2 * Routines having to do with the 'struct sk_buff' memory handlers.
4 * Authors: Alan Cox <iiitac@pyr.swan.ac.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
7 * Version: $Id: skbuff.c,v 1.90 2001/11/07 05:56:19 davem Exp $
10 * Alan Cox : Fixed the worst of the load
12 * Dave Platt : Interrupt stacking fix.
13 * Richard Kooijman : Timestamp fixes.
14 * Alan Cox : Changed buffer format.
15 * Alan Cox : destructor hook for AF_UNIX etc.
16 * Linus Torvalds : Better skb_clone.
17 * Alan Cox : Added skb_copy.
18 * Alan Cox : Added all the changed routines Linus
19 * only put in the headers
20 * Ray VanTassle : Fixed --skb->lock in free
21 * Alan Cox : skb_copy copy arp field
22 * Andi Kleen : slabified it.
23 * Robert Olsson : Removed skb_head_pool
26 * The __skb_ routines should be called with interrupts
27 * disabled, or you better be *real* sure that the operation is atomic
28 * with respect to whatever list is being frobbed (e.g. via lock_sock()
29 * or via disabling bottom half handlers, etc).
31 * This program is free software; you can redistribute it and/or
32 * modify it under the terms of the GNU General Public License
33 * as published by the Free Software Foundation; either version
34 * 2 of the License, or (at your option) any later version.
38 * The functions in this file will not compile correctly with gcc 2.4.x
41 #include <linux/config.h>
42 #include <linux/module.h>
43 #include <linux/types.h>
44 #include <linux/kernel.h>
45 #include <linux/sched.h>
47 #include <linux/interrupt.h>
49 #include <linux/inet.h>
50 #include <linux/slab.h>
51 #include <linux/netdevice.h>
52 #ifdef CONFIG_NET_CLS_ACT
53 #include <net/pkt_sched.h>
55 #include <linux/string.h>
56 #include <linux/skbuff.h>
57 #include <linux/cache.h>
58 #include <linux/rtnetlink.h>
59 #include <linux/init.h>
60 #include <linux/highmem.h>
62 #include <net/protocol.h>
65 #include <net/checksum.h>
68 #include <asm/uaccess.h>
69 #include <asm/system.h>
71 static kmem_cache_t *skbuff_head_cache __read_mostly;
72 static kmem_cache_t *skbuff_fclone_cache __read_mostly;
75 * Keep out-of-line to prevent kernel bloat.
76 * __builtin_return_address is not used because it is not always
81 * skb_over_panic - private function
86 * Out of line support code for skb_put(). Not user callable.
88 void skb_over_panic(struct sk_buff *skb, int sz, void *here)
90 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
91 "data:%p tail:%p end:%p dev:%s\n",
92 here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
93 skb->dev ? skb->dev->name : "<NULL>");
98 * skb_under_panic - private function
103 * Out of line support code for skb_push(). Not user callable.
106 void skb_under_panic(struct sk_buff *skb, int sz, void *here)
108 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
109 "data:%p tail:%p end:%p dev:%s\n",
110 here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
111 skb->dev ? skb->dev->name : "<NULL>");
115 void skb_truesize_bug(struct sk_buff *skb)
117 printk(KERN_ERR "SKB BUG: Invalid truesize (%u) "
118 "len=%u, sizeof(sk_buff)=%Zd\n",
119 skb->truesize, skb->len, sizeof(struct sk_buff));
121 EXPORT_SYMBOL(skb_truesize_bug);
123 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
124 * 'private' fields and also do memory statistics to find all the
130 * __alloc_skb - allocate a network buffer
131 * @size: size to allocate
132 * @gfp_mask: allocation mask
133 * @fclone: allocate from fclone cache instead of head cache
134 * and allocate a cloned (child) skb
136 * Allocate a new &sk_buff. The returned buffer has no headroom and a
137 * tail room of size bytes. The object has a reference count of one.
138 * The return is the buffer. On a failure the return is %NULL.
140 * Buffers may only be allocated from interrupts using a @gfp_mask of
143 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
147 struct skb_shared_info *shinfo;
151 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
154 skb = kmem_cache_alloc(cache, gfp_mask & ~__GFP_DMA);
158 /* Get the DATA. Size must match skb_add_mtu(). */
159 size = SKB_DATA_ALIGN(size);
160 data = ____kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
164 memset(skb, 0, offsetof(struct sk_buff, truesize));
165 skb->truesize = size + sizeof(struct sk_buff);
166 atomic_set(&skb->users, 1);
170 skb->end = data + size;
171 /* make sure we initialize shinfo sequentially */
172 shinfo = skb_shinfo(skb);
173 atomic_set(&shinfo->dataref, 1);
174 shinfo->nr_frags = 0;
175 shinfo->gso_size = 0;
176 shinfo->gso_segs = 0;
177 shinfo->gso_type = 0;
178 shinfo->ip6_frag_id = 0;
179 shinfo->frag_list = NULL;
182 struct sk_buff *child = skb + 1;
183 atomic_t *fclone_ref = (atomic_t *) (child + 1);
185 skb->fclone = SKB_FCLONE_ORIG;
186 atomic_set(fclone_ref, 1);
188 child->fclone = SKB_FCLONE_UNAVAILABLE;
193 kmem_cache_free(cache, skb);
199 * alloc_skb_from_cache - allocate a network buffer
200 * @cp: kmem_cache from which to allocate the data area
201 * (object size must be big enough for @size bytes + skb overheads)
202 * @size: size to allocate
203 * @gfp_mask: allocation mask
205 * Allocate a new &sk_buff. The returned buffer has no headroom and
206 * tail room of size bytes. The object has a reference count of one.
207 * The return is the buffer. On a failure the return is %NULL.
209 * Buffers may only be allocated from interrupts using a @gfp_mask of
212 struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
220 skb = kmem_cache_alloc(skbuff_head_cache,
221 gfp_mask & ~__GFP_DMA);
226 size = SKB_DATA_ALIGN(size);
227 data = kmem_cache_alloc(cp, gfp_mask);
231 memset(skb, 0, offsetof(struct sk_buff, truesize));
232 skb->truesize = size + sizeof(struct sk_buff);
233 atomic_set(&skb->users, 1);
237 skb->end = data + size;
239 atomic_set(&(skb_shinfo(skb)->dataref), 1);
240 skb_shinfo(skb)->nr_frags = 0;
241 skb_shinfo(skb)->gso_size = 0;
242 skb_shinfo(skb)->gso_segs = 0;
243 skb_shinfo(skb)->gso_type = 0;
244 skb_shinfo(skb)->frag_list = NULL;
248 kmem_cache_free(skbuff_head_cache, skb);
254 static void skb_drop_fraglist(struct sk_buff *skb)
256 struct sk_buff *list = skb_shinfo(skb)->frag_list;
258 skb_shinfo(skb)->frag_list = NULL;
261 struct sk_buff *this = list;
267 static void skb_clone_fraglist(struct sk_buff *skb)
269 struct sk_buff *list;
271 for (list = skb_shinfo(skb)->frag_list; list; list = list->next)
275 static void skb_release_data(struct sk_buff *skb)
278 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
279 &skb_shinfo(skb)->dataref)) {
280 if (skb_shinfo(skb)->nr_frags) {
282 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
283 put_page(skb_shinfo(skb)->frags[i].page);
286 if (skb_shinfo(skb)->frag_list)
287 skb_drop_fraglist(skb);
294 * Free an skbuff by memory without cleaning the state.
296 void kfree_skbmem(struct sk_buff *skb)
298 struct sk_buff *other;
299 atomic_t *fclone_ref;
301 skb_release_data(skb);
302 switch (skb->fclone) {
303 case SKB_FCLONE_UNAVAILABLE:
304 kmem_cache_free(skbuff_head_cache, skb);
307 case SKB_FCLONE_ORIG:
308 fclone_ref = (atomic_t *) (skb + 2);
309 if (atomic_dec_and_test(fclone_ref))
310 kmem_cache_free(skbuff_fclone_cache, skb);
313 case SKB_FCLONE_CLONE:
314 fclone_ref = (atomic_t *) (skb + 1);
317 /* The clone portion is available for
318 * fast-cloning again.
320 skb->fclone = SKB_FCLONE_UNAVAILABLE;
322 if (atomic_dec_and_test(fclone_ref))
323 kmem_cache_free(skbuff_fclone_cache, other);
329 * __kfree_skb - private function
332 * Free an sk_buff. Release anything attached to the buffer.
333 * Clean the state. This is an internal helper function. Users should
334 * always call kfree_skb
337 void __kfree_skb(struct sk_buff *skb)
339 dst_release(skb->dst);
341 secpath_put(skb->sp);
343 if (skb->destructor) {
345 skb->destructor(skb);
347 #ifdef CONFIG_NETFILTER
348 nf_conntrack_put(skb->nfct);
349 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
350 nf_conntrack_put_reasm(skb->nfct_reasm);
352 #ifdef CONFIG_BRIDGE_NETFILTER
353 nf_bridge_put(skb->nf_bridge);
356 /* XXX: IS this still necessary? - JHS */
357 #ifdef CONFIG_NET_SCHED
359 #ifdef CONFIG_NET_CLS_ACT
368 * kfree_skb - free an sk_buff
369 * @skb: buffer to free
371 * Drop a reference to the buffer and free it if the usage count has
374 void kfree_skb(struct sk_buff *skb)
378 if (likely(atomic_read(&skb->users) == 1))
380 else if (likely(!atomic_dec_and_test(&skb->users)))
386 * skb_clone - duplicate an sk_buff
387 * @skb: buffer to clone
388 * @gfp_mask: allocation priority
390 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
391 * copies share the same packet data but not structure. The new
392 * buffer has a reference count of 1. If the allocation fails the
393 * function returns %NULL otherwise the new buffer is returned.
395 * If this function is called from an interrupt gfp_mask() must be
399 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
404 if (skb->fclone == SKB_FCLONE_ORIG &&
405 n->fclone == SKB_FCLONE_UNAVAILABLE) {
406 atomic_t *fclone_ref = (atomic_t *) (n + 1);
407 n->fclone = SKB_FCLONE_CLONE;
408 atomic_inc(fclone_ref);
410 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
413 n->fclone = SKB_FCLONE_UNAVAILABLE;
416 #define C(x) n->x = skb->x
418 n->next = n->prev = NULL;
429 secpath_get(skb->sp);
431 memcpy(n->cb, skb->cb, sizeof(skb->cb));
441 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
445 n->destructor = NULL;
446 #ifdef CONFIG_NETFILTER
449 nf_conntrack_get(skb->nfct);
451 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
453 nf_conntrack_get_reasm(skb->nfct_reasm);
455 #ifdef CONFIG_BRIDGE_NETFILTER
457 nf_bridge_get(skb->nf_bridge);
459 #endif /*CONFIG_NETFILTER*/
460 #ifdef CONFIG_NET_SCHED
462 #ifdef CONFIG_NET_CLS_ACT
463 n->tc_verd = SET_TC_VERD(skb->tc_verd,0);
464 n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd);
465 n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
468 skb_copy_secmark(n, skb);
471 atomic_set(&n->users, 1);
477 atomic_inc(&(skb_shinfo(skb)->dataref));
483 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
486 * Shift between the two data areas in bytes
488 unsigned long offset = new->data - old->data;
492 new->priority = old->priority;
493 new->protocol = old->protocol;
494 new->dst = dst_clone(old->dst);
496 new->sp = secpath_get(old->sp);
498 new->h.raw = old->h.raw + offset;
499 new->nh.raw = old->nh.raw + offset;
500 new->mac.raw = old->mac.raw + offset;
501 memcpy(new->cb, old->cb, sizeof(old->cb));
502 new->local_df = old->local_df;
503 new->fclone = SKB_FCLONE_UNAVAILABLE;
504 new->pkt_type = old->pkt_type;
505 new->tstamp = old->tstamp;
506 new->destructor = NULL;
507 #ifdef CONFIG_NETFILTER
508 new->nfmark = old->nfmark;
509 new->nfct = old->nfct;
510 nf_conntrack_get(old->nfct);
511 new->nfctinfo = old->nfctinfo;
512 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
513 new->nfct_reasm = old->nfct_reasm;
514 nf_conntrack_get_reasm(old->nfct_reasm);
516 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
517 new->ipvs_property = old->ipvs_property;
519 #ifdef CONFIG_BRIDGE_NETFILTER
520 new->nf_bridge = old->nf_bridge;
521 nf_bridge_get(old->nf_bridge);
524 #ifdef CONFIG_NET_SCHED
525 #ifdef CONFIG_NET_CLS_ACT
526 new->tc_verd = old->tc_verd;
528 new->tc_index = old->tc_index;
530 skb_copy_secmark(new, old);
531 atomic_set(&new->users, 1);
532 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
533 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
534 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
538 * skb_copy - create private copy of an sk_buff
539 * @skb: buffer to copy
540 * @gfp_mask: allocation priority
542 * Make a copy of both an &sk_buff and its data. This is used when the
543 * caller wishes to modify the data and needs a private copy of the
544 * data to alter. Returns %NULL on failure or the pointer to the buffer
545 * on success. The returned buffer has a reference count of 1.
547 * As by-product this function converts non-linear &sk_buff to linear
548 * one, so that &sk_buff becomes completely private and caller is allowed
549 * to modify all the data of returned buffer. This means that this
550 * function is not recommended for use in circumstances when only
551 * header is going to be modified. Use pskb_copy() instead.
554 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
556 int headerlen = skb->data - skb->head;
558 * Allocate the copy buffer
560 struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len,
565 /* Set the data pointer */
566 skb_reserve(n, headerlen);
567 /* Set the tail pointer and length */
568 skb_put(n, skb->len);
570 n->ip_summed = skb->ip_summed;
572 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
575 copy_skb_header(n, skb);
581 * pskb_copy - create copy of an sk_buff with private head.
582 * @skb: buffer to copy
583 * @gfp_mask: allocation priority
585 * Make a copy of both an &sk_buff and part of its data, located
586 * in header. Fragmented data remain shared. This is used when
587 * the caller wishes to modify only header of &sk_buff and needs
588 * private copy of the header to alter. Returns %NULL on failure
589 * or the pointer to the buffer on success.
590 * The returned buffer has a reference count of 1.
593 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
596 * Allocate the copy buffer
598 struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask);
603 /* Set the data pointer */
604 skb_reserve(n, skb->data - skb->head);
605 /* Set the tail pointer and length */
606 skb_put(n, skb_headlen(skb));
608 memcpy(n->data, skb->data, n->len);
610 n->ip_summed = skb->ip_summed;
612 n->data_len = skb->data_len;
615 if (skb_shinfo(skb)->nr_frags) {
618 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
619 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
620 get_page(skb_shinfo(n)->frags[i].page);
622 skb_shinfo(n)->nr_frags = i;
625 if (skb_shinfo(skb)->frag_list) {
626 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
627 skb_clone_fraglist(n);
630 copy_skb_header(n, skb);
636 * pskb_expand_head - reallocate header of &sk_buff
637 * @skb: buffer to reallocate
638 * @nhead: room to add at head
639 * @ntail: room to add at tail
640 * @gfp_mask: allocation priority
642 * Expands (or creates identical copy, if &nhead and &ntail are zero)
643 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
644 * reference count of 1. Returns zero in the case of success or error,
645 * if expansion failed. In the last case, &sk_buff is not changed.
647 * All the pointers pointing into skb header may change and must be
648 * reloaded after call to this function.
651 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
656 int size = nhead + (skb->end - skb->head) + ntail;
662 size = SKB_DATA_ALIGN(size);
664 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
668 /* Copy only real data... and, alas, header. This should be
669 * optimized for the cases when header is void. */
670 memcpy(data + nhead, skb->head, skb->tail - skb->head);
671 memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
673 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
674 get_page(skb_shinfo(skb)->frags[i].page);
676 if (skb_shinfo(skb)->frag_list)
677 skb_clone_fraglist(skb);
679 skb_release_data(skb);
681 off = (data + nhead) - skb->head;
684 skb->end = data + size;
692 atomic_set(&skb_shinfo(skb)->dataref, 1);
699 /* Make private copy of skb with writable head and some headroom */
701 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
703 struct sk_buff *skb2;
704 int delta = headroom - skb_headroom(skb);
707 skb2 = pskb_copy(skb, GFP_ATOMIC);
709 skb2 = skb_clone(skb, GFP_ATOMIC);
710 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
721 * skb_copy_expand - copy and expand sk_buff
722 * @skb: buffer to copy
723 * @newheadroom: new free bytes at head
724 * @newtailroom: new free bytes at tail
725 * @gfp_mask: allocation priority
727 * Make a copy of both an &sk_buff and its data and while doing so
728 * allocate additional space.
730 * This is used when the caller wishes to modify the data and needs a
731 * private copy of the data to alter as well as more space for new fields.
732 * Returns %NULL on failure or the pointer to the buffer
733 * on success. The returned buffer has a reference count of 1.
735 * You must pass %GFP_ATOMIC as the allocation priority if this function
736 * is called from an interrupt.
738 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used
739 * only by netfilter in the cases when checksum is recalculated? --ANK
741 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
742 int newheadroom, int newtailroom,
746 * Allocate the copy buffer
748 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
750 int head_copy_len, head_copy_off;
755 skb_reserve(n, newheadroom);
757 /* Set the tail pointer and length */
758 skb_put(n, skb->len);
760 head_copy_len = skb_headroom(skb);
762 if (newheadroom <= head_copy_len)
763 head_copy_len = newheadroom;
765 head_copy_off = newheadroom - head_copy_len;
767 /* Copy the linear header and data. */
768 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
769 skb->len + head_copy_len))
772 copy_skb_header(n, skb);
778 * skb_pad - zero pad the tail of an skb
779 * @skb: buffer to pad
782 * Ensure that a buffer is followed by a padding area that is zero
783 * filled. Used by network drivers which may DMA or transfer data
784 * beyond the buffer end onto the wire.
786 * May return error in out of memory cases. The skb is freed on error.
789 int skb_pad(struct sk_buff *skb, int pad)
794 /* If the skbuff is non linear tailroom is always zero.. */
795 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
796 memset(skb->data+skb->len, 0, pad);
800 ntail = skb->data_len + pad - (skb->end - skb->tail);
801 if (likely(skb_cloned(skb) || ntail > 0)) {
802 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
807 /* FIXME: The use of this function with non-linear skb's really needs
810 err = skb_linearize(skb);
814 memset(skb->data + skb->len, 0, pad);
822 /* Trims skb to length len. It can change skb pointers.
825 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
827 int offset = skb_headlen(skb);
828 int nfrags = skb_shinfo(skb)->nr_frags;
831 for (i = 0; i < nfrags; i++) {
832 int end = offset + skb_shinfo(skb)->frags[i].size;
834 if (skb_cloned(skb)) {
835 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
839 put_page(skb_shinfo(skb)->frags[i].page);
840 skb_shinfo(skb)->nr_frags--;
842 skb_shinfo(skb)->frags[i].size = len - offset;
849 skb->data_len -= skb->len - len;
852 if (len <= skb_headlen(skb)) {
855 skb->tail = skb->data + len;
856 if (skb_shinfo(skb)->frag_list && !skb_cloned(skb))
857 skb_drop_fraglist(skb);
859 skb->data_len -= skb->len - len;
868 * __pskb_pull_tail - advance tail of skb header
869 * @skb: buffer to reallocate
870 * @delta: number of bytes to advance tail
872 * The function makes a sense only on a fragmented &sk_buff,
873 * it expands header moving its tail forward and copying necessary
874 * data from fragmented part.
876 * &sk_buff MUST have reference count of 1.
878 * Returns %NULL (and &sk_buff does not change) if pull failed
879 * or value of new tail of skb in the case of success.
881 * All the pointers pointing into skb header may change and must be
882 * reloaded after call to this function.
885 /* Moves tail of skb head forward, copying data from fragmented part,
886 * when it is necessary.
887 * 1. It may fail due to malloc failure.
888 * 2. It may change skb pointers.
890 * It is pretty complicated. Luckily, it is called only in exceptional cases.
892 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
894 /* If skb has not enough free space at tail, get new one
895 * plus 128 bytes for future expansions. If we have enough
896 * room at tail, reallocate without expansion only if skb is cloned.
898 int i, k, eat = (skb->tail + delta) - skb->end;
900 if (eat > 0 || skb_cloned(skb)) {
901 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
906 if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
909 /* Optimization: no fragments, no reasons to preestimate
910 * size of pulled pages. Superb.
912 if (!skb_shinfo(skb)->frag_list)
915 /* Estimate size of pulled pages. */
917 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
918 if (skb_shinfo(skb)->frags[i].size >= eat)
920 eat -= skb_shinfo(skb)->frags[i].size;
923 /* If we need update frag list, we are in troubles.
924 * Certainly, it possible to add an offset to skb data,
925 * but taking into account that pulling is expected to
926 * be very rare operation, it is worth to fight against
927 * further bloating skb head and crucify ourselves here instead.
928 * Pure masohism, indeed. 8)8)
931 struct sk_buff *list = skb_shinfo(skb)->frag_list;
932 struct sk_buff *clone = NULL;
933 struct sk_buff *insp = NULL;
938 if (list->len <= eat) {
939 /* Eaten as whole. */
944 /* Eaten partially. */
946 if (skb_shared(list)) {
947 /* Sucks! We need to fork list. :-( */
948 clone = skb_clone(list, GFP_ATOMIC);
954 /* This may be pulled without
958 if (!pskb_pull(list, eat)) {
967 /* Free pulled out fragments. */
968 while ((list = skb_shinfo(skb)->frag_list) != insp) {
969 skb_shinfo(skb)->frag_list = list->next;
972 /* And insert new clone at head. */
975 skb_shinfo(skb)->frag_list = clone;
978 /* Success! Now we may commit changes to skb data. */
983 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
984 if (skb_shinfo(skb)->frags[i].size <= eat) {
985 put_page(skb_shinfo(skb)->frags[i].page);
986 eat -= skb_shinfo(skb)->frags[i].size;
988 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
990 skb_shinfo(skb)->frags[k].page_offset += eat;
991 skb_shinfo(skb)->frags[k].size -= eat;
997 skb_shinfo(skb)->nr_frags = k;
1000 skb->data_len -= delta;
1005 /* Copy some data bits from skb to kernel buffer. */
1007 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1010 int start = skb_headlen(skb);
1012 if (offset > (int)skb->len - len)
1016 if ((copy = start - offset) > 0) {
1019 memcpy(to, skb->data + offset, copy);
1020 if ((len -= copy) == 0)
1026 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1029 BUG_TRAP(start <= offset + len);
1031 end = start + skb_shinfo(skb)->frags[i].size;
1032 if ((copy = end - offset) > 0) {
1038 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1040 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1041 offset - start, copy);
1042 kunmap_skb_frag(vaddr);
1044 if ((len -= copy) == 0)
1052 if (skb_shinfo(skb)->frag_list) {
1053 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1055 for (; list; list = list->next) {
1058 BUG_TRAP(start <= offset + len);
1060 end = start + list->len;
1061 if ((copy = end - offset) > 0) {
1064 if (skb_copy_bits(list, offset - start,
1067 if ((len -= copy) == 0)
1083 * skb_store_bits - store bits from kernel buffer to skb
1084 * @skb: destination buffer
1085 * @offset: offset in destination
1086 * @from: source buffer
1087 * @len: number of bytes to copy
1089 * Copy the specified number of bytes from the source buffer to the
1090 * destination skb. This function handles all the messy bits of
1091 * traversing fragment lists and such.
1094 int skb_store_bits(const struct sk_buff *skb, int offset, void *from, int len)
1097 int start = skb_headlen(skb);
1099 if (offset > (int)skb->len - len)
1102 if ((copy = start - offset) > 0) {
1105 memcpy(skb->data + offset, from, copy);
1106 if ((len -= copy) == 0)
1112 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1113 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1116 BUG_TRAP(start <= offset + len);
1118 end = start + frag->size;
1119 if ((copy = end - offset) > 0) {
1125 vaddr = kmap_skb_frag(frag);
1126 memcpy(vaddr + frag->page_offset + offset - start,
1128 kunmap_skb_frag(vaddr);
1130 if ((len -= copy) == 0)
1138 if (skb_shinfo(skb)->frag_list) {
1139 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1141 for (; list; list = list->next) {
1144 BUG_TRAP(start <= offset + len);
1146 end = start + list->len;
1147 if ((copy = end - offset) > 0) {
1150 if (skb_store_bits(list, offset - start,
1153 if ((len -= copy) == 0)
1168 EXPORT_SYMBOL(skb_store_bits);
1170 /* Checksum skb data. */
1172 unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1173 int len, unsigned int csum)
1175 int start = skb_headlen(skb);
1176 int i, copy = start - offset;
1179 /* Checksum header. */
1183 csum = csum_partial(skb->data + offset, copy, csum);
1184 if ((len -= copy) == 0)
1190 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1193 BUG_TRAP(start <= offset + len);
1195 end = start + skb_shinfo(skb)->frags[i].size;
1196 if ((copy = end - offset) > 0) {
1199 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1203 vaddr = kmap_skb_frag(frag);
1204 csum2 = csum_partial(vaddr + frag->page_offset +
1205 offset - start, copy, 0);
1206 kunmap_skb_frag(vaddr);
1207 csum = csum_block_add(csum, csum2, pos);
1216 if (skb_shinfo(skb)->frag_list) {
1217 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1219 for (; list; list = list->next) {
1222 BUG_TRAP(start <= offset + len);
1224 end = start + list->len;
1225 if ((copy = end - offset) > 0) {
1229 csum2 = skb_checksum(list, offset - start,
1231 csum = csum_block_add(csum, csum2, pos);
1232 if ((len -= copy) == 0)
1245 /* Both of above in one bottle. */
1247 unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1248 u8 *to, int len, unsigned int csum)
1250 int start = skb_headlen(skb);
1251 int i, copy = start - offset;
1258 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1260 if ((len -= copy) == 0)
1267 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1270 BUG_TRAP(start <= offset + len);
1272 end = start + skb_shinfo(skb)->frags[i].size;
1273 if ((copy = end - offset) > 0) {
1276 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1280 vaddr = kmap_skb_frag(frag);
1281 csum2 = csum_partial_copy_nocheck(vaddr +
1285 kunmap_skb_frag(vaddr);
1286 csum = csum_block_add(csum, csum2, pos);
1296 if (skb_shinfo(skb)->frag_list) {
1297 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1299 for (; list; list = list->next) {
1303 BUG_TRAP(start <= offset + len);
1305 end = start + list->len;
1306 if ((copy = end - offset) > 0) {
1309 csum2 = skb_copy_and_csum_bits(list,
1312 csum = csum_block_add(csum, csum2, pos);
1313 if ((len -= copy) == 0)
1326 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1331 if (skb->ip_summed == CHECKSUM_HW)
1332 csstart = skb->h.raw - skb->data;
1334 csstart = skb_headlen(skb);
1336 BUG_ON(csstart > skb_headlen(skb));
1338 memcpy(to, skb->data, csstart);
1341 if (csstart != skb->len)
1342 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1343 skb->len - csstart, 0);
1345 if (skb->ip_summed == CHECKSUM_HW) {
1346 long csstuff = csstart + skb->csum;
1348 *((unsigned short *)(to + csstuff)) = csum_fold(csum);
1353 * skb_dequeue - remove from the head of the queue
1354 * @list: list to dequeue from
1356 * Remove the head of the list. The list lock is taken so the function
1357 * may be used safely with other locking list functions. The head item is
1358 * returned or %NULL if the list is empty.
1361 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1363 unsigned long flags;
1364 struct sk_buff *result;
1366 spin_lock_irqsave(&list->lock, flags);
1367 result = __skb_dequeue(list);
1368 spin_unlock_irqrestore(&list->lock, flags);
1373 * skb_dequeue_tail - remove from the tail of the queue
1374 * @list: list to dequeue from
1376 * Remove the tail of the list. The list lock is taken so the function
1377 * may be used safely with other locking list functions. The tail item is
1378 * returned or %NULL if the list is empty.
1380 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1382 unsigned long flags;
1383 struct sk_buff *result;
1385 spin_lock_irqsave(&list->lock, flags);
1386 result = __skb_dequeue_tail(list);
1387 spin_unlock_irqrestore(&list->lock, flags);
1392 * skb_queue_purge - empty a list
1393 * @list: list to empty
1395 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1396 * the list and one reference dropped. This function takes the list
1397 * lock and is atomic with respect to other list locking functions.
1399 void skb_queue_purge(struct sk_buff_head *list)
1401 struct sk_buff *skb;
1402 while ((skb = skb_dequeue(list)) != NULL)
1407 * skb_queue_head - queue a buffer at the list head
1408 * @list: list to use
1409 * @newsk: buffer to queue
1411 * Queue a buffer at the start of the list. This function takes the
1412 * list lock and can be used safely with other locking &sk_buff functions
1415 * A buffer cannot be placed on two lists at the same time.
1417 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
1419 unsigned long flags;
1421 spin_lock_irqsave(&list->lock, flags);
1422 __skb_queue_head(list, newsk);
1423 spin_unlock_irqrestore(&list->lock, flags);
1427 * skb_queue_tail - queue a buffer at the list tail
1428 * @list: list to use
1429 * @newsk: buffer to queue
1431 * Queue a buffer at the tail of the list. This function takes the
1432 * list lock and can be used safely with other locking &sk_buff functions
1435 * A buffer cannot be placed on two lists at the same time.
1437 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
1439 unsigned long flags;
1441 spin_lock_irqsave(&list->lock, flags);
1442 __skb_queue_tail(list, newsk);
1443 spin_unlock_irqrestore(&list->lock, flags);
1447 * skb_unlink - remove a buffer from a list
1448 * @skb: buffer to remove
1449 * @list: list to use
1451 * Remove a packet from a list. The list locks are taken and this
1452 * function is atomic with respect to other list locked calls
1454 * You must know what list the SKB is on.
1456 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1458 unsigned long flags;
1460 spin_lock_irqsave(&list->lock, flags);
1461 __skb_unlink(skb, list);
1462 spin_unlock_irqrestore(&list->lock, flags);
1466 * skb_append - append a buffer
1467 * @old: buffer to insert after
1468 * @newsk: buffer to insert
1469 * @list: list to use
1471 * Place a packet after a given packet in a list. The list locks are taken
1472 * and this function is atomic with respect to other list locked calls.
1473 * A buffer cannot be placed on two lists at the same time.
1475 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1477 unsigned long flags;
1479 spin_lock_irqsave(&list->lock, flags);
1480 __skb_append(old, newsk, list);
1481 spin_unlock_irqrestore(&list->lock, flags);
1486 * skb_insert - insert a buffer
1487 * @old: buffer to insert before
1488 * @newsk: buffer to insert
1489 * @list: list to use
1491 * Place a packet before a given packet in a list. The list locks are
1492 * taken and this function is atomic with respect to other list locked
1495 * A buffer cannot be placed on two lists at the same time.
1497 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1499 unsigned long flags;
1501 spin_lock_irqsave(&list->lock, flags);
1502 __skb_insert(newsk, old->prev, old, list);
1503 spin_unlock_irqrestore(&list->lock, flags);
1508 * Tune the memory allocator for a new MTU size.
1510 void skb_add_mtu(int mtu)
1512 /* Must match allocation in alloc_skb */
1513 mtu = SKB_DATA_ALIGN(mtu) + sizeof(struct skb_shared_info);
1515 kmem_add_cache_size(mtu);
1519 static inline void skb_split_inside_header(struct sk_buff *skb,
1520 struct sk_buff* skb1,
1521 const u32 len, const int pos)
1525 memcpy(skb_put(skb1, pos - len), skb->data + len, pos - len);
1527 /* And move data appendix as is. */
1528 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1529 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
1531 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
1532 skb_shinfo(skb)->nr_frags = 0;
1533 skb1->data_len = skb->data_len;
1534 skb1->len += skb1->data_len;
1537 skb->tail = skb->data + len;
1540 static inline void skb_split_no_header(struct sk_buff *skb,
1541 struct sk_buff* skb1,
1542 const u32 len, int pos)
1545 const int nfrags = skb_shinfo(skb)->nr_frags;
1547 skb_shinfo(skb)->nr_frags = 0;
1548 skb1->len = skb1->data_len = skb->len - len;
1550 skb->data_len = len - pos;
1552 for (i = 0; i < nfrags; i++) {
1553 int size = skb_shinfo(skb)->frags[i].size;
1555 if (pos + size > len) {
1556 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
1560 * We have two variants in this case:
1561 * 1. Move all the frag to the second
1562 * part, if it is possible. F.e.
1563 * this approach is mandatory for TUX,
1564 * where splitting is expensive.
1565 * 2. Split is accurately. We make this.
1567 get_page(skb_shinfo(skb)->frags[i].page);
1568 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
1569 skb_shinfo(skb1)->frags[0].size -= len - pos;
1570 skb_shinfo(skb)->frags[i].size = len - pos;
1571 skb_shinfo(skb)->nr_frags++;
1575 skb_shinfo(skb)->nr_frags++;
1578 skb_shinfo(skb1)->nr_frags = k;
1582 * skb_split - Split fragmented skb to two parts at length len.
1583 * @skb: the buffer to split
1584 * @skb1: the buffer to receive the second part
1585 * @len: new length for skb
1587 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
1589 int pos = skb_headlen(skb);
1591 if (len < pos) /* Split line is inside header. */
1592 skb_split_inside_header(skb, skb1, len, pos);
1593 else /* Second chunk has no header, nothing to copy. */
1594 skb_split_no_header(skb, skb1, len, pos);
1598 * skb_prepare_seq_read - Prepare a sequential read of skb data
1599 * @skb: the buffer to read
1600 * @from: lower offset of data to be read
1601 * @to: upper offset of data to be read
1602 * @st: state variable
1604 * Initializes the specified state variable. Must be called before
1605 * invoking skb_seq_read() for the first time.
1607 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1608 unsigned int to, struct skb_seq_state *st)
1610 st->lower_offset = from;
1611 st->upper_offset = to;
1612 st->root_skb = st->cur_skb = skb;
1613 st->frag_idx = st->stepped_offset = 0;
1614 st->frag_data = NULL;
1618 * skb_seq_read - Sequentially read skb data
1619 * @consumed: number of bytes consumed by the caller so far
1620 * @data: destination pointer for data to be returned
1621 * @st: state variable
1623 * Reads a block of skb data at &consumed relative to the
1624 * lower offset specified to skb_prepare_seq_read(). Assigns
1625 * the head of the data block to &data and returns the length
1626 * of the block or 0 if the end of the skb data or the upper
1627 * offset has been reached.
1629 * The caller is not required to consume all of the data
1630 * returned, i.e. &consumed is typically set to the number
1631 * of bytes already consumed and the next call to
1632 * skb_seq_read() will return the remaining part of the block.
1634 * Note: The size of each block of data returned can be arbitary,
1635 * this limitation is the cost for zerocopy seqeuental
1636 * reads of potentially non linear data.
1638 * Note: Fragment lists within fragments are not implemented
1639 * at the moment, state->root_skb could be replaced with
1640 * a stack for this purpose.
1642 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1643 struct skb_seq_state *st)
1645 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
1648 if (unlikely(abs_offset >= st->upper_offset))
1652 block_limit = skb_headlen(st->cur_skb);
1654 if (abs_offset < block_limit) {
1655 *data = st->cur_skb->data + abs_offset;
1656 return block_limit - abs_offset;
1659 if (st->frag_idx == 0 && !st->frag_data)
1660 st->stepped_offset += skb_headlen(st->cur_skb);
1662 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
1663 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
1664 block_limit = frag->size + st->stepped_offset;
1666 if (abs_offset < block_limit) {
1668 st->frag_data = kmap_skb_frag(frag);
1670 *data = (u8 *) st->frag_data + frag->page_offset +
1671 (abs_offset - st->stepped_offset);
1673 return block_limit - abs_offset;
1676 if (st->frag_data) {
1677 kunmap_skb_frag(st->frag_data);
1678 st->frag_data = NULL;
1682 st->stepped_offset += frag->size;
1685 if (st->cur_skb->next) {
1686 st->cur_skb = st->cur_skb->next;
1689 } else if (st->root_skb == st->cur_skb &&
1690 skb_shinfo(st->root_skb)->frag_list) {
1691 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
1699 * skb_abort_seq_read - Abort a sequential read of skb data
1700 * @st: state variable
1702 * Must be called if skb_seq_read() was not called until it
1705 void skb_abort_seq_read(struct skb_seq_state *st)
1708 kunmap_skb_frag(st->frag_data);
1711 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
1713 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
1714 struct ts_config *conf,
1715 struct ts_state *state)
1717 return skb_seq_read(offset, text, TS_SKB_CB(state));
1720 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
1722 skb_abort_seq_read(TS_SKB_CB(state));
1726 * skb_find_text - Find a text pattern in skb data
1727 * @skb: the buffer to look in
1728 * @from: search offset
1730 * @config: textsearch configuration
1731 * @state: uninitialized textsearch state variable
1733 * Finds a pattern in the skb data according to the specified
1734 * textsearch configuration. Use textsearch_next() to retrieve
1735 * subsequent occurrences of the pattern. Returns the offset
1736 * to the first occurrence or UINT_MAX if no match was found.
1738 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1739 unsigned int to, struct ts_config *config,
1740 struct ts_state *state)
1744 config->get_next_block = skb_ts_get_next_block;
1745 config->finish = skb_ts_finish;
1747 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
1749 ret = textsearch_find(config, state);
1750 return (ret <= to - from ? ret : UINT_MAX);
1754 * skb_append_datato_frags: - append the user data to a skb
1755 * @sk: sock structure
1756 * @skb: skb structure to be appened with user data.
1757 * @getfrag: call back function to be used for getting the user data
1758 * @from: pointer to user message iov
1759 * @length: length of the iov message
1761 * Description: This procedure append the user data in the fragment part
1762 * of the skb if any page alloc fails user this procedure returns -ENOMEM
1764 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1765 int (*getfrag)(void *from, char *to, int offset,
1766 int len, int odd, struct sk_buff *skb),
1767 void *from, int length)
1770 skb_frag_t *frag = NULL;
1771 struct page *page = NULL;
1777 /* Return error if we don't have space for new frag */
1778 frg_cnt = skb_shinfo(skb)->nr_frags;
1779 if (frg_cnt >= MAX_SKB_FRAGS)
1782 /* allocate a new page for next frag */
1783 page = alloc_pages(sk->sk_allocation, 0);
1785 /* If alloc_page fails just return failure and caller will
1786 * free previous allocated pages by doing kfree_skb()
1791 /* initialize the next frag */
1792 sk->sk_sndmsg_page = page;
1793 sk->sk_sndmsg_off = 0;
1794 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
1795 skb->truesize += PAGE_SIZE;
1796 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1798 /* get the new initialized frag */
1799 frg_cnt = skb_shinfo(skb)->nr_frags;
1800 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
1802 /* copy the user data to page */
1803 left = PAGE_SIZE - frag->page_offset;
1804 copy = (length > left)? left : length;
1806 ret = getfrag(from, (page_address(frag->page) +
1807 frag->page_offset + frag->size),
1808 offset, copy, 0, skb);
1812 /* copy was successful so update the size parameters */
1813 sk->sk_sndmsg_off += copy;
1816 skb->data_len += copy;
1820 } while (length > 0);
1826 * skb_pull_rcsum - pull skb and update receive checksum
1827 * @skb: buffer to update
1828 * @start: start of data before pull
1829 * @len: length of data pulled
1831 * This function performs an skb_pull on the packet and updates
1832 * update the CHECKSUM_HW checksum. It should be used on receive
1833 * path processing instead of skb_pull unless you know that the
1834 * checksum difference is zero (e.g., a valid IP header) or you
1835 * are setting ip_summed to CHECKSUM_NONE.
1837 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
1839 BUG_ON(len > skb->len);
1841 BUG_ON(skb->len < skb->data_len);
1842 skb_postpull_rcsum(skb, skb->data, len);
1843 return skb->data += len;
1846 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
1849 * skb_segment - Perform protocol segmentation on skb.
1850 * @skb: buffer to segment
1851 * @features: features for the output path (see dev->features)
1853 * This function performs segmentation on the given skb. It returns
1854 * the segment at the given position. It returns NULL if there are
1855 * no more segments to generate, or when an error is encountered.
1857 struct sk_buff *skb_segment(struct sk_buff *skb, int features)
1859 struct sk_buff *segs = NULL;
1860 struct sk_buff *tail = NULL;
1861 unsigned int mss = skb_shinfo(skb)->gso_size;
1862 unsigned int doffset = skb->data - skb->mac.raw;
1863 unsigned int offset = doffset;
1864 unsigned int headroom;
1866 int sg = features & NETIF_F_SG;
1867 int nfrags = skb_shinfo(skb)->nr_frags;
1872 __skb_push(skb, doffset);
1873 headroom = skb_headroom(skb);
1874 pos = skb_headlen(skb);
1877 struct sk_buff *nskb;
1883 len = skb->len - offset;
1887 hsize = skb_headlen(skb) - offset;
1890 nsize = hsize + doffset;
1891 if (nsize > len + doffset || !sg)
1892 nsize = len + doffset;
1894 nskb = alloc_skb(nsize + headroom, GFP_ATOMIC);
1895 if (unlikely(!nskb))
1904 nskb->dev = skb->dev;
1905 nskb->priority = skb->priority;
1906 nskb->protocol = skb->protocol;
1907 nskb->dst = dst_clone(skb->dst);
1908 memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
1909 nskb->pkt_type = skb->pkt_type;
1910 nskb->mac_len = skb->mac_len;
1912 skb_reserve(nskb, headroom);
1913 nskb->mac.raw = nskb->data;
1914 nskb->nh.raw = nskb->data + skb->mac_len;
1915 nskb->h.raw = nskb->nh.raw + (skb->h.raw - skb->nh.raw);
1916 memcpy(skb_put(nskb, doffset), skb->data, doffset);
1919 nskb->csum = skb_copy_and_csum_bits(skb, offset,
1925 frag = skb_shinfo(nskb)->frags;
1928 nskb->ip_summed = CHECKSUM_HW;
1929 nskb->csum = skb->csum;
1930 memcpy(skb_put(nskb, hsize), skb->data + offset, hsize);
1932 while (pos < offset + len) {
1933 BUG_ON(i >= nfrags);
1935 *frag = skb_shinfo(skb)->frags[i];
1936 get_page(frag->page);
1940 frag->page_offset += offset - pos;
1941 frag->size -= offset - pos;
1946 if (pos + size <= offset + len) {
1950 frag->size -= pos + size - (offset + len);
1957 skb_shinfo(nskb)->nr_frags = k;
1958 nskb->data_len = len - hsize;
1959 nskb->len += nskb->data_len;
1960 nskb->truesize += nskb->data_len;
1961 } while ((offset += len) < skb->len);
1966 while ((skb = segs)) {
1970 return ERR_PTR(err);
1973 EXPORT_SYMBOL_GPL(skb_segment);
1975 void __init skb_init(void)
1977 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
1978 sizeof(struct sk_buff),
1982 if (!skbuff_head_cache)
1983 panic("cannot create skbuff cache");
1985 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
1986 (2*sizeof(struct sk_buff)) +
1991 if (!skbuff_fclone_cache)
1992 panic("cannot create skbuff cache");
1995 EXPORT_SYMBOL(___pskb_trim);
1996 EXPORT_SYMBOL(__kfree_skb);
1997 EXPORT_SYMBOL(kfree_skb);
1998 EXPORT_SYMBOL(__pskb_pull_tail);
1999 EXPORT_SYMBOL(__alloc_skb);
2000 EXPORT_SYMBOL(pskb_copy);
2001 EXPORT_SYMBOL(pskb_expand_head);
2002 EXPORT_SYMBOL(skb_checksum);
2003 EXPORT_SYMBOL(skb_clone);
2004 EXPORT_SYMBOL(skb_clone_fraglist);
2005 EXPORT_SYMBOL(skb_copy);
2006 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2007 EXPORT_SYMBOL(skb_copy_and_csum_dev);
2008 EXPORT_SYMBOL(skb_copy_bits);
2009 EXPORT_SYMBOL(skb_copy_expand);
2010 EXPORT_SYMBOL(skb_over_panic);
2011 EXPORT_SYMBOL(skb_pad);
2012 EXPORT_SYMBOL(skb_realloc_headroom);
2013 EXPORT_SYMBOL(skb_under_panic);
2014 EXPORT_SYMBOL(skb_dequeue);
2015 EXPORT_SYMBOL(skb_dequeue_tail);
2016 EXPORT_SYMBOL(skb_insert);
2017 EXPORT_SYMBOL(skb_queue_purge);
2018 EXPORT_SYMBOL(skb_queue_head);
2019 EXPORT_SYMBOL(skb_queue_tail);
2020 EXPORT_SYMBOL(skb_unlink);
2021 EXPORT_SYMBOL(skb_append);
2022 EXPORT_SYMBOL(skb_split);
2023 EXPORT_SYMBOL(skb_prepare_seq_read);
2024 EXPORT_SYMBOL(skb_seq_read);
2025 EXPORT_SYMBOL(skb_abort_seq_read);
2026 EXPORT_SYMBOL(skb_find_text);
2027 EXPORT_SYMBOL(skb_append_datato_frags);