(const struct sk_buff_head *list,
 717                                      const struct sk_buff *skb)
 718{
 719        return skb->prev == (struct sk_buff *)list;
 720}
 721
 722/**
 723 *      skb_queue_next - return the next packet in the queue
 724 *      @list: queue head
 725 *      @skb: current buffer
 726 *
 727 *      Return the next packet in @list after @skb.  It is only valid to
 728 *      call this if skb_queue_is_last() evaluates to false.
 729 */
 730static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
 731                                             const struct sk_buff *skb)
 732{
 733        /* This BUG_ON may seem severe, but if we just return then we
 734         * are going to dereference garbage.
 735         */
 736        BUG_ON(skb_queue_is_last(list, skb));
 737        return skb->next;
 738}
 739
 740/**
 741 *      skb_queue_prev - return the prev packet in the queue
 742 *      @list: queue head
 743 *      @skb: current buffer
 744 *
 745 *      Return the prev packet in @list before @skb.  It is only valid to
 746 *      call this if skb_queue_is_first() evaluates to false.
 747 */
 748static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
 749                                             const struct sk_buff *skb)
 750{
 751        /* This BUG_ON may seem severe, but if we just return then we
 752         * are going to dereference garbage.
 753         */
 754        BUG_ON(skb_queue_is_first(list, skb));
 755        return skb->prev;
 756}
 757
 758/**
 759 *      skb_get - reference buffer
 760 *      @skb: buffer to reference
 761 *
 762 *      Makes another reference to a socket buffer and returns a pointer
 763 *      to the buffer.
 764 */
 765static inline struct sk_buff *skb_get(struct sk_buff *skb)
 766{
 767        atomic_inc(&skb->users);
 768        return skb;
 769}
 770
 771/*
 772 * If users == 1, we are the only owner and are can avoid redundant
 773 * atomic change.
 774 */
 775
 776/**
 777 *      skb_cloned - is the buffer a clone
 778 *      @skb: buffer to check
 779 *
 780 *      Returns true if the buffer was generated with skb_clone() and is
 781 *      one of multiple shared copies of the buffer. Cloned buffers are
 782 *      shared data so must not be written to under normal circumstances.
 783 */
 784static inline int skb_cloned(const struct sk_buff *skb)
 785{
 786        return skb->cloned &&
 787               (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
 788}
 789
 790/**
 791 *      skb_header_cloned - is the header a clone
 792 *      @skb: buffer to check
 793 *
 794 *      Returns true if modifying the header part of the buffer requires
 795 *      the data to be copied.
 796 */
 797static inline int skb_header_cloned(const struct sk_buff *skb)
 798{
 799        int dataref;
 800
 801        if (!skb->cloned)
 802                return 0;
 803
 804        dataref = atomic_read(&skb_shinfo(skb)->dataref);
 805        dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
 806        return dataref != 1;
 807}
 808
 809/**
 810 *      skb_header_release - release reference to header
 811 *      @skb: buffer to operate on
 812 *
 813 *      Drop a reference to the header part of the buffer.  This is done
 814 *      by acquiring a payload reference.  You must not read from the header
 815 *      part of skb->data after this.
 816 */
 817static inline void skb_header_release(struct sk_buff *skb)
 818{
 819        BUG_ON(skb->nohdr);
 820        skb->nohdr = 1;
 821        atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
 822}
 823
 824/**
 825 *      skb_shared - is the buffer shared
 826 *      @skb: buffer to check
 827 *
 828 *      Returns true if more than one person has a reference to this
 829 *      buffer.
 830 */
 831static inline int skb_shared(const struct sk_buff *skb)
 832{
 833        return atomic_read(&skb->users) != 1;
 834}
 835
 836/**
 837 *      skb_share_check - check if buffer is shared and if so clone it
 838 *      @skb: buffer to check
 839 *      @pri: priority for memory allocation
 840 *
 841 *      If the buffer is shared the buffer is cloned and the old copy
 842 *      drops a reference. A new clone with a single reference is returned.
 843 *      If the buffer is not shared the original buffer is returned. When
 844 *      being called from interrupt status or with spinlocks held pri must
 845 *      be GFP_ATOMIC.
 846 *
 847 *      NULL is returned on a memory allocation failure.
 848 */
 849static inline struct sk_buff *skb_share_check(struct sk_buff *skb,
 850                                              gfp_t pri)
 851{
 852        might_sleep_if(pri & __GFP_WAIT);
 853        if (skb_shared(skb)) {
 854                struct sk_buff *nskb = skb_clone(skb, pri);
 855                kfree_skb(skb);
 856                skb = nskb;
 857        }
 858        return skb;
 859}
 860
 861/*
 862 *      Copy shared buffers into a new sk_buff. We effectively do COW on
 863 *      packets to handle cases where we have a local reader and forward
 864 *      and a couple of other messy ones. The normal one is tcpdumping
 865 *      a packet thats being forwarded.
 866 */
 867
 868/**
 869 *      skb_unshare - make a copy of a shared buffer
 870 *      @skb: buffer to check
 871 *      @pri: priority for memory allocation
 872 *
 873 *      If the socket buffer is a clone then this function creates a new
 874 *      copy of the data, drops a reference count on the old copy and returns
 875 *      the new copy with the reference count at 1. If the buffer is not a clone
 876 *      the original buffer is returned. When called with a spinlock held or
 877 *      from interrupt state @pri must be %GFP_ATOMIC
 878 *
 879 *      %NULL is returned on a memory allocation failure.
 880 */
 881static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
 882                                          gfp_t pri)
 883{
 884        might_sleep_if(pri & __GFP_WAIT);
 885        if (skb_cloned(skb)) {
 886                struct sk_buff *nskb = skb_copy(skb, pri);
 887                kfree_skb(skb); /* Free our shared copy */
 888                skb = nskb;
 889        }
 890        return skb;
 891}
 892
 893/**
 894 *      skb_peek - peek at the head of an &sk_buff_head
 895 *      @list_: list to peek at
 896 *
 897 *      Peek an &sk_buff. Unlike most other operations you _MUST_
 898 *      be careful with this one. A peek leaves the buffer on the
 899 *      list and someone else may run off with it. You must hold
 900 *      the appropriate locks or have a private queue to do this.
 901 *
 902 *      Returns %NULL for an empty list or a pointer to the head element.
 903 *      The reference count is not incremented and the reference is therefore
 904 *      volatile. Use with caution.
 905 */
 906static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
 907{
 908        struct sk_buff *skb = list_->next;
 909
 910        if (skb == (struct sk_buff *)list_)
 911                skb = NULL;
 912        return skb;
 913}
 914
 915/**
 916 *      skb_peek_next - peek skb following the given one from a queue
 917 *      @skb: skb to start from
 918 *      @list_: list to peek at
 919 *
 920 *      Returns %NULL when the end of the list is met or a pointer to the
 921 *      next element. The reference count is not incremented and the
 922 *      reference is therefore volatile. Use with caution.
 923 */
 924static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
 925                const struct sk_buff_head *list_)
 926{
 927        struct sk_buff *next = skb->next;
 928
 929        if (next == (struct sk_buff *)list_)
 930                next = NULL;
 931        return next;
 932}
 933
 934/**
 935 *      skb_peek_tail - peek at the tail of an &sk_buff_head
 936 *      @list_: list to peek at
 937 *
 938 *      Peek an &sk_buff. Unlike most other operations you _MUST_
 939 *      be careful with this one. A peek leaves the buffer on the
 940 *      list and someone else may run off with it. You must hold
 941 *      the appropriate locks or have a private queue to do this.
 942 *
 943 *      Returns %NULL for an empty list or a pointer to the tail element.
 944 *      The reference count is not incremented and the reference is therefore
 945 *      volatile. Use with caution.
 946 */
 947static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
 948{
 949        struct sk_buff *skb = list_->prev;
 950
 951        if (skb == (struct sk_buff *)list_)
 952                skb = NULL;
 953        return skb;
 954
 955}
 956
 957/**
 958 *      skb_queue_len   - get queue length
 959 *      @list_: list to measure
 960 *
 961 *      Return the length of an &sk_buff queue.
 962 */
 963static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
 964{
 965        return list_->qlen;
 966}
 967
 968/**
 969 *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
 970 *      @list: queue to initialize
 971 *
 972 *      This initializes only the list and queue length aspects of
 973 *      an sk_buff_head object.  This allows to initialize the list
 974 *      aspects of an sk_buff_head without reinitializing things like
 975 *      the spinlock.  It can also be used for on-stack sk_buff_head
 976 *      objects where the spinlock is known to not be used.
 977 */
 978static inline void __skb_queue_head_init(struct sk_buff_head *list)
 979{
 980        list->prev = list->next = (struct sk_buff *)list;
 981        list->qlen = 0;
 982}
 983
 984/*
 985 * This function creates a split out lock class for each invocation;
 986 * this is needed for now since a whole lot of users of the skb-queue
 987 * infrastructure in drivers have different locking usage (in hardirq)
 988 * than the networking core (in softirq only). In the long run either the
 989 * network layer or drivers should need annotation to consolidate the
 990 * main types of usage into 3 classes.
 991 */
 992static inline void skb_queue_head_init(struct sk_buff_head *list)
 993{
 994        spin_lock_init(&list->lock);
 995        __skb_queue_head_init(list);
 996}
 997
 998static inline void skb_queue_head_init_class(struct sk_buff_head *list,
 999                struct lock_class_key *class)
1000{
1001        skb_queue_head_init(list);
1002        lockdep_set_class(&list->lock, class);
1003}
1004
1005/*
1006 *      Insert an sk_buff on a list.
1007 *
1008 *      The "__skb_xxxx()" functions are the non-atomic ones that
1009 *      can only be called with interrupts disabled.
1010 */
1011extern void        skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
1012static inline void __skb_insert(struct sk_buff *newsk,
1013                                struct sk_buff *prev, struct sk_buff *next,
1014                                struct sk_buff_head *list)
1015{
1016        newsk->next = next;
1017        newsk->prev = prev;
1018        next->prev  = prev->next = newsk;
1019        list->qlen++;
1020}
1021
1022static inline void __skb_queue_splice(const struct sk_buff_head *list,
1023                                      struct sk_buff *prev,
1024                                      struct sk_buff *next)
1025{
1026        struct sk_buff *first = list->next;
1027        struct sk_buff *last = list->prev;
1028
1029        first->prev = prev;
1030        prev->next = first;
1031
1032        last->next = next;
1033        next->prev = last;
1034}
1035
1036/**
1037 *      skb_queue_splice - join two skb lists, this is designed for stacks
1038 *      @list: the new list to add
1039 *      @head: the place to add it in the first list
1040 */
1041static inline void skb_queue_splice(const struct sk_buff_head *list,
1042                                    struct sk_buff_head *head)
1043{
1044        if (!skb_queue_empty(list)) {
1045                __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1046                head->qlen += list->qlen;
1047        }
1048}
1049
1050/**
1051 *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1052 *      @list: the new list to add
1053 *      @head: the place to add it in the first list
1054 *
1055 *      The list at @list is reinitialised
1056 */
1057static inline void skb_queue_splice_init(struct sk_buff_head *list,
1058                                         struct sk_buff_head *head)
1059{
1060        if (!skb_queue_empty(list)) {
1061                __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1062                head->qlen += list->qlen;
1063                __skb_queue_head_init(list);
1064        }
1065}
1066
1067/**
1068 *      skb_queue_splice_tail - join two skb lists, each list being a queue
1069 *      @list: the new list to add
1070 *      @head: the place to add it in the first list
1071 */
1072static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1073                                         struct sk_buff_head *head)
1074{
1075        if (!skb_queue_empty(list)) {
1076                __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1077                head->qlen += list->qlen;
1078        }
1079}
1080
1081/**
1082 *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1083 *      @list: the new list to add
1084 *      @head: the place to add it in the first list
1085 *
1086 *      Each of the lists is a queue.
1087 *      The list at @list is reinitialised
1088 */
1089static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1090                                              struct sk_buff_head *head)
1091{
1092        if (!skb_queue_empty(list)) {
1093                __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1094                head->qlen += list->qlen;
1095                __skb_queue_head_init(list);
1096        }
1097}
1098
1099/**
1100 *      __skb_queue_after - queue a buffer at the list head
1101 *      @list: list to use
1102 *      @prev: place after this buffer
1103 *      @newsk: buffer to queue
1104 *
1105 *      Queue a buffer int the middle of a list. This function takes no locks
1106 *      and you must therefore hold required locks before calling it.
1107 *
1108 *      A buffer cannot be placed on two lists at the same time.
1109 */
1110static inline void __skb_queue_after(struct sk_buff_head *list,
1111                                     struct sk_buff *prev,
1112                                     struct sk_buff *newsk)
1113{
1114        __skb_insert(newsk, prev, prev->next, list);
1115}
1116
1117extern void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1118                       struct sk_buff_head *list);
1119
1120static inline void __skb_queue_before(struct sk_buff_head *list,
1121                                      struct sk_buff *next,
1122                                      struct sk_buff *newsk)
1123{
1124        __skb_insert(newsk, next->prev, next, list);
1125}
1126
1127/**
1128 *      __skb_queue_head - queue a buffer at the list head
1129 *      @list: list to use
1130 *      @newsk: buffer to queue
1131 *
1132 *      Queue a buffer at the start of a list. This function takes no locks
1133 *      and you must therefore hold required locks before calling it.
1134 *
1135 *      A buffer cannot be placed on two lists at the same time.
1136 */
1137extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1138static inline void __skb_queue_head(struct sk_buff_head *list,
1139                                    struct sk_buff *newsk)
1140{
1141        __skb_queue_after(list, (struct sk_buff *)list, newsk);
1142}
1143
1144/**
1145 *      __skb_queue_tail - queue a buffer at the list tail
1146 *      @list: list to use
1147 *      @newsk: buffer to queue
1148 *
1149 *      Queue a buffer at the end of a list. This function takes no locks
1150 *      and you must therefore hold required locks before calling it.
1151 *
1152 *      A buffer cannot be placed on two lists at the same time.
1153 */
1154extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1155static inline void __skb_queue_tail(struct sk_buff_head *list,
1156                                   struct sk_buff *newsk)
1157{
1158        __skb_queue_before(list, (struct sk_buff *)list, newsk);
1159}
1160
1161/*
1162 * remove sk_buff from list. _Must_ be called atomically, and with
1163 * the list known..
1164 */
1165extern void        skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1166static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1167{
1168        struct sk_buff *next, *prev;
1169
1170        list->qlen--;
1171        next       = skb->next;
1172        prev       = skb->prev;
1173        skb->next  = skb->prev = NULL;
1174        next->prev = prev;
1175        prev->next = next;
1176}
1177
1178/**
1179 *      __skb_dequeue - remove from the head of the queue
1180 *      @list: list to dequeue from
1181 *
1182 *      Remove the head of the list. This function does not take any locks
1183 *      so must be used with appropriate locks held only. The head item is
1184 *      returned or %NULL if the list is empty.
1185 */
1186extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1187static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1188{
1189        struct sk_buff *skb = skb_peek(list);
1190        if (skb)
1191                __skb_unlink(skb, list);
1192        return skb;
1193}
1194
1195/**
1196 *      __skb_dequeue_tail - remove from the tail of the queue
1197 *      @list: list to dequeue from
1198 *
1199 *      Remove the tail of the list. This function does not take any locks
1200 *      so must be used with appropriate locks held only. The tail item is
1201 *      returned or %NULL if the list is empty.
1202 */
1203extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1204static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1205{
1206        struct sk_buff *skb = skb_peek_tail(list);
1207        if (skb)
1208                __skb_unlink(skb, list);
1209        return skb;
1210}
1211
1212
1213static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1214{
1215        return skb->data_len;
1216}
1217
1218static inline unsigned int skb_headlen(const struct sk_buff *skb)
1219{
1220        return skb->len - skb->data_len;
1221}
1222
1223static inline int skb_pagelen(const struct sk_buff *skb)
1224{
1225        int i, len = 0;
1226
1227        for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1228                len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1229        return len + skb_headlen(skb);
1230}
1231
1232/**
1233 * __skb_fill_page_desc - initialise a paged fragment in an skb
1234 * @skb: buffer containing fragment to be initialised
1235 * @i: paged fragment index to initialise
1236 * @page: the page to use for this fragment
1237 * @off: the offset to the data with @page
1238 * @size: the length of the data
1239 *
1240 * Initialises the @i'th fragment of @skb to point to &size bytes at
1241 * offset @off within @page.
1242 *
1243 * Does not take any additional reference on the fragment.
1244 */
1245static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1246                                        struct page *page, int off, int size)
1247{
1248        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1249
1250        /*
1251         * Propagate page->pfmemalloc to the skb if we can. The problem is
1252         * that not all callers have unique ownership of the page. If
1253         * pfmemalloc is set, we check the mapping as a mapping implies
1254         * page->index is set (index and pfmemalloc share space).
1255         * If it's a valid mapping, we cannot use page->pfmemalloc but we
1256         * do not lose pfmemalloc information as the pages would not be
1257         * allocated using __GFP_MEMALLOC.
1258         */
1259        if (page->pfmemalloc && !page->mapping)
1260                skb->pfmemalloc = true;
1261        frag->page.p              = page;
1262        frag->page_offset         = off;
1263        skb_frag_size_set(frag, size);
1264}
1265
1266/**
1267 * skb_fill_page_desc - initialise a paged fragment in an skb
1268 * @skb: buffer containing fragment to be initialised
1269 * @i: paged fragment index to initialise
1270 * @page: the page to use for this fragment
1271 * @off: the offset to the data with @page
1272 * @size: the length of the data
1273 *
1274 * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1275 * @skb to point to &size bytes at offset @off within @page. In
1276 * addition updates @skb such that @i is the last fragment.
1277 *
1278 * Does not take any additional reference on the fragment.
1279 */
1280static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1281                                      struct page *page, int off, int size)
1282{
1283        __skb_fill_page_desc(skb, i, page, off, size);
1284        skb_shinfo(skb)->nr_frags = i + 1;
1285}
1286
1287extern void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page,
1288                            int off, int size, unsigned int truesize);
1289
1290#define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1291#define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1292#define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1293
1294#ifdef NET_SKBUFF_DATA_USES_OFFSET
1295static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1296{
1297        return skb->head + skb->tail;
1298}
1299
1300static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1301{
1302        skb->tail = skb->data - skb->head;
1303}
1304
1305static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1306{
1307        skb_reset_tail_pointer(skb);
1308        skb->tail += offset;
1309}
1310#else /* NET_SKBUFF_DATA_USES_OFFSET */
1311static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1312{
1313        return skb->tail;
1314}
1315
1316static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1317{
1318        skb->tail = skb->data;
1319}
1320
1321static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1322{
1323        skb->tail = skb->data + offset;
1324}
1325
1326#endif /* NET_SKBUFF_DATA_USES_OFFSET */
1327
1328/*
1329 *      Add data to an sk_buff
1330 */
1331extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1332static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1333{
1334        unsigned char *tmp = skb_tail_pointer(skb);
1335        SKB_LINEAR_ASSERT(skb);
1336        skb->tail += len;
1337        skb->len  += len;
1338        return tmp;
1339}
1340
1341extern unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1342static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1343{
1344        skb->data -= len;
1345        skb->len  += len;
1346        return skb->data;
1347}
1348
1349extern unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1350static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1351{
1352        skb->len -= len;
1353        BUG_ON(skb->len < skb->data_len);
1354        return skb->data += len;
1355}
1356
1357static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1358{
1359        return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1360}
1361
1362extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1363
1364static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1365{
1366        if (len > skb_headlen(skb) &&
1367            !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1368                return NULL;
1369        skb->len -= len;
1370        return skb->data += len;
1371}
1372
1373static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1374{
1375        return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1376}
1377
1378static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1379{
1380        if (likely(len <= skb_headlen(skb)))
1381                return 1;
1382        if (unlikely(len > skb->len))
1383                return 0;
1384        return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1385}
1386
1387/**
1388 *      skb_headroom - bytes at buffer head
1389 *      @skb: buffer to check
1390 *
1391 *      Return the number of bytes of free space at the head of an &sk_buff.
1392 */
1393static inline unsigned int skb_headroom(const struct sk_buff *skb)
1394{
1395        return skb->data - skb->head;
1396}
1397
1398/**
1399 *      skb_tailroom - bytes at buffer end
1400 *      @skb: buffer to check
1401 *
1402 *      Return the number of bytes of free space at the tail of an sk_buff
1403 */
1404static inline int skb_tailroom(const struct sk_buff *skb)
1405{
1406        return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1407}
1408
1409/**
1410 *      skb_availroom - bytes at buffer end
1411 *      @skb: buffer to check
1412 *
1413 *      Return the number of bytes of free space at the tail of an sk_buff
1414 *      allocated by sk_stream_alloc()
1415 */
1416static inline int skb_availroom(const struct sk_buff *skb)
1417{
1418        return skb_is_nonlinear(skb) ? 0 : skb->avail_size - skb->len;
1419}
1420
1421/**
1422 *      skb_reserve - adjust headroom
1423 *      @skb: buffer to alter
1424 *      @len: bytes to move
1425 *
1426 *      Increase the headroom of an empty &sk_buff by reducing the tail
1427 *      room. This is only allowed for an empty buffer.
1428 */
1429static inline void skb_reserve(struct sk_buff *skb, int len)
1430{
1431        skb->data += len;
1432        skb->tail += len;
1433}
1434
1435static inline void skb_reset_mac_len(struct sk_buff *skb)
1436{
1437        skb->mac_len = skb->network_header - skb->mac_header;
1438}
1439
1440#ifdef NET_SKBUFF_DATA_USES_OFFSET
1441static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1442{
1443        return skb->head + skb->transport_header;
1444}
1445
1446static inline void skb_reset_transport_header(struct sk_buff *skb)
1447{
1448        skb->transport_header = skb->data - skb->head;
1449}
1450
1451static inline void skb_set_transport_header(struct sk_buff *skb,
1452                                            const int offset)
1453{
1454        skb_reset_transport_header(skb);
1455        skb->transport_header += offset;
1456}
1457
1458static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1459{
1460        return skb->head + skb->network_header;
1461}
1462
1463static inline void skb_reset_network_header(struct sk_buff *skb)
1464{
1465        skb->network_header = skb->data - skb->head;
1466}
1467
1468static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1469{
1470        skb_reset_network_header(skb);
1471        skb->network_header += offset;
1472}
1473
1474static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1475{
1476        return skb->head + skb->mac_header;
1477}
1478
1479static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1480{
1481        return skb->mac_header != ~0U;
1482}
1483
1484static inline void skb_reset_mac_header(struct sk_buff *skb)
1485{
1486        skb->mac_header = skb->data - skb->head;
1487}
1488
1489static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1490{
1491        skb_reset_mac_header(skb);
1492        skb->mac_header += offset;
1493}
1494
1495#else /* NET_SKBUFF_DATA_USES_OFFSET */
1496
1497static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1498{
1499        return skb->transport_header;
1500}
1501
1502static inline void skb_reset_transport_header(struct sk_buff *skb)
1503{
1504        skb->transport_header = skb->data;
1505}
1506
1507static inline void skb_set_transport_header(struct sk_buff *skb,
1508                                            const int offset)
1509{
1510        skb->transport_header = skb->data + offset;
1511}
1512
1513static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1514{
1515        return skb->network_header;
1516}
1517
1518static inline void skb_reset_network_header(struct sk_buff *skb)
1519{
1520        skb->network_header = skb->data;
1521}
1522
1523static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1524{
1525        skb->network_header = skb->data + offset;
1526}
1527
1528static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1529{
1530        return skb->mac_header;
1531}
1532
1533static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1534{
1535        return skb->mac_header != NULL;
1536}
1537
1538static inline void skb_reset_mac_header(struct sk_buff *skb)
1539{
1540        skb->mac_header = skb->data;
1541}
1542
1543static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1544{
1545        skb->mac_header = skb->data + offset;
1546}
1547#endif /* NET_SKBUFF_DATA_USES_OFFSET */
1548
1549static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1550{
1551        if (skb_mac_header_was_set(skb)) {
1552                const unsigned char *old_mac = skb_mac_header(skb);
1553
1554                skb_set_mac_header(skb, -skb->mac_len);
1555                memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1556        }
1557}
1558
1559static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1560{
1561        return skb->csum_start - skb_headroom(skb);
1562}
1563
1564static inline int skb_transport_offset(const struct sk_buff *skb)
1565{
1566        return skb_transport_header(skb) - skb->data;
1567}
1568
1569static inline u32 skb_network_header_len(const struct sk_buff *skb)
1570{
1571        return skb->transport_header - skb->network_header;
1572}
1573
1574static inline int skb_network_offset(const struct sk_buff *skb)
1575{
1576        return skb_network_header(skb) - skb->data;
1577}
1578
1579static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1580{
1581        return pskb_may_pull(skb, skb_network_offset(skb) + len);
1582}
1583
1584/*
1585 * CPUs often take a performance hit when accessing unaligned memory
1586 * locations. The actual performance hit varies, it can be small if the
1587 * hardware handles it or large if we have to take an exception and fix it
1588 * in software.
1589 *
1590 * Since an ethernet header is 14 bytes network drivers often end up with
1591 * the IP header at an unaligned offset. The IP header can be aligned by
1592 * shifting the start of the packet by 2 bytes. Drivers should do this
1593 * with:
1594 *
1595 * skb_reserve(skb, NET_IP_ALIGN);
1596 *
1597 * The downside to this alignment of the IP header is that the DMA is now
1598 * unaligned. On some architectures the cost of an unaligned DMA is high
1599 * and this cost outweighs the gains made by aligning the IP header.
1600 *
1601 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1602 * to be overridden.
1603 */
1604#ifndef NET_IP_ALIGN
1605#define NET_IP_ALIGN    2
1606#endif
1607
1608/*
1609 * The networking layer reserves some headroom in skb data (via
1610 * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1611 * the header has to grow. In the default case, if the header has to grow
1612 * 32 bytes or less we avoid the reallocation.
1613 *
1614 * Unfortunately this headroom changes the DMA alignment of the resulting
1615 * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1616 * on some architectures. An architecture can override this value,
1617 * perhaps setting it to a cacheline in size (since that will maintain
1618 * cacheline alignment of the DMA). It must be a power of 2.
1619 *
1620 * Various parts of the networking layer expect at least 32 bytes of
1621 * headroom, you should not reduce this.
1622 *
1623 * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
1624 * to reduce average number of cache lines per packet.
1625 * get_rps_cpus() for example only access one 64 bytes aligned block :
1626 * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
1627 */
1628#ifndef NET_SKB_PAD
1629#define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
1630#endif
1631
1632extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1633
1634static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1635{
1636        if (unlikely(skb_is_nonlinear(skb))) {
1637                WARN_ON(1);
1638                return;
1639        }
1640        skb->len = len;
1641        skb_set_tail_pointer(skb, len);
1642}
1643
1644extern void skb_trim(struct sk_buff *skb, unsigned int len);
1645
1646static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1647{
1648        if (skb->data_len)
1649                return ___pskb_trim(skb, len);
1650        __skb_trim(skb, len);
1651        return 0;
1652}
1653
1654static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1655{
1656        return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1657}
1658
1659/**
1660 *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1661 *      @skb: buffer to alter
1662 *      @len: new length
1663 *
1664 *      This is identical to pskb_trim except that the caller knows that
1665 *      the skb is not cloned so we should never get an error due to out-
1666 *      of-memory.
1667 */
1668static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1669{
1670        int err = pskb_trim(skb, len);
1671        BUG_ON(err);
1672}
1673
1674/**
1675 *      skb_orphan - orphan a buffer
1676 *      @skb: buffer to orphan
1677 *
1678 *      If a buffer currently has an owner then we call the owner's
1679 *      destructor function and make the @skb unowned. The buffer continues
1680 *      to exist but is no longer charged to its former owner.
1681 */
1682static inline void skb_orphan(struct sk_buff *skb)
1683{
1684        if (skb->destructor)
1685                skb->destructor(skb);
1686        skb->destructor = NULL;
1687        skb->sk         = NULL;
1688}
1689
1690/**
1691 *      skb_orphan_frags - orphan the frags contained in a buffer
1692 *      @skb: buffer to orphan frags from
1693 *      @gfp_mask: allocation mask for replacement pages
1694 *
1695 *      For each frag in the SKB which needs a destructor (i.e. has an
1696 *      owner) create a copy of that frag and release the original
1697 *      page by calling the destructor.
1698 */
1699static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
1700{
1701        if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
1702                return 0;
1703        return skb_copy_ubufs(skb, gfp_mask);
1704}
1705
1706/**
1707 *      __skb_queue_purge - empty a list
1708 *      @list: list to empty
1709 *
1710 *      Delete all buffers on an &sk_buff list. Each buffer is removed from
1711 *      the list and one reference dropped. This function does not take the
1712 *      list lock and the caller must hold the relevant locks to use it.
1713 */
1714extern void skb_queue_purge(struct sk_buff_head *list);
1715static inline void __skb_queue_purge(struct sk_buff_head *list)
1716{
1717        struct sk_buff *skb;
1718        while ((skb = __skb_dequeue(list)) != NULL)
1719                kfree_skb(skb);
1720}
1721
1722extern void *netdev_alloc_frag(unsigned int fragsz);
1723
1724extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
1725                                          unsigned int length,
1726                                          gfp_t gfp_mask);
1727
1728/**
1729 *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
1730 *      @dev: network device to receive on
1731 *      @length: length to allocate
1732 *
1733 *      Allocate a new &sk_buff and assign it a usage count of one. The
1734 *      buffer has unspecified headroom built in. Users should allocate
1735 *      the headroom they think they need without accounting for the
1736 *      built in space. The built in space is used for optimisations.
1737 *
1738 *      %NULL is returned if there is no free memory. Although this function
1739 *      allocates memory it can be called from an interrupt.
1740 */
1741static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
1742                                               unsigned int length)
1743{
1744        return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
1745}
1746
1747/* legacy helper around __netdev_alloc_skb() */
1748static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
1749                                              gfp_t gfp_mask)
1750{
1751        return __netdev_alloc_skb(NULL, length, gfp_mask);
1752}
1753
1754/* legacy helper around netdev_alloc_skb() */
1755static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1756{
1757        return netdev_alloc_skb(NULL, length);
1758}
1759
1760
1761static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
1762                unsigned int length, gfp_t gfp)
1763{
1764        struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
1765
1766        if (NET_IP_ALIGN && skb)
1767                skb_reserve(skb, NET_IP_ALIGN);
1768        return skb;
1769}
1770
1771static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
1772                unsigned int length)
1773{
1774        return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
1775}
1776
1777/*
1778 *      __skb_alloc_page - allocate pages for ps-rx on a skb and preserve pfmemalloc data
1779 *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1780 *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1781 *      @order: size of the allocation
1782 *
1783 *      Allocate a new page.
1784 *
1785 *      %NULL is returned if there is no free memory.
1786*/
1787static inline struct page *__skb_alloc_pages(gfp_t gfp_mask,
1788                                              struct sk_buff *skb,
1789                                              unsigned int order)
1790{
1791        struct page *page;
1792
1793        gfp_mask |= __GFP_COLD;
1794
1795        if (!(gfp_mask & __GFP_NOMEMALLOC))
1796                gfp_mask |= __GFP_MEMALLOC;
1797
1798        page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
1799        if (skb && page && page->pfmemalloc)
1800                skb->pfmemalloc = true;
1801
1802        return page;
1803}
1804
1805/**
1806 *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
1807 *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1808 *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1809 *
1810 *      Allocate a new page.
1811 *
1812 *      %NULL is returned if there is no free memory.
1813 */
1814static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
1815                                             struct sk_buff *skb)
1816{
1817        return __skb_alloc_pages(gfp_mask, skb, 0);
1818}
1819
1820/**
1821 *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
1822 *      @page: The page that was allocated from skb_alloc_page
1823 *      @skb: The skb that may need pfmemalloc set
1824 */
1825static inline void skb_propagate_pfmemalloc(struct page *page,
1826                                             struct sk_buff *skb)
1827{
1828        if (page && page->pfmemalloc)
1829                skb->pfmemalloc = true;
1830}
1831
1832/**
1833 * skb_frag_page - retrieve the page refered to by a paged fragment
1834 * @frag: the paged fragment
1835 *
1836 * Returns the &struct page associated with @frag.
1837 */
1838static inline struct page *skb_frag_page(const skb_frag_t *frag)
1839{
1840        return frag->page.p;
1841}
1842
1843/**
1844 * __skb_frag_ref - take an addition reference on a paged fragment.
1845 * @frag: the paged fragment
1846 *
1847 * Takes an additional reference on the paged fragment @frag.
1848 */
1849static inline void __skb_frag_ref(skb_frag_t *frag)
1850{
1851        get_page(skb_frag_page(frag));
1852}
1853
1854/**
1855 * skb_frag_ref - take an addition reference on a paged fragment of an skb.
1856 * @skb: the buffer
1857 * @f: the fragment offset.
1858 *
1859 * Takes an additional reference on the @f'th paged fragment of @skb.
1860 */
1861static inline void skb_frag_ref(struct sk_buff *skb, int f)
1862{
1863        __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
1864}
1865
1866/**
1867 * __skb_frag_unref - release a reference on a paged fragment.
1868 * @frag: the paged fragment
1869 *
1870 * Releases a reference on the paged fragment @frag.
1871 */
1872static inline void __skb_frag_unref(skb_frag_t *frag)
1873{
1874        put_page(skb_frag_page(frag));
1875}
1876
1877/**
1878 * skb_frag_unref - release a reference on a paged fragment of an skb.
1879 * @skb: the buffer
1880 * @f: the fragment offset
1881 *
1882 * Releases a reference on the @f'th paged fragment of @skb.
1883 */
1884static inline void skb_frag_unref(struct sk_buff *skb, int f)
1885{
1886        __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
1887}
1888
1889/**
1890 * skb_frag_address - gets the address of the data contained in a paged fragment
1891 * @frag: the paged fragment buffer
1892 *
1893 * Returns the address of the data within @frag. The page must already
1894 * be mapped.
1895 */
1896static inline void *skb_frag_address(const skb_frag_t *frag)
1897{
1898        return page_address(skb_frag_page(frag)) + frag->page_offset;
1899}
1900
1901/**
1902 * skb_frag_address_safe - gets the address of the data contained in a paged fragment
1903 * @frag: the paged fragment buffer
1904 *
1905 * Returns the address of the data within @frag. Checks that the page
1906 * is mapped and returns %NULL otherwise.
1907 */
1908static inline void *skb_frag_address_safe(const skb_frag_t *frag)
1909{
1910        void *ptr = page_address(skb_frag_page(frag));
1911        if (unlikely(!ptr))
1912                return NULL;
1913
1914        return ptr + frag->page_offset;
1915}
1916
1917/**
1918 * __skb_frag_set_page - sets the page contained in a paged fragment
1919 * @frag: the paged fragment
1920 * @page: the page to set
1921 *
1922 * Sets the fragment @frag to contain @page.
1923 */
1924static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
1925{
1926        frag->page.p = page;
1927}
1928
1929/**
1930 * skb_frag_set_page - sets the page contained in a paged fragment of an skb
1931 * @skb: the buffer
1932 * @f: the fragment offset
1933 * @page: the page to set
1934 *
1935 * Sets the @f'th fragment of @skb to contain @page.
1936 */
1937static inline void skb_frag_set_page(struct sk_buff *skb, int f,
1938                                     struct page *page)
1939{
1940        __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
1941}
1942
1943/**
1944 * skb_frag_dma_map - maps a paged fragment via the DMA API
1945 * @dev: the device to map the fragment to
1946 * @frag: the paged fragment to map
1947 * @offset: the offset within the fragment (starting at the
1948 *          fragment's own offset)
1949 * @size: the number of bytes to map
1950 * @dir: the direction of the mapping (%PCI_DMA_*)
1951 *
1952 * Maps the page associated with @frag to @device.
1953 */
1954static inline dma_addr_t skb_frag_dma_map(struct device *dev,
1955                                          const skb_frag_t *frag,
1956                                          size_t offset, size_t size,
1957                                          enum dma_data_direction dir)
1958{
1959        return dma_map_page(dev, skb_frag_page(frag),
1960                            frag->page_offset + offset, size, dir);
1961}
1962
1963static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
1964                                        gfp_t gfp_mask)
1965{
1966        return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
1967}
1968
1969/**
1970 *      skb_clone_writable - is the header of a clone writable
1971 *      @skb: buffer to check
1972 *      @len: length up to which to write
1973 *
1974 *      Returns true if modifying the header part of the cloned buffer
1975 *      does not requires the data to be copied.
1976 */
1977static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
1978{
1979        return !skb_header_cloned(skb) &&
1980               skb_headroom(skb) + len <= skb->hdr_len;
1981}
1982
1983static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
1984                            int cloned)
1985{
1986        int delta = 0;
1987
1988        if (headroom > skb_headroom(skb))
1989                delta = headroom - skb_headroom(skb);
1990
1991        if (delta || cloned)
1992                return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
1993                                        GFP_ATOMIC);
1994        return 0;
1995}
1996
1997/**
1998 *      skb_cow - copy header of skb when it is required
1999 *      @skb: buffer to cow
2000 *      @headroom: needed headroom
2001 *
2002 *      If the skb passed lacks sufficient headroom or its data part
2003 *      is shared, data is reallocated. If reallocation fails, an error
2004 *      is returned and original skb is not changed.
2005 *
2006 *      The result is skb with writable area skb->head...skb->tail
2007 *      and at least @headroom of space at head.
2008 */
2009static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2010{
2011        return __skb_cow(skb, headroom, skb_cloned(skb));
2012}
2013
2014/**
2015 *      skb_cow_head - skb_cow but only making the head writable
2016 *      @skb: buffer to cow
2017 *      @headroom: needed headroom
2018 *
2019 *      This function is identical to skb_cow except that we replace the
2020 *      skb_cloned check by skb_header_cloned.  It should be used when
2021 *      you only need to push on some header and do not need to modify
2022 *      the data.
2023 */
2024static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2025{
2026        return __skb_cow(skb, headroom, skb_header_cloned(skb));
2027}
2028
2029/**
2030 *      skb_padto       - pad an skbuff up to a minimal size
2031 *      @skb: buffer to pad
2032 *      @len: minimal length
2033 *
2034 *      Pads up a buffer to ensure the trailing bytes exist and are
2035 *      blanked. If the buffer already contains sufficient data it
2036 *      is untouched. Otherwise it is extended. Returns zero on
2037 *      success. The skb is freed on error.
2038 */
2039 
2040static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2041{
2042        unsigned int size = skb->len;
2043        if (likely(size >= len))
2044                return 0;
2045        return skb_pad(skb, len - size);
2046}
2047
2048static inline int skb_add_data(struct sk_buff *skb,
2049                               char __user *from, int copy)
2050{
2051        const int off = skb->len;
2052
2053        if (skb->ip_summed == CHECKSUM_NONE) {
2054                int err = 0;
2055                __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2056                                                            copy, 0, &err);
2057                if (!err) {
2058                        skb->csum = csum_block_add(skb->csum, csum, off);
2059                        return 0;
2060                }
2061        } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2062                return 0;
2063
2064        __skb_trim(skb, off);
2065        return -EFAULT;
2066}
2067
2068static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2069                                    const struct page *page, int off)
2070{
2071        if (i) {
2072                const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2073
2074                return page == skb_frag_page(frag) &&
2075                       off == frag->page_offset + skb_frag_size(frag);
2076        }
2077        return false;
2078}
2079
2080static inline int __skb_linearize(struct sk_buff *skb)
2081{
2082        return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2083}
2084
2085/**
2086 *      skb_linearize - convert paged skb to linear one
2087 *      @skb: buffer to linarize
2088 *
2089 *      If there is no free memory -ENOMEM is returned, otherwise zero
2090 *      is returned and the old skb data released.
2091 */
2092static inline int skb_linearize(struct sk_buff *skb)
2093{
2094        return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2095}
2096
2097/**
2098 *      skb_linearize_cow - make sure skb is linear and writable
2099 *      @skb: buffer to process
2100 *
2101 *      If there is no free memory -ENOMEM is returned, otherwise zero
2102 *      is returned and the old skb data released.
2103 */
2104static inline int skb_linearize_cow(struct sk_buff *skb)
2105{
2106        return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2107               __skb_linearize(skb) : 0;
2108}
2109
2110/**
2111 *      skb_postpull_rcsum - update checksum for received skb after pull
2112 *      @skb: buffer to update
2113 *      @start: start of data before pull
2114 *      @len: length of data pulled
2115 *
2116 *      After doing a pull on a received packet, you need to call this to
2117 *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2118 *      CHECKSUM_NONE so that it can be recomputed from scratch.
2119 */
2120
2121static inline void skb_postpull_rcsum(struct sk_buff *skb,
2122                                      const void *start, unsigned int len)
2123{
2124        if (skb->ip_summed == CHECKSUM_COMPLETE)
2125                skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2126}
2127
2128unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2129
2130/**
2131 *      pskb_trim_rcsum - trim received skb and update checksum
2132 *      @skb: buffer to trim
2133 *      @len: new length
2134 *
2135 *      This is exactly the same as pskb_trim except that it ensures the
2136 *      checksum of received packets are still valid after the operation.
2137 */
2138
2139static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2140{
2141        if (likely(len >= skb->len))
2142                return 0;
2143        if (skb->ip_summed == CHECKSUM_COMPLETE)
2144                skb->ip_summed = CHECKSUM_NONE;
2145        return __pskb_trim(skb, len);
2146}
2147
2148#define skb_queue_walk(queue, skb) \
2149                for (skb = (queue)->next;                                       \
2150                     skb != (struct sk_buff *)(queue);                          \
2151                     skb = skb->next)
2152
2153#define skb_queue_walk_safe(queue, skb, tmp)                                    \
2154                for (skb = (queue)->next, tmp = skb->next;                      \
2155                     skb != (struct sk_buff *)(queue);                          \
2156                     skb = tmp, tmp = skb->next)
2157
2158#define skb_queue_walk_from(queue, skb)                                         \
2159                for (; skb != (struct sk_buff *)(queue);                        \
2160                     skb = skb->next)
2161
2162#define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2163                for (tmp = skb->next;                                           \
2164                     skb != (struct sk_buff *)(queue);                          \
2165                     skb = tmp, tmp = skb->next)
2166
2167#define skb_queue_reverse_walk(queue, skb) \
2168                for (skb = (queue)->prev;                                       \
2169                     skb != (struct sk_buff *)(queue);                          \
2170                     skb = skb->prev)
2171
2172#define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2173                for (skb = (queue)->prev, tmp = skb->prev;                      \
2174                     skb != (struct sk_buff *)(queue);                          \
2175                     skb = tmp, tmp = skb->prev)
2176
2177#define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2178                for (tmp = skb->prev;                                           \
2179                     skb != (struct sk_buff *)(queue);                          \
2180                     skb = tmp, tmp = skb->prev)
2181
2182static inline bool skb_has_frag_list(const struct sk_buff *skb)
2183{
2184        return skb_shinfo(skb)->frag_list != NULL;
2185}
2186
2187static inline void skb_frag_list_init(struct sk_buff *skb)
2188{
2189        skb_shinfo(skb)->frag_list = NULL;
2190}
2191
2192static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2193{
2194        frag->next = skb_shinfo(skb)->frag_list;
2195        skb_shinfo(skb)->frag_list = frag;
2196}
2197
2198#define skb_walk_frags(skb, iter)       \
2199        for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2200
2201extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2202                                           int *peeked, int *off, int *err);
2203extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
2204                                         int noblock, int *err);
2205extern unsigned int    datagram_poll(struct file *file, struct socket *sock,
2206                                     struct poll_table_struct *wait);
2207extern int             skb_copy_datagram_iovec(const struct sk_buff *from,
2208                                               int offset, struct iovec *to,
2209                                               int size);
2210extern int             skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
2211                                                        int hlen,
2212                                                        struct iovec *iov);
2213extern int             skb_copy_datagram_from_iovec(struct sk_buff *skb,
2214                                                    int offset,
2215                                                    const struct iovec *from,
2216                                                    int from_offset,
2217                                                    int len);
2218extern int             skb_copy_datagram_const_iovec(const struct sk_buff *from,
2219                                                     int offset,
2220                                                     const struct iovec *to,
2221                                                     int to_offset,
2222                                                     int size);
2223extern void            skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2224extern void            skb_free_datagram_locked(struct sock *sk,
2225                                                struct sk_buff *skb);
2226extern int             skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
2227                                         unsigned int flags);
2228extern __wsum          skb_checksum(const struct sk_buff *skb, int offset,
2229                                    int len, __wsum csum);
2230extern int             skb_copy_bits(const struct sk_buff *skb, int offset,
2231                                     void *to, int len);
2232extern int             skb_store_bits(struct sk_buff *skb, int offset,
2233                                      const void *from, int len);
2234extern __wsum          skb_copy_and_csum_bits(const struct sk_buff *skb,
2235                                              int offset, u8 *to, int len,
2236                                              __wsum csum);
2237extern int             skb_splice_bits(struct sk_buff *skb,
2238                                                unsigned int offset,
2239                                                struct pipe_inode_info *pipe,
2240                                                unsigned int len,
2241                                                unsigned int flags);
2242extern void            skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2243extern void            skb_split(struct sk_buff *skb,
2244                                 struct sk_buff *skb1, const u32 len);
2245extern int             skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
2246                                 int shiftlen);
2247
2248extern struct sk_buff *skb_segment(struct sk_buff *skb,
2249                                   netdev_features_t features);
2250
2251static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2252                                       int len, void *buffer)
2253{
2254        int hlen = skb_headlen(skb);
2255
2256        if (hlen - offset >= len)
2257                return skb->data + offset;
2258
2259        if (skb_copy_bits(skb, offset, buffer, len) < 0)
2260                return NULL;
2261
2262        return buffer;
2263}
2264
2265static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2266                                             void *to,
2267                                             const unsigned int len)
2268{
2269        memcpy(to, skb->data, len);
2270}
2271
2272static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2273                                                    const int offset, void *to,
2274                                                    const unsigned int len)
2275{
2276        memcpy(to, skb->data + offset, len);
2277}
2278
2279static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2280                                           const void *from,
2281                                           const unsigned int len)
2282{
2283        memcpy(skb->data, from, len);
2284}
2285
2286static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2287                                                  const int offset,
2288                                                  const void *from,
2289                                                  const unsigned int len)
2290{
2291        memcpy(skb->data + offset, from, len);
2292}
2293
2294extern void skb_init(void);
2295
2296static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2297{
2298        return skb->tstamp;
2299}
2300
2301/**
2302 *      skb_get_timestamp - get timestamp from a skb
2303 *      @skb: skb to get stamp from
2304 *      @stamp: pointer to struct timeval to store stamp in
2305 *
2306 *      Timestamps are stored in the skb as offsets to a base timestamp.
2307 *      This function converts the offset back to a struct timeval and stores
2308 *      it in stamp.
2309 */
2310static inline void skb_get_timestamp(const struct sk_buff *skb,
2311                                     struct timeval *stamp)
2312{
2313        *stamp = ktime_to_timeval(skb->tstamp);
2314}
2315
2316static inline void skb_get_timestampns(const struct sk_buff *skb,
2317                                       struct timespec *stamp)
2318{
2319        *stamp = ktime_to_timespec(skb->tstamp);
2320}
2321
2322static inline void __net_timestamp(struct sk_buff *skb)
2323{
2324        skb->tstamp = ktime_get_real();
2325}
2326
2327static inline ktime_t net_timedelta(ktime_t t)
2328{
2329        return ktime_sub(ktime_get_real(), t);
2330}
2331
2332static inline ktime_t net_invalid_timestamp(void)
2333{
2334        return ktime_set(0, 0);
2335}
2336
2337extern void skb_timestamping_init(void);
2338
2339#ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2340
2341extern void skb_clone_tx_timestamp(struct sk_buff *skb);
2342extern bool skb_defer_rx_timestamp(struct sk_buff *skb);
2343
2344#else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2345
2346static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2347{
2348}
2349
2350static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2351{
2352        return false;
2353}
2354
2355#endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2356
2357/**
2358 * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2359 *
2360 * PHY drivers may accept clones of transmitted packets for
2361 * timestamping via their phy_driver.txtstamp method. These drivers
2362 * must call this function to return the skb back to the stack, with
2363 * or without a timestamp.
2364 *
2365 * @skb: clone of the the original outgoing packet
2366 * @hwtstamps: hardware time stamps, may be NULL if not available
2367 *
2368 */
2369void skb_complete_tx_timestamp(struct sk_buff *skb,
2370                               struct skb_shared_hwtstamps *hwtstamps);
2371
2372/**
2373 * skb_tstamp_tx - queue clone of skb with send time stamps
2374 * @orig_skb:   the original outgoing packet
2375 * @hwtstamps:  hardware time stamps, may be NULL if not available
2376 *
2377 * If the skb has a socket associated, then this function clones the
2378 * skb (thus sharing the actual data and optional structures), stores
2379 * the optional hardware time stamping information (if non NULL) or
2380 * generates a software time stamp (otherwise), then queues the clone
2381 * to the error queue of the socket.  Errors are silently ignored.
2382 */
2383extern void skb_tstamp_tx(struct sk_buff *orig_skb,
2384                        struct skb_shared_hwtstamps *hwtstamps);
2385
2386static inline void sw_tx_timestamp(struct sk_buff *skb)
2387{
2388        if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2389            !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2390                skb_tstamp_tx(skb, NULL);
2391}
2392
2393/**
2394 * skb_tx_timestamp() - Driver hook for transmit timestamping
2395 *
2396 * Ethernet MAC Drivers should call this function in their hard_xmit()
2397 * function immediately before giving the sk_buff to the MAC hardware.
2398 *
2399 * @skb: A socket buffer.
2400 */
2401static inline void skb_tx_timestamp(struct sk_buff *skb)
2402{
2403        skb_clone_tx_timestamp(skb);
2404        sw_tx_timestamp(skb);
2405}
2406
2407/**
2408 * skb_complete_wifi_ack - deliver skb with wifi status
2409 *
2410 * @skb: the original outgoing packet
2411 * @acked: ack status
2412 *
2413 */
2414void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2415
2416extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2417extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
2418
2419static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2420{
2421        return skb->ip_summed & CHECKSUM_UNNECESSARY;
2422}
2423
2424/**
2425 *      skb_checksum_complete - Calculate checksum of an entire packet
2426 *      @skb: packet to process
2427 *
2428 *      This function calculates the checksum over the entire packet plus
2429 *      the value of skb->csum.  The latter can be used to supply the
2430 *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2431 *      checksum.
2432 *
2433 *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2434 *      this function can be used to verify that checksum on received
2435 *      packets.  In that case the function should return zero if the
2436 *      checksum is correct.  In particular, this function will return zero
2437 *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2438 *      hardware has already verified the correctness of the checksum.
2439 */
2440static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2441{
2442        return skb_csum_unnecessary(skb) ?
2443               0 : __skb_checksum_complete(skb);
2444}
2445
2446#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2447extern void nf_conntrack_destroy(struct nf_conntrack *nfct);
2448static inline void nf_conntrack_put(struct nf_conntrack *nfct)
2449{
2450        if (nfct && atomic_dec_and_test(&nfct->use))
2451                nf_conntrack_destroy(nfct);
2452}
2453static inline void nf_conntrack_get(struct nf_conntrack *nfct)
2454{
2455        if (nfct)
2456                atomic_inc(&nfct->use);
2457}
2458#endif
2459#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2460static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
2461{
2462        if (skb)
2463                atomic_inc(&skb->users);
2464}
2465static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
2466{
2467        if (skb)
2468                kfree_skb(skb);
2469}
2470#endif
2471#ifdef CONFIG_BRIDGE_NETFILTER
2472static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
2473{
2474        if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
2475                kfree(nf_bridge);
2476}
2477static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
2478{
2479        if (nf_bridge)
2480                atomic_inc(&nf_bridge->use);
2481}
2482#endif /* CONFIG_BRIDGE_NETFILTER */
2483static inline void nf_reset(struct sk_buff *skb)
2484{
2485#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2486        nf_conntrack_put(skb->nfct);
2487        skb->nfct = NULL;
2488#endif
2489#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2490        nf_conntrack_put_reasm(skb->nfct_reasm);
2491        skb->nfct_reasm = NULL;
2492#endif
2493#ifdef CONFIG_BRIDGE_NETFILTER
2494        nf_bridge_put(skb->nf_bridge);
2495        skb->nf_bridge = NULL;
2496#endif
2497}
2498
2499/* Note: This doesn't put any conntrack and bridge info in dst. */
2500static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2501{
2502#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2503        dst->nfct = src->nfct;
2504        nf_conntrack_get(src->nfct);
2505        dst->nfctinfo = src->nfctinfo;
2506#endif
2507#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2508        dst->nfct_reasm = src->nfct_reasm;
2509        nf_conntrack_get_reasm(src->nfct_reasm);
2510#endif
2511#ifdef CONFIG_BRIDGE_NETFILTER
2512        dst->nf_bridge  = src->nf_bridge;
2513        nf_bridge_get(src->nf_bridge);
2514#endif
2515}
2516
2517static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2518{
2519#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2520        nf_conntrack_put(dst->nfct);
2521#endif
2522#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2523        nf_conntrack_put_reasm(dst->nfct_reasm);
2524#endif
2525#ifdef CONFIG_BRIDGE_NETFILTER
2526        nf_bridge_put(dst->nf_bridge);
2527#endif
2528        __nf_copy(dst, src);
2529}
2530
2531#ifdef CONFIG_NETWORK_SECMARK
2532static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2533{
2534        to->secmark = from->secmark;
2535}
2536
2537static inline void skb_init_secmark(struct sk_buff *skb)
2538{
2539        skb->secmark = 0;
2540}
2541#else
2542static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2543{ }
2544
2545static inline void skb_init_secmark(struct sk_buff *skb)
2546{ }
2547#endif
2548
2549static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
2550{
2551        skb->queue_mapping = queue_mapping;
2552}
2553
2554static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2555{
2556        return skb->queue_mapping;
2557}
2558
2559static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
2560{
2561        to->queue_mapping = from->queue_mapping;
2562}
2563
2564static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
2565{
2566        skb->queue_mapping = rx_queue + 1;
2567}
2568
2569static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
2570{
2571        return skb->queue_mapping - 1;
2572}
2573
2574static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
2575{
2576        return skb->queue_mapping != 0;
2577}
2578
2579extern u16 __skb_tx_hash(const struct net_device *dev,
2580                         const struct sk_buff *skb,
2581                         unsigned int num_tx_queues);
2582
2583#ifdef CONFIG_XFRM
2584static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2585{
2586        return skb->sp;
2587}
2588#else
2589static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2590{
2591        return NULL;
2592}
2593#endif
2594
2595static inline bool skb_is_gso(const struct sk_buff *skb)
2596{
2597        return skb_shinfo(skb)->gso_size;
2598}
2599
2600static inline bool skb_is_gso_v6(const struct sk_buff *skb)
2601{
2602        return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
2603}
2604
2605extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
2606
2607static inline bool skb_warn_if_lro(const struct sk_buff *skb)
2608{
2609        /* LRO sets gso_size but not gso_type, whereas if GSO is really
2610         * wanted then gso_type will be set. */
2611        const struct skb_shared_info *shinfo = skb_shinfo(skb);
2612
2613        if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
2614            unlikely(shinfo->gso_type == 0)) {
2615                __skb_warn_lro_forwarding(skb);
2616                return true;
2617        }
2618        return false;
2619}
2620
2621static inline void skb_forward_csum(struct sk_buff *skb)
2622{
2623        /* Unfortunately we don't support this one.  Any brave souls? */
2624        if (skb->ip_summed == CHECKSUM_COMPLETE)
2625                skb->ip_summed = CHECKSUM_NONE;
2626}
2627
2628/**
2629 * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
2630 * @skb: skb to check
2631 *
2632 * fresh skbs have their ip_summed set to CHECKSUM_NONE.
2633 * Instead of forcing ip_summed to CHECKSUM_NONE, we can
2634 * use this helper, to document places where we make this assertion.
2635 */
2636static inline void skb_checksum_none_assert(const struct sk_buff *skb)
2637{
2638#ifdef DEBUG
2639        BUG_ON(skb->ip_summed != CHECKSUM_NONE);
2640#endif
2641}
2642
2643bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
2644
2645static inline bool skb_is_recycleable(const struct sk_buff *skb, int skb_size)
2646{
2647        if (irqs_disabled())
2648                return false;
2649
2650        if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)
2651                return false;
2652
2653        if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
2654                return false;
2655
2656        skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
2657        if (skb_end_offset(skb) < skb_size)
2658                return false;
2659
2660        if (skb_shared(skb) || skb_cloned(skb))
2661                return false;
2662
2663        return true;
2664}
2665
2666/**
2667 * skb_head_is_locked - Determine if the skb->head is locked down
2668 * @skb: skb to check
2669 *
2670 * The head on skbs build around a head frag can be removed if they are
2671 * not cloned.  This function returns true if the skb head is locked down
2672 * due to either being allocated via kmalloc, or by being a clone with
2673 * multiple references to the head.
2674 */
2675static inline bool skb_head_is_locked(const struct sk_buff *skb)
2676{
2677        return !skb->head_frag || skb_cloned(skb);
2678}
2679#endif  /* __KERNEL__ */
2680#endif  /* _LINUX_SKBUFF_H */
2681
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