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/config.h>
42 #include <linux/module.h>
43 #include <linux/types.h>
44 #include <linux/kernel.h>
45 #include <linux/sched.h>
47 #include <linux/interrupt.h>
49 #include <linux/inet.h>
50 #include <linux/slab.h>
51 #include <linux/netdevice.h>
52 #ifdef CONFIG_NET_CLS_ACT
53 #include <net/pkt_sched.h>
55 #include <linux/string.h>
56 #include <linux/skbuff.h>
57 #include <linux/cache.h>
58 #include <linux/rtnetlink.h>
59 #include <linux/init.h>
60 #include <linux/highmem.h>
62 #include <net/protocol.h>
65 #include <net/checksum.h>
68 #include <asm/uaccess.h>
69 #include <asm/system.h>
71 static kmem_cache_t
*skbuff_head_cache __read_mostly
;
72 static kmem_cache_t
*skbuff_fclone_cache __read_mostly
;
74 struct timeval __read_mostly skb_tv_base
;
77 * Keep out-of-line to prevent kernel bloat.
78 * __builtin_return_address is not used because it is not always
83 * skb_over_panic - private function
88 * Out of line support code for skb_put(). Not user callable.
90 void skb_over_panic(struct sk_buff
*skb
, int sz
, void *here
)
92 printk(KERN_EMERG
"skb_over_panic: text:%p len:%d put:%d head:%p "
93 "data:%p tail:%p end:%p dev:%s\n",
94 here
, skb
->len
, sz
, skb
->head
, skb
->data
, skb
->tail
, skb
->end
,
95 skb
->dev
? skb
->dev
->name
: "<NULL>");
100 * skb_under_panic - private function
105 * Out of line support code for skb_push(). Not user callable.
108 void skb_under_panic(struct sk_buff
*skb
, int sz
, void *here
)
110 printk(KERN_EMERG
"skb_under_panic: text:%p len:%d put:%d head:%p "
111 "data:%p tail:%p end:%p dev:%s\n",
112 here
, skb
->len
, sz
, skb
->head
, skb
->data
, skb
->tail
, skb
->end
,
113 skb
->dev
? skb
->dev
->name
: "<NULL>");
117 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
118 * 'private' fields and also do memory statistics to find all the
124 * __alloc_skb - allocate a network buffer
125 * @size: size to allocate
126 * @gfp_mask: allocation mask
128 * Allocate a new &sk_buff. The returned buffer has no headroom and a
129 * tail room of size bytes. The object has a reference count of one.
130 * The return is the buffer. On a failure the return is %NULL.
132 * Buffers may only be allocated from interrupts using a @gfp_mask of
135 struct sk_buff
*__alloc_skb(unsigned int size
, unsigned int __nocast gfp_mask
,
143 skb
= kmem_cache_alloc(skbuff_fclone_cache
,
144 gfp_mask
& ~__GFP_DMA
);
146 skb
= kmem_cache_alloc(skbuff_head_cache
,
147 gfp_mask
& ~__GFP_DMA
);
152 /* Get the DATA. Size must match skb_add_mtu(). */
153 size
= SKB_DATA_ALIGN(size
);
154 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
158 memset(skb
, 0, offsetof(struct sk_buff
, truesize
));
159 skb
->truesize
= size
+ sizeof(struct sk_buff
);
160 atomic_set(&skb
->users
, 1);
164 skb
->end
= data
+ size
;
166 struct sk_buff
*child
= skb
+ 1;
167 atomic_t
*fclone_ref
= (atomic_t
*) (child
+ 1);
169 skb
->fclone
= SKB_FCLONE_ORIG
;
170 atomic_set(fclone_ref
, 1);
172 child
->fclone
= SKB_FCLONE_UNAVAILABLE
;
174 atomic_set(&(skb_shinfo(skb
)->dataref
), 1);
175 skb_shinfo(skb
)->nr_frags
= 0;
176 skb_shinfo(skb
)->tso_size
= 0;
177 skb_shinfo(skb
)->tso_segs
= 0;
178 skb_shinfo(skb
)->frag_list
= NULL
;
182 kmem_cache_free(skbuff_head_cache
, skb
);
188 * alloc_skb_from_cache - allocate a network buffer
189 * @cp: kmem_cache from which to allocate the data area
190 * (object size must be big enough for @size bytes + skb overheads)
191 * @size: size to allocate
192 * @gfp_mask: allocation mask
194 * Allocate a new &sk_buff. The returned buffer has no headroom and
195 * tail room of size bytes. The object has a reference count of one.
196 * The return is the buffer. On a failure the return is %NULL.
198 * Buffers may only be allocated from interrupts using a @gfp_mask of
201 struct sk_buff
*alloc_skb_from_cache(kmem_cache_t
*cp
,
203 unsigned int __nocast gfp_mask
)
209 skb
= kmem_cache_alloc(skbuff_head_cache
,
210 gfp_mask
& ~__GFP_DMA
);
215 size
= SKB_DATA_ALIGN(size
);
216 data
= kmem_cache_alloc(cp
, gfp_mask
);
220 memset(skb
, 0, offsetof(struct sk_buff
, truesize
));
221 skb
->truesize
= size
+ sizeof(struct sk_buff
);
222 atomic_set(&skb
->users
, 1);
226 skb
->end
= data
+ size
;
228 atomic_set(&(skb_shinfo(skb
)->dataref
), 1);
229 skb_shinfo(skb
)->nr_frags
= 0;
230 skb_shinfo(skb
)->tso_size
= 0;
231 skb_shinfo(skb
)->tso_segs
= 0;
232 skb_shinfo(skb
)->frag_list
= NULL
;
236 kmem_cache_free(skbuff_head_cache
, skb
);
242 static void skb_drop_fraglist(struct sk_buff
*skb
)
244 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
246 skb_shinfo(skb
)->frag_list
= NULL
;
249 struct sk_buff
*this = list
;
255 static void skb_clone_fraglist(struct sk_buff
*skb
)
257 struct sk_buff
*list
;
259 for (list
= skb_shinfo(skb
)->frag_list
; list
; list
= list
->next
)
263 void skb_release_data(struct sk_buff
*skb
)
266 !atomic_sub_return(skb
->nohdr
? (1 << SKB_DATAREF_SHIFT
) + 1 : 1,
267 &skb_shinfo(skb
)->dataref
)) {
268 if (skb_shinfo(skb
)->nr_frags
) {
270 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
271 put_page(skb_shinfo(skb
)->frags
[i
].page
);
274 if (skb_shinfo(skb
)->frag_list
)
275 skb_drop_fraglist(skb
);
282 * Free an skbuff by memory without cleaning the state.
284 void kfree_skbmem(struct sk_buff
*skb
)
286 struct sk_buff
*other
;
287 atomic_t
*fclone_ref
;
289 skb_release_data(skb
);
290 switch (skb
->fclone
) {
291 case SKB_FCLONE_UNAVAILABLE
:
292 kmem_cache_free(skbuff_head_cache
, skb
);
295 case SKB_FCLONE_ORIG
:
296 fclone_ref
= (atomic_t
*) (skb
+ 2);
297 if (atomic_dec_and_test(fclone_ref
))
298 kmem_cache_free(skbuff_fclone_cache
, skb
);
301 case SKB_FCLONE_CLONE
:
302 fclone_ref
= (atomic_t
*) (skb
+ 1);
305 /* The clone portion is available for
306 * fast-cloning again.
308 skb
->fclone
= SKB_FCLONE_UNAVAILABLE
;
310 if (atomic_dec_and_test(fclone_ref
))
311 kmem_cache_free(skbuff_fclone_cache
, other
);
317 * __kfree_skb - private function
320 * Free an sk_buff. Release anything attached to the buffer.
321 * Clean the state. This is an internal helper function. Users should
322 * always call kfree_skb
325 void __kfree_skb(struct sk_buff
*skb
)
327 dst_release(skb
->dst
);
329 secpath_put(skb
->sp
);
331 if (skb
->destructor
) {
333 skb
->destructor(skb
);
335 #ifdef CONFIG_NETFILTER
336 nf_conntrack_put(skb
->nfct
);
337 #ifdef CONFIG_BRIDGE_NETFILTER
338 nf_bridge_put(skb
->nf_bridge
);
341 /* XXX: IS this still necessary? - JHS */
342 #ifdef CONFIG_NET_SCHED
344 #ifdef CONFIG_NET_CLS_ACT
353 * skb_clone - duplicate an sk_buff
354 * @skb: buffer to clone
355 * @gfp_mask: allocation priority
357 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
358 * copies share the same packet data but not structure. The new
359 * buffer has a reference count of 1. If the allocation fails the
360 * function returns %NULL otherwise the new buffer is returned.
362 * If this function is called from an interrupt gfp_mask() must be
366 struct sk_buff
*skb_clone(struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
371 if (skb
->fclone
== SKB_FCLONE_ORIG
&&
372 n
->fclone
== SKB_FCLONE_UNAVAILABLE
) {
373 atomic_t
*fclone_ref
= (atomic_t
*) (n
+ 1);
374 n
->fclone
= SKB_FCLONE_CLONE
;
375 atomic_inc(fclone_ref
);
377 n
= kmem_cache_alloc(skbuff_head_cache
, gfp_mask
);
380 n
->fclone
= SKB_FCLONE_UNAVAILABLE
;
383 #define C(x) n->x = skb->x
385 n
->next
= n
->prev
= NULL
;
396 secpath_get(skb
->sp
);
398 memcpy(n
->cb
, skb
->cb
, sizeof(skb
->cb
));
409 n
->destructor
= NULL
;
410 #ifdef CONFIG_NETFILTER
413 nf_conntrack_get(skb
->nfct
);
415 #ifdef CONFIG_BRIDGE_NETFILTER
417 nf_bridge_get(skb
->nf_bridge
);
419 #endif /*CONFIG_NETFILTER*/
420 #ifdef CONFIG_NET_SCHED
422 #ifdef CONFIG_NET_CLS_ACT
423 n
->tc_verd
= SET_TC_VERD(skb
->tc_verd
,0);
424 n
->tc_verd
= CLR_TC_OK2MUNGE(n
->tc_verd
);
425 n
->tc_verd
= CLR_TC_MUNGED(n
->tc_verd
);
431 atomic_set(&n
->users
, 1);
437 atomic_inc(&(skb_shinfo(skb
)->dataref
));
443 static void copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
446 * Shift between the two data areas in bytes
448 unsigned long offset
= new->data
- old
->data
;
452 new->priority
= old
->priority
;
453 new->protocol
= old
->protocol
;
454 new->dst
= dst_clone(old
->dst
);
456 new->sp
= secpath_get(old
->sp
);
458 new->h
.raw
= old
->h
.raw
+ offset
;
459 new->nh
.raw
= old
->nh
.raw
+ offset
;
460 new->mac
.raw
= old
->mac
.raw
+ offset
;
461 memcpy(new->cb
, old
->cb
, sizeof(old
->cb
));
462 new->local_df
= old
->local_df
;
463 new->fclone
= SKB_FCLONE_UNAVAILABLE
;
464 new->pkt_type
= old
->pkt_type
;
465 new->tstamp
= old
->tstamp
;
466 new->destructor
= NULL
;
467 #ifdef CONFIG_NETFILTER
468 new->nfmark
= old
->nfmark
;
469 new->nfct
= old
->nfct
;
470 nf_conntrack_get(old
->nfct
);
471 new->nfctinfo
= old
->nfctinfo
;
472 #ifdef CONFIG_BRIDGE_NETFILTER
473 new->nf_bridge
= old
->nf_bridge
;
474 nf_bridge_get(old
->nf_bridge
);
477 #ifdef CONFIG_NET_SCHED
478 #ifdef CONFIG_NET_CLS_ACT
479 new->tc_verd
= old
->tc_verd
;
481 new->tc_index
= old
->tc_index
;
483 atomic_set(&new->users
, 1);
484 skb_shinfo(new)->tso_size
= skb_shinfo(old
)->tso_size
;
485 skb_shinfo(new)->tso_segs
= skb_shinfo(old
)->tso_segs
;
489 * skb_copy - create private copy of an sk_buff
490 * @skb: buffer to copy
491 * @gfp_mask: allocation priority
493 * Make a copy of both an &sk_buff and its data. This is used when the
494 * caller wishes to modify the data and needs a private copy of the
495 * data to alter. Returns %NULL on failure or the pointer to the buffer
496 * on success. The returned buffer has a reference count of 1.
498 * As by-product this function converts non-linear &sk_buff to linear
499 * one, so that &sk_buff becomes completely private and caller is allowed
500 * to modify all the data of returned buffer. This means that this
501 * function is not recommended for use in circumstances when only
502 * header is going to be modified. Use pskb_copy() instead.
505 struct sk_buff
*skb_copy(const struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
507 int headerlen
= skb
->data
- skb
->head
;
509 * Allocate the copy buffer
511 struct sk_buff
*n
= alloc_skb(skb
->end
- skb
->head
+ skb
->data_len
,
516 /* Set the data pointer */
517 skb_reserve(n
, headerlen
);
518 /* Set the tail pointer and length */
519 skb_put(n
, skb
->len
);
521 n
->ip_summed
= skb
->ip_summed
;
523 if (skb_copy_bits(skb
, -headerlen
, n
->head
, headerlen
+ skb
->len
))
526 copy_skb_header(n
, skb
);
532 * pskb_copy - create copy of an sk_buff with private head.
533 * @skb: buffer to copy
534 * @gfp_mask: allocation priority
536 * Make a copy of both an &sk_buff and part of its data, located
537 * in header. Fragmented data remain shared. This is used when
538 * the caller wishes to modify only header of &sk_buff and needs
539 * private copy of the header to alter. Returns %NULL on failure
540 * or the pointer to the buffer on success.
541 * The returned buffer has a reference count of 1.
544 struct sk_buff
*pskb_copy(struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
547 * Allocate the copy buffer
549 struct sk_buff
*n
= alloc_skb(skb
->end
- skb
->head
, gfp_mask
);
554 /* Set the data pointer */
555 skb_reserve(n
, skb
->data
- skb
->head
);
556 /* Set the tail pointer and length */
557 skb_put(n
, skb_headlen(skb
));
559 memcpy(n
->data
, skb
->data
, n
->len
);
561 n
->ip_summed
= skb
->ip_summed
;
563 n
->data_len
= skb
->data_len
;
566 if (skb_shinfo(skb
)->nr_frags
) {
569 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
570 skb_shinfo(n
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
571 get_page(skb_shinfo(n
)->frags
[i
].page
);
573 skb_shinfo(n
)->nr_frags
= i
;
576 if (skb_shinfo(skb
)->frag_list
) {
577 skb_shinfo(n
)->frag_list
= skb_shinfo(skb
)->frag_list
;
578 skb_clone_fraglist(n
);
581 copy_skb_header(n
, skb
);
587 * pskb_expand_head - reallocate header of &sk_buff
588 * @skb: buffer to reallocate
589 * @nhead: room to add at head
590 * @ntail: room to add at tail
591 * @gfp_mask: allocation priority
593 * Expands (or creates identical copy, if &nhead and &ntail are zero)
594 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
595 * reference count of 1. Returns zero in the case of success or error,
596 * if expansion failed. In the last case, &sk_buff is not changed.
598 * All the pointers pointing into skb header may change and must be
599 * reloaded after call to this function.
602 int pskb_expand_head(struct sk_buff
*skb
, int nhead
, int ntail
,
603 unsigned int __nocast gfp_mask
)
607 int size
= nhead
+ (skb
->end
- skb
->head
) + ntail
;
613 size
= SKB_DATA_ALIGN(size
);
615 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
619 /* Copy only real data... and, alas, header. This should be
620 * optimized for the cases when header is void. */
621 memcpy(data
+ nhead
, skb
->head
, skb
->tail
- skb
->head
);
622 memcpy(data
+ size
, skb
->end
, sizeof(struct skb_shared_info
));
624 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
625 get_page(skb_shinfo(skb
)->frags
[i
].page
);
627 if (skb_shinfo(skb
)->frag_list
)
628 skb_clone_fraglist(skb
);
630 skb_release_data(skb
);
632 off
= (data
+ nhead
) - skb
->head
;
635 skb
->end
= data
+ size
;
643 atomic_set(&skb_shinfo(skb
)->dataref
, 1);
650 /* Make private copy of skb with writable head and some headroom */
652 struct sk_buff
*skb_realloc_headroom(struct sk_buff
*skb
, unsigned int headroom
)
654 struct sk_buff
*skb2
;
655 int delta
= headroom
- skb_headroom(skb
);
658 skb2
= pskb_copy(skb
, GFP_ATOMIC
);
660 skb2
= skb_clone(skb
, GFP_ATOMIC
);
661 if (skb2
&& pskb_expand_head(skb2
, SKB_DATA_ALIGN(delta
), 0,
672 * skb_copy_expand - copy and expand sk_buff
673 * @skb: buffer to copy
674 * @newheadroom: new free bytes at head
675 * @newtailroom: new free bytes at tail
676 * @gfp_mask: allocation priority
678 * Make a copy of both an &sk_buff and its data and while doing so
679 * allocate additional space.
681 * This is used when the caller wishes to modify the data and needs a
682 * private copy of the data to alter as well as more space for new fields.
683 * Returns %NULL on failure or the pointer to the buffer
684 * on success. The returned buffer has a reference count of 1.
686 * You must pass %GFP_ATOMIC as the allocation priority if this function
687 * is called from an interrupt.
689 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used
690 * only by netfilter in the cases when checksum is recalculated? --ANK
692 struct sk_buff
*skb_copy_expand(const struct sk_buff
*skb
,
693 int newheadroom
, int newtailroom
,
694 unsigned int __nocast gfp_mask
)
697 * Allocate the copy buffer
699 struct sk_buff
*n
= alloc_skb(newheadroom
+ skb
->len
+ newtailroom
,
701 int head_copy_len
, head_copy_off
;
706 skb_reserve(n
, newheadroom
);
708 /* Set the tail pointer and length */
709 skb_put(n
, skb
->len
);
711 head_copy_len
= skb_headroom(skb
);
713 if (newheadroom
<= head_copy_len
)
714 head_copy_len
= newheadroom
;
716 head_copy_off
= newheadroom
- head_copy_len
;
718 /* Copy the linear header and data. */
719 if (skb_copy_bits(skb
, -head_copy_len
, n
->head
+ head_copy_off
,
720 skb
->len
+ head_copy_len
))
723 copy_skb_header(n
, skb
);
729 * skb_pad - zero pad the tail of an skb
730 * @skb: buffer to pad
733 * Ensure that a buffer is followed by a padding area that is zero
734 * filled. Used by network drivers which may DMA or transfer data
735 * beyond the buffer end onto the wire.
737 * May return NULL in out of memory cases.
740 struct sk_buff
*skb_pad(struct sk_buff
*skb
, int pad
)
742 struct sk_buff
*nskb
;
744 /* If the skbuff is non linear tailroom is always zero.. */
745 if (skb_tailroom(skb
) >= pad
) {
746 memset(skb
->data
+skb
->len
, 0, pad
);
750 nskb
= skb_copy_expand(skb
, skb_headroom(skb
), skb_tailroom(skb
) + pad
, GFP_ATOMIC
);
753 memset(nskb
->data
+nskb
->len
, 0, pad
);
757 /* Trims skb to length len. It can change skb pointers, if "realloc" is 1.
758 * If realloc==0 and trimming is impossible without change of data,
762 int ___pskb_trim(struct sk_buff
*skb
, unsigned int len
, int realloc
)
764 int offset
= skb_headlen(skb
);
765 int nfrags
= skb_shinfo(skb
)->nr_frags
;
768 for (i
= 0; i
< nfrags
; i
++) {
769 int end
= offset
+ skb_shinfo(skb
)->frags
[i
].size
;
771 if (skb_cloned(skb
)) {
774 if (pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))
778 put_page(skb_shinfo(skb
)->frags
[i
].page
);
779 skb_shinfo(skb
)->nr_frags
--;
781 skb_shinfo(skb
)->frags
[i
].size
= len
- offset
;
788 skb
->data_len
-= skb
->len
- len
;
791 if (len
<= skb_headlen(skb
)) {
794 skb
->tail
= skb
->data
+ len
;
795 if (skb_shinfo(skb
)->frag_list
&& !skb_cloned(skb
))
796 skb_drop_fraglist(skb
);
798 skb
->data_len
-= skb
->len
- len
;
807 * __pskb_pull_tail - advance tail of skb header
808 * @skb: buffer to reallocate
809 * @delta: number of bytes to advance tail
811 * The function makes a sense only on a fragmented &sk_buff,
812 * it expands header moving its tail forward and copying necessary
813 * data from fragmented part.
815 * &sk_buff MUST have reference count of 1.
817 * Returns %NULL (and &sk_buff does not change) if pull failed
818 * or value of new tail of skb in the case of success.
820 * All the pointers pointing into skb header may change and must be
821 * reloaded after call to this function.
824 /* Moves tail of skb head forward, copying data from fragmented part,
825 * when it is necessary.
826 * 1. It may fail due to malloc failure.
827 * 2. It may change skb pointers.
829 * It is pretty complicated. Luckily, it is called only in exceptional cases.
831 unsigned char *__pskb_pull_tail(struct sk_buff
*skb
, int delta
)
833 /* If skb has not enough free space at tail, get new one
834 * plus 128 bytes for future expansions. If we have enough
835 * room at tail, reallocate without expansion only if skb is cloned.
837 int i
, k
, eat
= (skb
->tail
+ delta
) - skb
->end
;
839 if (eat
> 0 || skb_cloned(skb
)) {
840 if (pskb_expand_head(skb
, 0, eat
> 0 ? eat
+ 128 : 0,
845 if (skb_copy_bits(skb
, skb_headlen(skb
), skb
->tail
, delta
))
848 /* Optimization: no fragments, no reasons to preestimate
849 * size of pulled pages. Superb.
851 if (!skb_shinfo(skb
)->frag_list
)
854 /* Estimate size of pulled pages. */
856 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
857 if (skb_shinfo(skb
)->frags
[i
].size
>= eat
)
859 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
862 /* If we need update frag list, we are in troubles.
863 * Certainly, it possible to add an offset to skb data,
864 * but taking into account that pulling is expected to
865 * be very rare operation, it is worth to fight against
866 * further bloating skb head and crucify ourselves here instead.
867 * Pure masohism, indeed. 8)8)
870 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
871 struct sk_buff
*clone
= NULL
;
872 struct sk_buff
*insp
= NULL
;
878 if (list
->len
<= eat
) {
879 /* Eaten as whole. */
884 /* Eaten partially. */
886 if (skb_shared(list
)) {
887 /* Sucks! We need to fork list. :-( */
888 clone
= skb_clone(list
, GFP_ATOMIC
);
894 /* This may be pulled without
898 if (!pskb_pull(list
, eat
)) {
907 /* Free pulled out fragments. */
908 while ((list
= skb_shinfo(skb
)->frag_list
) != insp
) {
909 skb_shinfo(skb
)->frag_list
= list
->next
;
912 /* And insert new clone at head. */
915 skb_shinfo(skb
)->frag_list
= clone
;
918 /* Success! Now we may commit changes to skb data. */
923 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
924 if (skb_shinfo(skb
)->frags
[i
].size
<= eat
) {
925 put_page(skb_shinfo(skb
)->frags
[i
].page
);
926 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
928 skb_shinfo(skb
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
930 skb_shinfo(skb
)->frags
[k
].page_offset
+= eat
;
931 skb_shinfo(skb
)->frags
[k
].size
-= eat
;
937 skb_shinfo(skb
)->nr_frags
= k
;
940 skb
->data_len
-= delta
;
945 /* Copy some data bits from skb to kernel buffer. */
947 int skb_copy_bits(const struct sk_buff
*skb
, int offset
, void *to
, int len
)
950 int start
= skb_headlen(skb
);
952 if (offset
> (int)skb
->len
- len
)
956 if ((copy
= start
- offset
) > 0) {
959 memcpy(to
, skb
->data
+ offset
, copy
);
960 if ((len
-= copy
) == 0)
966 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
969 BUG_TRAP(start
<= offset
+ len
);
971 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
972 if ((copy
= end
- offset
) > 0) {
978 vaddr
= kmap_skb_frag(&skb_shinfo(skb
)->frags
[i
]);
980 vaddr
+ skb_shinfo(skb
)->frags
[i
].page_offset
+
981 offset
- start
, copy
);
982 kunmap_skb_frag(vaddr
);
984 if ((len
-= copy
) == 0)
992 if (skb_shinfo(skb
)->frag_list
) {
993 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
995 for (; list
; list
= list
->next
) {
998 BUG_TRAP(start
<= offset
+ len
);
1000 end
= start
+ list
->len
;
1001 if ((copy
= end
- offset
) > 0) {
1004 if (skb_copy_bits(list
, offset
- start
,
1007 if ((len
-= copy
) == 0)
1023 * skb_store_bits - store bits from kernel buffer to skb
1024 * @skb: destination buffer
1025 * @offset: offset in destination
1026 * @from: source buffer
1027 * @len: number of bytes to copy
1029 * Copy the specified number of bytes from the source buffer to the
1030 * destination skb. This function handles all the messy bits of
1031 * traversing fragment lists and such.
1034 int skb_store_bits(const struct sk_buff
*skb
, int offset
, void *from
, int len
)
1037 int start
= skb_headlen(skb
);
1039 if (offset
> (int)skb
->len
- len
)
1042 if ((copy
= start
- offset
) > 0) {
1045 memcpy(skb
->data
+ offset
, from
, copy
);
1046 if ((len
-= copy
) == 0)
1052 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1053 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1056 BUG_TRAP(start
<= offset
+ len
);
1058 end
= start
+ frag
->size
;
1059 if ((copy
= end
- offset
) > 0) {
1065 vaddr
= kmap_skb_frag(frag
);
1066 memcpy(vaddr
+ frag
->page_offset
+ offset
- start
,
1068 kunmap_skb_frag(vaddr
);
1070 if ((len
-= copy
) == 0)
1078 if (skb_shinfo(skb
)->frag_list
) {
1079 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1081 for (; list
; list
= list
->next
) {
1084 BUG_TRAP(start
<= offset
+ len
);
1086 end
= start
+ list
->len
;
1087 if ((copy
= end
- offset
) > 0) {
1090 if (skb_store_bits(list
, offset
- start
,
1093 if ((len
-= copy
) == 0)
1108 EXPORT_SYMBOL(skb_store_bits
);
1110 /* Checksum skb data. */
1112 unsigned int skb_checksum(const struct sk_buff
*skb
, int offset
,
1113 int len
, unsigned int csum
)
1115 int start
= skb_headlen(skb
);
1116 int i
, copy
= start
- offset
;
1119 /* Checksum header. */
1123 csum
= csum_partial(skb
->data
+ offset
, copy
, csum
);
1124 if ((len
-= copy
) == 0)
1130 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1133 BUG_TRAP(start
<= offset
+ len
);
1135 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1136 if ((copy
= end
- offset
) > 0) {
1139 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1143 vaddr
= kmap_skb_frag(frag
);
1144 csum2
= csum_partial(vaddr
+ frag
->page_offset
+
1145 offset
- start
, copy
, 0);
1146 kunmap_skb_frag(vaddr
);
1147 csum
= csum_block_add(csum
, csum2
, pos
);
1156 if (skb_shinfo(skb
)->frag_list
) {
1157 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1159 for (; list
; list
= list
->next
) {
1162 BUG_TRAP(start
<= offset
+ len
);
1164 end
= start
+ list
->len
;
1165 if ((copy
= end
- offset
) > 0) {
1169 csum2
= skb_checksum(list
, offset
- start
,
1171 csum
= csum_block_add(csum
, csum2
, pos
);
1172 if ((len
-= copy
) == 0)
1186 /* Both of above in one bottle. */
1188 unsigned int skb_copy_and_csum_bits(const struct sk_buff
*skb
, int offset
,
1189 u8
*to
, int len
, unsigned int csum
)
1191 int start
= skb_headlen(skb
);
1192 int i
, copy
= start
- offset
;
1199 csum
= csum_partial_copy_nocheck(skb
->data
+ offset
, to
,
1201 if ((len
-= copy
) == 0)
1208 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1211 BUG_TRAP(start
<= offset
+ len
);
1213 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1214 if ((copy
= end
- offset
) > 0) {
1217 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1221 vaddr
= kmap_skb_frag(frag
);
1222 csum2
= csum_partial_copy_nocheck(vaddr
+
1226 kunmap_skb_frag(vaddr
);
1227 csum
= csum_block_add(csum
, csum2
, pos
);
1237 if (skb_shinfo(skb
)->frag_list
) {
1238 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1240 for (; list
; list
= list
->next
) {
1244 BUG_TRAP(start
<= offset
+ len
);
1246 end
= start
+ list
->len
;
1247 if ((copy
= end
- offset
) > 0) {
1250 csum2
= skb_copy_and_csum_bits(list
,
1253 csum
= csum_block_add(csum
, csum2
, pos
);
1254 if ((len
-= copy
) == 0)
1268 void skb_copy_and_csum_dev(const struct sk_buff
*skb
, u8
*to
)
1273 if (skb
->ip_summed
== CHECKSUM_HW
)
1274 csstart
= skb
->h
.raw
- skb
->data
;
1276 csstart
= skb_headlen(skb
);
1278 if (csstart
> skb_headlen(skb
))
1281 memcpy(to
, skb
->data
, csstart
);
1284 if (csstart
!= skb
->len
)
1285 csum
= skb_copy_and_csum_bits(skb
, csstart
, to
+ csstart
,
1286 skb
->len
- csstart
, 0);
1288 if (skb
->ip_summed
== CHECKSUM_HW
) {
1289 long csstuff
= csstart
+ skb
->csum
;
1291 *((unsigned short *)(to
+ csstuff
)) = csum_fold(csum
);
1296 * skb_dequeue - remove from the head of the queue
1297 * @list: list to dequeue from
1299 * Remove the head of the list. The list lock is taken so the function
1300 * may be used safely with other locking list functions. The head item is
1301 * returned or %NULL if the list is empty.
1304 struct sk_buff
*skb_dequeue(struct sk_buff_head
*list
)
1306 unsigned long flags
;
1307 struct sk_buff
*result
;
1309 spin_lock_irqsave(&list
->lock
, flags
);
1310 result
= __skb_dequeue(list
);
1311 spin_unlock_irqrestore(&list
->lock
, flags
);
1316 * skb_dequeue_tail - remove from the tail of the queue
1317 * @list: list to dequeue from
1319 * Remove the tail of the list. The list lock is taken so the function
1320 * may be used safely with other locking list functions. The tail item is
1321 * returned or %NULL if the list is empty.
1323 struct sk_buff
*skb_dequeue_tail(struct sk_buff_head
*list
)
1325 unsigned long flags
;
1326 struct sk_buff
*result
;
1328 spin_lock_irqsave(&list
->lock
, flags
);
1329 result
= __skb_dequeue_tail(list
);
1330 spin_unlock_irqrestore(&list
->lock
, flags
);
1335 * skb_queue_purge - empty a list
1336 * @list: list to empty
1338 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1339 * the list and one reference dropped. This function takes the list
1340 * lock and is atomic with respect to other list locking functions.
1342 void skb_queue_purge(struct sk_buff_head
*list
)
1344 struct sk_buff
*skb
;
1345 while ((skb
= skb_dequeue(list
)) != NULL
)
1350 * skb_queue_head - queue a buffer at the list head
1351 * @list: list to use
1352 * @newsk: buffer to queue
1354 * Queue a buffer at the start of the list. This function takes the
1355 * list lock and can be used safely with other locking &sk_buff functions
1358 * A buffer cannot be placed on two lists at the same time.
1360 void skb_queue_head(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1362 unsigned long flags
;
1364 spin_lock_irqsave(&list
->lock
, flags
);
1365 __skb_queue_head(list
, newsk
);
1366 spin_unlock_irqrestore(&list
->lock
, flags
);
1370 * skb_queue_tail - queue a buffer at the list tail
1371 * @list: list to use
1372 * @newsk: buffer to queue
1374 * Queue a buffer at the tail of the list. This function takes the
1375 * list lock and can be used safely with other locking &sk_buff functions
1378 * A buffer cannot be placed on two lists at the same time.
1380 void skb_queue_tail(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1382 unsigned long flags
;
1384 spin_lock_irqsave(&list
->lock
, flags
);
1385 __skb_queue_tail(list
, newsk
);
1386 spin_unlock_irqrestore(&list
->lock
, flags
);
1390 * skb_unlink - remove a buffer from a list
1391 * @skb: buffer to remove
1392 * @list: list to use
1394 * Remove a packet from a list. The list locks are taken and this
1395 * function is atomic with respect to other list locked calls
1397 * You must know what list the SKB is on.
1399 void skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
)
1401 unsigned long flags
;
1403 spin_lock_irqsave(&list
->lock
, flags
);
1404 __skb_unlink(skb
, list
);
1405 spin_unlock_irqrestore(&list
->lock
, flags
);
1409 * skb_append - append a buffer
1410 * @old: buffer to insert after
1411 * @newsk: buffer to insert
1412 * @list: list to use
1414 * Place a packet after a given packet in a list. The list locks are taken
1415 * and this function is atomic with respect to other list locked calls.
1416 * A buffer cannot be placed on two lists at the same time.
1418 void skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1420 unsigned long flags
;
1422 spin_lock_irqsave(&list
->lock
, flags
);
1423 __skb_append(old
, newsk
, list
);
1424 spin_unlock_irqrestore(&list
->lock
, flags
);
1429 * skb_insert - insert a buffer
1430 * @old: buffer to insert before
1431 * @newsk: buffer to insert
1432 * @list: list to use
1434 * Place a packet before a given packet in a list. The list locks are
1435 * taken and this function is atomic with respect to other list locked
1438 * A buffer cannot be placed on two lists at the same time.
1440 void skb_insert(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1442 unsigned long flags
;
1444 spin_lock_irqsave(&list
->lock
, flags
);
1445 __skb_insert(newsk
, old
->prev
, old
, list
);
1446 spin_unlock_irqrestore(&list
->lock
, flags
);
1451 * Tune the memory allocator for a new MTU size.
1453 void skb_add_mtu(int mtu
)
1455 /* Must match allocation in alloc_skb */
1456 mtu
= SKB_DATA_ALIGN(mtu
) + sizeof(struct skb_shared_info
);
1458 kmem_add_cache_size(mtu
);
1462 static inline void skb_split_inside_header(struct sk_buff
*skb
,
1463 struct sk_buff
* skb1
,
1464 const u32 len
, const int pos
)
1468 memcpy(skb_put(skb1
, pos
- len
), skb
->data
+ len
, pos
- len
);
1470 /* And move data appendix as is. */
1471 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
1472 skb_shinfo(skb1
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
1474 skb_shinfo(skb1
)->nr_frags
= skb_shinfo(skb
)->nr_frags
;
1475 skb_shinfo(skb
)->nr_frags
= 0;
1476 skb1
->data_len
= skb
->data_len
;
1477 skb1
->len
+= skb1
->data_len
;
1480 skb
->tail
= skb
->data
+ len
;
1483 static inline void skb_split_no_header(struct sk_buff
*skb
,
1484 struct sk_buff
* skb1
,
1485 const u32 len
, int pos
)
1488 const int nfrags
= skb_shinfo(skb
)->nr_frags
;
1490 skb_shinfo(skb
)->nr_frags
= 0;
1491 skb1
->len
= skb1
->data_len
= skb
->len
- len
;
1493 skb
->data_len
= len
- pos
;
1495 for (i
= 0; i
< nfrags
; i
++) {
1496 int size
= skb_shinfo(skb
)->frags
[i
].size
;
1498 if (pos
+ size
> len
) {
1499 skb_shinfo(skb1
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1503 * We have two variants in this case:
1504 * 1. Move all the frag to the second
1505 * part, if it is possible. F.e.
1506 * this approach is mandatory for TUX,
1507 * where splitting is expensive.
1508 * 2. Split is accurately. We make this.
1510 get_page(skb_shinfo(skb
)->frags
[i
].page
);
1511 skb_shinfo(skb1
)->frags
[0].page_offset
+= len
- pos
;
1512 skb_shinfo(skb1
)->frags
[0].size
-= len
- pos
;
1513 skb_shinfo(skb
)->frags
[i
].size
= len
- pos
;
1514 skb_shinfo(skb
)->nr_frags
++;
1518 skb_shinfo(skb
)->nr_frags
++;
1521 skb_shinfo(skb1
)->nr_frags
= k
;
1525 * skb_split - Split fragmented skb to two parts at length len.
1526 * @skb: the buffer to split
1527 * @skb1: the buffer to receive the second part
1528 * @len: new length for skb
1530 void skb_split(struct sk_buff
*skb
, struct sk_buff
*skb1
, const u32 len
)
1532 int pos
= skb_headlen(skb
);
1534 if (len
< pos
) /* Split line is inside header. */
1535 skb_split_inside_header(skb
, skb1
, len
, pos
);
1536 else /* Second chunk has no header, nothing to copy. */
1537 skb_split_no_header(skb
, skb1
, len
, pos
);
1541 * skb_prepare_seq_read - Prepare a sequential read of skb data
1542 * @skb: the buffer to read
1543 * @from: lower offset of data to be read
1544 * @to: upper offset of data to be read
1545 * @st: state variable
1547 * Initializes the specified state variable. Must be called before
1548 * invoking skb_seq_read() for the first time.
1550 void skb_prepare_seq_read(struct sk_buff
*skb
, unsigned int from
,
1551 unsigned int to
, struct skb_seq_state
*st
)
1553 st
->lower_offset
= from
;
1554 st
->upper_offset
= to
;
1555 st
->root_skb
= st
->cur_skb
= skb
;
1556 st
->frag_idx
= st
->stepped_offset
= 0;
1557 st
->frag_data
= NULL
;
1561 * skb_seq_read - Sequentially read skb data
1562 * @consumed: number of bytes consumed by the caller so far
1563 * @data: destination pointer for data to be returned
1564 * @st: state variable
1566 * Reads a block of skb data at &consumed relative to the
1567 * lower offset specified to skb_prepare_seq_read(). Assigns
1568 * the head of the data block to &data and returns the length
1569 * of the block or 0 if the end of the skb data or the upper
1570 * offset has been reached.
1572 * The caller is not required to consume all of the data
1573 * returned, i.e. &consumed is typically set to the number
1574 * of bytes already consumed and the next call to
1575 * skb_seq_read() will return the remaining part of the block.
1577 * Note: The size of each block of data returned can be arbitary,
1578 * this limitation is the cost for zerocopy seqeuental
1579 * reads of potentially non linear data.
1581 * Note: Fragment lists within fragments are not implemented
1582 * at the moment, state->root_skb could be replaced with
1583 * a stack for this purpose.
1585 unsigned int skb_seq_read(unsigned int consumed
, const u8
**data
,
1586 struct skb_seq_state
*st
)
1588 unsigned int block_limit
, abs_offset
= consumed
+ st
->lower_offset
;
1591 if (unlikely(abs_offset
>= st
->upper_offset
))
1595 block_limit
= skb_headlen(st
->cur_skb
);
1597 if (abs_offset
< block_limit
) {
1598 *data
= st
->cur_skb
->data
+ abs_offset
;
1599 return block_limit
- abs_offset
;
1602 if (st
->frag_idx
== 0 && !st
->frag_data
)
1603 st
->stepped_offset
+= skb_headlen(st
->cur_skb
);
1605 while (st
->frag_idx
< skb_shinfo(st
->cur_skb
)->nr_frags
) {
1606 frag
= &skb_shinfo(st
->cur_skb
)->frags
[st
->frag_idx
];
1607 block_limit
= frag
->size
+ st
->stepped_offset
;
1609 if (abs_offset
< block_limit
) {
1611 st
->frag_data
= kmap_skb_frag(frag
);
1613 *data
= (u8
*) st
->frag_data
+ frag
->page_offset
+
1614 (abs_offset
- st
->stepped_offset
);
1616 return block_limit
- abs_offset
;
1619 if (st
->frag_data
) {
1620 kunmap_skb_frag(st
->frag_data
);
1621 st
->frag_data
= NULL
;
1625 st
->stepped_offset
+= frag
->size
;
1628 if (st
->cur_skb
->next
) {
1629 st
->cur_skb
= st
->cur_skb
->next
;
1632 } else if (st
->root_skb
== st
->cur_skb
&&
1633 skb_shinfo(st
->root_skb
)->frag_list
) {
1634 st
->cur_skb
= skb_shinfo(st
->root_skb
)->frag_list
;
1642 * skb_abort_seq_read - Abort a sequential read of skb data
1643 * @st: state variable
1645 * Must be called if skb_seq_read() was not called until it
1648 void skb_abort_seq_read(struct skb_seq_state
*st
)
1651 kunmap_skb_frag(st
->frag_data
);
1654 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
1656 static unsigned int skb_ts_get_next_block(unsigned int offset
, const u8
**text
,
1657 struct ts_config
*conf
,
1658 struct ts_state
*state
)
1660 return skb_seq_read(offset
, text
, TS_SKB_CB(state
));
1663 static void skb_ts_finish(struct ts_config
*conf
, struct ts_state
*state
)
1665 skb_abort_seq_read(TS_SKB_CB(state
));
1669 * skb_find_text - Find a text pattern in skb data
1670 * @skb: the buffer to look in
1671 * @from: search offset
1673 * @config: textsearch configuration
1674 * @state: uninitialized textsearch state variable
1676 * Finds a pattern in the skb data according to the specified
1677 * textsearch configuration. Use textsearch_next() to retrieve
1678 * subsequent occurrences of the pattern. Returns the offset
1679 * to the first occurrence or UINT_MAX if no match was found.
1681 unsigned int skb_find_text(struct sk_buff
*skb
, unsigned int from
,
1682 unsigned int to
, struct ts_config
*config
,
1683 struct ts_state
*state
)
1685 config
->get_next_block
= skb_ts_get_next_block
;
1686 config
->finish
= skb_ts_finish
;
1688 skb_prepare_seq_read(skb
, from
, to
, TS_SKB_CB(state
));
1690 return textsearch_find(config
, state
);
1693 void __init
skb_init(void)
1695 skbuff_head_cache
= kmem_cache_create("skbuff_head_cache",
1696 sizeof(struct sk_buff
),
1700 if (!skbuff_head_cache
)
1701 panic("cannot create skbuff cache");
1703 skbuff_fclone_cache
= kmem_cache_create("skbuff_fclone_cache",
1704 (2*sizeof(struct sk_buff
)) +
1709 if (!skbuff_fclone_cache
)
1710 panic("cannot create skbuff cache");
1712 do_gettimeofday(&skb_tv_base
);
1715 EXPORT_SYMBOL(___pskb_trim
);
1716 EXPORT_SYMBOL(__kfree_skb
);
1717 EXPORT_SYMBOL(__pskb_pull_tail
);
1718 EXPORT_SYMBOL(__alloc_skb
);
1719 EXPORT_SYMBOL(pskb_copy
);
1720 EXPORT_SYMBOL(pskb_expand_head
);
1721 EXPORT_SYMBOL(skb_checksum
);
1722 EXPORT_SYMBOL(skb_clone
);
1723 EXPORT_SYMBOL(skb_clone_fraglist
);
1724 EXPORT_SYMBOL(skb_copy
);
1725 EXPORT_SYMBOL(skb_copy_and_csum_bits
);
1726 EXPORT_SYMBOL(skb_copy_and_csum_dev
);
1727 EXPORT_SYMBOL(skb_copy_bits
);
1728 EXPORT_SYMBOL(skb_copy_expand
);
1729 EXPORT_SYMBOL(skb_over_panic
);
1730 EXPORT_SYMBOL(skb_pad
);
1731 EXPORT_SYMBOL(skb_realloc_headroom
);
1732 EXPORT_SYMBOL(skb_under_panic
);
1733 EXPORT_SYMBOL(skb_dequeue
);
1734 EXPORT_SYMBOL(skb_dequeue_tail
);
1735 EXPORT_SYMBOL(skb_insert
);
1736 EXPORT_SYMBOL(skb_queue_purge
);
1737 EXPORT_SYMBOL(skb_queue_head
);
1738 EXPORT_SYMBOL(skb_queue_tail
);
1739 EXPORT_SYMBOL(skb_unlink
);
1740 EXPORT_SYMBOL(skb_append
);
1741 EXPORT_SYMBOL(skb_split
);
1742 EXPORT_SYMBOL(skb_prepare_seq_read
);
1743 EXPORT_SYMBOL(skb_seq_read
);
1744 EXPORT_SYMBOL(skb_abort_seq_read
);
1745 EXPORT_SYMBOL(skb_find_text
);
1746 EXPORT_SYMBOL(skb_tv_base
);