2 * Routines having to do with the 'struct sk_buff' memory handlers.
4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
8 * Alan Cox : Fixed the worst of the load
10 * Dave Platt : Interrupt stacking fix.
11 * Richard Kooijman : Timestamp fixes.
12 * Alan Cox : Changed buffer format.
13 * Alan Cox : destructor hook for AF_UNIX etc.
14 * Linus Torvalds : Better skb_clone.
15 * Alan Cox : Added skb_copy.
16 * Alan Cox : Added all the changed routines Linus
17 * only put in the headers
18 * Ray VanTassle : Fixed --skb->lock in free
19 * Alan Cox : skb_copy copy arp field
20 * Andi Kleen : slabified it.
21 * Robert Olsson : Removed skb_head_pool
24 * The __skb_ routines should be called with interrupts
25 * disabled, or you better be *real* sure that the operation is atomic
26 * with respect to whatever list is being frobbed (e.g. via lock_sock()
27 * or via disabling bottom half handlers, etc).
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
36 * The functions in this file will not compile correctly with gcc 2.4.x
39 #include <linux/module.h>
40 #include <linux/types.h>
41 #include <linux/kernel.h>
43 #include <linux/interrupt.h>
45 #include <linux/inet.h>
46 #include <linux/slab.h>
47 #include <linux/netdevice.h>
48 #ifdef CONFIG_NET_CLS_ACT
49 #include <net/pkt_sched.h>
51 #include <linux/string.h>
52 #include <linux/skbuff.h>
53 #include <linux/splice.h>
54 #include <linux/cache.h>
55 #include <linux/rtnetlink.h>
56 #include <linux/init.h>
57 #include <linux/scatterlist.h>
58 #include <linux/errqueue.h>
60 #include <net/protocol.h>
63 #include <net/checksum.h>
66 #include <asm/uaccess.h>
67 #include <asm/system.h>
68 #include <trace/skb.h>
72 static struct kmem_cache *skbuff_head_cache __read_mostly;
73 static struct kmem_cache *skbuff_fclone_cache __read_mostly;
75 static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
76 struct pipe_buffer *buf)
81 static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
82 struct pipe_buffer *buf)
87 static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
88 struct pipe_buffer *buf)
94 /* Pipe buffer operations for a socket. */
95 static struct pipe_buf_operations sock_pipe_buf_ops = {
97 .map = generic_pipe_buf_map,
98 .unmap = generic_pipe_buf_unmap,
99 .confirm = generic_pipe_buf_confirm,
100 .release = sock_pipe_buf_release,
101 .steal = sock_pipe_buf_steal,
102 .get = sock_pipe_buf_get,
106 * Keep out-of-line to prevent kernel bloat.
107 * __builtin_return_address is not used because it is not always
112 * skb_over_panic - private function
117 * Out of line support code for skb_put(). Not user callable.
119 void skb_over_panic(struct sk_buff *skb, int sz, void *here)
121 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
122 "data:%p tail:%#lx end:%#lx dev:%s\n",
123 here, skb->len, sz, skb->head, skb->data,
124 (unsigned long)skb->tail, (unsigned long)skb->end,
125 skb->dev ? skb->dev->name : "<NULL>");
128 EXPORT_SYMBOL(skb_over_panic);
131 * skb_under_panic - private function
136 * Out of line support code for skb_push(). Not user callable.
139 void skb_under_panic(struct sk_buff *skb, int sz, void *here)
141 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
142 "data:%p tail:%#lx end:%#lx dev:%s\n",
143 here, skb->len, sz, skb->head, skb->data,
144 (unsigned long)skb->tail, (unsigned long)skb->end,
145 skb->dev ? skb->dev->name : "<NULL>");
148 EXPORT_SYMBOL(skb_under_panic);
150 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
151 * 'private' fields and also do memory statistics to find all the
157 * __alloc_skb - allocate a network buffer
158 * @size: size to allocate
159 * @gfp_mask: allocation mask
160 * @fclone: allocate from fclone cache instead of head cache
161 * and allocate a cloned (child) skb
162 * @node: numa node to allocate memory on
164 * Allocate a new &sk_buff. The returned buffer has no headroom and a
165 * tail room of size bytes. The object has a reference count of one.
166 * The return is the buffer. On a failure the return is %NULL.
168 * Buffers may only be allocated from interrupts using a @gfp_mask of
171 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
172 int fclone, int node)
174 struct kmem_cache *cache;
175 struct skb_shared_info *shinfo;
179 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
182 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
186 size = SKB_DATA_ALIGN(size);
187 data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
193 * Only clear those fields we need to clear, not those that we will
194 * actually initialise below. Hence, don't put any more fields after
195 * the tail pointer in struct sk_buff!
197 memset(skb, 0, offsetof(struct sk_buff, tail));
198 skb->truesize = size + sizeof(struct sk_buff);
199 atomic_set(&skb->users, 1);
202 skb_reset_tail_pointer(skb);
203 skb->end = skb->tail + size;
204 /* make sure we initialize shinfo sequentially */
205 shinfo = skb_shinfo(skb);
206 atomic_set(&shinfo->dataref, 1);
207 shinfo->nr_frags = 0;
208 shinfo->gso_size = 0;
209 shinfo->gso_segs = 0;
210 shinfo->gso_type = 0;
211 shinfo->ip6_frag_id = 0;
212 shinfo->tx_flags.flags = 0;
213 shinfo->frag_list = NULL;
214 memset(&shinfo->hwtstamps, 0, sizeof(shinfo->hwtstamps));
217 struct sk_buff *child = skb + 1;
218 atomic_t *fclone_ref = (atomic_t *) (child + 1);
220 skb->fclone = SKB_FCLONE_ORIG;
221 atomic_set(fclone_ref, 1);
223 child->fclone = SKB_FCLONE_UNAVAILABLE;
228 kmem_cache_free(cache, skb);
232 EXPORT_SYMBOL(__alloc_skb);
235 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
236 * @dev: network device to receive on
237 * @length: length to allocate
238 * @gfp_mask: get_free_pages mask, passed to alloc_skb
240 * Allocate a new &sk_buff and assign it a usage count of one. The
241 * buffer has unspecified headroom built in. Users should allocate
242 * the headroom they think they need without accounting for the
243 * built in space. The built in space is used for optimisations.
245 * %NULL is returned if there is no free memory.
247 struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
248 unsigned int length, gfp_t gfp_mask)
250 int node = dev->dev.parent ? dev_to_node(dev->dev.parent) : -1;
253 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, node);
255 skb_reserve(skb, NET_SKB_PAD);
260 EXPORT_SYMBOL(__netdev_alloc_skb);
262 struct page *__netdev_alloc_page(struct net_device *dev, gfp_t gfp_mask)
264 int node = dev->dev.parent ? dev_to_node(dev->dev.parent) : -1;
267 page = alloc_pages_node(node, gfp_mask, 0);
270 EXPORT_SYMBOL(__netdev_alloc_page);
272 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
275 skb_fill_page_desc(skb, i, page, off, size);
277 skb->data_len += size;
278 skb->truesize += size;
280 EXPORT_SYMBOL(skb_add_rx_frag);
283 * dev_alloc_skb - allocate an skbuff for receiving
284 * @length: length to allocate
286 * Allocate a new &sk_buff and assign it a usage count of one. The
287 * buffer has unspecified headroom built in. Users should allocate
288 * the headroom they think they need without accounting for the
289 * built in space. The built in space is used for optimisations.
291 * %NULL is returned if there is no free memory. Although this function
292 * allocates memory it can be called from an interrupt.
294 struct sk_buff *dev_alloc_skb(unsigned int length)
297 * There is more code here than it seems:
298 * __dev_alloc_skb is an inline
300 return __dev_alloc_skb(length, GFP_ATOMIC);
302 EXPORT_SYMBOL(dev_alloc_skb);
304 static void skb_drop_list(struct sk_buff **listp)
306 struct sk_buff *list = *listp;
311 struct sk_buff *this = list;
317 static inline void skb_drop_fraglist(struct sk_buff *skb)
319 skb_drop_list(&skb_shinfo(skb)->frag_list);
322 static void skb_clone_fraglist(struct sk_buff *skb)
324 struct sk_buff *list;
326 for (list = skb_shinfo(skb)->frag_list; list; list = list->next)
330 static void skb_release_data(struct sk_buff *skb)
333 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
334 &skb_shinfo(skb)->dataref)) {
335 if (skb_shinfo(skb)->nr_frags) {
337 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
338 put_page(skb_shinfo(skb)->frags[i].page);
341 if (skb_shinfo(skb)->frag_list)
342 skb_drop_fraglist(skb);
349 * Free an skbuff by memory without cleaning the state.
351 static void kfree_skbmem(struct sk_buff *skb)
353 struct sk_buff *other;
354 atomic_t *fclone_ref;
356 switch (skb->fclone) {
357 case SKB_FCLONE_UNAVAILABLE:
358 kmem_cache_free(skbuff_head_cache, skb);
361 case SKB_FCLONE_ORIG:
362 fclone_ref = (atomic_t *) (skb + 2);
363 if (atomic_dec_and_test(fclone_ref))
364 kmem_cache_free(skbuff_fclone_cache, skb);
367 case SKB_FCLONE_CLONE:
368 fclone_ref = (atomic_t *) (skb + 1);
371 /* The clone portion is available for
372 * fast-cloning again.
374 skb->fclone = SKB_FCLONE_UNAVAILABLE;
376 if (atomic_dec_and_test(fclone_ref))
377 kmem_cache_free(skbuff_fclone_cache, other);
382 static void skb_release_head_state(struct sk_buff *skb)
384 dst_release(skb->dst);
386 secpath_put(skb->sp);
388 if (skb->destructor) {
390 skb->destructor(skb);
392 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
393 nf_conntrack_put(skb->nfct);
394 nf_conntrack_put_reasm(skb->nfct_reasm);
396 #ifdef CONFIG_BRIDGE_NETFILTER
397 nf_bridge_put(skb->nf_bridge);
399 /* XXX: IS this still necessary? - JHS */
400 #ifdef CONFIG_NET_SCHED
402 #ifdef CONFIG_NET_CLS_ACT
408 /* Free everything but the sk_buff shell. */
409 static void skb_release_all(struct sk_buff *skb)
411 skb_release_head_state(skb);
412 skb_release_data(skb);
416 * __kfree_skb - private function
419 * Free an sk_buff. Release anything attached to the buffer.
420 * Clean the state. This is an internal helper function. Users should
421 * always call kfree_skb
424 void __kfree_skb(struct sk_buff *skb)
426 skb_release_all(skb);
429 EXPORT_SYMBOL(__kfree_skb);
432 * kfree_skb - free an sk_buff
433 * @skb: buffer to free
435 * Drop a reference to the buffer and free it if the usage count has
438 void kfree_skb(struct sk_buff *skb)
442 if (likely(atomic_read(&skb->users) == 1))
444 else if (likely(!atomic_dec_and_test(&skb->users)))
446 trace_kfree_skb(skb, __builtin_return_address(0));
449 EXPORT_SYMBOL(kfree_skb);
452 * consume_skb - free an skbuff
453 * @skb: buffer to free
455 * Drop a ref to the buffer and free it if the usage count has hit zero
456 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
457 * is being dropped after a failure and notes that
459 void consume_skb(struct sk_buff *skb)
463 if (likely(atomic_read(&skb->users) == 1))
465 else if (likely(!atomic_dec_and_test(&skb->users)))
469 EXPORT_SYMBOL(consume_skb);
472 * skb_recycle_check - check if skb can be reused for receive
474 * @skb_size: minimum receive buffer size
476 * Checks that the skb passed in is not shared or cloned, and
477 * that it is linear and its head portion at least as large as
478 * skb_size so that it can be recycled as a receive buffer.
479 * If these conditions are met, this function does any necessary
480 * reference count dropping and cleans up the skbuff as if it
481 * just came from __alloc_skb().
483 int skb_recycle_check(struct sk_buff *skb, int skb_size)
485 struct skb_shared_info *shinfo;
487 if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
490 skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
491 if (skb_end_pointer(skb) - skb->head < skb_size)
494 if (skb_shared(skb) || skb_cloned(skb))
497 skb_release_head_state(skb);
498 shinfo = skb_shinfo(skb);
499 atomic_set(&shinfo->dataref, 1);
500 shinfo->nr_frags = 0;
501 shinfo->gso_size = 0;
502 shinfo->gso_segs = 0;
503 shinfo->gso_type = 0;
504 shinfo->ip6_frag_id = 0;
505 shinfo->tx_flags.flags = 0;
506 shinfo->frag_list = NULL;
507 memset(&shinfo->hwtstamps, 0, sizeof(shinfo->hwtstamps));
509 memset(skb, 0, offsetof(struct sk_buff, tail));
510 skb->data = skb->head + NET_SKB_PAD;
511 skb_reset_tail_pointer(skb);
515 EXPORT_SYMBOL(skb_recycle_check);
517 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
519 new->tstamp = old->tstamp;
521 new->transport_header = old->transport_header;
522 new->network_header = old->network_header;
523 new->mac_header = old->mac_header;
524 new->dst = dst_clone(old->dst);
526 new->sp = secpath_get(old->sp);
528 memcpy(new->cb, old->cb, sizeof(old->cb));
529 new->csum = old->csum;
530 new->local_df = old->local_df;
531 new->pkt_type = old->pkt_type;
532 new->ip_summed = old->ip_summed;
533 skb_copy_queue_mapping(new, old);
534 new->priority = old->priority;
535 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
536 new->ipvs_property = old->ipvs_property;
538 new->protocol = old->protocol;
539 new->mark = old->mark;
542 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
543 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
544 new->nf_trace = old->nf_trace;
546 #ifdef CONFIG_NET_SCHED
547 new->tc_index = old->tc_index;
548 #ifdef CONFIG_NET_CLS_ACT
549 new->tc_verd = old->tc_verd;
552 new->vlan_tci = old->vlan_tci;
553 #if defined(CONFIG_MAC80211) || defined(CONFIG_MAC80211_MODULE)
554 new->do_not_encrypt = old->do_not_encrypt;
555 new->requeue = old->requeue;
558 skb_copy_secmark(new, old);
562 * You should not add any new code to this function. Add it to
563 * __copy_skb_header above instead.
565 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
567 #define C(x) n->x = skb->x
569 n->next = n->prev = NULL;
571 __copy_skb_header(n, skb);
576 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
579 n->destructor = NULL;
585 atomic_set(&n->users, 1);
587 atomic_inc(&(skb_shinfo(skb)->dataref));
595 * skb_morph - morph one skb into another
596 * @dst: the skb to receive the contents
597 * @src: the skb to supply the contents
599 * This is identical to skb_clone except that the target skb is
600 * supplied by the user.
602 * The target skb is returned upon exit.
604 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
606 skb_release_all(dst);
607 return __skb_clone(dst, src);
609 EXPORT_SYMBOL_GPL(skb_morph);
612 * skb_clone - duplicate an sk_buff
613 * @skb: buffer to clone
614 * @gfp_mask: allocation priority
616 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
617 * copies share the same packet data but not structure. The new
618 * buffer has a reference count of 1. If the allocation fails the
619 * function returns %NULL otherwise the new buffer is returned.
621 * If this function is called from an interrupt gfp_mask() must be
625 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
630 if (skb->fclone == SKB_FCLONE_ORIG &&
631 n->fclone == SKB_FCLONE_UNAVAILABLE) {
632 atomic_t *fclone_ref = (atomic_t *) (n + 1);
633 n->fclone = SKB_FCLONE_CLONE;
634 atomic_inc(fclone_ref);
636 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
639 n->fclone = SKB_FCLONE_UNAVAILABLE;
642 return __skb_clone(n, skb);
644 EXPORT_SYMBOL(skb_clone);
646 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
648 #ifndef NET_SKBUFF_DATA_USES_OFFSET
650 * Shift between the two data areas in bytes
652 unsigned long offset = new->data - old->data;
655 __copy_skb_header(new, old);
657 #ifndef NET_SKBUFF_DATA_USES_OFFSET
658 /* {transport,network,mac}_header are relative to skb->head */
659 new->transport_header += offset;
660 new->network_header += offset;
661 new->mac_header += offset;
663 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
664 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
665 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
669 * skb_copy - create private copy of an sk_buff
670 * @skb: buffer to copy
671 * @gfp_mask: allocation priority
673 * Make a copy of both an &sk_buff and its data. This is used when the
674 * caller wishes to modify the data and needs a private copy of the
675 * data to alter. Returns %NULL on failure or the pointer to the buffer
676 * on success. The returned buffer has a reference count of 1.
678 * As by-product this function converts non-linear &sk_buff to linear
679 * one, so that &sk_buff becomes completely private and caller is allowed
680 * to modify all the data of returned buffer. This means that this
681 * function is not recommended for use in circumstances when only
682 * header is going to be modified. Use pskb_copy() instead.
685 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
687 int headerlen = skb->data - skb->head;
689 * Allocate the copy buffer
692 #ifdef NET_SKBUFF_DATA_USES_OFFSET
693 n = alloc_skb(skb->end + skb->data_len, gfp_mask);
695 n = alloc_skb(skb->end - skb->head + skb->data_len, gfp_mask);
700 /* Set the data pointer */
701 skb_reserve(n, headerlen);
702 /* Set the tail pointer and length */
703 skb_put(n, skb->len);
705 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
708 copy_skb_header(n, skb);
711 EXPORT_SYMBOL(skb_copy);
714 * pskb_copy - create copy of an sk_buff with private head.
715 * @skb: buffer to copy
716 * @gfp_mask: allocation priority
718 * Make a copy of both an &sk_buff and part of its data, located
719 * in header. Fragmented data remain shared. This is used when
720 * the caller wishes to modify only header of &sk_buff and needs
721 * private copy of the header to alter. Returns %NULL on failure
722 * or the pointer to the buffer on success.
723 * The returned buffer has a reference count of 1.
726 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
729 * Allocate the copy buffer
732 #ifdef NET_SKBUFF_DATA_USES_OFFSET
733 n = alloc_skb(skb->end, gfp_mask);
735 n = alloc_skb(skb->end - skb->head, gfp_mask);
740 /* Set the data pointer */
741 skb_reserve(n, skb->data - skb->head);
742 /* Set the tail pointer and length */
743 skb_put(n, skb_headlen(skb));
745 skb_copy_from_linear_data(skb, n->data, n->len);
747 n->truesize += skb->data_len;
748 n->data_len = skb->data_len;
751 if (skb_shinfo(skb)->nr_frags) {
754 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
755 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
756 get_page(skb_shinfo(n)->frags[i].page);
758 skb_shinfo(n)->nr_frags = i;
761 if (skb_shinfo(skb)->frag_list) {
762 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
763 skb_clone_fraglist(n);
766 copy_skb_header(n, skb);
770 EXPORT_SYMBOL(pskb_copy);
773 * pskb_expand_head - reallocate header of &sk_buff
774 * @skb: buffer to reallocate
775 * @nhead: room to add at head
776 * @ntail: room to add at tail
777 * @gfp_mask: allocation priority
779 * Expands (or creates identical copy, if &nhead and &ntail are zero)
780 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
781 * reference count of 1. Returns zero in the case of success or error,
782 * if expansion failed. In the last case, &sk_buff is not changed.
784 * All the pointers pointing into skb header may change and must be
785 * reloaded after call to this function.
788 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
793 #ifdef NET_SKBUFF_DATA_USES_OFFSET
794 int size = nhead + skb->end + ntail;
796 int size = nhead + (skb->end - skb->head) + ntail;
805 size = SKB_DATA_ALIGN(size);
807 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
811 /* Copy only real data... and, alas, header. This should be
812 * optimized for the cases when header is void. */
813 #ifdef NET_SKBUFF_DATA_USES_OFFSET
814 memcpy(data + nhead, skb->head, skb->tail);
816 memcpy(data + nhead, skb->head, skb->tail - skb->head);
818 memcpy(data + size, skb_end_pointer(skb),
819 sizeof(struct skb_shared_info));
821 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
822 get_page(skb_shinfo(skb)->frags[i].page);
824 if (skb_shinfo(skb)->frag_list)
825 skb_clone_fraglist(skb);
827 skb_release_data(skb);
829 off = (data + nhead) - skb->head;
833 #ifdef NET_SKBUFF_DATA_USES_OFFSET
837 skb->end = skb->head + size;
839 /* {transport,network,mac}_header and tail are relative to skb->head */
841 skb->transport_header += off;
842 skb->network_header += off;
843 skb->mac_header += off;
844 skb->csum_start += nhead;
848 atomic_set(&skb_shinfo(skb)->dataref, 1);
854 EXPORT_SYMBOL(pskb_expand_head);
856 /* Make private copy of skb with writable head and some headroom */
858 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
860 struct sk_buff *skb2;
861 int delta = headroom - skb_headroom(skb);
864 skb2 = pskb_copy(skb, GFP_ATOMIC);
866 skb2 = skb_clone(skb, GFP_ATOMIC);
867 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
875 EXPORT_SYMBOL(skb_realloc_headroom);
878 * skb_copy_expand - copy and expand sk_buff
879 * @skb: buffer to copy
880 * @newheadroom: new free bytes at head
881 * @newtailroom: new free bytes at tail
882 * @gfp_mask: allocation priority
884 * Make a copy of both an &sk_buff and its data and while doing so
885 * allocate additional space.
887 * This is used when the caller wishes to modify the data and needs a
888 * private copy of the data to alter as well as more space for new fields.
889 * Returns %NULL on failure or the pointer to the buffer
890 * on success. The returned buffer has a reference count of 1.
892 * You must pass %GFP_ATOMIC as the allocation priority if this function
893 * is called from an interrupt.
895 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
896 int newheadroom, int newtailroom,
900 * Allocate the copy buffer
902 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
904 int oldheadroom = skb_headroom(skb);
905 int head_copy_len, head_copy_off;
911 skb_reserve(n, newheadroom);
913 /* Set the tail pointer and length */
914 skb_put(n, skb->len);
916 head_copy_len = oldheadroom;
918 if (newheadroom <= head_copy_len)
919 head_copy_len = newheadroom;
921 head_copy_off = newheadroom - head_copy_len;
923 /* Copy the linear header and data. */
924 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
925 skb->len + head_copy_len))
928 copy_skb_header(n, skb);
930 off = newheadroom - oldheadroom;
931 n->csum_start += off;
932 #ifdef NET_SKBUFF_DATA_USES_OFFSET
933 n->transport_header += off;
934 n->network_header += off;
935 n->mac_header += off;
940 EXPORT_SYMBOL(skb_copy_expand);
943 * skb_pad - zero pad the tail of an skb
944 * @skb: buffer to pad
947 * Ensure that a buffer is followed by a padding area that is zero
948 * filled. Used by network drivers which may DMA or transfer data
949 * beyond the buffer end onto the wire.
951 * May return error in out of memory cases. The skb is freed on error.
954 int skb_pad(struct sk_buff *skb, int pad)
959 /* If the skbuff is non linear tailroom is always zero.. */
960 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
961 memset(skb->data+skb->len, 0, pad);
965 ntail = skb->data_len + pad - (skb->end - skb->tail);
966 if (likely(skb_cloned(skb) || ntail > 0)) {
967 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
972 /* FIXME: The use of this function with non-linear skb's really needs
975 err = skb_linearize(skb);
979 memset(skb->data + skb->len, 0, pad);
986 EXPORT_SYMBOL(skb_pad);
989 * skb_put - add data to a buffer
990 * @skb: buffer to use
991 * @len: amount of data to add
993 * This function extends the used data area of the buffer. If this would
994 * exceed the total buffer size the kernel will panic. A pointer to the
995 * first byte of the extra data is returned.
997 unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
999 unsigned char *tmp = skb_tail_pointer(skb);
1000 SKB_LINEAR_ASSERT(skb);
1003 if (unlikely(skb->tail > skb->end))
1004 skb_over_panic(skb, len, __builtin_return_address(0));
1007 EXPORT_SYMBOL(skb_put);
1010 * skb_push - add data to the start of a buffer
1011 * @skb: buffer to use
1012 * @len: amount of data to add
1014 * This function extends the used data area of the buffer at the buffer
1015 * start. If this would exceed the total buffer headroom the kernel will
1016 * panic. A pointer to the first byte of the extra data is returned.
1018 unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1022 if (unlikely(skb->data<skb->head))
1023 skb_under_panic(skb, len, __builtin_return_address(0));
1026 EXPORT_SYMBOL(skb_push);
1029 * skb_pull - remove data from the start of a buffer
1030 * @skb: buffer to use
1031 * @len: amount of data to remove
1033 * This function removes data from the start of a buffer, returning
1034 * the memory to the headroom. A pointer to the next data in the buffer
1035 * is returned. Once the data has been pulled future pushes will overwrite
1038 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1040 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1042 EXPORT_SYMBOL(skb_pull);
1045 * skb_trim - remove end from a buffer
1046 * @skb: buffer to alter
1049 * Cut the length of a buffer down by removing data from the tail. If
1050 * the buffer is already under the length specified it is not modified.
1051 * The skb must be linear.
1053 void skb_trim(struct sk_buff *skb, unsigned int len)
1056 __skb_trim(skb, len);
1058 EXPORT_SYMBOL(skb_trim);
1060 /* Trims skb to length len. It can change skb pointers.
1063 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1065 struct sk_buff **fragp;
1066 struct sk_buff *frag;
1067 int offset = skb_headlen(skb);
1068 int nfrags = skb_shinfo(skb)->nr_frags;
1072 if (skb_cloned(skb) &&
1073 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1080 for (; i < nfrags; i++) {
1081 int end = offset + skb_shinfo(skb)->frags[i].size;
1088 skb_shinfo(skb)->frags[i++].size = len - offset;
1091 skb_shinfo(skb)->nr_frags = i;
1093 for (; i < nfrags; i++)
1094 put_page(skb_shinfo(skb)->frags[i].page);
1096 if (skb_shinfo(skb)->frag_list)
1097 skb_drop_fraglist(skb);
1101 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1102 fragp = &frag->next) {
1103 int end = offset + frag->len;
1105 if (skb_shared(frag)) {
1106 struct sk_buff *nfrag;
1108 nfrag = skb_clone(frag, GFP_ATOMIC);
1109 if (unlikely(!nfrag))
1112 nfrag->next = frag->next;
1124 unlikely((err = pskb_trim(frag, len - offset))))
1128 skb_drop_list(&frag->next);
1133 if (len > skb_headlen(skb)) {
1134 skb->data_len -= skb->len - len;
1139 skb_set_tail_pointer(skb, len);
1144 EXPORT_SYMBOL(___pskb_trim);
1147 * __pskb_pull_tail - advance tail of skb header
1148 * @skb: buffer to reallocate
1149 * @delta: number of bytes to advance tail
1151 * The function makes a sense only on a fragmented &sk_buff,
1152 * it expands header moving its tail forward and copying necessary
1153 * data from fragmented part.
1155 * &sk_buff MUST have reference count of 1.
1157 * Returns %NULL (and &sk_buff does not change) if pull failed
1158 * or value of new tail of skb in the case of success.
1160 * All the pointers pointing into skb header may change and must be
1161 * reloaded after call to this function.
1164 /* Moves tail of skb head forward, copying data from fragmented part,
1165 * when it is necessary.
1166 * 1. It may fail due to malloc failure.
1167 * 2. It may change skb pointers.
1169 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1171 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1173 /* If skb has not enough free space at tail, get new one
1174 * plus 128 bytes for future expansions. If we have enough
1175 * room at tail, reallocate without expansion only if skb is cloned.
1177 int i, k, eat = (skb->tail + delta) - skb->end;
1179 if (eat > 0 || skb_cloned(skb)) {
1180 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1185 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1188 /* Optimization: no fragments, no reasons to preestimate
1189 * size of pulled pages. Superb.
1191 if (!skb_shinfo(skb)->frag_list)
1194 /* Estimate size of pulled pages. */
1196 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1197 if (skb_shinfo(skb)->frags[i].size >= eat)
1199 eat -= skb_shinfo(skb)->frags[i].size;
1202 /* If we need update frag list, we are in troubles.
1203 * Certainly, it possible to add an offset to skb data,
1204 * but taking into account that pulling is expected to
1205 * be very rare operation, it is worth to fight against
1206 * further bloating skb head and crucify ourselves here instead.
1207 * Pure masohism, indeed. 8)8)
1210 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1211 struct sk_buff *clone = NULL;
1212 struct sk_buff *insp = NULL;
1217 if (list->len <= eat) {
1218 /* Eaten as whole. */
1223 /* Eaten partially. */
1225 if (skb_shared(list)) {
1226 /* Sucks! We need to fork list. :-( */
1227 clone = skb_clone(list, GFP_ATOMIC);
1233 /* This may be pulled without
1237 if (!pskb_pull(list, eat)) {
1245 /* Free pulled out fragments. */
1246 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1247 skb_shinfo(skb)->frag_list = list->next;
1250 /* And insert new clone at head. */
1253 skb_shinfo(skb)->frag_list = clone;
1256 /* Success! Now we may commit changes to skb data. */
1261 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1262 if (skb_shinfo(skb)->frags[i].size <= eat) {
1263 put_page(skb_shinfo(skb)->frags[i].page);
1264 eat -= skb_shinfo(skb)->frags[i].size;
1266 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1268 skb_shinfo(skb)->frags[k].page_offset += eat;
1269 skb_shinfo(skb)->frags[k].size -= eat;
1275 skb_shinfo(skb)->nr_frags = k;
1278 skb->data_len -= delta;
1280 return skb_tail_pointer(skb);
1282 EXPORT_SYMBOL(__pskb_pull_tail);
1284 /* Copy some data bits from skb to kernel buffer. */
1286 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1289 int start = skb_headlen(skb);
1291 if (offset > (int)skb->len - len)
1295 if ((copy = start - offset) > 0) {
1298 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1299 if ((len -= copy) == 0)
1305 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1308 WARN_ON(start > offset + len);
1310 end = start + skb_shinfo(skb)->frags[i].size;
1311 if ((copy = end - offset) > 0) {
1317 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1319 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1320 offset - start, copy);
1321 kunmap_skb_frag(vaddr);
1323 if ((len -= copy) == 0)
1331 if (skb_shinfo(skb)->frag_list) {
1332 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1334 for (; list; list = list->next) {
1337 WARN_ON(start > offset + len);
1339 end = start + list->len;
1340 if ((copy = end - offset) > 0) {
1343 if (skb_copy_bits(list, offset - start,
1346 if ((len -= copy) == 0)
1360 EXPORT_SYMBOL(skb_copy_bits);
1363 * Callback from splice_to_pipe(), if we need to release some pages
1364 * at the end of the spd in case we error'ed out in filling the pipe.
1366 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1368 put_page(spd->pages[i]);
1371 static inline struct page *linear_to_page(struct page *page, unsigned int *len,
1372 unsigned int *offset,
1373 struct sk_buff *skb, struct sock *sk)
1375 struct page *p = sk->sk_sndmsg_page;
1380 p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
1384 off = sk->sk_sndmsg_off = 0;
1385 /* hold one ref to this page until it's full */
1389 off = sk->sk_sndmsg_off;
1390 mlen = PAGE_SIZE - off;
1391 if (mlen < 64 && mlen < *len) {
1396 *len = min_t(unsigned int, *len, mlen);
1399 memcpy(page_address(p) + off, page_address(page) + *offset, *len);
1400 sk->sk_sndmsg_off += *len;
1408 * Fill page/offset/length into spd, if it can hold more pages.
1410 static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page,
1411 unsigned int *len, unsigned int offset,
1412 struct sk_buff *skb, int linear,
1415 if (unlikely(spd->nr_pages == PIPE_BUFFERS))
1419 page = linear_to_page(page, len, &offset, skb, sk);
1425 spd->pages[spd->nr_pages] = page;
1426 spd->partial[spd->nr_pages].len = *len;
1427 spd->partial[spd->nr_pages].offset = offset;
1433 static inline void __segment_seek(struct page **page, unsigned int *poff,
1434 unsigned int *plen, unsigned int off)
1439 n = *poff / PAGE_SIZE;
1441 *page = nth_page(*page, n);
1443 *poff = *poff % PAGE_SIZE;
1447 static inline int __splice_segment(struct page *page, unsigned int poff,
1448 unsigned int plen, unsigned int *off,
1449 unsigned int *len, struct sk_buff *skb,
1450 struct splice_pipe_desc *spd, int linear,
1456 /* skip this segment if already processed */
1462 /* ignore any bits we already processed */
1464 __segment_seek(&page, &poff, &plen, *off);
1469 unsigned int flen = min(*len, plen);
1471 /* the linear region may spread across several pages */
1472 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
1474 if (spd_fill_page(spd, page, &flen, poff, skb, linear, sk))
1477 __segment_seek(&page, &poff, &plen, flen);
1480 } while (*len && plen);
1486 * Map linear and fragment data from the skb to spd. It reports failure if the
1487 * pipe is full or if we already spliced the requested length.
1489 static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
1490 unsigned int *len, struct splice_pipe_desc *spd,
1496 * map the linear part
1498 if (__splice_segment(virt_to_page(skb->data),
1499 (unsigned long) skb->data & (PAGE_SIZE - 1),
1501 offset, len, skb, spd, 1, sk))
1505 * then map the fragments
1507 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1508 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1510 if (__splice_segment(f->page, f->page_offset, f->size,
1511 offset, len, skb, spd, 0, sk))
1519 * Map data from the skb to a pipe. Should handle both the linear part,
1520 * the fragments, and the frag list. It does NOT handle frag lists within
1521 * the frag list, if such a thing exists. We'd probably need to recurse to
1522 * handle that cleanly.
1524 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1525 struct pipe_inode_info *pipe, unsigned int tlen,
1528 struct partial_page partial[PIPE_BUFFERS];
1529 struct page *pages[PIPE_BUFFERS];
1530 struct splice_pipe_desc spd = {
1534 .ops = &sock_pipe_buf_ops,
1535 .spd_release = sock_spd_release,
1537 struct sock *sk = skb->sk;
1540 * __skb_splice_bits() only fails if the output has no room left,
1541 * so no point in going over the frag_list for the error case.
1543 if (__skb_splice_bits(skb, &offset, &tlen, &spd, sk))
1549 * now see if we have a frag_list to map
1551 if (skb_shinfo(skb)->frag_list) {
1552 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1554 for (; list && tlen; list = list->next) {
1555 if (__skb_splice_bits(list, &offset, &tlen, &spd, sk))
1565 * Drop the socket lock, otherwise we have reverse
1566 * locking dependencies between sk_lock and i_mutex
1567 * here as compared to sendfile(). We enter here
1568 * with the socket lock held, and splice_to_pipe() will
1569 * grab the pipe inode lock. For sendfile() emulation,
1570 * we call into ->sendpage() with the i_mutex lock held
1571 * and networking will grab the socket lock.
1574 ret = splice_to_pipe(pipe, &spd);
1583 * skb_store_bits - store bits from kernel buffer to skb
1584 * @skb: destination buffer
1585 * @offset: offset in destination
1586 * @from: source buffer
1587 * @len: number of bytes to copy
1589 * Copy the specified number of bytes from the source buffer to the
1590 * destination skb. This function handles all the messy bits of
1591 * traversing fragment lists and such.
1594 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1597 int start = skb_headlen(skb);
1599 if (offset > (int)skb->len - len)
1602 if ((copy = start - offset) > 0) {
1605 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1606 if ((len -= copy) == 0)
1612 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1613 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1616 WARN_ON(start > offset + len);
1618 end = start + frag->size;
1619 if ((copy = end - offset) > 0) {
1625 vaddr = kmap_skb_frag(frag);
1626 memcpy(vaddr + frag->page_offset + offset - start,
1628 kunmap_skb_frag(vaddr);
1630 if ((len -= copy) == 0)
1638 if (skb_shinfo(skb)->frag_list) {
1639 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1641 for (; list; list = list->next) {
1644 WARN_ON(start > offset + len);
1646 end = start + list->len;
1647 if ((copy = end - offset) > 0) {
1650 if (skb_store_bits(list, offset - start,
1653 if ((len -= copy) == 0)
1667 EXPORT_SYMBOL(skb_store_bits);
1669 /* Checksum skb data. */
1671 __wsum skb_checksum(const struct sk_buff *skb, int offset,
1672 int len, __wsum csum)
1674 int start = skb_headlen(skb);
1675 int i, copy = start - offset;
1678 /* Checksum header. */
1682 csum = csum_partial(skb->data + offset, copy, csum);
1683 if ((len -= copy) == 0)
1689 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1692 WARN_ON(start > offset + len);
1694 end = start + skb_shinfo(skb)->frags[i].size;
1695 if ((copy = end - offset) > 0) {
1698 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1702 vaddr = kmap_skb_frag(frag);
1703 csum2 = csum_partial(vaddr + frag->page_offset +
1704 offset - start, copy, 0);
1705 kunmap_skb_frag(vaddr);
1706 csum = csum_block_add(csum, csum2, pos);
1715 if (skb_shinfo(skb)->frag_list) {
1716 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1718 for (; list; list = list->next) {
1721 WARN_ON(start > offset + len);
1723 end = start + list->len;
1724 if ((copy = end - offset) > 0) {
1728 csum2 = skb_checksum(list, offset - start,
1730 csum = csum_block_add(csum, csum2, pos);
1731 if ((len -= copy) == 0)
1743 EXPORT_SYMBOL(skb_checksum);
1745 /* Both of above in one bottle. */
1747 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1748 u8 *to, int len, __wsum csum)
1750 int start = skb_headlen(skb);
1751 int i, copy = start - offset;
1758 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1760 if ((len -= copy) == 0)
1767 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1770 WARN_ON(start > offset + len);
1772 end = start + skb_shinfo(skb)->frags[i].size;
1773 if ((copy = end - offset) > 0) {
1776 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1780 vaddr = kmap_skb_frag(frag);
1781 csum2 = csum_partial_copy_nocheck(vaddr +
1785 kunmap_skb_frag(vaddr);
1786 csum = csum_block_add(csum, csum2, pos);
1796 if (skb_shinfo(skb)->frag_list) {
1797 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1799 for (; list; list = list->next) {
1803 WARN_ON(start > offset + len);
1805 end = start + list->len;
1806 if ((copy = end - offset) > 0) {
1809 csum2 = skb_copy_and_csum_bits(list,
1812 csum = csum_block_add(csum, csum2, pos);
1813 if ((len -= copy) == 0)
1825 EXPORT_SYMBOL(skb_copy_and_csum_bits);
1827 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1832 if (skb->ip_summed == CHECKSUM_PARTIAL)
1833 csstart = skb->csum_start - skb_headroom(skb);
1835 csstart = skb_headlen(skb);
1837 BUG_ON(csstart > skb_headlen(skb));
1839 skb_copy_from_linear_data(skb, to, csstart);
1842 if (csstart != skb->len)
1843 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1844 skb->len - csstart, 0);
1846 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1847 long csstuff = csstart + skb->csum_offset;
1849 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
1852 EXPORT_SYMBOL(skb_copy_and_csum_dev);
1855 * skb_dequeue - remove from the head of the queue
1856 * @list: list to dequeue from
1858 * Remove the head of the list. The list lock is taken so the function
1859 * may be used safely with other locking list functions. The head item is
1860 * returned or %NULL if the list is empty.
1863 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1865 unsigned long flags;
1866 struct sk_buff *result;
1868 spin_lock_irqsave(&list->lock, flags);
1869 result = __skb_dequeue(list);
1870 spin_unlock_irqrestore(&list->lock, flags);
1873 EXPORT_SYMBOL(skb_dequeue);
1876 * skb_dequeue_tail - remove from the tail of the queue
1877 * @list: list to dequeue from
1879 * Remove the tail of the list. The list lock is taken so the function
1880 * may be used safely with other locking list functions. The tail item is
1881 * returned or %NULL if the list is empty.
1883 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1885 unsigned long flags;
1886 struct sk_buff *result;
1888 spin_lock_irqsave(&list->lock, flags);
1889 result = __skb_dequeue_tail(list);
1890 spin_unlock_irqrestore(&list->lock, flags);
1893 EXPORT_SYMBOL(skb_dequeue_tail);
1896 * skb_queue_purge - empty a list
1897 * @list: list to empty
1899 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1900 * the list and one reference dropped. This function takes the list
1901 * lock and is atomic with respect to other list locking functions.
1903 void skb_queue_purge(struct sk_buff_head *list)
1905 struct sk_buff *skb;
1906 while ((skb = skb_dequeue(list)) != NULL)
1909 EXPORT_SYMBOL(skb_queue_purge);
1912 * skb_queue_head - queue a buffer at the list head
1913 * @list: list to use
1914 * @newsk: buffer to queue
1916 * Queue a buffer at the start of the list. This function takes the
1917 * list lock and can be used safely with other locking &sk_buff functions
1920 * A buffer cannot be placed on two lists at the same time.
1922 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
1924 unsigned long flags;
1926 spin_lock_irqsave(&list->lock, flags);
1927 __skb_queue_head(list, newsk);
1928 spin_unlock_irqrestore(&list->lock, flags);
1930 EXPORT_SYMBOL(skb_queue_head);
1933 * skb_queue_tail - queue a buffer at the list tail
1934 * @list: list to use
1935 * @newsk: buffer to queue
1937 * Queue a buffer at the tail of the list. This function takes the
1938 * list lock and can be used safely with other locking &sk_buff functions
1941 * A buffer cannot be placed on two lists at the same time.
1943 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
1945 unsigned long flags;
1947 spin_lock_irqsave(&list->lock, flags);
1948 __skb_queue_tail(list, newsk);
1949 spin_unlock_irqrestore(&list->lock, flags);
1951 EXPORT_SYMBOL(skb_queue_tail);
1954 * skb_unlink - remove a buffer from a list
1955 * @skb: buffer to remove
1956 * @list: list to use
1958 * Remove a packet from a list. The list locks are taken and this
1959 * function is atomic with respect to other list locked calls
1961 * You must know what list the SKB is on.
1963 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1965 unsigned long flags;
1967 spin_lock_irqsave(&list->lock, flags);
1968 __skb_unlink(skb, list);
1969 spin_unlock_irqrestore(&list->lock, flags);
1971 EXPORT_SYMBOL(skb_unlink);
1974 * skb_append - append a buffer
1975 * @old: buffer to insert after
1976 * @newsk: buffer to insert
1977 * @list: list to use
1979 * Place a packet after a given packet in a list. The list locks are taken
1980 * and this function is atomic with respect to other list locked calls.
1981 * A buffer cannot be placed on two lists at the same time.
1983 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1985 unsigned long flags;
1987 spin_lock_irqsave(&list->lock, flags);
1988 __skb_queue_after(list, old, newsk);
1989 spin_unlock_irqrestore(&list->lock, flags);
1991 EXPORT_SYMBOL(skb_append);
1994 * skb_insert - insert a buffer
1995 * @old: buffer to insert before
1996 * @newsk: buffer to insert
1997 * @list: list to use
1999 * Place a packet before a given packet in a list. The list locks are
2000 * taken and this function is atomic with respect to other list locked
2003 * A buffer cannot be placed on two lists at the same time.
2005 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2007 unsigned long flags;
2009 spin_lock_irqsave(&list->lock, flags);
2010 __skb_insert(newsk, old->prev, old, list);
2011 spin_unlock_irqrestore(&list->lock, flags);
2013 EXPORT_SYMBOL(skb_insert);
2015 static inline void skb_split_inside_header(struct sk_buff *skb,
2016 struct sk_buff* skb1,
2017 const u32 len, const int pos)
2021 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2023 /* And move data appendix as is. */
2024 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2025 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2027 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2028 skb_shinfo(skb)->nr_frags = 0;
2029 skb1->data_len = skb->data_len;
2030 skb1->len += skb1->data_len;
2033 skb_set_tail_pointer(skb, len);
2036 static inline void skb_split_no_header(struct sk_buff *skb,
2037 struct sk_buff* skb1,
2038 const u32 len, int pos)
2041 const int nfrags = skb_shinfo(skb)->nr_frags;
2043 skb_shinfo(skb)->nr_frags = 0;
2044 skb1->len = skb1->data_len = skb->len - len;
2046 skb->data_len = len - pos;
2048 for (i = 0; i < nfrags; i++) {
2049 int size = skb_shinfo(skb)->frags[i].size;
2051 if (pos + size > len) {
2052 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2056 * We have two variants in this case:
2057 * 1. Move all the frag to the second
2058 * part, if it is possible. F.e.
2059 * this approach is mandatory for TUX,
2060 * where splitting is expensive.
2061 * 2. Split is accurately. We make this.
2063 get_page(skb_shinfo(skb)->frags[i].page);
2064 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2065 skb_shinfo(skb1)->frags[0].size -= len - pos;
2066 skb_shinfo(skb)->frags[i].size = len - pos;
2067 skb_shinfo(skb)->nr_frags++;
2071 skb_shinfo(skb)->nr_frags++;
2074 skb_shinfo(skb1)->nr_frags = k;
2078 * skb_split - Split fragmented skb to two parts at length len.
2079 * @skb: the buffer to split
2080 * @skb1: the buffer to receive the second part
2081 * @len: new length for skb
2083 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2085 int pos = skb_headlen(skb);
2087 if (len < pos) /* Split line is inside header. */
2088 skb_split_inside_header(skb, skb1, len, pos);
2089 else /* Second chunk has no header, nothing to copy. */
2090 skb_split_no_header(skb, skb1, len, pos);
2092 EXPORT_SYMBOL(skb_split);
2094 /* Shifting from/to a cloned skb is a no-go.
2096 * Caller cannot keep skb_shinfo related pointers past calling here!
2098 static int skb_prepare_for_shift(struct sk_buff *skb)
2100 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2104 * skb_shift - Shifts paged data partially from skb to another
2105 * @tgt: buffer into which tail data gets added
2106 * @skb: buffer from which the paged data comes from
2107 * @shiftlen: shift up to this many bytes
2109 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2110 * the length of the skb, from tgt to skb. Returns number bytes shifted.
2111 * It's up to caller to free skb if everything was shifted.
2113 * If @tgt runs out of frags, the whole operation is aborted.
2115 * Skb cannot include anything else but paged data while tgt is allowed
2116 * to have non-paged data as well.
2118 * TODO: full sized shift could be optimized but that would need
2119 * specialized skb free'er to handle frags without up-to-date nr_frags.
2121 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2123 int from, to, merge, todo;
2124 struct skb_frag_struct *fragfrom, *fragto;
2126 BUG_ON(shiftlen > skb->len);
2127 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */
2131 to = skb_shinfo(tgt)->nr_frags;
2132 fragfrom = &skb_shinfo(skb)->frags[from];
2134 /* Actual merge is delayed until the point when we know we can
2135 * commit all, so that we don't have to undo partial changes
2138 !skb_can_coalesce(tgt, to, fragfrom->page, fragfrom->page_offset)) {
2143 todo -= fragfrom->size;
2145 if (skb_prepare_for_shift(skb) ||
2146 skb_prepare_for_shift(tgt))
2149 /* All previous frag pointers might be stale! */
2150 fragfrom = &skb_shinfo(skb)->frags[from];
2151 fragto = &skb_shinfo(tgt)->frags[merge];
2153 fragto->size += shiftlen;
2154 fragfrom->size -= shiftlen;
2155 fragfrom->page_offset += shiftlen;
2163 /* Skip full, not-fitting skb to avoid expensive operations */
2164 if ((shiftlen == skb->len) &&
2165 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2168 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2171 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2172 if (to == MAX_SKB_FRAGS)
2175 fragfrom = &skb_shinfo(skb)->frags[from];
2176 fragto = &skb_shinfo(tgt)->frags[to];
2178 if (todo >= fragfrom->size) {
2179 *fragto = *fragfrom;
2180 todo -= fragfrom->size;
2185 get_page(fragfrom->page);
2186 fragto->page = fragfrom->page;
2187 fragto->page_offset = fragfrom->page_offset;
2188 fragto->size = todo;
2190 fragfrom->page_offset += todo;
2191 fragfrom->size -= todo;
2199 /* Ready to "commit" this state change to tgt */
2200 skb_shinfo(tgt)->nr_frags = to;
2203 fragfrom = &skb_shinfo(skb)->frags[0];
2204 fragto = &skb_shinfo(tgt)->frags[merge];
2206 fragto->size += fragfrom->size;
2207 put_page(fragfrom->page);
2210 /* Reposition in the original skb */
2212 while (from < skb_shinfo(skb)->nr_frags)
2213 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2214 skb_shinfo(skb)->nr_frags = to;
2216 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2219 /* Most likely the tgt won't ever need its checksum anymore, skb on
2220 * the other hand might need it if it needs to be resent
2222 tgt->ip_summed = CHECKSUM_PARTIAL;
2223 skb->ip_summed = CHECKSUM_PARTIAL;
2225 /* Yak, is it really working this way? Some helper please? */
2226 skb->len -= shiftlen;
2227 skb->data_len -= shiftlen;
2228 skb->truesize -= shiftlen;
2229 tgt->len += shiftlen;
2230 tgt->data_len += shiftlen;
2231 tgt->truesize += shiftlen;
2237 * skb_prepare_seq_read - Prepare a sequential read of skb data
2238 * @skb: the buffer to read
2239 * @from: lower offset of data to be read
2240 * @to: upper offset of data to be read
2241 * @st: state variable
2243 * Initializes the specified state variable. Must be called before
2244 * invoking skb_seq_read() for the first time.
2246 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2247 unsigned int to, struct skb_seq_state *st)
2249 st->lower_offset = from;
2250 st->upper_offset = to;
2251 st->root_skb = st->cur_skb = skb;
2252 st->frag_idx = st->stepped_offset = 0;
2253 st->frag_data = NULL;
2255 EXPORT_SYMBOL(skb_prepare_seq_read);
2258 * skb_seq_read - Sequentially read skb data
2259 * @consumed: number of bytes consumed by the caller so far
2260 * @data: destination pointer for data to be returned
2261 * @st: state variable
2263 * Reads a block of skb data at &consumed relative to the
2264 * lower offset specified to skb_prepare_seq_read(). Assigns
2265 * the head of the data block to &data and returns the length
2266 * of the block or 0 if the end of the skb data or the upper
2267 * offset has been reached.
2269 * The caller is not required to consume all of the data
2270 * returned, i.e. &consumed is typically set to the number
2271 * of bytes already consumed and the next call to
2272 * skb_seq_read() will return the remaining part of the block.
2274 * Note 1: The size of each block of data returned can be arbitary,
2275 * this limitation is the cost for zerocopy seqeuental
2276 * reads of potentially non linear data.
2278 * Note 2: Fragment lists within fragments are not implemented
2279 * at the moment, state->root_skb could be replaced with
2280 * a stack for this purpose.
2282 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2283 struct skb_seq_state *st)
2285 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2288 if (unlikely(abs_offset >= st->upper_offset))
2292 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2294 if (abs_offset < block_limit && !st->frag_data) {
2295 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2296 return block_limit - abs_offset;
2299 if (st->frag_idx == 0 && !st->frag_data)
2300 st->stepped_offset += skb_headlen(st->cur_skb);
2302 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2303 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2304 block_limit = frag->size + st->stepped_offset;
2306 if (abs_offset < block_limit) {
2308 st->frag_data = kmap_skb_frag(frag);
2310 *data = (u8 *) st->frag_data + frag->page_offset +
2311 (abs_offset - st->stepped_offset);
2313 return block_limit - abs_offset;
2316 if (st->frag_data) {
2317 kunmap_skb_frag(st->frag_data);
2318 st->frag_data = NULL;
2322 st->stepped_offset += frag->size;
2325 if (st->frag_data) {
2326 kunmap_skb_frag(st->frag_data);
2327 st->frag_data = NULL;
2330 if (st->root_skb == st->cur_skb &&
2331 skb_shinfo(st->root_skb)->frag_list) {
2332 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2335 } else if (st->cur_skb->next) {
2336 st->cur_skb = st->cur_skb->next;
2343 EXPORT_SYMBOL(skb_seq_read);
2346 * skb_abort_seq_read - Abort a sequential read of skb data
2347 * @st: state variable
2349 * Must be called if skb_seq_read() was not called until it
2352 void skb_abort_seq_read(struct skb_seq_state *st)
2355 kunmap_skb_frag(st->frag_data);
2357 EXPORT_SYMBOL(skb_abort_seq_read);
2359 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2361 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2362 struct ts_config *conf,
2363 struct ts_state *state)
2365 return skb_seq_read(offset, text, TS_SKB_CB(state));
2368 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2370 skb_abort_seq_read(TS_SKB_CB(state));
2374 * skb_find_text - Find a text pattern in skb data
2375 * @skb: the buffer to look in
2376 * @from: search offset
2378 * @config: textsearch configuration
2379 * @state: uninitialized textsearch state variable
2381 * Finds a pattern in the skb data according to the specified
2382 * textsearch configuration. Use textsearch_next() to retrieve
2383 * subsequent occurrences of the pattern. Returns the offset
2384 * to the first occurrence or UINT_MAX if no match was found.
2386 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2387 unsigned int to, struct ts_config *config,
2388 struct ts_state *state)
2392 config->get_next_block = skb_ts_get_next_block;
2393 config->finish = skb_ts_finish;
2395 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2397 ret = textsearch_find(config, state);
2398 return (ret <= to - from ? ret : UINT_MAX);
2400 EXPORT_SYMBOL(skb_find_text);
2403 * skb_append_datato_frags: - append the user data to a skb
2404 * @sk: sock structure
2405 * @skb: skb structure to be appened with user data.
2406 * @getfrag: call back function to be used for getting the user data
2407 * @from: pointer to user message iov
2408 * @length: length of the iov message
2410 * Description: This procedure append the user data in the fragment part
2411 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2413 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2414 int (*getfrag)(void *from, char *to, int offset,
2415 int len, int odd, struct sk_buff *skb),
2416 void *from, int length)
2419 skb_frag_t *frag = NULL;
2420 struct page *page = NULL;
2426 /* Return error if we don't have space for new frag */
2427 frg_cnt = skb_shinfo(skb)->nr_frags;
2428 if (frg_cnt >= MAX_SKB_FRAGS)
2431 /* allocate a new page for next frag */
2432 page = alloc_pages(sk->sk_allocation, 0);
2434 /* If alloc_page fails just return failure and caller will
2435 * free previous allocated pages by doing kfree_skb()
2440 /* initialize the next frag */
2441 sk->sk_sndmsg_page = page;
2442 sk->sk_sndmsg_off = 0;
2443 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
2444 skb->truesize += PAGE_SIZE;
2445 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
2447 /* get the new initialized frag */
2448 frg_cnt = skb_shinfo(skb)->nr_frags;
2449 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
2451 /* copy the user data to page */
2452 left = PAGE_SIZE - frag->page_offset;
2453 copy = (length > left)? left : length;
2455 ret = getfrag(from, (page_address(frag->page) +
2456 frag->page_offset + frag->size),
2457 offset, copy, 0, skb);
2461 /* copy was successful so update the size parameters */
2462 sk->sk_sndmsg_off += copy;
2465 skb->data_len += copy;
2469 } while (length > 0);
2473 EXPORT_SYMBOL(skb_append_datato_frags);
2476 * skb_pull_rcsum - pull skb and update receive checksum
2477 * @skb: buffer to update
2478 * @len: length of data pulled
2480 * This function performs an skb_pull on the packet and updates
2481 * the CHECKSUM_COMPLETE checksum. It should be used on
2482 * receive path processing instead of skb_pull unless you know
2483 * that the checksum difference is zero (e.g., a valid IP header)
2484 * or you are setting ip_summed to CHECKSUM_NONE.
2486 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2488 BUG_ON(len > skb->len);
2490 BUG_ON(skb->len < skb->data_len);
2491 skb_postpull_rcsum(skb, skb->data, len);
2492 return skb->data += len;
2495 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2498 * skb_segment - Perform protocol segmentation on skb.
2499 * @skb: buffer to segment
2500 * @features: features for the output path (see dev->features)
2502 * This function performs segmentation on the given skb. It returns
2503 * a pointer to the first in a list of new skbs for the segments.
2504 * In case of error it returns ERR_PTR(err).
2506 struct sk_buff *skb_segment(struct sk_buff *skb, int features)
2508 struct sk_buff *segs = NULL;
2509 struct sk_buff *tail = NULL;
2510 struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
2511 unsigned int mss = skb_shinfo(skb)->gso_size;
2512 unsigned int doffset = skb->data - skb_mac_header(skb);
2513 unsigned int offset = doffset;
2514 unsigned int headroom;
2516 int sg = features & NETIF_F_SG;
2517 int nfrags = skb_shinfo(skb)->nr_frags;
2522 __skb_push(skb, doffset);
2523 headroom = skb_headroom(skb);
2524 pos = skb_headlen(skb);
2527 struct sk_buff *nskb;
2532 len = skb->len - offset;
2536 hsize = skb_headlen(skb) - offset;
2539 if (hsize > len || !sg)
2542 if (!hsize && i >= nfrags) {
2543 BUG_ON(fskb->len != len);
2546 nskb = skb_clone(fskb, GFP_ATOMIC);
2549 if (unlikely(!nskb))
2552 hsize = skb_end_pointer(nskb) - nskb->head;
2553 if (skb_cow_head(nskb, doffset + headroom)) {
2558 nskb->truesize += skb_end_pointer(nskb) - nskb->head -
2560 skb_release_head_state(nskb);
2561 __skb_push(nskb, doffset);
2563 nskb = alloc_skb(hsize + doffset + headroom,
2566 if (unlikely(!nskb))
2569 skb_reserve(nskb, headroom);
2570 __skb_put(nskb, doffset);
2579 __copy_skb_header(nskb, skb);
2580 nskb->mac_len = skb->mac_len;
2582 skb_reset_mac_header(nskb);
2583 skb_set_network_header(nskb, skb->mac_len);
2584 nskb->transport_header = (nskb->network_header +
2585 skb_network_header_len(skb));
2586 skb_copy_from_linear_data(skb, nskb->data, doffset);
2588 if (fskb != skb_shinfo(skb)->frag_list)
2592 nskb->ip_summed = CHECKSUM_NONE;
2593 nskb->csum = skb_copy_and_csum_bits(skb, offset,
2599 frag = skb_shinfo(nskb)->frags;
2601 skb_copy_from_linear_data_offset(skb, offset,
2602 skb_put(nskb, hsize), hsize);
2604 while (pos < offset + len && i < nfrags) {
2605 *frag = skb_shinfo(skb)->frags[i];
2606 get_page(frag->page);
2610 frag->page_offset += offset - pos;
2611 frag->size -= offset - pos;
2614 skb_shinfo(nskb)->nr_frags++;
2616 if (pos + size <= offset + len) {
2620 frag->size -= pos + size - (offset + len);
2627 if (pos < offset + len) {
2628 struct sk_buff *fskb2 = fskb;
2630 BUG_ON(pos + fskb->len != offset + len);
2636 fskb2 = skb_clone(fskb2, GFP_ATOMIC);
2642 BUG_ON(skb_shinfo(nskb)->frag_list);
2643 skb_shinfo(nskb)->frag_list = fskb2;
2647 nskb->data_len = len - hsize;
2648 nskb->len += nskb->data_len;
2649 nskb->truesize += nskb->data_len;
2650 } while ((offset += len) < skb->len);
2655 while ((skb = segs)) {
2659 return ERR_PTR(err);
2661 EXPORT_SYMBOL_GPL(skb_segment);
2663 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2665 struct sk_buff *p = *head;
2666 struct sk_buff *nskb;
2667 struct skb_shared_info *skbinfo = skb_shinfo(skb);
2668 struct skb_shared_info *pinfo = skb_shinfo(p);
2669 unsigned int headroom;
2670 unsigned int len = skb_gro_len(skb);
2671 unsigned int offset = skb_gro_offset(skb);
2672 unsigned int headlen = skb_headlen(skb);
2674 if (p->len + len >= 65536)
2677 if (pinfo->frag_list)
2679 else if (headlen <= offset) {
2682 int i = skbinfo->nr_frags;
2683 int nr_frags = pinfo->nr_frags + i;
2687 if (nr_frags > MAX_SKB_FRAGS)
2690 pinfo->nr_frags = nr_frags;
2691 skbinfo->nr_frags = 0;
2693 frag = pinfo->frags + nr_frags;
2694 frag2 = skbinfo->frags + i;
2699 frag->page_offset += offset;
2700 frag->size -= offset;
2702 skb->truesize -= skb->data_len;
2703 skb->len -= skb->data_len;
2706 NAPI_GRO_CB(skb)->free = 1;
2710 headroom = skb_headroom(p);
2711 nskb = netdev_alloc_skb(p->dev, headroom + skb_gro_offset(p));
2712 if (unlikely(!nskb))
2715 __copy_skb_header(nskb, p);
2716 nskb->mac_len = p->mac_len;
2718 skb_reserve(nskb, headroom);
2719 __skb_put(nskb, skb_gro_offset(p));
2721 skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
2722 skb_set_network_header(nskb, skb_network_offset(p));
2723 skb_set_transport_header(nskb, skb_transport_offset(p));
2725 __skb_pull(p, skb_gro_offset(p));
2726 memcpy(skb_mac_header(nskb), skb_mac_header(p),
2727 p->data - skb_mac_header(p));
2729 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
2730 skb_shinfo(nskb)->frag_list = p;
2731 skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2732 skb_header_release(p);
2735 nskb->data_len += p->len;
2736 nskb->truesize += p->len;
2737 nskb->len += p->len;
2740 nskb->next = p->next;
2746 if (offset > headlen) {
2747 skbinfo->frags[0].page_offset += offset - headlen;
2748 skbinfo->frags[0].size -= offset - headlen;
2752 __skb_pull(skb, offset);
2754 p->prev->next = skb;
2756 skb_header_release(skb);
2759 NAPI_GRO_CB(p)->count++;
2764 NAPI_GRO_CB(skb)->same_flow = 1;
2767 EXPORT_SYMBOL_GPL(skb_gro_receive);
2769 void __init skb_init(void)
2771 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
2772 sizeof(struct sk_buff),
2774 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2776 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2777 (2*sizeof(struct sk_buff)) +
2780 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2785 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2786 * @skb: Socket buffer containing the buffers to be mapped
2787 * @sg: The scatter-gather list to map into
2788 * @offset: The offset into the buffer's contents to start mapping
2789 * @len: Length of buffer space to be mapped
2791 * Fill the specified scatter-gather list with mappings/pointers into a
2792 * region of the buffer space attached to a socket buffer.
2795 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2797 int start = skb_headlen(skb);
2798 int i, copy = start - offset;
2804 sg_set_buf(sg, skb->data + offset, copy);
2806 if ((len -= copy) == 0)
2811 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2814 WARN_ON(start > offset + len);
2816 end = start + skb_shinfo(skb)->frags[i].size;
2817 if ((copy = end - offset) > 0) {
2818 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2822 sg_set_page(&sg[elt], frag->page, copy,
2823 frag->page_offset+offset-start);
2832 if (skb_shinfo(skb)->frag_list) {
2833 struct sk_buff *list = skb_shinfo(skb)->frag_list;
2835 for (; list; list = list->next) {
2838 WARN_ON(start > offset + len);
2840 end = start + list->len;
2841 if ((copy = end - offset) > 0) {
2844 elt += __skb_to_sgvec(list, sg+elt, offset - start,
2846 if ((len -= copy) == 0)
2857 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2859 int nsg = __skb_to_sgvec(skb, sg, offset, len);
2861 sg_mark_end(&sg[nsg - 1]);
2865 EXPORT_SYMBOL_GPL(skb_to_sgvec);
2868 * skb_cow_data - Check that a socket buffer's data buffers are writable
2869 * @skb: The socket buffer to check.
2870 * @tailbits: Amount of trailing space to be added
2871 * @trailer: Returned pointer to the skb where the @tailbits space begins
2873 * Make sure that the data buffers attached to a socket buffer are
2874 * writable. If they are not, private copies are made of the data buffers
2875 * and the socket buffer is set to use these instead.
2877 * If @tailbits is given, make sure that there is space to write @tailbits
2878 * bytes of data beyond current end of socket buffer. @trailer will be
2879 * set to point to the skb in which this space begins.
2881 * The number of scatterlist elements required to completely map the
2882 * COW'd and extended socket buffer will be returned.
2884 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
2888 struct sk_buff *skb1, **skb_p;
2890 /* If skb is cloned or its head is paged, reallocate
2891 * head pulling out all the pages (pages are considered not writable
2892 * at the moment even if they are anonymous).
2894 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
2895 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
2898 /* Easy case. Most of packets will go this way. */
2899 if (!skb_shinfo(skb)->frag_list) {
2900 /* A little of trouble, not enough of space for trailer.
2901 * This should not happen, when stack is tuned to generate
2902 * good frames. OK, on miss we reallocate and reserve even more
2903 * space, 128 bytes is fair. */
2905 if (skb_tailroom(skb) < tailbits &&
2906 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
2914 /* Misery. We are in troubles, going to mincer fragments... */
2917 skb_p = &skb_shinfo(skb)->frag_list;
2920 while ((skb1 = *skb_p) != NULL) {
2923 /* The fragment is partially pulled by someone,
2924 * this can happen on input. Copy it and everything
2927 if (skb_shared(skb1))
2930 /* If the skb is the last, worry about trailer. */
2932 if (skb1->next == NULL && tailbits) {
2933 if (skb_shinfo(skb1)->nr_frags ||
2934 skb_shinfo(skb1)->frag_list ||
2935 skb_tailroom(skb1) < tailbits)
2936 ntail = tailbits + 128;
2942 skb_shinfo(skb1)->nr_frags ||
2943 skb_shinfo(skb1)->frag_list) {
2944 struct sk_buff *skb2;
2946 /* Fuck, we are miserable poor guys... */
2948 skb2 = skb_copy(skb1, GFP_ATOMIC);
2950 skb2 = skb_copy_expand(skb1,
2954 if (unlikely(skb2 == NULL))
2958 skb_set_owner_w(skb2, skb1->sk);
2960 /* Looking around. Are we still alive?
2961 * OK, link new skb, drop old one */
2963 skb2->next = skb1->next;
2970 skb_p = &skb1->next;
2975 EXPORT_SYMBOL_GPL(skb_cow_data);
2977 void skb_tstamp_tx(struct sk_buff *orig_skb,
2978 struct skb_shared_hwtstamps *hwtstamps)
2980 struct sock *sk = orig_skb->sk;
2981 struct sock_exterr_skb *serr;
2982 struct sk_buff *skb;
2988 skb = skb_clone(orig_skb, GFP_ATOMIC);
2993 *skb_hwtstamps(skb) =
2997 * no hardware time stamps available,
2998 * so keep the skb_shared_tx and only
2999 * store software time stamp
3001 skb->tstamp = ktime_get_real();
3004 serr = SKB_EXT_ERR(skb);
3005 memset(serr, 0, sizeof(*serr));
3006 serr->ee.ee_errno = ENOMSG;
3007 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3008 err = sock_queue_err_skb(sk, skb);
3012 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3016 * skb_partial_csum_set - set up and verify partial csum values for packet
3017 * @skb: the skb to set
3018 * @start: the number of bytes after skb->data to start checksumming.
3019 * @off: the offset from start to place the checksum.
3021 * For untrusted partially-checksummed packets, we need to make sure the values
3022 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3024 * This function checks and sets those values and skb->ip_summed: if this
3025 * returns false you should drop the packet.
3027 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3029 if (unlikely(start > skb->len - 2) ||
3030 unlikely((int)start + off > skb->len - 2)) {
3031 if (net_ratelimit())
3033 "bad partial csum: csum=%u/%u len=%u\n",
3034 start, off, skb->len);
3037 skb->ip_summed = CHECKSUM_PARTIAL;
3038 skb->csum_start = skb_headroom(skb) + start;
3039 skb->csum_offset = off;
3042 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3044 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3046 if (net_ratelimit())
3047 pr_warning("%s: received packets cannot be forwarded"
3048 " while LRO is enabled\n", skb->dev->name);
3050 EXPORT_SYMBOL(__skb_warn_lro_forwarding);