16df7bd77e78828441db6dfe9a721d6632d1cad2
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
;
74 * Keep out-of-line to prevent kernel bloat.
75 * __builtin_return_address is not used because it is not always
80 * skb_over_panic - private function
85 * Out of line support code for skb_put(). Not user callable.
87 void skb_over_panic(struct sk_buff
*skb
, int sz
, void *here
)
89 printk(KERN_EMERG
"skb_over_panic: text:%p len:%d put:%d head:%p "
90 "data:%p tail:%p end:%p dev:%s\n",
91 here
, skb
->len
, sz
, skb
->head
, skb
->data
, skb
->tail
, skb
->end
,
92 skb
->dev
? skb
->dev
->name
: "<NULL>");
97 * skb_under_panic - private function
102 * Out of line support code for skb_push(). Not user callable.
105 void skb_under_panic(struct sk_buff
*skb
, int sz
, void *here
)
107 printk(KERN_EMERG
"skb_under_panic: text:%p len:%d put:%d head:%p "
108 "data:%p tail:%p end:%p dev:%s\n",
109 here
, skb
->len
, sz
, skb
->head
, skb
->data
, skb
->tail
, skb
->end
,
110 skb
->dev
? skb
->dev
->name
: "<NULL>");
114 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
115 * 'private' fields and also do memory statistics to find all the
121 * alloc_skb - allocate a network buffer
122 * @size: size to allocate
123 * @gfp_mask: allocation mask
125 * Allocate a new &sk_buff. The returned buffer has no headroom and a
126 * tail room of size bytes. The object has a reference count of one.
127 * The return is the buffer. On a failure the return is %NULL.
129 * Buffers may only be allocated from interrupts using a @gfp_mask of
132 struct sk_buff
*alloc_skb(unsigned int size
, unsigned int __nocast gfp_mask
)
138 skb
= kmem_cache_alloc(skbuff_head_cache
,
139 gfp_mask
& ~__GFP_DMA
);
143 /* Get the DATA. Size must match skb_add_mtu(). */
144 size
= SKB_DATA_ALIGN(size
);
145 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
149 memset(skb
, 0, offsetof(struct sk_buff
, truesize
));
150 skb
->truesize
= size
+ sizeof(struct sk_buff
);
151 atomic_set(&skb
->users
, 1);
155 skb
->end
= data
+ size
;
157 atomic_set(&(skb_shinfo(skb
)->dataref
), 1);
158 skb_shinfo(skb
)->nr_frags
= 0;
159 skb_shinfo(skb
)->tso_size
= 0;
160 skb_shinfo(skb
)->tso_segs
= 0;
161 skb_shinfo(skb
)->frag_list
= NULL
;
165 kmem_cache_free(skbuff_head_cache
, skb
);
171 * alloc_skb_from_cache - allocate a network buffer
172 * @cp: kmem_cache from which to allocate the data area
173 * (object size must be big enough for @size bytes + skb overheads)
174 * @size: size to allocate
175 * @gfp_mask: allocation mask
177 * Allocate a new &sk_buff. The returned buffer has no headroom and
178 * tail room of size bytes. The object has a reference count of one.
179 * The return is the buffer. On a failure the return is %NULL.
181 * Buffers may only be allocated from interrupts using a @gfp_mask of
184 struct sk_buff
*alloc_skb_from_cache(kmem_cache_t
*cp
,
186 unsigned int __nocast gfp_mask
)
192 skb
= kmem_cache_alloc(skbuff_head_cache
,
193 gfp_mask
& ~__GFP_DMA
);
198 size
= SKB_DATA_ALIGN(size
);
199 data
= kmem_cache_alloc(cp
, gfp_mask
);
203 memset(skb
, 0, offsetof(struct sk_buff
, truesize
));
204 skb
->truesize
= size
+ sizeof(struct sk_buff
);
205 atomic_set(&skb
->users
, 1);
209 skb
->end
= data
+ size
;
211 atomic_set(&(skb_shinfo(skb
)->dataref
), 1);
212 skb_shinfo(skb
)->nr_frags
= 0;
213 skb_shinfo(skb
)->tso_size
= 0;
214 skb_shinfo(skb
)->tso_segs
= 0;
215 skb_shinfo(skb
)->frag_list
= NULL
;
219 kmem_cache_free(skbuff_head_cache
, skb
);
225 static void skb_drop_fraglist(struct sk_buff
*skb
)
227 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
229 skb_shinfo(skb
)->frag_list
= NULL
;
232 struct sk_buff
*this = list
;
238 static void skb_clone_fraglist(struct sk_buff
*skb
)
240 struct sk_buff
*list
;
242 for (list
= skb_shinfo(skb
)->frag_list
; list
; list
= list
->next
)
246 void skb_release_data(struct sk_buff
*skb
)
249 !atomic_sub_return(skb
->nohdr
? (1 << SKB_DATAREF_SHIFT
) + 1 : 1,
250 &skb_shinfo(skb
)->dataref
)) {
251 if (skb_shinfo(skb
)->nr_frags
) {
253 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
254 put_page(skb_shinfo(skb
)->frags
[i
].page
);
257 if (skb_shinfo(skb
)->frag_list
)
258 skb_drop_fraglist(skb
);
265 * Free an skbuff by memory without cleaning the state.
267 void kfree_skbmem(struct sk_buff
*skb
)
269 skb_release_data(skb
);
270 kmem_cache_free(skbuff_head_cache
, skb
);
274 * __kfree_skb - private function
277 * Free an sk_buff. Release anything attached to the buffer.
278 * Clean the state. This is an internal helper function. Users should
279 * always call kfree_skb
282 void __kfree_skb(struct sk_buff
*skb
)
284 dst_release(skb
->dst
);
286 secpath_put(skb
->sp
);
288 if (skb
->destructor
) {
290 skb
->destructor(skb
);
292 #ifdef CONFIG_NETFILTER
293 nf_conntrack_put(skb
->nfct
);
294 #ifdef CONFIG_BRIDGE_NETFILTER
295 nf_bridge_put(skb
->nf_bridge
);
298 /* XXX: IS this still necessary? - JHS */
299 #ifdef CONFIG_NET_SCHED
301 #ifdef CONFIG_NET_CLS_ACT
310 * skb_clone - duplicate an sk_buff
311 * @skb: buffer to clone
312 * @gfp_mask: allocation priority
314 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
315 * copies share the same packet data but not structure. The new
316 * buffer has a reference count of 1. If the allocation fails the
317 * function returns %NULL otherwise the new buffer is returned.
319 * If this function is called from an interrupt gfp_mask() must be
323 struct sk_buff
*skb_clone(struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
325 struct sk_buff
*n
= kmem_cache_alloc(skbuff_head_cache
, gfp_mask
);
330 #define C(x) n->x = skb->x
332 n
->next
= n
->prev
= NULL
;
344 secpath_get(skb
->sp
);
346 memcpy(n
->cb
, skb
->cb
, sizeof(skb
->cb
));
357 n
->destructor
= NULL
;
358 #ifdef CONFIG_NETFILTER
361 nf_conntrack_get(skb
->nfct
);
363 #ifdef CONFIG_BRIDGE_NETFILTER
365 nf_bridge_get(skb
->nf_bridge
);
367 #endif /*CONFIG_NETFILTER*/
368 #ifdef CONFIG_NET_SCHED
370 #ifdef CONFIG_NET_CLS_ACT
371 n
->tc_verd
= SET_TC_VERD(skb
->tc_verd
,0);
372 n
->tc_verd
= CLR_TC_OK2MUNGE(n
->tc_verd
);
373 n
->tc_verd
= CLR_TC_MUNGED(n
->tc_verd
);
379 atomic_set(&n
->users
, 1);
385 atomic_inc(&(skb_shinfo(skb
)->dataref
));
391 static void copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
394 * Shift between the two data areas in bytes
396 unsigned long offset
= new->data
- old
->data
;
400 new->real_dev
= old
->real_dev
;
401 new->priority
= old
->priority
;
402 new->protocol
= old
->protocol
;
403 new->dst
= dst_clone(old
->dst
);
405 new->sp
= secpath_get(old
->sp
);
407 new->h
.raw
= old
->h
.raw
+ offset
;
408 new->nh
.raw
= old
->nh
.raw
+ offset
;
409 new->mac
.raw
= old
->mac
.raw
+ offset
;
410 memcpy(new->cb
, old
->cb
, sizeof(old
->cb
));
411 new->local_df
= old
->local_df
;
412 new->pkt_type
= old
->pkt_type
;
413 new->stamp
= old
->stamp
;
414 new->destructor
= NULL
;
415 #ifdef CONFIG_NETFILTER
416 new->nfmark
= old
->nfmark
;
417 new->nfct
= old
->nfct
;
418 nf_conntrack_get(old
->nfct
);
419 new->nfctinfo
= old
->nfctinfo
;
420 #ifdef CONFIG_BRIDGE_NETFILTER
421 new->nf_bridge
= old
->nf_bridge
;
422 nf_bridge_get(old
->nf_bridge
);
425 #ifdef CONFIG_NET_SCHED
426 #ifdef CONFIG_NET_CLS_ACT
427 new->tc_verd
= old
->tc_verd
;
429 new->tc_index
= old
->tc_index
;
431 atomic_set(&new->users
, 1);
432 skb_shinfo(new)->tso_size
= skb_shinfo(old
)->tso_size
;
433 skb_shinfo(new)->tso_segs
= skb_shinfo(old
)->tso_segs
;
437 * skb_copy - create private copy of an sk_buff
438 * @skb: buffer to copy
439 * @gfp_mask: allocation priority
441 * Make a copy of both an &sk_buff and its data. This is used when the
442 * caller wishes to modify the data and needs a private copy of the
443 * data to alter. Returns %NULL on failure or the pointer to the buffer
444 * on success. The returned buffer has a reference count of 1.
446 * As by-product this function converts non-linear &sk_buff to linear
447 * one, so that &sk_buff becomes completely private and caller is allowed
448 * to modify all the data of returned buffer. This means that this
449 * function is not recommended for use in circumstances when only
450 * header is going to be modified. Use pskb_copy() instead.
453 struct sk_buff
*skb_copy(const struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
455 int headerlen
= skb
->data
- skb
->head
;
457 * Allocate the copy buffer
459 struct sk_buff
*n
= alloc_skb(skb
->end
- skb
->head
+ skb
->data_len
,
464 /* Set the data pointer */
465 skb_reserve(n
, headerlen
);
466 /* Set the tail pointer and length */
467 skb_put(n
, skb
->len
);
469 n
->ip_summed
= skb
->ip_summed
;
471 if (skb_copy_bits(skb
, -headerlen
, n
->head
, headerlen
+ skb
->len
))
474 copy_skb_header(n
, skb
);
480 * pskb_copy - create copy of an sk_buff with private head.
481 * @skb: buffer to copy
482 * @gfp_mask: allocation priority
484 * Make a copy of both an &sk_buff and part of its data, located
485 * in header. Fragmented data remain shared. This is used when
486 * the caller wishes to modify only header of &sk_buff and needs
487 * private copy of the header to alter. Returns %NULL on failure
488 * or the pointer to the buffer on success.
489 * The returned buffer has a reference count of 1.
492 struct sk_buff
*pskb_copy(struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
495 * Allocate the copy buffer
497 struct sk_buff
*n
= alloc_skb(skb
->end
- skb
->head
, gfp_mask
);
502 /* Set the data pointer */
503 skb_reserve(n
, skb
->data
- skb
->head
);
504 /* Set the tail pointer and length */
505 skb_put(n
, skb_headlen(skb
));
507 memcpy(n
->data
, skb
->data
, n
->len
);
509 n
->ip_summed
= skb
->ip_summed
;
511 n
->data_len
= skb
->data_len
;
514 if (skb_shinfo(skb
)->nr_frags
) {
517 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
518 skb_shinfo(n
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
519 get_page(skb_shinfo(n
)->frags
[i
].page
);
521 skb_shinfo(n
)->nr_frags
= i
;
524 if (skb_shinfo(skb
)->frag_list
) {
525 skb_shinfo(n
)->frag_list
= skb_shinfo(skb
)->frag_list
;
526 skb_clone_fraglist(n
);
529 copy_skb_header(n
, skb
);
535 * pskb_expand_head - reallocate header of &sk_buff
536 * @skb: buffer to reallocate
537 * @nhead: room to add at head
538 * @ntail: room to add at tail
539 * @gfp_mask: allocation priority
541 * Expands (or creates identical copy, if &nhead and &ntail are zero)
542 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
543 * reference count of 1. Returns zero in the case of success or error,
544 * if expansion failed. In the last case, &sk_buff is not changed.
546 * All the pointers pointing into skb header may change and must be
547 * reloaded after call to this function.
550 int pskb_expand_head(struct sk_buff
*skb
, int nhead
, int ntail
,
551 unsigned int __nocast gfp_mask
)
555 int size
= nhead
+ (skb
->end
- skb
->head
) + ntail
;
561 size
= SKB_DATA_ALIGN(size
);
563 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
567 /* Copy only real data... and, alas, header. This should be
568 * optimized for the cases when header is void. */
569 memcpy(data
+ nhead
, skb
->head
, skb
->tail
- skb
->head
);
570 memcpy(data
+ size
, skb
->end
, sizeof(struct skb_shared_info
));
572 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
573 get_page(skb_shinfo(skb
)->frags
[i
].page
);
575 if (skb_shinfo(skb
)->frag_list
)
576 skb_clone_fraglist(skb
);
578 skb_release_data(skb
);
580 off
= (data
+ nhead
) - skb
->head
;
583 skb
->end
= data
+ size
;
591 atomic_set(&skb_shinfo(skb
)->dataref
, 1);
598 /* Make private copy of skb with writable head and some headroom */
600 struct sk_buff
*skb_realloc_headroom(struct sk_buff
*skb
, unsigned int headroom
)
602 struct sk_buff
*skb2
;
603 int delta
= headroom
- skb_headroom(skb
);
606 skb2
= pskb_copy(skb
, GFP_ATOMIC
);
608 skb2
= skb_clone(skb
, GFP_ATOMIC
);
609 if (skb2
&& pskb_expand_head(skb2
, SKB_DATA_ALIGN(delta
), 0,
620 * skb_copy_expand - copy and expand sk_buff
621 * @skb: buffer to copy
622 * @newheadroom: new free bytes at head
623 * @newtailroom: new free bytes at tail
624 * @gfp_mask: allocation priority
626 * Make a copy of both an &sk_buff and its data and while doing so
627 * allocate additional space.
629 * This is used when the caller wishes to modify the data and needs a
630 * private copy of the data to alter as well as more space for new fields.
631 * Returns %NULL on failure or the pointer to the buffer
632 * on success. The returned buffer has a reference count of 1.
634 * You must pass %GFP_ATOMIC as the allocation priority if this function
635 * is called from an interrupt.
637 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used
638 * only by netfilter in the cases when checksum is recalculated? --ANK
640 struct sk_buff
*skb_copy_expand(const struct sk_buff
*skb
,
641 int newheadroom
, int newtailroom
,
642 unsigned int __nocast gfp_mask
)
645 * Allocate the copy buffer
647 struct sk_buff
*n
= alloc_skb(newheadroom
+ skb
->len
+ newtailroom
,
649 int head_copy_len
, head_copy_off
;
654 skb_reserve(n
, newheadroom
);
656 /* Set the tail pointer and length */
657 skb_put(n
, skb
->len
);
659 head_copy_len
= skb_headroom(skb
);
661 if (newheadroom
<= head_copy_len
)
662 head_copy_len
= newheadroom
;
664 head_copy_off
= newheadroom
- head_copy_len
;
666 /* Copy the linear header and data. */
667 if (skb_copy_bits(skb
, -head_copy_len
, n
->head
+ head_copy_off
,
668 skb
->len
+ head_copy_len
))
671 copy_skb_header(n
, skb
);
677 * skb_pad - zero pad the tail of an skb
678 * @skb: buffer to pad
681 * Ensure that a buffer is followed by a padding area that is zero
682 * filled. Used by network drivers which may DMA or transfer data
683 * beyond the buffer end onto the wire.
685 * May return NULL in out of memory cases.
688 struct sk_buff
*skb_pad(struct sk_buff
*skb
, int pad
)
690 struct sk_buff
*nskb
;
692 /* If the skbuff is non linear tailroom is always zero.. */
693 if (skb_tailroom(skb
) >= pad
) {
694 memset(skb
->data
+skb
->len
, 0, pad
);
698 nskb
= skb_copy_expand(skb
, skb_headroom(skb
), skb_tailroom(skb
) + pad
, GFP_ATOMIC
);
701 memset(nskb
->data
+nskb
->len
, 0, pad
);
705 /* Trims skb to length len. It can change skb pointers, if "realloc" is 1.
706 * If realloc==0 and trimming is impossible without change of data,
710 int ___pskb_trim(struct sk_buff
*skb
, unsigned int len
, int realloc
)
712 int offset
= skb_headlen(skb
);
713 int nfrags
= skb_shinfo(skb
)->nr_frags
;
716 for (i
= 0; i
< nfrags
; i
++) {
717 int end
= offset
+ skb_shinfo(skb
)->frags
[i
].size
;
719 if (skb_cloned(skb
)) {
722 if (pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))
726 put_page(skb_shinfo(skb
)->frags
[i
].page
);
727 skb_shinfo(skb
)->nr_frags
--;
729 skb_shinfo(skb
)->frags
[i
].size
= len
- offset
;
736 skb
->data_len
-= skb
->len
- len
;
739 if (len
<= skb_headlen(skb
)) {
742 skb
->tail
= skb
->data
+ len
;
743 if (skb_shinfo(skb
)->frag_list
&& !skb_cloned(skb
))
744 skb_drop_fraglist(skb
);
746 skb
->data_len
-= skb
->len
- len
;
755 * __pskb_pull_tail - advance tail of skb header
756 * @skb: buffer to reallocate
757 * @delta: number of bytes to advance tail
759 * The function makes a sense only on a fragmented &sk_buff,
760 * it expands header moving its tail forward and copying necessary
761 * data from fragmented part.
763 * &sk_buff MUST have reference count of 1.
765 * Returns %NULL (and &sk_buff does not change) if pull failed
766 * or value of new tail of skb in the case of success.
768 * All the pointers pointing into skb header may change and must be
769 * reloaded after call to this function.
772 /* Moves tail of skb head forward, copying data from fragmented part,
773 * when it is necessary.
774 * 1. It may fail due to malloc failure.
775 * 2. It may change skb pointers.
777 * It is pretty complicated. Luckily, it is called only in exceptional cases.
779 unsigned char *__pskb_pull_tail(struct sk_buff
*skb
, int delta
)
781 /* If skb has not enough free space at tail, get new one
782 * plus 128 bytes for future expansions. If we have enough
783 * room at tail, reallocate without expansion only if skb is cloned.
785 int i
, k
, eat
= (skb
->tail
+ delta
) - skb
->end
;
787 if (eat
> 0 || skb_cloned(skb
)) {
788 if (pskb_expand_head(skb
, 0, eat
> 0 ? eat
+ 128 : 0,
793 if (skb_copy_bits(skb
, skb_headlen(skb
), skb
->tail
, delta
))
796 /* Optimization: no fragments, no reasons to preestimate
797 * size of pulled pages. Superb.
799 if (!skb_shinfo(skb
)->frag_list
)
802 /* Estimate size of pulled pages. */
804 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
805 if (skb_shinfo(skb
)->frags
[i
].size
>= eat
)
807 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
810 /* If we need update frag list, we are in troubles.
811 * Certainly, it possible to add an offset to skb data,
812 * but taking into account that pulling is expected to
813 * be very rare operation, it is worth to fight against
814 * further bloating skb head and crucify ourselves here instead.
815 * Pure masohism, indeed. 8)8)
818 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
819 struct sk_buff
*clone
= NULL
;
820 struct sk_buff
*insp
= NULL
;
826 if (list
->len
<= eat
) {
827 /* Eaten as whole. */
832 /* Eaten partially. */
834 if (skb_shared(list
)) {
835 /* Sucks! We need to fork list. :-( */
836 clone
= skb_clone(list
, GFP_ATOMIC
);
842 /* This may be pulled without
846 if (!pskb_pull(list
, eat
)) {
855 /* Free pulled out fragments. */
856 while ((list
= skb_shinfo(skb
)->frag_list
) != insp
) {
857 skb_shinfo(skb
)->frag_list
= list
->next
;
860 /* And insert new clone at head. */
863 skb_shinfo(skb
)->frag_list
= clone
;
866 /* Success! Now we may commit changes to skb data. */
871 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
872 if (skb_shinfo(skb
)->frags
[i
].size
<= eat
) {
873 put_page(skb_shinfo(skb
)->frags
[i
].page
);
874 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
876 skb_shinfo(skb
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
878 skb_shinfo(skb
)->frags
[k
].page_offset
+= eat
;
879 skb_shinfo(skb
)->frags
[k
].size
-= eat
;
885 skb_shinfo(skb
)->nr_frags
= k
;
888 skb
->data_len
-= delta
;
893 /* Copy some data bits from skb to kernel buffer. */
895 int skb_copy_bits(const struct sk_buff
*skb
, int offset
, void *to
, int len
)
898 int start
= skb_headlen(skb
);
900 if (offset
> (int)skb
->len
- len
)
904 if ((copy
= start
- offset
) > 0) {
907 memcpy(to
, skb
->data
+ offset
, copy
);
908 if ((len
-= copy
) == 0)
914 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
917 BUG_TRAP(start
<= offset
+ len
);
919 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
920 if ((copy
= end
- offset
) > 0) {
926 vaddr
= kmap_skb_frag(&skb_shinfo(skb
)->frags
[i
]);
928 vaddr
+ skb_shinfo(skb
)->frags
[i
].page_offset
+
929 offset
- start
, copy
);
930 kunmap_skb_frag(vaddr
);
932 if ((len
-= copy
) == 0)
940 if (skb_shinfo(skb
)->frag_list
) {
941 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
943 for (; list
; list
= list
->next
) {
946 BUG_TRAP(start
<= offset
+ len
);
948 end
= start
+ list
->len
;
949 if ((copy
= end
- offset
) > 0) {
952 if (skb_copy_bits(list
, offset
- start
,
955 if ((len
-= copy
) == 0)
971 * skb_store_bits - store bits from kernel buffer to skb
972 * @skb: destination buffer
973 * @offset: offset in destination
974 * @from: source buffer
975 * @len: number of bytes to copy
977 * Copy the specified number of bytes from the source buffer to the
978 * destination skb. This function handles all the messy bits of
979 * traversing fragment lists and such.
982 int skb_store_bits(const struct sk_buff
*skb
, int offset
, void *from
, int len
)
985 int start
= skb_headlen(skb
);
987 if (offset
> (int)skb
->len
- len
)
990 if ((copy
= start
- offset
) > 0) {
993 memcpy(skb
->data
+ offset
, from
, copy
);
994 if ((len
-= copy
) == 0)
1000 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1001 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1004 BUG_TRAP(start
<= offset
+ len
);
1006 end
= start
+ frag
->size
;
1007 if ((copy
= end
- offset
) > 0) {
1013 vaddr
= kmap_skb_frag(frag
);
1014 memcpy(vaddr
+ frag
->page_offset
+ offset
- start
,
1016 kunmap_skb_frag(vaddr
);
1018 if ((len
-= copy
) == 0)
1026 if (skb_shinfo(skb
)->frag_list
) {
1027 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1029 for (; list
; list
= list
->next
) {
1032 BUG_TRAP(start
<= offset
+ len
);
1034 end
= start
+ list
->len
;
1035 if ((copy
= end
- offset
) > 0) {
1038 if (skb_store_bits(list
, offset
- start
,
1041 if ((len
-= copy
) == 0)
1056 EXPORT_SYMBOL(skb_store_bits
);
1058 /* Checksum skb data. */
1060 unsigned int skb_checksum(const struct sk_buff
*skb
, int offset
,
1061 int len
, unsigned int csum
)
1063 int start
= skb_headlen(skb
);
1064 int i
, copy
= start
- offset
;
1067 /* Checksum header. */
1071 csum
= csum_partial(skb
->data
+ offset
, copy
, csum
);
1072 if ((len
-= copy
) == 0)
1078 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1081 BUG_TRAP(start
<= offset
+ len
);
1083 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1084 if ((copy
= end
- offset
) > 0) {
1087 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1091 vaddr
= kmap_skb_frag(frag
);
1092 csum2
= csum_partial(vaddr
+ frag
->page_offset
+
1093 offset
- start
, copy
, 0);
1094 kunmap_skb_frag(vaddr
);
1095 csum
= csum_block_add(csum
, csum2
, pos
);
1104 if (skb_shinfo(skb
)->frag_list
) {
1105 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1107 for (; list
; list
= list
->next
) {
1110 BUG_TRAP(start
<= offset
+ len
);
1112 end
= start
+ list
->len
;
1113 if ((copy
= end
- offset
) > 0) {
1117 csum2
= skb_checksum(list
, offset
- start
,
1119 csum
= csum_block_add(csum
, csum2
, pos
);
1120 if ((len
-= copy
) == 0)
1134 /* Both of above in one bottle. */
1136 unsigned int skb_copy_and_csum_bits(const struct sk_buff
*skb
, int offset
,
1137 u8
*to
, int len
, unsigned int csum
)
1139 int start
= skb_headlen(skb
);
1140 int i
, copy
= start
- offset
;
1147 csum
= csum_partial_copy_nocheck(skb
->data
+ offset
, to
,
1149 if ((len
-= copy
) == 0)
1156 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1159 BUG_TRAP(start
<= offset
+ len
);
1161 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1162 if ((copy
= end
- offset
) > 0) {
1165 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1169 vaddr
= kmap_skb_frag(frag
);
1170 csum2
= csum_partial_copy_nocheck(vaddr
+
1174 kunmap_skb_frag(vaddr
);
1175 csum
= csum_block_add(csum
, csum2
, pos
);
1185 if (skb_shinfo(skb
)->frag_list
) {
1186 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1188 for (; list
; list
= list
->next
) {
1192 BUG_TRAP(start
<= offset
+ len
);
1194 end
= start
+ list
->len
;
1195 if ((copy
= end
- offset
) > 0) {
1198 csum2
= skb_copy_and_csum_bits(list
,
1201 csum
= csum_block_add(csum
, csum2
, pos
);
1202 if ((len
-= copy
) == 0)
1216 void skb_copy_and_csum_dev(const struct sk_buff
*skb
, u8
*to
)
1221 if (skb
->ip_summed
== CHECKSUM_HW
)
1222 csstart
= skb
->h
.raw
- skb
->data
;
1224 csstart
= skb_headlen(skb
);
1226 if (csstart
> skb_headlen(skb
))
1229 memcpy(to
, skb
->data
, csstart
);
1232 if (csstart
!= skb
->len
)
1233 csum
= skb_copy_and_csum_bits(skb
, csstart
, to
+ csstart
,
1234 skb
->len
- csstart
, 0);
1236 if (skb
->ip_summed
== CHECKSUM_HW
) {
1237 long csstuff
= csstart
+ skb
->csum
;
1239 *((unsigned short *)(to
+ csstuff
)) = csum_fold(csum
);
1244 * skb_dequeue - remove from the head of the queue
1245 * @list: list to dequeue from
1247 * Remove the head of the list. The list lock is taken so the function
1248 * may be used safely with other locking list functions. The head item is
1249 * returned or %NULL if the list is empty.
1252 struct sk_buff
*skb_dequeue(struct sk_buff_head
*list
)
1254 unsigned long flags
;
1255 struct sk_buff
*result
;
1257 spin_lock_irqsave(&list
->lock
, flags
);
1258 result
= __skb_dequeue(list
);
1259 spin_unlock_irqrestore(&list
->lock
, flags
);
1264 * skb_dequeue_tail - remove from the tail of the queue
1265 * @list: list to dequeue from
1267 * Remove the tail of the list. The list lock is taken so the function
1268 * may be used safely with other locking list functions. The tail item is
1269 * returned or %NULL if the list is empty.
1271 struct sk_buff
*skb_dequeue_tail(struct sk_buff_head
*list
)
1273 unsigned long flags
;
1274 struct sk_buff
*result
;
1276 spin_lock_irqsave(&list
->lock
, flags
);
1277 result
= __skb_dequeue_tail(list
);
1278 spin_unlock_irqrestore(&list
->lock
, flags
);
1283 * skb_queue_purge - empty a list
1284 * @list: list to empty
1286 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1287 * the list and one reference dropped. This function takes the list
1288 * lock and is atomic with respect to other list locking functions.
1290 void skb_queue_purge(struct sk_buff_head
*list
)
1292 struct sk_buff
*skb
;
1293 while ((skb
= skb_dequeue(list
)) != NULL
)
1298 * skb_queue_head - queue a buffer at the list head
1299 * @list: list to use
1300 * @newsk: buffer to queue
1302 * Queue a buffer at the start of the list. This function takes the
1303 * list lock and can be used safely with other locking &sk_buff functions
1306 * A buffer cannot be placed on two lists at the same time.
1308 void skb_queue_head(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1310 unsigned long flags
;
1312 spin_lock_irqsave(&list
->lock
, flags
);
1313 __skb_queue_head(list
, newsk
);
1314 spin_unlock_irqrestore(&list
->lock
, flags
);
1318 * skb_queue_tail - queue a buffer at the list tail
1319 * @list: list to use
1320 * @newsk: buffer to queue
1322 * Queue a buffer at the tail of the list. This function takes the
1323 * list lock and can be used safely with other locking &sk_buff functions
1326 * A buffer cannot be placed on two lists at the same time.
1328 void skb_queue_tail(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1330 unsigned long flags
;
1332 spin_lock_irqsave(&list
->lock
, flags
);
1333 __skb_queue_tail(list
, newsk
);
1334 spin_unlock_irqrestore(&list
->lock
, flags
);
1338 * skb_unlink - remove a buffer from a list
1339 * @skb: buffer to remove
1340 * @list: list to use
1342 * Remove a packet from a list. The list locks are taken and this
1343 * function is atomic with respect to other list locked calls
1345 * You must know what list the SKB is on.
1347 void skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
)
1349 unsigned long flags
;
1351 spin_lock_irqsave(&list
->lock
, flags
);
1352 __skb_unlink(skb
, list
);
1353 spin_unlock_irqrestore(&list
->lock
, flags
);
1357 * skb_append - append a buffer
1358 * @old: buffer to insert after
1359 * @newsk: buffer to insert
1360 * @list: list to use
1362 * Place a packet after a given packet in a list. The list locks are taken
1363 * and this function is atomic with respect to other list locked calls.
1364 * A buffer cannot be placed on two lists at the same time.
1366 void skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1368 unsigned long flags
;
1370 spin_lock_irqsave(&list
->lock
, flags
);
1371 __skb_append(old
, newsk
, list
);
1372 spin_unlock_irqrestore(&list
->lock
, flags
);
1377 * skb_insert - insert a buffer
1378 * @old: buffer to insert before
1379 * @newsk: buffer to insert
1380 * @list: list to use
1382 * Place a packet before a given packet in a list. The list locks are
1383 * taken and this function is atomic with respect to other list locked
1386 * A buffer cannot be placed on two lists at the same time.
1388 void skb_insert(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1390 unsigned long flags
;
1392 spin_lock_irqsave(&list
->lock
, flags
);
1393 __skb_insert(newsk
, old
->prev
, old
, list
);
1394 spin_unlock_irqrestore(&list
->lock
, flags
);
1399 * Tune the memory allocator for a new MTU size.
1401 void skb_add_mtu(int mtu
)
1403 /* Must match allocation in alloc_skb */
1404 mtu
= SKB_DATA_ALIGN(mtu
) + sizeof(struct skb_shared_info
);
1406 kmem_add_cache_size(mtu
);
1410 static inline void skb_split_inside_header(struct sk_buff
*skb
,
1411 struct sk_buff
* skb1
,
1412 const u32 len
, const int pos
)
1416 memcpy(skb_put(skb1
, pos
- len
), skb
->data
+ len
, pos
- len
);
1418 /* And move data appendix as is. */
1419 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
1420 skb_shinfo(skb1
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
1422 skb_shinfo(skb1
)->nr_frags
= skb_shinfo(skb
)->nr_frags
;
1423 skb_shinfo(skb
)->nr_frags
= 0;
1424 skb1
->data_len
= skb
->data_len
;
1425 skb1
->len
+= skb1
->data_len
;
1428 skb
->tail
= skb
->data
+ len
;
1431 static inline void skb_split_no_header(struct sk_buff
*skb
,
1432 struct sk_buff
* skb1
,
1433 const u32 len
, int pos
)
1436 const int nfrags
= skb_shinfo(skb
)->nr_frags
;
1438 skb_shinfo(skb
)->nr_frags
= 0;
1439 skb1
->len
= skb1
->data_len
= skb
->len
- len
;
1441 skb
->data_len
= len
- pos
;
1443 for (i
= 0; i
< nfrags
; i
++) {
1444 int size
= skb_shinfo(skb
)->frags
[i
].size
;
1446 if (pos
+ size
> len
) {
1447 skb_shinfo(skb1
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1451 * We have two variants in this case:
1452 * 1. Move all the frag to the second
1453 * part, if it is possible. F.e.
1454 * this approach is mandatory for TUX,
1455 * where splitting is expensive.
1456 * 2. Split is accurately. We make this.
1458 get_page(skb_shinfo(skb
)->frags
[i
].page
);
1459 skb_shinfo(skb1
)->frags
[0].page_offset
+= len
- pos
;
1460 skb_shinfo(skb1
)->frags
[0].size
-= len
- pos
;
1461 skb_shinfo(skb
)->frags
[i
].size
= len
- pos
;
1462 skb_shinfo(skb
)->nr_frags
++;
1466 skb_shinfo(skb
)->nr_frags
++;
1469 skb_shinfo(skb1
)->nr_frags
= k
;
1473 * skb_split - Split fragmented skb to two parts at length len.
1474 * @skb: the buffer to split
1475 * @skb1: the buffer to receive the second part
1476 * @len: new length for skb
1478 void skb_split(struct sk_buff
*skb
, struct sk_buff
*skb1
, const u32 len
)
1480 int pos
= skb_headlen(skb
);
1482 if (len
< pos
) /* Split line is inside header. */
1483 skb_split_inside_header(skb
, skb1
, len
, pos
);
1484 else /* Second chunk has no header, nothing to copy. */
1485 skb_split_no_header(skb
, skb1
, len
, pos
);
1489 * skb_prepare_seq_read - Prepare a sequential read of skb data
1490 * @skb: the buffer to read
1491 * @from: lower offset of data to be read
1492 * @to: upper offset of data to be read
1493 * @st: state variable
1495 * Initializes the specified state variable. Must be called before
1496 * invoking skb_seq_read() for the first time.
1498 void skb_prepare_seq_read(struct sk_buff
*skb
, unsigned int from
,
1499 unsigned int to
, struct skb_seq_state
*st
)
1501 st
->lower_offset
= from
;
1502 st
->upper_offset
= to
;
1503 st
->root_skb
= st
->cur_skb
= skb
;
1504 st
->frag_idx
= st
->stepped_offset
= 0;
1505 st
->frag_data
= NULL
;
1509 * skb_seq_read - Sequentially read skb data
1510 * @consumed: number of bytes consumed by the caller so far
1511 * @data: destination pointer for data to be returned
1512 * @st: state variable
1514 * Reads a block of skb data at &consumed relative to the
1515 * lower offset specified to skb_prepare_seq_read(). Assigns
1516 * the head of the data block to &data and returns the length
1517 * of the block or 0 if the end of the skb data or the upper
1518 * offset has been reached.
1520 * The caller is not required to consume all of the data
1521 * returned, i.e. &consumed is typically set to the number
1522 * of bytes already consumed and the next call to
1523 * skb_seq_read() will return the remaining part of the block.
1525 * Note: The size of each block of data returned can be arbitary,
1526 * this limitation is the cost for zerocopy seqeuental
1527 * reads of potentially non linear data.
1529 * Note: Fragment lists within fragments are not implemented
1530 * at the moment, state->root_skb could be replaced with
1531 * a stack for this purpose.
1533 unsigned int skb_seq_read(unsigned int consumed
, const u8
**data
,
1534 struct skb_seq_state
*st
)
1536 unsigned int block_limit
, abs_offset
= consumed
+ st
->lower_offset
;
1539 if (unlikely(abs_offset
>= st
->upper_offset
))
1543 block_limit
= skb_headlen(st
->cur_skb
);
1545 if (abs_offset
< block_limit
) {
1546 *data
= st
->cur_skb
->data
+ abs_offset
;
1547 return block_limit
- abs_offset
;
1550 if (st
->frag_idx
== 0 && !st
->frag_data
)
1551 st
->stepped_offset
+= skb_headlen(st
->cur_skb
);
1553 while (st
->frag_idx
< skb_shinfo(st
->cur_skb
)->nr_frags
) {
1554 frag
= &skb_shinfo(st
->cur_skb
)->frags
[st
->frag_idx
];
1555 block_limit
= frag
->size
+ st
->stepped_offset
;
1557 if (abs_offset
< block_limit
) {
1559 st
->frag_data
= kmap_skb_frag(frag
);
1561 *data
= (u8
*) st
->frag_data
+ frag
->page_offset
+
1562 (abs_offset
- st
->stepped_offset
);
1564 return block_limit
- abs_offset
;
1567 if (st
->frag_data
) {
1568 kunmap_skb_frag(st
->frag_data
);
1569 st
->frag_data
= NULL
;
1573 st
->stepped_offset
+= frag
->size
;
1576 if (st
->cur_skb
->next
) {
1577 st
->cur_skb
= st
->cur_skb
->next
;
1580 } else if (st
->root_skb
== st
->cur_skb
&&
1581 skb_shinfo(st
->root_skb
)->frag_list
) {
1582 st
->cur_skb
= skb_shinfo(st
->root_skb
)->frag_list
;
1590 * skb_abort_seq_read - Abort a sequential read of skb data
1591 * @st: state variable
1593 * Must be called if skb_seq_read() was not called until it
1596 void skb_abort_seq_read(struct skb_seq_state
*st
)
1599 kunmap_skb_frag(st
->frag_data
);
1602 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
1604 static unsigned int skb_ts_get_next_block(unsigned int offset
, const u8
**text
,
1605 struct ts_config
*conf
,
1606 struct ts_state
*state
)
1608 return skb_seq_read(offset
, text
, TS_SKB_CB(state
));
1611 static void skb_ts_finish(struct ts_config
*conf
, struct ts_state
*state
)
1613 skb_abort_seq_read(TS_SKB_CB(state
));
1617 * skb_find_text - Find a text pattern in skb data
1618 * @skb: the buffer to look in
1619 * @from: search offset
1621 * @config: textsearch configuration
1622 * @state: uninitialized textsearch state variable
1624 * Finds a pattern in the skb data according to the specified
1625 * textsearch configuration. Use textsearch_next() to retrieve
1626 * subsequent occurrences of the pattern. Returns the offset
1627 * to the first occurrence or UINT_MAX if no match was found.
1629 unsigned int skb_find_text(struct sk_buff
*skb
, unsigned int from
,
1630 unsigned int to
, struct ts_config
*config
,
1631 struct ts_state
*state
)
1633 config
->get_next_block
= skb_ts_get_next_block
;
1634 config
->finish
= skb_ts_finish
;
1636 skb_prepare_seq_read(skb
, from
, to
, TS_SKB_CB(state
));
1638 return textsearch_find(config
, state
);
1641 void __init
skb_init(void)
1643 skbuff_head_cache
= kmem_cache_create("skbuff_head_cache",
1644 sizeof(struct sk_buff
),
1648 if (!skbuff_head_cache
)
1649 panic("cannot create skbuff cache");
1652 EXPORT_SYMBOL(___pskb_trim
);
1653 EXPORT_SYMBOL(__kfree_skb
);
1654 EXPORT_SYMBOL(__pskb_pull_tail
);
1655 EXPORT_SYMBOL(alloc_skb
);
1656 EXPORT_SYMBOL(pskb_copy
);
1657 EXPORT_SYMBOL(pskb_expand_head
);
1658 EXPORT_SYMBOL(skb_checksum
);
1659 EXPORT_SYMBOL(skb_clone
);
1660 EXPORT_SYMBOL(skb_clone_fraglist
);
1661 EXPORT_SYMBOL(skb_copy
);
1662 EXPORT_SYMBOL(skb_copy_and_csum_bits
);
1663 EXPORT_SYMBOL(skb_copy_and_csum_dev
);
1664 EXPORT_SYMBOL(skb_copy_bits
);
1665 EXPORT_SYMBOL(skb_copy_expand
);
1666 EXPORT_SYMBOL(skb_over_panic
);
1667 EXPORT_SYMBOL(skb_pad
);
1668 EXPORT_SYMBOL(skb_realloc_headroom
);
1669 EXPORT_SYMBOL(skb_under_panic
);
1670 EXPORT_SYMBOL(skb_dequeue
);
1671 EXPORT_SYMBOL(skb_dequeue_tail
);
1672 EXPORT_SYMBOL(skb_insert
);
1673 EXPORT_SYMBOL(skb_queue_purge
);
1674 EXPORT_SYMBOL(skb_queue_head
);
1675 EXPORT_SYMBOL(skb_queue_tail
);
1676 EXPORT_SYMBOL(skb_unlink
);
1677 EXPORT_SYMBOL(skb_append
);
1678 EXPORT_SYMBOL(skb_split
);
1679 EXPORT_SYMBOL(skb_prepare_seq_read
);
1680 EXPORT_SYMBOL(skb_seq_read
);
1681 EXPORT_SYMBOL(skb_abort_seq_read
);
1682 EXPORT_SYMBOL(skb_find_text
);