Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0

Linux/include/linux/skbuff.h

  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 #include <linux/rbtree.h>
 24 #include <linux/socket.h>
 25 
 26 #include <linux/atomic.h>
 27 #include <asm/types.h>
 28 #include <linux/spinlock.h>
 29 #include <linux/net.h>
 30 #include <linux/textsearch.h>
 31 #include <net/checksum.h>
 32 #include <linux/rcupdate.h>
 33 #include <linux/hrtimer.h>
 34 #include <linux/dma-mapping.h>
 35 #include <linux/netdev_features.h>
 36 #include <linux/sched.h>
 37 #include <net/flow_keys.h>
 38 
 39 /* A. Checksumming of received packets by device.
 40  *
 41  * CHECKSUM_NONE:
 42  *
 43  *   Device failed to checksum this packet e.g. due to lack of capabilities.
 44  *   The packet contains full (though not verified) checksum in packet but
 45  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 46  *
 47  * CHECKSUM_UNNECESSARY:
 48  *
 49  *   The hardware you're dealing with doesn't calculate the full checksum
 50  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
 51  *   for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
 52  *   if their checksums are okay. skb->csum is still undefined in this case
 53  *   though. It is a bad option, but, unfortunately, nowadays most vendors do
 54  *   this. Apparently with the secret goal to sell you new devices, when you
 55  *   will add new protocol to your host, f.e. IPv6 8)
 56  *
 57  *   CHECKSUM_UNNECESSARY is applicable to following protocols:
 58  *     TCP: IPv6 and IPv4.
 59  *     UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
 60  *       zero UDP checksum for either IPv4 or IPv6, the networking stack
 61  *       may perform further validation in this case.
 62  *     GRE: only if the checksum is present in the header.
 63  *     SCTP: indicates the CRC in SCTP header has been validated.
 64  *
 65  *   skb->csum_level indicates the number of consecutive checksums found in
 66  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
 67  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
 68  *   and a device is able to verify the checksums for UDP (possibly zero),
 69  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
 70  *   two. If the device were only able to verify the UDP checksum and not
 71  *   GRE, either because it doesn't support GRE checksum of because GRE
 72  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
 73  *   not considered in this case).
 74  *
 75  * CHECKSUM_COMPLETE:
 76  *
 77  *   This is the most generic way. The device supplied checksum of the _whole_
 78  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
 79  *   hardware doesn't need to parse L3/L4 headers to implement this.
 80  *
 81  *   Note: Even if device supports only some protocols, but is able to produce
 82  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
 83  *
 84  * CHECKSUM_PARTIAL:
 85  *
 86  *   A checksum is set up to be offloaded to a device as described in the
 87  *   output description for CHECKSUM_PARTIAL. This may occur on a packet
 88  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
 89  *   on the same host, or it may be set in the input path in GRO or remote
 90  *   checksum offload. For the purposes of checksum verification, the checksum
 91  *   referred to by skb->csum_start + skb->csum_offset and any preceding
 92  *   checksums in the packet are considered verified. Any checksums in the
 93  *   packet that are after the checksum being offloaded are not considered to
 94  *   be verified.
 95  *
 96  * B. Checksumming on output.
 97  *
 98  * CHECKSUM_NONE:
 99  *
100  *   The skb was already checksummed by the protocol, or a checksum is not
101  *   required.
102  *
103  * CHECKSUM_PARTIAL:
104  *
105  *   The device is required to checksum the packet as seen by hard_start_xmit()
106  *   from skb->csum_start up to the end, and to record/write the checksum at
107  *   offset skb->csum_start + skb->csum_offset.
108  *
109  *   The device must show its capabilities in dev->features, set up at device
110  *   setup time, e.g. netdev_features.h:
111  *
112  *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
113  *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
114  *                        IPv4. Sigh. Vendors like this way for an unknown reason.
115  *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
116  *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
117  *      NETIF_F_...     - Well, you get the picture.
118  *
119  * CHECKSUM_UNNECESSARY:
120  *
121  *   Normally, the device will do per protocol specific checksumming. Protocol
122  *   implementations that do not want the NIC to perform the checksum
123  *   calculation should use this flag in their outgoing skbs.
124  *
125  *      NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
126  *                         offload. Correspondingly, the FCoE protocol driver
127  *                         stack should use CHECKSUM_UNNECESSARY.
128  *
129  * Any questions? No questions, good.           --ANK
130  */
131 
132 /* Don't change this without changing skb_csum_unnecessary! */
133 #define CHECKSUM_NONE           0
134 #define CHECKSUM_UNNECESSARY    1
135 #define CHECKSUM_COMPLETE       2
136 #define CHECKSUM_PARTIAL        3
137 
138 /* Maximum value in skb->csum_level */
139 #define SKB_MAX_CSUM_LEVEL      3
140 
141 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
142 #define SKB_WITH_OVERHEAD(X)    \
143         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
144 #define SKB_MAX_ORDER(X, ORDER) \
145         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
146 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
147 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
148 
149 /* return minimum truesize of one skb containing X bytes of data */
150 #define SKB_TRUESIZE(X) ((X) +                                          \
151                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
152                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
153 
154 struct net_device;
155 struct scatterlist;
156 struct pipe_inode_info;
157 struct iov_iter;
158 struct napi_struct;
159 
160 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
161 struct nf_conntrack {
162         atomic_t use;
163 };
164 #endif
165 
166 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
167 struct nf_bridge_info {
168         atomic_t                use;
169         unsigned int            mask;
170         struct net_device       *physindev;
171         struct net_device       *physoutdev;
172         unsigned long           data[32 / sizeof(unsigned long)];
173 };
174 #endif
175 
176 struct sk_buff_head {
177         /* These two members must be first. */
178         struct sk_buff  *next;
179         struct sk_buff  *prev;
180 
181         __u32           qlen;
182         spinlock_t      lock;
183 };
184 
185 struct sk_buff;
186 
187 /* To allow 64K frame to be packed as single skb without frag_list we
188  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
189  * buffers which do not start on a page boundary.
190  *
191  * Since GRO uses frags we allocate at least 16 regardless of page
192  * size.
193  */
194 #if (65536/PAGE_SIZE + 1) < 16
195 #define MAX_SKB_FRAGS 16UL
196 #else
197 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
198 #endif
199 
200 typedef struct skb_frag_struct skb_frag_t;
201 
202 struct skb_frag_struct {
203         struct {
204                 struct page *p;
205         } page;
206 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
207         __u32 page_offset;
208         __u32 size;
209 #else
210         __u16 page_offset;
211         __u16 size;
212 #endif
213 };
214 
215 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
216 {
217         return frag->size;
218 }
219 
220 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
221 {
222         frag->size = size;
223 }
224 
225 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
226 {
227         frag->size += delta;
228 }
229 
230 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
231 {
232         frag->size -= delta;
233 }
234 
235 #define HAVE_HW_TIME_STAMP
236 
237 /**
238  * struct skb_shared_hwtstamps - hardware time stamps
239  * @hwtstamp:   hardware time stamp transformed into duration
240  *              since arbitrary point in time
241  *
242  * Software time stamps generated by ktime_get_real() are stored in
243  * skb->tstamp.
244  *
245  * hwtstamps can only be compared against other hwtstamps from
246  * the same device.
247  *
248  * This structure is attached to packets as part of the
249  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
250  */
251 struct skb_shared_hwtstamps {
252         ktime_t hwtstamp;
253 };
254 
255 /* Definitions for tx_flags in struct skb_shared_info */
256 enum {
257         /* generate hardware time stamp */
258         SKBTX_HW_TSTAMP = 1 << 0,
259 
260         /* generate software time stamp when queueing packet to NIC */
261         SKBTX_SW_TSTAMP = 1 << 1,
262 
263         /* device driver is going to provide hardware time stamp */
264         SKBTX_IN_PROGRESS = 1 << 2,
265 
266         /* device driver supports TX zero-copy buffers */
267         SKBTX_DEV_ZEROCOPY = 1 << 3,
268 
269         /* generate wifi status information (where possible) */
270         SKBTX_WIFI_STATUS = 1 << 4,
271 
272         /* This indicates at least one fragment might be overwritten
273          * (as in vmsplice(), sendfile() ...)
274          * If we need to compute a TX checksum, we'll need to copy
275          * all frags to avoid possible bad checksum
276          */
277         SKBTX_SHARED_FRAG = 1 << 5,
278 
279         /* generate software time stamp when entering packet scheduling */
280         SKBTX_SCHED_TSTAMP = 1 << 6,
281 
282         /* generate software timestamp on peer data acknowledgment */
283         SKBTX_ACK_TSTAMP = 1 << 7,
284 };
285 
286 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
287                                  SKBTX_SCHED_TSTAMP | \
288                                  SKBTX_ACK_TSTAMP)
289 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
290 
291 /*
292  * The callback notifies userspace to release buffers when skb DMA is done in
293  * lower device, the skb last reference should be 0 when calling this.
294  * The zerocopy_success argument is true if zero copy transmit occurred,
295  * false on data copy or out of memory error caused by data copy attempt.
296  * The ctx field is used to track device context.
297  * The desc field is used to track userspace buffer index.
298  */
299 struct ubuf_info {
300         void (*callback)(struct ubuf_info *, bool zerocopy_success);
301         void *ctx;
302         unsigned long desc;
303 };
304 
305 /* This data is invariant across clones and lives at
306  * the end of the header data, ie. at skb->end.
307  */
308 struct skb_shared_info {
309         unsigned char   nr_frags;
310         __u8            tx_flags;
311         unsigned short  gso_size;
312         /* Warning: this field is not always filled in (UFO)! */
313         unsigned short  gso_segs;
314         unsigned short  gso_type;
315         struct sk_buff  *frag_list;
316         struct skb_shared_hwtstamps hwtstamps;
317         u32             tskey;
318         __be32          ip6_frag_id;
319 
320         /*
321          * Warning : all fields before dataref are cleared in __alloc_skb()
322          */
323         atomic_t        dataref;
324 
325         /* Intermediate layers must ensure that destructor_arg
326          * remains valid until skb destructor */
327         void *          destructor_arg;
328 
329         /* must be last field, see pskb_expand_head() */
330         skb_frag_t      frags[MAX_SKB_FRAGS];
331 };
332 
333 /* We divide dataref into two halves.  The higher 16 bits hold references
334  * to the payload part of skb->data.  The lower 16 bits hold references to
335  * the entire skb->data.  A clone of a headerless skb holds the length of
336  * the header in skb->hdr_len.
337  *
338  * All users must obey the rule that the skb->data reference count must be
339  * greater than or equal to the payload reference count.
340  *
341  * Holding a reference to the payload part means that the user does not
342  * care about modifications to the header part of skb->data.
343  */
344 #define SKB_DATAREF_SHIFT 16
345 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
346 
347 
348 enum {
349         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
350         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
351         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
352 };
353 
354 enum {
355         SKB_GSO_TCPV4 = 1 << 0,
356         SKB_GSO_UDP = 1 << 1,
357 
358         /* This indicates the skb is from an untrusted source. */
359         SKB_GSO_DODGY = 1 << 2,
360 
361         /* This indicates the tcp segment has CWR set. */
362         SKB_GSO_TCP_ECN = 1 << 3,
363 
364         SKB_GSO_TCPV6 = 1 << 4,
365 
366         SKB_GSO_FCOE = 1 << 5,
367 
368         SKB_GSO_GRE = 1 << 6,
369 
370         SKB_GSO_GRE_CSUM = 1 << 7,
371 
372         SKB_GSO_IPIP = 1 << 8,
373 
374         SKB_GSO_SIT = 1 << 9,
375 
376         SKB_GSO_UDP_TUNNEL = 1 << 10,
377 
378         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
379 
380         SKB_GSO_TUNNEL_REMCSUM = 1 << 12,
381 };
382 
383 #if BITS_PER_LONG > 32
384 #define NET_SKBUFF_DATA_USES_OFFSET 1
385 #endif
386 
387 #ifdef NET_SKBUFF_DATA_USES_OFFSET
388 typedef unsigned int sk_buff_data_t;
389 #else
390 typedef unsigned char *sk_buff_data_t;
391 #endif
392 
393 /**
394  * struct skb_mstamp - multi resolution time stamps
395  * @stamp_us: timestamp in us resolution
396  * @stamp_jiffies: timestamp in jiffies
397  */
398 struct skb_mstamp {
399         union {
400                 u64             v64;
401                 struct {
402                         u32     stamp_us;
403                         u32     stamp_jiffies;
404                 };
405         };
406 };
407 
408 /**
409  * skb_mstamp_get - get current timestamp
410  * @cl: place to store timestamps
411  */
412 static inline void skb_mstamp_get(struct skb_mstamp *cl)
413 {
414         u64 val = local_clock();
415 
416         do_div(val, NSEC_PER_USEC);
417         cl->stamp_us = (u32)val;
418         cl->stamp_jiffies = (u32)jiffies;
419 }
420 
421 /**
422  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
423  * @t1: pointer to newest sample
424  * @t0: pointer to oldest sample
425  */
426 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
427                                       const struct skb_mstamp *t0)
428 {
429         s32 delta_us = t1->stamp_us - t0->stamp_us;
430         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
431 
432         /* If delta_us is negative, this might be because interval is too big,
433          * or local_clock() drift is too big : fallback using jiffies.
434          */
435         if (delta_us <= 0 ||
436             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
437 
438                 delta_us = jiffies_to_usecs(delta_jiffies);
439 
440         return delta_us;
441 }
442 
443 
444 /** 
445  *      struct sk_buff - socket buffer
446  *      @next: Next buffer in list
447  *      @prev: Previous buffer in list
448  *      @tstamp: Time we arrived/left
449  *      @rbnode: RB tree node, alternative to next/prev for netem/tcp
450  *      @sk: Socket we are owned by
451  *      @dev: Device we arrived on/are leaving by
452  *      @cb: Control buffer. Free for use by every layer. Put private vars here
453  *      @_skb_refdst: destination entry (with norefcount bit)
454  *      @sp: the security path, used for xfrm
455  *      @len: Length of actual data
456  *      @data_len: Data length
457  *      @mac_len: Length of link layer header
458  *      @hdr_len: writable header length of cloned skb
459  *      @csum: Checksum (must include start/offset pair)
460  *      @csum_start: Offset from skb->head where checksumming should start
461  *      @csum_offset: Offset from csum_start where checksum should be stored
462  *      @priority: Packet queueing priority
463  *      @ignore_df: allow local fragmentation
464  *      @cloned: Head may be cloned (check refcnt to be sure)
465  *      @ip_summed: Driver fed us an IP checksum
466  *      @nohdr: Payload reference only, must not modify header
467  *      @nfctinfo: Relationship of this skb to the connection
468  *      @pkt_type: Packet class
469  *      @fclone: skbuff clone status
470  *      @ipvs_property: skbuff is owned by ipvs
471  *      @peeked: this packet has been seen already, so stats have been
472  *              done for it, don't do them again
473  *      @nf_trace: netfilter packet trace flag
474  *      @protocol: Packet protocol from driver
475  *      @destructor: Destruct function
476  *      @nfct: Associated connection, if any
477  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
478  *      @skb_iif: ifindex of device we arrived on
479  *      @tc_index: Traffic control index
480  *      @tc_verd: traffic control verdict
481  *      @hash: the packet hash
482  *      @queue_mapping: Queue mapping for multiqueue devices
483  *      @xmit_more: More SKBs are pending for this queue
484  *      @ndisc_nodetype: router type (from link layer)
485  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
486  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
487  *              ports.
488  *      @sw_hash: indicates hash was computed in software stack
489  *      @wifi_acked_valid: wifi_acked was set
490  *      @wifi_acked: whether frame was acked on wifi or not
491  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
492   *     @napi_id: id of the NAPI struct this skb came from
493  *      @secmark: security marking
494  *      @mark: Generic packet mark
495  *      @dropcount: total number of sk_receive_queue overflows
496  *      @vlan_proto: vlan encapsulation protocol
497  *      @vlan_tci: vlan tag control information
498  *      @inner_protocol: Protocol (encapsulation)
499  *      @inner_transport_header: Inner transport layer header (encapsulation)
500  *      @inner_network_header: Network layer header (encapsulation)
501  *      @inner_mac_header: Link layer header (encapsulation)
502  *      @transport_header: Transport layer header
503  *      @network_header: Network layer header
504  *      @mac_header: Link layer header
505  *      @tail: Tail pointer
506  *      @end: End pointer
507  *      @head: Head of buffer
508  *      @data: Data head pointer
509  *      @truesize: Buffer size
510  *      @users: User count - see {datagram,tcp}.c
511  */
512 
513 struct sk_buff {
514         union {
515                 struct {
516                         /* These two members must be first. */
517                         struct sk_buff          *next;
518                         struct sk_buff          *prev;
519 
520                         union {
521                                 ktime_t         tstamp;
522                                 struct skb_mstamp skb_mstamp;
523                         };
524                 };
525                 struct rb_node  rbnode; /* used in netem & tcp stack */
526         };
527         struct sock             *sk;
528         struct net_device       *dev;
529 
530         /*
531          * This is the control buffer. It is free to use for every
532          * layer. Please put your private variables there. If you
533          * want to keep them across layers you have to do a skb_clone()
534          * first. This is owned by whoever has the skb queued ATM.
535          */
536         char                    cb[48] __aligned(8);
537 
538         unsigned long           _skb_refdst;
539         void                    (*destructor)(struct sk_buff *skb);
540 #ifdef CONFIG_XFRM
541         struct  sec_path        *sp;
542 #endif
543 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
544         struct nf_conntrack     *nfct;
545 #endif
546 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
547         struct nf_bridge_info   *nf_bridge;
548 #endif
549         unsigned int            len,
550                                 data_len;
551         __u16                   mac_len,
552                                 hdr_len;
553 
554         /* Following fields are _not_ copied in __copy_skb_header()
555          * Note that queue_mapping is here mostly to fill a hole.
556          */
557         kmemcheck_bitfield_begin(flags1);
558         __u16                   queue_mapping;
559         __u8                    cloned:1,
560                                 nohdr:1,
561                                 fclone:2,
562                                 peeked:1,
563                                 head_frag:1,
564                                 xmit_more:1;
565         /* one bit hole */
566         kmemcheck_bitfield_end(flags1);
567 
568         /* fields enclosed in headers_start/headers_end are copied
569          * using a single memcpy() in __copy_skb_header()
570          */
571         /* private: */
572         __u32                   headers_start[0];
573         /* public: */
574 
575 /* if you move pkt_type around you also must adapt those constants */
576 #ifdef __BIG_ENDIAN_BITFIELD
577 #define PKT_TYPE_MAX    (7 << 5)
578 #else
579 #define PKT_TYPE_MAX    7
580 #endif
581 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
582 
583         __u8                    __pkt_type_offset[0];
584         __u8                    pkt_type:3;
585         __u8                    pfmemalloc:1;
586         __u8                    ignore_df:1;
587         __u8                    nfctinfo:3;
588 
589         __u8                    nf_trace:1;
590         __u8                    ip_summed:2;
591         __u8                    ooo_okay:1;
592         __u8                    l4_hash:1;
593         __u8                    sw_hash:1;
594         __u8                    wifi_acked_valid:1;
595         __u8                    wifi_acked:1;
596 
597         __u8                    no_fcs:1;
598         /* Indicates the inner headers are valid in the skbuff. */
599         __u8                    encapsulation:1;
600         __u8                    encap_hdr_csum:1;
601         __u8                    csum_valid:1;
602         __u8                    csum_complete_sw:1;
603         __u8                    csum_level:2;
604         __u8                    csum_bad:1;
605 
606 #ifdef CONFIG_IPV6_NDISC_NODETYPE
607         __u8                    ndisc_nodetype:2;
608 #endif
609         __u8                    ipvs_property:1;
610         __u8                    inner_protocol_type:1;
611         __u8                    remcsum_offload:1;
612         /* 3 or 5 bit hole */
613 
614 #ifdef CONFIG_NET_SCHED
615         __u16                   tc_index;       /* traffic control index */
616 #ifdef CONFIG_NET_CLS_ACT
617         __u16                   tc_verd;        /* traffic control verdict */
618 #endif
619 #endif
620 
621         union {
622                 __wsum          csum;
623                 struct {
624                         __u16   csum_start;
625                         __u16   csum_offset;
626                 };
627         };
628         __u32                   priority;
629         int                     skb_iif;
630         __u32                   hash;
631         __be16                  vlan_proto;
632         __u16                   vlan_tci;
633 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
634         union {
635                 unsigned int    napi_id;
636                 unsigned int    sender_cpu;
637         };
638 #endif
639 #ifdef CONFIG_NETWORK_SECMARK
640         __u32                   secmark;
641 #endif
642         union {
643                 __u32           mark;
644                 __u32           dropcount;
645                 __u32           reserved_tailroom;
646         };
647 
648         union {
649                 __be16          inner_protocol;
650                 __u8            inner_ipproto;
651         };
652 
653         __u16                   inner_transport_header;
654         __u16                   inner_network_header;
655         __u16                   inner_mac_header;
656 
657         __be16                  protocol;
658         __u16                   transport_header;
659         __u16                   network_header;
660         __u16                   mac_header;
661 
662         /* private: */
663         __u32                   headers_end[0];
664         /* public: */
665 
666         /* These elements must be at the end, see alloc_skb() for details.  */
667         sk_buff_data_t          tail;
668         sk_buff_data_t          end;
669         unsigned char           *head,
670                                 *data;
671         unsigned int            truesize;
672         atomic_t                users;
673 };
674 
675 #ifdef __KERNEL__
676 /*
677  *      Handling routines are only of interest to the kernel
678  */
679 #include <linux/slab.h>
680 
681 
682 #define SKB_ALLOC_FCLONE        0x01
683 #define SKB_ALLOC_RX            0x02
684 #define SKB_ALLOC_NAPI          0x04
685 
686 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
687 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
688 {
689         return unlikely(skb->pfmemalloc);
690 }
691 
692 /*
693  * skb might have a dst pointer attached, refcounted or not.
694  * _skb_refdst low order bit is set if refcount was _not_ taken
695  */
696 #define SKB_DST_NOREF   1UL
697 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
698 
699 /**
700  * skb_dst - returns skb dst_entry
701  * @skb: buffer
702  *
703  * Returns skb dst_entry, regardless of reference taken or not.
704  */
705 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
706 {
707         /* If refdst was not refcounted, check we still are in a 
708          * rcu_read_lock section
709          */
710         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
711                 !rcu_read_lock_held() &&
712                 !rcu_read_lock_bh_held());
713         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
714 }
715 
716 /**
717  * skb_dst_set - sets skb dst
718  * @skb: buffer
719  * @dst: dst entry
720  *
721  * Sets skb dst, assuming a reference was taken on dst and should
722  * be released by skb_dst_drop()
723  */
724 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
725 {
726         skb->_skb_refdst = (unsigned long)dst;
727 }
728 
729 /**
730  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
731  * @skb: buffer
732  * @dst: dst entry
733  *
734  * Sets skb dst, assuming a reference was not taken on dst.
735  * If dst entry is cached, we do not take reference and dst_release
736  * will be avoided by refdst_drop. If dst entry is not cached, we take
737  * reference, so that last dst_release can destroy the dst immediately.
738  */
739 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
740 {
741         WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
742         skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
743 }
744 
745 /**
746  * skb_dst_is_noref - Test if skb dst isn't refcounted
747  * @skb: buffer
748  */
749 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
750 {
751         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
752 }
753 
754 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
755 {
756         return (struct rtable *)skb_dst(skb);
757 }
758 
759 void kfree_skb(struct sk_buff *skb);
760 void kfree_skb_list(struct sk_buff *segs);
761 void skb_tx_error(struct sk_buff *skb);
762 void consume_skb(struct sk_buff *skb);
763 void  __kfree_skb(struct sk_buff *skb);
764 extern struct kmem_cache *skbuff_head_cache;
765 
766 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
767 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
768                       bool *fragstolen, int *delta_truesize);
769 
770 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
771                             int node);
772 struct sk_buff *build_skb(void *data, unsigned int frag_size);
773 static inline struct sk_buff *alloc_skb(unsigned int size,
774                                         gfp_t priority)
775 {
776         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
777 }
778 
779 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
780                                      unsigned long data_len,
781                                      int max_page_order,
782                                      int *errcode,
783                                      gfp_t gfp_mask);
784 
785 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
786 struct sk_buff_fclones {
787         struct sk_buff  skb1;
788 
789         struct sk_buff  skb2;
790 
791         atomic_t        fclone_ref;
792 };
793 
794 /**
795  *      skb_fclone_busy - check if fclone is busy
796  *      @skb: buffer
797  *
798  * Returns true is skb is a fast clone, and its clone is not freed.
799  * Some drivers call skb_orphan() in their ndo_start_xmit(),
800  * so we also check that this didnt happen.
801  */
802 static inline bool skb_fclone_busy(const struct sock *sk,
803                                    const struct sk_buff *skb)
804 {
805         const struct sk_buff_fclones *fclones;
806 
807         fclones = container_of(skb, struct sk_buff_fclones, skb1);
808 
809         return skb->fclone == SKB_FCLONE_ORIG &&
810                atomic_read(&fclones->fclone_ref) > 1 &&
811                fclones->skb2.sk == sk;
812 }
813 
814 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
815                                                gfp_t priority)
816 {
817         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
818 }
819 
820 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
821 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
822 {
823         return __alloc_skb_head(priority, -1);
824 }
825 
826 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
827 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
828 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
829 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
830 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
831                                    gfp_t gfp_mask, bool fclone);
832 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
833                                           gfp_t gfp_mask)
834 {
835         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
836 }
837 
838 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
839 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
840                                      unsigned int headroom);
841 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
842                                 int newtailroom, gfp_t priority);
843 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
844                         int offset, int len);
845 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
846                  int len);
847 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
848 int skb_pad(struct sk_buff *skb, int pad);
849 #define dev_kfree_skb(a)        consume_skb(a)
850 
851 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
852                             int getfrag(void *from, char *to, int offset,
853                                         int len, int odd, struct sk_buff *skb),
854                             void *from, int length);
855 
856 struct skb_seq_state {
857         __u32           lower_offset;
858         __u32           upper_offset;
859         __u32           frag_idx;
860         __u32           stepped_offset;
861         struct sk_buff  *root_skb;
862         struct sk_buff  *cur_skb;
863         __u8            *frag_data;
864 };
865 
866 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
867                           unsigned int to, struct skb_seq_state *st);
868 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
869                           struct skb_seq_state *st);
870 void skb_abort_seq_read(struct skb_seq_state *st);
871 
872 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
873                            unsigned int to, struct ts_config *config,
874                            struct ts_state *state);
875 
876 /*
877  * Packet hash types specify the type of hash in skb_set_hash.
878  *
879  * Hash types refer to the protocol layer addresses which are used to
880  * construct a packet's hash. The hashes are used to differentiate or identify
881  * flows of the protocol layer for the hash type. Hash types are either
882  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
883  *
884  * Properties of hashes:
885  *
886  * 1) Two packets in different flows have different hash values
887  * 2) Two packets in the same flow should have the same hash value
888  *
889  * A hash at a higher layer is considered to be more specific. A driver should
890  * set the most specific hash possible.
891  *
892  * A driver cannot indicate a more specific hash than the layer at which a hash
893  * was computed. For instance an L3 hash cannot be set as an L4 hash.
894  *
895  * A driver may indicate a hash level which is less specific than the
896  * actual layer the hash was computed on. For instance, a hash computed
897  * at L4 may be considered an L3 hash. This should only be done if the
898  * driver can't unambiguously determine that the HW computed the hash at
899  * the higher layer. Note that the "should" in the second property above
900  * permits this.
901  */
902 enum pkt_hash_types {
903         PKT_HASH_TYPE_NONE,     /* Undefined type */
904         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
905         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
906         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
907 };
908 
909 static inline void
910 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
911 {
912         skb->l4_hash = (type == PKT_HASH_TYPE_L4);
913         skb->sw_hash = 0;
914         skb->hash = hash;
915 }
916 
917 void __skb_get_hash(struct sk_buff *skb);
918 static inline __u32 skb_get_hash(struct sk_buff *skb)
919 {
920         if (!skb->l4_hash && !skb->sw_hash)
921                 __skb_get_hash(skb);
922 
923         return skb->hash;
924 }
925 
926 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
927 {
928         return skb->hash;
929 }
930 
931 static inline void skb_clear_hash(struct sk_buff *skb)
932 {
933         skb->hash = 0;
934         skb->sw_hash = 0;
935         skb->l4_hash = 0;
936 }
937 
938 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
939 {
940         if (!skb->l4_hash)
941                 skb_clear_hash(skb);
942 }
943 
944 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
945 {
946         to->hash = from->hash;
947         to->sw_hash = from->sw_hash;
948         to->l4_hash = from->l4_hash;
949 };
950 
951 static inline void skb_sender_cpu_clear(struct sk_buff *skb)
952 {
953 #ifdef CONFIG_XPS
954         skb->sender_cpu = 0;
955 #endif
956 }
957 
958 #ifdef NET_SKBUFF_DATA_USES_OFFSET
959 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
960 {
961         return skb->head + skb->end;
962 }
963 
964 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
965 {
966         return skb->end;
967 }
968 #else
969 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
970 {
971         return skb->end;
972 }
973 
974 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
975 {
976         return skb->end - skb->head;
977 }
978 #endif
979 
980 /* Internal */
981 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
982 
983 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
984 {
985         return &skb_shinfo(skb)->hwtstamps;
986 }
987 
988 /**
989  *      skb_queue_empty - check if a queue is empty
990  *      @list: queue head
991  *
992  *      Returns true if the queue is empty, false otherwise.
993  */
994 static inline int skb_queue_empty(const struct sk_buff_head *list)
995 {
996         return list->next == (const struct sk_buff *) list;
997 }
998 
999 /**
1000  *      skb_queue_is_last - check if skb is the last entry in the queue
1001  *      @list: queue head
1002  *      @skb: buffer
1003  *
1004  *      Returns true if @skb is the last buffer on the list.
1005  */
1006 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1007                                      const struct sk_buff *skb)
1008 {
1009         return skb->next == (const struct sk_buff *) list;
1010 }
1011 
1012 /**
1013  *      skb_queue_is_first - check if skb is the first entry in the queue
1014  *      @list: queue head
1015  *      @skb: buffer
1016  *
1017  *      Returns true if @skb is the first buffer on the list.
1018  */
1019 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1020                                       const struct sk_buff *skb)
1021 {
1022         return skb->prev == (const struct sk_buff *) list;
1023 }
1024 
1025 /**
1026  *      skb_queue_next - return the next packet in the queue
1027  *      @list: queue head
1028  *      @skb: current buffer
1029  *
1030  *      Return the next packet in @list after @skb.  It is only valid to
1031  *      call this if skb_queue_is_last() evaluates to false.
1032  */
1033 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1034                                              const struct sk_buff *skb)
1035 {
1036         /* This BUG_ON may seem severe, but if we just return then we
1037          * are going to dereference garbage.
1038          */
1039         BUG_ON(skb_queue_is_last(list, skb));
1040         return skb->next;
1041 }
1042 
1043 /**
1044  *      skb_queue_prev - return the prev packet in the queue
1045  *      @list: queue head
1046  *      @skb: current buffer
1047  *
1048  *      Return the prev packet in @list before @skb.  It is only valid to
1049  *      call this if skb_queue_is_first() evaluates to false.
1050  */
1051 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1052                                              const struct sk_buff *skb)
1053 {
1054         /* This BUG_ON may seem severe, but if we just return then we
1055          * are going to dereference garbage.
1056          */
1057         BUG_ON(skb_queue_is_first(list, skb));
1058         return skb->prev;
1059 }
1060 
1061 /**
1062  *      skb_get - reference buffer
1063  *      @skb: buffer to reference
1064  *
1065  *      Makes another reference to a socket buffer and returns a pointer
1066  *      to the buffer.
1067  */
1068 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1069 {
1070         atomic_inc(&skb->users);
1071         return skb;
1072 }
1073 
1074 /*
1075  * If users == 1, we are the only owner and are can avoid redundant
1076  * atomic change.
1077  */
1078 
1079 /**
1080  *      skb_cloned - is the buffer a clone
1081  *      @skb: buffer to check
1082  *
1083  *      Returns true if the buffer was generated with skb_clone() and is
1084  *      one of multiple shared copies of the buffer. Cloned buffers are
1085  *      shared data so must not be written to under normal circumstances.
1086  */
1087 static inline int skb_cloned(const struct sk_buff *skb)
1088 {
1089         return skb->cloned &&
1090                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1091 }
1092 
1093 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1094 {
1095         might_sleep_if(pri & __GFP_WAIT);
1096 
1097         if (skb_cloned(skb))
1098                 return pskb_expand_head(skb, 0, 0, pri);
1099 
1100         return 0;
1101 }
1102 
1103 /**
1104  *      skb_header_cloned - is the header a clone
1105  *      @skb: buffer to check
1106  *
1107  *      Returns true if modifying the header part of the buffer requires
1108  *      the data to be copied.
1109  */
1110 static inline int skb_header_cloned(const struct sk_buff *skb)
1111 {
1112         int dataref;
1113 
1114         if (!skb->cloned)
1115                 return 0;
1116 
1117         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1118         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1119         return dataref != 1;
1120 }
1121 
1122 /**
1123  *      skb_header_release - release reference to header
1124  *      @skb: buffer to operate on
1125  *
1126  *      Drop a reference to the header part of the buffer.  This is done
1127  *      by acquiring a payload reference.  You must not read from the header
1128  *      part of skb->data after this.
1129  *      Note : Check if you can use __skb_header_release() instead.
1130  */
1131 static inline void skb_header_release(struct sk_buff *skb)
1132 {
1133         BUG_ON(skb->nohdr);
1134         skb->nohdr = 1;
1135         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1136 }
1137 
1138 /**
1139  *      __skb_header_release - release reference to header
1140  *      @skb: buffer to operate on
1141  *
1142  *      Variant of skb_header_release() assuming skb is private to caller.
1143  *      We can avoid one atomic operation.
1144  */
1145 static inline void __skb_header_release(struct sk_buff *skb)
1146 {
1147         skb->nohdr = 1;
1148         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1149 }
1150 
1151 
1152 /**
1153  *      skb_shared - is the buffer shared
1154  *      @skb: buffer to check
1155  *
1156  *      Returns true if more than one person has a reference to this
1157  *      buffer.
1158  */
1159 static inline int skb_shared(const struct sk_buff *skb)
1160 {
1161         return atomic_read(&skb->users) != 1;
1162 }
1163 
1164 /**
1165  *      skb_share_check - check if buffer is shared and if so clone it
1166  *      @skb: buffer to check
1167  *      @pri: priority for memory allocation
1168  *
1169  *      If the buffer is shared the buffer is cloned and the old copy
1170  *      drops a reference. A new clone with a single reference is returned.
1171  *      If the buffer is not shared the original buffer is returned. When
1172  *      being called from interrupt status or with spinlocks held pri must
1173  *      be GFP_ATOMIC.
1174  *
1175  *      NULL is returned on a memory allocation failure.
1176  */
1177 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1178 {
1179         might_sleep_if(pri & __GFP_WAIT);
1180         if (skb_shared(skb)) {
1181                 struct sk_buff *nskb = skb_clone(skb, pri);
1182 
1183                 if (likely(nskb))
1184                         consume_skb(skb);
1185                 else
1186                         kfree_skb(skb);
1187                 skb = nskb;
1188         }
1189         return skb;
1190 }
1191 
1192 /*
1193  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1194  *      packets to handle cases where we have a local reader and forward
1195  *      and a couple of other messy ones. The normal one is tcpdumping
1196  *      a packet thats being forwarded.
1197  */
1198 
1199 /**
1200  *      skb_unshare - make a copy of a shared buffer
1201  *      @skb: buffer to check
1202  *      @pri: priority for memory allocation
1203  *
1204  *      If the socket buffer is a clone then this function creates a new
1205  *      copy of the data, drops a reference count on the old copy and returns
1206  *      the new copy with the reference count at 1. If the buffer is not a clone
1207  *      the original buffer is returned. When called with a spinlock held or
1208  *      from interrupt state @pri must be %GFP_ATOMIC
1209  *
1210  *      %NULL is returned on a memory allocation failure.
1211  */
1212 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1213                                           gfp_t pri)
1214 {
1215         might_sleep_if(pri & __GFP_WAIT);
1216         if (skb_cloned(skb)) {
1217                 struct sk_buff *nskb = skb_copy(skb, pri);
1218 
1219                 /* Free our shared copy */
1220                 if (likely(nskb))
1221                         consume_skb(skb);
1222                 else
1223                         kfree_skb(skb);
1224                 skb = nskb;
1225         }
1226         return skb;
1227 }
1228 
1229 /**
1230  *      skb_peek - peek at the head of an &sk_buff_head
1231  *      @list_: list to peek at
1232  *
1233  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1234  *      be careful with this one. A peek leaves the buffer on the
1235  *      list and someone else may run off with it. You must hold
1236  *      the appropriate locks or have a private queue to do this.
1237  *
1238  *      Returns %NULL for an empty list or a pointer to the head element.
1239  *      The reference count is not incremented and the reference is therefore
1240  *      volatile. Use with caution.
1241  */
1242 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1243 {
1244         struct sk_buff *skb = list_->next;
1245 
1246         if (skb == (struct sk_buff *)list_)
1247                 skb = NULL;
1248         return skb;
1249 }
1250 
1251 /**
1252  *      skb_peek_next - peek skb following the given one from a queue
1253  *      @skb: skb to start from
1254  *      @list_: list to peek at
1255  *
1256  *      Returns %NULL when the end of the list is met or a pointer to the
1257  *      next element. The reference count is not incremented and the
1258  *      reference is therefore volatile. Use with caution.
1259  */
1260 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1261                 const struct sk_buff_head *list_)
1262 {
1263         struct sk_buff *next = skb->next;
1264 
1265         if (next == (struct sk_buff *)list_)
1266                 next = NULL;
1267         return next;
1268 }
1269 
1270 /**
1271  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1272  *      @list_: list to peek at
1273  *
1274  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1275  *      be careful with this one. A peek leaves the buffer on the
1276  *      list and someone else may run off with it. You must hold
1277  *      the appropriate locks or have a private queue to do this.
1278  *
1279  *      Returns %NULL for an empty list or a pointer to the tail element.
1280  *      The reference count is not incremented and the reference is therefore
1281  *      volatile. Use with caution.
1282  */
1283 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1284 {
1285         struct sk_buff *skb = list_->prev;
1286 
1287         if (skb == (struct sk_buff *)list_)
1288                 skb = NULL;
1289         return skb;
1290 
1291 }
1292 
1293 /**
1294  *      skb_queue_len   - get queue length
1295  *      @list_: list to measure
1296  *
1297  *      Return the length of an &sk_buff queue.
1298  */
1299 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1300 {
1301         return list_->qlen;
1302 }
1303 
1304 /**
1305  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1306  *      @list: queue to initialize
1307  *
1308  *      This initializes only the list and queue length aspects of
1309  *      an sk_buff_head object.  This allows to initialize the list
1310  *      aspects of an sk_buff_head without reinitializing things like
1311  *      the spinlock.  It can also be used for on-stack sk_buff_head
1312  *      objects where the spinlock is known to not be used.
1313  */
1314 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1315 {
1316         list->prev = list->next = (struct sk_buff *)list;
1317         list->qlen = 0;
1318 }
1319 
1320 /*
1321  * This function creates a split out lock class for each invocation;
1322  * this is needed for now since a whole lot of users of the skb-queue
1323  * infrastructure in drivers have different locking usage (in hardirq)
1324  * than the networking core (in softirq only). In the long run either the
1325  * network layer or drivers should need annotation to consolidate the
1326  * main types of usage into 3 classes.
1327  */
1328 static inline void skb_queue_head_init(struct sk_buff_head *list)
1329 {
1330         spin_lock_init(&list->lock);
1331         __skb_queue_head_init(list);
1332 }
1333 
1334 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1335                 struct lock_class_key *class)
1336 {
1337         skb_queue_head_init(list);
1338         lockdep_set_class(&list->lock, class);
1339 }
1340 
1341 /*
1342  *      Insert an sk_buff on a list.
1343  *
1344  *      The "__skb_xxxx()" functions are the non-atomic ones that
1345  *      can only be called with interrupts disabled.
1346  */
1347 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1348                 struct sk_buff_head *list);
1349 static inline void __skb_insert(struct sk_buff *newsk,
1350                                 struct sk_buff *prev, struct sk_buff *next,
1351                                 struct sk_buff_head *list)
1352 {
1353         newsk->next = next;
1354         newsk->prev = prev;
1355         next->prev  = prev->next = newsk;
1356         list->qlen++;
1357 }
1358 
1359 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1360                                       struct sk_buff *prev,
1361                                       struct sk_buff *next)
1362 {
1363         struct sk_buff *first = list->next;
1364         struct sk_buff *last = list->prev;
1365 
1366         first->prev = prev;
1367         prev->next = first;
1368 
1369         last->next = next;
1370         next->prev = last;
1371 }
1372 
1373 /**
1374  *      skb_queue_splice - join two skb lists, this is designed for stacks
1375  *      @list: the new list to add
1376  *      @head: the place to add it in the first list
1377  */
1378 static inline void skb_queue_splice(const struct sk_buff_head *list,
1379                                     struct sk_buff_head *head)
1380 {
1381         if (!skb_queue_empty(list)) {
1382                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1383                 head->qlen += list->qlen;
1384         }
1385 }
1386 
1387 /**
1388  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1389  *      @list: the new list to add
1390  *      @head: the place to add it in the first list
1391  *
1392  *      The list at @list is reinitialised
1393  */
1394 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1395                                          struct sk_buff_head *head)
1396 {
1397         if (!skb_queue_empty(list)) {
1398                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1399                 head->qlen += list->qlen;
1400                 __skb_queue_head_init(list);
1401         }
1402 }
1403 
1404 /**
1405  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1406  *      @list: the new list to add
1407  *      @head: the place to add it in the first list
1408  */
1409 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1410                                          struct sk_buff_head *head)
1411 {
1412         if (!skb_queue_empty(list)) {
1413                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1414                 head->qlen += list->qlen;
1415         }
1416 }
1417 
1418 /**
1419  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1420  *      @list: the new list to add
1421  *      @head: the place to add it in the first list
1422  *
1423  *      Each of the lists is a queue.
1424  *      The list at @list is reinitialised
1425  */
1426 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1427                                               struct sk_buff_head *head)
1428 {
1429         if (!skb_queue_empty(list)) {
1430                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1431                 head->qlen += list->qlen;
1432                 __skb_queue_head_init(list);
1433         }
1434 }
1435 
1436 /**
1437  *      __skb_queue_after - queue a buffer at the list head
1438  *      @list: list to use
1439  *      @prev: place after this buffer
1440  *      @newsk: buffer to queue
1441  *
1442  *      Queue a buffer int the middle of a list. This function takes no locks
1443  *      and you must therefore hold required locks before calling it.
1444  *
1445  *      A buffer cannot be placed on two lists at the same time.
1446  */
1447 static inline void __skb_queue_after(struct sk_buff_head *list,
1448                                      struct sk_buff *prev,
1449                                      struct sk_buff *newsk)
1450 {
1451         __skb_insert(newsk, prev, prev->next, list);
1452 }
1453 
1454 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1455                 struct sk_buff_head *list);
1456 
1457 static inline void __skb_queue_before(struct sk_buff_head *list,
1458                                       struct sk_buff *next,
1459                                       struct sk_buff *newsk)
1460 {
1461         __skb_insert(newsk, next->prev, next, list);
1462 }
1463 
1464 /**
1465  *      __skb_queue_head - queue a buffer at the list head
1466  *      @list: list to use
1467  *      @newsk: buffer to queue
1468  *
1469  *      Queue a buffer at the start of a list. This function takes no locks
1470  *      and you must therefore hold required locks before calling it.
1471  *
1472  *      A buffer cannot be placed on two lists at the same time.
1473  */
1474 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1475 static inline void __skb_queue_head(struct sk_buff_head *list,
1476                                     struct sk_buff *newsk)
1477 {
1478         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1479 }
1480 
1481 /**
1482  *      __skb_queue_tail - queue a buffer at the list tail
1483  *      @list: list to use
1484  *      @newsk: buffer to queue
1485  *
1486  *      Queue a buffer at the end of a list. This function takes no locks
1487  *      and you must therefore hold required locks before calling it.
1488  *
1489  *      A buffer cannot be placed on two lists at the same time.
1490  */
1491 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1492 static inline void __skb_queue_tail(struct sk_buff_head *list,
1493                                    struct sk_buff *newsk)
1494 {
1495         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1496 }
1497 
1498 /*
1499  * remove sk_buff from list. _Must_ be called atomically, and with
1500  * the list known..
1501  */
1502 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1503 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1504 {
1505         struct sk_buff *next, *prev;
1506 
1507         list->qlen--;
1508         next       = skb->next;
1509         prev       = skb->prev;
1510         skb->next  = skb->prev = NULL;
1511         next->prev = prev;
1512         prev->next = next;
1513 }
1514 
1515 /**
1516  *      __skb_dequeue - remove from the head of the queue
1517  *      @list: list to dequeue from
1518  *
1519  *      Remove the head of the list. This function does not take any locks
1520  *      so must be used with appropriate locks held only. The head item is
1521  *      returned or %NULL if the list is empty.
1522  */
1523 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1524 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1525 {
1526         struct sk_buff *skb = skb_peek(list);
1527         if (skb)
1528                 __skb_unlink(skb, list);
1529         return skb;
1530 }
1531 
1532 /**
1533  *      __skb_dequeue_tail - remove from the tail of the queue
1534  *      @list: list to dequeue from
1535  *
1536  *      Remove the tail of the list. This function does not take any locks
1537  *      so must be used with appropriate locks held only. The tail item is
1538  *      returned or %NULL if the list is empty.
1539  */
1540 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1541 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1542 {
1543         struct sk_buff *skb = skb_peek_tail(list);
1544         if (skb)
1545                 __skb_unlink(skb, list);
1546         return skb;
1547 }
1548 
1549 
1550 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1551 {
1552         return skb->data_len;
1553 }
1554 
1555 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1556 {
1557         return skb->len - skb->data_len;
1558 }
1559 
1560 static inline int skb_pagelen(const struct sk_buff *skb)
1561 {
1562         int i, len = 0;
1563 
1564         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1565                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1566         return len + skb_headlen(skb);
1567 }
1568 
1569 /**
1570  * __skb_fill_page_desc - initialise a paged fragment in an skb
1571  * @skb: buffer containing fragment to be initialised
1572  * @i: paged fragment index to initialise
1573  * @page: the page to use for this fragment
1574  * @off: the offset to the data with @page
1575  * @size: the length of the data
1576  *
1577  * Initialises the @i'th fragment of @skb to point to &size bytes at
1578  * offset @off within @page.
1579  *
1580  * Does not take any additional reference on the fragment.
1581  */
1582 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1583                                         struct page *page, int off, int size)
1584 {
1585         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1586 
1587         /*
1588          * Propagate page->pfmemalloc to the skb if we can. The problem is
1589          * that not all callers have unique ownership of the page. If
1590          * pfmemalloc is set, we check the mapping as a mapping implies
1591          * page->index is set (index and pfmemalloc share space).
1592          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1593          * do not lose pfmemalloc information as the pages would not be
1594          * allocated using __GFP_MEMALLOC.
1595          */
1596         frag->page.p              = page;
1597         frag->page_offset         = off;
1598         skb_frag_size_set(frag, size);
1599 
1600         page = compound_head(page);
1601         if (page->pfmemalloc && !page->mapping)
1602                 skb->pfmemalloc = true;
1603 }
1604 
1605 /**
1606  * skb_fill_page_desc - initialise a paged fragment in an skb
1607  * @skb: buffer containing fragment to be initialised
1608  * @i: paged fragment index to initialise
1609  * @page: the page to use for this fragment
1610  * @off: the offset to the data with @page
1611  * @size: the length of the data
1612  *
1613  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1614  * @skb to point to @size bytes at offset @off within @page. In
1615  * addition updates @skb such that @i is the last fragment.
1616  *
1617  * Does not take any additional reference on the fragment.
1618  */
1619 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1620                                       struct page *page, int off, int size)
1621 {
1622         __skb_fill_page_desc(skb, i, page, off, size);
1623         skb_shinfo(skb)->nr_frags = i + 1;
1624 }
1625 
1626 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1627                      int size, unsigned int truesize);
1628 
1629 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1630                           unsigned int truesize);
1631 
1632 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1633 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1634 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1635 
1636 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1637 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1638 {
1639         return skb->head + skb->tail;
1640 }
1641 
1642 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1643 {
1644         skb->tail = skb->data - skb->head;
1645 }
1646 
1647 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1648 {
1649         skb_reset_tail_pointer(skb);
1650         skb->tail += offset;
1651 }
1652 
1653 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1654 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1655 {
1656         return skb->tail;
1657 }
1658 
1659 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1660 {
1661         skb->tail = skb->data;
1662 }
1663 
1664 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1665 {
1666         skb->tail = skb->data + offset;
1667 }
1668 
1669 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1670 
1671 /*
1672  *      Add data to an sk_buff
1673  */
1674 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1675 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1676 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1677 {
1678         unsigned char *tmp = skb_tail_pointer(skb);
1679         SKB_LINEAR_ASSERT(skb);
1680         skb->tail += len;
1681         skb->len  += len;
1682         return tmp;
1683 }
1684 
1685 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1686 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1687 {
1688         skb->data -= len;
1689         skb->len  += len;
1690         return skb->data;
1691 }
1692 
1693 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1694 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1695 {
1696         skb->len -= len;
1697         BUG_ON(skb->len < skb->data_len);
1698         return skb->data += len;
1699 }
1700 
1701 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1702 {
1703         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1704 }
1705 
1706 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1707 
1708 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1709 {
1710         if (len > skb_headlen(skb) &&
1711             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1712                 return NULL;
1713         skb->len -= len;
1714         return skb->data += len;
1715 }
1716 
1717 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1718 {
1719         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1720 }
1721 
1722 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1723 {
1724         if (likely(len <= skb_headlen(skb)))
1725                 return 1;
1726         if (unlikely(len > skb->len))
1727                 return 0;
1728         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1729 }
1730 
1731 /**
1732  *      skb_headroom - bytes at buffer head
1733  *      @skb: buffer to check
1734  *
1735  *      Return the number of bytes of free space at the head of an &sk_buff.
1736  */
1737 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1738 {
1739         return skb->data - skb->head;
1740 }
1741 
1742 /**
1743  *      skb_tailroom - bytes at buffer end
1744  *      @skb: buffer to check
1745  *
1746  *      Return the number of bytes of free space at the tail of an sk_buff
1747  */
1748 static inline int skb_tailroom(const struct sk_buff *skb)
1749 {
1750         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1751 }
1752 
1753 /**
1754  *      skb_availroom - bytes at buffer end
1755  *      @skb: buffer to check
1756  *
1757  *      Return the number of bytes of free space at the tail of an sk_buff
1758  *      allocated by sk_stream_alloc()
1759  */
1760 static inline int skb_availroom(const struct sk_buff *skb)
1761 {
1762         if (skb_is_nonlinear(skb))
1763                 return 0;
1764 
1765         return skb->end - skb->tail - skb->reserved_tailroom;
1766 }
1767 
1768 /**
1769  *      skb_reserve - adjust headroom
1770  *      @skb: buffer to alter
1771  *      @len: bytes to move
1772  *
1773  *      Increase the headroom of an empty &sk_buff by reducing the tail
1774  *      room. This is only allowed for an empty buffer.
1775  */
1776 static inline void skb_reserve(struct sk_buff *skb, int len)
1777 {
1778         skb->data += len;
1779         skb->tail += len;
1780 }
1781 
1782 #define ENCAP_TYPE_ETHER        0
1783 #define ENCAP_TYPE_IPPROTO      1
1784 
1785 static inline void skb_set_inner_protocol(struct sk_buff *skb,
1786                                           __be16 protocol)
1787 {
1788         skb->inner_protocol = protocol;
1789         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
1790 }
1791 
1792 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
1793                                          __u8 ipproto)
1794 {
1795         skb->inner_ipproto = ipproto;
1796         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
1797 }
1798 
1799 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1800 {
1801         skb->inner_mac_header = skb->mac_header;
1802         skb->inner_network_header = skb->network_header;
1803         skb->inner_transport_header = skb->transport_header;
1804 }
1805 
1806 static inline void skb_reset_mac_len(struct sk_buff *skb)
1807 {
1808         skb->mac_len = skb->network_header - skb->mac_header;
1809 }
1810 
1811 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1812                                                         *skb)
1813 {
1814         return skb->head + skb->inner_transport_header;
1815 }
1816 
1817 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1818 {
1819         skb->inner_transport_header = skb->data - skb->head;
1820 }
1821 
1822 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1823                                                    const int offset)
1824 {
1825         skb_reset_inner_transport_header(skb);
1826         skb->inner_transport_header += offset;
1827 }
1828 
1829 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1830 {
1831         return skb->head + skb->inner_network_header;
1832 }
1833 
1834 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1835 {
1836         skb->inner_network_header = skb->data - skb->head;
1837 }
1838 
1839 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1840                                                 const int offset)
1841 {
1842         skb_reset_inner_network_header(skb);
1843         skb->inner_network_header += offset;
1844 }
1845 
1846 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1847 {
1848         return skb->head + skb->inner_mac_header;
1849 }
1850 
1851 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1852 {
1853         skb->inner_mac_header = skb->data - skb->head;
1854 }
1855 
1856 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1857                                             const int offset)
1858 {
1859         skb_reset_inner_mac_header(skb);
1860         skb->inner_mac_header += offset;
1861 }
1862 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1863 {
1864         return skb->transport_header != (typeof(skb->transport_header))~0U;
1865 }
1866 
1867 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1868 {
1869         return skb->head + skb->transport_header;
1870 }
1871 
1872 static inline void skb_reset_transport_header(struct sk_buff *skb)
1873 {
1874         skb->transport_header = skb->data - skb->head;
1875 }
1876 
1877 static inline void skb_set_transport_header(struct sk_buff *skb,
1878                                             const int offset)
1879 {
1880         skb_reset_transport_header(skb);
1881         skb->transport_header += offset;
1882 }
1883 
1884 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1885 {
1886         return skb->head + skb->network_header;
1887 }
1888 
1889 static inline void skb_reset_network_header(struct sk_buff *skb)
1890 {
1891         skb->network_header = skb->data - skb->head;
1892 }
1893 
1894 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1895 {
1896         skb_reset_network_header(skb);
1897         skb->network_header += offset;
1898 }
1899 
1900 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1901 {
1902         return skb->head + skb->mac_header;
1903 }
1904 
1905 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1906 {
1907         return skb->mac_header != (typeof(skb->mac_header))~0U;
1908 }
1909 
1910 static inline void skb_reset_mac_header(struct sk_buff *skb)
1911 {
1912         skb->mac_header = skb->data - skb->head;
1913 }
1914 
1915 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1916 {
1917         skb_reset_mac_header(skb);
1918         skb->mac_header += offset;
1919 }
1920 
1921 static inline void skb_pop_mac_header(struct sk_buff *skb)
1922 {
1923         skb->mac_header = skb->network_header;
1924 }
1925 
1926 static inline void skb_probe_transport_header(struct sk_buff *skb,
1927                                               const int offset_hint)
1928 {
1929         struct flow_keys keys;
1930 
1931         if (skb_transport_header_was_set(skb))
1932                 return;
1933         else if (skb_flow_dissect(skb, &keys))
1934                 skb_set_transport_header(skb, keys.thoff);
1935         else
1936                 skb_set_transport_header(skb, offset_hint);
1937 }
1938 
1939 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1940 {
1941         if (skb_mac_header_was_set(skb)) {
1942                 const unsigned char *old_mac = skb_mac_header(skb);
1943 
1944                 skb_set_mac_header(skb, -skb->mac_len);
1945                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1946         }
1947 }
1948 
1949 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1950 {
1951         return skb->csum_start - skb_headroom(skb);
1952 }
1953 
1954 static inline int skb_transport_offset(const struct sk_buff *skb)
1955 {
1956         return skb_transport_header(skb) - skb->data;
1957 }
1958 
1959 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1960 {
1961         return skb->transport_header - skb->network_header;
1962 }
1963 
1964 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1965 {
1966         return skb->inner_transport_header - skb->inner_network_header;
1967 }
1968 
1969 static inline int skb_network_offset(const struct sk_buff *skb)
1970 {
1971         return skb_network_header(skb) - skb->data;
1972 }
1973 
1974 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1975 {
1976         return skb_inner_network_header(skb) - skb->data;
1977 }
1978 
1979 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1980 {
1981         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1982 }
1983 
1984 /*
1985  * CPUs often take a performance hit when accessing unaligned memory
1986  * locations. The actual performance hit varies, it can be small if the
1987  * hardware handles it or large if we have to take an exception and fix it
1988  * in software.
1989  *
1990  * Since an ethernet header is 14 bytes network drivers often end up with
1991  * the IP header at an unaligned offset. The IP header can be aligned by
1992  * shifting the start of the packet by 2 bytes. Drivers should do this
1993  * with:
1994  *
1995  * skb_reserve(skb, NET_IP_ALIGN);
1996  *
1997  * The downside to this alignment of the IP header is that the DMA is now
1998  * unaligned. On some architectures the cost of an unaligned DMA is high
1999  * and this cost outweighs the gains made by aligning the IP header.
2000  *
2001  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2002  * to be overridden.
2003  */
2004 #ifndef NET_IP_ALIGN
2005 #define NET_IP_ALIGN    2
2006 #endif
2007 
2008 /*
2009  * The networking layer reserves some headroom in skb data (via
2010  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2011  * the header has to grow. In the default case, if the header has to grow
2012  * 32 bytes or less we avoid the reallocation.
2013  *
2014  * Unfortunately this headroom changes the DMA alignment of the resulting
2015  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2016  * on some architectures. An architecture can override this value,
2017  * perhaps setting it to a cacheline in size (since that will maintain
2018  * cacheline alignment of the DMA). It must be a power of 2.
2019  *
2020  * Various parts of the networking layer expect at least 32 bytes of
2021  * headroom, you should not reduce this.
2022  *
2023  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2024  * to reduce average number of cache lines per packet.
2025  * get_rps_cpus() for example only access one 64 bytes aligned block :
2026  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2027  */
2028 #ifndef NET_SKB_PAD
2029 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2030 #endif
2031 
2032 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2033 
2034 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2035 {
2036         if (unlikely(skb_is_nonlinear(skb))) {
2037                 WARN_ON(1);
2038                 return;
2039         }
2040         skb->len = len;
2041         skb_set_tail_pointer(skb, len);
2042 }
2043 
2044 void skb_trim(struct sk_buff *skb, unsigned int len);
2045 
2046 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2047 {
2048         if (skb->data_len)
2049                 return ___pskb_trim(skb, len);
2050         __skb_trim(skb, len);
2051         return 0;
2052 }
2053 
2054 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2055 {
2056         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2057 }
2058 
2059 /**
2060  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2061  *      @skb: buffer to alter
2062  *      @len: new length
2063  *
2064  *      This is identical to pskb_trim except that the caller knows that
2065  *      the skb is not cloned so we should never get an error due to out-
2066  *      of-memory.
2067  */
2068 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2069 {
2070         int err = pskb_trim(skb, len);
2071         BUG_ON(err);
2072 }
2073 
2074 /**
2075  *      skb_orphan - orphan a buffer
2076  *      @skb: buffer to orphan
2077  *
2078  *      If a buffer currently has an owner then we call the owner's
2079  *      destructor function and make the @skb unowned. The buffer continues
2080  *      to exist but is no longer charged to its former owner.
2081  */
2082 static inline void skb_orphan(struct sk_buff *skb)
2083 {
2084         if (skb->destructor) {
2085                 skb->destructor(skb);
2086                 skb->destructor = NULL;
2087                 skb->sk         = NULL;
2088         } else {
2089                 BUG_ON(skb->sk);
2090         }
2091 }
2092 
2093 /**
2094  *      skb_orphan_frags - orphan the frags contained in a buffer
2095  *      @skb: buffer to orphan frags from
2096  *      @gfp_mask: allocation mask for replacement pages
2097  *
2098  *      For each frag in the SKB which needs a destructor (i.e. has an
2099  *      owner) create a copy of that frag and release the original
2100  *      page by calling the destructor.
2101  */
2102 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2103 {
2104         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2105                 return 0;
2106         return skb_copy_ubufs(skb, gfp_mask);
2107 }
2108 
2109 /**
2110  *      __skb_queue_purge - empty a list
2111  *      @list: list to empty
2112  *
2113  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2114  *      the list and one reference dropped. This function does not take the
2115  *      list lock and the caller must hold the relevant locks to use it.
2116  */
2117 void skb_queue_purge(struct sk_buff_head *list);
2118 static inline void __skb_queue_purge(struct sk_buff_head *list)
2119 {
2120         struct sk_buff *skb;
2121         while ((skb = __skb_dequeue(list)) != NULL)
2122                 kfree_skb(skb);
2123 }
2124 
2125 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
2126 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
2127 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
2128 
2129 void *netdev_alloc_frag(unsigned int fragsz);
2130 
2131 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2132                                    gfp_t gfp_mask);
2133 
2134 /**
2135  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2136  *      @dev: network device to receive on
2137  *      @length: length to allocate
2138  *
2139  *      Allocate a new &sk_buff and assign it a usage count of one. The
2140  *      buffer has unspecified headroom built in. Users should allocate
2141  *      the headroom they think they need without accounting for the
2142  *      built in space. The built in space is used for optimisations.
2143  *
2144  *      %NULL is returned if there is no free memory. Although this function
2145  *      allocates memory it can be called from an interrupt.
2146  */
2147 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2148                                                unsigned int length)
2149 {
2150         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2151 }
2152 
2153 /* legacy helper around __netdev_alloc_skb() */
2154 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2155                                               gfp_t gfp_mask)
2156 {
2157         return __netdev_alloc_skb(NULL, length, gfp_mask);
2158 }
2159 
2160 /* legacy helper around netdev_alloc_skb() */
2161 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2162 {
2163         return netdev_alloc_skb(NULL, length);
2164 }
2165 
2166 
2167 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2168                 unsigned int length, gfp_t gfp)
2169 {
2170         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2171 
2172         if (NET_IP_ALIGN && skb)
2173                 skb_reserve(skb, NET_IP_ALIGN);
2174         return skb;
2175 }
2176 
2177 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2178                 unsigned int length)
2179 {
2180         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2181 }
2182 
2183 void *napi_alloc_frag(unsigned int fragsz);
2184 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2185                                  unsigned int length, gfp_t gfp_mask);
2186 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2187                                              unsigned int length)
2188 {
2189         return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2190 }
2191 
2192 /**
2193  * __dev_alloc_pages - allocate page for network Rx
2194  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2195  * @order: size of the allocation
2196  *
2197  * Allocate a new page.
2198  *
2199  * %NULL is returned if there is no free memory.
2200 */
2201 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2202                                              unsigned int order)
2203 {
2204         /* This piece of code contains several assumptions.
2205          * 1.  This is for device Rx, therefor a cold page is preferred.
2206          * 2.  The expectation is the user wants a compound page.
2207          * 3.  If requesting a order 0 page it will not be compound
2208          *     due to the check to see if order has a value in prep_new_page
2209          * 4.  __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2210          *     code in gfp_to_alloc_flags that should be enforcing this.
2211          */
2212         gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
2213 
2214         return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2215 }
2216 
2217 static inline struct page *dev_alloc_pages(unsigned int order)
2218 {
2219         return __dev_alloc_pages(GFP_ATOMIC, order);
2220 }
2221 
2222 /**
2223  * __dev_alloc_page - allocate a page for network Rx
2224  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2225  *
2226  * Allocate a new page.
2227  *
2228  * %NULL is returned if there is no free memory.
2229  */
2230 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2231 {
2232         return __dev_alloc_pages(gfp_mask, 0);
2233 }
2234 
2235 static inline struct page *dev_alloc_page(void)
2236 {
2237         return __dev_alloc_page(GFP_ATOMIC);
2238 }
2239 
2240 /**
2241  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2242  *      @page: The page that was allocated from skb_alloc_page
2243  *      @skb: The skb that may need pfmemalloc set
2244  */
2245 static inline void skb_propagate_pfmemalloc(struct page *page,
2246                                              struct sk_buff *skb)
2247 {
2248         if (page && page->pfmemalloc)
2249                 skb->pfmemalloc = true;
2250 }
2251 
2252 /**
2253  * skb_frag_page - retrieve the page referred to by a paged fragment
2254  * @frag: the paged fragment
2255  *
2256  * Returns the &struct page associated with @frag.
2257  */
2258 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2259 {
2260         return frag->page.p;
2261 }
2262 
2263 /**
2264  * __skb_frag_ref - take an addition reference on a paged fragment.
2265  * @frag: the paged fragment
2266  *
2267  * Takes an additional reference on the paged fragment @frag.
2268  */
2269 static inline void __skb_frag_ref(skb_frag_t *frag)
2270 {
2271         get_page(skb_frag_page(frag));
2272 }
2273 
2274 /**
2275  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2276  * @skb: the buffer
2277  * @f: the fragment offset.
2278  *
2279  * Takes an additional reference on the @f'th paged fragment of @skb.
2280  */
2281 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2282 {
2283         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2284 }
2285 
2286 /**
2287  * __skb_frag_unref - release a reference on a paged fragment.
2288  * @frag: the paged fragment
2289  *
2290  * Releases a reference on the paged fragment @frag.
2291  */
2292 static inline void __skb_frag_unref(skb_frag_t *frag)
2293 {
2294         put_page(skb_frag_page(frag));
2295 }
2296 
2297 /**
2298  * skb_frag_unref - release a reference on a paged fragment of an skb.
2299  * @skb: the buffer
2300  * @f: the fragment offset
2301  *
2302  * Releases a reference on the @f'th paged fragment of @skb.
2303  */
2304 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2305 {
2306         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2307 }
2308 
2309 /**
2310  * skb_frag_address - gets the address of the data contained in a paged fragment
2311  * @frag: the paged fragment buffer
2312  *
2313  * Returns the address of the data within @frag. The page must already
2314  * be mapped.
2315  */
2316 static inline void *skb_frag_address(const skb_frag_t *frag)
2317 {
2318         return page_address(skb_frag_page(frag)) + frag->page_offset;
2319 }
2320 
2321 /**
2322  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2323  * @frag: the paged fragment buffer
2324  *
2325  * Returns the address of the data within @frag. Checks that the page
2326  * is mapped and returns %NULL otherwise.
2327  */
2328 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2329 {
2330         void *ptr = page_address(skb_frag_page(frag));
2331         if (unlikely(!ptr))
2332                 return NULL;
2333 
2334         return ptr + frag->page_offset;
2335 }
2336 
2337 /**
2338  * __skb_frag_set_page - sets the page contained in a paged fragment
2339  * @frag: the paged fragment
2340  * @page: the page to set
2341  *
2342  * Sets the fragment @frag to contain @page.
2343  */
2344 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2345 {
2346         frag->page.p = page;
2347 }
2348 
2349 /**
2350  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2351  * @skb: the buffer
2352  * @f: the fragment offset
2353  * @page: the page to set
2354  *
2355  * Sets the @f'th fragment of @skb to contain @page.
2356  */
2357 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2358                                      struct page *page)
2359 {
2360         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2361 }
2362 
2363 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2364 
2365 /**
2366  * skb_frag_dma_map - maps a paged fragment via the DMA API
2367  * @dev: the device to map the fragment to
2368  * @frag: the paged fragment to map
2369  * @offset: the offset within the fragment (starting at the
2370  *          fragment's own offset)
2371  * @size: the number of bytes to map
2372  * @dir: the direction of the mapping (%PCI_DMA_*)
2373  *
2374  * Maps the page associated with @frag to @device.
2375  */
2376 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2377                                           const skb_frag_t *frag,
2378                                           size_t offset, size_t size,
2379                                           enum dma_data_direction dir)
2380 {
2381         return dma_map_page(dev, skb_frag_page(frag),
2382                             frag->page_offset + offset, size, dir);
2383 }
2384 
2385 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2386                                         gfp_t gfp_mask)
2387 {
2388         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2389 }
2390 
2391 
2392 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2393                                                   gfp_t gfp_mask)
2394 {
2395         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2396 }
2397 
2398 
2399 /**
2400  *      skb_clone_writable - is the header of a clone writable
2401  *      @skb: buffer to check
2402  *      @len: length up to which to write
2403  *
2404  *      Returns true if modifying the header part of the cloned buffer
2405  *      does not requires the data to be copied.
2406  */
2407 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2408 {
2409         return !skb_header_cloned(skb) &&
2410                skb_headroom(skb) + len <= skb->hdr_len;
2411 }
2412 
2413 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2414                             int cloned)
2415 {
2416         int delta = 0;
2417 
2418         if (headroom > skb_headroom(skb))
2419                 delta = headroom - skb_headroom(skb);
2420 
2421         if (delta || cloned)
2422                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2423                                         GFP_ATOMIC);
2424         return 0;
2425 }
2426 
2427 /**
2428  *      skb_cow - copy header of skb when it is required
2429  *      @skb: buffer to cow
2430  *      @headroom: needed headroom
2431  *
2432  *      If the skb passed lacks sufficient headroom or its data part
2433  *      is shared, data is reallocated. If reallocation fails, an error
2434  *      is returned and original skb is not changed.
2435  *
2436  *      The result is skb with writable area skb->head...skb->tail
2437  *      and at least @headroom of space at head.
2438  */
2439 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2440 {
2441         return __skb_cow(skb, headroom, skb_cloned(skb));
2442 }
2443 
2444 /**
2445  *      skb_cow_head - skb_cow but only making the head writable
2446  *      @skb: buffer to cow
2447  *      @headroom: needed headroom
2448  *
2449  *      This function is identical to skb_cow except that we replace the
2450  *      skb_cloned check by skb_header_cloned.  It should be used when
2451  *      you only need to push on some header and do not need to modify
2452  *      the data.
2453  */
2454 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2455 {
2456         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2457 }
2458 
2459 /**
2460  *      skb_padto       - pad an skbuff up to a minimal size
2461  *      @skb: buffer to pad
2462  *      @len: minimal length
2463  *
2464  *      Pads up a buffer to ensure the trailing bytes exist and are
2465  *      blanked. If the buffer already contains sufficient data it
2466  *      is untouched. Otherwise it is extended. Returns zero on
2467  *      success. The skb is freed on error.
2468  */
2469 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2470 {
2471         unsigned int size = skb->len;
2472         if (likely(size >= len))
2473                 return 0;
2474         return skb_pad(skb, len - size);
2475 }
2476 
2477 /**
2478  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
2479  *      @skb: buffer to pad
2480  *      @len: minimal length
2481  *
2482  *      Pads up a buffer to ensure the trailing bytes exist and are
2483  *      blanked. If the buffer already contains sufficient data it
2484  *      is untouched. Otherwise it is extended. Returns zero on
2485  *      success. The skb is freed on error.
2486  */
2487 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2488 {
2489         unsigned int size = skb->len;
2490 
2491         if (unlikely(size < len)) {
2492                 len -= size;
2493                 if (skb_pad(skb, len))
2494                         return -ENOMEM;
2495                 __skb_put(skb, len);
2496         }
2497         return 0;
2498 }
2499 
2500 static inline int skb_add_data(struct sk_buff *skb,
2501                                struct iov_iter *from, int copy)
2502 {
2503         const int off = skb->len;
2504 
2505         if (skb->ip_summed == CHECKSUM_NONE) {
2506                 __wsum csum = 0;
2507                 if (csum_and_copy_from_iter(skb_put(skb, copy), copy,
2508                                             &csum, from) == copy) {
2509                         skb->csum = csum_block_add(skb->csum, csum, off);
2510                         return 0;
2511                 }
2512         } else if (copy_from_iter(skb_put(skb, copy), copy, from) == copy)
2513                 return 0;
2514 
2515         __skb_trim(skb, off);
2516         return -EFAULT;
2517 }
2518 
2519 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2520                                     const struct page *page, int off)
2521 {
2522         if (i) {
2523                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2524 
2525                 return page == skb_frag_page(frag) &&
2526                        off == frag->page_offset + skb_frag_size(frag);
2527         }
2528         return false;
2529 }
2530 
2531 static inline int __skb_linearize(struct sk_buff *skb)
2532 {
2533         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2534 }
2535 
2536 /**
2537  *      skb_linearize - convert paged skb to linear one
2538  *      @skb: buffer to linarize
2539  *
2540  *      If there is no free memory -ENOMEM is returned, otherwise zero
2541  *      is returned and the old skb data released.
2542  */
2543 static inline int skb_linearize(struct sk_buff *skb)
2544 {
2545         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2546 }
2547 
2548 /**
2549  * skb_has_shared_frag - can any frag be overwritten
2550  * @skb: buffer to test
2551  *
2552  * Return true if the skb has at least one frag that might be modified
2553  * by an external entity (as in vmsplice()/sendfile())
2554  */
2555 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2556 {
2557         return skb_is_nonlinear(skb) &&
2558                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2559 }
2560 
2561 /**
2562  *      skb_linearize_cow - make sure skb is linear and writable
2563  *      @skb: buffer to process
2564  *
2565  *      If there is no free memory -ENOMEM is returned, otherwise zero
2566  *      is returned and the old skb data released.
2567  */
2568 static inline int skb_linearize_cow(struct sk_buff *skb)
2569 {
2570         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2571                __skb_linearize(skb) : 0;
2572 }
2573 
2574 /**
2575  *      skb_postpull_rcsum - update checksum for received skb after pull
2576  *      @skb: buffer to update
2577  *      @start: start of data before pull
2578  *      @len: length of data pulled
2579  *
2580  *      After doing a pull on a received packet, you need to call this to
2581  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2582  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2583  */
2584 
2585 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2586                                       const void *start, unsigned int len)
2587 {
2588         if (skb->ip_summed == CHECKSUM_COMPLETE)
2589                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2590 }
2591 
2592 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2593 
2594 /**
2595  *      pskb_trim_rcsum - trim received skb and update checksum
2596  *      @skb: buffer to trim
2597  *      @len: new length
2598  *
2599  *      This is exactly the same as pskb_trim except that it ensures the
2600  *      checksum of received packets are still valid after the operation.
2601  */
2602 
2603 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2604 {
2605         if (likely(len >= skb->len))
2606                 return 0;
2607         if (skb->ip_summed == CHECKSUM_COMPLETE)
2608                 skb->ip_summed = CHECKSUM_NONE;
2609         return __pskb_trim(skb, len);
2610 }
2611 
2612 #define skb_queue_walk(queue, skb) \
2613                 for (skb = (queue)->next;                                       \
2614                      skb != (struct sk_buff *)(queue);                          \
2615                      skb = skb->next)
2616 
2617 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2618                 for (skb = (queue)->next, tmp = skb->next;                      \
2619                      skb != (struct sk_buff *)(queue);                          \
2620                      skb = tmp, tmp = skb->next)
2621 
2622 #define skb_queue_walk_from(queue, skb)                                         \
2623                 for (; skb != (struct sk_buff *)(queue);                        \
2624                      skb = skb->next)
2625 
2626 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2627                 for (tmp = skb->next;                                           \
2628                      skb != (struct sk_buff *)(queue);                          \
2629                      skb = tmp, tmp = skb->next)
2630 
2631 #define skb_queue_reverse_walk(queue, skb) \
2632                 for (skb = (queue)->prev;                                       \
2633                      skb != (struct sk_buff *)(queue);                          \
2634                      skb = skb->prev)
2635 
2636 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2637                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2638                      skb != (struct sk_buff *)(queue);                          \
2639                      skb = tmp, tmp = skb->prev)
2640 
2641 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2642                 for (tmp = skb->prev;                                           \
2643                      skb != (struct sk_buff *)(queue);                          \
2644                      skb = tmp, tmp = skb->prev)
2645 
2646 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2647 {
2648         return skb_shinfo(skb)->frag_list != NULL;
2649 }
2650 
2651 static inline void skb_frag_list_init(struct sk_buff *skb)
2652 {
2653         skb_shinfo(skb)->frag_list = NULL;
2654 }
2655 
2656 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2657 {
2658         frag->next = skb_shinfo(skb)->frag_list;
2659         skb_shinfo(skb)->frag_list = frag;
2660 }
2661 
2662 #define skb_walk_frags(skb, iter)       \
2663         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2664 
2665 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2666                                     int *peeked, int *off, int *err);
2667 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2668                                   int *err);
2669 unsigned int datagram_poll(struct file *file, struct socket *sock,
2670                            struct poll_table_struct *wait);
2671 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
2672                            struct iov_iter *to, int size);
2673 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
2674                                         struct msghdr *msg, int size)
2675 {
2676         return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
2677 }
2678 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
2679                                    struct msghdr *msg);
2680 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
2681                                  struct iov_iter *from, int len);
2682 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
2683 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2684 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2685 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2686 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2687 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2688 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2689                               int len, __wsum csum);
2690 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
2691                     struct pipe_inode_info *pipe, unsigned int len,
2692                     unsigned int flags);
2693 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2694 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
2695 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
2696                  int len, int hlen);
2697 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2698 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2699 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2700 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2701 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2702 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
2703 int skb_ensure_writable(struct sk_buff *skb, int write_len);
2704 int skb_vlan_pop(struct sk_buff *skb);
2705 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
2706 
2707 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
2708 {
2709         return copy_from_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
2710 }
2711 
2712 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
2713 {
2714         return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
2715 }
2716 
2717 struct skb_checksum_ops {
2718         __wsum (*update)(const void *mem, int len, __wsum wsum);
2719         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2720 };
2721 
2722 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2723                       __wsum csum, const struct skb_checksum_ops *ops);
2724 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2725                     __wsum csum);
2726 
2727 static inline void *__skb_header_pointer(const struct sk_buff *skb, int offset,
2728                                          int len, void *data, int hlen, void *buffer)
2729 {
2730         if (hlen - offset >= len)
2731                 return data + offset;
2732 
2733         if (!skb ||
2734             skb_copy_bits(skb, offset, buffer, len) < 0)
2735                 return NULL;
2736 
2737         return buffer;
2738 }
2739 
2740 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2741                                        int len, void *buffer)
2742 {
2743         return __skb_header_pointer(skb, offset, len, skb->data,
2744                                     skb_headlen(skb), buffer);
2745 }
2746 
2747 /**
2748  *      skb_needs_linearize - check if we need to linearize a given skb
2749  *                            depending on the given device features.
2750  *      @skb: socket buffer to check
2751  *      @features: net device features
2752  *
2753  *      Returns true if either:
2754  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
2755  *      2. skb is fragmented and the device does not support SG.
2756  */
2757 static inline bool skb_needs_linearize(struct sk_buff *skb,
2758                                        netdev_features_t features)
2759 {
2760         return skb_is_nonlinear(skb) &&
2761                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
2762                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
2763 }
2764 
2765 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2766                                              void *to,
2767                                              const unsigned int len)
2768 {
2769         memcpy(to, skb->data, len);
2770 }
2771 
2772 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2773                                                     const int offset, void *to,
2774                                                     const unsigned int len)
2775 {
2776         memcpy(to, skb->data + offset, len);
2777 }
2778 
2779 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2780                                            const void *from,
2781                                            const unsigned int len)
2782 {
2783         memcpy(skb->data, from, len);
2784 }
2785 
2786 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2787                                                   const int offset,
2788                                                   const void *from,
2789                                                   const unsigned int len)
2790 {
2791         memcpy(skb->data + offset, from, len);
2792 }
2793 
2794 void skb_init(void);
2795 
2796 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2797 {
2798         return skb->tstamp;
2799 }
2800 
2801 /**
2802  *      skb_get_timestamp - get timestamp from a skb
2803  *      @skb: skb to get stamp from
2804  *      @stamp: pointer to struct timeval to store stamp in
2805  *
2806  *      Timestamps are stored in the skb as offsets to a base timestamp.
2807  *      This function converts the offset back to a struct timeval and stores
2808  *      it in stamp.
2809  */
2810 static inline void skb_get_timestamp(const struct sk_buff *skb,
2811                                      struct timeval *stamp)
2812 {
2813         *stamp = ktime_to_timeval(skb->tstamp);
2814 }
2815 
2816 static inline void skb_get_timestampns(const struct sk_buff *skb,
2817                                        struct timespec *stamp)
2818 {
2819         *stamp = ktime_to_timespec(skb->tstamp);
2820 }
2821 
2822 static inline void __net_timestamp(struct sk_buff *skb)
2823 {
2824         skb->tstamp = ktime_get_real();
2825 }
2826 
2827 static inline ktime_t net_timedelta(ktime_t t)
2828 {
2829         return ktime_sub(ktime_get_real(), t);
2830 }
2831 
2832 static inline ktime_t net_invalid_timestamp(void)
2833 {
2834         return ktime_set(0, 0);
2835 }
2836 
2837 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
2838 
2839 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2840 
2841 void skb_clone_tx_timestamp(struct sk_buff *skb);
2842 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2843 
2844 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2845 
2846 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2847 {
2848 }
2849 
2850 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2851 {
2852         return false;
2853 }
2854 
2855 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2856 
2857 /**
2858  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2859  *
2860  * PHY drivers may accept clones of transmitted packets for
2861  * timestamping via their phy_driver.txtstamp method. These drivers
2862  * must call this function to return the skb back to the stack, with
2863  * or without a timestamp.
2864  *
2865  * @skb: clone of the the original outgoing packet
2866  * @hwtstamps: hardware time stamps, may be NULL if not available
2867  *
2868  */
2869 void skb_complete_tx_timestamp(struct sk_buff *skb,
2870                                struct skb_shared_hwtstamps *hwtstamps);
2871 
2872 void __skb_tstamp_tx(struct sk_buff *orig_skb,
2873                      struct skb_shared_hwtstamps *hwtstamps,
2874                      struct sock *sk, int tstype);
2875 
2876 /**
2877  * skb_tstamp_tx - queue clone of skb with send time stamps
2878  * @orig_skb:   the original outgoing packet
2879  * @hwtstamps:  hardware time stamps, may be NULL if not available
2880  *
2881  * If the skb has a socket associated, then this function clones the
2882  * skb (thus sharing the actual data and optional structures), stores
2883  * the optional hardware time stamping information (if non NULL) or
2884  * generates a software time stamp (otherwise), then queues the clone
2885  * to the error queue of the socket.  Errors are silently ignored.
2886  */
2887 void skb_tstamp_tx(struct sk_buff *orig_skb,
2888                    struct skb_shared_hwtstamps *hwtstamps);
2889 
2890 static inline void sw_tx_timestamp(struct sk_buff *skb)
2891 {
2892         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2893             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2894                 skb_tstamp_tx(skb, NULL);
2895 }
2896 
2897 /**
2898  * skb_tx_timestamp() - Driver hook for transmit timestamping
2899  *
2900  * Ethernet MAC Drivers should call this function in their hard_xmit()
2901  * function immediately before giving the sk_buff to the MAC hardware.
2902  *
2903  * Specifically, one should make absolutely sure that this function is
2904  * called before TX completion of this packet can trigger.  Otherwise
2905  * the packet could potentially already be freed.
2906  *
2907  * @skb: A socket buffer.
2908  */
2909 static inline void skb_tx_timestamp(struct sk_buff *skb)
2910 {
2911         skb_clone_tx_timestamp(skb);
2912         sw_tx_timestamp(skb);
2913 }
2914 
2915 /**
2916  * skb_complete_wifi_ack - deliver skb with wifi status
2917  *
2918  * @skb: the original outgoing packet
2919  * @acked: ack status
2920  *
2921  */
2922 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2923 
2924 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2925 __sum16 __skb_checksum_complete(struct sk_buff *skb);
2926 
2927 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2928 {
2929         return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
2930                 skb->csum_valid ||
2931                 (skb->ip_summed == CHECKSUM_PARTIAL &&
2932                  skb_checksum_start_offset(skb) >= 0));
2933 }
2934 
2935 /**
2936  *      skb_checksum_complete - Calculate checksum of an entire packet
2937  *      @skb: packet to process
2938  *
2939  *      This function calculates the checksum over the entire packet plus
2940  *      the value of skb->csum.  The latter can be used to supply the
2941  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2942  *      checksum.
2943  *
2944  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2945  *      this function can be used to verify that checksum on received
2946  *      packets.  In that case the function should return zero if the
2947  *      checksum is correct.  In particular, this function will return zero
2948  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2949  *      hardware has already verified the correctness of the checksum.
2950  */
2951 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2952 {
2953         return skb_csum_unnecessary(skb) ?
2954                0 : __skb_checksum_complete(skb);
2955 }
2956 
2957 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
2958 {
2959         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
2960                 if (skb->csum_level == 0)
2961                         skb->ip_summed = CHECKSUM_NONE;
2962                 else
2963                         skb->csum_level--;
2964         }
2965 }
2966 
2967 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
2968 {
2969         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
2970                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
2971                         skb->csum_level++;
2972         } else if (skb->ip_summed == CHECKSUM_NONE) {
2973                 skb->ip_summed = CHECKSUM_UNNECESSARY;
2974                 skb->csum_level = 0;
2975         }
2976 }
2977 
2978 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
2979 {
2980         /* Mark current checksum as bad (typically called from GRO
2981          * path). In the case that ip_summed is CHECKSUM_NONE
2982          * this must be the first checksum encountered in the packet.
2983          * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
2984          * checksum after the last one validated. For UDP, a zero
2985          * checksum can not be marked as bad.
2986          */
2987 
2988         if (skb->ip_summed == CHECKSUM_NONE ||
2989             skb->ip_summed == CHECKSUM_UNNECESSARY)
2990                 skb->csum_bad = 1;
2991 }
2992 
2993 /* Check if we need to perform checksum complete validation.
2994  *
2995  * Returns true if checksum complete is needed, false otherwise
2996  * (either checksum is unnecessary or zero checksum is allowed).
2997  */
2998 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
2999                                                   bool zero_okay,
3000                                                   __sum16 check)
3001 {
3002         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3003                 skb->csum_valid = 1;
3004                 __skb_decr_checksum_unnecessary(skb);
3005                 return false;
3006         }
3007 
3008         return true;
3009 }
3010 
3011 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3012  * in checksum_init.
3013  */
3014 #define CHECKSUM_BREAK 76
3015 
3016 /* Validate (init) checksum based on checksum complete.
3017  *
3018  * Return values:
3019  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
3020  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3021  *      checksum is stored in skb->csum for use in __skb_checksum_complete
3022  *   non-zero: value of invalid checksum
3023  *
3024  */
3025 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3026                                                        bool complete,
3027                                                        __wsum psum)
3028 {
3029         if (skb->ip_summed == CHECKSUM_COMPLETE) {
3030                 if (!csum_fold(csum_add(psum, skb->csum))) {
3031                         skb->csum_valid = 1;
3032                         return 0;
3033                 }
3034         } else if (skb->csum_bad) {
3035                 /* ip_summed == CHECKSUM_NONE in this case */
3036                 return 1;
3037         }
3038 
3039         skb->csum = psum;
3040 
3041         if (complete || skb->len <= CHECKSUM_BREAK) {
3042                 __sum16 csum;
3043 
3044                 csum = __skb_checksum_complete(skb);
3045                 skb->csum_valid = !csum;
3046                 return csum;
3047         }
3048 
3049         return 0;
3050 }
3051 
3052 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3053 {
3054         return 0;
3055 }
3056 
3057 /* Perform checksum validate (init). Note that this is a macro since we only
3058  * want to calculate the pseudo header which is an input function if necessary.
3059  * First we try to validate without any computation (checksum unnecessary) and
3060  * then calculate based on checksum complete calling the function to compute
3061  * pseudo header.
3062  *
3063  * Return values:
3064  *   0: checksum is validated or try to in skb_checksum_complete
3065  *   non-zero: value of invalid checksum
3066  */
3067 #define __skb_checksum_validate(skb, proto, complete,                   \
3068                                 zero_okay, check, compute_pseudo)       \
3069 ({                                                                      \
3070         __sum16 __ret = 0;                                              \
3071         skb->csum_valid = 0;                                            \
3072         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3073                 __ret = __skb_checksum_validate_complete(skb,           \
3074                                 complete, compute_pseudo(skb, proto));  \
3075         __ret;                                                          \
3076 })
3077 
3078 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3079         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3080 
3081 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3082         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3083 
3084 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3085         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3086 
3087 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3088                                          compute_pseudo)                \
3089         __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3090 
3091 #define skb_checksum_simple_validate(skb)                               \
3092         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3093 
3094 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3095 {
3096         return (skb->ip_summed == CHECKSUM_NONE &&
3097                 skb->csum_valid && !skb->csum_bad);
3098 }
3099 
3100 static inline void __skb_checksum_convert(struct sk_buff *skb,
3101                                           __sum16 check, __wsum pseudo)
3102 {
3103         skb->csum = ~pseudo;
3104         skb->ip_summed = CHECKSUM_COMPLETE;
3105 }
3106 
3107 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3108 do {                                                                    \
3109         if (__skb_checksum_convert_check(skb))                          \
3110                 __skb_checksum_convert(skb, check,                      \
3111                                        compute_pseudo(skb, proto));     \
3112 } while (0)
3113 
3114 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3115                                               u16 start, u16 offset)
3116 {
3117         skb->ip_summed = CHECKSUM_PARTIAL;
3118         skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3119         skb->csum_offset = offset - start;
3120 }
3121 
3122 /* Update skbuf and packet to reflect the remote checksum offload operation.
3123  * When called, ptr indicates the starting point for skb->csum when
3124  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3125  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3126  */
3127 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3128                                        int start, int offset, bool nopartial)
3129 {
3130         __wsum delta;
3131 
3132         if (!nopartial) {
3133                 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3134                 return;
3135         }
3136 
3137          if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3138                 __skb_checksum_complete(skb);
3139                 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3140         }
3141 
3142         delta = remcsum_adjust(ptr, skb->csum, start, offset);
3143 
3144         /* Adjust skb->csum since we changed the packet */
3145         skb->csum = csum_add(skb->csum, delta);
3146 }
3147 
3148 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3149 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3150 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3151 {
3152         if (nfct && atomic_dec_and_test(&nfct->use))
3153                 nf_conntrack_destroy(nfct);
3154 }
3155 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3156 {
3157         if (nfct)
3158                 atomic_inc(&nfct->use);
3159 }
3160 #endif
3161 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3162 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3163 {
3164         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3165                 kfree(nf_bridge);
3166 }
3167 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3168 {
3169         if (nf_bridge)
3170                 atomic_inc(&nf_bridge->use);
3171 }
3172 #endif /* CONFIG_BRIDGE_NETFILTER */
3173 static inline void nf_reset(struct sk_buff *skb)
3174 {
3175 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3176         nf_conntrack_put(skb->nfct);
3177         skb->nfct = NULL;
3178 #endif
3179 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3180         nf_bridge_put(skb->nf_bridge);
3181         skb->nf_bridge = NULL;
3182 #endif
3183 }
3184 
3185 static inline void nf_reset_trace(struct sk_buff *skb)
3186 {
3187 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3188         skb->nf_trace = 0;
3189 #endif
3190 }
3191 
3192 /* Note: This doesn't put any conntrack and bridge info in dst. */
3193 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3194                              bool copy)
3195 {
3196 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3197         dst->nfct = src->nfct;
3198         nf_conntrack_get(src->nfct);
3199         if (copy)
3200                 dst->nfctinfo = src->nfctinfo;
3201 #endif
3202 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3203         dst->nf_bridge  = src->nf_bridge;
3204         nf_bridge_get(src->nf_bridge);
3205 #endif
3206 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3207         if (copy)
3208                 dst->nf_trace = src->nf_trace;
3209 #endif
3210 }
3211 
3212 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3213 {
3214 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3215         nf_conntrack_put(dst->nfct);
3216 #endif
3217 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3218         nf_bridge_put(dst->nf_bridge);
3219 #endif
3220         __nf_copy(dst, src, true);
3221 }
3222 
3223 #ifdef CONFIG_NETWORK_SECMARK
3224 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3225 {
3226         to->secmark = from->secmark;
3227 }
3228 
3229 static inline void skb_init_secmark(struct sk_buff *skb)
3230 {
3231         skb->secmark = 0;
3232 }
3233 #else
3234 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3235 { }
3236 
3237 static inline void skb_init_secmark(struct sk_buff *skb)
3238 { }
3239 #endif
3240 
3241 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3242 {
3243         return !skb->destructor &&
3244 #if IS_ENABLED(CONFIG_XFRM)
3245                 !skb->sp &&
3246 #endif
3247 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3248                 !skb->nfct &&
3249 #endif
3250                 !skb->_skb_refdst &&
3251                 !skb_has_frag_list(skb);
3252 }
3253 
3254 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3255 {
3256         skb->queue_mapping = queue_mapping;
3257 }
3258 
3259 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3260 {
3261         return skb->queue_mapping;
3262 }
3263 
3264 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3265 {
3266         to->queue_mapping = from->queue_mapping;
3267 }
3268 
3269 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3270 {
3271         skb->queue_mapping = rx_queue + 1;
3272 }
3273 
3274 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3275 {
3276         return skb->queue_mapping - 1;
3277 }
3278 
3279 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3280 {
3281         return skb->queue_mapping != 0;
3282 }
3283 
3284 u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
3285                   unsigned int num_tx_queues);
3286 
3287 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3288 {
3289 #ifdef CONFIG_XFRM
3290         return skb->sp;
3291 #else
3292         return NULL;
3293 #endif
3294 }
3295 
3296 /* Keeps track of mac header offset relative to skb->head.
3297  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3298  * For non-tunnel skb it points to skb_mac_header() and for
3299  * tunnel skb it points to outer mac header.
3300  * Keeps track of level of encapsulation of network headers.
3301  */
3302 struct skb_gso_cb {
3303         int     mac_offset;
3304         int     encap_level;
3305         __u16   csum_start;
3306 };
3307 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
3308 
3309 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3310 {
3311         return (skb_mac_header(inner_skb) - inner_skb->head) -
3312                 SKB_GSO_CB(inner_skb)->mac_offset;
3313 }
3314 
3315 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3316 {
3317         int new_headroom, headroom;
3318         int ret;
3319 
3320         headroom = skb_headroom(skb);
3321         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3322         if (ret)
3323                 return ret;
3324 
3325         new_headroom = skb_headroom(skb);
3326         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3327         return 0;
3328 }
3329 
3330 /* Compute the checksum for a gso segment. First compute the checksum value
3331  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3332  * then add in skb->csum (checksum from csum_start to end of packet).
3333  * skb->csum and csum_start are then updated to reflect the checksum of the
3334  * resultant packet starting from the transport header-- the resultant checksum
3335  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3336  * header.
3337  */
3338 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3339 {
3340         int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
3341             skb_transport_offset(skb);
3342         __u16 csum;
3343 
3344         csum = csum_fold(csum_partial(skb_transport_header(skb),
3345                                       plen, skb->csum));
3346         skb->csum = res;
3347         SKB_GSO_CB(skb)->csum_start -= plen;
3348 
3349         return csum;
3350 }
3351 
3352 static inline bool skb_is_gso(const struct sk_buff *skb)
3353 {
3354         return skb_shinfo(skb)->gso_size;
3355 }
3356 
3357 /* Note: Should be called only if skb_is_gso(skb) is true */
3358 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3359 {
3360         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3361 }
3362 
3363 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3364 
3365 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3366 {
3367         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3368          * wanted then gso_type will be set. */
3369         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3370 
3371         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3372             unlikely(shinfo->gso_type == 0)) {
3373                 __skb_warn_lro_forwarding(skb);
3374                 return true;
3375         }
3376         return false;
3377 }
3378 
3379 static inline void skb_forward_csum(struct sk_buff *skb)
3380 {
3381         /* Unfortunately we don't support this one.  Any brave souls? */
3382         if (skb->ip_summed == CHECKSUM_COMPLETE)
3383                 skb->ip_summed = CHECKSUM_NONE;
3384 }
3385 
3386 /**
3387  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3388  * @skb: skb to check
3389  *
3390  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3391  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3392  * use this helper, to document places where we make this assertion.
3393  */
3394 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3395 {
3396 #ifdef DEBUG
3397         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3398 #endif
3399 }
3400 
3401 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3402 
3403 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3404 
3405 u32 skb_get_poff(const struct sk_buff *skb);
3406 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
3407                    const struct flow_keys *keys, int hlen);
3408 
3409 /**
3410  * skb_head_is_locked - Determine if the skb->head is locked down
3411  * @skb: skb to check
3412  *
3413  * The head on skbs build around a head frag can be removed if they are
3414  * not cloned.  This function returns true if the skb head is locked down
3415  * due to either being allocated via kmalloc, or by being a clone with
3416  * multiple references to the head.
3417  */
3418 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3419 {
3420         return !skb->head_frag || skb_cloned(skb);
3421 }
3422 
3423 /**
3424  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3425  *
3426  * @skb: GSO skb
3427  *
3428  * skb_gso_network_seglen is used to determine the real size of the
3429  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3430  *
3431  * The MAC/L2 header is not accounted for.
3432  */
3433 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3434 {
3435         unsigned int hdr_len = skb_transport_header(skb) -
3436                                skb_network_header(skb);
3437         return hdr_len + skb_gso_transport_seglen(skb);
3438 }
3439 #endif  /* __KERNEL__ */
3440 #endif  /* _LINUX_SKBUFF_H */
3441 

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