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Linux/include/linux/skbuff.h

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

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