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/splice.h>
56 #include <linux/cache.h>
57 #include <linux/rtnetlink.h>
58 #include <linux/init.h>
59 #include <linux/scatterlist.h>
61 #include <net/protocol.h>
64 #include <net/checksum.h>
67 #include <asm/uaccess.h>
68 #include <asm/system.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
)
78 struct sk_buff
*skb
= (struct sk_buff
*) buf
->private;
83 static void sock_pipe_buf_get(struct pipe_inode_info
*pipe
,
84 struct pipe_buffer
*buf
)
86 struct sk_buff
*skb
= (struct sk_buff
*) buf
->private;
91 static int sock_pipe_buf_steal(struct pipe_inode_info
*pipe
,
92 struct pipe_buffer
*buf
)
98 /* Pipe buffer operations for a socket. */
99 static struct pipe_buf_operations sock_pipe_buf_ops
= {
101 .map
= generic_pipe_buf_map
,
102 .unmap
= generic_pipe_buf_unmap
,
103 .confirm
= generic_pipe_buf_confirm
,
104 .release
= sock_pipe_buf_release
,
105 .steal
= sock_pipe_buf_steal
,
106 .get
= sock_pipe_buf_get
,
110 * Keep out-of-line to prevent kernel bloat.
111 * __builtin_return_address is not used because it is not always
116 * skb_over_panic - private function
121 * Out of line support code for skb_put(). Not user callable.
123 void skb_over_panic(struct sk_buff
*skb
, int sz
, void *here
)
125 printk(KERN_EMERG
"skb_over_panic: text:%p len:%d put:%d head:%p "
126 "data:%p tail:%#lx end:%#lx dev:%s\n",
127 here
, skb
->len
, sz
, skb
->head
, skb
->data
,
128 (unsigned long)skb
->tail
, (unsigned long)skb
->end
,
129 skb
->dev
? skb
->dev
->name
: "<NULL>");
134 * skb_under_panic - private function
139 * Out of line support code for skb_push(). Not user callable.
142 void skb_under_panic(struct sk_buff
*skb
, int sz
, void *here
)
144 printk(KERN_EMERG
"skb_under_panic: text:%p len:%d put:%d head:%p "
145 "data:%p tail:%#lx end:%#lx dev:%s\n",
146 here
, skb
->len
, sz
, skb
->head
, skb
->data
,
147 (unsigned long)skb
->tail
, (unsigned long)skb
->end
,
148 skb
->dev
? skb
->dev
->name
: "<NULL>");
152 void skb_truesize_bug(struct sk_buff
*skb
)
154 printk(KERN_ERR
"SKB BUG: Invalid truesize (%u) "
155 "len=%u, sizeof(sk_buff)=%Zd\n",
156 skb
->truesize
, skb
->len
, sizeof(struct sk_buff
));
158 EXPORT_SYMBOL(skb_truesize_bug
);
160 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
161 * 'private' fields and also do memory statistics to find all the
167 * __alloc_skb - allocate a network buffer
168 * @size: size to allocate
169 * @gfp_mask: allocation mask
170 * @fclone: allocate from fclone cache instead of head cache
171 * and allocate a cloned (child) skb
172 * @node: numa node to allocate memory on
174 * Allocate a new &sk_buff. The returned buffer has no headroom and a
175 * tail room of size bytes. The object has a reference count of one.
176 * The return is the buffer. On a failure the return is %NULL.
178 * Buffers may only be allocated from interrupts using a @gfp_mask of
181 struct sk_buff
*__alloc_skb(unsigned int size
, gfp_t gfp_mask
,
182 int fclone
, int node
)
184 struct kmem_cache
*cache
;
185 struct skb_shared_info
*shinfo
;
189 cache
= fclone
? skbuff_fclone_cache
: skbuff_head_cache
;
192 skb
= kmem_cache_alloc_node(cache
, gfp_mask
& ~__GFP_DMA
, node
);
196 size
= SKB_DATA_ALIGN(size
);
197 data
= kmalloc_node_track_caller(size
+ sizeof(struct skb_shared_info
),
203 * Only clear those fields we need to clear, not those that we will
204 * actually initialise below. Hence, don't put any more fields after
205 * the tail pointer in struct sk_buff!
207 memset(skb
, 0, offsetof(struct sk_buff
, tail
));
208 skb
->truesize
= size
+ sizeof(struct sk_buff
);
209 atomic_set(&skb
->users
, 1);
212 skb_reset_tail_pointer(skb
);
213 skb
->end
= skb
->tail
+ size
;
214 /* make sure we initialize shinfo sequentially */
215 shinfo
= skb_shinfo(skb
);
216 atomic_set(&shinfo
->dataref
, 1);
217 shinfo
->nr_frags
= 0;
218 shinfo
->gso_size
= 0;
219 shinfo
->gso_segs
= 0;
220 shinfo
->gso_type
= 0;
221 shinfo
->ip6_frag_id
= 0;
222 shinfo
->frag_list
= NULL
;
225 struct sk_buff
*child
= skb
+ 1;
226 atomic_t
*fclone_ref
= (atomic_t
*) (child
+ 1);
228 skb
->fclone
= SKB_FCLONE_ORIG
;
229 atomic_set(fclone_ref
, 1);
231 child
->fclone
= SKB_FCLONE_UNAVAILABLE
;
236 kmem_cache_free(cache
, skb
);
242 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
243 * @dev: network device to receive on
244 * @length: length to allocate
245 * @gfp_mask: get_free_pages mask, passed to alloc_skb
247 * Allocate a new &sk_buff and assign it a usage count of one. The
248 * buffer has unspecified headroom built in. Users should allocate
249 * the headroom they think they need without accounting for the
250 * built in space. The built in space is used for optimisations.
252 * %NULL is returned if there is no free memory.
254 struct sk_buff
*__netdev_alloc_skb(struct net_device
*dev
,
255 unsigned int length
, gfp_t gfp_mask
)
257 int node
= dev
->dev
.parent
? dev_to_node(dev
->dev
.parent
) : -1;
260 skb
= __alloc_skb(length
+ NET_SKB_PAD
, gfp_mask
, 0, node
);
262 skb_reserve(skb
, NET_SKB_PAD
);
269 * dev_alloc_skb - allocate an skbuff for receiving
270 * @length: length to allocate
272 * Allocate a new &sk_buff and assign it a usage count of one. The
273 * buffer has unspecified headroom built in. Users should allocate
274 * the headroom they think they need without accounting for the
275 * built in space. The built in space is used for optimisations.
277 * %NULL is returned if there is no free memory. Although this function
278 * allocates memory it can be called from an interrupt.
280 struct sk_buff
*dev_alloc_skb(unsigned int length
)
283 * There is more code here than it seems:
284 * __dev_alloc_skb is an inline
286 return __dev_alloc_skb(length
, GFP_ATOMIC
);
288 EXPORT_SYMBOL(dev_alloc_skb
);
290 static void skb_drop_list(struct sk_buff
**listp
)
292 struct sk_buff
*list
= *listp
;
297 struct sk_buff
*this = list
;
303 static inline void skb_drop_fraglist(struct sk_buff
*skb
)
305 skb_drop_list(&skb_shinfo(skb
)->frag_list
);
308 static void skb_clone_fraglist(struct sk_buff
*skb
)
310 struct sk_buff
*list
;
312 for (list
= skb_shinfo(skb
)->frag_list
; list
; list
= list
->next
)
316 static void skb_release_data(struct sk_buff
*skb
)
319 !atomic_sub_return(skb
->nohdr
? (1 << SKB_DATAREF_SHIFT
) + 1 : 1,
320 &skb_shinfo(skb
)->dataref
)) {
321 if (skb_shinfo(skb
)->nr_frags
) {
323 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
324 put_page(skb_shinfo(skb
)->frags
[i
].page
);
327 if (skb_shinfo(skb
)->frag_list
)
328 skb_drop_fraglist(skb
);
335 * Free an skbuff by memory without cleaning the state.
337 static void kfree_skbmem(struct sk_buff
*skb
)
339 struct sk_buff
*other
;
340 atomic_t
*fclone_ref
;
342 switch (skb
->fclone
) {
343 case SKB_FCLONE_UNAVAILABLE
:
344 kmem_cache_free(skbuff_head_cache
, skb
);
347 case SKB_FCLONE_ORIG
:
348 fclone_ref
= (atomic_t
*) (skb
+ 2);
349 if (atomic_dec_and_test(fclone_ref
))
350 kmem_cache_free(skbuff_fclone_cache
, skb
);
353 case SKB_FCLONE_CLONE
:
354 fclone_ref
= (atomic_t
*) (skb
+ 1);
357 /* The clone portion is available for
358 * fast-cloning again.
360 skb
->fclone
= SKB_FCLONE_UNAVAILABLE
;
362 if (atomic_dec_and_test(fclone_ref
))
363 kmem_cache_free(skbuff_fclone_cache
, other
);
368 /* Free everything but the sk_buff shell. */
369 static void skb_release_all(struct sk_buff
*skb
)
371 dst_release(skb
->dst
);
373 secpath_put(skb
->sp
);
375 if (skb
->destructor
) {
377 skb
->destructor(skb
);
379 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
380 nf_conntrack_put(skb
->nfct
);
381 nf_conntrack_put_reasm(skb
->nfct_reasm
);
383 #ifdef CONFIG_BRIDGE_NETFILTER
384 nf_bridge_put(skb
->nf_bridge
);
386 /* XXX: IS this still necessary? - JHS */
387 #ifdef CONFIG_NET_SCHED
389 #ifdef CONFIG_NET_CLS_ACT
393 skb_release_data(skb
);
397 * __kfree_skb - private function
400 * Free an sk_buff. Release anything attached to the buffer.
401 * Clean the state. This is an internal helper function. Users should
402 * always call kfree_skb
405 void __kfree_skb(struct sk_buff
*skb
)
407 skb_release_all(skb
);
412 * kfree_skb - free an sk_buff
413 * @skb: buffer to free
415 * Drop a reference to the buffer and free it if the usage count has
418 void kfree_skb(struct sk_buff
*skb
)
422 if (likely(atomic_read(&skb
->users
) == 1))
424 else if (likely(!atomic_dec_and_test(&skb
->users
)))
429 static void __copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
431 new->tstamp
= old
->tstamp
;
433 new->transport_header
= old
->transport_header
;
434 new->network_header
= old
->network_header
;
435 new->mac_header
= old
->mac_header
;
436 new->dst
= dst_clone(old
->dst
);
438 new->sp
= secpath_get(old
->sp
);
440 memcpy(new->cb
, old
->cb
, sizeof(old
->cb
));
441 new->csum_start
= old
->csum_start
;
442 new->csum_offset
= old
->csum_offset
;
443 new->local_df
= old
->local_df
;
444 new->pkt_type
= old
->pkt_type
;
445 new->ip_summed
= old
->ip_summed
;
446 skb_copy_queue_mapping(new, old
);
447 new->priority
= old
->priority
;
448 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
449 new->ipvs_property
= old
->ipvs_property
;
451 new->protocol
= old
->protocol
;
452 new->mark
= old
->mark
;
454 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
455 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
456 new->nf_trace
= old
->nf_trace
;
458 #ifdef CONFIG_NET_SCHED
459 new->tc_index
= old
->tc_index
;
460 #ifdef CONFIG_NET_CLS_ACT
461 new->tc_verd
= old
->tc_verd
;
464 skb_copy_secmark(new, old
);
467 static struct sk_buff
*__skb_clone(struct sk_buff
*n
, struct sk_buff
*skb
)
469 #define C(x) n->x = skb->x
471 n
->next
= n
->prev
= NULL
;
473 __copy_skb_header(n
, skb
);
478 n
->hdr_len
= skb
->nohdr
? skb_headroom(skb
) : skb
->hdr_len
;
481 n
->destructor
= NULL
;
488 atomic_set(&n
->users
, 1);
490 atomic_inc(&(skb_shinfo(skb
)->dataref
));
498 * skb_morph - morph one skb into another
499 * @dst: the skb to receive the contents
500 * @src: the skb to supply the contents
502 * This is identical to skb_clone except that the target skb is
503 * supplied by the user.
505 * The target skb is returned upon exit.
507 struct sk_buff
*skb_morph(struct sk_buff
*dst
, struct sk_buff
*src
)
509 skb_release_all(dst
);
510 return __skb_clone(dst
, src
);
512 EXPORT_SYMBOL_GPL(skb_morph
);
515 * skb_clone - duplicate an sk_buff
516 * @skb: buffer to clone
517 * @gfp_mask: allocation priority
519 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
520 * copies share the same packet data but not structure. The new
521 * buffer has a reference count of 1. If the allocation fails the
522 * function returns %NULL otherwise the new buffer is returned.
524 * If this function is called from an interrupt gfp_mask() must be
528 struct sk_buff
*skb_clone(struct sk_buff
*skb
, gfp_t gfp_mask
)
533 if (skb
->fclone
== SKB_FCLONE_ORIG
&&
534 n
->fclone
== SKB_FCLONE_UNAVAILABLE
) {
535 atomic_t
*fclone_ref
= (atomic_t
*) (n
+ 1);
536 n
->fclone
= SKB_FCLONE_CLONE
;
537 atomic_inc(fclone_ref
);
539 n
= kmem_cache_alloc(skbuff_head_cache
, gfp_mask
);
542 n
->fclone
= SKB_FCLONE_UNAVAILABLE
;
545 return __skb_clone(n
, skb
);
548 static void copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
550 #ifndef NET_SKBUFF_DATA_USES_OFFSET
552 * Shift between the two data areas in bytes
554 unsigned long offset
= new->data
- old
->data
;
557 __copy_skb_header(new, old
);
559 #ifndef NET_SKBUFF_DATA_USES_OFFSET
560 /* {transport,network,mac}_header are relative to skb->head */
561 new->transport_header
+= offset
;
562 new->network_header
+= offset
;
563 new->mac_header
+= offset
;
565 skb_shinfo(new)->gso_size
= skb_shinfo(old
)->gso_size
;
566 skb_shinfo(new)->gso_segs
= skb_shinfo(old
)->gso_segs
;
567 skb_shinfo(new)->gso_type
= skb_shinfo(old
)->gso_type
;
571 * skb_copy - create private copy of an sk_buff
572 * @skb: buffer to copy
573 * @gfp_mask: allocation priority
575 * Make a copy of both an &sk_buff and its data. This is used when the
576 * caller wishes to modify the data and needs a private copy of the
577 * data to alter. Returns %NULL on failure or the pointer to the buffer
578 * on success. The returned buffer has a reference count of 1.
580 * As by-product this function converts non-linear &sk_buff to linear
581 * one, so that &sk_buff becomes completely private and caller is allowed
582 * to modify all the data of returned buffer. This means that this
583 * function is not recommended for use in circumstances when only
584 * header is going to be modified. Use pskb_copy() instead.
587 struct sk_buff
*skb_copy(const struct sk_buff
*skb
, gfp_t gfp_mask
)
589 int headerlen
= skb
->data
- skb
->head
;
591 * Allocate the copy buffer
594 #ifdef NET_SKBUFF_DATA_USES_OFFSET
595 n
= alloc_skb(skb
->end
+ skb
->data_len
, gfp_mask
);
597 n
= alloc_skb(skb
->end
- skb
->head
+ skb
->data_len
, gfp_mask
);
602 /* Set the data pointer */
603 skb_reserve(n
, headerlen
);
604 /* Set the tail pointer and length */
605 skb_put(n
, skb
->len
);
607 if (skb_copy_bits(skb
, -headerlen
, n
->head
, headerlen
+ skb
->len
))
610 copy_skb_header(n
, skb
);
616 * pskb_copy - create copy of an sk_buff with private head.
617 * @skb: buffer to copy
618 * @gfp_mask: allocation priority
620 * Make a copy of both an &sk_buff and part of its data, located
621 * in header. Fragmented data remain shared. This is used when
622 * the caller wishes to modify only header of &sk_buff and needs
623 * private copy of the header to alter. Returns %NULL on failure
624 * or the pointer to the buffer on success.
625 * The returned buffer has a reference count of 1.
628 struct sk_buff
*pskb_copy(struct sk_buff
*skb
, gfp_t gfp_mask
)
631 * Allocate the copy buffer
634 #ifdef NET_SKBUFF_DATA_USES_OFFSET
635 n
= alloc_skb(skb
->end
, gfp_mask
);
637 n
= alloc_skb(skb
->end
- skb
->head
, gfp_mask
);
642 /* Set the data pointer */
643 skb_reserve(n
, skb
->data
- skb
->head
);
644 /* Set the tail pointer and length */
645 skb_put(n
, skb_headlen(skb
));
647 skb_copy_from_linear_data(skb
, n
->data
, n
->len
);
649 n
->truesize
+= skb
->data_len
;
650 n
->data_len
= skb
->data_len
;
653 if (skb_shinfo(skb
)->nr_frags
) {
656 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
657 skb_shinfo(n
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
658 get_page(skb_shinfo(n
)->frags
[i
].page
);
660 skb_shinfo(n
)->nr_frags
= i
;
663 if (skb_shinfo(skb
)->frag_list
) {
664 skb_shinfo(n
)->frag_list
= skb_shinfo(skb
)->frag_list
;
665 skb_clone_fraglist(n
);
668 copy_skb_header(n
, skb
);
674 * pskb_expand_head - reallocate header of &sk_buff
675 * @skb: buffer to reallocate
676 * @nhead: room to add at head
677 * @ntail: room to add at tail
678 * @gfp_mask: allocation priority
680 * Expands (or creates identical copy, if &nhead and &ntail are zero)
681 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
682 * reference count of 1. Returns zero in the case of success or error,
683 * if expansion failed. In the last case, &sk_buff is not changed.
685 * All the pointers pointing into skb header may change and must be
686 * reloaded after call to this function.
689 int pskb_expand_head(struct sk_buff
*skb
, int nhead
, int ntail
,
694 #ifdef NET_SKBUFF_DATA_USES_OFFSET
695 int size
= nhead
+ skb
->end
+ ntail
;
697 int size
= nhead
+ (skb
->end
- skb
->head
) + ntail
;
704 size
= SKB_DATA_ALIGN(size
);
706 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
710 /* Copy only real data... and, alas, header. This should be
711 * optimized for the cases when header is void. */
712 #ifdef NET_SKBUFF_DATA_USES_OFFSET
713 memcpy(data
+ nhead
, skb
->head
, skb
->tail
);
715 memcpy(data
+ nhead
, skb
->head
, skb
->tail
- skb
->head
);
717 memcpy(data
+ size
, skb_end_pointer(skb
),
718 sizeof(struct skb_shared_info
));
720 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
721 get_page(skb_shinfo(skb
)->frags
[i
].page
);
723 if (skb_shinfo(skb
)->frag_list
)
724 skb_clone_fraglist(skb
);
726 skb_release_data(skb
);
728 off
= (data
+ nhead
) - skb
->head
;
732 #ifdef NET_SKBUFF_DATA_USES_OFFSET
736 skb
->end
= skb
->head
+ size
;
738 /* {transport,network,mac}_header and tail are relative to skb->head */
740 skb
->transport_header
+= off
;
741 skb
->network_header
+= off
;
742 skb
->mac_header
+= off
;
743 skb
->csum_start
+= nhead
;
747 atomic_set(&skb_shinfo(skb
)->dataref
, 1);
754 /* Make private copy of skb with writable head and some headroom */
756 struct sk_buff
*skb_realloc_headroom(struct sk_buff
*skb
, unsigned int headroom
)
758 struct sk_buff
*skb2
;
759 int delta
= headroom
- skb_headroom(skb
);
762 skb2
= pskb_copy(skb
, GFP_ATOMIC
);
764 skb2
= skb_clone(skb
, GFP_ATOMIC
);
765 if (skb2
&& pskb_expand_head(skb2
, SKB_DATA_ALIGN(delta
), 0,
776 * skb_copy_expand - copy and expand sk_buff
777 * @skb: buffer to copy
778 * @newheadroom: new free bytes at head
779 * @newtailroom: new free bytes at tail
780 * @gfp_mask: allocation priority
782 * Make a copy of both an &sk_buff and its data and while doing so
783 * allocate additional space.
785 * This is used when the caller wishes to modify the data and needs a
786 * private copy of the data to alter as well as more space for new fields.
787 * Returns %NULL on failure or the pointer to the buffer
788 * on success. The returned buffer has a reference count of 1.
790 * You must pass %GFP_ATOMIC as the allocation priority if this function
791 * is called from an interrupt.
793 struct sk_buff
*skb_copy_expand(const struct sk_buff
*skb
,
794 int newheadroom
, int newtailroom
,
798 * Allocate the copy buffer
800 struct sk_buff
*n
= alloc_skb(newheadroom
+ skb
->len
+ newtailroom
,
802 int oldheadroom
= skb_headroom(skb
);
803 int head_copy_len
, head_copy_off
;
809 skb_reserve(n
, newheadroom
);
811 /* Set the tail pointer and length */
812 skb_put(n
, skb
->len
);
814 head_copy_len
= oldheadroom
;
816 if (newheadroom
<= head_copy_len
)
817 head_copy_len
= newheadroom
;
819 head_copy_off
= newheadroom
- head_copy_len
;
821 /* Copy the linear header and data. */
822 if (skb_copy_bits(skb
, -head_copy_len
, n
->head
+ head_copy_off
,
823 skb
->len
+ head_copy_len
))
826 copy_skb_header(n
, skb
);
828 off
= newheadroom
- oldheadroom
;
829 n
->csum_start
+= off
;
830 #ifdef NET_SKBUFF_DATA_USES_OFFSET
831 n
->transport_header
+= off
;
832 n
->network_header
+= off
;
833 n
->mac_header
+= off
;
840 * skb_pad - zero pad the tail of an skb
841 * @skb: buffer to pad
844 * Ensure that a buffer is followed by a padding area that is zero
845 * filled. Used by network drivers which may DMA or transfer data
846 * beyond the buffer end onto the wire.
848 * May return error in out of memory cases. The skb is freed on error.
851 int skb_pad(struct sk_buff
*skb
, int pad
)
856 /* If the skbuff is non linear tailroom is always zero.. */
857 if (!skb_cloned(skb
) && skb_tailroom(skb
) >= pad
) {
858 memset(skb
->data
+skb
->len
, 0, pad
);
862 ntail
= skb
->data_len
+ pad
- (skb
->end
- skb
->tail
);
863 if (likely(skb_cloned(skb
) || ntail
> 0)) {
864 err
= pskb_expand_head(skb
, 0, ntail
, GFP_ATOMIC
);
869 /* FIXME: The use of this function with non-linear skb's really needs
872 err
= skb_linearize(skb
);
876 memset(skb
->data
+ skb
->len
, 0, pad
);
885 * skb_put - add data to a buffer
886 * @skb: buffer to use
887 * @len: amount of data to add
889 * This function extends the used data area of the buffer. If this would
890 * exceed the total buffer size the kernel will panic. A pointer to the
891 * first byte of the extra data is returned.
893 unsigned char *skb_put(struct sk_buff
*skb
, unsigned int len
)
895 unsigned char *tmp
= skb_tail_pointer(skb
);
896 SKB_LINEAR_ASSERT(skb
);
899 if (unlikely(skb
->tail
> skb
->end
))
900 skb_over_panic(skb
, len
, __builtin_return_address(0));
903 EXPORT_SYMBOL(skb_put
);
906 * skb_push - add data to the start of a buffer
907 * @skb: buffer to use
908 * @len: amount of data to add
910 * This function extends the used data area of the buffer at the buffer
911 * start. If this would exceed the total buffer headroom the kernel will
912 * panic. A pointer to the first byte of the extra data is returned.
914 unsigned char *skb_push(struct sk_buff
*skb
, unsigned int len
)
918 if (unlikely(skb
->data
<skb
->head
))
919 skb_under_panic(skb
, len
, __builtin_return_address(0));
922 EXPORT_SYMBOL(skb_push
);
925 * skb_pull - remove data from the start of a buffer
926 * @skb: buffer to use
927 * @len: amount of data to remove
929 * This function removes data from the start of a buffer, returning
930 * the memory to the headroom. A pointer to the next data in the buffer
931 * is returned. Once the data has been pulled future pushes will overwrite
934 unsigned char *skb_pull(struct sk_buff
*skb
, unsigned int len
)
936 return unlikely(len
> skb
->len
) ? NULL
: __skb_pull(skb
, len
);
938 EXPORT_SYMBOL(skb_pull
);
941 * skb_trim - remove end from a buffer
942 * @skb: buffer to alter
945 * Cut the length of a buffer down by removing data from the tail. If
946 * the buffer is already under the length specified it is not modified.
947 * The skb must be linear.
949 void skb_trim(struct sk_buff
*skb
, unsigned int len
)
952 __skb_trim(skb
, len
);
954 EXPORT_SYMBOL(skb_trim
);
956 /* Trims skb to length len. It can change skb pointers.
959 int ___pskb_trim(struct sk_buff
*skb
, unsigned int len
)
961 struct sk_buff
**fragp
;
962 struct sk_buff
*frag
;
963 int offset
= skb_headlen(skb
);
964 int nfrags
= skb_shinfo(skb
)->nr_frags
;
968 if (skb_cloned(skb
) &&
969 unlikely((err
= pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))))
976 for (; i
< nfrags
; i
++) {
977 int end
= offset
+ skb_shinfo(skb
)->frags
[i
].size
;
984 skb_shinfo(skb
)->frags
[i
++].size
= len
- offset
;
987 skb_shinfo(skb
)->nr_frags
= i
;
989 for (; i
< nfrags
; i
++)
990 put_page(skb_shinfo(skb
)->frags
[i
].page
);
992 if (skb_shinfo(skb
)->frag_list
)
993 skb_drop_fraglist(skb
);
997 for (fragp
= &skb_shinfo(skb
)->frag_list
; (frag
= *fragp
);
998 fragp
= &frag
->next
) {
999 int end
= offset
+ frag
->len
;
1001 if (skb_shared(frag
)) {
1002 struct sk_buff
*nfrag
;
1004 nfrag
= skb_clone(frag
, GFP_ATOMIC
);
1005 if (unlikely(!nfrag
))
1008 nfrag
->next
= frag
->next
;
1020 unlikely((err
= pskb_trim(frag
, len
- offset
))))
1024 skb_drop_list(&frag
->next
);
1029 if (len
> skb_headlen(skb
)) {
1030 skb
->data_len
-= skb
->len
- len
;
1035 skb_set_tail_pointer(skb
, len
);
1042 * __pskb_pull_tail - advance tail of skb header
1043 * @skb: buffer to reallocate
1044 * @delta: number of bytes to advance tail
1046 * The function makes a sense only on a fragmented &sk_buff,
1047 * it expands header moving its tail forward and copying necessary
1048 * data from fragmented part.
1050 * &sk_buff MUST have reference count of 1.
1052 * Returns %NULL (and &sk_buff does not change) if pull failed
1053 * or value of new tail of skb in the case of success.
1055 * All the pointers pointing into skb header may change and must be
1056 * reloaded after call to this function.
1059 /* Moves tail of skb head forward, copying data from fragmented part,
1060 * when it is necessary.
1061 * 1. It may fail due to malloc failure.
1062 * 2. It may change skb pointers.
1064 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1066 unsigned char *__pskb_pull_tail(struct sk_buff
*skb
, int delta
)
1068 /* If skb has not enough free space at tail, get new one
1069 * plus 128 bytes for future expansions. If we have enough
1070 * room at tail, reallocate without expansion only if skb is cloned.
1072 int i
, k
, eat
= (skb
->tail
+ delta
) - skb
->end
;
1074 if (eat
> 0 || skb_cloned(skb
)) {
1075 if (pskb_expand_head(skb
, 0, eat
> 0 ? eat
+ 128 : 0,
1080 if (skb_copy_bits(skb
, skb_headlen(skb
), skb_tail_pointer(skb
), delta
))
1083 /* Optimization: no fragments, no reasons to preestimate
1084 * size of pulled pages. Superb.
1086 if (!skb_shinfo(skb
)->frag_list
)
1089 /* Estimate size of pulled pages. */
1091 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1092 if (skb_shinfo(skb
)->frags
[i
].size
>= eat
)
1094 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
1097 /* If we need update frag list, we are in troubles.
1098 * Certainly, it possible to add an offset to skb data,
1099 * but taking into account that pulling is expected to
1100 * be very rare operation, it is worth to fight against
1101 * further bloating skb head and crucify ourselves here instead.
1102 * Pure masohism, indeed. 8)8)
1105 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1106 struct sk_buff
*clone
= NULL
;
1107 struct sk_buff
*insp
= NULL
;
1112 if (list
->len
<= eat
) {
1113 /* Eaten as whole. */
1118 /* Eaten partially. */
1120 if (skb_shared(list
)) {
1121 /* Sucks! We need to fork list. :-( */
1122 clone
= skb_clone(list
, GFP_ATOMIC
);
1128 /* This may be pulled without
1132 if (!pskb_pull(list
, eat
)) {
1141 /* Free pulled out fragments. */
1142 while ((list
= skb_shinfo(skb
)->frag_list
) != insp
) {
1143 skb_shinfo(skb
)->frag_list
= list
->next
;
1146 /* And insert new clone at head. */
1149 skb_shinfo(skb
)->frag_list
= clone
;
1152 /* Success! Now we may commit changes to skb data. */
1157 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1158 if (skb_shinfo(skb
)->frags
[i
].size
<= eat
) {
1159 put_page(skb_shinfo(skb
)->frags
[i
].page
);
1160 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
1162 skb_shinfo(skb
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1164 skb_shinfo(skb
)->frags
[k
].page_offset
+= eat
;
1165 skb_shinfo(skb
)->frags
[k
].size
-= eat
;
1171 skb_shinfo(skb
)->nr_frags
= k
;
1174 skb
->data_len
-= delta
;
1176 return skb_tail_pointer(skb
);
1179 /* Copy some data bits from skb to kernel buffer. */
1181 int skb_copy_bits(const struct sk_buff
*skb
, int offset
, void *to
, int len
)
1184 int start
= skb_headlen(skb
);
1186 if (offset
> (int)skb
->len
- len
)
1190 if ((copy
= start
- offset
) > 0) {
1193 skb_copy_from_linear_data_offset(skb
, offset
, to
, copy
);
1194 if ((len
-= copy
) == 0)
1200 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1203 BUG_TRAP(start
<= offset
+ len
);
1205 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1206 if ((copy
= end
- offset
) > 0) {
1212 vaddr
= kmap_skb_frag(&skb_shinfo(skb
)->frags
[i
]);
1214 vaddr
+ skb_shinfo(skb
)->frags
[i
].page_offset
+
1215 offset
- start
, copy
);
1216 kunmap_skb_frag(vaddr
);
1218 if ((len
-= copy
) == 0)
1226 if (skb_shinfo(skb
)->frag_list
) {
1227 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1229 for (; list
; list
= list
->next
) {
1232 BUG_TRAP(start
<= offset
+ len
);
1234 end
= start
+ list
->len
;
1235 if ((copy
= end
- offset
) > 0) {
1238 if (skb_copy_bits(list
, offset
- start
,
1241 if ((len
-= copy
) == 0)
1257 * Callback from splice_to_pipe(), if we need to release some pages
1258 * at the end of the spd in case we error'ed out in filling the pipe.
1260 static void sock_spd_release(struct splice_pipe_desc
*spd
, unsigned int i
)
1262 struct sk_buff
*skb
= (struct sk_buff
*) spd
->partial
[i
].private;
1268 * Fill page/offset/length into spd, if it can hold more pages.
1270 static inline int spd_fill_page(struct splice_pipe_desc
*spd
, struct page
*page
,
1271 unsigned int len
, unsigned int offset
,
1272 struct sk_buff
*skb
)
1274 if (unlikely(spd
->nr_pages
== PIPE_BUFFERS
))
1277 spd
->pages
[spd
->nr_pages
] = page
;
1278 spd
->partial
[spd
->nr_pages
].len
= len
;
1279 spd
->partial
[spd
->nr_pages
].offset
= offset
;
1280 spd
->partial
[spd
->nr_pages
].private = (unsigned long) skb_get(skb
);
1286 * Map linear and fragment data from the skb to spd. Returns number of
1289 static int __skb_splice_bits(struct sk_buff
*skb
, unsigned int *offset
,
1290 unsigned int *total_len
,
1291 struct splice_pipe_desc
*spd
)
1293 unsigned int nr_pages
= spd
->nr_pages
;
1294 unsigned int poff
, plen
, len
, toff
, tlen
;
1295 int headlen
, seg
, error
= 0;
1305 * if the offset is greater than the linear part, go directly to
1308 headlen
= skb_headlen(skb
);
1309 if (toff
>= headlen
) {
1315 * first map the linear region into the pages/partial map, skipping
1316 * any potential initial offset.
1319 while (len
< headlen
) {
1320 void *p
= skb
->data
+ len
;
1322 poff
= (unsigned long) p
& (PAGE_SIZE
- 1);
1323 plen
= min_t(unsigned int, headlen
- len
, PAGE_SIZE
- poff
);
1336 plen
= min(plen
, tlen
);
1341 * just jump directly to update and return, no point
1342 * in going over fragments when the output is full.
1344 error
= spd_fill_page(spd
, virt_to_page(p
), plen
, poff
, skb
);
1352 * then map the fragments
1355 for (seg
= 0; seg
< skb_shinfo(skb
)->nr_frags
; seg
++) {
1356 const skb_frag_t
*f
= &skb_shinfo(skb
)->frags
[seg
];
1359 poff
= f
->page_offset
;
1371 plen
= min(plen
, tlen
);
1375 error
= spd_fill_page(spd
, f
->page
, plen
, poff
, skb
);
1383 if (spd
->nr_pages
- nr_pages
) {
1389 /* update the offset to reflect the linear part skip, if any */
1396 * Map data from the skb to a pipe. Should handle both the linear part,
1397 * the fragments, and the frag list. It does NOT handle frag lists within
1398 * the frag list, if such a thing exists. We'd probably need to recurse to
1399 * handle that cleanly.
1401 int skb_splice_bits(struct sk_buff
*__skb
, unsigned int offset
,
1402 struct pipe_inode_info
*pipe
, unsigned int tlen
,
1405 struct partial_page partial
[PIPE_BUFFERS
];
1406 struct page
*pages
[PIPE_BUFFERS
];
1407 struct splice_pipe_desc spd
= {
1411 .ops
= &sock_pipe_buf_ops
,
1412 .spd_release
= sock_spd_release
,
1414 struct sk_buff
*skb
;
1417 * I'd love to avoid the clone here, but tcp_read_sock()
1418 * ignores reference counts and unconditonally kills the sk_buff
1419 * on return from the actor.
1421 skb
= skb_clone(__skb
, GFP_KERNEL
);
1426 * __skb_splice_bits() only fails if the output has no room left,
1427 * so no point in going over the frag_list for the error case.
1429 if (__skb_splice_bits(skb
, &offset
, &tlen
, &spd
))
1435 * now see if we have a frag_list to map
1437 if (skb_shinfo(skb
)->frag_list
) {
1438 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1440 for (; list
&& tlen
; list
= list
->next
) {
1441 if (__skb_splice_bits(list
, &offset
, &tlen
, &spd
))
1448 * drop our reference to the clone, the pipe consumption will
1455 struct sock
*sk
= __skb
->sk
;
1458 * Drop the socket lock, otherwise we have reverse
1459 * locking dependencies between sk_lock and i_mutex
1460 * here as compared to sendfile(). We enter here
1461 * with the socket lock held, and splice_to_pipe() will
1462 * grab the pipe inode lock. For sendfile() emulation,
1463 * we call into ->sendpage() with the i_mutex lock held
1464 * and networking will grab the socket lock.
1467 ret
= splice_to_pipe(pipe
, &spd
);
1476 * skb_store_bits - store bits from kernel buffer to skb
1477 * @skb: destination buffer
1478 * @offset: offset in destination
1479 * @from: source buffer
1480 * @len: number of bytes to copy
1482 * Copy the specified number of bytes from the source buffer to the
1483 * destination skb. This function handles all the messy bits of
1484 * traversing fragment lists and such.
1487 int skb_store_bits(struct sk_buff
*skb
, int offset
, const void *from
, int len
)
1490 int start
= skb_headlen(skb
);
1492 if (offset
> (int)skb
->len
- len
)
1495 if ((copy
= start
- offset
) > 0) {
1498 skb_copy_to_linear_data_offset(skb
, offset
, from
, copy
);
1499 if ((len
-= copy
) == 0)
1505 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1506 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1509 BUG_TRAP(start
<= offset
+ len
);
1511 end
= start
+ frag
->size
;
1512 if ((copy
= end
- offset
) > 0) {
1518 vaddr
= kmap_skb_frag(frag
);
1519 memcpy(vaddr
+ frag
->page_offset
+ offset
- start
,
1521 kunmap_skb_frag(vaddr
);
1523 if ((len
-= copy
) == 0)
1531 if (skb_shinfo(skb
)->frag_list
) {
1532 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1534 for (; list
; list
= list
->next
) {
1537 BUG_TRAP(start
<= offset
+ len
);
1539 end
= start
+ list
->len
;
1540 if ((copy
= end
- offset
) > 0) {
1543 if (skb_store_bits(list
, offset
- start
,
1546 if ((len
-= copy
) == 0)
1561 EXPORT_SYMBOL(skb_store_bits
);
1563 /* Checksum skb data. */
1565 __wsum
skb_checksum(const struct sk_buff
*skb
, int offset
,
1566 int len
, __wsum csum
)
1568 int start
= skb_headlen(skb
);
1569 int i
, copy
= start
- offset
;
1572 /* Checksum header. */
1576 csum
= csum_partial(skb
->data
+ offset
, copy
, csum
);
1577 if ((len
-= copy
) == 0)
1583 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1586 BUG_TRAP(start
<= offset
+ len
);
1588 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1589 if ((copy
= end
- offset
) > 0) {
1592 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1596 vaddr
= kmap_skb_frag(frag
);
1597 csum2
= csum_partial(vaddr
+ frag
->page_offset
+
1598 offset
- start
, copy
, 0);
1599 kunmap_skb_frag(vaddr
);
1600 csum
= csum_block_add(csum
, csum2
, pos
);
1609 if (skb_shinfo(skb
)->frag_list
) {
1610 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1612 for (; list
; list
= list
->next
) {
1615 BUG_TRAP(start
<= offset
+ len
);
1617 end
= start
+ list
->len
;
1618 if ((copy
= end
- offset
) > 0) {
1622 csum2
= skb_checksum(list
, offset
- start
,
1624 csum
= csum_block_add(csum
, csum2
, pos
);
1625 if ((len
-= copy
) == 0)
1638 /* Both of above in one bottle. */
1640 __wsum
skb_copy_and_csum_bits(const struct sk_buff
*skb
, int offset
,
1641 u8
*to
, int len
, __wsum csum
)
1643 int start
= skb_headlen(skb
);
1644 int i
, copy
= start
- offset
;
1651 csum
= csum_partial_copy_nocheck(skb
->data
+ offset
, to
,
1653 if ((len
-= copy
) == 0)
1660 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1663 BUG_TRAP(start
<= offset
+ len
);
1665 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1666 if ((copy
= end
- offset
) > 0) {
1669 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1673 vaddr
= kmap_skb_frag(frag
);
1674 csum2
= csum_partial_copy_nocheck(vaddr
+
1678 kunmap_skb_frag(vaddr
);
1679 csum
= csum_block_add(csum
, csum2
, pos
);
1689 if (skb_shinfo(skb
)->frag_list
) {
1690 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1692 for (; list
; list
= list
->next
) {
1696 BUG_TRAP(start
<= offset
+ len
);
1698 end
= start
+ list
->len
;
1699 if ((copy
= end
- offset
) > 0) {
1702 csum2
= skb_copy_and_csum_bits(list
,
1705 csum
= csum_block_add(csum
, csum2
, pos
);
1706 if ((len
-= copy
) == 0)
1719 void skb_copy_and_csum_dev(const struct sk_buff
*skb
, u8
*to
)
1724 if (skb
->ip_summed
== CHECKSUM_PARTIAL
)
1725 csstart
= skb
->csum_start
- skb_headroom(skb
);
1727 csstart
= skb_headlen(skb
);
1729 BUG_ON(csstart
> skb_headlen(skb
));
1731 skb_copy_from_linear_data(skb
, to
, csstart
);
1734 if (csstart
!= skb
->len
)
1735 csum
= skb_copy_and_csum_bits(skb
, csstart
, to
+ csstart
,
1736 skb
->len
- csstart
, 0);
1738 if (skb
->ip_summed
== CHECKSUM_PARTIAL
) {
1739 long csstuff
= csstart
+ skb
->csum_offset
;
1741 *((__sum16
*)(to
+ csstuff
)) = csum_fold(csum
);
1746 * skb_dequeue - remove from the head of the queue
1747 * @list: list to dequeue from
1749 * Remove the head of the list. The list lock is taken so the function
1750 * may be used safely with other locking list functions. The head item is
1751 * returned or %NULL if the list is empty.
1754 struct sk_buff
*skb_dequeue(struct sk_buff_head
*list
)
1756 unsigned long flags
;
1757 struct sk_buff
*result
;
1759 spin_lock_irqsave(&list
->lock
, flags
);
1760 result
= __skb_dequeue(list
);
1761 spin_unlock_irqrestore(&list
->lock
, flags
);
1766 * skb_dequeue_tail - remove from the tail of the queue
1767 * @list: list to dequeue from
1769 * Remove the tail of the list. The list lock is taken so the function
1770 * may be used safely with other locking list functions. The tail item is
1771 * returned or %NULL if the list is empty.
1773 struct sk_buff
*skb_dequeue_tail(struct sk_buff_head
*list
)
1775 unsigned long flags
;
1776 struct sk_buff
*result
;
1778 spin_lock_irqsave(&list
->lock
, flags
);
1779 result
= __skb_dequeue_tail(list
);
1780 spin_unlock_irqrestore(&list
->lock
, flags
);
1785 * skb_queue_purge - empty a list
1786 * @list: list to empty
1788 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1789 * the list and one reference dropped. This function takes the list
1790 * lock and is atomic with respect to other list locking functions.
1792 void skb_queue_purge(struct sk_buff_head
*list
)
1794 struct sk_buff
*skb
;
1795 while ((skb
= skb_dequeue(list
)) != NULL
)
1800 * skb_queue_head - queue a buffer at the list head
1801 * @list: list to use
1802 * @newsk: buffer to queue
1804 * Queue a buffer at the start of the list. This function takes the
1805 * list lock and can be used safely with other locking &sk_buff functions
1808 * A buffer cannot be placed on two lists at the same time.
1810 void skb_queue_head(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1812 unsigned long flags
;
1814 spin_lock_irqsave(&list
->lock
, flags
);
1815 __skb_queue_head(list
, newsk
);
1816 spin_unlock_irqrestore(&list
->lock
, flags
);
1820 * skb_queue_tail - queue a buffer at the list tail
1821 * @list: list to use
1822 * @newsk: buffer to queue
1824 * Queue a buffer at the tail of the list. This function takes the
1825 * list lock and can be used safely with other locking &sk_buff functions
1828 * A buffer cannot be placed on two lists at the same time.
1830 void skb_queue_tail(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1832 unsigned long flags
;
1834 spin_lock_irqsave(&list
->lock
, flags
);
1835 __skb_queue_tail(list
, newsk
);
1836 spin_unlock_irqrestore(&list
->lock
, flags
);
1840 * skb_unlink - remove a buffer from a list
1841 * @skb: buffer to remove
1842 * @list: list to use
1844 * Remove a packet from a list. The list locks are taken and this
1845 * function is atomic with respect to other list locked calls
1847 * You must know what list the SKB is on.
1849 void skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
)
1851 unsigned long flags
;
1853 spin_lock_irqsave(&list
->lock
, flags
);
1854 __skb_unlink(skb
, list
);
1855 spin_unlock_irqrestore(&list
->lock
, flags
);
1859 * skb_append - append a buffer
1860 * @old: buffer to insert after
1861 * @newsk: buffer to insert
1862 * @list: list to use
1864 * Place a packet after a given packet in a list. The list locks are taken
1865 * and this function is atomic with respect to other list locked calls.
1866 * A buffer cannot be placed on two lists at the same time.
1868 void skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1870 unsigned long flags
;
1872 spin_lock_irqsave(&list
->lock
, flags
);
1873 __skb_queue_after(list
, old
, newsk
);
1874 spin_unlock_irqrestore(&list
->lock
, flags
);
1879 * skb_insert - insert a buffer
1880 * @old: buffer to insert before
1881 * @newsk: buffer to insert
1882 * @list: list to use
1884 * Place a packet before a given packet in a list. The list locks are
1885 * taken and this function is atomic with respect to other list locked
1888 * A buffer cannot be placed on two lists at the same time.
1890 void skb_insert(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1892 unsigned long flags
;
1894 spin_lock_irqsave(&list
->lock
, flags
);
1895 __skb_insert(newsk
, old
->prev
, old
, list
);
1896 spin_unlock_irqrestore(&list
->lock
, flags
);
1899 static inline void skb_split_inside_header(struct sk_buff
*skb
,
1900 struct sk_buff
* skb1
,
1901 const u32 len
, const int pos
)
1905 skb_copy_from_linear_data_offset(skb
, len
, skb_put(skb1
, pos
- len
),
1907 /* And move data appendix as is. */
1908 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
1909 skb_shinfo(skb1
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
1911 skb_shinfo(skb1
)->nr_frags
= skb_shinfo(skb
)->nr_frags
;
1912 skb_shinfo(skb
)->nr_frags
= 0;
1913 skb1
->data_len
= skb
->data_len
;
1914 skb1
->len
+= skb1
->data_len
;
1917 skb_set_tail_pointer(skb
, len
);
1920 static inline void skb_split_no_header(struct sk_buff
*skb
,
1921 struct sk_buff
* skb1
,
1922 const u32 len
, int pos
)
1925 const int nfrags
= skb_shinfo(skb
)->nr_frags
;
1927 skb_shinfo(skb
)->nr_frags
= 0;
1928 skb1
->len
= skb1
->data_len
= skb
->len
- len
;
1930 skb
->data_len
= len
- pos
;
1932 for (i
= 0; i
< nfrags
; i
++) {
1933 int size
= skb_shinfo(skb
)->frags
[i
].size
;
1935 if (pos
+ size
> len
) {
1936 skb_shinfo(skb1
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1940 * We have two variants in this case:
1941 * 1. Move all the frag to the second
1942 * part, if it is possible. F.e.
1943 * this approach is mandatory for TUX,
1944 * where splitting is expensive.
1945 * 2. Split is accurately. We make this.
1947 get_page(skb_shinfo(skb
)->frags
[i
].page
);
1948 skb_shinfo(skb1
)->frags
[0].page_offset
+= len
- pos
;
1949 skb_shinfo(skb1
)->frags
[0].size
-= len
- pos
;
1950 skb_shinfo(skb
)->frags
[i
].size
= len
- pos
;
1951 skb_shinfo(skb
)->nr_frags
++;
1955 skb_shinfo(skb
)->nr_frags
++;
1958 skb_shinfo(skb1
)->nr_frags
= k
;
1962 * skb_split - Split fragmented skb to two parts at length len.
1963 * @skb: the buffer to split
1964 * @skb1: the buffer to receive the second part
1965 * @len: new length for skb
1967 void skb_split(struct sk_buff
*skb
, struct sk_buff
*skb1
, const u32 len
)
1969 int pos
= skb_headlen(skb
);
1971 if (len
< pos
) /* Split line is inside header. */
1972 skb_split_inside_header(skb
, skb1
, len
, pos
);
1973 else /* Second chunk has no header, nothing to copy. */
1974 skb_split_no_header(skb
, skb1
, len
, pos
);
1978 * skb_prepare_seq_read - Prepare a sequential read of skb data
1979 * @skb: the buffer to read
1980 * @from: lower offset of data to be read
1981 * @to: upper offset of data to be read
1982 * @st: state variable
1984 * Initializes the specified state variable. Must be called before
1985 * invoking skb_seq_read() for the first time.
1987 void skb_prepare_seq_read(struct sk_buff
*skb
, unsigned int from
,
1988 unsigned int to
, struct skb_seq_state
*st
)
1990 st
->lower_offset
= from
;
1991 st
->upper_offset
= to
;
1992 st
->root_skb
= st
->cur_skb
= skb
;
1993 st
->frag_idx
= st
->stepped_offset
= 0;
1994 st
->frag_data
= NULL
;
1998 * skb_seq_read - Sequentially read skb data
1999 * @consumed: number of bytes consumed by the caller so far
2000 * @data: destination pointer for data to be returned
2001 * @st: state variable
2003 * Reads a block of skb data at &consumed relative to the
2004 * lower offset specified to skb_prepare_seq_read(). Assigns
2005 * the head of the data block to &data and returns the length
2006 * of the block or 0 if the end of the skb data or the upper
2007 * offset has been reached.
2009 * The caller is not required to consume all of the data
2010 * returned, i.e. &consumed is typically set to the number
2011 * of bytes already consumed and the next call to
2012 * skb_seq_read() will return the remaining part of the block.
2014 * Note 1: The size of each block of data returned can be arbitary,
2015 * this limitation is the cost for zerocopy seqeuental
2016 * reads of potentially non linear data.
2018 * Note 2: Fragment lists within fragments are not implemented
2019 * at the moment, state->root_skb could be replaced with
2020 * a stack for this purpose.
2022 unsigned int skb_seq_read(unsigned int consumed
, const u8
**data
,
2023 struct skb_seq_state
*st
)
2025 unsigned int block_limit
, abs_offset
= consumed
+ st
->lower_offset
;
2028 if (unlikely(abs_offset
>= st
->upper_offset
))
2032 block_limit
= skb_headlen(st
->cur_skb
);
2034 if (abs_offset
< block_limit
) {
2035 *data
= st
->cur_skb
->data
+ abs_offset
;
2036 return block_limit
- abs_offset
;
2039 if (st
->frag_idx
== 0 && !st
->frag_data
)
2040 st
->stepped_offset
+= skb_headlen(st
->cur_skb
);
2042 while (st
->frag_idx
< skb_shinfo(st
->cur_skb
)->nr_frags
) {
2043 frag
= &skb_shinfo(st
->cur_skb
)->frags
[st
->frag_idx
];
2044 block_limit
= frag
->size
+ st
->stepped_offset
;
2046 if (abs_offset
< block_limit
) {
2048 st
->frag_data
= kmap_skb_frag(frag
);
2050 *data
= (u8
*) st
->frag_data
+ frag
->page_offset
+
2051 (abs_offset
- st
->stepped_offset
);
2053 return block_limit
- abs_offset
;
2056 if (st
->frag_data
) {
2057 kunmap_skb_frag(st
->frag_data
);
2058 st
->frag_data
= NULL
;
2062 st
->stepped_offset
+= frag
->size
;
2065 if (st
->frag_data
) {
2066 kunmap_skb_frag(st
->frag_data
);
2067 st
->frag_data
= NULL
;
2070 if (st
->cur_skb
->next
) {
2071 st
->cur_skb
= st
->cur_skb
->next
;
2074 } else if (st
->root_skb
== st
->cur_skb
&&
2075 skb_shinfo(st
->root_skb
)->frag_list
) {
2076 st
->cur_skb
= skb_shinfo(st
->root_skb
)->frag_list
;
2084 * skb_abort_seq_read - Abort a sequential read of skb data
2085 * @st: state variable
2087 * Must be called if skb_seq_read() was not called until it
2090 void skb_abort_seq_read(struct skb_seq_state
*st
)
2093 kunmap_skb_frag(st
->frag_data
);
2096 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2098 static unsigned int skb_ts_get_next_block(unsigned int offset
, const u8
**text
,
2099 struct ts_config
*conf
,
2100 struct ts_state
*state
)
2102 return skb_seq_read(offset
, text
, TS_SKB_CB(state
));
2105 static void skb_ts_finish(struct ts_config
*conf
, struct ts_state
*state
)
2107 skb_abort_seq_read(TS_SKB_CB(state
));
2111 * skb_find_text - Find a text pattern in skb data
2112 * @skb: the buffer to look in
2113 * @from: search offset
2115 * @config: textsearch configuration
2116 * @state: uninitialized textsearch state variable
2118 * Finds a pattern in the skb data according to the specified
2119 * textsearch configuration. Use textsearch_next() to retrieve
2120 * subsequent occurrences of the pattern. Returns the offset
2121 * to the first occurrence or UINT_MAX if no match was found.
2123 unsigned int skb_find_text(struct sk_buff
*skb
, unsigned int from
,
2124 unsigned int to
, struct ts_config
*config
,
2125 struct ts_state
*state
)
2129 config
->get_next_block
= skb_ts_get_next_block
;
2130 config
->finish
= skb_ts_finish
;
2132 skb_prepare_seq_read(skb
, from
, to
, TS_SKB_CB(state
));
2134 ret
= textsearch_find(config
, state
);
2135 return (ret
<= to
- from
? ret
: UINT_MAX
);
2139 * skb_append_datato_frags: - append the user data to a skb
2140 * @sk: sock structure
2141 * @skb: skb structure to be appened with user data.
2142 * @getfrag: call back function to be used for getting the user data
2143 * @from: pointer to user message iov
2144 * @length: length of the iov message
2146 * Description: This procedure append the user data in the fragment part
2147 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2149 int skb_append_datato_frags(struct sock
*sk
, struct sk_buff
*skb
,
2150 int (*getfrag
)(void *from
, char *to
, int offset
,
2151 int len
, int odd
, struct sk_buff
*skb
),
2152 void *from
, int length
)
2155 skb_frag_t
*frag
= NULL
;
2156 struct page
*page
= NULL
;
2162 /* Return error if we don't have space for new frag */
2163 frg_cnt
= skb_shinfo(skb
)->nr_frags
;
2164 if (frg_cnt
>= MAX_SKB_FRAGS
)
2167 /* allocate a new page for next frag */
2168 page
= alloc_pages(sk
->sk_allocation
, 0);
2170 /* If alloc_page fails just return failure and caller will
2171 * free previous allocated pages by doing kfree_skb()
2176 /* initialize the next frag */
2177 sk
->sk_sndmsg_page
= page
;
2178 sk
->sk_sndmsg_off
= 0;
2179 skb_fill_page_desc(skb
, frg_cnt
, page
, 0, 0);
2180 skb
->truesize
+= PAGE_SIZE
;
2181 atomic_add(PAGE_SIZE
, &sk
->sk_wmem_alloc
);
2183 /* get the new initialized frag */
2184 frg_cnt
= skb_shinfo(skb
)->nr_frags
;
2185 frag
= &skb_shinfo(skb
)->frags
[frg_cnt
- 1];
2187 /* copy the user data to page */
2188 left
= PAGE_SIZE
- frag
->page_offset
;
2189 copy
= (length
> left
)? left
: length
;
2191 ret
= getfrag(from
, (page_address(frag
->page
) +
2192 frag
->page_offset
+ frag
->size
),
2193 offset
, copy
, 0, skb
);
2197 /* copy was successful so update the size parameters */
2198 sk
->sk_sndmsg_off
+= copy
;
2201 skb
->data_len
+= copy
;
2205 } while (length
> 0);
2211 * skb_pull_rcsum - pull skb and update receive checksum
2212 * @skb: buffer to update
2213 * @len: length of data pulled
2215 * This function performs an skb_pull on the packet and updates
2216 * the CHECKSUM_COMPLETE checksum. It should be used on
2217 * receive path processing instead of skb_pull unless you know
2218 * that the checksum difference is zero (e.g., a valid IP header)
2219 * or you are setting ip_summed to CHECKSUM_NONE.
2221 unsigned char *skb_pull_rcsum(struct sk_buff
*skb
, unsigned int len
)
2223 BUG_ON(len
> skb
->len
);
2225 BUG_ON(skb
->len
< skb
->data_len
);
2226 skb_postpull_rcsum(skb
, skb
->data
, len
);
2227 return skb
->data
+= len
;
2230 EXPORT_SYMBOL_GPL(skb_pull_rcsum
);
2233 * skb_segment - Perform protocol segmentation on skb.
2234 * @skb: buffer to segment
2235 * @features: features for the output path (see dev->features)
2237 * This function performs segmentation on the given skb. It returns
2238 * a pointer to the first in a list of new skbs for the segments.
2239 * In case of error it returns ERR_PTR(err).
2241 struct sk_buff
*skb_segment(struct sk_buff
*skb
, int features
)
2243 struct sk_buff
*segs
= NULL
;
2244 struct sk_buff
*tail
= NULL
;
2245 unsigned int mss
= skb_shinfo(skb
)->gso_size
;
2246 unsigned int doffset
= skb
->data
- skb_mac_header(skb
);
2247 unsigned int offset
= doffset
;
2248 unsigned int headroom
;
2250 int sg
= features
& NETIF_F_SG
;
2251 int nfrags
= skb_shinfo(skb
)->nr_frags
;
2256 __skb_push(skb
, doffset
);
2257 headroom
= skb_headroom(skb
);
2258 pos
= skb_headlen(skb
);
2261 struct sk_buff
*nskb
;
2267 len
= skb
->len
- offset
;
2271 hsize
= skb_headlen(skb
) - offset
;
2274 if (hsize
> len
|| !sg
)
2277 nskb
= alloc_skb(hsize
+ doffset
+ headroom
, GFP_ATOMIC
);
2278 if (unlikely(!nskb
))
2287 nskb
->dev
= skb
->dev
;
2288 skb_copy_queue_mapping(nskb
, skb
);
2289 nskb
->priority
= skb
->priority
;
2290 nskb
->protocol
= skb
->protocol
;
2291 nskb
->dst
= dst_clone(skb
->dst
);
2292 memcpy(nskb
->cb
, skb
->cb
, sizeof(skb
->cb
));
2293 nskb
->pkt_type
= skb
->pkt_type
;
2294 nskb
->mac_len
= skb
->mac_len
;
2296 skb_reserve(nskb
, headroom
);
2297 skb_reset_mac_header(nskb
);
2298 skb_set_network_header(nskb
, skb
->mac_len
);
2299 nskb
->transport_header
= (nskb
->network_header
+
2300 skb_network_header_len(skb
));
2301 skb_copy_from_linear_data(skb
, skb_put(nskb
, doffset
),
2304 nskb
->csum
= skb_copy_and_csum_bits(skb
, offset
,
2310 frag
= skb_shinfo(nskb
)->frags
;
2313 nskb
->ip_summed
= CHECKSUM_PARTIAL
;
2314 nskb
->csum
= skb
->csum
;
2315 skb_copy_from_linear_data_offset(skb
, offset
,
2316 skb_put(nskb
, hsize
), hsize
);
2318 while (pos
< offset
+ len
) {
2319 BUG_ON(i
>= nfrags
);
2321 *frag
= skb_shinfo(skb
)->frags
[i
];
2322 get_page(frag
->page
);
2326 frag
->page_offset
+= offset
- pos
;
2327 frag
->size
-= offset
- pos
;
2332 if (pos
+ size
<= offset
+ len
) {
2336 frag
->size
-= pos
+ size
- (offset
+ len
);
2343 skb_shinfo(nskb
)->nr_frags
= k
;
2344 nskb
->data_len
= len
- hsize
;
2345 nskb
->len
+= nskb
->data_len
;
2346 nskb
->truesize
+= nskb
->data_len
;
2347 } while ((offset
+= len
) < skb
->len
);
2352 while ((skb
= segs
)) {
2356 return ERR_PTR(err
);
2359 EXPORT_SYMBOL_GPL(skb_segment
);
2361 void __init
skb_init(void)
2363 skbuff_head_cache
= kmem_cache_create("skbuff_head_cache",
2364 sizeof(struct sk_buff
),
2366 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
,
2368 skbuff_fclone_cache
= kmem_cache_create("skbuff_fclone_cache",
2369 (2*sizeof(struct sk_buff
)) +
2372 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
,
2377 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2378 * @skb: Socket buffer containing the buffers to be mapped
2379 * @sg: The scatter-gather list to map into
2380 * @offset: The offset into the buffer's contents to start mapping
2381 * @len: Length of buffer space to be mapped
2383 * Fill the specified scatter-gather list with mappings/pointers into a
2384 * region of the buffer space attached to a socket buffer.
2387 __skb_to_sgvec(struct sk_buff
*skb
, struct scatterlist
*sg
, int offset
, int len
)
2389 int start
= skb_headlen(skb
);
2390 int i
, copy
= start
- offset
;
2396 sg_set_buf(sg
, skb
->data
+ offset
, copy
);
2398 if ((len
-= copy
) == 0)
2403 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
2406 BUG_TRAP(start
<= offset
+ len
);
2408 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
2409 if ((copy
= end
- offset
) > 0) {
2410 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
2414 sg_set_page(&sg
[elt
], frag
->page
, copy
,
2415 frag
->page_offset
+offset
-start
);
2424 if (skb_shinfo(skb
)->frag_list
) {
2425 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
2427 for (; list
; list
= list
->next
) {
2430 BUG_TRAP(start
<= offset
+ len
);
2432 end
= start
+ list
->len
;
2433 if ((copy
= end
- offset
) > 0) {
2436 elt
+= __skb_to_sgvec(list
, sg
+elt
, offset
- start
,
2438 if ((len
-= copy
) == 0)
2449 int skb_to_sgvec(struct sk_buff
*skb
, struct scatterlist
*sg
, int offset
, int len
)
2451 int nsg
= __skb_to_sgvec(skb
, sg
, offset
, len
);
2453 sg_mark_end(&sg
[nsg
- 1]);
2459 * skb_cow_data - Check that a socket buffer's data buffers are writable
2460 * @skb: The socket buffer to check.
2461 * @tailbits: Amount of trailing space to be added
2462 * @trailer: Returned pointer to the skb where the @tailbits space begins
2464 * Make sure that the data buffers attached to a socket buffer are
2465 * writable. If they are not, private copies are made of the data buffers
2466 * and the socket buffer is set to use these instead.
2468 * If @tailbits is given, make sure that there is space to write @tailbits
2469 * bytes of data beyond current end of socket buffer. @trailer will be
2470 * set to point to the skb in which this space begins.
2472 * The number of scatterlist elements required to completely map the
2473 * COW'd and extended socket buffer will be returned.
2475 int skb_cow_data(struct sk_buff
*skb
, int tailbits
, struct sk_buff
**trailer
)
2479 struct sk_buff
*skb1
, **skb_p
;
2481 /* If skb is cloned or its head is paged, reallocate
2482 * head pulling out all the pages (pages are considered not writable
2483 * at the moment even if they are anonymous).
2485 if ((skb_cloned(skb
) || skb_shinfo(skb
)->nr_frags
) &&
2486 __pskb_pull_tail(skb
, skb_pagelen(skb
)-skb_headlen(skb
)) == NULL
)
2489 /* Easy case. Most of packets will go this way. */
2490 if (!skb_shinfo(skb
)->frag_list
) {
2491 /* A little of trouble, not enough of space for trailer.
2492 * This should not happen, when stack is tuned to generate
2493 * good frames. OK, on miss we reallocate and reserve even more
2494 * space, 128 bytes is fair. */
2496 if (skb_tailroom(skb
) < tailbits
&&
2497 pskb_expand_head(skb
, 0, tailbits
-skb_tailroom(skb
)+128, GFP_ATOMIC
))
2505 /* Misery. We are in troubles, going to mincer fragments... */
2508 skb_p
= &skb_shinfo(skb
)->frag_list
;
2511 while ((skb1
= *skb_p
) != NULL
) {
2514 /* The fragment is partially pulled by someone,
2515 * this can happen on input. Copy it and everything
2518 if (skb_shared(skb1
))
2521 /* If the skb is the last, worry about trailer. */
2523 if (skb1
->next
== NULL
&& tailbits
) {
2524 if (skb_shinfo(skb1
)->nr_frags
||
2525 skb_shinfo(skb1
)->frag_list
||
2526 skb_tailroom(skb1
) < tailbits
)
2527 ntail
= tailbits
+ 128;
2533 skb_shinfo(skb1
)->nr_frags
||
2534 skb_shinfo(skb1
)->frag_list
) {
2535 struct sk_buff
*skb2
;
2537 /* Fuck, we are miserable poor guys... */
2539 skb2
= skb_copy(skb1
, GFP_ATOMIC
);
2541 skb2
= skb_copy_expand(skb1
,
2545 if (unlikely(skb2
== NULL
))
2549 skb_set_owner_w(skb2
, skb1
->sk
);
2551 /* Looking around. Are we still alive?
2552 * OK, link new skb, drop old one */
2554 skb2
->next
= skb1
->next
;
2561 skb_p
= &skb1
->next
;
2568 * skb_partial_csum_set - set up and verify partial csum values for packet
2569 * @skb: the skb to set
2570 * @start: the number of bytes after skb->data to start checksumming.
2571 * @off: the offset from start to place the checksum.
2573 * For untrusted partially-checksummed packets, we need to make sure the values
2574 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
2576 * This function checks and sets those values and skb->ip_summed: if this
2577 * returns false you should drop the packet.
2579 bool skb_partial_csum_set(struct sk_buff
*skb
, u16 start
, u16 off
)
2581 if (unlikely(start
> skb
->len
- 2) ||
2582 unlikely((int)start
+ off
> skb
->len
- 2)) {
2583 if (net_ratelimit())
2585 "bad partial csum: csum=%u/%u len=%u\n",
2586 start
, off
, skb
->len
);
2589 skb
->ip_summed
= CHECKSUM_PARTIAL
;
2590 skb
->csum_start
= skb_headroom(skb
) + start
;
2591 skb
->csum_offset
= off
;
2595 EXPORT_SYMBOL(___pskb_trim
);
2596 EXPORT_SYMBOL(__kfree_skb
);
2597 EXPORT_SYMBOL(kfree_skb
);
2598 EXPORT_SYMBOL(__pskb_pull_tail
);
2599 EXPORT_SYMBOL(__alloc_skb
);
2600 EXPORT_SYMBOL(__netdev_alloc_skb
);
2601 EXPORT_SYMBOL(pskb_copy
);
2602 EXPORT_SYMBOL(pskb_expand_head
);
2603 EXPORT_SYMBOL(skb_checksum
);
2604 EXPORT_SYMBOL(skb_clone
);
2605 EXPORT_SYMBOL(skb_copy
);
2606 EXPORT_SYMBOL(skb_copy_and_csum_bits
);
2607 EXPORT_SYMBOL(skb_copy_and_csum_dev
);
2608 EXPORT_SYMBOL(skb_copy_bits
);
2609 EXPORT_SYMBOL(skb_copy_expand
);
2610 EXPORT_SYMBOL(skb_over_panic
);
2611 EXPORT_SYMBOL(skb_pad
);
2612 EXPORT_SYMBOL(skb_realloc_headroom
);
2613 EXPORT_SYMBOL(skb_under_panic
);
2614 EXPORT_SYMBOL(skb_dequeue
);
2615 EXPORT_SYMBOL(skb_dequeue_tail
);
2616 EXPORT_SYMBOL(skb_insert
);
2617 EXPORT_SYMBOL(skb_queue_purge
);
2618 EXPORT_SYMBOL(skb_queue_head
);
2619 EXPORT_SYMBOL(skb_queue_tail
);
2620 EXPORT_SYMBOL(skb_unlink
);
2621 EXPORT_SYMBOL(skb_append
);
2622 EXPORT_SYMBOL(skb_split
);
2623 EXPORT_SYMBOL(skb_prepare_seq_read
);
2624 EXPORT_SYMBOL(skb_seq_read
);
2625 EXPORT_SYMBOL(skb_abort_seq_read
);
2626 EXPORT_SYMBOL(skb_find_text
);
2627 EXPORT_SYMBOL(skb_append_datato_frags
);
2629 EXPORT_SYMBOL_GPL(skb_to_sgvec
);
2630 EXPORT_SYMBOL_GPL(skb_cow_data
);
2631 EXPORT_SYMBOL_GPL(skb_partial_csum_set
);