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Linux/include/linux/skbuff.h

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

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