2 * Definitions for the 'struct sk_buff' memory handlers.
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/config.h>
18 #include <linux/kernel.h>
19 #include <linux/compiler.h>
20 #include <linux/time.h>
21 #include <linux/cache.h>
23 #include <asm/atomic.h>
24 #include <asm/types.h>
25 #include <linux/spinlock.h>
27 #include <linux/highmem.h>
28 #include <linux/poll.h>
29 #include <linux/net.h>
30 #include <net/checksum.h>
32 #define HAVE_ALLOC_SKB /* For the drivers to know */
33 #define HAVE_ALIGNABLE_SKB /* Ditto 8) */
34 #define SLAB_SKB /* Slabified skbuffs */
36 #define CHECKSUM_NONE 0
38 #define CHECKSUM_UNNECESSARY 2
40 #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
41 ~(SMP_CACHE_BYTES - 1))
42 #define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \
43 sizeof(struct skb_shared_info)) & \
44 ~(SMP_CACHE_BYTES - 1))
45 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
46 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
48 /* A. Checksumming of received packets by device.
50 * NONE: device failed to checksum this packet.
51 * skb->csum is undefined.
53 * UNNECESSARY: device parsed packet and wouldbe verified checksum.
54 * skb->csum is undefined.
55 * It is bad option, but, unfortunately, many of vendors do this.
56 * Apparently with secret goal to sell you new device, when you
57 * will add new protocol to your host. F.e. IPv6. 8)
59 * HW: the most generic way. Device supplied checksum of _all_
60 * the packet as seen by netif_rx in skb->csum.
61 * NOTE: Even if device supports only some protocols, but
62 * is able to produce some skb->csum, it MUST use HW,
65 * B. Checksumming on output.
67 * NONE: skb is checksummed by protocol or csum is not required.
69 * HW: device is required to csum packet as seen by hard_start_xmit
70 * from skb->h.raw to the end and to record the checksum
71 * at skb->h.raw+skb->csum.
73 * Device must show its capabilities in dev->features, set
74 * at device setup time.
75 * NETIF_F_HW_CSUM - it is clever device, it is able to checksum
77 * NETIF_F_NO_CSUM - loopback or reliable single hop media.
78 * NETIF_F_IP_CSUM - device is dumb. It is able to csum only
79 * TCP/UDP over IPv4. Sigh. Vendors like this
80 * way by an unknown reason. Though, see comment above
81 * about CHECKSUM_UNNECESSARY. 8)
83 * Any questions? No questions, good. --ANK
88 #ifdef CONFIG_NETFILTER
91 void (*destroy)(struct nf_conntrack *);
94 #ifdef CONFIG_BRIDGE_NETFILTER
95 struct nf_bridge_info {
97 struct net_device *physindev;
98 struct net_device *physoutdev;
99 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
100 struct net_device *netoutdev;
103 unsigned long data[32 / sizeof(unsigned long)];
109 struct sk_buff_head {
110 /* These two members must be first. */
111 struct sk_buff *next;
112 struct sk_buff *prev;
120 /* To allow 64K frame to be packed as single skb without frag_list */
121 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
123 typedef struct skb_frag_struct skb_frag_t;
125 struct skb_frag_struct {
131 /* This data is invariant across clones and lives at
132 * the end of the header data, ie. at skb->end.
134 struct skb_shared_info {
136 unsigned int nr_frags;
137 unsigned short tso_size;
138 unsigned short tso_segs;
139 struct sk_buff *frag_list;
140 skb_frag_t frags[MAX_SKB_FRAGS];
143 /* We divide dataref into two halves. The higher 16 bits hold references
144 * to the payload part of skb->data. The lower 16 bits hold references to
145 * the entire skb->data. It is up to the users of the skb to agree on
146 * where the payload starts.
148 * All users must obey the rule that the skb->data reference count must be
149 * greater than or equal to the payload reference count.
151 * Holding a reference to the payload part means that the user does not
152 * care about modifications to the header part of skb->data.
154 #define SKB_DATAREF_SHIFT 16
155 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
158 * struct sk_buff - socket buffer
159 * @next: Next buffer in list
160 * @prev: Previous buffer in list
161 * @list: List we are on
162 * @sk: Socket we are owned by
163 * @stamp: Time we arrived
164 * @dev: Device we arrived on/are leaving by
165 * @input_dev: Device we arrived on
166 * @real_dev: The real device we are using
167 * @h: Transport layer header
168 * @nh: Network layer header
169 * @mac: Link layer header
170 * @dst: destination entry
171 * @sp: the security path, used for xfrm
172 * @cb: Control buffer. Free for use by every layer. Put private vars here
173 * @len: Length of actual data
174 * @data_len: Data length
175 * @mac_len: Length of link layer header
177 * @local_df: allow local fragmentation
178 * @cloned: Head may be cloned (check refcnt to be sure)
179 * @nohdr: Payload reference only, must not modify header
180 * @pkt_type: Packet class
181 * @ip_summed: Driver fed us an IP checksum
182 * @priority: Packet queueing priority
183 * @users: User count - see {datagram,tcp}.c
184 * @protocol: Packet protocol from driver
185 * @security: Security level of packet
186 * @truesize: Buffer size
187 * @head: Head of buffer
188 * @data: Data head pointer
189 * @tail: Tail pointer
191 * @destructor: Destruct function
192 * @nfmark: Can be used for communication between hooks
193 * @nfcache: Cache info
194 * @nfct: Associated connection, if any
195 * @nfctinfo: Relationship of this skb to the connection
196 * @nf_debug: Netfilter debugging
197 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
198 * @private: Data which is private to the HIPPI implementation
199 * @tc_index: Traffic control index
200 * @tc_verd: traffic control verdict
201 * @tc_classid: traffic control classid
205 /* These two members must be first. */
206 struct sk_buff *next;
207 struct sk_buff *prev;
209 struct sk_buff_head *list;
211 struct timeval stamp;
212 struct net_device *dev;
213 struct net_device *input_dev;
214 struct net_device *real_dev;
219 struct icmphdr *icmph;
220 struct igmphdr *igmph;
222 struct ipv6hdr *ipv6h;
228 struct ipv6hdr *ipv6h;
237 struct dst_entry *dst;
241 * This is the control buffer. It is free to use for every
242 * layer. Please put your private variables there. If you
243 * want to keep them across layers you have to do a skb_clone()
244 * first. This is owned by whoever has the skb queued ATM.
252 unsigned char local_df,
258 unsigned short protocol,
261 void (*destructor)(struct sk_buff *skb);
262 #ifdef CONFIG_NETFILTER
263 unsigned long nfmark;
266 struct nf_conntrack *nfct;
267 #ifdef CONFIG_NETFILTER_DEBUG
268 unsigned int nf_debug;
270 #ifdef CONFIG_BRIDGE_NETFILTER
271 struct nf_bridge_info *nf_bridge;
273 #endif /* CONFIG_NETFILTER */
274 #if defined(CONFIG_HIPPI)
279 #ifdef CONFIG_NET_SCHED
280 __u32 tc_index; /* traffic control index */
281 #ifdef CONFIG_NET_CLS_ACT
282 __u32 tc_verd; /* traffic control verdict */
283 __u32 tc_classid; /* traffic control classid */
287 #if defined(CONFIG_VNET) || defined(CONFIG_VNET_MODULE)
288 xid_t xid; /* VServer context ID */
291 /* These elements must be at the end, see alloc_skb() for details. */
292 unsigned int truesize;
302 * Handling routines are only of interest to the kernel
304 #include <linux/slab.h>
306 #include <asm/system.h>
308 extern void __kfree_skb(struct sk_buff *skb);
309 extern struct sk_buff *alloc_skb(unsigned int size, int priority);
310 extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
311 unsigned int size, int priority);
312 extern void kfree_skbmem(struct sk_buff *skb);
313 extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
314 extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
315 extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
316 extern int pskb_expand_head(struct sk_buff *skb,
317 int nhead, int ntail, int gfp_mask);
318 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
319 unsigned int headroom);
320 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
321 int newheadroom, int newtailroom,
323 extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
324 #define dev_kfree_skb(a) kfree_skb(a)
325 extern void skb_over_panic(struct sk_buff *skb, int len,
327 extern void skb_under_panic(struct sk_buff *skb, int len,
331 #define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
334 * skb_queue_empty - check if a queue is empty
337 * Returns true if the queue is empty, false otherwise.
339 static inline int skb_queue_empty(const struct sk_buff_head *list)
341 return list->next == (struct sk_buff *)list;
345 * skb_get - reference buffer
346 * @skb: buffer to reference
348 * Makes another reference to a socket buffer and returns a pointer
351 static inline struct sk_buff *skb_get(struct sk_buff *skb)
353 atomic_inc(&skb->users);
358 * If users == 1, we are the only owner and are can avoid redundant
363 * kfree_skb - free an sk_buff
364 * @skb: buffer to free
366 * Drop a reference to the buffer and free it if the usage count has
369 static inline void kfree_skb(struct sk_buff *skb)
371 if (likely(atomic_read(&skb->users) == 1))
373 else if (likely(!atomic_dec_and_test(&skb->users)))
379 * skb_cloned - is the buffer a clone
380 * @skb: buffer to check
382 * Returns true if the buffer was generated with skb_clone() and is
383 * one of multiple shared copies of the buffer. Cloned buffers are
384 * shared data so must not be written to under normal circumstances.
386 static inline int skb_cloned(const struct sk_buff *skb)
388 return skb->cloned &&
389 (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
393 * skb_header_cloned - is the header a clone
394 * @skb: buffer to check
396 * Returns true if modifying the header part of the buffer requires
397 * the data to be copied.
399 static inline int skb_header_cloned(const struct sk_buff *skb)
406 dataref = atomic_read(&skb_shinfo(skb)->dataref);
407 dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
412 * skb_header_release - release reference to header
413 * @skb: buffer to operate on
415 * Drop a reference to the header part of the buffer. This is done
416 * by acquiring a payload reference. You must not read from the header
417 * part of skb->data after this.
419 static inline void skb_header_release(struct sk_buff *skb)
423 atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
427 * skb_shared - is the buffer shared
428 * @skb: buffer to check
430 * Returns true if more than one person has a reference to this
433 static inline int skb_shared(const struct sk_buff *skb)
435 return atomic_read(&skb->users) != 1;
439 * skb_share_check - check if buffer is shared and if so clone it
440 * @skb: buffer to check
441 * @pri: priority for memory allocation
443 * If the buffer is shared the buffer is cloned and the old copy
444 * drops a reference. A new clone with a single reference is returned.
445 * If the buffer is not shared the original buffer is returned. When
446 * being called from interrupt status or with spinlocks held pri must
449 * NULL is returned on a memory allocation failure.
451 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri)
453 might_sleep_if(pri & __GFP_WAIT);
454 if (skb_shared(skb)) {
455 struct sk_buff *nskb = skb_clone(skb, pri);
463 * Copy shared buffers into a new sk_buff. We effectively do COW on
464 * packets to handle cases where we have a local reader and forward
465 * and a couple of other messy ones. The normal one is tcpdumping
466 * a packet thats being forwarded.
470 * skb_unshare - make a copy of a shared buffer
471 * @skb: buffer to check
472 * @pri: priority for memory allocation
474 * If the socket buffer is a clone then this function creates a new
475 * copy of the data, drops a reference count on the old copy and returns
476 * the new copy with the reference count at 1. If the buffer is not a clone
477 * the original buffer is returned. When called with a spinlock held or
478 * from interrupt state @pri must be %GFP_ATOMIC
480 * %NULL is returned on a memory allocation failure.
482 static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri)
484 might_sleep_if(pri & __GFP_WAIT);
485 if (skb_cloned(skb)) {
486 struct sk_buff *nskb = skb_copy(skb, pri);
487 kfree_skb(skb); /* Free our shared copy */
495 * @list_: list to peek at
497 * Peek an &sk_buff. Unlike most other operations you _MUST_
498 * be careful with this one. A peek leaves the buffer on the
499 * list and someone else may run off with it. You must hold
500 * the appropriate locks or have a private queue to do this.
502 * Returns %NULL for an empty list or a pointer to the head element.
503 * The reference count is not incremented and the reference is therefore
504 * volatile. Use with caution.
506 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
508 struct sk_buff *list = ((struct sk_buff *)list_)->next;
509 if (list == (struct sk_buff *)list_)
516 * @list_: list to peek at
518 * Peek an &sk_buff. Unlike most other operations you _MUST_
519 * be careful with this one. A peek leaves the buffer on the
520 * list and someone else may run off with it. You must hold
521 * the appropriate locks or have a private queue to do this.
523 * Returns %NULL for an empty list or a pointer to the tail element.
524 * The reference count is not incremented and the reference is therefore
525 * volatile. Use with caution.
527 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
529 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
530 if (list == (struct sk_buff *)list_)
536 * skb_queue_len - get queue length
537 * @list_: list to measure
539 * Return the length of an &sk_buff queue.
541 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
546 static inline void skb_queue_head_init(struct sk_buff_head *list)
548 spin_lock_init(&list->lock);
549 list->prev = list->next = (struct sk_buff *)list;
554 * Insert an sk_buff at the start of a list.
556 * The "__skb_xxxx()" functions are the non-atomic ones that
557 * can only be called with interrupts disabled.
561 * __skb_queue_head - queue a buffer at the list head
563 * @newsk: buffer to queue
565 * Queue a buffer at the start of a list. This function takes no locks
566 * and you must therefore hold required locks before calling it.
568 * A buffer cannot be placed on two lists at the same time.
570 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
571 static inline void __skb_queue_head(struct sk_buff_head *list,
572 struct sk_buff *newsk)
574 struct sk_buff *prev, *next;
578 prev = (struct sk_buff *)list;
582 next->prev = prev->next = newsk;
586 * __skb_queue_tail - queue a buffer at the list tail
588 * @newsk: buffer to queue
590 * Queue a buffer at the end of a list. This function takes no locks
591 * and you must therefore hold required locks before calling it.
593 * A buffer cannot be placed on two lists at the same time.
595 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
596 static inline void __skb_queue_tail(struct sk_buff_head *list,
597 struct sk_buff *newsk)
599 struct sk_buff *prev, *next;
603 next = (struct sk_buff *)list;
607 next->prev = prev->next = newsk;
612 * __skb_dequeue - remove from the head of the queue
613 * @list: list to dequeue from
615 * Remove the head of the list. This function does not take any locks
616 * so must be used with appropriate locks held only. The head item is
617 * returned or %NULL if the list is empty.
619 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
620 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
622 struct sk_buff *next, *prev, *result;
624 prev = (struct sk_buff *) list;
633 result->next = result->prev = NULL;
641 * Insert a packet on a list.
643 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk);
644 static inline void __skb_insert(struct sk_buff *newsk,
645 struct sk_buff *prev, struct sk_buff *next,
646 struct sk_buff_head *list)
650 next->prev = prev->next = newsk;
656 * Place a packet after a given packet in a list.
658 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk);
659 static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk)
661 __skb_insert(newsk, old, old->next, old->list);
665 * remove sk_buff from list. _Must_ be called atomically, and with
668 extern void skb_unlink(struct sk_buff *skb);
669 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
671 struct sk_buff *next, *prev;
676 skb->next = skb->prev = NULL;
683 /* XXX: more streamlined implementation */
686 * __skb_dequeue_tail - remove from the tail of the queue
687 * @list: list to dequeue from
689 * Remove the tail of the list. This function does not take any locks
690 * so must be used with appropriate locks held only. The tail item is
691 * returned or %NULL if the list is empty.
693 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
694 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
696 struct sk_buff *skb = skb_peek_tail(list);
698 __skb_unlink(skb, list);
703 static inline int skb_is_nonlinear(const struct sk_buff *skb)
705 return skb->data_len;
708 static inline unsigned int skb_headlen(const struct sk_buff *skb)
710 return skb->len - skb->data_len;
713 static inline int skb_pagelen(const struct sk_buff *skb)
717 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
718 len += skb_shinfo(skb)->frags[i].size;
719 return len + skb_headlen(skb);
722 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
723 struct page *page, int off, int size)
725 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
728 frag->page_offset = off;
730 skb_shinfo(skb)->nr_frags = i + 1;
733 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
734 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
735 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
738 * Add data to an sk_buff
740 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
742 unsigned char *tmp = skb->tail;
743 SKB_LINEAR_ASSERT(skb);
750 * skb_put - add data to a buffer
751 * @skb: buffer to use
752 * @len: amount of data to add
754 * This function extends the used data area of the buffer. If this would
755 * exceed the total buffer size the kernel will panic. A pointer to the
756 * first byte of the extra data is returned.
758 static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
760 unsigned char *tmp = skb->tail;
761 SKB_LINEAR_ASSERT(skb);
764 if (unlikely(skb->tail>skb->end))
765 skb_over_panic(skb, len, current_text_addr());
769 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
777 * skb_push - add data to the start of a buffer
778 * @skb: buffer to use
779 * @len: amount of data to add
781 * This function extends the used data area of the buffer at the buffer
782 * start. If this would exceed the total buffer headroom the kernel will
783 * panic. A pointer to the first byte of the extra data is returned.
785 static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
789 if (unlikely(skb->data<skb->head))
790 skb_under_panic(skb, len, current_text_addr());
794 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
797 BUG_ON(skb->len < skb->data_len);
798 return skb->data += len;
802 * skb_pull - remove data from the start of a buffer
803 * @skb: buffer to use
804 * @len: amount of data to remove
806 * This function removes data from the start of a buffer, returning
807 * the memory to the headroom. A pointer to the next data in the buffer
808 * is returned. Once the data has been pulled future pushes will overwrite
811 static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
813 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
816 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
818 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
820 if (len > skb_headlen(skb) &&
821 !__pskb_pull_tail(skb, len-skb_headlen(skb)))
824 return skb->data += len;
827 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
829 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
832 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
834 if (likely(len <= skb_headlen(skb)))
836 if (unlikely(len > skb->len))
838 return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
842 * skb_headroom - bytes at buffer head
843 * @skb: buffer to check
845 * Return the number of bytes of free space at the head of an &sk_buff.
847 static inline int skb_headroom(const struct sk_buff *skb)
849 return skb->data - skb->head;
853 * skb_tailroom - bytes at buffer end
854 * @skb: buffer to check
856 * Return the number of bytes of free space at the tail of an sk_buff
858 static inline int skb_tailroom(const struct sk_buff *skb)
860 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
864 * skb_reserve - adjust headroom
865 * @skb: buffer to alter
866 * @len: bytes to move
868 * Increase the headroom of an empty &sk_buff by reducing the tail
869 * room. This is only allowed for an empty buffer.
871 static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
878 * CPUs often take a performance hit when accessing unaligned memory
879 * locations. The actual performance hit varies, it can be small if the
880 * hardware handles it or large if we have to take an exception and fix it
883 * Since an ethernet header is 14 bytes network drivers often end up with
884 * the IP header at an unaligned offset. The IP header can be aligned by
885 * shifting the start of the packet by 2 bytes. Drivers should do this
888 * skb_reserve(NET_IP_ALIGN);
890 * The downside to this alignment of the IP header is that the DMA is now
891 * unaligned. On some architectures the cost of an unaligned DMA is high
892 * and this cost outweighs the gains made by aligning the IP header.
894 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
898 #define NET_IP_ALIGN 2
901 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
903 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
905 if (!skb->data_len) {
907 skb->tail = skb->data + len;
909 ___pskb_trim(skb, len, 0);
913 * skb_trim - remove end from a buffer
914 * @skb: buffer to alter
917 * Cut the length of a buffer down by removing data from the tail. If
918 * the buffer is already under the length specified it is not modified.
920 static inline void skb_trim(struct sk_buff *skb, unsigned int len)
923 __skb_trim(skb, len);
927 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
929 if (!skb->data_len) {
931 skb->tail = skb->data+len;
934 return ___pskb_trim(skb, len, 1);
937 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
939 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
943 * skb_orphan - orphan a buffer
944 * @skb: buffer to orphan
946 * If a buffer currently has an owner then we call the owner's
947 * destructor function and make the @skb unowned. The buffer continues
948 * to exist but is no longer charged to its former owner.
950 static inline void skb_orphan(struct sk_buff *skb)
953 skb->destructor(skb);
954 skb->destructor = NULL;
959 * __skb_queue_purge - empty a list
960 * @list: list to empty
962 * Delete all buffers on an &sk_buff list. Each buffer is removed from
963 * the list and one reference dropped. This function does not take the
964 * list lock and the caller must hold the relevant locks to use it.
966 extern void skb_queue_purge(struct sk_buff_head *list);
967 static inline void __skb_queue_purge(struct sk_buff_head *list)
970 while ((skb = __skb_dequeue(list)) != NULL)
974 #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
976 * __dev_alloc_skb - allocate an skbuff for sending
977 * @length: length to allocate
978 * @gfp_mask: get_free_pages mask, passed to alloc_skb
980 * Allocate a new &sk_buff and assign it a usage count of one. The
981 * buffer has unspecified headroom built in. Users should allocate
982 * the headroom they think they need without accounting for the
983 * built in space. The built in space is used for optimisations.
985 * %NULL is returned in there is no free memory.
987 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
990 struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
992 skb_reserve(skb, 16);
996 extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask);
1000 * dev_alloc_skb - allocate an skbuff for sending
1001 * @length: length to allocate
1003 * Allocate a new &sk_buff and assign it a usage count of one. The
1004 * buffer has unspecified headroom built in. Users should allocate
1005 * the headroom they think they need without accounting for the
1006 * built in space. The built in space is used for optimisations.
1008 * %NULL is returned in there is no free memory. Although this function
1009 * allocates memory it can be called from an interrupt.
1011 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1013 return __dev_alloc_skb(length, GFP_ATOMIC);
1017 * skb_cow - copy header of skb when it is required
1018 * @skb: buffer to cow
1019 * @headroom: needed headroom
1021 * If the skb passed lacks sufficient headroom or its data part
1022 * is shared, data is reallocated. If reallocation fails, an error
1023 * is returned and original skb is not changed.
1025 * The result is skb with writable area skb->head...skb->tail
1026 * and at least @headroom of space at head.
1028 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
1030 int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb);
1035 if (delta || skb_cloned(skb))
1036 return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC);
1041 * skb_padto - pad an skbuff up to a minimal size
1042 * @skb: buffer to pad
1043 * @len: minimal length
1045 * Pads up a buffer to ensure the trailing bytes exist and are
1046 * blanked. If the buffer already contains sufficient data it
1047 * is untouched. Returns the buffer, which may be a replacement
1048 * for the original, or NULL for out of memory - in which case
1049 * the original buffer is still freed.
1052 static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
1054 unsigned int size = skb->len;
1055 if (likely(size >= len))
1057 return skb_pad(skb, len-size);
1060 static inline int skb_add_data(struct sk_buff *skb,
1061 char __user *from, int copy)
1063 const int off = skb->len;
1065 if (skb->ip_summed == CHECKSUM_NONE) {
1067 unsigned int csum = csum_and_copy_from_user(from,
1071 skb->csum = csum_block_add(skb->csum, csum, off);
1074 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1077 __skb_trim(skb, off);
1081 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1082 struct page *page, int off)
1085 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1087 return page == frag->page &&
1088 off == frag->page_offset + frag->size;
1094 * skb_linearize - convert paged skb to linear one
1095 * @skb: buffer to linarize
1096 * @gfp: allocation mode
1098 * If there is no free memory -ENOMEM is returned, otherwise zero
1099 * is returned and the old skb data released.
1101 extern int __skb_linearize(struct sk_buff *skb, int gfp);
1102 static inline int skb_linearize(struct sk_buff *skb, int gfp)
1104 return __skb_linearize(skb, gfp);
1108 * skb_postpull_rcsum - update checksum for received skb after pull
1109 * @skb: buffer to update
1110 * @start: start of data before pull
1111 * @len: length of data pulled
1113 * After doing a pull on a received packet, you need to call this to
1114 * update the CHECKSUM_HW checksum, or set ip_summed to CHECKSUM_NONE
1115 * so that it can be recomputed from scratch.
1118 static inline void skb_postpull_rcsum(struct sk_buff *skb,
1119 const void *start, int len)
1121 if (skb->ip_summed == CHECKSUM_HW)
1122 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
1126 * pskb_trim_rcsum - trim received skb and update checksum
1127 * @skb: buffer to trim
1130 * This is exactly the same as pskb_trim except that it ensures the
1131 * checksum of received packets are still valid after the operation.
1134 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
1136 if (len >= skb->len)
1138 if (skb->ip_summed == CHECKSUM_HW)
1139 skb->ip_summed = CHECKSUM_NONE;
1140 return __pskb_trim(skb, len);
1143 static inline void *kmap_skb_frag(const skb_frag_t *frag)
1145 #ifdef CONFIG_HIGHMEM
1150 return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ);
1153 static inline void kunmap_skb_frag(void *vaddr)
1155 kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
1156 #ifdef CONFIG_HIGHMEM
1161 #define skb_queue_walk(queue, skb) \
1162 for (skb = (queue)->next; \
1163 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1167 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1168 int noblock, int *err);
1169 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1170 struct poll_table_struct *wait);
1171 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1172 int offset, struct iovec *to,
1174 extern int skb_copy_and_csum_datagram_iovec(const
1175 struct sk_buff *skb,
1178 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1179 extern unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1180 int len, unsigned int csum);
1181 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1183 extern int skb_store_bits(const struct sk_buff *skb, int offset,
1184 void *from, int len);
1185 extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb,
1186 int offset, u8 *to, int len,
1188 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1189 extern void skb_split(struct sk_buff *skb,
1190 struct sk_buff *skb1, const u32 len);
1192 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
1193 int len, void *buffer)
1195 int hlen = skb_headlen(skb);
1197 if (offset + len <= hlen)
1198 return skb->data + offset;
1200 if (skb_copy_bits(skb, offset, buffer, len) < 0)
1206 extern void skb_init(void);
1207 extern void skb_add_mtu(int mtu);
1209 struct tux_req_struct;
1211 #ifdef CONFIG_NETFILTER
1212 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
1214 if (nfct && atomic_dec_and_test(&nfct->use))
1215 nfct->destroy(nfct);
1217 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
1220 atomic_inc(&nfct->use);
1222 static inline void nf_reset(struct sk_buff *skb)
1224 nf_conntrack_put(skb->nfct);
1226 #ifdef CONFIG_NETFILTER_DEBUG
1230 static inline void nf_reset_debug(struct sk_buff *skb)
1232 #ifdef CONFIG_NETFILTER_DEBUG
1237 #ifdef CONFIG_BRIDGE_NETFILTER
1238 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1240 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1243 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1246 atomic_inc(&nf_bridge->use);
1248 #endif /* CONFIG_BRIDGE_NETFILTER */
1249 #else /* CONFIG_NETFILTER */
1250 static inline void nf_reset(struct sk_buff *skb) {}
1251 #endif /* CONFIG_NETFILTER */
1253 #endif /* __KERNEL__ */
1254 #endif /* _LINUX_SKBUFF_H */