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

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  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 
 24 #include <linux/atomic.h>
 25 #include <asm/types.h>
 26 #include <linux/spinlock.h>
 27 #include <linux/net.h>
 28 #include <linux/textsearch.h>
 29 #include <net/checksum.h>
 30 #include <linux/rcupdate.h>
 31 #include <linux/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 extern int sysctl_max_skb_frags;
153 
154 typedef struct skb_frag_struct skb_frag_t;
155 
156 struct skb_frag_struct {
157         struct {
158                 struct page *p;
159         } page;
160 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
161         __u32 page_offset;
162         __u32 size;
163 #else
164         __u16 page_offset;
165         __u16 size;
166 #endif
167 };
168 
169 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
170 {
171         return frag->size;
172 }
173 
174 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
175 {
176         frag->size = size;
177 }
178 
179 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
180 {
181         frag->size += delta;
182 }
183 
184 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
185 {
186         frag->size -= delta;
187 }
188 
189 #define HAVE_HW_TIME_STAMP
190 
191 /**
192  * struct skb_shared_hwtstamps - hardware time stamps
193  * @hwtstamp:   hardware time stamp transformed into duration
194  *              since arbitrary point in time
195  * @syststamp:  hwtstamp transformed to system time base
196  *
197  * Software time stamps generated by ktime_get_real() are stored in
198  * skb->tstamp. The relation between the different kinds of time
199  * stamps is as follows:
200  *
201  * syststamp and tstamp can be compared against each other in
202  * arbitrary combinations.  The accuracy of a
203  * syststamp/tstamp/"syststamp from other device" comparison is
204  * limited by the accuracy of the transformation into system time
205  * base. This depends on the device driver and its underlying
206  * hardware.
207  *
208  * hwtstamps can only be compared against other hwtstamps from
209  * the same device.
210  *
211  * This structure is attached to packets as part of the
212  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
213  */
214 struct skb_shared_hwtstamps {
215         ktime_t hwtstamp;
216         ktime_t syststamp;
217 };
218 
219 /* Definitions for tx_flags in struct skb_shared_info */
220 enum {
221         /* generate hardware time stamp */
222         SKBTX_HW_TSTAMP = 1 << 0,
223 
224         /* generate software time stamp */
225         SKBTX_SW_TSTAMP = 1 << 1,
226 
227         /* device driver is going to provide hardware time stamp */
228         SKBTX_IN_PROGRESS = 1 << 2,
229 
230         /* device driver supports TX zero-copy buffers */
231         SKBTX_DEV_ZEROCOPY = 1 << 3,
232 
233         /* generate wifi status information (where possible) */
234         SKBTX_WIFI_STATUS = 1 << 4,
235 
236         /* This indicates at least one fragment might be overwritten
237          * (as in vmsplice(), sendfile() ...)
238          * If we need to compute a TX checksum, we'll need to copy
239          * all frags to avoid possible bad checksum
240          */
241         SKBTX_SHARED_FRAG = 1 << 5,
242 };
243 
244 /*
245  * The callback notifies userspace to release buffers when skb DMA is done in
246  * lower device, the skb last reference should be 0 when calling this.
247  * The zerocopy_success argument is true if zero copy transmit occurred,
248  * false on data copy or out of memory error caused by data copy attempt.
249  * The ctx field is used to track device context.
250  * The desc field is used to track userspace buffer index.
251  */
252 struct ubuf_info {
253         void (*callback)(struct ubuf_info *, bool zerocopy_success);
254         void *ctx;
255         unsigned long desc;
256 };
257 
258 /* This data is invariant across clones and lives at
259  * the end of the header data, ie. at skb->end.
260  */
261 struct skb_shared_info {
262         unsigned char   nr_frags;
263         __u8            tx_flags;
264         unsigned short  gso_size;
265         /* Warning: this field is not always filled in (UFO)! */
266         unsigned short  gso_segs;
267         unsigned short  gso_type;
268         struct sk_buff  *frag_list;
269         struct skb_shared_hwtstamps hwtstamps;
270         __be32          ip6_frag_id;
271 
272         /*
273          * Warning : all fields before dataref are cleared in __alloc_skb()
274          */
275         atomic_t        dataref;
276 
277         /* Intermediate layers must ensure that destructor_arg
278          * remains valid until skb destructor */
279         void *          destructor_arg;
280 
281         /* must be last field, see pskb_expand_head() */
282         skb_frag_t      frags[MAX_SKB_FRAGS];
283 };
284 
285 /* We divide dataref into two halves.  The higher 16 bits hold references
286  * to the payload part of skb->data.  The lower 16 bits hold references to
287  * the entire skb->data.  A clone of a headerless skb holds the length of
288  * the header in skb->hdr_len.
289  *
290  * All users must obey the rule that the skb->data reference count must be
291  * greater than or equal to the payload reference count.
292  *
293  * Holding a reference to the payload part means that the user does not
294  * care about modifications to the header part of skb->data.
295  */
296 #define SKB_DATAREF_SHIFT 16
297 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
298 
299 
300 enum {
301         SKB_FCLONE_UNAVAILABLE,
302         SKB_FCLONE_ORIG,
303         SKB_FCLONE_CLONE,
304 };
305 
306 enum {
307         SKB_GSO_TCPV4 = 1 << 0,
308         SKB_GSO_UDP = 1 << 1,
309 
310         /* This indicates the skb is from an untrusted source. */
311         SKB_GSO_DODGY = 1 << 2,
312 
313         /* This indicates the tcp segment has CWR set. */
314         SKB_GSO_TCP_ECN = 1 << 3,
315 
316         SKB_GSO_TCPV6 = 1 << 4,
317 
318         SKB_GSO_FCOE = 1 << 5,
319 
320         SKB_GSO_GRE = 1 << 6,
321 
322         SKB_GSO_UDP_TUNNEL = 1 << 7,
323 
324         SKB_GSO_MPLS = 1 << 8,
325 };
326 
327 #if BITS_PER_LONG > 32
328 #define NET_SKBUFF_DATA_USES_OFFSET 1
329 #endif
330 
331 #ifdef NET_SKBUFF_DATA_USES_OFFSET
332 typedef unsigned int sk_buff_data_t;
333 #else
334 typedef unsigned char *sk_buff_data_t;
335 #endif
336 
337 /** 
338  *      struct sk_buff - socket buffer
339  *      @next: Next buffer in list
340  *      @prev: Previous buffer in list
341  *      @tstamp: Time we arrived
342  *      @sk: Socket we are owned by
343  *      @dev: Device we arrived on/are leaving by
344  *      @cb: Control buffer. Free for use by every layer. Put private vars here
345  *      @_skb_refdst: destination entry (with norefcount bit)
346  *      @sp: the security path, used for xfrm
347  *      @len: Length of actual data
348  *      @data_len: Data length
349  *      @mac_len: Length of link layer header
350  *      @hdr_len: writable header length of cloned skb
351  *      @csum: Checksum (must include start/offset pair)
352  *      @csum_start: Offset from skb->head where checksumming should start
353  *      @csum_offset: Offset from csum_start where checksum should be stored
354  *      @priority: Packet queueing priority
355  *      @local_df: allow local fragmentation
356  *      @cloned: Head may be cloned (check refcnt to be sure)
357  *      @ip_summed: Driver fed us an IP checksum
358  *      @nohdr: Payload reference only, must not modify header
359  *      @nfctinfo: Relationship of this skb to the connection
360  *      @pkt_type: Packet class
361  *      @fclone: skbuff clone status
362  *      @ipvs_property: skbuff is owned by ipvs
363  *      @peeked: this packet has been seen already, so stats have been
364  *              done for it, don't do them again
365  *      @nf_trace: netfilter packet trace flag
366  *      @protocol: Packet protocol from driver
367  *      @destructor: Destruct function
368  *      @nfct: Associated connection, if any
369  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
370  *      @skb_iif: ifindex of device we arrived on
371  *      @tc_index: Traffic control index
372  *      @tc_verd: traffic control verdict
373  *      @rxhash: the packet hash computed on receive
374  *      @queue_mapping: Queue mapping for multiqueue devices
375  *      @ndisc_nodetype: router type (from link layer)
376  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
377  *      @l4_rxhash: indicate rxhash is a canonical 4-tuple hash over transport
378  *              ports.
379  *      @wifi_acked_valid: wifi_acked was set
380  *      @wifi_acked: whether frame was acked on wifi or not
381  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
382  *      @dma_cookie: a cookie to one of several possible DMA operations
383  *              done by skb DMA functions
384   *     @napi_id: id of the NAPI struct this skb came from
385  *      @secmark: security marking
386  *      @mark: Generic packet mark
387  *      @dropcount: total number of sk_receive_queue overflows
388  *      @vlan_proto: vlan encapsulation protocol
389  *      @vlan_tci: vlan tag control information
390  *      @inner_protocol: Protocol (encapsulation)
391  *      @inner_transport_header: Inner transport layer header (encapsulation)
392  *      @inner_network_header: Network layer header (encapsulation)
393  *      @inner_mac_header: Link layer header (encapsulation)
394  *      @transport_header: Transport layer header
395  *      @network_header: Network layer header
396  *      @mac_header: Link layer header
397  *      @tail: Tail pointer
398  *      @end: End pointer
399  *      @head: Head of buffer
400  *      @data: Data head pointer
401  *      @truesize: Buffer size
402  *      @users: User count - see {datagram,tcp}.c
403  */
404 
405 struct sk_buff {
406         /* These two members must be first. */
407         struct sk_buff          *next;
408         struct sk_buff          *prev;
409 
410         ktime_t                 tstamp;
411 
412         struct sock             *sk;
413         struct net_device       *dev;
414 
415         /*
416          * This is the control buffer. It is free to use for every
417          * layer. Please put your private variables there. If you
418          * want to keep them across layers you have to do a skb_clone()
419          * first. This is owned by whoever has the skb queued ATM.
420          */
421         char                    cb[48] __aligned(8);
422 
423         unsigned long           _skb_refdst;
424 #ifdef CONFIG_XFRM
425         struct  sec_path        *sp;
426 #endif
427         unsigned int            len,
428                                 data_len;
429         __u16                   mac_len,
430                                 hdr_len;
431         union {
432                 __wsum          csum;
433                 struct {
434                         __u16   csum_start;
435                         __u16   csum_offset;
436                 };
437         };
438         __u32                   priority;
439         kmemcheck_bitfield_begin(flags1);
440         __u8                    local_df:1,
441                                 cloned:1,
442                                 ip_summed:2,
443                                 nohdr:1,
444                                 nfctinfo:3;
445         __u8                    pkt_type:3,
446                                 fclone:2,
447                                 ipvs_property:1,
448                                 peeked:1,
449                                 nf_trace:1;
450         kmemcheck_bitfield_end(flags1);
451         __be16                  protocol;
452 
453         void                    (*destructor)(struct sk_buff *skb);
454 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
455         struct nf_conntrack     *nfct;
456 #endif
457 #ifdef CONFIG_BRIDGE_NETFILTER
458         struct nf_bridge_info   *nf_bridge;
459 #endif
460 
461         int                     skb_iif;
462 
463         __u32                   rxhash;
464 
465         __be16                  vlan_proto;
466         __u16                   vlan_tci;
467 
468 #ifdef CONFIG_NET_SCHED
469         __u16                   tc_index;       /* traffic control index */
470 #ifdef CONFIG_NET_CLS_ACT
471         __u16                   tc_verd;        /* traffic control verdict */
472 #endif
473 #endif
474 
475         __u16                   queue_mapping;
476         kmemcheck_bitfield_begin(flags2);
477 #ifdef CONFIG_IPV6_NDISC_NODETYPE
478         __u8                    ndisc_nodetype:2;
479 #endif
480         __u8                    pfmemalloc:1;
481         __u8                    ooo_okay:1;
482         __u8                    l4_rxhash:1;
483         __u8                    wifi_acked_valid:1;
484         __u8                    wifi_acked:1;
485         __u8                    no_fcs:1;
486         __u8                    head_frag:1;
487         /* Encapsulation protocol and NIC drivers should use
488          * this flag to indicate to each other if the skb contains
489          * encapsulated packet or not and maybe use the inner packet
490          * headers if needed
491          */
492         __u8                    encapsulation:1;
493         /* 6/8 bit hole (depending on ndisc_nodetype presence) */
494         kmemcheck_bitfield_end(flags2);
495 
496 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
497         union {
498                 unsigned int    napi_id;
499                 dma_cookie_t    dma_cookie;
500         };
501 #endif
502 #ifdef CONFIG_NETWORK_SECMARK
503         __u32                   secmark;
504 #endif
505         union {
506                 __u32           mark;
507                 __u32           dropcount;
508                 __u32           reserved_tailroom;
509         };
510 
511         __be16                  inner_protocol;
512         __u16                   inner_transport_header;
513         __u16                   inner_network_header;
514         __u16                   inner_mac_header;
515         __u16                   transport_header;
516         __u16                   network_header;
517         __u16                   mac_header;
518         /* These elements must be at the end, see alloc_skb() for details.  */
519         sk_buff_data_t          tail;
520         sk_buff_data_t          end;
521         unsigned char           *head,
522                                 *data;
523         unsigned int            truesize;
524         atomic_t                users;
525 };
526 
527 #ifdef __KERNEL__
528 /*
529  *      Handling routines are only of interest to the kernel
530  */
531 #include <linux/slab.h>
532 
533 
534 #define SKB_ALLOC_FCLONE        0x01
535 #define SKB_ALLOC_RX            0x02
536 
537 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
538 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
539 {
540         return unlikely(skb->pfmemalloc);
541 }
542 
543 /*
544  * skb might have a dst pointer attached, refcounted or not.
545  * _skb_refdst low order bit is set if refcount was _not_ taken
546  */
547 #define SKB_DST_NOREF   1UL
548 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
549 
550 /**
551  * skb_dst - returns skb dst_entry
552  * @skb: buffer
553  *
554  * Returns skb dst_entry, regardless of reference taken or not.
555  */
556 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
557 {
558         /* If refdst was not refcounted, check we still are in a 
559          * rcu_read_lock section
560          */
561         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
562                 !rcu_read_lock_held() &&
563                 !rcu_read_lock_bh_held());
564         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
565 }
566 
567 /**
568  * skb_dst_set - sets skb dst
569  * @skb: buffer
570  * @dst: dst entry
571  *
572  * Sets skb dst, assuming a reference was taken on dst and should
573  * be released by skb_dst_drop()
574  */
575 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
576 {
577         skb->_skb_refdst = (unsigned long)dst;
578 }
579 
580 extern void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
581                                 bool force);
582 
583 /**
584  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
585  * @skb: buffer
586  * @dst: dst entry
587  *
588  * Sets skb dst, assuming a reference was not taken on dst.
589  * If dst entry is cached, we do not take reference and dst_release
590  * will be avoided by refdst_drop. If dst entry is not cached, we take
591  * reference, so that last dst_release can destroy the dst immediately.
592  */
593 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
594 {
595         __skb_dst_set_noref(skb, dst, false);
596 }
597 
598 /**
599  * skb_dst_set_noref_force - sets skb dst, without taking reference
600  * @skb: buffer
601  * @dst: dst entry
602  *
603  * Sets skb dst, assuming a reference was not taken on dst.
604  * No reference is taken and no dst_release will be called. While for
605  * cached dsts deferred reclaim is a basic feature, for entries that are
606  * not cached it is caller's job to guarantee that last dst_release for
607  * provided dst happens when nobody uses it, eg. after a RCU grace period.
608  */
609 static inline void skb_dst_set_noref_force(struct sk_buff *skb,
610                                            struct dst_entry *dst)
611 {
612         __skb_dst_set_noref(skb, dst, true);
613 }
614 
615 /**
616  * skb_dst_is_noref - Test if skb dst isn't refcounted
617  * @skb: buffer
618  */
619 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
620 {
621         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
622 }
623 
624 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
625 {
626         return (struct rtable *)skb_dst(skb);
627 }
628 
629 extern void kfree_skb(struct sk_buff *skb);
630 extern void kfree_skb_list(struct sk_buff *segs);
631 extern void skb_tx_error(struct sk_buff *skb);
632 extern void consume_skb(struct sk_buff *skb);
633 extern void            __kfree_skb(struct sk_buff *skb);
634 extern struct kmem_cache *skbuff_head_cache;
635 
636 extern void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
637 extern bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
638                              bool *fragstolen, int *delta_truesize);
639 
640 extern struct sk_buff *__alloc_skb(unsigned int size,
641                                    gfp_t priority, int flags, int node);
642 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
643 extern struct sk_buff *build_skb(void *data, unsigned int frag_size);
644 static inline struct sk_buff *alloc_skb(unsigned int size,
645                                         gfp_t priority)
646 {
647         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
648 }
649 
650 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
651                                                gfp_t priority)
652 {
653         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
654 }
655 
656 extern struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
657 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
658 {
659         return __alloc_skb_head(priority, -1);
660 }
661 
662 extern struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
663 extern int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
664 extern struct sk_buff *skb_clone(struct sk_buff *skb,
665                                  gfp_t priority);
666 extern struct sk_buff *skb_copy(const struct sk_buff *skb,
667                                 gfp_t priority);
668 extern struct sk_buff *__pskb_copy(struct sk_buff *skb,
669                                  int headroom, gfp_t gfp_mask);
670 
671 extern int             pskb_expand_head(struct sk_buff *skb,
672                                         int nhead, int ntail,
673                                         gfp_t gfp_mask);
674 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
675                                             unsigned int headroom);
676 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
677                                        int newheadroom, int newtailroom,
678                                        gfp_t priority);
679 extern int             skb_to_sgvec(struct sk_buff *skb,
680                                     struct scatterlist *sg, int offset,
681                                     int len);
682 extern int             skb_cow_data(struct sk_buff *skb, int tailbits,
683                                     struct sk_buff **trailer);
684 extern int             skb_pad(struct sk_buff *skb, int pad);
685 #define dev_kfree_skb(a)        consume_skb(a)
686 
687 extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
688                         int getfrag(void *from, char *to, int offset,
689                         int len,int odd, struct sk_buff *skb),
690                         void *from, int length);
691 
692 struct skb_seq_state {
693         __u32           lower_offset;
694         __u32           upper_offset;
695         __u32           frag_idx;
696         __u32           stepped_offset;
697         struct sk_buff  *root_skb;
698         struct sk_buff  *cur_skb;
699         __u8            *frag_data;
700 };
701 
702 extern void           skb_prepare_seq_read(struct sk_buff *skb,
703                                            unsigned int from, unsigned int to,
704                                            struct skb_seq_state *st);
705 extern unsigned int   skb_seq_read(unsigned int consumed, const u8 **data,
706                                    struct skb_seq_state *st);
707 extern void           skb_abort_seq_read(struct skb_seq_state *st);
708 
709 extern unsigned int   skb_find_text(struct sk_buff *skb, unsigned int from,
710                                     unsigned int to, struct ts_config *config,
711                                     struct ts_state *state);
712 
713 extern void __skb_get_rxhash(struct sk_buff *skb);
714 static inline __u32 skb_get_rxhash(struct sk_buff *skb)
715 {
716         if (!skb->l4_rxhash)
717                 __skb_get_rxhash(skb);
718 
719         return skb->rxhash;
720 }
721 
722 #ifdef NET_SKBUFF_DATA_USES_OFFSET
723 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
724 {
725         return skb->head + skb->end;
726 }
727 
728 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
729 {
730         return skb->end;
731 }
732 #else
733 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
734 {
735         return skb->end;
736 }
737 
738 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
739 {
740         return skb->end - skb->head;
741 }
742 #endif
743 
744 /* Internal */
745 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
746 
747 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
748 {
749         return &skb_shinfo(skb)->hwtstamps;
750 }
751 
752 /**
753  *      skb_queue_empty - check if a queue is empty
754  *      @list: queue head
755  *
756  *      Returns true if the queue is empty, false otherwise.
757  */
758 static inline int skb_queue_empty(const struct sk_buff_head *list)
759 {
760         return list->next == (struct sk_buff *)list;
761 }
762 
763 /**
764  *      skb_queue_is_last - check if skb is the last entry in the queue
765  *      @list: queue head
766  *      @skb: buffer
767  *
768  *      Returns true if @skb is the last buffer on the list.
769  */
770 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
771                                      const struct sk_buff *skb)
772 {
773         return skb->next == (struct sk_buff *)list;
774 }
775 
776 /**
777  *      skb_queue_is_first - check if skb is the first entry in the queue
778  *      @list: queue head
779  *      @skb: buffer
780  *
781  *      Returns true if @skb is the first buffer on the list.
782  */
783 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
784                                       const struct sk_buff *skb)
785 {
786         return skb->prev == (struct sk_buff *)list;
787 }
788 
789 /**
790  *      skb_queue_next - return the next packet in the queue
791  *      @list: queue head
792  *      @skb: current buffer
793  *
794  *      Return the next packet in @list after @skb.  It is only valid to
795  *      call this if skb_queue_is_last() evaluates to false.
796  */
797 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
798                                              const struct sk_buff *skb)
799 {
800         /* This BUG_ON may seem severe, but if we just return then we
801          * are going to dereference garbage.
802          */
803         BUG_ON(skb_queue_is_last(list, skb));
804         return skb->next;
805 }
806 
807 /**
808  *      skb_queue_prev - return the prev packet in the queue
809  *      @list: queue head
810  *      @skb: current buffer
811  *
812  *      Return the prev packet in @list before @skb.  It is only valid to
813  *      call this if skb_queue_is_first() evaluates to false.
814  */
815 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
816                                              const struct sk_buff *skb)
817 {
818         /* This BUG_ON may seem severe, but if we just return then we
819          * are going to dereference garbage.
820          */
821         BUG_ON(skb_queue_is_first(list, skb));
822         return skb->prev;
823 }
824 
825 /**
826  *      skb_get - reference buffer
827  *      @skb: buffer to reference
828  *
829  *      Makes another reference to a socket buffer and returns a pointer
830  *      to the buffer.
831  */
832 static inline struct sk_buff *skb_get(struct sk_buff *skb)
833 {
834         atomic_inc(&skb->users);
835         return skb;
836 }
837 
838 /*
839  * If users == 1, we are the only owner and are can avoid redundant
840  * atomic change.
841  */
842 
843 /**
844  *      skb_cloned - is the buffer a clone
845  *      @skb: buffer to check
846  *
847  *      Returns true if the buffer was generated with skb_clone() and is
848  *      one of multiple shared copies of the buffer. Cloned buffers are
849  *      shared data so must not be written to under normal circumstances.
850  */
851 static inline int skb_cloned(const struct sk_buff *skb)
852 {
853         return skb->cloned &&
854                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
855 }
856 
857 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
858 {
859         might_sleep_if(pri & __GFP_WAIT);
860 
861         if (skb_cloned(skb))
862                 return pskb_expand_head(skb, 0, 0, pri);
863 
864         return 0;
865 }
866 
867 /**
868  *      skb_header_cloned - is the header a clone
869  *      @skb: buffer to check
870  *
871  *      Returns true if modifying the header part of the buffer requires
872  *      the data to be copied.
873  */
874 static inline int skb_header_cloned(const struct sk_buff *skb)
875 {
876         int dataref;
877 
878         if (!skb->cloned)
879                 return 0;
880 
881         dataref = atomic_read(&skb_shinfo(skb)->dataref);
882         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
883         return dataref != 1;
884 }
885 
886 /**
887  *      skb_header_release - release reference to header
888  *      @skb: buffer to operate on
889  *
890  *      Drop a reference to the header part of the buffer.  This is done
891  *      by acquiring a payload reference.  You must not read from the header
892  *      part of skb->data after this.
893  */
894 static inline void skb_header_release(struct sk_buff *skb)
895 {
896         BUG_ON(skb->nohdr);
897         skb->nohdr = 1;
898         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
899 }
900 
901 /**
902  *      skb_shared - is the buffer shared
903  *      @skb: buffer to check
904  *
905  *      Returns true if more than one person has a reference to this
906  *      buffer.
907  */
908 static inline int skb_shared(const struct sk_buff *skb)
909 {
910         return atomic_read(&skb->users) != 1;
911 }
912 
913 /**
914  *      skb_share_check - check if buffer is shared and if so clone it
915  *      @skb: buffer to check
916  *      @pri: priority for memory allocation
917  *
918  *      If the buffer is shared the buffer is cloned and the old copy
919  *      drops a reference. A new clone with a single reference is returned.
920  *      If the buffer is not shared the original buffer is returned. When
921  *      being called from interrupt status or with spinlocks held pri must
922  *      be GFP_ATOMIC.
923  *
924  *      NULL is returned on a memory allocation failure.
925  */
926 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
927 {
928         might_sleep_if(pri & __GFP_WAIT);
929         if (skb_shared(skb)) {
930                 struct sk_buff *nskb = skb_clone(skb, pri);
931 
932                 if (likely(nskb))
933                         consume_skb(skb);
934                 else
935                         kfree_skb(skb);
936                 skb = nskb;
937         }
938         return skb;
939 }
940 
941 /*
942  *      Copy shared buffers into a new sk_buff. We effectively do COW on
943  *      packets to handle cases where we have a local reader and forward
944  *      and a couple of other messy ones. The normal one is tcpdumping
945  *      a packet thats being forwarded.
946  */
947 
948 /**
949  *      skb_unshare - make a copy of a shared buffer
950  *      @skb: buffer to check
951  *      @pri: priority for memory allocation
952  *
953  *      If the socket buffer is a clone then this function creates a new
954  *      copy of the data, drops a reference count on the old copy and returns
955  *      the new copy with the reference count at 1. If the buffer is not a clone
956  *      the original buffer is returned. When called with a spinlock held or
957  *      from interrupt state @pri must be %GFP_ATOMIC
958  *
959  *      %NULL is returned on a memory allocation failure.
960  */
961 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
962                                           gfp_t pri)
963 {
964         might_sleep_if(pri & __GFP_WAIT);
965         if (skb_cloned(skb)) {
966                 struct sk_buff *nskb = skb_copy(skb, pri);
967                 kfree_skb(skb); /* Free our shared copy */
968                 skb = nskb;
969         }
970         return skb;
971 }
972 
973 /**
974  *      skb_peek - peek at the head of an &sk_buff_head
975  *      @list_: list to peek at
976  *
977  *      Peek an &sk_buff. Unlike most other operations you _MUST_
978  *      be careful with this one. A peek leaves the buffer on the
979  *      list and someone else may run off with it. You must hold
980  *      the appropriate locks or have a private queue to do this.
981  *
982  *      Returns %NULL for an empty list or a pointer to the head element.
983  *      The reference count is not incremented and the reference is therefore
984  *      volatile. Use with caution.
985  */
986 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
987 {
988         struct sk_buff *skb = list_->next;
989 
990         if (skb == (struct sk_buff *)list_)
991                 skb = NULL;
992         return skb;
993 }
994 
995 /**
996  *      skb_peek_next - peek skb following the given one from a queue
997  *      @skb: skb to start from
998  *      @list_: list to peek at
999  *
1000  *      Returns %NULL when the end of the list is met or a pointer to the
1001  *      next element. The reference count is not incremented and the
1002  *      reference is therefore volatile. Use with caution.
1003  */
1004 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1005                 const struct sk_buff_head *list_)
1006 {
1007         struct sk_buff *next = skb->next;
1008 
1009         if (next == (struct sk_buff *)list_)
1010                 next = NULL;
1011         return next;
1012 }
1013 
1014 /**
1015  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1016  *      @list_: list to peek at
1017  *
1018  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1019  *      be careful with this one. A peek leaves the buffer on the
1020  *      list and someone else may run off with it. You must hold
1021  *      the appropriate locks or have a private queue to do this.
1022  *
1023  *      Returns %NULL for an empty list or a pointer to the tail element.
1024  *      The reference count is not incremented and the reference is therefore
1025  *      volatile. Use with caution.
1026  */
1027 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1028 {
1029         struct sk_buff *skb = list_->prev;
1030 
1031         if (skb == (struct sk_buff *)list_)
1032                 skb = NULL;
1033         return skb;
1034 
1035 }
1036 
1037 /**
1038  *      skb_queue_len   - get queue length
1039  *      @list_: list to measure
1040  *
1041  *      Return the length of an &sk_buff queue.
1042  */
1043 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1044 {
1045         return list_->qlen;
1046 }
1047 
1048 /**
1049  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1050  *      @list: queue to initialize
1051  *
1052  *      This initializes only the list and queue length aspects of
1053  *      an sk_buff_head object.  This allows to initialize the list
1054  *      aspects of an sk_buff_head without reinitializing things like
1055  *      the spinlock.  It can also be used for on-stack sk_buff_head
1056  *      objects where the spinlock is known to not be used.
1057  */
1058 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1059 {
1060         list->prev = list->next = (struct sk_buff *)list;
1061         list->qlen = 0;
1062 }
1063 
1064 /*
1065  * This function creates a split out lock class for each invocation;
1066  * this is needed for now since a whole lot of users of the skb-queue
1067  * infrastructure in drivers have different locking usage (in hardirq)
1068  * than the networking core (in softirq only). In the long run either the
1069  * network layer or drivers should need annotation to consolidate the
1070  * main types of usage into 3 classes.
1071  */
1072 static inline void skb_queue_head_init(struct sk_buff_head *list)
1073 {
1074         spin_lock_init(&list->lock);
1075         __skb_queue_head_init(list);
1076 }
1077 
1078 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1079                 struct lock_class_key *class)
1080 {
1081         skb_queue_head_init(list);
1082         lockdep_set_class(&list->lock, class);
1083 }
1084 
1085 /*
1086  *      Insert an sk_buff on a list.
1087  *
1088  *      The "__skb_xxxx()" functions are the non-atomic ones that
1089  *      can only be called with interrupts disabled.
1090  */
1091 extern void        skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
1092 static inline void __skb_insert(struct sk_buff *newsk,
1093                                 struct sk_buff *prev, struct sk_buff *next,
1094                                 struct sk_buff_head *list)
1095 {
1096         newsk->next = next;
1097         newsk->prev = prev;
1098         next->prev  = prev->next = newsk;
1099         list->qlen++;
1100 }
1101 
1102 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1103                                       struct sk_buff *prev,
1104                                       struct sk_buff *next)
1105 {
1106         struct sk_buff *first = list->next;
1107         struct sk_buff *last = list->prev;
1108 
1109         first->prev = prev;
1110         prev->next = first;
1111 
1112         last->next = next;
1113         next->prev = last;
1114 }
1115 
1116 /**
1117  *      skb_queue_splice - join two skb lists, this is designed for stacks
1118  *      @list: the new list to add
1119  *      @head: the place to add it in the first list
1120  */
1121 static inline void skb_queue_splice(const struct sk_buff_head *list,
1122                                     struct sk_buff_head *head)
1123 {
1124         if (!skb_queue_empty(list)) {
1125                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1126                 head->qlen += list->qlen;
1127         }
1128 }
1129 
1130 /**
1131  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1132  *      @list: the new list to add
1133  *      @head: the place to add it in the first list
1134  *
1135  *      The list at @list is reinitialised
1136  */
1137 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1138                                          struct sk_buff_head *head)
1139 {
1140         if (!skb_queue_empty(list)) {
1141                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1142                 head->qlen += list->qlen;
1143                 __skb_queue_head_init(list);
1144         }
1145 }
1146 
1147 /**
1148  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1149  *      @list: the new list to add
1150  *      @head: the place to add it in the first list
1151  */
1152 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1153                                          struct sk_buff_head *head)
1154 {
1155         if (!skb_queue_empty(list)) {
1156                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1157                 head->qlen += list->qlen;
1158         }
1159 }
1160 
1161 /**
1162  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1163  *      @list: the new list to add
1164  *      @head: the place to add it in the first list
1165  *
1166  *      Each of the lists is a queue.
1167  *      The list at @list is reinitialised
1168  */
1169 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1170                                               struct sk_buff_head *head)
1171 {
1172         if (!skb_queue_empty(list)) {
1173                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1174                 head->qlen += list->qlen;
1175                 __skb_queue_head_init(list);
1176         }
1177 }
1178 
1179 /**
1180  *      __skb_queue_after - queue a buffer at the list head
1181  *      @list: list to use
1182  *      @prev: place after this buffer
1183  *      @newsk: buffer to queue
1184  *
1185  *      Queue a buffer int the middle of a list. This function takes no locks
1186  *      and you must therefore hold required locks before calling it.
1187  *
1188  *      A buffer cannot be placed on two lists at the same time.
1189  */
1190 static inline void __skb_queue_after(struct sk_buff_head *list,
1191                                      struct sk_buff *prev,
1192                                      struct sk_buff *newsk)
1193 {
1194         __skb_insert(newsk, prev, prev->next, list);
1195 }
1196 
1197 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1198                        struct sk_buff_head *list);
1199 
1200 static inline void __skb_queue_before(struct sk_buff_head *list,
1201                                       struct sk_buff *next,
1202                                       struct sk_buff *newsk)
1203 {
1204         __skb_insert(newsk, next->prev, next, list);
1205 }
1206 
1207 /**
1208  *      __skb_queue_head - queue a buffer at the list head
1209  *      @list: list to use
1210  *      @newsk: buffer to queue
1211  *
1212  *      Queue a buffer at the start of a list. This function takes no locks
1213  *      and you must therefore hold required locks before calling it.
1214  *
1215  *      A buffer cannot be placed on two lists at the same time.
1216  */
1217 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1218 static inline void __skb_queue_head(struct sk_buff_head *list,
1219                                     struct sk_buff *newsk)
1220 {
1221         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1222 }
1223 
1224 /**
1225  *      __skb_queue_tail - queue a buffer at the list tail
1226  *      @list: list to use
1227  *      @newsk: buffer to queue
1228  *
1229  *      Queue a buffer at the end of a list. This function takes no locks
1230  *      and you must therefore hold required locks before calling it.
1231  *
1232  *      A buffer cannot be placed on two lists at the same time.
1233  */
1234 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1235 static inline void __skb_queue_tail(struct sk_buff_head *list,
1236                                    struct sk_buff *newsk)
1237 {
1238         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1239 }
1240 
1241 /*
1242  * remove sk_buff from list. _Must_ be called atomically, and with
1243  * the list known..
1244  */
1245 extern void        skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1246 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1247 {
1248         struct sk_buff *next, *prev;
1249 
1250         list->qlen--;
1251         next       = skb->next;
1252         prev       = skb->prev;
1253         skb->next  = skb->prev = NULL;
1254         next->prev = prev;
1255         prev->next = next;
1256 }
1257 
1258 /**
1259  *      __skb_dequeue - remove from the head of the queue
1260  *      @list: list to dequeue from
1261  *
1262  *      Remove the head of the list. This function does not take any locks
1263  *      so must be used with appropriate locks held only. The head item is
1264  *      returned or %NULL if the list is empty.
1265  */
1266 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1267 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1268 {
1269         struct sk_buff *skb = skb_peek(list);
1270         if (skb)
1271                 __skb_unlink(skb, list);
1272         return skb;
1273 }
1274 
1275 /**
1276  *      __skb_dequeue_tail - remove from the tail of the queue
1277  *      @list: list to dequeue from
1278  *
1279  *      Remove the tail of the list. This function does not take any locks
1280  *      so must be used with appropriate locks held only. The tail item is
1281  *      returned or %NULL if the list is empty.
1282  */
1283 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1284 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1285 {
1286         struct sk_buff *skb = skb_peek_tail(list);
1287         if (skb)
1288                 __skb_unlink(skb, list);
1289         return skb;
1290 }
1291 
1292 
1293 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1294 {
1295         return skb->data_len;
1296 }
1297 
1298 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1299 {
1300         return skb->len - skb->data_len;
1301 }
1302 
1303 static inline int skb_pagelen(const struct sk_buff *skb)
1304 {
1305         int i, len = 0;
1306 
1307         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1308                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1309         return len + skb_headlen(skb);
1310 }
1311 
1312 /**
1313  * __skb_fill_page_desc - initialise a paged fragment in an skb
1314  * @skb: buffer containing fragment to be initialised
1315  * @i: paged fragment index to initialise
1316  * @page: the page to use for this fragment
1317  * @off: the offset to the data with @page
1318  * @size: the length of the data
1319  *
1320  * Initialises the @i'th fragment of @skb to point to &size bytes at
1321  * offset @off within @page.
1322  *
1323  * Does not take any additional reference on the fragment.
1324  */
1325 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1326                                         struct page *page, int off, int size)
1327 {
1328         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1329 
1330         /*
1331          * Propagate page->pfmemalloc to the skb if we can. The problem is
1332          * that not all callers have unique ownership of the page. If
1333          * pfmemalloc is set, we check the mapping as a mapping implies
1334          * page->index is set (index and pfmemalloc share space).
1335          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1336          * do not lose pfmemalloc information as the pages would not be
1337          * allocated using __GFP_MEMALLOC.
1338          */
1339         frag->page.p              = page;
1340         frag->page_offset         = off;
1341         skb_frag_size_set(frag, size);
1342 
1343         page = compound_head(page);
1344         if (page->pfmemalloc && !page->mapping)
1345                 skb->pfmemalloc = true;
1346 }
1347 
1348 /**
1349  * skb_fill_page_desc - initialise a paged fragment in an skb
1350  * @skb: buffer containing fragment to be initialised
1351  * @i: paged fragment index to initialise
1352  * @page: the page to use for this fragment
1353  * @off: the offset to the data with @page
1354  * @size: the length of the data
1355  *
1356  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1357  * @skb to point to &size bytes at offset @off within @page. In
1358  * addition updates @skb such that @i is the last fragment.
1359  *
1360  * Does not take any additional reference on the fragment.
1361  */
1362 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1363                                       struct page *page, int off, int size)
1364 {
1365         __skb_fill_page_desc(skb, i, page, off, size);
1366         skb_shinfo(skb)->nr_frags = i + 1;
1367 }
1368 
1369 extern void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page,
1370                             int off, int size, unsigned int truesize);
1371 
1372 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1373 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1374 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1375 
1376 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1377 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1378 {
1379         return skb->head + skb->tail;
1380 }
1381 
1382 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1383 {
1384         skb->tail = skb->data - skb->head;
1385 }
1386 
1387 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1388 {
1389         skb_reset_tail_pointer(skb);
1390         skb->tail += offset;
1391 }
1392 
1393 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1394 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1395 {
1396         return skb->tail;
1397 }
1398 
1399 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1400 {
1401         skb->tail = skb->data;
1402 }
1403 
1404 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1405 {
1406         skb->tail = skb->data + offset;
1407 }
1408 
1409 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1410 
1411 /*
1412  *      Add data to an sk_buff
1413  */
1414 extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1415 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1416 {
1417         unsigned char *tmp = skb_tail_pointer(skb);
1418         SKB_LINEAR_ASSERT(skb);
1419         skb->tail += len;
1420         skb->len  += len;
1421         return tmp;
1422 }
1423 
1424 extern unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1425 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1426 {
1427         skb->data -= len;
1428         skb->len  += len;
1429         return skb->data;
1430 }
1431 
1432 extern unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1433 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1434 {
1435         skb->len -= len;
1436         BUG_ON(skb->len < skb->data_len);
1437         return skb->data += len;
1438 }
1439 
1440 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1441 {
1442         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1443 }
1444 
1445 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1446 
1447 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1448 {
1449         if (len > skb_headlen(skb) &&
1450             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1451                 return NULL;
1452         skb->len -= len;
1453         return skb->data += len;
1454 }
1455 
1456 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1457 {
1458         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1459 }
1460 
1461 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1462 {
1463         if (likely(len <= skb_headlen(skb)))
1464                 return 1;
1465         if (unlikely(len > skb->len))
1466                 return 0;
1467         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1468 }
1469 
1470 /**
1471  *      skb_headroom - bytes at buffer head
1472  *      @skb: buffer to check
1473  *
1474  *      Return the number of bytes of free space at the head of an &sk_buff.
1475  */
1476 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1477 {
1478         return skb->data - skb->head;
1479 }
1480 
1481 /**
1482  *      skb_tailroom - bytes at buffer end
1483  *      @skb: buffer to check
1484  *
1485  *      Return the number of bytes of free space at the tail of an sk_buff
1486  */
1487 static inline int skb_tailroom(const struct sk_buff *skb)
1488 {
1489         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1490 }
1491 
1492 /**
1493  *      skb_availroom - bytes at buffer end
1494  *      @skb: buffer to check
1495  *
1496  *      Return the number of bytes of free space at the tail of an sk_buff
1497  *      allocated by sk_stream_alloc()
1498  */
1499 static inline int skb_availroom(const struct sk_buff *skb)
1500 {
1501         if (skb_is_nonlinear(skb))
1502                 return 0;
1503 
1504         return skb->end - skb->tail - skb->reserved_tailroom;
1505 }
1506 
1507 /**
1508  *      skb_reserve - adjust headroom
1509  *      @skb: buffer to alter
1510  *      @len: bytes to move
1511  *
1512  *      Increase the headroom of an empty &sk_buff by reducing the tail
1513  *      room. This is only allowed for an empty buffer.
1514  */
1515 static inline void skb_reserve(struct sk_buff *skb, int len)
1516 {
1517         skb->data += len;
1518         skb->tail += len;
1519 }
1520 
1521 /**
1522  *      skb_tailroom_reserve - adjust reserved_tailroom
1523  *      @skb: buffer to alter
1524  *      @mtu: maximum amount of headlen permitted
1525  *      @needed_tailroom: minimum amount of reserved_tailroom
1526  *
1527  *      Set reserved_tailroom so that headlen can be as large as possible but
1528  *      not larger than mtu and tailroom cannot be smaller than
1529  *      needed_tailroom.
1530  *      The required headroom should already have been reserved before using
1531  *      this function.
1532  */
1533 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
1534                                         unsigned int needed_tailroom)
1535 {
1536         SKB_LINEAR_ASSERT(skb);
1537         if (mtu < skb_tailroom(skb) - needed_tailroom)
1538                 /* use at most mtu */
1539                 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
1540         else
1541                 /* use up to all available space */
1542                 skb->reserved_tailroom = needed_tailroom;
1543 }
1544 
1545 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1546 {
1547         skb->inner_mac_header = skb->mac_header;
1548         skb->inner_network_header = skb->network_header;
1549         skb->inner_transport_header = skb->transport_header;
1550 }
1551 
1552 static inline void skb_reset_mac_len(struct sk_buff *skb)
1553 {
1554         skb->mac_len = skb->network_header - skb->mac_header;
1555 }
1556 
1557 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1558                                                         *skb)
1559 {
1560         return skb->head + skb->inner_transport_header;
1561 }
1562 
1563 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1564 {
1565         skb->inner_transport_header = skb->data - skb->head;
1566 }
1567 
1568 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1569                                                    const int offset)
1570 {
1571         skb_reset_inner_transport_header(skb);
1572         skb->inner_transport_header += offset;
1573 }
1574 
1575 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1576 {
1577         return skb->head + skb->inner_network_header;
1578 }
1579 
1580 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1581 {
1582         skb->inner_network_header = skb->data - skb->head;
1583 }
1584 
1585 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1586                                                 const int offset)
1587 {
1588         skb_reset_inner_network_header(skb);
1589         skb->inner_network_header += offset;
1590 }
1591 
1592 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1593 {
1594         return skb->head + skb->inner_mac_header;
1595 }
1596 
1597 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1598 {
1599         skb->inner_mac_header = skb->data - skb->head;
1600 }
1601 
1602 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1603                                             const int offset)
1604 {
1605         skb_reset_inner_mac_header(skb);
1606         skb->inner_mac_header += offset;
1607 }
1608 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1609 {
1610         return skb->transport_header != (typeof(skb->transport_header))~0U;
1611 }
1612 
1613 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1614 {
1615         return skb->head + skb->transport_header;
1616 }
1617 
1618 static inline void skb_reset_transport_header(struct sk_buff *skb)
1619 {
1620         skb->transport_header = skb->data - skb->head;
1621 }
1622 
1623 static inline void skb_set_transport_header(struct sk_buff *skb,
1624                                             const int offset)
1625 {
1626         skb_reset_transport_header(skb);
1627         skb->transport_header += offset;
1628 }
1629 
1630 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1631 {
1632         return skb->head + skb->network_header;
1633 }
1634 
1635 static inline void skb_reset_network_header(struct sk_buff *skb)
1636 {
1637         skb->network_header = skb->data - skb->head;
1638 }
1639 
1640 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1641 {
1642         skb_reset_network_header(skb);
1643         skb->network_header += offset;
1644 }
1645 
1646 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1647 {
1648         return skb->head + skb->mac_header;
1649 }
1650 
1651 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1652 {
1653         return skb->mac_header != (typeof(skb->mac_header))~0U;
1654 }
1655 
1656 static inline void skb_reset_mac_header(struct sk_buff *skb)
1657 {
1658         skb->mac_header = skb->data - skb->head;
1659 }
1660 
1661 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1662 {
1663         skb_reset_mac_header(skb);
1664         skb->mac_header += offset;
1665 }
1666 
1667 static inline void skb_pop_mac_header(struct sk_buff *skb)
1668 {
1669         skb->mac_header = skb->network_header;
1670 }
1671 
1672 static inline void skb_probe_transport_header(struct sk_buff *skb,
1673                                               const int offset_hint)
1674 {
1675         struct flow_keys keys;
1676 
1677         if (skb_transport_header_was_set(skb))
1678                 return;
1679         else if (skb_flow_dissect(skb, &keys))
1680                 skb_set_transport_header(skb, keys.thoff);
1681         else
1682                 skb_set_transport_header(skb, offset_hint);
1683 }
1684 
1685 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1686 {
1687         if (skb_mac_header_was_set(skb)) {
1688                 const unsigned char *old_mac = skb_mac_header(skb);
1689 
1690                 skb_set_mac_header(skb, -skb->mac_len);
1691                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1692         }
1693 }
1694 
1695 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1696 {
1697         return skb->csum_start - skb_headroom(skb);
1698 }
1699 
1700 static inline int skb_transport_offset(const struct sk_buff *skb)
1701 {
1702         return skb_transport_header(skb) - skb->data;
1703 }
1704 
1705 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1706 {
1707         return skb->transport_header - skb->network_header;
1708 }
1709 
1710 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1711 {
1712         return skb->inner_transport_header - skb->inner_network_header;
1713 }
1714 
1715 static inline int skb_network_offset(const struct sk_buff *skb)
1716 {
1717         return skb_network_header(skb) - skb->data;
1718 }
1719 
1720 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1721 {
1722         return skb_inner_network_header(skb) - skb->data;
1723 }
1724 
1725 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1726 {
1727         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1728 }
1729 
1730 /*
1731  * CPUs often take a performance hit when accessing unaligned memory
1732  * locations. The actual performance hit varies, it can be small if the
1733  * hardware handles it or large if we have to take an exception and fix it
1734  * in software.
1735  *
1736  * Since an ethernet header is 14 bytes network drivers often end up with
1737  * the IP header at an unaligned offset. The IP header can be aligned by
1738  * shifting the start of the packet by 2 bytes. Drivers should do this
1739  * with:
1740  *
1741  * skb_reserve(skb, NET_IP_ALIGN);
1742  *
1743  * The downside to this alignment of the IP header is that the DMA is now
1744  * unaligned. On some architectures the cost of an unaligned DMA is high
1745  * and this cost outweighs the gains made by aligning the IP header.
1746  *
1747  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1748  * to be overridden.
1749  */
1750 #ifndef NET_IP_ALIGN
1751 #define NET_IP_ALIGN    2
1752 #endif
1753 
1754 /*
1755  * The networking layer reserves some headroom in skb data (via
1756  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1757  * the header has to grow. In the default case, if the header has to grow
1758  * 32 bytes or less we avoid the reallocation.
1759  *
1760  * Unfortunately this headroom changes the DMA alignment of the resulting
1761  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1762  * on some architectures. An architecture can override this value,
1763  * perhaps setting it to a cacheline in size (since that will maintain
1764  * cacheline alignment of the DMA). It must be a power of 2.
1765  *
1766  * Various parts of the networking layer expect at least 32 bytes of
1767  * headroom, you should not reduce this.
1768  *
1769  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
1770  * to reduce average number of cache lines per packet.
1771  * get_rps_cpus() for example only access one 64 bytes aligned block :
1772  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
1773  */
1774 #ifndef NET_SKB_PAD
1775 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
1776 #endif
1777 
1778 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1779 
1780 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1781 {
1782         if (unlikely(skb_is_nonlinear(skb))) {
1783                 WARN_ON(1);
1784                 return;
1785         }
1786         skb->len = len;
1787         skb_set_tail_pointer(skb, len);
1788 }
1789 
1790 extern void skb_trim(struct sk_buff *skb, unsigned int len);
1791 
1792 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1793 {
1794         if (skb->data_len)
1795                 return ___pskb_trim(skb, len);
1796         __skb_trim(skb, len);
1797         return 0;
1798 }
1799 
1800 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1801 {
1802         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1803 }
1804 
1805 /**
1806  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1807  *      @skb: buffer to alter
1808  *      @len: new length
1809  *
1810  *      This is identical to pskb_trim except that the caller knows that
1811  *      the skb is not cloned so we should never get an error due to out-
1812  *      of-memory.
1813  */
1814 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1815 {
1816         int err = pskb_trim(skb, len);
1817         BUG_ON(err);
1818 }
1819 
1820 /**
1821  *      skb_orphan - orphan a buffer
1822  *      @skb: buffer to orphan
1823  *
1824  *      If a buffer currently has an owner then we call the owner's
1825  *      destructor function and make the @skb unowned. The buffer continues
1826  *      to exist but is no longer charged to its former owner.
1827  */
1828 static inline void skb_orphan(struct sk_buff *skb)
1829 {
1830         if (skb->destructor) {
1831                 skb->destructor(skb);
1832                 skb->destructor = NULL;
1833                 skb->sk         = NULL;
1834         } else {
1835                 BUG_ON(skb->sk);
1836         }
1837 }
1838 
1839 /**
1840  *      skb_orphan_frags - orphan the frags contained in a buffer
1841  *      @skb: buffer to orphan frags from
1842  *      @gfp_mask: allocation mask for replacement pages
1843  *
1844  *      For each frag in the SKB which needs a destructor (i.e. has an
1845  *      owner) create a copy of that frag and release the original
1846  *      page by calling the destructor.
1847  */
1848 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
1849 {
1850         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
1851                 return 0;
1852         return skb_copy_ubufs(skb, gfp_mask);
1853 }
1854 
1855 /**
1856  *      __skb_queue_purge - empty a list
1857  *      @list: list to empty
1858  *
1859  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
1860  *      the list and one reference dropped. This function does not take the
1861  *      list lock and the caller must hold the relevant locks to use it.
1862  */
1863 extern void skb_queue_purge(struct sk_buff_head *list);
1864 static inline void __skb_queue_purge(struct sk_buff_head *list)
1865 {
1866         struct sk_buff *skb;
1867         while ((skb = __skb_dequeue(list)) != NULL)
1868                 kfree_skb(skb);
1869 }
1870 
1871 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
1872 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
1873 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
1874 
1875 extern void *netdev_alloc_frag(unsigned int fragsz);
1876 
1877 extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
1878                                           unsigned int length,
1879                                           gfp_t gfp_mask);
1880 
1881 /**
1882  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
1883  *      @dev: network device to receive on
1884  *      @length: length to allocate
1885  *
1886  *      Allocate a new &sk_buff and assign it a usage count of one. The
1887  *      buffer has unspecified headroom built in. Users should allocate
1888  *      the headroom they think they need without accounting for the
1889  *      built in space. The built in space is used for optimisations.
1890  *
1891  *      %NULL is returned if there is no free memory. Although this function
1892  *      allocates memory it can be called from an interrupt.
1893  */
1894 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
1895                                                unsigned int length)
1896 {
1897         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
1898 }
1899 
1900 /* legacy helper around __netdev_alloc_skb() */
1901 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
1902                                               gfp_t gfp_mask)
1903 {
1904         return __netdev_alloc_skb(NULL, length, gfp_mask);
1905 }
1906 
1907 /* legacy helper around netdev_alloc_skb() */
1908 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1909 {
1910         return netdev_alloc_skb(NULL, length);
1911 }
1912 
1913 
1914 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
1915                 unsigned int length, gfp_t gfp)
1916 {
1917         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
1918 
1919         if (NET_IP_ALIGN && skb)
1920                 skb_reserve(skb, NET_IP_ALIGN);
1921         return skb;
1922 }
1923 
1924 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
1925                 unsigned int length)
1926 {
1927         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
1928 }
1929 
1930 /**
1931  *      __skb_alloc_pages - allocate pages for ps-rx on a skb and preserve pfmemalloc data
1932  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1933  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1934  *      @order: size of the allocation
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_pages(gfp_t gfp_mask,
1941                                               struct sk_buff *skb,
1942                                               unsigned int order)
1943 {
1944         struct page *page;
1945 
1946         gfp_mask |= __GFP_COLD;
1947 
1948         if (!(gfp_mask & __GFP_NOMEMALLOC))
1949                 gfp_mask |= __GFP_MEMALLOC;
1950 
1951         page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
1952         if (skb && page && page->pfmemalloc)
1953                 skb->pfmemalloc = true;
1954 
1955         return page;
1956 }
1957 
1958 /**
1959  *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
1960  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1961  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1962  *
1963  *      Allocate a new page.
1964  *
1965  *      %NULL is returned if there is no free memory.
1966  */
1967 static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
1968                                              struct sk_buff *skb)
1969 {
1970         return __skb_alloc_pages(gfp_mask, skb, 0);
1971 }
1972 
1973 /**
1974  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
1975  *      @page: The page that was allocated from skb_alloc_page
1976  *      @skb: The skb that may need pfmemalloc set
1977  */
1978 static inline void skb_propagate_pfmemalloc(struct page *page,
1979                                              struct sk_buff *skb)
1980 {
1981         if (page && page->pfmemalloc)
1982                 skb->pfmemalloc = true;
1983 }
1984 
1985 /**
1986  * skb_frag_page - retrieve the page refered to by a paged fragment
1987  * @frag: the paged fragment
1988  *
1989  * Returns the &struct page associated with @frag.
1990  */
1991 static inline struct page *skb_frag_page(const skb_frag_t *frag)
1992 {
1993         return frag->page.p;
1994 }
1995 
1996 /**
1997  * __skb_frag_ref - take an addition reference on a paged fragment.
1998  * @frag: the paged fragment
1999  *
2000  * Takes an additional reference on the paged fragment @frag.
2001  */
2002 static inline void __skb_frag_ref(skb_frag_t *frag)
2003 {
2004         get_page(skb_frag_page(frag));
2005 }
2006 
2007 /**
2008  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2009  * @skb: the buffer
2010  * @f: the fragment offset.
2011  *
2012  * Takes an additional reference on the @f'th paged fragment of @skb.
2013  */
2014 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2015 {
2016         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2017 }
2018 
2019 /**
2020  * __skb_frag_unref - release a reference on a paged fragment.
2021  * @frag: the paged fragment
2022  *
2023  * Releases a reference on the paged fragment @frag.
2024  */
2025 static inline void __skb_frag_unref(skb_frag_t *frag)
2026 {
2027         put_page(skb_frag_page(frag));
2028 }
2029 
2030 /**
2031  * skb_frag_unref - release a reference on a paged fragment of an skb.
2032  * @skb: the buffer
2033  * @f: the fragment offset
2034  *
2035  * Releases a reference on the @f'th paged fragment of @skb.
2036  */
2037 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2038 {
2039         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2040 }
2041 
2042 /**
2043  * skb_frag_address - gets the address of the data contained in a paged fragment
2044  * @frag: the paged fragment buffer
2045  *
2046  * Returns the address of the data within @frag. The page must already
2047  * be mapped.
2048  */
2049 static inline void *skb_frag_address(const skb_frag_t *frag)
2050 {
2051         return page_address(skb_frag_page(frag)) + frag->page_offset;
2052 }
2053 
2054 /**
2055  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2056  * @frag: the paged fragment buffer
2057  *
2058  * Returns the address of the data within @frag. Checks that the page
2059  * is mapped and returns %NULL otherwise.
2060  */
2061 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2062 {
2063         void *ptr = page_address(skb_frag_page(frag));
2064         if (unlikely(!ptr))
2065                 return NULL;
2066 
2067         return ptr + frag->page_offset;
2068 }
2069 
2070 /**
2071  * __skb_frag_set_page - sets the page contained in a paged fragment
2072  * @frag: the paged fragment
2073  * @page: the page to set
2074  *
2075  * Sets the fragment @frag to contain @page.
2076  */
2077 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2078 {
2079         frag->page.p = page;
2080 }
2081 
2082 /**
2083  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2084  * @skb: the buffer
2085  * @f: the fragment offset
2086  * @page: the page to set
2087  *
2088  * Sets the @f'th fragment of @skb to contain @page.
2089  */
2090 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2091                                      struct page *page)
2092 {
2093         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2094 }
2095 
2096 /**
2097  * skb_frag_dma_map - maps a paged fragment via the DMA API
2098  * @dev: the device to map the fragment to
2099  * @frag: the paged fragment to map
2100  * @offset: the offset within the fragment (starting at the
2101  *          fragment's own offset)
2102  * @size: the number of bytes to map
2103  * @dir: the direction of the mapping (%PCI_DMA_*)
2104  *
2105  * Maps the page associated with @frag to @device.
2106  */
2107 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2108                                           const skb_frag_t *frag,
2109                                           size_t offset, size_t size,
2110                                           enum dma_data_direction dir)
2111 {
2112         return dma_map_page(dev, skb_frag_page(frag),
2113                             frag->page_offset + offset, size, dir);
2114 }
2115 
2116 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2117                                         gfp_t gfp_mask)
2118 {
2119         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2120 }
2121 
2122 /**
2123  *      skb_clone_writable - is the header of a clone writable
2124  *      @skb: buffer to check
2125  *      @len: length up to which to write
2126  *
2127  *      Returns true if modifying the header part of the cloned buffer
2128  *      does not requires the data to be copied.
2129  */
2130 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2131 {
2132         return !skb_header_cloned(skb) &&
2133                skb_headroom(skb) + len <= skb->hdr_len;
2134 }
2135 
2136 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2137                             int cloned)
2138 {
2139         int delta = 0;
2140 
2141         if (headroom > skb_headroom(skb))
2142                 delta = headroom - skb_headroom(skb);
2143 
2144         if (delta || cloned)
2145                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2146                                         GFP_ATOMIC);
2147         return 0;
2148 }
2149 
2150 /**
2151  *      skb_cow - copy header of skb when it is required
2152  *      @skb: buffer to cow
2153  *      @headroom: needed headroom
2154  *
2155  *      If the skb passed lacks sufficient headroom or its data part
2156  *      is shared, data is reallocated. If reallocation fails, an error
2157  *      is returned and original skb is not changed.
2158  *
2159  *      The result is skb with writable area skb->head...skb->tail
2160  *      and at least @headroom of space at head.
2161  */
2162 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2163 {
2164         return __skb_cow(skb, headroom, skb_cloned(skb));
2165 }
2166 
2167 /**
2168  *      skb_cow_head - skb_cow but only making the head writable
2169  *      @skb: buffer to cow
2170  *      @headroom: needed headroom
2171  *
2172  *      This function is identical to skb_cow except that we replace the
2173  *      skb_cloned check by skb_header_cloned.  It should be used when
2174  *      you only need to push on some header and do not need to modify
2175  *      the data.
2176  */
2177 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2178 {
2179         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2180 }
2181 
2182 /**
2183  *      skb_padto       - pad an skbuff up to a minimal size
2184  *      @skb: buffer to pad
2185  *      @len: minimal length
2186  *
2187  *      Pads up a buffer to ensure the trailing bytes exist and are
2188  *      blanked. If the buffer already contains sufficient data it
2189  *      is untouched. Otherwise it is extended. Returns zero on
2190  *      success. The skb is freed on error.
2191  */
2192  
2193 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2194 {
2195         unsigned int size = skb->len;
2196         if (likely(size >= len))
2197                 return 0;
2198         return skb_pad(skb, len - size);
2199 }
2200 
2201 static inline int skb_add_data(struct sk_buff *skb,
2202                                char __user *from, int copy)
2203 {
2204         const int off = skb->len;
2205 
2206         if (skb->ip_summed == CHECKSUM_NONE) {
2207                 int err = 0;
2208                 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2209                                                             copy, 0, &err);
2210                 if (!err) {
2211                         skb->csum = csum_block_add(skb->csum, csum, off);
2212                         return 0;
2213                 }
2214         } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2215                 return 0;
2216 
2217         __skb_trim(skb, off);
2218         return -EFAULT;
2219 }
2220 
2221 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2222                                     const struct page *page, int off)
2223 {
2224         if (i) {
2225                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2226 
2227                 return page == skb_frag_page(frag) &&
2228                        off == frag->page_offset + skb_frag_size(frag);
2229         }
2230         return false;
2231 }
2232 
2233 static inline int __skb_linearize(struct sk_buff *skb)
2234 {
2235         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2236 }
2237 
2238 /**
2239  *      skb_linearize - convert paged skb to linear one
2240  *      @skb: buffer to linarize
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(struct sk_buff *skb)
2246 {
2247         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2248 }
2249 
2250 /**
2251  * skb_has_shared_frag - can any frag be overwritten
2252  * @skb: buffer to test
2253  *
2254  * Return true if the skb has at least one frag that might be modified
2255  * by an external entity (as in vmsplice()/sendfile())
2256  */
2257 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2258 {
2259         return skb_is_nonlinear(skb) &&
2260                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2261 }
2262 
2263 /**
2264  *      skb_linearize_cow - make sure skb is linear and writable
2265  *      @skb: buffer to process
2266  *
2267  *      If there is no free memory -ENOMEM is returned, otherwise zero
2268  *      is returned and the old skb data released.
2269  */
2270 static inline int skb_linearize_cow(struct sk_buff *skb)
2271 {
2272         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2273                __skb_linearize(skb) : 0;
2274 }
2275 
2276 /**
2277  *      skb_postpull_rcsum - update checksum for received skb after pull
2278  *      @skb: buffer to update
2279  *      @start: start of data before pull
2280  *      @len: length of data pulled
2281  *
2282  *      After doing a pull on a received packet, you need to call this to
2283  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2284  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2285  */
2286 
2287 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2288                                       const void *start, unsigned int len)
2289 {
2290         if (skb->ip_summed == CHECKSUM_COMPLETE)
2291                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2292         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2293                  skb_checksum_start_offset(skb) < 0)
2294                 skb->ip_summed = CHECKSUM_NONE;
2295 }
2296 
2297 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2298 
2299 /**
2300  *      pskb_trim_rcsum - trim received skb and update checksum
2301  *      @skb: buffer to trim
2302  *      @len: new length
2303  *
2304  *      This is exactly the same as pskb_trim except that it ensures the
2305  *      checksum of received packets are still valid after the operation.
2306  */
2307 
2308 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2309 {
2310         if (likely(len >= skb->len))
2311                 return 0;
2312         if (skb->ip_summed == CHECKSUM_COMPLETE)
2313                 skb->ip_summed = CHECKSUM_NONE;
2314         return __pskb_trim(skb, len);
2315 }
2316 
2317 #define skb_queue_walk(queue, skb) \
2318                 for (skb = (queue)->next;                                       \
2319                      skb != (struct sk_buff *)(queue);                          \
2320                      skb = skb->next)
2321 
2322 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2323                 for (skb = (queue)->next, tmp = skb->next;                      \
2324                      skb != (struct sk_buff *)(queue);                          \
2325                      skb = tmp, tmp = skb->next)
2326 
2327 #define skb_queue_walk_from(queue, skb)                                         \
2328                 for (; skb != (struct sk_buff *)(queue);                        \
2329                      skb = skb->next)
2330 
2331 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2332                 for (tmp = skb->next;                                           \
2333                      skb != (struct sk_buff *)(queue);                          \
2334                      skb = tmp, tmp = skb->next)
2335 
2336 #define skb_queue_reverse_walk(queue, skb) \
2337                 for (skb = (queue)->prev;                                       \
2338                      skb != (struct sk_buff *)(queue);                          \
2339                      skb = skb->prev)
2340 
2341 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2342                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2343                      skb != (struct sk_buff *)(queue);                          \
2344                      skb = tmp, tmp = skb->prev)
2345 
2346 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2347                 for (tmp = skb->prev;                                           \
2348                      skb != (struct sk_buff *)(queue);                          \
2349                      skb = tmp, tmp = skb->prev)
2350 
2351 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2352 {
2353         return skb_shinfo(skb)->frag_list != NULL;
2354 }
2355 
2356 static inline void skb_frag_list_init(struct sk_buff *skb)
2357 {
2358         skb_shinfo(skb)->frag_list = NULL;
2359 }
2360 
2361 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2362 {
2363         frag->next = skb_shinfo(skb)->frag_list;
2364         skb_shinfo(skb)->frag_list = frag;
2365 }
2366 
2367 #define skb_walk_frags(skb, iter)       \
2368         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2369 
2370 extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2371                                            int *peeked, int *off, int *err);
2372 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
2373                                          int noblock, int *err);
2374 extern unsigned int    datagram_poll(struct file *file, struct socket *sock,
2375                                      struct poll_table_struct *wait);
2376 extern int             skb_copy_datagram_iovec(const struct sk_buff *from,
2377                                                int offset, struct iovec *to,
2378                                                int size);
2379 extern int             skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
2380                                                         int hlen,
2381                                                         struct iovec *iov,
2382                                                         int len);
2383 extern int             skb_copy_datagram_from_iovec(struct sk_buff *skb,
2384                                                     int offset,
2385                                                     const struct iovec *from,
2386                                                     int from_offset,
2387                                                     int len);
2388 extern int             zerocopy_sg_from_iovec(struct sk_buff *skb,
2389                                               const struct iovec *frm,
2390                                               int offset,
2391                                               size_t count);
2392 extern int             skb_copy_datagram_const_iovec(const struct sk_buff *from,
2393                                                      int offset,
2394                                                      const struct iovec *to,
2395                                                      int to_offset,
2396                                                      int size);
2397 extern void            skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2398 extern void            skb_free_datagram_locked(struct sock *sk,
2399                                                 struct sk_buff *skb);
2400 extern int             skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
2401                                          unsigned int flags);
2402 extern __wsum          skb_checksum(const struct sk_buff *skb, int offset,
2403                                     int len, __wsum csum);
2404 extern int             skb_copy_bits(const struct sk_buff *skb, int offset,
2405                                      void *to, int len);
2406 extern int             skb_store_bits(struct sk_buff *skb, int offset,
2407                                       const void *from, int len);
2408 extern __wsum          skb_copy_and_csum_bits(const struct sk_buff *skb,
2409                                               int offset, u8 *to, int len,
2410                                               __wsum csum);
2411 extern int             skb_splice_bits(struct sk_buff *skb,
2412                                                 unsigned int offset,
2413                                                 struct pipe_inode_info *pipe,
2414                                                 unsigned int len,
2415                                                 unsigned int flags);
2416 extern void            skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2417 extern void            skb_split(struct sk_buff *skb,
2418                                  struct sk_buff *skb1, const u32 len);
2419 extern int             skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
2420                                  int shiftlen);
2421 extern void            skb_scrub_packet(struct sk_buff *skb, bool xnet);
2422 
2423 extern struct sk_buff *skb_segment(struct sk_buff *skb,
2424                                    netdev_features_t features);
2425 
2426 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2427 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
2428 
2429 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2430                                        int len, void *buffer)
2431 {
2432         int hlen = skb_headlen(skb);
2433 
2434         if (hlen - offset >= len)
2435                 return skb->data + offset;
2436 
2437         if (skb_copy_bits(skb, offset, buffer, len) < 0)
2438                 return NULL;
2439 
2440         return buffer;
2441 }
2442 
2443 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2444                                              void *to,
2445                                              const unsigned int len)
2446 {
2447         memcpy(to, skb->data, len);
2448 }
2449 
2450 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2451                                                     const int offset, void *to,
2452                                                     const unsigned int len)
2453 {
2454         memcpy(to, skb->data + offset, len);
2455 }
2456 
2457 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2458                                            const void *from,
2459                                            const unsigned int len)
2460 {
2461         memcpy(skb->data, from, len);
2462 }
2463 
2464 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2465                                                   const int offset,
2466                                                   const void *from,
2467                                                   const unsigned int len)
2468 {
2469         memcpy(skb->data + offset, from, len);
2470 }
2471 
2472 extern void skb_init(void);
2473 
2474 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2475 {
2476         return skb->tstamp;
2477 }
2478 
2479 /**
2480  *      skb_get_timestamp - get timestamp from a skb
2481  *      @skb: skb to get stamp from
2482  *      @stamp: pointer to struct timeval to store stamp in
2483  *
2484  *      Timestamps are stored in the skb as offsets to a base timestamp.
2485  *      This function converts the offset back to a struct timeval and stores
2486  *      it in stamp.
2487  */
2488 static inline void skb_get_timestamp(const struct sk_buff *skb,
2489                                      struct timeval *stamp)
2490 {
2491         *stamp = ktime_to_timeval(skb->tstamp);
2492 }
2493 
2494 static inline void skb_get_timestampns(const struct sk_buff *skb,
2495                                        struct timespec *stamp)
2496 {
2497         *stamp = ktime_to_timespec(skb->tstamp);
2498 }
2499 
2500 static inline void __net_timestamp(struct sk_buff *skb)
2501 {
2502         skb->tstamp = ktime_get_real();
2503 }
2504 
2505 static inline ktime_t net_timedelta(ktime_t t)
2506 {
2507         return ktime_sub(ktime_get_real(), t);
2508 }
2509 
2510 static inline ktime_t net_invalid_timestamp(void)
2511 {
2512         return ktime_set(0, 0);
2513 }
2514 
2515 extern void skb_timestamping_init(void);
2516 
2517 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2518 
2519 extern void skb_clone_tx_timestamp(struct sk_buff *skb);
2520 extern bool skb_defer_rx_timestamp(struct sk_buff *skb);
2521 
2522 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2523 
2524 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2525 {
2526 }
2527 
2528 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2529 {
2530         return false;
2531 }
2532 
2533 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2534 
2535 /**
2536  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2537  *
2538  * PHY drivers may accept clones of transmitted packets for
2539  * timestamping via their phy_driver.txtstamp method. These drivers
2540  * must call this function to return the skb back to the stack, with
2541  * or without a timestamp.
2542  *
2543  * @skb: clone of the the original outgoing packet
2544  * @hwtstamps: hardware time stamps, may be NULL if not available
2545  *
2546  */
2547 void skb_complete_tx_timestamp(struct sk_buff *skb,
2548                                struct skb_shared_hwtstamps *hwtstamps);
2549 
2550 /**
2551  * skb_tstamp_tx - queue clone of skb with send time stamps
2552  * @orig_skb:   the original outgoing packet
2553  * @hwtstamps:  hardware time stamps, may be NULL if not available
2554  *
2555  * If the skb has a socket associated, then this function clones the
2556  * skb (thus sharing the actual data and optional structures), stores
2557  * the optional hardware time stamping information (if non NULL) or
2558  * generates a software time stamp (otherwise), then queues the clone
2559  * to the error queue of the socket.  Errors are silently ignored.
2560  */
2561 extern void skb_tstamp_tx(struct sk_buff *orig_skb,
2562                         struct skb_shared_hwtstamps *hwtstamps);
2563 
2564 static inline void sw_tx_timestamp(struct sk_buff *skb)
2565 {
2566         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2567             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2568                 skb_tstamp_tx(skb, NULL);
2569 }
2570 
2571 /**
2572  * skb_tx_timestamp() - Driver hook for transmit timestamping
2573  *
2574  * Ethernet MAC Drivers should call this function in their hard_xmit()
2575  * function immediately before giving the sk_buff to the MAC hardware.
2576  *
2577  * @skb: A socket buffer.
2578  */
2579 static inline void skb_tx_timestamp(struct sk_buff *skb)
2580 {
2581         skb_clone_tx_timestamp(skb);
2582         sw_tx_timestamp(skb);
2583 }
2584 
2585 /**
2586  * skb_complete_wifi_ack - deliver skb with wifi status
2587  *
2588  * @skb: the original outgoing packet
2589  * @acked: ack status
2590  *
2591  */
2592 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2593 
2594 extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2595 extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
2596 
2597 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2598 {
2599         return skb->ip_summed & CHECKSUM_UNNECESSARY;
2600 }
2601 
2602 /**
2603  *      skb_checksum_complete - Calculate checksum of an entire packet
2604  *      @skb: packet to process
2605  *
2606  *      This function calculates the checksum over the entire packet plus
2607  *      the value of skb->csum.  The latter can be used to supply the
2608  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2609  *      checksum.
2610  *
2611  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2612  *      this function can be used to verify that checksum on received
2613  *      packets.  In that case the function should return zero if the
2614  *      checksum is correct.  In particular, this function will return zero
2615  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2616  *      hardware has already verified the correctness of the checksum.
2617  */
2618 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2619 {
2620         return skb_csum_unnecessary(skb) ?
2621                0 : __skb_checksum_complete(skb);
2622 }
2623 
2624 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2625 extern void nf_conntrack_destroy(struct nf_conntrack *nfct);
2626 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
2627 {
2628         if (nfct && atomic_dec_and_test(&nfct->use))
2629                 nf_conntrack_destroy(nfct);
2630 }
2631 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
2632 {
2633         if (nfct)
2634                 atomic_inc(&nfct->use);
2635 }
2636 #endif
2637 #ifdef CONFIG_BRIDGE_NETFILTER
2638 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
2639 {
2640         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
2641                 kfree(nf_bridge);
2642 }
2643 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
2644 {
2645         if (nf_bridge)
2646                 atomic_inc(&nf_bridge->use);
2647 }
2648 #endif /* CONFIG_BRIDGE_NETFILTER */
2649 static inline void nf_reset(struct sk_buff *skb)
2650 {
2651 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2652         nf_conntrack_put(skb->nfct);
2653         skb->nfct = NULL;
2654 #endif
2655 #ifdef CONFIG_BRIDGE_NETFILTER
2656         nf_bridge_put(skb->nf_bridge);
2657         skb->nf_bridge = NULL;
2658 #endif
2659 }
2660 
2661 static inline void nf_reset_trace(struct sk_buff *skb)
2662 {
2663 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
2664         skb->nf_trace = 0;
2665 #endif
2666 }
2667 
2668 /* Note: This doesn't put any conntrack and bridge info in dst. */
2669 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2670 {
2671 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2672         dst->nfct = src->nfct;
2673         nf_conntrack_get(src->nfct);
2674         dst->nfctinfo = src->nfctinfo;
2675 #endif
2676 #ifdef CONFIG_BRIDGE_NETFILTER
2677         dst->nf_bridge  = src->nf_bridge;
2678         nf_bridge_get(src->nf_bridge);
2679 #endif
2680 }
2681 
2682 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2683 {
2684 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2685         nf_conntrack_put(dst->nfct);
2686 #endif
2687 #ifdef CONFIG_BRIDGE_NETFILTER
2688         nf_bridge_put(dst->nf_bridge);
2689 #endif
2690         __nf_copy(dst, src);
2691 }
2692 
2693 #ifdef CONFIG_NETWORK_SECMARK
2694 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2695 {
2696         to->secmark = from->secmark;
2697 }
2698 
2699 static inline void skb_init_secmark(struct sk_buff *skb)
2700 {
2701         skb->secmark = 0;
2702 }
2703 #else
2704 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2705 { }
2706 
2707 static inline void skb_init_secmark(struct sk_buff *skb)
2708 { }
2709 #endif
2710 
2711 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
2712 {
2713         skb->queue_mapping = queue_mapping;
2714 }
2715 
2716 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2717 {
2718         return skb->queue_mapping;
2719 }
2720 
2721 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
2722 {
2723         to->queue_mapping = from->queue_mapping;
2724 }
2725 
2726 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
2727 {
2728         skb->queue_mapping = rx_queue + 1;
2729 }
2730 
2731 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
2732 {
2733         return skb->queue_mapping - 1;
2734 }
2735 
2736 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
2737 {
2738         return skb->queue_mapping != 0;
2739 }
2740 
2741 extern u16 __skb_tx_hash(const struct net_device *dev,
2742                          const struct sk_buff *skb,
2743                          unsigned int num_tx_queues);
2744 
2745 #ifdef CONFIG_XFRM
2746 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2747 {
2748         return skb->sp;
2749 }
2750 #else
2751 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2752 {
2753         return NULL;
2754 }
2755 #endif
2756 
2757 /* Keeps track of mac header offset relative to skb->head.
2758  * It is useful for TSO of Tunneling protocol. e.g. GRE.
2759  * For non-tunnel skb it points to skb_mac_header() and for
2760  * tunnel skb it points to outer mac header. */
2761 struct skb_gso_cb {
2762         int mac_offset;
2763 };
2764 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
2765 
2766 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
2767 {
2768         return (skb_mac_header(inner_skb) - inner_skb->head) -
2769                 SKB_GSO_CB(inner_skb)->mac_offset;
2770 }
2771 
2772 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
2773 {
2774         int new_headroom, headroom;
2775         int ret;
2776 
2777         headroom = skb_headroom(skb);
2778         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
2779         if (ret)
2780                 return ret;
2781 
2782         new_headroom = skb_headroom(skb);
2783         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
2784         return 0;
2785 }
2786 
2787 static inline bool skb_is_gso(const struct sk_buff *skb)
2788 {
2789         return skb_shinfo(skb)->gso_size;
2790 }
2791 
2792 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
2793 {
2794         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
2795 }
2796 
2797 extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
2798 
2799 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
2800 {
2801         /* LRO sets gso_size but not gso_type, whereas if GSO is really
2802          * wanted then gso_type will be set. */
2803         const struct skb_shared_info *shinfo = skb_shinfo(skb);
2804 
2805         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
2806             unlikely(shinfo->gso_type == 0)) {
2807                 __skb_warn_lro_forwarding(skb);
2808                 return true;
2809         }
2810         return false;
2811 }
2812 
2813 static inline void skb_forward_csum(struct sk_buff *skb)
2814 {
2815         /* Unfortunately we don't support this one.  Any brave souls? */
2816         if (skb->ip_summed == CHECKSUM_COMPLETE)
2817                 skb->ip_summed = CHECKSUM_NONE;
2818 }
2819 
2820 /**
2821  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
2822  * @skb: skb to check
2823  *
2824  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
2825  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
2826  * use this helper, to document places where we make this assertion.
2827  */
2828 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
2829 {
2830 #ifdef DEBUG
2831         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
2832 #endif
2833 }
2834 
2835 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
2836 
2837 u32 __skb_get_poff(const struct sk_buff *skb);
2838 
2839 /**
2840  * skb_head_is_locked - Determine if the skb->head is locked down
2841  * @skb: skb to check
2842  *
2843  * The head on skbs build around a head frag can be removed if they are
2844  * not cloned.  This function returns true if the skb head is locked down
2845  * due to either being allocated via kmalloc, or by being a clone with
2846  * multiple references to the head.
2847  */
2848 static inline bool skb_head_is_locked(const struct sk_buff *skb)
2849 {
2850         return !skb->head_frag || skb_cloned(skb);
2851 }
2852 
2853 /**
2854  * skb_gso_network_seglen - Return length of individual segments of a gso packet
2855  *
2856  * @skb: GSO skb
2857  *
2858  * skb_gso_network_seglen is used to determine the real size of the
2859  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
2860  *
2861  * The MAC/L2 header is not accounted for.
2862  */
2863 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
2864 {
2865         unsigned int hdr_len = skb_transport_header(skb) -
2866                                skb_network_header(skb);
2867         return hdr_len + skb_gso_transport_seglen(skb);
2868 }
2869 #endif  /* __KERNEL__ */
2870 #endif  /* _LINUX_SKBUFF_H */
2871 

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