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>
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>
59 #include <net/protocol.h>
62 #include <net/checksum.h>
65 #include <asm/uaccess.h>
66 #include <asm/system.h>
70 static struct kmem_cache
*skbuff_head_cache __read_mostly
;
71 static struct kmem_cache
*skbuff_fclone_cache __read_mostly
;
73 static void sock_pipe_buf_release(struct pipe_inode_info
*pipe
,
74 struct pipe_buffer
*buf
)
76 struct sk_buff
*skb
= (struct sk_buff
*) buf
->private;
81 static void sock_pipe_buf_get(struct pipe_inode_info
*pipe
,
82 struct pipe_buffer
*buf
)
84 struct sk_buff
*skb
= (struct sk_buff
*) buf
->private;
89 static int sock_pipe_buf_steal(struct pipe_inode_info
*pipe
,
90 struct pipe_buffer
*buf
)
96 /* Pipe buffer operations for a socket. */
97 static struct pipe_buf_operations sock_pipe_buf_ops
= {
99 .map
= generic_pipe_buf_map
,
100 .unmap
= generic_pipe_buf_unmap
,
101 .confirm
= generic_pipe_buf_confirm
,
102 .release
= sock_pipe_buf_release
,
103 .steal
= sock_pipe_buf_steal
,
104 .get
= sock_pipe_buf_get
,
108 * Keep out-of-line to prevent kernel bloat.
109 * __builtin_return_address is not used because it is not always
114 * skb_over_panic - private function
119 * Out of line support code for skb_put(). Not user callable.
121 void skb_over_panic(struct sk_buff
*skb
, int sz
, void *here
)
123 printk(KERN_EMERG
"skb_over_panic: text:%p len:%d put:%d head:%p "
124 "data:%p tail:%#lx end:%#lx dev:%s\n",
125 here
, skb
->len
, sz
, skb
->head
, skb
->data
,
126 (unsigned long)skb
->tail
, (unsigned long)skb
->end
,
127 skb
->dev
? skb
->dev
->name
: "<NULL>");
132 * skb_under_panic - private function
137 * Out of line support code for skb_push(). Not user callable.
140 void skb_under_panic(struct sk_buff
*skb
, int sz
, void *here
)
142 printk(KERN_EMERG
"skb_under_panic: text:%p len:%d put:%d head:%p "
143 "data:%p tail:%#lx end:%#lx dev:%s\n",
144 here
, skb
->len
, sz
, skb
->head
, skb
->data
,
145 (unsigned long)skb
->tail
, (unsigned long)skb
->end
,
146 skb
->dev
? skb
->dev
->name
: "<NULL>");
150 void skb_truesize_bug(struct sk_buff
*skb
)
152 printk(KERN_ERR
"SKB BUG: Invalid truesize (%u) "
153 "len=%u, sizeof(sk_buff)=%Zd\n",
154 skb
->truesize
, skb
->len
, sizeof(struct sk_buff
));
156 EXPORT_SYMBOL(skb_truesize_bug
);
158 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
159 * 'private' fields and also do memory statistics to find all the
165 * __alloc_skb - allocate a network buffer
166 * @size: size to allocate
167 * @gfp_mask: allocation mask
168 * @fclone: allocate from fclone cache instead of head cache
169 * and allocate a cloned (child) skb
170 * @node: numa node to allocate memory on
172 * Allocate a new &sk_buff. The returned buffer has no headroom and a
173 * tail room of size bytes. The object has a reference count of one.
174 * The return is the buffer. On a failure the return is %NULL.
176 * Buffers may only be allocated from interrupts using a @gfp_mask of
179 struct sk_buff
*__alloc_skb(unsigned int size
, gfp_t gfp_mask
,
180 int fclone
, int node
)
182 struct kmem_cache
*cache
;
183 struct skb_shared_info
*shinfo
;
187 cache
= fclone
? skbuff_fclone_cache
: skbuff_head_cache
;
190 skb
= kmem_cache_alloc_node(cache
, gfp_mask
& ~__GFP_DMA
, node
);
194 size
= SKB_DATA_ALIGN(size
);
195 data
= kmalloc_node_track_caller(size
+ sizeof(struct skb_shared_info
),
201 * Only clear those fields we need to clear, not those that we will
202 * actually initialise below. Hence, don't put any more fields after
203 * the tail pointer in struct sk_buff!
205 memset(skb
, 0, offsetof(struct sk_buff
, tail
));
206 skb
->truesize
= size
+ sizeof(struct sk_buff
);
207 atomic_set(&skb
->users
, 1);
210 skb_reset_tail_pointer(skb
);
211 skb
->end
= skb
->tail
+ size
;
212 /* make sure we initialize shinfo sequentially */
213 shinfo
= skb_shinfo(skb
);
214 atomic_set(&shinfo
->dataref
, 1);
215 shinfo
->nr_frags
= 0;
216 shinfo
->gso_size
= 0;
217 shinfo
->gso_segs
= 0;
218 shinfo
->gso_type
= 0;
219 shinfo
->ip6_frag_id
= 0;
220 shinfo
->frag_list
= NULL
;
223 struct sk_buff
*child
= skb
+ 1;
224 atomic_t
*fclone_ref
= (atomic_t
*) (child
+ 1);
226 skb
->fclone
= SKB_FCLONE_ORIG
;
227 atomic_set(fclone_ref
, 1);
229 child
->fclone
= SKB_FCLONE_UNAVAILABLE
;
234 kmem_cache_free(cache
, skb
);
240 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
241 * @dev: network device to receive on
242 * @length: length to allocate
243 * @gfp_mask: get_free_pages mask, passed to alloc_skb
245 * Allocate a new &sk_buff and assign it a usage count of one. The
246 * buffer has unspecified headroom built in. Users should allocate
247 * the headroom they think they need without accounting for the
248 * built in space. The built in space is used for optimisations.
250 * %NULL is returned if there is no free memory.
252 struct sk_buff
*__netdev_alloc_skb(struct net_device
*dev
,
253 unsigned int length
, gfp_t gfp_mask
)
255 int node
= dev
->dev
.parent
? dev_to_node(dev
->dev
.parent
) : -1;
258 skb
= __alloc_skb(length
+ NET_SKB_PAD
, gfp_mask
, 0, node
);
260 skb_reserve(skb
, NET_SKB_PAD
);
267 * dev_alloc_skb - allocate an skbuff for receiving
268 * @length: length to allocate
270 * Allocate a new &sk_buff and assign it a usage count of one. The
271 * buffer has unspecified headroom built in. Users should allocate
272 * the headroom they think they need without accounting for the
273 * built in space. The built in space is used for optimisations.
275 * %NULL is returned if there is no free memory. Although this function
276 * allocates memory it can be called from an interrupt.
278 struct sk_buff
*dev_alloc_skb(unsigned int length
)
281 * There is more code here than it seems:
282 * __dev_alloc_skb is an inline
284 return __dev_alloc_skb(length
, GFP_ATOMIC
);
286 EXPORT_SYMBOL(dev_alloc_skb
);
288 static void skb_drop_list(struct sk_buff
**listp
)
290 struct sk_buff
*list
= *listp
;
295 struct sk_buff
*this = list
;
301 static inline void skb_drop_fraglist(struct sk_buff
*skb
)
303 skb_drop_list(&skb_shinfo(skb
)->frag_list
);
306 static void skb_clone_fraglist(struct sk_buff
*skb
)
308 struct sk_buff
*list
;
310 for (list
= skb_shinfo(skb
)->frag_list
; list
; list
= list
->next
)
314 static void skb_release_data(struct sk_buff
*skb
)
317 !atomic_sub_return(skb
->nohdr
? (1 << SKB_DATAREF_SHIFT
) + 1 : 1,
318 &skb_shinfo(skb
)->dataref
)) {
319 if (skb_shinfo(skb
)->nr_frags
) {
321 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
322 put_page(skb_shinfo(skb
)->frags
[i
].page
);
325 if (skb_shinfo(skb
)->frag_list
)
326 skb_drop_fraglist(skb
);
333 * Free an skbuff by memory without cleaning the state.
335 static void kfree_skbmem(struct sk_buff
*skb
)
337 struct sk_buff
*other
;
338 atomic_t
*fclone_ref
;
340 switch (skb
->fclone
) {
341 case SKB_FCLONE_UNAVAILABLE
:
342 kmem_cache_free(skbuff_head_cache
, skb
);
345 case SKB_FCLONE_ORIG
:
346 fclone_ref
= (atomic_t
*) (skb
+ 2);
347 if (atomic_dec_and_test(fclone_ref
))
348 kmem_cache_free(skbuff_fclone_cache
, skb
);
351 case SKB_FCLONE_CLONE
:
352 fclone_ref
= (atomic_t
*) (skb
+ 1);
355 /* The clone portion is available for
356 * fast-cloning again.
358 skb
->fclone
= SKB_FCLONE_UNAVAILABLE
;
360 if (atomic_dec_and_test(fclone_ref
))
361 kmem_cache_free(skbuff_fclone_cache
, other
);
366 /* Free everything but the sk_buff shell. */
367 static void skb_release_all(struct sk_buff
*skb
)
369 dst_release(skb
->dst
);
371 secpath_put(skb
->sp
);
373 if (skb
->destructor
) {
375 skb
->destructor(skb
);
377 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
378 nf_conntrack_put(skb
->nfct
);
379 nf_conntrack_put_reasm(skb
->nfct_reasm
);
381 #ifdef CONFIG_BRIDGE_NETFILTER
382 nf_bridge_put(skb
->nf_bridge
);
384 /* XXX: IS this still necessary? - JHS */
385 #ifdef CONFIG_NET_SCHED
387 #ifdef CONFIG_NET_CLS_ACT
391 skb_release_data(skb
);
395 * __kfree_skb - private function
398 * Free an sk_buff. Release anything attached to the buffer.
399 * Clean the state. This is an internal helper function. Users should
400 * always call kfree_skb
403 void __kfree_skb(struct sk_buff
*skb
)
405 skb_release_all(skb
);
410 * kfree_skb - free an sk_buff
411 * @skb: buffer to free
413 * Drop a reference to the buffer and free it if the usage count has
416 void kfree_skb(struct sk_buff
*skb
)
420 if (likely(atomic_read(&skb
->users
) == 1))
422 else if (likely(!atomic_dec_and_test(&skb
->users
)))
427 static void __copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
429 new->tstamp
= old
->tstamp
;
431 new->transport_header
= old
->transport_header
;
432 new->network_header
= old
->network_header
;
433 new->mac_header
= old
->mac_header
;
434 new->dst
= dst_clone(old
->dst
);
436 new->sp
= secpath_get(old
->sp
);
438 memcpy(new->cb
, old
->cb
, sizeof(old
->cb
));
439 new->csum_start
= old
->csum_start
;
440 new->csum_offset
= old
->csum_offset
;
441 new->local_df
= old
->local_df
;
442 new->pkt_type
= old
->pkt_type
;
443 new->ip_summed
= old
->ip_summed
;
444 skb_copy_queue_mapping(new, old
);
445 new->priority
= old
->priority
;
446 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
447 new->ipvs_property
= old
->ipvs_property
;
449 new->protocol
= old
->protocol
;
450 new->mark
= old
->mark
;
452 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
453 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
454 new->nf_trace
= old
->nf_trace
;
456 #ifdef CONFIG_NET_SCHED
457 new->tc_index
= old
->tc_index
;
458 #ifdef CONFIG_NET_CLS_ACT
459 new->tc_verd
= old
->tc_verd
;
462 new->vlan_tci
= old
->vlan_tci
;
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 #if defined(CONFIG_MAC80211) || defined(CONFIG_MAC80211_MODULE)
491 atomic_set(&n
->users
, 1);
493 atomic_inc(&(skb_shinfo(skb
)->dataref
));
501 * skb_morph - morph one skb into another
502 * @dst: the skb to receive the contents
503 * @src: the skb to supply the contents
505 * This is identical to skb_clone except that the target skb is
506 * supplied by the user.
508 * The target skb is returned upon exit.
510 struct sk_buff
*skb_morph(struct sk_buff
*dst
, struct sk_buff
*src
)
512 skb_release_all(dst
);
513 return __skb_clone(dst
, src
);
515 EXPORT_SYMBOL_GPL(skb_morph
);
518 * skb_clone - duplicate an sk_buff
519 * @skb: buffer to clone
520 * @gfp_mask: allocation priority
522 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
523 * copies share the same packet data but not structure. The new
524 * buffer has a reference count of 1. If the allocation fails the
525 * function returns %NULL otherwise the new buffer is returned.
527 * If this function is called from an interrupt gfp_mask() must be
531 struct sk_buff
*skb_clone(struct sk_buff
*skb
, gfp_t gfp_mask
)
536 if (skb
->fclone
== SKB_FCLONE_ORIG
&&
537 n
->fclone
== SKB_FCLONE_UNAVAILABLE
) {
538 atomic_t
*fclone_ref
= (atomic_t
*) (n
+ 1);
539 n
->fclone
= SKB_FCLONE_CLONE
;
540 atomic_inc(fclone_ref
);
542 n
= kmem_cache_alloc(skbuff_head_cache
, gfp_mask
);
545 n
->fclone
= SKB_FCLONE_UNAVAILABLE
;
548 return __skb_clone(n
, skb
);
551 static void copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
553 #ifndef NET_SKBUFF_DATA_USES_OFFSET
555 * Shift between the two data areas in bytes
557 unsigned long offset
= new->data
- old
->data
;
560 __copy_skb_header(new, old
);
562 #ifndef NET_SKBUFF_DATA_USES_OFFSET
563 /* {transport,network,mac}_header are relative to skb->head */
564 new->transport_header
+= offset
;
565 new->network_header
+= offset
;
566 new->mac_header
+= offset
;
568 skb_shinfo(new)->gso_size
= skb_shinfo(old
)->gso_size
;
569 skb_shinfo(new)->gso_segs
= skb_shinfo(old
)->gso_segs
;
570 skb_shinfo(new)->gso_type
= skb_shinfo(old
)->gso_type
;
574 * skb_copy - create private copy of an sk_buff
575 * @skb: buffer to copy
576 * @gfp_mask: allocation priority
578 * Make a copy of both an &sk_buff and its data. This is used when the
579 * caller wishes to modify the data and needs a private copy of the
580 * data to alter. Returns %NULL on failure or the pointer to the buffer
581 * on success. The returned buffer has a reference count of 1.
583 * As by-product this function converts non-linear &sk_buff to linear
584 * one, so that &sk_buff becomes completely private and caller is allowed
585 * to modify all the data of returned buffer. This means that this
586 * function is not recommended for use in circumstances when only
587 * header is going to be modified. Use pskb_copy() instead.
590 struct sk_buff
*skb_copy(const struct sk_buff
*skb
, gfp_t gfp_mask
)
592 int headerlen
= skb
->data
- skb
->head
;
594 * Allocate the copy buffer
597 #ifdef NET_SKBUFF_DATA_USES_OFFSET
598 n
= alloc_skb(skb
->end
+ skb
->data_len
, gfp_mask
);
600 n
= alloc_skb(skb
->end
- skb
->head
+ skb
->data_len
, gfp_mask
);
605 /* Set the data pointer */
606 skb_reserve(n
, headerlen
);
607 /* Set the tail pointer and length */
608 skb_put(n
, skb
->len
);
610 if (skb_copy_bits(skb
, -headerlen
, n
->head
, headerlen
+ skb
->len
))
613 copy_skb_header(n
, skb
);
619 * pskb_copy - create copy of an sk_buff with private head.
620 * @skb: buffer to copy
621 * @gfp_mask: allocation priority
623 * Make a copy of both an &sk_buff and part of its data, located
624 * in header. Fragmented data remain shared. This is used when
625 * the caller wishes to modify only header of &sk_buff and needs
626 * private copy of the header to alter. Returns %NULL on failure
627 * or the pointer to the buffer on success.
628 * The returned buffer has a reference count of 1.
631 struct sk_buff
*pskb_copy(struct sk_buff
*skb
, gfp_t gfp_mask
)
634 * Allocate the copy buffer
637 #ifdef NET_SKBUFF_DATA_USES_OFFSET
638 n
= alloc_skb(skb
->end
, gfp_mask
);
640 n
= alloc_skb(skb
->end
- skb
->head
, gfp_mask
);
645 /* Set the data pointer */
646 skb_reserve(n
, skb
->data
- skb
->head
);
647 /* Set the tail pointer and length */
648 skb_put(n
, skb_headlen(skb
));
650 skb_copy_from_linear_data(skb
, n
->data
, n
->len
);
652 n
->truesize
+= skb
->data_len
;
653 n
->data_len
= skb
->data_len
;
656 if (skb_shinfo(skb
)->nr_frags
) {
659 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
660 skb_shinfo(n
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
661 get_page(skb_shinfo(n
)->frags
[i
].page
);
663 skb_shinfo(n
)->nr_frags
= i
;
666 if (skb_shinfo(skb
)->frag_list
) {
667 skb_shinfo(n
)->frag_list
= skb_shinfo(skb
)->frag_list
;
668 skb_clone_fraglist(n
);
671 copy_skb_header(n
, skb
);
677 * pskb_expand_head - reallocate header of &sk_buff
678 * @skb: buffer to reallocate
679 * @nhead: room to add at head
680 * @ntail: room to add at tail
681 * @gfp_mask: allocation priority
683 * Expands (or creates identical copy, if &nhead and &ntail are zero)
684 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
685 * reference count of 1. Returns zero in the case of success or error,
686 * if expansion failed. In the last case, &sk_buff is not changed.
688 * All the pointers pointing into skb header may change and must be
689 * reloaded after call to this function.
692 int pskb_expand_head(struct sk_buff
*skb
, int nhead
, int ntail
,
697 #ifdef NET_SKBUFF_DATA_USES_OFFSET
698 int size
= nhead
+ skb
->end
+ ntail
;
700 int size
= nhead
+ (skb
->end
- skb
->head
) + ntail
;
707 size
= SKB_DATA_ALIGN(size
);
709 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
713 /* Copy only real data... and, alas, header. This should be
714 * optimized for the cases when header is void. */
715 #ifdef NET_SKBUFF_DATA_USES_OFFSET
716 memcpy(data
+ nhead
, skb
->head
, skb
->tail
);
718 memcpy(data
+ nhead
, skb
->head
, skb
->tail
- skb
->head
);
720 memcpy(data
+ size
, skb_end_pointer(skb
),
721 sizeof(struct skb_shared_info
));
723 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
724 get_page(skb_shinfo(skb
)->frags
[i
].page
);
726 if (skb_shinfo(skb
)->frag_list
)
727 skb_clone_fraglist(skb
);
729 skb_release_data(skb
);
731 off
= (data
+ nhead
) - skb
->head
;
735 #ifdef NET_SKBUFF_DATA_USES_OFFSET
739 skb
->end
= skb
->head
+ size
;
741 /* {transport,network,mac}_header and tail are relative to skb->head */
743 skb
->transport_header
+= off
;
744 skb
->network_header
+= off
;
745 skb
->mac_header
+= off
;
746 skb
->csum_start
+= nhead
;
750 atomic_set(&skb_shinfo(skb
)->dataref
, 1);
757 /* Make private copy of skb with writable head and some headroom */
759 struct sk_buff
*skb_realloc_headroom(struct sk_buff
*skb
, unsigned int headroom
)
761 struct sk_buff
*skb2
;
762 int delta
= headroom
- skb_headroom(skb
);
765 skb2
= pskb_copy(skb
, GFP_ATOMIC
);
767 skb2
= skb_clone(skb
, GFP_ATOMIC
);
768 if (skb2
&& pskb_expand_head(skb2
, SKB_DATA_ALIGN(delta
), 0,
779 * skb_copy_expand - copy and expand sk_buff
780 * @skb: buffer to copy
781 * @newheadroom: new free bytes at head
782 * @newtailroom: new free bytes at tail
783 * @gfp_mask: allocation priority
785 * Make a copy of both an &sk_buff and its data and while doing so
786 * allocate additional space.
788 * This is used when the caller wishes to modify the data and needs a
789 * private copy of the data to alter as well as more space for new fields.
790 * Returns %NULL on failure or the pointer to the buffer
791 * on success. The returned buffer has a reference count of 1.
793 * You must pass %GFP_ATOMIC as the allocation priority if this function
794 * is called from an interrupt.
796 struct sk_buff
*skb_copy_expand(const struct sk_buff
*skb
,
797 int newheadroom
, int newtailroom
,
801 * Allocate the copy buffer
803 struct sk_buff
*n
= alloc_skb(newheadroom
+ skb
->len
+ newtailroom
,
805 int oldheadroom
= skb_headroom(skb
);
806 int head_copy_len
, head_copy_off
;
812 skb_reserve(n
, newheadroom
);
814 /* Set the tail pointer and length */
815 skb_put(n
, skb
->len
);
817 head_copy_len
= oldheadroom
;
819 if (newheadroom
<= head_copy_len
)
820 head_copy_len
= newheadroom
;
822 head_copy_off
= newheadroom
- head_copy_len
;
824 /* Copy the linear header and data. */
825 if (skb_copy_bits(skb
, -head_copy_len
, n
->head
+ head_copy_off
,
826 skb
->len
+ head_copy_len
))
829 copy_skb_header(n
, skb
);
831 off
= newheadroom
- oldheadroom
;
832 n
->csum_start
+= off
;
833 #ifdef NET_SKBUFF_DATA_USES_OFFSET
834 n
->transport_header
+= off
;
835 n
->network_header
+= off
;
836 n
->mac_header
+= off
;
843 * skb_pad - zero pad the tail of an skb
844 * @skb: buffer to pad
847 * Ensure that a buffer is followed by a padding area that is zero
848 * filled. Used by network drivers which may DMA or transfer data
849 * beyond the buffer end onto the wire.
851 * May return error in out of memory cases. The skb is freed on error.
854 int skb_pad(struct sk_buff
*skb
, int pad
)
859 /* If the skbuff is non linear tailroom is always zero.. */
860 if (!skb_cloned(skb
) && skb_tailroom(skb
) >= pad
) {
861 memset(skb
->data
+skb
->len
, 0, pad
);
865 ntail
= skb
->data_len
+ pad
- (skb
->end
- skb
->tail
);
866 if (likely(skb_cloned(skb
) || ntail
> 0)) {
867 err
= pskb_expand_head(skb
, 0, ntail
, GFP_ATOMIC
);
872 /* FIXME: The use of this function with non-linear skb's really needs
875 err
= skb_linearize(skb
);
879 memset(skb
->data
+ skb
->len
, 0, pad
);
888 * skb_put - add data to a buffer
889 * @skb: buffer to use
890 * @len: amount of data to add
892 * This function extends the used data area of the buffer. If this would
893 * exceed the total buffer size the kernel will panic. A pointer to the
894 * first byte of the extra data is returned.
896 unsigned char *skb_put(struct sk_buff
*skb
, unsigned int len
)
898 unsigned char *tmp
= skb_tail_pointer(skb
);
899 SKB_LINEAR_ASSERT(skb
);
902 if (unlikely(skb
->tail
> skb
->end
))
903 skb_over_panic(skb
, len
, __builtin_return_address(0));
906 EXPORT_SYMBOL(skb_put
);
909 * skb_push - add data to the start of a buffer
910 * @skb: buffer to use
911 * @len: amount of data to add
913 * This function extends the used data area of the buffer at the buffer
914 * start. If this would exceed the total buffer headroom the kernel will
915 * panic. A pointer to the first byte of the extra data is returned.
917 unsigned char *skb_push(struct sk_buff
*skb
, unsigned int len
)
921 if (unlikely(skb
->data
<skb
->head
))
922 skb_under_panic(skb
, len
, __builtin_return_address(0));
925 EXPORT_SYMBOL(skb_push
);
928 * skb_pull - remove data from the start of a buffer
929 * @skb: buffer to use
930 * @len: amount of data to remove
932 * This function removes data from the start of a buffer, returning
933 * the memory to the headroom. A pointer to the next data in the buffer
934 * is returned. Once the data has been pulled future pushes will overwrite
937 unsigned char *skb_pull(struct sk_buff
*skb
, unsigned int len
)
939 return unlikely(len
> skb
->len
) ? NULL
: __skb_pull(skb
, len
);
941 EXPORT_SYMBOL(skb_pull
);
944 * skb_trim - remove end from a buffer
945 * @skb: buffer to alter
948 * Cut the length of a buffer down by removing data from the tail. If
949 * the buffer is already under the length specified it is not modified.
950 * The skb must be linear.
952 void skb_trim(struct sk_buff
*skb
, unsigned int len
)
955 __skb_trim(skb
, len
);
957 EXPORT_SYMBOL(skb_trim
);
959 /* Trims skb to length len. It can change skb pointers.
962 int ___pskb_trim(struct sk_buff
*skb
, unsigned int len
)
964 struct sk_buff
**fragp
;
965 struct sk_buff
*frag
;
966 int offset
= skb_headlen(skb
);
967 int nfrags
= skb_shinfo(skb
)->nr_frags
;
971 if (skb_cloned(skb
) &&
972 unlikely((err
= pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))))
979 for (; i
< nfrags
; i
++) {
980 int end
= offset
+ skb_shinfo(skb
)->frags
[i
].size
;
987 skb_shinfo(skb
)->frags
[i
++].size
= len
- offset
;
990 skb_shinfo(skb
)->nr_frags
= i
;
992 for (; i
< nfrags
; i
++)
993 put_page(skb_shinfo(skb
)->frags
[i
].page
);
995 if (skb_shinfo(skb
)->frag_list
)
996 skb_drop_fraglist(skb
);
1000 for (fragp
= &skb_shinfo(skb
)->frag_list
; (frag
= *fragp
);
1001 fragp
= &frag
->next
) {
1002 int end
= offset
+ frag
->len
;
1004 if (skb_shared(frag
)) {
1005 struct sk_buff
*nfrag
;
1007 nfrag
= skb_clone(frag
, GFP_ATOMIC
);
1008 if (unlikely(!nfrag
))
1011 nfrag
->next
= frag
->next
;
1023 unlikely((err
= pskb_trim(frag
, len
- offset
))))
1027 skb_drop_list(&frag
->next
);
1032 if (len
> skb_headlen(skb
)) {
1033 skb
->data_len
-= skb
->len
- len
;
1038 skb_set_tail_pointer(skb
, len
);
1045 * __pskb_pull_tail - advance tail of skb header
1046 * @skb: buffer to reallocate
1047 * @delta: number of bytes to advance tail
1049 * The function makes a sense only on a fragmented &sk_buff,
1050 * it expands header moving its tail forward and copying necessary
1051 * data from fragmented part.
1053 * &sk_buff MUST have reference count of 1.
1055 * Returns %NULL (and &sk_buff does not change) if pull failed
1056 * or value of new tail of skb in the case of success.
1058 * All the pointers pointing into skb header may change and must be
1059 * reloaded after call to this function.
1062 /* Moves tail of skb head forward, copying data from fragmented part,
1063 * when it is necessary.
1064 * 1. It may fail due to malloc failure.
1065 * 2. It may change skb pointers.
1067 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1069 unsigned char *__pskb_pull_tail(struct sk_buff
*skb
, int delta
)
1071 /* If skb has not enough free space at tail, get new one
1072 * plus 128 bytes for future expansions. If we have enough
1073 * room at tail, reallocate without expansion only if skb is cloned.
1075 int i
, k
, eat
= (skb
->tail
+ delta
) - skb
->end
;
1077 if (eat
> 0 || skb_cloned(skb
)) {
1078 if (pskb_expand_head(skb
, 0, eat
> 0 ? eat
+ 128 : 0,
1083 if (skb_copy_bits(skb
, skb_headlen(skb
), skb_tail_pointer(skb
), delta
))
1086 /* Optimization: no fragments, no reasons to preestimate
1087 * size of pulled pages. Superb.
1089 if (!skb_shinfo(skb
)->frag_list
)
1092 /* Estimate size of pulled pages. */
1094 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1095 if (skb_shinfo(skb
)->frags
[i
].size
>= eat
)
1097 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
1100 /* If we need update frag list, we are in troubles.
1101 * Certainly, it possible to add an offset to skb data,
1102 * but taking into account that pulling is expected to
1103 * be very rare operation, it is worth to fight against
1104 * further bloating skb head and crucify ourselves here instead.
1105 * Pure masohism, indeed. 8)8)
1108 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1109 struct sk_buff
*clone
= NULL
;
1110 struct sk_buff
*insp
= NULL
;
1115 if (list
->len
<= eat
) {
1116 /* Eaten as whole. */
1121 /* Eaten partially. */
1123 if (skb_shared(list
)) {
1124 /* Sucks! We need to fork list. :-( */
1125 clone
= skb_clone(list
, GFP_ATOMIC
);
1131 /* This may be pulled without
1135 if (!pskb_pull(list
, eat
)) {
1144 /* Free pulled out fragments. */
1145 while ((list
= skb_shinfo(skb
)->frag_list
) != insp
) {
1146 skb_shinfo(skb
)->frag_list
= list
->next
;
1149 /* And insert new clone at head. */
1152 skb_shinfo(skb
)->frag_list
= clone
;
1155 /* Success! Now we may commit changes to skb data. */
1160 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1161 if (skb_shinfo(skb
)->frags
[i
].size
<= eat
) {
1162 put_page(skb_shinfo(skb
)->frags
[i
].page
);
1163 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
1165 skb_shinfo(skb
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1167 skb_shinfo(skb
)->frags
[k
].page_offset
+= eat
;
1168 skb_shinfo(skb
)->frags
[k
].size
-= eat
;
1174 skb_shinfo(skb
)->nr_frags
= k
;
1177 skb
->data_len
-= delta
;
1179 return skb_tail_pointer(skb
);
1182 /* Copy some data bits from skb to kernel buffer. */
1184 int skb_copy_bits(const struct sk_buff
*skb
, int offset
, void *to
, int len
)
1187 int start
= skb_headlen(skb
);
1189 if (offset
> (int)skb
->len
- len
)
1193 if ((copy
= start
- offset
) > 0) {
1196 skb_copy_from_linear_data_offset(skb
, offset
, to
, copy
);
1197 if ((len
-= copy
) == 0)
1203 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1206 WARN_ON(start
> offset
+ len
);
1208 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1209 if ((copy
= end
- offset
) > 0) {
1215 vaddr
= kmap_skb_frag(&skb_shinfo(skb
)->frags
[i
]);
1217 vaddr
+ skb_shinfo(skb
)->frags
[i
].page_offset
+
1218 offset
- start
, copy
);
1219 kunmap_skb_frag(vaddr
);
1221 if ((len
-= copy
) == 0)
1229 if (skb_shinfo(skb
)->frag_list
) {
1230 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1232 for (; list
; list
= list
->next
) {
1235 WARN_ON(start
> offset
+ len
);
1237 end
= start
+ list
->len
;
1238 if ((copy
= end
- offset
) > 0) {
1241 if (skb_copy_bits(list
, offset
- start
,
1244 if ((len
-= copy
) == 0)
1260 * Callback from splice_to_pipe(), if we need to release some pages
1261 * at the end of the spd in case we error'ed out in filling the pipe.
1263 static void sock_spd_release(struct splice_pipe_desc
*spd
, unsigned int i
)
1265 struct sk_buff
*skb
= (struct sk_buff
*) spd
->partial
[i
].private;
1271 * Fill page/offset/length into spd, if it can hold more pages.
1273 static inline int spd_fill_page(struct splice_pipe_desc
*spd
, struct page
*page
,
1274 unsigned int len
, unsigned int offset
,
1275 struct sk_buff
*skb
)
1277 if (unlikely(spd
->nr_pages
== PIPE_BUFFERS
))
1280 spd
->pages
[spd
->nr_pages
] = page
;
1281 spd
->partial
[spd
->nr_pages
].len
= len
;
1282 spd
->partial
[spd
->nr_pages
].offset
= offset
;
1283 spd
->partial
[spd
->nr_pages
].private = (unsigned long) skb_get(skb
);
1288 static inline void __segment_seek(struct page
**page
, unsigned int *poff
,
1289 unsigned int *plen
, unsigned int off
)
1292 *page
+= *poff
/ PAGE_SIZE
;
1293 *poff
= *poff
% PAGE_SIZE
;
1297 static inline int __splice_segment(struct page
*page
, unsigned int poff
,
1298 unsigned int plen
, unsigned int *off
,
1299 unsigned int *len
, struct sk_buff
*skb
,
1300 struct splice_pipe_desc
*spd
)
1305 /* skip this segment if already processed */
1311 /* ignore any bits we already processed */
1313 __segment_seek(&page
, &poff
, &plen
, *off
);
1318 unsigned int flen
= min(*len
, plen
);
1320 /* the linear region may spread across several pages */
1321 flen
= min_t(unsigned int, flen
, PAGE_SIZE
- poff
);
1323 if (spd_fill_page(spd
, page
, flen
, poff
, skb
))
1326 __segment_seek(&page
, &poff
, &plen
, flen
);
1329 } while (*len
&& plen
);
1335 * Map linear and fragment data from the skb to spd. It reports failure if the
1336 * pipe is full or if we already spliced the requested length.
1338 static int __skb_splice_bits(struct sk_buff
*skb
, unsigned int *offset
,
1340 struct splice_pipe_desc
*spd
)
1345 * map the linear part
1347 if (__splice_segment(virt_to_page(skb
->data
),
1348 (unsigned long) skb
->data
& (PAGE_SIZE
- 1),
1350 offset
, len
, skb
, spd
))
1354 * then map the fragments
1356 for (seg
= 0; seg
< skb_shinfo(skb
)->nr_frags
; seg
++) {
1357 const skb_frag_t
*f
= &skb_shinfo(skb
)->frags
[seg
];
1359 if (__splice_segment(f
->page
, f
->page_offset
, f
->size
,
1360 offset
, len
, skb
, spd
))
1368 * Map data from the skb to a pipe. Should handle both the linear part,
1369 * the fragments, and the frag list. It does NOT handle frag lists within
1370 * the frag list, if such a thing exists. We'd probably need to recurse to
1371 * handle that cleanly.
1373 int skb_splice_bits(struct sk_buff
*__skb
, unsigned int offset
,
1374 struct pipe_inode_info
*pipe
, unsigned int tlen
,
1377 struct partial_page partial
[PIPE_BUFFERS
];
1378 struct page
*pages
[PIPE_BUFFERS
];
1379 struct splice_pipe_desc spd
= {
1383 .ops
= &sock_pipe_buf_ops
,
1384 .spd_release
= sock_spd_release
,
1386 struct sk_buff
*skb
;
1389 * I'd love to avoid the clone here, but tcp_read_sock()
1390 * ignores reference counts and unconditonally kills the sk_buff
1391 * on return from the actor.
1393 skb
= skb_clone(__skb
, GFP_KERNEL
);
1398 * __skb_splice_bits() only fails if the output has no room left,
1399 * so no point in going over the frag_list for the error case.
1401 if (__skb_splice_bits(skb
, &offset
, &tlen
, &spd
))
1407 * now see if we have a frag_list to map
1409 if (skb_shinfo(skb
)->frag_list
) {
1410 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1412 for (; list
&& tlen
; list
= list
->next
) {
1413 if (__skb_splice_bits(list
, &offset
, &tlen
, &spd
))
1420 * drop our reference to the clone, the pipe consumption will
1427 struct sock
*sk
= __skb
->sk
;
1430 * Drop the socket lock, otherwise we have reverse
1431 * locking dependencies between sk_lock and i_mutex
1432 * here as compared to sendfile(). We enter here
1433 * with the socket lock held, and splice_to_pipe() will
1434 * grab the pipe inode lock. For sendfile() emulation,
1435 * we call into ->sendpage() with the i_mutex lock held
1436 * and networking will grab the socket lock.
1439 ret
= splice_to_pipe(pipe
, &spd
);
1448 * skb_store_bits - store bits from kernel buffer to skb
1449 * @skb: destination buffer
1450 * @offset: offset in destination
1451 * @from: source buffer
1452 * @len: number of bytes to copy
1454 * Copy the specified number of bytes from the source buffer to the
1455 * destination skb. This function handles all the messy bits of
1456 * traversing fragment lists and such.
1459 int skb_store_bits(struct sk_buff
*skb
, int offset
, const void *from
, int len
)
1462 int start
= skb_headlen(skb
);
1464 if (offset
> (int)skb
->len
- len
)
1467 if ((copy
= start
- offset
) > 0) {
1470 skb_copy_to_linear_data_offset(skb
, offset
, from
, copy
);
1471 if ((len
-= copy
) == 0)
1477 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1478 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1481 WARN_ON(start
> offset
+ len
);
1483 end
= start
+ frag
->size
;
1484 if ((copy
= end
- offset
) > 0) {
1490 vaddr
= kmap_skb_frag(frag
);
1491 memcpy(vaddr
+ frag
->page_offset
+ offset
- start
,
1493 kunmap_skb_frag(vaddr
);
1495 if ((len
-= copy
) == 0)
1503 if (skb_shinfo(skb
)->frag_list
) {
1504 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1506 for (; list
; list
= list
->next
) {
1509 WARN_ON(start
> offset
+ len
);
1511 end
= start
+ list
->len
;
1512 if ((copy
= end
- offset
) > 0) {
1515 if (skb_store_bits(list
, offset
- start
,
1518 if ((len
-= copy
) == 0)
1533 EXPORT_SYMBOL(skb_store_bits
);
1535 /* Checksum skb data. */
1537 __wsum
skb_checksum(const struct sk_buff
*skb
, int offset
,
1538 int len
, __wsum csum
)
1540 int start
= skb_headlen(skb
);
1541 int i
, copy
= start
- offset
;
1544 /* Checksum header. */
1548 csum
= csum_partial(skb
->data
+ offset
, copy
, csum
);
1549 if ((len
-= copy
) == 0)
1555 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1558 WARN_ON(start
> offset
+ len
);
1560 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1561 if ((copy
= end
- offset
) > 0) {
1564 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1568 vaddr
= kmap_skb_frag(frag
);
1569 csum2
= csum_partial(vaddr
+ frag
->page_offset
+
1570 offset
- start
, copy
, 0);
1571 kunmap_skb_frag(vaddr
);
1572 csum
= csum_block_add(csum
, csum2
, pos
);
1581 if (skb_shinfo(skb
)->frag_list
) {
1582 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1584 for (; list
; list
= list
->next
) {
1587 WARN_ON(start
> offset
+ len
);
1589 end
= start
+ list
->len
;
1590 if ((copy
= end
- offset
) > 0) {
1594 csum2
= skb_checksum(list
, offset
- start
,
1596 csum
= csum_block_add(csum
, csum2
, pos
);
1597 if ((len
-= copy
) == 0)
1610 /* Both of above in one bottle. */
1612 __wsum
skb_copy_and_csum_bits(const struct sk_buff
*skb
, int offset
,
1613 u8
*to
, int len
, __wsum csum
)
1615 int start
= skb_headlen(skb
);
1616 int i
, copy
= start
- offset
;
1623 csum
= csum_partial_copy_nocheck(skb
->data
+ offset
, to
,
1625 if ((len
-= copy
) == 0)
1632 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1635 WARN_ON(start
> offset
+ len
);
1637 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1638 if ((copy
= end
- offset
) > 0) {
1641 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1645 vaddr
= kmap_skb_frag(frag
);
1646 csum2
= csum_partial_copy_nocheck(vaddr
+
1650 kunmap_skb_frag(vaddr
);
1651 csum
= csum_block_add(csum
, csum2
, pos
);
1661 if (skb_shinfo(skb
)->frag_list
) {
1662 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1664 for (; list
; list
= list
->next
) {
1668 WARN_ON(start
> offset
+ len
);
1670 end
= start
+ list
->len
;
1671 if ((copy
= end
- offset
) > 0) {
1674 csum2
= skb_copy_and_csum_bits(list
,
1677 csum
= csum_block_add(csum
, csum2
, pos
);
1678 if ((len
-= copy
) == 0)
1691 void skb_copy_and_csum_dev(const struct sk_buff
*skb
, u8
*to
)
1696 if (skb
->ip_summed
== CHECKSUM_PARTIAL
)
1697 csstart
= skb
->csum_start
- skb_headroom(skb
);
1699 csstart
= skb_headlen(skb
);
1701 BUG_ON(csstart
> skb_headlen(skb
));
1703 skb_copy_from_linear_data(skb
, to
, csstart
);
1706 if (csstart
!= skb
->len
)
1707 csum
= skb_copy_and_csum_bits(skb
, csstart
, to
+ csstart
,
1708 skb
->len
- csstart
, 0);
1710 if (skb
->ip_summed
== CHECKSUM_PARTIAL
) {
1711 long csstuff
= csstart
+ skb
->csum_offset
;
1713 *((__sum16
*)(to
+ csstuff
)) = csum_fold(csum
);
1718 * skb_dequeue - remove from the head of the queue
1719 * @list: list to dequeue from
1721 * Remove the head of the list. The list lock is taken so the function
1722 * may be used safely with other locking list functions. The head item is
1723 * returned or %NULL if the list is empty.
1726 struct sk_buff
*skb_dequeue(struct sk_buff_head
*list
)
1728 unsigned long flags
;
1729 struct sk_buff
*result
;
1731 spin_lock_irqsave(&list
->lock
, flags
);
1732 result
= __skb_dequeue(list
);
1733 spin_unlock_irqrestore(&list
->lock
, flags
);
1738 * skb_dequeue_tail - remove from the tail of the queue
1739 * @list: list to dequeue from
1741 * Remove the tail of the list. The list lock is taken so the function
1742 * may be used safely with other locking list functions. The tail item is
1743 * returned or %NULL if the list is empty.
1745 struct sk_buff
*skb_dequeue_tail(struct sk_buff_head
*list
)
1747 unsigned long flags
;
1748 struct sk_buff
*result
;
1750 spin_lock_irqsave(&list
->lock
, flags
);
1751 result
= __skb_dequeue_tail(list
);
1752 spin_unlock_irqrestore(&list
->lock
, flags
);
1757 * skb_queue_purge - empty a list
1758 * @list: list to empty
1760 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1761 * the list and one reference dropped. This function takes the list
1762 * lock and is atomic with respect to other list locking functions.
1764 void skb_queue_purge(struct sk_buff_head
*list
)
1766 struct sk_buff
*skb
;
1767 while ((skb
= skb_dequeue(list
)) != NULL
)
1772 * skb_queue_head - queue a buffer at the list head
1773 * @list: list to use
1774 * @newsk: buffer to queue
1776 * Queue a buffer at the start of the list. This function takes the
1777 * list lock and can be used safely with other locking &sk_buff functions
1780 * A buffer cannot be placed on two lists at the same time.
1782 void skb_queue_head(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1784 unsigned long flags
;
1786 spin_lock_irqsave(&list
->lock
, flags
);
1787 __skb_queue_head(list
, newsk
);
1788 spin_unlock_irqrestore(&list
->lock
, flags
);
1792 * skb_queue_tail - queue a buffer at the list tail
1793 * @list: list to use
1794 * @newsk: buffer to queue
1796 * Queue a buffer at the tail of the list. This function takes the
1797 * list lock and can be used safely with other locking &sk_buff functions
1800 * A buffer cannot be placed on two lists at the same time.
1802 void skb_queue_tail(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1804 unsigned long flags
;
1806 spin_lock_irqsave(&list
->lock
, flags
);
1807 __skb_queue_tail(list
, newsk
);
1808 spin_unlock_irqrestore(&list
->lock
, flags
);
1812 * skb_unlink - remove a buffer from a list
1813 * @skb: buffer to remove
1814 * @list: list to use
1816 * Remove a packet from a list. The list locks are taken and this
1817 * function is atomic with respect to other list locked calls
1819 * You must know what list the SKB is on.
1821 void skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
)
1823 unsigned long flags
;
1825 spin_lock_irqsave(&list
->lock
, flags
);
1826 __skb_unlink(skb
, list
);
1827 spin_unlock_irqrestore(&list
->lock
, flags
);
1831 * skb_append - append a buffer
1832 * @old: buffer to insert after
1833 * @newsk: buffer to insert
1834 * @list: list to use
1836 * Place a packet after a given packet in a list. The list locks are taken
1837 * and this function is atomic with respect to other list locked calls.
1838 * A buffer cannot be placed on two lists at the same time.
1840 void skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1842 unsigned long flags
;
1844 spin_lock_irqsave(&list
->lock
, flags
);
1845 __skb_queue_after(list
, old
, newsk
);
1846 spin_unlock_irqrestore(&list
->lock
, flags
);
1851 * skb_insert - insert a buffer
1852 * @old: buffer to insert before
1853 * @newsk: buffer to insert
1854 * @list: list to use
1856 * Place a packet before a given packet in a list. The list locks are
1857 * taken and this function is atomic with respect to other list locked
1860 * A buffer cannot be placed on two lists at the same time.
1862 void skb_insert(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1864 unsigned long flags
;
1866 spin_lock_irqsave(&list
->lock
, flags
);
1867 __skb_insert(newsk
, old
->prev
, old
, list
);
1868 spin_unlock_irqrestore(&list
->lock
, flags
);
1871 static inline void skb_split_inside_header(struct sk_buff
*skb
,
1872 struct sk_buff
* skb1
,
1873 const u32 len
, const int pos
)
1877 skb_copy_from_linear_data_offset(skb
, len
, skb_put(skb1
, pos
- len
),
1879 /* And move data appendix as is. */
1880 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
1881 skb_shinfo(skb1
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
1883 skb_shinfo(skb1
)->nr_frags
= skb_shinfo(skb
)->nr_frags
;
1884 skb_shinfo(skb
)->nr_frags
= 0;
1885 skb1
->data_len
= skb
->data_len
;
1886 skb1
->len
+= skb1
->data_len
;
1889 skb_set_tail_pointer(skb
, len
);
1892 static inline void skb_split_no_header(struct sk_buff
*skb
,
1893 struct sk_buff
* skb1
,
1894 const u32 len
, int pos
)
1897 const int nfrags
= skb_shinfo(skb
)->nr_frags
;
1899 skb_shinfo(skb
)->nr_frags
= 0;
1900 skb1
->len
= skb1
->data_len
= skb
->len
- len
;
1902 skb
->data_len
= len
- pos
;
1904 for (i
= 0; i
< nfrags
; i
++) {
1905 int size
= skb_shinfo(skb
)->frags
[i
].size
;
1907 if (pos
+ size
> len
) {
1908 skb_shinfo(skb1
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1912 * We have two variants in this case:
1913 * 1. Move all the frag to the second
1914 * part, if it is possible. F.e.
1915 * this approach is mandatory for TUX,
1916 * where splitting is expensive.
1917 * 2. Split is accurately. We make this.
1919 get_page(skb_shinfo(skb
)->frags
[i
].page
);
1920 skb_shinfo(skb1
)->frags
[0].page_offset
+= len
- pos
;
1921 skb_shinfo(skb1
)->frags
[0].size
-= len
- pos
;
1922 skb_shinfo(skb
)->frags
[i
].size
= len
- pos
;
1923 skb_shinfo(skb
)->nr_frags
++;
1927 skb_shinfo(skb
)->nr_frags
++;
1930 skb_shinfo(skb1
)->nr_frags
= k
;
1934 * skb_split - Split fragmented skb to two parts at length len.
1935 * @skb: the buffer to split
1936 * @skb1: the buffer to receive the second part
1937 * @len: new length for skb
1939 void skb_split(struct sk_buff
*skb
, struct sk_buff
*skb1
, const u32 len
)
1941 int pos
= skb_headlen(skb
);
1943 if (len
< pos
) /* Split line is inside header. */
1944 skb_split_inside_header(skb
, skb1
, len
, pos
);
1945 else /* Second chunk has no header, nothing to copy. */
1946 skb_split_no_header(skb
, skb1
, len
, pos
);
1950 * skb_prepare_seq_read - Prepare a sequential read of skb data
1951 * @skb: the buffer to read
1952 * @from: lower offset of data to be read
1953 * @to: upper offset of data to be read
1954 * @st: state variable
1956 * Initializes the specified state variable. Must be called before
1957 * invoking skb_seq_read() for the first time.
1959 void skb_prepare_seq_read(struct sk_buff
*skb
, unsigned int from
,
1960 unsigned int to
, struct skb_seq_state
*st
)
1962 st
->lower_offset
= from
;
1963 st
->upper_offset
= to
;
1964 st
->root_skb
= st
->cur_skb
= skb
;
1965 st
->frag_idx
= st
->stepped_offset
= 0;
1966 st
->frag_data
= NULL
;
1970 * skb_seq_read - Sequentially read skb data
1971 * @consumed: number of bytes consumed by the caller so far
1972 * @data: destination pointer for data to be returned
1973 * @st: state variable
1975 * Reads a block of skb data at &consumed relative to the
1976 * lower offset specified to skb_prepare_seq_read(). Assigns
1977 * the head of the data block to &data and returns the length
1978 * of the block or 0 if the end of the skb data or the upper
1979 * offset has been reached.
1981 * The caller is not required to consume all of the data
1982 * returned, i.e. &consumed is typically set to the number
1983 * of bytes already consumed and the next call to
1984 * skb_seq_read() will return the remaining part of the block.
1986 * Note 1: The size of each block of data returned can be arbitary,
1987 * this limitation is the cost for zerocopy seqeuental
1988 * reads of potentially non linear data.
1990 * Note 2: Fragment lists within fragments are not implemented
1991 * at the moment, state->root_skb could be replaced with
1992 * a stack for this purpose.
1994 unsigned int skb_seq_read(unsigned int consumed
, const u8
**data
,
1995 struct skb_seq_state
*st
)
1997 unsigned int block_limit
, abs_offset
= consumed
+ st
->lower_offset
;
2000 if (unlikely(abs_offset
>= st
->upper_offset
))
2004 block_limit
= skb_headlen(st
->cur_skb
);
2006 if (abs_offset
< block_limit
) {
2007 *data
= st
->cur_skb
->data
+ abs_offset
;
2008 return block_limit
- abs_offset
;
2011 if (st
->frag_idx
== 0 && !st
->frag_data
)
2012 st
->stepped_offset
+= skb_headlen(st
->cur_skb
);
2014 while (st
->frag_idx
< skb_shinfo(st
->cur_skb
)->nr_frags
) {
2015 frag
= &skb_shinfo(st
->cur_skb
)->frags
[st
->frag_idx
];
2016 block_limit
= frag
->size
+ st
->stepped_offset
;
2018 if (abs_offset
< block_limit
) {
2020 st
->frag_data
= kmap_skb_frag(frag
);
2022 *data
= (u8
*) st
->frag_data
+ frag
->page_offset
+
2023 (abs_offset
- st
->stepped_offset
);
2025 return block_limit
- abs_offset
;
2028 if (st
->frag_data
) {
2029 kunmap_skb_frag(st
->frag_data
);
2030 st
->frag_data
= NULL
;
2034 st
->stepped_offset
+= frag
->size
;
2037 if (st
->frag_data
) {
2038 kunmap_skb_frag(st
->frag_data
);
2039 st
->frag_data
= NULL
;
2042 if (st
->cur_skb
->next
) {
2043 st
->cur_skb
= st
->cur_skb
->next
;
2046 } else if (st
->root_skb
== st
->cur_skb
&&
2047 skb_shinfo(st
->root_skb
)->frag_list
) {
2048 st
->cur_skb
= skb_shinfo(st
->root_skb
)->frag_list
;
2056 * skb_abort_seq_read - Abort a sequential read of skb data
2057 * @st: state variable
2059 * Must be called if skb_seq_read() was not called until it
2062 void skb_abort_seq_read(struct skb_seq_state
*st
)
2065 kunmap_skb_frag(st
->frag_data
);
2068 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2070 static unsigned int skb_ts_get_next_block(unsigned int offset
, const u8
**text
,
2071 struct ts_config
*conf
,
2072 struct ts_state
*state
)
2074 return skb_seq_read(offset
, text
, TS_SKB_CB(state
));
2077 static void skb_ts_finish(struct ts_config
*conf
, struct ts_state
*state
)
2079 skb_abort_seq_read(TS_SKB_CB(state
));
2083 * skb_find_text - Find a text pattern in skb data
2084 * @skb: the buffer to look in
2085 * @from: search offset
2087 * @config: textsearch configuration
2088 * @state: uninitialized textsearch state variable
2090 * Finds a pattern in the skb data according to the specified
2091 * textsearch configuration. Use textsearch_next() to retrieve
2092 * subsequent occurrences of the pattern. Returns the offset
2093 * to the first occurrence or UINT_MAX if no match was found.
2095 unsigned int skb_find_text(struct sk_buff
*skb
, unsigned int from
,
2096 unsigned int to
, struct ts_config
*config
,
2097 struct ts_state
*state
)
2101 config
->get_next_block
= skb_ts_get_next_block
;
2102 config
->finish
= skb_ts_finish
;
2104 skb_prepare_seq_read(skb
, from
, to
, TS_SKB_CB(state
));
2106 ret
= textsearch_find(config
, state
);
2107 return (ret
<= to
- from
? ret
: UINT_MAX
);
2111 * skb_append_datato_frags: - append the user data to a skb
2112 * @sk: sock structure
2113 * @skb: skb structure to be appened with user data.
2114 * @getfrag: call back function to be used for getting the user data
2115 * @from: pointer to user message iov
2116 * @length: length of the iov message
2118 * Description: This procedure append the user data in the fragment part
2119 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2121 int skb_append_datato_frags(struct sock
*sk
, struct sk_buff
*skb
,
2122 int (*getfrag
)(void *from
, char *to
, int offset
,
2123 int len
, int odd
, struct sk_buff
*skb
),
2124 void *from
, int length
)
2127 skb_frag_t
*frag
= NULL
;
2128 struct page
*page
= NULL
;
2134 /* Return error if we don't have space for new frag */
2135 frg_cnt
= skb_shinfo(skb
)->nr_frags
;
2136 if (frg_cnt
>= MAX_SKB_FRAGS
)
2139 /* allocate a new page for next frag */
2140 page
= alloc_pages(sk
->sk_allocation
, 0);
2142 /* If alloc_page fails just return failure and caller will
2143 * free previous allocated pages by doing kfree_skb()
2148 /* initialize the next frag */
2149 sk
->sk_sndmsg_page
= page
;
2150 sk
->sk_sndmsg_off
= 0;
2151 skb_fill_page_desc(skb
, frg_cnt
, page
, 0, 0);
2152 skb
->truesize
+= PAGE_SIZE
;
2153 atomic_add(PAGE_SIZE
, &sk
->sk_wmem_alloc
);
2155 /* get the new initialized frag */
2156 frg_cnt
= skb_shinfo(skb
)->nr_frags
;
2157 frag
= &skb_shinfo(skb
)->frags
[frg_cnt
- 1];
2159 /* copy the user data to page */
2160 left
= PAGE_SIZE
- frag
->page_offset
;
2161 copy
= (length
> left
)? left
: length
;
2163 ret
= getfrag(from
, (page_address(frag
->page
) +
2164 frag
->page_offset
+ frag
->size
),
2165 offset
, copy
, 0, skb
);
2169 /* copy was successful so update the size parameters */
2170 sk
->sk_sndmsg_off
+= copy
;
2173 skb
->data_len
+= copy
;
2177 } while (length
> 0);
2183 * skb_pull_rcsum - pull skb and update receive checksum
2184 * @skb: buffer to update
2185 * @len: length of data pulled
2187 * This function performs an skb_pull on the packet and updates
2188 * the CHECKSUM_COMPLETE checksum. It should be used on
2189 * receive path processing instead of skb_pull unless you know
2190 * that the checksum difference is zero (e.g., a valid IP header)
2191 * or you are setting ip_summed to CHECKSUM_NONE.
2193 unsigned char *skb_pull_rcsum(struct sk_buff
*skb
, unsigned int len
)
2195 BUG_ON(len
> skb
->len
);
2197 BUG_ON(skb
->len
< skb
->data_len
);
2198 skb_postpull_rcsum(skb
, skb
->data
, len
);
2199 return skb
->data
+= len
;
2202 EXPORT_SYMBOL_GPL(skb_pull_rcsum
);
2205 * skb_segment - Perform protocol segmentation on skb.
2206 * @skb: buffer to segment
2207 * @features: features for the output path (see dev->features)
2209 * This function performs segmentation on the given skb. It returns
2210 * a pointer to the first in a list of new skbs for the segments.
2211 * In case of error it returns ERR_PTR(err).
2213 struct sk_buff
*skb_segment(struct sk_buff
*skb
, int features
)
2215 struct sk_buff
*segs
= NULL
;
2216 struct sk_buff
*tail
= NULL
;
2217 unsigned int mss
= skb_shinfo(skb
)->gso_size
;
2218 unsigned int doffset
= skb
->data
- skb_mac_header(skb
);
2219 unsigned int offset
= doffset
;
2220 unsigned int headroom
;
2222 int sg
= features
& NETIF_F_SG
;
2223 int nfrags
= skb_shinfo(skb
)->nr_frags
;
2228 __skb_push(skb
, doffset
);
2229 headroom
= skb_headroom(skb
);
2230 pos
= skb_headlen(skb
);
2233 struct sk_buff
*nskb
;
2239 len
= skb
->len
- offset
;
2243 hsize
= skb_headlen(skb
) - offset
;
2246 if (hsize
> len
|| !sg
)
2249 nskb
= alloc_skb(hsize
+ doffset
+ headroom
, GFP_ATOMIC
);
2250 if (unlikely(!nskb
))
2259 __copy_skb_header(nskb
, skb
);
2260 nskb
->mac_len
= skb
->mac_len
;
2262 skb_reserve(nskb
, headroom
);
2263 skb_reset_mac_header(nskb
);
2264 skb_set_network_header(nskb
, skb
->mac_len
);
2265 nskb
->transport_header
= (nskb
->network_header
+
2266 skb_network_header_len(skb
));
2267 skb_copy_from_linear_data(skb
, skb_put(nskb
, doffset
),
2270 nskb
->ip_summed
= CHECKSUM_NONE
;
2271 nskb
->csum
= skb_copy_and_csum_bits(skb
, offset
,
2277 frag
= skb_shinfo(nskb
)->frags
;
2280 skb_copy_from_linear_data_offset(skb
, offset
,
2281 skb_put(nskb
, hsize
), hsize
);
2283 while (pos
< offset
+ len
) {
2284 BUG_ON(i
>= nfrags
);
2286 *frag
= skb_shinfo(skb
)->frags
[i
];
2287 get_page(frag
->page
);
2291 frag
->page_offset
+= offset
- pos
;
2292 frag
->size
-= offset
- pos
;
2297 if (pos
+ size
<= offset
+ len
) {
2301 frag
->size
-= pos
+ size
- (offset
+ len
);
2308 skb_shinfo(nskb
)->nr_frags
= k
;
2309 nskb
->data_len
= len
- hsize
;
2310 nskb
->len
+= nskb
->data_len
;
2311 nskb
->truesize
+= nskb
->data_len
;
2312 } while ((offset
+= len
) < skb
->len
);
2317 while ((skb
= segs
)) {
2321 return ERR_PTR(err
);
2324 EXPORT_SYMBOL_GPL(skb_segment
);
2326 void __init
skb_init(void)
2328 skbuff_head_cache
= kmem_cache_create("skbuff_head_cache",
2329 sizeof(struct sk_buff
),
2331 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
,
2333 skbuff_fclone_cache
= kmem_cache_create("skbuff_fclone_cache",
2334 (2*sizeof(struct sk_buff
)) +
2337 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
,
2342 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2343 * @skb: Socket buffer containing the buffers to be mapped
2344 * @sg: The scatter-gather list to map into
2345 * @offset: The offset into the buffer's contents to start mapping
2346 * @len: Length of buffer space to be mapped
2348 * Fill the specified scatter-gather list with mappings/pointers into a
2349 * region of the buffer space attached to a socket buffer.
2352 __skb_to_sgvec(struct sk_buff
*skb
, struct scatterlist
*sg
, int offset
, int len
)
2354 int start
= skb_headlen(skb
);
2355 int i
, copy
= start
- offset
;
2361 sg_set_buf(sg
, skb
->data
+ offset
, copy
);
2363 if ((len
-= copy
) == 0)
2368 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
2371 WARN_ON(start
> offset
+ len
);
2373 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
2374 if ((copy
= end
- offset
) > 0) {
2375 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
2379 sg_set_page(&sg
[elt
], frag
->page
, copy
,
2380 frag
->page_offset
+offset
-start
);
2389 if (skb_shinfo(skb
)->frag_list
) {
2390 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
2392 for (; list
; list
= list
->next
) {
2395 WARN_ON(start
> offset
+ len
);
2397 end
= start
+ list
->len
;
2398 if ((copy
= end
- offset
) > 0) {
2401 elt
+= __skb_to_sgvec(list
, sg
+elt
, offset
- start
,
2403 if ((len
-= copy
) == 0)
2414 int skb_to_sgvec(struct sk_buff
*skb
, struct scatterlist
*sg
, int offset
, int len
)
2416 int nsg
= __skb_to_sgvec(skb
, sg
, offset
, len
);
2418 sg_mark_end(&sg
[nsg
- 1]);
2424 * skb_cow_data - Check that a socket buffer's data buffers are writable
2425 * @skb: The socket buffer to check.
2426 * @tailbits: Amount of trailing space to be added
2427 * @trailer: Returned pointer to the skb where the @tailbits space begins
2429 * Make sure that the data buffers attached to a socket buffer are
2430 * writable. If they are not, private copies are made of the data buffers
2431 * and the socket buffer is set to use these instead.
2433 * If @tailbits is given, make sure that there is space to write @tailbits
2434 * bytes of data beyond current end of socket buffer. @trailer will be
2435 * set to point to the skb in which this space begins.
2437 * The number of scatterlist elements required to completely map the
2438 * COW'd and extended socket buffer will be returned.
2440 int skb_cow_data(struct sk_buff
*skb
, int tailbits
, struct sk_buff
**trailer
)
2444 struct sk_buff
*skb1
, **skb_p
;
2446 /* If skb is cloned or its head is paged, reallocate
2447 * head pulling out all the pages (pages are considered not writable
2448 * at the moment even if they are anonymous).
2450 if ((skb_cloned(skb
) || skb_shinfo(skb
)->nr_frags
) &&
2451 __pskb_pull_tail(skb
, skb_pagelen(skb
)-skb_headlen(skb
)) == NULL
)
2454 /* Easy case. Most of packets will go this way. */
2455 if (!skb_shinfo(skb
)->frag_list
) {
2456 /* A little of trouble, not enough of space for trailer.
2457 * This should not happen, when stack is tuned to generate
2458 * good frames. OK, on miss we reallocate and reserve even more
2459 * space, 128 bytes is fair. */
2461 if (skb_tailroom(skb
) < tailbits
&&
2462 pskb_expand_head(skb
, 0, tailbits
-skb_tailroom(skb
)+128, GFP_ATOMIC
))
2470 /* Misery. We are in troubles, going to mincer fragments... */
2473 skb_p
= &skb_shinfo(skb
)->frag_list
;
2476 while ((skb1
= *skb_p
) != NULL
) {
2479 /* The fragment is partially pulled by someone,
2480 * this can happen on input. Copy it and everything
2483 if (skb_shared(skb1
))
2486 /* If the skb is the last, worry about trailer. */
2488 if (skb1
->next
== NULL
&& tailbits
) {
2489 if (skb_shinfo(skb1
)->nr_frags
||
2490 skb_shinfo(skb1
)->frag_list
||
2491 skb_tailroom(skb1
) < tailbits
)
2492 ntail
= tailbits
+ 128;
2498 skb_shinfo(skb1
)->nr_frags
||
2499 skb_shinfo(skb1
)->frag_list
) {
2500 struct sk_buff
*skb2
;
2502 /* Fuck, we are miserable poor guys... */
2504 skb2
= skb_copy(skb1
, GFP_ATOMIC
);
2506 skb2
= skb_copy_expand(skb1
,
2510 if (unlikely(skb2
== NULL
))
2514 skb_set_owner_w(skb2
, skb1
->sk
);
2516 /* Looking around. Are we still alive?
2517 * OK, link new skb, drop old one */
2519 skb2
->next
= skb1
->next
;
2526 skb_p
= &skb1
->next
;
2533 * skb_partial_csum_set - set up and verify partial csum values for packet
2534 * @skb: the skb to set
2535 * @start: the number of bytes after skb->data to start checksumming.
2536 * @off: the offset from start to place the checksum.
2538 * For untrusted partially-checksummed packets, we need to make sure the values
2539 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
2541 * This function checks and sets those values and skb->ip_summed: if this
2542 * returns false you should drop the packet.
2544 bool skb_partial_csum_set(struct sk_buff
*skb
, u16 start
, u16 off
)
2546 if (unlikely(start
> skb
->len
- 2) ||
2547 unlikely((int)start
+ off
> skb
->len
- 2)) {
2548 if (net_ratelimit())
2550 "bad partial csum: csum=%u/%u len=%u\n",
2551 start
, off
, skb
->len
);
2554 skb
->ip_summed
= CHECKSUM_PARTIAL
;
2555 skb
->csum_start
= skb_headroom(skb
) + start
;
2556 skb
->csum_offset
= off
;
2560 void __skb_warn_lro_forwarding(const struct sk_buff
*skb
)
2562 if (net_ratelimit())
2563 pr_warning("%s: received packets cannot be forwarded"
2564 " while LRO is enabled\n", skb
->dev
->name
);
2567 EXPORT_SYMBOL(___pskb_trim
);
2568 EXPORT_SYMBOL(__kfree_skb
);
2569 EXPORT_SYMBOL(kfree_skb
);
2570 EXPORT_SYMBOL(__pskb_pull_tail
);
2571 EXPORT_SYMBOL(__alloc_skb
);
2572 EXPORT_SYMBOL(__netdev_alloc_skb
);
2573 EXPORT_SYMBOL(pskb_copy
);
2574 EXPORT_SYMBOL(pskb_expand_head
);
2575 EXPORT_SYMBOL(skb_checksum
);
2576 EXPORT_SYMBOL(skb_clone
);
2577 EXPORT_SYMBOL(skb_copy
);
2578 EXPORT_SYMBOL(skb_copy_and_csum_bits
);
2579 EXPORT_SYMBOL(skb_copy_and_csum_dev
);
2580 EXPORT_SYMBOL(skb_copy_bits
);
2581 EXPORT_SYMBOL(skb_copy_expand
);
2582 EXPORT_SYMBOL(skb_over_panic
);
2583 EXPORT_SYMBOL(skb_pad
);
2584 EXPORT_SYMBOL(skb_realloc_headroom
);
2585 EXPORT_SYMBOL(skb_under_panic
);
2586 EXPORT_SYMBOL(skb_dequeue
);
2587 EXPORT_SYMBOL(skb_dequeue_tail
);
2588 EXPORT_SYMBOL(skb_insert
);
2589 EXPORT_SYMBOL(skb_queue_purge
);
2590 EXPORT_SYMBOL(skb_queue_head
);
2591 EXPORT_SYMBOL(skb_queue_tail
);
2592 EXPORT_SYMBOL(skb_unlink
);
2593 EXPORT_SYMBOL(skb_append
);
2594 EXPORT_SYMBOL(skb_split
);
2595 EXPORT_SYMBOL(skb_prepare_seq_read
);
2596 EXPORT_SYMBOL(skb_seq_read
);
2597 EXPORT_SYMBOL(skb_abort_seq_read
);
2598 EXPORT_SYMBOL(skb_find_text
);
2599 EXPORT_SYMBOL(skb_append_datato_frags
);
2600 EXPORT_SYMBOL(__skb_warn_lro_forwarding
);
2602 EXPORT_SYMBOL_GPL(skb_to_sgvec
);
2603 EXPORT_SYMBOL_GPL(skb_cow_data
);
2604 EXPORT_SYMBOL_GPL(skb_partial_csum_set
);