async: make sure independent async domains can't accidentally entangle
[linux-2.6/mini2440.git] / include / linux / skbuff.h
blob5fd389162f014ccb053d8563de6ce2a16cedd90f
1 /*
2 * Definitions for the 'struct sk_buff' memory handlers.
4 * Authors:
5 * Alan Cox, <gw4pts@gw4pts.ampr.org>
6 * Florian La Roche, <rzsfl@rz.uni-sb.de>
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.
14 #ifndef _LINUX_SKBUFF_H
15 #define _LINUX_SKBUFF_H
17 #include <linux/kernel.h>
18 #include <linux/compiler.h>
19 #include <linux/time.h>
20 #include <linux/cache.h>
22 #include <asm/atomic.h>
23 #include <asm/types.h>
24 #include <linux/spinlock.h>
25 #include <linux/net.h>
26 #include <linux/textsearch.h>
27 #include <net/checksum.h>
28 #include <linux/rcupdate.h>
29 #include <linux/dmaengine.h>
30 #include <linux/hrtimer.h>
32 /* Don't change this without changing skb_csum_unnecessary! */
33 #define CHECKSUM_NONE 0
34 #define CHECKSUM_UNNECESSARY 1
35 #define CHECKSUM_COMPLETE 2
36 #define CHECKSUM_PARTIAL 3
38 #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
39 ~(SMP_CACHE_BYTES - 1))
40 #define SKB_WITH_OVERHEAD(X) \
41 ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
42 #define SKB_MAX_ORDER(X, ORDER) \
43 SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
44 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
45 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
47 /* A. Checksumming of received packets by device.
49 * NONE: device failed to checksum this packet.
50 * skb->csum is undefined.
52 * UNNECESSARY: device parsed packet and wouldbe verified checksum.
53 * skb->csum is undefined.
54 * It is bad option, but, unfortunately, many of vendors do this.
55 * Apparently with secret goal to sell you new device, when you
56 * will add new protocol to your host. F.e. IPv6. 8)
58 * COMPLETE: the most generic way. Device supplied checksum of _all_
59 * the packet as seen by netif_rx in skb->csum.
60 * NOTE: Even if device supports only some protocols, but
61 * is able to produce some skb->csum, it MUST use COMPLETE,
62 * not UNNECESSARY.
64 * PARTIAL: identical to the case for output below. This may occur
65 * on a packet received directly from another Linux OS, e.g.,
66 * a virtualised Linux kernel on the same host. The packet can
67 * be treated in the same way as UNNECESSARY except that on
68 * output (i.e., forwarding) the checksum must be filled in
69 * by the OS or the hardware.
71 * B. Checksumming on output.
73 * NONE: skb is checksummed by protocol or csum is not required.
75 * PARTIAL: device is required to csum packet as seen by hard_start_xmit
76 * from skb->csum_start to the end and to record the checksum
77 * at skb->csum_start + skb->csum_offset.
79 * Device must show its capabilities in dev->features, set
80 * at device setup time.
81 * NETIF_F_HW_CSUM - it is clever device, it is able to checksum
82 * everything.
83 * NETIF_F_NO_CSUM - loopback or reliable single hop media.
84 * NETIF_F_IP_CSUM - device is dumb. It is able to csum only
85 * TCP/UDP over IPv4. Sigh. Vendors like this
86 * way by an unknown reason. Though, see comment above
87 * about CHECKSUM_UNNECESSARY. 8)
88 * NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
90 * Any questions? No questions, good. --ANK
93 struct net_device;
94 struct scatterlist;
95 struct pipe_inode_info;
97 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
98 struct nf_conntrack {
99 atomic_t use;
101 #endif
103 #ifdef CONFIG_BRIDGE_NETFILTER
104 struct nf_bridge_info {
105 atomic_t use;
106 struct net_device *physindev;
107 struct net_device *physoutdev;
108 unsigned int mask;
109 unsigned long data[32 / sizeof(unsigned long)];
111 #endif
113 struct sk_buff_head {
114 /* These two members must be first. */
115 struct sk_buff *next;
116 struct sk_buff *prev;
118 __u32 qlen;
119 spinlock_t lock;
122 struct sk_buff;
124 /* To allow 64K frame to be packed as single skb without frag_list */
125 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
127 typedef struct skb_frag_struct skb_frag_t;
129 struct skb_frag_struct {
130 struct page *page;
131 __u32 page_offset;
132 __u32 size;
135 #define HAVE_HW_TIME_STAMP
138 * struct skb_shared_hwtstamps - hardware time stamps
139 * @hwtstamp: hardware time stamp transformed into duration
140 * since arbitrary point in time
141 * @syststamp: hwtstamp transformed to system time base
143 * Software time stamps generated by ktime_get_real() are stored in
144 * skb->tstamp. The relation between the different kinds of time
145 * stamps is as follows:
147 * syststamp and tstamp can be compared against each other in
148 * arbitrary combinations. The accuracy of a
149 * syststamp/tstamp/"syststamp from other device" comparison is
150 * limited by the accuracy of the transformation into system time
151 * base. This depends on the device driver and its underlying
152 * hardware.
154 * hwtstamps can only be compared against other hwtstamps from
155 * the same device.
157 * This structure is attached to packets as part of the
158 * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
160 struct skb_shared_hwtstamps {
161 ktime_t hwtstamp;
162 ktime_t syststamp;
166 * struct skb_shared_tx - instructions for time stamping of outgoing packets
167 * @hardware: generate hardware time stamp
168 * @software: generate software time stamp
169 * @in_progress: device driver is going to provide
170 * hardware time stamp
171 * @flags: all shared_tx flags
173 * These flags are attached to packets as part of the
174 * &skb_shared_info. Use skb_tx() to get a pointer.
176 union skb_shared_tx {
177 struct {
178 __u8 hardware:1,
179 software:1,
180 in_progress:1;
182 __u8 flags;
185 /* This data is invariant across clones and lives at
186 * the end of the header data, ie. at skb->end.
188 struct skb_shared_info {
189 atomic_t dataref;
190 unsigned short nr_frags;
191 unsigned short gso_size;
192 /* Warning: this field is not always filled in (UFO)! */
193 unsigned short gso_segs;
194 unsigned short gso_type;
195 __be32 ip6_frag_id;
196 union skb_shared_tx tx_flags;
197 #ifdef CONFIG_HAS_DMA
198 unsigned int num_dma_maps;
199 #endif
200 struct sk_buff *frag_list;
201 struct skb_shared_hwtstamps hwtstamps;
202 skb_frag_t frags[MAX_SKB_FRAGS];
203 #ifdef CONFIG_HAS_DMA
204 dma_addr_t dma_maps[MAX_SKB_FRAGS + 1];
205 #endif
208 /* We divide dataref into two halves. The higher 16 bits hold references
209 * to the payload part of skb->data. The lower 16 bits hold references to
210 * the entire skb->data. A clone of a headerless skb holds the length of
211 * the header in skb->hdr_len.
213 * All users must obey the rule that the skb->data reference count must be
214 * greater than or equal to the payload reference count.
216 * Holding a reference to the payload part means that the user does not
217 * care about modifications to the header part of skb->data.
219 #define SKB_DATAREF_SHIFT 16
220 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
223 enum {
224 SKB_FCLONE_UNAVAILABLE,
225 SKB_FCLONE_ORIG,
226 SKB_FCLONE_CLONE,
229 enum {
230 SKB_GSO_TCPV4 = 1 << 0,
231 SKB_GSO_UDP = 1 << 1,
233 /* This indicates the skb is from an untrusted source. */
234 SKB_GSO_DODGY = 1 << 2,
236 /* This indicates the tcp segment has CWR set. */
237 SKB_GSO_TCP_ECN = 1 << 3,
239 SKB_GSO_TCPV6 = 1 << 4,
241 SKB_GSO_FCOE = 1 << 5,
244 #if BITS_PER_LONG > 32
245 #define NET_SKBUFF_DATA_USES_OFFSET 1
246 #endif
248 #ifdef NET_SKBUFF_DATA_USES_OFFSET
249 typedef unsigned int sk_buff_data_t;
250 #else
251 typedef unsigned char *sk_buff_data_t;
252 #endif
254 /**
255 * struct sk_buff - socket buffer
256 * @next: Next buffer in list
257 * @prev: Previous buffer in list
258 * @sk: Socket we are owned by
259 * @tstamp: Time we arrived
260 * @dev: Device we arrived on/are leaving by
261 * @transport_header: Transport layer header
262 * @network_header: Network layer header
263 * @mac_header: Link layer header
264 * @dst: destination entry
265 * @sp: the security path, used for xfrm
266 * @cb: Control buffer. Free for use by every layer. Put private vars here
267 * @len: Length of actual data
268 * @data_len: Data length
269 * @mac_len: Length of link layer header
270 * @hdr_len: writable header length of cloned skb
271 * @csum: Checksum (must include start/offset pair)
272 * @csum_start: Offset from skb->head where checksumming should start
273 * @csum_offset: Offset from csum_start where checksum should be stored
274 * @local_df: allow local fragmentation
275 * @cloned: Head may be cloned (check refcnt to be sure)
276 * @nohdr: Payload reference only, must not modify header
277 * @pkt_type: Packet class
278 * @fclone: skbuff clone status
279 * @ip_summed: Driver fed us an IP checksum
280 * @priority: Packet queueing priority
281 * @users: User count - see {datagram,tcp}.c
282 * @protocol: Packet protocol from driver
283 * @truesize: Buffer size
284 * @head: Head of buffer
285 * @data: Data head pointer
286 * @tail: Tail pointer
287 * @end: End pointer
288 * @destructor: Destruct function
289 * @mark: Generic packet mark
290 * @nfct: Associated connection, if any
291 * @ipvs_property: skbuff is owned by ipvs
292 * @peeked: this packet has been seen already, so stats have been
293 * done for it, don't do them again
294 * @nf_trace: netfilter packet trace flag
295 * @nfctinfo: Relationship of this skb to the connection
296 * @nfct_reasm: netfilter conntrack re-assembly pointer
297 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
298 * @iif: ifindex of device we arrived on
299 * @queue_mapping: Queue mapping for multiqueue devices
300 * @tc_index: Traffic control index
301 * @tc_verd: traffic control verdict
302 * @ndisc_nodetype: router type (from link layer)
303 * @do_not_encrypt: set to prevent encryption of this frame
304 * @requeue: set to indicate that the wireless core should attempt
305 * a software retry on this frame if we failed to
306 * receive an ACK for it
307 * @dma_cookie: a cookie to one of several possible DMA operations
308 * done by skb DMA functions
309 * @secmark: security marking
310 * @vlan_tci: vlan tag control information
313 struct sk_buff {
314 /* These two members must be first. */
315 struct sk_buff *next;
316 struct sk_buff *prev;
318 struct sock *sk;
319 ktime_t tstamp;
320 struct net_device *dev;
322 union {
323 struct dst_entry *dst;
324 struct rtable *rtable;
326 #ifdef CONFIG_XFRM
327 struct sec_path *sp;
328 #endif
330 * This is the control buffer. It is free to use for every
331 * layer. Please put your private variables there. If you
332 * want to keep them across layers you have to do a skb_clone()
333 * first. This is owned by whoever has the skb queued ATM.
335 char cb[48];
337 unsigned int len,
338 data_len;
339 __u16 mac_len,
340 hdr_len;
341 union {
342 __wsum csum;
343 struct {
344 __u16 csum_start;
345 __u16 csum_offset;
348 __u32 priority;
349 __u8 local_df:1,
350 cloned:1,
351 ip_summed:2,
352 nohdr:1,
353 nfctinfo:3;
354 __u8 pkt_type:3,
355 fclone:2,
356 ipvs_property:1,
357 peeked:1,
358 nf_trace:1;
359 __be16 protocol;
361 void (*destructor)(struct sk_buff *skb);
362 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
363 struct nf_conntrack *nfct;
364 struct sk_buff *nfct_reasm;
365 #endif
366 #ifdef CONFIG_BRIDGE_NETFILTER
367 struct nf_bridge_info *nf_bridge;
368 #endif
370 int iif;
371 __u16 queue_mapping;
372 #ifdef CONFIG_NET_SCHED
373 __u16 tc_index; /* traffic control index */
374 #ifdef CONFIG_NET_CLS_ACT
375 __u16 tc_verd; /* traffic control verdict */
376 #endif
377 #endif
378 #ifdef CONFIG_IPV6_NDISC_NODETYPE
379 __u8 ndisc_nodetype:2;
380 #endif
381 #if defined(CONFIG_MAC80211) || defined(CONFIG_MAC80211_MODULE)
382 __u8 do_not_encrypt:1;
383 __u8 requeue:1;
384 #endif
385 /* 0/13/14 bit hole */
387 #ifdef CONFIG_NET_DMA
388 dma_cookie_t dma_cookie;
389 #endif
390 #ifdef CONFIG_NETWORK_SECMARK
391 __u32 secmark;
392 #endif
394 __u32 mark;
396 __u16 vlan_tci;
398 sk_buff_data_t transport_header;
399 sk_buff_data_t network_header;
400 sk_buff_data_t mac_header;
401 /* These elements must be at the end, see alloc_skb() for details. */
402 sk_buff_data_t tail;
403 sk_buff_data_t end;
404 unsigned char *head,
405 *data;
406 unsigned int truesize;
407 atomic_t users;
410 #ifdef __KERNEL__
412 * Handling routines are only of interest to the kernel
414 #include <linux/slab.h>
416 #include <asm/system.h>
418 #ifdef CONFIG_HAS_DMA
419 #include <linux/dma-mapping.h>
420 extern int skb_dma_map(struct device *dev, struct sk_buff *skb,
421 enum dma_data_direction dir);
422 extern void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
423 enum dma_data_direction dir);
424 #endif
426 extern void kfree_skb(struct sk_buff *skb);
427 extern void consume_skb(struct sk_buff *skb);
428 extern void __kfree_skb(struct sk_buff *skb);
429 extern struct sk_buff *__alloc_skb(unsigned int size,
430 gfp_t priority, int fclone, int node);
431 static inline struct sk_buff *alloc_skb(unsigned int size,
432 gfp_t priority)
434 return __alloc_skb(size, priority, 0, -1);
437 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
438 gfp_t priority)
440 return __alloc_skb(size, priority, 1, -1);
443 extern int skb_recycle_check(struct sk_buff *skb, int skb_size);
445 extern struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
446 extern struct sk_buff *skb_clone(struct sk_buff *skb,
447 gfp_t priority);
448 extern struct sk_buff *skb_copy(const struct sk_buff *skb,
449 gfp_t priority);
450 extern struct sk_buff *pskb_copy(struct sk_buff *skb,
451 gfp_t gfp_mask);
452 extern int pskb_expand_head(struct sk_buff *skb,
453 int nhead, int ntail,
454 gfp_t gfp_mask);
455 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
456 unsigned int headroom);
457 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
458 int newheadroom, int newtailroom,
459 gfp_t priority);
460 extern int skb_to_sgvec(struct sk_buff *skb,
461 struct scatterlist *sg, int offset,
462 int len);
463 extern int skb_cow_data(struct sk_buff *skb, int tailbits,
464 struct sk_buff **trailer);
465 extern int skb_pad(struct sk_buff *skb, int pad);
466 #define dev_kfree_skb(a) consume_skb(a)
467 #define dev_consume_skb(a) kfree_skb_clean(a)
468 extern void skb_over_panic(struct sk_buff *skb, int len,
469 void *here);
470 extern void skb_under_panic(struct sk_buff *skb, int len,
471 void *here);
473 extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
474 int getfrag(void *from, char *to, int offset,
475 int len,int odd, struct sk_buff *skb),
476 void *from, int length);
478 struct skb_seq_state
480 __u32 lower_offset;
481 __u32 upper_offset;
482 __u32 frag_idx;
483 __u32 stepped_offset;
484 struct sk_buff *root_skb;
485 struct sk_buff *cur_skb;
486 __u8 *frag_data;
489 extern void skb_prepare_seq_read(struct sk_buff *skb,
490 unsigned int from, unsigned int to,
491 struct skb_seq_state *st);
492 extern unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
493 struct skb_seq_state *st);
494 extern void skb_abort_seq_read(struct skb_seq_state *st);
496 extern unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
497 unsigned int to, struct ts_config *config,
498 struct ts_state *state);
500 #ifdef NET_SKBUFF_DATA_USES_OFFSET
501 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
503 return skb->head + skb->end;
505 #else
506 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
508 return skb->end;
510 #endif
512 /* Internal */
513 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
515 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
517 return &skb_shinfo(skb)->hwtstamps;
520 static inline union skb_shared_tx *skb_tx(struct sk_buff *skb)
522 return &skb_shinfo(skb)->tx_flags;
526 * skb_queue_empty - check if a queue is empty
527 * @list: queue head
529 * Returns true if the queue is empty, false otherwise.
531 static inline int skb_queue_empty(const struct sk_buff_head *list)
533 return list->next == (struct sk_buff *)list;
537 * skb_queue_is_last - check if skb is the last entry in the queue
538 * @list: queue head
539 * @skb: buffer
541 * Returns true if @skb is the last buffer on the list.
543 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
544 const struct sk_buff *skb)
546 return (skb->next == (struct sk_buff *) list);
550 * skb_queue_is_first - check if skb is the first entry in the queue
551 * @list: queue head
552 * @skb: buffer
554 * Returns true if @skb is the first buffer on the list.
556 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
557 const struct sk_buff *skb)
559 return (skb->prev == (struct sk_buff *) list);
563 * skb_queue_next - return the next packet in the queue
564 * @list: queue head
565 * @skb: current buffer
567 * Return the next packet in @list after @skb. It is only valid to
568 * call this if skb_queue_is_last() evaluates to false.
570 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
571 const struct sk_buff *skb)
573 /* This BUG_ON may seem severe, but if we just return then we
574 * are going to dereference garbage.
576 BUG_ON(skb_queue_is_last(list, skb));
577 return skb->next;
581 * skb_queue_prev - return the prev packet in the queue
582 * @list: queue head
583 * @skb: current buffer
585 * Return the prev packet in @list before @skb. It is only valid to
586 * call this if skb_queue_is_first() evaluates to false.
588 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
589 const struct sk_buff *skb)
591 /* This BUG_ON may seem severe, but if we just return then we
592 * are going to dereference garbage.
594 BUG_ON(skb_queue_is_first(list, skb));
595 return skb->prev;
599 * skb_get - reference buffer
600 * @skb: buffer to reference
602 * Makes another reference to a socket buffer and returns a pointer
603 * to the buffer.
605 static inline struct sk_buff *skb_get(struct sk_buff *skb)
607 atomic_inc(&skb->users);
608 return skb;
612 * If users == 1, we are the only owner and are can avoid redundant
613 * atomic change.
617 * skb_cloned - is the buffer a clone
618 * @skb: buffer to check
620 * Returns true if the buffer was generated with skb_clone() and is
621 * one of multiple shared copies of the buffer. Cloned buffers are
622 * shared data so must not be written to under normal circumstances.
624 static inline int skb_cloned(const struct sk_buff *skb)
626 return skb->cloned &&
627 (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
631 * skb_header_cloned - is the header a clone
632 * @skb: buffer to check
634 * Returns true if modifying the header part of the buffer requires
635 * the data to be copied.
637 static inline int skb_header_cloned(const struct sk_buff *skb)
639 int dataref;
641 if (!skb->cloned)
642 return 0;
644 dataref = atomic_read(&skb_shinfo(skb)->dataref);
645 dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
646 return dataref != 1;
650 * skb_header_release - release reference to header
651 * @skb: buffer to operate on
653 * Drop a reference to the header part of the buffer. This is done
654 * by acquiring a payload reference. You must not read from the header
655 * part of skb->data after this.
657 static inline void skb_header_release(struct sk_buff *skb)
659 BUG_ON(skb->nohdr);
660 skb->nohdr = 1;
661 atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
665 * skb_shared - is the buffer shared
666 * @skb: buffer to check
668 * Returns true if more than one person has a reference to this
669 * buffer.
671 static inline int skb_shared(const struct sk_buff *skb)
673 return atomic_read(&skb->users) != 1;
677 * skb_share_check - check if buffer is shared and if so clone it
678 * @skb: buffer to check
679 * @pri: priority for memory allocation
681 * If the buffer is shared the buffer is cloned and the old copy
682 * drops a reference. A new clone with a single reference is returned.
683 * If the buffer is not shared the original buffer is returned. When
684 * being called from interrupt status or with spinlocks held pri must
685 * be GFP_ATOMIC.
687 * NULL is returned on a memory allocation failure.
689 static inline struct sk_buff *skb_share_check(struct sk_buff *skb,
690 gfp_t pri)
692 might_sleep_if(pri & __GFP_WAIT);
693 if (skb_shared(skb)) {
694 struct sk_buff *nskb = skb_clone(skb, pri);
695 kfree_skb(skb);
696 skb = nskb;
698 return skb;
702 * Copy shared buffers into a new sk_buff. We effectively do COW on
703 * packets to handle cases where we have a local reader and forward
704 * and a couple of other messy ones. The normal one is tcpdumping
705 * a packet thats being forwarded.
709 * skb_unshare - make a copy of a shared buffer
710 * @skb: buffer to check
711 * @pri: priority for memory allocation
713 * If the socket buffer is a clone then this function creates a new
714 * copy of the data, drops a reference count on the old copy and returns
715 * the new copy with the reference count at 1. If the buffer is not a clone
716 * the original buffer is returned. When called with a spinlock held or
717 * from interrupt state @pri must be %GFP_ATOMIC
719 * %NULL is returned on a memory allocation failure.
721 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
722 gfp_t pri)
724 might_sleep_if(pri & __GFP_WAIT);
725 if (skb_cloned(skb)) {
726 struct sk_buff *nskb = skb_copy(skb, pri);
727 kfree_skb(skb); /* Free our shared copy */
728 skb = nskb;
730 return skb;
734 * skb_peek
735 * @list_: list to peek at
737 * Peek an &sk_buff. Unlike most other operations you _MUST_
738 * be careful with this one. A peek leaves the buffer on the
739 * list and someone else may run off with it. You must hold
740 * the appropriate locks or have a private queue to do this.
742 * Returns %NULL for an empty list or a pointer to the head element.
743 * The reference count is not incremented and the reference is therefore
744 * volatile. Use with caution.
746 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
748 struct sk_buff *list = ((struct sk_buff *)list_)->next;
749 if (list == (struct sk_buff *)list_)
750 list = NULL;
751 return list;
755 * skb_peek_tail
756 * @list_: list to peek at
758 * Peek an &sk_buff. Unlike most other operations you _MUST_
759 * be careful with this one. A peek leaves the buffer on the
760 * list and someone else may run off with it. You must hold
761 * the appropriate locks or have a private queue to do this.
763 * Returns %NULL for an empty list or a pointer to the tail element.
764 * The reference count is not incremented and the reference is therefore
765 * volatile. Use with caution.
767 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
769 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
770 if (list == (struct sk_buff *)list_)
771 list = NULL;
772 return list;
776 * skb_queue_len - get queue length
777 * @list_: list to measure
779 * Return the length of an &sk_buff queue.
781 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
783 return list_->qlen;
787 * __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
788 * @list: queue to initialize
790 * This initializes only the list and queue length aspects of
791 * an sk_buff_head object. This allows to initialize the list
792 * aspects of an sk_buff_head without reinitializing things like
793 * the spinlock. It can also be used for on-stack sk_buff_head
794 * objects where the spinlock is known to not be used.
796 static inline void __skb_queue_head_init(struct sk_buff_head *list)
798 list->prev = list->next = (struct sk_buff *)list;
799 list->qlen = 0;
803 * This function creates a split out lock class for each invocation;
804 * this is needed for now since a whole lot of users of the skb-queue
805 * infrastructure in drivers have different locking usage (in hardirq)
806 * than the networking core (in softirq only). In the long run either the
807 * network layer or drivers should need annotation to consolidate the
808 * main types of usage into 3 classes.
810 static inline void skb_queue_head_init(struct sk_buff_head *list)
812 spin_lock_init(&list->lock);
813 __skb_queue_head_init(list);
816 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
817 struct lock_class_key *class)
819 skb_queue_head_init(list);
820 lockdep_set_class(&list->lock, class);
824 * Insert an sk_buff on a list.
826 * The "__skb_xxxx()" functions are the non-atomic ones that
827 * can only be called with interrupts disabled.
829 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
830 static inline void __skb_insert(struct sk_buff *newsk,
831 struct sk_buff *prev, struct sk_buff *next,
832 struct sk_buff_head *list)
834 newsk->next = next;
835 newsk->prev = prev;
836 next->prev = prev->next = newsk;
837 list->qlen++;
840 static inline void __skb_queue_splice(const struct sk_buff_head *list,
841 struct sk_buff *prev,
842 struct sk_buff *next)
844 struct sk_buff *first = list->next;
845 struct sk_buff *last = list->prev;
847 first->prev = prev;
848 prev->next = first;
850 last->next = next;
851 next->prev = last;
855 * skb_queue_splice - join two skb lists, this is designed for stacks
856 * @list: the new list to add
857 * @head: the place to add it in the first list
859 static inline void skb_queue_splice(const struct sk_buff_head *list,
860 struct sk_buff_head *head)
862 if (!skb_queue_empty(list)) {
863 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
864 head->qlen += list->qlen;
869 * skb_queue_splice - join two skb lists and reinitialise the emptied list
870 * @list: the new list to add
871 * @head: the place to add it in the first list
873 * The list at @list is reinitialised
875 static inline void skb_queue_splice_init(struct sk_buff_head *list,
876 struct sk_buff_head *head)
878 if (!skb_queue_empty(list)) {
879 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
880 head->qlen += list->qlen;
881 __skb_queue_head_init(list);
886 * skb_queue_splice_tail - join two skb lists, each list being a queue
887 * @list: the new list to add
888 * @head: the place to add it in the first list
890 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
891 struct sk_buff_head *head)
893 if (!skb_queue_empty(list)) {
894 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
895 head->qlen += list->qlen;
900 * skb_queue_splice_tail - join two skb lists and reinitialise the emptied list
901 * @list: the new list to add
902 * @head: the place to add it in the first list
904 * Each of the lists is a queue.
905 * The list at @list is reinitialised
907 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
908 struct sk_buff_head *head)
910 if (!skb_queue_empty(list)) {
911 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
912 head->qlen += list->qlen;
913 __skb_queue_head_init(list);
918 * __skb_queue_after - queue a buffer at the list head
919 * @list: list to use
920 * @prev: place after this buffer
921 * @newsk: buffer to queue
923 * Queue a buffer int the middle of a list. This function takes no locks
924 * and you must therefore hold required locks before calling it.
926 * A buffer cannot be placed on two lists at the same time.
928 static inline void __skb_queue_after(struct sk_buff_head *list,
929 struct sk_buff *prev,
930 struct sk_buff *newsk)
932 __skb_insert(newsk, prev, prev->next, list);
935 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk,
936 struct sk_buff_head *list);
938 static inline void __skb_queue_before(struct sk_buff_head *list,
939 struct sk_buff *next,
940 struct sk_buff *newsk)
942 __skb_insert(newsk, next->prev, next, list);
946 * __skb_queue_head - queue a buffer at the list head
947 * @list: list to use
948 * @newsk: buffer to queue
950 * Queue a buffer at the start of a list. This function takes no locks
951 * and you must therefore hold required locks before calling it.
953 * A buffer cannot be placed on two lists at the same time.
955 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
956 static inline void __skb_queue_head(struct sk_buff_head *list,
957 struct sk_buff *newsk)
959 __skb_queue_after(list, (struct sk_buff *)list, newsk);
963 * __skb_queue_tail - queue a buffer at the list tail
964 * @list: list to use
965 * @newsk: buffer to queue
967 * Queue a buffer at the end of a list. This function takes no locks
968 * and you must therefore hold required locks before calling it.
970 * A buffer cannot be placed on two lists at the same time.
972 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
973 static inline void __skb_queue_tail(struct sk_buff_head *list,
974 struct sk_buff *newsk)
976 __skb_queue_before(list, (struct sk_buff *)list, newsk);
980 * remove sk_buff from list. _Must_ be called atomically, and with
981 * the list known..
983 extern void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
984 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
986 struct sk_buff *next, *prev;
988 list->qlen--;
989 next = skb->next;
990 prev = skb->prev;
991 skb->next = skb->prev = NULL;
992 next->prev = prev;
993 prev->next = next;
997 * __skb_dequeue - remove from the head of the queue
998 * @list: list to dequeue from
1000 * Remove the head of the list. This function does not take any locks
1001 * so must be used with appropriate locks held only. The head item is
1002 * returned or %NULL if the list is empty.
1004 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1005 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1007 struct sk_buff *skb = skb_peek(list);
1008 if (skb)
1009 __skb_unlink(skb, list);
1010 return skb;
1014 * __skb_dequeue_tail - remove from the tail of the queue
1015 * @list: list to dequeue from
1017 * Remove the tail of the list. This function does not take any locks
1018 * so must be used with appropriate locks held only. The tail item is
1019 * returned or %NULL if the list is empty.
1021 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1022 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1024 struct sk_buff *skb = skb_peek_tail(list);
1025 if (skb)
1026 __skb_unlink(skb, list);
1027 return skb;
1031 static inline int skb_is_nonlinear(const struct sk_buff *skb)
1033 return skb->data_len;
1036 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1038 return skb->len - skb->data_len;
1041 static inline int skb_pagelen(const struct sk_buff *skb)
1043 int i, len = 0;
1045 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1046 len += skb_shinfo(skb)->frags[i].size;
1047 return len + skb_headlen(skb);
1050 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1051 struct page *page, int off, int size)
1053 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1055 frag->page = page;
1056 frag->page_offset = off;
1057 frag->size = size;
1058 skb_shinfo(skb)->nr_frags = i + 1;
1061 extern void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page,
1062 int off, int size);
1064 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
1065 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
1066 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
1068 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1069 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1071 return skb->head + skb->tail;
1074 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1076 skb->tail = skb->data - skb->head;
1079 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1081 skb_reset_tail_pointer(skb);
1082 skb->tail += offset;
1084 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1085 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1087 return skb->tail;
1090 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1092 skb->tail = skb->data;
1095 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1097 skb->tail = skb->data + offset;
1100 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1103 * Add data to an sk_buff
1105 extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1106 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1108 unsigned char *tmp = skb_tail_pointer(skb);
1109 SKB_LINEAR_ASSERT(skb);
1110 skb->tail += len;
1111 skb->len += len;
1112 return tmp;
1115 extern unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1116 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1118 skb->data -= len;
1119 skb->len += len;
1120 return skb->data;
1123 extern unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1124 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1126 skb->len -= len;
1127 BUG_ON(skb->len < skb->data_len);
1128 return skb->data += len;
1131 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1133 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1135 if (len > skb_headlen(skb) &&
1136 !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1137 return NULL;
1138 skb->len -= len;
1139 return skb->data += len;
1142 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1144 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1147 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1149 if (likely(len <= skb_headlen(skb)))
1150 return 1;
1151 if (unlikely(len > skb->len))
1152 return 0;
1153 return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1157 * skb_headroom - bytes at buffer head
1158 * @skb: buffer to check
1160 * Return the number of bytes of free space at the head of an &sk_buff.
1162 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1164 return skb->data - skb->head;
1168 * skb_tailroom - bytes at buffer end
1169 * @skb: buffer to check
1171 * Return the number of bytes of free space at the tail of an sk_buff
1173 static inline int skb_tailroom(const struct sk_buff *skb)
1175 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1179 * skb_reserve - adjust headroom
1180 * @skb: buffer to alter
1181 * @len: bytes to move
1183 * Increase the headroom of an empty &sk_buff by reducing the tail
1184 * room. This is only allowed for an empty buffer.
1186 static inline void skb_reserve(struct sk_buff *skb, int len)
1188 skb->data += len;
1189 skb->tail += len;
1192 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1193 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1195 return skb->head + skb->transport_header;
1198 static inline void skb_reset_transport_header(struct sk_buff *skb)
1200 skb->transport_header = skb->data - skb->head;
1203 static inline void skb_set_transport_header(struct sk_buff *skb,
1204 const int offset)
1206 skb_reset_transport_header(skb);
1207 skb->transport_header += offset;
1210 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1212 return skb->head + skb->network_header;
1215 static inline void skb_reset_network_header(struct sk_buff *skb)
1217 skb->network_header = skb->data - skb->head;
1220 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1222 skb_reset_network_header(skb);
1223 skb->network_header += offset;
1226 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1228 return skb->head + skb->mac_header;
1231 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1233 return skb->mac_header != ~0U;
1236 static inline void skb_reset_mac_header(struct sk_buff *skb)
1238 skb->mac_header = skb->data - skb->head;
1241 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1243 skb_reset_mac_header(skb);
1244 skb->mac_header += offset;
1247 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1249 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1251 return skb->transport_header;
1254 static inline void skb_reset_transport_header(struct sk_buff *skb)
1256 skb->transport_header = skb->data;
1259 static inline void skb_set_transport_header(struct sk_buff *skb,
1260 const int offset)
1262 skb->transport_header = skb->data + offset;
1265 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1267 return skb->network_header;
1270 static inline void skb_reset_network_header(struct sk_buff *skb)
1272 skb->network_header = skb->data;
1275 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1277 skb->network_header = skb->data + offset;
1280 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1282 return skb->mac_header;
1285 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1287 return skb->mac_header != NULL;
1290 static inline void skb_reset_mac_header(struct sk_buff *skb)
1292 skb->mac_header = skb->data;
1295 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1297 skb->mac_header = skb->data + offset;
1299 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1301 static inline int skb_transport_offset(const struct sk_buff *skb)
1303 return skb_transport_header(skb) - skb->data;
1306 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1308 return skb->transport_header - skb->network_header;
1311 static inline int skb_network_offset(const struct sk_buff *skb)
1313 return skb_network_header(skb) - skb->data;
1317 * CPUs often take a performance hit when accessing unaligned memory
1318 * locations. The actual performance hit varies, it can be small if the
1319 * hardware handles it or large if we have to take an exception and fix it
1320 * in software.
1322 * Since an ethernet header is 14 bytes network drivers often end up with
1323 * the IP header at an unaligned offset. The IP header can be aligned by
1324 * shifting the start of the packet by 2 bytes. Drivers should do this
1325 * with:
1327 * skb_reserve(NET_IP_ALIGN);
1329 * The downside to this alignment of the IP header is that the DMA is now
1330 * unaligned. On some architectures the cost of an unaligned DMA is high
1331 * and this cost outweighs the gains made by aligning the IP header.
1333 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1334 * to be overridden.
1336 #ifndef NET_IP_ALIGN
1337 #define NET_IP_ALIGN 2
1338 #endif
1341 * The networking layer reserves some headroom in skb data (via
1342 * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1343 * the header has to grow. In the default case, if the header has to grow
1344 * 32 bytes or less we avoid the reallocation.
1346 * Unfortunately this headroom changes the DMA alignment of the resulting
1347 * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1348 * on some architectures. An architecture can override this value,
1349 * perhaps setting it to a cacheline in size (since that will maintain
1350 * cacheline alignment of the DMA). It must be a power of 2.
1352 * Various parts of the networking layer expect at least 32 bytes of
1353 * headroom, you should not reduce this.
1355 #ifndef NET_SKB_PAD
1356 #define NET_SKB_PAD 32
1357 #endif
1359 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1361 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1363 if (unlikely(skb->data_len)) {
1364 WARN_ON(1);
1365 return;
1367 skb->len = len;
1368 skb_set_tail_pointer(skb, len);
1371 extern void skb_trim(struct sk_buff *skb, unsigned int len);
1373 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1375 if (skb->data_len)
1376 return ___pskb_trim(skb, len);
1377 __skb_trim(skb, len);
1378 return 0;
1381 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1383 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1387 * pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1388 * @skb: buffer to alter
1389 * @len: new length
1391 * This is identical to pskb_trim except that the caller knows that
1392 * the skb is not cloned so we should never get an error due to out-
1393 * of-memory.
1395 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1397 int err = pskb_trim(skb, len);
1398 BUG_ON(err);
1402 * skb_orphan - orphan a buffer
1403 * @skb: buffer to orphan
1405 * If a buffer currently has an owner then we call the owner's
1406 * destructor function and make the @skb unowned. The buffer continues
1407 * to exist but is no longer charged to its former owner.
1409 static inline void skb_orphan(struct sk_buff *skb)
1411 if (skb->destructor)
1412 skb->destructor(skb);
1413 skb->destructor = NULL;
1414 skb->sk = NULL;
1418 * __skb_queue_purge - empty a list
1419 * @list: list to empty
1421 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1422 * the list and one reference dropped. This function does not take the
1423 * list lock and the caller must hold the relevant locks to use it.
1425 extern void skb_queue_purge(struct sk_buff_head *list);
1426 static inline void __skb_queue_purge(struct sk_buff_head *list)
1428 struct sk_buff *skb;
1429 while ((skb = __skb_dequeue(list)) != NULL)
1430 kfree_skb(skb);
1434 * __dev_alloc_skb - allocate an skbuff for receiving
1435 * @length: length to allocate
1436 * @gfp_mask: get_free_pages mask, passed to alloc_skb
1438 * Allocate a new &sk_buff and assign it a usage count of one. The
1439 * buffer has unspecified headroom built in. Users should allocate
1440 * the headroom they think they need without accounting for the
1441 * built in space. The built in space is used for optimisations.
1443 * %NULL is returned if there is no free memory.
1445 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
1446 gfp_t gfp_mask)
1448 struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
1449 if (likely(skb))
1450 skb_reserve(skb, NET_SKB_PAD);
1451 return skb;
1454 extern struct sk_buff *dev_alloc_skb(unsigned int length);
1456 extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
1457 unsigned int length, gfp_t gfp_mask);
1460 * netdev_alloc_skb - allocate an skbuff for rx on a specific device
1461 * @dev: network device to receive on
1462 * @length: length to allocate
1464 * Allocate a new &sk_buff and assign it a usage count of one. The
1465 * buffer has unspecified headroom built in. Users should allocate
1466 * the headroom they think they need without accounting for the
1467 * built in space. The built in space is used for optimisations.
1469 * %NULL is returned if there is no free memory. Although this function
1470 * allocates memory it can be called from an interrupt.
1472 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
1473 unsigned int length)
1475 return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
1478 extern struct page *__netdev_alloc_page(struct net_device *dev, gfp_t gfp_mask);
1481 * netdev_alloc_page - allocate a page for ps-rx on a specific device
1482 * @dev: network device to receive on
1484 * Allocate a new page node local to the specified device.
1486 * %NULL is returned if there is no free memory.
1488 static inline struct page *netdev_alloc_page(struct net_device *dev)
1490 return __netdev_alloc_page(dev, GFP_ATOMIC);
1493 static inline void netdev_free_page(struct net_device *dev, struct page *page)
1495 __free_page(page);
1499 * skb_clone_writable - is the header of a clone writable
1500 * @skb: buffer to check
1501 * @len: length up to which to write
1503 * Returns true if modifying the header part of the cloned buffer
1504 * does not requires the data to be copied.
1506 static inline int skb_clone_writable(struct sk_buff *skb, unsigned int len)
1508 return !skb_header_cloned(skb) &&
1509 skb_headroom(skb) + len <= skb->hdr_len;
1512 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
1513 int cloned)
1515 int delta = 0;
1517 if (headroom < NET_SKB_PAD)
1518 headroom = NET_SKB_PAD;
1519 if (headroom > skb_headroom(skb))
1520 delta = headroom - skb_headroom(skb);
1522 if (delta || cloned)
1523 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
1524 GFP_ATOMIC);
1525 return 0;
1529 * skb_cow - copy header of skb when it is required
1530 * @skb: buffer to cow
1531 * @headroom: needed headroom
1533 * If the skb passed lacks sufficient headroom or its data part
1534 * is shared, data is reallocated. If reallocation fails, an error
1535 * is returned and original skb is not changed.
1537 * The result is skb with writable area skb->head...skb->tail
1538 * and at least @headroom of space at head.
1540 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
1542 return __skb_cow(skb, headroom, skb_cloned(skb));
1546 * skb_cow_head - skb_cow but only making the head writable
1547 * @skb: buffer to cow
1548 * @headroom: needed headroom
1550 * This function is identical to skb_cow except that we replace the
1551 * skb_cloned check by skb_header_cloned. It should be used when
1552 * you only need to push on some header and do not need to modify
1553 * the data.
1555 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
1557 return __skb_cow(skb, headroom, skb_header_cloned(skb));
1561 * skb_padto - pad an skbuff up to a minimal size
1562 * @skb: buffer to pad
1563 * @len: minimal length
1565 * Pads up a buffer to ensure the trailing bytes exist and are
1566 * blanked. If the buffer already contains sufficient data it
1567 * is untouched. Otherwise it is extended. Returns zero on
1568 * success. The skb is freed on error.
1571 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
1573 unsigned int size = skb->len;
1574 if (likely(size >= len))
1575 return 0;
1576 return skb_pad(skb, len - size);
1579 static inline int skb_add_data(struct sk_buff *skb,
1580 char __user *from, int copy)
1582 const int off = skb->len;
1584 if (skb->ip_summed == CHECKSUM_NONE) {
1585 int err = 0;
1586 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
1587 copy, 0, &err);
1588 if (!err) {
1589 skb->csum = csum_block_add(skb->csum, csum, off);
1590 return 0;
1592 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1593 return 0;
1595 __skb_trim(skb, off);
1596 return -EFAULT;
1599 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1600 struct page *page, int off)
1602 if (i) {
1603 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1605 return page == frag->page &&
1606 off == frag->page_offset + frag->size;
1608 return 0;
1611 static inline int __skb_linearize(struct sk_buff *skb)
1613 return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
1617 * skb_linearize - convert paged skb to linear one
1618 * @skb: buffer to linarize
1620 * If there is no free memory -ENOMEM is returned, otherwise zero
1621 * is returned and the old skb data released.
1623 static inline int skb_linearize(struct sk_buff *skb)
1625 return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
1629 * skb_linearize_cow - make sure skb is linear and writable
1630 * @skb: buffer to process
1632 * If there is no free memory -ENOMEM is returned, otherwise zero
1633 * is returned and the old skb data released.
1635 static inline int skb_linearize_cow(struct sk_buff *skb)
1637 return skb_is_nonlinear(skb) || skb_cloned(skb) ?
1638 __skb_linearize(skb) : 0;
1642 * skb_postpull_rcsum - update checksum for received skb after pull
1643 * @skb: buffer to update
1644 * @start: start of data before pull
1645 * @len: length of data pulled
1647 * After doing a pull on a received packet, you need to call this to
1648 * update the CHECKSUM_COMPLETE checksum, or set ip_summed to
1649 * CHECKSUM_NONE so that it can be recomputed from scratch.
1652 static inline void skb_postpull_rcsum(struct sk_buff *skb,
1653 const void *start, unsigned int len)
1655 if (skb->ip_summed == CHECKSUM_COMPLETE)
1656 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
1659 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
1662 * pskb_trim_rcsum - trim received skb and update checksum
1663 * @skb: buffer to trim
1664 * @len: new length
1666 * This is exactly the same as pskb_trim except that it ensures the
1667 * checksum of received packets are still valid after the operation.
1670 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
1672 if (likely(len >= skb->len))
1673 return 0;
1674 if (skb->ip_summed == CHECKSUM_COMPLETE)
1675 skb->ip_summed = CHECKSUM_NONE;
1676 return __pskb_trim(skb, len);
1679 #define skb_queue_walk(queue, skb) \
1680 for (skb = (queue)->next; \
1681 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1682 skb = skb->next)
1684 #define skb_queue_walk_safe(queue, skb, tmp) \
1685 for (skb = (queue)->next, tmp = skb->next; \
1686 skb != (struct sk_buff *)(queue); \
1687 skb = tmp, tmp = skb->next)
1689 #define skb_queue_walk_from(queue, skb) \
1690 for (; prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1691 skb = skb->next)
1693 #define skb_queue_walk_from_safe(queue, skb, tmp) \
1694 for (tmp = skb->next; \
1695 skb != (struct sk_buff *)(queue); \
1696 skb = tmp, tmp = skb->next)
1698 #define skb_queue_reverse_walk(queue, skb) \
1699 for (skb = (queue)->prev; \
1700 prefetch(skb->prev), (skb != (struct sk_buff *)(queue)); \
1701 skb = skb->prev)
1704 extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
1705 int *peeked, int *err);
1706 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1707 int noblock, int *err);
1708 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1709 struct poll_table_struct *wait);
1710 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1711 int offset, struct iovec *to,
1712 int size);
1713 extern int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
1714 int hlen,
1715 struct iovec *iov);
1716 extern int skb_copy_datagram_from_iovec(struct sk_buff *skb,
1717 int offset,
1718 struct iovec *from,
1719 int len);
1720 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1721 extern int skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
1722 unsigned int flags);
1723 extern __wsum skb_checksum(const struct sk_buff *skb, int offset,
1724 int len, __wsum csum);
1725 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1726 void *to, int len);
1727 extern int skb_store_bits(struct sk_buff *skb, int offset,
1728 const void *from, int len);
1729 extern __wsum skb_copy_and_csum_bits(const struct sk_buff *skb,
1730 int offset, u8 *to, int len,
1731 __wsum csum);
1732 extern int skb_splice_bits(struct sk_buff *skb,
1733 unsigned int offset,
1734 struct pipe_inode_info *pipe,
1735 unsigned int len,
1736 unsigned int flags);
1737 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1738 extern void skb_split(struct sk_buff *skb,
1739 struct sk_buff *skb1, const u32 len);
1740 extern int skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
1741 int shiftlen);
1743 extern struct sk_buff *skb_segment(struct sk_buff *skb, int features);
1745 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
1746 int len, void *buffer)
1748 int hlen = skb_headlen(skb);
1750 if (hlen - offset >= len)
1751 return skb->data + offset;
1753 if (skb_copy_bits(skb, offset, buffer, len) < 0)
1754 return NULL;
1756 return buffer;
1759 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
1760 void *to,
1761 const unsigned int len)
1763 memcpy(to, skb->data, len);
1766 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
1767 const int offset, void *to,
1768 const unsigned int len)
1770 memcpy(to, skb->data + offset, len);
1773 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
1774 const void *from,
1775 const unsigned int len)
1777 memcpy(skb->data, from, len);
1780 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
1781 const int offset,
1782 const void *from,
1783 const unsigned int len)
1785 memcpy(skb->data + offset, from, len);
1788 extern void skb_init(void);
1790 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
1792 return skb->tstamp;
1796 * skb_get_timestamp - get timestamp from a skb
1797 * @skb: skb to get stamp from
1798 * @stamp: pointer to struct timeval to store stamp in
1800 * Timestamps are stored in the skb as offsets to a base timestamp.
1801 * This function converts the offset back to a struct timeval and stores
1802 * it in stamp.
1804 static inline void skb_get_timestamp(const struct sk_buff *skb,
1805 struct timeval *stamp)
1807 *stamp = ktime_to_timeval(skb->tstamp);
1810 static inline void skb_get_timestampns(const struct sk_buff *skb,
1811 struct timespec *stamp)
1813 *stamp = ktime_to_timespec(skb->tstamp);
1816 static inline void __net_timestamp(struct sk_buff *skb)
1818 skb->tstamp = ktime_get_real();
1821 static inline ktime_t net_timedelta(ktime_t t)
1823 return ktime_sub(ktime_get_real(), t);
1826 static inline ktime_t net_invalid_timestamp(void)
1828 return ktime_set(0, 0);
1832 * skb_tstamp_tx - queue clone of skb with send time stamps
1833 * @orig_skb: the original outgoing packet
1834 * @hwtstamps: hardware time stamps, may be NULL if not available
1836 * If the skb has a socket associated, then this function clones the
1837 * skb (thus sharing the actual data and optional structures), stores
1838 * the optional hardware time stamping information (if non NULL) or
1839 * generates a software time stamp (otherwise), then queues the clone
1840 * to the error queue of the socket. Errors are silently ignored.
1842 extern void skb_tstamp_tx(struct sk_buff *orig_skb,
1843 struct skb_shared_hwtstamps *hwtstamps);
1845 extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
1846 extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
1848 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
1850 return skb->ip_summed & CHECKSUM_UNNECESSARY;
1854 * skb_checksum_complete - Calculate checksum of an entire packet
1855 * @skb: packet to process
1857 * This function calculates the checksum over the entire packet plus
1858 * the value of skb->csum. The latter can be used to supply the
1859 * checksum of a pseudo header as used by TCP/UDP. It returns the
1860 * checksum.
1862 * For protocols that contain complete checksums such as ICMP/TCP/UDP,
1863 * this function can be used to verify that checksum on received
1864 * packets. In that case the function should return zero if the
1865 * checksum is correct. In particular, this function will return zero
1866 * if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
1867 * hardware has already verified the correctness of the checksum.
1869 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
1871 return skb_csum_unnecessary(skb) ?
1872 0 : __skb_checksum_complete(skb);
1875 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1876 extern void nf_conntrack_destroy(struct nf_conntrack *nfct);
1877 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
1879 if (nfct && atomic_dec_and_test(&nfct->use))
1880 nf_conntrack_destroy(nfct);
1882 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
1884 if (nfct)
1885 atomic_inc(&nfct->use);
1887 static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
1889 if (skb)
1890 atomic_inc(&skb->users);
1892 static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
1894 if (skb)
1895 kfree_skb(skb);
1897 #endif
1898 #ifdef CONFIG_BRIDGE_NETFILTER
1899 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1901 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1902 kfree(nf_bridge);
1904 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1906 if (nf_bridge)
1907 atomic_inc(&nf_bridge->use);
1909 #endif /* CONFIG_BRIDGE_NETFILTER */
1910 static inline void nf_reset(struct sk_buff *skb)
1912 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1913 nf_conntrack_put(skb->nfct);
1914 skb->nfct = NULL;
1915 nf_conntrack_put_reasm(skb->nfct_reasm);
1916 skb->nfct_reasm = NULL;
1917 #endif
1918 #ifdef CONFIG_BRIDGE_NETFILTER
1919 nf_bridge_put(skb->nf_bridge);
1920 skb->nf_bridge = NULL;
1921 #endif
1924 /* Note: This doesn't put any conntrack and bridge info in dst. */
1925 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
1927 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1928 dst->nfct = src->nfct;
1929 nf_conntrack_get(src->nfct);
1930 dst->nfctinfo = src->nfctinfo;
1931 dst->nfct_reasm = src->nfct_reasm;
1932 nf_conntrack_get_reasm(src->nfct_reasm);
1933 #endif
1934 #ifdef CONFIG_BRIDGE_NETFILTER
1935 dst->nf_bridge = src->nf_bridge;
1936 nf_bridge_get(src->nf_bridge);
1937 #endif
1940 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
1942 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1943 nf_conntrack_put(dst->nfct);
1944 nf_conntrack_put_reasm(dst->nfct_reasm);
1945 #endif
1946 #ifdef CONFIG_BRIDGE_NETFILTER
1947 nf_bridge_put(dst->nf_bridge);
1948 #endif
1949 __nf_copy(dst, src);
1952 #ifdef CONFIG_NETWORK_SECMARK
1953 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
1955 to->secmark = from->secmark;
1958 static inline void skb_init_secmark(struct sk_buff *skb)
1960 skb->secmark = 0;
1962 #else
1963 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
1966 static inline void skb_init_secmark(struct sk_buff *skb)
1968 #endif
1970 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
1972 skb->queue_mapping = queue_mapping;
1975 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
1977 return skb->queue_mapping;
1980 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
1982 to->queue_mapping = from->queue_mapping;
1985 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
1987 skb->queue_mapping = rx_queue + 1;
1990 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
1992 return skb->queue_mapping - 1;
1995 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
1997 return (skb->queue_mapping != 0);
2000 extern u16 skb_tx_hash(const struct net_device *dev,
2001 const struct sk_buff *skb);
2003 #ifdef CONFIG_XFRM
2004 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2006 return skb->sp;
2008 #else
2009 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
2011 return NULL;
2013 #endif
2015 static inline int skb_is_gso(const struct sk_buff *skb)
2017 return skb_shinfo(skb)->gso_size;
2020 static inline int skb_is_gso_v6(const struct sk_buff *skb)
2022 return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
2025 extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
2027 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
2029 /* LRO sets gso_size but not gso_type, whereas if GSO is really
2030 * wanted then gso_type will be set. */
2031 struct skb_shared_info *shinfo = skb_shinfo(skb);
2032 if (shinfo->gso_size != 0 && unlikely(shinfo->gso_type == 0)) {
2033 __skb_warn_lro_forwarding(skb);
2034 return true;
2036 return false;
2039 static inline void skb_forward_csum(struct sk_buff *skb)
2041 /* Unfortunately we don't support this one. Any brave souls? */
2042 if (skb->ip_summed == CHECKSUM_COMPLETE)
2043 skb->ip_summed = CHECKSUM_NONE;
2046 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
2047 #endif /* __KERNEL__ */
2048 #endif /* _LINUX_SKBUFF_H */