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TOMOYO Linux Cross Reference
Linux/include/linux/skbuff.h

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  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 
 24 #include <linux/atomic.h>
 25 #include <asm/types.h>
 26 #include <linux/spinlock.h>
 27 #include <linux/net.h>
 28 #include <linux/textsearch.h>
 29 #include <net/checksum.h>
 30 #include <linux/rcupdate.h>
 31 #include <linux/hrtimer.h>
 32 #include <linux/dma-mapping.h>
 33 #include <linux/netdev_features.h>
 34 #include <linux/sched.h>
 35 #include <net/flow_keys.h>
 36 
 37 /* A. Checksumming of received packets by device.
 38  *
 39  * CHECKSUM_NONE:
 40  *
 41  *   Device failed to checksum this packet e.g. due to lack of capabilities.
 42  *   The packet contains full (though not verified) checksum in packet but
 43  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 44  *
 45  * CHECKSUM_UNNECESSARY:
 46  *
 47  *   The hardware you're dealing with doesn't calculate the full checksum
 48  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
 49  *   for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
 50  *   if their checksums are okay. skb->csum is still undefined in this case
 51  *   though. It is a bad option, but, unfortunately, nowadays most vendors do
 52  *   this. Apparently with the secret goal to sell you new devices, when you
 53  *   will add new protocol to your host, f.e. IPv6 8)
 54  *
 55  *   CHECKSUM_UNNECESSARY is applicable to following protocols:
 56  *     TCP: IPv6 and IPv4.
 57  *     UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
 58  *       zero UDP checksum for either IPv4 or IPv6, the networking stack
 59  *       may perform further validation in this case.
 60  *     GRE: only if the checksum is present in the header.
 61  *     SCTP: indicates the CRC in SCTP header has been validated.
 62  *
 63  *   skb->csum_level indicates the number of consecutive checksums found in
 64  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
 65  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
 66  *   and a device is able to verify the checksums for UDP (possibly zero),
 67  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
 68  *   two. If the device were only able to verify the UDP checksum and not
 69  *   GRE, either because it doesn't support GRE checksum of because GRE
 70  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
 71  *   not considered in this case).
 72  *
 73  * CHECKSUM_COMPLETE:
 74  *
 75  *   This is the most generic way. The device supplied checksum of the _whole_
 76  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
 77  *   hardware doesn't need to parse L3/L4 headers to implement this.
 78  *
 79  *   Note: Even if device supports only some protocols, but is able to produce
 80  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
 81  *
 82  * CHECKSUM_PARTIAL:
 83  *
 84  *   This is identical to the case for output below. This may occur on a packet
 85  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
 86  *   on the same host. The packet can be treated in the same way as
 87  *   CHECKSUM_UNNECESSARY, except that on output (i.e., forwarding) the
 88  *   checksum must be filled in by the OS or the hardware.
 89  *
 90  * B. Checksumming on output.
 91  *
 92  * CHECKSUM_NONE:
 93  *
 94  *   The skb was already checksummed by the protocol, or a checksum is not
 95  *   required.
 96  *
 97  * CHECKSUM_PARTIAL:
 98  *
 99  *   The device is required to checksum the packet as seen by hard_start_xmit()
100  *   from skb->csum_start up to the end, and to record/write the checksum at
101  *   offset skb->csum_start + skb->csum_offset.
102  *
103  *   The device must show its capabilities in dev->features, set up at device
104  *   setup time, e.g. netdev_features.h:
105  *
106  *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
107  *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
108  *                        IPv4. Sigh. Vendors like this way for an unknown reason.
109  *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
110  *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
111  *      NETIF_F_...     - Well, you get the picture.
112  *
113  * CHECKSUM_UNNECESSARY:
114  *
115  *   Normally, the device will do per protocol specific checksumming. Protocol
116  *   implementations that do not want the NIC to perform the checksum
117  *   calculation should use this flag in their outgoing skbs.
118  *
119  *      NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
120  *                         offload. Correspondingly, the FCoE protocol driver
121  *                         stack should use CHECKSUM_UNNECESSARY.
122  *
123  * Any questions? No questions, good.           --ANK
124  */
125 
126 /* Don't change this without changing skb_csum_unnecessary! */
127 #define CHECKSUM_NONE           0
128 #define CHECKSUM_UNNECESSARY    1
129 #define CHECKSUM_COMPLETE       2
130 #define CHECKSUM_PARTIAL        3
131 
132 /* Maximum value in skb->csum_level */
133 #define SKB_MAX_CSUM_LEVEL      3
134 
135 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
136 #define SKB_WITH_OVERHEAD(X)    \
137         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
138 #define SKB_MAX_ORDER(X, ORDER) \
139         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
140 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
141 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
142 
143 /* return minimum truesize of one skb containing X bytes of data */
144 #define SKB_TRUESIZE(X) ((X) +                                          \
145                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
146                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
147 
148 struct net_device;
149 struct scatterlist;
150 struct pipe_inode_info;
151 
152 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
153 struct nf_conntrack {
154         atomic_t use;
155 };
156 #endif
157 
158 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
159 struct nf_bridge_info {
160         atomic_t                use;
161         unsigned int            mask;
162         struct net_device       *physindev;
163         struct net_device       *physoutdev;
164         unsigned long           data[32 / sizeof(unsigned long)];
165 };
166 #endif
167 
168 struct sk_buff_head {
169         /* These two members must be first. */
170         struct sk_buff  *next;
171         struct sk_buff  *prev;
172 
173         __u32           qlen;
174         spinlock_t      lock;
175 };
176 
177 struct sk_buff;
178 
179 /* To allow 64K frame to be packed as single skb without frag_list we
180  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
181  * buffers which do not start on a page boundary.
182  *
183  * Since GRO uses frags we allocate at least 16 regardless of page
184  * size.
185  */
186 #if (65536/PAGE_SIZE + 1) < 16
187 #define MAX_SKB_FRAGS 16UL
188 #else
189 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
190 #endif
191 extern int sysctl_max_skb_frags;
192 
193 typedef struct skb_frag_struct skb_frag_t;
194 
195 struct skb_frag_struct {
196         struct {
197                 struct page *p;
198         } page;
199 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
200         __u32 page_offset;
201         __u32 size;
202 #else
203         __u16 page_offset;
204         __u16 size;
205 #endif
206 };
207 
208 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
209 {
210         return frag->size;
211 }
212 
213 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
214 {
215         frag->size = size;
216 }
217 
218 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
219 {
220         frag->size += delta;
221 }
222 
223 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
224 {
225         frag->size -= delta;
226 }
227 
228 #define HAVE_HW_TIME_STAMP
229 
230 /**
231  * struct skb_shared_hwtstamps - hardware time stamps
232  * @hwtstamp:   hardware time stamp transformed into duration
233  *              since arbitrary point in time
234  *
235  * Software time stamps generated by ktime_get_real() are stored in
236  * skb->tstamp.
237  *
238  * hwtstamps can only be compared against other hwtstamps from
239  * the same device.
240  *
241  * This structure is attached to packets as part of the
242  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
243  */
244 struct skb_shared_hwtstamps {
245         ktime_t hwtstamp;
246 };
247 
248 /* Definitions for tx_flags in struct skb_shared_info */
249 enum {
250         /* generate hardware time stamp */
251         SKBTX_HW_TSTAMP = 1 << 0,
252 
253         /* generate software time stamp when queueing packet to NIC */
254         SKBTX_SW_TSTAMP = 1 << 1,
255 
256         /* device driver is going to provide hardware time stamp */
257         SKBTX_IN_PROGRESS = 1 << 2,
258 
259         /* device driver supports TX zero-copy buffers */
260         SKBTX_DEV_ZEROCOPY = 1 << 3,
261 
262         /* generate wifi status information (where possible) */
263         SKBTX_WIFI_STATUS = 1 << 4,
264 
265         /* This indicates at least one fragment might be overwritten
266          * (as in vmsplice(), sendfile() ...)
267          * If we need to compute a TX checksum, we'll need to copy
268          * all frags to avoid possible bad checksum
269          */
270         SKBTX_SHARED_FRAG = 1 << 5,
271 
272         /* generate software time stamp when entering packet scheduling */
273         SKBTX_SCHED_TSTAMP = 1 << 6,
274 
275         /* generate software timestamp on peer data acknowledgment */
276         SKBTX_ACK_TSTAMP = 1 << 7,
277 };
278 
279 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
280                                  SKBTX_SCHED_TSTAMP | \
281                                  SKBTX_ACK_TSTAMP)
282 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
283 
284 /*
285  * The callback notifies userspace to release buffers when skb DMA is done in
286  * lower device, the skb last reference should be 0 when calling this.
287  * The zerocopy_success argument is true if zero copy transmit occurred,
288  * false on data copy or out of memory error caused by data copy attempt.
289  * The ctx field is used to track device context.
290  * The desc field is used to track userspace buffer index.
291  */
292 struct ubuf_info {
293         void (*callback)(struct ubuf_info *, bool zerocopy_success);
294         void *ctx;
295         unsigned long desc;
296 };
297 
298 /* This data is invariant across clones and lives at
299  * the end of the header data, ie. at skb->end.
300  */
301 struct skb_shared_info {
302         unsigned char   nr_frags;
303         __u8            tx_flags;
304         unsigned short  gso_size;
305         /* Warning: this field is not always filled in (UFO)! */
306         unsigned short  gso_segs;
307         unsigned short  gso_type;
308         struct sk_buff  *frag_list;
309         struct skb_shared_hwtstamps hwtstamps;
310         u32             tskey;
311         __be32          ip6_frag_id;
312 
313         /*
314          * Warning : all fields before dataref are cleared in __alloc_skb()
315          */
316         atomic_t        dataref;
317 
318         /* Intermediate layers must ensure that destructor_arg
319          * remains valid until skb destructor */
320         void *          destructor_arg;
321 
322         /* must be last field, see pskb_expand_head() */
323         skb_frag_t      frags[MAX_SKB_FRAGS];
324 };
325 
326 /* We divide dataref into two halves.  The higher 16 bits hold references
327  * to the payload part of skb->data.  The lower 16 bits hold references to
328  * the entire skb->data.  A clone of a headerless skb holds the length of
329  * the header in skb->hdr_len.
330  *
331  * All users must obey the rule that the skb->data reference count must be
332  * greater than or equal to the payload reference count.
333  *
334  * Holding a reference to the payload part means that the user does not
335  * care about modifications to the header part of skb->data.
336  */
337 #define SKB_DATAREF_SHIFT 16
338 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
339 
340 
341 enum {
342         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
343         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
344         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
345         SKB_FCLONE_FREE,        /* this companion fclone skb is available */
346 };
347 
348 enum {
349         SKB_GSO_TCPV4 = 1 << 0,
350         SKB_GSO_UDP = 1 << 1,
351 
352         /* This indicates the skb is from an untrusted source. */
353         SKB_GSO_DODGY = 1 << 2,
354 
355         /* This indicates the tcp segment has CWR set. */
356         SKB_GSO_TCP_ECN = 1 << 3,
357 
358         SKB_GSO_TCPV6 = 1 << 4,
359 
360         SKB_GSO_FCOE = 1 << 5,
361 
362         SKB_GSO_GRE = 1 << 6,
363 
364         SKB_GSO_GRE_CSUM = 1 << 7,
365 
366         SKB_GSO_IPIP = 1 << 8,
367 
368         SKB_GSO_SIT = 1 << 9,
369 
370         SKB_GSO_UDP_TUNNEL = 1 << 10,
371 
372         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
373 
374         SKB_GSO_MPLS = 1 << 12,
375 
376 };
377 
378 #if BITS_PER_LONG > 32
379 #define NET_SKBUFF_DATA_USES_OFFSET 1
380 #endif
381 
382 #ifdef NET_SKBUFF_DATA_USES_OFFSET
383 typedef unsigned int sk_buff_data_t;
384 #else
385 typedef unsigned char *sk_buff_data_t;
386 #endif
387 
388 /**
389  * struct skb_mstamp - multi resolution time stamps
390  * @stamp_us: timestamp in us resolution
391  * @stamp_jiffies: timestamp in jiffies
392  */
393 struct skb_mstamp {
394         union {
395                 u64             v64;
396                 struct {
397                         u32     stamp_us;
398                         u32     stamp_jiffies;
399                 };
400         };
401 };
402 
403 /**
404  * skb_mstamp_get - get current timestamp
405  * @cl: place to store timestamps
406  */
407 static inline void skb_mstamp_get(struct skb_mstamp *cl)
408 {
409         u64 val = local_clock();
410 
411         do_div(val, NSEC_PER_USEC);
412         cl->stamp_us = (u32)val;
413         cl->stamp_jiffies = (u32)jiffies;
414 }
415 
416 /**
417  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
418  * @t1: pointer to newest sample
419  * @t0: pointer to oldest sample
420  */
421 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
422                                       const struct skb_mstamp *t0)
423 {
424         s32 delta_us = t1->stamp_us - t0->stamp_us;
425         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
426 
427         /* If delta_us is negative, this might be because interval is too big,
428          * or local_clock() drift is too big : fallback using jiffies.
429          */
430         if (delta_us <= 0 ||
431             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
432 
433                 delta_us = jiffies_to_usecs(delta_jiffies);
434 
435         return delta_us;
436 }
437 
438 
439 /** 
440  *      struct sk_buff - socket buffer
441  *      @next: Next buffer in list
442  *      @prev: Previous buffer in list
443  *      @tstamp: Time we arrived/left
444  *      @sk: Socket we are owned by
445  *      @dev: Device we arrived on/are leaving by
446  *      @cb: Control buffer. Free for use by every layer. Put private vars here
447  *      @_skb_refdst: destination entry (with norefcount bit)
448  *      @sp: the security path, used for xfrm
449  *      @len: Length of actual data
450  *      @data_len: Data length
451  *      @mac_len: Length of link layer header
452  *      @hdr_len: writable header length of cloned skb
453  *      @csum: Checksum (must include start/offset pair)
454  *      @csum_start: Offset from skb->head where checksumming should start
455  *      @csum_offset: Offset from csum_start where checksum should be stored
456  *      @priority: Packet queueing priority
457  *      @ignore_df: allow local fragmentation
458  *      @cloned: Head may be cloned (check refcnt to be sure)
459  *      @ip_summed: Driver fed us an IP checksum
460  *      @nohdr: Payload reference only, must not modify header
461  *      @nfctinfo: Relationship of this skb to the connection
462  *      @pkt_type: Packet class
463  *      @fclone: skbuff clone status
464  *      @ipvs_property: skbuff is owned by ipvs
465  *      @peeked: this packet has been seen already, so stats have been
466  *              done for it, don't do them again
467  *      @nf_trace: netfilter packet trace flag
468  *      @protocol: Packet protocol from driver
469  *      @destructor: Destruct function
470  *      @nfct: Associated connection, if any
471  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
472  *      @skb_iif: ifindex of device we arrived on
473  *      @tc_index: Traffic control index
474  *      @tc_verd: traffic control verdict
475  *      @hash: the packet hash
476  *      @queue_mapping: Queue mapping for multiqueue devices
477  *      @xmit_more: More SKBs are pending for this queue
478  *      @pfmemalloc: skbuff was allocated from PFMEMALLOC reserves
479  *      @ndisc_nodetype: router type (from link layer)
480  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
481  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
482  *              ports.
483  *      @sw_hash: indicates hash was computed in software stack
484  *      @wifi_acked_valid: wifi_acked was set
485  *      @wifi_acked: whether frame was acked on wifi or not
486  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
487   *     @napi_id: id of the NAPI struct this skb came from
488  *      @secmark: security marking
489  *      @mark: Generic packet mark
490  *      @dropcount: total number of sk_receive_queue overflows
491  *      @vlan_proto: vlan encapsulation protocol
492  *      @vlan_tci: vlan tag control information
493  *      @inner_protocol: Protocol (encapsulation)
494  *      @inner_transport_header: Inner transport layer header (encapsulation)
495  *      @inner_network_header: Network layer header (encapsulation)
496  *      @inner_mac_header: Link layer header (encapsulation)
497  *      @transport_header: Transport layer header
498  *      @network_header: Network layer header
499  *      @mac_header: Link layer header
500  *      @tail: Tail pointer
501  *      @end: End pointer
502  *      @head: Head of buffer
503  *      @data: Data head pointer
504  *      @truesize: Buffer size
505  *      @users: User count - see {datagram,tcp}.c
506  */
507 
508 struct sk_buff {
509         /* These two members must be first. */
510         struct sk_buff          *next;
511         struct sk_buff          *prev;
512 
513         union {
514                 ktime_t         tstamp;
515                 struct skb_mstamp skb_mstamp;
516         };
517 
518         struct sock             *sk;
519         struct net_device       *dev;
520 
521         /*
522          * This is the control buffer. It is free to use for every
523          * layer. Please put your private variables there. If you
524          * want to keep them across layers you have to do a skb_clone()
525          * first. This is owned by whoever has the skb queued ATM.
526          */
527         char                    cb[48] __aligned(8);
528 
529         unsigned long           _skb_refdst;
530         void                    (*destructor)(struct sk_buff *skb);
531 #ifdef CONFIG_XFRM
532         struct  sec_path        *sp;
533 #endif
534 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
535         struct nf_conntrack     *nfct;
536 #endif
537 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
538         struct nf_bridge_info   *nf_bridge;
539 #endif
540         unsigned int            len,
541                                 data_len;
542         __u16                   mac_len,
543                                 hdr_len;
544 
545         /* Following fields are _not_ copied in __copy_skb_header()
546          * Note that queue_mapping is here mostly to fill a hole.
547          */
548         kmemcheck_bitfield_begin(flags1);
549         __u16                   queue_mapping;
550         __u8                    cloned:1,
551                                 nohdr:1,
552                                 fclone:2,
553                                 peeked:1,
554                                 head_frag:1,
555                                 xmit_more:1,
556                                 pfmemalloc:1;
557         kmemcheck_bitfield_end(flags1);
558 
559         /* fields enclosed in headers_start/headers_end are copied
560          * using a single memcpy() in __copy_skb_header()
561          */
562         /* private: */
563         __u32                   headers_start[0];
564         /* public: */
565 
566 /* if you move pkt_type around you also must adapt those constants */
567 #ifdef __BIG_ENDIAN_BITFIELD
568 #define PKT_TYPE_MAX    (7 << 5)
569 #else
570 #define PKT_TYPE_MAX    7
571 #endif
572 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
573 
574         __u8                    __pkt_type_offset[0];
575         __u8                    pkt_type:3;
576         __u8                    ignore_df:1;
577         __u8                    nfctinfo:3;
578         __u8                    nf_trace:1;
579 
580         __u8                    ip_summed:2;
581         __u8                    ooo_okay:1;
582         __u8                    l4_hash:1;
583         __u8                    sw_hash:1;
584         __u8                    wifi_acked_valid:1;
585         __u8                    wifi_acked:1;
586         __u8                    no_fcs:1;
587 
588         /* Indicates the inner headers are valid in the skbuff. */
589         __u8                    encapsulation:1;
590         __u8                    encap_hdr_csum:1;
591         __u8                    csum_valid:1;
592         __u8                    csum_complete_sw:1;
593         __u8                    csum_level:2;
594         __u8                    csum_bad:1;
595 #ifdef CONFIG_IPV6_NDISC_NODETYPE
596         __u8                    ndisc_nodetype:2;
597 #endif
598         __u8                    ipvs_property:1;
599 
600         __u8                    inner_protocol_type:1;
601         /* 4 or 6 bit hole */
602 
603 #ifdef CONFIG_NET_SCHED
604         __u16                   tc_index;       /* traffic control index */
605 #ifdef CONFIG_NET_CLS_ACT
606         __u16                   tc_verd;        /* traffic control verdict */
607 #endif
608 #endif
609 
610         union {
611                 __wsum          csum;
612                 struct {
613                         __u16   csum_start;
614                         __u16   csum_offset;
615                 };
616         };
617         __u32                   priority;
618         int                     skb_iif;
619         __u32                   hash;
620         __be16                  vlan_proto;
621         __u16                   vlan_tci;
622 #ifdef CONFIG_NET_RX_BUSY_POLL
623         unsigned int    napi_id;
624 #endif
625 #ifdef CONFIG_NETWORK_SECMARK
626         __u32                   secmark;
627 #endif
628         union {
629                 __u32           mark;
630                 __u32           dropcount;
631                 __u32           reserved_tailroom;
632         };
633 
634         union {
635                 __be16          inner_protocol;
636                 __u8            inner_ipproto;
637         };
638 
639         __u16                   inner_transport_header;
640         __u16                   inner_network_header;
641         __u16                   inner_mac_header;
642 
643         __be16                  protocol;
644         __u16                   transport_header;
645         __u16                   network_header;
646         __u16                   mac_header;
647 
648         /* private: */
649         __u32                   headers_end[0];
650         /* public: */
651 
652         /* These elements must be at the end, see alloc_skb() for details.  */
653         sk_buff_data_t          tail;
654         sk_buff_data_t          end;
655         unsigned char           *head,
656                                 *data;
657         unsigned int            truesize;
658         atomic_t                users;
659 };
660 
661 #ifdef __KERNEL__
662 /*
663  *      Handling routines are only of interest to the kernel
664  */
665 #include <linux/slab.h>
666 
667 
668 #define SKB_ALLOC_FCLONE        0x01
669 #define SKB_ALLOC_RX            0x02
670 
671 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
672 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
673 {
674         return unlikely(skb->pfmemalloc);
675 }
676 
677 /*
678  * skb might have a dst pointer attached, refcounted or not.
679  * _skb_refdst low order bit is set if refcount was _not_ taken
680  */
681 #define SKB_DST_NOREF   1UL
682 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
683 
684 /**
685  * skb_dst - returns skb dst_entry
686  * @skb: buffer
687  *
688  * Returns skb dst_entry, regardless of reference taken or not.
689  */
690 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
691 {
692         /* If refdst was not refcounted, check we still are in a 
693          * rcu_read_lock section
694          */
695         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
696                 !rcu_read_lock_held() &&
697                 !rcu_read_lock_bh_held());
698         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
699 }
700 
701 /**
702  * skb_dst_set - sets skb dst
703  * @skb: buffer
704  * @dst: dst entry
705  *
706  * Sets skb dst, assuming a reference was taken on dst and should
707  * be released by skb_dst_drop()
708  */
709 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
710 {
711         skb->_skb_refdst = (unsigned long)dst;
712 }
713 
714 void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
715                          bool force);
716 
717 /**
718  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
719  * @skb: buffer
720  * @dst: dst entry
721  *
722  * Sets skb dst, assuming a reference was not taken on dst.
723  * If dst entry is cached, we do not take reference and dst_release
724  * will be avoided by refdst_drop. If dst entry is not cached, we take
725  * reference, so that last dst_release can destroy the dst immediately.
726  */
727 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
728 {
729         __skb_dst_set_noref(skb, dst, false);
730 }
731 
732 /**
733  * skb_dst_set_noref_force - sets skb dst, without taking reference
734  * @skb: buffer
735  * @dst: dst entry
736  *
737  * Sets skb dst, assuming a reference was not taken on dst.
738  * No reference is taken and no dst_release will be called. While for
739  * cached dsts deferred reclaim is a basic feature, for entries that are
740  * not cached it is caller's job to guarantee that last dst_release for
741  * provided dst happens when nobody uses it, eg. after a RCU grace period.
742  */
743 static inline void skb_dst_set_noref_force(struct sk_buff *skb,
744                                            struct dst_entry *dst)
745 {
746         __skb_dst_set_noref(skb, dst, true);
747 }
748 
749 /**
750  * skb_dst_is_noref - Test if skb dst isn't refcounted
751  * @skb: buffer
752  */
753 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
754 {
755         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
756 }
757 
758 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
759 {
760         return (struct rtable *)skb_dst(skb);
761 }
762 
763 void kfree_skb(struct sk_buff *skb);
764 void kfree_skb_list(struct sk_buff *segs);
765 void skb_tx_error(struct sk_buff *skb);
766 void consume_skb(struct sk_buff *skb);
767 void  __kfree_skb(struct sk_buff *skb);
768 extern struct kmem_cache *skbuff_head_cache;
769 
770 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
771 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
772                       bool *fragstolen, int *delta_truesize);
773 
774 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
775                             int node);
776 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
777 struct sk_buff *build_skb(void *data, unsigned int frag_size);
778 static inline struct sk_buff *alloc_skb(unsigned int size,
779                                         gfp_t priority)
780 {
781         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
782 }
783 
784 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
785                                      unsigned long data_len,
786                                      int max_page_order,
787                                      int *errcode,
788                                      gfp_t gfp_mask);
789 
790 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
791 struct sk_buff_fclones {
792         struct sk_buff  skb1;
793 
794         struct sk_buff  skb2;
795 
796         atomic_t        fclone_ref;
797 };
798 
799 /**
800  *      skb_fclone_busy - check if fclone is busy
801  *      @skb: buffer
802  *
803  * Returns true is skb is a fast clone, and its clone is not freed.
804  * Some drivers call skb_orphan() in their ndo_start_xmit(),
805  * so we also check that this didnt happen.
806  */
807 static inline bool skb_fclone_busy(const struct sock *sk,
808                                    const struct sk_buff *skb)
809 {
810         const struct sk_buff_fclones *fclones;
811 
812         fclones = container_of(skb, struct sk_buff_fclones, skb1);
813 
814         return skb->fclone == SKB_FCLONE_ORIG &&
815                fclones->skb2.fclone == SKB_FCLONE_CLONE &&
816                fclones->skb2.sk == sk;
817 }
818 
819 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
820                                                gfp_t priority)
821 {
822         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
823 }
824 
825 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
826 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
827 {
828         return __alloc_skb_head(priority, -1);
829 }
830 
831 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
832 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
833 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
834 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
835 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
836                                    gfp_t gfp_mask, bool fclone);
837 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
838                                           gfp_t gfp_mask)
839 {
840         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
841 }
842 
843 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
844 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
845                                      unsigned int headroom);
846 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
847                                 int newtailroom, gfp_t priority);
848 int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
849                                      int offset, int len);
850 int __must_check skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg,
851                               int offset, int len);
852 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
853 int skb_pad(struct sk_buff *skb, int pad);
854 #define dev_kfree_skb(a)        consume_skb(a)
855 
856 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
857                             int getfrag(void *from, char *to, int offset,
858                                         int len, int odd, struct sk_buff *skb),
859                             void *from, int length);
860 
861 struct skb_seq_state {
862         __u32           lower_offset;
863         __u32           upper_offset;
864         __u32           frag_idx;
865         __u32           stepped_offset;
866         struct sk_buff  *root_skb;
867         struct sk_buff  *cur_skb;
868         __u8            *frag_data;
869 };
870 
871 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
872                           unsigned int to, struct skb_seq_state *st);
873 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
874                           struct skb_seq_state *st);
875 void skb_abort_seq_read(struct skb_seq_state *st);
876 
877 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
878                            unsigned int to, struct ts_config *config,
879                            struct ts_state *state);
880 
881 /*
882  * Packet hash types specify the type of hash in skb_set_hash.
883  *
884  * Hash types refer to the protocol layer addresses which are used to
885  * construct a packet's hash. The hashes are used to differentiate or identify
886  * flows of the protocol layer for the hash type. Hash types are either
887  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
888  *
889  * Properties of hashes:
890  *
891  * 1) Two packets in different flows have different hash values
892  * 2) Two packets in the same flow should have the same hash value
893  *
894  * A hash at a higher layer is considered to be more specific. A driver should
895  * set the most specific hash possible.
896  *
897  * A driver cannot indicate a more specific hash than the layer at which a hash
898  * was computed. For instance an L3 hash cannot be set as an L4 hash.
899  *
900  * A driver may indicate a hash level which is less specific than the
901  * actual layer the hash was computed on. For instance, a hash computed
902  * at L4 may be considered an L3 hash. This should only be done if the
903  * driver can't unambiguously determine that the HW computed the hash at
904  * the higher layer. Note that the "should" in the second property above
905  * permits this.
906  */
907 enum pkt_hash_types {
908         PKT_HASH_TYPE_NONE,     /* Undefined type */
909         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
910         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
911         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
912 };
913 
914 static inline void
915 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
916 {
917         skb->l4_hash = (type == PKT_HASH_TYPE_L4);
918         skb->sw_hash = 0;
919         skb->hash = hash;
920 }
921 
922 void __skb_get_hash(struct sk_buff *skb);
923 static inline __u32 skb_get_hash(struct sk_buff *skb)
924 {
925         if (!skb->l4_hash && !skb->sw_hash)
926                 __skb_get_hash(skb);
927 
928         return skb->hash;
929 }
930 
931 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
932 {
933         return skb->hash;
934 }
935 
936 static inline void skb_clear_hash(struct sk_buff *skb)
937 {
938         skb->hash = 0;
939         skb->sw_hash = 0;
940         skb->l4_hash = 0;
941 }
942 
943 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
944 {
945         if (!skb->l4_hash)
946                 skb_clear_hash(skb);
947 }
948 
949 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
950 {
951         to->hash = from->hash;
952         to->sw_hash = from->sw_hash;
953         to->l4_hash = from->l4_hash;
954 };
955 
956 #ifdef NET_SKBUFF_DATA_USES_OFFSET
957 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
958 {
959         return skb->head + skb->end;
960 }
961 
962 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
963 {
964         return skb->end;
965 }
966 #else
967 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
968 {
969         return skb->end;
970 }
971 
972 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
973 {
974         return skb->end - skb->head;
975 }
976 #endif
977 
978 /* Internal */
979 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
980 
981 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
982 {
983         return &skb_shinfo(skb)->hwtstamps;
984 }
985 
986 /**
987  *      skb_queue_empty - check if a queue is empty
988  *      @list: queue head
989  *
990  *      Returns true if the queue is empty, false otherwise.
991  */
992 static inline int skb_queue_empty(const struct sk_buff_head *list)
993 {
994         return list->next == (const struct sk_buff *) list;
995 }
996 
997 /**
998  *      skb_queue_is_last - check if skb is the last entry in the queue
999  *      @list: queue head
1000  *      @skb: buffer
1001  *
1002  *      Returns true if @skb is the last buffer on the list.
1003  */
1004 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1005                                      const struct sk_buff *skb)
1006 {
1007         return skb->next == (const struct sk_buff *) list;
1008 }
1009 
1010 /**
1011  *      skb_queue_is_first - check if skb is the first entry in the queue
1012  *      @list: queue head
1013  *      @skb: buffer
1014  *
1015  *      Returns true if @skb is the first buffer on the list.
1016  */
1017 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1018                                       const struct sk_buff *skb)
1019 {
1020         return skb->prev == (const struct sk_buff *) list;
1021 }
1022 
1023 /**
1024  *      skb_queue_next - return the next packet in the queue
1025  *      @list: queue head
1026  *      @skb: current buffer
1027  *
1028  *      Return the next packet in @list after @skb.  It is only valid to
1029  *      call this if skb_queue_is_last() evaluates to false.
1030  */
1031 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1032                                              const struct sk_buff *skb)
1033 {
1034         /* This BUG_ON may seem severe, but if we just return then we
1035          * are going to dereference garbage.
1036          */
1037         BUG_ON(skb_queue_is_last(list, skb));
1038         return skb->next;
1039 }
1040 
1041 /**
1042  *      skb_queue_prev - return the prev packet in the queue
1043  *      @list: queue head
1044  *      @skb: current buffer
1045  *
1046  *      Return the prev packet in @list before @skb.  It is only valid to
1047  *      call this if skb_queue_is_first() evaluates to false.
1048  */
1049 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1050                                              const struct sk_buff *skb)
1051 {
1052         /* This BUG_ON may seem severe, but if we just return then we
1053          * are going to dereference garbage.
1054          */
1055         BUG_ON(skb_queue_is_first(list, skb));
1056         return skb->prev;
1057 }
1058 
1059 /**
1060  *      skb_get - reference buffer
1061  *      @skb: buffer to reference
1062  *
1063  *      Makes another reference to a socket buffer and returns a pointer
1064  *      to the buffer.
1065  */
1066 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1067 {
1068         atomic_inc(&skb->users);
1069         return skb;
1070 }
1071 
1072 /*
1073  * If users == 1, we are the only owner and are can avoid redundant
1074  * atomic change.
1075  */
1076 
1077 /**
1078  *      skb_cloned - is the buffer a clone
1079  *      @skb: buffer to check
1080  *
1081  *      Returns true if the buffer was generated with skb_clone() and is
1082  *      one of multiple shared copies of the buffer. Cloned buffers are
1083  *      shared data so must not be written to under normal circumstances.
1084  */
1085 static inline int skb_cloned(const struct sk_buff *skb)
1086 {
1087         return skb->cloned &&
1088                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1089 }
1090 
1091 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1092 {
1093         might_sleep_if(pri & __GFP_WAIT);
1094 
1095         if (skb_cloned(skb))
1096                 return pskb_expand_head(skb, 0, 0, pri);
1097 
1098         return 0;
1099 }
1100 
1101 /**
1102  *      skb_header_cloned - is the header a clone
1103  *      @skb: buffer to check
1104  *
1105  *      Returns true if modifying the header part of the buffer requires
1106  *      the data to be copied.
1107  */
1108 static inline int skb_header_cloned(const struct sk_buff *skb)
1109 {
1110         int dataref;
1111 
1112         if (!skb->cloned)
1113                 return 0;
1114 
1115         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1116         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1117         return dataref != 1;
1118 }
1119 
1120 /**
1121  *      skb_header_release - release reference to header
1122  *      @skb: buffer to operate on
1123  *
1124  *      Drop a reference to the header part of the buffer.  This is done
1125  *      by acquiring a payload reference.  You must not read from the header
1126  *      part of skb->data after this.
1127  *      Note : Check if you can use __skb_header_release() instead.
1128  */
1129 static inline void skb_header_release(struct sk_buff *skb)
1130 {
1131         BUG_ON(skb->nohdr);
1132         skb->nohdr = 1;
1133         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1134 }
1135 
1136 /**
1137  *      __skb_header_release - release reference to header
1138  *      @skb: buffer to operate on
1139  *
1140  *      Variant of skb_header_release() assuming skb is private to caller.
1141  *      We can avoid one atomic operation.
1142  */
1143 static inline void __skb_header_release(struct sk_buff *skb)
1144 {
1145         skb->nohdr = 1;
1146         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1147 }
1148 
1149 
1150 /**
1151  *      skb_shared - is the buffer shared
1152  *      @skb: buffer to check
1153  *
1154  *      Returns true if more than one person has a reference to this
1155  *      buffer.
1156  */
1157 static inline int skb_shared(const struct sk_buff *skb)
1158 {
1159         return atomic_read(&skb->users) != 1;
1160 }
1161 
1162 /**
1163  *      skb_share_check - check if buffer is shared and if so clone it
1164  *      @skb: buffer to check
1165  *      @pri: priority for memory allocation
1166  *
1167  *      If the buffer is shared the buffer is cloned and the old copy
1168  *      drops a reference. A new clone with a single reference is returned.
1169  *      If the buffer is not shared the original buffer is returned. When
1170  *      being called from interrupt status or with spinlocks held pri must
1171  *      be GFP_ATOMIC.
1172  *
1173  *      NULL is returned on a memory allocation failure.
1174  */
1175 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1176 {
1177         might_sleep_if(pri & __GFP_WAIT);
1178         if (skb_shared(skb)) {
1179                 struct sk_buff *nskb = skb_clone(skb, pri);
1180 
1181                 if (likely(nskb))
1182                         consume_skb(skb);
1183                 else
1184                         kfree_skb(skb);
1185                 skb = nskb;
1186         }
1187         return skb;
1188 }
1189 
1190 /*
1191  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1192  *      packets to handle cases where we have a local reader and forward
1193  *      and a couple of other messy ones. The normal one is tcpdumping
1194  *      a packet thats being forwarded.
1195  */
1196 
1197 /**
1198  *      skb_unshare - make a copy of a shared buffer
1199  *      @skb: buffer to check
1200  *      @pri: priority for memory allocation
1201  *
1202  *      If the socket buffer is a clone then this function creates a new
1203  *      copy of the data, drops a reference count on the old copy and returns
1204  *      the new copy with the reference count at 1. If the buffer is not a clone
1205  *      the original buffer is returned. When called with a spinlock held or
1206  *      from interrupt state @pri must be %GFP_ATOMIC
1207  *
1208  *      %NULL is returned on a memory allocation failure.
1209  */
1210 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1211                                           gfp_t pri)
1212 {
1213         might_sleep_if(pri & __GFP_WAIT);
1214         if (skb_cloned(skb)) {
1215                 struct sk_buff *nskb = skb_copy(skb, pri);
1216 
1217                 /* Free our shared copy */
1218                 if (likely(nskb))
1219                         consume_skb(skb);
1220                 else
1221                         kfree_skb(skb);
1222                 skb = nskb;
1223         }
1224         return skb;
1225 }
1226 
1227 /**
1228  *      skb_peek - peek at the head of an &sk_buff_head
1229  *      @list_: list to peek at
1230  *
1231  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1232  *      be careful with this one. A peek leaves the buffer on the
1233  *      list and someone else may run off with it. You must hold
1234  *      the appropriate locks or have a private queue to do this.
1235  *
1236  *      Returns %NULL for an empty list or a pointer to the head element.
1237  *      The reference count is not incremented and the reference is therefore
1238  *      volatile. Use with caution.
1239  */
1240 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1241 {
1242         struct sk_buff *skb = list_->next;
1243 
1244         if (skb == (struct sk_buff *)list_)
1245                 skb = NULL;
1246         return skb;
1247 }
1248 
1249 /**
1250  *      skb_peek_next - peek skb following the given one from a queue
1251  *      @skb: skb to start from
1252  *      @list_: list to peek at
1253  *
1254  *      Returns %NULL when the end of the list is met or a pointer to the
1255  *      next element. The reference count is not incremented and the
1256  *      reference is therefore volatile. Use with caution.
1257  */
1258 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1259                 const struct sk_buff_head *list_)
1260 {
1261         struct sk_buff *next = skb->next;
1262 
1263         if (next == (struct sk_buff *)list_)
1264                 next = NULL;
1265         return next;
1266 }
1267 
1268 /**
1269  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1270  *      @list_: list to peek at
1271  *
1272  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1273  *      be careful with this one. A peek leaves the buffer on the
1274  *      list and someone else may run off with it. You must hold
1275  *      the appropriate locks or have a private queue to do this.
1276  *
1277  *      Returns %NULL for an empty list or a pointer to the tail element.
1278  *      The reference count is not incremented and the reference is therefore
1279  *      volatile. Use with caution.
1280  */
1281 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1282 {
1283         struct sk_buff *skb = list_->prev;
1284 
1285         if (skb == (struct sk_buff *)list_)
1286                 skb = NULL;
1287         return skb;
1288 
1289 }
1290 
1291 /**
1292  *      skb_queue_len   - get queue length
1293  *      @list_: list to measure
1294  *
1295  *      Return the length of an &sk_buff queue.
1296  */
1297 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1298 {
1299         return list_->qlen;
1300 }
1301 
1302 /**
1303  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1304  *      @list: queue to initialize
1305  *
1306  *      This initializes only the list and queue length aspects of
1307  *      an sk_buff_head object.  This allows to initialize the list
1308  *      aspects of an sk_buff_head without reinitializing things like
1309  *      the spinlock.  It can also be used for on-stack sk_buff_head
1310  *      objects where the spinlock is known to not be used.
1311  */
1312 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1313 {
1314         list->prev = list->next = (struct sk_buff *)list;
1315         list->qlen = 0;
1316 }
1317 
1318 /*
1319  * This function creates a split out lock class for each invocation;
1320  * this is needed for now since a whole lot of users of the skb-queue
1321  * infrastructure in drivers have different locking usage (in hardirq)
1322  * than the networking core (in softirq only). In the long run either the
1323  * network layer or drivers should need annotation to consolidate the
1324  * main types of usage into 3 classes.
1325  */
1326 static inline void skb_queue_head_init(struct sk_buff_head *list)
1327 {
1328         spin_lock_init(&list->lock);
1329         __skb_queue_head_init(list);
1330 }
1331 
1332 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1333                 struct lock_class_key *class)
1334 {
1335         skb_queue_head_init(list);
1336         lockdep_set_class(&list->lock, class);
1337 }
1338 
1339 /*
1340  *      Insert an sk_buff on a list.
1341  *
1342  *      The "__skb_xxxx()" functions are the non-atomic ones that
1343  *      can only be called with interrupts disabled.
1344  */
1345 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1346                 struct sk_buff_head *list);
1347 static inline void __skb_insert(struct sk_buff *newsk,
1348                                 struct sk_buff *prev, struct sk_buff *next,
1349                                 struct sk_buff_head *list)
1350 {
1351         newsk->next = next;
1352         newsk->prev = prev;
1353         next->prev  = prev->next = newsk;
1354         list->qlen++;
1355 }
1356 
1357 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1358                                       struct sk_buff *prev,
1359                                       struct sk_buff *next)
1360 {
1361         struct sk_buff *first = list->next;
1362         struct sk_buff *last = list->prev;
1363 
1364         first->prev = prev;
1365         prev->next = first;
1366 
1367         last->next = next;
1368         next->prev = last;
1369 }
1370 
1371 /**
1372  *      skb_queue_splice - join two skb lists, this is designed for stacks
1373  *      @list: the new list to add
1374  *      @head: the place to add it in the first list
1375  */
1376 static inline void skb_queue_splice(const struct sk_buff_head *list,
1377                                     struct sk_buff_head *head)
1378 {
1379         if (!skb_queue_empty(list)) {
1380                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1381                 head->qlen += list->qlen;
1382         }
1383 }
1384 
1385 /**
1386  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1387  *      @list: the new list to add
1388  *      @head: the place to add it in the first list
1389  *
1390  *      The list at @list is reinitialised
1391  */
1392 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1393                                          struct sk_buff_head *head)
1394 {
1395         if (!skb_queue_empty(list)) {
1396                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1397                 head->qlen += list->qlen;
1398                 __skb_queue_head_init(list);
1399         }
1400 }
1401 
1402 /**
1403  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1404  *      @list: the new list to add
1405  *      @head: the place to add it in the first list
1406  */
1407 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1408                                          struct sk_buff_head *head)
1409 {
1410         if (!skb_queue_empty(list)) {
1411                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1412                 head->qlen += list->qlen;
1413         }
1414 }
1415 
1416 /**
1417  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1418  *      @list: the new list to add
1419  *      @head: the place to add it in the first list
1420  *
1421  *      Each of the lists is a queue.
1422  *      The list at @list is reinitialised
1423  */
1424 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1425                                               struct sk_buff_head *head)
1426 {
1427         if (!skb_queue_empty(list)) {
1428                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1429                 head->qlen += list->qlen;
1430                 __skb_queue_head_init(list);
1431         }
1432 }
1433 
1434 /**
1435  *      __skb_queue_after - queue a buffer at the list head
1436  *      @list: list to use
1437  *      @prev: place after this buffer
1438  *      @newsk: buffer to queue
1439  *
1440  *      Queue a buffer int the middle of a list. This function takes no locks
1441  *      and you must therefore hold required locks before calling it.
1442  *
1443  *      A buffer cannot be placed on two lists at the same time.
1444  */
1445 static inline void __skb_queue_after(struct sk_buff_head *list,
1446                                      struct sk_buff *prev,
1447                                      struct sk_buff *newsk)
1448 {
1449         __skb_insert(newsk, prev, prev->next, list);
1450 }
1451 
1452 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1453                 struct sk_buff_head *list);
1454 
1455 static inline void __skb_queue_before(struct sk_buff_head *list,
1456                                       struct sk_buff *next,
1457                                       struct sk_buff *newsk)
1458 {
1459         __skb_insert(newsk, next->prev, next, list);
1460 }
1461 
1462 /**
1463  *      __skb_queue_head - queue a buffer at the list head
1464  *      @list: list to use
1465  *      @newsk: buffer to queue
1466  *
1467  *      Queue a buffer at the start of a list. This function takes no locks
1468  *      and you must therefore hold required locks before calling it.
1469  *
1470  *      A buffer cannot be placed on two lists at the same time.
1471  */
1472 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1473 static inline void __skb_queue_head(struct sk_buff_head *list,
1474                                     struct sk_buff *newsk)
1475 {
1476         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1477 }
1478 
1479 /**
1480  *      __skb_queue_tail - queue a buffer at the list tail
1481  *      @list: list to use
1482  *      @newsk: buffer to queue
1483  *
1484  *      Queue a buffer at the end of a list. This function takes no locks
1485  *      and you must therefore hold required locks before calling it.
1486  *
1487  *      A buffer cannot be placed on two lists at the same time.
1488  */
1489 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1490 static inline void __skb_queue_tail(struct sk_buff_head *list,
1491                                    struct sk_buff *newsk)
1492 {
1493         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1494 }
1495 
1496 /*
1497  * remove sk_buff from list. _Must_ be called atomically, and with
1498  * the list known..
1499  */
1500 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1501 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1502 {
1503         struct sk_buff *next, *prev;
1504 
1505         list->qlen--;
1506         next       = skb->next;
1507         prev       = skb->prev;
1508         skb->next  = skb->prev = NULL;
1509         next->prev = prev;
1510         prev->next = next;
1511 }
1512 
1513 /**
1514  *      __skb_dequeue - remove from the head of the queue
1515  *      @list: list to dequeue from
1516  *
1517  *      Remove the head of the list. This function does not take any locks
1518  *      so must be used with appropriate locks held only. The head item is
1519  *      returned or %NULL if the list is empty.
1520  */
1521 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1522 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1523 {
1524         struct sk_buff *skb = skb_peek(list);
1525         if (skb)
1526                 __skb_unlink(skb, list);
1527         return skb;
1528 }
1529 
1530 /**
1531  *      __skb_dequeue_tail - remove from the tail of the queue
1532  *      @list: list to dequeue from
1533  *
1534  *      Remove the tail of the list. This function does not take any locks
1535  *      so must be used with appropriate locks held only. The tail item is
1536  *      returned or %NULL if the list is empty.
1537  */
1538 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1539 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1540 {
1541         struct sk_buff *skb = skb_peek_tail(list);
1542         if (skb)
1543                 __skb_unlink(skb, list);
1544         return skb;
1545 }
1546 
1547 
1548 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1549 {
1550         return skb->data_len;
1551 }
1552 
1553 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1554 {
1555         return skb->len - skb->data_len;
1556 }
1557 
1558 static inline int skb_pagelen(const struct sk_buff *skb)
1559 {
1560         int i, len = 0;
1561 
1562         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1563                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1564         return len + skb_headlen(skb);
1565 }
1566 
1567 /**
1568  * __skb_fill_page_desc - initialise a paged fragment in an skb
1569  * @skb: buffer containing fragment to be initialised
1570  * @i: paged fragment index to initialise
1571  * @page: the page to use for this fragment
1572  * @off: the offset to the data with @page
1573  * @size: the length of the data
1574  *
1575  * Initialises the @i'th fragment of @skb to point to &size bytes at
1576  * offset @off within @page.
1577  *
1578  * Does not take any additional reference on the fragment.
1579  */
1580 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1581                                         struct page *page, int off, int size)
1582 {
1583         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1584 
1585         /*
1586          * Propagate page->pfmemalloc to the skb if we can. The problem is
1587          * that not all callers have unique ownership of the page. If
1588          * pfmemalloc is set, we check the mapping as a mapping implies
1589          * page->index is set (index and pfmemalloc share space).
1590          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1591          * do not lose pfmemalloc information as the pages would not be
1592          * allocated using __GFP_MEMALLOC.
1593          */
1594         frag->page.p              = page;
1595         frag->page_offset         = off;
1596         skb_frag_size_set(frag, size);
1597 
1598         page = compound_head(page);
1599         if (page->pfmemalloc && !page->mapping)
1600                 skb->pfmemalloc = true;
1601 }
1602 
1603 /**
1604  * skb_fill_page_desc - initialise a paged fragment in an skb
1605  * @skb: buffer containing fragment to be initialised
1606  * @i: paged fragment index to initialise
1607  * @page: the page to use for this fragment
1608  * @off: the offset to the data with @page
1609  * @size: the length of the data
1610  *
1611  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1612  * @skb to point to @size bytes at offset @off within @page. In
1613  * addition updates @skb such that @i is the last fragment.
1614  *
1615  * Does not take any additional reference on the fragment.
1616  */
1617 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1618                                       struct page *page, int off, int size)
1619 {
1620         __skb_fill_page_desc(skb, i, page, off, size);
1621         skb_shinfo(skb)->nr_frags = i + 1;
1622 }
1623 
1624 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1625                      int size, unsigned int truesize);
1626 
1627 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1628                           unsigned int truesize);
1629 
1630 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1631 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1632 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1633 
1634 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1635 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1636 {
1637         return skb->head + skb->tail;
1638 }
1639 
1640 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1641 {
1642         skb->tail = skb->data - skb->head;
1643 }
1644 
1645 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1646 {
1647         skb_reset_tail_pointer(skb);
1648         skb->tail += offset;
1649 }
1650 
1651 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1652 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1653 {
1654         return skb->tail;
1655 }
1656 
1657 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1658 {
1659         skb->tail = skb->data;
1660 }
1661 
1662 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1663 {
1664         skb->tail = skb->data + offset;
1665 }
1666 
1667 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1668 
1669 /*
1670  *      Add data to an sk_buff
1671  */
1672 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1673 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1674 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1675 {
1676         unsigned char *tmp = skb_tail_pointer(skb);
1677         SKB_LINEAR_ASSERT(skb);
1678         skb->tail += len;
1679         skb->len  += len;
1680         return tmp;
1681 }
1682 
1683 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1684 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1685 {
1686         skb->data -= len;
1687         skb->len  += len;
1688         return skb->data;
1689 }
1690 
1691 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1692 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1693 {
1694         skb->len -= len;
1695         BUG_ON(skb->len < skb->data_len);
1696         return skb->data += len;
1697 }
1698 
1699 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1700 {
1701         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1702 }
1703 
1704 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1705 
1706 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1707 {
1708         if (len > skb_headlen(skb) &&
1709             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1710                 return NULL;
1711         skb->len -= len;
1712         return skb->data += len;
1713 }
1714 
1715 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1716 {
1717         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1718 }
1719 
1720 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1721 {
1722         if (likely(len <= skb_headlen(skb)))
1723                 return 1;
1724         if (unlikely(len > skb->len))
1725                 return 0;
1726         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1727 }
1728 
1729 /**
1730  *      skb_headroom - bytes at buffer head
1731  *      @skb: buffer to check
1732  *
1733  *      Return the number of bytes of free space at the head of an &sk_buff.
1734  */
1735 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1736 {
1737         return skb->data - skb->head;
1738 }
1739 
1740 /**
1741  *      skb_tailroom - bytes at buffer end
1742  *      @skb: buffer to check
1743  *
1744  *      Return the number of bytes of free space at the tail of an sk_buff
1745  */
1746 static inline int skb_tailroom(const struct sk_buff *skb)
1747 {
1748         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1749 }
1750 
1751 /**
1752  *      skb_availroom - bytes at buffer end
1753  *      @skb: buffer to check
1754  *
1755  *      Return the number of bytes of free space at the tail of an sk_buff
1756  *      allocated by sk_stream_alloc()
1757  */
1758 static inline int skb_availroom(const struct sk_buff *skb)
1759 {
1760         if (skb_is_nonlinear(skb))
1761                 return 0;
1762 
1763         return skb->end - skb->tail - skb->reserved_tailroom;
1764 }
1765 
1766 /**
1767  *      skb_reserve - adjust headroom
1768  *      @skb: buffer to alter
1769  *      @len: bytes to move
1770  *
1771  *      Increase the headroom of an empty &sk_buff by reducing the tail
1772  *      room. This is only allowed for an empty buffer.
1773  */
1774 static inline void skb_reserve(struct sk_buff *skb, int len)
1775 {
1776         skb->data += len;
1777         skb->tail += len;
1778 }
1779 
1780 #define ENCAP_TYPE_ETHER        0
1781 #define ENCAP_TYPE_IPPROTO      1
1782 
1783 static inline void skb_set_inner_protocol(struct sk_buff *skb,
1784                                           __be16 protocol)
1785 {
1786         skb->inner_protocol = protocol;
1787         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
1788 }
1789 
1790 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
1791                                          __u8 ipproto)
1792 {
1793         skb->inner_ipproto = ipproto;
1794         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
1795 }
1796 
1797 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1798 {
1799         skb->inner_mac_header = skb->mac_header;
1800         skb->inner_network_header = skb->network_header;
1801         skb->inner_transport_header = skb->transport_header;
1802 }
1803 
1804 static inline void skb_reset_mac_len(struct sk_buff *skb)
1805 {
1806         skb->mac_len = skb->network_header - skb->mac_header;
1807 }
1808 
1809 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1810                                                         *skb)
1811 {
1812         return skb->head + skb->inner_transport_header;
1813 }
1814 
1815 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1816 {
1817         skb->inner_transport_header = skb->data - skb->head;
1818 }
1819 
1820 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1821                                                    const int offset)
1822 {
1823         skb_reset_inner_transport_header(skb);
1824         skb->inner_transport_header += offset;
1825 }
1826 
1827 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1828 {
1829         return skb->head + skb->inner_network_header;
1830 }
1831 
1832 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1833 {
1834         skb->inner_network_header = skb->data - skb->head;
1835 }
1836 
1837 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1838                                                 const int offset)
1839 {
1840         skb_reset_inner_network_header(skb);
1841         skb->inner_network_header += offset;
1842 }
1843 
1844 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1845 {
1846         return skb->head + skb->inner_mac_header;
1847 }
1848 
1849 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1850 {
1851         skb->inner_mac_header = skb->data - skb->head;
1852 }
1853 
1854 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1855                                             const int offset)
1856 {
1857         skb_reset_inner_mac_header(skb);
1858         skb->inner_mac_header += offset;
1859 }
1860 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1861 {
1862         return skb->transport_header != (typeof(skb->transport_header))~0U;
1863 }
1864 
1865 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1866 {
1867         return skb->head + skb->transport_header;
1868 }
1869 
1870 static inline void skb_reset_transport_header(struct sk_buff *skb)
1871 {
1872         skb->transport_header = skb->data - skb->head;
1873 }
1874 
1875 static inline void skb_set_transport_header(struct sk_buff *skb,
1876                                             const int offset)
1877 {
1878         skb_reset_transport_header(skb);
1879         skb->transport_header += offset;
1880 }
1881 
1882 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1883 {
1884         return skb->head + skb->network_header;
1885 }
1886 
1887 static inline void skb_reset_network_header(struct sk_buff *skb)
1888 {
1889         skb->network_header = skb->data - skb->head;
1890 }
1891 
1892 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1893 {
1894         skb_reset_network_header(skb);
1895         skb->network_header += offset;
1896 }
1897 
1898 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1899 {
1900         return skb->head + skb->mac_header;
1901 }
1902 
1903 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1904 {
1905         return skb->mac_header != (typeof(skb->mac_header))~0U;
1906 }
1907 
1908 static inline void skb_reset_mac_header(struct sk_buff *skb)
1909 {
1910         skb->mac_header = skb->data - skb->head;
1911 }
1912 
1913 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1914 {
1915         skb_reset_mac_header(skb);
1916         skb->mac_header += offset;
1917 }
1918 
1919 static inline void skb_pop_mac_header(struct sk_buff *skb)
1920 {
1921         skb->mac_header = skb->network_header;
1922 }
1923 
1924 static inline void skb_probe_transport_header(struct sk_buff *skb,
1925                                               const int offset_hint)
1926 {
1927         struct flow_keys keys;
1928 
1929         if (skb_transport_header_was_set(skb))
1930                 return;
1931         else if (skb_flow_dissect(skb, &keys))
1932                 skb_set_transport_header(skb, keys.thoff);
1933         else
1934                 skb_set_transport_header(skb, offset_hint);
1935 }
1936 
1937 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1938 {
1939         if (skb_mac_header_was_set(skb)) {
1940                 const unsigned char *old_mac = skb_mac_header(skb);
1941 
1942                 skb_set_mac_header(skb, -skb->mac_len);
1943                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1944         }
1945 }
1946 
1947 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1948 {
1949         return skb->csum_start - skb_headroom(skb);
1950 }
1951 
1952 static inline int skb_transport_offset(const struct sk_buff *skb)
1953 {
1954         return skb_transport_header(skb) - skb->data;
1955 }
1956 
1957 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1958 {
1959         return skb->transport_header - skb->network_header;
1960 }
1961 
1962 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1963 {
1964         return skb->inner_transport_header - skb->inner_network_header;
1965 }
1966 
1967 static inline int skb_network_offset(const struct sk_buff *skb)
1968 {
1969         return skb_network_header(skb) - skb->data;
1970 }
1971 
1972 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1973 {
1974         return skb_inner_network_header(skb) - skb->data;
1975 }
1976 
1977 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1978 {
1979         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1980 }
1981 
1982 /*
1983  * CPUs often take a performance hit when accessing unaligned memory
1984  * locations. The actual performance hit varies, it can be small if the
1985  * hardware handles it or large if we have to take an exception and fix it
1986  * in software.
1987  *
1988  * Since an ethernet header is 14 bytes network drivers often end up with
1989  * the IP header at an unaligned offset. The IP header can be aligned by
1990  * shifting the start of the packet by 2 bytes. Drivers should do this
1991  * with:
1992  *
1993  * skb_reserve(skb, NET_IP_ALIGN);
1994  *
1995  * The downside to this alignment of the IP header is that the DMA is now
1996  * unaligned. On some architectures the cost of an unaligned DMA is high
1997  * and this cost outweighs the gains made by aligning the IP header.
1998  *
1999  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2000  * to be overridden.
2001  */
2002 #ifndef NET_IP_ALIGN
2003 #define NET_IP_ALIGN    2
2004 #endif
2005 
2006 /*
2007  * The networking layer reserves some headroom in skb data (via
2008  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2009  * the header has to grow. In the default case, if the header has to grow
2010  * 32 bytes or less we avoid the reallocation.
2011  *
2012  * Unfortunately this headroom changes the DMA alignment of the resulting
2013  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2014  * on some architectures. An architecture can override this value,
2015  * perhaps setting it to a cacheline in size (since that will maintain
2016  * cacheline alignment of the DMA). It must be a power of 2.
2017  *
2018  * Various parts of the networking layer expect at least 32 bytes of
2019  * headroom, you should not reduce this.
2020  *
2021  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2022  * to reduce average number of cache lines per packet.
2023  * get_rps_cpus() for example only access one 64 bytes aligned block :
2024  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2025  */
2026 #ifndef NET_SKB_PAD
2027 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2028 #endif
2029 
2030 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2031 
2032 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2033 {
2034         if (unlikely(skb_is_nonlinear(skb))) {
2035                 WARN_ON(1);
2036                 return;
2037         }
2038         skb->len = len;
2039         skb_set_tail_pointer(skb, len);
2040 }
2041 
2042 void skb_trim(struct sk_buff *skb, unsigned int len);
2043 
2044 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2045 {
2046         if (skb->data_len)
2047                 return ___pskb_trim(skb, len);
2048         __skb_trim(skb, len);
2049         return 0;
2050 }
2051 
2052 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2053 {
2054         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2055 }
2056 
2057 /**
2058  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2059  *      @skb: buffer to alter
2060  *      @len: new length
2061  *
2062  *      This is identical to pskb_trim except that the caller knows that
2063  *      the skb is not cloned so we should never get an error due to out-
2064  *      of-memory.
2065  */
2066 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2067 {
2068         int err = pskb_trim(skb, len);
2069         BUG_ON(err);
2070 }
2071 
2072 /**
2073  *      skb_orphan - orphan a buffer
2074  *      @skb: buffer to orphan
2075  *
2076  *      If a buffer currently has an owner then we call the owner's
2077  *      destructor function and make the @skb unowned. The buffer continues
2078  *      to exist but is no longer charged to its former owner.
2079  */
2080 static inline void skb_orphan(struct sk_buff *skb)
2081 {
2082         if (skb->destructor) {
2083                 skb->destructor(skb);
2084                 skb->destructor = NULL;
2085                 skb->sk         = NULL;
2086         } else {
2087                 BUG_ON(skb->sk);
2088         }
2089 }
2090 
2091 /**
2092  *      skb_orphan_frags - orphan the frags contained in a buffer
2093  *      @skb: buffer to orphan frags from
2094  *      @gfp_mask: allocation mask for replacement pages
2095  *
2096  *      For each frag in the SKB which needs a destructor (i.e. has an
2097  *      owner) create a copy of that frag and release the original
2098  *      page by calling the destructor.
2099  */
2100 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2101 {
2102         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2103                 return 0;
2104         return skb_copy_ubufs(skb, gfp_mask);
2105 }
2106 
2107 /**
2108  *      __skb_queue_purge - empty a list
2109  *      @list: list to empty
2110  *
2111  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2112  *      the list and one reference dropped. This function does not take the
2113  *      list lock and the caller must hold the relevant locks to use it.
2114  */
2115 void skb_queue_purge(struct sk_buff_head *list);
2116 static inline void __skb_queue_purge(struct sk_buff_head *list)
2117 {
2118         struct sk_buff *skb;
2119         while ((skb = __skb_dequeue(list)) != NULL)
2120                 kfree_skb(skb);
2121 }
2122 
2123 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
2124 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
2125 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
2126 
2127 void *netdev_alloc_frag(unsigned int fragsz);
2128 
2129 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2130                                    gfp_t gfp_mask);
2131 
2132 /**
2133  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2134  *      @dev: network device to receive on
2135  *      @length: length to allocate
2136  *
2137  *      Allocate a new &sk_buff and assign it a usage count of one. The
2138  *      buffer has unspecified headroom built in. Users should allocate
2139  *      the headroom they think they need without accounting for the
2140  *      built in space. The built in space is used for optimisations.
2141  *
2142  *      %NULL is returned if there is no free memory. Although this function
2143  *      allocates memory it can be called from an interrupt.
2144  */
2145 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2146                                                unsigned int length)
2147 {
2148         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2149 }
2150 
2151 /* legacy helper around __netdev_alloc_skb() */
2152 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2153                                               gfp_t gfp_mask)
2154 {
2155         return __netdev_alloc_skb(NULL, length, gfp_mask);
2156 }
2157 
2158 /* legacy helper around netdev_alloc_skb() */
2159 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2160 {
2161         return netdev_alloc_skb(NULL, length);
2162 }
2163 
2164 
2165 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2166                 unsigned int length, gfp_t gfp)
2167 {
2168         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2169 
2170         if (NET_IP_ALIGN && skb)
2171                 skb_reserve(skb, NET_IP_ALIGN);
2172         return skb;
2173 }
2174 
2175 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2176                 unsigned int length)
2177 {
2178         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2179 }
2180 
2181 /**
2182  *      __skb_alloc_pages - allocate pages for ps-rx on a skb and preserve pfmemalloc data
2183  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
2184  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
2185  *      @order: size of the allocation
2186  *
2187  *      Allocate a new page.
2188  *
2189  *      %NULL is returned if there is no free memory.
2190 */
2191 static inline struct page *__skb_alloc_pages(gfp_t gfp_mask,
2192                                               struct sk_buff *skb,
2193                                               unsigned int order)
2194 {
2195         struct page *page;
2196 
2197         gfp_mask |= __GFP_COLD;
2198 
2199         if (!(gfp_mask & __GFP_NOMEMALLOC))
2200                 gfp_mask |= __GFP_MEMALLOC;
2201 
2202         page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2203         if (skb && page && page->pfmemalloc)
2204                 skb->pfmemalloc = true;
2205 
2206         return page;
2207 }
2208 
2209 /**
2210  *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
2211  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
2212  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
2213  *
2214  *      Allocate a new page.
2215  *
2216  *      %NULL is returned if there is no free memory.
2217  */
2218 static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
2219                                              struct sk_buff *skb)
2220 {
2221         return __skb_alloc_pages(gfp_mask, skb, 0);
2222 }
2223 
2224 /**
2225  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2226  *      @page: The page that was allocated from skb_alloc_page
2227  *      @skb: The skb that may need pfmemalloc set
2228  */
2229 static inline void skb_propagate_pfmemalloc(struct page *page,
2230                                              struct sk_buff *skb)
2231 {
2232         if (page && page->pfmemalloc)
2233                 skb->pfmemalloc = true;
2234 }
2235 
2236 /**
2237  * skb_frag_page - retrieve the page referred to by a paged fragment
2238  * @frag: the paged fragment
2239  *
2240  * Returns the &struct page associated with @frag.
2241  */
2242 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2243 {
2244         return frag->page.p;
2245 }
2246 
2247 /**
2248  * __skb_frag_ref - take an addition reference on a paged fragment.
2249  * @frag: the paged fragment
2250  *
2251  * Takes an additional reference on the paged fragment @frag.
2252  */
2253 static inline void __skb_frag_ref(skb_frag_t *frag)
2254 {
2255         get_page(skb_frag_page(frag));
2256 }
2257 
2258 /**
2259  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2260  * @skb: the buffer
2261  * @f: the fragment offset.
2262  *
2263  * Takes an additional reference on the @f'th paged fragment of @skb.
2264  */
2265 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2266 {
2267         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2268 }
2269 
2270 /**
2271  * __skb_frag_unref - release a reference on a paged fragment.
2272  * @frag: the paged fragment
2273  *
2274  * Releases a reference on the paged fragment @frag.
2275  */
2276 static inline void __skb_frag_unref(skb_frag_t *frag)
2277 {
2278         put_page(skb_frag_page(frag));
2279 }
2280 
2281 /**
2282  * skb_frag_unref - release a reference on a paged fragment of an skb.
2283  * @skb: the buffer
2284  * @f: the fragment offset
2285  *
2286  * Releases a reference on the @f'th paged fragment of @skb.
2287  */
2288 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2289 {
2290         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2291 }
2292 
2293 /**
2294  * skb_frag_address - gets the address of the data contained in a paged fragment
2295  * @frag: the paged fragment buffer
2296  *
2297  * Returns the address of the data within @frag. The page must already
2298  * be mapped.
2299  */
2300 static inline void *skb_frag_address(const skb_frag_t *frag)
2301 {
2302         return page_address(skb_frag_page(frag)) + frag->page_offset;
2303 }
2304 
2305 /**
2306  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2307  * @frag: the paged fragment buffer
2308  *
2309  * Returns the address of the data within @frag. Checks that the page
2310  * is mapped and returns %NULL otherwise.
2311  */
2312 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2313 {
2314         void *ptr = page_address(skb_frag_page(frag));
2315         if (unlikely(!ptr))
2316                 return NULL;
2317 
2318         return ptr + frag->page_offset;
2319 }
2320 
2321 /**
2322  * __skb_frag_set_page - sets the page contained in a paged fragment
2323  * @frag: the paged fragment
2324  * @page: the page to set
2325  *
2326  * Sets the fragment @frag to contain @page.
2327  */
2328 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2329 {
2330         frag->page.p = page;
2331 }
2332 
2333 /**
2334  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2335  * @skb: the buffer
2336  * @f: the fragment offset
2337  * @page: the page to set
2338  *
2339  * Sets the @f'th fragment of @skb to contain @page.
2340  */
2341 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2342                                      struct page *page)
2343 {
2344         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2345 }
2346 
2347 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2348 
2349 /**
2350  * skb_frag_dma_map - maps a paged fragment via the DMA API
2351  * @dev: the device to map the fragment to
2352  * @frag: the paged fragment to map
2353  * @offset: the offset within the fragment (starting at the
2354  *          fragment's own offset)
2355  * @size: the number of bytes to map
2356  * @dir: the direction of the mapping (%PCI_DMA_*)
2357  *
2358  * Maps the page associated with @frag to @device.
2359  */
2360 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2361                                           const skb_frag_t *frag,
2362                                           size_t offset, size_t size,
2363                                           enum dma_data_direction dir)
2364 {
2365         return dma_map_page(dev, skb_frag_page(frag),
2366                             frag->page_offset + offset, size, dir);
2367 }
2368 
2369 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2370                                         gfp_t gfp_mask)
2371 {
2372         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2373 }
2374 
2375 
2376 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2377                                                   gfp_t gfp_mask)
2378 {
2379         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2380 }
2381 
2382 
2383 /**
2384  *      skb_clone_writable - is the header of a clone writable
2385  *      @skb: buffer to check
2386  *      @len: length up to which to write
2387  *
2388  *      Returns true if modifying the header part of the cloned buffer
2389  *      does not requires the data to be copied.
2390  */
2391 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2392 {
2393         return !skb_header_cloned(skb) &&
2394                skb_headroom(skb) + len <= skb->hdr_len;
2395 }
2396 
2397 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2398                             int cloned)
2399 {
2400         int delta = 0;
2401 
2402         if (headroom > skb_headroom(skb))
2403                 delta = headroom - skb_headroom(skb);
2404 
2405         if (delta || cloned)
2406                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2407                                         GFP_ATOMIC);
2408         return 0;
2409 }
2410 
2411 /**
2412  *      skb_cow - copy header of skb when it is required
2413  *      @skb: buffer to cow
2414  *      @headroom: needed headroom
2415  *
2416  *      If the skb passed lacks sufficient headroom or its data part
2417  *      is shared, data is reallocated. If reallocation fails, an error
2418  *      is returned and original skb is not changed.
2419  *
2420  *      The result is skb with writable area skb->head...skb->tail
2421  *      and at least @headroom of space at head.
2422  */
2423 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2424 {
2425         return __skb_cow(skb, headroom, skb_cloned(skb));
2426 }
2427 
2428 /**
2429  *      skb_cow_head - skb_cow but only making the head writable
2430  *      @skb: buffer to cow
2431  *      @headroom: needed headroom
2432  *
2433  *      This function is identical to skb_cow except that we replace the
2434  *      skb_cloned check by skb_header_cloned.  It should be used when
2435  *      you only need to push on some header and do not need to modify
2436  *      the data.
2437  */
2438 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2439 {
2440         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2441 }
2442 
2443 /**
2444  *      skb_padto       - pad an skbuff up to a minimal size
2445  *      @skb: buffer to pad
2446  *      @len: minimal length
2447  *
2448  *      Pads up a buffer to ensure the trailing bytes exist and are
2449  *      blanked. If the buffer already contains sufficient data it
2450  *      is untouched. Otherwise it is extended. Returns zero on
2451  *      success. The skb is freed on error.
2452  */
2453  
2454 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2455 {
2456         unsigned int size = skb->len;
2457         if (likely(size >= len))
2458                 return 0;
2459         return skb_pad(skb, len - size);
2460 }
2461 
2462 static inline int skb_add_data(struct sk_buff *skb,
2463                                char __user *from, int copy)
2464 {
2465         const int off = skb->len;
2466 
2467         if (skb->ip_summed == CHECKSUM_NONE) {
2468                 int err = 0;
2469                 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2470                                                             copy, 0, &err);
2471                 if (!err) {
2472                         skb->csum = csum_block_add(skb->csum, csum, off);
2473                         return 0;
2474                 }
2475         } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2476                 return 0;
2477 
2478         __skb_trim(skb, off);
2479         return -EFAULT;
2480 }
2481 
2482 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2483                                     const struct page *page, int off)
2484 {
2485         if (i) {
2486                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2487 
2488                 return page == skb_frag_page(frag) &&
2489                        off == frag->page_offset + skb_frag_size(frag);
2490         }
2491         return false;
2492 }
2493 
2494 static inline int __skb_linearize(struct sk_buff *skb)
2495 {
2496         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2497 }
2498 
2499 /**
2500  *      skb_linearize - convert paged skb to linear one
2501  *      @skb: buffer to linarize
2502  *
2503  *      If there is no free memory -ENOMEM is returned, otherwise zero
2504  *      is returned and the old skb data released.
2505  */
2506 static inline int skb_linearize(struct sk_buff *skb)
2507 {
2508         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2509 }
2510 
2511 /**
2512  * skb_has_shared_frag - can any frag be overwritten
2513  * @skb: buffer to test
2514  *
2515  * Return true if the skb has at least one frag that might be modified
2516  * by an external entity (as in vmsplice()/sendfile())
2517  */
2518 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2519 {
2520         return skb_is_nonlinear(skb) &&
2521                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2522 }
2523 
2524 /**
2525  *      skb_linearize_cow - make sure skb is linear and writable
2526  *      @skb: buffer to process
2527  *
2528  *      If there is no free memory -ENOMEM is returned, otherwise zero
2529  *      is returned and the old skb data released.
2530  */
2531 static inline int skb_linearize_cow(struct sk_buff *skb)
2532 {
2533         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2534                __skb_linearize(skb) : 0;
2535 }
2536 
2537 /**
2538  *      skb_postpull_rcsum - update checksum for received skb after pull
2539  *      @skb: buffer to update
2540  *      @start: start of data before pull
2541  *      @len: length of data pulled
2542  *
2543  *      After doing a pull on a received packet, you need to call this to
2544  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2545  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2546  */
2547 
2548 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2549                                       const void *start, unsigned int len)
2550 {
2551         if (skb->ip_summed == CHECKSUM_COMPLETE)
2552                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2553         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2554                  skb_checksum_start_offset(skb) < 0)
2555                 skb->ip_summed = CHECKSUM_NONE;
2556 }
2557 
2558 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2559 
2560 /**
2561  *      pskb_trim_rcsum - trim received skb and update checksum
2562  *      @skb: buffer to trim
2563  *      @len: new length
2564  *
2565  *      This is exactly the same as pskb_trim except that it ensures the
2566  *      checksum of received packets are still valid after the operation.
2567  */
2568 
2569 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2570 {
2571         if (likely(len >= skb->len))
2572                 return 0;
2573         if (skb->ip_summed == CHECKSUM_COMPLETE)
2574                 skb->ip_summed = CHECKSUM_NONE;
2575         return __pskb_trim(skb, len);
2576 }
2577 
2578 #define skb_queue_walk(queue, skb) \
2579                 for (skb = (queue)->next;                                       \
2580                      skb != (struct sk_buff *)(queue);                          \
2581                      skb = skb->next)
2582 
2583 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2584                 for (skb = (queue)->next, tmp = skb->next;                      \
2585                      skb != (struct sk_buff *)(queue);                          \
2586                      skb = tmp, tmp = skb->next)
2587 
2588 #define skb_queue_walk_from(queue, skb)                                         \
2589                 for (; skb != (struct sk_buff *)(queue);                        \
2590                      skb = skb->next)
2591 
2592 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2593                 for (tmp = skb->next;                                           \
2594                      skb != (struct sk_buff *)(queue);                          \
2595                      skb = tmp, tmp = skb->next)
2596 
2597 #define skb_queue_reverse_walk(queue, skb) \
2598                 for (skb = (queue)->prev;                                       \
2599                      skb != (struct sk_buff *)(queue);                          \
2600                      skb = skb->prev)
2601 
2602 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2603                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2604                      skb != (struct sk_buff *)(queue);                          \
2605                      skb = tmp, tmp = skb->prev)
2606 
2607 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2608                 for (tmp = skb->prev;                                           \
2609                      skb != (struct sk_buff *)(queue);                          \
2610                      skb = tmp, tmp = skb->prev)
2611 
2612 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2613 {
2614         return skb_shinfo(skb)->frag_list != NULL;
2615 }
2616 
2617 static inline void skb_frag_list_init(struct sk_buff *skb)
2618 {
2619         skb_shinfo(skb)->frag_list = NULL;
2620 }
2621 
2622 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2623 {
2624         frag->next = skb_shinfo(skb)->frag_list;
2625         skb_shinfo(skb)->frag_list = frag;
2626 }
2627 
2628 #define skb_walk_frags(skb, iter)       \
2629         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2630 
2631 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2632                                     int *peeked, int *off, int *err);
2633 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2634                                   int *err);
2635 unsigned int datagram_poll(struct file *file, struct socket *sock,
2636                            struct poll_table_struct *wait);
2637 int skb_copy_datagram_iovec(const struct sk_buff *from, int offset,
2638                             struct iovec *to, int size);
2639 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, int hlen,
2640                                      struct iovec *iov);
2641 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
2642                                  const struct iovec *from, int from_offset,
2643                                  int len);
2644 int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
2645                            int offset, size_t count);
2646 int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset,
2647                                   const struct iovec *to, int to_offset,
2648                                   int size);
2649 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2650 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2651 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2652 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2653 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2654 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2655                               int len, __wsum csum);
2656 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
2657                     struct pipe_inode_info *pipe, unsigned int len,
2658                     unsigned int flags);
2659 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2660 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
2661 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
2662                  int len, int hlen);
2663 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2664 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2665 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2666 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2667 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2668 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
2669 
2670 struct skb_checksum_ops {
2671         __wsum (*update)(const void *mem, int len, __wsum wsum);
2672         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2673 };
2674 
2675 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2676                       __wsum csum, const struct skb_checksum_ops *ops);
2677 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2678                     __wsum csum);
2679 
2680 static inline void *__skb_header_pointer(const struct sk_buff *skb, int offset,
2681                                          int len, void *data, int hlen, void *buffer)
2682 {
2683         if (hlen - offset >= len)
2684                 return data + offset;
2685 
2686         if (!skb ||
2687             skb_copy_bits(skb, offset, buffer, len) < 0)
2688                 return NULL;
2689 
2690         return buffer;
2691 }
2692 
2693 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2694                                        int len, void *buffer)
2695 {
2696         return __skb_header_pointer(skb, offset, len, skb->data,
2697                                     skb_headlen(skb), buffer);
2698 }
2699 
2700 /**
2701  *      skb_needs_linearize - check if we need to linearize a given skb
2702  *                            depending on the given device features.
2703  *      @skb: socket buffer to check
2704  *      @features: net device features
2705  *
2706  *      Returns true if either:
2707  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
2708  *      2. skb is fragmented and the device does not support SG.
2709  */
2710 static inline bool skb_needs_linearize(struct sk_buff *skb,
2711                                        netdev_features_t features)
2712 {
2713         return skb_is_nonlinear(skb) &&
2714                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
2715                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
2716 }
2717 
2718 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2719                                              void *to,
2720                                              const unsigned int len)
2721 {
2722         memcpy(to, skb->data, len);
2723 }
2724 
2725 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2726                                                     const int offset, void *to,
2727                                                     const unsigned int len)
2728 {
2729         memcpy(to, skb->data + offset, len);
2730 }
2731 
2732 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2733                                            const void *from,
2734                                            const unsigned int len)
2735 {
2736         memcpy(skb->data, from, len);
2737 }
2738 
2739 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2740                                                   const int offset,
2741                                                   const void *from,
2742                                                   const unsigned int len)
2743 {
2744         memcpy(skb->data + offset, from, len);
2745 }
2746 
2747 void skb_init(void);
2748 
2749 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2750 {
2751         return skb->tstamp;
2752 }
2753 
2754 /**
2755  *      skb_get_timestamp - get timestamp from a skb
2756  *      @skb: skb to get stamp from
2757  *      @stamp: pointer to struct timeval to store stamp in
2758  *
2759  *      Timestamps are stored in the skb as offsets to a base timestamp.
2760  *      This function converts the offset back to a struct timeval and stores
2761  *      it in stamp.
2762  */
2763 static inline void skb_get_timestamp(const struct sk_buff *skb,
2764                                      struct timeval *stamp)
2765 {
2766         *stamp = ktime_to_timeval(skb->tstamp);
2767 }
2768 
2769 static inline void skb_get_timestampns(const struct sk_buff *skb,
2770                                        struct timespec *stamp)
2771 {
2772         *stamp = ktime_to_timespec(skb->tstamp);
2773 }
2774 
2775 static inline void __net_timestamp(struct sk_buff *skb)
2776 {
2777         skb->tstamp = ktime_get_real();
2778 }
2779 
2780 static inline ktime_t net_timedelta(ktime_t t)
2781 {
2782         return ktime_sub(ktime_get_real(), t);
2783 }
2784 
2785 static inline ktime_t net_invalid_timestamp(void)
2786 {
2787         return ktime_set(0, 0);
2788 }
2789 
2790 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
2791 
2792 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2793 
2794 void skb_clone_tx_timestamp(struct sk_buff *skb);
2795 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2796 
2797 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2798 
2799 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2800 {
2801 }
2802 
2803 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2804 {
2805         return false;
2806 }
2807 
2808 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2809 
2810 /**
2811  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2812  *
2813  * PHY drivers may accept clones of transmitted packets for
2814  * timestamping via their phy_driver.txtstamp method. These drivers
2815  * must call this function to return the skb back to the stack, with
2816  * or without a timestamp.
2817  *
2818  * @skb: clone of the the original outgoing packet
2819  * @hwtstamps: hardware time stamps, may be NULL if not available
2820  *
2821  */
2822 void skb_complete_tx_timestamp(struct sk_buff *skb,
2823                                struct skb_shared_hwtstamps *hwtstamps);
2824 
2825 void __skb_tstamp_tx(struct sk_buff *orig_skb,
2826                      struct skb_shared_hwtstamps *hwtstamps,
2827                      struct sock *sk, int tstype);
2828 
2829 /**
2830  * skb_tstamp_tx - queue clone of skb with send time stamps
2831  * @orig_skb:   the original outgoing packet
2832  * @hwtstamps:  hardware time stamps, may be NULL if not available
2833  *
2834  * If the skb has a socket associated, then this function clones the
2835  * skb (thus sharing the actual data and optional structures), stores
2836  * the optional hardware time stamping information (if non NULL) or
2837  * generates a software time stamp (otherwise), then queues the clone
2838  * to the error queue of the socket.  Errors are silently ignored.
2839  */
2840 void skb_tstamp_tx(struct sk_buff *orig_skb,
2841                    struct skb_shared_hwtstamps *hwtstamps);
2842 
2843 static inline void sw_tx_timestamp(struct sk_buff *skb)
2844 {
2845         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2846             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2847                 skb_tstamp_tx(skb, NULL);
2848 }
2849 
2850 /**
2851  * skb_tx_timestamp() - Driver hook for transmit timestamping
2852  *
2853  * Ethernet MAC Drivers should call this function in their hard_xmit()
2854  * function immediately before giving the sk_buff to the MAC hardware.
2855  *
2856  * Specifically, one should make absolutely sure that this function is
2857  * called before TX completion of this packet can trigger.  Otherwise
2858  * the packet could potentially already be freed.
2859  *
2860  * @skb: A socket buffer.
2861  */
2862 static inline void skb_tx_timestamp(struct sk_buff *skb)
2863 {
2864         skb_clone_tx_timestamp(skb);
2865         sw_tx_timestamp(skb);
2866 }
2867 
2868 /**
2869  * skb_complete_wifi_ack - deliver skb with wifi status
2870  *
2871  * @skb: the original outgoing packet
2872  * @acked: ack status
2873  *
2874  */
2875 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2876 
2877 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2878 __sum16 __skb_checksum_complete(struct sk_buff *skb);
2879 
2880 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2881 {
2882         return ((skb->ip_summed & CHECKSUM_UNNECESSARY) || skb->csum_valid);
2883 }
2884 
2885 /**
2886  *      skb_checksum_complete - Calculate checksum of an entire packet
2887  *      @skb: packet to process
2888  *
2889  *      This function calculates the checksum over the entire packet plus
2890  *      the value of skb->csum.  The latter can be used to supply the
2891  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2892  *      checksum.
2893  *
2894  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2895  *      this function can be used to verify that checksum on received
2896  *      packets.  In that case the function should return zero if the
2897  *      checksum is correct.  In particular, this function will return zero
2898  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2899  *      hardware has already verified the correctness of the checksum.
2900  */
2901 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2902 {
2903         return skb_csum_unnecessary(skb) ?
2904                0 : __skb_checksum_complete(skb);
2905 }
2906 
2907 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
2908 {
2909         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
2910                 if (skb->csum_level == 0)
2911                         skb->ip_summed = CHECKSUM_NONE;
2912                 else
2913                         skb->csum_level--;
2914         }
2915 }
2916 
2917 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
2918 {
2919         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
2920                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
2921                         skb->csum_level++;
2922         } else if (skb->ip_summed == CHECKSUM_NONE) {
2923                 skb->ip_summed = CHECKSUM_UNNECESSARY;
2924                 skb->csum_level = 0;
2925         }
2926 }
2927 
2928 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
2929 {
2930         /* Mark current checksum as bad (typically called from GRO
2931          * path). In the case that ip_summed is CHECKSUM_NONE
2932          * this must be the first checksum encountered in the packet.
2933          * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
2934          * checksum after the last one validated. For UDP, a zero
2935          * checksum can not be marked as bad.
2936          */
2937 
2938         if (skb->ip_summed == CHECKSUM_NONE ||
2939             skb->ip_summed == CHECKSUM_UNNECESSARY)
2940                 skb->csum_bad = 1;
2941 }
2942 
2943 /* Check if we need to perform checksum complete validation.
2944  *
2945  * Returns true if checksum complete is needed, false otherwise
2946  * (either checksum is unnecessary or zero checksum is allowed).
2947  */
2948 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
2949                                                   bool zero_okay,
2950                                                   __sum16 check)
2951 {
2952         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
2953                 skb->csum_valid = 1;
2954                 __skb_decr_checksum_unnecessary(skb);
2955                 return false;
2956         }
2957 
2958         return true;
2959 }
2960 
2961 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
2962  * in checksum_init.
2963  */
2964 #define CHECKSUM_BREAK 76
2965 
2966 /* Unset checksum-complete
2967  *
2968  * Unset checksum complete can be done when packet is being modified
2969  * (uncompressed for instance) and checksum-complete value is
2970  * invalidated.
2971  */
2972 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
2973 {
2974         if (skb->ip_summed == CHECKSUM_COMPLETE)
2975                 skb->ip_summed = CHECKSUM_NONE;
2976 }
2977 
2978 /* Validate (init) checksum based on checksum complete.
2979  *
2980  * Return values:
2981  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
2982  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
2983  *      checksum is stored in skb->csum for use in __skb_checksum_complete
2984  *   non-zero: value of invalid checksum
2985  *
2986  */
2987 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
2988                                                        bool complete,
2989                                                        __wsum psum)
2990 {
2991         if (skb->ip_summed == CHECKSUM_COMPLETE) {
2992                 if (!csum_fold(csum_add(psum, skb->csum))) {
2993                         skb->csum_valid = 1;
2994                         return 0;
2995                 }
2996         } else if (skb->csum_bad) {
2997                 /* ip_summed == CHECKSUM_NONE in this case */
2998                 return 1;
2999         }
3000 
3001         skb->csum = psum;
3002 
3003         if (complete || skb->len <= CHECKSUM_BREAK) {
3004                 __sum16 csum;
3005 
3006                 csum = __skb_checksum_complete(skb);
3007                 skb->csum_valid = !csum;
3008                 return csum;
3009         }
3010 
3011         return 0;
3012 }
3013 
3014 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3015 {
3016         return 0;
3017 }
3018 
3019 /* Perform checksum validate (init). Note that this is a macro since we only
3020  * want to calculate the pseudo header which is an input function if necessary.
3021  * First we try to validate without any computation (checksum unnecessary) and
3022  * then calculate based on checksum complete calling the function to compute
3023  * pseudo header.
3024  *
3025  * Return values:
3026  *   0: checksum is validated or try to in skb_checksum_complete
3027  *   non-zero: value of invalid checksum
3028  */
3029 #define __skb_checksum_validate(skb, proto, complete,                   \
3030                                 zero_okay, check, compute_pseudo)       \
3031 ({                                                                      \
3032         __sum16 __ret = 0;                                              \
3033         skb->csum_valid = 0;                                            \
3034         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3035                 __ret = __skb_checksum_validate_complete(skb,           \
3036                                 complete, compute_pseudo(skb, proto));  \
3037         __ret;                                                          \
3038 })
3039 
3040 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3041         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3042 
3043 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3044         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3045 
3046 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3047         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3048 
3049 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3050                                          compute_pseudo)                \
3051         __skb_checksum_validate_(skb, proto, true, true, check, compute_pseudo)
3052 
3053 #define skb_checksum_simple_validate(skb)                               \
3054         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3055 
3056 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3057 {
3058         return (skb->ip_summed == CHECKSUM_NONE &&
3059                 skb->csum_valid && !skb->csum_bad);
3060 }
3061 
3062 static inline void __skb_checksum_convert(struct sk_buff *skb,
3063                                           __sum16 check, __wsum pseudo)
3064 {
3065         skb->csum = ~pseudo;
3066         skb->ip_summed = CHECKSUM_COMPLETE;
3067 }
3068 
3069 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3070 do {                                                                    \
3071         if (__skb_checksum_convert_check(skb))                          \
3072                 __skb_checksum_convert(skb, check,                      \
3073                                        compute_pseudo(skb, proto));     \
3074 } while (0)
3075 
3076 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3077 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3078 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3079 {
3080         if (nfct && atomic_dec_and_test(&nfct->use))
3081                 nf_conntrack_destroy(nfct);
3082 }
3083 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3084 {
3085         if (nfct)
3086                 atomic_inc(&nfct->use);
3087 }
3088 #endif
3089 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3090 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3091 {
3092         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3093                 kfree(nf_bridge);
3094 }
3095 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3096 {
3097         if (nf_bridge)
3098                 atomic_inc(&nf_bridge->use);
3099 }
3100 #endif /* CONFIG_BRIDGE_NETFILTER */
3101 static inline void nf_reset(struct sk_buff *skb)
3102 {
3103 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3104         nf_conntrack_put(skb->nfct);
3105         skb->nfct = NULL;
3106 #endif
3107 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3108         nf_bridge_put(skb->nf_bridge);
3109         skb->nf_bridge = NULL;
3110 #endif
3111 }
3112 
3113 static inline void nf_reset_trace(struct sk_buff *skb)
3114 {
3115 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3116         skb->nf_trace = 0;
3117 #endif
3118 }
3119 
3120 static inline void ipvs_reset(struct sk_buff *skb)
3121 {
3122 #if IS_ENABLED(CONFIG_IP_VS)
3123         skb->ipvs_property = 0;
3124 #endif
3125 }
3126 
3127 /* Note: This doesn't put any conntrack and bridge info in dst. */
3128 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3129                              bool copy)
3130 {
3131 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3132         dst->nfct = src->nfct;
3133         nf_conntrack_get(src->nfct);
3134         if (copy)
3135                 dst->nfctinfo = src->nfctinfo;
3136 #endif
3137 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3138         dst->nf_bridge  = src->nf_bridge;
3139         nf_bridge_get(src->nf_bridge);
3140 #endif
3141 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3142         if (copy)
3143                 dst->nf_trace = src->nf_trace;
3144 #endif
3145 }
3146 
3147 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3148 {
3149 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3150         nf_conntrack_put(dst->nfct);
3151 #endif
3152 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3153         nf_bridge_put(dst->nf_bridge);
3154 #endif
3155         __nf_copy(dst, src, true);
3156 }
3157 
3158 #ifdef CONFIG_NETWORK_SECMARK
3159 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3160 {
3161         to->secmark = from->secmark;
3162 }
3163 
3164 static inline void skb_init_secmark(struct sk_buff *skb)
3165 {
3166         skb->secmark = 0;
3167 }
3168 #else
3169 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3170 { }
3171 
3172 static inline void skb_init_secmark(struct sk_buff *skb)
3173 { }
3174 #endif
3175 
3176 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3177 {
3178         return !skb->destructor &&
3179 #if IS_ENABLED(CONFIG_XFRM)
3180                 !skb->sp &&
3181 #endif
3182 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3183                 !skb->nfct &&
3184 #endif
3185                 !skb->_skb_refdst &&
3186                 !skb_has_frag_list(skb);
3187 }
3188 
3189 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3190 {
3191         skb->queue_mapping = queue_mapping;
3192 }
3193 
3194 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3195 {
3196         return skb->queue_mapping;
3197 }
3198 
3199 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3200 {
3201         to->queue_mapping = from->queue_mapping;
3202 }
3203 
3204 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3205 {
3206         skb->queue_mapping = rx_queue + 1;
3207 }
3208 
3209 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3210 {
3211         return skb->queue_mapping - 1;
3212 }
3213 
3214 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3215 {
3216         return skb->queue_mapping != 0;
3217 }
3218 
3219 u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
3220                   unsigned int num_tx_queues);
3221 
3222 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3223 {
3224 #ifdef CONFIG_XFRM
3225         return skb->sp;
3226 #else
3227         return NULL;
3228 #endif
3229 }
3230 
3231 /* Keeps track of mac header offset relative to skb->head.
3232  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3233  * For non-tunnel skb it points to skb_mac_header() and for
3234  * tunnel skb it points to outer mac header.
3235  * Keeps track of level of encapsulation of network headers.
3236  */
3237 struct skb_gso_cb {
3238         int     mac_offset;
3239         int     encap_level;
3240         __u16   csum_start;
3241 };
3242 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
3243 
3244 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3245 {
3246         return (skb_mac_header(inner_skb) - inner_skb->head) -
3247                 SKB_GSO_CB(inner_skb)->mac_offset;
3248 }
3249 
3250 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3251 {
3252         int new_headroom, headroom;
3253         int ret;
3254 
3255         headroom = skb_headroom(skb);
3256         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3257         if (ret)
3258                 return ret;
3259 
3260         new_headroom = skb_headroom(skb);
3261         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3262         return 0;
3263 }
3264 
3265 /* Compute the checksum for a gso segment. First compute the checksum value
3266  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3267  * then add in skb->csum (checksum from csum_start to end of packet).
3268  * skb->csum and csum_start are then updated to reflect the checksum of the
3269  * resultant packet starting from the transport header-- the resultant checksum
3270  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3271  * header.
3272  */
3273 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3274 {
3275         int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
3276             skb_transport_offset(skb);
3277         __u16 csum;
3278 
3279         csum = csum_fold(csum_partial(skb_transport_header(skb),
3280                                       plen, skb->csum));
3281         skb->csum = res;
3282         SKB_GSO_CB(skb)->csum_start -= plen;
3283 
3284         return csum;
3285 }
3286 
3287 static inline bool skb_is_gso(const struct sk_buff *skb)
3288 {
3289         return skb_shinfo(skb)->gso_size;
3290 }
3291 
3292 /* Note: Should be called only if skb_is_gso(skb) is true */
3293 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3294 {
3295         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3296 }
3297 
3298 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3299 
3300 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3301 {
3302         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3303          * wanted then gso_type will be set. */
3304         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3305 
3306         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3307             unlikely(shinfo->gso_type == 0)) {
3308                 __skb_warn_lro_forwarding(skb);
3309                 return true;
3310         }
3311         return false;
3312 }
3313 
3314 static inline void skb_forward_csum(struct sk_buff *skb)
3315 {
3316         /* Unfortunately we don't support this one.  Any brave souls? */
3317         if (skb->ip_summed == CHECKSUM_COMPLETE)
3318                 skb->ip_summed = CHECKSUM_NONE;
3319 }
3320 
3321 /**
3322  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3323  * @skb: skb to check
3324  *
3325  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3326  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3327  * use this helper, to document places where we make this assertion.
3328  */
3329 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3330 {
3331 #ifdef DEBUG
3332         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3333 #endif
3334 }
3335 
3336 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3337 
3338 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3339 
3340 u32 skb_get_poff(const struct sk_buff *skb);
3341 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
3342                    const struct flow_keys *keys, int hlen);
3343 
3344 /**
3345  * skb_head_is_locked - Determine if the skb->head is locked down
3346  * @skb: skb to check
3347  *
3348  * The head on skbs build around a head frag can be removed if they are
3349  * not cloned.  This function returns true if the skb head is locked down
3350  * due to either being allocated via kmalloc, or by being a clone with
3351  * multiple references to the head.
3352  */
3353 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3354 {
3355         return !skb->head_frag || skb_cloned(skb);
3356 }
3357 
3358 /**
3359  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3360  *
3361  * @skb: GSO skb
3362  *
3363  * skb_gso_network_seglen is used to determine the real size of the
3364  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3365  *
3366  * The MAC/L2 header is not accounted for.
3367  */
3368 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3369 {
3370         unsigned int hdr_len = skb_transport_header(skb) -
3371                                skb_network_header(skb);
3372         return hdr_len + skb_gso_transport_seglen(skb);
3373 }
3374 #endif  /* __KERNEL__ */
3375 #endif  /* _LINUX_SKBUFF_H */
3376 

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