~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

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

Version: ~ [ linux-5.5 ] ~ [ linux-5.4.15 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.98 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.167 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.211 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.211 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 <net/flow_keys.h>
 36 
 37 /* Don't change this without changing skb_csum_unnecessary! */
 38 #define CHECKSUM_NONE 0
 39 #define CHECKSUM_UNNECESSARY 1
 40 #define CHECKSUM_COMPLETE 2
 41 #define CHECKSUM_PARTIAL 3
 42 
 43 #define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
 44                                  ~(SMP_CACHE_BYTES - 1))
 45 #define SKB_WITH_OVERHEAD(X)    \
 46         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 47 #define SKB_MAX_ORDER(X, ORDER) \
 48         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
 49 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
 50 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
 51 
 52 /* return minimum truesize of one skb containing X bytes of data */
 53 #define SKB_TRUESIZE(X) ((X) +                                          \
 54                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
 55                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 56 
 57 /* A. Checksumming of received packets by device.
 58  *
 59  *      NONE: device failed to checksum this packet.
 60  *              skb->csum is undefined.
 61  *
 62  *      UNNECESSARY: device parsed packet and wouldbe verified checksum.
 63  *              skb->csum is undefined.
 64  *            It is bad option, but, unfortunately, many of vendors do this.
 65  *            Apparently with secret goal to sell you new device, when you
 66  *            will add new protocol to your host. F.e. IPv6. 8)
 67  *
 68  *      COMPLETE: the most generic way. Device supplied checksum of _all_
 69  *          the packet as seen by netif_rx in skb->csum.
 70  *          NOTE: Even if device supports only some protocols, but
 71  *          is able to produce some skb->csum, it MUST use COMPLETE,
 72  *          not UNNECESSARY.
 73  *
 74  *      PARTIAL: identical to the case for output below.  This may occur
 75  *          on a packet received directly from another Linux OS, e.g.,
 76  *          a virtualised Linux kernel on the same host.  The packet can
 77  *          be treated in the same way as UNNECESSARY except that on
 78  *          output (i.e., forwarding) the checksum must be filled in
 79  *          by the OS or the hardware.
 80  *
 81  * B. Checksumming on output.
 82  *
 83  *      NONE: skb is checksummed by protocol or csum is not required.
 84  *
 85  *      PARTIAL: device is required to csum packet as seen by hard_start_xmit
 86  *      from skb->csum_start to the end and to record the checksum
 87  *      at skb->csum_start + skb->csum_offset.
 88  *
 89  *      Device must show its capabilities in dev->features, set
 90  *      at device setup time.
 91  *      NETIF_F_HW_CSUM - it is clever device, it is able to checksum
 92  *                        everything.
 93  *      NETIF_F_IP_CSUM - device is dumb. It is able to csum only
 94  *                        TCP/UDP over IPv4. Sigh. Vendors like this
 95  *                        way by an unknown reason. Though, see comment above
 96  *                        about CHECKSUM_UNNECESSARY. 8)
 97  *      NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
 98  *
 99  *      UNNECESSARY: device will do per protocol specific csum. Protocol drivers
100  *      that do not want net to perform the checksum calculation should use
101  *      this flag in their outgoing skbs.
102  *      NETIF_F_FCOE_CRC  this indicates 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 struct net_device;
110 struct scatterlist;
111 struct pipe_inode_info;
112 
113 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
114 struct nf_conntrack {
115         atomic_t use;
116 };
117 #endif
118 
119 #ifdef CONFIG_BRIDGE_NETFILTER
120 struct nf_bridge_info {
121         atomic_t                use;
122         unsigned int            mask;
123         struct net_device       *physindev;
124         struct net_device       *physoutdev;
125         unsigned long           data[32 / sizeof(unsigned long)];
126 };
127 #endif
128 
129 struct sk_buff_head {
130         /* These two members must be first. */
131         struct sk_buff  *next;
132         struct sk_buff  *prev;
133 
134         __u32           qlen;
135         spinlock_t      lock;
136 };
137 
138 struct sk_buff;
139 
140 /* To allow 64K frame to be packed as single skb without frag_list we
141  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
142  * buffers which do not start on a page boundary.
143  *
144  * Since GRO uses frags we allocate at least 16 regardless of page
145  * size.
146  */
147 #if (65536/PAGE_SIZE + 1) < 16
148 #define MAX_SKB_FRAGS 16UL
149 #else
150 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
151 #endif
152 
153 typedef struct skb_frag_struct skb_frag_t;
154 
155 struct skb_frag_struct {
156         struct {
157                 struct page *p;
158         } page;
159 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
160         __u32 page_offset;
161         __u32 size;
162 #else
163         __u16 page_offset;
164         __u16 size;
165 #endif
166 };
167 
168 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
169 {
170         return frag->size;
171 }
172 
173 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
174 {
175         frag->size = size;
176 }
177 
178 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
179 {
180         frag->size += delta;
181 }
182 
183 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
184 {
185         frag->size -= delta;
186 }
187 
188 #define HAVE_HW_TIME_STAMP
189 
190 /**
191  * struct skb_shared_hwtstamps - hardware time stamps
192  * @hwtstamp:   hardware time stamp transformed into duration
193  *              since arbitrary point in time
194  * @syststamp:  hwtstamp transformed to system time base
195  *
196  * Software time stamps generated by ktime_get_real() are stored in
197  * skb->tstamp. The relation between the different kinds of time
198  * stamps is as follows:
199  *
200  * syststamp and tstamp can be compared against each other in
201  * arbitrary combinations.  The accuracy of a
202  * syststamp/tstamp/"syststamp from other device" comparison is
203  * limited by the accuracy of the transformation into system time
204  * base. This depends on the device driver and its underlying
205  * hardware.
206  *
207  * hwtstamps can only be compared against other hwtstamps from
208  * the same device.
209  *
210  * This structure is attached to packets as part of the
211  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
212  */
213 struct skb_shared_hwtstamps {
214         ktime_t hwtstamp;
215         ktime_t syststamp;
216 };
217 
218 /* Definitions for tx_flags in struct skb_shared_info */
219 enum {
220         /* generate hardware time stamp */
221         SKBTX_HW_TSTAMP = 1 << 0,
222 
223         /* generate software time stamp */
224         SKBTX_SW_TSTAMP = 1 << 1,
225 
226         /* device driver is going to provide hardware time stamp */
227         SKBTX_IN_PROGRESS = 1 << 2,
228 
229         /* device driver supports TX zero-copy buffers */
230         SKBTX_DEV_ZEROCOPY = 1 << 3,
231 
232         /* generate wifi status information (where possible) */
233         SKBTX_WIFI_STATUS = 1 << 4,
234 
235         /* This indicates at least one fragment might be overwritten
236          * (as in vmsplice(), sendfile() ...)
237          * If we need to compute a TX checksum, we'll need to copy
238          * all frags to avoid possible bad checksum
239          */
240         SKBTX_SHARED_FRAG = 1 << 5,
241 };
242 
243 /*
244  * The callback notifies userspace to release buffers when skb DMA is done in
245  * lower device, the skb last reference should be 0 when calling this.
246  * The zerocopy_success argument is true if zero copy transmit occurred,
247  * false on data copy or out of memory error caused by data copy attempt.
248  * The ctx field is used to track device context.
249  * The desc field is used to track userspace buffer index.
250  */
251 struct ubuf_info {
252         void (*callback)(struct ubuf_info *, bool zerocopy_success);
253         void *ctx;
254         unsigned long desc;
255 };
256 
257 /* This data is invariant across clones and lives at
258  * the end of the header data, ie. at skb->end.
259  */
260 struct skb_shared_info {
261         unsigned char   nr_frags;
262         __u8            tx_flags;
263         unsigned short  gso_size;
264         /* Warning: this field is not always filled in (UFO)! */
265         unsigned short  gso_segs;
266         unsigned short  gso_type;
267         struct sk_buff  *frag_list;
268         struct skb_shared_hwtstamps hwtstamps;
269         __be32          ip6_frag_id;
270 
271         /*
272          * Warning : all fields before dataref are cleared in __alloc_skb()
273          */
274         atomic_t        dataref;
275 
276         /* Intermediate layers must ensure that destructor_arg
277          * remains valid until skb destructor */
278         void *          destructor_arg;
279 
280         /* must be last field, see pskb_expand_head() */
281         skb_frag_t      frags[MAX_SKB_FRAGS];
282 };
283 
284 /* We divide dataref into two halves.  The higher 16 bits hold references
285  * to the payload part of skb->data.  The lower 16 bits hold references to
286  * the entire skb->data.  A clone of a headerless skb holds the length of
287  * the header in skb->hdr_len.
288  *
289  * All users must obey the rule that the skb->data reference count must be
290  * greater than or equal to the payload reference count.
291  *
292  * Holding a reference to the payload part means that the user does not
293  * care about modifications to the header part of skb->data.
294  */
295 #define SKB_DATAREF_SHIFT 16
296 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
297 
298 
299 enum {
300         SKB_FCLONE_UNAVAILABLE,
301         SKB_FCLONE_ORIG,
302         SKB_FCLONE_CLONE,
303 };
304 
305 enum {
306         SKB_GSO_TCPV4 = 1 << 0,
307         SKB_GSO_UDP = 1 << 1,
308 
309         /* This indicates the skb is from an untrusted source. */
310         SKB_GSO_DODGY = 1 << 2,
311 
312         /* This indicates the tcp segment has CWR set. */
313         SKB_GSO_TCP_ECN = 1 << 3,
314 
315         SKB_GSO_TCPV6 = 1 << 4,
316 
317         SKB_GSO_FCOE = 1 << 5,
318 
319         SKB_GSO_GRE = 1 << 6,
320 
321         SKB_GSO_UDP_TUNNEL = 1 << 7,
322 
323         SKB_GSO_MPLS = 1 << 8,
324 };
325 
326 #if BITS_PER_LONG > 32
327 #define NET_SKBUFF_DATA_USES_OFFSET 1
328 #endif
329 
330 #ifdef NET_SKBUFF_DATA_USES_OFFSET
331 typedef unsigned int sk_buff_data_t;
332 #else
333 typedef unsigned char *sk_buff_data_t;
334 #endif
335 
336 #if defined(CONFIG_NF_DEFRAG_IPV4) || defined(CONFIG_NF_DEFRAG_IPV4_MODULE) || \
337     defined(CONFIG_NF_DEFRAG_IPV6) || defined(CONFIG_NF_DEFRAG_IPV6_MODULE)
338 #define NET_SKBUFF_NF_DEFRAG_NEEDED 1
339 #endif
340 
341 /** 
342  *      struct sk_buff - socket buffer
343  *      @next: Next buffer in list
344  *      @prev: Previous buffer in list
345  *      @tstamp: Time we arrived
346  *      @sk: Socket we are owned by
347  *      @dev: Device we arrived on/are leaving by
348  *      @cb: Control buffer. Free for use by every layer. Put private vars here
349  *      @_skb_refdst: destination entry (with norefcount bit)
350  *      @sp: the security path, used for xfrm
351  *      @len: Length of actual data
352  *      @data_len: Data length
353  *      @mac_len: Length of link layer header
354  *      @hdr_len: writable header length of cloned skb
355  *      @csum: Checksum (must include start/offset pair)
356  *      @csum_start: Offset from skb->head where checksumming should start
357  *      @csum_offset: Offset from csum_start where checksum should be stored
358  *      @priority: Packet queueing priority
359  *      @local_df: allow local fragmentation
360  *      @cloned: Head may be cloned (check refcnt to be sure)
361  *      @ip_summed: Driver fed us an IP checksum
362  *      @nohdr: Payload reference only, must not modify header
363  *      @nfctinfo: Relationship of this skb to the connection
364  *      @pkt_type: Packet class
365  *      @fclone: skbuff clone status
366  *      @ipvs_property: skbuff is owned by ipvs
367  *      @peeked: this packet has been seen already, so stats have been
368  *              done for it, don't do them again
369  *      @nf_trace: netfilter packet trace flag
370  *      @protocol: Packet protocol from driver
371  *      @destructor: Destruct function
372  *      @nfct: Associated connection, if any
373  *      @nfct_reasm: netfilter conntrack re-assembly pointer
374  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
375  *      @skb_iif: ifindex of device we arrived on
376  *      @tc_index: Traffic control index
377  *      @tc_verd: traffic control verdict
378  *      @rxhash: the packet hash computed on receive
379  *      @queue_mapping: Queue mapping for multiqueue devices
380  *      @ndisc_nodetype: router type (from link layer)
381  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
382  *      @l4_rxhash: indicate rxhash is a canonical 4-tuple hash over transport
383  *              ports.
384  *      @wifi_acked_valid: wifi_acked was set
385  *      @wifi_acked: whether frame was acked on wifi or not
386  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
387  *      @dma_cookie: a cookie to one of several possible DMA operations
388  *              done by skb DMA functions
389   *     @napi_id: id of the NAPI struct this skb came from
390  *      @secmark: security marking
391  *      @mark: Generic packet mark
392  *      @dropcount: total number of sk_receive_queue overflows
393  *      @vlan_proto: vlan encapsulation protocol
394  *      @vlan_tci: vlan tag control information
395  *      @inner_protocol: Protocol (encapsulation)
396  *      @inner_transport_header: Inner transport layer header (encapsulation)
397  *      @inner_network_header: Network layer header (encapsulation)
398  *      @inner_mac_header: Link layer header (encapsulation)
399  *      @transport_header: Transport layer header
400  *      @network_header: Network layer header
401  *      @mac_header: Link layer header
402  *      @tail: Tail pointer
403  *      @end: End pointer
404  *      @head: Head of buffer
405  *      @data: Data head pointer
406  *      @truesize: Buffer size
407  *      @users: User count - see {datagram,tcp}.c
408  */
409 
410 struct sk_buff {
411         /* These two members must be first. */
412         struct sk_buff          *next;
413         struct sk_buff          *prev;
414 
415         ktime_t                 tstamp;
416 
417         struct sock             *sk;
418         struct net_device       *dev;
419 
420         /*
421          * This is the control buffer. It is free to use for every
422          * layer. Please put your private variables there. If you
423          * want to keep them across layers you have to do a skb_clone()
424          * first. This is owned by whoever has the skb queued ATM.
425          */
426         char                    cb[48] __aligned(8);
427 
428         unsigned long           _skb_refdst;
429 #ifdef CONFIG_XFRM
430         struct  sec_path        *sp;
431 #endif
432         unsigned int            len,
433                                 data_len;
434         __u16                   mac_len,
435                                 hdr_len;
436         union {
437                 __wsum          csum;
438                 struct {
439                         __u16   csum_start;
440                         __u16   csum_offset;
441                 };
442         };
443         __u32                   priority;
444         kmemcheck_bitfield_begin(flags1);
445         __u8                    local_df:1,
446                                 cloned:1,
447                                 ip_summed:2,
448                                 nohdr:1,
449                                 nfctinfo:3;
450         __u8                    pkt_type:3,
451                                 fclone:2,
452                                 ipvs_property:1,
453                                 peeked:1,
454                                 nf_trace:1;
455         kmemcheck_bitfield_end(flags1);
456         __be16                  protocol;
457 
458         void                    (*destructor)(struct sk_buff *skb);
459 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
460         struct nf_conntrack     *nfct;
461 #endif
462 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
463         struct sk_buff          *nfct_reasm;
464 #endif
465 #ifdef CONFIG_BRIDGE_NETFILTER
466         struct nf_bridge_info   *nf_bridge;
467 #endif
468 
469         int                     skb_iif;
470 
471         __u32                   rxhash;
472 
473         __be16                  vlan_proto;
474         __u16                   vlan_tci;
475 
476 #ifdef CONFIG_NET_SCHED
477         __u16                   tc_index;       /* traffic control index */
478 #ifdef CONFIG_NET_CLS_ACT
479         __u16                   tc_verd;        /* traffic control verdict */
480 #endif
481 #endif
482 
483         __u16                   queue_mapping;
484         kmemcheck_bitfield_begin(flags2);
485 #ifdef CONFIG_IPV6_NDISC_NODETYPE
486         __u8                    ndisc_nodetype:2;
487 #endif
488         __u8                    pfmemalloc:1;
489         __u8                    ooo_okay:1;
490         __u8                    l4_rxhash:1;
491         __u8                    wifi_acked_valid:1;
492         __u8                    wifi_acked:1;
493         __u8                    no_fcs:1;
494         __u8                    head_frag:1;
495         /* Encapsulation protocol and NIC drivers should use
496          * this flag to indicate to each other if the skb contains
497          * encapsulated packet or not and maybe use the inner packet
498          * headers if needed
499          */
500         __u8                    encapsulation:1;
501         /* 7/9 bit hole (depending on ndisc_nodetype presence) */
502         kmemcheck_bitfield_end(flags2);
503 
504 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
505         union {
506                 unsigned int    napi_id;
507                 dma_cookie_t    dma_cookie;
508         };
509 #endif
510 #ifdef CONFIG_NETWORK_SECMARK
511         __u32                   secmark;
512 #endif
513         union {
514                 __u32           mark;
515                 __u32           dropcount;
516                 __u32           reserved_tailroom;
517         };
518 
519         __be16                  inner_protocol;
520         __u16                   inner_transport_header;
521         __u16                   inner_network_header;
522         __u16                   inner_mac_header;
523         __u16                   transport_header;
524         __u16                   network_header;
525         __u16                   mac_header;
526         /* These elements must be at the end, see alloc_skb() for details.  */
527         sk_buff_data_t          tail;
528         sk_buff_data_t          end;
529         unsigned char           *head,
530                                 *data;
531         unsigned int            truesize;
532         atomic_t                users;
533 };
534 
535 #ifdef __KERNEL__
536 /*
537  *      Handling routines are only of interest to the kernel
538  */
539 #include <linux/slab.h>
540 
541 
542 #define SKB_ALLOC_FCLONE        0x01
543 #define SKB_ALLOC_RX            0x02
544 
545 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
546 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
547 {
548         return unlikely(skb->pfmemalloc);
549 }
550 
551 /*
552  * skb might have a dst pointer attached, refcounted or not.
553  * _skb_refdst low order bit is set if refcount was _not_ taken
554  */
555 #define SKB_DST_NOREF   1UL
556 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
557 
558 /**
559  * skb_dst - returns skb dst_entry
560  * @skb: buffer
561  *
562  * Returns skb dst_entry, regardless of reference taken or not.
563  */
564 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
565 {
566         /* If refdst was not refcounted, check we still are in a 
567          * rcu_read_lock section
568          */
569         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
570                 !rcu_read_lock_held() &&
571                 !rcu_read_lock_bh_held());
572         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
573 }
574 
575 /**
576  * skb_dst_set - sets skb dst
577  * @skb: buffer
578  * @dst: dst entry
579  *
580  * Sets skb dst, assuming a reference was taken on dst and should
581  * be released by skb_dst_drop()
582  */
583 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
584 {
585         skb->_skb_refdst = (unsigned long)dst;
586 }
587 
588 extern void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
589                                 bool force);
590 
591 /**
592  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
593  * @skb: buffer
594  * @dst: dst entry
595  *
596  * Sets skb dst, assuming a reference was not taken on dst.
597  * If dst entry is cached, we do not take reference and dst_release
598  * will be avoided by refdst_drop. If dst entry is not cached, we take
599  * reference, so that last dst_release can destroy the dst immediately.
600  */
601 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
602 {
603         __skb_dst_set_noref(skb, dst, false);
604 }
605 
606 /**
607  * skb_dst_set_noref_force - sets skb dst, without taking reference
608  * @skb: buffer
609  * @dst: dst entry
610  *
611  * Sets skb dst, assuming a reference was not taken on dst.
612  * No reference is taken and no dst_release will be called. While for
613  * cached dsts deferred reclaim is a basic feature, for entries that are
614  * not cached it is caller's job to guarantee that last dst_release for
615  * provided dst happens when nobody uses it, eg. after a RCU grace period.
616  */
617 static inline void skb_dst_set_noref_force(struct sk_buff *skb,
618                                            struct dst_entry *dst)
619 {
620         __skb_dst_set_noref(skb, dst, true);
621 }
622 
623 /**
624  * skb_dst_is_noref - Test if skb dst isn't refcounted
625  * @skb: buffer
626  */
627 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
628 {
629         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
630 }
631 
632 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
633 {
634         return (struct rtable *)skb_dst(skb);
635 }
636 
637 extern void kfree_skb(struct sk_buff *skb);
638 extern void kfree_skb_list(struct sk_buff *segs);
639 extern void skb_tx_error(struct sk_buff *skb);
640 extern void consume_skb(struct sk_buff *skb);
641 extern void            __kfree_skb(struct sk_buff *skb);
642 extern struct kmem_cache *skbuff_head_cache;
643 
644 extern void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
645 extern bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
646                              bool *fragstolen, int *delta_truesize);
647 
648 extern struct sk_buff *__alloc_skb(unsigned int size,
649                                    gfp_t priority, int flags, int node);
650 extern struct sk_buff *build_skb(void *data, unsigned int frag_size);
651 static inline struct sk_buff *alloc_skb(unsigned int size,
652                                         gfp_t priority)
653 {
654         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
655 }
656 
657 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
658                                                gfp_t priority)
659 {
660         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
661 }
662 
663 extern struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
664 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
665 {
666         return __alloc_skb_head(priority, -1);
667 }
668 
669 extern struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
670 extern int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
671 extern struct sk_buff *skb_clone(struct sk_buff *skb,
672                                  gfp_t priority);
673 extern struct sk_buff *skb_copy(const struct sk_buff *skb,
674                                 gfp_t priority);
675 extern struct sk_buff *__pskb_copy(struct sk_buff *skb,
676                                  int headroom, gfp_t gfp_mask);
677 
678 extern int             pskb_expand_head(struct sk_buff *skb,
679                                         int nhead, int ntail,
680                                         gfp_t gfp_mask);
681 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
682                                             unsigned int headroom);
683 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
684                                        int newheadroom, int newtailroom,
685                                        gfp_t priority);
686 extern int             skb_to_sgvec(struct sk_buff *skb,
687                                     struct scatterlist *sg, int offset,
688                                     int len);
689 extern int             skb_cow_data(struct sk_buff *skb, int tailbits,
690                                     struct sk_buff **trailer);
691 extern int             skb_pad(struct sk_buff *skb, int pad);
692 #define dev_kfree_skb(a)        consume_skb(a)
693 
694 extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
695                         int getfrag(void *from, char *to, int offset,
696                         int len,int odd, struct sk_buff *skb),
697                         void *from, int length);
698 
699 struct skb_seq_state {
700         __u32           lower_offset;
701         __u32           upper_offset;
702         __u32           frag_idx;
703         __u32           stepped_offset;
704         struct sk_buff  *root_skb;
705         struct sk_buff  *cur_skb;
706         __u8            *frag_data;
707 };
708 
709 extern void           skb_prepare_seq_read(struct sk_buff *skb,
710                                            unsigned int from, unsigned int to,
711                                            struct skb_seq_state *st);
712 extern unsigned int   skb_seq_read(unsigned int consumed, const u8 **data,
713                                    struct skb_seq_state *st);
714 extern void           skb_abort_seq_read(struct skb_seq_state *st);
715 
716 extern unsigned int   skb_find_text(struct sk_buff *skb, unsigned int from,
717                                     unsigned int to, struct ts_config *config,
718                                     struct ts_state *state);
719 
720 extern void __skb_get_rxhash(struct sk_buff *skb);
721 static inline __u32 skb_get_rxhash(struct sk_buff *skb)
722 {
723         if (!skb->l4_rxhash)
724                 __skb_get_rxhash(skb);
725 
726         return skb->rxhash;
727 }
728 
729 #ifdef NET_SKBUFF_DATA_USES_OFFSET
730 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
731 {
732         return skb->head + skb->end;
733 }
734 
735 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
736 {
737         return skb->end;
738 }
739 #else
740 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
741 {
742         return skb->end;
743 }
744 
745 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
746 {
747         return skb->end - skb->head;
748 }
749 #endif
750 
751 /* Internal */
752 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
753 
754 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
755 {
756         return &skb_shinfo(skb)->hwtstamps;
757 }
758 
759 /**
760  *      skb_queue_empty - check if a queue is empty
761  *      @list: queue head
762  *
763  *      Returns true if the queue is empty, false otherwise.
764  */
765 static inline int skb_queue_empty(const struct sk_buff_head *list)
766 {
767         return list->next == (struct sk_buff *)list;
768 }
769 
770 /**
771  *      skb_queue_is_last - check if skb is the last entry in the queue
772  *      @list: queue head
773  *      @skb: buffer
774  *
775  *      Returns true if @skb is the last buffer on the list.
776  */
777 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
778                                      const struct sk_buff *skb)
779 {
780         return skb->next == (struct sk_buff *)list;
781 }
782 
783 /**
784  *      skb_queue_is_first - check if skb is the first entry in the queue
785  *      @list: queue head
786  *      @skb: buffer
787  *
788  *      Returns true if @skb is the first buffer on the list.
789  */
790 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
791                                       const struct sk_buff *skb)
792 {
793         return skb->prev == (struct sk_buff *)list;
794 }
795 
796 /**
797  *      skb_queue_next - return the next packet in the queue
798  *      @list: queue head
799  *      @skb: current buffer
800  *
801  *      Return the next packet in @list after @skb.  It is only valid to
802  *      call this if skb_queue_is_last() evaluates to false.
803  */
804 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
805                                              const struct sk_buff *skb)
806 {
807         /* This BUG_ON may seem severe, but if we just return then we
808          * are going to dereference garbage.
809          */
810         BUG_ON(skb_queue_is_last(list, skb));
811         return skb->next;
812 }
813 
814 /**
815  *      skb_queue_prev - return the prev packet in the queue
816  *      @list: queue head
817  *      @skb: current buffer
818  *
819  *      Return the prev packet in @list before @skb.  It is only valid to
820  *      call this if skb_queue_is_first() evaluates to false.
821  */
822 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
823                                              const struct sk_buff *skb)
824 {
825         /* This BUG_ON may seem severe, but if we just return then we
826          * are going to dereference garbage.
827          */
828         BUG_ON(skb_queue_is_first(list, skb));
829         return skb->prev;
830 }
831 
832 /**
833  *      skb_get - reference buffer
834  *      @skb: buffer to reference
835  *
836  *      Makes another reference to a socket buffer and returns a pointer
837  *      to the buffer.
838  */
839 static inline struct sk_buff *skb_get(struct sk_buff *skb)
840 {
841         atomic_inc(&skb->users);
842         return skb;
843 }
844 
845 /*
846  * If users == 1, we are the only owner and are can avoid redundant
847  * atomic change.
848  */
849 
850 /**
851  *      skb_cloned - is the buffer a clone
852  *      @skb: buffer to check
853  *
854  *      Returns true if the buffer was generated with skb_clone() and is
855  *      one of multiple shared copies of the buffer. Cloned buffers are
856  *      shared data so must not be written to under normal circumstances.
857  */
858 static inline int skb_cloned(const struct sk_buff *skb)
859 {
860         return skb->cloned &&
861                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
862 }
863 
864 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
865 {
866         might_sleep_if(pri & __GFP_WAIT);
867 
868         if (skb_cloned(skb))
869                 return pskb_expand_head(skb, 0, 0, pri);
870 
871         return 0;
872 }
873 
874 /**
875  *      skb_header_cloned - is the header a clone
876  *      @skb: buffer to check
877  *
878  *      Returns true if modifying the header part of the buffer requires
879  *      the data to be copied.
880  */
881 static inline int skb_header_cloned(const struct sk_buff *skb)
882 {
883         int dataref;
884 
885         if (!skb->cloned)
886                 return 0;
887 
888         dataref = atomic_read(&skb_shinfo(skb)->dataref);
889         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
890         return dataref != 1;
891 }
892 
893 /**
894  *      skb_header_release - release reference to header
895  *      @skb: buffer to operate on
896  *
897  *      Drop a reference to the header part of the buffer.  This is done
898  *      by acquiring a payload reference.  You must not read from the header
899  *      part of skb->data after this.
900  */
901 static inline void skb_header_release(struct sk_buff *skb)
902 {
903         BUG_ON(skb->nohdr);
904         skb->nohdr = 1;
905         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
906 }
907 
908 /**
909  *      skb_shared - is the buffer shared
910  *      @skb: buffer to check
911  *
912  *      Returns true if more than one person has a reference to this
913  *      buffer.
914  */
915 static inline int skb_shared(const struct sk_buff *skb)
916 {
917         return atomic_read(&skb->users) != 1;
918 }
919 
920 /**
921  *      skb_share_check - check if buffer is shared and if so clone it
922  *      @skb: buffer to check
923  *      @pri: priority for memory allocation
924  *
925  *      If the buffer is shared the buffer is cloned and the old copy
926  *      drops a reference. A new clone with a single reference is returned.
927  *      If the buffer is not shared the original buffer is returned. When
928  *      being called from interrupt status or with spinlocks held pri must
929  *      be GFP_ATOMIC.
930  *
931  *      NULL is returned on a memory allocation failure.
932  */
933 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
934 {
935         might_sleep_if(pri & __GFP_WAIT);
936         if (skb_shared(skb)) {
937                 struct sk_buff *nskb = skb_clone(skb, pri);
938 
939                 if (likely(nskb))
940                         consume_skb(skb);
941                 else
942                         kfree_skb(skb);
943                 skb = nskb;
944         }
945         return skb;
946 }
947 
948 /*
949  *      Copy shared buffers into a new sk_buff. We effectively do COW on
950  *      packets to handle cases where we have a local reader and forward
951  *      and a couple of other messy ones. The normal one is tcpdumping
952  *      a packet thats being forwarded.
953  */
954 
955 /**
956  *      skb_unshare - make a copy of a shared buffer
957  *      @skb: buffer to check
958  *      @pri: priority for memory allocation
959  *
960  *      If the socket buffer is a clone then this function creates a new
961  *      copy of the data, drops a reference count on the old copy and returns
962  *      the new copy with the reference count at 1. If the buffer is not a clone
963  *      the original buffer is returned. When called with a spinlock held or
964  *      from interrupt state @pri must be %GFP_ATOMIC
965  *
966  *      %NULL is returned on a memory allocation failure.
967  */
968 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
969                                           gfp_t pri)
970 {
971         might_sleep_if(pri & __GFP_WAIT);
972         if (skb_cloned(skb)) {
973                 struct sk_buff *nskb = skb_copy(skb, pri);
974                 kfree_skb(skb); /* Free our shared copy */
975                 skb = nskb;
976         }
977         return skb;
978 }
979 
980 /**
981  *      skb_peek - peek at the head of an &sk_buff_head
982  *      @list_: list to peek at
983  *
984  *      Peek an &sk_buff. Unlike most other operations you _MUST_
985  *      be careful with this one. A peek leaves the buffer on the
986  *      list and someone else may run off with it. You must hold
987  *      the appropriate locks or have a private queue to do this.
988  *
989  *      Returns %NULL for an empty list or a pointer to the head element.
990  *      The reference count is not incremented and the reference is therefore
991  *      volatile. Use with caution.
992  */
993 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
994 {
995         struct sk_buff *skb = list_->next;
996 
997         if (skb == (struct sk_buff *)list_)
998                 skb = NULL;
999         return skb;
1000 }
1001 
1002 /**
1003  *      skb_peek_next - peek skb following the given one from a queue
1004  *      @skb: skb to start from
1005  *      @list_: list to peek at
1006  *
1007  *      Returns %NULL when the end of the list is met or a pointer to the
1008  *      next element. The reference count is not incremented and the
1009  *      reference is therefore volatile. Use with caution.
1010  */
1011 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1012                 const struct sk_buff_head *list_)
1013 {
1014         struct sk_buff *next = skb->next;
1015 
1016         if (next == (struct sk_buff *)list_)
1017                 next = NULL;
1018         return next;
1019 }
1020 
1021 /**
1022  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1023  *      @list_: list to peek at
1024  *
1025  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1026  *      be careful with this one. A peek leaves the buffer on the
1027  *      list and someone else may run off with it. You must hold
1028  *      the appropriate locks or have a private queue to do this.
1029  *
1030  *      Returns %NULL for an empty list or a pointer to the tail element.
1031  *      The reference count is not incremented and the reference is therefore
1032  *      volatile. Use with caution.
1033  */
1034 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1035 {
1036         struct sk_buff *skb = list_->prev;
1037 
1038         if (skb == (struct sk_buff *)list_)
1039                 skb = NULL;
1040         return skb;
1041 
1042 }
1043 
1044 /**
1045  *      skb_queue_len   - get queue length
1046  *      @list_: list to measure
1047  *
1048  *      Return the length of an &sk_buff queue.
1049  */
1050 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1051 {
1052         return list_->qlen;
1053 }
1054 
1055 /**
1056  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1057  *      @list: queue to initialize
1058  *
1059  *      This initializes only the list and queue length aspects of
1060  *      an sk_buff_head object.  This allows to initialize the list
1061  *      aspects of an sk_buff_head without reinitializing things like
1062  *      the spinlock.  It can also be used for on-stack sk_buff_head
1063  *      objects where the spinlock is known to not be used.
1064  */
1065 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1066 {
1067         list->prev = list->next = (struct sk_buff *)list;
1068         list->qlen = 0;
1069 }
1070 
1071 /*
1072  * This function creates a split out lock class for each invocation;
1073  * this is needed for now since a whole lot of users of the skb-queue
1074  * infrastructure in drivers have different locking usage (in hardirq)
1075  * than the networking core (in softirq only). In the long run either the
1076  * network layer or drivers should need annotation to consolidate the
1077  * main types of usage into 3 classes.
1078  */
1079 static inline void skb_queue_head_init(struct sk_buff_head *list)
1080 {
1081         spin_lock_init(&list->lock);
1082         __skb_queue_head_init(list);
1083 }
1084 
1085 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1086                 struct lock_class_key *class)
1087 {
1088         skb_queue_head_init(list);
1089         lockdep_set_class(&list->lock, class);
1090 }
1091 
1092 /*
1093  *      Insert an sk_buff on a list.
1094  *
1095  *      The "__skb_xxxx()" functions are the non-atomic ones that
1096  *      can only be called with interrupts disabled.
1097  */
1098 extern void        skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
1099 static inline void __skb_insert(struct sk_buff *newsk,
1100                                 struct sk_buff *prev, struct sk_buff *next,
1101                                 struct sk_buff_head *list)
1102 {
1103         newsk->next = next;
1104         newsk->prev = prev;
1105         next->prev  = prev->next = newsk;
1106         list->qlen++;
1107 }
1108 
1109 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1110                                       struct sk_buff *prev,
1111                                       struct sk_buff *next)
1112 {
1113         struct sk_buff *first = list->next;
1114         struct sk_buff *last = list->prev;
1115 
1116         first->prev = prev;
1117         prev->next = first;
1118 
1119         last->next = next;
1120         next->prev = last;
1121 }
1122 
1123 /**
1124  *      skb_queue_splice - join two skb lists, this is designed for stacks
1125  *      @list: the new list to add
1126  *      @head: the place to add it in the first list
1127  */
1128 static inline void skb_queue_splice(const struct sk_buff_head *list,
1129                                     struct sk_buff_head *head)
1130 {
1131         if (!skb_queue_empty(list)) {
1132                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1133                 head->qlen += list->qlen;
1134         }
1135 }
1136 
1137 /**
1138  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1139  *      @list: the new list to add
1140  *      @head: the place to add it in the first list
1141  *
1142  *      The list at @list is reinitialised
1143  */
1144 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1145                                          struct sk_buff_head *head)
1146 {
1147         if (!skb_queue_empty(list)) {
1148                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1149                 head->qlen += list->qlen;
1150                 __skb_queue_head_init(list);
1151         }
1152 }
1153 
1154 /**
1155  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1156  *      @list: the new list to add
1157  *      @head: the place to add it in the first list
1158  */
1159 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1160                                          struct sk_buff_head *head)
1161 {
1162         if (!skb_queue_empty(list)) {
1163                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1164                 head->qlen += list->qlen;
1165         }
1166 }
1167 
1168 /**
1169  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1170  *      @list: the new list to add
1171  *      @head: the place to add it in the first list
1172  *
1173  *      Each of the lists is a queue.
1174  *      The list at @list is reinitialised
1175  */
1176 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1177                                               struct sk_buff_head *head)
1178 {
1179         if (!skb_queue_empty(list)) {
1180                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1181                 head->qlen += list->qlen;
1182                 __skb_queue_head_init(list);
1183         }
1184 }
1185 
1186 /**
1187  *      __skb_queue_after - queue a buffer at the list head
1188  *      @list: list to use
1189  *      @prev: place after this buffer
1190  *      @newsk: buffer to queue
1191  *
1192  *      Queue a buffer int the middle of a list. This function takes no locks
1193  *      and you must therefore hold required locks before calling it.
1194  *
1195  *      A buffer cannot be placed on two lists at the same time.
1196  */
1197 static inline void __skb_queue_after(struct sk_buff_head *list,
1198                                      struct sk_buff *prev,
1199                                      struct sk_buff *newsk)
1200 {
1201         __skb_insert(newsk, prev, prev->next, list);
1202 }
1203 
1204 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1205                        struct sk_buff_head *list);
1206 
1207 static inline void __skb_queue_before(struct sk_buff_head *list,
1208                                       struct sk_buff *next,
1209                                       struct sk_buff *newsk)
1210 {
1211         __skb_insert(newsk, next->prev, next, list);
1212 }
1213 
1214 /**
1215  *      __skb_queue_head - queue a buffer at the list head
1216  *      @list: list to use
1217  *      @newsk: buffer to queue
1218  *
1219  *      Queue a buffer at the start of a list. This function takes no locks
1220  *      and you must therefore hold required locks before calling it.
1221  *
1222  *      A buffer cannot be placed on two lists at the same time.
1223  */
1224 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1225 static inline void __skb_queue_head(struct sk_buff_head *list,
1226                                     struct sk_buff *newsk)
1227 {
1228         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1229 }
1230 
1231 /**
1232  *      __skb_queue_tail - queue a buffer at the list tail
1233  *      @list: list to use
1234  *      @newsk: buffer to queue
1235  *
1236  *      Queue a buffer at the end of a list. This function takes no locks
1237  *      and you must therefore hold required locks before calling it.
1238  *
1239  *      A buffer cannot be placed on two lists at the same time.
1240  */
1241 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1242 static inline void __skb_queue_tail(struct sk_buff_head *list,
1243                                    struct sk_buff *newsk)
1244 {
1245         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1246 }
1247 
1248 /*
1249  * remove sk_buff from list. _Must_ be called atomically, and with
1250  * the list known..
1251  */
1252 extern void        skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1253 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1254 {
1255         struct sk_buff *next, *prev;
1256 
1257         list->qlen--;
1258         next       = skb->next;
1259         prev       = skb->prev;
1260         skb->next  = skb->prev = NULL;
1261         next->prev = prev;
1262         prev->next = next;
1263 }
1264 
1265 /**
1266  *      __skb_dequeue - remove from the head of the queue
1267  *      @list: list to dequeue from
1268  *
1269  *      Remove the head of the list. This function does not take any locks
1270  *      so must be used with appropriate locks held only. The head item is
1271  *      returned or %NULL if the list is empty.
1272  */
1273 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1274 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1275 {
1276         struct sk_buff *skb = skb_peek(list);
1277         if (skb)
1278                 __skb_unlink(skb, list);
1279         return skb;
1280 }
1281 
1282 /**
1283  *      __skb_dequeue_tail - remove from the tail of the queue
1284  *      @list: list to dequeue from
1285  *
1286  *      Remove the tail of the list. This function does not take any locks
1287  *      so must be used with appropriate locks held only. The tail item is
1288  *      returned or %NULL if the list is empty.
1289  */
1290 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1291 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1292 {
1293         struct sk_buff *skb = skb_peek_tail(list);
1294         if (skb)
1295                 __skb_unlink(skb, list);
1296         return skb;
1297 }
1298 
1299 
1300 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1301 {
1302         return skb->data_len;
1303 }
1304 
1305 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1306 {
1307         return skb->len - skb->data_len;
1308 }
1309 
1310 static inline int skb_pagelen(const struct sk_buff *skb)
1311 {
1312         int i, len = 0;
1313 
1314         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1315                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1316         return len + skb_headlen(skb);
1317 }
1318 
1319 static inline bool skb_has_frags(const struct sk_buff *skb)
1320 {
1321         return skb_shinfo(skb)->nr_frags;
1322 }
1323 
1324 /**
1325  * __skb_fill_page_desc - initialise a paged fragment in an skb
1326  * @skb: buffer containing fragment to be initialised
1327  * @i: paged fragment index to initialise
1328  * @page: the page to use for this fragment
1329  * @off: the offset to the data with @page
1330  * @size: the length of the data
1331  *
1332  * Initialises the @i'th fragment of @skb to point to &size bytes at
1333  * offset @off within @page.
1334  *
1335  * Does not take any additional reference on the fragment.
1336  */
1337 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1338                                         struct page *page, int off, int size)
1339 {
1340         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1341 
1342         /*
1343          * Propagate page->pfmemalloc to the skb if we can. The problem is
1344          * that not all callers have unique ownership of the page. If
1345          * pfmemalloc is set, we check the mapping as a mapping implies
1346          * page->index is set (index and pfmemalloc share space).
1347          * If it's a valid mapping, we cannot use page->pfmemalloc but we
1348          * do not lose pfmemalloc information as the pages would not be
1349          * allocated using __GFP_MEMALLOC.
1350          */
1351         frag->page.p              = page;
1352         frag->page_offset         = off;
1353         skb_frag_size_set(frag, size);
1354 
1355         page = compound_head(page);
1356         if (page->pfmemalloc && !page->mapping)
1357                 skb->pfmemalloc = true;
1358 }
1359 
1360 /**
1361  * skb_fill_page_desc - initialise a paged fragment in an skb
1362  * @skb: buffer containing fragment to be initialised
1363  * @i: paged fragment index to initialise
1364  * @page: the page to use for this fragment
1365  * @off: the offset to the data with @page
1366  * @size: the length of the data
1367  *
1368  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1369  * @skb to point to &size bytes at offset @off within @page. In
1370  * addition updates @skb such that @i is the last fragment.
1371  *
1372  * Does not take any additional reference on the fragment.
1373  */
1374 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1375                                       struct page *page, int off, int size)
1376 {
1377         __skb_fill_page_desc(skb, i, page, off, size);
1378         skb_shinfo(skb)->nr_frags = i + 1;
1379 }
1380 
1381 extern void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page,
1382                             int off, int size, unsigned int truesize);
1383 
1384 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1385 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1386 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1387 
1388 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1389 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1390 {
1391         return skb->head + skb->tail;
1392 }
1393 
1394 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1395 {
1396         skb->tail = skb->data - skb->head;
1397 }
1398 
1399 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1400 {
1401         skb_reset_tail_pointer(skb);
1402         skb->tail += offset;
1403 }
1404 
1405 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1406 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1407 {
1408         return skb->tail;
1409 }
1410 
1411 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1412 {
1413         skb->tail = skb->data;
1414 }
1415 
1416 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1417 {
1418         skb->tail = skb->data + offset;
1419 }
1420 
1421 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1422 
1423 /*
1424  *      Add data to an sk_buff
1425  */
1426 extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1427 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1428 {
1429         unsigned char *tmp = skb_tail_pointer(skb);
1430         SKB_LINEAR_ASSERT(skb);
1431         skb->tail += len;
1432         skb->len  += len;
1433         return tmp;
1434 }
1435 
1436 extern unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1437 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1438 {
1439         skb->data -= len;
1440         skb->len  += len;
1441         return skb->data;
1442 }
1443 
1444 extern unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1445 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1446 {
1447         skb->len -= len;
1448         BUG_ON(skb->len < skb->data_len);
1449         return skb->data += len;
1450 }
1451 
1452 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1453 {
1454         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1455 }
1456 
1457 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1458 
1459 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1460 {
1461         if (len > skb_headlen(skb) &&
1462             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1463                 return NULL;
1464         skb->len -= len;
1465         return skb->data += len;
1466 }
1467 
1468 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1469 {
1470         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1471 }
1472 
1473 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1474 {
1475         if (likely(len <= skb_headlen(skb)))
1476                 return 1;
1477         if (unlikely(len > skb->len))
1478                 return 0;
1479         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1480 }
1481 
1482 /**
1483  *      skb_headroom - bytes at buffer head
1484  *      @skb: buffer to check
1485  *
1486  *      Return the number of bytes of free space at the head of an &sk_buff.
1487  */
1488 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1489 {
1490         return skb->data - skb->head;
1491 }
1492 
1493 /**
1494  *      skb_tailroom - bytes at buffer end
1495  *      @skb: buffer to check
1496  *
1497  *      Return the number of bytes of free space at the tail of an sk_buff
1498  */
1499 static inline int skb_tailroom(const struct sk_buff *skb)
1500 {
1501         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1502 }
1503 
1504 /**
1505  *      skb_availroom - bytes at buffer end
1506  *      @skb: buffer to check
1507  *
1508  *      Return the number of bytes of free space at the tail of an sk_buff
1509  *      allocated by sk_stream_alloc()
1510  */
1511 static inline int skb_availroom(const struct sk_buff *skb)
1512 {
1513         if (skb_is_nonlinear(skb))
1514                 return 0;
1515 
1516         return skb->end - skb->tail - skb->reserved_tailroom;
1517 }
1518 
1519 /**
1520  *      skb_reserve - adjust headroom
1521  *      @skb: buffer to alter
1522  *      @len: bytes to move
1523  *
1524  *      Increase the headroom of an empty &sk_buff by reducing the tail
1525  *      room. This is only allowed for an empty buffer.
1526  */
1527 static inline void skb_reserve(struct sk_buff *skb, int len)
1528 {
1529         skb->data += len;
1530         skb->tail += len;
1531 }
1532 
1533 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1534 {
1535         skb->inner_mac_header = skb->mac_header;
1536         skb->inner_network_header = skb->network_header;
1537         skb->inner_transport_header = skb->transport_header;
1538 }
1539 
1540 static inline void skb_reset_mac_len(struct sk_buff *skb)
1541 {
1542         skb->mac_len = skb->network_header - skb->mac_header;
1543 }
1544 
1545 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1546                                                         *skb)
1547 {
1548         return skb->head + skb->inner_transport_header;
1549 }
1550 
1551 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1552 {
1553         skb->inner_transport_header = skb->data - skb->head;
1554 }
1555 
1556 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1557                                                    const int offset)
1558 {
1559         skb_reset_inner_transport_header(skb);
1560         skb->inner_transport_header += offset;
1561 }
1562 
1563 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1564 {
1565         return skb->head + skb->inner_network_header;
1566 }
1567 
1568 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1569 {
1570         skb->inner_network_header = skb->data - skb->head;
1571 }
1572 
1573 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1574                                                 const int offset)
1575 {
1576         skb_reset_inner_network_header(skb);
1577         skb->inner_network_header += offset;
1578 }
1579 
1580 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1581 {
1582         return skb->head + skb->inner_mac_header;
1583 }
1584 
1585 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1586 {
1587         skb->inner_mac_header = skb->data - skb->head;
1588 }
1589 
1590 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1591                                             const int offset)
1592 {
1593         skb_reset_inner_mac_header(skb);
1594         skb->inner_mac_header += offset;
1595 }
1596 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1597 {
1598         return skb->transport_header != (typeof(skb->transport_header))~0U;
1599 }
1600 
1601 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1602 {
1603         return skb->head + skb->transport_header;
1604 }
1605 
1606 static inline void skb_reset_transport_header(struct sk_buff *skb)
1607 {
1608         skb->transport_header = skb->data - skb->head;
1609 }
1610 
1611 static inline void skb_set_transport_header(struct sk_buff *skb,
1612                                             const int offset)
1613 {
1614         skb_reset_transport_header(skb);
1615         skb->transport_header += offset;
1616 }
1617 
1618 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1619 {
1620         return skb->head + skb->network_header;
1621 }
1622 
1623 static inline void skb_reset_network_header(struct sk_buff *skb)
1624 {
1625         skb->network_header = skb->data - skb->head;
1626 }
1627 
1628 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1629 {
1630         skb_reset_network_header(skb);
1631         skb->network_header += offset;
1632 }
1633 
1634 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1635 {
1636         return skb->head + skb->mac_header;
1637 }
1638 
1639 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1640 {
1641         return skb->mac_header != (typeof(skb->mac_header))~0U;
1642 }
1643 
1644 static inline void skb_reset_mac_header(struct sk_buff *skb)
1645 {
1646         skb->mac_header = skb->data - skb->head;
1647 }
1648 
1649 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1650 {
1651         skb_reset_mac_header(skb);
1652         skb->mac_header += offset;
1653 }
1654 
1655 static inline void skb_probe_transport_header(struct sk_buff *skb,
1656                                               const int offset_hint)
1657 {
1658         struct flow_keys keys;
1659 
1660         if (skb_transport_header_was_set(skb))
1661                 return;
1662         else if (skb_flow_dissect(skb, &keys))
1663                 skb_set_transport_header(skb, keys.thoff);
1664         else
1665                 skb_set_transport_header(skb, offset_hint);
1666 }
1667 
1668 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
1669 {
1670         if (skb_mac_header_was_set(skb)) {
1671                 const unsigned char *old_mac = skb_mac_header(skb);
1672 
1673                 skb_set_mac_header(skb, -skb->mac_len);
1674                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
1675         }
1676 }
1677 
1678 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
1679 {
1680         return skb->csum_start - skb_headroom(skb);
1681 }
1682 
1683 static inline int skb_transport_offset(const struct sk_buff *skb)
1684 {
1685         return skb_transport_header(skb) - skb->data;
1686 }
1687 
1688 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1689 {
1690         return skb->transport_header - skb->network_header;
1691 }
1692 
1693 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
1694 {
1695         return skb->inner_transport_header - skb->inner_network_header;
1696 }
1697 
1698 static inline int skb_network_offset(const struct sk_buff *skb)
1699 {
1700         return skb_network_header(skb) - skb->data;
1701 }
1702 
1703 static inline int skb_inner_network_offset(const struct sk_buff *skb)
1704 {
1705         return skb_inner_network_header(skb) - skb->data;
1706 }
1707 
1708 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
1709 {
1710         return pskb_may_pull(skb, skb_network_offset(skb) + len);
1711 }
1712 
1713 /*
1714  * CPUs often take a performance hit when accessing unaligned memory
1715  * locations. The actual performance hit varies, it can be small if the
1716  * hardware handles it or large if we have to take an exception and fix it
1717  * in software.
1718  *
1719  * Since an ethernet header is 14 bytes network drivers often end up with
1720  * the IP header at an unaligned offset. The IP header can be aligned by
1721  * shifting the start of the packet by 2 bytes. Drivers should do this
1722  * with:
1723  *
1724  * skb_reserve(skb, NET_IP_ALIGN);
1725  *
1726  * The downside to this alignment of the IP header is that the DMA is now
1727  * unaligned. On some architectures the cost of an unaligned DMA is high
1728  * and this cost outweighs the gains made by aligning the IP header.
1729  *
1730  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1731  * to be overridden.
1732  */
1733 #ifndef NET_IP_ALIGN
1734 #define NET_IP_ALIGN    2
1735 #endif
1736 
1737 /*
1738  * The networking layer reserves some headroom in skb data (via
1739  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1740  * the header has to grow. In the default case, if the header has to grow
1741  * 32 bytes or less we avoid the reallocation.
1742  *
1743  * Unfortunately this headroom changes the DMA alignment of the resulting
1744  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1745  * on some architectures. An architecture can override this value,
1746  * perhaps setting it to a cacheline in size (since that will maintain
1747  * cacheline alignment of the DMA). It must be a power of 2.
1748  *
1749  * Various parts of the networking layer expect at least 32 bytes of
1750  * headroom, you should not reduce this.
1751  *
1752  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
1753  * to reduce average number of cache lines per packet.
1754  * get_rps_cpus() for example only access one 64 bytes aligned block :
1755  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
1756  */
1757 #ifndef NET_SKB_PAD
1758 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
1759 #endif
1760 
1761 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1762 
1763 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1764 {
1765         if (unlikely(skb_is_nonlinear(skb))) {
1766                 WARN_ON(1);
1767                 return;
1768         }
1769         skb->len = len;
1770         skb_set_tail_pointer(skb, len);
1771 }
1772 
1773 extern void skb_trim(struct sk_buff *skb, unsigned int len);
1774 
1775 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1776 {
1777         if (skb->data_len)
1778                 return ___pskb_trim(skb, len);
1779         __skb_trim(skb, len);
1780         return 0;
1781 }
1782 
1783 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1784 {
1785         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1786 }
1787 
1788 /**
1789  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1790  *      @skb: buffer to alter
1791  *      @len: new length
1792  *
1793  *      This is identical to pskb_trim except that the caller knows that
1794  *      the skb is not cloned so we should never get an error due to out-
1795  *      of-memory.
1796  */
1797 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1798 {
1799         int err = pskb_trim(skb, len);
1800         BUG_ON(err);
1801 }
1802 
1803 /**
1804  *      skb_orphan - orphan a buffer
1805  *      @skb: buffer to orphan
1806  *
1807  *      If a buffer currently has an owner then we call the owner's
1808  *      destructor function and make the @skb unowned. The buffer continues
1809  *      to exist but is no longer charged to its former owner.
1810  */
1811 static inline void skb_orphan(struct sk_buff *skb)
1812 {
1813         if (skb->destructor)
1814                 skb->destructor(skb);
1815         skb->destructor = NULL;
1816         skb->sk         = NULL;
1817 }
1818 
1819 /**
1820  *      skb_orphan_frags - orphan the frags contained in a buffer
1821  *      @skb: buffer to orphan frags from
1822  *      @gfp_mask: allocation mask for replacement pages
1823  *
1824  *      For each frag in the SKB which needs a destructor (i.e. has an
1825  *      owner) create a copy of that frag and release the original
1826  *      page by calling the destructor.
1827  */
1828 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
1829 {
1830         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
1831                 return 0;
1832         return skb_copy_ubufs(skb, gfp_mask);
1833 }
1834 
1835 /**
1836  *      __skb_queue_purge - empty a list
1837  *      @list: list to empty
1838  *
1839  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
1840  *      the list and one reference dropped. This function does not take the
1841  *      list lock and the caller must hold the relevant locks to use it.
1842  */
1843 extern void skb_queue_purge(struct sk_buff_head *list);
1844 static inline void __skb_queue_purge(struct sk_buff_head *list)
1845 {
1846         struct sk_buff *skb;
1847         while ((skb = __skb_dequeue(list)) != NULL)
1848                 kfree_skb(skb);
1849 }
1850 
1851 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768)
1852 #define NETDEV_FRAG_PAGE_MAX_SIZE  (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER)
1853 #define NETDEV_PAGECNT_MAX_BIAS    NETDEV_FRAG_PAGE_MAX_SIZE
1854 
1855 extern void *netdev_alloc_frag(unsigned int fragsz);
1856 
1857 extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
1858                                           unsigned int length,
1859                                           gfp_t gfp_mask);
1860 
1861 /**
1862  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
1863  *      @dev: network device to receive on
1864  *      @length: length to allocate
1865  *
1866  *      Allocate a new &sk_buff and assign it a usage count of one. The
1867  *      buffer has unspecified headroom built in. Users should allocate
1868  *      the headroom they think they need without accounting for the
1869  *      built in space. The built in space is used for optimisations.
1870  *
1871  *      %NULL is returned if there is no free memory. Although this function
1872  *      allocates memory it can be called from an interrupt.
1873  */
1874 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
1875                                                unsigned int length)
1876 {
1877         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
1878 }
1879 
1880 /* legacy helper around __netdev_alloc_skb() */
1881 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
1882                                               gfp_t gfp_mask)
1883 {
1884         return __netdev_alloc_skb(NULL, length, gfp_mask);
1885 }
1886 
1887 /* legacy helper around netdev_alloc_skb() */
1888 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1889 {
1890         return netdev_alloc_skb(NULL, length);
1891 }
1892 
1893 
1894 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
1895                 unsigned int length, gfp_t gfp)
1896 {
1897         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
1898 
1899         if (NET_IP_ALIGN && skb)
1900                 skb_reserve(skb, NET_IP_ALIGN);
1901         return skb;
1902 }
1903 
1904 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
1905                 unsigned int length)
1906 {
1907         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
1908 }
1909 
1910 /*
1911  *      __skb_alloc_page - allocate pages for ps-rx on a skb and preserve pfmemalloc data
1912  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1913  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1914  *      @order: size of the allocation
1915  *
1916  *      Allocate a new page.
1917  *
1918  *      %NULL is returned if there is no free memory.
1919 */
1920 static inline struct page *__skb_alloc_pages(gfp_t gfp_mask,
1921                                               struct sk_buff *skb,
1922                                               unsigned int order)
1923 {
1924         struct page *page;
1925 
1926         gfp_mask |= __GFP_COLD;
1927 
1928         if (!(gfp_mask & __GFP_NOMEMALLOC))
1929                 gfp_mask |= __GFP_MEMALLOC;
1930 
1931         page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
1932         if (skb && page && page->pfmemalloc)
1933                 skb->pfmemalloc = true;
1934 
1935         return page;
1936 }
1937 
1938 /**
1939  *      __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data
1940  *      @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
1941  *      @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used
1942  *
1943  *      Allocate a new page.
1944  *
1945  *      %NULL is returned if there is no free memory.
1946  */
1947 static inline struct page *__skb_alloc_page(gfp_t gfp_mask,
1948                                              struct sk_buff *skb)
1949 {
1950         return __skb_alloc_pages(gfp_mask, skb, 0);
1951 }
1952 
1953 /**
1954  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
1955  *      @page: The page that was allocated from skb_alloc_page
1956  *      @skb: The skb that may need pfmemalloc set
1957  */
1958 static inline void skb_propagate_pfmemalloc(struct page *page,
1959                                              struct sk_buff *skb)
1960 {
1961         if (page && page->pfmemalloc)
1962                 skb->pfmemalloc = true;
1963 }
1964 
1965 /**
1966  * skb_frag_page - retrieve the page refered to by a paged fragment
1967  * @frag: the paged fragment
1968  *
1969  * Returns the &struct page associated with @frag.
1970  */
1971 static inline struct page *skb_frag_page(const skb_frag_t *frag)
1972 {
1973         return frag->page.p;
1974 }
1975 
1976 /**
1977  * __skb_frag_ref - take an addition reference on a paged fragment.
1978  * @frag: the paged fragment
1979  *
1980  * Takes an additional reference on the paged fragment @frag.
1981  */
1982 static inline void __skb_frag_ref(skb_frag_t *frag)
1983 {
1984         get_page(skb_frag_page(frag));
1985 }
1986 
1987 /**
1988  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
1989  * @skb: the buffer
1990  * @f: the fragment offset.
1991  *
1992  * Takes an additional reference on the @f'th paged fragment of @skb.
1993  */
1994 static inline void skb_frag_ref(struct sk_buff *skb, int f)
1995 {
1996         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
1997 }
1998 
1999 /**
2000  * __skb_frag_unref - release a reference on a paged fragment.
2001  * @frag: the paged fragment
2002  *
2003  * Releases a reference on the paged fragment @frag.
2004  */
2005 static inline void __skb_frag_unref(skb_frag_t *frag)
2006 {
2007         put_page(skb_frag_page(frag));
2008 }
2009 
2010 /**
2011  * skb_frag_unref - release a reference on a paged fragment of an skb.
2012  * @skb: the buffer
2013  * @f: the fragment offset
2014  *
2015  * Releases a reference on the @f'th paged fragment of @skb.
2016  */
2017 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2018 {
2019         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2020 }
2021 
2022 /**
2023  * skb_frag_address - gets the address of the data contained in a paged fragment
2024  * @frag: the paged fragment buffer
2025  *
2026  * Returns the address of the data within @frag. The page must already
2027  * be mapped.
2028  */
2029 static inline void *skb_frag_address(const skb_frag_t *frag)
2030 {
2031         return page_address(skb_frag_page(frag)) + frag->page_offset;
2032 }
2033 
2034 /**
2035  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2036  * @frag: the paged fragment buffer
2037  *
2038  * Returns the address of the data within @frag. Checks that the page
2039  * is mapped and returns %NULL otherwise.
2040  */
2041 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2042 {
2043         void *ptr = page_address(skb_frag_page(frag));
2044         if (unlikely(!ptr))
2045                 return NULL;
2046 
2047         return ptr + frag->page_offset;
2048 }
2049 
2050 /**
2051  * __skb_frag_set_page - sets the page contained in a paged fragment
2052  * @frag: the paged fragment
2053  * @page: the page to set
2054  *
2055  * Sets the fragment @frag to contain @page.
2056  */
2057 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2058 {
2059         frag->page.p = page;
2060 }
2061 
2062 /**
2063  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2064  * @skb: the buffer
2065  * @f: the fragment offset
2066  * @page: the page to set
2067  *
2068  * Sets the @f'th fragment of @skb to contain @page.
2069  */
2070 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2071                                      struct page *page)
2072 {
2073         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2074 }
2075 
2076 /**
2077  * skb_frag_dma_map - maps a paged fragment via the DMA API
2078  * @dev: the device to map the fragment to
2079  * @frag: the paged fragment to map
2080  * @offset: the offset within the fragment (starting at the
2081  *          fragment's own offset)
2082  * @size: the number of bytes to map
2083  * @dir: the direction of the mapping (%PCI_DMA_*)
2084  *
2085  * Maps the page associated with @frag to @device.
2086  */
2087 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2088                                           const skb_frag_t *frag,
2089                                           size_t offset, size_t size,
2090                                           enum dma_data_direction dir)
2091 {
2092         return dma_map_page(dev, skb_frag_page(frag),
2093                             frag->page_offset + offset, size, dir);
2094 }
2095 
2096 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2097                                         gfp_t gfp_mask)
2098 {
2099         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2100 }
2101 
2102 /**
2103  *      skb_clone_writable - is the header of a clone writable
2104  *      @skb: buffer to check
2105  *      @len: length up to which to write
2106  *
2107  *      Returns true if modifying the header part of the cloned buffer
2108  *      does not requires the data to be copied.
2109  */
2110 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2111 {
2112         return !skb_header_cloned(skb) &&
2113                skb_headroom(skb) + len <= skb->hdr_len;
2114 }
2115 
2116 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2117                             int cloned)
2118 {
2119         int delta = 0;
2120 
2121         if (headroom > skb_headroom(skb))
2122                 delta = headroom - skb_headroom(skb);
2123 
2124         if (delta || cloned)
2125                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2126                                         GFP_ATOMIC);
2127         return 0;
2128 }
2129 
2130 /**
2131  *      skb_cow - copy header of skb when it is required
2132  *      @skb: buffer to cow
2133  *      @headroom: needed headroom
2134  *
2135  *      If the skb passed lacks sufficient headroom or its data part
2136  *      is shared, data is reallocated. If reallocation fails, an error
2137  *      is returned and original skb is not changed.
2138  *
2139  *      The result is skb with writable area skb->head...skb->tail
2140  *      and at least @headroom of space at head.
2141  */
2142 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2143 {
2144         return __skb_cow(skb, headroom, skb_cloned(skb));
2145 }
2146 
2147 /**
2148  *      skb_cow_head - skb_cow but only making the head writable
2149  *      @skb: buffer to cow
2150  *      @headroom: needed headroom
2151  *
2152  *      This function is identical to skb_cow except that we replace the
2153  *      skb_cloned check by skb_header_cloned.  It should be used when
2154  *      you only need to push on some header and do not need to modify
2155  *      the data.
2156  */
2157 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2158 {
2159         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2160 }
2161 
2162 /**
2163  *      skb_padto       - pad an skbuff up to a minimal size
2164  *      @skb: buffer to pad
2165  *      @len: minimal length
2166  *
2167  *      Pads up a buffer to ensure the trailing bytes exist and are
2168  *      blanked. If the buffer already contains sufficient data it
2169  *      is untouched. Otherwise it is extended. Returns zero on
2170  *      success. The skb is freed on error.
2171  */
2172  
2173 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2174 {
2175         unsigned int size = skb->len;
2176         if (likely(size >= len))
2177                 return 0;
2178         return skb_pad(skb, len - size);
2179 }
2180 
2181 static inline int skb_add_data(struct sk_buff *skb,
2182                                char __user *from, int copy)
2183 {
2184         const int off = skb->len;
2185 
2186         if (skb->ip_summed == CHECKSUM_NONE) {
2187                 int err = 0;
2188                 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
2189                                                             copy, 0, &err);
2190                 if (!err) {
2191                         skb->csum = csum_block_add(skb->csum, csum, off);
2192                         return 0;
2193                 }
2194         } else if (!copy_from_user(skb_put(skb, copy), from, copy))
2195                 return 0;
2196 
2197         __skb_trim(skb, off);
2198         return -EFAULT;
2199 }
2200 
2201 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2202                                     const struct page *page, int off)
2203 {
2204         if (i) {
2205                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2206 
2207                 return page == skb_frag_page(frag) &&
2208                        off == frag->page_offset + skb_frag_size(frag);
2209         }
2210         return false;
2211 }
2212 
2213 static inline int __skb_linearize(struct sk_buff *skb)
2214 {
2215         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2216 }
2217 
2218 /**
2219  *      skb_linearize - convert paged skb to linear one
2220  *      @skb: buffer to linarize
2221  *
2222  *      If there is no free memory -ENOMEM is returned, otherwise zero
2223  *      is returned and the old skb data released.
2224  */
2225 static inline int skb_linearize(struct sk_buff *skb)
2226 {
2227         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2228 }
2229 
2230 /**
2231  * skb_has_shared_frag - can any frag be overwritten
2232  * @skb: buffer to test
2233  *
2234  * Return true if the skb has at least one frag that might be modified
2235  * by an external entity (as in vmsplice()/sendfile())
2236  */
2237 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2238 {
2239         return skb_is_nonlinear(skb) &&
2240                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2241 }
2242 
2243 /**
2244  *      skb_linearize_cow - make sure skb is linear and writable
2245  *      @skb: buffer to process
2246  *
2247  *      If there is no free memory -ENOMEM is returned, otherwise zero
2248  *      is returned and the old skb data released.
2249  */
2250 static inline int skb_linearize_cow(struct sk_buff *skb)
2251 {
2252         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2253                __skb_linearize(skb) : 0;
2254 }
2255 
2256 /**
2257  *      skb_postpull_rcsum - update checksum for received skb after pull
2258  *      @skb: buffer to update
2259  *      @start: start of data before pull
2260  *      @len: length of data pulled
2261  *
2262  *      After doing a pull on a received packet, you need to call this to
2263  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2264  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2265  */
2266 
2267 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2268                                       const void *start, unsigned int len)
2269 {
2270         if (skb->ip_summed == CHECKSUM_COMPLETE)
2271                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2272 }
2273 
2274 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2275 
2276 /**
2277  *      pskb_trim_rcsum - trim received skb and update checksum
2278  *      @skb: buffer to trim
2279  *      @len: new length
2280  *
2281  *      This is exactly the same as pskb_trim except that it ensures the
2282  *      checksum of received packets are still valid after the operation.
2283  */
2284 
2285 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2286 {
2287         if (likely(len >= skb->len))
2288                 return 0;
2289         if (skb->ip_summed == CHECKSUM_COMPLETE)
2290                 skb->ip_summed = CHECKSUM_NONE;
2291         return __pskb_trim(skb, len);
2292 }
2293 
2294 #define skb_queue_walk(queue, skb) \
2295                 for (skb = (queue)->next;                                       \
2296                      skb != (struct sk_buff *)(queue);                          \
2297                      skb = skb->next)
2298 
2299 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2300                 for (skb = (queue)->next, tmp = skb->next;                      \
2301                      skb != (struct sk_buff *)(queue);                          \
2302                      skb = tmp, tmp = skb->next)
2303 
2304 #define skb_queue_walk_from(queue, skb)                                         \
2305                 for (; skb != (struct sk_buff *)(queue);                        \
2306                      skb = skb->next)
2307 
2308 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2309                 for (tmp = skb->next;                                           \
2310                      skb != (struct sk_buff *)(queue);                          \
2311                      skb = tmp, tmp = skb->next)
2312 
2313 #define skb_queue_reverse_walk(queue, skb) \
2314                 for (skb = (queue)->prev;                                       \
2315                      skb != (struct sk_buff *)(queue);                          \
2316                      skb = skb->prev)
2317 
2318 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2319                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2320                      skb != (struct sk_buff *)(queue);                          \
2321                      skb = tmp, tmp = skb->prev)
2322 
2323 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2324                 for (tmp = skb->prev;                                           \
2325                      skb != (struct sk_buff *)(queue);                          \
2326                      skb = tmp, tmp = skb->prev)
2327 
2328 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2329 {
2330         return skb_shinfo(skb)->frag_list != NULL;
2331 }
2332 
2333 static inline void skb_frag_list_init(struct sk_buff *skb)
2334 {
2335         skb_shinfo(skb)->frag_list = NULL;
2336 }
2337 
2338 static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
2339 {
2340         frag->next = skb_shinfo(skb)->frag_list;
2341         skb_shinfo(skb)->frag_list = frag;
2342 }
2343 
2344 #define skb_walk_frags(skb, iter)       \
2345         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2346 
2347 extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2348                                            int *peeked, int *off, int *err);
2349 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
2350                                          int noblock, int *err);
2351 extern unsigned int    datagram_poll(struct file *file, struct socket *sock,
2352                                      struct poll_table_struct *wait);
2353 extern int             skb_copy_datagram_iovec(const struct sk_buff *from,
2354                                                int offset, struct iovec *to,
2355                                                int size);
2356 extern int             skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
2357                                                         int hlen,
2358                                                         struct iovec *iov);
2359 extern int             skb_copy_datagram_from_iovec(struct sk_buff *skb,
2360                                                     int offset,
2361                                                     const struct iovec *from,
2362                                                     int from_offset,
2363                                                     int len);
2364 extern int             skb_copy_datagram_const_iovec(const struct sk_buff *from,
2365                                                      int offset,
2366                                                      const struct iovec *to,
2367                                                      int to_offset,
2368                                                      int size);
2369 extern void            skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2370 extern void            skb_free_datagram_locked(struct sock *sk,
2371                                                 struct sk_buff *skb);
2372 extern int             skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
2373                                          unsigned int flags);
2374 extern __wsum          skb_checksum(const struct sk_buff *skb, int offset,
2375                                     int len, __wsum csum);
2376 extern int             skb_copy_bits(const struct sk_buff *skb, int offset,
2377                                      void *to, int len);
2378 extern int             skb_store_bits(struct sk_buff *skb, int offset,
2379                                       const void *from, int len);
2380 extern __wsum          skb_copy_and_csum_bits(const struct sk_buff *skb,
2381                                               int offset, u8 *to, int len,
2382                                               __wsum csum);
2383 extern int             skb_splice_bits(struct sk_buff *skb,
2384                                                 unsigned int offset,
2385                                                 struct pipe_inode_info *pipe,
2386                                                 unsigned int len,
2387                                                 unsigned int flags);
2388 extern void            skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2389 extern void            skb_split(struct sk_buff *skb,
2390                                  struct sk_buff *skb1, const u32 len);
2391 extern int             skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
2392                                  int shiftlen);
2393 extern void            skb_scrub_packet(struct sk_buff *skb);
2394 
2395 extern struct sk_buff *skb_segment(struct sk_buff *skb,
2396                                    netdev_features_t features);
2397 
2398 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
2399                                        int len, void *buffer)
2400 {
2401         int hlen = skb_headlen(skb);
2402 
2403         if (hlen - offset >= len)
2404                 return skb->data + offset;
2405 
2406         if (skb_copy_bits(skb, offset, buffer, len) < 0)
2407                 return NULL;
2408 
2409         return buffer;
2410 }
2411 
2412 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2413                                              void *to,
2414                                              const unsigned int len)
2415 {
2416         memcpy(to, skb->data, len);
2417 }
2418 
2419 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2420                                                     const int offset, void *to,
2421                                                     const unsigned int len)
2422 {
2423         memcpy(to, skb->data + offset, len);
2424 }
2425 
2426 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2427                                            const void *from,
2428                                            const unsigned int len)
2429 {
2430         memcpy(skb->data, from, len);
2431 }
2432 
2433 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2434                                                   const int offset,
2435                                                   const void *from,
2436                                                   const unsigned int len)
2437 {
2438         memcpy(skb->data + offset, from, len);
2439 }
2440 
2441 extern void skb_init(void);
2442 
2443 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2444 {
2445         return skb->tstamp;
2446 }
2447 
2448 /**
2449  *      skb_get_timestamp - get timestamp from a skb
2450  *      @skb: skb to get stamp from
2451  *      @stamp: pointer to struct timeval to store stamp in
2452  *
2453  *      Timestamps are stored in the skb as offsets to a base timestamp.
2454  *      This function converts the offset back to a struct timeval and stores
2455  *      it in stamp.
2456  */
2457 static inline void skb_get_timestamp(const struct sk_buff *skb,
2458                                      struct timeval *stamp)
2459 {
2460         *stamp = ktime_to_timeval(skb->tstamp);
2461 }
2462 
2463 static inline void skb_get_timestampns(const struct sk_buff *skb,
2464                                        struct timespec *stamp)
2465 {
2466         *stamp = ktime_to_timespec(skb->tstamp);
2467 }
2468 
2469 static inline void __net_timestamp(struct sk_buff *skb)
2470 {
2471         skb->tstamp = ktime_get_real();
2472 }
2473 
2474 static inline ktime_t net_timedelta(ktime_t t)
2475 {
2476         return ktime_sub(ktime_get_real(), t);
2477 }
2478 
2479 static inline ktime_t net_invalid_timestamp(void)
2480 {
2481         return ktime_set(0, 0);
2482 }
2483 
2484 extern void skb_timestamping_init(void);
2485 
2486 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2487 
2488 extern void skb_clone_tx_timestamp(struct sk_buff *skb);
2489 extern bool skb_defer_rx_timestamp(struct sk_buff *skb);
2490 
2491 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2492 
2493 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2494 {
2495 }
2496 
2497 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2498 {
2499         return false;
2500 }
2501 
2502 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2503 
2504 /**
2505  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2506  *
2507  * PHY drivers may accept clones of transmitted packets for
2508  * timestamping via their phy_driver.txtstamp method. These drivers
2509  * must call this function to return the skb back to the stack, with
2510  * or without a timestamp.
2511  *
2512  * @skb: clone of the the original outgoing packet
2513  * @hwtstamps: hardware time stamps, may be NULL if not available
2514  *
2515  */
2516 void skb_complete_tx_timestamp(struct sk_buff *skb,
2517                                struct skb_shared_hwtstamps *hwtstamps);
2518 
2519 /**
2520  * skb_tstamp_tx - queue clone of skb with send time stamps
2521  * @orig_skb:   the original outgoing packet
2522  * @hwtstamps:  hardware time stamps, may be NULL if not available
2523  *
2524  * If the skb has a socket associated, then this function clones the
2525  * skb (thus sharing the actual data and optional structures), stores
2526  * the optional hardware time stamping information (if non NULL) or
2527  * generates a software time stamp (otherwise), then queues the clone
2528  * to the error queue of the socket.  Errors are silently ignored.
2529  */
2530 extern void skb_tstamp_tx(struct sk_buff *orig_skb,
2531                         struct skb_shared_hwtstamps *hwtstamps);
2532 
2533 static inline void sw_tx_timestamp(struct sk_buff *skb)
2534 {
2535         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
2536             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
2537                 skb_tstamp_tx(skb, NULL);
2538 }
2539 
2540 /**
2541  * skb_tx_timestamp() - Driver hook for transmit timestamping
2542  *
2543  * Ethernet MAC Drivers should call this function in their hard_xmit()
2544  * function immediately before giving the sk_buff to the MAC hardware.
2545  *
2546  * @skb: A socket buffer.
2547  */
2548 static inline void skb_tx_timestamp(struct sk_buff *skb)
2549 {
2550         skb_clone_tx_timestamp(skb);
2551         sw_tx_timestamp(skb);
2552 }
2553 
2554 /**
2555  * skb_complete_wifi_ack - deliver skb with wifi status
2556  *
2557  * @skb: the original outgoing packet
2558  * @acked: ack status
2559  *
2560  */
2561 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
2562 
2563 extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
2564 extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
2565 
2566 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
2567 {
2568         return skb->ip_summed & CHECKSUM_UNNECESSARY;
2569 }
2570 
2571 /**
2572  *      skb_checksum_complete - Calculate checksum of an entire packet
2573  *      @skb: packet to process
2574  *
2575  *      This function calculates the checksum over the entire packet plus
2576  *      the value of skb->csum.  The latter can be used to supply the
2577  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
2578  *      checksum.
2579  *
2580  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
2581  *      this function can be used to verify that checksum on received
2582  *      packets.  In that case the function should return zero if the
2583  *      checksum is correct.  In particular, this function will return zero
2584  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
2585  *      hardware has already verified the correctness of the checksum.
2586  */
2587 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
2588 {
2589         return skb_csum_unnecessary(skb) ?
2590                0 : __skb_checksum_complete(skb);
2591 }
2592 
2593 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2594 extern void nf_conntrack_destroy(struct nf_conntrack *nfct);
2595 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
2596 {
2597         if (nfct && atomic_dec_and_test(&nfct->use))
2598                 nf_conntrack_destroy(nfct);
2599 }
2600 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
2601 {
2602         if (nfct)
2603                 atomic_inc(&nfct->use);
2604 }
2605 #endif
2606 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2607 static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
2608 {
2609         if (skb)
2610                 atomic_inc(&skb->users);
2611 }
2612 static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
2613 {
2614         if (skb)
2615                 kfree_skb(skb);
2616 }
2617 #endif
2618 #ifdef CONFIG_BRIDGE_NETFILTER
2619 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
2620 {
2621         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
2622                 kfree(nf_bridge);
2623 }
2624 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
2625 {
2626         if (nf_bridge)
2627                 atomic_inc(&nf_bridge->use);
2628 }
2629 #endif /* CONFIG_BRIDGE_NETFILTER */
2630 static inline void nf_reset(struct sk_buff *skb)
2631 {
2632 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2633         nf_conntrack_put(skb->nfct);
2634         skb->nfct = NULL;
2635 #endif
2636 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2637         nf_conntrack_put_reasm(skb->nfct_reasm);
2638         skb->nfct_reasm = NULL;
2639 #endif
2640 #ifdef CONFIG_BRIDGE_NETFILTER
2641         nf_bridge_put(skb->nf_bridge);
2642         skb->nf_bridge = NULL;
2643 #endif
2644 }
2645 
2646 static inline void nf_reset_trace(struct sk_buff *skb)
2647 {
2648 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
2649         skb->nf_trace = 0;
2650 #endif
2651 }
2652 
2653 /* Note: This doesn't put any conntrack and bridge info in dst. */
2654 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2655 {
2656 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2657         dst->nfct = src->nfct;
2658         nf_conntrack_get(src->nfct);
2659         dst->nfctinfo = src->nfctinfo;
2660 #endif
2661 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2662         dst->nfct_reasm = src->nfct_reasm;
2663         nf_conntrack_get_reasm(src->nfct_reasm);
2664 #endif
2665 #ifdef CONFIG_BRIDGE_NETFILTER
2666         dst->nf_bridge  = src->nf_bridge;
2667         nf_bridge_get(src->nf_bridge);
2668 #endif
2669 }
2670 
2671 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
2672 {
2673 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
2674         nf_conntrack_put(dst->nfct);
2675 #endif
2676 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
2677         nf_conntrack_put_reasm(dst->nfct_reasm);
2678 #endif
2679 #ifdef CONFIG_BRIDGE_NETFILTER
2680         nf_bridge_put(dst->nf_bridge);
2681 #endif
2682         __nf_copy(dst, src);
2683 }
2684 
2685 #ifdef CONFIG_NETWORK_SECMARK
2686 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2687 {
2688         to->secmark = from->secmark;
2689 }
2690 
2691 static inline void skb_init_secmark(struct sk_buff *skb)
2692 {
2693         skb->secmark = 0;
2694 }
2695 #else
2696 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
2697 { }
2698 
2699 static inline void skb_init_secmark(struct sk_buff *skb)
2700 { }
2701 #endif
2702 
2703 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
2704 {
2705         skb->queue_mapping = queue_mapping;
2706 }
2707 
2708 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2709 {
2710         return skb->queue_mapping;
2711 }
2712 
2713 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
2714 {
2715         to->queue_mapping = from->queue_mapping;
2716 }
2717 
2718 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
2719 {
2720         skb->queue_mapping = rx_queue + 1;
2721 }
2722 
2723 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
2724 {
2725         return skb->queue_mapping - 1;
2726 }
2727 
2728 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
2729 {
2730         return skb->queue_mapping != 0;
2731 }
2732 
2733 extern u16 __skb_tx_hash(const struct net_device *dev,
2734                          const struct sk_buff *skb,
2735                          unsigned int num_tx_queues);
2736 
2737 #ifdef CONFIG_XFRM
2738 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2739 {
2740         return skb->sp;
2741 }
2742 #else
2743 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2744 {
2745         return NULL;
2746 }
2747 #endif
2748 
2749 /* Keeps track of mac header offset relative to skb->head.
2750  * It is useful for TSO of Tunneling protocol. e.g. GRE.
2751  * For non-tunnel skb it points to skb_mac_header() and for
2752  * tunnel skb it points to outer mac header. */
2753 struct skb_gso_cb {
2754         int mac_offset;
2755 };
2756 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
2757 
2758 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
2759 {
2760         return (skb_mac_header(inner_skb) - inner_skb->head) -
2761                 SKB_GSO_CB(inner_skb)->mac_offset;
2762 }
2763 
2764 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
2765 {
2766         int new_headroom, headroom;
2767         int ret;
2768 
2769         headroom = skb_headroom(skb);
2770         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
2771         if (ret)
2772                 return ret;
2773 
2774         new_headroom = skb_headroom(skb);
2775         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
2776         return 0;
2777 }
2778 
2779 static inline bool skb_is_gso(const struct sk_buff *skb)
2780 {
2781         return skb_shinfo(skb)->gso_size;
2782 }
2783 
2784 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
2785 {
2786         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
2787 }
2788 
2789 extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
2790 
2791 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
2792 {
2793         /* LRO sets gso_size but not gso_type, whereas if GSO is really
2794          * wanted then gso_type will be set. */
2795         const struct skb_shared_info *shinfo = skb_shinfo(skb);
2796 
2797         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
2798             unlikely(shinfo->gso_type == 0)) {
2799                 __skb_warn_lro_forwarding(skb);
2800                 return true;
2801         }
2802         return false;
2803 }
2804 
2805 static inline void skb_forward_csum(struct sk_buff *skb)
2806 {
2807         /* Unfortunately we don't support this one.  Any brave souls? */
2808         if (skb->ip_summed == CHECKSUM_COMPLETE)
2809                 skb->ip_summed = CHECKSUM_NONE;
2810 }
2811 
2812 /**
2813  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
2814  * @skb: skb to check
2815  *
2816  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
2817  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
2818  * use this helper, to document places where we make this assertion.
2819  */
2820 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
2821 {
2822 #ifdef DEBUG
2823         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
2824 #endif
2825 }
2826 
2827 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
2828 
2829 u32 __skb_get_poff(const struct sk_buff *skb);
2830 
2831 /**
2832  * skb_head_is_locked - Determine if the skb->head is locked down
2833  * @skb: skb to check
2834  *
2835  * The head on skbs build around a head frag can be removed if they are
2836  * not cloned.  This function returns true if the skb head is locked down
2837  * due to either being allocated via kmalloc, or by being a clone with
2838  * multiple references to the head.
2839  */
2840 static inline bool skb_head_is_locked(const struct sk_buff *skb)
2841 {
2842         return !skb->head_frag || skb_cloned(skb);
2843 }
2844 #endif  /* __KERNEL__ */
2845 #endif  /* _LINUX_SKBUFF_H */
2846 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp