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/module.h>
42 #include <linux/types.h>
43 #include <linux/kernel.h>
44 #include <linux/sched.h>
46 #include <linux/interrupt.h>
48 #include <linux/inet.h>
49 #include <linux/slab.h>
50 #include <linux/netdevice.h>
51 #ifdef CONFIG_NET_CLS_ACT
52 #include <net/pkt_sched.h>
54 #include <linux/string.h>
55 #include <linux/skbuff.h>
56 #include <linux/cache.h>
57 #include <linux/rtnetlink.h>
58 #include <linux/init.h>
59 #include <linux/highmem.h>
61 #include <net/protocol.h>
64 #include <net/checksum.h>
67 #include <asm/uaccess.h>
68 #include <asm/system.h>
70 static kmem_cache_t *skbuff_head_cache __read_mostly;
71 static kmem_cache_t *skbuff_fclone_cache __read_mostly;
74 * lockdep: lock class key used by skb_queue_head_init():
76 struct lock_class_key skb_queue_lock_key;
78 EXPORT_SYMBOL(skb_queue_lock_key);
81 * Keep out-of-line to prevent kernel bloat.
82 * __builtin_return_address is not used because it is not always
87 * skb_over_panic - private function
92 * Out of line support code for skb_put(). Not user callable.
94 void skb_over_panic(struct sk_buff *skb, int sz, void *here)
96 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
97 "data:%p tail:%p end:%p dev:%s\n",
98 here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
99 skb->dev ? skb->dev->name : "<NULL>");
104 * skb_under_panic - private function
109 * Out of line support code for skb_push(). Not user callable.
112 void skb_under_panic(struct sk_buff *skb, int sz, void *here)
114 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
115 "data:%p tail:%p end:%p dev:%s\n",
116 here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
117 skb->dev ? skb->dev->name : "<NULL>");
121 void skb_truesize_bug(struct sk_buff *skb)
123 printk(KERN_ERR "SKB BUG: Invalid truesize (%u) "
124 "len=%u, sizeof(sk_buff)=%Zd\n",
125 skb->truesize, skb->len, sizeof(struct sk_buff));
127 EXPORT_SYMBOL(skb_truesize_bug);
129 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
130 * 'private' fields and also do memory statistics to find all the
136 * __alloc_skb - allocate a network buffer
137 * @size: size to allocate
138 * @gfp_mask: allocation mask
139 * @fclone: allocate from fclone cache instead of head cache
140 * and allocate a cloned (child) skb
142 * Allocate a new &sk_buff. The returned buffer has no headroom and a
143 * tail room of size bytes. The object has a reference count of one.
144 * The return is the buffer. On a failure the return is %NULL.
146 * Buffers may only be allocated from interrupts using a @gfp_mask of
149 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
153 struct skb_shared_info *shinfo;
157 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
160 skb = kmem_cache_alloc(cache, gfp_mask & ~__GFP_DMA);
164 /* Get the DATA. Size must match skb_add_mtu(). */
165 size = SKB_DATA_ALIGN(size);
166 data = ____kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
170 memset(skb, 0, offsetof(struct sk_buff, truesize));
171 skb->truesize = size + sizeof(struct sk_buff);
172 atomic_set(&skb->users, 1);
176 skb->end = data + size;
177 /* make sure we initialize shinfo sequentially */
178 shinfo = skb_shinfo(skb);
179 atomic_set(&shinfo->dataref, 1);
180 shinfo->nr_frags = 0;
181 shinfo->gso_size = 0;
182 shinfo->gso_segs = 0;
183 shinfo->gso_type = 0;
184 shinfo->ip6_frag_id = 0;
185 shinfo->frag_list = NULL;
188 struct sk_buff *child = skb + 1;
189 atomic_t *fclone_ref = (atomic_t *) (child + 1);
191 skb->fclone = SKB_FCLONE_ORIG;
192 atomic_set(fclone_ref, 1);
194 child->fclone = SKB_FCLONE_UNAVAILABLE;
199 kmem_cache_free(cache, skb);
205 * alloc_skb_from_cache - allocate a network buffer
206 * @cp: kmem_cache from which to allocate the data area
207 * (object size must be big enough for @size bytes + skb overheads)
208 * @size: size to allocate
209 * @gfp_mask: allocation mask
211 * Allocate a new &sk_buff. The returned buffer has no headroom and
212 * tail room of size bytes. The object has a reference count of one.
213 * The return is the buffer. On a failure the return is %NULL.
215 * Buffers may only be allocated from interrupts using a @gfp_mask of
218 struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
226 skb = kmem_cache_alloc(skbuff_head_cache,
227 gfp_mask & ~__GFP_DMA);
232 size = SKB_DATA_ALIGN(size);
233 data = kmem_cache_alloc(cp, gfp_mask);
237 memset(skb, 0, offsetof(struct sk_buff, truesize));
238 skb->truesize = size + sizeof(struct sk_buff);
239 atomic_set(&skb->users, 1);
243 skb->end = data + size;
245 atomic_set(&(skb_shinfo(skb)->dataref), 1);
246 skb_shinfo(skb)->nr_frags = 0;
247 skb_shinfo(skb)->gso_size = 0;
248 skb_shinfo(skb)->gso_segs = 0;
249 skb_shinfo(skb)->gso_type = 0;
250 skb_shinfo(skb)->frag_list = NULL;
254 kmem_cache_free(skbuff_head_cache, skb);
260 static void skb_drop_list(struct sk_buff **listp)
262 struct sk_buff *list = *listp;
267 struct sk_buff *this = list;
273 static inline void skb_drop_fraglist(struct sk_buff *skb)
275 skb_drop_list(&skb_shinfo(skb)->frag_list);
278 static void skb_clone_fraglist(struct sk_buff *skb)
280 struct sk_buff *list;
282 for (list = skb_shinfo(skb)->frag_list; list; list = list->next)
286 static void skb_release_data(struct sk_buff *skb)
289 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
290 &skb_shinfo(skb)->dataref)) {
291 if (skb_shinfo(skb)->nr_frags) {
293 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
294 put_page(skb_shinfo(skb)->frags[i].page);
297 if (skb_shinfo(skb)->frag_list)
298 skb_drop_fraglist(skb);
305 * Free an skbuff by memory without cleaning the state.
307 void kfree_skbmem(struct sk_buff *skb)
309 struct sk_buff *other;
310 atomic_t *fclone_ref;
312 skb_release_data(skb);
313 switch (skb->fclone) {
314 case SKB_FCLONE_UNAVAILABLE:
315 kmem_cache_free(skbuff_head_cache, skb);
318 case SKB_FCLONE_ORIG:
319 fclone_ref = (atomic_t *) (skb + 2);
320 if (atomic_dec_and_test(fclone_ref))
321 kmem_cache_free(skbuff_fclone_cache, skb);
324 case SKB_FCLONE_CLONE:
325 fclone_ref = (atomic_t *) (skb + 1);
328 /* The clone portion is available for
329 * fast-cloning again.
331 skb->fclone = SKB_FCLONE_UNAVAILABLE;
333 if (atomic_dec_and_test(fclone_ref))
334 kmem_cache_free(skbuff_fclone_cache, other);
340 * __kfree_skb - private function
343 * Free an sk_buff. Release anything attached to the buffer.
344 * Clean the state. This is an internal helper function. Users should
345 * always call kfree_skb
348 void __kfree_skb(struct sk_buff *skb)
350 dst_release(skb->dst);
352 secpath_put(skb->sp);
354 if (skb->destructor) {
356 skb->destructor(skb);
358 #ifdef CONFIG_NETFILTER
359 nf_conntrack_put(skb->nfct);
360 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
361 nf_conntrack_put_reasm(skb->nfct_reasm);
363 #ifdef CONFIG_BRIDGE_NETFILTER
364 nf_bridge_put(skb->nf_bridge);
367 /* XXX: IS this still necessary? - JHS */
368 #ifdef CONFIG_NET_SCHED
370 #ifdef CONFIG_NET_CLS_ACT
379 * kfree_skb - free an sk_buff
380 * @skb: buffer to free
382 * Drop a reference to the buffer and free it if the usage count has
385 void kfree_skb(struct sk_buff *skb)
389 if (likely(atomic_read(&skb->users) == 1))
391 else if (likely(!atomic_dec_and_test(&skb->users)))
397 * skb_clone - duplicate an sk_buff
398 * @skb: buffer to clone
399 * @gfp_mask: allocation priority
401 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
402 * copies share the same packet data but not structure. The new
403 * buffer has a reference count of 1. If the allocation fails the
404 * function returns %NULL otherwise the new buffer is returned.
406 * If this function is called from an interrupt gfp_mask() must be
410 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
415 if (skb->fclone == SKB_FCLONE_ORIG &&
416 n->fclone == SKB_FCLONE_UNAVAILABLE) {
417 atomic_t *fclone_ref = (atomic_t *) (n + 1);
418 n->fclone = SKB_FCLONE_CLONE;
419 atomic_inc(fclone_ref);
421 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
424 n->fclone = SKB_FCLONE_UNAVAILABLE;
427 #define C(x) n->x = skb->x
429 n->next = n->prev = NULL;
440 secpath_get(skb->sp);
442 memcpy(n->cb, skb->cb, sizeof(skb->cb));
452 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
456 n->destructor = NULL;
457 #ifdef CONFIG_NETFILTER
460 nf_conntrack_get(skb->nfct);
462 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
464 nf_conntrack_get_reasm(skb->nfct_reasm);
466 #ifdef CONFIG_BRIDGE_NETFILTER
468 nf_bridge_get(skb->nf_bridge);
470 #endif /*CONFIG_NETFILTER*/
471 #ifdef CONFIG_NET_SCHED
473 #ifdef CONFIG_NET_CLS_ACT
474 n->tc_verd = SET_TC_VERD(skb->tc_verd,0);
475 n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd);
476 n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
479 skb_copy_secmark(n, skb);
482 atomic_set(&n->users, 1);
488 atomic_inc(&(skb_shinfo(skb)->dataref));
494 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
497 * Shift between the two data areas in bytes
499 unsigned long offset = new->data - old->data;
503 new->priority = old->priority;
504 new->protocol = old->protocol;
505 new->dst = dst_clone(old->dst);
507 new->sp = secpath_get(old->sp);
509 new->h.raw = old->h.raw + offset;
510 new->nh.raw = old->nh.raw + offset;
511 new->mac.raw = old->mac.raw + offset;
512 memcpy(new->cb, old->cb, sizeof(old->cb));
513 new->local_df = old->local_df;
514 new->fclone = SKB_FCLONE_UNAVAILABLE;
515 new->pkt_type = old->pkt_type;
516 new->tstamp = old->tstamp;
517 new->destructor = NULL;
518 #ifdef CONFIG_NETFILTER
519 new->nfmark = old->nfmark;
520 new->nfct = old->nfct;
521 nf_conntrack_get(old->nfct);
522 new->nfctinfo = old->nfctinfo;
523 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
524 new->nfct_reasm = old->nfct_reasm;
525 nf_conntrack_get_reasm(old->nfct_reasm);
527 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
528 new->ipvs_property = old->ipvs_property;
530 #ifdef CONFIG_BRIDGE_NETFILTER
531 new->nf_bridge = old->nf_bridge;
532 nf_bridge_get(old->nf_bridge);
535 #ifdef CONFIG_NET_SCHED
536 #ifdef CONFIG_NET_CLS_ACT
537 new->tc_verd = old->tc_verd;
539 new->tc_index = old->tc_index;
541 skb_copy_secmark(new, old);
542 atomic_set(&new->users, 1);
543 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
544 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
545 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
549 * skb_copy - create private copy of an sk_buff
550 * @skb: buffer to copy
551 * @gfp_mask: allocation priority
553 * Make a copy of both an &sk_buff and its data. This is used when the
554 * caller wishes to modify the data and needs a private copy of the
555 * data to alter. Returns %NULL on failure or the pointer to the buffer
556 * on success. The returned buffer has a reference count of 1.
558 * As by-product this function converts non-linear &sk_buff to linear
559 * one, so that &sk_buff becomes completely private and caller is allowed
560 * to modify all the data of returned buffer. This means that this
561 * function is not recommended for use in circumstances when only
562 * header is going to be modified. Use pskb_copy() instead.
565 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
567 int headerlen = skb->data - skb->head;
569 * Allocate the copy buffer
571 struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len,
576 /* Set the data pointer */
577 skb_reserve(n, headerlen);
578 /* Set the tail pointer and length */
579 skb_put(n, skb->len);
581 n->ip_summed = skb->ip_summed;
583 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
586 copy_skb_header(n, skb);
592 * pskb_copy - create copy of an sk_buff with private head.
593 * @skb: buffer to copy
594 * @gfp_mask: allocation priority
596 * Make a copy of both an &sk_buff and part of its data, located
597 * in header. Fragmented data remain shared. This is used when
598 * the caller wishes to modify only header of &sk_buff and needs
599 * private copy of the header to alter. Returns %NULL on failure
600 * or the pointer to the buffer on success.
601 * The returned buffer has a reference count of 1.
604 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
607 * Allocate the copy buffer
609 struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask);
614 /* Set the data pointer */
615 skb_reserve(n, skb->data - skb->head);
616 /* Set the tail pointer and length */
617 skb_put(n, skb_headlen(skb));
619 memcpy(n->data, skb->data, n->len);
621 n->ip_summed = skb->ip_summed;
623 n->data_len = skb->data_len;
626 if (skb_shinfo(skb)->nr_frags) {
629 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
630 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
631 get_page(skb_shinfo(n)->frags[i].page);
633 skb_shinfo(n)->nr_frags = i;
636 if (skb_shinfo(skb)->frag_list) {
637 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
638 skb_clone_fraglist(n);
641 copy_skb_header(n, skb);
647 * pskb_expand_head - reallocate header of &sk_buff
648 * @skb: buffer to reallocate
649 * @nhead: room to add at head
650 * @ntail: room to add at tail
651 * @gfp_mask: allocation priority
653 * Expands (or creates identical copy, if &nhead and &ntail are zero)
654 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
655 * reference count of 1. Returns zero in the case of success or error,
656 * if expansion failed. In the last case, &sk_buff is not changed.
658 * All the pointers pointing into skb header may change and must be
659 * reloaded after call to this function.
662 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
667 int size = nhead + (skb->end - skb->head) + ntail;
673 size = SKB_DATA_ALIGN(size);
675 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
679 /* Copy only real data... and, alas, header. This should be
680 * optimized for the cases when header is void. */
681 memcpy(data + nhead, skb->head, skb->tail - skb->head);
682 memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
684 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
685 get_page(skb_shinfo(skb)->frags[i].page);
687 if (skb_shinfo(skb)->frag_list)
688 skb_clone_fraglist(skb);
690 skb_release_data(skb);
692 off = (data + nhead) - skb->head;
695 skb->end = data + size;
703 atomic_set(&skb_shinfo(skb)->dataref, 1);
710 /* Make private copy of skb with writable head and some headroom */
712 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
714 struct sk_buff *skb2;
715 int delta = headroom - skb_headroom(skb);
718 skb2 = pskb_copy(skb, GFP_ATOMIC);
720 skb2 = skb_clone(skb, GFP_ATOMIC);
721 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
732 * skb_copy_expand - copy and expand sk_buff
733 * @skb: buffer to copy
734 * @newheadroom: new free bytes at head
735 * @newtailroom: new free bytes at tail
736 * @gfp_mask: allocation priority
738 * Make a copy of both an &sk_buff and its data and while doing so
739 * allocate additional space.
741 * This is used when the caller wishes to modify the data and needs a
742 * private copy of the data to alter as well as more space for new fields.
743 * Returns %NULL on failure or the pointer to the buffer
744 * on success. The returned buffer has a reference count of 1.
746 * You must pass %GFP_ATOMIC as the allocation priority if this function
747 * is called from an interrupt.
749 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used
750 * only by netfilter in the cases when checksum is recalculated? --ANK
752 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
753 int newheadroom, int newtailroom,
757 * Allocate the copy buffer
759 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
761 int head_copy_len, head_copy_off;
766 skb_reserve(n, newheadroom);
768 /* Set the tail pointer and length */
769 skb_put(n, skb->len);
771 head_copy_len = skb_headroom(skb);
773 if (newheadroom <= head_copy_len)
774 head_copy_len = newheadroom;
776 head_copy_off = newheadroom - head_copy_len;
778 /* Copy the linear header and data. */
779 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
780 skb->len + head_copy_len))
783 copy_skb_header(n, skb);
789 * skb_pad - zero pad the tail of an skb
790 * @skb: buffer to pad
793 * Ensure that a buffer is followed by a padding area that is zero
794 * filled. Used by network drivers which may DMA or transfer data
795 * beyond the buffer end onto the wire.
797 * May return error in out of memory cases. The skb is freed on error.
800 int skb_pad(struct sk_buff *skb, int pad)
805 /* If the skbuff is non linear tailroom is always zero.. */
806 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
807 memset(skb->data+skb->len, 0, pad);
811 ntail = skb->data_len + pad - (skb->end - skb->tail);
812 if (likely(skb_cloned(skb) || ntail > 0)) {
813 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
818 /* FIXME: The use of this function with non-linear skb's really needs
821 err = skb_linearize(skb);
825 memset(skb->data + skb->len, 0, pad);
833 /* Trims skb to length len. It can change skb pointers.
836 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
838 struct sk_buff **fragp;
839 struct sk_buff *frag;
840 int offset = skb_headlen(skb);
841 int nfrags = skb_shinfo(skb)->nr_frags;
845 if (skb_cloned(skb) &&
846 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
849 for (i = 0; i < nfrags; i++) {
850 int end = offset + skb_shinfo(skb)->frags[i].size;
858 skb_shinfo(skb)->frags[i++].size = len - offset;
860 skb_shinfo(skb)->nr_frags = i;
862 for (; i < nfrags; i++)
863 put_page(skb_shinfo(skb)->frags[i].page);
865 if (skb_shinfo(skb)->frag_list)
866 skb_drop_fraglist(skb);
870 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
871 fragp = &frag->next) {
872 int end = offset + frag->len;
874 if (skb_shared(frag)) {
875 struct sk_buff *nfrag;
877 nfrag = skb_clone(frag, GFP_ATOMIC);
878 if (unlikely(!nfrag))
881 nfrag->next = frag->next;
892 unlikely((err = pskb_trim(frag, len - offset))))
896 skb_drop_list(&frag->next);
900 if (len > skb_headlen(skb)) {
901 skb->data_len -= skb->len - len;
906 skb->tail = skb->data + len;
913 * __pskb_pull_tail - advance tail of skb header
914 * @skb: buffer to reallocate
915 * @delta: number of bytes to advance tail
917 * The function makes a sense only on a fragmented &sk_buff,
918 * it expands header moving its tail forward and copying necessary
919 * data from fragmented part.
921 * &sk_buff MUST have reference count of 1.
923 * Returns %NULL (and &sk_buff does not change) if pull failed
924 * or value of new tail of skb in the case of success.
926 * All the pointers pointing into skb header may change and must be
927 * reloaded after call to this function.
930 /* Moves tail of skb head forward, copying data from fragmented part,
931 * when it is necessary.
932 * 1. It may fail due to malloc failure.
933 * 2. It may change skb pointers.
935 * It is pretty complicated. Luckily, it is called only in exceptional cases.
937 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
939 /* If skb has not enough free space at tail, get new one
940 * plus 128 bytes for future expansions. If we have enough
941 * room at tail, reallocate without expansion only if skb is cloned.
943 int i, k, eat = (skb->tail + delta) - skb->end;
945 if (eat > 0 || skb_cloned(skb)) {
946 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
951 if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
954 /* Optimization: no fragments, no reasons to preestimate
955 * size of pulled pages. Superb.
957 if (!skb_shinfo(skb)->frag_list)
960 /* Estimate size of pulled pages. */
962 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
963 if (skb_shinfo(skb)->frags[i].size >= eat)
965 eat -= skb_shinfo(skb)->frags[i].size;
968 /* If we need update frag list, we are in troubles.
969 * Certainly, it possible to add an offset to skb data,
970 * but taking into account that pulling is expected to
971 * be very rare operation, it is worth to fight against
972 * further bloating skb head and crucify ourselves here instead.
973 * Pure masohism, indeed. 8)8)
976 struct sk_buff *list = skb_shinfo(skb)->frag_list;
977 struct sk_buff *clone = NULL;
978 struct sk_buff *insp = NULL;
983 if (list->len <= eat) {
984 /* Eaten as whole. */
989 /* Eaten partially. */
991 if (skb_shared(list)) {
992 /* Sucks! We need to fork list. :-( */
993 clone = skb_clone(list, GFP_ATOMIC);
999 /* This may be pulled without
1003 if (!pskb_pull(list, eat)) {
1012 /* Free pulled out fragments. */
1013 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1014 skb_shinfo(skb)->frag_list = list->next;
1017 /* And insert new clone at head. */
1020 skb_shinfo(skb)->frag_list = clone;
1023 /* Success! Now we may commit changes to skb data. */
1028 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1029 if (skb_shinfo(skb)->frags[i].size <= eat) {
1030 put_page(skb_shinfo(skb)->frags[i].page);
1031 eat -= skb_shinfo(skb)->frags[i].size;
1033 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1035 skb_shinfo(skb)->frags[k].page_offset += eat;
1036 skb_shinfo(skb)->frags[k].size -= eat;
1042 skb_shinfo(skb)->nr_frags = k;
1045 skb->data_len -= delta;
1050 /* Copy some data bits from skb to kernel buffer. */
1052 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1055 int start = skb_headlen(skb);
1057 if (offset > (int)skb->len - len)
1061 if ((copy = start - offset) > 0) {
1064 memcpy(to, skb->data + offset, copy);
1065 if ((len -= copy) == 0)
1071 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1074 BUG_TRAP(start <= offset + len);
1076 end = start + skb_shinfo(skb)->frags[i].size;
1077 if ((copy = end - offset) > 0) {
1083 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1085 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1086 offset - start, copy);
1087 kunmap_skb_frag(vaddr);
1089 if ((len -= copy) == 0)
1097 if (skb_shinfo(skb)->frag_list) {
1098 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1100 for (; list; list = list->next) {
1103 BUG_TRAP(start <= offset + len);
1105 end = start + list->len;
1106 if ((copy = end - offset) > 0) {
1109 if (skb_copy_bits(list, offset - start,
1112 if ((len -= copy) == 0)
1128 * skb_store_bits - store bits from kernel buffer to skb
1129 * @skb: destination buffer
1130 * @offset: offset in destination
1131 * @from: source buffer
1132 * @len: number of bytes to copy
1134 * Copy the specified number of bytes from the source buffer to the
1135 * destination skb. This function handles all the messy bits of
1136 * traversing fragment lists and such.
1139 int skb_store_bits(const struct sk_buff *skb, int offset, void *from, int len)
1142 int start = skb_headlen(skb);
1144 if (offset > (int)skb->len - len)
1147 if ((copy = start - offset) > 0) {
1150 memcpy(skb->data + offset, from, copy);
1151 if ((len -= copy) == 0)
1157 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1158 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1161 BUG_TRAP(start <= offset + len);
1163 end = start + frag->size;
1164 if ((copy = end - offset) > 0) {
1170 vaddr = kmap_skb_frag(frag);
1171 memcpy(vaddr + frag->page_offset + offset - start,
1173 kunmap_skb_frag(vaddr);
1175 if ((len -= copy) == 0)
1183 if (skb_shinfo(skb)->frag_list) {
1184 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1186 for (; list; list = list->next) {
1189 BUG_TRAP(start <= offset + len);
1191 end = start + list->len;
1192 if ((copy = end - offset) > 0) {
1195 if (skb_store_bits(list, offset - start,
1198 if ((len -= copy) == 0)
1213 EXPORT_SYMBOL(skb_store_bits);
1215 /* Checksum skb data. */
1217 unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1218 int len, unsigned int csum)
1220 int start = skb_headlen(skb);
1221 int i, copy = start - offset;
1224 /* Checksum header. */
1228 csum = csum_partial(skb->data + offset, copy, csum);
1229 if ((len -= copy) == 0)
1235 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1238 BUG_TRAP(start <= offset + len);
1240 end = start + skb_shinfo(skb)->frags[i].size;
1241 if ((copy = end - offset) > 0) {
1244 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1248 vaddr = kmap_skb_frag(frag);
1249 csum2 = csum_partial(vaddr + frag->page_offset +
1250 offset - start, copy, 0);
1251 kunmap_skb_frag(vaddr);
1252 csum = csum_block_add(csum, csum2, pos);
1261 if (skb_shinfo(skb)->frag_list) {
1262 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1264 for (; list; list = list->next) {
1267 BUG_TRAP(start <= offset + len);
1269 end = start + list->len;
1270 if ((copy = end - offset) > 0) {
1274 csum2 = skb_checksum(list, offset - start,
1276 csum = csum_block_add(csum, csum2, pos);
1277 if ((len -= copy) == 0)
1290 /* Both of above in one bottle. */
1292 unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1293 u8 *to, int len, unsigned int csum)
1295 int start = skb_headlen(skb);
1296 int i, copy = start - offset;
1303 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1305 if ((len -= copy) == 0)
1312 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1315 BUG_TRAP(start <= offset + len);
1317 end = start + skb_shinfo(skb)->frags[i].size;
1318 if ((copy = end - offset) > 0) {
1321 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1325 vaddr = kmap_skb_frag(frag);
1326 csum2 = csum_partial_copy_nocheck(vaddr +
1330 kunmap_skb_frag(vaddr);
1331 csum = csum_block_add(csum, csum2, pos);
1341 if (skb_shinfo(skb)->frag_list) {
1342 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1344 for (; list; list = list->next) {
1348 BUG_TRAP(start <= offset + len);
1350 end = start + list->len;
1351 if ((copy = end - offset) > 0) {
1354 csum2 = skb_copy_and_csum_bits(list,
1357 csum = csum_block_add(csum, csum2, pos);
1358 if ((len -= copy) == 0)
1371 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1376 if (skb->ip_summed == CHECKSUM_HW)
1377 csstart = skb->h.raw - skb->data;
1379 csstart = skb_headlen(skb);
1381 BUG_ON(csstart > skb_headlen(skb));
1383 memcpy(to, skb->data, csstart);
1386 if (csstart != skb->len)
1387 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1388 skb->len - csstart, 0);
1390 if (skb->ip_summed == CHECKSUM_HW) {
1391 long csstuff = csstart + skb->csum;
1393 *((unsigned short *)(to + csstuff)) = csum_fold(csum);
1398 * skb_dequeue - remove from the head of the queue
1399 * @list: list to dequeue from
1401 * Remove the head of the list. The list lock is taken so the function
1402 * may be used safely with other locking list functions. The head item is
1403 * returned or %NULL if the list is empty.
1406 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1408 unsigned long flags;
1409 struct sk_buff *result;
1411 spin_lock_irqsave(&list->lock, flags);
1412 result = __skb_dequeue(list);
1413 spin_unlock_irqrestore(&list->lock, flags);
1418 * skb_dequeue_tail - remove from the tail of the queue
1419 * @list: list to dequeue from
1421 * Remove the tail of the list. The list lock is taken so the function
1422 * may be used safely with other locking list functions. The tail item is
1423 * returned or %NULL if the list is empty.
1425 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1427 unsigned long flags;
1428 struct sk_buff *result;
1430 spin_lock_irqsave(&list->lock, flags);
1431 result = __skb_dequeue_tail(list);
1432 spin_unlock_irqrestore(&list->lock, flags);
1437 * skb_queue_purge - empty a list
1438 * @list: list to empty
1440 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1441 * the list and one reference dropped. This function takes the list
1442 * lock and is atomic with respect to other list locking functions.
1444 void skb_queue_purge(struct sk_buff_head *list)
1446 struct sk_buff *skb;
1447 while ((skb = skb_dequeue(list)) != NULL)
1452 * skb_queue_head - queue a buffer at the list head
1453 * @list: list to use
1454 * @newsk: buffer to queue
1456 * Queue a buffer at the start of the list. This function takes the
1457 * list lock and can be used safely with other locking &sk_buff functions
1460 * A buffer cannot be placed on two lists at the same time.
1462 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
1464 unsigned long flags;
1466 spin_lock_irqsave(&list->lock, flags);
1467 __skb_queue_head(list, newsk);
1468 spin_unlock_irqrestore(&list->lock, flags);
1472 * skb_queue_tail - queue a buffer at the list tail
1473 * @list: list to use
1474 * @newsk: buffer to queue
1476 * Queue a buffer at the tail of the list. This function takes the
1477 * list lock and can be used safely with other locking &sk_buff functions
1480 * A buffer cannot be placed on two lists at the same time.
1482 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
1484 unsigned long flags;
1486 spin_lock_irqsave(&list->lock, flags);
1487 __skb_queue_tail(list, newsk);
1488 spin_unlock_irqrestore(&list->lock, flags);
1492 * skb_unlink - remove a buffer from a list
1493 * @skb: buffer to remove
1494 * @list: list to use
1496 * Remove a packet from a list. The list locks are taken and this
1497 * function is atomic with respect to other list locked calls
1499 * You must know what list the SKB is on.
1501 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1503 unsigned long flags;
1505 spin_lock_irqsave(&list->lock, flags);
1506 __skb_unlink(skb, list);
1507 spin_unlock_irqrestore(&list->lock, flags);
1511 * skb_append - append a buffer
1512 * @old: buffer to insert after
1513 * @newsk: buffer to insert
1514 * @list: list to use
1516 * Place a packet after a given packet in a list. The list locks are taken
1517 * and this function is atomic with respect to other list locked calls.
1518 * A buffer cannot be placed on two lists at the same time.
1520 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1522 unsigned long flags;
1524 spin_lock_irqsave(&list->lock, flags);
1525 __skb_append(old, newsk, list);
1526 spin_unlock_irqrestore(&list->lock, flags);
1531 * skb_insert - insert a buffer
1532 * @old: buffer to insert before
1533 * @newsk: buffer to insert
1534 * @list: list to use
1536 * Place a packet before a given packet in a list. The list locks are
1537 * taken and this function is atomic with respect to other list locked
1540 * A buffer cannot be placed on two lists at the same time.
1542 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1544 unsigned long flags;
1546 spin_lock_irqsave(&list->lock, flags);
1547 __skb_insert(newsk, old->prev, old, list);
1548 spin_unlock_irqrestore(&list->lock, flags);
1553 * Tune the memory allocator for a new MTU size.
1555 void skb_add_mtu(int mtu)
1557 /* Must match allocation in alloc_skb */
1558 mtu = SKB_DATA_ALIGN(mtu) + sizeof(struct skb_shared_info);
1560 kmem_add_cache_size(mtu);
1564 static inline void skb_split_inside_header(struct sk_buff *skb,
1565 struct sk_buff* skb1,
1566 const u32 len, const int pos)
1570 memcpy(skb_put(skb1, pos - len), skb->data + len, pos - len);
1572 /* And move data appendix as is. */
1573 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1574 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
1576 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
1577 skb_shinfo(skb)->nr_frags = 0;
1578 skb1->data_len = skb->data_len;
1579 skb1->len += skb1->data_len;
1582 skb->tail = skb->data + len;
1585 static inline void skb_split_no_header(struct sk_buff *skb,
1586 struct sk_buff* skb1,
1587 const u32 len, int pos)
1590 const int nfrags = skb_shinfo(skb)->nr_frags;
1592 skb_shinfo(skb)->nr_frags = 0;
1593 skb1->len = skb1->data_len = skb->len - len;
1595 skb->data_len = len - pos;
1597 for (i = 0; i < nfrags; i++) {
1598 int size = skb_shinfo(skb)->frags[i].size;
1600 if (pos + size > len) {
1601 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
1605 * We have two variants in this case:
1606 * 1. Move all the frag to the second
1607 * part, if it is possible. F.e.
1608 * this approach is mandatory for TUX,
1609 * where splitting is expensive.
1610 * 2. Split is accurately. We make this.
1612 get_page(skb_shinfo(skb)->frags[i].page);
1613 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
1614 skb_shinfo(skb1)->frags[0].size -= len - pos;
1615 skb_shinfo(skb)->frags[i].size = len - pos;
1616 skb_shinfo(skb)->nr_frags++;
1620 skb_shinfo(skb)->nr_frags++;
1623 skb_shinfo(skb1)->nr_frags = k;
1627 * skb_split - Split fragmented skb to two parts at length len.
1628 * @skb: the buffer to split
1629 * @skb1: the buffer to receive the second part
1630 * @len: new length for skb
1632 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
1634 int pos = skb_headlen(skb);
1636 if (len < pos) /* Split line is inside header. */
1637 skb_split_inside_header(skb, skb1, len, pos);
1638 else /* Second chunk has no header, nothing to copy. */
1639 skb_split_no_header(skb, skb1, len, pos);
1643 * skb_prepare_seq_read - Prepare a sequential read of skb data
1644 * @skb: the buffer to read
1645 * @from: lower offset of data to be read
1646 * @to: upper offset of data to be read
1647 * @st: state variable
1649 * Initializes the specified state variable. Must be called before
1650 * invoking skb_seq_read() for the first time.
1652 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1653 unsigned int to, struct skb_seq_state *st)
1655 st->lower_offset = from;
1656 st->upper_offset = to;
1657 st->root_skb = st->cur_skb = skb;
1658 st->frag_idx = st->stepped_offset = 0;
1659 st->frag_data = NULL;
1663 * skb_seq_read - Sequentially read skb data
1664 * @consumed: number of bytes consumed by the caller so far
1665 * @data: destination pointer for data to be returned
1666 * @st: state variable
1668 * Reads a block of skb data at &consumed relative to the
1669 * lower offset specified to skb_prepare_seq_read(). Assigns
1670 * the head of the data block to &data and returns the length
1671 * of the block or 0 if the end of the skb data or the upper
1672 * offset has been reached.
1674 * The caller is not required to consume all of the data
1675 * returned, i.e. &consumed is typically set to the number
1676 * of bytes already consumed and the next call to
1677 * skb_seq_read() will return the remaining part of the block.
1679 * Note: The size of each block of data returned can be arbitary,
1680 * this limitation is the cost for zerocopy seqeuental
1681 * reads of potentially non linear data.
1683 * Note: Fragment lists within fragments are not implemented
1684 * at the moment, state->root_skb could be replaced with
1685 * a stack for this purpose.
1687 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1688 struct skb_seq_state *st)
1690 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
1693 if (unlikely(abs_offset >= st->upper_offset))
1697 block_limit = skb_headlen(st->cur_skb);
1699 if (abs_offset < block_limit) {
1700 *data = st->cur_skb->data + abs_offset;
1701 return block_limit - abs_offset;
1704 if (st->frag_idx == 0 && !st->frag_data)
1705 st->stepped_offset += skb_headlen(st->cur_skb);
1707 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
1708 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
1709 block_limit = frag->size + st->stepped_offset;
1711 if (abs_offset < block_limit) {
1713 st->frag_data = kmap_skb_frag(frag);
1715 *data = (u8 *) st->frag_data + frag->page_offset +
1716 (abs_offset - st->stepped_offset);
1718 return block_limit - abs_offset;
1721 if (st->frag_data) {
1722 kunmap_skb_frag(st->frag_data);
1723 st->frag_data = NULL;
1727 st->stepped_offset += frag->size;
1730 if (st->cur_skb->next) {
1731 st->cur_skb = st->cur_skb->next;
1734 } else if (st->root_skb == st->cur_skb &&
1735 skb_shinfo(st->root_skb)->frag_list) {
1736 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
1744 * skb_abort_seq_read - Abort a sequential read of skb data
1745 * @st: state variable
1747 * Must be called if skb_seq_read() was not called until it
1750 void skb_abort_seq_read(struct skb_seq_state *st)
1753 kunmap_skb_frag(st->frag_data);
1756 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
1758 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
1759 struct ts_config *conf,
1760 struct ts_state *state)
1762 return skb_seq_read(offset, text, TS_SKB_CB(state));
1765 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
1767 skb_abort_seq_read(TS_SKB_CB(state));
1771 * skb_find_text - Find a text pattern in skb data
1772 * @skb: the buffer to look in
1773 * @from: search offset
1775 * @config: textsearch configuration
1776 * @state: uninitialized textsearch state variable
1778 * Finds a pattern in the skb data according to the specified
1779 * textsearch configuration. Use textsearch_next() to retrieve
1780 * subsequent occurrences of the pattern. Returns the offset
1781 * to the first occurrence or UINT_MAX if no match was found.
1783 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1784 unsigned int to, struct ts_config *config,
1785 struct ts_state *state)
1789 config->get_next_block = skb_ts_get_next_block;
1790 config->finish = skb_ts_finish;
1792 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
1794 ret = textsearch_find(config, state);
1795 return (ret <= to - from ? ret : UINT_MAX);
1799 * skb_append_datato_frags: - append the user data to a skb
1800 * @sk: sock structure
1801 * @skb: skb structure to be appened with user data.
1802 * @getfrag: call back function to be used for getting the user data
1803 * @from: pointer to user message iov
1804 * @length: length of the iov message
1806 * Description: This procedure append the user data in the fragment part
1807 * of the skb if any page alloc fails user this procedure returns -ENOMEM
1809 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1810 int (*getfrag)(void *from, char *to, int offset,
1811 int len, int odd, struct sk_buff *skb),
1812 void *from, int length)
1815 skb_frag_t *frag = NULL;
1816 struct page *page = NULL;
1822 /* Return error if we don't have space for new frag */
1823 frg_cnt = skb_shinfo(skb)->nr_frags;
1824 if (frg_cnt >= MAX_SKB_FRAGS)
1827 /* allocate a new page for next frag */
1828 page = alloc_pages(sk->sk_allocation, 0);
1830 /* If alloc_page fails just return failure and caller will
1831 * free previous allocated pages by doing kfree_skb()
1836 /* initialize the next frag */
1837 sk->sk_sndmsg_page = page;
1838 sk->sk_sndmsg_off = 0;
1839 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
1840 skb->truesize += PAGE_SIZE;
1841 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1843 /* get the new initialized frag */
1844 frg_cnt = skb_shinfo(skb)->nr_frags;
1845 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
1847 /* copy the user data to page */
1848 left = PAGE_SIZE - frag->page_offset;
1849 copy = (length > left)? left : length;
1851 ret = getfrag(from, (page_address(frag->page) +
1852 frag->page_offset + frag->size),
1853 offset, copy, 0, skb);
1857 /* copy was successful so update the size parameters */
1858 sk->sk_sndmsg_off += copy;
1861 skb->data_len += copy;
1865 } while (length > 0);
1871 * skb_pull_rcsum - pull skb and update receive checksum
1872 * @skb: buffer to update
1873 * @start: start of data before pull
1874 * @len: length of data pulled
1876 * This function performs an skb_pull on the packet and updates
1877 * update the CHECKSUM_HW checksum. It should be used on receive
1878 * path processing instead of skb_pull unless you know that the
1879 * checksum difference is zero (e.g., a valid IP header) or you
1880 * are setting ip_summed to CHECKSUM_NONE.
1882 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
1884 BUG_ON(len > skb->len);
1886 BUG_ON(skb->len < skb->data_len);
1887 skb_postpull_rcsum(skb, skb->data, len);
1888 return skb->data += len;
1891 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
1894 * skb_segment - Perform protocol segmentation on skb.
1895 * @skb: buffer to segment
1896 * @features: features for the output path (see dev->features)
1898 * This function performs segmentation on the given skb. It returns
1899 * the segment at the given position. It returns NULL if there are
1900 * no more segments to generate, or when an error is encountered.
1902 struct sk_buff *skb_segment(struct sk_buff *skb, int features)
1904 struct sk_buff *segs = NULL;
1905 struct sk_buff *tail = NULL;
1906 unsigned int mss = skb_shinfo(skb)->gso_size;
1907 unsigned int doffset = skb->data - skb->mac.raw;
1908 unsigned int offset = doffset;
1909 unsigned int headroom;
1911 int sg = features & NETIF_F_SG;
1912 int nfrags = skb_shinfo(skb)->nr_frags;
1917 __skb_push(skb, doffset);
1918 headroom = skb_headroom(skb);
1919 pos = skb_headlen(skb);
1922 struct sk_buff *nskb;
1928 len = skb->len - offset;
1932 hsize = skb_headlen(skb) - offset;
1935 nsize = hsize + doffset;
1936 if (nsize > len + doffset || !sg)
1937 nsize = len + doffset;
1939 nskb = alloc_skb(nsize + headroom, GFP_ATOMIC);
1940 if (unlikely(!nskb))
1949 nskb->dev = skb->dev;
1950 nskb->priority = skb->priority;
1951 nskb->protocol = skb->protocol;
1952 nskb->dst = dst_clone(skb->dst);
1953 memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
1954 nskb->pkt_type = skb->pkt_type;
1955 nskb->mac_len = skb->mac_len;
1957 skb_reserve(nskb, headroom);
1958 nskb->mac.raw = nskb->data;
1959 nskb->nh.raw = nskb->data + skb->mac_len;
1960 nskb->h.raw = nskb->nh.raw + (skb->h.raw - skb->nh.raw);
1961 memcpy(skb_put(nskb, doffset), skb->data, doffset);
1964 nskb->csum = skb_copy_and_csum_bits(skb, offset,
1970 frag = skb_shinfo(nskb)->frags;
1973 nskb->ip_summed = CHECKSUM_HW;
1974 nskb->csum = skb->csum;
1975 memcpy(skb_put(nskb, hsize), skb->data + offset, hsize);
1977 while (pos < offset + len) {
1978 BUG_ON(i >= nfrags);
1980 *frag = skb_shinfo(skb)->frags[i];
1981 get_page(frag->page);
1985 frag->page_offset += offset - pos;
1986 frag->size -= offset - pos;
1991 if (pos + size <= offset + len) {
1995 frag->size -= pos + size - (offset + len);
2002 skb_shinfo(nskb)->nr_frags = k;
2003 nskb->data_len = len - hsize;
2004 nskb->len += nskb->data_len;
2005 nskb->truesize += nskb->data_len;
2006 } while ((offset += len) < skb->len);
2011 while ((skb = segs)) {
2015 return ERR_PTR(err);
2018 EXPORT_SYMBOL_GPL(skb_segment);
2020 void __init skb_init(void)
2022 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
2023 sizeof(struct sk_buff),
2027 if (!skbuff_head_cache)
2028 panic("cannot create skbuff cache");
2030 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2031 (2*sizeof(struct sk_buff)) +
2036 if (!skbuff_fclone_cache)
2037 panic("cannot create skbuff cache");
2040 EXPORT_SYMBOL(___pskb_trim);
2041 EXPORT_SYMBOL(__kfree_skb);
2042 EXPORT_SYMBOL(kfree_skb);
2043 EXPORT_SYMBOL(__pskb_pull_tail);
2044 EXPORT_SYMBOL(__alloc_skb);
2045 EXPORT_SYMBOL(pskb_copy);
2046 EXPORT_SYMBOL(pskb_expand_head);
2047 EXPORT_SYMBOL(skb_checksum);
2048 EXPORT_SYMBOL(skb_clone);
2049 EXPORT_SYMBOL(skb_clone_fraglist);
2050 EXPORT_SYMBOL(skb_copy);
2051 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2052 EXPORT_SYMBOL(skb_copy_and_csum_dev);
2053 EXPORT_SYMBOL(skb_copy_bits);
2054 EXPORT_SYMBOL(skb_copy_expand);
2055 EXPORT_SYMBOL(skb_over_panic);
2056 EXPORT_SYMBOL(skb_pad);
2057 EXPORT_SYMBOL(skb_realloc_headroom);
2058 EXPORT_SYMBOL(skb_under_panic);
2059 EXPORT_SYMBOL(skb_dequeue);
2060 EXPORT_SYMBOL(skb_dequeue_tail);
2061 EXPORT_SYMBOL(skb_insert);
2062 EXPORT_SYMBOL(skb_queue_purge);
2063 EXPORT_SYMBOL(skb_queue_head);
2064 EXPORT_SYMBOL(skb_queue_tail);
2065 EXPORT_SYMBOL(skb_unlink);
2066 EXPORT_SYMBOL(skb_append);
2067 EXPORT_SYMBOL(skb_split);
2068 EXPORT_SYMBOL(skb_prepare_seq_read);
2069 EXPORT_SYMBOL(skb_seq_read);
2070 EXPORT_SYMBOL(skb_abort_seq_read);
2071 EXPORT_SYMBOL(skb_find_text);
2072 EXPORT_SYMBOL(skb_append_datato_frags);