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: FIXME: Describe this field
171 * @cb: Control buffer. Free for use by every layer. Put private vars here
172 * @len: Length of actual data
173 * @data_len: Data length
174 * @mac_len: Length of link layer header
176 * @__unused: Dead field, may be reused
177 * @cloned: Head may be cloned (check refcnt to be sure)
178 * @nohdr: Payload reference only, must not modify header
179 * @pkt_type: Packet class
180 * @ip_summed: Driver fed us an IP checksum
181 * @priority: Packet queueing priority
182 * @users: User count - see {datagram,tcp}.c
183 * @protocol: Packet protocol from driver
184 * @security: Security level of packet
185 * @truesize: Buffer size
186 * @head: Head of buffer
187 * @data: Data head pointer
188 * @tail: Tail pointer
190 * @destructor: Destruct function
191 * @nfmark: Can be used for communication between hooks
192 * @nfcache: Cache info
193 * @nfct: Associated connection, if any
194 * @nfctinfo: Relationship of this skb to the connection
195 * @nf_debug: Netfilter debugging
196 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
197 * @private: Data which is private to the HIPPI implementation
198 * @tc_index: Traffic control index
199 * @tc_verd: traffic control verdict
200 * @tc_classid: traffic control classid
204 /* These two members must be first. */
205 struct sk_buff *next;
206 struct sk_buff *prev;
208 struct sk_buff_head *list;
210 struct timeval stamp;
211 struct net_device *dev;
212 struct net_device *input_dev;
213 struct net_device *real_dev;
218 struct icmphdr *icmph;
219 struct igmphdr *igmph;
221 struct ipv6hdr *ipv6h;
227 struct ipv6hdr *ipv6h;
236 struct dst_entry *dst;
240 * This is the control buffer. It is free to use for every
241 * layer. Please put your private variables there. If you
242 * want to keep them across layers you have to do a skb_clone()
243 * first. This is owned by whoever has the skb queued ATM.
251 unsigned char local_df,
257 unsigned short protocol,
260 void (*destructor)(struct sk_buff *skb);
261 #ifdef CONFIG_NETFILTER
262 unsigned long nfmark;
265 struct nf_conntrack *nfct;
266 #ifdef CONFIG_NETFILTER_DEBUG
267 unsigned int nf_debug;
269 #ifdef CONFIG_BRIDGE_NETFILTER
270 struct nf_bridge_info *nf_bridge;
272 #endif /* CONFIG_NETFILTER */
273 #if defined(CONFIG_HIPPI)
278 #ifdef CONFIG_NET_SCHED
279 __u32 tc_index; /* traffic control index */
280 #ifdef CONFIG_NET_CLS_ACT
281 __u32 tc_verd; /* traffic control verdict */
282 __u32 tc_classid; /* traffic control classid */
288 /* These elements must be at the end, see alloc_skb() for details. */
289 unsigned int truesize;
299 * Handling routines are only of interest to the kernel
301 #include <linux/slab.h>
303 #include <asm/system.h>
305 extern void __kfree_skb(struct sk_buff *skb);
306 extern struct sk_buff *alloc_skb(unsigned int size, int priority);
307 extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
308 unsigned int size, int priority);
309 extern void kfree_skbmem(struct sk_buff *skb);
310 extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
311 extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
312 extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
313 extern int pskb_expand_head(struct sk_buff *skb,
314 int nhead, int ntail, int gfp_mask);
315 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
316 unsigned int headroom);
317 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
318 int newheadroom, int newtailroom,
320 extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
321 #define dev_kfree_skb(a) kfree_skb(a)
322 extern void skb_over_panic(struct sk_buff *skb, int len,
324 extern void skb_under_panic(struct sk_buff *skb, int len,
328 #define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
331 * skb_queue_empty - check if a queue is empty
334 * Returns true if the queue is empty, false otherwise.
336 static inline int skb_queue_empty(const struct sk_buff_head *list)
338 return list->next == (struct sk_buff *)list;
342 * skb_get - reference buffer
343 * @skb: buffer to reference
345 * Makes another reference to a socket buffer and returns a pointer
348 static inline struct sk_buff *skb_get(struct sk_buff *skb)
350 atomic_inc(&skb->users);
355 * If users == 1, we are the only owner and are can avoid redundant
360 * kfree_skb - free an sk_buff
361 * @skb: buffer to free
363 * Drop a reference to the buffer and free it if the usage count has
366 static inline void kfree_skb(struct sk_buff *skb)
368 if (likely(atomic_read(&skb->users) == 1))
370 else if (likely(!atomic_dec_and_test(&skb->users)))
376 * skb_cloned - is the buffer a clone
377 * @skb: buffer to check
379 * Returns true if the buffer was generated with skb_clone() and is
380 * one of multiple shared copies of the buffer. Cloned buffers are
381 * shared data so must not be written to under normal circumstances.
383 static inline int skb_cloned(const struct sk_buff *skb)
385 return skb->cloned &&
386 (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
390 * skb_header_cloned - is the header a clone
391 * @skb: buffer to check
393 * Returns true if modifying the header part of the buffer requires
394 * the data to be copied.
396 static inline int skb_header_cloned(const struct sk_buff *skb)
403 dataref = atomic_read(&skb_shinfo(skb)->dataref);
404 dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
409 * skb_header_release - release reference to header
410 * @skb: buffer to operate on
412 * Drop a reference to the header part of the buffer. This is done
413 * by acquiring a payload reference. You must not read from the header
414 * part of skb->data after this.
416 static inline void skb_header_release(struct sk_buff *skb)
420 atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
424 * skb_shared - is the buffer shared
425 * @skb: buffer to check
427 * Returns true if more than one person has a reference to this
430 static inline int skb_shared(const struct sk_buff *skb)
432 return atomic_read(&skb->users) != 1;
436 * skb_share_check - check if buffer is shared and if so clone it
437 * @skb: buffer to check
438 * @pri: priority for memory allocation
440 * If the buffer is shared the buffer is cloned and the old copy
441 * drops a reference. A new clone with a single reference is returned.
442 * If the buffer is not shared the original buffer is returned. When
443 * being called from interrupt status or with spinlocks held pri must
446 * NULL is returned on a memory allocation failure.
448 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri)
450 might_sleep_if(pri & __GFP_WAIT);
451 if (skb_shared(skb)) {
452 struct sk_buff *nskb = skb_clone(skb, pri);
460 * Copy shared buffers into a new sk_buff. We effectively do COW on
461 * packets to handle cases where we have a local reader and forward
462 * and a couple of other messy ones. The normal one is tcpdumping
463 * a packet thats being forwarded.
467 * skb_unshare - make a copy of a shared buffer
468 * @skb: buffer to check
469 * @pri: priority for memory allocation
471 * If the socket buffer is a clone then this function creates a new
472 * copy of the data, drops a reference count on the old copy and returns
473 * the new copy with the reference count at 1. If the buffer is not a clone
474 * the original buffer is returned. When called with a spinlock held or
475 * from interrupt state @pri must be %GFP_ATOMIC
477 * %NULL is returned on a memory allocation failure.
479 static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri)
481 might_sleep_if(pri & __GFP_WAIT);
482 if (skb_cloned(skb)) {
483 struct sk_buff *nskb = skb_copy(skb, pri);
484 kfree_skb(skb); /* Free our shared copy */
492 * @list_: list to peek at
494 * Peek an &sk_buff. Unlike most other operations you _MUST_
495 * be careful with this one. A peek leaves the buffer on the
496 * list and someone else may run off with it. You must hold
497 * the appropriate locks or have a private queue to do this.
499 * Returns %NULL for an empty list or a pointer to the head element.
500 * The reference count is not incremented and the reference is therefore
501 * volatile. Use with caution.
503 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
505 struct sk_buff *list = ((struct sk_buff *)list_)->next;
506 if (list == (struct sk_buff *)list_)
513 * @list_: list to peek at
515 * Peek an &sk_buff. Unlike most other operations you _MUST_
516 * be careful with this one. A peek leaves the buffer on the
517 * list and someone else may run off with it. You must hold
518 * the appropriate locks or have a private queue to do this.
520 * Returns %NULL for an empty list or a pointer to the tail element.
521 * The reference count is not incremented and the reference is therefore
522 * volatile. Use with caution.
524 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
526 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
527 if (list == (struct sk_buff *)list_)
533 * skb_queue_len - get queue length
534 * @list_: list to measure
536 * Return the length of an &sk_buff queue.
538 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
543 static inline void skb_queue_head_init(struct sk_buff_head *list)
545 spin_lock_init(&list->lock);
546 list->prev = list->next = (struct sk_buff *)list;
551 * Insert an sk_buff at the start of a list.
553 * The "__skb_xxxx()" functions are the non-atomic ones that
554 * can only be called with interrupts disabled.
558 * __skb_queue_head - queue a buffer at the list head
560 * @newsk: buffer to queue
562 * Queue a buffer at the start of a list. This function takes no locks
563 * and you must therefore hold required locks before calling it.
565 * A buffer cannot be placed on two lists at the same time.
567 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
568 static inline void __skb_queue_head(struct sk_buff_head *list,
569 struct sk_buff *newsk)
571 struct sk_buff *prev, *next;
575 prev = (struct sk_buff *)list;
579 next->prev = prev->next = newsk;
583 * __skb_queue_tail - queue a buffer at the list tail
585 * @newsk: buffer to queue
587 * Queue a buffer at the end of a list. This function takes no locks
588 * and you must therefore hold required locks before calling it.
590 * A buffer cannot be placed on two lists at the same time.
592 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
593 static inline void __skb_queue_tail(struct sk_buff_head *list,
594 struct sk_buff *newsk)
596 struct sk_buff *prev, *next;
600 next = (struct sk_buff *)list;
604 next->prev = prev->next = newsk;
609 * __skb_dequeue - remove from the head of the queue
610 * @list: list to dequeue from
612 * Remove the head of the list. This function does not take any locks
613 * so must be used with appropriate locks held only. The head item is
614 * returned or %NULL if the list is empty.
616 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
617 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
619 struct sk_buff *next, *prev, *result;
621 prev = (struct sk_buff *) list;
630 result->next = result->prev = NULL;
638 * Insert a packet on a list.
640 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk);
641 static inline void __skb_insert(struct sk_buff *newsk,
642 struct sk_buff *prev, struct sk_buff *next,
643 struct sk_buff_head *list)
647 next->prev = prev->next = newsk;
653 * Place a packet after a given packet in a list.
655 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk);
656 static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk)
658 __skb_insert(newsk, old, old->next, old->list);
662 * remove sk_buff from list. _Must_ be called atomically, and with
665 extern void skb_unlink(struct sk_buff *skb);
666 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
668 struct sk_buff *next, *prev;
673 skb->next = skb->prev = NULL;
680 /* XXX: more streamlined implementation */
683 * __skb_dequeue_tail - remove from the tail of the queue
684 * @list: list to dequeue from
686 * Remove the tail of the list. This function does not take any locks
687 * so must be used with appropriate locks held only. The tail item is
688 * returned or %NULL if the list is empty.
690 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
691 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
693 struct sk_buff *skb = skb_peek_tail(list);
695 __skb_unlink(skb, list);
700 static inline int skb_is_nonlinear(const struct sk_buff *skb)
702 return skb->data_len;
705 static inline unsigned int skb_headlen(const struct sk_buff *skb)
707 return skb->len - skb->data_len;
710 static inline int skb_pagelen(const struct sk_buff *skb)
714 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
715 len += skb_shinfo(skb)->frags[i].size;
716 return len + skb_headlen(skb);
719 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
720 struct page *page, int off, int size)
722 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
725 frag->page_offset = off;
727 skb_shinfo(skb)->nr_frags = i + 1;
730 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
731 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
732 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
735 * Add data to an sk_buff
737 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
739 unsigned char *tmp = skb->tail;
740 SKB_LINEAR_ASSERT(skb);
747 * skb_put - add data to a buffer
748 * @skb: buffer to use
749 * @len: amount of data to add
751 * This function extends the used data area of the buffer. If this would
752 * exceed the total buffer size the kernel will panic. A pointer to the
753 * first byte of the extra data is returned.
755 static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
757 unsigned char *tmp = skb->tail;
758 SKB_LINEAR_ASSERT(skb);
761 if (unlikely(skb->tail>skb->end))
762 skb_over_panic(skb, len, current_text_addr());
766 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
774 * skb_push - add data to the start of a buffer
775 * @skb: buffer to use
776 * @len: amount of data to add
778 * This function extends the used data area of the buffer at the buffer
779 * start. If this would exceed the total buffer headroom the kernel will
780 * panic. A pointer to the first byte of the extra data is returned.
782 static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
786 if (unlikely(skb->data<skb->head))
787 skb_under_panic(skb, len, current_text_addr());
791 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
794 BUG_ON(skb->len < skb->data_len);
795 return skb->data += len;
799 * skb_pull - remove data from the start of a buffer
800 * @skb: buffer to use
801 * @len: amount of data to remove
803 * This function removes data from the start of a buffer, returning
804 * the memory to the headroom. A pointer to the next data in the buffer
805 * is returned. Once the data has been pulled future pushes will overwrite
808 static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
810 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
813 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
815 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
817 if (len > skb_headlen(skb) &&
818 !__pskb_pull_tail(skb, len-skb_headlen(skb)))
821 return skb->data += len;
824 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
826 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
829 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
831 if (likely(len <= skb_headlen(skb)))
833 if (unlikely(len > skb->len))
835 return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
839 * skb_headroom - bytes at buffer head
840 * @skb: buffer to check
842 * Return the number of bytes of free space at the head of an &sk_buff.
844 static inline int skb_headroom(const struct sk_buff *skb)
846 return skb->data - skb->head;
850 * skb_tailroom - bytes at buffer end
851 * @skb: buffer to check
853 * Return the number of bytes of free space at the tail of an sk_buff
855 static inline int skb_tailroom(const struct sk_buff *skb)
857 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
861 * skb_reserve - adjust headroom
862 * @skb: buffer to alter
863 * @len: bytes to move
865 * Increase the headroom of an empty &sk_buff by reducing the tail
866 * room. This is only allowed for an empty buffer.
868 static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
875 * CPUs often take a performance hit when accessing unaligned memory
876 * locations. The actual performance hit varies, it can be small if the
877 * hardware handles it or large if we have to take an exception and fix it
880 * Since an ethernet header is 14 bytes network drivers often end up with
881 * the IP header at an unaligned offset. The IP header can be aligned by
882 * shifting the start of the packet by 2 bytes. Drivers should do this
885 * skb_reserve(NET_IP_ALIGN);
887 * The downside to this alignment of the IP header is that the DMA is now
888 * unaligned. On some architectures the cost of an unaligned DMA is high
889 * and this cost outweighs the gains made by aligning the IP header.
891 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
895 #define NET_IP_ALIGN 2
898 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
900 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
902 if (!skb->data_len) {
904 skb->tail = skb->data + len;
906 ___pskb_trim(skb, len, 0);
910 * skb_trim - remove end from a buffer
911 * @skb: buffer to alter
914 * Cut the length of a buffer down by removing data from the tail. If
915 * the buffer is already under the length specified it is not modified.
917 static inline void skb_trim(struct sk_buff *skb, unsigned int len)
920 __skb_trim(skb, len);
924 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
926 if (!skb->data_len) {
928 skb->tail = skb->data+len;
931 return ___pskb_trim(skb, len, 1);
934 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
936 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
940 * skb_orphan - orphan a buffer
941 * @skb: buffer to orphan
943 * If a buffer currently has an owner then we call the owner's
944 * destructor function and make the @skb unowned. The buffer continues
945 * to exist but is no longer charged to its former owner.
947 static inline void skb_orphan(struct sk_buff *skb)
950 skb->destructor(skb);
951 skb->destructor = NULL;
956 * __skb_queue_purge - empty a list
957 * @list: list to empty
959 * Delete all buffers on an &sk_buff list. Each buffer is removed from
960 * the list and one reference dropped. This function does not take the
961 * list lock and the caller must hold the relevant locks to use it.
963 extern void skb_queue_purge(struct sk_buff_head *list);
964 static inline void __skb_queue_purge(struct sk_buff_head *list)
967 while ((skb = __skb_dequeue(list)) != NULL)
971 #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
973 * __dev_alloc_skb - allocate an skbuff for sending
974 * @length: length to allocate
975 * @gfp_mask: get_free_pages mask, passed to alloc_skb
977 * Allocate a new &sk_buff and assign it a usage count of one. The
978 * buffer has unspecified headroom built in. Users should allocate
979 * the headroom they think they need without accounting for the
980 * built in space. The built in space is used for optimisations.
982 * %NULL is returned in there is no free memory.
984 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
987 struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
989 skb_reserve(skb, 16);
993 extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask);
997 * dev_alloc_skb - allocate an skbuff for sending
998 * @length: length to allocate
1000 * Allocate a new &sk_buff and assign it a usage count of one. The
1001 * buffer has unspecified headroom built in. Users should allocate
1002 * the headroom they think they need without accounting for the
1003 * built in space. The built in space is used for optimisations.
1005 * %NULL is returned in there is no free memory. Although this function
1006 * allocates memory it can be called from an interrupt.
1008 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1010 return __dev_alloc_skb(length, GFP_ATOMIC);
1014 * skb_cow - copy header of skb when it is required
1015 * @skb: buffer to cow
1016 * @headroom: needed headroom
1018 * If the skb passed lacks sufficient headroom or its data part
1019 * is shared, data is reallocated. If reallocation fails, an error
1020 * is returned and original skb is not changed.
1022 * The result is skb with writable area skb->head...skb->tail
1023 * and at least @headroom of space at head.
1025 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
1027 int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb);
1032 if (delta || skb_cloned(skb))
1033 return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC);
1038 * skb_padto - pad an skbuff up to a minimal size
1039 * @skb: buffer to pad
1040 * @len: minimal length
1042 * Pads up a buffer to ensure the trailing bytes exist and are
1043 * blanked. If the buffer already contains sufficient data it
1044 * is untouched. Returns the buffer, which may be a replacement
1045 * for the original, or NULL for out of memory - in which case
1046 * the original buffer is still freed.
1049 static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
1051 unsigned int size = skb->len;
1052 if (likely(size >= len))
1054 return skb_pad(skb, len-size);
1057 static inline int skb_add_data(struct sk_buff *skb,
1058 char __user *from, int copy)
1060 const int off = skb->len;
1062 if (skb->ip_summed == CHECKSUM_NONE) {
1064 unsigned int csum = csum_and_copy_from_user(from,
1068 skb->csum = csum_block_add(skb->csum, csum, off);
1071 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1074 __skb_trim(skb, off);
1078 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1079 struct page *page, int off)
1082 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1084 return page == frag->page &&
1085 off == frag->page_offset + frag->size;
1091 * skb_linearize - convert paged skb to linear one
1092 * @skb: buffer to linarize
1093 * @gfp: allocation mode
1095 * If there is no free memory -ENOMEM is returned, otherwise zero
1096 * is returned and the old skb data released.
1098 extern int __skb_linearize(struct sk_buff *skb, int gfp);
1099 static inline int skb_linearize(struct sk_buff *skb, int gfp)
1101 return __skb_linearize(skb, gfp);
1105 * skb_postpull_rcsum - update checksum for received skb after pull
1106 * @skb: buffer to update
1107 * @start: start of data before pull
1108 * @len: length of data pulled
1110 * After doing a pull on a received packet, you need to call this to
1111 * update the CHECKSUM_HW checksum, or set ip_summed to CHECKSUM_NONE
1112 * so that it can be recomputed from scratch.
1115 static inline void skb_postpull_rcsum(struct sk_buff *skb,
1116 const void *start, int len)
1118 if (skb->ip_summed == CHECKSUM_HW)
1119 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
1123 * pskb_trim_rcsum - trim received skb and update checksum
1124 * @skb: buffer to trim
1127 * This is exactly the same as pskb_trim except that it ensures the
1128 * checksum of received packets are still valid after the operation.
1131 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
1133 if (len >= skb->len)
1135 if (skb->ip_summed == CHECKSUM_HW)
1136 skb->ip_summed = CHECKSUM_NONE;
1137 return __pskb_trim(skb, len);
1140 static inline void *kmap_skb_frag(const skb_frag_t *frag)
1142 #ifdef CONFIG_HIGHMEM
1147 return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ);
1150 static inline void kunmap_skb_frag(void *vaddr)
1152 kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
1153 #ifdef CONFIG_HIGHMEM
1158 #define skb_queue_walk(queue, skb) \
1159 for (skb = (queue)->next; \
1160 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1164 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1165 int noblock, int *err);
1166 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1167 struct poll_table_struct *wait);
1168 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1169 int offset, struct iovec *to,
1171 extern int skb_copy_and_csum_datagram_iovec(const
1172 struct sk_buff *skb,
1175 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1176 extern unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1177 int len, unsigned int csum);
1178 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1180 extern int skb_store_bits(const struct sk_buff *skb, int offset,
1181 void *from, int len);
1182 extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb,
1183 int offset, u8 *to, int len,
1185 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1186 extern void skb_split(struct sk_buff *skb,
1187 struct sk_buff *skb1, const u32 len);
1189 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
1190 int len, void *buffer)
1192 int hlen = skb_headlen(skb);
1194 if (offset + len <= hlen)
1195 return skb->data + offset;
1197 if (skb_copy_bits(skb, offset, buffer, len) < 0)
1203 extern void skb_init(void);
1204 extern void skb_add_mtu(int mtu);
1206 #ifdef CONFIG_NETFILTER
1207 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
1209 if (nfct && atomic_dec_and_test(&nfct->use))
1210 nfct->destroy(nfct);
1212 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
1215 atomic_inc(&nfct->use);
1217 static inline void nf_reset(struct sk_buff *skb)
1219 nf_conntrack_put(skb->nfct);
1221 #ifdef CONFIG_NETFILTER_DEBUG
1225 static inline void nf_reset_debug(struct sk_buff *skb)
1227 #ifdef CONFIG_NETFILTER_DEBUG
1232 #ifdef CONFIG_BRIDGE_NETFILTER
1233 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1235 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1238 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1241 atomic_inc(&nf_bridge->use);
1243 #endif /* CONFIG_BRIDGE_NETFILTER */
1244 #else /* CONFIG_NETFILTER */
1245 static inline void nf_reset(struct sk_buff *skb) {}
1246 #endif /* CONFIG_NETFILTER */
1248 #endif /* __KERNEL__ */
1249 #endif /* _LINUX_SKBUFF_H */