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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/compiler.h>
 19 #include <linux/time.h>
 20 #include <linux/bug.h>
 21 #include <linux/cache.h>
 22 #include <linux/rbtree.h>
 23 #include <linux/socket.h>
 24 #include <linux/refcount.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  *     FCOE: indicates the CRC in FC frame has been validated.
113  *
114  *   skb->csum_level indicates the number of consecutive checksums found in
115  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
116  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
117  *   and a device is able to verify the checksums for UDP (possibly zero),
118  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
119  *   two. If the device were only able to verify the UDP checksum and not
120  *   GRE, either because it doesn't support GRE checksum of because GRE
121  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
122  *   not considered in this case).
123  *
124  * CHECKSUM_COMPLETE:
125  *
126  *   This is the most generic way. The device supplied checksum of the _whole_
127  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
128  *   hardware doesn't need to parse L3/L4 headers to implement this.
129  *
130  *   Notes:
131  *   - Even if device supports only some protocols, but is able to produce
132  *     skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
133  *   - CHECKSUM_COMPLETE is not applicable to SCTP and FCoE protocols.
134  *
135  * CHECKSUM_PARTIAL:
136  *
137  *   A checksum is set up to be offloaded to a device as described in the
138  *   output description for CHECKSUM_PARTIAL. This may occur on a packet
139  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
140  *   on the same host, or it may be set in the input path in GRO or remote
141  *   checksum offload. For the purposes of checksum verification, the checksum
142  *   referred to by skb->csum_start + skb->csum_offset and any preceding
143  *   checksums in the packet are considered verified. Any checksums in the
144  *   packet that are after the checksum being offloaded are not considered to
145  *   be verified.
146  *
147  * C. Checksumming on transmit for non-GSO. The stack requests checksum offload
148  *    in the skb->ip_summed for a packet. Values are:
149  *
150  * CHECKSUM_PARTIAL:
151  *
152  *   The driver is required to checksum the packet as seen by hard_start_xmit()
153  *   from skb->csum_start up to the end, and to record/write the checksum at
154  *   offset skb->csum_start + skb->csum_offset. A driver may verify that the
155  *   csum_start and csum_offset values are valid values given the length and
156  *   offset of the packet, however they should not attempt to validate that the
157  *   checksum refers to a legitimate transport layer checksum-- it is the
158  *   purview of the stack to validate that csum_start and csum_offset are set
159  *   correctly.
160  *
161  *   When the stack requests checksum offload for a packet, the driver MUST
162  *   ensure that the checksum is set correctly. A driver can either offload the
163  *   checksum calculation to the device, or call skb_checksum_help (in the case
164  *   that the device does not support offload for a particular checksum).
165  *
166  *   NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
167  *   NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
168  *   checksum offload capability.
169  *   skb_csum_hwoffload_help() can be called to resolve CHECKSUM_PARTIAL based
170  *   on network device checksumming capabilities: if a packet does not match
171  *   them, skb_checksum_help or skb_crc32c_help (depending on the value of
172  *   csum_not_inet, see item D.) 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 set csum_start and csum_offset accordingly, set ip_summed to
193  *     CHECKSUM_PARTIAL and set csum_not_inet to 1, to provide an indication in
194  *     the skbuff that the CHECKSUM_PARTIAL refers to CRC32c.
195  *     A driver that supports both IP checksum offload and SCTP CRC32c offload
196  *     must verify which offload is configured for a packet by testing the
197  *     value of skb->csum_not_inet; skb_crc32c_csum_help is provided to resolve
198  *     CHECKSUM_PARTIAL on skbs where csum_not_inet is set to 1.
199  *
200  *   NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
201  *     offloading the FCOE CRC in a packet. To perform this offload the stack
202  *     will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
203  *     accordingly. Note the there is no indication in the skbuff that the
204  *     CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports
205  *     both IP checksum offload and FCOE CRC offload must verify which offload
206  *     is configured for a packet presumably by inspecting packet headers.
207  *
208  * E. Checksumming on output with GSO.
209  *
210  * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload
211  * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the
212  * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as
213  * part of the GSO operation is implied. If a checksum is being offloaded
214  * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset
215  * are set to refer to the outermost checksum being offload (two offloaded
216  * checksums are possible with UDP encapsulation).
217  */
218 
219 /* Don't change this without changing skb_csum_unnecessary! */
220 #define CHECKSUM_NONE           0
221 #define CHECKSUM_UNNECESSARY    1
222 #define CHECKSUM_COMPLETE       2
223 #define CHECKSUM_PARTIAL        3
224 
225 /* Maximum value in skb->csum_level */
226 #define SKB_MAX_CSUM_LEVEL      3
227 
228 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
229 #define SKB_WITH_OVERHEAD(X)    \
230         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
231 #define SKB_MAX_ORDER(X, ORDER) \
232         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
233 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
234 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
235 
236 /* return minimum truesize of one skb containing X bytes of data */
237 #define SKB_TRUESIZE(X) ((X) +                                          \
238                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
239                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
240 
241 struct net_device;
242 struct scatterlist;
243 struct pipe_inode_info;
244 struct iov_iter;
245 struct napi_struct;
246 struct bpf_prog;
247 union bpf_attr;
248 struct skb_ext;
249 
250 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
251 struct nf_conntrack {
252         atomic_t use;
253 };
254 #endif
255 
256 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
257 struct nf_bridge_info {
258         enum {
259                 BRNF_PROTO_UNCHANGED,
260                 BRNF_PROTO_8021Q,
261                 BRNF_PROTO_PPPOE
262         } orig_proto:8;
263         u8                      pkt_otherhost:1;
264         u8                      in_prerouting:1;
265         u8                      bridged_dnat:1;
266         __u16                   frag_max_size;
267         struct net_device       *physindev;
268 
269         /* always valid & non-NULL from FORWARD on, for physdev match */
270         struct net_device       *physoutdev;
271         union {
272                 /* prerouting: detect dnat in orig/reply direction */
273                 __be32          ipv4_daddr;
274                 struct in6_addr ipv6_daddr;
275 
276                 /* after prerouting + nat detected: store original source
277                  * mac since neigh resolution overwrites it, only used while
278                  * skb is out in neigh layer.
279                  */
280                 char neigh_header[8];
281         };
282 };
283 #endif
284 
285 struct sk_buff_head {
286         /* These two members must be first. */
287         struct sk_buff  *next;
288         struct sk_buff  *prev;
289 
290         __u32           qlen;
291         spinlock_t      lock;
292 };
293 
294 struct sk_buff;
295 
296 /* To allow 64K frame to be packed as single skb without frag_list we
297  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
298  * buffers which do not start on a page boundary.
299  *
300  * Since GRO uses frags we allocate at least 16 regardless of page
301  * size.
302  */
303 #if (65536/PAGE_SIZE + 1) < 16
304 #define MAX_SKB_FRAGS 16UL
305 #else
306 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
307 #endif
308 extern int sysctl_max_skb_frags;
309 
310 /* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
311  * segment using its current segmentation instead.
312  */
313 #define GSO_BY_FRAGS    0xFFFF
314 
315 typedef struct skb_frag_struct skb_frag_t;
316 
317 struct skb_frag_struct {
318         struct {
319                 struct page *p;
320         } page;
321 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
322         __u32 page_offset;
323         __u32 size;
324 #else
325         __u16 page_offset;
326         __u16 size;
327 #endif
328 };
329 
330 /**
331  * skb_frag_size - Returns the size of a skb fragment
332  * @frag: skb fragment
333  */
334 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
335 {
336         return frag->size;
337 }
338 
339 /**
340  * skb_frag_size_set - Sets the size of a skb fragment
341  * @frag: skb fragment
342  * @size: size of fragment
343  */
344 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
345 {
346         frag->size = size;
347 }
348 
349 /**
350  * skb_frag_size_add - Incrementes the size of a skb fragment by %delta
351  * @frag: skb fragment
352  * @delta: value to add
353  */
354 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
355 {
356         frag->size += delta;
357 }
358 
359 /**
360  * skb_frag_size_sub - Decrements the size of a skb fragment by %delta
361  * @frag: skb fragment
362  * @delta: value to subtract
363  */
364 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
365 {
366         frag->size -= delta;
367 }
368 
369 /**
370  * skb_frag_must_loop - Test if %p is a high memory page
371  * @p: fragment's page
372  */
373 static inline bool skb_frag_must_loop(struct page *p)
374 {
375 #if defined(CONFIG_HIGHMEM)
376         if (PageHighMem(p))
377                 return true;
378 #endif
379         return false;
380 }
381 
382 /**
383  *      skb_frag_foreach_page - loop over pages in a fragment
384  *
385  *      @f:             skb frag to operate on
386  *      @f_off:         offset from start of f->page.p
387  *      @f_len:         length from f_off to loop over
388  *      @p:             (temp var) current page
389  *      @p_off:         (temp var) offset from start of current page,
390  *                                 non-zero only on first page.
391  *      @p_len:         (temp var) length in current page,
392  *                                 < PAGE_SIZE only on first and last page.
393  *      @copied:        (temp var) length so far, excluding current p_len.
394  *
395  *      A fragment can hold a compound page, in which case per-page
396  *      operations, notably kmap_atomic, must be called for each
397  *      regular page.
398  */
399 #define skb_frag_foreach_page(f, f_off, f_len, p, p_off, p_len, copied) \
400         for (p = skb_frag_page(f) + ((f_off) >> PAGE_SHIFT),            \
401              p_off = (f_off) & (PAGE_SIZE - 1),                         \
402              p_len = skb_frag_must_loop(p) ?                            \
403              min_t(u32, f_len, PAGE_SIZE - p_off) : f_len,              \
404              copied = 0;                                                \
405              copied < f_len;                                            \
406              copied += p_len, p++, p_off = 0,                           \
407              p_len = min_t(u32, f_len - copied, PAGE_SIZE))             \
408 
409 #define HAVE_HW_TIME_STAMP
410 
411 /**
412  * struct skb_shared_hwtstamps - hardware time stamps
413  * @hwtstamp:   hardware time stamp transformed into duration
414  *              since arbitrary point in time
415  *
416  * Software time stamps generated by ktime_get_real() are stored in
417  * skb->tstamp.
418  *
419  * hwtstamps can only be compared against other hwtstamps from
420  * the same device.
421  *
422  * This structure is attached to packets as part of the
423  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
424  */
425 struct skb_shared_hwtstamps {
426         ktime_t hwtstamp;
427 };
428 
429 /* Definitions for tx_flags in struct skb_shared_info */
430 enum {
431         /* generate hardware time stamp */
432         SKBTX_HW_TSTAMP = 1 << 0,
433 
434         /* generate software time stamp when queueing packet to NIC */
435         SKBTX_SW_TSTAMP = 1 << 1,
436 
437         /* device driver is going to provide hardware time stamp */
438         SKBTX_IN_PROGRESS = 1 << 2,
439 
440         /* device driver supports TX zero-copy buffers */
441         SKBTX_DEV_ZEROCOPY = 1 << 3,
442 
443         /* generate wifi status information (where possible) */
444         SKBTX_WIFI_STATUS = 1 << 4,
445 
446         /* This indicates at least one fragment might be overwritten
447          * (as in vmsplice(), sendfile() ...)
448          * If we need to compute a TX checksum, we'll need to copy
449          * all frags to avoid possible bad checksum
450          */
451         SKBTX_SHARED_FRAG = 1 << 5,
452 
453         /* generate software time stamp when entering packet scheduling */
454         SKBTX_SCHED_TSTAMP = 1 << 6,
455 };
456 
457 #define SKBTX_ZEROCOPY_FRAG     (SKBTX_DEV_ZEROCOPY | SKBTX_SHARED_FRAG)
458 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
459                                  SKBTX_SCHED_TSTAMP)
460 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
461 
462 /*
463  * The callback notifies userspace to release buffers when skb DMA is done in
464  * lower device, the skb last reference should be 0 when calling this.
465  * The zerocopy_success argument is true if zero copy transmit occurred,
466  * false on data copy or out of memory error caused by data copy attempt.
467  * The ctx field is used to track device context.
468  * The desc field is used to track userspace buffer index.
469  */
470 struct ubuf_info {
471         void (*callback)(struct ubuf_info *, bool zerocopy_success);
472         union {
473                 struct {
474                         unsigned long desc;
475                         void *ctx;
476                 };
477                 struct {
478                         u32 id;
479                         u16 len;
480                         u16 zerocopy:1;
481                         u32 bytelen;
482                 };
483         };
484         refcount_t refcnt;
485 
486         struct mmpin {
487                 struct user_struct *user;
488                 unsigned int num_pg;
489         } mmp;
490 };
491 
492 #define skb_uarg(SKB)   ((struct ubuf_info *)(skb_shinfo(SKB)->destructor_arg))
493 
494 int mm_account_pinned_pages(struct mmpin *mmp, size_t size);
495 void mm_unaccount_pinned_pages(struct mmpin *mmp);
496 
497 struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size);
498 struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
499                                         struct ubuf_info *uarg);
500 
501 static inline void sock_zerocopy_get(struct ubuf_info *uarg)
502 {
503         refcount_inc(&uarg->refcnt);
504 }
505 
506 void sock_zerocopy_put(struct ubuf_info *uarg);
507 void sock_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
508 
509 void sock_zerocopy_callback(struct ubuf_info *uarg, bool success);
510 
511 int skb_zerocopy_iter_dgram(struct sk_buff *skb, struct msghdr *msg, int len);
512 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
513                              struct msghdr *msg, int len,
514                              struct ubuf_info *uarg);
515 
516 /* This data is invariant across clones and lives at
517  * the end of the header data, ie. at skb->end.
518  */
519 struct skb_shared_info {
520         __u8            __unused;
521         __u8            meta_len;
522         __u8            nr_frags;
523         __u8            tx_flags;
524         unsigned short  gso_size;
525         /* Warning: this field is not always filled in (UFO)! */
526         unsigned short  gso_segs;
527         struct sk_buff  *frag_list;
528         struct skb_shared_hwtstamps hwtstamps;
529         unsigned int    gso_type;
530         u32             tskey;
531 
532         /*
533          * Warning : all fields before dataref are cleared in __alloc_skb()
534          */
535         atomic_t        dataref;
536 
537         /* Intermediate layers must ensure that destructor_arg
538          * remains valid until skb destructor */
539         void *          destructor_arg;
540 
541         /* must be last field, see pskb_expand_head() */
542         skb_frag_t      frags[MAX_SKB_FRAGS];
543 };
544 
545 /* We divide dataref into two halves.  The higher 16 bits hold references
546  * to the payload part of skb->data.  The lower 16 bits hold references to
547  * the entire skb->data.  A clone of a headerless skb holds the length of
548  * the header in skb->hdr_len.
549  *
550  * All users must obey the rule that the skb->data reference count must be
551  * greater than or equal to the payload reference count.
552  *
553  * Holding a reference to the payload part means that the user does not
554  * care about modifications to the header part of skb->data.
555  */
556 #define SKB_DATAREF_SHIFT 16
557 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
558 
559 
560 enum {
561         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
562         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
563         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
564 };
565 
566 enum {
567         SKB_GSO_TCPV4 = 1 << 0,
568 
569         /* This indicates the skb is from an untrusted source. */
570         SKB_GSO_DODGY = 1 << 1,
571 
572         /* This indicates the tcp segment has CWR set. */
573         SKB_GSO_TCP_ECN = 1 << 2,
574 
575         SKB_GSO_TCP_FIXEDID = 1 << 3,
576 
577         SKB_GSO_TCPV6 = 1 << 4,
578 
579         SKB_GSO_FCOE = 1 << 5,
580 
581         SKB_GSO_GRE = 1 << 6,
582 
583         SKB_GSO_GRE_CSUM = 1 << 7,
584 
585         SKB_GSO_IPXIP4 = 1 << 8,
586 
587         SKB_GSO_IPXIP6 = 1 << 9,
588 
589         SKB_GSO_UDP_TUNNEL = 1 << 10,
590 
591         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
592 
593         SKB_GSO_PARTIAL = 1 << 12,
594 
595         SKB_GSO_TUNNEL_REMCSUM = 1 << 13,
596 
597         SKB_GSO_SCTP = 1 << 14,
598 
599         SKB_GSO_ESP = 1 << 15,
600 
601         SKB_GSO_UDP = 1 << 16,
602 
603         SKB_GSO_UDP_L4 = 1 << 17,
604 };
605 
606 #if BITS_PER_LONG > 32
607 #define NET_SKBUFF_DATA_USES_OFFSET 1
608 #endif
609 
610 #ifdef NET_SKBUFF_DATA_USES_OFFSET
611 typedef unsigned int sk_buff_data_t;
612 #else
613 typedef unsigned char *sk_buff_data_t;
614 #endif
615 
616 /**
617  *      struct sk_buff - socket buffer
618  *      @next: Next buffer in list
619  *      @prev: Previous buffer in list
620  *      @tstamp: Time we arrived/left
621  *      @rbnode: RB tree node, alternative to next/prev for netem/tcp
622  *      @sk: Socket we are owned by
623  *      @dev: Device we arrived on/are leaving by
624  *      @cb: Control buffer. Free for use by every layer. Put private vars here
625  *      @_skb_refdst: destination entry (with norefcount bit)
626  *      @sp: the security path, used for xfrm
627  *      @len: Length of actual data
628  *      @data_len: Data length
629  *      @mac_len: Length of link layer header
630  *      @hdr_len: writable header length of cloned skb
631  *      @csum: Checksum (must include start/offset pair)
632  *      @csum_start: Offset from skb->head where checksumming should start
633  *      @csum_offset: Offset from csum_start where checksum should be stored
634  *      @priority: Packet queueing priority
635  *      @ignore_df: allow local fragmentation
636  *      @cloned: Head may be cloned (check refcnt to be sure)
637  *      @ip_summed: Driver fed us an IP checksum
638  *      @nohdr: Payload reference only, must not modify header
639  *      @pkt_type: Packet class
640  *      @fclone: skbuff clone status
641  *      @ipvs_property: skbuff is owned by ipvs
642  *      @offload_fwd_mark: Packet was L2-forwarded in hardware
643  *      @offload_l3_fwd_mark: Packet was L3-forwarded in hardware
644  *      @tc_skip_classify: do not classify packet. set by IFB device
645  *      @tc_at_ingress: used within tc_classify to distinguish in/egress
646  *      @tc_redirected: packet was redirected by a tc action
647  *      @tc_from_ingress: if tc_redirected, tc_at_ingress at time of redirect
648  *      @peeked: this packet has been seen already, so stats have been
649  *              done for it, don't do them again
650  *      @nf_trace: netfilter packet trace flag
651  *      @protocol: Packet protocol from driver
652  *      @destructor: Destruct function
653  *      @tcp_tsorted_anchor: list structure for TCP (tp->tsorted_sent_queue)
654  *      @_nfct: Associated connection, if any (with nfctinfo bits)
655  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
656  *      @skb_iif: ifindex of device we arrived on
657  *      @tc_index: Traffic control index
658  *      @hash: the packet hash
659  *      @queue_mapping: Queue mapping for multiqueue devices
660  *      @xmit_more: More SKBs are pending for this queue
661  *      @pfmemalloc: skbuff was allocated from PFMEMALLOC reserves
662  *      @active_extensions: active extensions (skb_ext_id types)
663  *      @ndisc_nodetype: router type (from link layer)
664  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
665  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
666  *              ports.
667  *      @sw_hash: indicates hash was computed in software stack
668  *      @wifi_acked_valid: wifi_acked was set
669  *      @wifi_acked: whether frame was acked on wifi or not
670  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
671  *      @csum_not_inet: use CRC32c to resolve CHECKSUM_PARTIAL
672  *      @dst_pending_confirm: need to confirm neighbour
673  *      @decrypted: Decrypted SKB
674  *      @napi_id: id of the NAPI struct this skb came from
675  *      @secmark: security marking
676  *      @mark: Generic packet mark
677  *      @vlan_proto: vlan encapsulation protocol
678  *      @vlan_tci: vlan tag control information
679  *      @inner_protocol: Protocol (encapsulation)
680  *      @inner_transport_header: Inner transport layer header (encapsulation)
681  *      @inner_network_header: Network layer header (encapsulation)
682  *      @inner_mac_header: Link layer header (encapsulation)
683  *      @transport_header: Transport layer header
684  *      @network_header: Network layer header
685  *      @mac_header: Link layer header
686  *      @tail: Tail pointer
687  *      @end: End pointer
688  *      @head: Head of buffer
689  *      @data: Data head pointer
690  *      @truesize: Buffer size
691  *      @users: User count - see {datagram,tcp}.c
692  *      @extensions: allocated extensions, valid if active_extensions is nonzero
693  */
694 
695 struct sk_buff {
696         union {
697                 struct {
698                         /* These two members must be first. */
699                         struct sk_buff          *next;
700                         struct sk_buff          *prev;
701 
702                         union {
703                                 struct net_device       *dev;
704                                 /* Some protocols might use this space to store information,
705                                  * while device pointer would be NULL.
706                                  * UDP receive path is one user.
707                                  */
708                                 unsigned long           dev_scratch;
709                         };
710                 };
711                 struct rb_node          rbnode; /* used in netem, ip4 defrag, and tcp stack */
712                 struct list_head        list;
713         };
714 
715         union {
716                 struct sock             *sk;
717                 int                     ip_defrag_offset;
718         };
719 
720         union {
721                 ktime_t         tstamp;
722                 u64             skb_mstamp_ns; /* earliest departure time */
723         };
724         /*
725          * This is the control buffer. It is free to use for every
726          * layer. Please put your private variables there. If you
727          * want to keep them across layers you have to do a skb_clone()
728          * first. This is owned by whoever has the skb queued ATM.
729          */
730         char                    cb[48] __aligned(8);
731 
732         union {
733                 struct {
734                         unsigned long   _skb_refdst;
735                         void            (*destructor)(struct sk_buff *skb);
736                 };
737                 struct list_head        tcp_tsorted_anchor;
738         };
739 
740 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
741         unsigned long            _nfct;
742 #endif
743         unsigned int            len,
744                                 data_len;
745         __u16                   mac_len,
746                                 hdr_len;
747 
748         /* Following fields are _not_ copied in __copy_skb_header()
749          * Note that queue_mapping is here mostly to fill a hole.
750          */
751         __u16                   queue_mapping;
752 
753 /* if you move cloned around you also must adapt those constants */
754 #ifdef __BIG_ENDIAN_BITFIELD
755 #define CLONED_MASK     (1 << 7)
756 #else
757 #define CLONED_MASK     1
758 #endif
759 #define CLONED_OFFSET()         offsetof(struct sk_buff, __cloned_offset)
760 
761         __u8                    __cloned_offset[0];
762         __u8                    cloned:1,
763                                 nohdr:1,
764                                 fclone:2,
765                                 peeked:1,
766                                 head_frag:1,
767                                 xmit_more:1,
768                                 pfmemalloc:1;
769 #ifdef CONFIG_SKB_EXTENSIONS
770         __u8                    active_extensions;
771 #endif
772         /* fields enclosed in headers_start/headers_end are copied
773          * using a single memcpy() in __copy_skb_header()
774          */
775         /* private: */
776         __u32                   headers_start[0];
777         /* public: */
778 
779 /* if you move pkt_type around you also must adapt those constants */
780 #ifdef __BIG_ENDIAN_BITFIELD
781 #define PKT_TYPE_MAX    (7 << 5)
782 #else
783 #define PKT_TYPE_MAX    7
784 #endif
785 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
786 
787         __u8                    __pkt_type_offset[0];
788         __u8                    pkt_type:3;
789         __u8                    ignore_df:1;
790         __u8                    nf_trace:1;
791         __u8                    ip_summed:2;
792         __u8                    ooo_okay:1;
793 
794         __u8                    l4_hash:1;
795         __u8                    sw_hash:1;
796         __u8                    wifi_acked_valid:1;
797         __u8                    wifi_acked:1;
798         __u8                    no_fcs:1;
799         /* Indicates the inner headers are valid in the skbuff. */
800         __u8                    encapsulation:1;
801         __u8                    encap_hdr_csum:1;
802         __u8                    csum_valid:1;
803 
804 #ifdef __BIG_ENDIAN_BITFIELD
805 #define PKT_VLAN_PRESENT_BIT    7
806 #else
807 #define PKT_VLAN_PRESENT_BIT    0
808 #endif
809 #define PKT_VLAN_PRESENT_OFFSET()       offsetof(struct sk_buff, __pkt_vlan_present_offset)
810         __u8                    __pkt_vlan_present_offset[0];
811         __u8                    vlan_present:1;
812         __u8                    csum_complete_sw:1;
813         __u8                    csum_level:2;
814         __u8                    csum_not_inet:1;
815         __u8                    dst_pending_confirm:1;
816 #ifdef CONFIG_IPV6_NDISC_NODETYPE
817         __u8                    ndisc_nodetype:2;
818 #endif
819 
820         __u8                    ipvs_property:1;
821         __u8                    inner_protocol_type:1;
822         __u8                    remcsum_offload:1;
823 #ifdef CONFIG_NET_SWITCHDEV
824         __u8                    offload_fwd_mark:1;
825         __u8                    offload_l3_fwd_mark:1;
826 #endif
827 #ifdef CONFIG_NET_CLS_ACT
828         __u8                    tc_skip_classify:1;
829         __u8                    tc_at_ingress:1;
830         __u8                    tc_redirected:1;
831         __u8                    tc_from_ingress:1;
832 #endif
833 #ifdef CONFIG_TLS_DEVICE
834         __u8                    decrypted:1;
835 #endif
836 
837 #ifdef CONFIG_NET_SCHED
838         __u16                   tc_index;       /* traffic control index */
839 #endif
840 
841         union {
842                 __wsum          csum;
843                 struct {
844                         __u16   csum_start;
845                         __u16   csum_offset;
846                 };
847         };
848         __u32                   priority;
849         int                     skb_iif;
850         __u32                   hash;
851         __be16                  vlan_proto;
852         __u16                   vlan_tci;
853 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
854         union {
855                 unsigned int    napi_id;
856                 unsigned int    sender_cpu;
857         };
858 #endif
859 #ifdef CONFIG_NETWORK_SECMARK
860         __u32           secmark;
861 #endif
862 
863         union {
864                 __u32           mark;
865                 __u32           reserved_tailroom;
866         };
867 
868         union {
869                 __be16          inner_protocol;
870                 __u8            inner_ipproto;
871         };
872 
873         __u16                   inner_transport_header;
874         __u16                   inner_network_header;
875         __u16                   inner_mac_header;
876 
877         __be16                  protocol;
878         __u16                   transport_header;
879         __u16                   network_header;
880         __u16                   mac_header;
881 
882         /* private: */
883         __u32                   headers_end[0];
884         /* public: */
885 
886         /* These elements must be at the end, see alloc_skb() for details.  */
887         sk_buff_data_t          tail;
888         sk_buff_data_t          end;
889         unsigned char           *head,
890                                 *data;
891         unsigned int            truesize;
892         refcount_t              users;
893 
894 #ifdef CONFIG_SKB_EXTENSIONS
895         /* only useable after checking ->active_extensions != 0 */
896         struct skb_ext          *extensions;
897 #endif
898 };
899 
900 #ifdef __KERNEL__
901 /*
902  *      Handling routines are only of interest to the kernel
903  */
904 
905 #define SKB_ALLOC_FCLONE        0x01
906 #define SKB_ALLOC_RX            0x02
907 #define SKB_ALLOC_NAPI          0x04
908 
909 /**
910  * skb_pfmemalloc - Test if the skb was allocated from PFMEMALLOC reserves
911  * @skb: buffer
912  */
913 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
914 {
915         return unlikely(skb->pfmemalloc);
916 }
917 
918 /*
919  * skb might have a dst pointer attached, refcounted or not.
920  * _skb_refdst low order bit is set if refcount was _not_ taken
921  */
922 #define SKB_DST_NOREF   1UL
923 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
924 
925 #define SKB_NFCT_PTRMASK        ~(7UL)
926 /**
927  * skb_dst - returns skb dst_entry
928  * @skb: buffer
929  *
930  * Returns skb dst_entry, regardless of reference taken or not.
931  */
932 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
933 {
934         /* If refdst was not refcounted, check we still are in a
935          * rcu_read_lock section
936          */
937         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
938                 !rcu_read_lock_held() &&
939                 !rcu_read_lock_bh_held());
940         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
941 }
942 
943 /**
944  * skb_dst_set - sets skb dst
945  * @skb: buffer
946  * @dst: dst entry
947  *
948  * Sets skb dst, assuming a reference was taken on dst and should
949  * be released by skb_dst_drop()
950  */
951 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
952 {
953         skb->_skb_refdst = (unsigned long)dst;
954 }
955 
956 /**
957  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
958  * @skb: buffer
959  * @dst: dst entry
960  *
961  * Sets skb dst, assuming a reference was not taken on dst.
962  * If dst entry is cached, we do not take reference and dst_release
963  * will be avoided by refdst_drop. If dst entry is not cached, we take
964  * reference, so that last dst_release can destroy the dst immediately.
965  */
966 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
967 {
968         WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
969         skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
970 }
971 
972 /**
973  * skb_dst_is_noref - Test if skb dst isn't refcounted
974  * @skb: buffer
975  */
976 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
977 {
978         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
979 }
980 
981 /**
982  * skb_rtable - Returns the skb &rtable
983  * @skb: buffer
984  */
985 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
986 {
987         return (struct rtable *)skb_dst(skb);
988 }
989 
990 /* For mangling skb->pkt_type from user space side from applications
991  * such as nft, tc, etc, we only allow a conservative subset of
992  * possible pkt_types to be set.
993 */
994 static inline bool skb_pkt_type_ok(u32 ptype)
995 {
996         return ptype <= PACKET_OTHERHOST;
997 }
998 
999 /**
1000  * skb_napi_id - Returns the skb's NAPI id
1001  * @skb: buffer
1002  */
1003 static inline unsigned int skb_napi_id(const struct sk_buff *skb)
1004 {
1005 #ifdef CONFIG_NET_RX_BUSY_POLL
1006         return skb->napi_id;
1007 #else
1008         return 0;
1009 #endif
1010 }
1011 
1012 /**
1013  * skb_unref - decrement the skb's reference count
1014  * @skb: buffer
1015  *
1016  * Returns true if we can free the skb.
1017  */
1018 static inline bool skb_unref(struct sk_buff *skb)
1019 {
1020         if (unlikely(!skb))
1021                 return false;
1022         if (likely(refcount_read(&skb->users) == 1))
1023                 smp_rmb();
1024         else if (likely(!refcount_dec_and_test(&skb->users)))
1025                 return false;
1026 
1027         return true;
1028 }
1029 
1030 void skb_release_head_state(struct sk_buff *skb);
1031 void kfree_skb(struct sk_buff *skb);
1032 void kfree_skb_list(struct sk_buff *segs);
1033 void skb_tx_error(struct sk_buff *skb);
1034 void consume_skb(struct sk_buff *skb);
1035 void __consume_stateless_skb(struct sk_buff *skb);
1036 void  __kfree_skb(struct sk_buff *skb);
1037 extern struct kmem_cache *skbuff_head_cache;
1038 
1039 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
1040 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
1041                       bool *fragstolen, int *delta_truesize);
1042 
1043 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
1044                             int node);
1045 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
1046 struct sk_buff *build_skb(void *data, unsigned int frag_size);
1047 
1048 /**
1049  * alloc_skb - allocate a network buffer
1050  * @size: size to allocate
1051  * @priority: allocation mask
1052  *
1053  * This function is a convenient wrapper around __alloc_skb().
1054  */
1055 static inline struct sk_buff *alloc_skb(unsigned int size,
1056                                         gfp_t priority)
1057 {
1058         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
1059 }
1060 
1061 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
1062                                      unsigned long data_len,
1063                                      int max_page_order,
1064                                      int *errcode,
1065                                      gfp_t gfp_mask);
1066 
1067 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
1068 struct sk_buff_fclones {
1069         struct sk_buff  skb1;
1070 
1071         struct sk_buff  skb2;
1072 
1073         refcount_t      fclone_ref;
1074 };
1075 
1076 /**
1077  *      skb_fclone_busy - check if fclone is busy
1078  *      @sk: socket
1079  *      @skb: buffer
1080  *
1081  * Returns true if skb is a fast clone, and its clone is not freed.
1082  * Some drivers call skb_orphan() in their ndo_start_xmit(),
1083  * so we also check that this didnt happen.
1084  */
1085 static inline bool skb_fclone_busy(const struct sock *sk,
1086                                    const struct sk_buff *skb)
1087 {
1088         const struct sk_buff_fclones *fclones;
1089 
1090         fclones = container_of(skb, struct sk_buff_fclones, skb1);
1091 
1092         return skb->fclone == SKB_FCLONE_ORIG &&
1093                refcount_read(&fclones->fclone_ref) > 1 &&
1094                fclones->skb2.sk == sk;
1095 }
1096 
1097 /**
1098  * alloc_skb_fclone - allocate a network buffer from fclone cache
1099  * @size: size to allocate
1100  * @priority: allocation mask
1101  *
1102  * This function is a convenient wrapper around __alloc_skb().
1103  */
1104 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
1105                                                gfp_t priority)
1106 {
1107         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
1108 }
1109 
1110 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
1111 void skb_headers_offset_update(struct sk_buff *skb, int off);
1112 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
1113 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
1114 void skb_copy_header(struct sk_buff *new, const struct sk_buff *old);
1115 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
1116 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1117                                    gfp_t gfp_mask, bool fclone);
1118 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
1119                                           gfp_t gfp_mask)
1120 {
1121         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
1122 }
1123 
1124 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
1125 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
1126                                      unsigned int headroom);
1127 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
1128                                 int newtailroom, gfp_t priority);
1129 int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
1130                                      int offset, int len);
1131 int __must_check skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg,
1132                               int offset, int len);
1133 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
1134 int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error);
1135 
1136 /**
1137  *      skb_pad                 -       zero pad the tail of an skb
1138  *      @skb: buffer to pad
1139  *      @pad: space to pad
1140  *
1141  *      Ensure that a buffer is followed by a padding area that is zero
1142  *      filled. Used by network drivers which may DMA or transfer data
1143  *      beyond the buffer end onto the wire.
1144  *
1145  *      May return error in out of memory cases. The skb is freed on error.
1146  */
1147 static inline int skb_pad(struct sk_buff *skb, int pad)
1148 {
1149         return __skb_pad(skb, pad, true);
1150 }
1151 #define dev_kfree_skb(a)        consume_skb(a)
1152 
1153 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
1154                          int offset, size_t size);
1155 
1156 struct skb_seq_state {
1157         __u32           lower_offset;
1158         __u32           upper_offset;
1159         __u32           frag_idx;
1160         __u32           stepped_offset;
1161         struct sk_buff  *root_skb;
1162         struct sk_buff  *cur_skb;
1163         __u8            *frag_data;
1164 };
1165 
1166 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1167                           unsigned int to, struct skb_seq_state *st);
1168 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1169                           struct skb_seq_state *st);
1170 void skb_abort_seq_read(struct skb_seq_state *st);
1171 
1172 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1173                            unsigned int to, struct ts_config *config);
1174 
1175 /*
1176  * Packet hash types specify the type of hash in skb_set_hash.
1177  *
1178  * Hash types refer to the protocol layer addresses which are used to
1179  * construct a packet's hash. The hashes are used to differentiate or identify
1180  * flows of the protocol layer for the hash type. Hash types are either
1181  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
1182  *
1183  * Properties of hashes:
1184  *
1185  * 1) Two packets in different flows have different hash values
1186  * 2) Two packets in the same flow should have the same hash value
1187  *
1188  * A hash at a higher layer is considered to be more specific. A driver should
1189  * set the most specific hash possible.
1190  *
1191  * A driver cannot indicate a more specific hash than the layer at which a hash
1192  * was computed. For instance an L3 hash cannot be set as an L4 hash.
1193  *
1194  * A driver may indicate a hash level which is less specific than the
1195  * actual layer the hash was computed on. For instance, a hash computed
1196  * at L4 may be considered an L3 hash. This should only be done if the
1197  * driver can't unambiguously determine that the HW computed the hash at
1198  * the higher layer. Note that the "should" in the second property above
1199  * permits this.
1200  */
1201 enum pkt_hash_types {
1202         PKT_HASH_TYPE_NONE,     /* Undefined type */
1203         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
1204         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
1205         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
1206 };
1207 
1208 static inline void skb_clear_hash(struct sk_buff *skb)
1209 {
1210         skb->hash = 0;
1211         skb->sw_hash = 0;
1212         skb->l4_hash = 0;
1213 }
1214 
1215 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
1216 {
1217         if (!skb->l4_hash)
1218                 skb_clear_hash(skb);
1219 }
1220 
1221 static inline void
1222 __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
1223 {
1224         skb->l4_hash = is_l4;
1225         skb->sw_hash = is_sw;
1226         skb->hash = hash;
1227 }
1228 
1229 static inline void
1230 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
1231 {
1232         /* Used by drivers to set hash from HW */
1233         __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
1234 }
1235 
1236 static inline void
1237 __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
1238 {
1239         __skb_set_hash(skb, hash, true, is_l4);
1240 }
1241 
1242 void __skb_get_hash(struct sk_buff *skb);
1243 u32 __skb_get_hash_symmetric(const struct sk_buff *skb);
1244 u32 skb_get_poff(const struct sk_buff *skb);
1245 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
1246                    const struct flow_keys_basic *keys, int hlen);
1247 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
1248                             void *data, int hlen_proto);
1249 
1250 static inline __be32 skb_flow_get_ports(const struct sk_buff *skb,
1251                                         int thoff, u8 ip_proto)
1252 {
1253         return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
1254 }
1255 
1256 void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
1257                              const struct flow_dissector_key *key,
1258                              unsigned int key_count);
1259 
1260 #ifdef CONFIG_NET
1261 int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
1262                                        struct bpf_prog *prog);
1263 
1264 int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
1265 #else
1266 static inline int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
1267                                                      struct bpf_prog *prog)
1268 {
1269         return -EOPNOTSUPP;
1270 }
1271 
1272 static inline int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr)
1273 {
1274         return -EOPNOTSUPP;
1275 }
1276 #endif
1277 
1278 struct bpf_flow_keys;
1279 bool __skb_flow_bpf_dissect(struct bpf_prog *prog,
1280                             const struct sk_buff *skb,
1281                             struct flow_dissector *flow_dissector,
1282                             struct bpf_flow_keys *flow_keys);
1283 bool __skb_flow_dissect(const struct sk_buff *skb,
1284                         struct flow_dissector *flow_dissector,
1285                         void *target_container,
1286                         void *data, __be16 proto, int nhoff, int hlen,
1287                         unsigned int flags);
1288 
1289 static inline bool skb_flow_dissect(const struct sk_buff *skb,
1290                                     struct flow_dissector *flow_dissector,
1291                                     void *target_container, unsigned int flags)
1292 {
1293         return __skb_flow_dissect(skb, flow_dissector, target_container,
1294                                   NULL, 0, 0, 0, flags);
1295 }
1296 
1297 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
1298                                               struct flow_keys *flow,
1299                                               unsigned int flags)
1300 {
1301         memset(flow, 0, sizeof(*flow));
1302         return __skb_flow_dissect(skb, &flow_keys_dissector, flow,
1303                                   NULL, 0, 0, 0, flags);
1304 }
1305 
1306 static inline bool
1307 skb_flow_dissect_flow_keys_basic(const struct sk_buff *skb,
1308                                  struct flow_keys_basic *flow, void *data,
1309                                  __be16 proto, int nhoff, int hlen,
1310                                  unsigned int flags)
1311 {
1312         memset(flow, 0, sizeof(*flow));
1313         return __skb_flow_dissect(skb, &flow_keys_basic_dissector, flow,
1314                                   data, proto, nhoff, hlen, flags);
1315 }
1316 
1317 void
1318 skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
1319                              struct flow_dissector *flow_dissector,
1320                              void *target_container);
1321 
1322 static inline __u32 skb_get_hash(struct sk_buff *skb)
1323 {
1324         if (!skb->l4_hash && !skb->sw_hash)
1325                 __skb_get_hash(skb);
1326 
1327         return skb->hash;
1328 }
1329 
1330 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
1331 {
1332         if (!skb->l4_hash && !skb->sw_hash) {
1333                 struct flow_keys keys;
1334                 __u32 hash = __get_hash_from_flowi6(fl6, &keys);
1335 
1336                 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1337         }
1338 
1339         return skb->hash;
1340 }
1341 
1342 __u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);
1343 
1344 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
1345 {
1346         return skb->hash;
1347 }
1348 
1349 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
1350 {
1351         to->hash = from->hash;
1352         to->sw_hash = from->sw_hash;
1353         to->l4_hash = from->l4_hash;
1354 };
1355 
1356 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1357 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1358 {
1359         return skb->head + skb->end;
1360 }
1361 
1362 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1363 {
1364         return skb->end;
1365 }
1366 #else
1367 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1368 {
1369         return skb->end;
1370 }
1371 
1372 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1373 {
1374         return skb->end - skb->head;
1375 }
1376 #endif
1377 
1378 /* Internal */
1379 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
1380 
1381 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
1382 {
1383         return &skb_shinfo(skb)->hwtstamps;
1384 }
1385 
1386 static inline struct ubuf_info *skb_zcopy(struct sk_buff *skb)
1387 {
1388         bool is_zcopy = skb && skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY;
1389 
1390         return is_zcopy ? skb_uarg(skb) : NULL;
1391 }
1392 
1393 static inline void skb_zcopy_set(struct sk_buff *skb, struct ubuf_info *uarg,
1394                                  bool *have_ref)
1395 {
1396         if (skb && uarg && !skb_zcopy(skb)) {
1397                 if (unlikely(have_ref && *have_ref))
1398                         *have_ref = false;
1399                 else
1400                         sock_zerocopy_get(uarg);
1401                 skb_shinfo(skb)->destructor_arg = uarg;
1402                 skb_shinfo(skb)->tx_flags |= SKBTX_ZEROCOPY_FRAG;
1403         }
1404 }
1405 
1406 static inline void skb_zcopy_set_nouarg(struct sk_buff *skb, void *val)
1407 {
1408         skb_shinfo(skb)->destructor_arg = (void *)((uintptr_t) val | 0x1UL);
1409         skb_shinfo(skb)->tx_flags |= SKBTX_ZEROCOPY_FRAG;
1410 }
1411 
1412 static inline bool skb_zcopy_is_nouarg(struct sk_buff *skb)
1413 {
1414         return (uintptr_t) skb_shinfo(skb)->destructor_arg & 0x1UL;
1415 }
1416 
1417 static inline void *skb_zcopy_get_nouarg(struct sk_buff *skb)
1418 {
1419         return (void *)((uintptr_t) skb_shinfo(skb)->destructor_arg & ~0x1UL);
1420 }
1421 
1422 /* Release a reference on a zerocopy structure */
1423 static inline void skb_zcopy_clear(struct sk_buff *skb, bool zerocopy)
1424 {
1425         struct ubuf_info *uarg = skb_zcopy(skb);
1426 
1427         if (uarg) {
1428                 if (uarg->callback == sock_zerocopy_callback) {
1429                         uarg->zerocopy = uarg->zerocopy && zerocopy;
1430                         sock_zerocopy_put(uarg);
1431                 } else if (!skb_zcopy_is_nouarg(skb)) {
1432                         uarg->callback(uarg, zerocopy);
1433                 }
1434 
1435                 skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
1436         }
1437 }
1438 
1439 /* Abort a zerocopy operation and revert zckey on error in send syscall */
1440 static inline void skb_zcopy_abort(struct sk_buff *skb)
1441 {
1442         struct ubuf_info *uarg = skb_zcopy(skb);
1443 
1444         if (uarg) {
1445                 sock_zerocopy_put_abort(uarg, false);
1446                 skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
1447         }
1448 }
1449 
1450 static inline void skb_mark_not_on_list(struct sk_buff *skb)
1451 {
1452         skb->next = NULL;
1453 }
1454 
1455 static inline void skb_list_del_init(struct sk_buff *skb)
1456 {
1457         __list_del_entry(&skb->list);
1458         skb_mark_not_on_list(skb);
1459 }
1460 
1461 /**
1462  *      skb_queue_empty - check if a queue is empty
1463  *      @list: queue head
1464  *
1465  *      Returns true if the queue is empty, false otherwise.
1466  */
1467 static inline int skb_queue_empty(const struct sk_buff_head *list)
1468 {
1469         return list->next == (const struct sk_buff *) list;
1470 }
1471 
1472 /**
1473  *      skb_queue_is_last - check if skb is the last entry in the queue
1474  *      @list: queue head
1475  *      @skb: buffer
1476  *
1477  *      Returns true if @skb is the last buffer on the list.
1478  */
1479 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1480                                      const struct sk_buff *skb)
1481 {
1482         return skb->next == (const struct sk_buff *) list;
1483 }
1484 
1485 /**
1486  *      skb_queue_is_first - check if skb is the first entry in the queue
1487  *      @list: queue head
1488  *      @skb: buffer
1489  *
1490  *      Returns true if @skb is the first buffer on the list.
1491  */
1492 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1493                                       const struct sk_buff *skb)
1494 {
1495         return skb->prev == (const struct sk_buff *) list;
1496 }
1497 
1498 /**
1499  *      skb_queue_next - return the next packet in the queue
1500  *      @list: queue head
1501  *      @skb: current buffer
1502  *
1503  *      Return the next packet in @list after @skb.  It is only valid to
1504  *      call this if skb_queue_is_last() evaluates to false.
1505  */
1506 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1507                                              const struct sk_buff *skb)
1508 {
1509         /* This BUG_ON may seem severe, but if we just return then we
1510          * are going to dereference garbage.
1511          */
1512         BUG_ON(skb_queue_is_last(list, skb));
1513         return skb->next;
1514 }
1515 
1516 /**
1517  *      skb_queue_prev - return the prev packet in the queue
1518  *      @list: queue head
1519  *      @skb: current buffer
1520  *
1521  *      Return the prev packet in @list before @skb.  It is only valid to
1522  *      call this if skb_queue_is_first() evaluates to false.
1523  */
1524 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1525                                              const struct sk_buff *skb)
1526 {
1527         /* This BUG_ON may seem severe, but if we just return then we
1528          * are going to dereference garbage.
1529          */
1530         BUG_ON(skb_queue_is_first(list, skb));
1531         return skb->prev;
1532 }
1533 
1534 /**
1535  *      skb_get - reference buffer
1536  *      @skb: buffer to reference
1537  *
1538  *      Makes another reference to a socket buffer and returns a pointer
1539  *      to the buffer.
1540  */
1541 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1542 {
1543         refcount_inc(&skb->users);
1544         return skb;
1545 }
1546 
1547 /*
1548  * If users == 1, we are the only owner and can avoid redundant atomic changes.
1549  */
1550 
1551 /**
1552  *      skb_cloned - is the buffer a clone
1553  *      @skb: buffer to check
1554  *
1555  *      Returns true if the buffer was generated with skb_clone() and is
1556  *      one of multiple shared copies of the buffer. Cloned buffers are
1557  *      shared data so must not be written to under normal circumstances.
1558  */
1559 static inline int skb_cloned(const struct sk_buff *skb)
1560 {
1561         return skb->cloned &&
1562                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1563 }
1564 
1565 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1566 {
1567         might_sleep_if(gfpflags_allow_blocking(pri));
1568 
1569         if (skb_cloned(skb))
1570                 return pskb_expand_head(skb, 0, 0, pri);
1571 
1572         return 0;
1573 }
1574 
1575 /**
1576  *      skb_header_cloned - is the header a clone
1577  *      @skb: buffer to check
1578  *
1579  *      Returns true if modifying the header part of the buffer requires
1580  *      the data to be copied.
1581  */
1582 static inline int skb_header_cloned(const struct sk_buff *skb)
1583 {
1584         int dataref;
1585 
1586         if (!skb->cloned)
1587                 return 0;
1588 
1589         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1590         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1591         return dataref != 1;
1592 }
1593 
1594 static inline int skb_header_unclone(struct sk_buff *skb, gfp_t pri)
1595 {
1596         might_sleep_if(gfpflags_allow_blocking(pri));
1597 
1598         if (skb_header_cloned(skb))
1599                 return pskb_expand_head(skb, 0, 0, pri);
1600 
1601         return 0;
1602 }
1603 
1604 /**
1605  *      __skb_header_release - release reference to header
1606  *      @skb: buffer to operate on
1607  */
1608 static inline void __skb_header_release(struct sk_buff *skb)
1609 {
1610         skb->nohdr = 1;
1611         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1612 }
1613 
1614 
1615 /**
1616  *      skb_shared - is the buffer shared
1617  *      @skb: buffer to check
1618  *
1619  *      Returns true if more than one person has a reference to this
1620  *      buffer.
1621  */
1622 static inline int skb_shared(const struct sk_buff *skb)
1623 {
1624         return refcount_read(&skb->users) != 1;
1625 }
1626 
1627 /**
1628  *      skb_share_check - check if buffer is shared and if so clone it
1629  *      @skb: buffer to check
1630  *      @pri: priority for memory allocation
1631  *
1632  *      If the buffer is shared the buffer is cloned and the old copy
1633  *      drops a reference. A new clone with a single reference is returned.
1634  *      If the buffer is not shared the original buffer is returned. When
1635  *      being called from interrupt status or with spinlocks held pri must
1636  *      be GFP_ATOMIC.
1637  *
1638  *      NULL is returned on a memory allocation failure.
1639  */
1640 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1641 {
1642         might_sleep_if(gfpflags_allow_blocking(pri));
1643         if (skb_shared(skb)) {
1644                 struct sk_buff *nskb = skb_clone(skb, pri);
1645 
1646                 if (likely(nskb))
1647                         consume_skb(skb);
1648                 else
1649                         kfree_skb(skb);
1650                 skb = nskb;
1651         }
1652         return skb;
1653 }
1654 
1655 /*
1656  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1657  *      packets to handle cases where we have a local reader and forward
1658  *      and a couple of other messy ones. The normal one is tcpdumping
1659  *      a packet thats being forwarded.
1660  */
1661 
1662 /**
1663  *      skb_unshare - make a copy of a shared buffer
1664  *      @skb: buffer to check
1665  *      @pri: priority for memory allocation
1666  *
1667  *      If the socket buffer is a clone then this function creates a new
1668  *      copy of the data, drops a reference count on the old copy and returns
1669  *      the new copy with the reference count at 1. If the buffer is not a clone
1670  *      the original buffer is returned. When called with a spinlock held or
1671  *      from interrupt state @pri must be %GFP_ATOMIC
1672  *
1673  *      %NULL is returned on a memory allocation failure.
1674  */
1675 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1676                                           gfp_t pri)
1677 {
1678         might_sleep_if(gfpflags_allow_blocking(pri));
1679         if (skb_cloned(skb)) {
1680                 struct sk_buff *nskb = skb_copy(skb, pri);
1681 
1682                 /* Free our shared copy */
1683                 if (likely(nskb))
1684                         consume_skb(skb);
1685                 else
1686                         kfree_skb(skb);
1687                 skb = nskb;
1688         }
1689         return skb;
1690 }
1691 
1692 /**
1693  *      skb_peek - peek at the head of an &sk_buff_head
1694  *      @list_: list to peek at
1695  *
1696  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1697  *      be careful with this one. A peek leaves the buffer on the
1698  *      list and someone else may run off with it. You must hold
1699  *      the appropriate locks or have a private queue to do this.
1700  *
1701  *      Returns %NULL for an empty list or a pointer to the head element.
1702  *      The reference count is not incremented and the reference is therefore
1703  *      volatile. Use with caution.
1704  */
1705 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1706 {
1707         struct sk_buff *skb = list_->next;
1708 
1709         if (skb == (struct sk_buff *)list_)
1710                 skb = NULL;
1711         return skb;
1712 }
1713 
1714 /**
1715  *      __skb_peek - peek at the head of a non-empty &sk_buff_head
1716  *      @list_: list to peek at
1717  *
1718  *      Like skb_peek(), but the caller knows that the list is not empty.
1719  */
1720 static inline struct sk_buff *__skb_peek(const struct sk_buff_head *list_)
1721 {
1722         return list_->next;
1723 }
1724 
1725 /**
1726  *      skb_peek_next - peek skb following the given one from a queue
1727  *      @skb: skb to start from
1728  *      @list_: list to peek at
1729  *
1730  *      Returns %NULL when the end of the list is met or a pointer to the
1731  *      next element. The reference count is not incremented and the
1732  *      reference is therefore volatile. Use with caution.
1733  */
1734 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1735                 const struct sk_buff_head *list_)
1736 {
1737         struct sk_buff *next = skb->next;
1738 
1739         if (next == (struct sk_buff *)list_)
1740                 next = NULL;
1741         return next;
1742 }
1743 
1744 /**
1745  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1746  *      @list_: list to peek at
1747  *
1748  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1749  *      be careful with this one. A peek leaves the buffer on the
1750  *      list and someone else may run off with it. You must hold
1751  *      the appropriate locks or have a private queue to do this.
1752  *
1753  *      Returns %NULL for an empty list or a pointer to the tail element.
1754  *      The reference count is not incremented and the reference is therefore
1755  *      volatile. Use with caution.
1756  */
1757 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1758 {
1759         struct sk_buff *skb = list_->prev;
1760 
1761         if (skb == (struct sk_buff *)list_)
1762                 skb = NULL;
1763         return skb;
1764 
1765 }
1766 
1767 /**
1768  *      skb_queue_len   - get queue length
1769  *      @list_: list to measure
1770  *
1771  *      Return the length of an &sk_buff queue.
1772  */
1773 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1774 {
1775         return list_->qlen;
1776 }
1777 
1778 /**
1779  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1780  *      @list: queue to initialize
1781  *
1782  *      This initializes only the list and queue length aspects of
1783  *      an sk_buff_head object.  This allows to initialize the list
1784  *      aspects of an sk_buff_head without reinitializing things like
1785  *      the spinlock.  It can also be used for on-stack sk_buff_head
1786  *      objects where the spinlock is known to not be used.
1787  */
1788 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1789 {
1790         list->prev = list->next = (struct sk_buff *)list;
1791         list->qlen = 0;
1792 }
1793 
1794 /*
1795  * This function creates a split out lock class for each invocation;
1796  * this is needed for now since a whole lot of users of the skb-queue
1797  * infrastructure in drivers have different locking usage (in hardirq)
1798  * than the networking core (in softirq only). In the long run either the
1799  * network layer or drivers should need annotation to consolidate the
1800  * main types of usage into 3 classes.
1801  */
1802 static inline void skb_queue_head_init(struct sk_buff_head *list)
1803 {
1804         spin_lock_init(&list->lock);
1805         __skb_queue_head_init(list);
1806 }
1807 
1808 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1809                 struct lock_class_key *class)
1810 {
1811         skb_queue_head_init(list);
1812         lockdep_set_class(&list->lock, class);
1813 }
1814 
1815 /*
1816  *      Insert an sk_buff on a list.
1817  *
1818  *      The "__skb_xxxx()" functions are the non-atomic ones that
1819  *      can only be called with interrupts disabled.
1820  */
1821 static inline void __skb_insert(struct sk_buff *newsk,
1822                                 struct sk_buff *prev, struct sk_buff *next,
1823                                 struct sk_buff_head *list)
1824 {
1825         newsk->next = next;
1826         newsk->prev = prev;
1827         next->prev  = prev->next = newsk;
1828         list->qlen++;
1829 }
1830 
1831 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1832                                       struct sk_buff *prev,
1833                                       struct sk_buff *next)
1834 {
1835         struct sk_buff *first = list->next;
1836         struct sk_buff *last = list->prev;
1837 
1838         first->prev = prev;
1839         prev->next = first;
1840 
1841         last->next = next;
1842         next->prev = last;
1843 }
1844 
1845 /**
1846  *      skb_queue_splice - join two skb lists, this is designed for stacks
1847  *      @list: the new list to add
1848  *      @head: the place to add it in the first list
1849  */
1850 static inline void skb_queue_splice(const struct sk_buff_head *list,
1851                                     struct sk_buff_head *head)
1852 {
1853         if (!skb_queue_empty(list)) {
1854                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1855                 head->qlen += list->qlen;
1856         }
1857 }
1858 
1859 /**
1860  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1861  *      @list: the new list to add
1862  *      @head: the place to add it in the first list
1863  *
1864  *      The list at @list is reinitialised
1865  */
1866 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1867                                          struct sk_buff_head *head)
1868 {
1869         if (!skb_queue_empty(list)) {
1870                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1871                 head->qlen += list->qlen;
1872                 __skb_queue_head_init(list);
1873         }
1874 }
1875 
1876 /**
1877  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1878  *      @list: the new list to add
1879  *      @head: the place to add it in the first list
1880  */
1881 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1882                                          struct sk_buff_head *head)
1883 {
1884         if (!skb_queue_empty(list)) {
1885                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1886                 head->qlen += list->qlen;
1887         }
1888 }
1889 
1890 /**
1891  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1892  *      @list: the new list to add
1893  *      @head: the place to add it in the first list
1894  *
1895  *      Each of the lists is a queue.
1896  *      The list at @list is reinitialised
1897  */
1898 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1899                                               struct sk_buff_head *head)
1900 {
1901         if (!skb_queue_empty(list)) {
1902                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1903                 head->qlen += list->qlen;
1904                 __skb_queue_head_init(list);
1905         }
1906 }
1907 
1908 /**
1909  *      __skb_queue_after - queue a buffer at the list head
1910  *      @list: list to use
1911  *      @prev: place after this buffer
1912  *      @newsk: buffer to queue
1913  *
1914  *      Queue a buffer int the middle of a list. This function takes no locks
1915  *      and you must therefore hold required locks before calling it.
1916  *
1917  *      A buffer cannot be placed on two lists at the same time.
1918  */
1919 static inline void __skb_queue_after(struct sk_buff_head *list,
1920                                      struct sk_buff *prev,
1921                                      struct sk_buff *newsk)
1922 {
1923         __skb_insert(newsk, prev, prev->next, list);
1924 }
1925 
1926 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1927                 struct sk_buff_head *list);
1928 
1929 static inline void __skb_queue_before(struct sk_buff_head *list,
1930                                       struct sk_buff *next,
1931                                       struct sk_buff *newsk)
1932 {
1933         __skb_insert(newsk, next->prev, next, list);
1934 }
1935 
1936 /**
1937  *      __skb_queue_head - queue a buffer at the list head
1938  *      @list: list to use
1939  *      @newsk: buffer to queue
1940  *
1941  *      Queue a buffer at the start of a list. This function takes no locks
1942  *      and you must therefore hold required locks before calling it.
1943  *
1944  *      A buffer cannot be placed on two lists at the same time.
1945  */
1946 static inline void __skb_queue_head(struct sk_buff_head *list,
1947                                     struct sk_buff *newsk)
1948 {
1949         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1950 }
1951 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1952 
1953 /**
1954  *      __skb_queue_tail - queue a buffer at the list tail
1955  *      @list: list to use
1956  *      @newsk: buffer to queue
1957  *
1958  *      Queue a buffer at the end of a list. This function takes no locks
1959  *      and you must therefore hold required locks before calling it.
1960  *
1961  *      A buffer cannot be placed on two lists at the same time.
1962  */
1963 static inline void __skb_queue_tail(struct sk_buff_head *list,
1964                                    struct sk_buff *newsk)
1965 {
1966         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1967 }
1968 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1969 
1970 /*
1971  * remove sk_buff from list. _Must_ be called atomically, and with
1972  * the list known..
1973  */
1974 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1975 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1976 {
1977         struct sk_buff *next, *prev;
1978 
1979         list->qlen--;
1980         next       = skb->next;
1981         prev       = skb->prev;
1982         skb->next  = skb->prev = NULL;
1983         next->prev = prev;
1984         prev->next = next;
1985 }
1986 
1987 /**
1988  *      __skb_dequeue - remove from the head of the queue
1989  *      @list: list to dequeue from
1990  *
1991  *      Remove the head of the list. This function does not take any locks
1992  *      so must be used with appropriate locks held only. The head item is
1993  *      returned or %NULL if the list is empty.
1994  */
1995 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1996 {
1997         struct sk_buff *skb = skb_peek(list);
1998         if (skb)
1999                 __skb_unlink(skb, list);
2000         return skb;
2001 }
2002 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
2003 
2004 /**
2005  *      __skb_dequeue_tail - remove from the tail of the queue
2006  *      @list: list to dequeue from
2007  *
2008  *      Remove the tail of the list. This function does not take any locks
2009  *      so must be used with appropriate locks held only. The tail item is
2010  *      returned or %NULL if the list is empty.
2011  */
2012 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
2013 {
2014         struct sk_buff *skb = skb_peek_tail(list);
2015         if (skb)
2016                 __skb_unlink(skb, list);
2017         return skb;
2018 }
2019 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
2020 
2021 
2022 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
2023 {
2024         return skb->data_len;
2025 }
2026 
2027 static inline unsigned int skb_headlen(const struct sk_buff *skb)
2028 {
2029         return skb->len - skb->data_len;
2030 }
2031 
2032 static inline unsigned int __skb_pagelen(const struct sk_buff *skb)
2033 {
2034         unsigned int i, len = 0;
2035 
2036         for (i = skb_shinfo(skb)->nr_frags - 1; (int)i >= 0; i--)
2037                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
2038         return len;
2039 }
2040 
2041 static inline unsigned int skb_pagelen(const struct sk_buff *skb)
2042 {
2043         return skb_headlen(skb) + __skb_pagelen(skb);
2044 }
2045 
2046 /**
2047  * __skb_fill_page_desc - initialise a paged fragment in an skb
2048  * @skb: buffer containing fragment to be initialised
2049  * @i: paged fragment index to initialise
2050  * @page: the page to use for this fragment
2051  * @off: the offset to the data with @page
2052  * @size: the length of the data
2053  *
2054  * Initialises the @i'th fragment of @skb to point to &size bytes at
2055  * offset @off within @page.
2056  *
2057  * Does not take any additional reference on the fragment.
2058  */
2059 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
2060                                         struct page *page, int off, int size)
2061 {
2062         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2063 
2064         /*
2065          * Propagate page pfmemalloc to the skb if we can. The problem is
2066          * that not all callers have unique ownership of the page but rely
2067          * on page_is_pfmemalloc doing the right thing(tm).
2068          */
2069         frag->page.p              = page;
2070         frag->page_offset         = off;
2071         skb_frag_size_set(frag, size);
2072 
2073         page = compound_head(page);
2074         if (page_is_pfmemalloc(page))
2075                 skb->pfmemalloc = true;
2076 }
2077 
2078 /**
2079  * skb_fill_page_desc - initialise a paged fragment in an skb
2080  * @skb: buffer containing fragment to be initialised
2081  * @i: paged fragment index to initialise
2082  * @page: the page to use for this fragment
2083  * @off: the offset to the data with @page
2084  * @size: the length of the data
2085  *
2086  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
2087  * @skb to point to @size bytes at offset @off within @page. In
2088  * addition updates @skb such that @i is the last fragment.
2089  *
2090  * Does not take any additional reference on the fragment.
2091  */
2092 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
2093                                       struct page *page, int off, int size)
2094 {
2095         __skb_fill_page_desc(skb, i, page, off, size);
2096         skb_shinfo(skb)->nr_frags = i + 1;
2097 }
2098 
2099 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
2100                      int size, unsigned int truesize);
2101 
2102 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
2103                           unsigned int truesize);
2104 
2105 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
2106 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
2107 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
2108 
2109 #ifdef NET_SKBUFF_DATA_USES_OFFSET
2110 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
2111 {
2112         return skb->head + skb->tail;
2113 }
2114 
2115 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
2116 {
2117         skb->tail = skb->data - skb->head;
2118 }
2119 
2120 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
2121 {
2122         skb_reset_tail_pointer(skb);
2123         skb->tail += offset;
2124 }
2125 
2126 #else /* NET_SKBUFF_DATA_USES_OFFSET */
2127 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
2128 {
2129         return skb->tail;
2130 }
2131 
2132 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
2133 {
2134         skb->tail = skb->data;
2135 }
2136 
2137 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
2138 {
2139         skb->tail = skb->data + offset;
2140 }
2141 
2142 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
2143 
2144 /*
2145  *      Add data to an sk_buff
2146  */
2147 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
2148 void *skb_put(struct sk_buff *skb, unsigned int len);
2149 static inline void *__skb_put(struct sk_buff *skb, unsigned int len)
2150 {
2151         void *tmp = skb_tail_pointer(skb);
2152         SKB_LINEAR_ASSERT(skb);
2153         skb->tail += len;
2154         skb->len  += len;
2155         return tmp;
2156 }
2157 
2158 static inline void *__skb_put_zero(struct sk_buff *skb, unsigned int len)
2159 {
2160         void *tmp = __skb_put(skb, len);
2161 
2162         memset(tmp, 0, len);
2163         return tmp;
2164 }
2165 
2166 static inline void *__skb_put_data(struct sk_buff *skb, const void *data,
2167                                    unsigned int len)
2168 {
2169         void *tmp = __skb_put(skb, len);
2170 
2171         memcpy(tmp, data, len);
2172         return tmp;
2173 }
2174 
2175 static inline void __skb_put_u8(struct sk_buff *skb, u8 val)
2176 {
2177         *(u8 *)__skb_put(skb, 1) = val;
2178 }
2179 
2180 static inline void *skb_put_zero(struct sk_buff *skb, unsigned int len)
2181 {
2182         void *tmp = skb_put(skb, len);
2183 
2184         memset(tmp, 0, len);
2185 
2186         return tmp;
2187 }
2188 
2189 static inline void *skb_put_data(struct sk_buff *skb, const void *data,
2190                                  unsigned int len)
2191 {
2192         void *tmp = skb_put(skb, len);
2193 
2194         memcpy(tmp, data, len);
2195 
2196         return tmp;
2197 }
2198 
2199 static inline void skb_put_u8(struct sk_buff *skb, u8 val)
2200 {
2201         *(u8 *)skb_put(skb, 1) = val;
2202 }
2203 
2204 void *skb_push(struct sk_buff *skb, unsigned int len);
2205 static inline void *__skb_push(struct sk_buff *skb, unsigned int len)
2206 {
2207         skb->data -= len;
2208         skb->len  += len;
2209         return skb->data;
2210 }
2211 
2212 void *skb_pull(struct sk_buff *skb, unsigned int len);
2213 static inline void *__skb_pull(struct sk_buff *skb, unsigned int len)
2214 {
2215         skb->len -= len;
2216         BUG_ON(skb->len < skb->data_len);
2217         return skb->data += len;
2218 }
2219 
2220 static inline void *skb_pull_inline(struct sk_buff *skb, unsigned int len)
2221 {
2222         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
2223 }
2224 
2225 void *__pskb_pull_tail(struct sk_buff *skb, int delta);
2226 
2227 static inline void *__pskb_pull(struct sk_buff *skb, unsigned int len)
2228 {
2229         if (len > skb_headlen(skb) &&
2230             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
2231                 return NULL;
2232         skb->len -= len;
2233         return skb->data += len;
2234 }
2235 
2236 static inline void *pskb_pull(struct sk_buff *skb, unsigned int len)
2237 {
2238         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
2239 }
2240 
2241 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
2242 {
2243         if (likely(len <= skb_headlen(skb)))
2244                 return 1;
2245         if (unlikely(len > skb->len))
2246                 return 0;
2247         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
2248 }
2249 
2250 void skb_condense(struct sk_buff *skb);
2251 
2252 /**
2253  *      skb_headroom - bytes at buffer head
2254  *      @skb: buffer to check
2255  *
2256  *      Return the number of bytes of free space at the head of an &sk_buff.
2257  */
2258 static inline unsigned int skb_headroom(const struct sk_buff *skb)
2259 {
2260         return skb->data - skb->head;
2261 }
2262 
2263 /**
2264  *      skb_tailroom - bytes at buffer end
2265  *      @skb: buffer to check
2266  *
2267  *      Return the number of bytes of free space at the tail of an sk_buff
2268  */
2269 static inline int skb_tailroom(const struct sk_buff *skb)
2270 {
2271         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
2272 }
2273 
2274 /**
2275  *      skb_availroom - bytes at buffer end
2276  *      @skb: buffer to check
2277  *
2278  *      Return the number of bytes of free space at the tail of an sk_buff
2279  *      allocated by sk_stream_alloc()
2280  */
2281 static inline int skb_availroom(const struct sk_buff *skb)
2282 {
2283         if (skb_is_nonlinear(skb))
2284                 return 0;
2285 
2286         return skb->end - skb->tail - skb->reserved_tailroom;
2287 }
2288 
2289 /**
2290  *      skb_reserve - adjust headroom
2291  *      @skb: buffer to alter
2292  *      @len: bytes to move
2293  *
2294  *      Increase the headroom of an empty &sk_buff by reducing the tail
2295  *      room. This is only allowed for an empty buffer.
2296  */
2297 static inline void skb_reserve(struct sk_buff *skb, int len)
2298 {
2299         skb->data += len;
2300         skb->tail += len;
2301 }
2302 
2303 /**
2304  *      skb_tailroom_reserve - adjust reserved_tailroom
2305  *      @skb: buffer to alter
2306  *      @mtu: maximum amount of headlen permitted
2307  *      @needed_tailroom: minimum amount of reserved_tailroom
2308  *
2309  *      Set reserved_tailroom so that headlen can be as large as possible but
2310  *      not larger than mtu and tailroom cannot be smaller than
2311  *      needed_tailroom.
2312  *      The required headroom should already have been reserved before using
2313  *      this function.
2314  */
2315 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
2316                                         unsigned int needed_tailroom)
2317 {
2318         SKB_LINEAR_ASSERT(skb);
2319         if (mtu < skb_tailroom(skb) - needed_tailroom)
2320                 /* use at most mtu */
2321                 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
2322         else
2323                 /* use up to all available space */
2324                 skb->reserved_tailroom = needed_tailroom;
2325 }
2326 
2327 #define ENCAP_TYPE_ETHER        0
2328 #define ENCAP_TYPE_IPPROTO      1
2329 
2330 static inline void skb_set_inner_protocol(struct sk_buff *skb,
2331                                           __be16 protocol)
2332 {
2333         skb->inner_protocol = protocol;
2334         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
2335 }
2336 
2337 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
2338                                          __u8 ipproto)
2339 {
2340         skb->inner_ipproto = ipproto;
2341         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
2342 }
2343 
2344 static inline void skb_reset_inner_headers(struct sk_buff *skb)
2345 {
2346         skb->inner_mac_header = skb->mac_header;
2347         skb->inner_network_header = skb->network_header;
2348         skb->inner_transport_header = skb->transport_header;
2349 }
2350 
2351 static inline void skb_reset_mac_len(struct sk_buff *skb)
2352 {
2353         skb->mac_len = skb->network_header - skb->mac_header;
2354 }
2355 
2356 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
2357                                                         *skb)
2358 {
2359         return skb->head + skb->inner_transport_header;
2360 }
2361 
2362 static inline int skb_inner_transport_offset(const struct sk_buff *skb)
2363 {
2364         return skb_inner_transport_header(skb) - skb->data;
2365 }
2366 
2367 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
2368 {
2369         skb->inner_transport_header = skb->data - skb->head;
2370 }
2371 
2372 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
2373                                                    const int offset)
2374 {
2375         skb_reset_inner_transport_header(skb);
2376         skb->inner_transport_header += offset;
2377 }
2378 
2379 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
2380 {
2381         return skb->head + skb->inner_network_header;
2382 }
2383 
2384 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
2385 {
2386         skb->inner_network_header = skb->data - skb->head;
2387 }
2388 
2389 static inline void skb_set_inner_network_header(struct sk_buff *skb,
2390                                                 const int offset)
2391 {
2392         skb_reset_inner_network_header(skb);
2393         skb->inner_network_header += offset;
2394 }
2395 
2396 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
2397 {
2398         return skb->head + skb->inner_mac_header;
2399 }
2400 
2401 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
2402 {
2403         skb->inner_mac_header = skb->data - skb->head;
2404 }
2405 
2406 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
2407                                             const int offset)
2408 {
2409         skb_reset_inner_mac_header(skb);
2410         skb->inner_mac_header += offset;
2411 }
2412 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
2413 {
2414         return skb->transport_header != (typeof(skb->transport_header))~0U;
2415 }
2416 
2417 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
2418 {
2419         return skb->head + skb->transport_header;
2420 }
2421 
2422 static inline void skb_reset_transport_header(struct sk_buff *skb)
2423 {
2424         skb->transport_header = skb->data - skb->head;
2425 }
2426 
2427 static inline void skb_set_transport_header(struct sk_buff *skb,
2428                                             const int offset)
2429 {
2430         skb_reset_transport_header(skb);
2431         skb->transport_header += offset;
2432 }
2433 
2434 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
2435 {
2436         return skb->head + skb->network_header;
2437 }
2438 
2439 static inline void skb_reset_network_header(struct sk_buff *skb)
2440 {
2441         skb->network_header = skb->data - skb->head;
2442 }
2443 
2444 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
2445 {
2446         skb_reset_network_header(skb);
2447         skb->network_header += offset;
2448 }
2449 
2450 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
2451 {
2452         return skb->head + skb->mac_header;
2453 }
2454 
2455 static inline int skb_mac_offset(const struct sk_buff *skb)
2456 {
2457         return skb_mac_header(skb) - skb->data;
2458 }
2459 
2460 static inline u32 skb_mac_header_len(const struct sk_buff *skb)
2461 {
2462         return skb->network_header - skb->mac_header;
2463 }
2464 
2465 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
2466 {
2467         return skb->mac_header != (typeof(skb->mac_header))~0U;
2468 }
2469 
2470 static inline void skb_reset_mac_header(struct sk_buff *skb)
2471 {
2472         skb->mac_header = skb->data - skb->head;
2473 }
2474 
2475 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
2476 {
2477         skb_reset_mac_header(skb);
2478         skb->mac_header += offset;
2479 }
2480 
2481 static inline void skb_pop_mac_header(struct sk_buff *skb)
2482 {
2483         skb->mac_header = skb->network_header;
2484 }
2485 
2486 static inline void skb_probe_transport_header(struct sk_buff *skb)
2487 {
2488         struct flow_keys_basic keys;
2489 
2490         if (skb_transport_header_was_set(skb))
2491                 return;
2492 
2493         if (skb_flow_dissect_flow_keys_basic(skb, &keys, NULL, 0, 0, 0, 0))
2494                 skb_set_transport_header(skb, keys.control.thoff);
2495 }
2496 
2497 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
2498 {
2499         if (skb_mac_header_was_set(skb)) {
2500                 const unsigned char *old_mac = skb_mac_header(skb);
2501 
2502                 skb_set_mac_header(skb, -skb->mac_len);
2503                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
2504         }
2505 }
2506 
2507 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
2508 {
2509         return skb->csum_start - skb_headroom(skb);
2510 }
2511 
2512 static inline unsigned char *skb_checksum_start(const struct sk_buff *skb)
2513 {
2514         return skb->head + skb->csum_start;
2515 }
2516 
2517 static inline int skb_transport_offset(const struct sk_buff *skb)
2518 {
2519         return skb_transport_header(skb) - skb->data;
2520 }
2521 
2522 static inline u32 skb_network_header_len(const struct sk_buff *skb)
2523 {
2524         return skb->transport_header - skb->network_header;
2525 }
2526 
2527 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
2528 {
2529         return skb->inner_transport_header - skb->inner_network_header;
2530 }
2531 
2532 static inline int skb_network_offset(const struct sk_buff *skb)
2533 {
2534         return skb_network_header(skb) - skb->data;
2535 }
2536 
2537 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2538 {
2539         return skb_inner_network_header(skb) - skb->data;
2540 }
2541 
2542 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2543 {
2544         return pskb_may_pull(skb, skb_network_offset(skb) + len);
2545 }
2546 
2547 /*
2548  * CPUs often take a performance hit when accessing unaligned memory
2549  * locations. The actual performance hit varies, it can be small if the
2550  * hardware handles it or large if we have to take an exception and fix it
2551  * in software.
2552  *
2553  * Since an ethernet header is 14 bytes network drivers often end up with
2554  * the IP header at an unaligned offset. The IP header can be aligned by
2555  * shifting the start of the packet by 2 bytes. Drivers should do this
2556  * with:
2557  *
2558  * skb_reserve(skb, NET_IP_ALIGN);
2559  *
2560  * The downside to this alignment of the IP header is that the DMA is now
2561  * unaligned. On some architectures the cost of an unaligned DMA is high
2562  * and this cost outweighs the gains made by aligning the IP header.
2563  *
2564  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2565  * to be overridden.
2566  */
2567 #ifndef NET_IP_ALIGN
2568 #define NET_IP_ALIGN    2
2569 #endif
2570 
2571 /*
2572  * The networking layer reserves some headroom in skb data (via
2573  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2574  * the header has to grow. In the default case, if the header has to grow
2575  * 32 bytes or less we avoid the reallocation.
2576  *
2577  * Unfortunately this headroom changes the DMA alignment of the resulting
2578  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2579  * on some architectures. An architecture can override this value,
2580  * perhaps setting it to a cacheline in size (since that will maintain
2581  * cacheline alignment of the DMA). It must be a power of 2.
2582  *
2583  * Various parts of the networking layer expect at least 32 bytes of
2584  * headroom, you should not reduce this.
2585  *
2586  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2587  * to reduce average number of cache lines per packet.
2588  * get_rps_cpus() for example only access one 64 bytes aligned block :
2589  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2590  */
2591 #ifndef NET_SKB_PAD
2592 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2593 #endif
2594 
2595 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2596 
2597 static inline void __skb_set_length(struct sk_buff *skb, unsigned int len)
2598 {
2599         if (WARN_ON(skb_is_nonlinear(skb)))
2600                 return;
2601         skb->len = len;
2602         skb_set_tail_pointer(skb, len);
2603 }
2604 
2605 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2606 {
2607         __skb_set_length(skb, len);
2608 }
2609 
2610 void skb_trim(struct sk_buff *skb, unsigned int len);
2611 
2612 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2613 {
2614         if (skb->data_len)
2615                 return ___pskb_trim(skb, len);
2616         __skb_trim(skb, len);
2617         return 0;
2618 }
2619 
2620 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2621 {
2622         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2623 }
2624 
2625 /**
2626  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2627  *      @skb: buffer to alter
2628  *      @len: new length
2629  *
2630  *      This is identical to pskb_trim except that the caller knows that
2631  *      the skb is not cloned so we should never get an error due to out-
2632  *      of-memory.
2633  */
2634 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2635 {
2636         int err = pskb_trim(skb, len);
2637         BUG_ON(err);
2638 }
2639 
2640 static inline int __skb_grow(struct sk_buff *skb, unsigned int len)
2641 {
2642         unsigned int diff = len - skb->len;
2643 
2644         if (skb_tailroom(skb) < diff) {
2645                 int ret = pskb_expand_head(skb, 0, diff - skb_tailroom(skb),
2646                                            GFP_ATOMIC);
2647                 if (ret)
2648                         return ret;
2649         }
2650         __skb_set_length(skb, len);
2651         return 0;
2652 }
2653 
2654 /**
2655  *      skb_orphan - orphan a buffer
2656  *      @skb: buffer to orphan
2657  *
2658  *      If a buffer currently has an owner then we call the owner's
2659  *      destructor function and make the @skb unowned. The buffer continues
2660  *      to exist but is no longer charged to its former owner.
2661  */
2662 static inline void skb_orphan(struct sk_buff *skb)
2663 {
2664         if (skb->destructor) {
2665                 skb->destructor(skb);
2666                 skb->destructor = NULL;
2667                 skb->sk         = NULL;
2668         } else {
2669                 BUG_ON(skb->sk);
2670         }
2671 }
2672 
2673 /**
2674  *      skb_orphan_frags - orphan the frags contained in a buffer
2675  *      @skb: buffer to orphan frags from
2676  *      @gfp_mask: allocation mask for replacement pages
2677  *
2678  *      For each frag in the SKB which needs a destructor (i.e. has an
2679  *      owner) create a copy of that frag and release the original
2680  *      page by calling the destructor.
2681  */
2682 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2683 {
2684         if (likely(!skb_zcopy(skb)))
2685                 return 0;
2686         if (skb_uarg(skb)->callback == sock_zerocopy_callback)
2687                 return 0;
2688         return skb_copy_ubufs(skb, gfp_mask);
2689 }
2690 
2691 /* Frags must be orphaned, even if refcounted, if skb might loop to rx path */
2692 static inline int skb_orphan_frags_rx(struct sk_buff *skb, gfp_t gfp_mask)
2693 {
2694         if (likely(!skb_zcopy(skb)))
2695                 return 0;
2696         return skb_copy_ubufs(skb, gfp_mask);
2697 }
2698 
2699 /**
2700  *      __skb_queue_purge - empty a list
2701  *      @list: list to empty
2702  *
2703  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2704  *      the list and one reference dropped. This function does not take the
2705  *      list lock and the caller must hold the relevant locks to use it.
2706  */
2707 static inline void __skb_queue_purge(struct sk_buff_head *list)
2708 {
2709         struct sk_buff *skb;
2710         while ((skb = __skb_dequeue(list)) != NULL)
2711                 kfree_skb(skb);
2712 }
2713 void skb_queue_purge(struct sk_buff_head *list);
2714 
2715 unsigned int skb_rbtree_purge(struct rb_root *root);
2716 
2717 void *netdev_alloc_frag(unsigned int fragsz);
2718 
2719 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2720                                    gfp_t gfp_mask);
2721 
2722 /**
2723  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2724  *      @dev: network device to receive on
2725  *      @length: length to allocate
2726  *
2727  *      Allocate a new &sk_buff and assign it a usage count of one. The
2728  *      buffer has unspecified headroom built in. Users should allocate
2729  *      the headroom they think they need without accounting for the
2730  *      built in space. The built in space is used for optimisations.
2731  *
2732  *      %NULL is returned if there is no free memory. Although this function
2733  *      allocates memory it can be called from an interrupt.
2734  */
2735 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2736                                                unsigned int length)
2737 {
2738         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2739 }
2740 
2741 /* legacy helper around __netdev_alloc_skb() */
2742 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2743                                               gfp_t gfp_mask)
2744 {
2745         return __netdev_alloc_skb(NULL, length, gfp_mask);
2746 }
2747 
2748 /* legacy helper around netdev_alloc_skb() */
2749 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2750 {
2751         return netdev_alloc_skb(NULL, length);
2752 }
2753 
2754 
2755 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2756                 unsigned int length, gfp_t gfp)
2757 {
2758         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2759 
2760         if (NET_IP_ALIGN && skb)
2761                 skb_reserve(skb, NET_IP_ALIGN);
2762         return skb;
2763 }
2764 
2765 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2766                 unsigned int length)
2767 {
2768         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2769 }
2770 
2771 static inline void skb_free_frag(void *addr)
2772 {
2773         page_frag_free(addr);
2774 }
2775 
2776 void *napi_alloc_frag(unsigned int fragsz);
2777 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2778                                  unsigned int length, gfp_t gfp_mask);
2779 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2780                                              unsigned int length)
2781 {
2782         return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2783 }
2784 void napi_consume_skb(struct sk_buff *skb, int budget);
2785 
2786 void __kfree_skb_flush(void);
2787 void __kfree_skb_defer(struct sk_buff *skb);
2788 
2789 /**
2790  * __dev_alloc_pages - allocate page for network Rx
2791  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2792  * @order: size of the allocation
2793  *
2794  * Allocate a new page.
2795  *
2796  * %NULL is returned if there is no free memory.
2797 */
2798 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2799                                              unsigned int order)
2800 {
2801         /* This piece of code contains several assumptions.
2802          * 1.  This is for device Rx, therefor a cold page is preferred.
2803          * 2.  The expectation is the user wants a compound page.
2804          * 3.  If requesting a order 0 page it will not be compound
2805          *     due to the check to see if order has a value in prep_new_page
2806          * 4.  __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2807          *     code in gfp_to_alloc_flags that should be enforcing this.
2808          */
2809         gfp_mask |= __GFP_COMP | __GFP_MEMALLOC;
2810 
2811         return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2812 }
2813 
2814 static inline struct page *dev_alloc_pages(unsigned int order)
2815 {
2816         return __dev_alloc_pages(GFP_ATOMIC | __GFP_NOWARN, order);
2817 }
2818 
2819 /**
2820  * __dev_alloc_page - allocate a page for network Rx
2821  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2822  *
2823  * Allocate a new page.
2824  *
2825  * %NULL is returned if there is no free memory.
2826  */
2827 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2828 {
2829         return __dev_alloc_pages(gfp_mask, 0);
2830 }
2831 
2832 static inline struct page *dev_alloc_page(void)
2833 {
2834         return dev_alloc_pages(0);
2835 }
2836 
2837 /**
2838  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2839  *      @page: The page that was allocated from skb_alloc_page
2840  *      @skb: The skb that may need pfmemalloc set
2841  */
2842 static inline void skb_propagate_pfmemalloc(struct page *page,
2843                                              struct sk_buff *skb)
2844 {
2845         if (page_is_pfmemalloc(page))
2846                 skb->pfmemalloc = true;
2847 }
2848 
2849 /**
2850  * skb_frag_page - retrieve the page referred to by a paged fragment
2851  * @frag: the paged fragment
2852  *
2853  * Returns the &struct page associated with @frag.
2854  */
2855 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2856 {
2857         return frag->page.p;
2858 }
2859 
2860 /**
2861  * __skb_frag_ref - take an addition reference on a paged fragment.
2862  * @frag: the paged fragment
2863  *
2864  * Takes an additional reference on the paged fragment @frag.
2865  */
2866 static inline void __skb_frag_ref(skb_frag_t *frag)
2867 {
2868         get_page(skb_frag_page(frag));
2869 }
2870 
2871 /**
2872  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2873  * @skb: the buffer
2874  * @f: the fragment offset.
2875  *
2876  * Takes an additional reference on the @f'th paged fragment of @skb.
2877  */
2878 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2879 {
2880         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2881 }
2882 
2883 /**
2884  * __skb_frag_unref - release a reference on a paged fragment.
2885  * @frag: the paged fragment
2886  *
2887  * Releases a reference on the paged fragment @frag.
2888  */
2889 static inline void __skb_frag_unref(skb_frag_t *frag)
2890 {
2891         put_page(skb_frag_page(frag));
2892 }
2893 
2894 /**
2895  * skb_frag_unref - release a reference on a paged fragment of an skb.
2896  * @skb: the buffer
2897  * @f: the fragment offset
2898  *
2899  * Releases a reference on the @f'th paged fragment of @skb.
2900  */
2901 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2902 {
2903         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2904 }
2905 
2906 /**
2907  * skb_frag_address - gets the address of the data contained in a paged fragment
2908  * @frag: the paged fragment buffer
2909  *
2910  * Returns the address of the data within @frag. The page must already
2911  * be mapped.
2912  */
2913 static inline void *skb_frag_address(const skb_frag_t *frag)
2914 {
2915         return page_address(skb_frag_page(frag)) + frag->page_offset;
2916 }
2917 
2918 /**
2919  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2920  * @frag: the paged fragment buffer
2921  *
2922  * Returns the address of the data within @frag. Checks that the page
2923  * is mapped and returns %NULL otherwise.
2924  */
2925 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2926 {
2927         void *ptr = page_address(skb_frag_page(frag));
2928         if (unlikely(!ptr))
2929                 return NULL;
2930 
2931         return ptr + frag->page_offset;
2932 }
2933 
2934 /**
2935  * __skb_frag_set_page - sets the page contained in a paged fragment
2936  * @frag: the paged fragment
2937  * @page: the page to set
2938  *
2939  * Sets the fragment @frag to contain @page.
2940  */
2941 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2942 {
2943         frag->page.p = page;
2944 }
2945 
2946 /**
2947  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2948  * @skb: the buffer
2949  * @f: the fragment offset
2950  * @page: the page to set
2951  *
2952  * Sets the @f'th fragment of @skb to contain @page.
2953  */
2954 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2955                                      struct page *page)
2956 {
2957         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2958 }
2959 
2960 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2961 
2962 /**
2963  * skb_frag_dma_map - maps a paged fragment via the DMA API
2964  * @dev: the device to map the fragment to
2965  * @frag: the paged fragment to map
2966  * @offset: the offset within the fragment (starting at the
2967  *          fragment's own offset)
2968  * @size: the number of bytes to map
2969  * @dir: the direction of the mapping (``PCI_DMA_*``)
2970  *
2971  * Maps the page associated with @frag to @device.
2972  */
2973 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2974                                           const skb_frag_t *frag,
2975                                           size_t offset, size_t size,
2976                                           enum dma_data_direction dir)
2977 {
2978         return dma_map_page(dev, skb_frag_page(frag),
2979                             frag->page_offset + offset, size, dir);
2980 }
2981 
2982 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2983                                         gfp_t gfp_mask)
2984 {
2985         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2986 }
2987 
2988 
2989 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2990                                                   gfp_t gfp_mask)
2991 {
2992         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2993 }
2994 
2995 
2996 /**
2997  *      skb_clone_writable - is the header of a clone writable
2998  *      @skb: buffer to check
2999  *      @len: length up to which to write
3000  *
3001  *      Returns true if modifying the header part of the cloned buffer
3002  *      does not requires the data to be copied.
3003  */
3004 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
3005 {
3006         return !skb_header_cloned(skb) &&
3007                skb_headroom(skb) + len <= skb->hdr_len;
3008 }
3009 
3010 static inline int skb_try_make_writable(struct sk_buff *skb,
3011                                         unsigned int write_len)
3012 {
3013         return skb_cloned(skb) && !skb_clone_writable(skb, write_len) &&
3014                pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
3015 }
3016 
3017 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
3018                             int cloned)
3019 {
3020         int delta = 0;
3021 
3022         if (headroom > skb_headroom(skb))
3023                 delta = headroom - skb_headroom(skb);
3024 
3025         if (delta || cloned)
3026                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
3027                                         GFP_ATOMIC);
3028         return 0;
3029 }
3030 
3031 /**
3032  *      skb_cow - copy header of skb when it is required
3033  *      @skb: buffer to cow
3034  *      @headroom: needed headroom
3035  *
3036  *      If the skb passed lacks sufficient headroom or its data part
3037  *      is shared, data is reallocated. If reallocation fails, an error
3038  *      is returned and original skb is not changed.
3039  *
3040  *      The result is skb with writable area skb->head...skb->tail
3041  *      and at least @headroom of space at head.
3042  */
3043 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
3044 {
3045         return __skb_cow(skb, headroom, skb_cloned(skb));
3046 }
3047 
3048 /**
3049  *      skb_cow_head - skb_cow but only making the head writable
3050  *      @skb: buffer to cow
3051  *      @headroom: needed headroom
3052  *
3053  *      This function is identical to skb_cow except that we replace the
3054  *      skb_cloned check by skb_header_cloned.  It should be used when
3055  *      you only need to push on some header and do not need to modify
3056  *      the data.
3057  */
3058 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
3059 {
3060         return __skb_cow(skb, headroom, skb_header_cloned(skb));
3061 }
3062 
3063 /**
3064  *      skb_padto       - pad an skbuff up to a minimal size
3065  *      @skb: buffer to pad
3066  *      @len: minimal length
3067  *
3068  *      Pads up a buffer to ensure the trailing bytes exist and are
3069  *      blanked. If the buffer already contains sufficient data it
3070  *      is untouched. Otherwise it is extended. Returns zero on
3071  *      success. The skb is freed on error.
3072  */
3073 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
3074 {
3075         unsigned int size = skb->len;
3076         if (likely(size >= len))
3077                 return 0;
3078         return skb_pad(skb, len - size);
3079 }
3080 
3081 /**
3082  *      __skb_put_padto - increase size and pad an skbuff up to a minimal size
3083  *      @skb: buffer to pad
3084  *      @len: minimal length
3085  *      @free_on_error: free buffer on error
3086  *
3087  *      Pads up a buffer to ensure the trailing bytes exist and are
3088  *      blanked. If the buffer already contains sufficient data it
3089  *      is untouched. Otherwise it is extended. Returns zero on
3090  *      success. The skb is freed on error if @free_on_error is true.
3091  */
3092 static inline int __skb_put_padto(struct sk_buff *skb, unsigned int len,
3093                                   bool free_on_error)
3094 {
3095         unsigned int size = skb->len;
3096 
3097         if (unlikely(size < len)) {
3098                 len -= size;
3099                 if (__skb_pad(skb, len, free_on_error))
3100                         return -ENOMEM;
3101                 __skb_put(skb, len);
3102         }
3103         return 0;
3104 }
3105 
3106 /**
3107  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
3108  *      @skb: buffer to pad
3109  *      @len: minimal length
3110  *
3111  *      Pads up a buffer to ensure the trailing bytes exist and are
3112  *      blanked. If the buffer already contains sufficient data it
3113  *      is untouched. Otherwise it is extended. Returns zero on
3114  *      success. The skb is freed on error.
3115  */
3116 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
3117 {
3118         return __skb_put_padto(skb, len, true);
3119 }
3120 
3121 static inline int skb_add_data(struct sk_buff *skb,
3122                                struct iov_iter *from, int copy)
3123 {
3124         const int off = skb->len;
3125 
3126         if (skb->ip_summed == CHECKSUM_NONE) {
3127                 __wsum csum = 0;
3128                 if (csum_and_copy_from_iter_full(skb_put(skb, copy), copy,
3129                                                  &csum, from)) {
3130                         skb->csum = csum_block_add(skb->csum, csum, off);
3131                         return 0;
3132                 }
3133         } else if (copy_from_iter_full(skb_put(skb, copy), copy, from))
3134                 return 0;
3135 
3136         __skb_trim(skb, off);
3137         return -EFAULT;
3138 }
3139 
3140 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
3141                                     const struct page *page, int off)
3142 {
3143         if (skb_zcopy(skb))
3144                 return false;
3145         if (i) {
3146                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
3147 
3148                 return page == skb_frag_page(frag) &&
3149                        off == frag->page_offset + skb_frag_size(frag);
3150         }
3151         return false;
3152 }
3153 
3154 static inline int __skb_linearize(struct sk_buff *skb)
3155 {
3156         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
3157 }
3158 
3159 /**
3160  *      skb_linearize - convert paged skb to linear one
3161  *      @skb: buffer to linarize
3162  *
3163  *      If there is no free memory -ENOMEM is returned, otherwise zero
3164  *      is returned and the old skb data released.
3165  */
3166 static inline int skb_linearize(struct sk_buff *skb)
3167 {
3168         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
3169 }
3170 
3171 /**
3172  * skb_has_shared_frag - can any frag be overwritten
3173  * @skb: buffer to test
3174  *
3175  * Return true if the skb has at least one frag that might be modified
3176  * by an external entity (as in vmsplice()/sendfile())
3177  */
3178 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
3179 {
3180         return skb_is_nonlinear(skb) &&
3181                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
3182 }
3183 
3184 /**
3185  *      skb_linearize_cow - make sure skb is linear and writable
3186  *      @skb: buffer to process
3187  *
3188  *      If there is no free memory -ENOMEM is returned, otherwise zero
3189  *      is returned and the old skb data released.
3190  */
3191 static inline int skb_linearize_cow(struct sk_buff *skb)
3192 {
3193         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
3194                __skb_linearize(skb) : 0;
3195 }
3196 
3197 static __always_inline void
3198 __skb_postpull_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
3199                      unsigned int off)
3200 {
3201         if (skb->ip_summed == CHECKSUM_COMPLETE)
3202                 skb->csum = csum_block_sub(skb->csum,
3203                                            csum_partial(start, len, 0), off);
3204         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
3205                  skb_checksum_start_offset(skb) < 0)
3206                 skb->ip_summed = CHECKSUM_NONE;
3207 }
3208 
3209 /**
3210  *      skb_postpull_rcsum - update checksum for received skb after pull
3211  *      @skb: buffer to update
3212  *      @start: start of data before pull
3213  *      @len: length of data pulled
3214  *
3215  *      After doing a pull on a received packet, you need to call this to
3216  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
3217  *      CHECKSUM_NONE so that it can be recomputed from scratch.
3218  */
3219 static inline void skb_postpull_rcsum(struct sk_buff *skb,
3220                                       const void *start, unsigned int len)
3221 {
3222         __skb_postpull_rcsum(skb, start, len, 0);
3223 }
3224 
3225 static __always_inline void
3226 __skb_postpush_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
3227                      unsigned int off)
3228 {
3229         if (skb->ip_summed == CHECKSUM_COMPLETE)
3230                 skb->csum = csum_block_add(skb->csum,
3231                                            csum_partial(start, len, 0), off);
3232 }
3233 
3234 /**
3235  *      skb_postpush_rcsum - update checksum for received skb after push
3236  *      @skb: buffer to update
3237  *      @start: start of data after push
3238  *      @len: length of data pushed
3239  *
3240  *      After doing a push on a received packet, you need to call this to
3241  *      update the CHECKSUM_COMPLETE checksum.
3242  */
3243 static inline void skb_postpush_rcsum(struct sk_buff *skb,
3244                                       const void *start, unsigned int len)
3245 {
3246         __skb_postpush_rcsum(skb, start, len, 0);
3247 }
3248 
3249 void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
3250 
3251 /**
3252  *      skb_push_rcsum - push skb and update receive checksum
3253  *      @skb: buffer to update
3254  *      @len: length of data pulled
3255  *
3256  *      This function performs an skb_push on the packet and updates
3257  *      the CHECKSUM_COMPLETE checksum.  It should be used on
3258  *      receive path processing instead of skb_push unless you know
3259  *      that the checksum difference is zero (e.g., a valid IP header)
3260  *      or you are setting ip_summed to CHECKSUM_NONE.
3261  */
3262 static inline void *skb_push_rcsum(struct sk_buff *skb, unsigned int len)
3263 {
3264         skb_push(skb, len);
3265         skb_postpush_rcsum(skb, skb->data, len);
3266         return skb->data;
3267 }
3268 
3269 int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len);
3270 /**
3271  *      pskb_trim_rcsum - trim received skb and update checksum
3272  *      @skb: buffer to trim
3273  *      @len: new length
3274  *
3275  *      This is exactly the same as pskb_trim except that it ensures the
3276  *      checksum of received packets are still valid after the operation.
3277  *      It can change skb pointers.
3278  */
3279 
3280 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
3281 {
3282         if (likely(len >= skb->len))
3283                 return 0;
3284         return pskb_trim_rcsum_slow(skb, len);
3285 }
3286 
3287 static inline int __skb_trim_rcsum(struct sk_buff *skb, unsigned int len)
3288 {
3289         if (skb->ip_summed == CHECKSUM_COMPLETE)
3290                 skb->ip_summed = CHECKSUM_NONE;
3291         __skb_trim(skb, len);
3292         return 0;
3293 }
3294 
3295 static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
3296 {
3297         if (skb->ip_summed == CHECKSUM_COMPLETE)
3298                 skb->ip_summed = CHECKSUM_NONE;
3299         return __skb_grow(skb, len);
3300 }
3301 
3302 #define rb_to_skb(rb) rb_entry_safe(rb, struct sk_buff, rbnode)
3303 #define skb_rb_first(root) rb_to_skb(rb_first(root))
3304 #define skb_rb_last(root)  rb_to_skb(rb_last(root))
3305 #define skb_rb_next(skb)   rb_to_skb(rb_next(&(skb)->rbnode))
3306 #define skb_rb_prev(skb)   rb_to_skb(rb_prev(&(skb)->rbnode))
3307 
3308 #define skb_queue_walk(queue, skb) \
3309                 for (skb = (queue)->next;                                       \
3310                      skb != (struct sk_buff *)(queue);                          \
3311                      skb = skb->next)
3312 
3313 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
3314                 for (skb = (queue)->next, tmp = skb->next;                      \
3315                      skb != (struct sk_buff *)(queue);                          \
3316                      skb = tmp, tmp = skb->next)
3317 
3318 #define skb_queue_walk_from(queue, skb)                                         \
3319                 for (; skb != (struct sk_buff *)(queue);                        \
3320                      skb = skb->next)
3321 
3322 #define skb_rbtree_walk(skb, root)                                              \
3323                 for (skb = skb_rb_first(root); skb != NULL;                     \
3324                      skb = skb_rb_next(skb))
3325 
3326 #define skb_rbtree_walk_from(skb)                                               \
3327                 for (; skb != NULL;                                             \
3328                      skb = skb_rb_next(skb))
3329 
3330 #define skb_rbtree_walk_from_safe(skb, tmp)                                     \
3331                 for (; tmp = skb ? skb_rb_next(skb) : NULL, (skb != NULL);      \
3332                      skb = tmp)
3333 
3334 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
3335                 for (tmp = skb->next;                                           \
3336                      skb != (struct sk_buff *)(queue);                          \
3337                      skb = tmp, tmp = skb->next)
3338 
3339 #define skb_queue_reverse_walk(queue, skb) \
3340                 for (skb = (queue)->prev;                                       \
3341                      skb != (struct sk_buff *)(queue);                          \
3342                      skb = skb->prev)
3343 
3344 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
3345                 for (skb = (queue)->prev, tmp = skb->prev;                      \
3346                      skb != (struct sk_buff *)(queue);                          \
3347                      skb = tmp, tmp = skb->prev)
3348 
3349 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
3350                 for (tmp = skb->prev;                                           \
3351                      skb != (struct sk_buff *)(queue);                          \
3352                      skb = tmp, tmp = skb->prev)
3353 
3354 static inline bool skb_has_frag_list(const struct sk_buff *skb)
3355 {
3356         return skb_shinfo(skb)->frag_list != NULL;
3357 }
3358 
3359 static inline void skb_frag_list_init(struct sk_buff *skb)
3360 {
3361         skb_shinfo(skb)->frag_list = NULL;
3362 }
3363 
3364 #define skb_walk_frags(skb, iter)       \
3365         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
3366 
3367 
3368 int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
3369                                 const struct sk_buff *skb);
3370 struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
3371                                           struct sk_buff_head *queue,
3372                                           unsigned int flags,
3373                                           void (*destructor)(struct sock *sk,
3374                                                            struct sk_buff *skb),
3375                                           int *peeked, int *off, int *err,
3376                                           struct sk_buff **last);
3377 struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
3378                                         void (*destructor)(struct sock *sk,
3379                                                            struct sk_buff *skb),
3380                                         int *peeked, int *off, int *err,
3381                                         struct sk_buff **last);
3382 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
3383                                     void (*destructor)(struct sock *sk,
3384                                                        struct sk_buff *skb),
3385                                     int *peeked, int *off, int *err);
3386 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
3387                                   int *err);
3388 __poll_t datagram_poll(struct file *file, struct socket *sock,
3389                            struct poll_table_struct *wait);
3390 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
3391                            struct iov_iter *to, int size);
3392 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
3393                                         struct msghdr *msg, int size)
3394 {
3395         return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
3396 }
3397 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
3398                                    struct msghdr *msg);
3399 int skb_copy_and_hash_datagram_iter(const struct sk_buff *skb, int offset,
3400                            struct iov_iter *to, int len,
3401                            struct ahash_request *hash);
3402 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
3403                                  struct iov_iter *from, int len);
3404 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
3405 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
3406 void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len);
3407 static inline void skb_free_datagram_locked(struct sock *sk,
3408                                             struct sk_buff *skb)
3409 {
3410         __skb_free_datagram_locked(sk, skb, 0);
3411 }
3412 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
3413 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
3414 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
3415 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
3416                               int len, __wsum csum);
3417 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3418                     struct pipe_inode_info *pipe, unsigned int len,
3419                     unsigned int flags);
3420 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
3421                          int len);
3422 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
3423 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
3424 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
3425                  int len, int hlen);
3426 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
3427 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
3428 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
3429 bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu);
3430 bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len);
3431 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
3432 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
3433 int skb_ensure_writable(struct sk_buff *skb, int write_len);
3434 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);
3435 int skb_vlan_pop(struct sk_buff *skb);
3436 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
3437 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
3438                              gfp_t gfp);
3439 
3440 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
3441 {
3442         return copy_from_iter_full(data, len, &msg->msg_iter) ? 0 : -EFAULT;
3443 }
3444 
3445 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
3446 {
3447         return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3448 }
3449 
3450 struct skb_checksum_ops {
3451         __wsum (*update)(const void *mem, int len, __wsum wsum);
3452         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
3453 };
3454 
3455 extern const struct skb_checksum_ops *crc32c_csum_stub __read_mostly;
3456 
3457 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3458                       __wsum csum, const struct skb_checksum_ops *ops);
3459 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
3460                     __wsum csum);
3461 
3462 static inline void * __must_check
3463 __skb_header_pointer(const struct sk_buff *skb, int offset,
3464                      int len, void *data, int hlen, void *buffer)
3465 {
3466         if (hlen - offset >= len)
3467                 return data + offset;
3468 
3469         if (!skb ||
3470             skb_copy_bits(skb, offset, buffer, len) < 0)
3471                 return NULL;
3472 
3473         return buffer;
3474 }
3475 
3476 static inline void * __must_check
3477 skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
3478 {
3479         return __skb_header_pointer(skb, offset, len, skb->data,
3480                                     skb_headlen(skb), buffer);
3481 }
3482 
3483 /**
3484  *      skb_needs_linearize - check if we need to linearize a given skb
3485  *                            depending on the given device features.
3486  *      @skb: socket buffer to check
3487  *      @features: net device features
3488  *
3489  *      Returns true if either:
3490  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
3491  *      2. skb is fragmented and the device does not support SG.
3492  */
3493 static inline bool skb_needs_linearize(struct sk_buff *skb,
3494                                        netdev_features_t features)
3495 {
3496         return skb_is_nonlinear(skb) &&
3497                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
3498                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
3499 }
3500 
3501 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
3502                                              void *to,
3503                                              const unsigned int len)
3504 {
3505         memcpy(to, skb->data, len);
3506 }
3507 
3508 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
3509                                                     const int offset, void *to,
3510                                                     const unsigned int len)
3511 {
3512         memcpy(to, skb->data + offset, len);
3513 }
3514 
3515 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
3516                                            const void *from,
3517                                            const unsigned int len)
3518 {
3519         memcpy(skb->data, from, len);
3520 }
3521 
3522 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
3523                                                   const int offset,
3524                                                   const void *from,
3525                                                   const unsigned int len)
3526 {
3527         memcpy(skb->data + offset, from, len);
3528 }
3529 
3530 void skb_init(void);
3531 
3532 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
3533 {
3534         return skb->tstamp;
3535 }
3536 
3537 /**
3538  *      skb_get_timestamp - get timestamp from a skb
3539  *      @skb: skb to get stamp from
3540  *      @stamp: pointer to struct __kernel_old_timeval to store stamp in
3541  *
3542  *      Timestamps are stored in the skb as offsets to a base timestamp.
3543  *      This function converts the offset back to a struct timeval and stores
3544  *      it in stamp.
3545  */
3546 static inline void skb_get_timestamp(const struct sk_buff *skb,
3547                                      struct __kernel_old_timeval *stamp)
3548 {
3549         *stamp = ns_to_kernel_old_timeval(skb->tstamp);
3550 }
3551 
3552 static inline void skb_get_new_timestamp(const struct sk_buff *skb,
3553                                          struct __kernel_sock_timeval *stamp)
3554 {
3555         struct timespec64 ts = ktime_to_timespec64(skb->tstamp);
3556 
3557         stamp->tv_sec = ts.tv_sec;
3558         stamp->tv_usec = ts.tv_nsec / 1000;
3559 }
3560 
3561 static inline void skb_get_timestampns(const struct sk_buff *skb,
3562                                        struct timespec *stamp)
3563 {
3564         *stamp = ktime_to_timespec(skb->tstamp);
3565 }
3566 
3567 static inline void skb_get_new_timestampns(const struct sk_buff *skb,
3568                                            struct __kernel_timespec *stamp)
3569 {
3570         struct timespec64 ts = ktime_to_timespec64(skb->tstamp);
3571 
3572         stamp->tv_sec = ts.tv_sec;
3573         stamp->tv_nsec = ts.tv_nsec;
3574 }
3575 
3576 static inline void __net_timestamp(struct sk_buff *skb)
3577 {
3578         skb->tstamp = ktime_get_real();
3579 }
3580 
3581 static inline ktime_t net_timedelta(ktime_t t)
3582 {
3583         return ktime_sub(ktime_get_real(), t);
3584 }
3585 
3586 static inline ktime_t net_invalid_timestamp(void)
3587 {
3588         return 0;
3589 }
3590 
3591 static inline u8 skb_metadata_len(const struct sk_buff *skb)
3592 {
3593         return skb_shinfo(skb)->meta_len;
3594 }
3595 
3596 static inline void *skb_metadata_end(const struct sk_buff *skb)
3597 {
3598         return skb_mac_header(skb);
3599 }
3600 
3601 static inline bool __skb_metadata_differs(const struct sk_buff *skb_a,
3602                                           const struct sk_buff *skb_b,
3603                                           u8 meta_len)
3604 {
3605         const void *a = skb_metadata_end(skb_a);
3606         const void *b = skb_metadata_end(skb_b);
3607         /* Using more efficient varaiant than plain call to memcmp(). */
3608 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
3609         u64 diffs = 0;
3610 
3611         switch (meta_len) {
3612 #define __it(x, op) (x -= sizeof(u##op))
3613 #define __it_diff(a, b, op) (*(u##op *)__it(a, op)) ^ (*(u##op *)__it(b, op))
3614         case 32: diffs |= __it_diff(a, b, 64);
3615                  /* fall through */
3616         case 24: diffs |= __it_diff(a, b, 64);
3617                  /* fall through */
3618         case 16: diffs |= __it_diff(a, b, 64);
3619                  /* fall through */
3620         case  8: diffs |= __it_diff(a, b, 64);
3621                 break;
3622         case 28: diffs |= __it_diff(a, b, 64);
3623                  /* fall through */
3624         case 20: diffs |= __it_diff(a, b, 64);
3625                  /* fall through */
3626         case 12: diffs |= __it_diff(a, b, 64);
3627                  /* fall through */
3628         case  4: diffs |= __it_diff(a, b, 32);
3629                 break;
3630         }
3631         return diffs;
3632 #else
3633         return memcmp(a - meta_len, b - meta_len, meta_len);
3634 #endif
3635 }
3636 
3637 static inline bool skb_metadata_differs(const struct sk_buff *skb_a,
3638                                         const struct sk_buff *skb_b)
3639 {
3640         u8 len_a = skb_metadata_len(skb_a);
3641         u8 len_b = skb_metadata_len(skb_b);
3642 
3643         if (!(len_a | len_b))
3644                 return false;
3645 
3646         return len_a != len_b ?
3647                true : __skb_metadata_differs(skb_a, skb_b, len_a);
3648 }
3649 
3650 static inline void skb_metadata_set(struct sk_buff *skb, u8 meta_len)
3651 {
3652         skb_shinfo(skb)->meta_len = meta_len;
3653 }
3654 
3655 static inline void skb_metadata_clear(struct sk_buff *skb)
3656 {
3657         skb_metadata_set(skb, 0);
3658 }
3659 
3660 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
3661 
3662 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
3663 
3664 void skb_clone_tx_timestamp(struct sk_buff *skb);
3665 bool skb_defer_rx_timestamp(struct sk_buff *skb);
3666 
3667 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
3668 
3669 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
3670 {
3671 }
3672 
3673 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
3674 {
3675         return false;
3676 }
3677 
3678 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
3679 
3680 /**
3681  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
3682  *
3683  * PHY drivers may accept clones of transmitted packets for
3684  * timestamping via their phy_driver.txtstamp method. These drivers
3685  * must call this function to return the skb back to the stack with a
3686  * timestamp.
3687  *
3688  * @skb: clone of the the original outgoing packet
3689  * @hwtstamps: hardware time stamps
3690  *
3691  */
3692 void skb_complete_tx_timestamp(struct sk_buff *skb,
3693                                struct skb_shared_hwtstamps *hwtstamps);
3694 
3695 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3696                      struct skb_shared_hwtstamps *hwtstamps,
3697                      struct sock *sk, int tstype);
3698 
3699 /**
3700  * skb_tstamp_tx - queue clone of skb with send time stamps
3701  * @orig_skb:   the original outgoing packet
3702  * @hwtstamps:  hardware time stamps, may be NULL if not available
3703  *
3704  * If the skb has a socket associated, then this function clones the
3705  * skb (thus sharing the actual data and optional structures), stores
3706  * the optional hardware time stamping information (if non NULL) or
3707  * generates a software time stamp (otherwise), then queues the clone
3708  * to the error queue of the socket.  Errors are silently ignored.
3709  */
3710 void skb_tstamp_tx(struct sk_buff *orig_skb,
3711                    struct skb_shared_hwtstamps *hwtstamps);
3712 
3713 /**
3714  * skb_tx_timestamp() - Driver hook for transmit timestamping
3715  *
3716  * Ethernet MAC Drivers should call this function in their hard_xmit()
3717  * function immediately before giving the sk_buff to the MAC hardware.
3718  *
3719  * Specifically, one should make absolutely sure that this function is
3720  * called before TX completion of this packet can trigger.  Otherwise
3721  * the packet could potentially already be freed.
3722  *
3723  * @skb: A socket buffer.
3724  */
3725 static inline void skb_tx_timestamp(struct sk_buff *skb)
3726 {
3727         skb_clone_tx_timestamp(skb);
3728         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
3729                 skb_tstamp_tx(skb, NULL);
3730 }
3731 
3732 /**
3733  * skb_complete_wifi_ack - deliver skb with wifi status
3734  *
3735  * @skb: the original outgoing packet
3736  * @acked: ack status
3737  *
3738  */
3739 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
3740 
3741 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
3742 __sum16 __skb_checksum_complete(struct sk_buff *skb);
3743 
3744 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
3745 {
3746         return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
3747                 skb->csum_valid ||
3748                 (skb->ip_summed == CHECKSUM_PARTIAL &&
3749                  skb_checksum_start_offset(skb) >= 0));
3750 }
3751 
3752 /**
3753  *      skb_checksum_complete - Calculate checksum of an entire packet
3754  *      @skb: packet to process
3755  *
3756  *      This function calculates the checksum over the entire packet plus
3757  *      the value of skb->csum.  The latter can be used to supply the
3758  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
3759  *      checksum.
3760  *
3761  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
3762  *      this function can be used to verify that checksum on received
3763  *      packets.  In that case the function should return zero if the
3764  *      checksum is correct.  In particular, this function will return zero
3765  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
3766  *      hardware has already verified the correctness of the checksum.
3767  */
3768 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
3769 {
3770         return skb_csum_unnecessary(skb) ?
3771                0 : __skb_checksum_complete(skb);
3772 }
3773 
3774 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
3775 {
3776         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3777                 if (skb->csum_level == 0)
3778                         skb->ip_summed = CHECKSUM_NONE;
3779                 else
3780                         skb->csum_level--;
3781         }
3782 }
3783 
3784 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
3785 {
3786         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3787                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3788                         skb->csum_level++;
3789         } else if (skb->ip_summed == CHECKSUM_NONE) {
3790                 skb->ip_summed = CHECKSUM_UNNECESSARY;
3791                 skb->csum_level = 0;
3792         }
3793 }
3794 
3795 /* Check if we need to perform checksum complete validation.
3796  *
3797  * Returns true if checksum complete is needed, false otherwise
3798  * (either checksum is unnecessary or zero checksum is allowed).
3799  */
3800 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3801                                                   bool zero_okay,
3802                                                   __sum16 check)
3803 {
3804         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3805                 skb->csum_valid = 1;
3806                 __skb_decr_checksum_unnecessary(skb);
3807                 return false;
3808         }
3809 
3810         return true;
3811 }
3812 
3813 /* For small packets <= CHECKSUM_BREAK perform checksum complete directly
3814  * in checksum_init.
3815  */
3816 #define CHECKSUM_BREAK 76
3817 
3818 /* Unset checksum-complete
3819  *
3820  * Unset checksum complete can be done when packet is being modified
3821  * (uncompressed for instance) and checksum-complete value is
3822  * invalidated.
3823  */
3824 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3825 {
3826         if (skb->ip_summed == CHECKSUM_COMPLETE)
3827                 skb->ip_summed = CHECKSUM_NONE;
3828 }
3829 
3830 /* Validate (init) checksum based on checksum complete.
3831  *
3832  * Return values:
3833  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
3834  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3835  *      checksum is stored in skb->csum for use in __skb_checksum_complete
3836  *   non-zero: value of invalid checksum
3837  *
3838  */
3839 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3840                                                        bool complete,
3841                                                        __wsum psum)
3842 {
3843         if (skb->ip_summed == CHECKSUM_COMPLETE) {
3844                 if (!csum_fold(csum_add(psum, skb->csum))) {
3845                         skb->csum_valid = 1;
3846                         return 0;
3847                 }
3848         }
3849 
3850         skb->csum = psum;
3851 
3852         if (complete || skb->len <= CHECKSUM_BREAK) {
3853                 __sum16 csum;
3854 
3855                 csum = __skb_checksum_complete(skb);
3856                 skb->csum_valid = !csum;
3857                 return csum;
3858         }
3859 
3860         return 0;
3861 }
3862 
3863 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3864 {
3865         return 0;
3866 }
3867 
3868 /* Perform checksum validate (init). Note that this is a macro since we only
3869  * want to calculate the pseudo header which is an input function if necessary.
3870  * First we try to validate without any computation (checksum unnecessary) and
3871  * then calculate based on checksum complete calling the function to compute
3872  * pseudo header.
3873  *
3874  * Return values:
3875  *   0: checksum is validated or try to in skb_checksum_complete
3876  *   non-zero: value of invalid checksum
3877  */
3878 #define __skb_checksum_validate(skb, proto, complete,                   \
3879                                 zero_okay, check, compute_pseudo)       \
3880 ({                                                                      \
3881         __sum16 __ret = 0;                                              \
3882         skb->csum_valid = 0;                                            \
3883         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3884                 __ret = __skb_checksum_validate_complete(skb,           \
3885                                 complete, compute_pseudo(skb, proto));  \
3886         __ret;                                                          \
3887 })
3888 
3889 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3890         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3891 
3892 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3893         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3894 
3895 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3896         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3897 
3898 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3899                                          compute_pseudo)                \
3900         __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3901 
3902 #define skb_checksum_simple_validate(skb)                               \
3903         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3904 
3905 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3906 {
3907         return (skb->ip_summed == CHECKSUM_NONE && skb->csum_valid);
3908 }
3909 
3910 static inline void __skb_checksum_convert(struct sk_buff *skb,
3911                                           __sum16 check, __wsum pseudo)
3912 {
3913         skb->csum = ~pseudo;
3914         skb->ip_summed = CHECKSUM_COMPLETE;
3915 }
3916 
3917 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3918 do {                                                                    \
3919         if (__skb_checksum_convert_check(skb))                          \
3920                 __skb_checksum_convert(skb, check,                      \
3921                                        compute_pseudo(skb, proto));     \
3922 } while (0)
3923 
3924 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3925                                               u16 start, u16 offset)
3926 {
3927         skb->ip_summed = CHECKSUM_PARTIAL;
3928         skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3929         skb->csum_offset = offset - start;
3930 }
3931 
3932 /* Update skbuf and packet to reflect the remote checksum offload operation.
3933  * When called, ptr indicates the starting point for skb->csum when
3934  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3935  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3936  */
3937 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3938                                        int start, int offset, bool nopartial)
3939 {
3940         __wsum delta;
3941 
3942         if (!nopartial) {
3943                 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3944                 return;
3945         }
3946 
3947          if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3948                 __skb_checksum_complete(skb);
3949                 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3950         }
3951 
3952         delta = remcsum_adjust(ptr, skb->csum, start, offset);
3953 
3954         /* Adjust skb->csum since we changed the packet */
3955         skb->csum = csum_add(skb->csum, delta);
3956 }
3957 
3958 static inline struct nf_conntrack *skb_nfct(const struct sk_buff *skb)
3959 {
3960 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3961         return (void *)(skb->_nfct & SKB_NFCT_PTRMASK);
3962 #else
3963         return NULL;
3964 #endif
3965 }
3966 
3967 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3968 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3969 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3970 {
3971         if (nfct && atomic_dec_and_test(&nfct->use))
3972                 nf_conntrack_destroy(nfct);
3973 }
3974 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3975 {
3976         if (nfct)
3977                 atomic_inc(&nfct->use);
3978 }
3979 #endif
3980 
3981 #ifdef CONFIG_SKB_EXTENSIONS
3982 enum skb_ext_id {
3983 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3984         SKB_EXT_BRIDGE_NF,
3985 #endif
3986 #ifdef CONFIG_XFRM
3987         SKB_EXT_SEC_PATH,
3988 #endif
3989         SKB_EXT_NUM, /* must be last */
3990 };
3991 
3992 /**
3993  *      struct skb_ext - sk_buff extensions
3994  *      @refcnt: 1 on allocation, deallocated on 0
3995  *      @offset: offset to add to @data to obtain extension address
3996  *      @chunks: size currently allocated, stored in SKB_EXT_ALIGN_SHIFT units
3997  *      @data: start of extension data, variable sized
3998  *
3999  *      Note: offsets/lengths are stored in chunks of 8 bytes, this allows
4000  *      to use 'u8' types while allowing up to 2kb worth of extension data.
4001  */
4002 struct skb_ext {
4003         refcount_t refcnt;
4004         u8 offset[SKB_EXT_NUM]; /* in chunks of 8 bytes */
4005         u8 chunks;              /* same */
4006         char data[0] __aligned(8);
4007 };
4008 
4009 void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id);
4010 void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id);
4011 void __skb_ext_put(struct skb_ext *ext);
4012 
4013 static inline void skb_ext_put(struct sk_buff *skb)
4014 {
4015         if (skb->active_extensions)
4016                 __skb_ext_put(skb->extensions);
4017 }
4018 
4019 static inline void __skb_ext_copy(struct sk_buff *dst,
4020                                   const struct sk_buff *src)
4021 {
4022         dst->active_extensions = src->active_extensions;
4023 
4024         if (src->active_extensions) {
4025                 struct skb_ext *ext = src->extensions;
4026 
4027                 refcount_inc(&ext->refcnt);
4028                 dst->extensions = ext;
4029         }
4030 }
4031 
4032 static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *src)
4033 {
4034         skb_ext_put(dst);
4035         __skb_ext_copy(dst, src);
4036 }
4037 
4038 static inline bool __skb_ext_exist(const struct skb_ext *ext, enum skb_ext_id i)
4039 {
4040         return !!ext->offset[i];
4041 }
4042 
4043 static inline bool skb_ext_exist(const struct sk_buff *skb, enum skb_ext_id id)
4044 {
4045         return skb->active_extensions & (1 << id);
4046 }
4047 
4048 static inline void skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
4049 {
4050         if (skb_ext_exist(skb, id))
4051                 __skb_ext_del(skb, id);
4052 }
4053 
4054 static inline void *skb_ext_find(const struct sk_buff *skb, enum skb_ext_id id)
4055 {
4056         if (skb_ext_exist(skb, id)) {
4057                 struct skb_ext *ext = skb->extensions;
4058 
4059                 return (void *)ext + (ext->offset[id] << 3);
4060         }
4061 
4062         return NULL;
4063 }
4064 #else
4065 static inline void skb_ext_put(struct sk_buff *skb) {}
4066 static inline void skb_ext_del(struct sk_buff *skb, int unused) {}
4067 static inline void __skb_ext_copy(struct sk_buff *d, const struct sk_buff *s) {}
4068 static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *s) {}
4069 #endif /* CONFIG_SKB_EXTENSIONS */
4070 
4071 static inline void nf_reset(struct sk_buff *skb)
4072 {
4073 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
4074         nf_conntrack_put(skb_nfct(skb));
4075         skb->_nfct = 0;
4076 #endif
4077 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4078         skb_ext_del(skb, SKB_EXT_BRIDGE_NF);
4079 #endif
4080 }
4081 
4082 static inline void nf_reset_trace(struct sk_buff *skb)
4083 {
4084 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
4085         skb->nf_trace = 0;
4086 #endif
4087 }
4088 
4089 static inline void ipvs_reset(struct sk_buff *skb)
4090 {
4091 #if IS_ENABLED(CONFIG_IP_VS)
4092         skb->ipvs_property = 0;
4093 #endif
4094 }
4095 
4096 /* Note: This doesn't put any conntrack info in dst. */
4097 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
4098                              bool copy)
4099 {
4100 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
4101         dst->_nfct = src->_nfct;
4102         nf_conntrack_get(skb_nfct(src));
4103 #endif
4104 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
4105         if (copy)
4106                 dst->nf_trace = src->nf_trace;
4107 #endif
4108 }
4109 
4110 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
4111 {
4112 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
4113         nf_conntrack_put(skb_nfct(dst));
4114 #endif
4115         __nf_copy(dst, src, true);
4116 }
4117 
4118 #ifdef CONFIG_NETWORK_SECMARK
4119 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
4120 {
4121         to->secmark = from->secmark;
4122 }
4123 
4124 static inline void skb_init_secmark(struct sk_buff *skb)
4125 {
4126         skb->secmark = 0;
4127 }
4128 #else
4129 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
4130 { }
4131 
4132 static inline void skb_init_secmark(struct sk_buff *skb)
4133 { }
4134 #endif
4135 
4136 static inline int secpath_exists(const struct sk_buff *skb)
4137 {
4138 #ifdef CONFIG_XFRM
4139         return skb_ext_exist(skb, SKB_EXT_SEC_PATH);
4140 #else
4141         return 0;
4142 #endif
4143 }
4144 
4145 static inline bool skb_irq_freeable(const struct sk_buff *skb)
4146 {
4147         return !skb->destructor &&
4148                 !secpath_exists(skb) &&
4149                 !skb_nfct(skb) &&
4150                 !skb->_skb_refdst &&
4151                 !skb_has_frag_list(skb);
4152 }
4153 
4154 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
4155 {
4156         skb->queue_mapping = queue_mapping;
4157 }
4158 
4159 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
4160 {
4161         return skb->queue_mapping;
4162 }
4163 
4164 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
4165 {
4166         to->queue_mapping = from->queue_mapping;
4167 }
4168 
4169 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
4170 {
4171         skb->queue_mapping = rx_queue + 1;
4172 }
4173 
4174 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
4175 {
4176         return skb->queue_mapping - 1;
4177 }
4178 
4179 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
4180 {
4181         return skb->queue_mapping != 0;
4182 }
4183 
4184 static inline void skb_set_dst_pending_confirm(struct sk_buff *skb, u32 val)
4185 {
4186         skb->dst_pending_confirm = val;
4187 }
4188 
4189 static inline bool skb_get_dst_pending_confirm(const struct sk_buff *skb)
4190 {
4191         return skb->dst_pending_confirm != 0;
4192 }
4193 
4194 static inline struct sec_path *skb_sec_path(const struct sk_buff *skb)
4195 {
4196 #ifdef CONFIG_XFRM
4197         return skb_ext_find(skb, SKB_EXT_SEC_PATH);
4198 #else
4199         return NULL;
4200 #endif
4201 }
4202 
4203 /* Keeps track of mac header offset relative to skb->head.
4204  * It is useful for TSO of Tunneling protocol. e.g. GRE.
4205  * For non-tunnel skb it points to skb_mac_header() and for
4206  * tunnel skb it points to outer mac header.
4207  * Keeps track of level of encapsulation of network headers.
4208  */
4209 struct skb_gso_cb {
4210         union {
4211                 int     mac_offset;
4212                 int     data_offset;
4213         };
4214         int     encap_level;
4215         __wsum  csum;
4216         __u16   csum_start;
4217 };
4218 #define SKB_SGO_CB_OFFSET       32
4219 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
4220 
4221 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
4222 {
4223         return (skb_mac_header(inner_skb) - inner_skb->head) -
4224                 SKB_GSO_CB(inner_skb)->mac_offset;
4225 }
4226 
4227 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
4228 {
4229         int new_headroom, headroom;
4230         int ret;
4231 
4232         headroom = skb_headroom(skb);
4233         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
4234         if (ret)
4235                 return ret;
4236 
4237         new_headroom = skb_headroom(skb);
4238         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
4239         return 0;
4240 }
4241 
4242 static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
4243 {
4244         /* Do not update partial checksums if remote checksum is enabled. */
4245         if (skb->remcsum_offload)
4246                 return;
4247 
4248         SKB_GSO_CB(skb)->csum = res;
4249         SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
4250 }
4251 
4252 /* Compute the checksum for a gso segment. First compute the checksum value
4253  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
4254  * then add in skb->csum (checksum from csum_start to end of packet).
4255  * skb->csum and csum_start are then updated to reflect the checksum of the
4256  * resultant packet starting from the transport header-- the resultant checksum
4257  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
4258  * header.
4259  */
4260 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
4261 {
4262         unsigned char *csum_start = skb_transport_header(skb);
4263         int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
4264         __wsum partial = SKB_GSO_CB(skb)->csum;
4265 
4266         SKB_GSO_CB(skb)->csum = res;
4267         SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
4268 
4269         return csum_fold(csum_partial(csum_start, plen, partial));
4270 }
4271 
4272 static inline bool skb_is_gso(const struct sk_buff *skb)
4273 {
4274         return skb_shinfo(skb)->gso_size;
4275 }
4276 
4277 /* Note: Should be called only if skb_is_gso(skb) is true */
4278 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
4279 {
4280         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
4281 }
4282 
4283 /* Note: Should be called only if skb_is_gso(skb) is true */
4284 static inline bool skb_is_gso_sctp(const struct sk_buff *skb)
4285 {
4286         return skb_shinfo(skb)->gso_type & SKB_GSO_SCTP;
4287 }
4288 
4289 /* Note: Should be called only if skb_is_gso(skb) is true */
4290 static inline bool skb_is_gso_tcp(const struct sk_buff *skb)
4291 {
4292         return skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6);
4293 }
4294 
4295 static inline void skb_gso_reset(struct sk_buff *skb)
4296 {
4297         skb_shinfo(skb)->gso_size = 0;
4298         skb_shinfo(skb)->gso_segs = 0;
4299         skb_shinfo(skb)->gso_type = 0;
4300 }
4301 
4302 static inline void skb_increase_gso_size(struct skb_shared_info *shinfo,
4303                                          u16 increment)
4304 {
4305         if (WARN_ON_ONCE(shinfo->gso_size == GSO_BY_FRAGS))
4306                 return;
4307         shinfo->gso_size += increment;
4308 }
4309 
4310 static inline void skb_decrease_gso_size(struct skb_shared_info *shinfo,
4311                                          u16 decrement)
4312 {
4313         if (WARN_ON_ONCE(shinfo->gso_size == GSO_BY_FRAGS))
4314                 return;
4315         shinfo->gso_size -= decrement;
4316 }
4317 
4318 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
4319 
4320 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
4321 {
4322         /* LRO sets gso_size but not gso_type, whereas if GSO is really
4323          * wanted then gso_type will be set. */
4324         const struct skb_shared_info *shinfo = skb_shinfo(skb);
4325 
4326         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
4327             unlikely(shinfo->gso_type == 0)) {
4328                 __skb_warn_lro_forwarding(skb);
4329                 return true;
4330         }
4331         return false;
4332 }
4333 
4334 static inline void skb_forward_csum(struct sk_buff *skb)
4335 {
4336         /* Unfortunately we don't support this one.  Any brave souls? */
4337         if (skb->ip_summed == CHECKSUM_COMPLETE)
4338                 skb->ip_summed = CHECKSUM_NONE;
4339 }
4340 
4341 /**
4342  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
4343  * @skb: skb to check
4344  *
4345  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
4346  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
4347  * use this helper, to document places where we make this assertion.
4348  */
4349 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
4350 {
4351 #ifdef DEBUG
4352         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
4353 #endif
4354 }
4355 
4356 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
4357 
4358 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
4359 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
4360                                      unsigned int transport_len,
4361                                      __sum16(*skb_chkf)(struct sk_buff *skb));
4362 
4363 /**
4364  * skb_head_is_locked - Determine if the skb->head is locked down
4365  * @skb: skb to check
4366  *
4367  * The head on skbs build around a head frag can be removed if they are
4368  * not cloned.  This function returns true if the skb head is locked down
4369  * due to either being allocated via kmalloc, or by being a clone with
4370  * multiple references to the head.
4371  */
4372 static inline bool skb_head_is_locked(const struct sk_buff *skb)
4373 {
4374         return !skb->head_frag || skb_cloned(skb);
4375 }
4376 
4377 /* Local Checksum Offload.
4378  * Compute outer checksum based on the assumption that the
4379  * inner checksum will be offloaded later.
4380  * See Documentation/networking/checksum-offloads.rst for
4381  * explanation of how this works.
4382  * Fill in outer checksum adjustment (e.g. with sum of outer
4383  * pseudo-header) before calling.
4384  * Also ensure that inner checksum is in linear data area.
4385  */
4386 static inline __wsum lco_csum(struct sk_buff *skb)
4387 {
4388         unsigned char *csum_start = skb_checksum_start(skb);
4389         unsigned char *l4_hdr = skb_transport_header(skb);
4390         __wsum partial;
4391 
4392         /* Start with complement of inner checksum adjustment */
4393         partial = ~csum_unfold(*(__force __sum16 *)(csum_start +
4394                                                     skb->csum_offset));
4395 
4396         /* Add in checksum of our headers (incl. outer checksum
4397          * adjustment filled in by caller) and return result.
4398          */
4399         return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
4400 }
4401 
4402 #endif  /* __KERNEL__ */
4403 #endif  /* _LINUX_SKBUFF_H */
4404 

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