Version:  2.0.40 2.2.26 2.4.37 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17

Linux/include/linux/skbuff.h

  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 
 24 #include <linux/atomic.h>
 25 #include <asm/types.h>
 26 #include <linux/spinlock.h>
 27 #include <linux/net.h>
 28 #include <linux/textsearch.h>
 29 #include <net/checksum.h>
 30 #include <linux/rcupdate.h>
 31 #include <linux/dmaengine.h>
 32 #include <linux/hrtimer.h>
 33 #include <linux/dma-mapping.h>
 34 #include <linux/netdev_features.h>
 35 #include <linux/sched.h>
 36 #include <net/flow_keys.h>
 37 
 38 /* A. Checksumming of received packets by device.
 39  *
 40  * CHECKSUM_NONE:
 41  *
 42  *   Device failed to checksum this packet e.g. due to lack of capabilities.
 43  *   The packet contains full (though not verified) checksum in packet but
 44  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 45  *
 46  * CHECKSUM_UNNECESSARY:
 47  *
 48  *   The hardware you're dealing with doesn't calculate the full checksum
 49  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
 50  *   for specific protocols e.g. TCP/UDP/SCTP, then, for such packets it will
 51  *   set CHECKSUM_UNNECESSARY if their checksums are okay. skb->csum is still
 52  *   undefined in this case though. It is a bad option, but, unfortunately,
 53  *   nowadays most vendors do this. Apparently with the secret goal to sell
 54  *   you new devices, when you will add new protocol to your host, f.e. IPv6 8)
 55  *
 56  * CHECKSUM_COMPLETE:
 57  *
 58  *   This is the most generic way. The device supplied checksum of the _whole_
 59  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
 60  *   hardware doesn't need to parse L3/L4 headers to implement this.
 61  *
 62  *   Note: Even if device supports only some protocols, but is able to produce
 63  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
 64  *
 65  * CHECKSUM_PARTIAL:
 66  *
 67  *   This is identical to the case for output below. This may occur on a packet
 68  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
 69  *   on the same host. The packet can be treated in the same way as
 70  *   CHECKSUM_UNNECESSARY, except that on output (i.e., forwarding) the
 71  *   checksum must be filled in by the OS or the hardware.
 72  *
 73  * B. Checksumming on output.
 74  *
 75  * CHECKSUM_NONE:
 76  *
 77  *   The skb was already checksummed by the protocol, or a checksum is not
 78  *   required.
 79  *
 80  * CHECKSUM_PARTIAL:
 81  *
 82  *   The device is required to checksum the packet as seen by hard_start_xmit()
 83  *   from skb->csum_start up to the end, and to record/write the checksum at
 84  *   offset skb->csum_start + skb->csum_offset.
 85  *
 86  *   The device must show its capabilities in dev->features, set up at device
 87  *   setup time, e.g. netdev_features.h:
 88  *
 89  *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
 90  *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
 91  *                        IPv4. Sigh. Vendors like this way for an unknown reason.
 92  *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
 93  *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
 94  *      NETIF_F_...     - Well, you get the picture.
 95  *
 96  * CHECKSUM_UNNECESSARY:
 97  *
 98  *   Normally, the device will do per protocol specific checksumming. Protocol
 99  *   implementations that do not want the NIC to perform the checksum
100  *   calculation should use this flag in their outgoing skbs.
101  *
102  *      NETIF_F_FCOE_CRC - This indicates that 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 /* Don't change this without changing skb_csum_unnecessary! */
110 #define CHECKSUM_NONE           0
111 #define CHECKSUM_UNNECESSARY    1
112 #define CHECKSUM_COMPLETE       2
113 #define CHECKSUM_PARTIAL        3
114 
115 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
116 #define SKB_WITH_OVERHEAD(X)    \
117         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
118 #define SKB_MAX_ORDER(X, ORDER) \
119         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
120 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
121 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
122 
123 /* return minimum truesize of one skb containing X bytes of data */
124 #define SKB_TRUESIZE(X) ((X) +                                          \
125                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
126                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
127 
128 struct net_device;
129 struct scatterlist;
130 struct pipe_inode_info;
131 
132 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
133 struct nf_conntrack {
134         atomic_t use;
135 };
136 #endif
137 
138 #ifdef CONFIG_BRIDGE_NETFILTER
139 struct nf_bridge_info {
140         atomic_t                use;
141         unsigned int            mask;
142         struct net_device       *physindev;
143         struct net_device       *physoutdev;
144         unsigned long           data[32 / sizeof(unsigned long)];
145 };
146 #endif
147 
148 struct sk_buff_head {
149         /* These two members must be first. */
150         struct sk_buff  *next;
151         struct sk_buff  *prev;
152 
153         __u32           qlen;
154         spinlock_t      lock;
155 };
156 
157 struct sk_buff;
158 
159 /* To allow 64K frame to be packed as single skb without frag_list we
160  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
161  * buffers which do not start on a page boundary.
162  *
163  * Since GRO uses frags we allocate at least 16 regardless of page
164  * size.
165  */
166 #if (65536/PAGE_SIZE + 1) < 16
167 #define MAX_SKB_FRAGS 16UL
168 #else
169 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
170 #endif
171 
172 typedef struct skb_frag_struct skb_frag_t;
173 
174 struct skb_frag_struct {
175         struct {
176                 struct page *p;
177         } page;
178 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
179         __u32 page_offset;
180         __u32 size;
181 #else
182         __u16 page_offset;
183         __u16 size;
184 #endif
185 };
186 
187 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
188 {
189         return frag->size;
190 }
191 
192 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
193 {
194         frag->size = size;
195 }
196 
197 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
198 {
199         frag->size += delta;
200 }
201 
202 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
203 {
204         frag->size -= delta;
205 }
206 
207 #define HAVE_HW_TIME_STAMP
208 
209 /**
210  * struct skb_shared_hwtstamps - hardware time stamps
211  * @hwtstamp:   hardware time stamp transformed into duration
212  *              since arbitrary point in time
213  *
214  * Software time stamps generated by ktime_get_real() are stored in
215  * skb->tstamp.
216  *
217  * hwtstamps can only be compared against other hwtstamps from
218  * the same device.
219  *
220  * This structure is attached to packets as part of the
221  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
222  */
223 struct skb_shared_hwtstamps {
224         ktime_t hwtstamp;
225 };
226 
227 /* Definitions for tx_flags in struct skb_shared_info */
228 enum {
229         /* generate hardware time stamp */
230         SKBTX_HW_TSTAMP = 1 << 0,
231 
232         /* generate software time stamp when queueing packet to NIC */
233         SKBTX_SW_TSTAMP = 1 << 1,
234 
235         /* device driver is going to provide hardware time stamp */
236         SKBTX_IN_PROGRESS = 1 << 2,
237 
238         /* device driver supports TX zero-copy buffers */
239         SKBTX_DEV_ZEROCOPY = 1 << 3,
240 
241         /* generate wifi status information (where possible) */
242         SKBTX_WIFI_STATUS = 1 << 4,
243 
244         /* This indicates at least one fragment might be overwritten
245          * (as in vmsplice(), sendfile() ...)
246          * If we need to compute a TX checksum, we'll need to copy
247          * all frags to avoid possible bad checksum
248          */
249         SKBTX_SHARED_FRAG = 1 << 5,
250 
251         /* generate software time stamp when entering packet scheduling */
252         SKBTX_SCHED_TSTAMP = 1 << 6,
253 
254         /* generate software timestamp on peer data acknowledgment */
255         SKBTX_ACK_TSTAMP = 1 << 7,
256 };
257 
258 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
259                                  SKBTX_SCHED_TSTAMP | \
260                                  SKBTX_ACK_TSTAMP)
261 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
262 
263 /*
264  * The callback notifies userspace to release buffers when skb DMA is done in
265  * lower device, the skb last reference should be 0 when calling this.
266  * The zerocopy_success argument is true if zero copy transmit occurred,
267  * false on data copy or out of memory error caused by data copy attempt.
268  * The ctx field is used to track device context.
269  * The desc field is used to track userspace buffer index.
270  */
271 struct ubuf_info {
272         void (*callback)(struct ubuf_info *, bool zerocopy_success);
273         void *ctx;
274         unsigned long desc;
275 };
276 
277 /* This data is invariant across clones and lives at
278  * the end of the header data, ie. at skb->end.
279  */
280 struct skb_shared_info {
281         unsigned char   nr_frags;
282         __u8            tx_flags;
283         unsigned short  gso_size;
284         /* Warning: this field is not always filled in (UFO)! */
285         unsigned short  gso_segs;
286         unsigned short  gso_type;
287         struct sk_buff  *frag_list;
288         struct skb_shared_hwtstamps hwtstamps;
289         u32             tskey;
290         __be32          ip6_frag_id;
291 
292         /*
293          * Warning : all fields before dataref are cleared in __alloc_skb()
294          */
295         atomic_t        dataref;
296 
297         /* Intermediate layers must ensure that destructor_arg
298          * remains valid until skb destructor */
299         void *          destructor_arg;
300 
301         /* must be last field, see pskb_expand_head() */
302         skb_frag_t      frags[MAX_SKB_FRAGS];
303 };
304 
305 /* We divide dataref into two halves.  The higher 16 bits hold references
306  * to the payload part of skb->data.  The lower 16 bits hold references to
307  * the entire skb->data.  A clone of a headerless skb holds the length of
308  * the header in skb->hdr_len.
309  *
310  * All users must obey the rule that the skb->data reference count must be
311  * greater than or equal to the payload reference count.
312  *
313  * Holding a reference to the payload part means that the user does not
314  * care about modifications to the header part of skb->data.
315  */
316 #define SKB_DATAREF_SHIFT 16
317 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
318 
319 
320 enum {
321         SKB_FCLONE_UNAVAILABLE,
322         SKB_FCLONE_ORIG,
323         SKB_FCLONE_CLONE,
324 };
325 
326 enum {
327         SKB_GSO_TCPV4 = 1 << 0,
328         SKB_GSO_UDP = 1 << 1,
329 
330         /* This indicates the skb is from an untrusted source. */
331         SKB_GSO_DODGY = 1 << 2,
332 
333         /* This indicates the tcp segment has CWR set. */
334         SKB_GSO_TCP_ECN = 1 << 3,
335 
336         SKB_GSO_TCPV6 = 1 << 4,
337 
338         SKB_GSO_FCOE = 1 << 5,
339 
340         SKB_GSO_GRE = 1 << 6,
341 
342         SKB_GSO_GRE_CSUM = 1 << 7,
343 
344         SKB_GSO_IPIP = 1 << 8,
345 
346         SKB_GSO_SIT = 1 << 9,
347 
348         SKB_GSO_UDP_TUNNEL = 1 << 10,
349 
350         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
351 
352         SKB_GSO_MPLS = 1 << 12,
353 
354 };
355 
356 #if BITS_PER_LONG > 32
357 #define NET_SKBUFF_DATA_USES_OFFSET 1
358 #endif
359 
360 #ifdef NET_SKBUFF_DATA_USES_OFFSET
361 typedef unsigned int sk_buff_data_t;
362 #else
363 typedef unsigned char *sk_buff_data_t;
364 #endif
365 
366 /**
367  * struct skb_mstamp - multi resolution time stamps
368  * @stamp_us: timestamp in us resolution
369  * @stamp_jiffies: timestamp in jiffies
370  */
371 struct skb_mstamp {
372         union {
373                 u64             v64;
374                 struct {
375                         u32     stamp_us;
376                         u32     stamp_jiffies;
377                 };
378         };
379 };
380 
381 /**
382  * skb_mstamp_get - get current timestamp
383  * @cl: place to store timestamps
384  */
385 static inline void skb_mstamp_get(struct skb_mstamp *cl)
386 {
387         u64 val = local_clock();
388 
389         do_div(val, NSEC_PER_USEC);
390         cl->stamp_us = (u32)val;
391         cl->stamp_jiffies = (u32)jiffies;
392 }
393 
394 /**
395  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
396  * @t1: pointer to newest sample
397  * @t0: pointer to oldest sample
398  */
399 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
400                                       const struct skb_mstamp *t0)
401 {
402         s32 delta_us = t1->stamp_us - t0->stamp_us;
403         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
404 
405         /* If delta_us is negative, this might be because interval is too big,
406          * or local_clock() drift is too big : fallback using jiffies.
407          */
408         if (delta_us <= 0 ||
409             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
410 
411                 delta_us = jiffies_to_usecs(delta_jiffies);
412 
413         return delta_us;
414 }
415 
416 
417 /** 
418  *      struct sk_buff - socket buffer
419  *      @next: Next buffer in list
420  *      @prev: Previous buffer in list
421  *      @tstamp: Time we arrived/left
422  *      @sk: Socket we are owned by
423  *      @dev: Device we arrived on/are leaving by
424  *      @cb: Control buffer. Free for use by every layer. Put private vars here
425  *      @_skb_refdst: destination entry (with norefcount bit)
426  *      @sp: the security path, used for xfrm
427  *      @len: Length of actual data
428  *      @data_len: Data length
429  *      @mac_len: Length of link layer header
430  *      @hdr_len: writable header length of cloned skb
431  *      @csum: Checksum (must include start/offset pair)
432  *      @csum_start: Offset from skb->head where checksumming should start
433  *      @csum_offset: Offset from csum_start where checksum should be stored
434  *      @priority: Packet queueing priority
435  *      @ignore_df: allow local fragmentation
436  *      @cloned: Head may be cloned (check refcnt to be sure)
437  *      @ip_summed: Driver fed us an IP checksum
438  *      @nohdr: Payload reference only, must not modify header
439  *      @nfctinfo: Relationship of this skb to the connection
440  *      @pkt_type: Packet class
441  *      @fclone: skbuff clone status
442  *      @ipvs_property: skbuff is owned by ipvs
443  *      @peeked: this packet has been seen already, so stats have been
444  *              done for it, don't do them again
445  *      @nf_trace: netfilter packet trace flag
446  *      @protocol: Packet protocol from driver
447  *      @destructor: Destruct function
448  *      @nfct: Associated connection, if any
449  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
450  *      @skb_iif: ifindex of device we arrived on
451  *      @tc_index: Traffic control index
452  *      @tc_verd: traffic control verdict
453  *      @hash: the packet hash
454  *      @queue_mapping: Queue mapping for multiqueue devices
455  *      @ndisc_nodetype: router type (from link layer)
456  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
457  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
458  *              ports.
459  *      @sw_hash: indicates hash was computed in software stack
460  *      @wifi_acked_valid: wifi_acked was set
461  *      @wifi_acked: whether frame was acked on wifi or not
462  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
463  *      @dma_cookie: a cookie to one of several possible DMA operations
464  *              done by skb DMA functions
465   *     @napi_id: id of the NAPI struct this skb came from
466  *      @secmark: security marking
467  *      @mark: Generic packet mark
468  *      @dropcount: total number of sk_receive_queue overflows
469  *      @vlan_proto: vlan encapsulation protocol
470  *      @vlan_tci: vlan tag control information
471  *      @inner_protocol: Protocol (encapsulation)
472  *      @inner_transport_header: Inner transport layer header (encapsulation)
473  *      @inner_network_header: Network layer header (encapsulation)
474  *      @inner_mac_header: Link layer header (encapsulation)
475  *      @transport_header: Transport layer header
476  *      @network_header: Network layer header
477  *      @mac_header: Link layer header
478  *      @tail: Tail pointer
479  *      @end: End pointer
480  *      @head: Head of buffer
481  *      @data: Data head pointer
482  *      @truesize: Buffer size
483  *      @users: User count - see {datagram,tcp}.c
484  */
485 
486 struct sk_buff {
487         /* These two members must be first. */
488         struct sk_buff          *next;
489         struct sk_buff          *prev;
490 
491         union {
492                 ktime_t         tstamp;
493                 struct skb_mstamp skb_mstamp;
494         };
495 
496         struct sock             *sk;
497         struct net_device       *dev;
498 
499         /*
500          * This is the control buffer. It is free to use for every
501          * layer. Please put your private variables there. If you
502          * want to keep them across layers you have to do a skb_clone()
503          * first. This is owned by whoever has the skb queued ATM.
504          */
505         char                    cb[48] __aligned(8);
506 
507         unsigned long           _skb_refdst;
508 #ifdef CONFIG_XFRM
509         struct  sec_path        *sp;
510 #endif
511         unsigned int            len,
512                                 data_len;
513         __u16                   mac_len,
514                                 hdr_len;
515         union {
516                 __wsum          csum;
517                 struct {
518                         __u16   csum_start;
519                         __u16   csum_offset;
520                 };
521         };
522         __u32                   priority;
523         kmemcheck_bitfield_begin(flags1);
524         __u8                    ignore_df:1,
525                                 cloned:1,
526                                 ip_summed:2,
527                                 nohdr:1,
528                                 nfctinfo:3;
529         __u8                    pkt_type:3,
530                                 fclone:2,
531                                 ipvs_property:1,
532                                 peeked:1,
533                                 nf_trace:1;
534         kmemcheck_bitfield_end(flags1);
535         __be16                  protocol;
536 
537         void                    (*destructor)(struct sk_buff *skb);
538 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
539         struct nf_conntrack     *nfct;
540 #endif
541 #ifdef CONFIG_BRIDGE_NETFILTER
542         struct nf_bridge_info   *nf_bridge;
543 #endif
544 
545         int                     skb_iif;
546 
547         __u32                   hash;
548 
549         __be16                  vlan_proto;
550         __u16                   vlan_tci;
551 
552 #ifdef CONFIG_NET_SCHED
553         __u16                   tc_index;       /* traffic control index */
554 #ifdef CONFIG_NET_CLS_ACT
555         __u16                   tc_verd;        /* traffic control verdict */
556 #endif
557 #endif
558 
559         __u16                   queue_mapping;
560         kmemcheck_bitfield_begin(flags2);
561 #ifdef CONFIG_IPV6_NDISC_NODETYPE
562         __u8                    ndisc_nodetype:2;
563 #endif
564         __u8                    pfmemalloc:1;
565         __u8                    ooo_okay:1;
566         __u8                    l4_hash:1;
567         __u8                    sw_hash:1;
568         __u8                    wifi_acked_valid:1;
569         __u8                    wifi_acked:1;
570         __u8                    no_fcs:1;
571         __u8                    head_frag:1;
572         /* Encapsulation protocol and NIC drivers should use
573          * this flag to indicate to each other if the skb contains
574          * encapsulated packet or not and maybe use the inner packet
575          * headers if needed
576          */
577         __u8                    encapsulation:1;
578         __u8                    encap_hdr_csum:1;
579         __u8                    csum_valid:1;
580         __u8                    csum_complete_sw:1;
581         /* 2/4 bit hole (depending on ndisc_nodetype presence) */
582         kmemcheck_bitfield_end(flags2);
583 
584 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
585         union {
586                 unsigned int    napi_id;
587                 dma_cookie_t    dma_cookie;
588         };
589 #endif
590 #ifdef CONFIG_NETWORK_SECMARK
591         __u32                   secmark;
592 #endif
593         union {
594                 __u32           mark;
595                 __u32           dropcount;
596                 __u32           reserved_tailroom;
597         };
598 
599         __be16                  inner_protocol;
600         __u16                   inner_transport_header;
601         __u16                   inner_network_header;
602         __u16                   inner_mac_header;
603         __u16                   transport_header;
604         __u16                   network_header;
605         __u16                   mac_header;
606         /* These elements must be at the end, see alloc_skb() for details.  */
607         sk_buff_data_t          tail;
608         sk_buff_data_t          end;
609         unsigned char           *head,
610                                 *data;
611         unsigned int            truesize;
612         atomic_t                users;
613 };
614 
615 #ifdef __KERNEL__
616 /*
617  *      Handling routines are only of interest to the kernel
618  */
619 #include <linux/slab.h>
620 
621 
622 #define SKB_ALLOC_FCLONE        0x01
623 #define SKB_ALLOC_RX            0x02
624 
625 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
626 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
627 {
628         return unlikely(skb->pfmemalloc);
629 }
630 
631 /*
632  * skb might have a dst pointer attached, refcounted or not.
633  * _skb_refdst low order bit is set if refcount was _not_ taken
634  */
635 #define SKB_DST_NOREF   1UL
636 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
637 
638 /**
639  * skb_dst - returns skb dst_entry
640  * @skb: buffer
641  *
642  * Returns skb dst_entry, regardless of reference taken or not.
643  */
644 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
645 {
646         /* If refdst was not refcounted, check we still are in a 
647          * rcu_read_lock section
648          */
649         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
650                 !rcu_read_lock_held() &&
651                 !rcu_read_lock_bh_held());
652         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
653 }
654 
655 /**
656  * skb_dst_set - sets skb dst
657  * @skb: buffer
658  * @dst: dst entry
659  *
660  * Sets skb dst, assuming a reference was taken on dst and should
661  * be released by skb_dst_drop()
662  */
663 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
664 {
665         skb->_skb_refdst = (unsigned long)dst;
666 }
667 
668 void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
669                          bool force);
670 
671 /**
672  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
673  * @skb: buffer
674  * @dst: dst entry
675  *
676  * Sets skb dst, assuming a reference was not taken on dst.
677  * If dst entry is cached, we do not take reference and dst_release
678  * will be avoided by refdst_drop. If dst entry is not cached, we take
679  * reference, so that last dst_release can destroy the dst immediately.
680  */
681 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
682 {
683         __skb_dst_set_noref(skb, dst, false);
684 }
685 
686 /**
687  * skb_dst_set_noref_force - sets skb dst, without taking reference
688  * @skb: buffer
689  * @dst: dst entry
690  *
691  * Sets skb dst, assuming a reference was not taken on dst.
692  * No reference is taken and no dst_release will be called. While for
693  * cached dsts deferred reclaim is a basic feature, for entries that are
694  * not cached it is caller's job to guarantee that last dst_release for
695  * provided dst happens when nobody uses it, eg. after a RCU grace period.
696  */
697 static inline void skb_dst_set_noref_force(struct sk_buff *skb,
698                                            struct dst_entry *dst)
699 {
700         __skb_dst_set_noref(skb, dst, true);
701 }
702 
703 /**
704  * skb_dst_is_noref - Test if skb dst isn't refcounted
705  * @skb: buffer
706  */
707 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
708 {
709         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
710 }
711 
712 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
713 {
714         return (struct rtable *)skb_dst(skb);
715 }
716 
717 void kfree_skb(struct sk_buff *skb);
718 void kfree_skb_list(struct sk_buff *segs);
719 void skb_tx_error(struct sk_buff *skb);
720 void consume_skb(struct sk_buff *skb);
721 void  __kfree_skb(struct sk_buff *skb);
722 extern struct kmem_cache *skbuff_head_cache;
723 
724 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
725 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
726                       bool *fragstolen, int *delta_truesize);
727 
728 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
729                             int node);
730 struct sk_buff *build_skb(void *data, unsigned int frag_size);
731 static inline struct sk_buff *alloc_skb(unsigned int size,
732                                         gfp_t priority)
733 {
734         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
735 }
736 
737 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
738                                                gfp_t priority)
739 {
740         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
741 }
742 
743 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
744 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
745 {
746         return __alloc_skb_head(priority, -1);
747 }
748 
749 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
750 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
751 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
752 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
753 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
754                                    gfp_t gfp_mask, bool fclone);
755 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
756                                           gfp_t gfp_mask)
757 {
758         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
759 }
760 
761 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
762 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
763                                      unsigned int headroom);
764 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
765                                 int newtailroom, gfp_t priority);
766 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
767                         int offset, int len);
768 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
769                  int len);
770 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
771 int skb_pad(struct sk_buff *skb, int pad);
772 #define dev_kfree_skb(a)        consume_skb(a)
773 
774 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
775                             int getfrag(void *from, char *to, int offset,
776                                         int len, int odd, struct sk_buff *skb),
777                             void *from, int length);
778 
779 struct skb_seq_state {
780         __u32           lower_offset;
781         __u32           upper_offset;
782         __u32           frag_idx;
783         __u32           stepped_offset;
784         struct sk_buff  *root_skb;
785         struct sk_buff  *cur_skb;
786         __u8            *frag_data;
787 };
788 
789 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
790                           unsigned int to, struct skb_seq_state *st);
791 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
792                           struct skb_seq_state *st);
793 void skb_abort_seq_read(struct skb_seq_state *st);
794 
795 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
796                            unsigned int to, struct ts_config *config,
797                            struct ts_state *state);
798 
799 /*
800  * Packet hash types specify the type of hash in skb_set_hash.
801  *
802  * Hash types refer to the protocol layer addresses which are used to
803  * construct a packet's hash. The hashes are used to differentiate or identify
804  * flows of the protocol layer for the hash type. Hash types are either
805  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
806  *
807  * Properties of hashes:
808  *
809  * 1) Two packets in different flows have different hash values
810  * 2) Two packets in the same flow should have the same hash value
811  *
812  * A hash at a higher layer is considered to be more specific. A driver should
813  * set the most specific hash possible.
814  *
815  * A driver cannot indicate a more specific hash than the layer at which a hash
816  * was computed. For instance an L3 hash cannot be set as an L4 hash.
817  *
818  * A driver may indicate a hash level which is less specific than the
819  * actual layer the hash was computed on. For instance, a hash computed
820  * at L4 may be considered an L3 hash. This should only be done if the
821  * driver can't unambiguously determine that the HW computed the hash at
822  * the higher layer. Note that the "should" in the second property above
823  * permits this.
824  */
825 enum pkt_hash_types {
826         PKT_HASH_TYPE_NONE,     /* Undefined type */
827         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
828         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
829         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
830 };
831 
832 static inline void
833 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
834 {
835         skb->l4_hash = (type == PKT_HASH_TYPE_L4);
836         skb->sw_hash = 0;
837         skb->hash = hash;
838 }
839 
840 void __skb_get_hash(struct sk_buff *skb);
841 static inline __u32 skb_get_hash(struct sk_buff *skb)
842 {
843         if (!skb->l4_hash && !skb->sw_hash)
844                 __skb_get_hash(skb);
845 
846         return skb->hash;
847 }
848 
849 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
850 {
851         return skb->hash;
852 }
853 
854 static inline void skb_clear_hash(struct sk_buff *skb)
855 {
856         skb->hash = 0;
857         skb->sw_hash = 0;
858         skb->l4_hash = 0;
859 }
860 
861 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
862 {
863         if (!skb->l4_hash)
864                 skb_clear_hash(skb);
865 }
866 
867 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
868 {
869         to->hash = from->hash;
870         to->sw_hash = from->sw_hash;
871         to->l4_hash = from->l4_hash;
872 };
873 
874 #ifdef NET_SKBUFF_DATA_USES_OFFSET
875 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
876 {
877         return skb->head + skb->end;
878 }
879 
880 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
881 {
882         return skb->end;
883 }
884 #else
885 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
886 {
887         return skb->end;
888 }
889 
890 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
891 {
892         return skb->end - skb->head;
893 }
894 #endif
895 
896 /* Internal */
897 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
898 
899 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
900 {
901         return &skb_shinfo(skb)->hwtstamps;
902 }
903 
904 /**
905  *      skb_queue_empty - check if a queue is empty
906  *      @list: queue head
907  *
908  *      Returns true if the queue is empty, false otherwise.
909  */
910 static inline int skb_queue_empty(const struct sk_buff_head *list)
911 {
912         return list->next == (const struct sk_buff *) list;
913 }
914 
915 /**
916  *      skb_queue_is_last - check if skb is the last entry in the queue
917  *      @list: queue head
918  *      @skb: buffer
919  *
920  *      Returns true if @skb is the last buffer on the list.
921  */
922 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
923                                      const struct sk_buff *skb)
924 {
925         return skb->next == (const struct sk_buff *) list;
926 }
927 
928 /**
929  *      skb_queue_is_first - check if skb is the first entry in the queue
930  *      @list: queue head
931  *      @skb: buffer
932  *
933  *      Returns true if @skb is the first buffer on the list.
934  */
935 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
936                                       const struct sk_buff *skb)
937 {
938         return skb->prev == (const struct sk_buff *) list;
939 }
940 
941 /**
942  *      skb_queue_next - return the next packet in the queue
943  *      @list: queue head
944  *      @skb: current buffer
945  *
946  *      Return the next packet in @list after @skb.  It is only valid to
947  *      call this if skb_queue_is_last() evaluates to false.
948  */
949 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
950                                              const struct sk_buff *skb)
951 {
952         /* This BUG_ON may seem severe, but if we just return then we
953          * are going to dereference garbage.
954          */
955         BUG_ON(skb_queue_is_last(list, skb));
956         return skb->next;
957 }
958 
959 /**
960  *      skb_queue_prev - return the prev packet in the queue
961  *      @list: queue head
962  *      @skb: current buffer
963  *
964  *      Return the prev packet in @list before @skb.  It is only valid to
965  *      call this if skb_queue_is_first() evaluates to false.
966  */
967 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
968                                              const struct sk_buff *skb)
969 {
970         /* This BUG_ON may seem severe, but if we just return then we
971          * are going to dereference garbage.
972          */
973         BUG_ON(skb_queue_is_first(list, skb));
974         return skb->prev;
975 }
976 
977 /**
978  *      skb_get - reference buffer
979  *      @skb: buffer to reference
980  *
981  *      Makes another reference to a socket buffer and returns a pointer
982  *      to the buffer.
983  */
984 static inline struct sk_buff *skb_get(struct sk_buff *skb)
985 {
986         atomic_inc(&skb->users);
987         return skb;
988 }
989 
990 /*
991  * If users == 1, we are the only owner and are can avoid redundant
992  * atomic change.
993  */
994 
995 /**
996  *      skb_cloned - is the buffer a clone
997  *      @skb: buffer to check
998  *
999  *      Returns true if the buffer was generated with skb_clone() and is
1000  *      one of multiple shared copies of the buffer. Cloned buffers are
1001  *      shared data so must not be written to under normal circumstances.
1002  */
1003 static inline int skb_cloned(const struct sk_buff *skb)
1004 {
1005         return skb->cloned &&
1006                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1007 }
1008 
1009 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1010 {
1011         might_sleep_if(pri & __GFP_WAIT);
1012 
1013         if (skb_cloned(skb))
1014                 return pskb_expand_head(skb, 0, 0, pri);
1015 
1016         return 0;
1017 }
1018 
1019 /**
1020  *      skb_header_cloned - is the header a clone
1021  *      @skb: buffer to check
1022  *
1023  *      Returns true if modifying the header part of the buffer requires
1024  *      the data to be copied.
1025  */
1026 static inline int skb_header_cloned(const struct sk_buff *skb)
1027 {
1028         int dataref;
1029 
1030         if (!skb->cloned)
1031                 return 0;
1032 
1033         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1034         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1035         return dataref != 1;
1036 }
1037 
1038 /**
1039  *      skb_header_release - release reference to header
1040  *      @skb: buffer to operate on
1041  *
1042  *      Drop a reference to the header part of the buffer.  This is done
1043  *      by acquiring a payload reference.  You must not read from the header
1044  *      part of skb->data after this.
1045  */
1046 static inline void skb_header_release(struct sk_buff *skb)
1047 {
1048         BUG_ON(skb->nohdr);
1049         skb->nohdr = 1;
1050         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1051 }
1052 
1053 /**
1054  *      skb_shared - is the buffer shared
1055  *      @skb: buffer to check
1056  *
1057  *      Returns true if more than one person has a reference to this
1058  *      buffer.
1059  */
1060 static inline int skb_shared(const struct sk_buff *skb)
1061 {
1062         return atomic_read(&skb->users) != 1;
1063 }
1064 
1065 /**
1066  *      skb_share_check - check if buffer is shared and if so clone it
1067  *      @skb: buffer to check
1068  *      @pri: priority for memory allocation
1069  *
1070  *      If the buffer is shared the buffer is cloned and the old copy
1071  *      drops a reference. A new clone with a single reference is returned.
1072  *      If the buffer is not shared the original buffer is returned. When
1073  *      being called from interrupt status or with spinlocks held pri must
1074  *      be GFP_ATOMIC.
1075  *
1076  *      NULL is returned on a memory allocation failure.
1077  */
1078 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1079 {
1080         might_sleep_if(pri & __GFP_WAIT);
1081         if (skb_shared(skb)) {
1082                 struct sk_buff *nskb = skb_clone(skb, pri);
1083 
1084                 if (likely(nskb))
1085                         consume_skb(skb);
1086                 else
1087                         kfree_skb(skb);
1088                 skb = nskb;
1089         }
1090         return skb;
1091 }
1092 
1093 /*
1094  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1095  *      packets to handle cases where we have a local reader and forward
1096  *      and a couple of other messy ones. The normal one is tcpdumping
1097  *      a packet thats being forwarded.
1098  */
1099 
1100 /**
1101  *      skb_unshare - make a copy of a shared buffer
1102  *      @skb: buffer to check
1103  *      @pri: priority for memory allocation
1104  *
1105  *      If the socket buffer is a clone then this function creates a new
1106  *      copy of the data, drops a reference count on the old copy and returns
1107  *      the new copy with the reference count at 1. If the buffer is not a clone
1108  *      the original buffer is returned. When called with a spinlock held or
1109  *      from interrupt state @pri must be %GFP_ATOMIC
1110  *
1111  *      %NULL is returned on a memory allocation failure.
1112  */
1113 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1114                                           gfp_t pri)
1115 {
1116         might_sleep_if(pri & __GFP_WAIT);
1117         if (skb_cloned(skb)) {
1118                 struct sk_buff *nskb = skb_copy(skb, pri);
1119                 kfree_skb(skb); /* Free our shared copy */
1120                 skb = nskb;
1121         }
1122         return skb;
1123 }
1124 
1125 /**
1126  *      skb_peek - peek at the head of an &sk_buff_head
1127  *      @list_: list to peek at
1128  *
1129  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1130  *      be careful with this one. A peek leaves the buffer on the
1131  *      list and someone else may run off with it. You must hold
1132  *      the appropriate locks or have a private queue to do this.
1133  *
1134  *      Returns %NULL for an empty list or a pointer to the head element.
1135  *      The reference count is not incremented and the reference is therefore
1136  *      volatile. Use with caution.
1137  */
1138 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1139 {
1140         struct sk_buff *skb = list_->next;
1141 
1142         if (skb == (struct sk_buff *)list_)
1143                 skb = NULL;
1144         return skb;
1145 }
1146 
1147 /**
1148  *      skb_peek_next - peek skb following the given one from a queue
1149  *      @skb: skb to start from
1150  *      @list_: list to peek at
1151  *
1152  *      Returns %NULL when the end of the list is met or a pointer to the
1153  *      next element. The reference count is not incremented and the
1154  *      reference is therefore volatile. Use with caution.
1155  */
1156 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1157                 const struct sk_buff_head *list_)
1158 {
1159         struct sk_buff *next = skb->next;
1160 
1161         if (next == (struct sk_buff *)list_)
1162                 next = NULL;
1163         return next;
1164 }
1165 
1166 /**
1167  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1168  *      @list_: list to peek at
1169  *
1170  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1171  *      be careful with this one. A peek leaves the buffer on the
1172  *      list and someone else may run off with it. You must hold
1173  *      the appropriate locks or have a private queue to do this.
1174  *
1175  *      Returns %NULL for an empty list or a pointer to the tail element.
1176  *      The reference count is not incremented and the reference is therefore
1177  *      volatile. Use with caution.
1178  */
1179 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1180 {
1181         struct sk_buff *skb = list_->prev;
1182 
1183         if (skb == (struct sk_buff *)list_)
1184                 skb = NULL;
1185         return skb;
1186 
1187 }
1188 
1189 /**
1190  *      skb_queue_len   - get queue length
1191  *      @list_: list to measure
1192  *
1193  *      Return the length of an &sk_buff queue.
1194  */
1195 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1196 {
1197         return list_->qlen;
1198 }
1199 
1200 /**
1201  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1202  *      @list: queue to initialize
1203  *
1204  *      This initializes only the list and queue length aspects of
1205  *      an sk_buff_head object.  This allows to initialize the list
1206  *      aspects of an sk_buff_head without reinitializing things like
1207  *      the spinlock.  It can also be used for on-stack sk_buff_head
1208  *      objects where the spinlock is known to not be used.
1209  */
1210 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1211 {
1212         list->prev = list->next = (struct sk_buff *)list;
1213         list->qlen = 0;
1214 }
1215 
1216 /*
1217  * This function creates a split out lock class for each invocation;
1218  * this is needed for now since a whole lot of users of the skb-queue
1219  * infrastructure in drivers have different locking usage (in hardirq)
1220  * than the networking core (in softirq only). In the long run either the
1221  * network layer or drivers should need annotation to consolidate the
1222  * main types of usage into 3 classes.
1223  */
1224 static inline void skb_queue_head_init(struct sk_buff_head *list)
1225 {
1226         spin_lock_init(&list->lock);
1227         __skb_queue_head_init(list);
1228 }
1229 
1230 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1231                 struct lock_class_key *class)
1232 {
1233         skb_queue_head_init(list);
1234         lockdep_set_class(&list->lock, class);
1235 }
1236 
1237 /*
1238  *      Insert an sk_buff on a list.
1239  *
1240  *      The "__skb_xxxx()" functions are the non-atomic ones that
1241  *      can only be called with interrupts disabled.
1242  */
1243 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1244                 struct sk_buff_head *list);
1245 static inline void __skb_insert(struct sk_buff *newsk,
1246                                 struct sk_buff *prev, struct sk_buff *next,
1247                                 struct sk_buff_head *list)
1248 {
1249         newsk->next = next;
1250         newsk->prev = prev;
1251         next->prev  = prev->next = newsk;
1252         list->qlen++;
1253 }
1254 
1255 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1256                                       struct sk_buff *prev,
1257                                       struct sk_buff *next)
1258 {
1259         struct sk_buff *first = list->next;
1260         struct sk_buff *last = list->prev;
1261 
1262         first->prev = prev;
1263         prev->next = first;
1264 
1265         last->next = next;
1266         next->prev = last;
1267 }
1268 
1269 /**
1270  *      skb_queue_splice - join two skb lists, this is designed for stacks
1271  *      @list: the new list to add
1272  *      @head: the place to add it in the first list
1273  */
1274 static inline void skb_queue_splice(const struct sk_buff_head *list,
1275                                     struct sk_buff_head *head)
1276 {
1277         if (!skb_queue_empty(list)) {
1278                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1279                 head->qlen += list->qlen;
1280         }
1281 }
1282 
1283 /**
1284  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1285  *      @list: the new list to add
1286  *      @head: the place to add it in the first list
1287  *
1288  *      The list at @list is reinitialised
1289  */
1290 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1291                                          struct sk_buff_head *head)
1292 {
1293         if (!skb_queue_empty(list)) {
1294                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1295                 head->qlen += list->qlen;
1296                 __skb_queue_head_init(list);
1297         }
1298 }
1299 
1300 /**
1301  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1302  *      @list: the new list to add
1303  *      @head: the place to add it in the first list
1304  */
1305 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1306                                          struct sk_buff_head *head)
1307 {
1308         if (!skb_queue_empty(list)) {
1309                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1310                 head->qlen += list->qlen;
1311         }
1312 }
1313 
1314 /**
1315  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1316  *      @list: the new list to add
1317  *      @head: the place to add it in the first list
1318  *
1319  *      Each of the lists is a queue.
1320  *      The list at @list is reinitialised
1321  */
1322 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1323                                               struct sk_buff_head *head)
1324 {
1325         if (!skb_queue_empty(list)) {
1326                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1327                 head->qlen += list->qlen;
1328                 __skb_queue_head_init(list);
1329         }
1330 }
1331 
1332 /**
1333  *      __skb_queue_after - queue a buffer at the list head
1334  *      @list: list to use
1335  *      @prev: place after this buffer
1336  *      @newsk: buffer to queue
1337  *
1338  *      Queue a buffer int the middle of a list. This function takes no locks
1339  *      and you must therefore hold required locks before calling it.
1340  *
1341  *      A buffer cannot be placed on two lists at the same time.
1342  */
1343 static inline void __skb_queue_after(struct sk_buff_head *list,
1344                                      struct sk_buff *prev,
1345                                      struct sk_buff *newsk)
1346 {
1347         __skb_insert(newsk, prev, prev->next, list);
1348 }
1349 
1350 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1351                 struct sk_buff_head *list);
1352 
1353 static inline void __skb_queue_before(struct sk_buff_head *list,
1354                                       struct sk_buff *next,
1355                                       struct sk_buff *newsk)
1356 {
1357         __skb_insert(newsk, next->prev, next, list);
1358 }
1359 
1360 /**
1361  *      __skb_queue_head - queue a buffer at the list head
1362  *      @list: list to use
1363  *      @newsk: buffer to queue
1364  *
1365  *      Queue a buffer at the start of a list. This function takes no locks
1366  *      and you must therefore hold required locks before calling it.
1367  *
1368  *      A buffer cannot be placed on two lists at the same time.
1369  */
1370 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1371 static inline void __skb_queue_head(struct sk_buff_head *list,
1372                                     struct sk_buff *newsk)
1373 {
1374         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1375 }
1376 
1377 /**
1378  *      __skb_queue_tail - queue a buffer at the list tail
1379  *      @list: list to use
1380  *      @newsk: buffer to queue
1381  *
1382  *      Queue a buffer at the end of a list. This function takes no locks
1383  *      and you must therefore hold required locks before calling it.
1384  *
1385  *      A buffer cannot be placed on two lists at the same time.
1386  */
1387 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1388 static inline void __skb_queue_tail(struct sk_buff_head *list,
1389                                    struct sk_buff *newsk)
1390 {
1391         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1392 }
1393 
1394 /*
1395  * remove sk_buff from list. _Must_ be called atomically, and with
1396  * the list known..
1397  */
1398 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1399 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1400 {
1401         struct sk_buff *next, *prev;
1402 
1403         list->qlen--;
1404         next       = skb->next;
1405         prev       = skb->prev;
1406         skb->next  = skb->prev = NULL;
1407         next->prev = prev;
1408         prev->next = next;
1409 }
1410 
1411 /**
1412  *      __skb_dequeue - remove from the head of the queue
1413  *      @list: list to dequeue from
1414  *
1415  *      Remove the head of the list. This function does not take any locks
1416  *      so must be used with appropriate locks held only. The head item is
1417  *      returned or %NULL if the list is empty.
1418  */
1419 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1420 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1421 {
1422         struct sk_buff *skb = skb_peek(list);
1423         if (skb)
1424                 __skb_unlink(skb, list);
1425         return skb;
1426 }
1427 
1428 /**
1429  *      __skb_dequeue_tail - remove from the tail of the queue
1430  *      @list: list to dequeue from
1431  *
1432  *      Remove the tail of the list. This function does not take any locks
1433  *      so must be used with appropriate locks held only. The tail item is
1434  *      returned or %NULL if the list is empty.
1435  */
1436 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1437 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1438 {
1439         struct sk_buff *skb = skb_peek_tail(list);
1440         if (skb)
1441                 __skb_unlink(skb, list);
1442         return skb;
1443 }
1444 
1445 
1446 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1447 {
1448         return skb->data_len;
1449 }
1450 
1451 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1452 {
1453         return skb->len - skb->data_len;
1454 }
1455 
1456 static inline int skb_pagelen(const struct sk_buff *skb)
1457 {
1458         int i, len = 0;
1459 
1460         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1461                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1462         return len + skb_headlen(skb);
1463 }
1464 
1465 /**
1466  * __skb_fill_page_desc - initialise a paged fragment in an skb
1467  * @skb: buffer containing fragment to be initialised
1468  * @i: paged fragment index to initialise
1469  * @page: the page to use for this fragment
1470  * @off: the offset to the data with @page
1471  * @size: the length of the data
1472  *
1473  * Initialises the @i'th fragment of @skb to point to &size bytes at
1474  * offset @off within @page.
1475  *
1476  * Does not take any additional reference on the fragment.
1477  */
1478 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1479                                         struct page *page, int off, int size)
1480 {
1481         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1482 
1483         /*
1484          * Propagate page->pfmemalloc to the skb if we can. The problem is
1485          * that not all callers have unique ownership of the page. If
1486          * pfmemalloc is set, we check the mapping as a mapping implies
1487          * page->index is set (index and pfmemalloc share space).
1488          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1489          * do not lose pfmemalloc information as the pages would not be
1490          * allocated using __GFP_MEMALLOC.
1491          */
1492         frag->page.p              = page;
1493         frag->page_offset         = off;
1494         skb_frag_size_set(frag, size);
1495 
1496         page = compound_head(page);
1497         if (page->pfmemalloc && !page->mapping)
1498                 skb->pfmemalloc = true;
1499 }
1500 
1501 /**
1502  * skb_fill_page_desc - initialise a paged fragment in an skb
1503  * @skb: buffer containing fragment to be initialised
1504  * @i: paged fragment index to initialise
1505  * @page: the page to use for this fragment
1506  * @off: the offset to the data with @page
1507  * @size: the length of the data
1508  *
1509  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1510  * @skb to point to @size bytes at offset @off within @page. In
1511  * addition updates @skb such that @i is the last fragment.
1512  *
1513  * Does not take any additional reference on the fragment.
1514  */
1515 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1516                                       struct page *page, int off, int size)
1517 {
1518         __skb_fill_page_desc(skb, i, page, off, size);
1519         skb_shinfo(skb)->nr_frags = i + 1;
1520 }
1521 
1522 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1523                      int size, unsigned int truesize);
1524 
1525 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1526                           unsigned int truesize);
1527 
1528 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1529 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1530 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1531 
1532 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1533 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1534 {
1535         return skb->head + skb->tail;
1536 }
1537 
1538 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1539 {
1540         skb->tail = skb->data - skb->head;
1541 }
1542 
1543 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1544 {
1545         skb_reset_tail_pointer(skb);
1546         skb->tail += offset;
1547 }
1548 
1549 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1550 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1551 {
1552         return skb->tail;
1553 }
1554 
1555 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1556 {
1557         skb->tail = skb->data;
1558 }
1559 
1560 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1561 {
1562         skb->tail = skb->data + offset;
1563 }
1564 
1565 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1566 
1567 /*
1568  *      Add data to an sk_buff
1569  */
1570 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1571 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1572 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1573 {
1574         unsigned char *tmp = skb_tail_pointer(skb);
1575         SKB_LINEAR_ASSERT(skb);
1576         skb->tail += len;
1577         skb->len  += len;
1578         return tmp;
1579 }
1580 
1581 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1582 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1583 {
1584         skb->data -= len;
1585         skb->len  += len;
1586         return skb->data;
1587 }
1588 
1589 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1590 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1591 {
1592         skb->len -= len;
1593         BUG_ON(skb->len < skb->data_len);
1594         return skb->data += len;
1595 }
1596 
1597 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1598 {
1599         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1600 }
1601 
1602 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1603 
1604 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1605 {
1606         if (len > skb_headlen(skb) &&
1607             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1608                 return NULL;
1609         skb->len -= len;
1610         return skb->data += len;
1611 }
1612 
1613 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1614 {
1615         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1616 }
1617 
1618 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1619 {
1620         if (likely(len <= skb_headlen(skb)))
1621                 return 1;
1622         if (unlikely(len > skb->len))
1623                 return 0;
1624         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1625 }
1626 
1627 /**
1628  *      skb_headroom - bytes at buffer head
1629  *      @skb: buffer to check
1630  *
1631  *      Return the number of bytes of free space at the head of an &sk_buff.
1632  */
1633 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1634 {
1635         return skb->data - skb->head;
1636 }
1637 
1638 /**
1639  *      skb_tailroom - bytes at buffer end
1640  *      @skb: buffer to check
1641  *
1642  *      Return the number of bytes of free space at the tail of an sk_buff
1643  */
1644 static inline int skb_tailroom(const struct sk_buff *skb)
1645 {
1646         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1647 }
1648 
1649 /**
1650  *      skb_availroom - bytes at buffer end
1651  *      @skb: buffer to check
1652  *
1653  *      Return the number of bytes of free space at the tail of an sk_buff
1654  *      allocated by sk_stream_alloc()
1655  */
1656 static inline int skb_availroom(const struct sk_buff *skb)
1657 {
1658         if (skb_is_nonlinear(skb))
1659                 return 0;
1660 
1661         return skb->end - skb->tail - skb->reserved_tailroom;
1662 }
1663 
1664 /**
1665  *      skb_reserve - adjust headroom
1666  *      @skb: buffer to alter
1667  *      @len: bytes to move
1668  *
1669  *      Increase the headroom of an empty &sk_buff by reducing the tail
1670  *      room. This is only allowed for an empty buffer.
1671  */
1672 static inline void skb_reserve(struct sk_buff *skb, int len)
1673 {
1674         skb->data += len;
1675         skb->tail += len;
1676 }
1677 
1678 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1679 {
1680         skb->inner_mac_header = skb->mac_header;
1681         skb->inner_network_header = skb->network_header;
1682         skb->inner_transport_header = skb->transport_header;
1683 }
1684 
1685 static inline void skb_reset_mac_len(struct sk_buff *skb)
1686 {
1687         skb->mac_len = skb->network_header - skb->mac_header;
1688 }
1689 
1690 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1691                                                         *skb)
1692 {
1693         return skb->head + skb->inner_transport_header;
1694 }
1695 
1696 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1697 {
1698         skb->inner_transport_header = skb->data - skb->head;
1699 }
1700 
1701 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1702                                                    const int offset)
1703 {
1704         skb_reset_inner_transport_header(skb);
1705         skb->inner_transport_header += offset;
1706 }
1707 
1708 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1709 {
1710         return skb->head + skb->inner_network_header;
1711 }
1712 
1713 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1714 {
1715         skb->inner_network_header = skb->data - skb->head;
1716 }
1717 
1718 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1719                                                 const int offset)
1720 {
1721         skb_reset_inner_network_header(skb);
1722         skb->inner_network_header += offset;
1723 }
1724 
1725 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1726 {
1727         return skb->head + skb->inner_mac_header;
1728 }
1729 
1730 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1731 {
1732         skb->inner_mac_header = skb->data - skb->head;
1733 }
1734 
1735 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1736                                             const int offset)
1737 {
1738         skb_reset_inner_mac_header(skb);
1739         skb->inner_mac_header += offset;
1740 }
1741 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1742 {
1743         return skb->transport_header != (typeof(skb->transport_header))~0U;
1744 }
1745 
1746 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1747 {
1748         return skb->head + skb->transport_header;
1749 }
1750 
1751 static inline void skb_reset_transport_header(struct sk_buff *skb)
1752 {
1753         skb->transport_header = skb->data - skb->head;
1754 }
1755 
1756 static inline void skb_set_transport_header(struct sk_buff *skb,
1757                                             const int offset)
1758 {
1759         skb_reset_transport_header(skb);
1760         skb->transport_header += offset;
1761 }
1762 
1763 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1764 {
1765         return skb->head + skb->network_header;
1766 }
1767 
1768 static inline void skb_reset_network_header(struct sk_buff *skb)
1769 {
1770         skb->network_header = skb->data - skb->head;
1771 }
1772 
1773 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1774 {
1775         skb_reset_network_header(skb);
1776         skb->network_header += offset;
1777 }
1778 
1779 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1780 {
1781         return skb->head + skb->mac_header;
1782 }
1783 
1784 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1785 {
1786         return skb->mac_header != (typeof(skb->mac_header))~0U;
1787 }
1788 
1789 static inline void skb_reset_mac_header(struct sk_buff *skb)
1790 {
1791         skb->mac_header = skb->data - skb->head;
1792 }
1793 
1794 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1795 {
1796         skb_reset_mac_header(skb);
1797         skb->mac_header += offset;
1798 }
1799 
1800 static inline void skb_pop_mac_header(struct sk_buff *skb)
1801 {
1802         skb->mac_header = skb->network_header;
1803 }
1804 
1805 static inline void skb_probe_transport_header(struct sk_buff *skb,
1806                                               const int offset_hint)
1807 {
1808         struct flow_keys keys;
1809 
1810         if (skb_transport_header_was_set(skb))
1811                 return;
1812         else if (skb_flow_dissect(skb, &keys))
1813                 skb_set_transport_header(skb, keys.thoff);
1814         else
1815                 skb_set_transport_header(skb, offset_hint);
1816 }
1817 
1818 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1819 {
1820         if (skb_mac_header_was_set(skb)) {
1821                 const unsigned char *old_mac = skb_mac_header(skb);
1822 
1823                 skb_set_mac_header(skb, -skb->mac_len);
1824                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1825         }
1826 }
1827 
1828 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1829 {
1830         return skb->csum_start - skb_headroom(skb);
1831 }
1832 
1833 static inline int skb_transport_offset(const struct sk_buff *skb)
1834 {
1835         return skb_transport_header(skb) - skb->data;
1836 }
1837 
1838 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1839 {
1840         return skb->transport_header - skb->network_header;
1841 }
1842 
1843 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1844 {
1845         return skb->inner_transport_header - skb->inner_network_header;
1846 }
1847 
1848 static inline int skb_network_offset(const struct sk_buff *skb)
1849 {
1850         return skb_network_header(skb) - skb->data;
1851 }
1852 
1853 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1854 {
1855         return skb_inner_network_header(skb) - skb->data;
1856 }
1857 
1858 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1859 {
1860         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1861 }
1862 
1863 static inline void skb_pop_rcv_encapsulation(struct sk_buff *skb)
1864 {
1865         /* Only continue with checksum unnecessary if device indicated
1866          * it is valid across encapsulation (skb->encapsulation was set).
1867          */
1868         if (skb->ip_summed == CHECKSUM_UNNECESSARY && !skb->encapsulation)
1869                 skb->ip_summed = CHECKSUM_NONE;
1870 
1871         skb->encapsulation = 0;
1872         skb->csum_valid = 0;
1873 }
1874 
1875 /*
1876  * CPUs often take a performance hit when accessing unaligned memory
1877  * locations. The actual performance hit varies, it can be small if the
1878  * hardware handles it or large if we have to take an exception and fix it
1879  * in software.
1880  *
1881  * Since an ethernet header is 14 bytes network drivers often end up with
1882  * the IP header at an unaligned offset. The IP header can be aligned by
1883  * shifting the start of the packet by 2 bytes. Drivers should do this
1884  * with:
1885  *
1886  * skb_reserve(skb, NET_IP_ALIGN);
1887  *
1888  * The downside to this alignment of the IP header is that the DMA is now
1889  * unaligned. On some architectures the cost of an unaligned DMA is high
1890  * and this cost outweighs the gains made by aligning the IP header.
1891  *
1892  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1893  * to be overridden.
1894  */
1895 #ifndef NET_IP_ALIGN
1896 #define NET_IP_ALIGN    2
1897 #endif
1898 
1899 /*
1900  * The networking layer reserves some headroom in skb data (via
1901  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1902  * the header has to grow. In the default case, if the header has to grow
1903  * 32 bytes or less we avoid the reallocation.
1904  *
1905  * Unfortunately this headroom changes the DMA alignment of the resulting
1906  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1907  * on some architectures. An architecture can override this value,
1908  * perhaps setting it to a cacheline in size (since that will maintain
1909  * cacheline alignment of the DMA). It must be a power of 2.
1910  *
1911  * Various parts of the networking layer expect at least 32 bytes of
1912  * headroom, you should not reduce this.
1913  *
1914  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
1915  * to reduce average number of cache lines per packet.
1916  * get_rps_cpus() for example only access one 64 bytes aligned block :
1917  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
1918  */
1919 #ifndef NET_SKB_PAD
1920 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
1921 #endif
1922 
1923 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1924 
1925 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1926 {
1927         if (unlikely(skb_is_nonlinear(skb))) {
1928                 WARN_ON(1);
1929                 return;
1930         }
1931         skb->len = len;
1932         skb_set_tail_pointer(skb, len);
1933 }
1934 
1935 void skb_trim(struct sk_buff *skb, unsigned int len);
1936 
1937 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1938 {
1939         if (skb->data_len)
1940                 return ___pskb_trim(skb, len);
1941         __skb_trim(skb, len);
1942         return 0;
1943 }
1944 
1945 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1946 {
1947         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1948 }
1949 
1950 /**
1951  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1952  *      @skb: buffer to alter
1953  *      @len: new length
1954  *
1955  *      This is identical to pskb_trim except that the caller knows that
1956  *      the skb is not cloned so we should never get an error due to out-
1957  *      of-memory.
1958  */
1959 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1960 {
1961         int err = pskb_trim(skb, len);
1962         BUG_ON(err);
1963 }
1964 
1965 /**
1966  *      skb_orphan - orphan a buffer
1967  *      @skb: buffer to orphan
1968  *
1969  *      If a buffer currently has an owner then we call the owner's
1970  *      destructor function and make the @skb unowned. The buffer continues
1971  *      to exist but is no longer charged to its former owner.
1972  */
1973 static inline void skb_orphan(struct sk_buff *skb)
1974 {
1975         if (skb->destructor) {
1976                 skb->destructor(skb);
1977                 skb->destructor = NULL;
1978                 skb->sk         = NULL;
1979         } else {
1980                 BUG_ON(skb->sk);
1981         }
1982 }
1983 
1984 /**
1985  *      skb_orphan_frags - orphan the frags contained in a buffer
1986  *      @skb: buffer to orphan frags from
1987  *      @gfp_mask: allocation mask for replacement pages
1988  *
1989  *      For each frag in the SKB which needs a destructor (i.e. has an
1990  *      owner) create a copy of that frag and release the original
1991  *      page by calling the destructor.
1992  */
1993 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
1994 {
1995         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
1996                 return 0;
1997         return skb_copy_ubufs(skb, gfp_mask);
1998 }
1999 
2000 /**
2001  *      __skb_queue_purge - empty a list
2002  *      @list: list to empty
2003  *
2004  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2005  *      the list and one reference dropped. This function does not take the
2006  *      list lock and the caller must hold the relevant locks to use it.
2007  */
2008 void skb_queue_purge(struct sk_buff_head *list);
2009 static inline void __skb_queue_purge(struct sk_buff_head *list)
2010 {
2011         struct sk_buff *skb;
2012         while ((skb = __skb_dequeue(list)) != NULL)
2013                 kfree_skb(skb);
2014 }
2015 
2016 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
2017 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
2018 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
2019 
2020 void *netdev_alloc_frag(unsigned int fragsz);
2021 
2022 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2023                                    gfp_t gfp_mask);
2024 
2025 /**
2026  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2027  *      @dev: network device to receive on
2028  *      @length: length to allocate
2029  *
2030  *      Allocate a new &sk_buff and assign it a usage count of one. The
2031  *      buffer has unspecified headroom built in. Users should allocate
2032  *      the headroom they think they need without accounting for the
2033  *      built in space. The built in space is used for optimisations.
2034  *
2035  *      %NULL is returned if there is no free memory. Although this function
2036  *      allocates memory it can be called from an interrupt.
2037  */
2038 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2039                                                unsigned int length)
2040 {
2041         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2042 }
2043 
2044 /* legacy helper around __netdev_alloc_skb() */
2045 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2046                                               gfp_t gfp_mask)
2047 {
2048         return __netdev_alloc_skb(NULL, length, gfp_mask);
2049 }
2050 
2051 /* legacy helper around netdev_alloc_skb() */
2052 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2053 {
2054         return netdev_alloc_skb(NULL, length);
2055 }
2056 
2057 
2058 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2059                 unsigned int length, gfp_t gfp)
2060 {
2061         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2062 
2063         if (NET_IP_ALIGN && skb)
2064                 skb_reserve(skb, NET_IP_ALIGN);
2065         return skb;
2066 }
2067 
2068 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2069                 unsigned int length)
2070 {
2071         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2072 }
2073 
2074 /**
2075  *      __skb_alloc_pages - allocate pages for ps-rx on a skb and preserve pfmemalloc data
2076  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
2077  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
2078  *      @order: size of the allocation
2079  *
2080  *      Allocate a new page.
2081  *
2082  *      %NULL is returned if there is no free memory.
2083 */
2084 static inline struct page *__skb_alloc_pages(gfp_t gfp_mask,
2085                                               struct sk_buff *skb,
2086                                               unsigned int order)
2087 {
2088         struct page *page;
2089 
2090         gfp_mask |= __GFP_COLD;
2091 
2092         if (!(gfp_mask & __GFP_NOMEMALLOC))
2093                 gfp_mask |= __GFP_MEMALLOC;
2094 
2095         page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2096         if (skb && page && page->pfmemalloc)
2097                 skb->pfmemalloc = true;
2098 
2099         return page;
2100 }
2101 
2102 /**
2103  *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
2104  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
2105  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
2106  *
2107  *      Allocate a new page.
2108  *
2109  *      %NULL is returned if there is no free memory.
2110  */
2111 static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
2112                                              struct sk_buff *skb)
2113 {
2114         return __skb_alloc_pages(gfp_mask, skb, 0);
2115 }
2116 
2117 /**
2118  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2119  *      @page: The page that was allocated from skb_alloc_page
2120  *      @skb: The skb that may need pfmemalloc set
2121  */
2122 static inline void skb_propagate_pfmemalloc(struct page *page,
2123                                              struct sk_buff *skb)
2124 {
2125         if (page && page->pfmemalloc)
2126                 skb->pfmemalloc = true;
2127 }
2128 
2129 /**
2130  * skb_frag_page - retrieve the page referred to by a paged fragment
2131  * @frag: the paged fragment
2132  *
2133  * Returns the &struct page associated with @frag.
2134  */
2135 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2136 {
2137         return frag->page.p;
2138 }
2139 
2140 /**
2141  * __skb_frag_ref - take an addition reference on a paged fragment.
2142  * @frag: the paged fragment
2143  *
2144  * Takes an additional reference on the paged fragment @frag.
2145  */
2146 static inline void __skb_frag_ref(skb_frag_t *frag)
2147 {
2148         get_page(skb_frag_page(frag));
2149 }
2150 
2151 /**
2152  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2153  * @skb: the buffer
2154  * @f: the fragment offset.
2155  *
2156  * Takes an additional reference on the @f'th paged fragment of @skb.
2157  */
2158 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2159 {
2160         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2161 }
2162 
2163 /**
2164  * __skb_frag_unref - release a reference on a paged fragment.
2165  * @frag: the paged fragment
2166  *
2167  * Releases a reference on the paged fragment @frag.
2168  */
2169 static inline void __skb_frag_unref(skb_frag_t *frag)
2170 {
2171         put_page(skb_frag_page(frag));
2172 }
2173 
2174 /**
2175  * skb_frag_unref - release a reference on a paged fragment of an skb.
2176  * @skb: the buffer
2177  * @f: the fragment offset
2178  *
2179  * Releases a reference on the @f'th paged fragment of @skb.
2180  */
2181 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2182 {
2183         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2184 }
2185 
2186 /**
2187  * skb_frag_address - gets the address of the data contained in a paged fragment
2188  * @frag: the paged fragment buffer
2189  *
2190  * Returns the address of the data within @frag. The page must already
2191  * be mapped.
2192  */
2193 static inline void *skb_frag_address(const skb_frag_t *frag)
2194 {
2195         return page_address(skb_frag_page(frag)) + frag->page_offset;
2196 }
2197 
2198 /**
2199  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2200  * @frag: the paged fragment buffer
2201  *
2202  * Returns the address of the data within @frag. Checks that the page
2203  * is mapped and returns %NULL otherwise.
2204  */
2205 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2206 {
2207         void *ptr = page_address(skb_frag_page(frag));
2208         if (unlikely(!ptr))
2209                 return NULL;
2210 
2211         return ptr + frag->page_offset;
2212 }
2213 
2214 /**
2215  * __skb_frag_set_page - sets the page contained in a paged fragment
2216  * @frag: the paged fragment
2217  * @page: the page to set
2218  *
2219  * Sets the fragment @frag to contain @page.
2220  */
2221 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2222 {
2223         frag->page.p = page;
2224 }
2225 
2226 /**
2227  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2228  * @skb: the buffer
2229  * @f: the fragment offset
2230  * @page: the page to set
2231  *
2232  * Sets the @f'th fragment of @skb to contain @page.
2233  */
2234 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2235                                      struct page *page)
2236 {
2237         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2238 }
2239 
2240 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2241 
2242 /**
2243  * skb_frag_dma_map - maps a paged fragment via the DMA API
2244  * @dev: the device to map the fragment to
2245  * @frag: the paged fragment to map
2246  * @offset: the offset within the fragment (starting at the
2247  *          fragment's own offset)
2248  * @size: the number of bytes to map
2249  * @dir: the direction of the mapping (%PCI_DMA_*)
2250  *
2251  * Maps the page associated with @frag to @device.
2252  */
2253 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2254                                           const skb_frag_t *frag,
2255                                           size_t offset, size_t size,
2256                                           enum dma_data_direction dir)
2257 {
2258         return dma_map_page(dev, skb_frag_page(frag),
2259                             frag->page_offset + offset, size, dir);
2260 }
2261 
2262 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2263                                         gfp_t gfp_mask)
2264 {
2265         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2266 }
2267 
2268 
2269 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2270                                                   gfp_t gfp_mask)
2271 {
2272         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2273 }
2274 
2275 
2276 /**
2277  *      skb_clone_writable - is the header of a clone writable
2278  *      @skb: buffer to check
2279  *      @len: length up to which to write
2280  *
2281  *      Returns true if modifying the header part of the cloned buffer
2282  *      does not requires the data to be copied.
2283  */
2284 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2285 {
2286         return !skb_header_cloned(skb) &&
2287                skb_headroom(skb) + len <= skb->hdr_len;
2288 }
2289 
2290 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2291                             int cloned)
2292 {
2293         int delta = 0;
2294 
2295         if (headroom > skb_headroom(skb))
2296                 delta = headroom - skb_headroom(skb);
2297 
2298         if (delta || cloned)
2299                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2300                                         GFP_ATOMIC);
2301         return 0;
2302 }
2303 
2304 /**
2305  *      skb_cow - copy header of skb when it is required
2306  *      @skb: buffer to cow
2307  *      @headroom: needed headroom
2308  *
2309  *      If the skb passed lacks sufficient headroom or its data part
2310  *      is shared, data is reallocated. If reallocation fails, an error
2311  *      is returned and original skb is not changed.
2312  *
2313  *      The result is skb with writable area skb->head...skb->tail
2314  *      and at least @headroom of space at head.
2315  */
2316 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2317 {
2318         return __skb_cow(skb, headroom, skb_cloned(skb));
2319 }
2320 
2321 /**
2322  *      skb_cow_head - skb_cow but only making the head writable
2323  *      @skb: buffer to cow
2324  *      @headroom: needed headroom
2325  *
2326  *      This function is identical to skb_cow except that we replace the
2327  *      skb_cloned check by skb_header_cloned.  It should be used when
2328  *      you only need to push on some header and do not need to modify
2329  *      the data.
2330  */
2331 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2332 {
2333         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2334 }
2335 
2336 /**
2337  *      skb_padto       - pad an skbuff up to a minimal size
2338  *      @skb: buffer to pad
2339  *      @len: minimal length
2340  *
2341  *      Pads up a buffer to ensure the trailing bytes exist and are
2342  *      blanked. If the buffer already contains sufficient data it
2343  *      is untouched. Otherwise it is extended. Returns zero on
2344  *      success. The skb is freed on error.
2345  */
2346  
2347 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2348 {
2349         unsigned int size = skb->len;
2350         if (likely(size >= len))
2351                 return 0;
2352         return skb_pad(skb, len - size);
2353 }
2354 
2355 static inline int skb_add_data(struct sk_buff *skb,
2356                                char __user *from, int copy)
2357 {
2358         const int off = skb->len;
2359 
2360         if (skb->ip_summed == CHECKSUM_NONE) {
2361                 int err = 0;
2362                 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2363                                                             copy, 0, &err);
2364                 if (!err) {
2365                         skb->csum = csum_block_add(skb->csum, csum, off);
2366                         return 0;
2367                 }
2368         } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2369                 return 0;
2370 
2371         __skb_trim(skb, off);
2372         return -EFAULT;
2373 }
2374 
2375 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2376                                     const struct page *page, int off)
2377 {
2378         if (i) {
2379                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2380 
2381                 return page == skb_frag_page(frag) &&
2382                        off == frag->page_offset + skb_frag_size(frag);
2383         }
2384         return false;
2385 }
2386 
2387 static inline int __skb_linearize(struct sk_buff *skb)
2388 {
2389         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2390 }
2391 
2392 /**
2393  *      skb_linearize - convert paged skb to linear one
2394  *      @skb: buffer to linarize
2395  *
2396  *      If there is no free memory -ENOMEM is returned, otherwise zero
2397  *      is returned and the old skb data released.
2398  */
2399 static inline int skb_linearize(struct sk_buff *skb)
2400 {
2401         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2402 }
2403 
2404 /**
2405  * skb_has_shared_frag - can any frag be overwritten
2406  * @skb: buffer to test
2407  *
2408  * Return true if the skb has at least one frag that might be modified
2409  * by an external entity (as in vmsplice()/sendfile())
2410  */
2411 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2412 {
2413         return skb_is_nonlinear(skb) &&
2414                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2415 }
2416 
2417 /**
2418  *      skb_linearize_cow - make sure skb is linear and writable
2419  *      @skb: buffer to process
2420  *
2421  *      If there is no free memory -ENOMEM is returned, otherwise zero
2422  *      is returned and the old skb data released.
2423  */
2424 static inline int skb_linearize_cow(struct sk_buff *skb)
2425 {
2426         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2427                __skb_linearize(skb) : 0;
2428 }
2429 
2430 /**
2431  *      skb_postpull_rcsum - update checksum for received skb after pull
2432  *      @skb: buffer to update
2433  *      @start: start of data before pull
2434  *      @len: length of data pulled
2435  *
2436  *      After doing a pull on a received packet, you need to call this to
2437  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2438  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2439  */
2440 
2441 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2442                                       const void *start, unsigned int len)
2443 {
2444         if (skb->ip_summed == CHECKSUM_COMPLETE)
2445                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2446 }
2447 
2448 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2449 
2450 /**
2451  *      pskb_trim_rcsum - trim received skb and update checksum
2452  *      @skb: buffer to trim
2453  *      @len: new length
2454  *
2455  *      This is exactly the same as pskb_trim except that it ensures the
2456  *      checksum of received packets are still valid after the operation.
2457  */
2458 
2459 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2460 {
2461         if (likely(len >= skb->len))
2462                 return 0;
2463         if (skb->ip_summed == CHECKSUM_COMPLETE)
2464                 skb->ip_summed = CHECKSUM_NONE;
2465         return __pskb_trim(skb, len);
2466 }
2467 
2468 #define skb_queue_walk(queue, skb) \
2469                 for (skb = (queue)->next;                                       \
2470                      skb != (struct sk_buff *)(queue);                          \
2471                      skb = skb->next)
2472 
2473 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2474                 for (skb = (queue)->next, tmp = skb->next;                      \
2475                      skb != (struct sk_buff *)(queue);                          \
2476                      skb = tmp, tmp = skb->next)
2477 
2478 #define skb_queue_walk_from(queue, skb)                                         \
2479                 for (; skb != (struct sk_buff *)(queue);                        \
2480                      skb = skb->next)
2481 
2482 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2483                 for (tmp = skb->next;                                           \
2484                      skb != (struct sk_buff *)(queue);                          \
2485                      skb = tmp, tmp = skb->next)
2486 
2487 #define skb_queue_reverse_walk(queue, skb) \
2488                 for (skb = (queue)->prev;                                       \
2489                      skb != (struct sk_buff *)(queue);                          \
2490                      skb = skb->prev)
2491 
2492 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2493                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2494                      skb != (struct sk_buff *)(queue);                          \
2495                      skb = tmp, tmp = skb->prev)
2496 
2497 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2498                 for (tmp = skb->prev;                                           \
2499                      skb != (struct sk_buff *)(queue);                          \
2500                      skb = tmp, tmp = skb->prev)
2501 
2502 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2503 {
2504         return skb_shinfo(skb)->frag_list != NULL;
2505 }
2506 
2507 static inline void skb_frag_list_init(struct sk_buff *skb)
2508 {
2509         skb_shinfo(skb)->frag_list = NULL;
2510 }
2511 
2512 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2513 {
2514         frag->next = skb_shinfo(skb)->frag_list;
2515         skb_shinfo(skb)->frag_list = frag;
2516 }
2517 
2518 #define skb_walk_frags(skb, iter)       \
2519         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2520 
2521 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2522                                     int *peeked, int *off, int *err);
2523 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2524                                   int *err);
2525 unsigned int datagram_poll(struct file *file, struct socket *sock,
2526                            struct poll_table_struct *wait);
2527 int skb_copy_datagram_iovec(const struct sk_buff *from, int offset,
2528                             struct iovec *to, int size);
2529 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, int hlen,
2530                                      struct iovec *iov);
2531 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
2532                                  const struct iovec *from, int from_offset,
2533                                  int len);
2534 int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
2535                            int offset, size_t count);
2536 int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset,
2537                                   const struct iovec *to, int to_offset,
2538                                   int size);
2539 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2540 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2541 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2542 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2543 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2544 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2545                               int len, __wsum csum);
2546 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
2547                     struct pipe_inode_info *pipe, unsigned int len,
2548                     unsigned int flags);
2549 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2550 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
2551 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
2552                  int len, int hlen);
2553 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2554 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2555 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2556 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2557 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2558 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
2559 
2560 struct skb_checksum_ops {
2561         __wsum (*update)(const void *mem, int len, __wsum wsum);
2562         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2563 };
2564 
2565 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2566                       __wsum csum, const struct skb_checksum_ops *ops);
2567 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2568                     __wsum csum);
2569 
2570 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2571                                        int len, void *buffer)
2572 {
2573         int hlen = skb_headlen(skb);
2574 
2575         if (hlen - offset >= len)
2576                 return skb->data + offset;
2577 
2578         if (skb_copy_bits(skb, offset, buffer, len) < 0)
2579                 return NULL;
2580 
2581         return buffer;
2582 }
2583 
2584 /**
2585  *      skb_needs_linearize - check if we need to linearize a given skb
2586  *                            depending on the given device features.
2587  *      @skb: socket buffer to check
2588  *      @features: net device features
2589  *
2590  *      Returns true if either:
2591  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
2592  *      2. skb is fragmented and the device does not support SG.
2593  */
2594 static inline bool skb_needs_linearize(struct sk_buff *skb,
2595                                        netdev_features_t features)
2596 {
2597         return skb_is_nonlinear(skb) &&
2598                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
2599                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
2600 }
2601 
2602 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2603                                              void *to,
2604                                              const unsigned int len)
2605 {
2606         memcpy(to, skb->data, len);
2607 }
2608 
2609 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2610                                                     const int offset, void *to,
2611                                                     const unsigned int len)
2612 {
2613         memcpy(to, skb->data + offset, len);
2614 }
2615 
2616 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2617                                            const void *from,
2618                                            const unsigned int len)
2619 {
2620         memcpy(skb->data, from, len);
2621 }
2622 
2623 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2624                                                   const int offset,
2625                                                   const void *from,
2626                                                   const unsigned int len)
2627 {
2628         memcpy(skb->data + offset, from, len);
2629 }
2630 
2631 void skb_init(void);
2632 
2633 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2634 {
2635         return skb->tstamp;
2636 }
2637 
2638 /**
2639  *      skb_get_timestamp - get timestamp from a skb
2640  *      @skb: skb to get stamp from
2641  *      @stamp: pointer to struct timeval to store stamp in
2642  *
2643  *      Timestamps are stored in the skb as offsets to a base timestamp.
2644  *      This function converts the offset back to a struct timeval and stores
2645  *      it in stamp.
2646  */
2647 static inline void skb_get_timestamp(const struct sk_buff *skb,
2648                                      struct timeval *stamp)
2649 {
2650         *stamp = ktime_to_timeval(skb->tstamp);
2651 }
2652 
2653 static inline void skb_get_timestampns(const struct sk_buff *skb,
2654                                        struct timespec *stamp)
2655 {
2656         *stamp = ktime_to_timespec(skb->tstamp);
2657 }
2658 
2659 static inline void __net_timestamp(struct sk_buff *skb)
2660 {
2661         skb->tstamp = ktime_get_real();
2662 }
2663 
2664 static inline ktime_t net_timedelta(ktime_t t)
2665 {
2666         return ktime_sub(ktime_get_real(), t);
2667 }
2668 
2669 static inline ktime_t net_invalid_timestamp(void)
2670 {
2671         return ktime_set(0, 0);
2672 }
2673 
2674 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2675 
2676 void skb_clone_tx_timestamp(struct sk_buff *skb);
2677 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2678 
2679 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2680 
2681 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2682 {
2683 }
2684 
2685 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2686 {
2687         return false;
2688 }
2689 
2690 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2691 
2692 /**
2693  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2694  *
2695  * PHY drivers may accept clones of transmitted packets for
2696  * timestamping via their phy_driver.txtstamp method. These drivers
2697  * must call this function to return the skb back to the stack, with
2698  * or without a timestamp.
2699  *
2700  * @skb: clone of the the original outgoing packet
2701  * @hwtstamps: hardware time stamps, may be NULL if not available
2702  *
2703  */
2704 void skb_complete_tx_timestamp(struct sk_buff *skb,
2705                                struct skb_shared_hwtstamps *hwtstamps);
2706 
2707 void __skb_tstamp_tx(struct sk_buff *orig_skb,
2708                      struct skb_shared_hwtstamps *hwtstamps,
2709                      struct sock *sk, int tstype);
2710 
2711 /**
2712  * skb_tstamp_tx - queue clone of skb with send time stamps
2713  * @orig_skb:   the original outgoing packet
2714  * @hwtstamps:  hardware time stamps, may be NULL if not available
2715  *
2716  * If the skb has a socket associated, then this function clones the
2717  * skb (thus sharing the actual data and optional structures), stores
2718  * the optional hardware time stamping information (if non NULL) or
2719  * generates a software time stamp (otherwise), then queues the clone
2720  * to the error queue of the socket.  Errors are silently ignored.
2721  */
2722 void skb_tstamp_tx(struct sk_buff *orig_skb,
2723                    struct skb_shared_hwtstamps *hwtstamps);
2724 
2725 static inline void sw_tx_timestamp(struct sk_buff *skb)
2726 {
2727         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2728             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2729                 skb_tstamp_tx(skb, NULL);
2730 }
2731 
2732 /**
2733  * skb_tx_timestamp() - Driver hook for transmit timestamping
2734  *
2735  * Ethernet MAC Drivers should call this function in their hard_xmit()
2736  * function immediately before giving the sk_buff to the MAC hardware.
2737  *
2738  * Specifically, one should make absolutely sure that this function is
2739  * called before TX completion of this packet can trigger.  Otherwise
2740  * the packet could potentially already be freed.
2741  *
2742  * @skb: A socket buffer.
2743  */
2744 static inline void skb_tx_timestamp(struct sk_buff *skb)
2745 {
2746         skb_clone_tx_timestamp(skb);
2747         sw_tx_timestamp(skb);
2748 }
2749 
2750 /**
2751  * skb_complete_wifi_ack - deliver skb with wifi status
2752  *
2753  * @skb: the original outgoing packet
2754  * @acked: ack status
2755  *
2756  */
2757 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2758 
2759 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2760 __sum16 __skb_checksum_complete(struct sk_buff *skb);
2761 
2762 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2763 {
2764         return ((skb->ip_summed & CHECKSUM_UNNECESSARY) || skb->csum_valid);
2765 }
2766 
2767 /**
2768  *      skb_checksum_complete - Calculate checksum of an entire packet
2769  *      @skb: packet to process
2770  *
2771  *      This function calculates the checksum over the entire packet plus
2772  *      the value of skb->csum.  The latter can be used to supply the
2773  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2774  *      checksum.
2775  *
2776  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2777  *      this function can be used to verify that checksum on received
2778  *      packets.  In that case the function should return zero if the
2779  *      checksum is correct.  In particular, this function will return zero
2780  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2781  *      hardware has already verified the correctness of the checksum.
2782  */
2783 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2784 {
2785         return skb_csum_unnecessary(skb) ?
2786                0 : __skb_checksum_complete(skb);
2787 }
2788 
2789 /* Check if we need to perform checksum complete validation.
2790  *
2791  * Returns true if checksum complete is needed, false otherwise
2792  * (either checksum is unnecessary or zero checksum is allowed).
2793  */
2794 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
2795                                                   bool zero_okay,
2796                                                   __sum16 check)
2797 {
2798         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
2799                 skb->csum_valid = 1;
2800                 return false;
2801         }
2802 
2803         return true;
2804 }
2805 
2806 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
2807  * in checksum_init.
2808  */
2809 #define CHECKSUM_BREAK 76
2810 
2811 /* Validate (init) checksum based on checksum complete.
2812  *
2813  * Return values:
2814  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
2815  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
2816  *      checksum is stored in skb->csum for use in __skb_checksum_complete
2817  *   non-zero: value of invalid checksum
2818  *
2819  */
2820 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
2821                                                        bool complete,
2822                                                        __wsum psum)
2823 {
2824         if (skb->ip_summed == CHECKSUM_COMPLETE) {
2825                 if (!csum_fold(csum_add(psum, skb->csum))) {
2826                         skb->csum_valid = 1;
2827                         return 0;
2828                 }
2829         }
2830 
2831         skb->csum = psum;
2832 
2833         if (complete || skb->len <= CHECKSUM_BREAK) {
2834                 __sum16 csum;
2835 
2836                 csum = __skb_checksum_complete(skb);
2837                 skb->csum_valid = !csum;
2838                 return csum;
2839         }
2840 
2841         return 0;
2842 }
2843 
2844 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
2845 {
2846         return 0;
2847 }
2848 
2849 /* Perform checksum validate (init). Note that this is a macro since we only
2850  * want to calculate the pseudo header which is an input function if necessary.
2851  * First we try to validate without any computation (checksum unnecessary) and
2852  * then calculate based on checksum complete calling the function to compute
2853  * pseudo header.
2854  *
2855  * Return values:
2856  *   0: checksum is validated or try to in skb_checksum_complete
2857  *   non-zero: value of invalid checksum
2858  */
2859 #define __skb_checksum_validate(skb, proto, complete,                   \
2860                                 zero_okay, check, compute_pseudo)       \
2861 ({                                                                      \
2862         __sum16 __ret = 0;                                              \
2863         skb->csum_valid = 0;                                            \
2864         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
2865                 __ret = __skb_checksum_validate_complete(skb,           \
2866                                 complete, compute_pseudo(skb, proto));  \
2867         __ret;                                                          \
2868 })
2869 
2870 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
2871         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
2872 
2873 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
2874         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
2875 
2876 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
2877         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
2878 
2879 #define skb_checksum_validate_zero_check(skb, proto, check,             \
2880                                          compute_pseudo)                \
2881         __skb_checksum_validate_(skb, proto, true, true, check, compute_pseudo)
2882 
2883 #define skb_checksum_simple_validate(skb)                               \
2884         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
2885 
2886 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2887 void nf_conntrack_destroy(struct nf_conntrack *nfct);
2888 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
2889 {
2890         if (nfct && atomic_dec_and_test(&nfct->use))
2891                 nf_conntrack_destroy(nfct);
2892 }
2893 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
2894 {
2895         if (nfct)
2896                 atomic_inc(&nfct->use);
2897 }
2898 #endif
2899 #ifdef CONFIG_BRIDGE_NETFILTER
2900 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
2901 {
2902         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
2903                 kfree(nf_bridge);
2904 }
2905 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
2906 {
2907         if (nf_bridge)
2908                 atomic_inc(&nf_bridge->use);
2909 }
2910 #endif /* CONFIG_BRIDGE_NETFILTER */
2911 static inline void nf_reset(struct sk_buff *skb)
2912 {
2913 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2914         nf_conntrack_put(skb->nfct);
2915         skb->nfct = NULL;
2916 #endif
2917 #ifdef CONFIG_BRIDGE_NETFILTER
2918         nf_bridge_put(skb->nf_bridge);
2919         skb->nf_bridge = NULL;
2920 #endif
2921 }
2922 
2923 static inline void nf_reset_trace(struct sk_buff *skb)
2924 {
2925 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
2926         skb->nf_trace = 0;
2927 #endif
2928 }
2929 
2930 /* Note: This doesn't put any conntrack and bridge info in dst. */
2931 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2932 {
2933 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2934         dst->nfct = src->nfct;
2935         nf_conntrack_get(src->nfct);
2936         dst->nfctinfo = src->nfctinfo;
2937 #endif
2938 #ifdef CONFIG_BRIDGE_NETFILTER
2939         dst->nf_bridge  = src->nf_bridge;
2940         nf_bridge_get(src->nf_bridge);
2941 #endif
2942 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
2943         dst->nf_trace = src->nf_trace;
2944 #endif
2945 }
2946 
2947 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2948 {
2949 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2950         nf_conntrack_put(dst->nfct);
2951 #endif
2952 #ifdef CONFIG_BRIDGE_NETFILTER
2953         nf_bridge_put(dst->nf_bridge);
2954 #endif
2955         __nf_copy(dst, src);
2956 }
2957 
2958 #ifdef CONFIG_NETWORK_SECMARK
2959 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2960 {
2961         to->secmark = from->secmark;
2962 }
2963 
2964 static inline void skb_init_secmark(struct sk_buff *skb)
2965 {
2966         skb->secmark = 0;
2967 }
2968 #else
2969 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2970 { }
2971 
2972 static inline void skb_init_secmark(struct sk_buff *skb)
2973 { }
2974 #endif
2975 
2976 static inline bool skb_irq_freeable(const struct sk_buff *skb)
2977 {
2978         return !skb->destructor &&
2979 #if IS_ENABLED(CONFIG_XFRM)
2980                 !skb->sp &&
2981 #endif
2982 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
2983                 !skb->nfct &&
2984 #endif
2985                 !skb->_skb_refdst &&
2986                 !skb_has_frag_list(skb);
2987 }
2988 
2989 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
2990 {
2991         skb->queue_mapping = queue_mapping;
2992 }
2993 
2994 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2995 {
2996         return skb->queue_mapping;
2997 }
2998 
2999 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3000 {
3001         to->queue_mapping = from->queue_mapping;
3002 }
3003 
3004 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3005 {
3006         skb->queue_mapping = rx_queue + 1;
3007 }
3008 
3009 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3010 {
3011         return skb->queue_mapping - 1;
3012 }
3013 
3014 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3015 {
3016         return skb->queue_mapping != 0;
3017 }
3018 
3019 u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
3020                   unsigned int num_tx_queues);
3021 
3022 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3023 {
3024 #ifdef CONFIG_XFRM
3025         return skb->sp;
3026 #else
3027         return NULL;
3028 #endif
3029 }
3030 
3031 /* Keeps track of mac header offset relative to skb->head.
3032  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3033  * For non-tunnel skb it points to skb_mac_header() and for
3034  * tunnel skb it points to outer mac header.
3035  * Keeps track of level of encapsulation of network headers.
3036  */
3037 struct skb_gso_cb {
3038         int     mac_offset;
3039         int     encap_level;
3040         __u16   csum_start;
3041 };
3042 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
3043 
3044 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3045 {
3046         return (skb_mac_header(inner_skb) - inner_skb->head) -
3047                 SKB_GSO_CB(inner_skb)->mac_offset;
3048 }
3049 
3050 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3051 {
3052         int new_headroom, headroom;
3053         int ret;
3054 
3055         headroom = skb_headroom(skb);
3056         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3057         if (ret)
3058                 return ret;
3059 
3060         new_headroom = skb_headroom(skb);
3061         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3062         return 0;
3063 }
3064 
3065 /* Compute the checksum for a gso segment. First compute the checksum value
3066  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3067  * then add in skb->csum (checksum from csum_start to end of packet).
3068  * skb->csum and csum_start are then updated to reflect the checksum of the
3069  * resultant packet starting from the transport header-- the resultant checksum
3070  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3071  * header.
3072  */
3073 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3074 {
3075         int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
3076             skb_transport_offset(skb);
3077         __u16 csum;
3078 
3079         csum = csum_fold(csum_partial(skb_transport_header(skb),
3080                                       plen, skb->csum));
3081         skb->csum = res;
3082         SKB_GSO_CB(skb)->csum_start -= plen;
3083 
3084         return csum;
3085 }
3086 
3087 static inline bool skb_is_gso(const struct sk_buff *skb)
3088 {
3089         return skb_shinfo(skb)->gso_size;
3090 }
3091 
3092 /* Note: Should be called only if skb_is_gso(skb) is true */
3093 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3094 {
3095         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3096 }
3097 
3098 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3099 
3100 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3101 {
3102         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3103          * wanted then gso_type will be set. */
3104         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3105 
3106         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3107             unlikely(shinfo->gso_type == 0)) {
3108                 __skb_warn_lro_forwarding(skb);
3109                 return true;
3110         }
3111         return false;
3112 }
3113 
3114 static inline void skb_forward_csum(struct sk_buff *skb)
3115 {
3116         /* Unfortunately we don't support this one.  Any brave souls? */
3117         if (skb->ip_summed == CHECKSUM_COMPLETE)
3118                 skb->ip_summed = CHECKSUM_NONE;
3119 }
3120 
3121 /**
3122  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3123  * @skb: skb to check
3124  *
3125  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3126  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3127  * use this helper, to document places where we make this assertion.
3128  */
3129 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3130 {
3131 #ifdef DEBUG
3132         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3133 #endif
3134 }
3135 
3136 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3137 
3138 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3139 
3140 u32 __skb_get_poff(const struct sk_buff *skb);
3141 
3142 /**
3143  * skb_head_is_locked - Determine if the skb->head is locked down
3144  * @skb: skb to check
3145  *
3146  * The head on skbs build around a head frag can be removed if they are
3147  * not cloned.  This function returns true if the skb head is locked down
3148  * due to either being allocated via kmalloc, or by being a clone with
3149  * multiple references to the head.
3150  */
3151 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3152 {
3153         return !skb->head_frag || skb_cloned(skb);
3154 }
3155 
3156 /**
3157  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3158  *
3159  * @skb: GSO skb
3160  *
3161  * skb_gso_network_seglen is used to determine the real size of the
3162  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3163  *
3164  * The MAC/L2 header is not accounted for.
3165  */
3166 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3167 {
3168         unsigned int hdr_len = skb_transport_header(skb) -
3169                                skb_network_header(skb);
3170         return hdr_len + skb_gso_transport_seglen(skb);
3171 }
3172 #endif  /* __KERNEL__ */
3173 #endif  /* _LINUX_SKBUFF_H */
3174 

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