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>
45 #include <linux/interrupt.h>
47 #include <linux/inet.h>
48 #include <linux/slab.h>
49 #include <linux/netdevice.h>
50 #ifdef CONFIG_NET_CLS_ACT
51 #include <net/pkt_sched.h>
53 #include <linux/string.h>
54 #include <linux/skbuff.h>
55 #include <linux/cache.h>
56 #include <linux/rtnetlink.h>
57 #include <linux/init.h>
58 #include <linux/scatterlist.h>
60 #include <net/protocol.h>
63 #include <net/checksum.h>
66 #include <asm/uaccess.h>
67 #include <asm/system.h>
71 static struct kmem_cache *skbuff_head_cache __read_mostly;
72 static struct kmem_cache *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:%#lx end:%#lx dev:%s\n",
92 here, skb->len, sz, skb->head, skb->data,
93 (unsigned long)skb->tail, (unsigned long)skb->end,
94 skb->dev ? skb->dev->name : "<NULL>");
99 * skb_under_panic - private function
104 * Out of line support code for skb_push(). Not user callable.
107 void skb_under_panic(struct sk_buff *skb, int sz, void *here)
109 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
110 "data:%p tail:%#lx end:%#lx dev:%s\n",
111 here, skb->len, sz, skb->head, skb->data,
112 (unsigned long)skb->tail, (unsigned long)skb->end,
113 skb->dev ? skb->dev->name : "<NULL>");
117 void skb_truesize_bug(struct sk_buff *skb)
119 printk(KERN_ERR "SKB BUG: Invalid truesize (%u) "
120 "len=%u, sizeof(sk_buff)=%Zd\n",
121 skb->truesize, skb->len, sizeof(struct sk_buff));
123 EXPORT_SYMBOL(skb_truesize_bug);
125 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
126 * 'private' fields and also do memory statistics to find all the
132 * __alloc_skb - allocate a network buffer
133 * @size: size to allocate
134 * @gfp_mask: allocation mask
135 * @fclone: allocate from fclone cache instead of head cache
136 * and allocate a cloned (child) skb
137 * @node: numa node to allocate memory on
139 * Allocate a new &sk_buff. The returned buffer has no headroom and a
140 * tail room of size bytes. The object has a reference count of one.
141 * The return is the buffer. On a failure the return is %NULL.
143 * Buffers may only be allocated from interrupts using a @gfp_mask of
146 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
147 int fclone, int node)
149 struct kmem_cache *cache;
150 struct skb_shared_info *shinfo;
154 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
157 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
161 size = SKB_DATA_ALIGN(size);
162 data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
168 * See comment in sk_buff definition, just before the 'tail' member
170 memset(skb, 0, offsetof(struct sk_buff, tail));
171 skb->truesize = size + sizeof(struct sk_buff);
172 atomic_set(&skb->users, 1);
175 skb_reset_tail_pointer(skb);
176 skb->end = skb->tail + 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 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
206 * @dev: network device to receive on
207 * @length: length to allocate
208 * @gfp_mask: get_free_pages mask, passed to alloc_skb
210 * Allocate a new &sk_buff and assign it a usage count of one. The
211 * buffer has unspecified headroom built in. Users should allocate
212 * the headroom they think they need without accounting for the
213 * built in space. The built in space is used for optimisations.
215 * %NULL is returned if there is no free memory.
217 struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
218 unsigned int length, gfp_t gfp_mask)
220 int node = dev->dev.parent ? dev_to_node(dev->dev.parent) : -1;
223 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, node);
225 skb_reserve(skb, NET_SKB_PAD);
231 static void skb_drop_list(struct sk_buff **listp)
233 struct sk_buff *list = *listp;
238 struct sk_buff *this = list;
244 static inline void skb_drop_fraglist(struct sk_buff *skb)
246 skb_drop_list(&skb_shinfo(skb)->frag_list);
249 static void skb_clone_fraglist(struct sk_buff *skb)
251 struct sk_buff *list;
253 for (list = skb_shinfo(skb)->frag_list; list; list = list->next)
257 static void skb_release_data(struct sk_buff *skb)
260 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
261 &skb_shinfo(skb)->dataref)) {
262 if (skb_shinfo(skb)->nr_frags) {
264 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
265 put_page(skb_shinfo(skb)->frags[i].page);
268 if (skb_shinfo(skb)->frag_list)
269 skb_drop_fraglist(skb);
276 * Free an skbuff by memory without cleaning the state.
278 void kfree_skbmem(struct sk_buff *skb)
280 struct sk_buff *other;
281 atomic_t *fclone_ref;
283 skb_release_data(skb);
284 switch (skb->fclone) {
285 case SKB_FCLONE_UNAVAILABLE:
286 kmem_cache_free(skbuff_head_cache, skb);
289 case SKB_FCLONE_ORIG:
290 fclone_ref = (atomic_t *) (skb + 2);
291 if (atomic_dec_and_test(fclone_ref))
292 kmem_cache_free(skbuff_fclone_cache, skb);
295 case SKB_FCLONE_CLONE:
296 fclone_ref = (atomic_t *) (skb + 1);
299 /* The clone portion is available for
300 * fast-cloning again.
302 skb->fclone = SKB_FCLONE_UNAVAILABLE;
304 if (atomic_dec_and_test(fclone_ref))
305 kmem_cache_free(skbuff_fclone_cache, other);
311 * __kfree_skb - private function
314 * Free an sk_buff. Release anything attached to the buffer.
315 * Clean the state. This is an internal helper function. Users should
316 * always call kfree_skb
319 void __kfree_skb(struct sk_buff *skb)
321 dst_release(skb->dst);
323 secpath_put(skb->sp);
325 if (skb->destructor) {
327 skb->destructor(skb);
329 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
330 nf_conntrack_put(skb->nfct);
331 nf_conntrack_put_reasm(skb->nfct_reasm);
333 #ifdef CONFIG_BRIDGE_NETFILTER
334 nf_bridge_put(skb->nf_bridge);
336 /* XXX: IS this still necessary? - JHS */
337 #ifdef CONFIG_NET_SCHED
339 #ifdef CONFIG_NET_CLS_ACT
348 * kfree_skb - free an sk_buff
349 * @skb: buffer to free
351 * Drop a reference to the buffer and free it if the usage count has
354 void kfree_skb(struct sk_buff *skb)
358 if (likely(atomic_read(&skb->users) == 1))
360 else if (likely(!atomic_dec_and_test(&skb->users)))
366 * skb_clone - duplicate an sk_buff
367 * @skb: buffer to clone
368 * @gfp_mask: allocation priority
370 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
371 * copies share the same packet data but not structure. The new
372 * buffer has a reference count of 1. If the allocation fails the
373 * function returns %NULL otherwise the new buffer is returned.
375 * If this function is called from an interrupt gfp_mask() must be
379 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
384 if (skb->fclone == SKB_FCLONE_ORIG &&
385 n->fclone == SKB_FCLONE_UNAVAILABLE) {
386 atomic_t *fclone_ref = (atomic_t *) (n + 1);
387 n->fclone = SKB_FCLONE_CLONE;
388 atomic_inc(fclone_ref);
390 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
393 n->fclone = SKB_FCLONE_UNAVAILABLE;
396 #define C(x) n->x = skb->x
398 n->next = n->prev = NULL;
409 secpath_get(skb->sp);
411 memcpy(n->cb, skb->cb, sizeof(skb->cb));
422 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
426 n->destructor = NULL;
429 #ifdef CONFIG_NET_SCHED
431 #ifdef CONFIG_NET_CLS_ACT
432 n->tc_verd = SET_TC_VERD(skb->tc_verd,0);
433 n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd);
434 n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
437 skb_copy_secmark(n, skb);
440 atomic_set(&n->users, 1);
446 atomic_inc(&(skb_shinfo(skb)->dataref));
452 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
454 #ifndef NET_SKBUFF_DATA_USES_OFFSET
456 * Shift between the two data areas in bytes
458 unsigned long offset = new->data - old->data;
462 new->priority = old->priority;
463 new->protocol = old->protocol;
464 new->dst = dst_clone(old->dst);
466 new->sp = secpath_get(old->sp);
468 new->transport_header = old->transport_header;
469 new->network_header = old->network_header;
470 new->mac_header = old->mac_header;
471 #ifndef NET_SKBUFF_DATA_USES_OFFSET
472 /* {transport,network,mac}_header are relative to skb->head */
473 new->transport_header += offset;
474 new->network_header += offset;
475 new->mac_header += offset;
477 memcpy(new->cb, old->cb, sizeof(old->cb));
478 new->local_df = old->local_df;
479 new->fclone = SKB_FCLONE_UNAVAILABLE;
480 new->pkt_type = old->pkt_type;
481 new->tstamp = old->tstamp;
482 new->destructor = NULL;
483 new->mark = old->mark;
485 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
486 new->ipvs_property = old->ipvs_property;
488 #ifdef CONFIG_NET_SCHED
489 #ifdef CONFIG_NET_CLS_ACT
490 new->tc_verd = old->tc_verd;
492 new->tc_index = old->tc_index;
494 skb_copy_secmark(new, old);
495 atomic_set(&new->users, 1);
496 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
497 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
498 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
502 * skb_copy - create private copy of an sk_buff
503 * @skb: buffer to copy
504 * @gfp_mask: allocation priority
506 * Make a copy of both an &sk_buff and its data. This is used when the
507 * caller wishes to modify the data and needs a private copy of the
508 * data to alter. Returns %NULL on failure or the pointer to the buffer
509 * on success. The returned buffer has a reference count of 1.
511 * As by-product this function converts non-linear &sk_buff to linear
512 * one, so that &sk_buff becomes completely private and caller is allowed
513 * to modify all the data of returned buffer. This means that this
514 * function is not recommended for use in circumstances when only
515 * header is going to be modified. Use pskb_copy() instead.
518 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
520 int headerlen = skb->data - skb->head;
522 * Allocate the copy buffer
525 #ifdef NET_SKBUFF_DATA_USES_OFFSET
526 n = alloc_skb(skb->end + skb->data_len, gfp_mask);
528 n = alloc_skb(skb->end - skb->head + skb->data_len, gfp_mask);
533 /* Set the data pointer */
534 skb_reserve(n, headerlen);
535 /* Set the tail pointer and length */
536 skb_put(n, skb->len);
538 n->ip_summed = skb->ip_summed;
540 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
543 copy_skb_header(n, skb);
549 * pskb_copy - create copy of an sk_buff with private head.
550 * @skb: buffer to copy
551 * @gfp_mask: allocation priority
553 * Make a copy of both an &sk_buff and part of its data, located
554 * in header. Fragmented data remain shared. This is used when
555 * the caller wishes to modify only header of &sk_buff and needs
556 * private copy of the header to alter. Returns %NULL on failure
557 * or the pointer to the buffer on success.
558 * The returned buffer has a reference count of 1.
561 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
564 * Allocate the copy buffer
567 #ifdef NET_SKBUFF_DATA_USES_OFFSET
568 n = alloc_skb(skb->end, gfp_mask);
570 n = alloc_skb(skb->end - skb->head, gfp_mask);
575 /* Set the data pointer */
576 skb_reserve(n, skb->data - skb->head);
577 /* Set the tail pointer and length */
578 skb_put(n, skb_headlen(skb));
580 skb_copy_from_linear_data(skb, n->data, n->len);
582 n->ip_summed = skb->ip_summed;
584 n->truesize += skb->data_len;
585 n->data_len = skb->data_len;
588 if (skb_shinfo(skb)->nr_frags) {
591 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
592 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
593 get_page(skb_shinfo(n)->frags[i].page);
595 skb_shinfo(n)->nr_frags = i;
598 if (skb_shinfo(skb)->frag_list) {
599 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
600 skb_clone_fraglist(n);
603 copy_skb_header(n, skb);
609 * pskb_expand_head - reallocate header of &sk_buff
610 * @skb: buffer to reallocate
611 * @nhead: room to add at head
612 * @ntail: room to add at tail
613 * @gfp_mask: allocation priority
615 * Expands (or creates identical copy, if &nhead and &ntail are zero)
616 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
617 * reference count of 1. Returns zero in the case of success or error,
618 * if expansion failed. In the last case, &sk_buff is not changed.
620 * All the pointers pointing into skb header may change and must be
621 * reloaded after call to this function.
624 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
629 #ifdef NET_SKBUFF_DATA_USES_OFFSET
630 int size = nhead + skb->end + ntail;
632 int size = nhead + (skb->end - skb->head) + ntail;
639 size = SKB_DATA_ALIGN(size);
641 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
645 /* Copy only real data... and, alas, header. This should be
646 * optimized for the cases when header is void. */
647 memcpy(data + nhead, skb->head,
648 #ifdef NET_SKBUFF_DATA_USES_OFFSET
651 skb->tail - skb->head);
653 memcpy(data + size, skb_end_pointer(skb),
654 sizeof(struct skb_shared_info));
656 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
657 get_page(skb_shinfo(skb)->frags[i].page);
659 if (skb_shinfo(skb)->frag_list)
660 skb_clone_fraglist(skb);
662 skb_release_data(skb);
664 off = (data + nhead) - skb->head;
668 #ifdef NET_SKBUFF_DATA_USES_OFFSET
672 skb->end = skb->head + size;
674 /* {transport,network,mac}_header and tail are relative to skb->head */
676 skb->transport_header += off;
677 skb->network_header += off;
678 skb->mac_header += off;
681 atomic_set(&skb_shinfo(skb)->dataref, 1);
688 /* Make private copy of skb with writable head and some headroom */
690 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
692 struct sk_buff *skb2;
693 int delta = headroom - skb_headroom(skb);
696 skb2 = pskb_copy(skb, GFP_ATOMIC);
698 skb2 = skb_clone(skb, GFP_ATOMIC);
699 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
710 * skb_copy_expand - copy and expand sk_buff
711 * @skb: buffer to copy
712 * @newheadroom: new free bytes at head
713 * @newtailroom: new free bytes at tail
714 * @gfp_mask: allocation priority
716 * Make a copy of both an &sk_buff and its data and while doing so
717 * allocate additional space.
719 * This is used when the caller wishes to modify the data and needs a
720 * private copy of the data to alter as well as more space for new fields.
721 * Returns %NULL on failure or the pointer to the buffer
722 * on success. The returned buffer has a reference count of 1.
724 * You must pass %GFP_ATOMIC as the allocation priority if this function
725 * is called from an interrupt.
727 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used
728 * only by netfilter in the cases when checksum is recalculated? --ANK
730 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
731 int newheadroom, int newtailroom,
735 * Allocate the copy buffer
737 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
739 int head_copy_len, head_copy_off;
744 skb_reserve(n, newheadroom);
746 /* Set the tail pointer and length */
747 skb_put(n, skb->len);
749 head_copy_len = skb_headroom(skb);
751 if (newheadroom <= head_copy_len)
752 head_copy_len = newheadroom;
754 head_copy_off = newheadroom - head_copy_len;
756 /* Copy the linear header and data. */
757 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
758 skb->len + head_copy_len))
761 copy_skb_header(n, skb);
767 * skb_pad - zero pad the tail of an skb
768 * @skb: buffer to pad
771 * Ensure that a buffer is followed by a padding area that is zero
772 * filled. Used by network drivers which may DMA or transfer data
773 * beyond the buffer end onto the wire.
775 * May return error in out of memory cases. The skb is freed on error.
778 int skb_pad(struct sk_buff *skb, int pad)
783 /* If the skbuff is non linear tailroom is always zero.. */
784 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
785 memset(skb->data+skb->len, 0, pad);
789 ntail = skb->data_len + pad - (skb->end - skb->tail);
790 if (likely(skb_cloned(skb) || ntail > 0)) {
791 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
796 /* FIXME: The use of this function with non-linear skb's really needs
799 err = skb_linearize(skb);
803 memset(skb->data + skb->len, 0, pad);
811 /* Trims skb to length len. It can change skb pointers.
814 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
816 struct sk_buff **fragp;
817 struct sk_buff *frag;
818 int offset = skb_headlen(skb);
819 int nfrags = skb_shinfo(skb)->nr_frags;
823 if (skb_cloned(skb) &&
824 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
831 for (; i < nfrags; i++) {
832 int end = offset + skb_shinfo(skb)->frags[i].size;
839 skb_shinfo(skb)->frags[i++].size = len - offset;
842 skb_shinfo(skb)->nr_frags = i;
844 for (; i < nfrags; i++)
845 put_page(skb_shinfo(skb)->frags[i].page);
847 if (skb_shinfo(skb)->frag_list)
848 skb_drop_fraglist(skb);
852 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
853 fragp = &frag->next) {
854 int end = offset + frag->len;
856 if (skb_shared(frag)) {
857 struct sk_buff *nfrag;
859 nfrag = skb_clone(frag, GFP_ATOMIC);
860 if (unlikely(!nfrag))
863 nfrag->next = frag->next;
875 unlikely((err = pskb_trim(frag, len - offset))))
879 skb_drop_list(&frag->next);
884 if (len > skb_headlen(skb)) {
885 skb->data_len -= skb->len - len;
890 skb_set_tail_pointer(skb, len);
897 * __pskb_pull_tail - advance tail of skb header
898 * @skb: buffer to reallocate
899 * @delta: number of bytes to advance tail
901 * The function makes a sense only on a fragmented &sk_buff,
902 * it expands header moving its tail forward and copying necessary
903 * data from fragmented part.
905 * &sk_buff MUST have reference count of 1.
907 * Returns %NULL (and &sk_buff does not change) if pull failed
908 * or value of new tail of skb in the case of success.
910 * All the pointers pointing into skb header may change and must be
911 * reloaded after call to this function.
914 /* Moves tail of skb head forward, copying data from fragmented part,
915 * when it is necessary.
916 * 1. It may fail due to malloc failure.
917 * 2. It may change skb pointers.
919 * It is pretty complicated. Luckily, it is called only in exceptional cases.
921 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
923 /* If skb has not enough free space at tail, get new one
924 * plus 128 bytes for future expansions. If we have enough
925 * room at tail, reallocate without expansion only if skb is cloned.
927 int i, k, eat = (skb->tail + delta) - skb->end;
929 if (eat > 0 || skb_cloned(skb)) {
930 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
935 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
938 /* Optimization: no fragments, no reasons to preestimate
939 * size of pulled pages. Superb.
941 if (!skb_shinfo(skb)->frag_list)
944 /* Estimate size of pulled pages. */
946 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
947 if (skb_shinfo(skb)->frags[i].size >= eat)
949 eat -= skb_shinfo(skb)->frags[i].size;
952 /* If we need update frag list, we are in troubles.
953 * Certainly, it possible to add an offset to skb data,
954 * but taking into account that pulling is expected to
955 * be very rare operation, it is worth to fight against
956 * further bloating skb head and crucify ourselves here instead.
957 * Pure masohism, indeed. 8)8)
960 struct sk_buff *list = skb_shinfo(skb)->frag_list;
961 struct sk_buff *clone = NULL;
962 struct sk_buff *insp = NULL;
967 if (list->len <= eat) {
968 /* Eaten as whole. */
973 /* Eaten partially. */
975 if (skb_shared(list)) {
976 /* Sucks! We need to fork list. :-( */
977 clone = skb_clone(list, GFP_ATOMIC);
983 /* This may be pulled without
987 if (!pskb_pull(list, eat)) {
996 /* Free pulled out fragments. */
997 while ((list = skb_shinfo(skb)->frag_list) != insp) {
998 skb_shinfo(skb)->frag_list = list->next;
1001 /* And insert new clone at head. */
1004 skb_shinfo(skb)->frag_list = clone;
1007 /* Success! Now we may commit changes to skb data. */
1012 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1013 if (skb_shinfo(skb)->frags[i].size <= eat) {
1014 put_page(skb_shinfo(skb)->frags[i].page);
1015 eat -= skb_shinfo(skb)->frags[i].size;
1017 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1019 skb_shinfo(skb)->frags[k].page_offset += eat;
1020 skb_shinfo(skb)->frags[k].size -= eat;
1026 skb_shinfo(skb)->nr_frags = k;
1029 skb->data_len -= delta;
1031 return skb_tail_pointer(skb);
1034 /* Copy some data bits from skb to kernel buffer. */
1036 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1039 int start = skb_headlen(skb);
1041 if (offset > (int)skb->len - len)
1045 if ((copy = start - offset) > 0) {
1048 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1049 if ((len -= copy) == 0)
1055 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1058 BUG_TRAP(start <= offset + len);
1060 end = start + skb_shinfo(skb)->frags[i].size;
1061 if ((copy = end - offset) > 0) {
1067 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1069 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1070 offset - start, copy);
1071 kunmap_skb_frag(vaddr);
1073 if ((len -= copy) == 0)
1081 if (skb_shinfo(skb)->frag_list) {
1082 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1084 for (; list; list = list->next) {
1087 BUG_TRAP(start <= offset + len);
1089 end = start + list->len;
1090 if ((copy = end - offset) > 0) {
1093 if (skb_copy_bits(list, offset - start,
1096 if ((len -= copy) == 0)
1112 * skb_store_bits - store bits from kernel buffer to skb
1113 * @skb: destination buffer
1114 * @offset: offset in destination
1115 * @from: source buffer
1116 * @len: number of bytes to copy
1118 * Copy the specified number of bytes from the source buffer to the
1119 * destination skb. This function handles all the messy bits of
1120 * traversing fragment lists and such.
1123 int skb_store_bits(const struct sk_buff *skb, int offset, void *from, int len)
1126 int start = skb_headlen(skb);
1128 if (offset > (int)skb->len - len)
1131 if ((copy = start - offset) > 0) {
1134 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1135 if ((len -= copy) == 0)
1141 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1142 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1145 BUG_TRAP(start <= offset + len);
1147 end = start + frag->size;
1148 if ((copy = end - offset) > 0) {
1154 vaddr = kmap_skb_frag(frag);
1155 memcpy(vaddr + frag->page_offset + offset - start,
1157 kunmap_skb_frag(vaddr);
1159 if ((len -= copy) == 0)
1167 if (skb_shinfo(skb)->frag_list) {
1168 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1170 for (; list; list = list->next) {
1173 BUG_TRAP(start <= offset + len);
1175 end = start + list->len;
1176 if ((copy = end - offset) > 0) {
1179 if (skb_store_bits(list, offset - start,
1182 if ((len -= copy) == 0)
1197 EXPORT_SYMBOL(skb_store_bits);
1199 /* Checksum skb data. */
1201 __wsum skb_checksum(const struct sk_buff *skb, int offset,
1202 int len, __wsum csum)
1204 int start = skb_headlen(skb);
1205 int i, copy = start - offset;
1208 /* Checksum header. */
1212 csum = csum_partial(skb->data + offset, copy, csum);
1213 if ((len -= copy) == 0)
1219 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1222 BUG_TRAP(start <= offset + len);
1224 end = start + skb_shinfo(skb)->frags[i].size;
1225 if ((copy = end - offset) > 0) {
1228 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1232 vaddr = kmap_skb_frag(frag);
1233 csum2 = csum_partial(vaddr + frag->page_offset +
1234 offset - start, copy, 0);
1235 kunmap_skb_frag(vaddr);
1236 csum = csum_block_add(csum, csum2, pos);
1245 if (skb_shinfo(skb)->frag_list) {
1246 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1248 for (; list; list = list->next) {
1251 BUG_TRAP(start <= offset + len);
1253 end = start + list->len;
1254 if ((copy = end - offset) > 0) {
1258 csum2 = skb_checksum(list, offset - start,
1260 csum = csum_block_add(csum, csum2, pos);
1261 if ((len -= copy) == 0)
1274 /* Both of above in one bottle. */
1276 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1277 u8 *to, int len, __wsum csum)
1279 int start = skb_headlen(skb);
1280 int i, copy = start - offset;
1287 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1289 if ((len -= copy) == 0)
1296 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1299 BUG_TRAP(start <= offset + len);
1301 end = start + skb_shinfo(skb)->frags[i].size;
1302 if ((copy = end - offset) > 0) {
1305 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1309 vaddr = kmap_skb_frag(frag);
1310 csum2 = csum_partial_copy_nocheck(vaddr +
1314 kunmap_skb_frag(vaddr);
1315 csum = csum_block_add(csum, csum2, pos);
1325 if (skb_shinfo(skb)->frag_list) {
1326 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1328 for (; list; list = list->next) {
1332 BUG_TRAP(start <= offset + len);
1334 end = start + list->len;
1335 if ((copy = end - offset) > 0) {
1338 csum2 = skb_copy_and_csum_bits(list,
1341 csum = csum_block_add(csum, csum2, pos);
1342 if ((len -= copy) == 0)
1355 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1360 if (skb->ip_summed == CHECKSUM_PARTIAL)
1361 csstart = skb_transport_offset(skb);
1363 csstart = skb_headlen(skb);
1365 BUG_ON(csstart > skb_headlen(skb));
1367 skb_copy_from_linear_data(skb, to, csstart);
1370 if (csstart != skb->len)
1371 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1372 skb->len - csstart, 0);
1374 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1375 long csstuff = csstart + skb->csum_offset;
1377 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
1382 * skb_dequeue - remove from the head of the queue
1383 * @list: list to dequeue from
1385 * Remove the head of the list. The list lock is taken so the function
1386 * may be used safely with other locking list functions. The head item is
1387 * returned or %NULL if the list is empty.
1390 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1392 unsigned long flags;
1393 struct sk_buff *result;
1395 spin_lock_irqsave(&list->lock, flags);
1396 result = __skb_dequeue(list);
1397 spin_unlock_irqrestore(&list->lock, flags);
1402 * skb_dequeue_tail - remove from the tail of the queue
1403 * @list: list to dequeue from
1405 * Remove the tail of the list. The list lock is taken so the function
1406 * may be used safely with other locking list functions. The tail item is
1407 * returned or %NULL if the list is empty.
1409 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1411 unsigned long flags;
1412 struct sk_buff *result;
1414 spin_lock_irqsave(&list->lock, flags);
1415 result = __skb_dequeue_tail(list);
1416 spin_unlock_irqrestore(&list->lock, flags);
1421 * skb_queue_purge - empty a list
1422 * @list: list to empty
1424 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1425 * the list and one reference dropped. This function takes the list
1426 * lock and is atomic with respect to other list locking functions.
1428 void skb_queue_purge(struct sk_buff_head *list)
1430 struct sk_buff *skb;
1431 while ((skb = skb_dequeue(list)) != NULL)
1436 * skb_queue_head - queue a buffer at the list head
1437 * @list: list to use
1438 * @newsk: buffer to queue
1440 * Queue a buffer at the start of the list. This function takes the
1441 * list lock and can be used safely with other locking &sk_buff functions
1444 * A buffer cannot be placed on two lists at the same time.
1446 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
1448 unsigned long flags;
1450 spin_lock_irqsave(&list->lock, flags);
1451 __skb_queue_head(list, newsk);
1452 spin_unlock_irqrestore(&list->lock, flags);
1456 * skb_queue_tail - queue a buffer at the list tail
1457 * @list: list to use
1458 * @newsk: buffer to queue
1460 * Queue a buffer at the tail of the list. This function takes the
1461 * list lock and can be used safely with other locking &sk_buff functions
1464 * A buffer cannot be placed on two lists at the same time.
1466 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
1468 unsigned long flags;
1470 spin_lock_irqsave(&list->lock, flags);
1471 __skb_queue_tail(list, newsk);
1472 spin_unlock_irqrestore(&list->lock, flags);
1476 * skb_unlink - remove a buffer from a list
1477 * @skb: buffer to remove
1478 * @list: list to use
1480 * Remove a packet from a list. The list locks are taken and this
1481 * function is atomic with respect to other list locked calls
1483 * You must know what list the SKB is on.
1485 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1487 unsigned long flags;
1489 spin_lock_irqsave(&list->lock, flags);
1490 __skb_unlink(skb, list);
1491 spin_unlock_irqrestore(&list->lock, flags);
1495 * skb_append - append a buffer
1496 * @old: buffer to insert after
1497 * @newsk: buffer to insert
1498 * @list: list to use
1500 * Place a packet after a given packet in a list. The list locks are taken
1501 * and this function is atomic with respect to other list locked calls.
1502 * A buffer cannot be placed on two lists at the same time.
1504 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1506 unsigned long flags;
1508 spin_lock_irqsave(&list->lock, flags);
1509 __skb_append(old, newsk, list);
1510 spin_unlock_irqrestore(&list->lock, flags);
1515 * skb_insert - insert a buffer
1516 * @old: buffer to insert before
1517 * @newsk: buffer to insert
1518 * @list: list to use
1520 * Place a packet before a given packet in a list. The list locks are
1521 * taken and this function is atomic with respect to other list locked
1524 * A buffer cannot be placed on two lists at the same time.
1526 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1528 unsigned long flags;
1530 spin_lock_irqsave(&list->lock, flags);
1531 __skb_insert(newsk, old->prev, old, list);
1532 spin_unlock_irqrestore(&list->lock, flags);
1535 static inline void skb_split_inside_header(struct sk_buff *skb,
1536 struct sk_buff* skb1,
1537 const u32 len, const int pos)
1541 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
1543 /* And move data appendix as is. */
1544 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1545 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
1547 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
1548 skb_shinfo(skb)->nr_frags = 0;
1549 skb1->data_len = skb->data_len;
1550 skb1->len += skb1->data_len;
1553 skb_set_tail_pointer(skb, len);
1556 static inline void skb_split_no_header(struct sk_buff *skb,
1557 struct sk_buff* skb1,
1558 const u32 len, int pos)
1561 const int nfrags = skb_shinfo(skb)->nr_frags;
1563 skb_shinfo(skb)->nr_frags = 0;
1564 skb1->len = skb1->data_len = skb->len - len;
1566 skb->data_len = len - pos;
1568 for (i = 0; i < nfrags; i++) {
1569 int size = skb_shinfo(skb)->frags[i].size;
1571 if (pos + size > len) {
1572 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
1576 * We have two variants in this case:
1577 * 1. Move all the frag to the second
1578 * part, if it is possible. F.e.
1579 * this approach is mandatory for TUX,
1580 * where splitting is expensive.
1581 * 2. Split is accurately. We make this.
1583 get_page(skb_shinfo(skb)->frags[i].page);
1584 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
1585 skb_shinfo(skb1)->frags[0].size -= len - pos;
1586 skb_shinfo(skb)->frags[i].size = len - pos;
1587 skb_shinfo(skb)->nr_frags++;
1591 skb_shinfo(skb)->nr_frags++;
1594 skb_shinfo(skb1)->nr_frags = k;
1598 * skb_split - Split fragmented skb to two parts at length len.
1599 * @skb: the buffer to split
1600 * @skb1: the buffer to receive the second part
1601 * @len: new length for skb
1603 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
1605 int pos = skb_headlen(skb);
1607 if (len < pos) /* Split line is inside header. */
1608 skb_split_inside_header(skb, skb1, len, pos);
1609 else /* Second chunk has no header, nothing to copy. */
1610 skb_split_no_header(skb, skb1, len, pos);
1614 * skb_prepare_seq_read - Prepare a sequential read of skb data
1615 * @skb: the buffer to read
1616 * @from: lower offset of data to be read
1617 * @to: upper offset of data to be read
1618 * @st: state variable
1620 * Initializes the specified state variable. Must be called before
1621 * invoking skb_seq_read() for the first time.
1623 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1624 unsigned int to, struct skb_seq_state *st)
1626 st->lower_offset = from;
1627 st->upper_offset = to;
1628 st->root_skb = st->cur_skb = skb;
1629 st->frag_idx = st->stepped_offset = 0;
1630 st->frag_data = NULL;
1634 * skb_seq_read - Sequentially read skb data
1635 * @consumed: number of bytes consumed by the caller so far
1636 * @data: destination pointer for data to be returned
1637 * @st: state variable
1639 * Reads a block of skb data at &consumed relative to the
1640 * lower offset specified to skb_prepare_seq_read(). Assigns
1641 * the head of the data block to &data and returns the length
1642 * of the block or 0 if the end of the skb data or the upper
1643 * offset has been reached.
1645 * The caller is not required to consume all of the data
1646 * returned, i.e. &consumed is typically set to the number
1647 * of bytes already consumed and the next call to
1648 * skb_seq_read() will return the remaining part of the block.
1650 * Note: The size of each block of data returned can be arbitary,
1651 * this limitation is the cost for zerocopy seqeuental
1652 * reads of potentially non linear data.
1654 * Note: Fragment lists within fragments are not implemented
1655 * at the moment, state->root_skb could be replaced with
1656 * a stack for this purpose.
1658 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1659 struct skb_seq_state *st)
1661 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
1664 if (unlikely(abs_offset >= st->upper_offset))
1668 block_limit = skb_headlen(st->cur_skb);
1670 if (abs_offset < block_limit) {
1671 *data = st->cur_skb->data + abs_offset;
1672 return block_limit - abs_offset;
1675 if (st->frag_idx == 0 && !st->frag_data)
1676 st->stepped_offset += skb_headlen(st->cur_skb);
1678 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
1679 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
1680 block_limit = frag->size + st->stepped_offset;
1682 if (abs_offset < block_limit) {
1684 st->frag_data = kmap_skb_frag(frag);
1686 *data = (u8 *) st->frag_data + frag->page_offset +
1687 (abs_offset - st->stepped_offset);
1689 return block_limit - abs_offset;
1692 if (st->frag_data) {
1693 kunmap_skb_frag(st->frag_data);
1694 st->frag_data = NULL;
1698 st->stepped_offset += frag->size;
1701 if (st->cur_skb->next) {
1702 st->cur_skb = st->cur_skb->next;
1705 } else if (st->root_skb == st->cur_skb &&
1706 skb_shinfo(st->root_skb)->frag_list) {
1707 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
1715 * skb_abort_seq_read - Abort a sequential read of skb data
1716 * @st: state variable
1718 * Must be called if skb_seq_read() was not called until it
1721 void skb_abort_seq_read(struct skb_seq_state *st)
1724 kunmap_skb_frag(st->frag_data);
1727 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
1729 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
1730 struct ts_config *conf,
1731 struct ts_state *state)
1733 return skb_seq_read(offset, text, TS_SKB_CB(state));
1736 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
1738 skb_abort_seq_read(TS_SKB_CB(state));
1742 * skb_find_text - Find a text pattern in skb data
1743 * @skb: the buffer to look in
1744 * @from: search offset
1746 * @config: textsearch configuration
1747 * @state: uninitialized textsearch state variable
1749 * Finds a pattern in the skb data according to the specified
1750 * textsearch configuration. Use textsearch_next() to retrieve
1751 * subsequent occurrences of the pattern. Returns the offset
1752 * to the first occurrence or UINT_MAX if no match was found.
1754 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1755 unsigned int to, struct ts_config *config,
1756 struct ts_state *state)
1760 config->get_next_block = skb_ts_get_next_block;
1761 config->finish = skb_ts_finish;
1763 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
1765 ret = textsearch_find(config, state);
1766 return (ret <= to - from ? ret : UINT_MAX);
1770 * skb_append_datato_frags: - append the user data to a skb
1771 * @sk: sock structure
1772 * @skb: skb structure to be appened with user data.
1773 * @getfrag: call back function to be used for getting the user data
1774 * @from: pointer to user message iov
1775 * @length: length of the iov message
1777 * Description: This procedure append the user data in the fragment part
1778 * of the skb if any page alloc fails user this procedure returns -ENOMEM
1780 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1781 int (*getfrag)(void *from, char *to, int offset,
1782 int len, int odd, struct sk_buff *skb),
1783 void *from, int length)
1786 skb_frag_t *frag = NULL;
1787 struct page *page = NULL;
1793 /* Return error if we don't have space for new frag */
1794 frg_cnt = skb_shinfo(skb)->nr_frags;
1795 if (frg_cnt >= MAX_SKB_FRAGS)
1798 /* allocate a new page for next frag */
1799 page = alloc_pages(sk->sk_allocation, 0);
1801 /* If alloc_page fails just return failure and caller will
1802 * free previous allocated pages by doing kfree_skb()
1807 /* initialize the next frag */
1808 sk->sk_sndmsg_page = page;
1809 sk->sk_sndmsg_off = 0;
1810 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
1811 skb->truesize += PAGE_SIZE;
1812 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1814 /* get the new initialized frag */
1815 frg_cnt = skb_shinfo(skb)->nr_frags;
1816 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
1818 /* copy the user data to page */
1819 left = PAGE_SIZE - frag->page_offset;
1820 copy = (length > left)? left : length;
1822 ret = getfrag(from, (page_address(frag->page) +
1823 frag->page_offset + frag->size),
1824 offset, copy, 0, skb);
1828 /* copy was successful so update the size parameters */
1829 sk->sk_sndmsg_off += copy;
1832 skb->data_len += copy;
1836 } while (length > 0);
1842 * skb_pull_rcsum - pull skb and update receive checksum
1843 * @skb: buffer to update
1844 * @start: start of data before pull
1845 * @len: length of data pulled
1847 * This function performs an skb_pull on the packet and updates
1848 * update the CHECKSUM_COMPLETE checksum. It should be used on
1849 * receive path processing instead of skb_pull unless you know
1850 * that the checksum difference is zero (e.g., a valid IP header)
1851 * or you are setting ip_summed to CHECKSUM_NONE.
1853 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
1855 BUG_ON(len > skb->len);
1857 BUG_ON(skb->len < skb->data_len);
1858 skb_postpull_rcsum(skb, skb->data, len);
1859 return skb->data += len;
1862 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
1865 * skb_segment - Perform protocol segmentation on skb.
1866 * @skb: buffer to segment
1867 * @features: features for the output path (see dev->features)
1869 * This function performs segmentation on the given skb. It returns
1870 * the segment at the given position. It returns NULL if there are
1871 * no more segments to generate, or when an error is encountered.
1873 struct sk_buff *skb_segment(struct sk_buff *skb, int features)
1875 struct sk_buff *segs = NULL;
1876 struct sk_buff *tail = NULL;
1877 unsigned int mss = skb_shinfo(skb)->gso_size;
1878 unsigned int doffset = skb->data - skb_mac_header(skb);
1879 unsigned int offset = doffset;
1880 unsigned int headroom;
1882 int sg = features & NETIF_F_SG;
1883 int nfrags = skb_shinfo(skb)->nr_frags;
1888 __skb_push(skb, doffset);
1889 headroom = skb_headroom(skb);
1890 pos = skb_headlen(skb);
1893 struct sk_buff *nskb;
1899 len = skb->len - offset;
1903 hsize = skb_headlen(skb) - offset;
1906 if (hsize > len || !sg)
1909 nskb = alloc_skb(hsize + doffset + headroom, GFP_ATOMIC);
1910 if (unlikely(!nskb))
1919 nskb->dev = skb->dev;
1920 nskb->priority = skb->priority;
1921 nskb->protocol = skb->protocol;
1922 nskb->dst = dst_clone(skb->dst);
1923 memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
1924 nskb->pkt_type = skb->pkt_type;
1925 nskb->mac_len = skb->mac_len;
1927 skb_reserve(nskb, headroom);
1928 skb_reset_mac_header(nskb);
1929 skb_set_network_header(nskb, skb->mac_len);
1930 nskb->transport_header = (nskb->network_header +
1931 skb_network_header_len(skb));
1932 skb_copy_from_linear_data(skb, skb_put(nskb, doffset),
1935 nskb->csum = skb_copy_and_csum_bits(skb, offset,
1941 frag = skb_shinfo(nskb)->frags;
1944 nskb->ip_summed = CHECKSUM_PARTIAL;
1945 nskb->csum = skb->csum;
1946 skb_copy_from_linear_data_offset(skb, offset,
1947 skb_put(nskb, hsize), hsize);
1949 while (pos < offset + len) {
1950 BUG_ON(i >= nfrags);
1952 *frag = skb_shinfo(skb)->frags[i];
1953 get_page(frag->page);
1957 frag->page_offset += offset - pos;
1958 frag->size -= offset - pos;
1963 if (pos + size <= offset + len) {
1967 frag->size -= pos + size - (offset + len);
1974 skb_shinfo(nskb)->nr_frags = k;
1975 nskb->data_len = len - hsize;
1976 nskb->len += nskb->data_len;
1977 nskb->truesize += nskb->data_len;
1978 } while ((offset += len) < skb->len);
1983 while ((skb = segs)) {
1987 return ERR_PTR(err);
1990 EXPORT_SYMBOL_GPL(skb_segment);
1992 void __init skb_init(void)
1994 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
1995 sizeof(struct sk_buff),
1997 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
1999 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2000 (2*sizeof(struct sk_buff)) +
2003 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2008 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2009 * @skb: Socket buffer containing the buffers to be mapped
2010 * @sg: The scatter-gather list to map into
2011 * @offset: The offset into the buffer's contents to start mapping
2012 * @len: Length of buffer space to be mapped
2014 * Fill the specified scatter-gather list with mappings/pointers into a
2015 * region of the buffer space attached to a socket buffer.
2018 skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2020 int start = skb_headlen(skb);
2021 int i, copy = start - offset;
2027 sg[elt].page = virt_to_page(skb->data + offset);
2028 sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
2029 sg[elt].length = copy;
2031 if ((len -= copy) == 0)
2036 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2039 BUG_TRAP(start <= offset + len);
2041 end = start + skb_shinfo(skb)->frags[i].size;
2042 if ((copy = end - offset) > 0) {
2043 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2047 sg[elt].page = frag->page;
2048 sg[elt].offset = frag->page_offset+offset-start;
2049 sg[elt].length = copy;
2058 if (skb_shinfo(skb)->frag_list) {
2059 struct sk_buff *list = skb_shinfo(skb)->frag_list;
2061 for (; list; list = list->next) {
2064 BUG_TRAP(start <= offset + len);
2066 end = start + list->len;
2067 if ((copy = end - offset) > 0) {
2070 elt += skb_to_sgvec(list, sg+elt, offset - start, copy);
2071 if ((len -= copy) == 0)
2083 * skb_cow_data - Check that a socket buffer's data buffers are writable
2084 * @skb: The socket buffer to check.
2085 * @tailbits: Amount of trailing space to be added
2086 * @trailer: Returned pointer to the skb where the @tailbits space begins
2088 * Make sure that the data buffers attached to a socket buffer are
2089 * writable. If they are not, private copies are made of the data buffers
2090 * and the socket buffer is set to use these instead.
2092 * If @tailbits is given, make sure that there is space to write @tailbits
2093 * bytes of data beyond current end of socket buffer. @trailer will be
2094 * set to point to the skb in which this space begins.
2096 * The number of scatterlist elements required to completely map the
2097 * COW'd and extended socket buffer will be returned.
2099 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
2103 struct sk_buff *skb1, **skb_p;
2105 /* If skb is cloned or its head is paged, reallocate
2106 * head pulling out all the pages (pages are considered not writable
2107 * at the moment even if they are anonymous).
2109 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
2110 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
2113 /* Easy case. Most of packets will go this way. */
2114 if (!skb_shinfo(skb)->frag_list) {
2115 /* A little of trouble, not enough of space for trailer.
2116 * This should not happen, when stack is tuned to generate
2117 * good frames. OK, on miss we reallocate and reserve even more
2118 * space, 128 bytes is fair. */
2120 if (skb_tailroom(skb) < tailbits &&
2121 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
2129 /* Misery. We are in troubles, going to mincer fragments... */
2132 skb_p = &skb_shinfo(skb)->frag_list;
2135 while ((skb1 = *skb_p) != NULL) {
2138 /* The fragment is partially pulled by someone,
2139 * this can happen on input. Copy it and everything
2142 if (skb_shared(skb1))
2145 /* If the skb is the last, worry about trailer. */
2147 if (skb1->next == NULL && tailbits) {
2148 if (skb_shinfo(skb1)->nr_frags ||
2149 skb_shinfo(skb1)->frag_list ||
2150 skb_tailroom(skb1) < tailbits)
2151 ntail = tailbits + 128;
2157 skb_shinfo(skb1)->nr_frags ||
2158 skb_shinfo(skb1)->frag_list) {
2159 struct sk_buff *skb2;
2161 /* Fuck, we are miserable poor guys... */
2163 skb2 = skb_copy(skb1, GFP_ATOMIC);
2165 skb2 = skb_copy_expand(skb1,
2169 if (unlikely(skb2 == NULL))
2173 skb_set_owner_w(skb2, skb1->sk);
2175 /* Looking around. Are we still alive?
2176 * OK, link new skb, drop old one */
2178 skb2->next = skb1->next;
2185 skb_p = &skb1->next;
2191 EXPORT_SYMBOL(___pskb_trim);
2192 EXPORT_SYMBOL(__kfree_skb);
2193 EXPORT_SYMBOL(kfree_skb);
2194 EXPORT_SYMBOL(__pskb_pull_tail);
2195 EXPORT_SYMBOL(__alloc_skb);
2196 EXPORT_SYMBOL(__netdev_alloc_skb);
2197 EXPORT_SYMBOL(pskb_copy);
2198 EXPORT_SYMBOL(pskb_expand_head);
2199 EXPORT_SYMBOL(skb_checksum);
2200 EXPORT_SYMBOL(skb_clone);
2201 EXPORT_SYMBOL(skb_clone_fraglist);
2202 EXPORT_SYMBOL(skb_copy);
2203 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2204 EXPORT_SYMBOL(skb_copy_and_csum_dev);
2205 EXPORT_SYMBOL(skb_copy_bits);
2206 EXPORT_SYMBOL(skb_copy_expand);
2207 EXPORT_SYMBOL(skb_over_panic);
2208 EXPORT_SYMBOL(skb_pad);
2209 EXPORT_SYMBOL(skb_realloc_headroom);
2210 EXPORT_SYMBOL(skb_under_panic);
2211 EXPORT_SYMBOL(skb_dequeue);
2212 EXPORT_SYMBOL(skb_dequeue_tail);
2213 EXPORT_SYMBOL(skb_insert);
2214 EXPORT_SYMBOL(skb_queue_purge);
2215 EXPORT_SYMBOL(skb_queue_head);
2216 EXPORT_SYMBOL(skb_queue_tail);
2217 EXPORT_SYMBOL(skb_unlink);
2218 EXPORT_SYMBOL(skb_append);
2219 EXPORT_SYMBOL(skb_split);
2220 EXPORT_SYMBOL(skb_prepare_seq_read);
2221 EXPORT_SYMBOL(skb_seq_read);
2222 EXPORT_SYMBOL(skb_abort_seq_read);
2223 EXPORT_SYMBOL(skb_find_text);
2224 EXPORT_SYMBOL(skb_append_datato_frags);
2226 EXPORT_SYMBOL_GPL(skb_to_sgvec);
2227 EXPORT_SYMBOL_GPL(skb_cow_data);