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

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  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 #include <linux/rbtree.h>
 24 #include <linux/socket.h>
 25 
 26 #include <linux/atomic.h>
 27 #include <asm/types.h>
 28 #include <linux/spinlock.h>
 29 #include <linux/net.h>
 30 #include <linux/textsearch.h>
 31 #include <net/checksum.h>
 32 #include <linux/rcupdate.h>
 33 #include <linux/hrtimer.h>
 34 #include <linux/dma-mapping.h>
 35 #include <linux/netdev_features.h>
 36 #include <linux/sched.h>
 37 #include <linux/sched/clock.h>
 38 #include <net/flow_dissector.h>
 39 #include <linux/splice.h>
 40 #include <linux/in6.h>
 41 #include <linux/if_packet.h>
 42 #include <net/flow.h>
 43 
 44 /* The interface for checksum offload between the stack and networking drivers
 45  * is as follows...
 46  *
 47  * A. IP checksum related features
 48  *
 49  * Drivers advertise checksum offload capabilities in the features of a device.
 50  * From the stack's point of view these are capabilities offered by the driver,
 51  * a driver typically only advertises features that it is capable of offloading
 52  * to its device.
 53  *
 54  * The checksum related features are:
 55  *
 56  *      NETIF_F_HW_CSUM - The driver (or its device) is able to compute one
 57  *                        IP (one's complement) checksum for any combination
 58  *                        of protocols or protocol layering. The checksum is
 59  *                        computed and set in a packet per the CHECKSUM_PARTIAL
 60  *                        interface (see below).
 61  *
 62  *      NETIF_F_IP_CSUM - Driver (device) is only able to checksum plain
 63  *                        TCP or UDP packets over IPv4. These are specifically
 64  *                        unencapsulated packets of the form IPv4|TCP or
 65  *                        IPv4|UDP where the Protocol field in the IPv4 header
 66  *                        is TCP or UDP. The IPv4 header may contain IP options
 67  *                        This feature cannot be set in features for a device
 68  *                        with NETIF_F_HW_CSUM also set. This feature is being
 69  *                        DEPRECATED (see below).
 70  *
 71  *      NETIF_F_IPV6_CSUM - Driver (device) is only able to checksum plain
 72  *                        TCP or UDP packets over IPv6. These are specifically
 73  *                        unencapsulated packets of the form IPv6|TCP or
 74  *                        IPv4|UDP where the Next Header field in the IPv6
 75  *                        header is either TCP or UDP. IPv6 extension headers
 76  *                        are not supported with this feature. This feature
 77  *                        cannot be set in features for a device with
 78  *                        NETIF_F_HW_CSUM also set. This feature is being
 79  *                        DEPRECATED (see below).
 80  *
 81  *      NETIF_F_RXCSUM - Driver (device) performs receive checksum offload.
 82  *                       This flag is used only used to disable the RX checksum
 83  *                       feature for a device. The stack will accept receive
 84  *                       checksum indication in packets received on a device
 85  *                       regardless of whether NETIF_F_RXCSUM is set.
 86  *
 87  * B. Checksumming of received packets by device. Indication of checksum
 88  *    verification is in set skb->ip_summed. Possible values are:
 89  *
 90  * CHECKSUM_NONE:
 91  *
 92  *   Device did not checksum this packet e.g. due to lack of capabilities.
 93  *   The packet contains full (though not verified) checksum in packet but
 94  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 95  *
 96  * CHECKSUM_UNNECESSARY:
 97  *
 98  *   The hardware you're dealing with doesn't calculate the full checksum
 99  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
100  *   for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
101  *   if their checksums are okay. skb->csum is still undefined in this case
102  *   though. A driver or device must never modify the checksum field in the
103  *   packet even if checksum is verified.
104  *
105  *   CHECKSUM_UNNECESSARY is applicable to following protocols:
106  *     TCP: IPv6 and IPv4.
107  *     UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
108  *       zero UDP checksum for either IPv4 or IPv6, the networking stack
109  *       may perform further validation in this case.
110  *     GRE: only if the checksum is present in the header.
111  *     SCTP: indicates the CRC in SCTP header has been validated.
112  *
113  *   skb->csum_level indicates the number of consecutive checksums found in
114  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
115  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
116  *   and a device is able to verify the checksums for UDP (possibly zero),
117  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
118  *   two. If the device were only able to verify the UDP checksum and not
119  *   GRE, either because it doesn't support GRE checksum of because GRE
120  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
121  *   not considered in this case).
122  *
123  * CHECKSUM_COMPLETE:
124  *
125  *   This is the most generic way. The device supplied checksum of the _whole_
126  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
127  *   hardware doesn't need to parse L3/L4 headers to implement this.
128  *
129  *   Note: Even if device supports only some protocols, but is able to produce
130  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
131  *
132  * CHECKSUM_PARTIAL:
133  *
134  *   A checksum is set up to be offloaded to a device as described in the
135  *   output description for CHECKSUM_PARTIAL. This may occur on a packet
136  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
137  *   on the same host, or it may be set in the input path in GRO or remote
138  *   checksum offload. For the purposes of checksum verification, the checksum
139  *   referred to by skb->csum_start + skb->csum_offset and any preceding
140  *   checksums in the packet are considered verified. Any checksums in the
141  *   packet that are after the checksum being offloaded are not considered to
142  *   be verified.
143  *
144  * C. Checksumming on transmit for non-GSO. The stack requests checksum offload
145  *    in the skb->ip_summed for a packet. Values are:
146  *
147  * CHECKSUM_PARTIAL:
148  *
149  *   The driver is required to checksum the packet as seen by hard_start_xmit()
150  *   from skb->csum_start up to the end, and to record/write the checksum at
151  *   offset skb->csum_start + skb->csum_offset. A driver may verify that the
152  *   csum_start and csum_offset values are valid values given the length and
153  *   offset of the packet, however they should not attempt to validate that the
154  *   checksum refers to a legitimate transport layer checksum-- it is the
155  *   purview of the stack to validate that csum_start and csum_offset are set
156  *   correctly.
157  *
158  *   When the stack requests checksum offload for a packet, the driver MUST
159  *   ensure that the checksum is set correctly. A driver can either offload the
160  *   checksum calculation to the device, or call skb_checksum_help (in the case
161  *   that the device does not support offload for a particular checksum).
162  *
163  *   NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
164  *   NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
165  *   checksum offload capability. If a  device has limited checksum capabilities
166  *   (for instance can only perform NETIF_F_IP_CSUM or NETIF_F_IPV6_CSUM as
167  *   described above) a helper function can be called to resolve
168  *   CHECKSUM_PARTIAL. The helper functions are skb_csum_off_chk*. The helper
169  *   function takes a spec argument that describes the protocol layer that is
170  *   supported for checksum offload and can be called for each packet. If a
171  *   packet does not match the specification for offload, skb_checksum_help
172  *   is called to resolve the checksum.
173  *
174  * CHECKSUM_NONE:
175  *
176  *   The skb was already checksummed by the protocol, or a checksum is not
177  *   required.
178  *
179  * CHECKSUM_UNNECESSARY:
180  *
181  *   This has the same meaning on as CHECKSUM_NONE for checksum offload on
182  *   output.
183  *
184  * CHECKSUM_COMPLETE:
185  *   Not used in checksum output. If a driver observes a packet with this value
186  *   set in skbuff, if should treat as CHECKSUM_NONE being set.
187  *
188  * D. Non-IP checksum (CRC) offloads
189  *
190  *   NETIF_F_SCTP_CRC - This feature indicates that a device is capable of
191  *     offloading the SCTP CRC in a packet. To perform this offload the stack
192  *     will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
193  *     accordingly. Note the there is no indication in the skbuff that the
194  *     CHECKSUM_PARTIAL refers to an SCTP checksum, a driver that supports
195  *     both IP checksum offload and SCTP CRC offload must verify which offload
196  *     is configured for a packet presumably by inspecting packet headers.
197  *
198  *   NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
199  *     offloading the FCOE CRC in a packet. To perform this offload the stack
200  *     will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
201  *     accordingly. Note the there is no indication in the skbuff that the
202  *     CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports
203  *     both IP checksum offload and FCOE CRC offload must verify which offload
204  *     is configured for a packet presumably by inspecting packet headers.
205  *
206  * E. Checksumming on output with GSO.
207  *
208  * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload
209  * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the
210  * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as
211  * part of the GSO operation is implied. If a checksum is being offloaded
212  * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset
213  * are set to refer to the outermost checksum being offload (two offloaded
214  * checksums are possible with UDP encapsulation).
215  */
216 
217 /* Don't change this without changing skb_csum_unnecessary! */
218 #define CHECKSUM_NONE           0
219 #define CHECKSUM_UNNECESSARY    1
220 #define CHECKSUM_COMPLETE       2
221 #define CHECKSUM_PARTIAL        3
222 
223 /* Maximum value in skb->csum_level */
224 #define SKB_MAX_CSUM_LEVEL      3
225 
226 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
227 #define SKB_WITH_OVERHEAD(X)    \
228         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
229 #define SKB_MAX_ORDER(X, ORDER) \
230         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
231 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
232 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
233 
234 /* return minimum truesize of one skb containing X bytes of data */
235 #define SKB_TRUESIZE(X) ((X) +                                          \
236                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
237                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
238 
239 struct net_device;
240 struct scatterlist;
241 struct pipe_inode_info;
242 struct iov_iter;
243 struct napi_struct;
244 
245 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
246 struct nf_conntrack {
247         atomic_t use;
248 };
249 #endif
250 
251 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
252 struct nf_bridge_info {
253         atomic_t                use;
254         enum {
255                 BRNF_PROTO_UNCHANGED,
256                 BRNF_PROTO_8021Q,
257                 BRNF_PROTO_PPPOE
258         } orig_proto:8;
259         u8                      pkt_otherhost:1;
260         u8                      in_prerouting:1;
261         u8                      bridged_dnat:1;
262         __u16                   frag_max_size;
263         struct net_device       *physindev;
264 
265         /* always valid & non-NULL from FORWARD on, for physdev match */
266         struct net_device       *physoutdev;
267         union {
268                 /* prerouting: detect dnat in orig/reply direction */
269                 __be32          ipv4_daddr;
270                 struct in6_addr ipv6_daddr;
271 
272                 /* after prerouting + nat detected: store original source
273                  * mac since neigh resolution overwrites it, only used while
274                  * skb is out in neigh layer.
275                  */
276                 char neigh_header[8];
277         };
278 };
279 #endif
280 
281 struct sk_buff_head {
282         /* These two members must be first. */
283         struct sk_buff  *next;
284         struct sk_buff  *prev;
285 
286         __u32           qlen;
287         spinlock_t      lock;
288 };
289 
290 struct sk_buff;
291 
292 /* To allow 64K frame to be packed as single skb without frag_list we
293  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
294  * buffers which do not start on a page boundary.
295  *
296  * Since GRO uses frags we allocate at least 16 regardless of page
297  * size.
298  */
299 #if (65536/PAGE_SIZE + 1) < 16
300 #define MAX_SKB_FRAGS 16UL
301 #else
302 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
303 #endif
304 extern int sysctl_max_skb_frags;
305 
306 /* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
307  * segment using its current segmentation instead.
308  */
309 #define GSO_BY_FRAGS    0xFFFF
310 
311 typedef struct skb_frag_struct skb_frag_t;
312 
313 struct skb_frag_struct {
314         struct {
315                 struct page *p;
316         } page;
317 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
318         __u32 page_offset;
319         __u32 size;
320 #else
321         __u16 page_offset;
322         __u16 size;
323 #endif
324 };
325 
326 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
327 {
328         return frag->size;
329 }
330 
331 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
332 {
333         frag->size = size;
334 }
335 
336 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
337 {
338         frag->size += delta;
339 }
340 
341 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
342 {
343         frag->size -= delta;
344 }
345 
346 #define HAVE_HW_TIME_STAMP
347 
348 /**
349  * struct skb_shared_hwtstamps - hardware time stamps
350  * @hwtstamp:   hardware time stamp transformed into duration
351  *              since arbitrary point in time
352  *
353  * Software time stamps generated by ktime_get_real() are stored in
354  * skb->tstamp.
355  *
356  * hwtstamps can only be compared against other hwtstamps from
357  * the same device.
358  *
359  * This structure is attached to packets as part of the
360  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
361  */
362 struct skb_shared_hwtstamps {
363         ktime_t hwtstamp;
364 };
365 
366 /* Definitions for tx_flags in struct skb_shared_info */
367 enum {
368         /* generate hardware time stamp */
369         SKBTX_HW_TSTAMP = 1 << 0,
370 
371         /* generate software time stamp when queueing packet to NIC */
372         SKBTX_SW_TSTAMP = 1 << 1,
373 
374         /* device driver is going to provide hardware time stamp */
375         SKBTX_IN_PROGRESS = 1 << 2,
376 
377         /* device driver supports TX zero-copy buffers */
378         SKBTX_DEV_ZEROCOPY = 1 << 3,
379 
380         /* generate wifi status information (where possible) */
381         SKBTX_WIFI_STATUS = 1 << 4,
382 
383         /* This indicates at least one fragment might be overwritten
384          * (as in vmsplice(), sendfile() ...)
385          * If we need to compute a TX checksum, we'll need to copy
386          * all frags to avoid possible bad checksum
387          */
388         SKBTX_SHARED_FRAG = 1 << 5,
389 
390         /* generate software time stamp when entering packet scheduling */
391         SKBTX_SCHED_TSTAMP = 1 << 6,
392 };
393 
394 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
395                                  SKBTX_SCHED_TSTAMP)
396 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
397 
398 /*
399  * The callback notifies userspace to release buffers when skb DMA is done in
400  * lower device, the skb last reference should be 0 when calling this.
401  * The zerocopy_success argument is true if zero copy transmit occurred,
402  * false on data copy or out of memory error caused by data copy attempt.
403  * The ctx field is used to track device context.
404  * The desc field is used to track userspace buffer index.
405  */
406 struct ubuf_info {
407         void (*callback)(struct ubuf_info *, bool zerocopy_success);
408         void *ctx;
409         unsigned long desc;
410 };
411 
412 /* This data is invariant across clones and lives at
413  * the end of the header data, ie. at skb->end.
414  */
415 struct skb_shared_info {
416         unsigned char   nr_frags;
417         __u8            tx_flags;
418         unsigned short  gso_size;
419         /* Warning: this field is not always filled in (UFO)! */
420         unsigned short  gso_segs;
421         unsigned short  gso_type;
422         struct sk_buff  *frag_list;
423         struct skb_shared_hwtstamps hwtstamps;
424         u32             tskey;
425         __be32          ip6_frag_id;
426 
427         /*
428          * Warning : all fields before dataref are cleared in __alloc_skb()
429          */
430         atomic_t        dataref;
431 
432         /* Intermediate layers must ensure that destructor_arg
433          * remains valid until skb destructor */
434         void *          destructor_arg;
435 
436         /* must be last field, see pskb_expand_head() */
437         skb_frag_t      frags[MAX_SKB_FRAGS];
438 };
439 
440 /* We divide dataref into two halves.  The higher 16 bits hold references
441  * to the payload part of skb->data.  The lower 16 bits hold references to
442  * the entire skb->data.  A clone of a headerless skb holds the length of
443  * the header in skb->hdr_len.
444  *
445  * All users must obey the rule that the skb->data reference count must be
446  * greater than or equal to the payload reference count.
447  *
448  * Holding a reference to the payload part means that the user does not
449  * care about modifications to the header part of skb->data.
450  */
451 #define SKB_DATAREF_SHIFT 16
452 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
453 
454 
455 enum {
456         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
457         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
458         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
459 };
460 
461 enum {
462         SKB_GSO_TCPV4 = 1 << 0,
463         SKB_GSO_UDP = 1 << 1,
464 
465         /* This indicates the skb is from an untrusted source. */
466         SKB_GSO_DODGY = 1 << 2,
467 
468         /* This indicates the tcp segment has CWR set. */
469         SKB_GSO_TCP_ECN = 1 << 3,
470 
471         SKB_GSO_TCP_FIXEDID = 1 << 4,
472 
473         SKB_GSO_TCPV6 = 1 << 5,
474 
475         SKB_GSO_FCOE = 1 << 6,
476 
477         SKB_GSO_GRE = 1 << 7,
478 
479         SKB_GSO_GRE_CSUM = 1 << 8,
480 
481         SKB_GSO_IPXIP4 = 1 << 9,
482 
483         SKB_GSO_IPXIP6 = 1 << 10,
484 
485         SKB_GSO_UDP_TUNNEL = 1 << 11,
486 
487         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 12,
488 
489         SKB_GSO_PARTIAL = 1 << 13,
490 
491         SKB_GSO_TUNNEL_REMCSUM = 1 << 14,
492 
493         SKB_GSO_SCTP = 1 << 15,
494 };
495 
496 #if BITS_PER_LONG > 32
497 #define NET_SKBUFF_DATA_USES_OFFSET 1
498 #endif
499 
500 #ifdef NET_SKBUFF_DATA_USES_OFFSET
501 typedef unsigned int sk_buff_data_t;
502 #else
503 typedef unsigned char *sk_buff_data_t;
504 #endif
505 
506 /**
507  * struct skb_mstamp - multi resolution time stamps
508  * @stamp_us: timestamp in us resolution
509  * @stamp_jiffies: timestamp in jiffies
510  */
511 struct skb_mstamp {
512         union {
513                 u64             v64;
514                 struct {
515                         u32     stamp_us;
516                         u32     stamp_jiffies;
517                 };
518         };
519 };
520 
521 /**
522  * skb_mstamp_get - get current timestamp
523  * @cl: place to store timestamps
524  */
525 static inline void skb_mstamp_get(struct skb_mstamp *cl)
526 {
527         u64 val = local_clock();
528 
529         do_div(val, NSEC_PER_USEC);
530         cl->stamp_us = (u32)val;
531         cl->stamp_jiffies = (u32)jiffies;
532 }
533 
534 /**
535  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
536  * @t1: pointer to newest sample
537  * @t0: pointer to oldest sample
538  */
539 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
540                                       const struct skb_mstamp *t0)
541 {
542         s32 delta_us = t1->stamp_us - t0->stamp_us;
543         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
544 
545         /* If delta_us is negative, this might be because interval is too big,
546          * or local_clock() drift is too big : fallback using jiffies.
547          */
548         if (delta_us <= 0 ||
549             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
550 
551                 delta_us = jiffies_to_usecs(delta_jiffies);
552 
553         return delta_us;
554 }
555 
556 static inline bool skb_mstamp_after(const struct skb_mstamp *t1,
557                                     const struct skb_mstamp *t0)
558 {
559         s32 diff = t1->stamp_jiffies - t0->stamp_jiffies;
560 
561         if (!diff)
562                 diff = t1->stamp_us - t0->stamp_us;
563         return diff > 0;
564 }
565 
566 /** 
567  *      struct sk_buff - socket buffer
568  *      @next: Next buffer in list
569  *      @prev: Previous buffer in list
570  *      @tstamp: Time we arrived/left
571  *      @rbnode: RB tree node, alternative to next/prev for netem/tcp
572  *      @sk: Socket we are owned by
573  *      @dev: Device we arrived on/are leaving by
574  *      @cb: Control buffer. Free for use by every layer. Put private vars here
575  *      @_skb_refdst: destination entry (with norefcount bit)
576  *      @sp: the security path, used for xfrm
577  *      @len: Length of actual data
578  *      @data_len: Data length
579  *      @mac_len: Length of link layer header
580  *      @hdr_len: writable header length of cloned skb
581  *      @csum: Checksum (must include start/offset pair)
582  *      @csum_start: Offset from skb->head where checksumming should start
583  *      @csum_offset: Offset from csum_start where checksum should be stored
584  *      @priority: Packet queueing priority
585  *      @ignore_df: allow local fragmentation
586  *      @cloned: Head may be cloned (check refcnt to be sure)
587  *      @ip_summed: Driver fed us an IP checksum
588  *      @nohdr: Payload reference only, must not modify header
589  *      @pkt_type: Packet class
590  *      @fclone: skbuff clone status
591  *      @ipvs_property: skbuff is owned by ipvs
592  *      @tc_skip_classify: do not classify packet. set by IFB device
593  *      @tc_at_ingress: used within tc_classify to distinguish in/egress
594  *      @tc_redirected: packet was redirected by a tc action
595  *      @tc_from_ingress: if tc_redirected, tc_at_ingress at time of redirect
596  *      @peeked: this packet has been seen already, so stats have been
597  *              done for it, don't do them again
598  *      @nf_trace: netfilter packet trace flag
599  *      @protocol: Packet protocol from driver
600  *      @destructor: Destruct function
601  *      @_nfct: Associated connection, if any (with nfctinfo bits)
602  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
603  *      @skb_iif: ifindex of device we arrived on
604  *      @tc_index: Traffic control index
605  *      @hash: the packet hash
606  *      @queue_mapping: Queue mapping for multiqueue devices
607  *      @xmit_more: More SKBs are pending for this queue
608  *      @ndisc_nodetype: router type (from link layer)
609  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
610  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
611  *              ports.
612  *      @sw_hash: indicates hash was computed in software stack
613  *      @wifi_acked_valid: wifi_acked was set
614  *      @wifi_acked: whether frame was acked on wifi or not
615  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
616  *      @dst_pending_confirm: need to confirm neighbour
617   *     @napi_id: id of the NAPI struct this skb came from
618  *      @secmark: security marking
619  *      @mark: Generic packet mark
620  *      @vlan_proto: vlan encapsulation protocol
621  *      @vlan_tci: vlan tag control information
622  *      @inner_protocol: Protocol (encapsulation)
623  *      @inner_transport_header: Inner transport layer header (encapsulation)
624  *      @inner_network_header: Network layer header (encapsulation)
625  *      @inner_mac_header: Link layer header (encapsulation)
626  *      @transport_header: Transport layer header
627  *      @network_header: Network layer header
628  *      @mac_header: Link layer header
629  *      @tail: Tail pointer
630  *      @end: End pointer
631  *      @head: Head of buffer
632  *      @data: Data head pointer
633  *      @truesize: Buffer size
634  *      @users: User count - see {datagram,tcp}.c
635  */
636 
637 struct sk_buff {
638         union {
639                 struct {
640                         /* These two members must be first. */
641                         struct sk_buff          *next;
642                         struct sk_buff          *prev;
643 
644                         union {
645                                 ktime_t         tstamp;
646                                 struct skb_mstamp skb_mstamp;
647                         };
648                 };
649                 struct rb_node  rbnode; /* used in netem & tcp stack */
650         };
651         struct sock             *sk;
652 
653         union {
654                 struct net_device       *dev;
655                 /* Some protocols might use this space to store information,
656                  * while device pointer would be NULL.
657                  * UDP receive path is one user.
658                  */
659                 unsigned long           dev_scratch;
660         };
661         /*
662          * This is the control buffer. It is free to use for every
663          * layer. Please put your private variables there. If you
664          * want to keep them across layers you have to do a skb_clone()
665          * first. This is owned by whoever has the skb queued ATM.
666          */
667         char                    cb[48] __aligned(8);
668 
669         unsigned long           _skb_refdst;
670         void                    (*destructor)(struct sk_buff *skb);
671 #ifdef CONFIG_XFRM
672         struct  sec_path        *sp;
673 #endif
674 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
675         unsigned long            _nfct;
676 #endif
677 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
678         struct nf_bridge_info   *nf_bridge;
679 #endif
680         unsigned int            len,
681                                 data_len;
682         __u16                   mac_len,
683                                 hdr_len;
684 
685         /* Following fields are _not_ copied in __copy_skb_header()
686          * Note that queue_mapping is here mostly to fill a hole.
687          */
688         kmemcheck_bitfield_begin(flags1);
689         __u16                   queue_mapping;
690 
691 /* if you move cloned around you also must adapt those constants */
692 #ifdef __BIG_ENDIAN_BITFIELD
693 #define CLONED_MASK     (1 << 7)
694 #else
695 #define CLONED_MASK     1
696 #endif
697 #define CLONED_OFFSET()         offsetof(struct sk_buff, __cloned_offset)
698 
699         __u8                    __cloned_offset[0];
700         __u8                    cloned:1,
701                                 nohdr:1,
702                                 fclone:2,
703                                 peeked:1,
704                                 head_frag:1,
705                                 xmit_more:1,
706                                 __unused:1; /* one bit hole */
707         kmemcheck_bitfield_end(flags1);
708 
709         /* fields enclosed in headers_start/headers_end are copied
710          * using a single memcpy() in __copy_skb_header()
711          */
712         /* private: */
713         __u32                   headers_start[0];
714         /* public: */
715 
716 /* if you move pkt_type around you also must adapt those constants */
717 #ifdef __BIG_ENDIAN_BITFIELD
718 #define PKT_TYPE_MAX    (7 << 5)
719 #else
720 #define PKT_TYPE_MAX    7
721 #endif
722 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
723 
724         __u8                    __pkt_type_offset[0];
725         __u8                    pkt_type:3;
726         __u8                    pfmemalloc:1;
727         __u8                    ignore_df:1;
728 
729         __u8                    nf_trace:1;
730         __u8                    ip_summed:2;
731         __u8                    ooo_okay:1;
732         __u8                    l4_hash:1;
733         __u8                    sw_hash:1;
734         __u8                    wifi_acked_valid:1;
735         __u8                    wifi_acked:1;
736 
737         __u8                    no_fcs:1;
738         /* Indicates the inner headers are valid in the skbuff. */
739         __u8                    encapsulation:1;
740         __u8                    encap_hdr_csum:1;
741         __u8                    csum_valid:1;
742         __u8                    csum_complete_sw:1;
743         __u8                    csum_level:2;
744         __u8                    csum_bad:1;
745 
746         __u8                    dst_pending_confirm:1;
747 #ifdef CONFIG_IPV6_NDISC_NODETYPE
748         __u8                    ndisc_nodetype:2;
749 #endif
750         __u8                    ipvs_property:1;
751         __u8                    inner_protocol_type:1;
752         __u8                    remcsum_offload:1;
753 #ifdef CONFIG_NET_SWITCHDEV
754         __u8                    offload_fwd_mark:1;
755 #endif
756 #ifdef CONFIG_NET_CLS_ACT
757         __u8                    tc_skip_classify:1;
758         __u8                    tc_at_ingress:1;
759         __u8                    tc_redirected:1;
760         __u8                    tc_from_ingress:1;
761 #endif
762 
763 #ifdef CONFIG_NET_SCHED
764         __u16                   tc_index;       /* traffic control index */
765 #endif
766 
767         union {
768                 __wsum          csum;
769                 struct {
770                         __u16   csum_start;
771                         __u16   csum_offset;
772                 };
773         };
774         __u32                   priority;
775         int                     skb_iif;
776         __u32                   hash;
777         __be16                  vlan_proto;
778         __u16                   vlan_tci;
779 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
780         union {
781                 unsigned int    napi_id;
782                 unsigned int    sender_cpu;
783         };
784 #endif
785 #ifdef CONFIG_NETWORK_SECMARK
786         __u32           secmark;
787 #endif
788 
789         union {
790                 __u32           mark;
791                 __u32           reserved_tailroom;
792         };
793 
794         union {
795                 __be16          inner_protocol;
796                 __u8            inner_ipproto;
797         };
798 
799         __u16                   inner_transport_header;
800         __u16                   inner_network_header;
801         __u16                   inner_mac_header;
802 
803         __be16                  protocol;
804         __u16                   transport_header;
805         __u16                   network_header;
806         __u16                   mac_header;
807 
808         /* private: */
809         __u32                   headers_end[0];
810         /* public: */
811 
812         /* These elements must be at the end, see alloc_skb() for details.  */
813         sk_buff_data_t          tail;
814         sk_buff_data_t          end;
815         unsigned char           *head,
816                                 *data;
817         unsigned int            truesize;
818         atomic_t                users;
819 };
820 
821 #ifdef __KERNEL__
822 /*
823  *      Handling routines are only of interest to the kernel
824  */
825 #include <linux/slab.h>
826 
827 
828 #define SKB_ALLOC_FCLONE        0x01
829 #define SKB_ALLOC_RX            0x02
830 #define SKB_ALLOC_NAPI          0x04
831 
832 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
833 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
834 {
835         return unlikely(skb->pfmemalloc);
836 }
837 
838 /*
839  * skb might have a dst pointer attached, refcounted or not.
840  * _skb_refdst low order bit is set if refcount was _not_ taken
841  */
842 #define SKB_DST_NOREF   1UL
843 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
844 
845 #define SKB_NFCT_PTRMASK        ~(7UL)
846 /**
847  * skb_dst - returns skb dst_entry
848  * @skb: buffer
849  *
850  * Returns skb dst_entry, regardless of reference taken or not.
851  */
852 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
853 {
854         /* If refdst was not refcounted, check we still are in a 
855          * rcu_read_lock section
856          */
857         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
858                 !rcu_read_lock_held() &&
859                 !rcu_read_lock_bh_held());
860         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
861 }
862 
863 /**
864  * skb_dst_set - sets skb dst
865  * @skb: buffer
866  * @dst: dst entry
867  *
868  * Sets skb dst, assuming a reference was taken on dst and should
869  * be released by skb_dst_drop()
870  */
871 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
872 {
873         skb->_skb_refdst = (unsigned long)dst;
874 }
875 
876 /**
877  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
878  * @skb: buffer
879  * @dst: dst entry
880  *
881  * Sets skb dst, assuming a reference was not taken on dst.
882  * If dst entry is cached, we do not take reference and dst_release
883  * will be avoided by refdst_drop. If dst entry is not cached, we take
884  * reference, so that last dst_release can destroy the dst immediately.
885  */
886 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
887 {
888         WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
889         skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
890 }
891 
892 /**
893  * skb_dst_is_noref - Test if skb dst isn't refcounted
894  * @skb: buffer
895  */
896 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
897 {
898         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
899 }
900 
901 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
902 {
903         return (struct rtable *)skb_dst(skb);
904 }
905 
906 /* For mangling skb->pkt_type from user space side from applications
907  * such as nft, tc, etc, we only allow a conservative subset of
908  * possible pkt_types to be set.
909 */
910 static inline bool skb_pkt_type_ok(u32 ptype)
911 {
912         return ptype <= PACKET_OTHERHOST;
913 }
914 
915 void kfree_skb(struct sk_buff *skb);
916 void kfree_skb_list(struct sk_buff *segs);
917 void skb_tx_error(struct sk_buff *skb);
918 void consume_skb(struct sk_buff *skb);
919 void  __kfree_skb(struct sk_buff *skb);
920 extern struct kmem_cache *skbuff_head_cache;
921 
922 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
923 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
924                       bool *fragstolen, int *delta_truesize);
925 
926 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
927                             int node);
928 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
929 struct sk_buff *build_skb(void *data, unsigned int frag_size);
930 static inline struct sk_buff *alloc_skb(unsigned int size,
931                                         gfp_t priority)
932 {
933         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
934 }
935 
936 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
937                                      unsigned long data_len,
938                                      int max_page_order,
939                                      int *errcode,
940                                      gfp_t gfp_mask);
941 
942 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
943 struct sk_buff_fclones {
944         struct sk_buff  skb1;
945 
946         struct sk_buff  skb2;
947 
948         atomic_t        fclone_ref;
949 };
950 
951 /**
952  *      skb_fclone_busy - check if fclone is busy
953  *      @sk: socket
954  *      @skb: buffer
955  *
956  * Returns true if skb is a fast clone, and its clone is not freed.
957  * Some drivers call skb_orphan() in their ndo_start_xmit(),
958  * so we also check that this didnt happen.
959  */
960 static inline bool skb_fclone_busy(const struct sock *sk,
961                                    const struct sk_buff *skb)
962 {
963         const struct sk_buff_fclones *fclones;
964 
965         fclones = container_of(skb, struct sk_buff_fclones, skb1);
966 
967         return skb->fclone == SKB_FCLONE_ORIG &&
968                atomic_read(&fclones->fclone_ref) > 1 &&
969                fclones->skb2.sk == sk;
970 }
971 
972 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
973                                                gfp_t priority)
974 {
975         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
976 }
977 
978 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
979 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
980 {
981         return __alloc_skb_head(priority, -1);
982 }
983 
984 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
985 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
986 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
987 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
988 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
989                                    gfp_t gfp_mask, bool fclone);
990 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
991                                           gfp_t gfp_mask)
992 {
993         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
994 }
995 
996 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
997 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
998                                      unsigned int headroom);
999 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
1000                                 int newtailroom, gfp_t priority);
1001 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
1002                         int offset, int len);
1003 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
1004                  int len);
1005 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
1006 int skb_pad(struct sk_buff *skb, int pad);
1007 #define dev_kfree_skb(a)        consume_skb(a)
1008 
1009 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1010                             int getfrag(void *from, char *to, int offset,
1011                                         int len, int odd, struct sk_buff *skb),
1012                             void *from, int length);
1013 
1014 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
1015                          int offset, size_t size);
1016 
1017 struct skb_seq_state {
1018         __u32           lower_offset;
1019         __u32           upper_offset;
1020         __u32           frag_idx;
1021         __u32           stepped_offset;
1022         struct sk_buff  *root_skb;
1023         struct sk_buff  *cur_skb;
1024         __u8            *frag_data;
1025 };
1026 
1027 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1028                           unsigned int to, struct skb_seq_state *st);
1029 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1030                           struct skb_seq_state *st);
1031 void skb_abort_seq_read(struct skb_seq_state *st);
1032 
1033 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1034                            unsigned int to, struct ts_config *config);
1035 
1036 /*
1037  * Packet hash types specify the type of hash in skb_set_hash.
1038  *
1039  * Hash types refer to the protocol layer addresses which are used to
1040  * construct a packet's hash. The hashes are used to differentiate or identify
1041  * flows of the protocol layer for the hash type. Hash types are either
1042  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
1043  *
1044  * Properties of hashes:
1045  *
1046  * 1) Two packets in different flows have different hash values
1047  * 2) Two packets in the same flow should have the same hash value
1048  *
1049  * A hash at a higher layer is considered to be more specific. A driver should
1050  * set the most specific hash possible.
1051  *
1052  * A driver cannot indicate a more specific hash than the layer at which a hash
1053  * was computed. For instance an L3 hash cannot be set as an L4 hash.
1054  *
1055  * A driver may indicate a hash level which is less specific than the
1056  * actual layer the hash was computed on. For instance, a hash computed
1057  * at L4 may be considered an L3 hash. This should only be done if the
1058  * driver can't unambiguously determine that the HW computed the hash at
1059  * the higher layer. Note that the "should" in the second property above
1060  * permits this.
1061  */
1062 enum pkt_hash_types {
1063         PKT_HASH_TYPE_NONE,     /* Undefined type */
1064         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
1065         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
1066         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
1067 };
1068 
1069 static inline void skb_clear_hash(struct sk_buff *skb)
1070 {
1071         skb->hash = 0;
1072         skb->sw_hash = 0;
1073         skb->l4_hash = 0;
1074 }
1075 
1076 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
1077 {
1078         if (!skb->l4_hash)
1079                 skb_clear_hash(skb);
1080 }
1081 
1082 static inline void
1083 __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
1084 {
1085         skb->l4_hash = is_l4;
1086         skb->sw_hash = is_sw;
1087         skb->hash = hash;
1088 }
1089 
1090 static inline void
1091 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
1092 {
1093         /* Used by drivers to set hash from HW */
1094         __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
1095 }
1096 
1097 static inline void
1098 __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
1099 {
1100         __skb_set_hash(skb, hash, true, is_l4);
1101 }
1102 
1103 void __skb_get_hash(struct sk_buff *skb);
1104 u32 __skb_get_hash_symmetric(const struct sk_buff *skb);
1105 u32 skb_get_poff(const struct sk_buff *skb);
1106 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
1107                    const struct flow_keys *keys, int hlen);
1108 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
1109                             void *data, int hlen_proto);
1110 
1111 static inline __be32 skb_flow_get_ports(const struct sk_buff *skb,
1112                                         int thoff, u8 ip_proto)
1113 {
1114         return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
1115 }
1116 
1117 void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
1118                              const struct flow_dissector_key *key,
1119                              unsigned int key_count);
1120 
1121 bool __skb_flow_dissect(const struct sk_buff *skb,
1122                         struct flow_dissector *flow_dissector,
1123                         void *target_container,
1124                         void *data, __be16 proto, int nhoff, int hlen,
1125                         unsigned int flags);
1126 
1127 static inline bool skb_flow_dissect(const struct sk_buff *skb,
1128                                     struct flow_dissector *flow_dissector,
1129                                     void *target_container, unsigned int flags)
1130 {
1131         return __skb_flow_dissect(skb, flow_dissector, target_container,
1132                                   NULL, 0, 0, 0, flags);
1133 }
1134 
1135 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
1136                                               struct flow_keys *flow,
1137                                               unsigned int flags)
1138 {
1139         memset(flow, 0, sizeof(*flow));
1140         return __skb_flow_dissect(skb, &flow_keys_dissector, flow,
1141                                   NULL, 0, 0, 0, flags);
1142 }
1143 
1144 static inline bool skb_flow_dissect_flow_keys_buf(struct flow_keys *flow,
1145                                                   void *data, __be16 proto,
1146                                                   int nhoff, int hlen,
1147                                                   unsigned int flags)
1148 {
1149         memset(flow, 0, sizeof(*flow));
1150         return __skb_flow_dissect(NULL, &flow_keys_buf_dissector, flow,
1151                                   data, proto, nhoff, hlen, flags);
1152 }
1153 
1154 static inline __u32 skb_get_hash(struct sk_buff *skb)
1155 {
1156         if (!skb->l4_hash && !skb->sw_hash)
1157                 __skb_get_hash(skb);
1158 
1159         return skb->hash;
1160 }
1161 
1162 __u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6);
1163 
1164 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
1165 {
1166         if (!skb->l4_hash && !skb->sw_hash) {
1167                 struct flow_keys keys;
1168                 __u32 hash = __get_hash_from_flowi6(fl6, &keys);
1169 
1170                 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1171         }
1172 
1173         return skb->hash;
1174 }
1175 
1176 __u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl);
1177 
1178 static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
1179 {
1180         if (!skb->l4_hash && !skb->sw_hash) {
1181                 struct flow_keys keys;
1182                 __u32 hash = __get_hash_from_flowi4(fl4, &keys);
1183 
1184                 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1185         }
1186 
1187         return skb->hash;
1188 }
1189 
1190 __u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);
1191 
1192 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
1193 {
1194         return skb->hash;
1195 }
1196 
1197 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
1198 {
1199         to->hash = from->hash;
1200         to->sw_hash = from->sw_hash;
1201         to->l4_hash = from->l4_hash;
1202 };
1203 
1204 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1205 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1206 {
1207         return skb->head + skb->end;
1208 }
1209 
1210 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1211 {
1212         return skb->end;
1213 }
1214 #else
1215 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1216 {
1217         return skb->end;
1218 }
1219 
1220 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1221 {
1222         return skb->end - skb->head;
1223 }
1224 #endif
1225 
1226 /* Internal */
1227 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
1228 
1229 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
1230 {
1231         return &skb_shinfo(skb)->hwtstamps;
1232 }
1233 
1234 /**
1235  *      skb_queue_empty - check if a queue is empty
1236  *      @list: queue head
1237  *
1238  *      Returns true if the queue is empty, false otherwise.
1239  */
1240 static inline int skb_queue_empty(const struct sk_buff_head *list)
1241 {
1242         return list->next == (const struct sk_buff *) list;
1243 }
1244 
1245 /**
1246  *      skb_queue_is_last - check if skb is the last entry in the queue
1247  *      @list: queue head
1248  *      @skb: buffer
1249  *
1250  *      Returns true if @skb is the last buffer on the list.
1251  */
1252 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1253                                      const struct sk_buff *skb)
1254 {
1255         return skb->next == (const struct sk_buff *) list;
1256 }
1257 
1258 /**
1259  *      skb_queue_is_first - check if skb is the first entry in the queue
1260  *      @list: queue head
1261  *      @skb: buffer
1262  *
1263  *      Returns true if @skb is the first buffer on the list.
1264  */
1265 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1266                                       const struct sk_buff *skb)
1267 {
1268         return skb->prev == (const struct sk_buff *) list;
1269 }
1270 
1271 /**
1272  *      skb_queue_next - return the next packet in the queue
1273  *      @list: queue head
1274  *      @skb: current buffer
1275  *
1276  *      Return the next packet in @list after @skb.  It is only valid to
1277  *      call this if skb_queue_is_last() evaluates to false.
1278  */
1279 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1280                                              const struct sk_buff *skb)
1281 {
1282         /* This BUG_ON may seem severe, but if we just return then we
1283          * are going to dereference garbage.
1284          */
1285         BUG_ON(skb_queue_is_last(list, skb));
1286         return skb->next;
1287 }
1288 
1289 /**
1290  *      skb_queue_prev - return the prev packet in the queue
1291  *      @list: queue head
1292  *      @skb: current buffer
1293  *
1294  *      Return the prev packet in @list before @skb.  It is only valid to
1295  *      call this if skb_queue_is_first() evaluates to false.
1296  */
1297 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1298                                              const struct sk_buff *skb)
1299 {
1300         /* This BUG_ON may seem severe, but if we just return then we
1301          * are going to dereference garbage.
1302          */
1303         BUG_ON(skb_queue_is_first(list, skb));
1304         return skb->prev;
1305 }
1306 
1307 /**
1308  *      skb_get - reference buffer
1309  *      @skb: buffer to reference
1310  *
1311  *      Makes another reference to a socket buffer and returns a pointer
1312  *      to the buffer.
1313  */
1314 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1315 {
1316         atomic_inc(&skb->users);
1317         return skb;
1318 }
1319 
1320 /*
1321  * If users == 1, we are the only owner and are can avoid redundant
1322  * atomic change.
1323  */
1324 
1325 /**
1326  *      skb_cloned - is the buffer a clone
1327  *      @skb: buffer to check
1328  *
1329  *      Returns true if the buffer was generated with skb_clone() and is
1330  *      one of multiple shared copies of the buffer. Cloned buffers are
1331  *      shared data so must not be written to under normal circumstances.
1332  */
1333 static inline int skb_cloned(const struct sk_buff *skb)
1334 {
1335         return skb->cloned &&
1336                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1337 }
1338 
1339 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1340 {
1341         might_sleep_if(gfpflags_allow_blocking(pri));
1342 
1343         if (skb_cloned(skb))
1344                 return pskb_expand_head(skb, 0, 0, pri);
1345 
1346         return 0;
1347 }
1348 
1349 /**
1350  *      skb_header_cloned - is the header a clone
1351  *      @skb: buffer to check
1352  *
1353  *      Returns true if modifying the header part of the buffer requires
1354  *      the data to be copied.
1355  */
1356 static inline int skb_header_cloned(const struct sk_buff *skb)
1357 {
1358         int dataref;
1359 
1360         if (!skb->cloned)
1361                 return 0;
1362 
1363         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1364         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1365         return dataref != 1;
1366 }
1367 
1368 static inline int skb_header_unclone(struct sk_buff *skb, gfp_t pri)
1369 {
1370         might_sleep_if(gfpflags_allow_blocking(pri));
1371 
1372         if (skb_header_cloned(skb))
1373                 return pskb_expand_head(skb, 0, 0, pri);
1374 
1375         return 0;
1376 }
1377 
1378 /**
1379  *      skb_header_release - release reference to header
1380  *      @skb: buffer to operate on
1381  *
1382  *      Drop a reference to the header part of the buffer.  This is done
1383  *      by acquiring a payload reference.  You must not read from the header
1384  *      part of skb->data after this.
1385  *      Note : Check if you can use __skb_header_release() instead.
1386  */
1387 static inline void skb_header_release(struct sk_buff *skb)
1388 {
1389         BUG_ON(skb->nohdr);
1390         skb->nohdr = 1;
1391         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1392 }
1393 
1394 /**
1395  *      __skb_header_release - release reference to header
1396  *      @skb: buffer to operate on
1397  *
1398  *      Variant of skb_header_release() assuming skb is private to caller.
1399  *      We can avoid one atomic operation.
1400  */
1401 static inline void __skb_header_release(struct sk_buff *skb)
1402 {
1403         skb->nohdr = 1;
1404         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1405 }
1406 
1407 
1408 /**
1409  *      skb_shared - is the buffer shared
1410  *      @skb: buffer to check
1411  *
1412  *      Returns true if more than one person has a reference to this
1413  *      buffer.
1414  */
1415 static inline int skb_shared(const struct sk_buff *skb)
1416 {
1417         return atomic_read(&skb->users) != 1;
1418 }
1419 
1420 /**
1421  *      skb_share_check - check if buffer is shared and if so clone it
1422  *      @skb: buffer to check
1423  *      @pri: priority for memory allocation
1424  *
1425  *      If the buffer is shared the buffer is cloned and the old copy
1426  *      drops a reference. A new clone with a single reference is returned.
1427  *      If the buffer is not shared the original buffer is returned. When
1428  *      being called from interrupt status or with spinlocks held pri must
1429  *      be GFP_ATOMIC.
1430  *
1431  *      NULL is returned on a memory allocation failure.
1432  */
1433 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1434 {
1435         might_sleep_if(gfpflags_allow_blocking(pri));
1436         if (skb_shared(skb)) {
1437                 struct sk_buff *nskb = skb_clone(skb, pri);
1438 
1439                 if (likely(nskb))
1440                         consume_skb(skb);
1441                 else
1442                         kfree_skb(skb);
1443                 skb = nskb;
1444         }
1445         return skb;
1446 }
1447 
1448 /*
1449  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1450  *      packets to handle cases where we have a local reader and forward
1451  *      and a couple of other messy ones. The normal one is tcpdumping
1452  *      a packet thats being forwarded.
1453  */
1454 
1455 /**
1456  *      skb_unshare - make a copy of a shared buffer
1457  *      @skb: buffer to check
1458  *      @pri: priority for memory allocation
1459  *
1460  *      If the socket buffer is a clone then this function creates a new
1461  *      copy of the data, drops a reference count on the old copy and returns
1462  *      the new copy with the reference count at 1. If the buffer is not a clone
1463  *      the original buffer is returned. When called with a spinlock held or
1464  *      from interrupt state @pri must be %GFP_ATOMIC
1465  *
1466  *      %NULL is returned on a memory allocation failure.
1467  */
1468 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1469                                           gfp_t pri)
1470 {
1471         might_sleep_if(gfpflags_allow_blocking(pri));
1472         if (skb_cloned(skb)) {
1473                 struct sk_buff *nskb = skb_copy(skb, pri);
1474 
1475                 /* Free our shared copy */
1476                 if (likely(nskb))
1477                         consume_skb(skb);
1478                 else
1479                         kfree_skb(skb);
1480                 skb = nskb;
1481         }
1482         return skb;
1483 }
1484 
1485 /**
1486  *      skb_peek - peek at the head of an &sk_buff_head
1487  *      @list_: list to peek at
1488  *
1489  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1490  *      be careful with this one. A peek leaves the buffer on the
1491  *      list and someone else may run off with it. You must hold
1492  *      the appropriate locks or have a private queue to do this.
1493  *
1494  *      Returns %NULL for an empty list or a pointer to the head element.
1495  *      The reference count is not incremented and the reference is therefore
1496  *      volatile. Use with caution.
1497  */
1498 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1499 {
1500         struct sk_buff *skb = list_->next;
1501 
1502         if (skb == (struct sk_buff *)list_)
1503                 skb = NULL;
1504         return skb;
1505 }
1506 
1507 /**
1508  *      skb_peek_next - peek skb following the given one from a queue
1509  *      @skb: skb to start from
1510  *      @list_: list to peek at
1511  *
1512  *      Returns %NULL when the end of the list is met or a pointer to the
1513  *      next element. The reference count is not incremented and the
1514  *      reference is therefore volatile. Use with caution.
1515  */
1516 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1517                 const struct sk_buff_head *list_)
1518 {
1519         struct sk_buff *next = skb->next;
1520 
1521         if (next == (struct sk_buff *)list_)
1522                 next = NULL;
1523         return next;
1524 }
1525 
1526 /**
1527  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1528  *      @list_: list to peek at
1529  *
1530  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1531  *      be careful with this one. A peek leaves the buffer on the
1532  *      list and someone else may run off with it. You must hold
1533  *      the appropriate locks or have a private queue to do this.
1534  *
1535  *      Returns %NULL for an empty list or a pointer to the tail element.
1536  *      The reference count is not incremented and the reference is therefore
1537  *      volatile. Use with caution.
1538  */
1539 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1540 {
1541         struct sk_buff *skb = list_->prev;
1542 
1543         if (skb == (struct sk_buff *)list_)
1544                 skb = NULL;
1545         return skb;
1546 
1547 }
1548 
1549 /**
1550  *      skb_queue_len   - get queue length
1551  *      @list_: list to measure
1552  *
1553  *      Return the length of an &sk_buff queue.
1554  */
1555 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1556 {
1557         return list_->qlen;
1558 }
1559 
1560 /**
1561  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1562  *      @list: queue to initialize
1563  *
1564  *      This initializes only the list and queue length aspects of
1565  *      an sk_buff_head object.  This allows to initialize the list
1566  *      aspects of an sk_buff_head without reinitializing things like
1567  *      the spinlock.  It can also be used for on-stack sk_buff_head
1568  *      objects where the spinlock is known to not be used.
1569  */
1570 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1571 {
1572         list->prev = list->next = (struct sk_buff *)list;
1573         list->qlen = 0;
1574 }
1575 
1576 /*
1577  * This function creates a split out lock class for each invocation;
1578  * this is needed for now since a whole lot of users of the skb-queue
1579  * infrastructure in drivers have different locking usage (in hardirq)
1580  * than the networking core (in softirq only). In the long run either the
1581  * network layer or drivers should need annotation to consolidate the
1582  * main types of usage into 3 classes.
1583  */
1584 static inline void skb_queue_head_init(struct sk_buff_head *list)
1585 {
1586         spin_lock_init(&list->lock);
1587         __skb_queue_head_init(list);
1588 }
1589 
1590 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1591                 struct lock_class_key *class)
1592 {
1593         skb_queue_head_init(list);
1594         lockdep_set_class(&list->lock, class);
1595 }
1596 
1597 /*
1598  *      Insert an sk_buff on a list.
1599  *
1600  *      The "__skb_xxxx()" functions are the non-atomic ones that
1601  *      can only be called with interrupts disabled.
1602  */
1603 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1604                 struct sk_buff_head *list);
1605 static inline void __skb_insert(struct sk_buff *newsk,
1606                                 struct sk_buff *prev, struct sk_buff *next,
1607                                 struct sk_buff_head *list)
1608 {
1609         newsk->next = next;
1610         newsk->prev = prev;
1611         next->prev  = prev->next = newsk;
1612         list->qlen++;
1613 }
1614 
1615 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1616                                       struct sk_buff *prev,
1617                                       struct sk_buff *next)
1618 {
1619         struct sk_buff *first = list->next;
1620         struct sk_buff *last = list->prev;
1621 
1622         first->prev = prev;
1623         prev->next = first;
1624 
1625         last->next = next;
1626         next->prev = last;
1627 }
1628 
1629 /**
1630  *      skb_queue_splice - join two skb lists, this is designed for stacks
1631  *      @list: the new list to add
1632  *      @head: the place to add it in the first list
1633  */
1634 static inline void skb_queue_splice(const struct sk_buff_head *list,
1635                                     struct sk_buff_head *head)
1636 {
1637         if (!skb_queue_empty(list)) {
1638                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1639                 head->qlen += list->qlen;
1640         }
1641 }
1642 
1643 /**
1644  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1645  *      @list: the new list to add
1646  *      @head: the place to add it in the first list
1647  *
1648  *      The list at @list is reinitialised
1649  */
1650 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1651                                          struct sk_buff_head *head)
1652 {
1653         if (!skb_queue_empty(list)) {
1654                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1655                 head->qlen += list->qlen;
1656                 __skb_queue_head_init(list);
1657         }
1658 }
1659 
1660 /**
1661  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1662  *      @list: the new list to add
1663  *      @head: the place to add it in the first list
1664  */
1665 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1666                                          struct sk_buff_head *head)
1667 {
1668         if (!skb_queue_empty(list)) {
1669                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1670                 head->qlen += list->qlen;
1671         }
1672 }
1673 
1674 /**
1675  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1676  *      @list: the new list to add
1677  *      @head: the place to add it in the first list
1678  *
1679  *      Each of the lists is a queue.
1680  *      The list at @list is reinitialised
1681  */
1682 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1683                                               struct sk_buff_head *head)
1684 {
1685         if (!skb_queue_empty(list)) {
1686                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1687                 head->qlen += list->qlen;
1688                 __skb_queue_head_init(list);
1689         }
1690 }
1691 
1692 /**
1693  *      __skb_queue_after - queue a buffer at the list head
1694  *      @list: list to use
1695  *      @prev: place after this buffer
1696  *      @newsk: buffer to queue
1697  *
1698  *      Queue a buffer int the middle of a list. This function takes no locks
1699  *      and you must therefore hold required locks before calling it.
1700  *
1701  *      A buffer cannot be placed on two lists at the same time.
1702  */
1703 static inline void __skb_queue_after(struct sk_buff_head *list,
1704                                      struct sk_buff *prev,
1705                                      struct sk_buff *newsk)
1706 {
1707         __skb_insert(newsk, prev, prev->next, list);
1708 }
1709 
1710 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1711                 struct sk_buff_head *list);
1712 
1713 static inline void __skb_queue_before(struct sk_buff_head *list,
1714                                       struct sk_buff *next,
1715                                       struct sk_buff *newsk)
1716 {
1717         __skb_insert(newsk, next->prev, next, list);
1718 }
1719 
1720 /**
1721  *      __skb_queue_head - queue a buffer at the list head
1722  *      @list: list to use
1723  *      @newsk: buffer to queue
1724  *
1725  *      Queue a buffer at the start of a list. This function takes no locks
1726  *      and you must therefore hold required locks before calling it.
1727  *
1728  *      A buffer cannot be placed on two lists at the same time.
1729  */
1730 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1731 static inline void __skb_queue_head(struct sk_buff_head *list,
1732                                     struct sk_buff *newsk)
1733 {
1734         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1735 }
1736 
1737 /**
1738  *      __skb_queue_tail - queue a buffer at the list tail
1739  *      @list: list to use
1740  *      @newsk: buffer to queue
1741  *
1742  *      Queue a buffer at the end of a list. This function takes no locks
1743  *      and you must therefore hold required locks before calling it.
1744  *
1745  *      A buffer cannot be placed on two lists at the same time.
1746  */
1747 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1748 static inline void __skb_queue_tail(struct sk_buff_head *list,
1749                                    struct sk_buff *newsk)
1750 {
1751         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1752 }
1753 
1754 /*
1755  * remove sk_buff from list. _Must_ be called atomically, and with
1756  * the list known..
1757  */
1758 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1759 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1760 {
1761         struct sk_buff *next, *prev;
1762 
1763         list->qlen--;
1764         next       = skb->next;
1765         prev       = skb->prev;
1766         skb->next  = skb->prev = NULL;
1767         next->prev = prev;
1768         prev->next = next;
1769 }
1770 
1771 /**
1772  *      __skb_dequeue - remove from the head of the queue
1773  *      @list: list to dequeue from
1774  *
1775  *      Remove the head of the list. This function does not take any locks
1776  *      so must be used with appropriate locks held only. The head item is
1777  *      returned or %NULL if the list is empty.
1778  */
1779 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1780 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1781 {
1782         struct sk_buff *skb = skb_peek(list);
1783         if (skb)
1784                 __skb_unlink(skb, list);
1785         return skb;
1786 }
1787 
1788 /**
1789  *      __skb_dequeue_tail - remove from the tail of the queue
1790  *      @list: list to dequeue from
1791  *
1792  *      Remove the tail of the list. This function does not take any locks
1793  *      so must be used with appropriate locks held only. The tail item is
1794  *      returned or %NULL if the list is empty.
1795  */
1796 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1797 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1798 {
1799         struct sk_buff *skb = skb_peek_tail(list);
1800         if (skb)
1801                 __skb_unlink(skb, list);
1802         return skb;
1803 }
1804 
1805 
1806 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1807 {
1808         return skb->data_len;
1809 }
1810 
1811 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1812 {
1813         return skb->len - skb->data_len;
1814 }
1815 
1816 static inline unsigned int skb_pagelen(const struct sk_buff *skb)
1817 {
1818         unsigned int i, len = 0;
1819 
1820         for (i = skb_shinfo(skb)->nr_frags - 1; (int)i >= 0; i--)
1821                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1822         return len + skb_headlen(skb);
1823 }
1824 
1825 /**
1826  * __skb_fill_page_desc - initialise a paged fragment in an skb
1827  * @skb: buffer containing fragment to be initialised
1828  * @i: paged fragment index to initialise
1829  * @page: the page to use for this fragment
1830  * @off: the offset to the data with @page
1831  * @size: the length of the data
1832  *
1833  * Initialises the @i'th fragment of @skb to point to &size bytes at
1834  * offset @off within @page.
1835  *
1836  * Does not take any additional reference on the fragment.
1837  */
1838 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1839                                         struct page *page, int off, int size)
1840 {
1841         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1842 
1843         /*
1844          * Propagate page pfmemalloc to the skb if we can. The problem is
1845          * that not all callers have unique ownership of the page but rely
1846          * on page_is_pfmemalloc doing the right thing(tm).
1847          */
1848         frag->page.p              = page;
1849         frag->page_offset         = off;
1850         skb_frag_size_set(frag, size);
1851 
1852         page = compound_head(page);
1853         if (page_is_pfmemalloc(page))
1854                 skb->pfmemalloc = true;
1855 }
1856 
1857 /**
1858  * skb_fill_page_desc - initialise a paged fragment in an skb
1859  * @skb: buffer containing fragment to be initialised
1860  * @i: paged fragment index to initialise
1861  * @page: the page to use for this fragment
1862  * @off: the offset to the data with @page
1863  * @size: the length of the data
1864  *
1865  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1866  * @skb to point to @size bytes at offset @off within @page. In
1867  * addition updates @skb such that @i is the last fragment.
1868  *
1869  * Does not take any additional reference on the fragment.
1870  */
1871 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1872                                       struct page *page, int off, int size)
1873 {
1874         __skb_fill_page_desc(skb, i, page, off, size);
1875         skb_shinfo(skb)->nr_frags = i + 1;
1876 }
1877 
1878 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1879                      int size, unsigned int truesize);
1880 
1881 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1882                           unsigned int truesize);
1883 
1884 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1885 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1886 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1887 
1888 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1889 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1890 {
1891         return skb->head + skb->tail;
1892 }
1893 
1894 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1895 {
1896         skb->tail = skb->data - skb->head;
1897 }
1898 
1899 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1900 {
1901         skb_reset_tail_pointer(skb);
1902         skb->tail += offset;
1903 }
1904 
1905 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1906 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1907 {
1908         return skb->tail;
1909 }
1910 
1911 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1912 {
1913         skb->tail = skb->data;
1914 }
1915 
1916 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1917 {
1918         skb->tail = skb->data + offset;
1919 }
1920 
1921 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1922 
1923 /*
1924  *      Add data to an sk_buff
1925  */
1926 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1927 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1928 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1929 {
1930         unsigned char *tmp = skb_tail_pointer(skb);
1931         SKB_LINEAR_ASSERT(skb);
1932         skb->tail += len;
1933         skb->len  += len;
1934         return tmp;
1935 }
1936 
1937 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1938 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1939 {
1940         skb->data -= len;
1941         skb->len  += len;
1942         return skb->data;
1943 }
1944 
1945 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1946 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1947 {
1948         skb->len -= len;
1949         BUG_ON(skb->len < skb->data_len);
1950         return skb->data += len;
1951 }
1952 
1953 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1954 {
1955         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1956 }
1957 
1958 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1959 
1960 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1961 {
1962         if (len > skb_headlen(skb) &&
1963             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1964                 return NULL;
1965         skb->len -= len;
1966         return skb->data += len;
1967 }
1968 
1969 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1970 {
1971         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1972 }
1973 
1974 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1975 {
1976         if (likely(len <= skb_headlen(skb)))
1977                 return 1;
1978         if (unlikely(len > skb->len))
1979                 return 0;
1980         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1981 }
1982 
1983 void skb_condense(struct sk_buff *skb);
1984 
1985 /**
1986  *      skb_headroom - bytes at buffer head
1987  *      @skb: buffer to check
1988  *
1989  *      Return the number of bytes of free space at the head of an &sk_buff.
1990  */
1991 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1992 {
1993         return skb->data - skb->head;
1994 }
1995 
1996 /**
1997  *      skb_tailroom - bytes at buffer end
1998  *      @skb: buffer to check
1999  *
2000  *      Return the number of bytes of free space at the tail of an sk_buff
2001  */
2002 static inline int skb_tailroom(const struct sk_buff *skb)
2003 {
2004         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
2005 }
2006 
2007 /**
2008  *      skb_availroom - bytes at buffer end
2009  *      @skb: buffer to check
2010  *
2011  *      Return the number of bytes of free space at the tail of an sk_buff
2012  *      allocated by sk_stream_alloc()
2013  */
2014 static inline int skb_availroom(const struct sk_buff *skb)
2015 {
2016         if (skb_is_nonlinear(skb))
2017                 return 0;
2018 
2019         return skb->end - skb->tail - skb->reserved_tailroom;
2020 }
2021 
2022 /**
2023  *      skb_reserve - adjust headroom
2024  *      @skb: buffer to alter
2025  *      @len: bytes to move
2026  *
2027  *      Increase the headroom of an empty &sk_buff by reducing the tail
2028  *      room. This is only allowed for an empty buffer.
2029  */
2030 static inline void skb_reserve(struct sk_buff *skb, int len)
2031 {
2032         skb->data += len;
2033         skb->tail += len;
2034 }
2035 
2036 /**
2037  *      skb_tailroom_reserve - adjust reserved_tailroom
2038  *      @skb: buffer to alter
2039  *      @mtu: maximum amount of headlen permitted
2040  *      @needed_tailroom: minimum amount of reserved_tailroom
2041  *
2042  *      Set reserved_tailroom so that headlen can be as large as possible but
2043  *      not larger than mtu and tailroom cannot be smaller than
2044  *      needed_tailroom.
2045  *      The required headroom should already have been reserved before using
2046  *      this function.
2047  */
2048 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
2049                                         unsigned int needed_tailroom)
2050 {
2051         SKB_LINEAR_ASSERT(skb);
2052         if (mtu < skb_tailroom(skb) - needed_tailroom)
2053                 /* use at most mtu */
2054                 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
2055         else
2056                 /* use up to all available space */
2057                 skb->reserved_tailroom = needed_tailroom;
2058 }
2059 
2060 #define ENCAP_TYPE_ETHER        0
2061 #define ENCAP_TYPE_IPPROTO      1
2062 
2063 static inline void skb_set_inner_protocol(struct sk_buff *skb,
2064                                           __be16 protocol)
2065 {
2066         skb->inner_protocol = protocol;
2067         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
2068 }
2069 
2070 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
2071                                          __u8 ipproto)
2072 {
2073         skb->inner_ipproto = ipproto;
2074         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
2075 }
2076 
2077 static inline void skb_reset_inner_headers(struct sk_buff *skb)
2078 {
2079         skb->inner_mac_header = skb->mac_header;
2080         skb->inner_network_header = skb->network_header;
2081         skb->inner_transport_header = skb->transport_header;
2082 }
2083 
2084 static inline void skb_reset_mac_len(struct sk_buff *skb)
2085 {
2086         skb->mac_len = skb->network_header - skb->mac_header;
2087 }
2088 
2089 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
2090                                                         *skb)
2091 {
2092         return skb->head + skb->inner_transport_header;
2093 }
2094 
2095 static inline int skb_inner_transport_offset(const struct sk_buff *skb)
2096 {
2097         return skb_inner_transport_header(skb) - skb->data;
2098 }
2099 
2100 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
2101 {
2102         skb->inner_transport_header = skb->data - skb->head;
2103 }
2104 
2105 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
2106                                                    const int offset)
2107 {
2108         skb_reset_inner_transport_header(skb);
2109         skb->inner_transport_header += offset;
2110 }
2111 
2112 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
2113 {
2114         return skb->head + skb->inner_network_header;
2115 }
2116 
2117 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
2118 {
2119         skb->inner_network_header = skb->data - skb->head;
2120 }
2121 
2122 static inline void skb_set_inner_network_header(struct sk_buff *skb,
2123                                                 const int offset)
2124 {
2125         skb_reset_inner_network_header(skb);
2126         skb->inner_network_header += offset;
2127 }
2128 
2129 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
2130 {
2131         return skb->head + skb->inner_mac_header;
2132 }
2133 
2134 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
2135 {
2136         skb->inner_mac_header = skb->data - skb->head;
2137 }
2138 
2139 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
2140                                             const int offset)
2141 {
2142         skb_reset_inner_mac_header(skb);
2143         skb->inner_mac_header += offset;
2144 }
2145 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
2146 {
2147         return skb->transport_header != (typeof(skb->transport_header))~0U;
2148 }
2149 
2150 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
2151 {
2152         return skb->head + skb->transport_header;
2153 }
2154 
2155 static inline void skb_reset_transport_header(struct sk_buff *skb)
2156 {
2157         skb->transport_header = skb->data - skb->head;
2158 }
2159 
2160 static inline void skb_set_transport_header(struct sk_buff *skb,
2161                                             const int offset)
2162 {
2163         skb_reset_transport_header(skb);
2164         skb->transport_header += offset;
2165 }
2166 
2167 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
2168 {
2169         return skb->head + skb->network_header;
2170 }
2171 
2172 static inline void skb_reset_network_header(struct sk_buff *skb)
2173 {
2174         skb->network_header = skb->data - skb->head;
2175 }
2176 
2177 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
2178 {
2179         skb_reset_network_header(skb);
2180         skb->network_header += offset;
2181 }
2182 
2183 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
2184 {
2185         return skb->head + skb->mac_header;
2186 }
2187 
2188 static inline int skb_mac_offset(const struct sk_buff *skb)
2189 {
2190         return skb_mac_header(skb) - skb->data;
2191 }
2192 
2193 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
2194 {
2195         return skb->mac_header != (typeof(skb->mac_header))~0U;
2196 }
2197 
2198 static inline void skb_reset_mac_header(struct sk_buff *skb)
2199 {
2200         skb->mac_header = skb->data - skb->head;
2201 }
2202 
2203 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
2204 {
2205         skb_reset_mac_header(skb);
2206         skb->mac_header += offset;
2207 }
2208 
2209 static inline void skb_pop_mac_header(struct sk_buff *skb)
2210 {
2211         skb->mac_header = skb->network_header;
2212 }
2213 
2214 static inline void skb_probe_transport_header(struct sk_buff *skb,
2215                                               const int offset_hint)
2216 {
2217         struct flow_keys keys;
2218 
2219         if (skb_transport_header_was_set(skb))
2220                 return;
2221         else if (skb_flow_dissect_flow_keys(skb, &keys, 0))
2222                 skb_set_transport_header(skb, keys.control.thoff);
2223         else
2224                 skb_set_transport_header(skb, offset_hint);
2225 }
2226 
2227 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
2228 {
2229         if (skb_mac_header_was_set(skb)) {
2230                 const unsigned char *old_mac = skb_mac_header(skb);
2231 
2232                 skb_set_mac_header(skb, -skb->mac_len);
2233                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
2234         }
2235 }
2236 
2237 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
2238 {
2239         return skb->csum_start - skb_headroom(skb);
2240 }
2241 
2242 static inline unsigned char *skb_checksum_start(const struct sk_buff *skb)
2243 {
2244         return skb->head + skb->csum_start;
2245 }
2246 
2247 static inline int skb_transport_offset(const struct sk_buff *skb)
2248 {
2249         return skb_transport_header(skb) - skb->data;
2250 }
2251 
2252 static inline u32 skb_network_header_len(const struct sk_buff *skb)
2253 {
2254         return skb->transport_header - skb->network_header;
2255 }
2256 
2257 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
2258 {
2259         return skb->inner_transport_header - skb->inner_network_header;
2260 }
2261 
2262 static inline int skb_network_offset(const struct sk_buff *skb)
2263 {
2264         return skb_network_header(skb) - skb->data;
2265 }
2266 
2267 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2268 {
2269         return skb_inner_network_header(skb) - skb->data;
2270 }
2271 
2272 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2273 {
2274         return pskb_may_pull(skb, skb_network_offset(skb) + len);
2275 }
2276 
2277 /*
2278  * CPUs often take a performance hit when accessing unaligned memory
2279  * locations. The actual performance hit varies, it can be small if the
2280  * hardware handles it or large if we have to take an exception and fix it
2281  * in software.
2282  *
2283  * Since an ethernet header is 14 bytes network drivers often end up with
2284  * the IP header at an unaligned offset. The IP header can be aligned by
2285  * shifting the start of the packet by 2 bytes. Drivers should do this
2286  * with:
2287  *
2288  * skb_reserve(skb, NET_IP_ALIGN);
2289  *
2290  * The downside to this alignment of the IP header is that the DMA is now
2291  * unaligned. On some architectures the cost of an unaligned DMA is high
2292  * and this cost outweighs the gains made by aligning the IP header.
2293  *
2294  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2295  * to be overridden.
2296  */
2297 #ifndef NET_IP_ALIGN
2298 #define NET_IP_ALIGN    2
2299 #endif
2300 
2301 /*
2302  * The networking layer reserves some headroom in skb data (via
2303  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2304  * the header has to grow. In the default case, if the header has to grow
2305  * 32 bytes or less we avoid the reallocation.
2306  *
2307  * Unfortunately this headroom changes the DMA alignment of the resulting
2308  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2309  * on some architectures. An architecture can override this value,
2310  * perhaps setting it to a cacheline in size (since that will maintain
2311  * cacheline alignment of the DMA). It must be a power of 2.
2312  *
2313  * Various parts of the networking layer expect at least 32 bytes of
2314  * headroom, you should not reduce this.
2315  *
2316  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2317  * to reduce average number of cache lines per packet.
2318  * get_rps_cpus() for example only access one 64 bytes aligned block :
2319  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2320  */
2321 #ifndef NET_SKB_PAD
2322 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2323 #endif
2324 
2325 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2326 
2327 static inline void __skb_set_length(struct sk_buff *skb, unsigned int len)
2328 {
2329         if (unlikely(skb_is_nonlinear(skb))) {
2330                 WARN_ON(1);
2331                 return;
2332         }
2333         skb->len = len;
2334         skb_set_tail_pointer(skb, len);
2335 }
2336 
2337 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2338 {
2339         __skb_set_length(skb, len);
2340 }
2341 
2342 void skb_trim(struct sk_buff *skb, unsigned int len);
2343 
2344 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2345 {
2346         if (skb->data_len)
2347                 return ___pskb_trim(skb, len);
2348         __skb_trim(skb, len);
2349         return 0;
2350 }
2351 
2352 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2353 {
2354         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2355 }
2356 
2357 /**
2358  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2359  *      @skb: buffer to alter
2360  *      @len: new length
2361  *
2362  *      This is identical to pskb_trim except that the caller knows that
2363  *      the skb is not cloned so we should never get an error due to out-
2364  *      of-memory.
2365  */
2366 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2367 {
2368         int err = pskb_trim(skb, len);
2369         BUG_ON(err);
2370 }
2371 
2372 static inline int __skb_grow(struct sk_buff *skb, unsigned int len)
2373 {
2374         unsigned int diff = len - skb->len;
2375 
2376         if (skb_tailroom(skb) < diff) {
2377                 int ret = pskb_expand_head(skb, 0, diff - skb_tailroom(skb),
2378                                            GFP_ATOMIC);
2379                 if (ret)
2380                         return ret;
2381         }
2382         __skb_set_length(skb, len);
2383         return 0;
2384 }
2385 
2386 /**
2387  *      skb_orphan - orphan a buffer
2388  *      @skb: buffer to orphan
2389  *
2390  *      If a buffer currently has an owner then we call the owner's
2391  *      destructor function and make the @skb unowned. The buffer continues
2392  *      to exist but is no longer charged to its former owner.
2393  */
2394 static inline void skb_orphan(struct sk_buff *skb)
2395 {
2396         if (skb->destructor) {
2397                 skb->destructor(skb);
2398                 skb->destructor = NULL;
2399                 skb->sk         = NULL;
2400         } else {
2401                 BUG_ON(skb->sk);
2402         }
2403 }
2404 
2405 /**
2406  *      skb_orphan_frags - orphan the frags contained in a buffer
2407  *      @skb: buffer to orphan frags from
2408  *      @gfp_mask: allocation mask for replacement pages
2409  *
2410  *      For each frag in the SKB which needs a destructor (i.e. has an
2411  *      owner) create a copy of that frag and release the original
2412  *      page by calling the destructor.
2413  */
2414 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2415 {
2416         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2417                 return 0;
2418         return skb_copy_ubufs(skb, gfp_mask);
2419 }
2420 
2421 /**
2422  *      __skb_queue_purge - empty a list
2423  *      @list: list to empty
2424  *
2425  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2426  *      the list and one reference dropped. This function does not take the
2427  *      list lock and the caller must hold the relevant locks to use it.
2428  */
2429 void skb_queue_purge(struct sk_buff_head *list);
2430 static inline void __skb_queue_purge(struct sk_buff_head *list)
2431 {
2432         struct sk_buff *skb;
2433         while ((skb = __skb_dequeue(list)) != NULL)
2434                 kfree_skb(skb);
2435 }
2436 
2437 void skb_rbtree_purge(struct rb_root *root);
2438 
2439 void *netdev_alloc_frag(unsigned int fragsz);
2440 
2441 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2442                                    gfp_t gfp_mask);
2443 
2444 /**
2445  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2446  *      @dev: network device to receive on
2447  *      @length: length to allocate
2448  *
2449  *      Allocate a new &sk_buff and assign it a usage count of one. The
2450  *      buffer has unspecified headroom built in. Users should allocate
2451  *      the headroom they think they need without accounting for the
2452  *      built in space. The built in space is used for optimisations.
2453  *
2454  *      %NULL is returned if there is no free memory. Although this function
2455  *      allocates memory it can be called from an interrupt.
2456  */
2457 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2458                                                unsigned int length)
2459 {
2460         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2461 }
2462 
2463 /* legacy helper around __netdev_alloc_skb() */
2464 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2465                                               gfp_t gfp_mask)
2466 {
2467         return __netdev_alloc_skb(NULL, length, gfp_mask);
2468 }
2469 
2470 /* legacy helper around netdev_alloc_skb() */
2471 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2472 {
2473         return netdev_alloc_skb(NULL, length);
2474 }
2475 
2476 
2477 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2478                 unsigned int length, gfp_t gfp)
2479 {
2480         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2481 
2482         if (NET_IP_ALIGN && skb)
2483                 skb_reserve(skb, NET_IP_ALIGN);
2484         return skb;
2485 }
2486 
2487 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2488                 unsigned int length)
2489 {
2490         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2491 }
2492 
2493 static inline void skb_free_frag(void *addr)
2494 {
2495         page_frag_free(addr);
2496 }
2497 
2498 void *napi_alloc_frag(unsigned int fragsz);
2499 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2500                                  unsigned int length, gfp_t gfp_mask);
2501 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2502                                              unsigned int length)
2503 {
2504         return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2505 }
2506 void napi_consume_skb(struct sk_buff *skb, int budget);
2507 
2508 void __kfree_skb_flush(void);
2509 void __kfree_skb_defer(struct sk_buff *skb);
2510 
2511 /**
2512  * __dev_alloc_pages - allocate page for network Rx
2513  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2514  * @order: size of the allocation
2515  *
2516  * Allocate a new page.
2517  *
2518  * %NULL is returned if there is no free memory.
2519 */
2520 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2521                                              unsigned int order)
2522 {
2523         /* This piece of code contains several assumptions.
2524          * 1.  This is for device Rx, therefor a cold page is preferred.
2525          * 2.  The expectation is the user wants a compound page.
2526          * 3.  If requesting a order 0 page it will not be compound
2527          *     due to the check to see if order has a value in prep_new_page
2528          * 4.  __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2529          *     code in gfp_to_alloc_flags that should be enforcing this.
2530          */
2531         gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
2532 
2533         return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2534 }
2535 
2536 static inline struct page *dev_alloc_pages(unsigned int order)
2537 {
2538         return __dev_alloc_pages(GFP_ATOMIC | __GFP_NOWARN, order);
2539 }
2540 
2541 /**
2542  * __dev_alloc_page - allocate a page for network Rx
2543  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2544  *
2545  * Allocate a new page.
2546  *
2547  * %NULL is returned if there is no free memory.
2548  */
2549 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2550 {
2551         return __dev_alloc_pages(gfp_mask, 0);
2552 }
2553 
2554 static inline struct page *dev_alloc_page(void)
2555 {
2556         return dev_alloc_pages(0);
2557 }
2558 
2559 /**
2560  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2561  *      @page: The page that was allocated from skb_alloc_page
2562  *      @skb: The skb that may need pfmemalloc set
2563  */
2564 static inline void skb_propagate_pfmemalloc(struct page *page,
2565                                              struct sk_buff *skb)
2566 {
2567         if (page_is_pfmemalloc(page))
2568                 skb->pfmemalloc = true;
2569 }
2570 
2571 /**
2572  * skb_frag_page - retrieve the page referred to by a paged fragment
2573  * @frag: the paged fragment
2574  *
2575  * Returns the &struct page associated with @frag.
2576  */
2577 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2578 {
2579         return frag->page.p;
2580 }
2581 
2582 /**
2583  * __skb_frag_ref - take an addition reference on a paged fragment.
2584  * @frag: the paged fragment
2585  *
2586  * Takes an additional reference on the paged fragment @frag.
2587  */
2588 static inline void __skb_frag_ref(skb_frag_t *frag)
2589 {
2590         get_page(skb_frag_page(frag));
2591 }
2592 
2593 /**
2594  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2595  * @skb: the buffer
2596  * @f: the fragment offset.
2597  *
2598  * Takes an additional reference on the @f'th paged fragment of @skb.
2599  */
2600 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2601 {
2602         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2603 }
2604 
2605 /**
2606  * __skb_frag_unref - release a reference on a paged fragment.
2607  * @frag: the paged fragment
2608  *
2609  * Releases a reference on the paged fragment @frag.
2610  */
2611 static inline void __skb_frag_unref(skb_frag_t *frag)
2612 {
2613         put_page(skb_frag_page(frag));
2614 }
2615 
2616 /**
2617  * skb_frag_unref - release a reference on a paged fragment of an skb.
2618  * @skb: the buffer
2619  * @f: the fragment offset
2620  *
2621  * Releases a reference on the @f'th paged fragment of @skb.
2622  */
2623 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2624 {
2625         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2626 }
2627 
2628 /**
2629  * skb_frag_address - gets the address of the data contained in a paged fragment
2630  * @frag: the paged fragment buffer
2631  *
2632  * Returns the address of the data within @frag. The page must already
2633  * be mapped.
2634  */
2635 static inline void *skb_frag_address(const skb_frag_t *frag)
2636 {
2637         return page_address(skb_frag_page(frag)) + frag->page_offset;
2638 }
2639 
2640 /**
2641  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2642  * @frag: the paged fragment buffer
2643  *
2644  * Returns the address of the data within @frag. Checks that the page
2645  * is mapped and returns %NULL otherwise.
2646  */
2647 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2648 {
2649         void *ptr = page_address(skb_frag_page(frag));
2650         if (unlikely(!ptr))
2651                 return NULL;
2652 
2653         return ptr + frag->page_offset;
2654 }
2655 
2656 /**
2657  * __skb_frag_set_page - sets the page contained in a paged fragment
2658  * @frag: the paged fragment
2659  * @page: the page to set
2660  *
2661  * Sets the fragment @frag to contain @page.
2662  */
2663 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2664 {
2665         frag->page.p = page;
2666 }
2667 
2668 /**
2669  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2670  * @skb: the buffer
2671  * @f: the fragment offset
2672  * @page: the page to set
2673  *
2674  * Sets the @f'th fragment of @skb to contain @page.
2675  */
2676 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2677                                      struct page *page)
2678 {
2679         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2680 }
2681 
2682 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2683 
2684 /**
2685  * skb_frag_dma_map - maps a paged fragment via the DMA API
2686  * @dev: the device to map the fragment to
2687  * @frag: the paged fragment to map
2688  * @offset: the offset within the fragment (starting at the
2689  *          fragment's own offset)
2690  * @size: the number of bytes to map
2691  * @dir: the direction of the mapping (%PCI_DMA_*)
2692  *
2693  * Maps the page associated with @frag to @device.
2694  */
2695 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2696                                           const skb_frag_t *frag,
2697                                           size_t offset, size_t size,
2698                                           enum dma_data_direction dir)
2699 {
2700         return dma_map_page(dev, skb_frag_page(frag),
2701                             frag->page_offset + offset, size, dir);
2702 }
2703 
2704 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2705                                         gfp_t gfp_mask)
2706 {
2707         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2708 }
2709 
2710 
2711 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2712                                                   gfp_t gfp_mask)
2713 {
2714         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2715 }
2716 
2717 
2718 /**
2719  *      skb_clone_writable - is the header of a clone writable
2720  *      @skb: buffer to check
2721  *      @len: length up to which to write
2722  *
2723  *      Returns true if modifying the header part of the cloned buffer
2724  *      does not requires the data to be copied.
2725  */
2726 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2727 {
2728         return !skb_header_cloned(skb) &&
2729                skb_headroom(skb) + len <= skb->hdr_len;
2730 }
2731 
2732 static inline int skb_try_make_writable(struct sk_buff *skb,
2733                                         unsigned int write_len)
2734 {
2735         return skb_cloned(skb) && !skb_clone_writable(skb, write_len) &&
2736                pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2737 }
2738 
2739 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2740                             int cloned)
2741 {
2742         int delta = 0;
2743 
2744         if (headroom > skb_headroom(skb))
2745                 delta = headroom - skb_headroom(skb);
2746 
2747         if (delta || cloned)
2748                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2749                                         GFP_ATOMIC);
2750         return 0;
2751 }
2752 
2753 /**
2754  *      skb_cow - copy header of skb when it is required
2755  *      @skb: buffer to cow
2756  *      @headroom: needed headroom
2757  *
2758  *      If the skb passed lacks sufficient headroom or its data part
2759  *      is shared, data is reallocated. If reallocation fails, an error
2760  *      is returned and original skb is not changed.
2761  *
2762  *      The result is skb with writable area skb->head...skb->tail
2763  *      and at least @headroom of space at head.
2764  */
2765 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2766 {
2767         return __skb_cow(skb, headroom, skb_cloned(skb));
2768 }
2769 
2770 /**
2771  *      skb_cow_head - skb_cow but only making the head writable
2772  *      @skb: buffer to cow
2773  *      @headroom: needed headroom
2774  *
2775  *      This function is identical to skb_cow except that we replace the
2776  *      skb_cloned check by skb_header_cloned.  It should be used when
2777  *      you only need to push on some header and do not need to modify
2778  *      the data.
2779  */
2780 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2781 {
2782         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2783 }
2784 
2785 /**
2786  *      skb_padto       - pad an skbuff up to a minimal size
2787  *      @skb: buffer to pad
2788  *      @len: minimal length
2789  *
2790  *      Pads up a buffer to ensure the trailing bytes exist and are
2791  *      blanked. If the buffer already contains sufficient data it
2792  *      is untouched. Otherwise it is extended. Returns zero on
2793  *      success. The skb is freed on error.
2794  */
2795 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2796 {
2797         unsigned int size = skb->len;
2798         if (likely(size >= len))
2799                 return 0;
2800         return skb_pad(skb, len - size);
2801 }
2802 
2803 /**
2804  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
2805  *      @skb: buffer to pad
2806  *      @len: minimal length
2807  *
2808  *      Pads up a buffer to ensure the trailing bytes exist and are
2809  *      blanked. If the buffer already contains sufficient data it
2810  *      is untouched. Otherwise it is extended. Returns zero on
2811  *      success. The skb is freed on error.
2812  */
2813 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2814 {
2815         unsigned int size = skb->len;
2816 
2817         if (unlikely(size < len)) {
2818                 len -= size;
2819                 if (skb_pad(skb, len))
2820                         return -ENOMEM;
2821                 __skb_put(skb, len);
2822         }
2823         return 0;
2824 }
2825 
2826 static inline int skb_add_data(struct sk_buff *skb,
2827                                struct iov_iter *from, int copy)
2828 {
2829         const int off = skb->len;
2830 
2831         if (skb->ip_summed == CHECKSUM_NONE) {
2832                 __wsum csum = 0;
2833                 if (csum_and_copy_from_iter_full(skb_put(skb, copy), copy,
2834                                                  &csum, from)) {
2835                         skb->csum = csum_block_add(skb->csum, csum, off);
2836                         return 0;
2837                 }
2838         } else if (copy_from_iter_full(skb_put(skb, copy), copy, from))
2839                 return 0;
2840 
2841         __skb_trim(skb, off);
2842         return -EFAULT;
2843 }
2844 
2845 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2846                                     const struct page *page, int off)
2847 {
2848         if (i) {
2849                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2850 
2851                 return page == skb_frag_page(frag) &&
2852                        off == frag->page_offset + skb_frag_size(frag);
2853         }
2854         return false;
2855 }
2856 
2857 static inline int __skb_linearize(struct sk_buff *skb)
2858 {
2859         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2860 }
2861 
2862 /**
2863  *      skb_linearize - convert paged skb to linear one
2864  *      @skb: buffer to linarize
2865  *
2866  *      If there is no free memory -ENOMEM is returned, otherwise zero
2867  *      is returned and the old skb data released.
2868  */
2869 static inline int skb_linearize(struct sk_buff *skb)
2870 {
2871         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2872 }
2873 
2874 /**
2875  * skb_has_shared_frag - can any frag be overwritten
2876  * @skb: buffer to test
2877  *
2878  * Return true if the skb has at least one frag that might be modified
2879  * by an external entity (as in vmsplice()/sendfile())
2880  */
2881 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2882 {
2883         return skb_is_nonlinear(skb) &&
2884                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2885 }
2886 
2887 /**
2888  *      skb_linearize_cow - make sure skb is linear and writable
2889  *      @skb: buffer to process
2890  *
2891  *      If there is no free memory -ENOMEM is returned, otherwise zero
2892  *      is returned and the old skb data released.
2893  */
2894 static inline int skb_linearize_cow(struct sk_buff *skb)
2895 {
2896         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2897                __skb_linearize(skb) : 0;
2898 }
2899 
2900 static __always_inline void
2901 __skb_postpull_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
2902                      unsigned int off)
2903 {
2904         if (skb->ip_summed == CHECKSUM_COMPLETE)
2905                 skb->csum = csum_block_sub(skb->csum,
2906                                            csum_partial(start, len, 0), off);
2907         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2908                  skb_checksum_start_offset(skb) < 0)
2909                 skb->ip_summed = CHECKSUM_NONE;
2910 }
2911 
2912 /**
2913  *      skb_postpull_rcsum - update checksum for received skb after pull
2914  *      @skb: buffer to update
2915  *      @start: start of data before pull
2916  *      @len: length of data pulled
2917  *
2918  *      After doing a pull on a received packet, you need to call this to
2919  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2920  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2921  */
2922 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2923                                       const void *start, unsigned int len)
2924 {
2925         __skb_postpull_rcsum(skb, start, len, 0);
2926 }
2927 
2928 static __always_inline void
2929 __skb_postpush_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
2930                      unsigned int off)
2931 {
2932         if (skb->ip_summed == CHECKSUM_COMPLETE)
2933                 skb->csum = csum_block_add(skb->csum,
2934                                            csum_partial(start, len, 0), off);
2935 }
2936 
2937 /**
2938  *      skb_postpush_rcsum - update checksum for received skb after push
2939  *      @skb: buffer to update
2940  *      @start: start of data after push
2941  *      @len: length of data pushed
2942  *
2943  *      After doing a push on a received packet, you need to call this to
2944  *      update the CHECKSUM_COMPLETE checksum.
2945  */
2946 static inline void skb_postpush_rcsum(struct sk_buff *skb,
2947                                       const void *start, unsigned int len)
2948 {
2949         __skb_postpush_rcsum(skb, start, len, 0);
2950 }
2951 
2952 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2953 
2954 /**
2955  *      skb_push_rcsum - push skb and update receive checksum
2956  *      @skb: buffer to update
2957  *      @len: length of data pulled
2958  *
2959  *      This function performs an skb_push on the packet and updates
2960  *      the CHECKSUM_COMPLETE checksum.  It should be used on
2961  *      receive path processing instead of skb_push unless you know
2962  *      that the checksum difference is zero (e.g., a valid IP header)
2963  *      or you are setting ip_summed to CHECKSUM_NONE.
2964  */
2965 static inline unsigned char *skb_push_rcsum(struct sk_buff *skb,
2966                                             unsigned int len)
2967 {
2968         skb_push(skb, len);
2969         skb_postpush_rcsum(skb, skb->data, len);
2970         return skb->data;
2971 }
2972 
2973 /**
2974  *      pskb_trim_rcsum - trim received skb and update checksum
2975  *      @skb: buffer to trim
2976  *      @len: new length
2977  *
2978  *      This is exactly the same as pskb_trim except that it ensures the
2979  *      checksum of received packets are still valid after the operation.
2980  */
2981 
2982 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2983 {
2984         if (likely(len >= skb->len))
2985                 return 0;
2986         if (skb->ip_summed == CHECKSUM_COMPLETE)
2987                 skb->ip_summed = CHECKSUM_NONE;
2988         return __pskb_trim(skb, len);
2989 }
2990 
2991 static inline int __skb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2992 {
2993         if (skb->ip_summed == CHECKSUM_COMPLETE)
2994                 skb->ip_summed = CHECKSUM_NONE;
2995         __skb_trim(skb, len);
2996         return 0;
2997 }
2998 
2999 static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
3000 {
3001         if (skb->ip_summed == CHECKSUM_COMPLETE)
3002                 skb->ip_summed = CHECKSUM_NONE;
3003         return __skb_grow(skb, len);
3004 }
3005 
3006 #define skb_queue_walk(queue, skb) \
3007                 for (skb = (queue)->next;                                       \
3008                      skb != (struct sk_buff *)(queue);                          \
3009                      skb = skb->next)
3010 
3011 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
3012                 for (skb = (queue)->next, tmp = skb->next;                      \
3013                      skb != (struct sk_buff *)(queue);                          \
3014                      skb = tmp, tmp = skb->next)
3015 
3016 #define skb_queue_walk_from(queue, skb)                                         \
3017                 for (; skb != (struct sk_buff *)(queue);                        \
3018                      skb = skb->next)
3019 
3020 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
3021                 for (tmp = skb->next;                                           \
3022                      skb != (struct sk_buff *)(queue);                          \
3023                      skb = tmp, tmp = skb->next)
3024 
3025 #define skb_queue_reverse_walk(queue, skb) \
3026                 for (skb = (queue)->prev;                                       \
3027                      skb != (struct sk_buff *)(queue);                          \
3028                      skb = skb->prev)
3029 
3030 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
3031                 for (skb = (queue)->prev, tmp = skb->prev;                      \
3032                      skb != (struct sk_buff *)(queue);                          \
3033                      skb = tmp, tmp = skb->prev)
3034 
3035 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
3036                 for (tmp = skb->prev;                                           \
3037                      skb != (struct sk_buff *)(queue);                          \
3038                      skb = tmp, tmp = skb->prev)
3039 
3040 static inline bool skb_has_frag_list(const struct sk_buff *skb)
3041 {
3042         return skb_shinfo(skb)->frag_list != NULL;
3043 }
3044 
3045 static inline void skb_frag_list_init(struct sk_buff *skb)
3046 {
3047         skb_shinfo(skb)->frag_list = NULL;
3048 }
3049 
3050 #define skb_walk_frags(skb, iter)       \
3051         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
3052 
3053 
3054 int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
3055                                 const struct sk_buff *skb);
3056 struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
3057                                         void (*destructor)(struct sock *sk,
3058                                                            struct sk_buff *skb),
3059                                         int *peeked, int *off, int *err,
3060                                         struct sk_buff **last);
3061 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
3062                                     void (*destructor)(struct sock *sk,
3063                                                        struct sk_buff *skb),
3064                                     int *peeked, int *off, int *err);
3065 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
3066                                   int *err);
3067 unsigned int datagram_poll(struct file *file, struct socket *sock,
3068                            struct poll_table_struct *wait);
3069 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
3070                            struct iov_iter *to, int size);
3071 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
3072                                         struct msghdr *msg, int size)
3073 {
3074         return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
3075 }
3076 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
3077                                    struct msghdr *msg);
3078 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
3079                                  struct iov_iter *from, int len);
3080 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
3081 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
3082 void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len);
3083 static inline void skb_free_datagram_locked(struct sock *sk,
3084                                             struct sk_buff *skb)
3085 {
3086         __skb_free_datagram_locked(sk, skb, 0);
3087 }
3088 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
3089 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
3090 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
3091 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
3092                               int len, __wsum csum);
3093 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3094                     struct pipe_inode_info *pipe, unsigned int len,
3095                     unsigned int flags);
3096 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
3097 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
3098 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
3099                  int len, int hlen);
3100 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
3101 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
3102 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
3103 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
3104 bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu);
3105 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
3106 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
3107 int skb_ensure_writable(struct sk_buff *skb, int write_len);
3108 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);
3109 int skb_vlan_pop(struct sk_buff *skb);
3110 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
3111 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
3112                              gfp_t gfp);
3113 
3114 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
3115 {
3116         return copy_from_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3117 }
3118 
3119 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
3120 {
3121         return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3122 }
3123 
3124 struct skb_checksum_ops {
3125         __wsum (*update)(const void *mem, int len, __wsum wsum);
3126         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
3127 };
3128 
3129 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3130                       __wsum csum, const struct skb_checksum_ops *ops);
3131 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
3132                     __wsum csum);
3133 
3134 static inline void * __must_check
3135 __skb_header_pointer(const struct sk_buff *skb, int offset,
3136                      int len, void *data, int hlen, void *buffer)
3137 {
3138         if (hlen - offset >= len)
3139                 return data + offset;
3140 
3141         if (!skb ||
3142             skb_copy_bits(skb, offset, buffer, len) < 0)
3143                 return NULL;
3144 
3145         return buffer;
3146 }
3147 
3148 static inline void * __must_check
3149 skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
3150 {
3151         return __skb_header_pointer(skb, offset, len, skb->data,
3152                                     skb_headlen(skb), buffer);
3153 }
3154 
3155 /**
3156  *      skb_needs_linearize - check if we need to linearize a given skb
3157  *                            depending on the given device features.
3158  *      @skb: socket buffer to check
3159  *      @features: net device features
3160  *
3161  *      Returns true if either:
3162  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
3163  *      2. skb is fragmented and the device does not support SG.
3164  */
3165 static inline bool skb_needs_linearize(struct sk_buff *skb,
3166                                        netdev_features_t features)
3167 {
3168         return skb_is_nonlinear(skb) &&
3169                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
3170                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
3171 }
3172 
3173 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
3174                                              void *to,
3175                                              const unsigned int len)
3176 {
3177         memcpy(to, skb->data, len);
3178 }
3179 
3180 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
3181                                                     const int offset, void *to,
3182                                                     const unsigned int len)
3183 {
3184         memcpy(to, skb->data + offset, len);
3185 }
3186 
3187 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
3188                                            const void *from,
3189                                            const unsigned int len)
3190 {
3191         memcpy(skb->data, from, len);
3192 }
3193 
3194 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
3195                                                   const int offset,
3196                                                   const void *from,
3197                                                   const unsigned int len)
3198 {
3199         memcpy(skb->data + offset, from, len);
3200 }
3201 
3202 void skb_init(void);
3203 
3204 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
3205 {
3206         return skb->tstamp;
3207 }
3208 
3209 /**
3210  *      skb_get_timestamp - get timestamp from a skb
3211  *      @skb: skb to get stamp from
3212  *      @stamp: pointer to struct timeval to store stamp in
3213  *
3214  *      Timestamps are stored in the skb as offsets to a base timestamp.
3215  *      This function converts the offset back to a struct timeval and stores
3216  *      it in stamp.
3217  */
3218 static inline void skb_get_timestamp(const struct sk_buff *skb,
3219                                      struct timeval *stamp)
3220 {
3221         *stamp = ktime_to_timeval(skb->tstamp);
3222 }
3223 
3224 static inline void skb_get_timestampns(const struct sk_buff *skb,
3225                                        struct timespec *stamp)
3226 {
3227         *stamp = ktime_to_timespec(skb->tstamp);
3228 }
3229 
3230 static inline void __net_timestamp(struct sk_buff *skb)
3231 {
3232         skb->tstamp = ktime_get_real();
3233 }
3234 
3235 static inline ktime_t net_timedelta(ktime_t t)
3236 {
3237         return ktime_sub(ktime_get_real(), t);
3238 }
3239 
3240 static inline ktime_t net_invalid_timestamp(void)
3241 {
3242         return 0;
3243 }
3244 
3245 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
3246 
3247 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
3248 
3249 void skb_clone_tx_timestamp(struct sk_buff *skb);
3250 bool skb_defer_rx_timestamp(struct sk_buff *skb);
3251 
3252 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
3253 
3254 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
3255 {
3256 }
3257 
3258 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
3259 {
3260         return false;
3261 }
3262 
3263 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
3264 
3265 /**
3266  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
3267  *
3268  * PHY drivers may accept clones of transmitted packets for
3269  * timestamping via their phy_driver.txtstamp method. These drivers
3270  * must call this function to return the skb back to the stack with a
3271  * timestamp.
3272  *
3273  * @skb: clone of the the original outgoing packet
3274  * @hwtstamps: hardware time stamps
3275  *
3276  */
3277 void skb_complete_tx_timestamp(struct sk_buff *skb,
3278                                struct skb_shared_hwtstamps *hwtstamps);
3279 
3280 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3281                      struct skb_shared_hwtstamps *hwtstamps,
3282                      struct sock *sk, int tstype);
3283 
3284 /**
3285  * skb_tstamp_tx - queue clone of skb with send time stamps
3286  * @orig_skb:   the original outgoing packet
3287  * @hwtstamps:  hardware time stamps, may be NULL if not available
3288  *
3289  * If the skb has a socket associated, then this function clones the
3290  * skb (thus sharing the actual data and optional structures), stores
3291  * the optional hardware time stamping information (if non NULL) or
3292  * generates a software time stamp (otherwise), then queues the clone
3293  * to the error queue of the socket.  Errors are silently ignored.
3294  */
3295 void skb_tstamp_tx(struct sk_buff *orig_skb,
3296                    struct skb_shared_hwtstamps *hwtstamps);
3297 
3298 static inline void sw_tx_timestamp(struct sk_buff *skb)
3299 {
3300         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
3301             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
3302                 skb_tstamp_tx(skb, NULL);
3303 }
3304 
3305 /**
3306  * skb_tx_timestamp() - Driver hook for transmit timestamping
3307  *
3308  * Ethernet MAC Drivers should call this function in their hard_xmit()
3309  * function immediately before giving the sk_buff to the MAC hardware.
3310  *
3311  * Specifically, one should make absolutely sure that this function is
3312  * called before TX completion of this packet can trigger.  Otherwise
3313  * the packet could potentially already be freed.
3314  *
3315  * @skb: A socket buffer.
3316  */
3317 static inline void skb_tx_timestamp(struct sk_buff *skb)
3318 {
3319         skb_clone_tx_timestamp(skb);
3320         sw_tx_timestamp(skb);
3321 }
3322 
3323 /**
3324  * skb_complete_wifi_ack - deliver skb with wifi status
3325  *
3326  * @skb: the original outgoing packet
3327  * @acked: ack status
3328  *
3329  */
3330 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
3331 
3332 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
3333 __sum16 __skb_checksum_complete(struct sk_buff *skb);
3334 
3335 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
3336 {
3337         return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
3338                 skb->csum_valid ||
3339                 (skb->ip_summed == CHECKSUM_PARTIAL &&
3340                  skb_checksum_start_offset(skb) >= 0));
3341 }
3342 
3343 /**
3344  *      skb_checksum_complete - Calculate checksum of an entire packet
3345  *      @skb: packet to process
3346  *
3347  *      This function calculates the checksum over the entire packet plus
3348  *      the value of skb->csum.  The latter can be used to supply the
3349  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
3350  *      checksum.
3351  *
3352  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
3353  *      this function can be used to verify that checksum on received
3354  *      packets.  In that case the function should return zero if the
3355  *      checksum is correct.  In particular, this function will return zero
3356  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
3357  *      hardware has already verified the correctness of the checksum.
3358  */
3359 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
3360 {
3361         return skb_csum_unnecessary(skb) ?
3362                0 : __skb_checksum_complete(skb);
3363 }
3364 
3365 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
3366 {
3367         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3368                 if (skb->csum_level == 0)
3369                         skb->ip_summed = CHECKSUM_NONE;
3370                 else
3371                         skb->csum_level--;
3372         }
3373 }
3374 
3375 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
3376 {
3377         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3378                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3379                         skb->csum_level++;
3380         } else if (skb->ip_summed == CHECKSUM_NONE) {
3381                 skb->ip_summed = CHECKSUM_UNNECESSARY;
3382                 skb->csum_level = 0;
3383         }
3384 }
3385 
3386 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
3387 {
3388         /* Mark current checksum as bad (typically called from GRO
3389          * path). In the case that ip_summed is CHECKSUM_NONE
3390          * this must be the first checksum encountered in the packet.
3391          * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
3392          * checksum after the last one validated. For UDP, a zero
3393          * checksum can not be marked as bad.
3394          */
3395 
3396         if (skb->ip_summed == CHECKSUM_NONE ||
3397             skb->ip_summed == CHECKSUM_UNNECESSARY)
3398                 skb->csum_bad = 1;
3399 }
3400 
3401 /* Check if we need to perform checksum complete validation.
3402  *
3403  * Returns true if checksum complete is needed, false otherwise
3404  * (either checksum is unnecessary or zero checksum is allowed).
3405  */
3406 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3407                                                   bool zero_okay,
3408                                                   __sum16 check)
3409 {
3410         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3411                 skb->csum_valid = 1;
3412                 __skb_decr_checksum_unnecessary(skb);
3413                 return false;
3414         }
3415 
3416         return true;
3417 }
3418 
3419 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3420  * in checksum_init.
3421  */
3422 #define CHECKSUM_BREAK 76
3423 
3424 /* Unset checksum-complete
3425  *
3426  * Unset checksum complete can be done when packet is being modified
3427  * (uncompressed for instance) and checksum-complete value is
3428  * invalidated.
3429  */
3430 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3431 {
3432         if (skb->ip_summed == CHECKSUM_COMPLETE)
3433                 skb->ip_summed = CHECKSUM_NONE;
3434 }
3435 
3436 /* Validate (init) checksum based on checksum complete.
3437  *
3438  * Return values:
3439  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
3440  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3441  *      checksum is stored in skb->csum for use in __skb_checksum_complete
3442  *   non-zero: value of invalid checksum
3443  *
3444  */
3445 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3446                                                        bool complete,
3447                                                        __wsum psum)
3448 {
3449         if (skb->ip_summed == CHECKSUM_COMPLETE) {
3450                 if (!csum_fold(csum_add(psum, skb->csum))) {
3451                         skb->csum_valid = 1;
3452                         return 0;
3453                 }
3454         } else if (skb->csum_bad) {
3455                 /* ip_summed == CHECKSUM_NONE in this case */
3456                 return (__force __sum16)1;
3457         }
3458 
3459         skb->csum = psum;
3460 
3461         if (complete || skb->len <= CHECKSUM_BREAK) {
3462                 __sum16 csum;
3463 
3464                 csum = __skb_checksum_complete(skb);
3465                 skb->csum_valid = !csum;
3466                 return csum;
3467         }
3468 
3469         return 0;
3470 }
3471 
3472 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3473 {
3474         return 0;
3475 }
3476 
3477 /* Perform checksum validate (init). Note that this is a macro since we only
3478  * want to calculate the pseudo header which is an input function if necessary.
3479  * First we try to validate without any computation (checksum unnecessary) and
3480  * then calculate based on checksum complete calling the function to compute
3481  * pseudo header.
3482  *
3483  * Return values:
3484  *   0: checksum is validated or try to in skb_checksum_complete
3485  *   non-zero: value of invalid checksum
3486  */
3487 #define __skb_checksum_validate(skb, proto, complete,                   \
3488                                 zero_okay, check, compute_pseudo)       \
3489 ({                                                                      \
3490         __sum16 __ret = 0;                                              \
3491         skb->csum_valid = 0;                                            \
3492         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3493                 __ret = __skb_checksum_validate_complete(skb,           \
3494                                 complete, compute_pseudo(skb, proto));  \
3495         __ret;                                                          \
3496 })
3497 
3498 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3499         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3500 
3501 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3502         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3503 
3504 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3505         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3506 
3507 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3508                                          compute_pseudo)                \
3509         __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3510 
3511 #define skb_checksum_simple_validate(skb)                               \
3512         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3513 
3514 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3515 {
3516         return (skb->ip_summed == CHECKSUM_NONE &&
3517                 skb->csum_valid && !skb->csum_bad);
3518 }
3519 
3520 static inline void __skb_checksum_convert(struct sk_buff *skb,
3521                                           __sum16 check, __wsum pseudo)
3522 {
3523         skb->csum = ~pseudo;
3524         skb->ip_summed = CHECKSUM_COMPLETE;
3525 }
3526 
3527 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3528 do {                                                                    \
3529         if (__skb_checksum_convert_check(skb))                          \
3530                 __skb_checksum_convert(skb, check,                      \
3531                                        compute_pseudo(skb, proto));     \
3532 } while (0)
3533 
3534 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3535                                               u16 start, u16 offset)
3536 {
3537         skb->ip_summed = CHECKSUM_PARTIAL;
3538         skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3539         skb->csum_offset = offset - start;
3540 }
3541 
3542 /* Update skbuf and packet to reflect the remote checksum offload operation.
3543  * When called, ptr indicates the starting point for skb->csum when
3544  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3545  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3546  */
3547 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3548                                        int start, int offset, bool nopartial)
3549 {
3550         __wsum delta;
3551 
3552         if (!nopartial) {
3553                 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3554                 return;
3555         }
3556 
3557          if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3558                 __skb_checksum_complete(skb);
3559                 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3560         }
3561 
3562         delta = remcsum_adjust(ptr, skb->csum, start, offset);
3563 
3564         /* Adjust skb->csum since we changed the packet */
3565         skb->csum = csum_add(skb->csum, delta);
3566 }
3567 
3568 static inline struct nf_conntrack *skb_nfct(const struct sk_buff *skb)
3569 {
3570 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3571         return (void *)(skb->_nfct & SKB_NFCT_PTRMASK);
3572 #else
3573         return NULL;
3574 #endif
3575 }
3576 
3577 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3578 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3579 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3580 {
3581         if (nfct && atomic_dec_and_test(&nfct->use))
3582                 nf_conntrack_destroy(nfct);
3583 }
3584 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3585 {
3586         if (nfct)
3587                 atomic_inc(&nfct->use);
3588 }
3589 #endif
3590 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3591 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3592 {
3593         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3594                 kfree(nf_bridge);
3595 }
3596 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3597 {
3598         if (nf_bridge)
3599                 atomic_inc(&nf_bridge->use);
3600 }
3601 #endif /* CONFIG_BRIDGE_NETFILTER */
3602 static inline void nf_reset(struct sk_buff *skb)
3603 {
3604 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3605         nf_conntrack_put(skb_nfct(skb));
3606         skb->_nfct = 0;
3607 #endif
3608 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3609         nf_bridge_put(skb->nf_bridge);
3610         skb->nf_bridge = NULL;
3611 #endif
3612 }
3613 
3614 static inline void nf_reset_trace(struct sk_buff *skb)
3615 {
3616 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3617         skb->nf_trace = 0;
3618 #endif
3619 }
3620 
3621 /* Note: This doesn't put any conntrack and bridge info in dst. */
3622 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3623                              bool copy)
3624 {
3625 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3626         dst->_nfct = src->_nfct;
3627         nf_conntrack_get(skb_nfct(src));
3628 #endif
3629 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3630         dst->nf_bridge  = src->nf_bridge;
3631         nf_bridge_get(src->nf_bridge);
3632 #endif
3633 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3634         if (copy)
3635                 dst->nf_trace = src->nf_trace;
3636 #endif
3637 }
3638 
3639 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3640 {
3641 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3642         nf_conntrack_put(skb_nfct(dst));
3643 #endif
3644 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3645         nf_bridge_put(dst->nf_bridge);
3646 #endif
3647         __nf_copy(dst, src, true);
3648 }
3649 
3650 #ifdef CONFIG_NETWORK_SECMARK
3651 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3652 {
3653         to->secmark = from->secmark;
3654 }
3655 
3656 static inline void skb_init_secmark(struct sk_buff *skb)
3657 {
3658         skb->secmark = 0;
3659 }
3660 #else
3661 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3662 { }
3663 
3664 static inline void skb_init_secmark(struct sk_buff *skb)
3665 { }
3666 #endif
3667 
3668 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3669 {
3670         return !skb->destructor &&
3671 #if IS_ENABLED(CONFIG_XFRM)
3672                 !skb->sp &&
3673 #endif
3674                 !skb_nfct(skb) &&
3675                 !skb->_skb_refdst &&
3676                 !skb_has_frag_list(skb);
3677 }
3678 
3679 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3680 {
3681         skb->queue_mapping = queue_mapping;
3682 }
3683 
3684 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3685 {
3686         return skb->queue_mapping;
3687 }
3688 
3689 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3690 {
3691         to->queue_mapping = from->queue_mapping;
3692 }
3693 
3694 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3695 {
3696         skb->queue_mapping = rx_queue + 1;
3697 }
3698 
3699 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3700 {
3701         return skb->queue_mapping - 1;
3702 }
3703 
3704 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3705 {
3706         return skb->queue_mapping != 0;
3707 }
3708 
3709 static inline void skb_set_dst_pending_confirm(struct sk_buff *skb, u32 val)
3710 {
3711         skb->dst_pending_confirm = val;
3712 }
3713 
3714 static inline bool skb_get_dst_pending_confirm(const struct sk_buff *skb)
3715 {
3716         return skb->dst_pending_confirm != 0;
3717 }
3718 
3719 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3720 {
3721 #ifdef CONFIG_XFRM
3722         return skb->sp;
3723 #else
3724         return NULL;
3725 #endif
3726 }
3727 
3728 /* Keeps track of mac header offset relative to skb->head.
3729  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3730  * For non-tunnel skb it points to skb_mac_header() and for
3731  * tunnel skb it points to outer mac header.
3732  * Keeps track of level of encapsulation of network headers.
3733  */
3734 struct skb_gso_cb {
3735         union {
3736                 int     mac_offset;
3737                 int     data_offset;
3738         };
3739         int     encap_level;
3740         __wsum  csum;
3741         __u16   csum_start;
3742 };
3743 #define SKB_SGO_CB_OFFSET       32
3744 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
3745 
3746 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3747 {
3748         return (skb_mac_header(inner_skb) - inner_skb->head) -
3749                 SKB_GSO_CB(inner_skb)->mac_offset;
3750 }
3751 
3752 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3753 {
3754         int new_headroom, headroom;
3755         int ret;
3756 
3757         headroom = skb_headroom(skb);
3758         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3759         if (ret)
3760                 return ret;
3761 
3762         new_headroom = skb_headroom(skb);
3763         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3764         return 0;
3765 }
3766 
3767 static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
3768 {
3769         /* Do not update partial checksums if remote checksum is enabled. */
3770         if (skb->remcsum_offload)
3771                 return;
3772 
3773         SKB_GSO_CB(skb)->csum = res;
3774         SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
3775 }
3776 
3777 /* Compute the checksum for a gso segment. First compute the checksum value
3778  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3779  * then add in skb->csum (checksum from csum_start to end of packet).
3780  * skb->csum and csum_start are then updated to reflect the checksum of the
3781  * resultant packet starting from the transport header-- the resultant checksum
3782  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3783  * header.
3784  */
3785 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3786 {
3787         unsigned char *csum_start = skb_transport_header(skb);
3788         int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
3789         __wsum partial = SKB_GSO_CB(skb)->csum;
3790 
3791         SKB_GSO_CB(skb)->csum = res;
3792         SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
3793 
3794         return csum_fold(csum_partial(csum_start, plen, partial));
3795 }
3796 
3797 static inline bool skb_is_gso(const struct sk_buff *skb)
3798 {
3799         return skb_shinfo(skb)->gso_size;
3800 }
3801 
3802 /* Note: Should be called only if skb_is_gso(skb) is true */
3803 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3804 {
3805         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3806 }
3807 
3808 static inline void skb_gso_reset(struct sk_buff *skb)
3809 {
3810         skb_shinfo(skb)->gso_size = 0;
3811         skb_shinfo(skb)->gso_segs = 0;
3812         skb_shinfo(skb)->gso_type = 0;
3813 }
3814 
3815 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3816 
3817 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3818 {
3819         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3820          * wanted then gso_type will be set. */
3821         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3822 
3823         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3824             unlikely(shinfo->gso_type == 0)) {
3825                 __skb_warn_lro_forwarding(skb);
3826                 return true;
3827         }
3828         return false;
3829 }
3830 
3831 static inline void skb_forward_csum(struct sk_buff *skb)
3832 {
3833         /* Unfortunately we don't support this one.  Any brave souls? */
3834         if (skb->ip_summed == CHECKSUM_COMPLETE)
3835                 skb->ip_summed = CHECKSUM_NONE;
3836 }
3837 
3838 /**
3839  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3840  * @skb: skb to check
3841  *
3842  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3843  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3844  * use this helper, to document places where we make this assertion.
3845  */
3846 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3847 {
3848 #ifdef DEBUG
3849         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3850 #endif
3851 }
3852 
3853 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3854 
3855 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3856 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
3857                                      unsigned int transport_len,
3858                                      __sum16(*skb_chkf)(struct sk_buff *skb));
3859 
3860 /**
3861  * skb_head_is_locked - Determine if the skb->head is locked down
3862  * @skb: skb to check
3863  *
3864  * The head on skbs build around a head frag can be removed if they are
3865  * not cloned.  This function returns true if the skb head is locked down
3866  * due to either being allocated via kmalloc, or by being a clone with
3867  * multiple references to the head.
3868  */
3869 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3870 {
3871         return !skb->head_frag || skb_cloned(skb);
3872 }
3873 
3874 /**
3875  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3876  *
3877  * @skb: GSO skb
3878  *
3879  * skb_gso_network_seglen is used to determine the real size of the
3880  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3881  *
3882  * The MAC/L2 header is not accounted for.
3883  */
3884 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3885 {
3886         unsigned int hdr_len = skb_transport_header(skb) -
3887                                skb_network_header(skb);
3888         return hdr_len + skb_gso_transport_seglen(skb);
3889 }
3890 
3891 /* Local Checksum Offload.
3892  * Compute outer checksum based on the assumption that the
3893  * inner checksum will be offloaded later.
3894  * See Documentation/networking/checksum-offloads.txt for
3895  * explanation of how this works.
3896  * Fill in outer checksum adjustment (e.g. with sum of outer
3897  * pseudo-header) before calling.
3898  * Also ensure that inner checksum is in linear data area.
3899  */
3900 static inline __wsum lco_csum(struct sk_buff *skb)
3901 {
3902         unsigned char *csum_start = skb_checksum_start(skb);
3903         unsigned char *l4_hdr = skb_transport_header(skb);
3904         __wsum partial;
3905 
3906         /* Start with complement of inner checksum adjustment */
3907         partial = ~csum_unfold(*(__force __sum16 *)(csum_start +
3908                                                     skb->csum_offset));
3909 
3910         /* Add in checksum of our headers (incl. outer checksum
3911          * adjustment filled in by caller) and return result.
3912          */
3913         return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
3914 }
3915 
3916 #endif  /* __KERNEL__ */
3917 #endif  /* _LINUX_SKBUFF_H */
3918 

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