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Linux/include/linux/skbuff.h

  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 
 24 #include <linux/atomic.h>
 25 #include <asm/types.h>
 26 #include <linux/spinlock.h>
 27 #include <linux/net.h>
 28 #include <linux/textsearch.h>
 29 #include <net/checksum.h>
 30 #include <linux/rcupdate.h>
 31 #include <linux/dmaengine.h>
 32 #include <linux/hrtimer.h>
 33 #include <linux/dma-mapping.h>
 34 #include <linux/netdev_features.h>
 35 #include <net/flow_keys.h>
 36 
 37 /* Don't change this without changing skb_csum_unnecessary! */
 38 #define CHECKSUM_NONE 0
 39 #define CHECKSUM_UNNECESSARY 1
 40 #define CHECKSUM_COMPLETE 2
 41 #define CHECKSUM_PARTIAL 3
 42 
 43 #define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
 44                                  ~(SMP_CACHE_BYTES - 1))
 45 #define SKB_WITH_OVERHEAD(X)    \
 46         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 47 #define SKB_MAX_ORDER(X, ORDER) \
 48         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
 49 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
 50 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
 51 
 52 /* return minimum truesize of one skb containing X bytes of data */
 53 #define SKB_TRUESIZE(X) ((X) +                                          \
 54                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
 55                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 56 
 57 /* A. Checksumming of received packets by device.
 58  *
 59  *      NONE: device failed to checksum this packet.
 60  *              skb->csum is undefined.
 61  *
 62  *      UNNECESSARY: device parsed packet and wouldbe verified checksum.
 63  *              skb->csum is undefined.
 64  *            It is bad option, but, unfortunately, many of vendors do this.
 65  *            Apparently with secret goal to sell you new device, when you
 66  *            will add new protocol to your host. F.e. IPv6. 8)
 67  *
 68  *      COMPLETE: the most generic way. Device supplied checksum of _all_
 69  *          the packet as seen by netif_rx in skb->csum.
 70  *          NOTE: Even if device supports only some protocols, but
 71  *          is able to produce some skb->csum, it MUST use COMPLETE,
 72  *          not UNNECESSARY.
 73  *
 74  *      PARTIAL: identical to the case for output below.  This may occur
 75  *          on a packet received directly from another Linux OS, e.g.,
 76  *          a virtualised Linux kernel on the same host.  The packet can
 77  *          be treated in the same way as UNNECESSARY except that on
 78  *          output (i.e., forwarding) the checksum must be filled in
 79  *          by the OS or the hardware.
 80  *
 81  * B. Checksumming on output.
 82  *
 83  *      NONE: skb is checksummed by protocol or csum is not required.
 84  *
 85  *      PARTIAL: device is required to csum packet as seen by hard_start_xmit
 86  *      from skb->csum_start to the end and to record the checksum
 87  *      at skb->csum_start + skb->csum_offset.
 88  *
 89  *      Device must show its capabilities in dev->features, set
 90  *      at device setup time.
 91  *      NETIF_F_HW_CSUM - it is clever device, it is able to checksum
 92  *                        everything.
 93  *      NETIF_F_IP_CSUM - device is dumb. It is able to csum only
 94  *                        TCP/UDP over IPv4. Sigh. Vendors like this
 95  *                        way by an unknown reason. Though, see comment above
 96  *                        about CHECKSUM_UNNECESSARY. 8)
 97  *      NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
 98  *
 99  *      UNNECESSARY: device will do per protocol specific csum. Protocol drivers
100  *      that do not want net to perform the checksum calculation should use
101  *      this flag in their outgoing skbs.
102  *      NETIF_F_FCOE_CRC  this indicates the device can do FCoE FC CRC
103  *                        offload. Correspondingly, the FCoE protocol driver
104  *                        stack should use CHECKSUM_UNNECESSARY.
105  *
106  *      Any questions? No questions, good.              --ANK
107  */
108 
109 struct net_device;
110 struct scatterlist;
111 struct pipe_inode_info;
112 
113 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
114 struct nf_conntrack {
115         atomic_t use;
116 };
117 #endif
118 
119 #ifdef CONFIG_BRIDGE_NETFILTER
120 struct nf_bridge_info {
121         atomic_t                use;
122         unsigned int            mask;
123         struct net_device       *physindev;
124         struct net_device       *physoutdev;
125         unsigned long           data[32 / sizeof(unsigned long)];
126 };
127 #endif
128 
129 struct sk_buff_head {
130         /* These two members must be first. */
131         struct sk_buff  *next;
132         struct sk_buff  *prev;
133 
134         __u32           qlen;
135         spinlock_t      lock;
136 };
137 
138 struct sk_buff;
139 
140 /* To allow 64K frame to be packed as single skb without frag_list we
141  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
142  * buffers which do not start on a page boundary.
143  *
144  * Since GRO uses frags we allocate at least 16 regardless of page
145  * size.
146  */
147 #if (65536/PAGE_SIZE + 1) < 16
148 #define MAX_SKB_FRAGS 16UL
149 #else
150 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
151 #endif
152 
153 typedef struct skb_frag_struct skb_frag_t;
154 
155 struct skb_frag_struct {
156         struct {
157                 struct page *p;
158         } page;
159 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
160         __u32 page_offset;
161         __u32 size;
162 #else
163         __u16 page_offset;
164         __u16 size;
165 #endif
166 };
167 
168 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
169 {
170         return frag->size;
171 }
172 
173 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
174 {
175         frag->size = size;
176 }
177 
178 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
179 {
180         frag->size += delta;
181 }
182 
183 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
184 {
185         frag->size -= delta;
186 }
187 
188 #define HAVE_HW_TIME_STAMP
189 
190 /**
191  * struct skb_shared_hwtstamps - hardware time stamps
192  * @hwtstamp:   hardware time stamp transformed into duration
193  *              since arbitrary point in time
194  * @syststamp:  hwtstamp transformed to system time base
195  *
196  * Software time stamps generated by ktime_get_real() are stored in
197  * skb->tstamp. The relation between the different kinds of time
198  * stamps is as follows:
199  *
200  * syststamp and tstamp can be compared against each other in
201  * arbitrary combinations.  The accuracy of a
202  * syststamp/tstamp/"syststamp from other device" comparison is
203  * limited by the accuracy of the transformation into system time
204  * base. This depends on the device driver and its underlying
205  * hardware.
206  *
207  * hwtstamps can only be compared against other hwtstamps from
208  * the same device.
209  *
210  * This structure is attached to packets as part of the
211  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
212  */
213 struct skb_shared_hwtstamps {
214         ktime_t hwtstamp;
215         ktime_t syststamp;
216 };
217 
218 /* Definitions for tx_flags in struct skb_shared_info */
219 enum {
220         /* generate hardware time stamp */
221         SKBTX_HW_TSTAMP = 1 << 0,
222 
223         /* generate software time stamp */
224         SKBTX_SW_TSTAMP = 1 << 1,
225 
226         /* device driver is going to provide hardware time stamp */
227         SKBTX_IN_PROGRESS = 1 << 2,
228 
229         /* device driver supports TX zero-copy buffers */
230         SKBTX_DEV_ZEROCOPY = 1 << 3,
231 
232         /* generate wifi status information (where possible) */
233         SKBTX_WIFI_STATUS = 1 << 4,
234 
235         /* This indicates at least one fragment might be overwritten
236          * (as in vmsplice(), sendfile() ...)
237          * If we need to compute a TX checksum, we'll need to copy
238          * all frags to avoid possible bad checksum
239          */
240         SKBTX_SHARED_FRAG = 1 << 5,
241 };
242 
243 /*
244  * The callback notifies userspace to release buffers when skb DMA is done in
245  * lower device, the skb last reference should be 0 when calling this.
246  * The zerocopy_success argument is true if zero copy transmit occurred,
247  * false on data copy or out of memory error caused by data copy attempt.
248  * The ctx field is used to track device context.
249  * The desc field is used to track userspace buffer index.
250  */
251 struct ubuf_info {
252         void (*callback)(struct ubuf_info *, bool zerocopy_success);
253         void *ctx;
254         unsigned long desc;
255 };
256 
257 /* This data is invariant across clones and lives at
258  * the end of the header data, ie. at skb->end.
259  */
260 struct skb_shared_info {
261         unsigned char   nr_frags;
262         __u8            tx_flags;
263         unsigned short  gso_size;
264         /* Warning: this field is not always filled in (UFO)! */
265         unsigned short  gso_segs;
266         unsigned short  gso_type;
267         struct sk_buff  *frag_list;
268         struct skb_shared_hwtstamps hwtstamps;
269         __be32          ip6_frag_id;
270 
271         /*
272          * Warning : all fields before dataref are cleared in __alloc_skb()
273          */
274         atomic_t        dataref;
275 
276         /* Intermediate layers must ensure that destructor_arg
277          * remains valid until skb destructor */
278         void *          destructor_arg;
279 
280         /* must be last field, see pskb_expand_head() */
281         skb_frag_t      frags[MAX_SKB_FRAGS];
282 };
283 
284 /* We divide dataref into two halves.  The higher 16 bits hold references
285  * to the payload part of skb->data.  The lower 16 bits hold references to
286  * the entire skb->data.  A clone of a headerless skb holds the length of
287  * the header in skb->hdr_len.
288  *
289  * All users must obey the rule that the skb->data reference count must be
290  * greater than or equal to the payload reference count.
291  *
292  * Holding a reference to the payload part means that the user does not
293  * care about modifications to the header part of skb->data.
294  */
295 #define SKB_DATAREF_SHIFT 16
296 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
297 
298 
299 enum {
300         SKB_FCLONE_UNAVAILABLE,
301         SKB_FCLONE_ORIG,
302         SKB_FCLONE_CLONE,
303 };
304 
305 enum {
306         SKB_GSO_TCPV4 = 1 << 0,
307         SKB_GSO_UDP = 1 << 1,
308 
309         /* This indicates the skb is from an untrusted source. */
310         SKB_GSO_DODGY = 1 << 2,
311 
312         /* This indicates the tcp segment has CWR set. */
313         SKB_GSO_TCP_ECN = 1 << 3,
314 
315         SKB_GSO_TCPV6 = 1 << 4,
316 
317         SKB_GSO_FCOE = 1 << 5,
318 
319         SKB_GSO_GRE = 1 << 6,
320 
321         SKB_GSO_IPIP = 1 << 7,
322 
323         SKB_GSO_SIT = 1 << 8,
324 
325         SKB_GSO_UDP_TUNNEL = 1 << 9,
326 
327         SKB_GSO_MPLS = 1 << 10,
328 };
329 
330 #if BITS_PER_LONG > 32
331 #define NET_SKBUFF_DATA_USES_OFFSET 1
332 #endif
333 
334 #ifdef NET_SKBUFF_DATA_USES_OFFSET
335 typedef unsigned int sk_buff_data_t;
336 #else
337 typedef unsigned char *sk_buff_data_t;
338 #endif
339 
340 /** 
341  *      struct sk_buff - socket buffer
342  *      @next: Next buffer in list
343  *      @prev: Previous buffer in list
344  *      @tstamp: Time we arrived
345  *      @sk: Socket we are owned by
346  *      @dev: Device we arrived on/are leaving by
347  *      @cb: Control buffer. Free for use by every layer. Put private vars here
348  *      @_skb_refdst: destination entry (with norefcount bit)
349  *      @sp: the security path, used for xfrm
350  *      @len: Length of actual data
351  *      @data_len: Data length
352  *      @mac_len: Length of link layer header
353  *      @hdr_len: writable header length of cloned skb
354  *      @csum: Checksum (must include start/offset pair)
355  *      @csum_start: Offset from skb->head where checksumming should start
356  *      @csum_offset: Offset from csum_start where checksum should be stored
357  *      @priority: Packet queueing priority
358  *      @local_df: allow local fragmentation
359  *      @cloned: Head may be cloned (check refcnt to be sure)
360  *      @ip_summed: Driver fed us an IP checksum
361  *      @nohdr: Payload reference only, must not modify header
362  *      @nfctinfo: Relationship of this skb to the connection
363  *      @pkt_type: Packet class
364  *      @fclone: skbuff clone status
365  *      @ipvs_property: skbuff is owned by ipvs
366  *      @peeked: this packet has been seen already, so stats have been
367  *              done for it, don't do them again
368  *      @nf_trace: netfilter packet trace flag
369  *      @protocol: Packet protocol from driver
370  *      @destructor: Destruct function
371  *      @nfct: Associated connection, if any
372  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
373  *      @skb_iif: ifindex of device we arrived on
374  *      @tc_index: Traffic control index
375  *      @tc_verd: traffic control verdict
376  *      @rxhash: the packet hash computed on receive
377  *      @queue_mapping: Queue mapping for multiqueue devices
378  *      @ndisc_nodetype: router type (from link layer)
379  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
380  *      @l4_rxhash: indicate rxhash is a canonical 4-tuple hash over transport
381  *              ports.
382  *      @wifi_acked_valid: wifi_acked was set
383  *      @wifi_acked: whether frame was acked on wifi or not
384  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
385  *      @dma_cookie: a cookie to one of several possible DMA operations
386  *              done by skb DMA functions
387   *     @napi_id: id of the NAPI struct this skb came from
388  *      @secmark: security marking
389  *      @mark: Generic packet mark
390  *      @dropcount: total number of sk_receive_queue overflows
391  *      @vlan_proto: vlan encapsulation protocol
392  *      @vlan_tci: vlan tag control information
393  *      @inner_protocol: Protocol (encapsulation)
394  *      @inner_transport_header: Inner transport layer header (encapsulation)
395  *      @inner_network_header: Network layer header (encapsulation)
396  *      @inner_mac_header: Link layer header (encapsulation)
397  *      @transport_header: Transport layer header
398  *      @network_header: Network layer header
399  *      @mac_header: Link layer header
400  *      @tail: Tail pointer
401  *      @end: End pointer
402  *      @head: Head of buffer
403  *      @data: Data head pointer
404  *      @truesize: Buffer size
405  *      @users: User count - see {datagram,tcp}.c
406  */
407 
408 struct sk_buff {
409         /* These two members must be first. */
410         struct sk_buff          *next;
411         struct sk_buff          *prev;
412 
413         ktime_t                 tstamp;
414 
415         struct sock             *sk;
416         struct net_device       *dev;
417 
418         /*
419          * This is the control buffer. It is free to use for every
420          * layer. Please put your private variables there. If you
421          * want to keep them across layers you have to do a skb_clone()
422          * first. This is owned by whoever has the skb queued ATM.
423          */
424         char                    cb[48] __aligned(8);
425 
426         unsigned long           _skb_refdst;
427 #ifdef CONFIG_XFRM
428         struct  sec_path        *sp;
429 #endif
430         unsigned int            len,
431                                 data_len;
432         __u16                   mac_len,
433                                 hdr_len;
434         union {
435                 __wsum          csum;
436                 struct {
437                         __u16   csum_start;
438                         __u16   csum_offset;
439                 };
440         };
441         __u32                   priority;
442         kmemcheck_bitfield_begin(flags1);
443         __u8                    local_df:1,
444                                 cloned:1,
445                                 ip_summed:2,
446                                 nohdr:1,
447                                 nfctinfo:3;
448         __u8                    pkt_type:3,
449                                 fclone:2,
450                                 ipvs_property:1,
451                                 peeked:1,
452                                 nf_trace:1;
453         kmemcheck_bitfield_end(flags1);
454         __be16                  protocol;
455 
456         void                    (*destructor)(struct sk_buff *skb);
457 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
458         struct nf_conntrack     *nfct;
459 #endif
460 #ifdef CONFIG_BRIDGE_NETFILTER
461         struct nf_bridge_info   *nf_bridge;
462 #endif
463 
464         int                     skb_iif;
465 
466         __u32                   rxhash;
467 
468         __be16                  vlan_proto;
469         __u16                   vlan_tci;
470 
471 #ifdef CONFIG_NET_SCHED
472         __u16                   tc_index;       /* traffic control index */
473 #ifdef CONFIG_NET_CLS_ACT
474         __u16                   tc_verd;        /* traffic control verdict */
475 #endif
476 #endif
477 
478         __u16                   queue_mapping;
479         kmemcheck_bitfield_begin(flags2);
480 #ifdef CONFIG_IPV6_NDISC_NODETYPE
481         __u8                    ndisc_nodetype:2;
482 #endif
483         __u8                    pfmemalloc:1;
484         __u8                    ooo_okay:1;
485         __u8                    l4_rxhash:1;
486         __u8                    wifi_acked_valid:1;
487         __u8                    wifi_acked:1;
488         __u8                    no_fcs:1;
489         __u8                    head_frag:1;
490         /* Encapsulation protocol and NIC drivers should use
491          * this flag to indicate to each other if the skb contains
492          * encapsulated packet or not and maybe use the inner packet
493          * headers if needed
494          */
495         __u8                    encapsulation:1;
496         /* 6/8 bit hole (depending on ndisc_nodetype presence) */
497         kmemcheck_bitfield_end(flags2);
498 
499 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
500         union {
501                 unsigned int    napi_id;
502                 dma_cookie_t    dma_cookie;
503         };
504 #endif
505 #ifdef CONFIG_NETWORK_SECMARK
506         __u32                   secmark;
507 #endif
508         union {
509                 __u32           mark;
510                 __u32           dropcount;
511                 __u32           reserved_tailroom;
512         };
513 
514         __be16                  inner_protocol;
515         __u16                   inner_transport_header;
516         __u16                   inner_network_header;
517         __u16                   inner_mac_header;
518         __u16                   transport_header;
519         __u16                   network_header;
520         __u16                   mac_header;
521         /* These elements must be at the end, see alloc_skb() for details.  */
522         sk_buff_data_t          tail;
523         sk_buff_data_t          end;
524         unsigned char           *head,
525                                 *data;
526         unsigned int            truesize;
527         atomic_t                users;
528 };
529 
530 #ifdef __KERNEL__
531 /*
532  *      Handling routines are only of interest to the kernel
533  */
534 #include <linux/slab.h>
535 
536 
537 #define SKB_ALLOC_FCLONE        0x01
538 #define SKB_ALLOC_RX            0x02
539 
540 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
541 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
542 {
543         return unlikely(skb->pfmemalloc);
544 }
545 
546 /*
547  * skb might have a dst pointer attached, refcounted or not.
548  * _skb_refdst low order bit is set if refcount was _not_ taken
549  */
550 #define SKB_DST_NOREF   1UL
551 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
552 
553 /**
554  * skb_dst - returns skb dst_entry
555  * @skb: buffer
556  *
557  * Returns skb dst_entry, regardless of reference taken or not.
558  */
559 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
560 {
561         /* If refdst was not refcounted, check we still are in a 
562          * rcu_read_lock section
563          */
564         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
565                 !rcu_read_lock_held() &&
566                 !rcu_read_lock_bh_held());
567         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
568 }
569 
570 /**
571  * skb_dst_set - sets skb dst
572  * @skb: buffer
573  * @dst: dst entry
574  *
575  * Sets skb dst, assuming a reference was taken on dst and should
576  * be released by skb_dst_drop()
577  */
578 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
579 {
580         skb->_skb_refdst = (unsigned long)dst;
581 }
582 
583 void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
584                          bool force);
585 
586 /**
587  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
588  * @skb: buffer
589  * @dst: dst entry
590  *
591  * Sets skb dst, assuming a reference was not taken on dst.
592  * If dst entry is cached, we do not take reference and dst_release
593  * will be avoided by refdst_drop. If dst entry is not cached, we take
594  * reference, so that last dst_release can destroy the dst immediately.
595  */
596 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
597 {
598         __skb_dst_set_noref(skb, dst, false);
599 }
600 
601 /**
602  * skb_dst_set_noref_force - sets skb dst, without taking reference
603  * @skb: buffer
604  * @dst: dst entry
605  *
606  * Sets skb dst, assuming a reference was not taken on dst.
607  * No reference is taken and no dst_release will be called. While for
608  * cached dsts deferred reclaim is a basic feature, for entries that are
609  * not cached it is caller's job to guarantee that last dst_release for
610  * provided dst happens when nobody uses it, eg. after a RCU grace period.
611  */
612 static inline void skb_dst_set_noref_force(struct sk_buff *skb,
613                                            struct dst_entry *dst)
614 {
615         __skb_dst_set_noref(skb, dst, true);
616 }
617 
618 /**
619  * skb_dst_is_noref - Test if skb dst isn't refcounted
620  * @skb: buffer
621  */
622 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
623 {
624         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
625 }
626 
627 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
628 {
629         return (struct rtable *)skb_dst(skb);
630 }
631 
632 void kfree_skb(struct sk_buff *skb);
633 void kfree_skb_list(struct sk_buff *segs);
634 void skb_tx_error(struct sk_buff *skb);
635 void consume_skb(struct sk_buff *skb);
636 void  __kfree_skb(struct sk_buff *skb);
637 extern struct kmem_cache *skbuff_head_cache;
638 
639 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
640 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
641                       bool *fragstolen, int *delta_truesize);
642 
643 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
644                             int node);
645 struct sk_buff *build_skb(void *data, unsigned int frag_size);
646 static inline struct sk_buff *alloc_skb(unsigned int size,
647                                         gfp_t priority)
648 {
649         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
650 }
651 
652 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
653                                                gfp_t priority)
654 {
655         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
656 }
657 
658 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
659 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
660 {
661         return __alloc_skb_head(priority, -1);
662 }
663 
664 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
665 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
666 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
667 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
668 struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask);
669 
670 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
671 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
672                                      unsigned int headroom);
673 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
674                                 int newtailroom, gfp_t priority);
675 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
676                  int len);
677 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
678 int skb_pad(struct sk_buff *skb, int pad);
679 #define dev_kfree_skb(a)        consume_skb(a)
680 
681 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
682                             int getfrag(void *from, char *to, int offset,
683                                         int len, int odd, struct sk_buff *skb),
684                             void *from, int length);
685 
686 struct skb_seq_state {
687         __u32           lower_offset;
688         __u32           upper_offset;
689         __u32           frag_idx;
690         __u32           stepped_offset;
691         struct sk_buff  *root_skb;
692         struct sk_buff  *cur_skb;
693         __u8            *frag_data;
694 };
695 
696 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
697                           unsigned int to, struct skb_seq_state *st);
698 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
699                           struct skb_seq_state *st);
700 void skb_abort_seq_read(struct skb_seq_state *st);
701 
702 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
703                            unsigned int to, struct ts_config *config,
704                            struct ts_state *state);
705 
706 void __skb_get_rxhash(struct sk_buff *skb);
707 static inline __u32 skb_get_rxhash(struct sk_buff *skb)
708 {
709         if (!skb->l4_rxhash)
710                 __skb_get_rxhash(skb);
711 
712         return skb->rxhash;
713 }
714 
715 #ifdef NET_SKBUFF_DATA_USES_OFFSET
716 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
717 {
718         return skb->head + skb->end;
719 }
720 
721 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
722 {
723         return skb->end;
724 }
725 #else
726 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
727 {
728         return skb->end;
729 }
730 
731 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
732 {
733         return skb->end - skb->head;
734 }
735 #endif
736 
737 /* Internal */
738 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
739 
740 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
741 {
742         return &skb_shinfo(skb)->hwtstamps;
743 }
744 
745 /**
746  *      skb_queue_empty - check if a queue is empty
747  *      @list: queue head
748  *
749  *      Returns true if the queue is empty, false otherwise.
750  */
751 static inline int skb_queue_empty(const struct sk_buff_head *list)
752 {
753         return list->next == (struct sk_buff *)list;
754 }
755 
756 /**
757  *      skb_queue_is_last - check if skb is the last entry in the queue
758  *      @list: queue head
759  *      @skb: buffer
760  *
761  *      Returns true if @skb is the last buffer on the list.
762  */
763 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
764                                      const struct sk_buff *skb)
765 {
766         return skb->next == (struct sk_buff *)list;
767 }
768 
769 /**
770  *      skb_queue_is_first - check if skb is the first entry in the queue
771  *      @list: queue head
772  *      @skb: buffer
773  *
774  *      Returns true if @skb is the first buffer on the list.
775  */
776 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
777                                       const struct sk_buff *skb)
778 {
779         return skb->prev == (struct sk_buff *)list;
780 }
781 
782 /**
783  *      skb_queue_next - return the next packet in the queue
784  *      @list: queue head
785  *      @skb: current buffer
786  *
787  *      Return the next packet in @list after @skb.  It is only valid to
788  *      call this if skb_queue_is_last() evaluates to false.
789  */
790 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
791                                              const struct sk_buff *skb)
792 {
793         /* This BUG_ON may seem severe, but if we just return then we
794          * are going to dereference garbage.
795          */
796         BUG_ON(skb_queue_is_last(list, skb));
797         return skb->next;
798 }
799 
800 /**
801  *      skb_queue_prev - return the prev packet in the queue
802  *      @list: queue head
803  *      @skb: current buffer
804  *
805  *      Return the prev packet in @list before @skb.  It is only valid to
806  *      call this if skb_queue_is_first() evaluates to false.
807  */
808 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
809                                              const struct sk_buff *skb)
810 {
811         /* This BUG_ON may seem severe, but if we just return then we
812          * are going to dereference garbage.
813          */
814         BUG_ON(skb_queue_is_first(list, skb));
815         return skb->prev;
816 }
817 
818 /**
819  *      skb_get - reference buffer
820  *      @skb: buffer to reference
821  *
822  *      Makes another reference to a socket buffer and returns a pointer
823  *      to the buffer.
824  */
825 static inline struct sk_buff *skb_get(struct sk_buff *skb)
826 {
827         atomic_inc(&skb->users);
828         return skb;
829 }
830 
831 /*
832  * If users == 1, we are the only owner and are can avoid redundant
833  * atomic change.
834  */
835 
836 /**
837  *      skb_cloned - is the buffer a clone
838  *      @skb: buffer to check
839  *
840  *      Returns true if the buffer was generated with skb_clone() and is
841  *      one of multiple shared copies of the buffer. Cloned buffers are
842  *      shared data so must not be written to under normal circumstances.
843  */
844 static inline int skb_cloned(const struct sk_buff *skb)
845 {
846         return skb->cloned &&
847                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
848 }
849 
850 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
851 {
852         might_sleep_if(pri & __GFP_WAIT);
853 
854         if (skb_cloned(skb))
855                 return pskb_expand_head(skb, 0, 0, pri);
856 
857         return 0;
858 }
859 
860 /**
861  *      skb_header_cloned - is the header a clone
862  *      @skb: buffer to check
863  *
864  *      Returns true if modifying the header part of the buffer requires
865  *      the data to be copied.
866  */
867 static inline int skb_header_cloned(const struct sk_buff *skb)
868 {
869         int dataref;
870 
871         if (!skb->cloned)
872                 return 0;
873 
874         dataref = atomic_read(&skb_shinfo(skb)->dataref);
875         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
876         return dataref != 1;
877 }
878 
879 /**
880  *      skb_header_release - release reference to header
881  *      @skb: buffer to operate on
882  *
883  *      Drop a reference to the header part of the buffer.  This is done
884  *      by acquiring a payload reference.  You must not read from the header
885  *      part of skb->data after this.
886  */
887 static inline void skb_header_release(struct sk_buff *skb)
888 {
889         BUG_ON(skb->nohdr);
890         skb->nohdr = 1;
891         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
892 }
893 
894 /**
895  *      skb_shared - is the buffer shared
896  *      @skb: buffer to check
897  *
898  *      Returns true if more than one person has a reference to this
899  *      buffer.
900  */
901 static inline int skb_shared(const struct sk_buff *skb)
902 {
903         return atomic_read(&skb->users) != 1;
904 }
905 
906 /**
907  *      skb_share_check - check if buffer is shared and if so clone it
908  *      @skb: buffer to check
909  *      @pri: priority for memory allocation
910  *
911  *      If the buffer is shared the buffer is cloned and the old copy
912  *      drops a reference. A new clone with a single reference is returned.
913  *      If the buffer is not shared the original buffer is returned. When
914  *      being called from interrupt status or with spinlocks held pri must
915  *      be GFP_ATOMIC.
916  *
917  *      NULL is returned on a memory allocation failure.
918  */
919 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
920 {
921         might_sleep_if(pri & __GFP_WAIT);
922         if (skb_shared(skb)) {
923                 struct sk_buff *nskb = skb_clone(skb, pri);
924 
925                 if (likely(nskb))
926                         consume_skb(skb);
927                 else
928                         kfree_skb(skb);
929                 skb = nskb;
930         }
931         return skb;
932 }
933 
934 /*
935  *      Copy shared buffers into a new sk_buff. We effectively do COW on
936  *      packets to handle cases where we have a local reader and forward
937  *      and a couple of other messy ones. The normal one is tcpdumping
938  *      a packet thats being forwarded.
939  */
940 
941 /**
942  *      skb_unshare - make a copy of a shared buffer
943  *      @skb: buffer to check
944  *      @pri: priority for memory allocation
945  *
946  *      If the socket buffer is a clone then this function creates a new
947  *      copy of the data, drops a reference count on the old copy and returns
948  *      the new copy with the reference count at 1. If the buffer is not a clone
949  *      the original buffer is returned. When called with a spinlock held or
950  *      from interrupt state @pri must be %GFP_ATOMIC
951  *
952  *      %NULL is returned on a memory allocation failure.
953  */
954 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
955                                           gfp_t pri)
956 {
957         might_sleep_if(pri & __GFP_WAIT);
958         if (skb_cloned(skb)) {
959                 struct sk_buff *nskb = skb_copy(skb, pri);
960                 kfree_skb(skb); /* Free our shared copy */
961                 skb = nskb;
962         }
963         return skb;
964 }
965 
966 /**
967  *      skb_peek - peek at the head of an &sk_buff_head
968  *      @list_: list to peek at
969  *
970  *      Peek an &sk_buff. Unlike most other operations you _MUST_
971  *      be careful with this one. A peek leaves the buffer on the
972  *      list and someone else may run off with it. You must hold
973  *      the appropriate locks or have a private queue to do this.
974  *
975  *      Returns %NULL for an empty list or a pointer to the head element.
976  *      The reference count is not incremented and the reference is therefore
977  *      volatile. Use with caution.
978  */
979 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
980 {
981         struct sk_buff *skb = list_->next;
982 
983         if (skb == (struct sk_buff *)list_)
984                 skb = NULL;
985         return skb;
986 }
987 
988 /**
989  *      skb_peek_next - peek skb following the given one from a queue
990  *      @skb: skb to start from
991  *      @list_: list to peek at
992  *
993  *      Returns %NULL when the end of the list is met or a pointer to the
994  *      next element. The reference count is not incremented and the
995  *      reference is therefore volatile. Use with caution.
996  */
997 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
998                 const struct sk_buff_head *list_)
999 {
1000         struct sk_buff *next = skb->next;
1001 
1002         if (next == (struct sk_buff *)list_)
1003                 next = NULL;
1004         return next;
1005 }
1006 
1007 /**
1008  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1009  *      @list_: list to peek at
1010  *
1011  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1012  *      be careful with this one. A peek leaves the buffer on the
1013  *      list and someone else may run off with it. You must hold
1014  *      the appropriate locks or have a private queue to do this.
1015  *
1016  *      Returns %NULL for an empty list or a pointer to the tail element.
1017  *      The reference count is not incremented and the reference is therefore
1018  *      volatile. Use with caution.
1019  */
1020 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1021 {
1022         struct sk_buff *skb = list_->prev;
1023 
1024         if (skb == (struct sk_buff *)list_)
1025                 skb = NULL;
1026         return skb;
1027 
1028 }
1029 
1030 /**
1031  *      skb_queue_len   - get queue length
1032  *      @list_: list to measure
1033  *
1034  *      Return the length of an &sk_buff queue.
1035  */
1036 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1037 {
1038         return list_->qlen;
1039 }
1040 
1041 /**
1042  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1043  *      @list: queue to initialize
1044  *
1045  *      This initializes only the list and queue length aspects of
1046  *      an sk_buff_head object.  This allows to initialize the list
1047  *      aspects of an sk_buff_head without reinitializing things like
1048  *      the spinlock.  It can also be used for on-stack sk_buff_head
1049  *      objects where the spinlock is known to not be used.
1050  */
1051 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1052 {
1053         list->prev = list->next = (struct sk_buff *)list;
1054         list->qlen = 0;
1055 }
1056 
1057 /*
1058  * This function creates a split out lock class for each invocation;
1059  * this is needed for now since a whole lot of users of the skb-queue
1060  * infrastructure in drivers have different locking usage (in hardirq)
1061  * than the networking core (in softirq only). In the long run either the
1062  * network layer or drivers should need annotation to consolidate the
1063  * main types of usage into 3 classes.
1064  */
1065 static inline void skb_queue_head_init(struct sk_buff_head *list)
1066 {
1067         spin_lock_init(&list->lock);
1068         __skb_queue_head_init(list);
1069 }
1070 
1071 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1072                 struct lock_class_key *class)
1073 {
1074         skb_queue_head_init(list);
1075         lockdep_set_class(&list->lock, class);
1076 }
1077 
1078 /*
1079  *      Insert an sk_buff on a list.
1080  *
1081  *      The "__skb_xxxx()" functions are the non-atomic ones that
1082  *      can only be called with interrupts disabled.
1083  */
1084 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1085                 struct sk_buff_head *list);
1086 static inline void __skb_insert(struct sk_buff *newsk,
1087                                 struct sk_buff *prev, struct sk_buff *next,
1088                                 struct sk_buff_head *list)
1089 {
1090         newsk->next = next;
1091         newsk->prev = prev;
1092         next->prev  = prev->next = newsk;
1093         list->qlen++;
1094 }
1095 
1096 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1097                                       struct sk_buff *prev,
1098                                       struct sk_buff *next)
1099 {
1100         struct sk_buff *first = list->next;
1101         struct sk_buff *last = list->prev;
1102 
1103         first->prev = prev;
1104         prev->next = first;
1105 
1106         last->next = next;
1107         next->prev = last;
1108 }
1109 
1110 /**
1111  *      skb_queue_splice - join two skb lists, this is designed for stacks
1112  *      @list: the new list to add
1113  *      @head: the place to add it in the first list
1114  */
1115 static inline void skb_queue_splice(const struct sk_buff_head *list,
1116                                     struct sk_buff_head *head)
1117 {
1118         if (!skb_queue_empty(list)) {
1119                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1120                 head->qlen += list->qlen;
1121         }
1122 }
1123 
1124 /**
1125  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1126  *      @list: the new list to add
1127  *      @head: the place to add it in the first list
1128  *
1129  *      The list at @list is reinitialised
1130  */
1131 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1132                                          struct sk_buff_head *head)
1133 {
1134         if (!skb_queue_empty(list)) {
1135                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1136                 head->qlen += list->qlen;
1137                 __skb_queue_head_init(list);
1138         }
1139 }
1140 
1141 /**
1142  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1143  *      @list: the new list to add
1144  *      @head: the place to add it in the first list
1145  */
1146 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1147                                          struct sk_buff_head *head)
1148 {
1149         if (!skb_queue_empty(list)) {
1150                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1151                 head->qlen += list->qlen;
1152         }
1153 }
1154 
1155 /**
1156  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1157  *      @list: the new list to add
1158  *      @head: the place to add it in the first list
1159  *
1160  *      Each of the lists is a queue.
1161  *      The list at @list is reinitialised
1162  */
1163 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1164                                               struct sk_buff_head *head)
1165 {
1166         if (!skb_queue_empty(list)) {
1167                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1168                 head->qlen += list->qlen;
1169                 __skb_queue_head_init(list);
1170         }
1171 }
1172 
1173 /**
1174  *      __skb_queue_after - queue a buffer at the list head
1175  *      @list: list to use
1176  *      @prev: place after this buffer
1177  *      @newsk: buffer to queue
1178  *
1179  *      Queue a buffer int the middle of a list. This function takes no locks
1180  *      and you must therefore hold required locks before calling it.
1181  *
1182  *      A buffer cannot be placed on two lists at the same time.
1183  */
1184 static inline void __skb_queue_after(struct sk_buff_head *list,
1185                                      struct sk_buff *prev,
1186                                      struct sk_buff *newsk)
1187 {
1188         __skb_insert(newsk, prev, prev->next, list);
1189 }
1190 
1191 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1192                 struct sk_buff_head *list);
1193 
1194 static inline void __skb_queue_before(struct sk_buff_head *list,
1195                                       struct sk_buff *next,
1196                                       struct sk_buff *newsk)
1197 {
1198         __skb_insert(newsk, next->prev, next, list);
1199 }
1200 
1201 /**
1202  *      __skb_queue_head - queue a buffer at the list head
1203  *      @list: list to use
1204  *      @newsk: buffer to queue
1205  *
1206  *      Queue a buffer at the start of a list. This function takes no locks
1207  *      and you must therefore hold required locks before calling it.
1208  *
1209  *      A buffer cannot be placed on two lists at the same time.
1210  */
1211 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1212 static inline void __skb_queue_head(struct sk_buff_head *list,
1213                                     struct sk_buff *newsk)
1214 {
1215         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1216 }
1217 
1218 /**
1219  *      __skb_queue_tail - queue a buffer at the list tail
1220  *      @list: list to use
1221  *      @newsk: buffer to queue
1222  *
1223  *      Queue a buffer at the end of a list. This function takes no locks
1224  *      and you must therefore hold required locks before calling it.
1225  *
1226  *      A buffer cannot be placed on two lists at the same time.
1227  */
1228 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1229 static inline void __skb_queue_tail(struct sk_buff_head *list,
1230                                    struct sk_buff *newsk)
1231 {
1232         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1233 }
1234 
1235 /*
1236  * remove sk_buff from list. _Must_ be called atomically, and with
1237  * the list known..
1238  */
1239 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1240 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1241 {
1242         struct sk_buff *next, *prev;
1243 
1244         list->qlen--;
1245         next       = skb->next;
1246         prev       = skb->prev;
1247         skb->next  = skb->prev = NULL;
1248         next->prev = prev;
1249         prev->next = next;
1250 }
1251 
1252 /**
1253  *      __skb_dequeue - remove from the head of the queue
1254  *      @list: list to dequeue from
1255  *
1256  *      Remove the head of the list. This function does not take any locks
1257  *      so must be used with appropriate locks held only. The head item is
1258  *      returned or %NULL if the list is empty.
1259  */
1260 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1261 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1262 {
1263         struct sk_buff *skb = skb_peek(list);
1264         if (skb)
1265                 __skb_unlink(skb, list);
1266         return skb;
1267 }
1268 
1269 /**
1270  *      __skb_dequeue_tail - remove from the tail of the queue
1271  *      @list: list to dequeue from
1272  *
1273  *      Remove the tail of the list. This function does not take any locks
1274  *      so must be used with appropriate locks held only. The tail item is
1275  *      returned or %NULL if the list is empty.
1276  */
1277 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1278 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1279 {
1280         struct sk_buff *skb = skb_peek_tail(list);
1281         if (skb)
1282                 __skb_unlink(skb, list);
1283         return skb;
1284 }
1285 
1286 
1287 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1288 {
1289         return skb->data_len;
1290 }
1291 
1292 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1293 {
1294         return skb->len - skb->data_len;
1295 }
1296 
1297 static inline int skb_pagelen(const struct sk_buff *skb)
1298 {
1299         int i, len = 0;
1300 
1301         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1302                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1303         return len + skb_headlen(skb);
1304 }
1305 
1306 /**
1307  * __skb_fill_page_desc - initialise a paged fragment in an skb
1308  * @skb: buffer containing fragment to be initialised
1309  * @i: paged fragment index to initialise
1310  * @page: the page to use for this fragment
1311  * @off: the offset to the data with @page
1312  * @size: the length of the data
1313  *
1314  * Initialises the @i'th fragment of @skb to point to &size bytes at
1315  * offset @off within @page.
1316  *
1317  * Does not take any additional reference on the fragment.
1318  */
1319 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1320                                         struct page *page, int off, int size)
1321 {
1322         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1323 
1324         /*
1325          * Propagate page->pfmemalloc to the skb if we can. The problem is
1326          * that not all callers have unique ownership of the page. If
1327          * pfmemalloc is set, we check the mapping as a mapping implies
1328          * page->index is set (index and pfmemalloc share space).
1329          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1330          * do not lose pfmemalloc information as the pages would not be
1331          * allocated using __GFP_MEMALLOC.
1332          */
1333         frag->page.p              = page;
1334         frag->page_offset         = off;
1335         skb_frag_size_set(frag, size);
1336 
1337         page = compound_head(page);
1338         if (page->pfmemalloc && !page->mapping)
1339                 skb->pfmemalloc = true;
1340 }
1341 
1342 /**
1343  * skb_fill_page_desc - initialise a paged fragment in an skb
1344  * @skb: buffer containing fragment to be initialised
1345  * @i: paged fragment index to initialise
1346  * @page: the page to use for this fragment
1347  * @off: the offset to the data with @page
1348  * @size: the length of the data
1349  *
1350  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1351  * @skb to point to @size bytes at offset @off within @page. In
1352  * addition updates @skb such that @i is the last fragment.
1353  *
1354  * Does not take any additional reference on the fragment.
1355  */
1356 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1357                                       struct page *page, int off, int size)
1358 {
1359         __skb_fill_page_desc(skb, i, page, off, size);
1360         skb_shinfo(skb)->nr_frags = i + 1;
1361 }
1362 
1363 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1364                      int size, unsigned int truesize);
1365 
1366 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1367                           unsigned int truesize);
1368 
1369 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1370 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1371 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1372 
1373 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1374 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1375 {
1376         return skb->head + skb->tail;
1377 }
1378 
1379 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1380 {
1381         skb->tail = skb->data - skb->head;
1382 }
1383 
1384 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1385 {
1386         skb_reset_tail_pointer(skb);
1387         skb->tail += offset;
1388 }
1389 
1390 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1391 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1392 {
1393         return skb->tail;
1394 }
1395 
1396 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1397 {
1398         skb->tail = skb->data;
1399 }
1400 
1401 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1402 {
1403         skb->tail = skb->data + offset;
1404 }
1405 
1406 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1407 
1408 /*
1409  *      Add data to an sk_buff
1410  */
1411 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1412 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1413 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1414 {
1415         unsigned char *tmp = skb_tail_pointer(skb);
1416         SKB_LINEAR_ASSERT(skb);
1417         skb->tail += len;
1418         skb->len  += len;
1419         return tmp;
1420 }
1421 
1422 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1423 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1424 {
1425         skb->data -= len;
1426         skb->len  += len;
1427         return skb->data;
1428 }
1429 
1430 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1431 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1432 {
1433         skb->len -= len;
1434         BUG_ON(skb->len < skb->data_len);
1435         return skb->data += len;
1436 }
1437 
1438 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1439 {
1440         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1441 }
1442 
1443 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1444 
1445 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1446 {
1447         if (len > skb_headlen(skb) &&
1448             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1449                 return NULL;
1450         skb->len -= len;
1451         return skb->data += len;
1452 }
1453 
1454 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1455 {
1456         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1457 }
1458 
1459 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1460 {
1461         if (likely(len <= skb_headlen(skb)))
1462                 return 1;
1463         if (unlikely(len > skb->len))
1464                 return 0;
1465         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1466 }
1467 
1468 /**
1469  *      skb_headroom - bytes at buffer head
1470  *      @skb: buffer to check
1471  *
1472  *      Return the number of bytes of free space at the head of an &sk_buff.
1473  */
1474 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1475 {
1476         return skb->data - skb->head;
1477 }
1478 
1479 /**
1480  *      skb_tailroom - bytes at buffer end
1481  *      @skb: buffer to check
1482  *
1483  *      Return the number of bytes of free space at the tail of an sk_buff
1484  */
1485 static inline int skb_tailroom(const struct sk_buff *skb)
1486 {
1487         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1488 }
1489 
1490 /**
1491  *      skb_availroom - bytes at buffer end
1492  *      @skb: buffer to check
1493  *
1494  *      Return the number of bytes of free space at the tail of an sk_buff
1495  *      allocated by sk_stream_alloc()
1496  */
1497 static inline int skb_availroom(const struct sk_buff *skb)
1498 {
1499         if (skb_is_nonlinear(skb))
1500                 return 0;
1501 
1502         return skb->end - skb->tail - skb->reserved_tailroom;
1503 }
1504 
1505 /**
1506  *      skb_reserve - adjust headroom
1507  *      @skb: buffer to alter
1508  *      @len: bytes to move
1509  *
1510  *      Increase the headroom of an empty &sk_buff by reducing the tail
1511  *      room. This is only allowed for an empty buffer.
1512  */
1513 static inline void skb_reserve(struct sk_buff *skb, int len)
1514 {
1515         skb->data += len;
1516         skb->tail += len;
1517 }
1518 
1519 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1520 {
1521         skb->inner_mac_header = skb->mac_header;
1522         skb->inner_network_header = skb->network_header;
1523         skb->inner_transport_header = skb->transport_header;
1524 }
1525 
1526 static inline void skb_reset_mac_len(struct sk_buff *skb)
1527 {
1528         skb->mac_len = skb->network_header - skb->mac_header;
1529 }
1530 
1531 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1532                                                         *skb)
1533 {
1534         return skb->head + skb->inner_transport_header;
1535 }
1536 
1537 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1538 {
1539         skb->inner_transport_header = skb->data - skb->head;
1540 }
1541 
1542 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1543                                                    const int offset)
1544 {
1545         skb_reset_inner_transport_header(skb);
1546         skb->inner_transport_header += offset;
1547 }
1548 
1549 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1550 {
1551         return skb->head + skb->inner_network_header;
1552 }
1553 
1554 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1555 {
1556         skb->inner_network_header = skb->data - skb->head;
1557 }
1558 
1559 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1560                                                 const int offset)
1561 {
1562         skb_reset_inner_network_header(skb);
1563         skb->inner_network_header += offset;
1564 }
1565 
1566 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1567 {
1568         return skb->head + skb->inner_mac_header;
1569 }
1570 
1571 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1572 {
1573         skb->inner_mac_header = skb->data - skb->head;
1574 }
1575 
1576 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1577                                             const int offset)
1578 {
1579         skb_reset_inner_mac_header(skb);
1580         skb->inner_mac_header += offset;
1581 }
1582 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1583 {
1584         return skb->transport_header != (typeof(skb->transport_header))~0U;
1585 }
1586 
1587 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1588 {
1589         return skb->head + skb->transport_header;
1590 }
1591 
1592 static inline void skb_reset_transport_header(struct sk_buff *skb)
1593 {
1594         skb->transport_header = skb->data - skb->head;
1595 }
1596 
1597 static inline void skb_set_transport_header(struct sk_buff *skb,
1598                                             const int offset)
1599 {
1600         skb_reset_transport_header(skb);
1601         skb->transport_header += offset;
1602 }
1603 
1604 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1605 {
1606         return skb->head + skb->network_header;
1607 }
1608 
1609 static inline void skb_reset_network_header(struct sk_buff *skb)
1610 {
1611         skb->network_header = skb->data - skb->head;
1612 }
1613 
1614 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1615 {
1616         skb_reset_network_header(skb);
1617         skb->network_header += offset;
1618 }
1619 
1620 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1621 {
1622         return skb->head + skb->mac_header;
1623 }
1624 
1625 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1626 {
1627         return skb->mac_header != (typeof(skb->mac_header))~0U;
1628 }
1629 
1630 static inline void skb_reset_mac_header(struct sk_buff *skb)
1631 {
1632         skb->mac_header = skb->data - skb->head;
1633 }
1634 
1635 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1636 {
1637         skb_reset_mac_header(skb);
1638         skb->mac_header += offset;
1639 }
1640 
1641 static inline void skb_pop_mac_header(struct sk_buff *skb)
1642 {
1643         skb->mac_header = skb->network_header;
1644 }
1645 
1646 static inline void skb_probe_transport_header(struct sk_buff *skb,
1647                                               const int offset_hint)
1648 {
1649         struct flow_keys keys;
1650 
1651         if (skb_transport_header_was_set(skb))
1652                 return;
1653         else if (skb_flow_dissect(skb, &keys))
1654                 skb_set_transport_header(skb, keys.thoff);
1655         else
1656                 skb_set_transport_header(skb, offset_hint);
1657 }
1658 
1659 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1660 {
1661         if (skb_mac_header_was_set(skb)) {
1662                 const unsigned char *old_mac = skb_mac_header(skb);
1663 
1664                 skb_set_mac_header(skb, -skb->mac_len);
1665                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1666         }
1667 }
1668 
1669 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1670 {
1671         return skb->csum_start - skb_headroom(skb);
1672 }
1673 
1674 static inline int skb_transport_offset(const struct sk_buff *skb)
1675 {
1676         return skb_transport_header(skb) - skb->data;
1677 }
1678 
1679 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1680 {
1681         return skb->transport_header - skb->network_header;
1682 }
1683 
1684 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1685 {
1686         return skb->inner_transport_header - skb->inner_network_header;
1687 }
1688 
1689 static inline int skb_network_offset(const struct sk_buff *skb)
1690 {
1691         return skb_network_header(skb) - skb->data;
1692 }
1693 
1694 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1695 {
1696         return skb_inner_network_header(skb) - skb->data;
1697 }
1698 
1699 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1700 {
1701         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1702 }
1703 
1704 /*
1705  * CPUs often take a performance hit when accessing unaligned memory
1706  * locations. The actual performance hit varies, it can be small if the
1707  * hardware handles it or large if we have to take an exception and fix it
1708  * in software.
1709  *
1710  * Since an ethernet header is 14 bytes network drivers often end up with
1711  * the IP header at an unaligned offset. The IP header can be aligned by
1712  * shifting the start of the packet by 2 bytes. Drivers should do this
1713  * with:
1714  *
1715  * skb_reserve(skb, NET_IP_ALIGN);
1716  *
1717  * The downside to this alignment of the IP header is that the DMA is now
1718  * unaligned. On some architectures the cost of an unaligned DMA is high
1719  * and this cost outweighs the gains made by aligning the IP header.
1720  *
1721  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1722  * to be overridden.
1723  */
1724 #ifndef NET_IP_ALIGN
1725 #define NET_IP_ALIGN    2
1726 #endif
1727 
1728 /*
1729  * The networking layer reserves some headroom in skb data (via
1730  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1731  * the header has to grow. In the default case, if the header has to grow
1732  * 32 bytes or less we avoid the reallocation.
1733  *
1734  * Unfortunately this headroom changes the DMA alignment of the resulting
1735  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1736  * on some architectures. An architecture can override this value,
1737  * perhaps setting it to a cacheline in size (since that will maintain
1738  * cacheline alignment of the DMA). It must be a power of 2.
1739  *
1740  * Various parts of the networking layer expect at least 32 bytes of
1741  * headroom, you should not reduce this.
1742  *
1743  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
1744  * to reduce average number of cache lines per packet.
1745  * get_rps_cpus() for example only access one 64 bytes aligned block :
1746  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
1747  */
1748 #ifndef NET_SKB_PAD
1749 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
1750 #endif
1751 
1752 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1753 
1754 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1755 {
1756         if (unlikely(skb_is_nonlinear(skb))) {
1757                 WARN_ON(1);
1758                 return;
1759         }
1760         skb->len = len;
1761         skb_set_tail_pointer(skb, len);
1762 }
1763 
1764 void skb_trim(struct sk_buff *skb, unsigned int len);
1765 
1766 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1767 {
1768         if (skb->data_len)
1769                 return ___pskb_trim(skb, len);
1770         __skb_trim(skb, len);
1771         return 0;
1772 }
1773 
1774 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1775 {
1776         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1777 }
1778 
1779 /**
1780  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1781  *      @skb: buffer to alter
1782  *      @len: new length
1783  *
1784  *      This is identical to pskb_trim except that the caller knows that
1785  *      the skb is not cloned so we should never get an error due to out-
1786  *      of-memory.
1787  */
1788 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1789 {
1790         int err = pskb_trim(skb, len);
1791         BUG_ON(err);
1792 }
1793 
1794 /**
1795  *      skb_orphan - orphan a buffer
1796  *      @skb: buffer to orphan
1797  *
1798  *      If a buffer currently has an owner then we call the owner's
1799  *      destructor function and make the @skb unowned. The buffer continues
1800  *      to exist but is no longer charged to its former owner.
1801  */
1802 static inline void skb_orphan(struct sk_buff *skb)
1803 {
1804         if (skb->destructor) {
1805                 skb->destructor(skb);
1806                 skb->destructor = NULL;
1807                 skb->sk         = NULL;
1808         } else {
1809                 BUG_ON(skb->sk);
1810         }
1811 }
1812 
1813 /**
1814  *      skb_orphan_frags - orphan the frags contained in a buffer
1815  *      @skb: buffer to orphan frags from
1816  *      @gfp_mask: allocation mask for replacement pages
1817  *
1818  *      For each frag in the SKB which needs a destructor (i.e. has an
1819  *      owner) create a copy of that frag and release the original
1820  *      page by calling the destructor.
1821  */
1822 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
1823 {
1824         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
1825                 return 0;
1826         return skb_copy_ubufs(skb, gfp_mask);
1827 }
1828 
1829 /**
1830  *      __skb_queue_purge - empty a list
1831  *      @list: list to empty
1832  *
1833  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
1834  *      the list and one reference dropped. This function does not take the
1835  *      list lock and the caller must hold the relevant locks to use it.
1836  */
1837 void skb_queue_purge(struct sk_buff_head *list);
1838 static inline void __skb_queue_purge(struct sk_buff_head *list)
1839 {
1840         struct sk_buff *skb;
1841         while ((skb = __skb_dequeue(list)) != NULL)
1842                 kfree_skb(skb);
1843 }
1844 
1845 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
1846 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
1847 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
1848 
1849 void *netdev_alloc_frag(unsigned int fragsz);
1850 
1851 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
1852                                    gfp_t gfp_mask);
1853 
1854 /**
1855  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
1856  *      @dev: network device to receive on
1857  *      @length: length to allocate
1858  *
1859  *      Allocate a new &sk_buff and assign it a usage count of one. The
1860  *      buffer has unspecified headroom built in. Users should allocate
1861  *      the headroom they think they need without accounting for the
1862  *      built in space. The built in space is used for optimisations.
1863  *
1864  *      %NULL is returned if there is no free memory. Although this function
1865  *      allocates memory it can be called from an interrupt.
1866  */
1867 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
1868                                                unsigned int length)
1869 {
1870         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
1871 }
1872 
1873 /* legacy helper around __netdev_alloc_skb() */
1874 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
1875                                               gfp_t gfp_mask)
1876 {
1877         return __netdev_alloc_skb(NULL, length, gfp_mask);
1878 }
1879 
1880 /* legacy helper around netdev_alloc_skb() */
1881 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1882 {
1883         return netdev_alloc_skb(NULL, length);
1884 }
1885 
1886 
1887 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
1888                 unsigned int length, gfp_t gfp)
1889 {
1890         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
1891 
1892         if (NET_IP_ALIGN && skb)
1893                 skb_reserve(skb, NET_IP_ALIGN);
1894         return skb;
1895 }
1896 
1897 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
1898                 unsigned int length)
1899 {
1900         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
1901 }
1902 
1903 /**
1904  *      __skb_alloc_pages - allocate pages for ps-rx on a skb and preserve pfmemalloc data
1905  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1906  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1907  *      @order: size of the allocation
1908  *
1909  *      Allocate a new page.
1910  *
1911  *      %NULL is returned if there is no free memory.
1912 */
1913 static inline struct page *__skb_alloc_pages(gfp_t gfp_mask,
1914                                               struct sk_buff *skb,
1915                                               unsigned int order)
1916 {
1917         struct page *page;
1918 
1919         gfp_mask |= __GFP_COLD;
1920 
1921         if (!(gfp_mask & __GFP_NOMEMALLOC))
1922                 gfp_mask |= __GFP_MEMALLOC;
1923 
1924         page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
1925         if (skb && page && page->pfmemalloc)
1926                 skb->pfmemalloc = true;
1927 
1928         return page;
1929 }
1930 
1931 /**
1932  *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
1933  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1934  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1935  *
1936  *      Allocate a new page.
1937  *
1938  *      %NULL is returned if there is no free memory.
1939  */
1940 static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
1941                                              struct sk_buff *skb)
1942 {
1943         return __skb_alloc_pages(gfp_mask, skb, 0);
1944 }
1945 
1946 /**
1947  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
1948  *      @page: The page that was allocated from skb_alloc_page
1949  *      @skb: The skb that may need pfmemalloc set
1950  */
1951 static inline void skb_propagate_pfmemalloc(struct page *page,
1952                                              struct sk_buff *skb)
1953 {
1954         if (page && page->pfmemalloc)
1955                 skb->pfmemalloc = true;
1956 }
1957 
1958 /**
1959  * skb_frag_page - retrieve the page refered to by a paged fragment
1960  * @frag: the paged fragment
1961  *
1962  * Returns the &struct page associated with @frag.
1963  */
1964 static inline struct page *skb_frag_page(const skb_frag_t *frag)
1965 {
1966         return frag->page.p;
1967 }
1968 
1969 /**
1970  * __skb_frag_ref - take an addition reference on a paged fragment.
1971  * @frag: the paged fragment
1972  *
1973  * Takes an additional reference on the paged fragment @frag.
1974  */
1975 static inline void __skb_frag_ref(skb_frag_t *frag)
1976 {
1977         get_page(skb_frag_page(frag));
1978 }
1979 
1980 /**
1981  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
1982  * @skb: the buffer
1983  * @f: the fragment offset.
1984  *
1985  * Takes an additional reference on the @f'th paged fragment of @skb.
1986  */
1987 static inline void skb_frag_ref(struct sk_buff *skb, int f)
1988 {
1989         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
1990 }
1991 
1992 /**
1993  * __skb_frag_unref - release a reference on a paged fragment.
1994  * @frag: the paged fragment
1995  *
1996  * Releases a reference on the paged fragment @frag.
1997  */
1998 static inline void __skb_frag_unref(skb_frag_t *frag)
1999 {
2000         put_page(skb_frag_page(frag));
2001 }
2002 
2003 /**
2004  * skb_frag_unref - release a reference on a paged fragment of an skb.
2005  * @skb: the buffer
2006  * @f: the fragment offset
2007  *
2008  * Releases a reference on the @f'th paged fragment of @skb.
2009  */
2010 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2011 {
2012         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2013 }
2014 
2015 /**
2016  * skb_frag_address - gets the address of the data contained in a paged fragment
2017  * @frag: the paged fragment buffer
2018  *
2019  * Returns the address of the data within @frag. The page must already
2020  * be mapped.
2021  */
2022 static inline void *skb_frag_address(const skb_frag_t *frag)
2023 {
2024         return page_address(skb_frag_page(frag)) + frag->page_offset;
2025 }
2026 
2027 /**
2028  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2029  * @frag: the paged fragment buffer
2030  *
2031  * Returns the address of the data within @frag. Checks that the page
2032  * is mapped and returns %NULL otherwise.
2033  */
2034 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2035 {
2036         void *ptr = page_address(skb_frag_page(frag));
2037         if (unlikely(!ptr))
2038                 return NULL;
2039 
2040         return ptr + frag->page_offset;
2041 }
2042 
2043 /**
2044  * __skb_frag_set_page - sets the page contained in a paged fragment
2045  * @frag: the paged fragment
2046  * @page: the page to set
2047  *
2048  * Sets the fragment @frag to contain @page.
2049  */
2050 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2051 {
2052         frag->page.p = page;
2053 }
2054 
2055 /**
2056  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2057  * @skb: the buffer
2058  * @f: the fragment offset
2059  * @page: the page to set
2060  *
2061  * Sets the @f'th fragment of @skb to contain @page.
2062  */
2063 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2064                                      struct page *page)
2065 {
2066         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2067 }
2068 
2069 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2070 
2071 /**
2072  * skb_frag_dma_map - maps a paged fragment via the DMA API
2073  * @dev: the device to map the fragment to
2074  * @frag: the paged fragment to map
2075  * @offset: the offset within the fragment (starting at the
2076  *          fragment's own offset)
2077  * @size: the number of bytes to map
2078  * @dir: the direction of the mapping (%PCI_DMA_*)
2079  *
2080  * Maps the page associated with @frag to @device.
2081  */
2082 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2083                                           const skb_frag_t *frag,
2084                                           size_t offset, size_t size,
2085                                           enum dma_data_direction dir)
2086 {
2087         return dma_map_page(dev, skb_frag_page(frag),
2088                             frag->page_offset + offset, size, dir);
2089 }
2090 
2091 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2092                                         gfp_t gfp_mask)
2093 {
2094         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2095 }
2096 
2097 /**
2098  *      skb_clone_writable - is the header of a clone writable
2099  *      @skb: buffer to check
2100  *      @len: length up to which to write
2101  *
2102  *      Returns true if modifying the header part of the cloned buffer
2103  *      does not requires the data to be copied.
2104  */
2105 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2106 {
2107         return !skb_header_cloned(skb) &&
2108                skb_headroom(skb) + len <= skb->hdr_len;
2109 }
2110 
2111 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2112                             int cloned)
2113 {
2114         int delta = 0;
2115 
2116         if (headroom > skb_headroom(skb))
2117                 delta = headroom - skb_headroom(skb);
2118 
2119         if (delta || cloned)
2120                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2121                                         GFP_ATOMIC);
2122         return 0;
2123 }
2124 
2125 /**
2126  *      skb_cow - copy header of skb when it is required
2127  *      @skb: buffer to cow
2128  *      @headroom: needed headroom
2129  *
2130  *      If the skb passed lacks sufficient headroom or its data part
2131  *      is shared, data is reallocated. If reallocation fails, an error
2132  *      is returned and original skb is not changed.
2133  *
2134  *      The result is skb with writable area skb->head...skb->tail
2135  *      and at least @headroom of space at head.
2136  */
2137 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2138 {
2139         return __skb_cow(skb, headroom, skb_cloned(skb));
2140 }
2141 
2142 /**
2143  *      skb_cow_head - skb_cow but only making the head writable
2144  *      @skb: buffer to cow
2145  *      @headroom: needed headroom
2146  *
2147  *      This function is identical to skb_cow except that we replace the
2148  *      skb_cloned check by skb_header_cloned.  It should be used when
2149  *      you only need to push on some header and do not need to modify
2150  *      the data.
2151  */
2152 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2153 {
2154         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2155 }
2156 
2157 /**
2158  *      skb_padto       - pad an skbuff up to a minimal size
2159  *      @skb: buffer to pad
2160  *      @len: minimal length
2161  *
2162  *      Pads up a buffer to ensure the trailing bytes exist and are
2163  *      blanked. If the buffer already contains sufficient data it
2164  *      is untouched. Otherwise it is extended. Returns zero on
2165  *      success. The skb is freed on error.
2166  */
2167  
2168 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2169 {
2170         unsigned int size = skb->len;
2171         if (likely(size >= len))
2172                 return 0;
2173         return skb_pad(skb, len - size);
2174 }
2175 
2176 static inline int skb_add_data(struct sk_buff *skb,
2177                                char __user *from, int copy)
2178 {
2179         const int off = skb->len;
2180 
2181         if (skb->ip_summed == CHECKSUM_NONE) {
2182                 int err = 0;
2183                 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2184                                                             copy, 0, &err);
2185                 if (!err) {
2186                         skb->csum = csum_block_add(skb->csum, csum, off);
2187                         return 0;
2188                 }
2189         } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2190                 return 0;
2191 
2192         __skb_trim(skb, off);
2193         return -EFAULT;
2194 }
2195 
2196 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2197                                     const struct page *page, int off)
2198 {
2199         if (i) {
2200                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2201 
2202                 return page == skb_frag_page(frag) &&
2203                        off == frag->page_offset + skb_frag_size(frag);
2204         }
2205         return false;
2206 }
2207 
2208 static inline int __skb_linearize(struct sk_buff *skb)
2209 {
2210         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2211 }
2212 
2213 /**
2214  *      skb_linearize - convert paged skb to linear one
2215  *      @skb: buffer to linarize
2216  *
2217  *      If there is no free memory -ENOMEM is returned, otherwise zero
2218  *      is returned and the old skb data released.
2219  */
2220 static inline int skb_linearize(struct sk_buff *skb)
2221 {
2222         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2223 }
2224 
2225 /**
2226  * skb_has_shared_frag - can any frag be overwritten
2227  * @skb: buffer to test
2228  *
2229  * Return true if the skb has at least one frag that might be modified
2230  * by an external entity (as in vmsplice()/sendfile())
2231  */
2232 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2233 {
2234         return skb_is_nonlinear(skb) &&
2235                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2236 }
2237 
2238 /**
2239  *      skb_linearize_cow - make sure skb is linear and writable
2240  *      @skb: buffer to process
2241  *
2242  *      If there is no free memory -ENOMEM is returned, otherwise zero
2243  *      is returned and the old skb data released.
2244  */
2245 static inline int skb_linearize_cow(struct sk_buff *skb)
2246 {
2247         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2248                __skb_linearize(skb) : 0;
2249 }
2250 
2251 /**
2252  *      skb_postpull_rcsum - update checksum for received skb after pull
2253  *      @skb: buffer to update
2254  *      @start: start of data before pull
2255  *      @len: length of data pulled
2256  *
2257  *      After doing a pull on a received packet, you need to call this to
2258  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2259  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2260  */
2261 
2262 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2263                                       const void *start, unsigned int len)
2264 {
2265         if (skb->ip_summed == CHECKSUM_COMPLETE)
2266                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2267 }
2268 
2269 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2270 
2271 /**
2272  *      pskb_trim_rcsum - trim received skb and update checksum
2273  *      @skb: buffer to trim
2274  *      @len: new length
2275  *
2276  *      This is exactly the same as pskb_trim except that it ensures the
2277  *      checksum of received packets are still valid after the operation.
2278  */
2279 
2280 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2281 {
2282         if (likely(len >= skb->len))
2283                 return 0;
2284         if (skb->ip_summed == CHECKSUM_COMPLETE)
2285                 skb->ip_summed = CHECKSUM_NONE;
2286         return __pskb_trim(skb, len);
2287 }
2288 
2289 #define skb_queue_walk(queue, skb) \
2290                 for (skb = (queue)->next;                                       \
2291                      skb != (struct sk_buff *)(queue);                          \
2292                      skb = skb->next)
2293 
2294 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2295                 for (skb = (queue)->next, tmp = skb->next;                      \
2296                      skb != (struct sk_buff *)(queue);                          \
2297                      skb = tmp, tmp = skb->next)
2298 
2299 #define skb_queue_walk_from(queue, skb)                                         \
2300                 for (; skb != (struct sk_buff *)(queue);                        \
2301                      skb = skb->next)
2302 
2303 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2304                 for (tmp = skb->next;                                           \
2305                      skb != (struct sk_buff *)(queue);                          \
2306                      skb = tmp, tmp = skb->next)
2307 
2308 #define skb_queue_reverse_walk(queue, skb) \
2309                 for (skb = (queue)->prev;                                       \
2310                      skb != (struct sk_buff *)(queue);                          \
2311                      skb = skb->prev)
2312 
2313 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2314                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2315                      skb != (struct sk_buff *)(queue);                          \
2316                      skb = tmp, tmp = skb->prev)
2317 
2318 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2319                 for (tmp = skb->prev;                                           \
2320                      skb != (struct sk_buff *)(queue);                          \
2321                      skb = tmp, tmp = skb->prev)
2322 
2323 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2324 {
2325         return skb_shinfo(skb)->frag_list != NULL;
2326 }
2327 
2328 static inline void skb_frag_list_init(struct sk_buff *skb)
2329 {
2330         skb_shinfo(skb)->frag_list = NULL;
2331 }
2332 
2333 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2334 {
2335         frag->next = skb_shinfo(skb)->frag_list;
2336         skb_shinfo(skb)->frag_list = frag;
2337 }
2338 
2339 #define skb_walk_frags(skb, iter)       \
2340         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2341 
2342 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2343                                     int *peeked, int *off, int *err);
2344 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2345                                   int *err);
2346 unsigned int datagram_poll(struct file *file, struct socket *sock,
2347                            struct poll_table_struct *wait);
2348 int skb_copy_datagram_iovec(const struct sk_buff *from, int offset,
2349                             struct iovec *to, int size);
2350 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, int hlen,
2351                                      struct iovec *iov);
2352 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
2353                                  const struct iovec *from, int from_offset,
2354                                  int len);
2355 int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
2356                            int offset, size_t count);
2357 int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset,
2358                                   const struct iovec *to, int to_offset,
2359                                   int size);
2360 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2361 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2362 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2363 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2364 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2365 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2366                               int len, __wsum csum);
2367 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
2368                     struct pipe_inode_info *pipe, unsigned int len,
2369                     unsigned int flags);
2370 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2371 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2372 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2373 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2374 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2375 
2376 struct skb_checksum_ops {
2377         __wsum (*update)(const void *mem, int len, __wsum wsum);
2378         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2379 };
2380 
2381 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2382                       __wsum csum, const struct skb_checksum_ops *ops);
2383 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2384                     __wsum csum);
2385 
2386 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2387                                        int len, void *buffer)
2388 {
2389         int hlen = skb_headlen(skb);
2390 
2391         if (hlen - offset >= len)
2392                 return skb->data + offset;
2393 
2394         if (skb_copy_bits(skb, offset, buffer, len) < 0)
2395                 return NULL;
2396 
2397         return buffer;
2398 }
2399 
2400 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2401                                              void *to,
2402                                              const unsigned int len)
2403 {
2404         memcpy(to, skb->data, len);
2405 }
2406 
2407 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2408                                                     const int offset, void *to,
2409                                                     const unsigned int len)
2410 {
2411         memcpy(to, skb->data + offset, len);
2412 }
2413 
2414 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2415                                            const void *from,
2416                                            const unsigned int len)
2417 {
2418         memcpy(skb->data, from, len);
2419 }
2420 
2421 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2422                                                   const int offset,
2423                                                   const void *from,
2424                                                   const unsigned int len)
2425 {
2426         memcpy(skb->data + offset, from, len);
2427 }
2428 
2429 void skb_init(void);
2430 
2431 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2432 {
2433         return skb->tstamp;
2434 }
2435 
2436 /**
2437  *      skb_get_timestamp - get timestamp from a skb
2438  *      @skb: skb to get stamp from
2439  *      @stamp: pointer to struct timeval to store stamp in
2440  *
2441  *      Timestamps are stored in the skb as offsets to a base timestamp.
2442  *      This function converts the offset back to a struct timeval and stores
2443  *      it in stamp.
2444  */
2445 static inline void skb_get_timestamp(const struct sk_buff *skb,
2446                                      struct timeval *stamp)
2447 {
2448         *stamp = ktime_to_timeval(skb->tstamp);
2449 }
2450 
2451 static inline void skb_get_timestampns(const struct sk_buff *skb,
2452                                        struct timespec *stamp)
2453 {
2454         *stamp = ktime_to_timespec(skb->tstamp);
2455 }
2456 
2457 static inline void __net_timestamp(struct sk_buff *skb)
2458 {
2459         skb->tstamp = ktime_get_real();
2460 }
2461 
2462 static inline ktime_t net_timedelta(ktime_t t)
2463 {
2464         return ktime_sub(ktime_get_real(), t);
2465 }
2466 
2467 static inline ktime_t net_invalid_timestamp(void)
2468 {
2469         return ktime_set(0, 0);
2470 }
2471 
2472 void skb_timestamping_init(void);
2473 
2474 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2475 
2476 void skb_clone_tx_timestamp(struct sk_buff *skb);
2477 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2478 
2479 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2480 
2481 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2482 {
2483 }
2484 
2485 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2486 {
2487         return false;
2488 }
2489 
2490 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2491 
2492 /**
2493  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2494  *
2495  * PHY drivers may accept clones of transmitted packets for
2496  * timestamping via their phy_driver.txtstamp method. These drivers
2497  * must call this function to return the skb back to the stack, with
2498  * or without a timestamp.
2499  *
2500  * @skb: clone of the the original outgoing packet
2501  * @hwtstamps: hardware time stamps, may be NULL if not available
2502  *
2503  */
2504 void skb_complete_tx_timestamp(struct sk_buff *skb,
2505                                struct skb_shared_hwtstamps *hwtstamps);
2506 
2507 /**
2508  * skb_tstamp_tx - queue clone of skb with send time stamps
2509  * @orig_skb:   the original outgoing packet
2510  * @hwtstamps:  hardware time stamps, may be NULL if not available
2511  *
2512  * If the skb has a socket associated, then this function clones the
2513  * skb (thus sharing the actual data and optional structures), stores
2514  * the optional hardware time stamping information (if non NULL) or
2515  * generates a software time stamp (otherwise), then queues the clone
2516  * to the error queue of the socket.  Errors are silently ignored.
2517  */
2518 void skb_tstamp_tx(struct sk_buff *orig_skb,
2519                    struct skb_shared_hwtstamps *hwtstamps);
2520 
2521 static inline void sw_tx_timestamp(struct sk_buff *skb)
2522 {
2523         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2524             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2525                 skb_tstamp_tx(skb, NULL);
2526 }
2527 
2528 /**
2529  * skb_tx_timestamp() - Driver hook for transmit timestamping
2530  *
2531  * Ethernet MAC Drivers should call this function in their hard_xmit()
2532  * function immediately before giving the sk_buff to the MAC hardware.
2533  *
2534  * Specifically, one should make absolutely sure that this function is
2535  * called before TX completion of this packet can trigger.  Otherwise
2536  * the packet could potentially already be freed.
2537  *
2538  * @skb: A socket buffer.
2539  */
2540 static inline void skb_tx_timestamp(struct sk_buff *skb)
2541 {
2542         skb_clone_tx_timestamp(skb);
2543         sw_tx_timestamp(skb);
2544 }
2545 
2546 /**
2547  * skb_complete_wifi_ack - deliver skb with wifi status
2548  *
2549  * @skb: the original outgoing packet
2550  * @acked: ack status
2551  *
2552  */
2553 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2554 
2555 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2556 __sum16 __skb_checksum_complete(struct sk_buff *skb);
2557 
2558 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2559 {
2560         return skb->ip_summed & CHECKSUM_UNNECESSARY;
2561 }
2562 
2563 /**
2564  *      skb_checksum_complete - Calculate checksum of an entire packet
2565  *      @skb: packet to process
2566  *
2567  *      This function calculates the checksum over the entire packet plus
2568  *      the value of skb->csum.  The latter can be used to supply the
2569  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2570  *      checksum.
2571  *
2572  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2573  *      this function can be used to verify that checksum on received
2574  *      packets.  In that case the function should return zero if the
2575  *      checksum is correct.  In particular, this function will return zero
2576  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2577  *      hardware has already verified the correctness of the checksum.
2578  */
2579 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2580 {
2581         return skb_csum_unnecessary(skb) ?
2582                0 : __skb_checksum_complete(skb);
2583 }
2584 
2585 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2586 void nf_conntrack_destroy(struct nf_conntrack *nfct);
2587 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
2588 {
2589         if (nfct && atomic_dec_and_test(&nfct->use))
2590                 nf_conntrack_destroy(nfct);
2591 }
2592 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
2593 {
2594         if (nfct)
2595                 atomic_inc(&nfct->use);
2596 }
2597 #endif
2598 #ifdef CONFIG_BRIDGE_NETFILTER
2599 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
2600 {
2601         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
2602                 kfree(nf_bridge);
2603 }
2604 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
2605 {
2606         if (nf_bridge)
2607                 atomic_inc(&nf_bridge->use);
2608 }
2609 #endif /* CONFIG_BRIDGE_NETFILTER */
2610 static inline void nf_reset(struct sk_buff *skb)
2611 {
2612 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2613         nf_conntrack_put(skb->nfct);
2614         skb->nfct = NULL;
2615 #endif
2616 #ifdef CONFIG_BRIDGE_NETFILTER
2617         nf_bridge_put(skb->nf_bridge);
2618         skb->nf_bridge = NULL;
2619 #endif
2620 }
2621 
2622 static inline void nf_reset_trace(struct sk_buff *skb)
2623 {
2624 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
2625         skb->nf_trace = 0;
2626 #endif
2627 }
2628 
2629 /* Note: This doesn't put any conntrack and bridge info in dst. */
2630 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2631 {
2632 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2633         dst->nfct = src->nfct;
2634         nf_conntrack_get(src->nfct);
2635         dst->nfctinfo = src->nfctinfo;
2636 #endif
2637 #ifdef CONFIG_BRIDGE_NETFILTER
2638         dst->nf_bridge  = src->nf_bridge;
2639         nf_bridge_get(src->nf_bridge);
2640 #endif
2641 }
2642 
2643 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2644 {
2645 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2646         nf_conntrack_put(dst->nfct);
2647 #endif
2648 #ifdef CONFIG_BRIDGE_NETFILTER
2649         nf_bridge_put(dst->nf_bridge);
2650 #endif
2651         __nf_copy(dst, src);
2652 }
2653 
2654 #ifdef CONFIG_NETWORK_SECMARK
2655 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2656 {
2657         to->secmark = from->secmark;
2658 }
2659 
2660 static inline void skb_init_secmark(struct sk_buff *skb)
2661 {
2662         skb->secmark = 0;
2663 }
2664 #else
2665 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2666 { }
2667 
2668 static inline void skb_init_secmark(struct sk_buff *skb)
2669 { }
2670 #endif
2671 
2672 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
2673 {
2674         skb->queue_mapping = queue_mapping;
2675 }
2676 
2677 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2678 {
2679         return skb->queue_mapping;
2680 }
2681 
2682 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
2683 {
2684         to->queue_mapping = from->queue_mapping;
2685 }
2686 
2687 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
2688 {
2689         skb->queue_mapping = rx_queue + 1;
2690 }
2691 
2692 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
2693 {
2694         return skb->queue_mapping - 1;
2695 }
2696 
2697 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
2698 {
2699         return skb->queue_mapping != 0;
2700 }
2701 
2702 u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
2703                   unsigned int num_tx_queues);
2704 
2705 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2706 {
2707 #ifdef CONFIG_XFRM
2708         return skb->sp;
2709 #else
2710         return NULL;
2711 #endif
2712 }
2713 
2714 /* Keeps track of mac header offset relative to skb->head.
2715  * It is useful for TSO of Tunneling protocol. e.g. GRE.
2716  * For non-tunnel skb it points to skb_mac_header() and for
2717  * tunnel skb it points to outer mac header.
2718  * Keeps track of level of encapsulation of network headers.
2719  */
2720 struct skb_gso_cb {
2721         int     mac_offset;
2722         int     encap_level;
2723 };
2724 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
2725 
2726 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
2727 {
2728         return (skb_mac_header(inner_skb) - inner_skb->head) -
2729                 SKB_GSO_CB(inner_skb)->mac_offset;
2730 }
2731 
2732 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
2733 {
2734         int new_headroom, headroom;
2735         int ret;
2736 
2737         headroom = skb_headroom(skb);
2738         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
2739         if (ret)
2740                 return ret;
2741 
2742         new_headroom = skb_headroom(skb);
2743         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
2744         return 0;
2745 }
2746 
2747 static inline bool skb_is_gso(const struct sk_buff *skb)
2748 {
2749         return skb_shinfo(skb)->gso_size;
2750 }
2751 
2752 /* Note: Should be called only if skb_is_gso(skb) is true */
2753 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
2754 {
2755         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
2756 }
2757 
2758 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
2759 
2760 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
2761 {
2762         /* LRO sets gso_size but not gso_type, whereas if GSO is really
2763          * wanted then gso_type will be set. */
2764         const struct skb_shared_info *shinfo = skb_shinfo(skb);
2765 
2766         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
2767             unlikely(shinfo->gso_type == 0)) {
2768                 __skb_warn_lro_forwarding(skb);
2769                 return true;
2770         }
2771         return false;
2772 }
2773 
2774 static inline void skb_forward_csum(struct sk_buff *skb)
2775 {
2776         /* Unfortunately we don't support this one.  Any brave souls? */
2777         if (skb->ip_summed == CHECKSUM_COMPLETE)
2778                 skb->ip_summed = CHECKSUM_NONE;
2779 }
2780 
2781 /**
2782  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
2783  * @skb: skb to check
2784  *
2785  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
2786  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
2787  * use this helper, to document places where we make this assertion.
2788  */
2789 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
2790 {
2791 #ifdef DEBUG
2792         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
2793 #endif
2794 }
2795 
2796 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
2797 
2798 u32 __skb_get_poff(const struct sk_buff *skb);
2799 
2800 /**
2801  * skb_head_is_locked - Determine if the skb->head is locked down
2802  * @skb: skb to check
2803  *
2804  * The head on skbs build around a head frag can be removed if they are
2805  * not cloned.  This function returns true if the skb head is locked down
2806  * due to either being allocated via kmalloc, or by being a clone with
2807  * multiple references to the head.
2808  */
2809 static inline bool skb_head_is_locked(const struct sk_buff *skb)
2810 {
2811         return !skb->head_frag || skb_cloned(skb);
2812 }
2813 #endif  /* __KERNEL__ */
2814 #endif  /* _LINUX_SKBUFF_H */
2815 

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