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

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