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

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  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 #include <linux/rbtree.h>
 24 #include <linux/socket.h>
 25 
 26 #include <linux/atomic.h>
 27 #include <asm/types.h>
 28 #include <linux/spinlock.h>
 29 #include <linux/net.h>
 30 #include <linux/textsearch.h>
 31 #include <net/checksum.h>
 32 #include <linux/rcupdate.h>
 33 #include <linux/hrtimer.h>
 34 #include <linux/dma-mapping.h>
 35 #include <linux/netdev_features.h>
 36 #include <linux/sched.h>
 37 #include <net/flow_keys.h>
 38 
 39 /* A. Checksumming of received packets by device.
 40  *
 41  * CHECKSUM_NONE:
 42  *
 43  *   Device failed to checksum this packet e.g. due to lack of capabilities.
 44  *   The packet contains full (though not verified) checksum in packet but
 45  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 46  *
 47  * CHECKSUM_UNNECESSARY:
 48  *
 49  *   The hardware you're dealing with doesn't calculate the full checksum
 50  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
 51  *   for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
 52  *   if their checksums are okay. skb->csum is still undefined in this case
 53  *   though. It is a bad option, but, unfortunately, nowadays most vendors do
 54  *   this. Apparently with the secret goal to sell you new devices, when you
 55  *   will add new protocol to your host, f.e. IPv6 8)
 56  *
 57  *   CHECKSUM_UNNECESSARY is applicable to following protocols:
 58  *     TCP: IPv6 and IPv4.
 59  *     UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
 60  *       zero UDP checksum for either IPv4 or IPv6, the networking stack
 61  *       may perform further validation in this case.
 62  *     GRE: only if the checksum is present in the header.
 63  *     SCTP: indicates the CRC in SCTP header has been validated.
 64  *
 65  *   skb->csum_level indicates the number of consecutive checksums found in
 66  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
 67  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
 68  *   and a device is able to verify the checksums for UDP (possibly zero),
 69  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
 70  *   two. If the device were only able to verify the UDP checksum and not
 71  *   GRE, either because it doesn't support GRE checksum of because GRE
 72  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
 73  *   not considered in this case).
 74  *
 75  * CHECKSUM_COMPLETE:
 76  *
 77  *   This is the most generic way. The device supplied checksum of the _whole_
 78  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
 79  *   hardware doesn't need to parse L3/L4 headers to implement this.
 80  *
 81  *   Note: Even if device supports only some protocols, but is able to produce
 82  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
 83  *
 84  * CHECKSUM_PARTIAL:
 85  *
 86  *   A checksum is set up to be offloaded to a device as described in the
 87  *   output description for CHECKSUM_PARTIAL. This may occur on a packet
 88  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
 89  *   on the same host, or it may be set in the input path in GRO or remote
 90  *   checksum offload. For the purposes of checksum verification, the checksum
 91  *   referred to by skb->csum_start + skb->csum_offset and any preceding
 92  *   checksums in the packet are considered verified. Any checksums in the
 93  *   packet that are after the checksum being offloaded are not considered to
 94  *   be verified.
 95  *
 96  * B. Checksumming on output.
 97  *
 98  * CHECKSUM_NONE:
 99  *
100  *   The skb was already checksummed by the protocol, or a checksum is not
101  *   required.
102  *
103  * CHECKSUM_PARTIAL:
104  *
105  *   The device is required to checksum the packet as seen by hard_start_xmit()
106  *   from skb->csum_start up to the end, and to record/write the checksum at
107  *   offset skb->csum_start + skb->csum_offset.
108  *
109  *   The device must show its capabilities in dev->features, set up at device
110  *   setup time, e.g. netdev_features.h:
111  *
112  *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
113  *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
114  *                        IPv4. Sigh. Vendors like this way for an unknown reason.
115  *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
116  *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
117  *      NETIF_F_...     - Well, you get the picture.
118  *
119  * CHECKSUM_UNNECESSARY:
120  *
121  *   Normally, the device will do per protocol specific checksumming. Protocol
122  *   implementations that do not want the NIC to perform the checksum
123  *   calculation should use this flag in their outgoing skbs.
124  *
125  *      NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
126  *                         offload. Correspondingly, the FCoE protocol driver
127  *                         stack should use CHECKSUM_UNNECESSARY.
128  *
129  * Any questions? No questions, good.           --ANK
130  */
131 
132 /* Don't change this without changing skb_csum_unnecessary! */
133 #define CHECKSUM_NONE           0
134 #define CHECKSUM_UNNECESSARY    1
135 #define CHECKSUM_COMPLETE       2
136 #define CHECKSUM_PARTIAL        3
137 
138 /* Maximum value in skb->csum_level */
139 #define SKB_MAX_CSUM_LEVEL      3
140 
141 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
142 #define SKB_WITH_OVERHEAD(X)    \
143         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
144 #define SKB_MAX_ORDER(X, ORDER) \
145         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
146 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
147 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
148 
149 /* return minimum truesize of one skb containing X bytes of data */
150 #define SKB_TRUESIZE(X) ((X) +                                          \
151                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
152                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
153 
154 struct net_device;
155 struct scatterlist;
156 struct pipe_inode_info;
157 struct iov_iter;
158 struct napi_struct;
159 
160 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
161 struct nf_conntrack {
162         atomic_t use;
163 };
164 #endif
165 
166 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
167 struct nf_bridge_info {
168         atomic_t                use;
169         enum {
170                 BRNF_PROTO_UNCHANGED,
171                 BRNF_PROTO_8021Q,
172                 BRNF_PROTO_PPPOE
173         } orig_proto;
174         bool                    pkt_otherhost;
175         unsigned int            mask;
176         struct net_device       *physindev;
177         struct net_device       *physoutdev;
178         char                    neigh_header[8];
179         __be32                  ipv4_daddr;
180 };
181 #endif
182 
183 struct sk_buff_head {
184         /* These two members must be first. */
185         struct sk_buff  *next;
186         struct sk_buff  *prev;
187 
188         __u32           qlen;
189         spinlock_t      lock;
190 };
191 
192 struct sk_buff;
193 
194 /* To allow 64K frame to be packed as single skb without frag_list we
195  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
196  * buffers which do not start on a page boundary.
197  *
198  * Since GRO uses frags we allocate at least 16 regardless of page
199  * size.
200  */
201 #if (65536/PAGE_SIZE + 1) < 16
202 #define MAX_SKB_FRAGS 16UL
203 #else
204 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
205 #endif
206 extern int sysctl_max_skb_frags;
207 
208 typedef struct skb_frag_struct skb_frag_t;
209 
210 struct skb_frag_struct {
211         struct {
212                 struct page *p;
213         } page;
214 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
215         __u32 page_offset;
216         __u32 size;
217 #else
218         __u16 page_offset;
219         __u16 size;
220 #endif
221 };
222 
223 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
224 {
225         return frag->size;
226 }
227 
228 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
229 {
230         frag->size = size;
231 }
232 
233 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
234 {
235         frag->size += delta;
236 }
237 
238 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
239 {
240         frag->size -= delta;
241 }
242 
243 #define HAVE_HW_TIME_STAMP
244 
245 /**
246  * struct skb_shared_hwtstamps - hardware time stamps
247  * @hwtstamp:   hardware time stamp transformed into duration
248  *              since arbitrary point in time
249  *
250  * Software time stamps generated by ktime_get_real() are stored in
251  * skb->tstamp.
252  *
253  * hwtstamps can only be compared against other hwtstamps from
254  * the same device.
255  *
256  * This structure is attached to packets as part of the
257  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
258  */
259 struct skb_shared_hwtstamps {
260         ktime_t hwtstamp;
261 };
262 
263 /* Definitions for tx_flags in struct skb_shared_info */
264 enum {
265         /* generate hardware time stamp */
266         SKBTX_HW_TSTAMP = 1 << 0,
267 
268         /* generate software time stamp when queueing packet to NIC */
269         SKBTX_SW_TSTAMP = 1 << 1,
270 
271         /* device driver is going to provide hardware time stamp */
272         SKBTX_IN_PROGRESS = 1 << 2,
273 
274         /* device driver supports TX zero-copy buffers */
275         SKBTX_DEV_ZEROCOPY = 1 << 3,
276 
277         /* generate wifi status information (where possible) */
278         SKBTX_WIFI_STATUS = 1 << 4,
279 
280         /* This indicates at least one fragment might be overwritten
281          * (as in vmsplice(), sendfile() ...)
282          * If we need to compute a TX checksum, we'll need to copy
283          * all frags to avoid possible bad checksum
284          */
285         SKBTX_SHARED_FRAG = 1 << 5,
286 
287         /* generate software time stamp when entering packet scheduling */
288         SKBTX_SCHED_TSTAMP = 1 << 6,
289 
290         /* generate software timestamp on peer data acknowledgment */
291         SKBTX_ACK_TSTAMP = 1 << 7,
292 };
293 
294 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
295                                  SKBTX_SCHED_TSTAMP | \
296                                  SKBTX_ACK_TSTAMP)
297 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
298 
299 /*
300  * The callback notifies userspace to release buffers when skb DMA is done in
301  * lower device, the skb last reference should be 0 when calling this.
302  * The zerocopy_success argument is true if zero copy transmit occurred,
303  * false on data copy or out of memory error caused by data copy attempt.
304  * The ctx field is used to track device context.
305  * The desc field is used to track userspace buffer index.
306  */
307 struct ubuf_info {
308         void (*callback)(struct ubuf_info *, bool zerocopy_success);
309         void *ctx;
310         unsigned long desc;
311 };
312 
313 /* This data is invariant across clones and lives at
314  * the end of the header data, ie. at skb->end.
315  */
316 struct skb_shared_info {
317         unsigned char   nr_frags;
318         __u8            tx_flags;
319         unsigned short  gso_size;
320         /* Warning: this field is not always filled in (UFO)! */
321         unsigned short  gso_segs;
322         unsigned short  gso_type;
323         struct sk_buff  *frag_list;
324         struct skb_shared_hwtstamps hwtstamps;
325         u32             tskey;
326         __be32          ip6_frag_id;
327 
328         /*
329          * Warning : all fields before dataref are cleared in __alloc_skb()
330          */
331         atomic_t        dataref;
332 
333         /* Intermediate layers must ensure that destructor_arg
334          * remains valid until skb destructor */
335         void *          destructor_arg;
336 
337         /* must be last field, see pskb_expand_head() */
338         skb_frag_t      frags[MAX_SKB_FRAGS];
339 };
340 
341 /* We divide dataref into two halves.  The higher 16 bits hold references
342  * to the payload part of skb->data.  The lower 16 bits hold references to
343  * the entire skb->data.  A clone of a headerless skb holds the length of
344  * the header in skb->hdr_len.
345  *
346  * All users must obey the rule that the skb->data reference count must be
347  * greater than or equal to the payload reference count.
348  *
349  * Holding a reference to the payload part means that the user does not
350  * care about modifications to the header part of skb->data.
351  */
352 #define SKB_DATAREF_SHIFT 16
353 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
354 
355 
356 enum {
357         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
358         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
359         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
360 };
361 
362 enum {
363         SKB_GSO_TCPV4 = 1 << 0,
364         SKB_GSO_UDP = 1 << 1,
365 
366         /* This indicates the skb is from an untrusted source. */
367         SKB_GSO_DODGY = 1 << 2,
368 
369         /* This indicates the tcp segment has CWR set. */
370         SKB_GSO_TCP_ECN = 1 << 3,
371 
372         SKB_GSO_TCPV6 = 1 << 4,
373 
374         SKB_GSO_FCOE = 1 << 5,
375 
376         SKB_GSO_GRE = 1 << 6,
377 
378         SKB_GSO_GRE_CSUM = 1 << 7,
379 
380         SKB_GSO_IPIP = 1 << 8,
381 
382         SKB_GSO_SIT = 1 << 9,
383 
384         SKB_GSO_UDP_TUNNEL = 1 << 10,
385 
386         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
387 
388         SKB_GSO_TUNNEL_REMCSUM = 1 << 12,
389 };
390 
391 #if BITS_PER_LONG > 32
392 #define NET_SKBUFF_DATA_USES_OFFSET 1
393 #endif
394 
395 #ifdef NET_SKBUFF_DATA_USES_OFFSET
396 typedef unsigned int sk_buff_data_t;
397 #else
398 typedef unsigned char *sk_buff_data_t;
399 #endif
400 
401 /**
402  * struct skb_mstamp - multi resolution time stamps
403  * @stamp_us: timestamp in us resolution
404  * @stamp_jiffies: timestamp in jiffies
405  */
406 struct skb_mstamp {
407         union {
408                 u64             v64;
409                 struct {
410                         u32     stamp_us;
411                         u32     stamp_jiffies;
412                 };
413         };
414 };
415 
416 /**
417  * skb_mstamp_get - get current timestamp
418  * @cl: place to store timestamps
419  */
420 static inline void skb_mstamp_get(struct skb_mstamp *cl)
421 {
422         u64 val = local_clock();
423 
424         do_div(val, NSEC_PER_USEC);
425         cl->stamp_us = (u32)val;
426         cl->stamp_jiffies = (u32)jiffies;
427 }
428 
429 /**
430  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
431  * @t1: pointer to newest sample
432  * @t0: pointer to oldest sample
433  */
434 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
435                                       const struct skb_mstamp *t0)
436 {
437         s32 delta_us = t1->stamp_us - t0->stamp_us;
438         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
439 
440         /* If delta_us is negative, this might be because interval is too big,
441          * or local_clock() drift is too big : fallback using jiffies.
442          */
443         if (delta_us <= 0 ||
444             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
445 
446                 delta_us = jiffies_to_usecs(delta_jiffies);
447 
448         return delta_us;
449 }
450 
451 
452 /** 
453  *      struct sk_buff - socket buffer
454  *      @next: Next buffer in list
455  *      @prev: Previous buffer in list
456  *      @tstamp: Time we arrived/left
457  *      @rbnode: RB tree node, alternative to next/prev for netem/tcp
458  *      @sk: Socket we are owned by
459  *      @dev: Device we arrived on/are leaving by
460  *      @cb: Control buffer. Free for use by every layer. Put private vars here
461  *      @_skb_refdst: destination entry (with norefcount bit)
462  *      @sp: the security path, used for xfrm
463  *      @len: Length of actual data
464  *      @data_len: Data length
465  *      @mac_len: Length of link layer header
466  *      @hdr_len: writable header length of cloned skb
467  *      @csum: Checksum (must include start/offset pair)
468  *      @csum_start: Offset from skb->head where checksumming should start
469  *      @csum_offset: Offset from csum_start where checksum should be stored
470  *      @priority: Packet queueing priority
471  *      @ignore_df: allow local fragmentation
472  *      @cloned: Head may be cloned (check refcnt to be sure)
473  *      @ip_summed: Driver fed us an IP checksum
474  *      @nohdr: Payload reference only, must not modify header
475  *      @nfctinfo: Relationship of this skb to the connection
476  *      @pkt_type: Packet class
477  *      @fclone: skbuff clone status
478  *      @ipvs_property: skbuff is owned by ipvs
479  *      @peeked: this packet has been seen already, so stats have been
480  *              done for it, don't do them again
481  *      @nf_trace: netfilter packet trace flag
482  *      @protocol: Packet protocol from driver
483  *      @destructor: Destruct function
484  *      @nfct: Associated connection, if any
485  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
486  *      @skb_iif: ifindex of device we arrived on
487  *      @tc_index: Traffic control index
488  *      @tc_verd: traffic control verdict
489  *      @hash: the packet hash
490  *      @queue_mapping: Queue mapping for multiqueue devices
491  *      @xmit_more: More SKBs are pending for this queue
492  *      @ndisc_nodetype: router type (from link layer)
493  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
494  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
495  *              ports.
496  *      @sw_hash: indicates hash was computed in software stack
497  *      @wifi_acked_valid: wifi_acked was set
498  *      @wifi_acked: whether frame was acked on wifi or not
499  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
500   *     @napi_id: id of the NAPI struct this skb came from
501  *      @secmark: security marking
502  *      @mark: Generic packet mark
503  *      @vlan_proto: vlan encapsulation protocol
504  *      @vlan_tci: vlan tag control information
505  *      @inner_protocol: Protocol (encapsulation)
506  *      @inner_transport_header: Inner transport layer header (encapsulation)
507  *      @inner_network_header: Network layer header (encapsulation)
508  *      @inner_mac_header: Link layer header (encapsulation)
509  *      @transport_header: Transport layer header
510  *      @network_header: Network layer header
511  *      @mac_header: Link layer header
512  *      @tail: Tail pointer
513  *      @end: End pointer
514  *      @head: Head of buffer
515  *      @data: Data head pointer
516  *      @truesize: Buffer size
517  *      @users: User count - see {datagram,tcp}.c
518  */
519 
520 struct sk_buff {
521         union {
522                 struct {
523                         /* These two members must be first. */
524                         struct sk_buff          *next;
525                         struct sk_buff          *prev;
526 
527                         union {
528                                 ktime_t         tstamp;
529                                 struct skb_mstamp skb_mstamp;
530                         };
531                 };
532                 struct rb_node  rbnode; /* used in netem & tcp stack */
533         };
534         struct sock             *sk;
535         struct net_device       *dev;
536 
537         /*
538          * This is the control buffer. It is free to use for every
539          * layer. Please put your private variables there. If you
540          * want to keep them across layers you have to do a skb_clone()
541          * first. This is owned by whoever has the skb queued ATM.
542          */
543         char                    cb[48] __aligned(8);
544 
545         unsigned long           _skb_refdst;
546         void                    (*destructor)(struct sk_buff *skb);
547 #ifdef CONFIG_XFRM
548         struct  sec_path        *sp;
549 #endif
550 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
551         struct nf_conntrack     *nfct;
552 #endif
553 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
554         struct nf_bridge_info   *nf_bridge;
555 #endif
556         unsigned int            len,
557                                 data_len;
558         __u16                   mac_len,
559                                 hdr_len;
560 
561         /* Following fields are _not_ copied in __copy_skb_header()
562          * Note that queue_mapping is here mostly to fill a hole.
563          */
564         kmemcheck_bitfield_begin(flags1);
565         __u16                   queue_mapping;
566         __u8                    cloned:1,
567                                 nohdr:1,
568                                 fclone:2,
569                                 peeked:1,
570                                 head_frag:1,
571                                 xmit_more:1;
572         /* one bit hole */
573         kmemcheck_bitfield_end(flags1);
574 
575         /* fields enclosed in headers_start/headers_end are copied
576          * using a single memcpy() in __copy_skb_header()
577          */
578         /* private: */
579         __u32                   headers_start[0];
580         /* public: */
581 
582 /* if you move pkt_type around you also must adapt those constants */
583 #ifdef __BIG_ENDIAN_BITFIELD
584 #define PKT_TYPE_MAX    (7 << 5)
585 #else
586 #define PKT_TYPE_MAX    7
587 #endif
588 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
589 
590         __u8                    __pkt_type_offset[0];
591         __u8                    pkt_type:3;
592         __u8                    pfmemalloc:1;
593         __u8                    ignore_df:1;
594         __u8                    nfctinfo:3;
595 
596         __u8                    nf_trace:1;
597         __u8                    ip_summed:2;
598         __u8                    ooo_okay:1;
599         __u8                    l4_hash:1;
600         __u8                    sw_hash:1;
601         __u8                    wifi_acked_valid:1;
602         __u8                    wifi_acked:1;
603 
604         __u8                    no_fcs:1;
605         /* Indicates the inner headers are valid in the skbuff. */
606         __u8                    encapsulation:1;
607         __u8                    encap_hdr_csum:1;
608         __u8                    csum_valid:1;
609         __u8                    csum_complete_sw:1;
610         __u8                    csum_level:2;
611         __u8                    csum_bad:1;
612 
613 #ifdef CONFIG_IPV6_NDISC_NODETYPE
614         __u8                    ndisc_nodetype:2;
615 #endif
616         __u8                    ipvs_property:1;
617         __u8                    inner_protocol_type:1;
618         __u8                    remcsum_offload:1;
619         /* 3 or 5 bit hole */
620 
621 #ifdef CONFIG_NET_SCHED
622         __u16                   tc_index;       /* traffic control index */
623 #ifdef CONFIG_NET_CLS_ACT
624         __u16                   tc_verd;        /* traffic control verdict */
625 #endif
626 #endif
627 
628         union {
629                 __wsum          csum;
630                 struct {
631                         __u16   csum_start;
632                         __u16   csum_offset;
633                 };
634         };
635         __u32                   priority;
636         int                     skb_iif;
637         __u32                   hash;
638         __be16                  vlan_proto;
639         __u16                   vlan_tci;
640 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
641         union {
642                 unsigned int    napi_id;
643                 unsigned int    sender_cpu;
644         };
645 #endif
646 #ifdef CONFIG_NETWORK_SECMARK
647         __u32                   secmark;
648 #endif
649         union {
650                 __u32           mark;
651                 __u32           reserved_tailroom;
652         };
653 
654         union {
655                 __be16          inner_protocol;
656                 __u8            inner_ipproto;
657         };
658 
659         __u16                   inner_transport_header;
660         __u16                   inner_network_header;
661         __u16                   inner_mac_header;
662 
663         __be16                  protocol;
664         __u16                   transport_header;
665         __u16                   network_header;
666         __u16                   mac_header;
667 
668         /* private: */
669         __u32                   headers_end[0];
670         /* public: */
671 
672         /* These elements must be at the end, see alloc_skb() for details.  */
673         sk_buff_data_t          tail;
674         sk_buff_data_t          end;
675         unsigned char           *head,
676                                 *data;
677         unsigned int            truesize;
678         atomic_t                users;
679 };
680 
681 #ifdef __KERNEL__
682 /*
683  *      Handling routines are only of interest to the kernel
684  */
685 #include <linux/slab.h>
686 
687 
688 #define SKB_ALLOC_FCLONE        0x01
689 #define SKB_ALLOC_RX            0x02
690 #define SKB_ALLOC_NAPI          0x04
691 
692 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
693 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
694 {
695         return unlikely(skb->pfmemalloc);
696 }
697 
698 /*
699  * skb might have a dst pointer attached, refcounted or not.
700  * _skb_refdst low order bit is set if refcount was _not_ taken
701  */
702 #define SKB_DST_NOREF   1UL
703 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
704 
705 /**
706  * skb_dst - returns skb dst_entry
707  * @skb: buffer
708  *
709  * Returns skb dst_entry, regardless of reference taken or not.
710  */
711 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
712 {
713         /* If refdst was not refcounted, check we still are in a 
714          * rcu_read_lock section
715          */
716         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
717                 !rcu_read_lock_held() &&
718                 !rcu_read_lock_bh_held());
719         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
720 }
721 
722 /**
723  * skb_dst_set - sets skb dst
724  * @skb: buffer
725  * @dst: dst entry
726  *
727  * Sets skb dst, assuming a reference was taken on dst and should
728  * be released by skb_dst_drop()
729  */
730 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
731 {
732         skb->_skb_refdst = (unsigned long)dst;
733 }
734 
735 /**
736  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
737  * @skb: buffer
738  * @dst: dst entry
739  *
740  * Sets skb dst, assuming a reference was not taken on dst.
741  * If dst entry is cached, we do not take reference and dst_release
742  * will be avoided by refdst_drop. If dst entry is not cached, we take
743  * reference, so that last dst_release can destroy the dst immediately.
744  */
745 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
746 {
747         WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
748         skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
749 }
750 
751 /**
752  * skb_dst_is_noref - Test if skb dst isn't refcounted
753  * @skb: buffer
754  */
755 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
756 {
757         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
758 }
759 
760 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
761 {
762         return (struct rtable *)skb_dst(skb);
763 }
764 
765 void kfree_skb(struct sk_buff *skb);
766 void kfree_skb_list(struct sk_buff *segs);
767 void skb_tx_error(struct sk_buff *skb);
768 void consume_skb(struct sk_buff *skb);
769 void  __kfree_skb(struct sk_buff *skb);
770 extern struct kmem_cache *skbuff_head_cache;
771 
772 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
773 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
774                       bool *fragstolen, int *delta_truesize);
775 
776 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
777                             int node);
778 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
779 struct sk_buff *build_skb(void *data, unsigned int frag_size);
780 static inline struct sk_buff *alloc_skb(unsigned int size,
781                                         gfp_t priority)
782 {
783         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
784 }
785 
786 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
787                                      unsigned long data_len,
788                                      int max_page_order,
789                                      int *errcode,
790                                      gfp_t gfp_mask);
791 
792 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
793 struct sk_buff_fclones {
794         struct sk_buff  skb1;
795 
796         struct sk_buff  skb2;
797 
798         atomic_t        fclone_ref;
799 };
800 
801 /**
802  *      skb_fclone_busy - check if fclone is busy
803  *      @skb: buffer
804  *
805  * Returns true is skb is a fast clone, and its clone is not freed.
806  * Some drivers call skb_orphan() in their ndo_start_xmit(),
807  * so we also check that this didnt happen.
808  */
809 static inline bool skb_fclone_busy(const struct sock *sk,
810                                    const struct sk_buff *skb)
811 {
812         const struct sk_buff_fclones *fclones;
813 
814         fclones = container_of(skb, struct sk_buff_fclones, skb1);
815 
816         return skb->fclone == SKB_FCLONE_ORIG &&
817                atomic_read(&fclones->fclone_ref) > 1 &&
818                fclones->skb2.sk == sk;
819 }
820 
821 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
822                                                gfp_t priority)
823 {
824         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
825 }
826 
827 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
828 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
829 {
830         return __alloc_skb_head(priority, -1);
831 }
832 
833 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
834 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
835 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
836 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
837 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
838                                    gfp_t gfp_mask, bool fclone);
839 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
840                                           gfp_t gfp_mask)
841 {
842         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
843 }
844 
845 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
846 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
847                                      unsigned int headroom);
848 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
849                                 int newtailroom, gfp_t priority);
850 int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
851                                      int offset, int len);
852 int __must_check skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg,
853                               int offset, int len);
854 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
855 int skb_pad(struct sk_buff *skb, int pad);
856 #define dev_kfree_skb(a)        consume_skb(a)
857 
858 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
859                             int getfrag(void *from, char *to, int offset,
860                                         int len, int odd, struct sk_buff *skb),
861                             void *from, int length);
862 
863 struct skb_seq_state {
864         __u32           lower_offset;
865         __u32           upper_offset;
866         __u32           frag_idx;
867         __u32           stepped_offset;
868         struct sk_buff  *root_skb;
869         struct sk_buff  *cur_skb;
870         __u8            *frag_data;
871 };
872 
873 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
874                           unsigned int to, struct skb_seq_state *st);
875 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
876                           struct skb_seq_state *st);
877 void skb_abort_seq_read(struct skb_seq_state *st);
878 
879 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
880                            unsigned int to, struct ts_config *config);
881 
882 /*
883  * Packet hash types specify the type of hash in skb_set_hash.
884  *
885  * Hash types refer to the protocol layer addresses which are used to
886  * construct a packet's hash. The hashes are used to differentiate or identify
887  * flows of the protocol layer for the hash type. Hash types are either
888  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
889  *
890  * Properties of hashes:
891  *
892  * 1) Two packets in different flows have different hash values
893  * 2) Two packets in the same flow should have the same hash value
894  *
895  * A hash at a higher layer is considered to be more specific. A driver should
896  * set the most specific hash possible.
897  *
898  * A driver cannot indicate a more specific hash than the layer at which a hash
899  * was computed. For instance an L3 hash cannot be set as an L4 hash.
900  *
901  * A driver may indicate a hash level which is less specific than the
902  * actual layer the hash was computed on. For instance, a hash computed
903  * at L4 may be considered an L3 hash. This should only be done if the
904  * driver can't unambiguously determine that the HW computed the hash at
905  * the higher layer. Note that the "should" in the second property above
906  * permits this.
907  */
908 enum pkt_hash_types {
909         PKT_HASH_TYPE_NONE,     /* Undefined type */
910         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
911         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
912         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
913 };
914 
915 static inline void
916 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
917 {
918         skb->l4_hash = (type == PKT_HASH_TYPE_L4);
919         skb->sw_hash = 0;
920         skb->hash = hash;
921 }
922 
923 void __skb_get_hash(struct sk_buff *skb);
924 static inline __u32 skb_get_hash(struct sk_buff *skb)
925 {
926         if (!skb->l4_hash && !skb->sw_hash)
927                 __skb_get_hash(skb);
928 
929         return skb->hash;
930 }
931 
932 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
933 {
934         return skb->hash;
935 }
936 
937 static inline void skb_clear_hash(struct sk_buff *skb)
938 {
939         skb->hash = 0;
940         skb->sw_hash = 0;
941         skb->l4_hash = 0;
942 }
943 
944 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
945 {
946         if (!skb->l4_hash)
947                 skb_clear_hash(skb);
948 }
949 
950 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
951 {
952         to->hash = from->hash;
953         to->sw_hash = from->sw_hash;
954         to->l4_hash = from->l4_hash;
955 };
956 
957 static inline void skb_sender_cpu_clear(struct sk_buff *skb)
958 {
959 #ifdef CONFIG_XPS
960         skb->sender_cpu = 0;
961 #endif
962 }
963 
964 #ifdef NET_SKBUFF_DATA_USES_OFFSET
965 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
966 {
967         return skb->head + skb->end;
968 }
969 
970 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
971 {
972         return skb->end;
973 }
974 #else
975 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
976 {
977         return skb->end;
978 }
979 
980 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
981 {
982         return skb->end - skb->head;
983 }
984 #endif
985 
986 /* Internal */
987 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
988 
989 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
990 {
991         return &skb_shinfo(skb)->hwtstamps;
992 }
993 
994 /**
995  *      skb_queue_empty - check if a queue is empty
996  *      @list: queue head
997  *
998  *      Returns true if the queue is empty, false otherwise.
999  */
1000 static inline int skb_queue_empty(const struct sk_buff_head *list)
1001 {
1002         return list->next == (const struct sk_buff *) list;
1003 }
1004 
1005 /**
1006  *      skb_queue_is_last - check if skb is the last entry in the queue
1007  *      @list: queue head
1008  *      @skb: buffer
1009  *
1010  *      Returns true if @skb is the last buffer on the list.
1011  */
1012 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1013                                      const struct sk_buff *skb)
1014 {
1015         return skb->next == (const struct sk_buff *) list;
1016 }
1017 
1018 /**
1019  *      skb_queue_is_first - check if skb is the first entry in the queue
1020  *      @list: queue head
1021  *      @skb: buffer
1022  *
1023  *      Returns true if @skb is the first buffer on the list.
1024  */
1025 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1026                                       const struct sk_buff *skb)
1027 {
1028         return skb->prev == (const struct sk_buff *) list;
1029 }
1030 
1031 /**
1032  *      skb_queue_next - return the next packet in the queue
1033  *      @list: queue head
1034  *      @skb: current buffer
1035  *
1036  *      Return the next packet in @list after @skb.  It is only valid to
1037  *      call this if skb_queue_is_last() evaluates to false.
1038  */
1039 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1040                                              const struct sk_buff *skb)
1041 {
1042         /* This BUG_ON may seem severe, but if we just return then we
1043          * are going to dereference garbage.
1044          */
1045         BUG_ON(skb_queue_is_last(list, skb));
1046         return skb->next;
1047 }
1048 
1049 /**
1050  *      skb_queue_prev - return the prev packet in the queue
1051  *      @list: queue head
1052  *      @skb: current buffer
1053  *
1054  *      Return the prev packet in @list before @skb.  It is only valid to
1055  *      call this if skb_queue_is_first() evaluates to false.
1056  */
1057 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1058                                              const struct sk_buff *skb)
1059 {
1060         /* This BUG_ON may seem severe, but if we just return then we
1061          * are going to dereference garbage.
1062          */
1063         BUG_ON(skb_queue_is_first(list, skb));
1064         return skb->prev;
1065 }
1066 
1067 /**
1068  *      skb_get - reference buffer
1069  *      @skb: buffer to reference
1070  *
1071  *      Makes another reference to a socket buffer and returns a pointer
1072  *      to the buffer.
1073  */
1074 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1075 {
1076         atomic_inc(&skb->users);
1077         return skb;
1078 }
1079 
1080 /*
1081  * If users == 1, we are the only owner and are can avoid redundant
1082  * atomic change.
1083  */
1084 
1085 /**
1086  *      skb_cloned - is the buffer a clone
1087  *      @skb: buffer to check
1088  *
1089  *      Returns true if the buffer was generated with skb_clone() and is
1090  *      one of multiple shared copies of the buffer. Cloned buffers are
1091  *      shared data so must not be written to under normal circumstances.
1092  */
1093 static inline int skb_cloned(const struct sk_buff *skb)
1094 {
1095         return skb->cloned &&
1096                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1097 }
1098 
1099 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1100 {
1101         might_sleep_if(pri & __GFP_WAIT);
1102 
1103         if (skb_cloned(skb))
1104                 return pskb_expand_head(skb, 0, 0, pri);
1105 
1106         return 0;
1107 }
1108 
1109 /**
1110  *      skb_header_cloned - is the header a clone
1111  *      @skb: buffer to check
1112  *
1113  *      Returns true if modifying the header part of the buffer requires
1114  *      the data to be copied.
1115  */
1116 static inline int skb_header_cloned(const struct sk_buff *skb)
1117 {
1118         int dataref;
1119 
1120         if (!skb->cloned)
1121                 return 0;
1122 
1123         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1124         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1125         return dataref != 1;
1126 }
1127 
1128 /**
1129  *      skb_header_release - release reference to header
1130  *      @skb: buffer to operate on
1131  *
1132  *      Drop a reference to the header part of the buffer.  This is done
1133  *      by acquiring a payload reference.  You must not read from the header
1134  *      part of skb->data after this.
1135  *      Note : Check if you can use __skb_header_release() instead.
1136  */
1137 static inline void skb_header_release(struct sk_buff *skb)
1138 {
1139         BUG_ON(skb->nohdr);
1140         skb->nohdr = 1;
1141         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1142 }
1143 
1144 /**
1145  *      __skb_header_release - release reference to header
1146  *      @skb: buffer to operate on
1147  *
1148  *      Variant of skb_header_release() assuming skb is private to caller.
1149  *      We can avoid one atomic operation.
1150  */
1151 static inline void __skb_header_release(struct sk_buff *skb)
1152 {
1153         skb->nohdr = 1;
1154         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1155 }
1156 
1157 
1158 /**
1159  *      skb_shared - is the buffer shared
1160  *      @skb: buffer to check
1161  *
1162  *      Returns true if more than one person has a reference to this
1163  *      buffer.
1164  */
1165 static inline int skb_shared(const struct sk_buff *skb)
1166 {
1167         return atomic_read(&skb->users) != 1;
1168 }
1169 
1170 /**
1171  *      skb_share_check - check if buffer is shared and if so clone it
1172  *      @skb: buffer to check
1173  *      @pri: priority for memory allocation
1174  *
1175  *      If the buffer is shared the buffer is cloned and the old copy
1176  *      drops a reference. A new clone with a single reference is returned.
1177  *      If the buffer is not shared the original buffer is returned. When
1178  *      being called from interrupt status or with spinlocks held pri must
1179  *      be GFP_ATOMIC.
1180  *
1181  *      NULL is returned on a memory allocation failure.
1182  */
1183 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1184 {
1185         might_sleep_if(pri & __GFP_WAIT);
1186         if (skb_shared(skb)) {
1187                 struct sk_buff *nskb = skb_clone(skb, pri);
1188 
1189                 if (likely(nskb))
1190                         consume_skb(skb);
1191                 else
1192                         kfree_skb(skb);
1193                 skb = nskb;
1194         }
1195         return skb;
1196 }
1197 
1198 /*
1199  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1200  *      packets to handle cases where we have a local reader and forward
1201  *      and a couple of other messy ones. The normal one is tcpdumping
1202  *      a packet thats being forwarded.
1203  */
1204 
1205 /**
1206  *      skb_unshare - make a copy of a shared buffer
1207  *      @skb: buffer to check
1208  *      @pri: priority for memory allocation
1209  *
1210  *      If the socket buffer is a clone then this function creates a new
1211  *      copy of the data, drops a reference count on the old copy and returns
1212  *      the new copy with the reference count at 1. If the buffer is not a clone
1213  *      the original buffer is returned. When called with a spinlock held or
1214  *      from interrupt state @pri must be %GFP_ATOMIC
1215  *
1216  *      %NULL is returned on a memory allocation failure.
1217  */
1218 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1219                                           gfp_t pri)
1220 {
1221         might_sleep_if(pri & __GFP_WAIT);
1222         if (skb_cloned(skb)) {
1223                 struct sk_buff *nskb = skb_copy(skb, pri);
1224 
1225                 /* Free our shared copy */
1226                 if (likely(nskb))
1227                         consume_skb(skb);
1228                 else
1229                         kfree_skb(skb);
1230                 skb = nskb;
1231         }
1232         return skb;
1233 }
1234 
1235 /**
1236  *      skb_peek - peek at the head of an &sk_buff_head
1237  *      @list_: list to peek at
1238  *
1239  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1240  *      be careful with this one. A peek leaves the buffer on the
1241  *      list and someone else may run off with it. You must hold
1242  *      the appropriate locks or have a private queue to do this.
1243  *
1244  *      Returns %NULL for an empty list or a pointer to the head element.
1245  *      The reference count is not incremented and the reference is therefore
1246  *      volatile. Use with caution.
1247  */
1248 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1249 {
1250         struct sk_buff *skb = list_->next;
1251 
1252         if (skb == (struct sk_buff *)list_)
1253                 skb = NULL;
1254         return skb;
1255 }
1256 
1257 /**
1258  *      skb_peek_next - peek skb following the given one from a queue
1259  *      @skb: skb to start from
1260  *      @list_: list to peek at
1261  *
1262  *      Returns %NULL when the end of the list is met or a pointer to the
1263  *      next element. The reference count is not incremented and the
1264  *      reference is therefore volatile. Use with caution.
1265  */
1266 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1267                 const struct sk_buff_head *list_)
1268 {
1269         struct sk_buff *next = skb->next;
1270 
1271         if (next == (struct sk_buff *)list_)
1272                 next = NULL;
1273         return next;
1274 }
1275 
1276 /**
1277  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1278  *      @list_: list to peek at
1279  *
1280  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1281  *      be careful with this one. A peek leaves the buffer on the
1282  *      list and someone else may run off with it. You must hold
1283  *      the appropriate locks or have a private queue to do this.
1284  *
1285  *      Returns %NULL for an empty list or a pointer to the tail element.
1286  *      The reference count is not incremented and the reference is therefore
1287  *      volatile. Use with caution.
1288  */
1289 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1290 {
1291         struct sk_buff *skb = list_->prev;
1292 
1293         if (skb == (struct sk_buff *)list_)
1294                 skb = NULL;
1295         return skb;
1296 
1297 }
1298 
1299 /**
1300  *      skb_queue_len   - get queue length
1301  *      @list_: list to measure
1302  *
1303  *      Return the length of an &sk_buff queue.
1304  */
1305 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1306 {
1307         return list_->qlen;
1308 }
1309 
1310 /**
1311  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1312  *      @list: queue to initialize
1313  *
1314  *      This initializes only the list and queue length aspects of
1315  *      an sk_buff_head object.  This allows to initialize the list
1316  *      aspects of an sk_buff_head without reinitializing things like
1317  *      the spinlock.  It can also be used for on-stack sk_buff_head
1318  *      objects where the spinlock is known to not be used.
1319  */
1320 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1321 {
1322         list->prev = list->next = (struct sk_buff *)list;
1323         list->qlen = 0;
1324 }
1325 
1326 /*
1327  * This function creates a split out lock class for each invocation;
1328  * this is needed for now since a whole lot of users of the skb-queue
1329  * infrastructure in drivers have different locking usage (in hardirq)
1330  * than the networking core (in softirq only). In the long run either the
1331  * network layer or drivers should need annotation to consolidate the
1332  * main types of usage into 3 classes.
1333  */
1334 static inline void skb_queue_head_init(struct sk_buff_head *list)
1335 {
1336         spin_lock_init(&list->lock);
1337         __skb_queue_head_init(list);
1338 }
1339 
1340 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1341                 struct lock_class_key *class)
1342 {
1343         skb_queue_head_init(list);
1344         lockdep_set_class(&list->lock, class);
1345 }
1346 
1347 /*
1348  *      Insert an sk_buff on a list.
1349  *
1350  *      The "__skb_xxxx()" functions are the non-atomic ones that
1351  *      can only be called with interrupts disabled.
1352  */
1353 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1354                 struct sk_buff_head *list);
1355 static inline void __skb_insert(struct sk_buff *newsk,
1356                                 struct sk_buff *prev, struct sk_buff *next,
1357                                 struct sk_buff_head *list)
1358 {
1359         newsk->next = next;
1360         newsk->prev = prev;
1361         next->prev  = prev->next = newsk;
1362         list->qlen++;
1363 }
1364 
1365 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1366                                       struct sk_buff *prev,
1367                                       struct sk_buff *next)
1368 {
1369         struct sk_buff *first = list->next;
1370         struct sk_buff *last = list->prev;
1371 
1372         first->prev = prev;
1373         prev->next = first;
1374 
1375         last->next = next;
1376         next->prev = last;
1377 }
1378 
1379 /**
1380  *      skb_queue_splice - join two skb lists, this is designed for stacks
1381  *      @list: the new list to add
1382  *      @head: the place to add it in the first list
1383  */
1384 static inline void skb_queue_splice(const struct sk_buff_head *list,
1385                                     struct sk_buff_head *head)
1386 {
1387         if (!skb_queue_empty(list)) {
1388                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1389                 head->qlen += list->qlen;
1390         }
1391 }
1392 
1393 /**
1394  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1395  *      @list: the new list to add
1396  *      @head: the place to add it in the first list
1397  *
1398  *      The list at @list is reinitialised
1399  */
1400 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1401                                          struct sk_buff_head *head)
1402 {
1403         if (!skb_queue_empty(list)) {
1404                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1405                 head->qlen += list->qlen;
1406                 __skb_queue_head_init(list);
1407         }
1408 }
1409 
1410 /**
1411  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1412  *      @list: the new list to add
1413  *      @head: the place to add it in the first list
1414  */
1415 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1416                                          struct sk_buff_head *head)
1417 {
1418         if (!skb_queue_empty(list)) {
1419                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1420                 head->qlen += list->qlen;
1421         }
1422 }
1423 
1424 /**
1425  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1426  *      @list: the new list to add
1427  *      @head: the place to add it in the first list
1428  *
1429  *      Each of the lists is a queue.
1430  *      The list at @list is reinitialised
1431  */
1432 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1433                                               struct sk_buff_head *head)
1434 {
1435         if (!skb_queue_empty(list)) {
1436                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1437                 head->qlen += list->qlen;
1438                 __skb_queue_head_init(list);
1439         }
1440 }
1441 
1442 /**
1443  *      __skb_queue_after - queue a buffer at the list head
1444  *      @list: list to use
1445  *      @prev: place after this buffer
1446  *      @newsk: buffer to queue
1447  *
1448  *      Queue a buffer int the middle of a list. This function takes no locks
1449  *      and you must therefore hold required locks before calling it.
1450  *
1451  *      A buffer cannot be placed on two lists at the same time.
1452  */
1453 static inline void __skb_queue_after(struct sk_buff_head *list,
1454                                      struct sk_buff *prev,
1455                                      struct sk_buff *newsk)
1456 {
1457         __skb_insert(newsk, prev, prev->next, list);
1458 }
1459 
1460 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1461                 struct sk_buff_head *list);
1462 
1463 static inline void __skb_queue_before(struct sk_buff_head *list,
1464                                       struct sk_buff *next,
1465                                       struct sk_buff *newsk)
1466 {
1467         __skb_insert(newsk, next->prev, next, list);
1468 }
1469 
1470 /**
1471  *      __skb_queue_head - queue a buffer at the list head
1472  *      @list: list to use
1473  *      @newsk: buffer to queue
1474  *
1475  *      Queue a buffer at the start of a list. This function takes no locks
1476  *      and you must therefore hold required locks before calling it.
1477  *
1478  *      A buffer cannot be placed on two lists at the same time.
1479  */
1480 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1481 static inline void __skb_queue_head(struct sk_buff_head *list,
1482                                     struct sk_buff *newsk)
1483 {
1484         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1485 }
1486 
1487 /**
1488  *      __skb_queue_tail - queue a buffer at the list tail
1489  *      @list: list to use
1490  *      @newsk: buffer to queue
1491  *
1492  *      Queue a buffer at the end of a list. This function takes no locks
1493  *      and you must therefore hold required locks before calling it.
1494  *
1495  *      A buffer cannot be placed on two lists at the same time.
1496  */
1497 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1498 static inline void __skb_queue_tail(struct sk_buff_head *list,
1499                                    struct sk_buff *newsk)
1500 {
1501         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1502 }
1503 
1504 /*
1505  * remove sk_buff from list. _Must_ be called atomically, and with
1506  * the list known..
1507  */
1508 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1509 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1510 {
1511         struct sk_buff *next, *prev;
1512 
1513         list->qlen--;
1514         next       = skb->next;
1515         prev       = skb->prev;
1516         skb->next  = skb->prev = NULL;
1517         next->prev = prev;
1518         prev->next = next;
1519 }
1520 
1521 /**
1522  *      __skb_dequeue - remove from the head of the queue
1523  *      @list: list to dequeue from
1524  *
1525  *      Remove the head of the list. This function does not take any locks
1526  *      so must be used with appropriate locks held only. The head item is
1527  *      returned or %NULL if the list is empty.
1528  */
1529 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1530 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1531 {
1532         struct sk_buff *skb = skb_peek(list);
1533         if (skb)
1534                 __skb_unlink(skb, list);
1535         return skb;
1536 }
1537 
1538 /**
1539  *      __skb_dequeue_tail - remove from the tail of the queue
1540  *      @list: list to dequeue from
1541  *
1542  *      Remove the tail of the list. This function does not take any locks
1543  *      so must be used with appropriate locks held only. The tail item is
1544  *      returned or %NULL if the list is empty.
1545  */
1546 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1547 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1548 {
1549         struct sk_buff *skb = skb_peek_tail(list);
1550         if (skb)
1551                 __skb_unlink(skb, list);
1552         return skb;
1553 }
1554 
1555 
1556 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1557 {
1558         return skb->data_len;
1559 }
1560 
1561 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1562 {
1563         return skb->len - skb->data_len;
1564 }
1565 
1566 static inline int skb_pagelen(const struct sk_buff *skb)
1567 {
1568         int i, len = 0;
1569 
1570         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1571                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1572         return len + skb_headlen(skb);
1573 }
1574 
1575 /**
1576  * __skb_fill_page_desc - initialise a paged fragment in an skb
1577  * @skb: buffer containing fragment to be initialised
1578  * @i: paged fragment index to initialise
1579  * @page: the page to use for this fragment
1580  * @off: the offset to the data with @page
1581  * @size: the length of the data
1582  *
1583  * Initialises the @i'th fragment of @skb to point to &size bytes at
1584  * offset @off within @page.
1585  *
1586  * Does not take any additional reference on the fragment.
1587  */
1588 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1589                                         struct page *page, int off, int size)
1590 {
1591         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1592 
1593         /*
1594          * Propagate page pfmemalloc to the skb if we can. The problem is
1595          * that not all callers have unique ownership of the page but rely
1596          * on page_is_pfmemalloc doing the right thing(tm).
1597          */
1598         frag->page.p              = page;
1599         frag->page_offset         = off;
1600         skb_frag_size_set(frag, size);
1601 
1602         page = compound_head(page);
1603         if (page_is_pfmemalloc(page))
1604                 skb->pfmemalloc = true;
1605 }
1606 
1607 /**
1608  * skb_fill_page_desc - initialise a paged fragment in an skb
1609  * @skb: buffer containing fragment to be initialised
1610  * @i: paged fragment index to initialise
1611  * @page: the page to use for this fragment
1612  * @off: the offset to the data with @page
1613  * @size: the length of the data
1614  *
1615  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1616  * @skb to point to @size bytes at offset @off within @page. In
1617  * addition updates @skb such that @i is the last fragment.
1618  *
1619  * Does not take any additional reference on the fragment.
1620  */
1621 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1622                                       struct page *page, int off, int size)
1623 {
1624         __skb_fill_page_desc(skb, i, page, off, size);
1625         skb_shinfo(skb)->nr_frags = i + 1;
1626 }
1627 
1628 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1629                      int size, unsigned int truesize);
1630 
1631 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1632                           unsigned int truesize);
1633 
1634 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1635 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1636 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1637 
1638 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1639 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1640 {
1641         return skb->head + skb->tail;
1642 }
1643 
1644 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1645 {
1646         skb->tail = skb->data - skb->head;
1647 }
1648 
1649 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1650 {
1651         skb_reset_tail_pointer(skb);
1652         skb->tail += offset;
1653 }
1654 
1655 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1656 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1657 {
1658         return skb->tail;
1659 }
1660 
1661 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1662 {
1663         skb->tail = skb->data;
1664 }
1665 
1666 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1667 {
1668         skb->tail = skb->data + offset;
1669 }
1670 
1671 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1672 
1673 /*
1674  *      Add data to an sk_buff
1675  */
1676 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1677 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1678 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1679 {
1680         unsigned char *tmp = skb_tail_pointer(skb);
1681         SKB_LINEAR_ASSERT(skb);
1682         skb->tail += len;
1683         skb->len  += len;
1684         return tmp;
1685 }
1686 
1687 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1688 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1689 {
1690         skb->data -= len;
1691         skb->len  += len;
1692         return skb->data;
1693 }
1694 
1695 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1696 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1697 {
1698         skb->len -= len;
1699         BUG_ON(skb->len < skb->data_len);
1700         return skb->data += len;
1701 }
1702 
1703 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1704 {
1705         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1706 }
1707 
1708 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1709 
1710 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1711 {
1712         if (len > skb_headlen(skb) &&
1713             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1714                 return NULL;
1715         skb->len -= len;
1716         return skb->data += len;
1717 }
1718 
1719 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1720 {
1721         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1722 }
1723 
1724 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1725 {
1726         if (likely(len <= skb_headlen(skb)))
1727                 return 1;
1728         if (unlikely(len > skb->len))
1729                 return 0;
1730         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1731 }
1732 
1733 /**
1734  *      skb_headroom - bytes at buffer head
1735  *      @skb: buffer to check
1736  *
1737  *      Return the number of bytes of free space at the head of an &sk_buff.
1738  */
1739 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1740 {
1741         return skb->data - skb->head;
1742 }
1743 
1744 /**
1745  *      skb_tailroom - bytes at buffer end
1746  *      @skb: buffer to check
1747  *
1748  *      Return the number of bytes of free space at the tail of an sk_buff
1749  */
1750 static inline int skb_tailroom(const struct sk_buff *skb)
1751 {
1752         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1753 }
1754 
1755 /**
1756  *      skb_availroom - bytes at buffer end
1757  *      @skb: buffer to check
1758  *
1759  *      Return the number of bytes of free space at the tail of an sk_buff
1760  *      allocated by sk_stream_alloc()
1761  */
1762 static inline int skb_availroom(const struct sk_buff *skb)
1763 {
1764         if (skb_is_nonlinear(skb))
1765                 return 0;
1766 
1767         return skb->end - skb->tail - skb->reserved_tailroom;
1768 }
1769 
1770 /**
1771  *      skb_reserve - adjust headroom
1772  *      @skb: buffer to alter
1773  *      @len: bytes to move
1774  *
1775  *      Increase the headroom of an empty &sk_buff by reducing the tail
1776  *      room. This is only allowed for an empty buffer.
1777  */
1778 static inline void skb_reserve(struct sk_buff *skb, int len)
1779 {
1780         skb->data += len;
1781         skb->tail += len;
1782 }
1783 
1784 /**
1785  *      skb_tailroom_reserve - adjust reserved_tailroom
1786  *      @skb: buffer to alter
1787  *      @mtu: maximum amount of headlen permitted
1788  *      @needed_tailroom: minimum amount of reserved_tailroom
1789  *
1790  *      Set reserved_tailroom so that headlen can be as large as possible but
1791  *      not larger than mtu and tailroom cannot be smaller than
1792  *      needed_tailroom.
1793  *      The required headroom should already have been reserved before using
1794  *      this function.
1795  */
1796 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
1797                                         unsigned int needed_tailroom)
1798 {
1799         SKB_LINEAR_ASSERT(skb);
1800         if (mtu < skb_tailroom(skb) - needed_tailroom)
1801                 /* use at most mtu */
1802                 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
1803         else
1804                 /* use up to all available space */
1805                 skb->reserved_tailroom = needed_tailroom;
1806 }
1807 
1808 #define ENCAP_TYPE_ETHER        0
1809 #define ENCAP_TYPE_IPPROTO      1
1810 
1811 static inline void skb_set_inner_protocol(struct sk_buff *skb,
1812                                           __be16 protocol)
1813 {
1814         skb->inner_protocol = protocol;
1815         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
1816 }
1817 
1818 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
1819                                          __u8 ipproto)
1820 {
1821         skb->inner_ipproto = ipproto;
1822         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
1823 }
1824 
1825 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1826 {
1827         skb->inner_mac_header = skb->mac_header;
1828         skb->inner_network_header = skb->network_header;
1829         skb->inner_transport_header = skb->transport_header;
1830 }
1831 
1832 static inline void skb_reset_mac_len(struct sk_buff *skb)
1833 {
1834         skb->mac_len = skb->network_header - skb->mac_header;
1835 }
1836 
1837 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1838                                                         *skb)
1839 {
1840         return skb->head + skb->inner_transport_header;
1841 }
1842 
1843 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1844 {
1845         skb->inner_transport_header = skb->data - skb->head;
1846 }
1847 
1848 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1849                                                    const int offset)
1850 {
1851         skb_reset_inner_transport_header(skb);
1852         skb->inner_transport_header += offset;
1853 }
1854 
1855 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1856 {
1857         return skb->head + skb->inner_network_header;
1858 }
1859 
1860 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1861 {
1862         skb->inner_network_header = skb->data - skb->head;
1863 }
1864 
1865 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1866                                                 const int offset)
1867 {
1868         skb_reset_inner_network_header(skb);
1869         skb->inner_network_header += offset;
1870 }
1871 
1872 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1873 {
1874         return skb->head + skb->inner_mac_header;
1875 }
1876 
1877 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1878 {
1879         skb->inner_mac_header = skb->data - skb->head;
1880 }
1881 
1882 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1883                                             const int offset)
1884 {
1885         skb_reset_inner_mac_header(skb);
1886         skb->inner_mac_header += offset;
1887 }
1888 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1889 {
1890         return skb->transport_header != (typeof(skb->transport_header))~0U;
1891 }
1892 
1893 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1894 {
1895         return skb->head + skb->transport_header;
1896 }
1897 
1898 static inline void skb_reset_transport_header(struct sk_buff *skb)
1899 {
1900         skb->transport_header = skb->data - skb->head;
1901 }
1902 
1903 static inline void skb_set_transport_header(struct sk_buff *skb,
1904                                             const int offset)
1905 {
1906         skb_reset_transport_header(skb);
1907         skb->transport_header += offset;
1908 }
1909 
1910 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1911 {
1912         return skb->head + skb->network_header;
1913 }
1914 
1915 static inline void skb_reset_network_header(struct sk_buff *skb)
1916 {
1917         skb->network_header = skb->data - skb->head;
1918 }
1919 
1920 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1921 {
1922         skb_reset_network_header(skb);
1923         skb->network_header += offset;
1924 }
1925 
1926 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1927 {
1928         return skb->head + skb->mac_header;
1929 }
1930 
1931 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1932 {
1933         return skb->mac_header != (typeof(skb->mac_header))~0U;
1934 }
1935 
1936 static inline void skb_reset_mac_header(struct sk_buff *skb)
1937 {
1938         skb->mac_header = skb->data - skb->head;
1939 }
1940 
1941 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1942 {
1943         skb_reset_mac_header(skb);
1944         skb->mac_header += offset;
1945 }
1946 
1947 static inline void skb_pop_mac_header(struct sk_buff *skb)
1948 {
1949         skb->mac_header = skb->network_header;
1950 }
1951 
1952 static inline void skb_probe_transport_header(struct sk_buff *skb,
1953                                               const int offset_hint)
1954 {
1955         struct flow_keys keys;
1956 
1957         if (skb_transport_header_was_set(skb))
1958                 return;
1959         else if (skb_flow_dissect(skb, &keys))
1960                 skb_set_transport_header(skb, keys.thoff);
1961         else
1962                 skb_set_transport_header(skb, offset_hint);
1963 }
1964 
1965 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1966 {
1967         if (skb_mac_header_was_set(skb)) {
1968                 const unsigned char *old_mac = skb_mac_header(skb);
1969 
1970                 skb_set_mac_header(skb, -skb->mac_len);
1971                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1972         }
1973 }
1974 
1975 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1976 {
1977         return skb->csum_start - skb_headroom(skb);
1978 }
1979 
1980 static inline int skb_transport_offset(const struct sk_buff *skb)
1981 {
1982         return skb_transport_header(skb) - skb->data;
1983 }
1984 
1985 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1986 {
1987         return skb->transport_header - skb->network_header;
1988 }
1989 
1990 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1991 {
1992         return skb->inner_transport_header - skb->inner_network_header;
1993 }
1994 
1995 static inline int skb_network_offset(const struct sk_buff *skb)
1996 {
1997         return skb_network_header(skb) - skb->data;
1998 }
1999 
2000 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2001 {
2002         return skb_inner_network_header(skb) - skb->data;
2003 }
2004 
2005 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2006 {
2007         return pskb_may_pull(skb, skb_network_offset(skb) + len);
2008 }
2009 
2010 /*
2011  * CPUs often take a performance hit when accessing unaligned memory
2012  * locations. The actual performance hit varies, it can be small if the
2013  * hardware handles it or large if we have to take an exception and fix it
2014  * in software.
2015  *
2016  * Since an ethernet header is 14 bytes network drivers often end up with
2017  * the IP header at an unaligned offset. The IP header can be aligned by
2018  * shifting the start of the packet by 2 bytes. Drivers should do this
2019  * with:
2020  *
2021  * skb_reserve(skb, NET_IP_ALIGN);
2022  *
2023  * The downside to this alignment of the IP header is that the DMA is now
2024  * unaligned. On some architectures the cost of an unaligned DMA is high
2025  * and this cost outweighs the gains made by aligning the IP header.
2026  *
2027  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2028  * to be overridden.
2029  */
2030 #ifndef NET_IP_ALIGN
2031 #define NET_IP_ALIGN    2
2032 #endif
2033 
2034 /*
2035  * The networking layer reserves some headroom in skb data (via
2036  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2037  * the header has to grow. In the default case, if the header has to grow
2038  * 32 bytes or less we avoid the reallocation.
2039  *
2040  * Unfortunately this headroom changes the DMA alignment of the resulting
2041  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2042  * on some architectures. An architecture can override this value,
2043  * perhaps setting it to a cacheline in size (since that will maintain
2044  * cacheline alignment of the DMA). It must be a power of 2.
2045  *
2046  * Various parts of the networking layer expect at least 32 bytes of
2047  * headroom, you should not reduce this.
2048  *
2049  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2050  * to reduce average number of cache lines per packet.
2051  * get_rps_cpus() for example only access one 64 bytes aligned block :
2052  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2053  */
2054 #ifndef NET_SKB_PAD
2055 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2056 #endif
2057 
2058 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2059 
2060 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2061 {
2062         if (unlikely(skb_is_nonlinear(skb))) {
2063                 WARN_ON(1);
2064                 return;
2065         }
2066         skb->len = len;
2067         skb_set_tail_pointer(skb, len);
2068 }
2069 
2070 void skb_trim(struct sk_buff *skb, unsigned int len);
2071 
2072 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2073 {
2074         if (skb->data_len)
2075                 return ___pskb_trim(skb, len);
2076         __skb_trim(skb, len);
2077         return 0;
2078 }
2079 
2080 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2081 {
2082         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2083 }
2084 
2085 /**
2086  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2087  *      @skb: buffer to alter
2088  *      @len: new length
2089  *
2090  *      This is identical to pskb_trim except that the caller knows that
2091  *      the skb is not cloned so we should never get an error due to out-
2092  *      of-memory.
2093  */
2094 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2095 {
2096         int err = pskb_trim(skb, len);
2097         BUG_ON(err);
2098 }
2099 
2100 /**
2101  *      skb_orphan - orphan a buffer
2102  *      @skb: buffer to orphan
2103  *
2104  *      If a buffer currently has an owner then we call the owner's
2105  *      destructor function and make the @skb unowned. The buffer continues
2106  *      to exist but is no longer charged to its former owner.
2107  */
2108 static inline void skb_orphan(struct sk_buff *skb)
2109 {
2110         if (skb->destructor) {
2111                 skb->destructor(skb);
2112                 skb->destructor = NULL;
2113                 skb->sk         = NULL;
2114         } else {
2115                 BUG_ON(skb->sk);
2116         }
2117 }
2118 
2119 /**
2120  *      skb_orphan_frags - orphan the frags contained in a buffer
2121  *      @skb: buffer to orphan frags from
2122  *      @gfp_mask: allocation mask for replacement pages
2123  *
2124  *      For each frag in the SKB which needs a destructor (i.e. has an
2125  *      owner) create a copy of that frag and release the original
2126  *      page by calling the destructor.
2127  */
2128 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2129 {
2130         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2131                 return 0;
2132         return skb_copy_ubufs(skb, gfp_mask);
2133 }
2134 
2135 /**
2136  *      __skb_queue_purge - empty a list
2137  *      @list: list to empty
2138  *
2139  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2140  *      the list and one reference dropped. This function does not take the
2141  *      list lock and the caller must hold the relevant locks to use it.
2142  */
2143 void skb_queue_purge(struct sk_buff_head *list);
2144 static inline void __skb_queue_purge(struct sk_buff_head *list)
2145 {
2146         struct sk_buff *skb;
2147         while ((skb = __skb_dequeue(list)) != NULL)
2148                 kfree_skb(skb);
2149 }
2150 
2151 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
2152 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
2153 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
2154 
2155 void *netdev_alloc_frag(unsigned int fragsz);
2156 
2157 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2158                                    gfp_t gfp_mask);
2159 
2160 /**
2161  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2162  *      @dev: network device to receive on
2163  *      @length: length to allocate
2164  *
2165  *      Allocate a new &sk_buff and assign it a usage count of one. The
2166  *      buffer has unspecified headroom built in. Users should allocate
2167  *      the headroom they think they need without accounting for the
2168  *      built in space. The built in space is used for optimisations.
2169  *
2170  *      %NULL is returned if there is no free memory. Although this function
2171  *      allocates memory it can be called from an interrupt.
2172  */
2173 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2174                                                unsigned int length)
2175 {
2176         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2177 }
2178 
2179 /* legacy helper around __netdev_alloc_skb() */
2180 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2181                                               gfp_t gfp_mask)
2182 {
2183         return __netdev_alloc_skb(NULL, length, gfp_mask);
2184 }
2185 
2186 /* legacy helper around netdev_alloc_skb() */
2187 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2188 {
2189         return netdev_alloc_skb(NULL, length);
2190 }
2191 
2192 
2193 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2194                 unsigned int length, gfp_t gfp)
2195 {
2196         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2197 
2198         if (NET_IP_ALIGN && skb)
2199                 skb_reserve(skb, NET_IP_ALIGN);
2200         return skb;
2201 }
2202 
2203 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2204                 unsigned int length)
2205 {
2206         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2207 }
2208 
2209 void *napi_alloc_frag(unsigned int fragsz);
2210 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2211                                  unsigned int length, gfp_t gfp_mask);
2212 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2213                                              unsigned int length)
2214 {
2215         return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2216 }
2217 
2218 /**
2219  * __dev_alloc_pages - allocate page for network Rx
2220  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2221  * @order: size of the allocation
2222  *
2223  * Allocate a new page.
2224  *
2225  * %NULL is returned if there is no free memory.
2226 */
2227 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2228                                              unsigned int order)
2229 {
2230         /* This piece of code contains several assumptions.
2231          * 1.  This is for device Rx, therefor a cold page is preferred.
2232          * 2.  The expectation is the user wants a compound page.
2233          * 3.  If requesting a order 0 page it will not be compound
2234          *     due to the check to see if order has a value in prep_new_page
2235          * 4.  __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2236          *     code in gfp_to_alloc_flags that should be enforcing this.
2237          */
2238         gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
2239 
2240         return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2241 }
2242 
2243 static inline struct page *dev_alloc_pages(unsigned int order)
2244 {
2245         return __dev_alloc_pages(GFP_ATOMIC, order);
2246 }
2247 
2248 /**
2249  * __dev_alloc_page - allocate a page for network Rx
2250  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2251  *
2252  * Allocate a new page.
2253  *
2254  * %NULL is returned if there is no free memory.
2255  */
2256 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2257 {
2258         return __dev_alloc_pages(gfp_mask, 0);
2259 }
2260 
2261 static inline struct page *dev_alloc_page(void)
2262 {
2263         return __dev_alloc_page(GFP_ATOMIC);
2264 }
2265 
2266 /**
2267  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2268  *      @page: The page that was allocated from skb_alloc_page
2269  *      @skb: The skb that may need pfmemalloc set
2270  */
2271 static inline void skb_propagate_pfmemalloc(struct page *page,
2272                                              struct sk_buff *skb)
2273 {
2274         if (page_is_pfmemalloc(page))
2275                 skb->pfmemalloc = true;
2276 }
2277 
2278 /**
2279  * skb_frag_page - retrieve the page referred to by a paged fragment
2280  * @frag: the paged fragment
2281  *
2282  * Returns the &struct page associated with @frag.
2283  */
2284 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2285 {
2286         return frag->page.p;
2287 }
2288 
2289 /**
2290  * __skb_frag_ref - take an addition reference on a paged fragment.
2291  * @frag: the paged fragment
2292  *
2293  * Takes an additional reference on the paged fragment @frag.
2294  */
2295 static inline void __skb_frag_ref(skb_frag_t *frag)
2296 {
2297         get_page(skb_frag_page(frag));
2298 }
2299 
2300 /**
2301  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2302  * @skb: the buffer
2303  * @f: the fragment offset.
2304  *
2305  * Takes an additional reference on the @f'th paged fragment of @skb.
2306  */
2307 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2308 {
2309         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2310 }
2311 
2312 /**
2313  * __skb_frag_unref - release a reference on a paged fragment.
2314  * @frag: the paged fragment
2315  *
2316  * Releases a reference on the paged fragment @frag.
2317  */
2318 static inline void __skb_frag_unref(skb_frag_t *frag)
2319 {
2320         put_page(skb_frag_page(frag));
2321 }
2322 
2323 /**
2324  * skb_frag_unref - release a reference on a paged fragment of an skb.
2325  * @skb: the buffer
2326  * @f: the fragment offset
2327  *
2328  * Releases a reference on the @f'th paged fragment of @skb.
2329  */
2330 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2331 {
2332         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2333 }
2334 
2335 /**
2336  * skb_frag_address - gets the address of the data contained in a paged fragment
2337  * @frag: the paged fragment buffer
2338  *
2339  * Returns the address of the data within @frag. The page must already
2340  * be mapped.
2341  */
2342 static inline void *skb_frag_address(const skb_frag_t *frag)
2343 {
2344         return page_address(skb_frag_page(frag)) + frag->page_offset;
2345 }
2346 
2347 /**
2348  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2349  * @frag: the paged fragment buffer
2350  *
2351  * Returns the address of the data within @frag. Checks that the page
2352  * is mapped and returns %NULL otherwise.
2353  */
2354 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2355 {
2356         void *ptr = page_address(skb_frag_page(frag));
2357         if (unlikely(!ptr))
2358                 return NULL;
2359 
2360         return ptr + frag->page_offset;
2361 }
2362 
2363 /**
2364  * __skb_frag_set_page - sets the page contained in a paged fragment
2365  * @frag: the paged fragment
2366  * @page: the page to set
2367  *
2368  * Sets the fragment @frag to contain @page.
2369  */
2370 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2371 {
2372         frag->page.p = page;
2373 }
2374 
2375 /**
2376  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2377  * @skb: the buffer
2378  * @f: the fragment offset
2379  * @page: the page to set
2380  *
2381  * Sets the @f'th fragment of @skb to contain @page.
2382  */
2383 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2384                                      struct page *page)
2385 {
2386         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2387 }
2388 
2389 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2390 
2391 /**
2392  * skb_frag_dma_map - maps a paged fragment via the DMA API
2393  * @dev: the device to map the fragment to
2394  * @frag: the paged fragment to map
2395  * @offset: the offset within the fragment (starting at the
2396  *          fragment's own offset)
2397  * @size: the number of bytes to map
2398  * @dir: the direction of the mapping (%PCI_DMA_*)
2399  *
2400  * Maps the page associated with @frag to @device.
2401  */
2402 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2403                                           const skb_frag_t *frag,
2404                                           size_t offset, size_t size,
2405                                           enum dma_data_direction dir)
2406 {
2407         return dma_map_page(dev, skb_frag_page(frag),
2408                             frag->page_offset + offset, size, dir);
2409 }
2410 
2411 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2412                                         gfp_t gfp_mask)
2413 {
2414         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2415 }
2416 
2417 
2418 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2419                                                   gfp_t gfp_mask)
2420 {
2421         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2422 }
2423 
2424 
2425 /**
2426  *      skb_clone_writable - is the header of a clone writable
2427  *      @skb: buffer to check
2428  *      @len: length up to which to write
2429  *
2430  *      Returns true if modifying the header part of the cloned buffer
2431  *      does not requires the data to be copied.
2432  */
2433 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2434 {
2435         return !skb_header_cloned(skb) &&
2436                skb_headroom(skb) + len <= skb->hdr_len;
2437 }
2438 
2439 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2440                             int cloned)
2441 {
2442         int delta = 0;
2443 
2444         if (headroom > skb_headroom(skb))
2445                 delta = headroom - skb_headroom(skb);
2446 
2447         if (delta || cloned)
2448                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2449                                         GFP_ATOMIC);
2450         return 0;
2451 }
2452 
2453 /**
2454  *      skb_cow - copy header of skb when it is required
2455  *      @skb: buffer to cow
2456  *      @headroom: needed headroom
2457  *
2458  *      If the skb passed lacks sufficient headroom or its data part
2459  *      is shared, data is reallocated. If reallocation fails, an error
2460  *      is returned and original skb is not changed.
2461  *
2462  *      The result is skb with writable area skb->head...skb->tail
2463  *      and at least @headroom of space at head.
2464  */
2465 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2466 {
2467         return __skb_cow(skb, headroom, skb_cloned(skb));
2468 }
2469 
2470 /**
2471  *      skb_cow_head - skb_cow but only making the head writable
2472  *      @skb: buffer to cow
2473  *      @headroom: needed headroom
2474  *
2475  *      This function is identical to skb_cow except that we replace the
2476  *      skb_cloned check by skb_header_cloned.  It should be used when
2477  *      you only need to push on some header and do not need to modify
2478  *      the data.
2479  */
2480 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2481 {
2482         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2483 }
2484 
2485 /**
2486  *      skb_padto       - pad an skbuff up to a minimal size
2487  *      @skb: buffer to pad
2488  *      @len: minimal length
2489  *
2490  *      Pads up a buffer to ensure the trailing bytes exist and are
2491  *      blanked. If the buffer already contains sufficient data it
2492  *      is untouched. Otherwise it is extended. Returns zero on
2493  *      success. The skb is freed on error.
2494  */
2495 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2496 {
2497         unsigned int size = skb->len;
2498         if (likely(size >= len))
2499                 return 0;
2500         return skb_pad(skb, len - size);
2501 }
2502 
2503 /**
2504  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
2505  *      @skb: buffer to pad
2506  *      @len: minimal length
2507  *
2508  *      Pads up a buffer to ensure the trailing bytes exist and are
2509  *      blanked. If the buffer already contains sufficient data it
2510  *      is untouched. Otherwise it is extended. Returns zero on
2511  *      success. The skb is freed on error.
2512  */
2513 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2514 {
2515         unsigned int size = skb->len;
2516 
2517         if (unlikely(size < len)) {
2518                 len -= size;
2519                 if (skb_pad(skb, len))
2520                         return -ENOMEM;
2521                 __skb_put(skb, len);
2522         }
2523         return 0;
2524 }
2525 
2526 static inline int skb_add_data(struct sk_buff *skb,
2527                                struct iov_iter *from, int copy)
2528 {
2529         const int off = skb->len;
2530 
2531         if (skb->ip_summed == CHECKSUM_NONE) {
2532                 __wsum csum = 0;
2533                 if (csum_and_copy_from_iter(skb_put(skb, copy), copy,
2534                                             &csum, from) == copy) {
2535                         skb->csum = csum_block_add(skb->csum, csum, off);
2536                         return 0;
2537                 }
2538         } else if (copy_from_iter(skb_put(skb, copy), copy, from) == copy)
2539                 return 0;
2540 
2541         __skb_trim(skb, off);
2542         return -EFAULT;
2543 }
2544 
2545 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2546                                     const struct page *page, int off)
2547 {
2548         if (i) {
2549                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2550 
2551                 return page == skb_frag_page(frag) &&
2552                        off == frag->page_offset + skb_frag_size(frag);
2553         }
2554         return false;
2555 }
2556 
2557 static inline int __skb_linearize(struct sk_buff *skb)
2558 {
2559         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2560 }
2561 
2562 /**
2563  *      skb_linearize - convert paged skb to linear one
2564  *      @skb: buffer to linarize
2565  *
2566  *      If there is no free memory -ENOMEM is returned, otherwise zero
2567  *      is returned and the old skb data released.
2568  */
2569 static inline int skb_linearize(struct sk_buff *skb)
2570 {
2571         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2572 }
2573 
2574 /**
2575  * skb_has_shared_frag - can any frag be overwritten
2576  * @skb: buffer to test
2577  *
2578  * Return true if the skb has at least one frag that might be modified
2579  * by an external entity (as in vmsplice()/sendfile())
2580  */
2581 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2582 {
2583         return skb_is_nonlinear(skb) &&
2584                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2585 }
2586 
2587 /**
2588  *      skb_linearize_cow - make sure skb is linear and writable
2589  *      @skb: buffer to process
2590  *
2591  *      If there is no free memory -ENOMEM is returned, otherwise zero
2592  *      is returned and the old skb data released.
2593  */
2594 static inline int skb_linearize_cow(struct sk_buff *skb)
2595 {
2596         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2597                __skb_linearize(skb) : 0;
2598 }
2599 
2600 /**
2601  *      skb_postpull_rcsum - update checksum for received skb after pull
2602  *      @skb: buffer to update
2603  *      @start: start of data before pull
2604  *      @len: length of data pulled
2605  *
2606  *      After doing a pull on a received packet, you need to call this to
2607  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2608  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2609  */
2610 
2611 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2612                                       const void *start, unsigned int len)
2613 {
2614         if (skb->ip_summed == CHECKSUM_COMPLETE)
2615                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2616         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2617                  skb_checksum_start_offset(skb) < 0)
2618                 skb->ip_summed = CHECKSUM_NONE;
2619 }
2620 
2621 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2622 
2623 /**
2624  *      pskb_trim_rcsum - trim received skb and update checksum
2625  *      @skb: buffer to trim
2626  *      @len: new length
2627  *
2628  *      This is exactly the same as pskb_trim except that it ensures the
2629  *      checksum of received packets are still valid after the operation.
2630  */
2631 
2632 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2633 {
2634         if (likely(len >= skb->len))
2635                 return 0;
2636         if (skb->ip_summed == CHECKSUM_COMPLETE)
2637                 skb->ip_summed = CHECKSUM_NONE;
2638         return __pskb_trim(skb, len);
2639 }
2640 
2641 #define skb_queue_walk(queue, skb) \
2642                 for (skb = (queue)->next;                                       \
2643                      skb != (struct sk_buff *)(queue);                          \
2644                      skb = skb->next)
2645 
2646 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2647                 for (skb = (queue)->next, tmp = skb->next;                      \
2648                      skb != (struct sk_buff *)(queue);                          \
2649                      skb = tmp, tmp = skb->next)
2650 
2651 #define skb_queue_walk_from(queue, skb)                                         \
2652                 for (; skb != (struct sk_buff *)(queue);                        \
2653                      skb = skb->next)
2654 
2655 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2656                 for (tmp = skb->next;                                           \
2657                      skb != (struct sk_buff *)(queue);                          \
2658                      skb = tmp, tmp = skb->next)
2659 
2660 #define skb_queue_reverse_walk(queue, skb) \
2661                 for (skb = (queue)->prev;                                       \
2662                      skb != (struct sk_buff *)(queue);                          \
2663                      skb = skb->prev)
2664 
2665 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2666                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2667                      skb != (struct sk_buff *)(queue);                          \
2668                      skb = tmp, tmp = skb->prev)
2669 
2670 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2671                 for (tmp = skb->prev;                                           \
2672                      skb != (struct sk_buff *)(queue);                          \
2673                      skb = tmp, tmp = skb->prev)
2674 
2675 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2676 {
2677         return skb_shinfo(skb)->frag_list != NULL;
2678 }
2679 
2680 static inline void skb_frag_list_init(struct sk_buff *skb)
2681 {
2682         skb_shinfo(skb)->frag_list = NULL;
2683 }
2684 
2685 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2686 {
2687         frag->next = skb_shinfo(skb)->frag_list;
2688         skb_shinfo(skb)->frag_list = frag;
2689 }
2690 
2691 #define skb_walk_frags(skb, iter)       \
2692         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2693 
2694 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2695                                     int *peeked, int *off, int *err);
2696 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2697                                   int *err);
2698 unsigned int datagram_poll(struct file *file, struct socket *sock,
2699                            struct poll_table_struct *wait);
2700 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
2701                            struct iov_iter *to, int size);
2702 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
2703                                         struct msghdr *msg, int size)
2704 {
2705         return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
2706 }
2707 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
2708                                    struct msghdr *msg);
2709 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
2710                                  struct iov_iter *from, int len);
2711 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
2712 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2713 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2714 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2715 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2716 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2717 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2718                               int len, __wsum csum);
2719 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
2720                     struct pipe_inode_info *pipe, unsigned int len,
2721                     unsigned int flags);
2722 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2723 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
2724 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
2725                  int len, int hlen);
2726 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2727 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2728 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2729 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2730 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2731 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
2732 int skb_ensure_writable(struct sk_buff *skb, int write_len);
2733 int skb_vlan_pop(struct sk_buff *skb);
2734 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
2735 
2736 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
2737 {
2738         return copy_from_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
2739 }
2740 
2741 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
2742 {
2743         return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
2744 }
2745 
2746 struct skb_checksum_ops {
2747         __wsum (*update)(const void *mem, int len, __wsum wsum);
2748         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2749 };
2750 
2751 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2752                       __wsum csum, const struct skb_checksum_ops *ops);
2753 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2754                     __wsum csum);
2755 
2756 static inline void *__skb_header_pointer(const struct sk_buff *skb, int offset,
2757                                          int len, void *data, int hlen, void *buffer)
2758 {
2759         if (hlen - offset >= len)
2760                 return data + offset;
2761 
2762         if (!skb ||
2763             skb_copy_bits(skb, offset, buffer, len) < 0)
2764                 return NULL;
2765 
2766         return buffer;
2767 }
2768 
2769 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2770                                        int len, void *buffer)
2771 {
2772         return __skb_header_pointer(skb, offset, len, skb->data,
2773                                     skb_headlen(skb), buffer);
2774 }
2775 
2776 /**
2777  *      skb_needs_linearize - check if we need to linearize a given skb
2778  *                            depending on the given device features.
2779  *      @skb: socket buffer to check
2780  *      @features: net device features
2781  *
2782  *      Returns true if either:
2783  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
2784  *      2. skb is fragmented and the device does not support SG.
2785  */
2786 static inline bool skb_needs_linearize(struct sk_buff *skb,
2787                                        netdev_features_t features)
2788 {
2789         return skb_is_nonlinear(skb) &&
2790                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
2791                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
2792 }
2793 
2794 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2795                                              void *to,
2796                                              const unsigned int len)
2797 {
2798         memcpy(to, skb->data, len);
2799 }
2800 
2801 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2802                                                     const int offset, void *to,
2803                                                     const unsigned int len)
2804 {
2805         memcpy(to, skb->data + offset, len);
2806 }
2807 
2808 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2809                                            const void *from,
2810                                            const unsigned int len)
2811 {
2812         memcpy(skb->data, from, len);
2813 }
2814 
2815 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2816                                                   const int offset,
2817                                                   const void *from,
2818                                                   const unsigned int len)
2819 {
2820         memcpy(skb->data + offset, from, len);
2821 }
2822 
2823 void skb_init(void);
2824 
2825 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2826 {
2827         return skb->tstamp;
2828 }
2829 
2830 /**
2831  *      skb_get_timestamp - get timestamp from a skb
2832  *      @skb: skb to get stamp from
2833  *      @stamp: pointer to struct timeval to store stamp in
2834  *
2835  *      Timestamps are stored in the skb as offsets to a base timestamp.
2836  *      This function converts the offset back to a struct timeval and stores
2837  *      it in stamp.
2838  */
2839 static inline void skb_get_timestamp(const struct sk_buff *skb,
2840                                      struct timeval *stamp)
2841 {
2842         *stamp = ktime_to_timeval(skb->tstamp);
2843 }
2844 
2845 static inline void skb_get_timestampns(const struct sk_buff *skb,
2846                                        struct timespec *stamp)
2847 {
2848         *stamp = ktime_to_timespec(skb->tstamp);
2849 }
2850 
2851 static inline void __net_timestamp(struct sk_buff *skb)
2852 {
2853         skb->tstamp = ktime_get_real();
2854 }
2855 
2856 static inline ktime_t net_timedelta(ktime_t t)
2857 {
2858         return ktime_sub(ktime_get_real(), t);
2859 }
2860 
2861 static inline ktime_t net_invalid_timestamp(void)
2862 {
2863         return ktime_set(0, 0);
2864 }
2865 
2866 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
2867 
2868 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2869 
2870 void skb_clone_tx_timestamp(struct sk_buff *skb);
2871 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2872 
2873 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2874 
2875 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2876 {
2877 }
2878 
2879 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2880 {
2881         return false;
2882 }
2883 
2884 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2885 
2886 /**
2887  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2888  *
2889  * PHY drivers may accept clones of transmitted packets for
2890  * timestamping via their phy_driver.txtstamp method. These drivers
2891  * must call this function to return the skb back to the stack, with
2892  * or without a timestamp.
2893  *
2894  * @skb: clone of the the original outgoing packet
2895  * @hwtstamps: hardware time stamps, may be NULL if not available
2896  *
2897  */
2898 void skb_complete_tx_timestamp(struct sk_buff *skb,
2899                                struct skb_shared_hwtstamps *hwtstamps);
2900 
2901 void __skb_tstamp_tx(struct sk_buff *orig_skb,
2902                      struct skb_shared_hwtstamps *hwtstamps,
2903                      struct sock *sk, int tstype);
2904 
2905 /**
2906  * skb_tstamp_tx - queue clone of skb with send time stamps
2907  * @orig_skb:   the original outgoing packet
2908  * @hwtstamps:  hardware time stamps, may be NULL if not available
2909  *
2910  * If the skb has a socket associated, then this function clones the
2911  * skb (thus sharing the actual data and optional structures), stores
2912  * the optional hardware time stamping information (if non NULL) or
2913  * generates a software time stamp (otherwise), then queues the clone
2914  * to the error queue of the socket.  Errors are silently ignored.
2915  */
2916 void skb_tstamp_tx(struct sk_buff *orig_skb,
2917                    struct skb_shared_hwtstamps *hwtstamps);
2918 
2919 static inline void sw_tx_timestamp(struct sk_buff *skb)
2920 {
2921         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2922             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2923                 skb_tstamp_tx(skb, NULL);
2924 }
2925 
2926 /**
2927  * skb_tx_timestamp() - Driver hook for transmit timestamping
2928  *
2929  * Ethernet MAC Drivers should call this function in their hard_xmit()
2930  * function immediately before giving the sk_buff to the MAC hardware.
2931  *
2932  * Specifically, one should make absolutely sure that this function is
2933  * called before TX completion of this packet can trigger.  Otherwise
2934  * the packet could potentially already be freed.
2935  *
2936  * @skb: A socket buffer.
2937  */
2938 static inline void skb_tx_timestamp(struct sk_buff *skb)
2939 {
2940         skb_clone_tx_timestamp(skb);
2941         sw_tx_timestamp(skb);
2942 }
2943 
2944 /**
2945  * skb_complete_wifi_ack - deliver skb with wifi status
2946  *
2947  * @skb: the original outgoing packet
2948  * @acked: ack status
2949  *
2950  */
2951 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2952 
2953 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2954 __sum16 __skb_checksum_complete(struct sk_buff *skb);
2955 
2956 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2957 {
2958         return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
2959                 skb->csum_valid ||
2960                 (skb->ip_summed == CHECKSUM_PARTIAL &&
2961                  skb_checksum_start_offset(skb) >= 0));
2962 }
2963 
2964 /**
2965  *      skb_checksum_complete - Calculate checksum of an entire packet
2966  *      @skb: packet to process
2967  *
2968  *      This function calculates the checksum over the entire packet plus
2969  *      the value of skb->csum.  The latter can be used to supply the
2970  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2971  *      checksum.
2972  *
2973  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2974  *      this function can be used to verify that checksum on received
2975  *      packets.  In that case the function should return zero if the
2976  *      checksum is correct.  In particular, this function will return zero
2977  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2978  *      hardware has already verified the correctness of the checksum.
2979  */
2980 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2981 {
2982         return skb_csum_unnecessary(skb) ?
2983                0 : __skb_checksum_complete(skb);
2984 }
2985 
2986 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
2987 {
2988         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
2989                 if (skb->csum_level == 0)
2990                         skb->ip_summed = CHECKSUM_NONE;
2991                 else
2992                         skb->csum_level--;
2993         }
2994 }
2995 
2996 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
2997 {
2998         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
2999                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3000                         skb->csum_level++;
3001         } else if (skb->ip_summed == CHECKSUM_NONE) {
3002                 skb->ip_summed = CHECKSUM_UNNECESSARY;
3003                 skb->csum_level = 0;
3004         }
3005 }
3006 
3007 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
3008 {
3009         /* Mark current checksum as bad (typically called from GRO
3010          * path). In the case that ip_summed is CHECKSUM_NONE
3011          * this must be the first checksum encountered in the packet.
3012          * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
3013          * checksum after the last one validated. For UDP, a zero
3014          * checksum can not be marked as bad.
3015          */
3016 
3017         if (skb->ip_summed == CHECKSUM_NONE ||
3018             skb->ip_summed == CHECKSUM_UNNECESSARY)
3019                 skb->csum_bad = 1;
3020 }
3021 
3022 /* Check if we need to perform checksum complete validation.
3023  *
3024  * Returns true if checksum complete is needed, false otherwise
3025  * (either checksum is unnecessary or zero checksum is allowed).
3026  */
3027 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3028                                                   bool zero_okay,
3029                                                   __sum16 check)
3030 {
3031         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3032                 skb->csum_valid = 1;
3033                 __skb_decr_checksum_unnecessary(skb);
3034                 return false;
3035         }
3036 
3037         return true;
3038 }
3039 
3040 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3041  * in checksum_init.
3042  */
3043 #define CHECKSUM_BREAK 76
3044 
3045 /* Unset checksum-complete
3046  *
3047  * Unset checksum complete can be done when packet is being modified
3048  * (uncompressed for instance) and checksum-complete value is
3049  * invalidated.
3050  */
3051 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3052 {
3053         if (skb->ip_summed == CHECKSUM_COMPLETE)
3054                 skb->ip_summed = CHECKSUM_NONE;
3055 }
3056 
3057 /* Validate (init) checksum based on checksum complete.
3058  *
3059  * Return values:
3060  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
3061  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3062  *      checksum is stored in skb->csum for use in __skb_checksum_complete
3063  *   non-zero: value of invalid checksum
3064  *
3065  */
3066 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3067                                                        bool complete,
3068                                                        __wsum psum)
3069 {
3070         if (skb->ip_summed == CHECKSUM_COMPLETE) {
3071                 if (!csum_fold(csum_add(psum, skb->csum))) {
3072                         skb->csum_valid = 1;
3073                         return 0;
3074                 }
3075         } else if (skb->csum_bad) {
3076                 /* ip_summed == CHECKSUM_NONE in this case */
3077                 return 1;
3078         }
3079 
3080         skb->csum = psum;
3081 
3082         if (complete || skb->len <= CHECKSUM_BREAK) {
3083                 __sum16 csum;
3084 
3085                 csum = __skb_checksum_complete(skb);
3086                 skb->csum_valid = !csum;
3087                 return csum;
3088         }
3089 
3090         return 0;
3091 }
3092 
3093 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3094 {
3095         return 0;
3096 }
3097 
3098 /* Perform checksum validate (init). Note that this is a macro since we only
3099  * want to calculate the pseudo header which is an input function if necessary.
3100  * First we try to validate without any computation (checksum unnecessary) and
3101  * then calculate based on checksum complete calling the function to compute
3102  * pseudo header.
3103  *
3104  * Return values:
3105  *   0: checksum is validated or try to in skb_checksum_complete
3106  *   non-zero: value of invalid checksum
3107  */
3108 #define __skb_checksum_validate(skb, proto, complete,                   \
3109                                 zero_okay, check, compute_pseudo)       \
3110 ({                                                                      \
3111         __sum16 __ret = 0;                                              \
3112         skb->csum_valid = 0;                                            \
3113         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3114                 __ret = __skb_checksum_validate_complete(skb,           \
3115                                 complete, compute_pseudo(skb, proto));  \
3116         __ret;                                                          \
3117 })
3118 
3119 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3120         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3121 
3122 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3123         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3124 
3125 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3126         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3127 
3128 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3129                                          compute_pseudo)                \
3130         __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3131 
3132 #define skb_checksum_simple_validate(skb)                               \
3133         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3134 
3135 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3136 {
3137         return (skb->ip_summed == CHECKSUM_NONE &&
3138                 skb->csum_valid && !skb->csum_bad);
3139 }
3140 
3141 static inline void __skb_checksum_convert(struct sk_buff *skb,
3142                                           __sum16 check, __wsum pseudo)
3143 {
3144         skb->csum = ~pseudo;
3145         skb->ip_summed = CHECKSUM_COMPLETE;
3146 }
3147 
3148 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3149 do {                                                                    \
3150         if (__skb_checksum_convert_check(skb))                          \
3151                 __skb_checksum_convert(skb, check,                      \
3152                                        compute_pseudo(skb, proto));     \
3153 } while (0)
3154 
3155 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3156                                               u16 start, u16 offset)
3157 {
3158         skb->ip_summed = CHECKSUM_PARTIAL;
3159         skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3160         skb->csum_offset = offset - start;
3161 }
3162 
3163 /* Update skbuf and packet to reflect the remote checksum offload operation.
3164  * When called, ptr indicates the starting point for skb->csum when
3165  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3166  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3167  */
3168 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3169                                        int start, int offset, bool nopartial)
3170 {
3171         __wsum delta;
3172 
3173         if (!nopartial) {
3174                 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3175                 return;
3176         }
3177 
3178          if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3179                 __skb_checksum_complete(skb);
3180                 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3181         }
3182 
3183         delta = remcsum_adjust(ptr, skb->csum, start, offset);
3184 
3185         /* Adjust skb->csum since we changed the packet */
3186         skb->csum = csum_add(skb->csum, delta);
3187 }
3188 
3189 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3190 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3191 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3192 {
3193         if (nfct && atomic_dec_and_test(&nfct->use))
3194                 nf_conntrack_destroy(nfct);
3195 }
3196 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3197 {
3198         if (nfct)
3199                 atomic_inc(&nfct->use);
3200 }
3201 #endif
3202 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3203 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3204 {
3205         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3206                 kfree(nf_bridge);
3207 }
3208 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3209 {
3210         if (nf_bridge)
3211                 atomic_inc(&nf_bridge->use);
3212 }
3213 #endif /* CONFIG_BRIDGE_NETFILTER */
3214 static inline void nf_reset(struct sk_buff *skb)
3215 {
3216 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3217         nf_conntrack_put(skb->nfct);
3218         skb->nfct = NULL;
3219 #endif
3220 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3221         nf_bridge_put(skb->nf_bridge);
3222         skb->nf_bridge = NULL;
3223 #endif
3224 }
3225 
3226 static inline void nf_reset_trace(struct sk_buff *skb)
3227 {
3228 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3229         skb->nf_trace = 0;
3230 #endif
3231 }
3232 
3233 static inline void ipvs_reset(struct sk_buff *skb)
3234 {
3235 #if IS_ENABLED(CONFIG_IP_VS)
3236         skb->ipvs_property = 0;
3237 #endif
3238 }
3239 
3240 /* Note: This doesn't put any conntrack and bridge info in dst. */
3241 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3242                              bool copy)
3243 {
3244 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3245         dst->nfct = src->nfct;
3246         nf_conntrack_get(src->nfct);
3247         if (copy)
3248                 dst->nfctinfo = src->nfctinfo;
3249 #endif
3250 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3251         dst->nf_bridge  = src->nf_bridge;
3252         nf_bridge_get(src->nf_bridge);
3253 #endif
3254 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3255         if (copy)
3256                 dst->nf_trace = src->nf_trace;
3257 #endif
3258 }
3259 
3260 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3261 {
3262 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3263         nf_conntrack_put(dst->nfct);
3264 #endif
3265 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3266         nf_bridge_put(dst->nf_bridge);
3267 #endif
3268         __nf_copy(dst, src, true);
3269 }
3270 
3271 #ifdef CONFIG_NETWORK_SECMARK
3272 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3273 {
3274         to->secmark = from->secmark;
3275 }
3276 
3277 static inline void skb_init_secmark(struct sk_buff *skb)
3278 {
3279         skb->secmark = 0;
3280 }
3281 #else
3282 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3283 { }
3284 
3285 static inline void skb_init_secmark(struct sk_buff *skb)
3286 { }
3287 #endif
3288 
3289 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3290 {
3291         return !skb->destructor &&
3292 #if IS_ENABLED(CONFIG_XFRM)
3293                 !skb->sp &&
3294 #endif
3295 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3296                 !skb->nfct &&
3297 #endif
3298                 !skb->_skb_refdst &&
3299                 !skb_has_frag_list(skb);
3300 }
3301 
3302 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3303 {
3304         skb->queue_mapping = queue_mapping;
3305 }
3306 
3307 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3308 {
3309         return skb->queue_mapping;
3310 }
3311 
3312 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3313 {
3314         to->queue_mapping = from->queue_mapping;
3315 }
3316 
3317 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3318 {
3319         skb->queue_mapping = rx_queue + 1;
3320 }
3321 
3322 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3323 {
3324         return skb->queue_mapping - 1;
3325 }
3326 
3327 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3328 {
3329         return skb->queue_mapping != 0;
3330 }
3331 
3332 u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
3333                   unsigned int num_tx_queues);
3334 
3335 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3336 {
3337 #ifdef CONFIG_XFRM
3338         return skb->sp;
3339 #else
3340         return NULL;
3341 #endif
3342 }
3343 
3344 /* Keeps track of mac header offset relative to skb->head.
3345  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3346  * For non-tunnel skb it points to skb_mac_header() and for
3347  * tunnel skb it points to outer mac header.
3348  * Keeps track of level of encapsulation of network headers.
3349  */
3350 struct skb_gso_cb {
3351         int     mac_offset;
3352         int     encap_level;
3353         __u16   csum_start;
3354 };
3355 #define SKB_SGO_CB_OFFSET       32
3356 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
3357 
3358 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3359 {
3360         return (skb_mac_header(inner_skb) - inner_skb->head) -
3361                 SKB_GSO_CB(inner_skb)->mac_offset;
3362 }
3363 
3364 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3365 {
3366         int new_headroom, headroom;
3367         int ret;
3368 
3369         headroom = skb_headroom(skb);
3370         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3371         if (ret)
3372                 return ret;
3373 
3374         new_headroom = skb_headroom(skb);
3375         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3376         return 0;
3377 }
3378 
3379 /* Compute the checksum for a gso segment. First compute the checksum value
3380  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3381  * then add in skb->csum (checksum from csum_start to end of packet).
3382  * skb->csum and csum_start are then updated to reflect the checksum of the
3383  * resultant packet starting from the transport header-- the resultant checksum
3384  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3385  * header.
3386  */
3387 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3388 {
3389         int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
3390             skb_transport_offset(skb);
3391         __u16 csum;
3392 
3393         csum = csum_fold(csum_partial(skb_transport_header(skb),
3394                                       plen, skb->csum));
3395         skb->csum = res;
3396         SKB_GSO_CB(skb)->csum_start -= plen;
3397 
3398         return csum;
3399 }
3400 
3401 static inline bool skb_is_gso(const struct sk_buff *skb)
3402 {
3403         return skb_shinfo(skb)->gso_size;
3404 }
3405 
3406 /* Note: Should be called only if skb_is_gso(skb) is true */
3407 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3408 {
3409         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3410 }
3411 
3412 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3413 
3414 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3415 {
3416         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3417          * wanted then gso_type will be set. */
3418         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3419 
3420         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3421             unlikely(shinfo->gso_type == 0)) {
3422                 __skb_warn_lro_forwarding(skb);
3423                 return true;
3424         }
3425         return false;
3426 }
3427 
3428 static inline void skb_forward_csum(struct sk_buff *skb)
3429 {
3430         /* Unfortunately we don't support this one.  Any brave souls? */
3431         if (skb->ip_summed == CHECKSUM_COMPLETE)
3432                 skb->ip_summed = CHECKSUM_NONE;
3433 }
3434 
3435 /**
3436  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3437  * @skb: skb to check
3438  *
3439  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3440  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3441  * use this helper, to document places where we make this assertion.
3442  */
3443 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3444 {
3445 #ifdef DEBUG
3446         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3447 #endif
3448 }
3449 
3450 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3451 
3452 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3453 
3454 u32 skb_get_poff(const struct sk_buff *skb);
3455 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
3456                    const struct flow_keys *keys, int hlen);
3457 
3458 /**
3459  * skb_head_is_locked - Determine if the skb->head is locked down
3460  * @skb: skb to check
3461  *
3462  * The head on skbs build around a head frag can be removed if they are
3463  * not cloned.  This function returns true if the skb head is locked down
3464  * due to either being allocated via kmalloc, or by being a clone with
3465  * multiple references to the head.
3466  */
3467 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3468 {
3469         return !skb->head_frag || skb_cloned(skb);
3470 }
3471 
3472 /**
3473  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3474  *
3475  * @skb: GSO skb
3476  *
3477  * skb_gso_network_seglen is used to determine the real size of the
3478  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3479  *
3480  * The MAC/L2 header is not accounted for.
3481  */
3482 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3483 {
3484         unsigned int hdr_len = skb_transport_header(skb) -
3485                                skb_network_header(skb);
3486         return hdr_len + skb_gso_transport_seglen(skb);
3487 }
3488 #endif  /* __KERNEL__ */
3489 #endif  /* _LINUX_SKBUFF_H */
3490 

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