Version:  2.0.40 2.2.26 2.4.37 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16

Linux/include/linux/skbuff.h

  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 
 24 #include <linux/atomic.h>
 25 #include <asm/types.h>
 26 #include <linux/spinlock.h>
 27 #include <linux/net.h>
 28 #include <linux/textsearch.h>
 29 #include <net/checksum.h>
 30 #include <linux/rcupdate.h>
 31 #include <linux/dmaengine.h>
 32 #include <linux/hrtimer.h>
 33 #include <linux/dma-mapping.h>
 34 #include <linux/netdev_features.h>
 35 #include <linux/sched.h>
 36 #include <net/flow_keys.h>
 37 
 38 /* A. Checksumming of received packets by device.
 39  *
 40  * CHECKSUM_NONE:
 41  *
 42  *   Device failed to checksum this packet e.g. due to lack of capabilities.
 43  *   The packet contains full (though not verified) checksum in packet but
 44  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 45  *
 46  * CHECKSUM_UNNECESSARY:
 47  *
 48  *   The hardware you're dealing with doesn't calculate the full checksum
 49  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
 50  *   for specific protocols e.g. TCP/UDP/SCTP, then, for such packets it will
 51  *   set CHECKSUM_UNNECESSARY if their checksums are okay. skb->csum is still
 52  *   undefined in this case though. It is a bad option, but, unfortunately,
 53  *   nowadays most vendors do this. Apparently with the secret goal to sell
 54  *   you new devices, when you will add new protocol to your host, f.e. IPv6 8)
 55  *
 56  * CHECKSUM_COMPLETE:
 57  *
 58  *   This is the most generic way. The device supplied checksum of the _whole_
 59  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
 60  *   hardware doesn't need to parse L3/L4 headers to implement this.
 61  *
 62  *   Note: Even if device supports only some protocols, but is able to produce
 63  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
 64  *
 65  * CHECKSUM_PARTIAL:
 66  *
 67  *   This is identical to the case for output below. This may occur on a packet
 68  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
 69  *   on the same host. The packet can be treated in the same way as
 70  *   CHECKSUM_UNNECESSARY, except that on output (i.e., forwarding) the
 71  *   checksum must be filled in by the OS or the hardware.
 72  *
 73  * B. Checksumming on output.
 74  *
 75  * CHECKSUM_NONE:
 76  *
 77  *   The skb was already checksummed by the protocol, or a checksum is not
 78  *   required.
 79  *
 80  * CHECKSUM_PARTIAL:
 81  *
 82  *   The device is required to checksum the packet as seen by hard_start_xmit()
 83  *   from skb->csum_start up to the end, and to record/write the checksum at
 84  *   offset skb->csum_start + skb->csum_offset.
 85  *
 86  *   The device must show its capabilities in dev->features, set up at device
 87  *   setup time, e.g. netdev_features.h:
 88  *
 89  *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
 90  *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
 91  *                        IPv4. Sigh. Vendors like this way for an unknown reason.
 92  *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
 93  *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
 94  *      NETIF_F_...     - Well, you get the picture.
 95  *
 96  * CHECKSUM_UNNECESSARY:
 97  *
 98  *   Normally, the device will do per protocol specific checksumming. Protocol
 99  *   implementations that do not want the NIC to perform the checksum
100  *   calculation should use this flag in their outgoing skbs.
101  *
102  *      NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
103  *                         offload. Correspondingly, the FCoE protocol driver
104  *                         stack should use CHECKSUM_UNNECESSARY.
105  *
106  * Any questions? No questions, good.           --ANK
107  */
108 
109 /* Don't change this without changing skb_csum_unnecessary! */
110 #define CHECKSUM_NONE           0
111 #define CHECKSUM_UNNECESSARY    1
112 #define CHECKSUM_COMPLETE       2
113 #define CHECKSUM_PARTIAL        3
114 
115 #define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
116                                  ~(SMP_CACHE_BYTES - 1))
117 #define SKB_WITH_OVERHEAD(X)    \
118         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
119 #define SKB_MAX_ORDER(X, ORDER) \
120         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
121 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
122 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
123 
124 /* return minimum truesize of one skb containing X bytes of data */
125 #define SKB_TRUESIZE(X) ((X) +                                          \
126                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
127                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
128 
129 struct net_device;
130 struct scatterlist;
131 struct pipe_inode_info;
132 
133 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
134 struct nf_conntrack {
135         atomic_t use;
136 };
137 #endif
138 
139 #ifdef CONFIG_BRIDGE_NETFILTER
140 struct nf_bridge_info {
141         atomic_t                use;
142         unsigned int            mask;
143         struct net_device       *physindev;
144         struct net_device       *physoutdev;
145         unsigned long           data[32 / sizeof(unsigned long)];
146 };
147 #endif
148 
149 struct sk_buff_head {
150         /* These two members must be first. */
151         struct sk_buff  *next;
152         struct sk_buff  *prev;
153 
154         __u32           qlen;
155         spinlock_t      lock;
156 };
157 
158 struct sk_buff;
159 
160 /* To allow 64K frame to be packed as single skb without frag_list we
161  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
162  * buffers which do not start on a page boundary.
163  *
164  * Since GRO uses frags we allocate at least 16 regardless of page
165  * size.
166  */
167 #if (65536/PAGE_SIZE + 1) < 16
168 #define MAX_SKB_FRAGS 16UL
169 #else
170 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
171 #endif
172 
173 typedef struct skb_frag_struct skb_frag_t;
174 
175 struct skb_frag_struct {
176         struct {
177                 struct page *p;
178         } page;
179 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
180         __u32 page_offset;
181         __u32 size;
182 #else
183         __u16 page_offset;
184         __u16 size;
185 #endif
186 };
187 
188 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
189 {
190         return frag->size;
191 }
192 
193 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
194 {
195         frag->size = size;
196 }
197 
198 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
199 {
200         frag->size += delta;
201 }
202 
203 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
204 {
205         frag->size -= delta;
206 }
207 
208 #define HAVE_HW_TIME_STAMP
209 
210 /**
211  * struct skb_shared_hwtstamps - hardware time stamps
212  * @hwtstamp:   hardware time stamp transformed into duration
213  *              since arbitrary point in time
214  * @syststamp:  hwtstamp transformed to system time base
215  *
216  * Software time stamps generated by ktime_get_real() are stored in
217  * skb->tstamp. The relation between the different kinds of time
218  * stamps is as follows:
219  *
220  * syststamp and tstamp can be compared against each other in
221  * arbitrary combinations.  The accuracy of a
222  * syststamp/tstamp/"syststamp from other device" comparison is
223  * limited by the accuracy of the transformation into system time
224  * base. This depends on the device driver and its underlying
225  * hardware.
226  *
227  * hwtstamps can only be compared against other hwtstamps from
228  * the same device.
229  *
230  * This structure is attached to packets as part of the
231  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
232  */
233 struct skb_shared_hwtstamps {
234         ktime_t hwtstamp;
235         ktime_t syststamp;
236 };
237 
238 /* Definitions for tx_flags in struct skb_shared_info */
239 enum {
240         /* generate hardware time stamp */
241         SKBTX_HW_TSTAMP = 1 << 0,
242 
243         /* generate software time stamp */
244         SKBTX_SW_TSTAMP = 1 << 1,
245 
246         /* device driver is going to provide hardware time stamp */
247         SKBTX_IN_PROGRESS = 1 << 2,
248 
249         /* device driver supports TX zero-copy buffers */
250         SKBTX_DEV_ZEROCOPY = 1 << 3,
251 
252         /* generate wifi status information (where possible) */
253         SKBTX_WIFI_STATUS = 1 << 4,
254 
255         /* This indicates at least one fragment might be overwritten
256          * (as in vmsplice(), sendfile() ...)
257          * If we need to compute a TX checksum, we'll need to copy
258          * all frags to avoid possible bad checksum
259          */
260         SKBTX_SHARED_FRAG = 1 << 5,
261 };
262 
263 /*
264  * The callback notifies userspace to release buffers when skb DMA is done in
265  * lower device, the skb last reference should be 0 when calling this.
266  * The zerocopy_success argument is true if zero copy transmit occurred,
267  * false on data copy or out of memory error caused by data copy attempt.
268  * The ctx field is used to track device context.
269  * The desc field is used to track userspace buffer index.
270  */
271 struct ubuf_info {
272         void (*callback)(struct ubuf_info *, bool zerocopy_success);
273         void *ctx;
274         unsigned long desc;
275 };
276 
277 /* This data is invariant across clones and lives at
278  * the end of the header data, ie. at skb->end.
279  */
280 struct skb_shared_info {
281         unsigned char   nr_frags;
282         __u8            tx_flags;
283         unsigned short  gso_size;
284         /* Warning: this field is not always filled in (UFO)! */
285         unsigned short  gso_segs;
286         unsigned short  gso_type;
287         struct sk_buff  *frag_list;
288         struct skb_shared_hwtstamps hwtstamps;
289         __be32          ip6_frag_id;
290 
291         /*
292          * Warning : all fields before dataref are cleared in __alloc_skb()
293          */
294         atomic_t        dataref;
295 
296         /* Intermediate layers must ensure that destructor_arg
297          * remains valid until skb destructor */
298         void *          destructor_arg;
299 
300         /* must be last field, see pskb_expand_head() */
301         skb_frag_t      frags[MAX_SKB_FRAGS];
302 };
303 
304 /* We divide dataref into two halves.  The higher 16 bits hold references
305  * to the payload part of skb->data.  The lower 16 bits hold references to
306  * the entire skb->data.  A clone of a headerless skb holds the length of
307  * the header in skb->hdr_len.
308  *
309  * All users must obey the rule that the skb->data reference count must be
310  * greater than or equal to the payload reference count.
311  *
312  * Holding a reference to the payload part means that the user does not
313  * care about modifications to the header part of skb->data.
314  */
315 #define SKB_DATAREF_SHIFT 16
316 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
317 
318 
319 enum {
320         SKB_FCLONE_UNAVAILABLE,
321         SKB_FCLONE_ORIG,
322         SKB_FCLONE_CLONE,
323 };
324 
325 enum {
326         SKB_GSO_TCPV4 = 1 << 0,
327         SKB_GSO_UDP = 1 << 1,
328 
329         /* This indicates the skb is from an untrusted source. */
330         SKB_GSO_DODGY = 1 << 2,
331 
332         /* This indicates the tcp segment has CWR set. */
333         SKB_GSO_TCP_ECN = 1 << 3,
334 
335         SKB_GSO_TCPV6 = 1 << 4,
336 
337         SKB_GSO_FCOE = 1 << 5,
338 
339         SKB_GSO_GRE = 1 << 6,
340 
341         SKB_GSO_GRE_CSUM = 1 << 7,
342 
343         SKB_GSO_IPIP = 1 << 8,
344 
345         SKB_GSO_SIT = 1 << 9,
346 
347         SKB_GSO_UDP_TUNNEL = 1 << 10,
348 
349         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
350 
351         SKB_GSO_MPLS = 1 << 12,
352 
353 };
354 
355 #if BITS_PER_LONG > 32
356 #define NET_SKBUFF_DATA_USES_OFFSET 1
357 #endif
358 
359 #ifdef NET_SKBUFF_DATA_USES_OFFSET
360 typedef unsigned int sk_buff_data_t;
361 #else
362 typedef unsigned char *sk_buff_data_t;
363 #endif
364 
365 /**
366  * struct skb_mstamp - multi resolution time stamps
367  * @stamp_us: timestamp in us resolution
368  * @stamp_jiffies: timestamp in jiffies
369  */
370 struct skb_mstamp {
371         union {
372                 u64             v64;
373                 struct {
374                         u32     stamp_us;
375                         u32     stamp_jiffies;
376                 };
377         };
378 };
379 
380 /**
381  * skb_mstamp_get - get current timestamp
382  * @cl: place to store timestamps
383  */
384 static inline void skb_mstamp_get(struct skb_mstamp *cl)
385 {
386         u64 val = local_clock();
387 
388         do_div(val, NSEC_PER_USEC);
389         cl->stamp_us = (u32)val;
390         cl->stamp_jiffies = (u32)jiffies;
391 }
392 
393 /**
394  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
395  * @t1: pointer to newest sample
396  * @t0: pointer to oldest sample
397  */
398 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
399                                       const struct skb_mstamp *t0)
400 {
401         s32 delta_us = t1->stamp_us - t0->stamp_us;
402         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
403 
404         /* If delta_us is negative, this might be because interval is too big,
405          * or local_clock() drift is too big : fallback using jiffies.
406          */
407         if (delta_us <= 0 ||
408             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
409 
410                 delta_us = jiffies_to_usecs(delta_jiffies);
411 
412         return delta_us;
413 }
414 
415 
416 /** 
417  *      struct sk_buff - socket buffer
418  *      @next: Next buffer in list
419  *      @prev: Previous buffer in list
420  *      @tstamp: Time we arrived/left
421  *      @sk: Socket we are owned by
422  *      @dev: Device we arrived on/are leaving by
423  *      @cb: Control buffer. Free for use by every layer. Put private vars here
424  *      @_skb_refdst: destination entry (with norefcount bit)
425  *      @sp: the security path, used for xfrm
426  *      @len: Length of actual data
427  *      @data_len: Data length
428  *      @mac_len: Length of link layer header
429  *      @hdr_len: writable header length of cloned skb
430  *      @csum: Checksum (must include start/offset pair)
431  *      @csum_start: Offset from skb->head where checksumming should start
432  *      @csum_offset: Offset from csum_start where checksum should be stored
433  *      @priority: Packet queueing priority
434  *      @ignore_df: allow local fragmentation
435  *      @cloned: Head may be cloned (check refcnt to be sure)
436  *      @ip_summed: Driver fed us an IP checksum
437  *      @nohdr: Payload reference only, must not modify header
438  *      @nfctinfo: Relationship of this skb to the connection
439  *      @pkt_type: Packet class
440  *      @fclone: skbuff clone status
441  *      @ipvs_property: skbuff is owned by ipvs
442  *      @peeked: this packet has been seen already, so stats have been
443  *              done for it, don't do them again
444  *      @nf_trace: netfilter packet trace flag
445  *      @protocol: Packet protocol from driver
446  *      @destructor: Destruct function
447  *      @nfct: Associated connection, if any
448  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
449  *      @skb_iif: ifindex of device we arrived on
450  *      @tc_index: Traffic control index
451  *      @tc_verd: traffic control verdict
452  *      @hash: the packet hash
453  *      @queue_mapping: Queue mapping for multiqueue devices
454  *      @ndisc_nodetype: router type (from link layer)
455  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
456  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
457  *              ports.
458  *      @wifi_acked_valid: wifi_acked was set
459  *      @wifi_acked: whether frame was acked on wifi or not
460  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
461  *      @dma_cookie: a cookie to one of several possible DMA operations
462  *              done by skb DMA functions
463   *     @napi_id: id of the NAPI struct this skb came from
464  *      @secmark: security marking
465  *      @mark: Generic packet mark
466  *      @dropcount: total number of sk_receive_queue overflows
467  *      @vlan_proto: vlan encapsulation protocol
468  *      @vlan_tci: vlan tag control information
469  *      @inner_protocol: Protocol (encapsulation)
470  *      @inner_transport_header: Inner transport layer header (encapsulation)
471  *      @inner_network_header: Network layer header (encapsulation)
472  *      @inner_mac_header: Link layer header (encapsulation)
473  *      @transport_header: Transport layer header
474  *      @network_header: Network layer header
475  *      @mac_header: Link layer header
476  *      @tail: Tail pointer
477  *      @end: End pointer
478  *      @head: Head of buffer
479  *      @data: Data head pointer
480  *      @truesize: Buffer size
481  *      @users: User count - see {datagram,tcp}.c
482  */
483 
484 struct sk_buff {
485         /* These two members must be first. */
486         struct sk_buff          *next;
487         struct sk_buff          *prev;
488 
489         union {
490                 ktime_t         tstamp;
491                 struct skb_mstamp skb_mstamp;
492         };
493 
494         struct sock             *sk;
495         struct net_device       *dev;
496 
497         /*
498          * This is the control buffer. It is free to use for every
499          * layer. Please put your private variables there. If you
500          * want to keep them across layers you have to do a skb_clone()
501          * first. This is owned by whoever has the skb queued ATM.
502          */
503         char                    cb[48] __aligned(8);
504 
505         unsigned long           _skb_refdst;
506 #ifdef CONFIG_XFRM
507         struct  sec_path        *sp;
508 #endif
509         unsigned int            len,
510                                 data_len;
511         __u16                   mac_len,
512                                 hdr_len;
513         union {
514                 __wsum          csum;
515                 struct {
516                         __u16   csum_start;
517                         __u16   csum_offset;
518                 };
519         };
520         __u32                   priority;
521         kmemcheck_bitfield_begin(flags1);
522         __u8                    ignore_df:1,
523                                 cloned:1,
524                                 ip_summed:2,
525                                 nohdr:1,
526                                 nfctinfo:3;
527         __u8                    pkt_type:3,
528                                 fclone:2,
529                                 ipvs_property:1,
530                                 peeked:1,
531                                 nf_trace:1;
532         kmemcheck_bitfield_end(flags1);
533         __be16                  protocol;
534 
535         void                    (*destructor)(struct sk_buff *skb);
536 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
537         struct nf_conntrack     *nfct;
538 #endif
539 #ifdef CONFIG_BRIDGE_NETFILTER
540         struct nf_bridge_info   *nf_bridge;
541 #endif
542 
543         int                     skb_iif;
544 
545         __u32                   hash;
546 
547         __be16                  vlan_proto;
548         __u16                   vlan_tci;
549 
550 #ifdef CONFIG_NET_SCHED
551         __u16                   tc_index;       /* traffic control index */
552 #ifdef CONFIG_NET_CLS_ACT
553         __u16                   tc_verd;        /* traffic control verdict */
554 #endif
555 #endif
556 
557         __u16                   queue_mapping;
558         kmemcheck_bitfield_begin(flags2);
559 #ifdef CONFIG_IPV6_NDISC_NODETYPE
560         __u8                    ndisc_nodetype:2;
561 #endif
562         __u8                    pfmemalloc:1;
563         __u8                    ooo_okay:1;
564         __u8                    l4_hash:1;
565         __u8                    wifi_acked_valid:1;
566         __u8                    wifi_acked:1;
567         __u8                    no_fcs:1;
568         __u8                    head_frag:1;
569         /* Encapsulation protocol and NIC drivers should use
570          * this flag to indicate to each other if the skb contains
571          * encapsulated packet or not and maybe use the inner packet
572          * headers if needed
573          */
574         __u8                    encapsulation:1;
575         __u8                    encap_hdr_csum:1;
576         __u8                    csum_valid:1;
577         __u8                    csum_complete_sw:1;
578         /* 3/5 bit hole (depending on ndisc_nodetype presence) */
579         kmemcheck_bitfield_end(flags2);
580 
581 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
582         union {
583                 unsigned int    napi_id;
584                 dma_cookie_t    dma_cookie;
585         };
586 #endif
587 #ifdef CONFIG_NETWORK_SECMARK
588         __u32                   secmark;
589 #endif
590         union {
591                 __u32           mark;
592                 __u32           dropcount;
593                 __u32           reserved_tailroom;
594         };
595 
596         __be16                  inner_protocol;
597         __u16                   inner_transport_header;
598         __u16                   inner_network_header;
599         __u16                   inner_mac_header;
600         __u16                   transport_header;
601         __u16                   network_header;
602         __u16                   mac_header;
603         /* These elements must be at the end, see alloc_skb() for details.  */
604         sk_buff_data_t          tail;
605         sk_buff_data_t          end;
606         unsigned char           *head,
607                                 *data;
608         unsigned int            truesize;
609         atomic_t                users;
610 };
611 
612 #ifdef __KERNEL__
613 /*
614  *      Handling routines are only of interest to the kernel
615  */
616 #include <linux/slab.h>
617 
618 
619 #define SKB_ALLOC_FCLONE        0x01
620 #define SKB_ALLOC_RX            0x02
621 
622 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
623 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
624 {
625         return unlikely(skb->pfmemalloc);
626 }
627 
628 /*
629  * skb might have a dst pointer attached, refcounted or not.
630  * _skb_refdst low order bit is set if refcount was _not_ taken
631  */
632 #define SKB_DST_NOREF   1UL
633 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
634 
635 /**
636  * skb_dst - returns skb dst_entry
637  * @skb: buffer
638  *
639  * Returns skb dst_entry, regardless of reference taken or not.
640  */
641 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
642 {
643         /* If refdst was not refcounted, check we still are in a 
644          * rcu_read_lock section
645          */
646         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
647                 !rcu_read_lock_held() &&
648                 !rcu_read_lock_bh_held());
649         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
650 }
651 
652 /**
653  * skb_dst_set - sets skb dst
654  * @skb: buffer
655  * @dst: dst entry
656  *
657  * Sets skb dst, assuming a reference was taken on dst and should
658  * be released by skb_dst_drop()
659  */
660 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
661 {
662         skb->_skb_refdst = (unsigned long)dst;
663 }
664 
665 void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
666                          bool force);
667 
668 /**
669  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
670  * @skb: buffer
671  * @dst: dst entry
672  *
673  * Sets skb dst, assuming a reference was not taken on dst.
674  * If dst entry is cached, we do not take reference and dst_release
675  * will be avoided by refdst_drop. If dst entry is not cached, we take
676  * reference, so that last dst_release can destroy the dst immediately.
677  */
678 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
679 {
680         __skb_dst_set_noref(skb, dst, false);
681 }
682 
683 /**
684  * skb_dst_set_noref_force - sets skb dst, without taking reference
685  * @skb: buffer
686  * @dst: dst entry
687  *
688  * Sets skb dst, assuming a reference was not taken on dst.
689  * No reference is taken and no dst_release will be called. While for
690  * cached dsts deferred reclaim is a basic feature, for entries that are
691  * not cached it is caller's job to guarantee that last dst_release for
692  * provided dst happens when nobody uses it, eg. after a RCU grace period.
693  */
694 static inline void skb_dst_set_noref_force(struct sk_buff *skb,
695                                            struct dst_entry *dst)
696 {
697         __skb_dst_set_noref(skb, dst, true);
698 }
699 
700 /**
701  * skb_dst_is_noref - Test if skb dst isn't refcounted
702  * @skb: buffer
703  */
704 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
705 {
706         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
707 }
708 
709 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
710 {
711         return (struct rtable *)skb_dst(skb);
712 }
713 
714 void kfree_skb(struct sk_buff *skb);
715 void kfree_skb_list(struct sk_buff *segs);
716 void skb_tx_error(struct sk_buff *skb);
717 void consume_skb(struct sk_buff *skb);
718 void  __kfree_skb(struct sk_buff *skb);
719 extern struct kmem_cache *skbuff_head_cache;
720 
721 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
722 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
723                       bool *fragstolen, int *delta_truesize);
724 
725 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
726                             int node);
727 struct sk_buff *build_skb(void *data, unsigned int frag_size);
728 static inline struct sk_buff *alloc_skb(unsigned int size,
729                                         gfp_t priority)
730 {
731         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
732 }
733 
734 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
735                                                gfp_t priority)
736 {
737         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
738 }
739 
740 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
741 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
742 {
743         return __alloc_skb_head(priority, -1);
744 }
745 
746 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
747 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
748 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
749 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
750 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
751                                    gfp_t gfp_mask, bool fclone);
752 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
753                                           gfp_t gfp_mask)
754 {
755         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
756 }
757 
758 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
759 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
760                                      unsigned int headroom);
761 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
762                                 int newtailroom, gfp_t priority);
763 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
764                         int offset, int len);
765 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
766                  int len);
767 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
768 int skb_pad(struct sk_buff *skb, int pad);
769 #define dev_kfree_skb(a)        consume_skb(a)
770 
771 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
772                             int getfrag(void *from, char *to, int offset,
773                                         int len, int odd, struct sk_buff *skb),
774                             void *from, int length);
775 
776 struct skb_seq_state {
777         __u32           lower_offset;
778         __u32           upper_offset;
779         __u32           frag_idx;
780         __u32           stepped_offset;
781         struct sk_buff  *root_skb;
782         struct sk_buff  *cur_skb;
783         __u8            *frag_data;
784 };
785 
786 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
787                           unsigned int to, struct skb_seq_state *st);
788 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
789                           struct skb_seq_state *st);
790 void skb_abort_seq_read(struct skb_seq_state *st);
791 
792 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
793                            unsigned int to, struct ts_config *config,
794                            struct ts_state *state);
795 
796 /*
797  * Packet hash types specify the type of hash in skb_set_hash.
798  *
799  * Hash types refer to the protocol layer addresses which are used to
800  * construct a packet's hash. The hashes are used to differentiate or identify
801  * flows of the protocol layer for the hash type. Hash types are either
802  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
803  *
804  * Properties of hashes:
805  *
806  * 1) Two packets in different flows have different hash values
807  * 2) Two packets in the same flow should have the same hash value
808  *
809  * A hash at a higher layer is considered to be more specific. A driver should
810  * set the most specific hash possible.
811  *
812  * A driver cannot indicate a more specific hash than the layer at which a hash
813  * was computed. For instance an L3 hash cannot be set as an L4 hash.
814  *
815  * A driver may indicate a hash level which is less specific than the
816  * actual layer the hash was computed on. For instance, a hash computed
817  * at L4 may be considered an L3 hash. This should only be done if the
818  * driver can't unambiguously determine that the HW computed the hash at
819  * the higher layer. Note that the "should" in the second property above
820  * permits this.
821  */
822 enum pkt_hash_types {
823         PKT_HASH_TYPE_NONE,     /* Undefined type */
824         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
825         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
826         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
827 };
828 
829 static inline void
830 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
831 {
832         skb->l4_hash = (type == PKT_HASH_TYPE_L4);
833         skb->hash = hash;
834 }
835 
836 void __skb_get_hash(struct sk_buff *skb);
837 static inline __u32 skb_get_hash(struct sk_buff *skb)
838 {
839         if (!skb->l4_hash)
840                 __skb_get_hash(skb);
841 
842         return skb->hash;
843 }
844 
845 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
846 {
847         return skb->hash;
848 }
849 
850 static inline void skb_clear_hash(struct sk_buff *skb)
851 {
852         skb->hash = 0;
853         skb->l4_hash = 0;
854 }
855 
856 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
857 {
858         if (!skb->l4_hash)
859                 skb_clear_hash(skb);
860 }
861 
862 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
863 {
864         to->hash = from->hash;
865         to->l4_hash = from->l4_hash;
866 };
867 
868 #ifdef NET_SKBUFF_DATA_USES_OFFSET
869 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
870 {
871         return skb->head + skb->end;
872 }
873 
874 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
875 {
876         return skb->end;
877 }
878 #else
879 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
880 {
881         return skb->end;
882 }
883 
884 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
885 {
886         return skb->end - skb->head;
887 }
888 #endif
889 
890 /* Internal */
891 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
892 
893 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
894 {
895         return &skb_shinfo(skb)->hwtstamps;
896 }
897 
898 /**
899  *      skb_queue_empty - check if a queue is empty
900  *      @list: queue head
901  *
902  *      Returns true if the queue is empty, false otherwise.
903  */
904 static inline int skb_queue_empty(const struct sk_buff_head *list)
905 {
906         return list->next == (const struct sk_buff *) list;
907 }
908 
909 /**
910  *      skb_queue_is_last - check if skb is the last entry in the queue
911  *      @list: queue head
912  *      @skb: buffer
913  *
914  *      Returns true if @skb is the last buffer on the list.
915  */
916 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
917                                      const struct sk_buff *skb)
918 {
919         return skb->next == (const struct sk_buff *) list;
920 }
921 
922 /**
923  *      skb_queue_is_first - check if skb is the first entry in the queue
924  *      @list: queue head
925  *      @skb: buffer
926  *
927  *      Returns true if @skb is the first buffer on the list.
928  */
929 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
930                                       const struct sk_buff *skb)
931 {
932         return skb->prev == (const struct sk_buff *) list;
933 }
934 
935 /**
936  *      skb_queue_next - return the next packet in the queue
937  *      @list: queue head
938  *      @skb: current buffer
939  *
940  *      Return the next packet in @list after @skb.  It is only valid to
941  *      call this if skb_queue_is_last() evaluates to false.
942  */
943 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
944                                              const struct sk_buff *skb)
945 {
946         /* This BUG_ON may seem severe, but if we just return then we
947          * are going to dereference garbage.
948          */
949         BUG_ON(skb_queue_is_last(list, skb));
950         return skb->next;
951 }
952 
953 /**
954  *      skb_queue_prev - return the prev packet in the queue
955  *      @list: queue head
956  *      @skb: current buffer
957  *
958  *      Return the prev packet in @list before @skb.  It is only valid to
959  *      call this if skb_queue_is_first() evaluates to false.
960  */
961 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
962                                              const struct sk_buff *skb)
963 {
964         /* This BUG_ON may seem severe, but if we just return then we
965          * are going to dereference garbage.
966          */
967         BUG_ON(skb_queue_is_first(list, skb));
968         return skb->prev;
969 }
970 
971 /**
972  *      skb_get - reference buffer
973  *      @skb: buffer to reference
974  *
975  *      Makes another reference to a socket buffer and returns a pointer
976  *      to the buffer.
977  */
978 static inline struct sk_buff *skb_get(struct sk_buff *skb)
979 {
980         atomic_inc(&skb->users);
981         return skb;
982 }
983 
984 /*
985  * If users == 1, we are the only owner and are can avoid redundant
986  * atomic change.
987  */
988 
989 /**
990  *      skb_cloned - is the buffer a clone
991  *      @skb: buffer to check
992  *
993  *      Returns true if the buffer was generated with skb_clone() and is
994  *      one of multiple shared copies of the buffer. Cloned buffers are
995  *      shared data so must not be written to under normal circumstances.
996  */
997 static inline int skb_cloned(const struct sk_buff *skb)
998 {
999         return skb->cloned &&
1000                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1001 }
1002 
1003 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1004 {
1005         might_sleep_if(pri & __GFP_WAIT);
1006 
1007         if (skb_cloned(skb))
1008                 return pskb_expand_head(skb, 0, 0, pri);
1009 
1010         return 0;
1011 }
1012 
1013 /**
1014  *      skb_header_cloned - is the header a clone
1015  *      @skb: buffer to check
1016  *
1017  *      Returns true if modifying the header part of the buffer requires
1018  *      the data to be copied.
1019  */
1020 static inline int skb_header_cloned(const struct sk_buff *skb)
1021 {
1022         int dataref;
1023 
1024         if (!skb->cloned)
1025                 return 0;
1026 
1027         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1028         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1029         return dataref != 1;
1030 }
1031 
1032 /**
1033  *      skb_header_release - release reference to header
1034  *      @skb: buffer to operate on
1035  *
1036  *      Drop a reference to the header part of the buffer.  This is done
1037  *      by acquiring a payload reference.  You must not read from the header
1038  *      part of skb->data after this.
1039  */
1040 static inline void skb_header_release(struct sk_buff *skb)
1041 {
1042         BUG_ON(skb->nohdr);
1043         skb->nohdr = 1;
1044         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1045 }
1046 
1047 /**
1048  *      skb_shared - is the buffer shared
1049  *      @skb: buffer to check
1050  *
1051  *      Returns true if more than one person has a reference to this
1052  *      buffer.
1053  */
1054 static inline int skb_shared(const struct sk_buff *skb)
1055 {
1056         return atomic_read(&skb->users) != 1;
1057 }
1058 
1059 /**
1060  *      skb_share_check - check if buffer is shared and if so clone it
1061  *      @skb: buffer to check
1062  *      @pri: priority for memory allocation
1063  *
1064  *      If the buffer is shared the buffer is cloned and the old copy
1065  *      drops a reference. A new clone with a single reference is returned.
1066  *      If the buffer is not shared the original buffer is returned. When
1067  *      being called from interrupt status or with spinlocks held pri must
1068  *      be GFP_ATOMIC.
1069  *
1070  *      NULL is returned on a memory allocation failure.
1071  */
1072 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1073 {
1074         might_sleep_if(pri & __GFP_WAIT);
1075         if (skb_shared(skb)) {
1076                 struct sk_buff *nskb = skb_clone(skb, pri);
1077 
1078                 if (likely(nskb))
1079                         consume_skb(skb);
1080                 else
1081                         kfree_skb(skb);
1082                 skb = nskb;
1083         }
1084         return skb;
1085 }
1086 
1087 /*
1088  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1089  *      packets to handle cases where we have a local reader and forward
1090  *      and a couple of other messy ones. The normal one is tcpdumping
1091  *      a packet thats being forwarded.
1092  */
1093 
1094 /**
1095  *      skb_unshare - make a copy of a shared buffer
1096  *      @skb: buffer to check
1097  *      @pri: priority for memory allocation
1098  *
1099  *      If the socket buffer is a clone then this function creates a new
1100  *      copy of the data, drops a reference count on the old copy and returns
1101  *      the new copy with the reference count at 1. If the buffer is not a clone
1102  *      the original buffer is returned. When called with a spinlock held or
1103  *      from interrupt state @pri must be %GFP_ATOMIC
1104  *
1105  *      %NULL is returned on a memory allocation failure.
1106  */
1107 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1108                                           gfp_t pri)
1109 {
1110         might_sleep_if(pri & __GFP_WAIT);
1111         if (skb_cloned(skb)) {
1112                 struct sk_buff *nskb = skb_copy(skb, pri);
1113                 kfree_skb(skb); /* Free our shared copy */
1114                 skb = nskb;
1115         }
1116         return skb;
1117 }
1118 
1119 /**
1120  *      skb_peek - peek at the head of an &sk_buff_head
1121  *      @list_: list to peek at
1122  *
1123  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1124  *      be careful with this one. A peek leaves the buffer on the
1125  *      list and someone else may run off with it. You must hold
1126  *      the appropriate locks or have a private queue to do this.
1127  *
1128  *      Returns %NULL for an empty list or a pointer to the head element.
1129  *      The reference count is not incremented and the reference is therefore
1130  *      volatile. Use with caution.
1131  */
1132 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1133 {
1134         struct sk_buff *skb = list_->next;
1135 
1136         if (skb == (struct sk_buff *)list_)
1137                 skb = NULL;
1138         return skb;
1139 }
1140 
1141 /**
1142  *      skb_peek_next - peek skb following the given one from a queue
1143  *      @skb: skb to start from
1144  *      @list_: list to peek at
1145  *
1146  *      Returns %NULL when the end of the list is met or a pointer to the
1147  *      next element. The reference count is not incremented and the
1148  *      reference is therefore volatile. Use with caution.
1149  */
1150 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1151                 const struct sk_buff_head *list_)
1152 {
1153         struct sk_buff *next = skb->next;
1154 
1155         if (next == (struct sk_buff *)list_)
1156                 next = NULL;
1157         return next;
1158 }
1159 
1160 /**
1161  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1162  *      @list_: list to peek at
1163  *
1164  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1165  *      be careful with this one. A peek leaves the buffer on the
1166  *      list and someone else may run off with it. You must hold
1167  *      the appropriate locks or have a private queue to do this.
1168  *
1169  *      Returns %NULL for an empty list or a pointer to the tail element.
1170  *      The reference count is not incremented and the reference is therefore
1171  *      volatile. Use with caution.
1172  */
1173 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1174 {
1175         struct sk_buff *skb = list_->prev;
1176 
1177         if (skb == (struct sk_buff *)list_)
1178                 skb = NULL;
1179         return skb;
1180 
1181 }
1182 
1183 /**
1184  *      skb_queue_len   - get queue length
1185  *      @list_: list to measure
1186  *
1187  *      Return the length of an &sk_buff queue.
1188  */
1189 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1190 {
1191         return list_->qlen;
1192 }
1193 
1194 /**
1195  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1196  *      @list: queue to initialize
1197  *
1198  *      This initializes only the list and queue length aspects of
1199  *      an sk_buff_head object.  This allows to initialize the list
1200  *      aspects of an sk_buff_head without reinitializing things like
1201  *      the spinlock.  It can also be used for on-stack sk_buff_head
1202  *      objects where the spinlock is known to not be used.
1203  */
1204 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1205 {
1206         list->prev = list->next = (struct sk_buff *)list;
1207         list->qlen = 0;
1208 }
1209 
1210 /*
1211  * This function creates a split out lock class for each invocation;
1212  * this is needed for now since a whole lot of users of the skb-queue
1213  * infrastructure in drivers have different locking usage (in hardirq)
1214  * than the networking core (in softirq only). In the long run either the
1215  * network layer or drivers should need annotation to consolidate the
1216  * main types of usage into 3 classes.
1217  */
1218 static inline void skb_queue_head_init(struct sk_buff_head *list)
1219 {
1220         spin_lock_init(&list->lock);
1221         __skb_queue_head_init(list);
1222 }
1223 
1224 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1225                 struct lock_class_key *class)
1226 {
1227         skb_queue_head_init(list);
1228         lockdep_set_class(&list->lock, class);
1229 }
1230 
1231 /*
1232  *      Insert an sk_buff on a list.
1233  *
1234  *      The "__skb_xxxx()" functions are the non-atomic ones that
1235  *      can only be called with interrupts disabled.
1236  */
1237 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1238                 struct sk_buff_head *list);
1239 static inline void __skb_insert(struct sk_buff *newsk,
1240                                 struct sk_buff *prev, struct sk_buff *next,
1241                                 struct sk_buff_head *list)
1242 {
1243         newsk->next = next;
1244         newsk->prev = prev;
1245         next->prev  = prev->next = newsk;
1246         list->qlen++;
1247 }
1248 
1249 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1250                                       struct sk_buff *prev,
1251                                       struct sk_buff *next)
1252 {
1253         struct sk_buff *first = list->next;
1254         struct sk_buff *last = list->prev;
1255 
1256         first->prev = prev;
1257         prev->next = first;
1258 
1259         last->next = next;
1260         next->prev = last;
1261 }
1262 
1263 /**
1264  *      skb_queue_splice - join two skb lists, this is designed for stacks
1265  *      @list: the new list to add
1266  *      @head: the place to add it in the first list
1267  */
1268 static inline void skb_queue_splice(const struct sk_buff_head *list,
1269                                     struct sk_buff_head *head)
1270 {
1271         if (!skb_queue_empty(list)) {
1272                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1273                 head->qlen += list->qlen;
1274         }
1275 }
1276 
1277 /**
1278  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1279  *      @list: the new list to add
1280  *      @head: the place to add it in the first list
1281  *
1282  *      The list at @list is reinitialised
1283  */
1284 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1285                                          struct sk_buff_head *head)
1286 {
1287         if (!skb_queue_empty(list)) {
1288                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1289                 head->qlen += list->qlen;
1290                 __skb_queue_head_init(list);
1291         }
1292 }
1293 
1294 /**
1295  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1296  *      @list: the new list to add
1297  *      @head: the place to add it in the first list
1298  */
1299 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1300                                          struct sk_buff_head *head)
1301 {
1302         if (!skb_queue_empty(list)) {
1303                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1304                 head->qlen += list->qlen;
1305         }
1306 }
1307 
1308 /**
1309  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1310  *      @list: the new list to add
1311  *      @head: the place to add it in the first list
1312  *
1313  *      Each of the lists is a queue.
1314  *      The list at @list is reinitialised
1315  */
1316 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1317                                               struct sk_buff_head *head)
1318 {
1319         if (!skb_queue_empty(list)) {
1320                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1321                 head->qlen += list->qlen;
1322                 __skb_queue_head_init(list);
1323         }
1324 }
1325 
1326 /**
1327  *      __skb_queue_after - queue a buffer at the list head
1328  *      @list: list to use
1329  *      @prev: place after this buffer
1330  *      @newsk: buffer to queue
1331  *
1332  *      Queue a buffer int the middle of a list. This function takes no locks
1333  *      and you must therefore hold required locks before calling it.
1334  *
1335  *      A buffer cannot be placed on two lists at the same time.
1336  */
1337 static inline void __skb_queue_after(struct sk_buff_head *list,
1338                                      struct sk_buff *prev,
1339                                      struct sk_buff *newsk)
1340 {
1341         __skb_insert(newsk, prev, prev->next, list);
1342 }
1343 
1344 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1345                 struct sk_buff_head *list);
1346 
1347 static inline void __skb_queue_before(struct sk_buff_head *list,
1348                                       struct sk_buff *next,
1349                                       struct sk_buff *newsk)
1350 {
1351         __skb_insert(newsk, next->prev, next, list);
1352 }
1353 
1354 /**
1355  *      __skb_queue_head - queue a buffer at the list head
1356  *      @list: list to use
1357  *      @newsk: buffer to queue
1358  *
1359  *      Queue a buffer at the start of a list. This function takes no locks
1360  *      and you must therefore hold required locks before calling it.
1361  *
1362  *      A buffer cannot be placed on two lists at the same time.
1363  */
1364 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1365 static inline void __skb_queue_head(struct sk_buff_head *list,
1366                                     struct sk_buff *newsk)
1367 {
1368         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1369 }
1370 
1371 /**
1372  *      __skb_queue_tail - queue a buffer at the list tail
1373  *      @list: list to use
1374  *      @newsk: buffer to queue
1375  *
1376  *      Queue a buffer at the end of a list. This function takes no locks
1377  *      and you must therefore hold required locks before calling it.
1378  *
1379  *      A buffer cannot be placed on two lists at the same time.
1380  */
1381 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1382 static inline void __skb_queue_tail(struct sk_buff_head *list,
1383                                    struct sk_buff *newsk)
1384 {
1385         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1386 }
1387 
1388 /*
1389  * remove sk_buff from list. _Must_ be called atomically, and with
1390  * the list known..
1391  */
1392 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1393 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1394 {
1395         struct sk_buff *next, *prev;
1396 
1397         list->qlen--;
1398         next       = skb->next;
1399         prev       = skb->prev;
1400         skb->next  = skb->prev = NULL;
1401         next->prev = prev;
1402         prev->next = next;
1403 }
1404 
1405 /**
1406  *      __skb_dequeue - remove from the head of the queue
1407  *      @list: list to dequeue from
1408  *
1409  *      Remove the head of the list. This function does not take any locks
1410  *      so must be used with appropriate locks held only. The head item is
1411  *      returned or %NULL if the list is empty.
1412  */
1413 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1414 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1415 {
1416         struct sk_buff *skb = skb_peek(list);
1417         if (skb)
1418                 __skb_unlink(skb, list);
1419         return skb;
1420 }
1421 
1422 /**
1423  *      __skb_dequeue_tail - remove from the tail of the queue
1424  *      @list: list to dequeue from
1425  *
1426  *      Remove the tail of the list. This function does not take any locks
1427  *      so must be used with appropriate locks held only. The tail item is
1428  *      returned or %NULL if the list is empty.
1429  */
1430 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1431 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1432 {
1433         struct sk_buff *skb = skb_peek_tail(list);
1434         if (skb)
1435                 __skb_unlink(skb, list);
1436         return skb;
1437 }
1438 
1439 
1440 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1441 {
1442         return skb->data_len;
1443 }
1444 
1445 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1446 {
1447         return skb->len - skb->data_len;
1448 }
1449 
1450 static inline int skb_pagelen(const struct sk_buff *skb)
1451 {
1452         int i, len = 0;
1453 
1454         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1455                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1456         return len + skb_headlen(skb);
1457 }
1458 
1459 /**
1460  * __skb_fill_page_desc - initialise a paged fragment in an skb
1461  * @skb: buffer containing fragment to be initialised
1462  * @i: paged fragment index to initialise
1463  * @page: the page to use for this fragment
1464  * @off: the offset to the data with @page
1465  * @size: the length of the data
1466  *
1467  * Initialises the @i'th fragment of @skb to point to &size bytes at
1468  * offset @off within @page.
1469  *
1470  * Does not take any additional reference on the fragment.
1471  */
1472 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1473                                         struct page *page, int off, int size)
1474 {
1475         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1476 
1477         /*
1478          * Propagate page->pfmemalloc to the skb if we can. The problem is
1479          * that not all callers have unique ownership of the page. If
1480          * pfmemalloc is set, we check the mapping as a mapping implies
1481          * page->index is set (index and pfmemalloc share space).
1482          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1483          * do not lose pfmemalloc information as the pages would not be
1484          * allocated using __GFP_MEMALLOC.
1485          */
1486         frag->page.p              = page;
1487         frag->page_offset         = off;
1488         skb_frag_size_set(frag, size);
1489 
1490         page = compound_head(page);
1491         if (page->pfmemalloc && !page->mapping)
1492                 skb->pfmemalloc = true;
1493 }
1494 
1495 /**
1496  * skb_fill_page_desc - initialise a paged fragment in an skb
1497  * @skb: buffer containing fragment to be initialised
1498  * @i: paged fragment index to initialise
1499  * @page: the page to use for this fragment
1500  * @off: the offset to the data with @page
1501  * @size: the length of the data
1502  *
1503  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1504  * @skb to point to @size bytes at offset @off within @page. In
1505  * addition updates @skb such that @i is the last fragment.
1506  *
1507  * Does not take any additional reference on the fragment.
1508  */
1509 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1510                                       struct page *page, int off, int size)
1511 {
1512         __skb_fill_page_desc(skb, i, page, off, size);
1513         skb_shinfo(skb)->nr_frags = i + 1;
1514 }
1515 
1516 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1517                      int size, unsigned int truesize);
1518 
1519 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1520                           unsigned int truesize);
1521 
1522 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1523 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1524 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1525 
1526 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1527 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1528 {
1529         return skb->head + skb->tail;
1530 }
1531 
1532 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1533 {
1534         skb->tail = skb->data - skb->head;
1535 }
1536 
1537 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1538 {
1539         skb_reset_tail_pointer(skb);
1540         skb->tail += offset;
1541 }
1542 
1543 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1544 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1545 {
1546         return skb->tail;
1547 }
1548 
1549 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1550 {
1551         skb->tail = skb->data;
1552 }
1553 
1554 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1555 {
1556         skb->tail = skb->data + offset;
1557 }
1558 
1559 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1560 
1561 /*
1562  *      Add data to an sk_buff
1563  */
1564 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1565 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1566 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1567 {
1568         unsigned char *tmp = skb_tail_pointer(skb);
1569         SKB_LINEAR_ASSERT(skb);
1570         skb->tail += len;
1571         skb->len  += len;
1572         return tmp;
1573 }
1574 
1575 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1576 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1577 {
1578         skb->data -= len;
1579         skb->len  += len;
1580         return skb->data;
1581 }
1582 
1583 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1584 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1585 {
1586         skb->len -= len;
1587         BUG_ON(skb->len < skb->data_len);
1588         return skb->data += len;
1589 }
1590 
1591 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1592 {
1593         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1594 }
1595 
1596 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1597 
1598 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1599 {
1600         if (len > skb_headlen(skb) &&
1601             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1602                 return NULL;
1603         skb->len -= len;
1604         return skb->data += len;
1605 }
1606 
1607 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1608 {
1609         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1610 }
1611 
1612 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1613 {
1614         if (likely(len <= skb_headlen(skb)))
1615                 return 1;
1616         if (unlikely(len > skb->len))
1617                 return 0;
1618         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1619 }
1620 
1621 /**
1622  *      skb_headroom - bytes at buffer head
1623  *      @skb: buffer to check
1624  *
1625  *      Return the number of bytes of free space at the head of an &sk_buff.
1626  */
1627 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1628 {
1629         return skb->data - skb->head;
1630 }
1631 
1632 /**
1633  *      skb_tailroom - bytes at buffer end
1634  *      @skb: buffer to check
1635  *
1636  *      Return the number of bytes of free space at the tail of an sk_buff
1637  */
1638 static inline int skb_tailroom(const struct sk_buff *skb)
1639 {
1640         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1641 }
1642 
1643 /**
1644  *      skb_availroom - bytes at buffer end
1645  *      @skb: buffer to check
1646  *
1647  *      Return the number of bytes of free space at the tail of an sk_buff
1648  *      allocated by sk_stream_alloc()
1649  */
1650 static inline int skb_availroom(const struct sk_buff *skb)
1651 {
1652         if (skb_is_nonlinear(skb))
1653                 return 0;
1654 
1655         return skb->end - skb->tail - skb->reserved_tailroom;
1656 }
1657 
1658 /**
1659  *      skb_reserve - adjust headroom
1660  *      @skb: buffer to alter
1661  *      @len: bytes to move
1662  *
1663  *      Increase the headroom of an empty &sk_buff by reducing the tail
1664  *      room. This is only allowed for an empty buffer.
1665  */
1666 static inline void skb_reserve(struct sk_buff *skb, int len)
1667 {
1668         skb->data += len;
1669         skb->tail += len;
1670 }
1671 
1672 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1673 {
1674         skb->inner_mac_header = skb->mac_header;
1675         skb->inner_network_header = skb->network_header;
1676         skb->inner_transport_header = skb->transport_header;
1677 }
1678 
1679 static inline void skb_reset_mac_len(struct sk_buff *skb)
1680 {
1681         skb->mac_len = skb->network_header - skb->mac_header;
1682 }
1683 
1684 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1685                                                         *skb)
1686 {
1687         return skb->head + skb->inner_transport_header;
1688 }
1689 
1690 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1691 {
1692         skb->inner_transport_header = skb->data - skb->head;
1693 }
1694 
1695 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1696                                                    const int offset)
1697 {
1698         skb_reset_inner_transport_header(skb);
1699         skb->inner_transport_header += offset;
1700 }
1701 
1702 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1703 {
1704         return skb->head + skb->inner_network_header;
1705 }
1706 
1707 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1708 {
1709         skb->inner_network_header = skb->data - skb->head;
1710 }
1711 
1712 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1713                                                 const int offset)
1714 {
1715         skb_reset_inner_network_header(skb);
1716         skb->inner_network_header += offset;
1717 }
1718 
1719 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1720 {
1721         return skb->head + skb->inner_mac_header;
1722 }
1723 
1724 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1725 {
1726         skb->inner_mac_header = skb->data - skb->head;
1727 }
1728 
1729 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1730                                             const int offset)
1731 {
1732         skb_reset_inner_mac_header(skb);
1733         skb->inner_mac_header += offset;
1734 }
1735 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1736 {
1737         return skb->transport_header != (typeof(skb->transport_header))~0U;
1738 }
1739 
1740 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1741 {
1742         return skb->head + skb->transport_header;
1743 }
1744 
1745 static inline void skb_reset_transport_header(struct sk_buff *skb)
1746 {
1747         skb->transport_header = skb->data - skb->head;
1748 }
1749 
1750 static inline void skb_set_transport_header(struct sk_buff *skb,
1751                                             const int offset)
1752 {
1753         skb_reset_transport_header(skb);
1754         skb->transport_header += offset;
1755 }
1756 
1757 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1758 {
1759         return skb->head + skb->network_header;
1760 }
1761 
1762 static inline void skb_reset_network_header(struct sk_buff *skb)
1763 {
1764         skb->network_header = skb->data - skb->head;
1765 }
1766 
1767 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1768 {
1769         skb_reset_network_header(skb);
1770         skb->network_header += offset;
1771 }
1772 
1773 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1774 {
1775         return skb->head + skb->mac_header;
1776 }
1777 
1778 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1779 {
1780         return skb->mac_header != (typeof(skb->mac_header))~0U;
1781 }
1782 
1783 static inline void skb_reset_mac_header(struct sk_buff *skb)
1784 {
1785         skb->mac_header = skb->data - skb->head;
1786 }
1787 
1788 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1789 {
1790         skb_reset_mac_header(skb);
1791         skb->mac_header += offset;
1792 }
1793 
1794 static inline void skb_pop_mac_header(struct sk_buff *skb)
1795 {
1796         skb->mac_header = skb->network_header;
1797 }
1798 
1799 static inline void skb_probe_transport_header(struct sk_buff *skb,
1800                                               const int offset_hint)
1801 {
1802         struct flow_keys keys;
1803 
1804         if (skb_transport_header_was_set(skb))
1805                 return;
1806         else if (skb_flow_dissect(skb, &keys))
1807                 skb_set_transport_header(skb, keys.thoff);
1808         else
1809                 skb_set_transport_header(skb, offset_hint);
1810 }
1811 
1812 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1813 {
1814         if (skb_mac_header_was_set(skb)) {
1815                 const unsigned char *old_mac = skb_mac_header(skb);
1816 
1817                 skb_set_mac_header(skb, -skb->mac_len);
1818                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1819         }
1820 }
1821 
1822 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1823 {
1824         return skb->csum_start - skb_headroom(skb);
1825 }
1826 
1827 static inline int skb_transport_offset(const struct sk_buff *skb)
1828 {
1829         return skb_transport_header(skb) - skb->data;
1830 }
1831 
1832 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1833 {
1834         return skb->transport_header - skb->network_header;
1835 }
1836 
1837 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1838 {
1839         return skb->inner_transport_header - skb->inner_network_header;
1840 }
1841 
1842 static inline int skb_network_offset(const struct sk_buff *skb)
1843 {
1844         return skb_network_header(skb) - skb->data;
1845 }
1846 
1847 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1848 {
1849         return skb_inner_network_header(skb) - skb->data;
1850 }
1851 
1852 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1853 {
1854         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1855 }
1856 
1857 static inline void skb_pop_rcv_encapsulation(struct sk_buff *skb)
1858 {
1859         /* Only continue with checksum unnecessary if device indicated
1860          * it is valid across encapsulation (skb->encapsulation was set).
1861          */
1862         if (skb->ip_summed == CHECKSUM_UNNECESSARY && !skb->encapsulation)
1863                 skb->ip_summed = CHECKSUM_NONE;
1864 
1865         skb->encapsulation = 0;
1866         skb->csum_valid = 0;
1867 }
1868 
1869 /*
1870  * CPUs often take a performance hit when accessing unaligned memory
1871  * locations. The actual performance hit varies, it can be small if the
1872  * hardware handles it or large if we have to take an exception and fix it
1873  * in software.
1874  *
1875  * Since an ethernet header is 14 bytes network drivers often end up with
1876  * the IP header at an unaligned offset. The IP header can be aligned by
1877  * shifting the start of the packet by 2 bytes. Drivers should do this
1878  * with:
1879  *
1880  * skb_reserve(skb, NET_IP_ALIGN);
1881  *
1882  * The downside to this alignment of the IP header is that the DMA is now
1883  * unaligned. On some architectures the cost of an unaligned DMA is high
1884  * and this cost outweighs the gains made by aligning the IP header.
1885  *
1886  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1887  * to be overridden.
1888  */
1889 #ifndef NET_IP_ALIGN
1890 #define NET_IP_ALIGN    2
1891 #endif
1892 
1893 /*
1894  * The networking layer reserves some headroom in skb data (via
1895  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1896  * the header has to grow. In the default case, if the header has to grow
1897  * 32 bytes or less we avoid the reallocation.
1898  *
1899  * Unfortunately this headroom changes the DMA alignment of the resulting
1900  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1901  * on some architectures. An architecture can override this value,
1902  * perhaps setting it to a cacheline in size (since that will maintain
1903  * cacheline alignment of the DMA). It must be a power of 2.
1904  *
1905  * Various parts of the networking layer expect at least 32 bytes of
1906  * headroom, you should not reduce this.
1907  *
1908  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
1909  * to reduce average number of cache lines per packet.
1910  * get_rps_cpus() for example only access one 64 bytes aligned block :
1911  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
1912  */
1913 #ifndef NET_SKB_PAD
1914 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
1915 #endif
1916 
1917 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1918 
1919 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1920 {
1921         if (unlikely(skb_is_nonlinear(skb))) {
1922                 WARN_ON(1);
1923                 return;
1924         }
1925         skb->len = len;
1926         skb_set_tail_pointer(skb, len);
1927 }
1928 
1929 void skb_trim(struct sk_buff *skb, unsigned int len);
1930 
1931 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1932 {
1933         if (skb->data_len)
1934                 return ___pskb_trim(skb, len);
1935         __skb_trim(skb, len);
1936         return 0;
1937 }
1938 
1939 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1940 {
1941         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1942 }
1943 
1944 /**
1945  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1946  *      @skb: buffer to alter
1947  *      @len: new length
1948  *
1949  *      This is identical to pskb_trim except that the caller knows that
1950  *      the skb is not cloned so we should never get an error due to out-
1951  *      of-memory.
1952  */
1953 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1954 {
1955         int err = pskb_trim(skb, len);
1956         BUG_ON(err);
1957 }
1958 
1959 /**
1960  *      skb_orphan - orphan a buffer
1961  *      @skb: buffer to orphan
1962  *
1963  *      If a buffer currently has an owner then we call the owner's
1964  *      destructor function and make the @skb unowned. The buffer continues
1965  *      to exist but is no longer charged to its former owner.
1966  */
1967 static inline void skb_orphan(struct sk_buff *skb)
1968 {
1969         if (skb->destructor) {
1970                 skb->destructor(skb);
1971                 skb->destructor = NULL;
1972                 skb->sk         = NULL;
1973         } else {
1974                 BUG_ON(skb->sk);
1975         }
1976 }
1977 
1978 /**
1979  *      skb_orphan_frags - orphan the frags contained in a buffer
1980  *      @skb: buffer to orphan frags from
1981  *      @gfp_mask: allocation mask for replacement pages
1982  *
1983  *      For each frag in the SKB which needs a destructor (i.e. has an
1984  *      owner) create a copy of that frag and release the original
1985  *      page by calling the destructor.
1986  */
1987 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
1988 {
1989         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
1990                 return 0;
1991         return skb_copy_ubufs(skb, gfp_mask);
1992 }
1993 
1994 /**
1995  *      __skb_queue_purge - empty a list
1996  *      @list: list to empty
1997  *
1998  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
1999  *      the list and one reference dropped. This function does not take the
2000  *      list lock and the caller must hold the relevant locks to use it.
2001  */
2002 void skb_queue_purge(struct sk_buff_head *list);
2003 static inline void __skb_queue_purge(struct sk_buff_head *list)
2004 {
2005         struct sk_buff *skb;
2006         while ((skb = __skb_dequeue(list)) != NULL)
2007                 kfree_skb(skb);
2008 }
2009 
2010 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
2011 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
2012 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
2013 
2014 void *netdev_alloc_frag(unsigned int fragsz);
2015 
2016 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2017                                    gfp_t gfp_mask);
2018 
2019 /**
2020  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2021  *      @dev: network device to receive on
2022  *      @length: length to allocate
2023  *
2024  *      Allocate a new &sk_buff and assign it a usage count of one. The
2025  *      buffer has unspecified headroom built in. Users should allocate
2026  *      the headroom they think they need without accounting for the
2027  *      built in space. The built in space is used for optimisations.
2028  *
2029  *      %NULL is returned if there is no free memory. Although this function
2030  *      allocates memory it can be called from an interrupt.
2031  */
2032 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2033                                                unsigned int length)
2034 {
2035         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2036 }
2037 
2038 /* legacy helper around __netdev_alloc_skb() */
2039 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2040                                               gfp_t gfp_mask)
2041 {
2042         return __netdev_alloc_skb(NULL, length, gfp_mask);
2043 }
2044 
2045 /* legacy helper around netdev_alloc_skb() */
2046 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2047 {
2048         return netdev_alloc_skb(NULL, length);
2049 }
2050 
2051 
2052 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2053                 unsigned int length, gfp_t gfp)
2054 {
2055         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2056 
2057         if (NET_IP_ALIGN && skb)
2058                 skb_reserve(skb, NET_IP_ALIGN);
2059         return skb;
2060 }
2061 
2062 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2063                 unsigned int length)
2064 {
2065         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2066 }
2067 
2068 /**
2069  *      __skb_alloc_pages - allocate pages for ps-rx on a skb and preserve pfmemalloc data
2070  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
2071  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
2072  *      @order: size of the allocation
2073  *
2074  *      Allocate a new page.
2075  *
2076  *      %NULL is returned if there is no free memory.
2077 */
2078 static inline struct page *__skb_alloc_pages(gfp_t gfp_mask,
2079                                               struct sk_buff *skb,
2080                                               unsigned int order)
2081 {
2082         struct page *page;
2083 
2084         gfp_mask |= __GFP_COLD;
2085 
2086         if (!(gfp_mask & __GFP_NOMEMALLOC))
2087                 gfp_mask |= __GFP_MEMALLOC;
2088 
2089         page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2090         if (skb && page && page->pfmemalloc)
2091                 skb->pfmemalloc = true;
2092 
2093         return page;
2094 }
2095 
2096 /**
2097  *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
2098  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
2099  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
2100  *
2101  *      Allocate a new page.
2102  *
2103  *      %NULL is returned if there is no free memory.
2104  */
2105 static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
2106                                              struct sk_buff *skb)
2107 {
2108         return __skb_alloc_pages(gfp_mask, skb, 0);
2109 }
2110 
2111 /**
2112  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2113  *      @page: The page that was allocated from skb_alloc_page
2114  *      @skb: The skb that may need pfmemalloc set
2115  */
2116 static inline void skb_propagate_pfmemalloc(struct page *page,
2117                                              struct sk_buff *skb)
2118 {
2119         if (page && page->pfmemalloc)
2120                 skb->pfmemalloc = true;
2121 }
2122 
2123 /**
2124  * skb_frag_page - retrieve the page referred to by a paged fragment
2125  * @frag: the paged fragment
2126  *
2127  * Returns the &struct page associated with @frag.
2128  */
2129 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2130 {
2131         return frag->page.p;
2132 }
2133 
2134 /**
2135  * __skb_frag_ref - take an addition reference on a paged fragment.
2136  * @frag: the paged fragment
2137  *
2138  * Takes an additional reference on the paged fragment @frag.
2139  */
2140 static inline void __skb_frag_ref(skb_frag_t *frag)
2141 {
2142         get_page(skb_frag_page(frag));
2143 }
2144 
2145 /**
2146  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2147  * @skb: the buffer
2148  * @f: the fragment offset.
2149  *
2150  * Takes an additional reference on the @f'th paged fragment of @skb.
2151  */
2152 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2153 {
2154         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2155 }
2156 
2157 /**
2158  * __skb_frag_unref - release a reference on a paged fragment.
2159  * @frag: the paged fragment
2160  *
2161  * Releases a reference on the paged fragment @frag.
2162  */
2163 static inline void __skb_frag_unref(skb_frag_t *frag)
2164 {
2165         put_page(skb_frag_page(frag));
2166 }
2167 
2168 /**
2169  * skb_frag_unref - release a reference on a paged fragment of an skb.
2170  * @skb: the buffer
2171  * @f: the fragment offset
2172  *
2173  * Releases a reference on the @f'th paged fragment of @skb.
2174  */
2175 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2176 {
2177         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2178 }
2179 
2180 /**
2181  * skb_frag_address - gets the address of the data contained in a paged fragment
2182  * @frag: the paged fragment buffer
2183  *
2184  * Returns the address of the data within @frag. The page must already
2185  * be mapped.
2186  */
2187 static inline void *skb_frag_address(const skb_frag_t *frag)
2188 {
2189         return page_address(skb_frag_page(frag)) + frag->page_offset;
2190 }
2191 
2192 /**
2193  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2194  * @frag: the paged fragment buffer
2195  *
2196  * Returns the address of the data within @frag. Checks that the page
2197  * is mapped and returns %NULL otherwise.
2198  */
2199 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2200 {
2201         void *ptr = page_address(skb_frag_page(frag));
2202         if (unlikely(!ptr))
2203                 return NULL;
2204 
2205         return ptr + frag->page_offset;
2206 }
2207 
2208 /**
2209  * __skb_frag_set_page - sets the page contained in a paged fragment
2210  * @frag: the paged fragment
2211  * @page: the page to set
2212  *
2213  * Sets the fragment @frag to contain @page.
2214  */
2215 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2216 {
2217         frag->page.p = page;
2218 }
2219 
2220 /**
2221  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2222  * @skb: the buffer
2223  * @f: the fragment offset
2224  * @page: the page to set
2225  *
2226  * Sets the @f'th fragment of @skb to contain @page.
2227  */
2228 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2229                                      struct page *page)
2230 {
2231         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2232 }
2233 
2234 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2235 
2236 /**
2237  * skb_frag_dma_map - maps a paged fragment via the DMA API
2238  * @dev: the device to map the fragment to
2239  * @frag: the paged fragment to map
2240  * @offset: the offset within the fragment (starting at the
2241  *          fragment's own offset)
2242  * @size: the number of bytes to map
2243  * @dir: the direction of the mapping (%PCI_DMA_*)
2244  *
2245  * Maps the page associated with @frag to @device.
2246  */
2247 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2248                                           const skb_frag_t *frag,
2249                                           size_t offset, size_t size,
2250                                           enum dma_data_direction dir)
2251 {
2252         return dma_map_page(dev, skb_frag_page(frag),
2253                             frag->page_offset + offset, size, dir);
2254 }
2255 
2256 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2257                                         gfp_t gfp_mask)
2258 {
2259         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2260 }
2261 
2262 
2263 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2264                                                   gfp_t gfp_mask)
2265 {
2266         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2267 }
2268 
2269 
2270 /**
2271  *      skb_clone_writable - is the header of a clone writable
2272  *      @skb: buffer to check
2273  *      @len: length up to which to write
2274  *
2275  *      Returns true if modifying the header part of the cloned buffer
2276  *      does not requires the data to be copied.
2277  */
2278 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2279 {
2280         return !skb_header_cloned(skb) &&
2281                skb_headroom(skb) + len <= skb->hdr_len;
2282 }
2283 
2284 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2285                             int cloned)
2286 {
2287         int delta = 0;
2288 
2289         if (headroom > skb_headroom(skb))
2290                 delta = headroom - skb_headroom(skb);
2291 
2292         if (delta || cloned)
2293                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2294                                         GFP_ATOMIC);
2295         return 0;
2296 }
2297 
2298 /**
2299  *      skb_cow - copy header of skb when it is required
2300  *      @skb: buffer to cow
2301  *      @headroom: needed headroom
2302  *
2303  *      If the skb passed lacks sufficient headroom or its data part
2304  *      is shared, data is reallocated. If reallocation fails, an error
2305  *      is returned and original skb is not changed.
2306  *
2307  *      The result is skb with writable area skb->head...skb->tail
2308  *      and at least @headroom of space at head.
2309  */
2310 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2311 {
2312         return __skb_cow(skb, headroom, skb_cloned(skb));
2313 }
2314 
2315 /**
2316  *      skb_cow_head - skb_cow but only making the head writable
2317  *      @skb: buffer to cow
2318  *      @headroom: needed headroom
2319  *
2320  *      This function is identical to skb_cow except that we replace the
2321  *      skb_cloned check by skb_header_cloned.  It should be used when
2322  *      you only need to push on some header and do not need to modify
2323  *      the data.
2324  */
2325 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2326 {
2327         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2328 }
2329 
2330 /**
2331  *      skb_padto       - pad an skbuff up to a minimal size
2332  *      @skb: buffer to pad
2333  *      @len: minimal length
2334  *
2335  *      Pads up a buffer to ensure the trailing bytes exist and are
2336  *      blanked. If the buffer already contains sufficient data it
2337  *      is untouched. Otherwise it is extended. Returns zero on
2338  *      success. The skb is freed on error.
2339  */
2340  
2341 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2342 {
2343         unsigned int size = skb->len;
2344         if (likely(size >= len))
2345                 return 0;
2346         return skb_pad(skb, len - size);
2347 }
2348 
2349 static inline int skb_add_data(struct sk_buff *skb,
2350                                char __user *from, int copy)
2351 {
2352         const int off = skb->len;
2353 
2354         if (skb->ip_summed == CHECKSUM_NONE) {
2355                 int err = 0;
2356                 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2357                                                             copy, 0, &err);
2358                 if (!err) {
2359                         skb->csum = csum_block_add(skb->csum, csum, off);
2360                         return 0;
2361                 }
2362         } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2363                 return 0;
2364 
2365         __skb_trim(skb, off);
2366         return -EFAULT;
2367 }
2368 
2369 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2370                                     const struct page *page, int off)
2371 {
2372         if (i) {
2373                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2374 
2375                 return page == skb_frag_page(frag) &&
2376                        off == frag->page_offset + skb_frag_size(frag);
2377         }
2378         return false;
2379 }
2380 
2381 static inline int __skb_linearize(struct sk_buff *skb)
2382 {
2383         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2384 }
2385 
2386 /**
2387  *      skb_linearize - convert paged skb to linear one
2388  *      @skb: buffer to linarize
2389  *
2390  *      If there is no free memory -ENOMEM is returned, otherwise zero
2391  *      is returned and the old skb data released.
2392  */
2393 static inline int skb_linearize(struct sk_buff *skb)
2394 {
2395         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2396 }
2397 
2398 /**
2399  * skb_has_shared_frag - can any frag be overwritten
2400  * @skb: buffer to test
2401  *
2402  * Return true if the skb has at least one frag that might be modified
2403  * by an external entity (as in vmsplice()/sendfile())
2404  */
2405 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2406 {
2407         return skb_is_nonlinear(skb) &&
2408                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2409 }
2410 
2411 /**
2412  *      skb_linearize_cow - make sure skb is linear and writable
2413  *      @skb: buffer to process
2414  *
2415  *      If there is no free memory -ENOMEM is returned, otherwise zero
2416  *      is returned and the old skb data released.
2417  */
2418 static inline int skb_linearize_cow(struct sk_buff *skb)
2419 {
2420         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2421                __skb_linearize(skb) : 0;
2422 }
2423 
2424 /**
2425  *      skb_postpull_rcsum - update checksum for received skb after pull
2426  *      @skb: buffer to update
2427  *      @start: start of data before pull
2428  *      @len: length of data pulled
2429  *
2430  *      After doing a pull on a received packet, you need to call this to
2431  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2432  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2433  */
2434 
2435 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2436                                       const void *start, unsigned int len)
2437 {
2438         if (skb->ip_summed == CHECKSUM_COMPLETE)
2439                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2440 }
2441 
2442 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2443 
2444 /**
2445  *      pskb_trim_rcsum - trim received skb and update checksum
2446  *      @skb: buffer to trim
2447  *      @len: new length
2448  *
2449  *      This is exactly the same as pskb_trim except that it ensures the
2450  *      checksum of received packets are still valid after the operation.
2451  */
2452 
2453 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2454 {
2455         if (likely(len >= skb->len))
2456                 return 0;
2457         if (skb->ip_summed == CHECKSUM_COMPLETE)
2458                 skb->ip_summed = CHECKSUM_NONE;
2459         return __pskb_trim(skb, len);
2460 }
2461 
2462 #define skb_queue_walk(queue, skb) \
2463                 for (skb = (queue)->next;                                       \
2464                      skb != (struct sk_buff *)(queue);                          \
2465                      skb = skb->next)
2466 
2467 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2468                 for (skb = (queue)->next, tmp = skb->next;                      \
2469                      skb != (struct sk_buff *)(queue);                          \
2470                      skb = tmp, tmp = skb->next)
2471 
2472 #define skb_queue_walk_from(queue, skb)                                         \
2473                 for (; skb != (struct sk_buff *)(queue);                        \
2474                      skb = skb->next)
2475 
2476 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2477                 for (tmp = skb->next;                                           \
2478                      skb != (struct sk_buff *)(queue);                          \
2479                      skb = tmp, tmp = skb->next)
2480 
2481 #define skb_queue_reverse_walk(queue, skb) \
2482                 for (skb = (queue)->prev;                                       \
2483                      skb != (struct sk_buff *)(queue);                          \
2484                      skb = skb->prev)
2485 
2486 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2487                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2488                      skb != (struct sk_buff *)(queue);                          \
2489                      skb = tmp, tmp = skb->prev)
2490 
2491 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2492                 for (tmp = skb->prev;                                           \
2493                      skb != (struct sk_buff *)(queue);                          \
2494                      skb = tmp, tmp = skb->prev)
2495 
2496 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2497 {
2498         return skb_shinfo(skb)->frag_list != NULL;
2499 }
2500 
2501 static inline void skb_frag_list_init(struct sk_buff *skb)
2502 {
2503         skb_shinfo(skb)->frag_list = NULL;
2504 }
2505 
2506 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2507 {
2508         frag->next = skb_shinfo(skb)->frag_list;
2509         skb_shinfo(skb)->frag_list = frag;
2510 }
2511 
2512 #define skb_walk_frags(skb, iter)       \
2513         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2514 
2515 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2516                                     int *peeked, int *off, int *err);
2517 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2518                                   int *err);
2519 unsigned int datagram_poll(struct file *file, struct socket *sock,
2520                            struct poll_table_struct *wait);
2521 int skb_copy_datagram_iovec(const struct sk_buff *from, int offset,
2522                             struct iovec *to, int size);
2523 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, int hlen,
2524                                      struct iovec *iov);
2525 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
2526                                  const struct iovec *from, int from_offset,
2527                                  int len);
2528 int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
2529                            int offset, size_t count);
2530 int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset,
2531                                   const struct iovec *to, int to_offset,
2532                                   int size);
2533 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2534 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2535 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2536 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2537 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2538 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2539                               int len, __wsum csum);
2540 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
2541                     struct pipe_inode_info *pipe, unsigned int len,
2542                     unsigned int flags);
2543 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2544 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
2545 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
2546                  int len, int hlen);
2547 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2548 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2549 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2550 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2551 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2552 
2553 struct skb_checksum_ops {
2554         __wsum (*update)(const void *mem, int len, __wsum wsum);
2555         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2556 };
2557 
2558 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2559                       __wsum csum, const struct skb_checksum_ops *ops);
2560 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2561                     __wsum csum);
2562 
2563 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2564                                        int len, void *buffer)
2565 {
2566         int hlen = skb_headlen(skb);
2567 
2568         if (hlen - offset >= len)
2569                 return skb->data + offset;
2570 
2571         if (skb_copy_bits(skb, offset, buffer, len) < 0)
2572                 return NULL;
2573 
2574         return buffer;
2575 }
2576 
2577 /**
2578  *      skb_needs_linearize - check if we need to linearize a given skb
2579  *                            depending on the given device features.
2580  *      @skb: socket buffer to check
2581  *      @features: net device features
2582  *
2583  *      Returns true if either:
2584  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
2585  *      2. skb is fragmented and the device does not support SG.
2586  */
2587 static inline bool skb_needs_linearize(struct sk_buff *skb,
2588                                        netdev_features_t features)
2589 {
2590         return skb_is_nonlinear(skb) &&
2591                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
2592                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
2593 }
2594 
2595 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2596                                              void *to,
2597                                              const unsigned int len)
2598 {
2599         memcpy(to, skb->data, len);
2600 }
2601 
2602 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2603                                                     const int offset, void *to,
2604                                                     const unsigned int len)
2605 {
2606         memcpy(to, skb->data + offset, len);
2607 }
2608 
2609 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2610                                            const void *from,
2611                                            const unsigned int len)
2612 {
2613         memcpy(skb->data, from, len);
2614 }
2615 
2616 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2617                                                   const int offset,
2618                                                   const void *from,
2619                                                   const unsigned int len)
2620 {
2621         memcpy(skb->data + offset, from, len);
2622 }
2623 
2624 void skb_init(void);
2625 
2626 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2627 {
2628         return skb->tstamp;
2629 }
2630 
2631 /**
2632  *      skb_get_timestamp - get timestamp from a skb
2633  *      @skb: skb to get stamp from
2634  *      @stamp: pointer to struct timeval to store stamp in
2635  *
2636  *      Timestamps are stored in the skb as offsets to a base timestamp.
2637  *      This function converts the offset back to a struct timeval and stores
2638  *      it in stamp.
2639  */
2640 static inline void skb_get_timestamp(const struct sk_buff *skb,
2641                                      struct timeval *stamp)
2642 {
2643         *stamp = ktime_to_timeval(skb->tstamp);
2644 }
2645 
2646 static inline void skb_get_timestampns(const struct sk_buff *skb,
2647                                        struct timespec *stamp)
2648 {
2649         *stamp = ktime_to_timespec(skb->tstamp);
2650 }
2651 
2652 static inline void __net_timestamp(struct sk_buff *skb)
2653 {
2654         skb->tstamp = ktime_get_real();
2655 }
2656 
2657 static inline ktime_t net_timedelta(ktime_t t)
2658 {
2659         return ktime_sub(ktime_get_real(), t);
2660 }
2661 
2662 static inline ktime_t net_invalid_timestamp(void)
2663 {
2664         return ktime_set(0, 0);
2665 }
2666 
2667 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2668 
2669 void skb_clone_tx_timestamp(struct sk_buff *skb);
2670 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2671 
2672 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2673 
2674 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2675 {
2676 }
2677 
2678 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2679 {
2680         return false;
2681 }
2682 
2683 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2684 
2685 /**
2686  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2687  *
2688  * PHY drivers may accept clones of transmitted packets for
2689  * timestamping via their phy_driver.txtstamp method. These drivers
2690  * must call this function to return the skb back to the stack, with
2691  * or without a timestamp.
2692  *
2693  * @skb: clone of the the original outgoing packet
2694  * @hwtstamps: hardware time stamps, may be NULL if not available
2695  *
2696  */
2697 void skb_complete_tx_timestamp(struct sk_buff *skb,
2698                                struct skb_shared_hwtstamps *hwtstamps);
2699 
2700 /**
2701  * skb_tstamp_tx - queue clone of skb with send time stamps
2702  * @orig_skb:   the original outgoing packet
2703  * @hwtstamps:  hardware time stamps, may be NULL if not available
2704  *
2705  * If the skb has a socket associated, then this function clones the
2706  * skb (thus sharing the actual data and optional structures), stores
2707  * the optional hardware time stamping information (if non NULL) or
2708  * generates a software time stamp (otherwise), then queues the clone
2709  * to the error queue of the socket.  Errors are silently ignored.
2710  */
2711 void skb_tstamp_tx(struct sk_buff *orig_skb,
2712                    struct skb_shared_hwtstamps *hwtstamps);
2713 
2714 static inline void sw_tx_timestamp(struct sk_buff *skb)
2715 {
2716         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2717             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2718                 skb_tstamp_tx(skb, NULL);
2719 }
2720 
2721 /**
2722  * skb_tx_timestamp() - Driver hook for transmit timestamping
2723  *
2724  * Ethernet MAC Drivers should call this function in their hard_xmit()
2725  * function immediately before giving the sk_buff to the MAC hardware.
2726  *
2727  * Specifically, one should make absolutely sure that this function is
2728  * called before TX completion of this packet can trigger.  Otherwise
2729  * the packet could potentially already be freed.
2730  *
2731  * @skb: A socket buffer.
2732  */
2733 static inline void skb_tx_timestamp(struct sk_buff *skb)
2734 {
2735         skb_clone_tx_timestamp(skb);
2736         sw_tx_timestamp(skb);
2737 }
2738 
2739 /**
2740  * skb_complete_wifi_ack - deliver skb with wifi status
2741  *
2742  * @skb: the original outgoing packet
2743  * @acked: ack status
2744  *
2745  */
2746 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2747 
2748 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2749 __sum16 __skb_checksum_complete(struct sk_buff *skb);
2750 
2751 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2752 {
2753         return ((skb->ip_summed & CHECKSUM_UNNECESSARY) || skb->csum_valid);
2754 }
2755 
2756 /**
2757  *      skb_checksum_complete - Calculate checksum of an entire packet
2758  *      @skb: packet to process
2759  *
2760  *      This function calculates the checksum over the entire packet plus
2761  *      the value of skb->csum.  The latter can be used to supply the
2762  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2763  *      checksum.
2764  *
2765  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2766  *      this function can be used to verify that checksum on received
2767  *      packets.  In that case the function should return zero if the
2768  *      checksum is correct.  In particular, this function will return zero
2769  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2770  *      hardware has already verified the correctness of the checksum.
2771  */
2772 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2773 {
2774         return skb_csum_unnecessary(skb) ?
2775                0 : __skb_checksum_complete(skb);
2776 }
2777 
2778 /* Check if we need to perform checksum complete validation.
2779  *
2780  * Returns true if checksum complete is needed, false otherwise
2781  * (either checksum is unnecessary or zero checksum is allowed).
2782  */
2783 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
2784                                                   bool zero_okay,
2785                                                   __sum16 check)
2786 {
2787         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
2788                 skb->csum_valid = 1;
2789                 return false;
2790         }
2791 
2792         return true;
2793 }
2794 
2795 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
2796  * in checksum_init.
2797  */
2798 #define CHECKSUM_BREAK 76
2799 
2800 /* Validate (init) checksum based on checksum complete.
2801  *
2802  * Return values:
2803  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
2804  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
2805  *      checksum is stored in skb->csum for use in __skb_checksum_complete
2806  *   non-zero: value of invalid checksum
2807  *
2808  */
2809 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
2810                                                        bool complete,
2811                                                        __wsum psum)
2812 {
2813         if (skb->ip_summed == CHECKSUM_COMPLETE) {
2814                 if (!csum_fold(csum_add(psum, skb->csum))) {
2815                         skb->csum_valid = 1;
2816                         return 0;
2817                 }
2818         }
2819 
2820         skb->csum = psum;
2821 
2822         if (complete || skb->len <= CHECKSUM_BREAK) {
2823                 __sum16 csum;
2824 
2825                 csum = __skb_checksum_complete(skb);
2826                 skb->csum_valid = !csum;
2827                 return csum;
2828         }
2829 
2830         return 0;
2831 }
2832 
2833 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
2834 {
2835         return 0;
2836 }
2837 
2838 /* Perform checksum validate (init). Note that this is a macro since we only
2839  * want to calculate the pseudo header which is an input function if necessary.
2840  * First we try to validate without any computation (checksum unnecessary) and
2841  * then calculate based on checksum complete calling the function to compute
2842  * pseudo header.
2843  *
2844  * Return values:
2845  *   0: checksum is validated or try to in skb_checksum_complete
2846  *   non-zero: value of invalid checksum
2847  */
2848 #define __skb_checksum_validate(skb, proto, complete,                   \
2849                                 zero_okay, check, compute_pseudo)       \
2850 ({                                                                      \
2851         __sum16 __ret = 0;                                              \
2852         skb->csum_valid = 0;                                            \
2853         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
2854                 __ret = __skb_checksum_validate_complete(skb,           \
2855                                 complete, compute_pseudo(skb, proto));  \
2856         __ret;                                                          \
2857 })
2858 
2859 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
2860         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
2861 
2862 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
2863         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
2864 
2865 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
2866         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
2867 
2868 #define skb_checksum_validate_zero_check(skb, proto, check,             \
2869                                          compute_pseudo)                \
2870         __skb_checksum_validate_(skb, proto, true, true, check, compute_pseudo)
2871 
2872 #define skb_checksum_simple_validate(skb)                               \
2873         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
2874 
2875 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2876 void nf_conntrack_destroy(struct nf_conntrack *nfct);
2877 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
2878 {
2879         if (nfct && atomic_dec_and_test(&nfct->use))
2880                 nf_conntrack_destroy(nfct);
2881 }
2882 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
2883 {
2884         if (nfct)
2885                 atomic_inc(&nfct->use);
2886 }
2887 #endif
2888 #ifdef CONFIG_BRIDGE_NETFILTER
2889 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
2890 {
2891         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
2892                 kfree(nf_bridge);
2893 }
2894 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
2895 {
2896         if (nf_bridge)
2897                 atomic_inc(&nf_bridge->use);
2898 }
2899 #endif /* CONFIG_BRIDGE_NETFILTER */
2900 static inline void nf_reset(struct sk_buff *skb)
2901 {
2902 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2903         nf_conntrack_put(skb->nfct);
2904         skb->nfct = NULL;
2905 #endif
2906 #ifdef CONFIG_BRIDGE_NETFILTER
2907         nf_bridge_put(skb->nf_bridge);
2908         skb->nf_bridge = NULL;
2909 #endif
2910 }
2911 
2912 static inline void nf_reset_trace(struct sk_buff *skb)
2913 {
2914 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
2915         skb->nf_trace = 0;
2916 #endif
2917 }
2918 
2919 /* Note: This doesn't put any conntrack and bridge info in dst. */
2920 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2921 {
2922 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2923         dst->nfct = src->nfct;
2924         nf_conntrack_get(src->nfct);
2925         dst->nfctinfo = src->nfctinfo;
2926 #endif
2927 #ifdef CONFIG_BRIDGE_NETFILTER
2928         dst->nf_bridge  = src->nf_bridge;
2929         nf_bridge_get(src->nf_bridge);
2930 #endif
2931 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
2932         dst->nf_trace = src->nf_trace;
2933 #endif
2934 }
2935 
2936 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2937 {
2938 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2939         nf_conntrack_put(dst->nfct);
2940 #endif
2941 #ifdef CONFIG_BRIDGE_NETFILTER
2942         nf_bridge_put(dst->nf_bridge);
2943 #endif
2944         __nf_copy(dst, src);
2945 }
2946 
2947 #ifdef CONFIG_NETWORK_SECMARK
2948 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2949 {
2950         to->secmark = from->secmark;
2951 }
2952 
2953 static inline void skb_init_secmark(struct sk_buff *skb)
2954 {
2955         skb->secmark = 0;
2956 }
2957 #else
2958 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2959 { }
2960 
2961 static inline void skb_init_secmark(struct sk_buff *skb)
2962 { }
2963 #endif
2964 
2965 static inline bool skb_irq_freeable(const struct sk_buff *skb)
2966 {
2967         return !skb->destructor &&
2968 #if IS_ENABLED(CONFIG_XFRM)
2969                 !skb->sp &&
2970 #endif
2971 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
2972                 !skb->nfct &&
2973 #endif
2974                 !skb->_skb_refdst &&
2975                 !skb_has_frag_list(skb);
2976 }
2977 
2978 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
2979 {
2980         skb->queue_mapping = queue_mapping;
2981 }
2982 
2983 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2984 {
2985         return skb->queue_mapping;
2986 }
2987 
2988 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
2989 {
2990         to->queue_mapping = from->queue_mapping;
2991 }
2992 
2993 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
2994 {
2995         skb->queue_mapping = rx_queue + 1;
2996 }
2997 
2998 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
2999 {
3000         return skb->queue_mapping - 1;
3001 }
3002 
3003 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3004 {
3005         return skb->queue_mapping != 0;
3006 }
3007 
3008 u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
3009                   unsigned int num_tx_queues);
3010 
3011 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3012 {
3013 #ifdef CONFIG_XFRM
3014         return skb->sp;
3015 #else
3016         return NULL;
3017 #endif
3018 }
3019 
3020 /* Keeps track of mac header offset relative to skb->head.
3021  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3022  * For non-tunnel skb it points to skb_mac_header() and for
3023  * tunnel skb it points to outer mac header.
3024  * Keeps track of level of encapsulation of network headers.
3025  */
3026 struct skb_gso_cb {
3027         int     mac_offset;
3028         int     encap_level;
3029         __u16   csum_start;
3030 };
3031 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
3032 
3033 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3034 {
3035         return (skb_mac_header(inner_skb) - inner_skb->head) -
3036                 SKB_GSO_CB(inner_skb)->mac_offset;
3037 }
3038 
3039 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3040 {
3041         int new_headroom, headroom;
3042         int ret;
3043 
3044         headroom = skb_headroom(skb);
3045         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3046         if (ret)
3047                 return ret;
3048 
3049         new_headroom = skb_headroom(skb);
3050         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3051         return 0;
3052 }
3053 
3054 /* Compute the checksum for a gso segment. First compute the checksum value
3055  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3056  * then add in skb->csum (checksum from csum_start to end of packet).
3057  * skb->csum and csum_start are then updated to reflect the checksum of the
3058  * resultant packet starting from the transport header-- the resultant checksum
3059  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3060  * header.
3061  */
3062 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3063 {
3064         int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
3065             skb_transport_offset(skb);
3066         __u16 csum;
3067 
3068         csum = csum_fold(csum_partial(skb_transport_header(skb),
3069                                       plen, skb->csum));
3070         skb->csum = res;
3071         SKB_GSO_CB(skb)->csum_start -= plen;
3072 
3073         return csum;
3074 }
3075 
3076 static inline bool skb_is_gso(const struct sk_buff *skb)
3077 {
3078         return skb_shinfo(skb)->gso_size;
3079 }
3080 
3081 /* Note: Should be called only if skb_is_gso(skb) is true */
3082 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3083 {
3084         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3085 }
3086 
3087 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3088 
3089 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3090 {
3091         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3092          * wanted then gso_type will be set. */
3093         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3094 
3095         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3096             unlikely(shinfo->gso_type == 0)) {
3097                 __skb_warn_lro_forwarding(skb);
3098                 return true;
3099         }
3100         return false;
3101 }
3102 
3103 static inline void skb_forward_csum(struct sk_buff *skb)
3104 {
3105         /* Unfortunately we don't support this one.  Any brave souls? */
3106         if (skb->ip_summed == CHECKSUM_COMPLETE)
3107                 skb->ip_summed = CHECKSUM_NONE;
3108 }
3109 
3110 /**
3111  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3112  * @skb: skb to check
3113  *
3114  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3115  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3116  * use this helper, to document places where we make this assertion.
3117  */
3118 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3119 {
3120 #ifdef DEBUG
3121         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3122 #endif
3123 }
3124 
3125 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3126 
3127 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3128 
3129 u32 __skb_get_poff(const struct sk_buff *skb);
3130 
3131 /**
3132  * skb_head_is_locked - Determine if the skb->head is locked down
3133  * @skb: skb to check
3134  *
3135  * The head on skbs build around a head frag can be removed if they are
3136  * not cloned.  This function returns true if the skb head is locked down
3137  * due to either being allocated via kmalloc, or by being a clone with
3138  * multiple references to the head.
3139  */
3140 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3141 {
3142         return !skb->head_frag || skb_cloned(skb);
3143 }
3144 
3145 /**
3146  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3147  *
3148  * @skb: GSO skb
3149  *
3150  * skb_gso_network_seglen is used to determine the real size of the
3151  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3152  *
3153  * The MAC/L2 header is not accounted for.
3154  */
3155 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3156 {
3157         unsigned int hdr_len = skb_transport_header(skb) -
3158                                skb_network_header(skb);
3159         return hdr_len + skb_gso_transport_seglen(skb);
3160 }
3161 #endif  /* __KERNEL__ */
3162 #endif  /* _LINUX_SKBUFF_H */
3163 

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