ef498cb9f786ebd6a93c8168302e43cb6ae1b6ff
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
;
343 secpath_get(skb
->sp
);
345 memcpy(n
->cb
, skb
->cb
, sizeof(skb
->cb
));
356 n
->destructor
= NULL
;
357 #ifdef CONFIG_NETFILTER
360 nf_conntrack_get(skb
->nfct
);
362 #ifdef CONFIG_BRIDGE_NETFILTER
364 nf_bridge_get(skb
->nf_bridge
);
366 #endif /*CONFIG_NETFILTER*/
367 #ifdef CONFIG_NET_SCHED
369 #ifdef CONFIG_NET_CLS_ACT
370 n
->tc_verd
= SET_TC_VERD(skb
->tc_verd
,0);
371 n
->tc_verd
= CLR_TC_OK2MUNGE(n
->tc_verd
);
372 n
->tc_verd
= CLR_TC_MUNGED(n
->tc_verd
);
378 atomic_set(&n
->users
, 1);
384 atomic_inc(&(skb_shinfo(skb
)->dataref
));
390 static void copy_skb_header(struct sk_buff
*new, const struct sk_buff
*old
)
393 * Shift between the two data areas in bytes
395 unsigned long offset
= new->data
- old
->data
;
399 new->priority
= old
->priority
;
400 new->protocol
= old
->protocol
;
401 new->dst
= dst_clone(old
->dst
);
403 new->sp
= secpath_get(old
->sp
);
405 new->h
.raw
= old
->h
.raw
+ offset
;
406 new->nh
.raw
= old
->nh
.raw
+ offset
;
407 new->mac
.raw
= old
->mac
.raw
+ offset
;
408 memcpy(new->cb
, old
->cb
, sizeof(old
->cb
));
409 new->local_df
= old
->local_df
;
410 new->pkt_type
= old
->pkt_type
;
411 new->stamp
= old
->stamp
;
412 new->destructor
= NULL
;
413 #ifdef CONFIG_NETFILTER
414 new->nfmark
= old
->nfmark
;
415 new->nfct
= old
->nfct
;
416 nf_conntrack_get(old
->nfct
);
417 new->nfctinfo
= old
->nfctinfo
;
418 #ifdef CONFIG_BRIDGE_NETFILTER
419 new->nf_bridge
= old
->nf_bridge
;
420 nf_bridge_get(old
->nf_bridge
);
423 #ifdef CONFIG_NET_SCHED
424 #ifdef CONFIG_NET_CLS_ACT
425 new->tc_verd
= old
->tc_verd
;
427 new->tc_index
= old
->tc_index
;
429 atomic_set(&new->users
, 1);
430 skb_shinfo(new)->tso_size
= skb_shinfo(old
)->tso_size
;
431 skb_shinfo(new)->tso_segs
= skb_shinfo(old
)->tso_segs
;
435 * skb_copy - create private copy of an sk_buff
436 * @skb: buffer to copy
437 * @gfp_mask: allocation priority
439 * Make a copy of both an &sk_buff and its data. This is used when the
440 * caller wishes to modify the data and needs a private copy of the
441 * data to alter. Returns %NULL on failure or the pointer to the buffer
442 * on success. The returned buffer has a reference count of 1.
444 * As by-product this function converts non-linear &sk_buff to linear
445 * one, so that &sk_buff becomes completely private and caller is allowed
446 * to modify all the data of returned buffer. This means that this
447 * function is not recommended for use in circumstances when only
448 * header is going to be modified. Use pskb_copy() instead.
451 struct sk_buff
*skb_copy(const struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
453 int headerlen
= skb
->data
- skb
->head
;
455 * Allocate the copy buffer
457 struct sk_buff
*n
= alloc_skb(skb
->end
- skb
->head
+ skb
->data_len
,
462 /* Set the data pointer */
463 skb_reserve(n
, headerlen
);
464 /* Set the tail pointer and length */
465 skb_put(n
, skb
->len
);
467 n
->ip_summed
= skb
->ip_summed
;
469 if (skb_copy_bits(skb
, -headerlen
, n
->head
, headerlen
+ skb
->len
))
472 copy_skb_header(n
, skb
);
478 * pskb_copy - create copy of an sk_buff with private head.
479 * @skb: buffer to copy
480 * @gfp_mask: allocation priority
482 * Make a copy of both an &sk_buff and part of its data, located
483 * in header. Fragmented data remain shared. This is used when
484 * the caller wishes to modify only header of &sk_buff and needs
485 * private copy of the header to alter. Returns %NULL on failure
486 * or the pointer to the buffer on success.
487 * The returned buffer has a reference count of 1.
490 struct sk_buff
*pskb_copy(struct sk_buff
*skb
, unsigned int __nocast gfp_mask
)
493 * Allocate the copy buffer
495 struct sk_buff
*n
= alloc_skb(skb
->end
- skb
->head
, gfp_mask
);
500 /* Set the data pointer */
501 skb_reserve(n
, skb
->data
- skb
->head
);
502 /* Set the tail pointer and length */
503 skb_put(n
, skb_headlen(skb
));
505 memcpy(n
->data
, skb
->data
, n
->len
);
507 n
->ip_summed
= skb
->ip_summed
;
509 n
->data_len
= skb
->data_len
;
512 if (skb_shinfo(skb
)->nr_frags
) {
515 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
516 skb_shinfo(n
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
517 get_page(skb_shinfo(n
)->frags
[i
].page
);
519 skb_shinfo(n
)->nr_frags
= i
;
522 if (skb_shinfo(skb
)->frag_list
) {
523 skb_shinfo(n
)->frag_list
= skb_shinfo(skb
)->frag_list
;
524 skb_clone_fraglist(n
);
527 copy_skb_header(n
, skb
);
533 * pskb_expand_head - reallocate header of &sk_buff
534 * @skb: buffer to reallocate
535 * @nhead: room to add at head
536 * @ntail: room to add at tail
537 * @gfp_mask: allocation priority
539 * Expands (or creates identical copy, if &nhead and &ntail are zero)
540 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
541 * reference count of 1. Returns zero in the case of success or error,
542 * if expansion failed. In the last case, &sk_buff is not changed.
544 * All the pointers pointing into skb header may change and must be
545 * reloaded after call to this function.
548 int pskb_expand_head(struct sk_buff
*skb
, int nhead
, int ntail
,
549 unsigned int __nocast gfp_mask
)
553 int size
= nhead
+ (skb
->end
- skb
->head
) + ntail
;
559 size
= SKB_DATA_ALIGN(size
);
561 data
= kmalloc(size
+ sizeof(struct skb_shared_info
), gfp_mask
);
565 /* Copy only real data... and, alas, header. This should be
566 * optimized for the cases when header is void. */
567 memcpy(data
+ nhead
, skb
->head
, skb
->tail
- skb
->head
);
568 memcpy(data
+ size
, skb
->end
, sizeof(struct skb_shared_info
));
570 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
571 get_page(skb_shinfo(skb
)->frags
[i
].page
);
573 if (skb_shinfo(skb
)->frag_list
)
574 skb_clone_fraglist(skb
);
576 skb_release_data(skb
);
578 off
= (data
+ nhead
) - skb
->head
;
581 skb
->end
= data
+ size
;
589 atomic_set(&skb_shinfo(skb
)->dataref
, 1);
596 /* Make private copy of skb with writable head and some headroom */
598 struct sk_buff
*skb_realloc_headroom(struct sk_buff
*skb
, unsigned int headroom
)
600 struct sk_buff
*skb2
;
601 int delta
= headroom
- skb_headroom(skb
);
604 skb2
= pskb_copy(skb
, GFP_ATOMIC
);
606 skb2
= skb_clone(skb
, GFP_ATOMIC
);
607 if (skb2
&& pskb_expand_head(skb2
, SKB_DATA_ALIGN(delta
), 0,
618 * skb_copy_expand - copy and expand sk_buff
619 * @skb: buffer to copy
620 * @newheadroom: new free bytes at head
621 * @newtailroom: new free bytes at tail
622 * @gfp_mask: allocation priority
624 * Make a copy of both an &sk_buff and its data and while doing so
625 * allocate additional space.
627 * This is used when the caller wishes to modify the data and needs a
628 * private copy of the data to alter as well as more space for new fields.
629 * Returns %NULL on failure or the pointer to the buffer
630 * on success. The returned buffer has a reference count of 1.
632 * You must pass %GFP_ATOMIC as the allocation priority if this function
633 * is called from an interrupt.
635 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used
636 * only by netfilter in the cases when checksum is recalculated? --ANK
638 struct sk_buff
*skb_copy_expand(const struct sk_buff
*skb
,
639 int newheadroom
, int newtailroom
,
640 unsigned int __nocast gfp_mask
)
643 * Allocate the copy buffer
645 struct sk_buff
*n
= alloc_skb(newheadroom
+ skb
->len
+ newtailroom
,
647 int head_copy_len
, head_copy_off
;
652 skb_reserve(n
, newheadroom
);
654 /* Set the tail pointer and length */
655 skb_put(n
, skb
->len
);
657 head_copy_len
= skb_headroom(skb
);
659 if (newheadroom
<= head_copy_len
)
660 head_copy_len
= newheadroom
;
662 head_copy_off
= newheadroom
- head_copy_len
;
664 /* Copy the linear header and data. */
665 if (skb_copy_bits(skb
, -head_copy_len
, n
->head
+ head_copy_off
,
666 skb
->len
+ head_copy_len
))
669 copy_skb_header(n
, skb
);
675 * skb_pad - zero pad the tail of an skb
676 * @skb: buffer to pad
679 * Ensure that a buffer is followed by a padding area that is zero
680 * filled. Used by network drivers which may DMA or transfer data
681 * beyond the buffer end onto the wire.
683 * May return NULL in out of memory cases.
686 struct sk_buff
*skb_pad(struct sk_buff
*skb
, int pad
)
688 struct sk_buff
*nskb
;
690 /* If the skbuff is non linear tailroom is always zero.. */
691 if (skb_tailroom(skb
) >= pad
) {
692 memset(skb
->data
+skb
->len
, 0, pad
);
696 nskb
= skb_copy_expand(skb
, skb_headroom(skb
), skb_tailroom(skb
) + pad
, GFP_ATOMIC
);
699 memset(nskb
->data
+nskb
->len
, 0, pad
);
703 /* Trims skb to length len. It can change skb pointers, if "realloc" is 1.
704 * If realloc==0 and trimming is impossible without change of data,
708 int ___pskb_trim(struct sk_buff
*skb
, unsigned int len
, int realloc
)
710 int offset
= skb_headlen(skb
);
711 int nfrags
= skb_shinfo(skb
)->nr_frags
;
714 for (i
= 0; i
< nfrags
; i
++) {
715 int end
= offset
+ skb_shinfo(skb
)->frags
[i
].size
;
717 if (skb_cloned(skb
)) {
720 if (pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))
724 put_page(skb_shinfo(skb
)->frags
[i
].page
);
725 skb_shinfo(skb
)->nr_frags
--;
727 skb_shinfo(skb
)->frags
[i
].size
= len
- offset
;
734 skb
->data_len
-= skb
->len
- len
;
737 if (len
<= skb_headlen(skb
)) {
740 skb
->tail
= skb
->data
+ len
;
741 if (skb_shinfo(skb
)->frag_list
&& !skb_cloned(skb
))
742 skb_drop_fraglist(skb
);
744 skb
->data_len
-= skb
->len
- len
;
753 * __pskb_pull_tail - advance tail of skb header
754 * @skb: buffer to reallocate
755 * @delta: number of bytes to advance tail
757 * The function makes a sense only on a fragmented &sk_buff,
758 * it expands header moving its tail forward and copying necessary
759 * data from fragmented part.
761 * &sk_buff MUST have reference count of 1.
763 * Returns %NULL (and &sk_buff does not change) if pull failed
764 * or value of new tail of skb in the case of success.
766 * All the pointers pointing into skb header may change and must be
767 * reloaded after call to this function.
770 /* Moves tail of skb head forward, copying data from fragmented part,
771 * when it is necessary.
772 * 1. It may fail due to malloc failure.
773 * 2. It may change skb pointers.
775 * It is pretty complicated. Luckily, it is called only in exceptional cases.
777 unsigned char *__pskb_pull_tail(struct sk_buff
*skb
, int delta
)
779 /* If skb has not enough free space at tail, get new one
780 * plus 128 bytes for future expansions. If we have enough
781 * room at tail, reallocate without expansion only if skb is cloned.
783 int i
, k
, eat
= (skb
->tail
+ delta
) - skb
->end
;
785 if (eat
> 0 || skb_cloned(skb
)) {
786 if (pskb_expand_head(skb
, 0, eat
> 0 ? eat
+ 128 : 0,
791 if (skb_copy_bits(skb
, skb_headlen(skb
), skb
->tail
, delta
))
794 /* Optimization: no fragments, no reasons to preestimate
795 * size of pulled pages. Superb.
797 if (!skb_shinfo(skb
)->frag_list
)
800 /* Estimate size of pulled pages. */
802 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
803 if (skb_shinfo(skb
)->frags
[i
].size
>= eat
)
805 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
808 /* If we need update frag list, we are in troubles.
809 * Certainly, it possible to add an offset to skb data,
810 * but taking into account that pulling is expected to
811 * be very rare operation, it is worth to fight against
812 * further bloating skb head and crucify ourselves here instead.
813 * Pure masohism, indeed. 8)8)
816 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
817 struct sk_buff
*clone
= NULL
;
818 struct sk_buff
*insp
= NULL
;
824 if (list
->len
<= eat
) {
825 /* Eaten as whole. */
830 /* Eaten partially. */
832 if (skb_shared(list
)) {
833 /* Sucks! We need to fork list. :-( */
834 clone
= skb_clone(list
, GFP_ATOMIC
);
840 /* This may be pulled without
844 if (!pskb_pull(list
, eat
)) {
853 /* Free pulled out fragments. */
854 while ((list
= skb_shinfo(skb
)->frag_list
) != insp
) {
855 skb_shinfo(skb
)->frag_list
= list
->next
;
858 /* And insert new clone at head. */
861 skb_shinfo(skb
)->frag_list
= clone
;
864 /* Success! Now we may commit changes to skb data. */
869 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
870 if (skb_shinfo(skb
)->frags
[i
].size
<= eat
) {
871 put_page(skb_shinfo(skb
)->frags
[i
].page
);
872 eat
-= skb_shinfo(skb
)->frags
[i
].size
;
874 skb_shinfo(skb
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
876 skb_shinfo(skb
)->frags
[k
].page_offset
+= eat
;
877 skb_shinfo(skb
)->frags
[k
].size
-= eat
;
883 skb_shinfo(skb
)->nr_frags
= k
;
886 skb
->data_len
-= delta
;
891 /* Copy some data bits from skb to kernel buffer. */
893 int skb_copy_bits(const struct sk_buff
*skb
, int offset
, void *to
, int len
)
896 int start
= skb_headlen(skb
);
898 if (offset
> (int)skb
->len
- len
)
902 if ((copy
= start
- offset
) > 0) {
905 memcpy(to
, skb
->data
+ offset
, copy
);
906 if ((len
-= copy
) == 0)
912 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
915 BUG_TRAP(start
<= offset
+ len
);
917 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
918 if ((copy
= end
- offset
) > 0) {
924 vaddr
= kmap_skb_frag(&skb_shinfo(skb
)->frags
[i
]);
926 vaddr
+ skb_shinfo(skb
)->frags
[i
].page_offset
+
927 offset
- start
, copy
);
928 kunmap_skb_frag(vaddr
);
930 if ((len
-= copy
) == 0)
938 if (skb_shinfo(skb
)->frag_list
) {
939 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
941 for (; list
; list
= list
->next
) {
944 BUG_TRAP(start
<= offset
+ len
);
946 end
= start
+ list
->len
;
947 if ((copy
= end
- offset
) > 0) {
950 if (skb_copy_bits(list
, offset
- start
,
953 if ((len
-= copy
) == 0)
969 * skb_store_bits - store bits from kernel buffer to skb
970 * @skb: destination buffer
971 * @offset: offset in destination
972 * @from: source buffer
973 * @len: number of bytes to copy
975 * Copy the specified number of bytes from the source buffer to the
976 * destination skb. This function handles all the messy bits of
977 * traversing fragment lists and such.
980 int skb_store_bits(const struct sk_buff
*skb
, int offset
, void *from
, int len
)
983 int start
= skb_headlen(skb
);
985 if (offset
> (int)skb
->len
- len
)
988 if ((copy
= start
- offset
) > 0) {
991 memcpy(skb
->data
+ offset
, from
, copy
);
992 if ((len
-= copy
) == 0)
998 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
999 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1002 BUG_TRAP(start
<= offset
+ len
);
1004 end
= start
+ frag
->size
;
1005 if ((copy
= end
- offset
) > 0) {
1011 vaddr
= kmap_skb_frag(frag
);
1012 memcpy(vaddr
+ frag
->page_offset
+ offset
- start
,
1014 kunmap_skb_frag(vaddr
);
1016 if ((len
-= copy
) == 0)
1024 if (skb_shinfo(skb
)->frag_list
) {
1025 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1027 for (; list
; list
= list
->next
) {
1030 BUG_TRAP(start
<= offset
+ len
);
1032 end
= start
+ list
->len
;
1033 if ((copy
= end
- offset
) > 0) {
1036 if (skb_store_bits(list
, offset
- start
,
1039 if ((len
-= copy
) == 0)
1054 EXPORT_SYMBOL(skb_store_bits
);
1056 /* Checksum skb data. */
1058 unsigned int skb_checksum(const struct sk_buff
*skb
, int offset
,
1059 int len
, unsigned int csum
)
1061 int start
= skb_headlen(skb
);
1062 int i
, copy
= start
- offset
;
1065 /* Checksum header. */
1069 csum
= csum_partial(skb
->data
+ offset
, copy
, csum
);
1070 if ((len
-= copy
) == 0)
1076 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1079 BUG_TRAP(start
<= offset
+ len
);
1081 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1082 if ((copy
= end
- offset
) > 0) {
1085 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1089 vaddr
= kmap_skb_frag(frag
);
1090 csum2
= csum_partial(vaddr
+ frag
->page_offset
+
1091 offset
- start
, copy
, 0);
1092 kunmap_skb_frag(vaddr
);
1093 csum
= csum_block_add(csum
, csum2
, pos
);
1102 if (skb_shinfo(skb
)->frag_list
) {
1103 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1105 for (; list
; list
= list
->next
) {
1108 BUG_TRAP(start
<= offset
+ len
);
1110 end
= start
+ list
->len
;
1111 if ((copy
= end
- offset
) > 0) {
1115 csum2
= skb_checksum(list
, offset
- start
,
1117 csum
= csum_block_add(csum
, csum2
, pos
);
1118 if ((len
-= copy
) == 0)
1132 /* Both of above in one bottle. */
1134 unsigned int skb_copy_and_csum_bits(const struct sk_buff
*skb
, int offset
,
1135 u8
*to
, int len
, unsigned int csum
)
1137 int start
= skb_headlen(skb
);
1138 int i
, copy
= start
- offset
;
1145 csum
= csum_partial_copy_nocheck(skb
->data
+ offset
, to
,
1147 if ((len
-= copy
) == 0)
1154 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
1157 BUG_TRAP(start
<= offset
+ len
);
1159 end
= start
+ skb_shinfo(skb
)->frags
[i
].size
;
1160 if ((copy
= end
- offset
) > 0) {
1163 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
1167 vaddr
= kmap_skb_frag(frag
);
1168 csum2
= csum_partial_copy_nocheck(vaddr
+
1172 kunmap_skb_frag(vaddr
);
1173 csum
= csum_block_add(csum
, csum2
, pos
);
1183 if (skb_shinfo(skb
)->frag_list
) {
1184 struct sk_buff
*list
= skb_shinfo(skb
)->frag_list
;
1186 for (; list
; list
= list
->next
) {
1190 BUG_TRAP(start
<= offset
+ len
);
1192 end
= start
+ list
->len
;
1193 if ((copy
= end
- offset
) > 0) {
1196 csum2
= skb_copy_and_csum_bits(list
,
1199 csum
= csum_block_add(csum
, csum2
, pos
);
1200 if ((len
-= copy
) == 0)
1214 void skb_copy_and_csum_dev(const struct sk_buff
*skb
, u8
*to
)
1219 if (skb
->ip_summed
== CHECKSUM_HW
)
1220 csstart
= skb
->h
.raw
- skb
->data
;
1222 csstart
= skb_headlen(skb
);
1224 if (csstart
> skb_headlen(skb
))
1227 memcpy(to
, skb
->data
, csstart
);
1230 if (csstart
!= skb
->len
)
1231 csum
= skb_copy_and_csum_bits(skb
, csstart
, to
+ csstart
,
1232 skb
->len
- csstart
, 0);
1234 if (skb
->ip_summed
== CHECKSUM_HW
) {
1235 long csstuff
= csstart
+ skb
->csum
;
1237 *((unsigned short *)(to
+ csstuff
)) = csum_fold(csum
);
1242 * skb_dequeue - remove from the head of the queue
1243 * @list: list to dequeue from
1245 * Remove the head of the list. The list lock is taken so the function
1246 * may be used safely with other locking list functions. The head item is
1247 * returned or %NULL if the list is empty.
1250 struct sk_buff
*skb_dequeue(struct sk_buff_head
*list
)
1252 unsigned long flags
;
1253 struct sk_buff
*result
;
1255 spin_lock_irqsave(&list
->lock
, flags
);
1256 result
= __skb_dequeue(list
);
1257 spin_unlock_irqrestore(&list
->lock
, flags
);
1262 * skb_dequeue_tail - remove from the tail of the queue
1263 * @list: list to dequeue from
1265 * Remove the tail of the list. The list lock is taken so the function
1266 * may be used safely with other locking list functions. The tail item is
1267 * returned or %NULL if the list is empty.
1269 struct sk_buff
*skb_dequeue_tail(struct sk_buff_head
*list
)
1271 unsigned long flags
;
1272 struct sk_buff
*result
;
1274 spin_lock_irqsave(&list
->lock
, flags
);
1275 result
= __skb_dequeue_tail(list
);
1276 spin_unlock_irqrestore(&list
->lock
, flags
);
1281 * skb_queue_purge - empty a list
1282 * @list: list to empty
1284 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1285 * the list and one reference dropped. This function takes the list
1286 * lock and is atomic with respect to other list locking functions.
1288 void skb_queue_purge(struct sk_buff_head
*list
)
1290 struct sk_buff
*skb
;
1291 while ((skb
= skb_dequeue(list
)) != NULL
)
1296 * skb_queue_head - queue a buffer at the list head
1297 * @list: list to use
1298 * @newsk: buffer to queue
1300 * Queue a buffer at the start of the list. This function takes the
1301 * list lock and can be used safely with other locking &sk_buff functions
1304 * A buffer cannot be placed on two lists at the same time.
1306 void skb_queue_head(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1308 unsigned long flags
;
1310 spin_lock_irqsave(&list
->lock
, flags
);
1311 __skb_queue_head(list
, newsk
);
1312 spin_unlock_irqrestore(&list
->lock
, flags
);
1316 * skb_queue_tail - queue a buffer at the list tail
1317 * @list: list to use
1318 * @newsk: buffer to queue
1320 * Queue a buffer at the tail of the list. This function takes the
1321 * list lock and can be used safely with other locking &sk_buff functions
1324 * A buffer cannot be placed on two lists at the same time.
1326 void skb_queue_tail(struct sk_buff_head
*list
, struct sk_buff
*newsk
)
1328 unsigned long flags
;
1330 spin_lock_irqsave(&list
->lock
, flags
);
1331 __skb_queue_tail(list
, newsk
);
1332 spin_unlock_irqrestore(&list
->lock
, flags
);
1336 * skb_unlink - remove a buffer from a list
1337 * @skb: buffer to remove
1338 * @list: list to use
1340 * Remove a packet from a list. The list locks are taken and this
1341 * function is atomic with respect to other list locked calls
1343 * You must know what list the SKB is on.
1345 void skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
)
1347 unsigned long flags
;
1349 spin_lock_irqsave(&list
->lock
, flags
);
1350 __skb_unlink(skb
, list
);
1351 spin_unlock_irqrestore(&list
->lock
, flags
);
1355 * skb_append - append a buffer
1356 * @old: buffer to insert after
1357 * @newsk: buffer to insert
1358 * @list: list to use
1360 * Place a packet after a given packet in a list. The list locks are taken
1361 * and this function is atomic with respect to other list locked calls.
1362 * A buffer cannot be placed on two lists at the same time.
1364 void skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1366 unsigned long flags
;
1368 spin_lock_irqsave(&list
->lock
, flags
);
1369 __skb_append(old
, newsk
, list
);
1370 spin_unlock_irqrestore(&list
->lock
, flags
);
1375 * skb_insert - insert a buffer
1376 * @old: buffer to insert before
1377 * @newsk: buffer to insert
1378 * @list: list to use
1380 * Place a packet before a given packet in a list. The list locks are
1381 * taken and this function is atomic with respect to other list locked
1384 * A buffer cannot be placed on two lists at the same time.
1386 void skb_insert(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
1388 unsigned long flags
;
1390 spin_lock_irqsave(&list
->lock
, flags
);
1391 __skb_insert(newsk
, old
->prev
, old
, list
);
1392 spin_unlock_irqrestore(&list
->lock
, flags
);
1397 * Tune the memory allocator for a new MTU size.
1399 void skb_add_mtu(int mtu
)
1401 /* Must match allocation in alloc_skb */
1402 mtu
= SKB_DATA_ALIGN(mtu
) + sizeof(struct skb_shared_info
);
1404 kmem_add_cache_size(mtu
);
1408 static inline void skb_split_inside_header(struct sk_buff
*skb
,
1409 struct sk_buff
* skb1
,
1410 const u32 len
, const int pos
)
1414 memcpy(skb_put(skb1
, pos
- len
), skb
->data
+ len
, pos
- len
);
1416 /* And move data appendix as is. */
1417 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++)
1418 skb_shinfo(skb1
)->frags
[i
] = skb_shinfo(skb
)->frags
[i
];
1420 skb_shinfo(skb1
)->nr_frags
= skb_shinfo(skb
)->nr_frags
;
1421 skb_shinfo(skb
)->nr_frags
= 0;
1422 skb1
->data_len
= skb
->data_len
;
1423 skb1
->len
+= skb1
->data_len
;
1426 skb
->tail
= skb
->data
+ len
;
1429 static inline void skb_split_no_header(struct sk_buff
*skb
,
1430 struct sk_buff
* skb1
,
1431 const u32 len
, int pos
)
1434 const int nfrags
= skb_shinfo(skb
)->nr_frags
;
1436 skb_shinfo(skb
)->nr_frags
= 0;
1437 skb1
->len
= skb1
->data_len
= skb
->len
- len
;
1439 skb
->data_len
= len
- pos
;
1441 for (i
= 0; i
< nfrags
; i
++) {
1442 int size
= skb_shinfo(skb
)->frags
[i
].size
;
1444 if (pos
+ size
> len
) {
1445 skb_shinfo(skb1
)->frags
[k
] = skb_shinfo(skb
)->frags
[i
];
1449 * We have two variants in this case:
1450 * 1. Move all the frag to the second
1451 * part, if it is possible. F.e.
1452 * this approach is mandatory for TUX,
1453 * where splitting is expensive.
1454 * 2. Split is accurately. We make this.
1456 get_page(skb_shinfo(skb
)->frags
[i
].page
);
1457 skb_shinfo(skb1
)->frags
[0].page_offset
+= len
- pos
;
1458 skb_shinfo(skb1
)->frags
[0].size
-= len
- pos
;
1459 skb_shinfo(skb
)->frags
[i
].size
= len
- pos
;
1460 skb_shinfo(skb
)->nr_frags
++;
1464 skb_shinfo(skb
)->nr_frags
++;
1467 skb_shinfo(skb1
)->nr_frags
= k
;
1471 * skb_split - Split fragmented skb to two parts at length len.
1472 * @skb: the buffer to split
1473 * @skb1: the buffer to receive the second part
1474 * @len: new length for skb
1476 void skb_split(struct sk_buff
*skb
, struct sk_buff
*skb1
, const u32 len
)
1478 int pos
= skb_headlen(skb
);
1480 if (len
< pos
) /* Split line is inside header. */
1481 skb_split_inside_header(skb
, skb1
, len
, pos
);
1482 else /* Second chunk has no header, nothing to copy. */
1483 skb_split_no_header(skb
, skb1
, len
, pos
);
1487 * skb_prepare_seq_read - Prepare a sequential read of skb data
1488 * @skb: the buffer to read
1489 * @from: lower offset of data to be read
1490 * @to: upper offset of data to be read
1491 * @st: state variable
1493 * Initializes the specified state variable. Must be called before
1494 * invoking skb_seq_read() for the first time.
1496 void skb_prepare_seq_read(struct sk_buff
*skb
, unsigned int from
,
1497 unsigned int to
, struct skb_seq_state
*st
)
1499 st
->lower_offset
= from
;
1500 st
->upper_offset
= to
;
1501 st
->root_skb
= st
->cur_skb
= skb
;
1502 st
->frag_idx
= st
->stepped_offset
= 0;
1503 st
->frag_data
= NULL
;
1507 * skb_seq_read - Sequentially read skb data
1508 * @consumed: number of bytes consumed by the caller so far
1509 * @data: destination pointer for data to be returned
1510 * @st: state variable
1512 * Reads a block of skb data at &consumed relative to the
1513 * lower offset specified to skb_prepare_seq_read(). Assigns
1514 * the head of the data block to &data and returns the length
1515 * of the block or 0 if the end of the skb data or the upper
1516 * offset has been reached.
1518 * The caller is not required to consume all of the data
1519 * returned, i.e. &consumed is typically set to the number
1520 * of bytes already consumed and the next call to
1521 * skb_seq_read() will return the remaining part of the block.
1523 * Note: The size of each block of data returned can be arbitary,
1524 * this limitation is the cost for zerocopy seqeuental
1525 * reads of potentially non linear data.
1527 * Note: Fragment lists within fragments are not implemented
1528 * at the moment, state->root_skb could be replaced with
1529 * a stack for this purpose.
1531 unsigned int skb_seq_read(unsigned int consumed
, const u8
**data
,
1532 struct skb_seq_state
*st
)
1534 unsigned int block_limit
, abs_offset
= consumed
+ st
->lower_offset
;
1537 if (unlikely(abs_offset
>= st
->upper_offset
))
1541 block_limit
= skb_headlen(st
->cur_skb
);
1543 if (abs_offset
< block_limit
) {
1544 *data
= st
->cur_skb
->data
+ abs_offset
;
1545 return block_limit
- abs_offset
;
1548 if (st
->frag_idx
== 0 && !st
->frag_data
)
1549 st
->stepped_offset
+= skb_headlen(st
->cur_skb
);
1551 while (st
->frag_idx
< skb_shinfo(st
->cur_skb
)->nr_frags
) {
1552 frag
= &skb_shinfo(st
->cur_skb
)->frags
[st
->frag_idx
];
1553 block_limit
= frag
->size
+ st
->stepped_offset
;
1555 if (abs_offset
< block_limit
) {
1557 st
->frag_data
= kmap_skb_frag(frag
);
1559 *data
= (u8
*) st
->frag_data
+ frag
->page_offset
+
1560 (abs_offset
- st
->stepped_offset
);
1562 return block_limit
- abs_offset
;
1565 if (st
->frag_data
) {
1566 kunmap_skb_frag(st
->frag_data
);
1567 st
->frag_data
= NULL
;
1571 st
->stepped_offset
+= frag
->size
;
1574 if (st
->cur_skb
->next
) {
1575 st
->cur_skb
= st
->cur_skb
->next
;
1578 } else if (st
->root_skb
== st
->cur_skb
&&
1579 skb_shinfo(st
->root_skb
)->frag_list
) {
1580 st
->cur_skb
= skb_shinfo(st
->root_skb
)->frag_list
;
1588 * skb_abort_seq_read - Abort a sequential read of skb data
1589 * @st: state variable
1591 * Must be called if skb_seq_read() was not called until it
1594 void skb_abort_seq_read(struct skb_seq_state
*st
)
1597 kunmap_skb_frag(st
->frag_data
);
1600 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
1602 static unsigned int skb_ts_get_next_block(unsigned int offset
, const u8
**text
,
1603 struct ts_config
*conf
,
1604 struct ts_state
*state
)
1606 return skb_seq_read(offset
, text
, TS_SKB_CB(state
));
1609 static void skb_ts_finish(struct ts_config
*conf
, struct ts_state
*state
)
1611 skb_abort_seq_read(TS_SKB_CB(state
));
1615 * skb_find_text - Find a text pattern in skb data
1616 * @skb: the buffer to look in
1617 * @from: search offset
1619 * @config: textsearch configuration
1620 * @state: uninitialized textsearch state variable
1622 * Finds a pattern in the skb data according to the specified
1623 * textsearch configuration. Use textsearch_next() to retrieve
1624 * subsequent occurrences of the pattern. Returns the offset
1625 * to the first occurrence or UINT_MAX if no match was found.
1627 unsigned int skb_find_text(struct sk_buff
*skb
, unsigned int from
,
1628 unsigned int to
, struct ts_config
*config
,
1629 struct ts_state
*state
)
1631 config
->get_next_block
= skb_ts_get_next_block
;
1632 config
->finish
= skb_ts_finish
;
1634 skb_prepare_seq_read(skb
, from
, to
, TS_SKB_CB(state
));
1636 return textsearch_find(config
, state
);
1639 void __init
skb_init(void)
1641 skbuff_head_cache
= kmem_cache_create("skbuff_head_cache",
1642 sizeof(struct sk_buff
),
1646 if (!skbuff_head_cache
)
1647 panic("cannot create skbuff cache");
1650 EXPORT_SYMBOL(___pskb_trim
);
1651 EXPORT_SYMBOL(__kfree_skb
);
1652 EXPORT_SYMBOL(__pskb_pull_tail
);
1653 EXPORT_SYMBOL(alloc_skb
);
1654 EXPORT_SYMBOL(pskb_copy
);
1655 EXPORT_SYMBOL(pskb_expand_head
);
1656 EXPORT_SYMBOL(skb_checksum
);
1657 EXPORT_SYMBOL(skb_clone
);
1658 EXPORT_SYMBOL(skb_clone_fraglist
);
1659 EXPORT_SYMBOL(skb_copy
);
1660 EXPORT_SYMBOL(skb_copy_and_csum_bits
);
1661 EXPORT_SYMBOL(skb_copy_and_csum_dev
);
1662 EXPORT_SYMBOL(skb_copy_bits
);
1663 EXPORT_SYMBOL(skb_copy_expand
);
1664 EXPORT_SYMBOL(skb_over_panic
);
1665 EXPORT_SYMBOL(skb_pad
);
1666 EXPORT_SYMBOL(skb_realloc_headroom
);
1667 EXPORT_SYMBOL(skb_under_panic
);
1668 EXPORT_SYMBOL(skb_dequeue
);
1669 EXPORT_SYMBOL(skb_dequeue_tail
);
1670 EXPORT_SYMBOL(skb_insert
);
1671 EXPORT_SYMBOL(skb_queue_purge
);
1672 EXPORT_SYMBOL(skb_queue_head
);
1673 EXPORT_SYMBOL(skb_queue_tail
);
1674 EXPORT_SYMBOL(skb_unlink
);
1675 EXPORT_SYMBOL(skb_append
);
1676 EXPORT_SYMBOL(skb_split
);
1677 EXPORT_SYMBOL(skb_prepare_seq_read
);
1678 EXPORT_SYMBOL(skb_seq_read
);
1679 EXPORT_SYMBOL(skb_abort_seq_read
);
1680 EXPORT_SYMBOL(skb_find_text
);
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