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Linux/include/linux/skbuff.h

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

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