2 * Routines having to do with the 'struct sk_buff' memory handlers.
4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
8 * Alan Cox : Fixed the worst of the load
10 * Dave Platt : Interrupt stacking fix.
11 * Richard Kooijman : Timestamp fixes.
12 * Alan Cox : Changed buffer format.
13 * Alan Cox : destructor hook for AF_UNIX etc.
14 * Linus Torvalds : Better skb_clone.
15 * Alan Cox : Added skb_copy.
16 * Alan Cox : Added all the changed routines Linus
17 * only put in the headers
18 * Ray VanTassle : Fixed --skb->lock in free
19 * Alan Cox : skb_copy copy arp field
20 * Andi Kleen : slabified it.
21 * Robert Olsson : Removed skb_head_pool
24 * The __skb_ routines should be called with interrupts
25 * disabled, or you better be *real* sure that the operation is atomic
26 * with respect to whatever list is being frobbed (e.g. via lock_sock()
27 * or via disabling bottom half handlers, etc).
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
36 * The functions in this file will not compile correctly with gcc 2.4.x
39 #include <linux/module.h>
40 #include <linux/types.h>
41 #include <linux/kernel.h>
42 #include <linux/kmemcheck.h>
44 #include <linux/interrupt.h>
46 #include <linux/inet.h>
47 #include <linux/slab.h>
48 #include <linux/netdevice.h>
49 #ifdef CONFIG_NET_CLS_ACT
50 #include <net/pkt_sched.h>
52 #include <linux/string.h>
53 #include <linux/skbuff.h>
54 #include <linux/splice.h>
55 #include <linux/cache.h>
56 #include <linux/rtnetlink.h>
57 #include <linux/init.h>
58 #include <linux/scatterlist.h>
59 #include <linux/errqueue.h>
61 #include <net/protocol.h>
64 #include <net/checksum.h>
67 #include <asm/uaccess.h>
68 #include <asm/system.h>
69 #include <trace/events/skb.h>
73 static struct kmem_cache *skbuff_head_cache __read_mostly;
74 static struct kmem_cache *skbuff_fclone_cache __read_mostly;
76 static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
77 struct pipe_buffer *buf)
82 static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
83 struct pipe_buffer *buf)
88 static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
89 struct pipe_buffer *buf)
95 /* Pipe buffer operations for a socket. */
96 static const struct pipe_buf_operations sock_pipe_buf_ops = {
98 .map = generic_pipe_buf_map,
99 .unmap = generic_pipe_buf_unmap,
100 .confirm = generic_pipe_buf_confirm,
101 .release = sock_pipe_buf_release,
102 .steal = sock_pipe_buf_steal,
103 .get = sock_pipe_buf_get,
107 * Keep out-of-line to prevent kernel bloat.
108 * __builtin_return_address is not used because it is not always
113 * skb_over_panic - private function
118 * Out of line support code for skb_put(). Not user callable.
120 static void skb_over_panic(struct sk_buff *skb, int sz, void *here)
122 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
123 "data:%p tail:%#lx end:%#lx dev:%s\n",
124 here, skb->len, sz, skb->head, skb->data,
125 (unsigned long)skb->tail, (unsigned long)skb->end,
126 skb->dev ? skb->dev->name : "<NULL>");
131 * skb_under_panic - private function
136 * Out of line support code for skb_push(). Not user callable.
139 static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
141 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
142 "data:%p tail:%#lx end:%#lx dev:%s\n",
143 here, skb->len, sz, skb->head, skb->data,
144 (unsigned long)skb->tail, (unsigned long)skb->end,
145 skb->dev ? skb->dev->name : "<NULL>");
149 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
150 * 'private' fields and also do memory statistics to find all the
156 * __alloc_skb - allocate a network buffer
157 * @size: size to allocate
158 * @gfp_mask: allocation mask
159 * @fclone: allocate from fclone cache instead of head cache
160 * and allocate a cloned (child) skb
161 * @node: numa node to allocate memory on
163 * Allocate a new &sk_buff. The returned buffer has no headroom and a
164 * tail room of size bytes. The object has a reference count of one.
165 * The return is the buffer. On a failure the return is %NULL.
167 * Buffers may only be allocated from interrupts using a @gfp_mask of
170 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
171 int fclone, int node)
173 struct kmem_cache *cache;
174 struct skb_shared_info *shinfo;
178 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
181 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
186 size = SKB_DATA_ALIGN(size);
187 data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
191 prefetchw(data + size);
194 * Only clear those fields we need to clear, not those that we will
195 * actually initialise below. Hence, don't put any more fields after
196 * the tail pointer in struct sk_buff!
198 memset(skb, 0, offsetof(struct sk_buff, tail));
199 skb->truesize = size + sizeof(struct sk_buff);
200 atomic_set(&skb->users, 1);
203 skb_reset_tail_pointer(skb);
204 skb->end = skb->tail + size;
205 #ifdef NET_SKBUFF_DATA_USES_OFFSET
206 skb->mac_header = ~0U;
209 /* make sure we initialize shinfo sequentially */
210 shinfo = skb_shinfo(skb);
211 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
212 atomic_set(&shinfo->dataref, 1);
215 struct sk_buff *child = skb + 1;
216 atomic_t *fclone_ref = (atomic_t *) (child + 1);
218 kmemcheck_annotate_bitfield(child, flags1);
219 kmemcheck_annotate_bitfield(child, flags2);
220 skb->fclone = SKB_FCLONE_ORIG;
221 atomic_set(fclone_ref, 1);
223 child->fclone = SKB_FCLONE_UNAVAILABLE;
228 kmem_cache_free(cache, skb);
232 EXPORT_SYMBOL(__alloc_skb);
235 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
236 * @dev: network device to receive on
237 * @length: length to allocate
238 * @gfp_mask: get_free_pages mask, passed to alloc_skb
240 * Allocate a new &sk_buff and assign it a usage count of one. The
241 * buffer has unspecified headroom built in. Users should allocate
242 * the headroom they think they need without accounting for the
243 * built in space. The built in space is used for optimisations.
245 * %NULL is returned if there is no free memory.
247 struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
248 unsigned int length, gfp_t gfp_mask)
252 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
254 skb_reserve(skb, NET_SKB_PAD);
259 EXPORT_SYMBOL(__netdev_alloc_skb);
261 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
264 skb_fill_page_desc(skb, i, page, off, size);
266 skb->data_len += size;
267 skb->truesize += size;
269 EXPORT_SYMBOL(skb_add_rx_frag);
272 * dev_alloc_skb - allocate an skbuff for receiving
273 * @length: length to allocate
275 * Allocate a new &sk_buff and assign it a usage count of one. The
276 * buffer has unspecified headroom built in. Users should allocate
277 * the headroom they think they need without accounting for the
278 * built in space. The built in space is used for optimisations.
280 * %NULL is returned if there is no free memory. Although this function
281 * allocates memory it can be called from an interrupt.
283 struct sk_buff *dev_alloc_skb(unsigned int length)
286 * There is more code here than it seems:
287 * __dev_alloc_skb is an inline
289 return __dev_alloc_skb(length, GFP_ATOMIC);
291 EXPORT_SYMBOL(dev_alloc_skb);
293 static void skb_drop_list(struct sk_buff **listp)
295 struct sk_buff *list = *listp;
300 struct sk_buff *this = list;
306 static inline void skb_drop_fraglist(struct sk_buff *skb)
308 skb_drop_list(&skb_shinfo(skb)->frag_list);
311 static void skb_clone_fraglist(struct sk_buff *skb)
313 struct sk_buff *list;
315 skb_walk_frags(skb, list)
319 static void skb_release_data(struct sk_buff *skb)
322 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
323 &skb_shinfo(skb)->dataref)) {
324 if (skb_shinfo(skb)->nr_frags) {
326 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
327 put_page(skb_shinfo(skb)->frags[i].page);
330 if (skb_has_frag_list(skb))
331 skb_drop_fraglist(skb);
338 * Free an skbuff by memory without cleaning the state.
340 static void kfree_skbmem(struct sk_buff *skb)
342 struct sk_buff *other;
343 atomic_t *fclone_ref;
345 switch (skb->fclone) {
346 case SKB_FCLONE_UNAVAILABLE:
347 kmem_cache_free(skbuff_head_cache, skb);
350 case SKB_FCLONE_ORIG:
351 fclone_ref = (atomic_t *) (skb + 2);
352 if (atomic_dec_and_test(fclone_ref))
353 kmem_cache_free(skbuff_fclone_cache, skb);
356 case SKB_FCLONE_CLONE:
357 fclone_ref = (atomic_t *) (skb + 1);
360 /* The clone portion is available for
361 * fast-cloning again.
363 skb->fclone = SKB_FCLONE_UNAVAILABLE;
365 if (atomic_dec_and_test(fclone_ref))
366 kmem_cache_free(skbuff_fclone_cache, other);
371 static void skb_release_head_state(struct sk_buff *skb)
375 secpath_put(skb->sp);
377 if (skb->destructor) {
379 skb->destructor(skb);
381 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
382 nf_conntrack_put(skb->nfct);
383 nf_conntrack_put_reasm(skb->nfct_reasm);
385 #ifdef CONFIG_BRIDGE_NETFILTER
386 nf_bridge_put(skb->nf_bridge);
388 /* XXX: IS this still necessary? - JHS */
389 #ifdef CONFIG_NET_SCHED
391 #ifdef CONFIG_NET_CLS_ACT
397 /* Free everything but the sk_buff shell. */
398 static void skb_release_all(struct sk_buff *skb)
400 skb_release_head_state(skb);
401 skb_release_data(skb);
405 * __kfree_skb - private function
408 * Free an sk_buff. Release anything attached to the buffer.
409 * Clean the state. This is an internal helper function. Users should
410 * always call kfree_skb
413 void __kfree_skb(struct sk_buff *skb)
415 skb_release_all(skb);
418 EXPORT_SYMBOL(__kfree_skb);
421 * kfree_skb - free an sk_buff
422 * @skb: buffer to free
424 * Drop a reference to the buffer and free it if the usage count has
427 void kfree_skb(struct sk_buff *skb)
431 if (likely(atomic_read(&skb->users) == 1))
433 else if (likely(!atomic_dec_and_test(&skb->users)))
435 trace_kfree_skb(skb, __builtin_return_address(0));
438 EXPORT_SYMBOL(kfree_skb);
441 * consume_skb - free an skbuff
442 * @skb: buffer to free
444 * Drop a ref to the buffer and free it if the usage count has hit zero
445 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
446 * is being dropped after a failure and notes that
448 void consume_skb(struct sk_buff *skb)
452 if (likely(atomic_read(&skb->users) == 1))
454 else if (likely(!atomic_dec_and_test(&skb->users)))
458 EXPORT_SYMBOL(consume_skb);
461 * skb_recycle_check - check if skb can be reused for receive
463 * @skb_size: minimum receive buffer size
465 * Checks that the skb passed in is not shared or cloned, and
466 * that it is linear and its head portion at least as large as
467 * skb_size so that it can be recycled as a receive buffer.
468 * If these conditions are met, this function does any necessary
469 * reference count dropping and cleans up the skbuff as if it
470 * just came from __alloc_skb().
472 bool skb_recycle_check(struct sk_buff *skb, int skb_size)
474 struct skb_shared_info *shinfo;
479 if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
482 skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
483 if (skb_end_pointer(skb) - skb->head < skb_size)
486 if (skb_shared(skb) || skb_cloned(skb))
489 skb_release_head_state(skb);
491 shinfo = skb_shinfo(skb);
492 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
493 atomic_set(&shinfo->dataref, 1);
495 memset(skb, 0, offsetof(struct sk_buff, tail));
496 skb->data = skb->head + NET_SKB_PAD;
497 skb_reset_tail_pointer(skb);
501 EXPORT_SYMBOL(skb_recycle_check);
503 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
505 new->tstamp = old->tstamp;
507 new->transport_header = old->transport_header;
508 new->network_header = old->network_header;
509 new->mac_header = old->mac_header;
510 skb_dst_copy(new, old);
511 new->rxhash = old->rxhash;
513 new->sp = secpath_get(old->sp);
515 memcpy(new->cb, old->cb, sizeof(old->cb));
516 new->csum = old->csum;
517 new->local_df = old->local_df;
518 new->pkt_type = old->pkt_type;
519 new->ip_summed = old->ip_summed;
520 skb_copy_queue_mapping(new, old);
521 new->priority = old->priority;
522 new->deliver_no_wcard = old->deliver_no_wcard;
523 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
524 new->ipvs_property = old->ipvs_property;
526 new->protocol = old->protocol;
527 new->mark = old->mark;
528 new->skb_iif = old->skb_iif;
530 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
531 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
532 new->nf_trace = old->nf_trace;
534 #ifdef CONFIG_NET_SCHED
535 new->tc_index = old->tc_index;
536 #ifdef CONFIG_NET_CLS_ACT
537 new->tc_verd = old->tc_verd;
540 new->vlan_tci = old->vlan_tci;
542 skb_copy_secmark(new, old);
546 * You should not add any new code to this function. Add it to
547 * __copy_skb_header above instead.
549 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
551 #define C(x) n->x = skb->x
553 n->next = n->prev = NULL;
555 __copy_skb_header(n, skb);
560 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
563 n->destructor = NULL;
569 atomic_set(&n->users, 1);
571 atomic_inc(&(skb_shinfo(skb)->dataref));
579 * skb_morph - morph one skb into another
580 * @dst: the skb to receive the contents
581 * @src: the skb to supply the contents
583 * This is identical to skb_clone except that the target skb is
584 * supplied by the user.
586 * The target skb is returned upon exit.
588 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
590 skb_release_all(dst);
591 return __skb_clone(dst, src);
593 EXPORT_SYMBOL_GPL(skb_morph);
596 * skb_clone - duplicate an sk_buff
597 * @skb: buffer to clone
598 * @gfp_mask: allocation priority
600 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
601 * copies share the same packet data but not structure. The new
602 * buffer has a reference count of 1. If the allocation fails the
603 * function returns %NULL otherwise the new buffer is returned.
605 * If this function is called from an interrupt gfp_mask() must be
609 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
614 if (skb->fclone == SKB_FCLONE_ORIG &&
615 n->fclone == SKB_FCLONE_UNAVAILABLE) {
616 atomic_t *fclone_ref = (atomic_t *) (n + 1);
617 n->fclone = SKB_FCLONE_CLONE;
618 atomic_inc(fclone_ref);
620 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
624 kmemcheck_annotate_bitfield(n, flags1);
625 kmemcheck_annotate_bitfield(n, flags2);
626 n->fclone = SKB_FCLONE_UNAVAILABLE;
629 return __skb_clone(n, skb);
631 EXPORT_SYMBOL(skb_clone);
633 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
635 #ifndef NET_SKBUFF_DATA_USES_OFFSET
637 * Shift between the two data areas in bytes
639 unsigned long offset = new->data - old->data;
642 __copy_skb_header(new, old);
644 #ifndef NET_SKBUFF_DATA_USES_OFFSET
645 /* {transport,network,mac}_header are relative to skb->head */
646 new->transport_header += offset;
647 new->network_header += offset;
648 if (skb_mac_header_was_set(new))
649 new->mac_header += offset;
651 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
652 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
653 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
657 * skb_copy - create private copy of an sk_buff
658 * @skb: buffer to copy
659 * @gfp_mask: allocation priority
661 * Make a copy of both an &sk_buff and its data. This is used when the
662 * caller wishes to modify the data and needs a private copy of the
663 * data to alter. Returns %NULL on failure or the pointer to the buffer
664 * on success. The returned buffer has a reference count of 1.
666 * As by-product this function converts non-linear &sk_buff to linear
667 * one, so that &sk_buff becomes completely private and caller is allowed
668 * to modify all the data of returned buffer. This means that this
669 * function is not recommended for use in circumstances when only
670 * header is going to be modified. Use pskb_copy() instead.
673 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
675 int headerlen = skb_headroom(skb);
676 unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
677 struct sk_buff *n = alloc_skb(size, gfp_mask);
682 /* Set the data pointer */
683 skb_reserve(n, headerlen);
684 /* Set the tail pointer and length */
685 skb_put(n, skb->len);
687 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
690 copy_skb_header(n, skb);
693 EXPORT_SYMBOL(skb_copy);
696 * pskb_copy - create copy of an sk_buff with private head.
697 * @skb: buffer to copy
698 * @gfp_mask: allocation priority
700 * Make a copy of both an &sk_buff and part of its data, located
701 * in header. Fragmented data remain shared. This is used when
702 * the caller wishes to modify only header of &sk_buff and needs
703 * private copy of the header to alter. Returns %NULL on failure
704 * or the pointer to the buffer on success.
705 * The returned buffer has a reference count of 1.
708 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
710 unsigned int size = skb_end_pointer(skb) - skb->head;
711 struct sk_buff *n = alloc_skb(size, gfp_mask);
716 /* Set the data pointer */
717 skb_reserve(n, skb_headroom(skb));
718 /* Set the tail pointer and length */
719 skb_put(n, skb_headlen(skb));
721 skb_copy_from_linear_data(skb, n->data, n->len);
723 n->truesize += skb->data_len;
724 n->data_len = skb->data_len;
727 if (skb_shinfo(skb)->nr_frags) {
730 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
731 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
732 get_page(skb_shinfo(n)->frags[i].page);
734 skb_shinfo(n)->nr_frags = i;
737 if (skb_has_frag_list(skb)) {
738 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
739 skb_clone_fraglist(n);
742 copy_skb_header(n, skb);
746 EXPORT_SYMBOL(pskb_copy);
749 * pskb_expand_head - reallocate header of &sk_buff
750 * @skb: buffer to reallocate
751 * @nhead: room to add at head
752 * @ntail: room to add at tail
753 * @gfp_mask: allocation priority
755 * Expands (or creates identical copy, if &nhead and &ntail are zero)
756 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
757 * reference count of 1. Returns zero in the case of success or error,
758 * if expansion failed. In the last case, &sk_buff is not changed.
760 * All the pointers pointing into skb header may change and must be
761 * reloaded after call to this function.
764 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
769 int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
778 size = SKB_DATA_ALIGN(size);
780 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
784 /* Copy only real data... and, alas, header. This should be
785 * optimized for the cases when header is void.
787 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
789 memcpy((struct skb_shared_info *)(data + size),
791 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
793 /* Check if we can avoid taking references on fragments if we own
794 * the last reference on skb->head. (see skb_release_data())
799 int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
801 fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
807 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
808 get_page(skb_shinfo(skb)->frags[i].page);
810 if (skb_has_frag_list(skb))
811 skb_clone_fraglist(skb);
813 skb_release_data(skb);
815 off = (data + nhead) - skb->head;
819 #ifdef NET_SKBUFF_DATA_USES_OFFSET
823 skb->end = skb->head + size;
825 /* {transport,network,mac}_header and tail are relative to skb->head */
827 skb->transport_header += off;
828 skb->network_header += off;
829 if (skb_mac_header_was_set(skb))
830 skb->mac_header += off;
831 /* Only adjust this if it actually is csum_start rather than csum */
832 if (skb->ip_summed == CHECKSUM_PARTIAL)
833 skb->csum_start += nhead;
837 atomic_set(&skb_shinfo(skb)->dataref, 1);
843 EXPORT_SYMBOL(pskb_expand_head);
845 /* Make private copy of skb with writable head and some headroom */
847 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
849 struct sk_buff *skb2;
850 int delta = headroom - skb_headroom(skb);
853 skb2 = pskb_copy(skb, GFP_ATOMIC);
855 skb2 = skb_clone(skb, GFP_ATOMIC);
856 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
864 EXPORT_SYMBOL(skb_realloc_headroom);
867 * skb_copy_expand - copy and expand sk_buff
868 * @skb: buffer to copy
869 * @newheadroom: new free bytes at head
870 * @newtailroom: new free bytes at tail
871 * @gfp_mask: allocation priority
873 * Make a copy of both an &sk_buff and its data and while doing so
874 * allocate additional space.
876 * This is used when the caller wishes to modify the data and needs a
877 * private copy of the data to alter as well as more space for new fields.
878 * Returns %NULL on failure or the pointer to the buffer
879 * on success. The returned buffer has a reference count of 1.
881 * You must pass %GFP_ATOMIC as the allocation priority if this function
882 * is called from an interrupt.
884 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
885 int newheadroom, int newtailroom,
889 * Allocate the copy buffer
891 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
893 int oldheadroom = skb_headroom(skb);
894 int head_copy_len, head_copy_off;
900 skb_reserve(n, newheadroom);
902 /* Set the tail pointer and length */
903 skb_put(n, skb->len);
905 head_copy_len = oldheadroom;
907 if (newheadroom <= head_copy_len)
908 head_copy_len = newheadroom;
910 head_copy_off = newheadroom - head_copy_len;
912 /* Copy the linear header and data. */
913 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
914 skb->len + head_copy_len))
917 copy_skb_header(n, skb);
919 off = newheadroom - oldheadroom;
920 if (n->ip_summed == CHECKSUM_PARTIAL)
921 n->csum_start += off;
922 #ifdef NET_SKBUFF_DATA_USES_OFFSET
923 n->transport_header += off;
924 n->network_header += off;
925 if (skb_mac_header_was_set(skb))
926 n->mac_header += off;
931 EXPORT_SYMBOL(skb_copy_expand);
934 * skb_pad - zero pad the tail of an skb
935 * @skb: buffer to pad
938 * Ensure that a buffer is followed by a padding area that is zero
939 * filled. Used by network drivers which may DMA or transfer data
940 * beyond the buffer end onto the wire.
942 * May return error in out of memory cases. The skb is freed on error.
945 int skb_pad(struct sk_buff *skb, int pad)
950 /* If the skbuff is non linear tailroom is always zero.. */
951 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
952 memset(skb->data+skb->len, 0, pad);
956 ntail = skb->data_len + pad - (skb->end - skb->tail);
957 if (likely(skb_cloned(skb) || ntail > 0)) {
958 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
963 /* FIXME: The use of this function with non-linear skb's really needs
966 err = skb_linearize(skb);
970 memset(skb->data + skb->len, 0, pad);
977 EXPORT_SYMBOL(skb_pad);
980 * skb_put - add data to a buffer
981 * @skb: buffer to use
982 * @len: amount of data to add
984 * This function extends the used data area of the buffer. If this would
985 * exceed the total buffer size the kernel will panic. A pointer to the
986 * first byte of the extra data is returned.
988 unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
990 unsigned char *tmp = skb_tail_pointer(skb);
991 SKB_LINEAR_ASSERT(skb);
994 if (unlikely(skb->tail > skb->end))
995 skb_over_panic(skb, len, __builtin_return_address(0));
998 EXPORT_SYMBOL(skb_put);
1001 * skb_push - add data to the start of a buffer
1002 * @skb: buffer to use
1003 * @len: amount of data to add
1005 * This function extends the used data area of the buffer at the buffer
1006 * start. If this would exceed the total buffer headroom the kernel will
1007 * panic. A pointer to the first byte of the extra data is returned.
1009 unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1013 if (unlikely(skb->data<skb->head))
1014 skb_under_panic(skb, len, __builtin_return_address(0));
1017 EXPORT_SYMBOL(skb_push);
1020 * skb_pull - remove data from the start of a buffer
1021 * @skb: buffer to use
1022 * @len: amount of data to remove
1024 * This function removes data from the start of a buffer, returning
1025 * the memory to the headroom. A pointer to the next data in the buffer
1026 * is returned. Once the data has been pulled future pushes will overwrite
1029 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1031 return skb_pull_inline(skb, len);
1033 EXPORT_SYMBOL(skb_pull);
1036 * skb_trim - remove end from a buffer
1037 * @skb: buffer to alter
1040 * Cut the length of a buffer down by removing data from the tail. If
1041 * the buffer is already under the length specified it is not modified.
1042 * The skb must be linear.
1044 void skb_trim(struct sk_buff *skb, unsigned int len)
1047 __skb_trim(skb, len);
1049 EXPORT_SYMBOL(skb_trim);
1051 /* Trims skb to length len. It can change skb pointers.
1054 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1056 struct sk_buff **fragp;
1057 struct sk_buff *frag;
1058 int offset = skb_headlen(skb);
1059 int nfrags = skb_shinfo(skb)->nr_frags;
1063 if (skb_cloned(skb) &&
1064 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1071 for (; i < nfrags; i++) {
1072 int end = offset + skb_shinfo(skb)->frags[i].size;
1079 skb_shinfo(skb)->frags[i++].size = len - offset;
1082 skb_shinfo(skb)->nr_frags = i;
1084 for (; i < nfrags; i++)
1085 put_page(skb_shinfo(skb)->frags[i].page);
1087 if (skb_has_frag_list(skb))
1088 skb_drop_fraglist(skb);
1092 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1093 fragp = &frag->next) {
1094 int end = offset + frag->len;
1096 if (skb_shared(frag)) {
1097 struct sk_buff *nfrag;
1099 nfrag = skb_clone(frag, GFP_ATOMIC);
1100 if (unlikely(!nfrag))
1103 nfrag->next = frag->next;
1115 unlikely((err = pskb_trim(frag, len - offset))))
1119 skb_drop_list(&frag->next);
1124 if (len > skb_headlen(skb)) {
1125 skb->data_len -= skb->len - len;
1130 skb_set_tail_pointer(skb, len);
1135 EXPORT_SYMBOL(___pskb_trim);
1138 * __pskb_pull_tail - advance tail of skb header
1139 * @skb: buffer to reallocate
1140 * @delta: number of bytes to advance tail
1142 * The function makes a sense only on a fragmented &sk_buff,
1143 * it expands header moving its tail forward and copying necessary
1144 * data from fragmented part.
1146 * &sk_buff MUST have reference count of 1.
1148 * Returns %NULL (and &sk_buff does not change) if pull failed
1149 * or value of new tail of skb in the case of success.
1151 * All the pointers pointing into skb header may change and must be
1152 * reloaded after call to this function.
1155 /* Moves tail of skb head forward, copying data from fragmented part,
1156 * when it is necessary.
1157 * 1. It may fail due to malloc failure.
1158 * 2. It may change skb pointers.
1160 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1162 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1164 /* If skb has not enough free space at tail, get new one
1165 * plus 128 bytes for future expansions. If we have enough
1166 * room at tail, reallocate without expansion only if skb is cloned.
1168 int i, k, eat = (skb->tail + delta) - skb->end;
1170 if (eat > 0 || skb_cloned(skb)) {
1171 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1176 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1179 /* Optimization: no fragments, no reasons to preestimate
1180 * size of pulled pages. Superb.
1182 if (!skb_has_frag_list(skb))
1185 /* Estimate size of pulled pages. */
1187 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1188 if (skb_shinfo(skb)->frags[i].size >= eat)
1190 eat -= skb_shinfo(skb)->frags[i].size;
1193 /* If we need update frag list, we are in troubles.
1194 * Certainly, it possible to add an offset to skb data,
1195 * but taking into account that pulling is expected to
1196 * be very rare operation, it is worth to fight against
1197 * further bloating skb head and crucify ourselves here instead.
1198 * Pure masohism, indeed. 8)8)
1201 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1202 struct sk_buff *clone = NULL;
1203 struct sk_buff *insp = NULL;
1208 if (list->len <= eat) {
1209 /* Eaten as whole. */
1214 /* Eaten partially. */
1216 if (skb_shared(list)) {
1217 /* Sucks! We need to fork list. :-( */
1218 clone = skb_clone(list, GFP_ATOMIC);
1224 /* This may be pulled without
1228 if (!pskb_pull(list, eat)) {
1236 /* Free pulled out fragments. */
1237 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1238 skb_shinfo(skb)->frag_list = list->next;
1241 /* And insert new clone at head. */
1244 skb_shinfo(skb)->frag_list = clone;
1247 /* Success! Now we may commit changes to skb data. */
1252 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1253 if (skb_shinfo(skb)->frags[i].size <= eat) {
1254 put_page(skb_shinfo(skb)->frags[i].page);
1255 eat -= skb_shinfo(skb)->frags[i].size;
1257 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1259 skb_shinfo(skb)->frags[k].page_offset += eat;
1260 skb_shinfo(skb)->frags[k].size -= eat;
1266 skb_shinfo(skb)->nr_frags = k;
1269 skb->data_len -= delta;
1271 return skb_tail_pointer(skb);
1273 EXPORT_SYMBOL(__pskb_pull_tail);
1275 /* Copy some data bits from skb to kernel buffer. */
1277 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1279 int start = skb_headlen(skb);
1280 struct sk_buff *frag_iter;
1283 if (offset > (int)skb->len - len)
1287 if ((copy = start - offset) > 0) {
1290 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1291 if ((len -= copy) == 0)
1297 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1300 WARN_ON(start > offset + len);
1302 end = start + skb_shinfo(skb)->frags[i].size;
1303 if ((copy = end - offset) > 0) {
1309 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1311 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1312 offset - start, copy);
1313 kunmap_skb_frag(vaddr);
1315 if ((len -= copy) == 0)
1323 skb_walk_frags(skb, frag_iter) {
1326 WARN_ON(start > offset + len);
1328 end = start + frag_iter->len;
1329 if ((copy = end - offset) > 0) {
1332 if (skb_copy_bits(frag_iter, offset - start, to, copy))
1334 if ((len -= copy) == 0)
1347 EXPORT_SYMBOL(skb_copy_bits);
1350 * Callback from splice_to_pipe(), if we need to release some pages
1351 * at the end of the spd in case we error'ed out in filling the pipe.
1353 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1355 put_page(spd->pages[i]);
1358 static inline struct page *linear_to_page(struct page *page, unsigned int *len,
1359 unsigned int *offset,
1360 struct sk_buff *skb, struct sock *sk)
1362 struct page *p = sk->sk_sndmsg_page;
1367 p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
1371 off = sk->sk_sndmsg_off = 0;
1372 /* hold one ref to this page until it's full */
1376 off = sk->sk_sndmsg_off;
1377 mlen = PAGE_SIZE - off;
1378 if (mlen < 64 && mlen < *len) {
1383 *len = min_t(unsigned int, *len, mlen);
1386 memcpy(page_address(p) + off, page_address(page) + *offset, *len);
1387 sk->sk_sndmsg_off += *len;
1395 * Fill page/offset/length into spd, if it can hold more pages.
1397 static inline int spd_fill_page(struct splice_pipe_desc *spd,
1398 struct pipe_inode_info *pipe, struct page *page,
1399 unsigned int *len, unsigned int offset,
1400 struct sk_buff *skb, int linear,
1403 if (unlikely(spd->nr_pages == pipe->buffers))
1407 page = linear_to_page(page, len, &offset, skb, sk);
1413 spd->pages[spd->nr_pages] = page;
1414 spd->partial[spd->nr_pages].len = *len;
1415 spd->partial[spd->nr_pages].offset = offset;
1421 static inline void __segment_seek(struct page **page, unsigned int *poff,
1422 unsigned int *plen, unsigned int off)
1427 n = *poff / PAGE_SIZE;
1429 *page = nth_page(*page, n);
1431 *poff = *poff % PAGE_SIZE;
1435 static inline int __splice_segment(struct page *page, unsigned int poff,
1436 unsigned int plen, unsigned int *off,
1437 unsigned int *len, struct sk_buff *skb,
1438 struct splice_pipe_desc *spd, int linear,
1440 struct pipe_inode_info *pipe)
1445 /* skip this segment if already processed */
1451 /* ignore any bits we already processed */
1453 __segment_seek(&page, &poff, &plen, *off);
1458 unsigned int flen = min(*len, plen);
1460 /* the linear region may spread across several pages */
1461 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
1463 if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
1466 __segment_seek(&page, &poff, &plen, flen);
1469 } while (*len && plen);
1475 * Map linear and fragment data from the skb to spd. It reports failure if the
1476 * pipe is full or if we already spliced the requested length.
1478 static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1479 unsigned int *offset, unsigned int *len,
1480 struct splice_pipe_desc *spd, struct sock *sk)
1485 * map the linear part
1487 if (__splice_segment(virt_to_page(skb->data),
1488 (unsigned long) skb->data & (PAGE_SIZE - 1),
1490 offset, len, skb, spd, 1, sk, pipe))
1494 * then map the fragments
1496 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1497 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1499 if (__splice_segment(f->page, f->page_offset, f->size,
1500 offset, len, skb, spd, 0, sk, pipe))
1508 * Map data from the skb to a pipe. Should handle both the linear part,
1509 * the fragments, and the frag list. It does NOT handle frag lists within
1510 * the frag list, if such a thing exists. We'd probably need to recurse to
1511 * handle that cleanly.
1513 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1514 struct pipe_inode_info *pipe, unsigned int tlen,
1517 struct partial_page partial[PIPE_DEF_BUFFERS];
1518 struct page *pages[PIPE_DEF_BUFFERS];
1519 struct splice_pipe_desc spd = {
1523 .ops = &sock_pipe_buf_ops,
1524 .spd_release = sock_spd_release,
1526 struct sk_buff *frag_iter;
1527 struct sock *sk = skb->sk;
1530 if (splice_grow_spd(pipe, &spd))
1534 * __skb_splice_bits() only fails if the output has no room left,
1535 * so no point in going over the frag_list for the error case.
1537 if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1543 * now see if we have a frag_list to map
1545 skb_walk_frags(skb, frag_iter) {
1548 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1555 * Drop the socket lock, otherwise we have reverse
1556 * locking dependencies between sk_lock and i_mutex
1557 * here as compared to sendfile(). We enter here
1558 * with the socket lock held, and splice_to_pipe() will
1559 * grab the pipe inode lock. For sendfile() emulation,
1560 * we call into ->sendpage() with the i_mutex lock held
1561 * and networking will grab the socket lock.
1564 ret = splice_to_pipe(pipe, &spd);
1568 splice_shrink_spd(pipe, &spd);
1573 * skb_store_bits - store bits from kernel buffer to skb
1574 * @skb: destination buffer
1575 * @offset: offset in destination
1576 * @from: source buffer
1577 * @len: number of bytes to copy
1579 * Copy the specified number of bytes from the source buffer to the
1580 * destination skb. This function handles all the messy bits of
1581 * traversing fragment lists and such.
1584 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1586 int start = skb_headlen(skb);
1587 struct sk_buff *frag_iter;
1590 if (offset > (int)skb->len - len)
1593 if ((copy = start - offset) > 0) {
1596 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1597 if ((len -= copy) == 0)
1603 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1604 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1607 WARN_ON(start > offset + len);
1609 end = start + frag->size;
1610 if ((copy = end - offset) > 0) {
1616 vaddr = kmap_skb_frag(frag);
1617 memcpy(vaddr + frag->page_offset + offset - start,
1619 kunmap_skb_frag(vaddr);
1621 if ((len -= copy) == 0)
1629 skb_walk_frags(skb, frag_iter) {
1632 WARN_ON(start > offset + len);
1634 end = start + frag_iter->len;
1635 if ((copy = end - offset) > 0) {
1638 if (skb_store_bits(frag_iter, offset - start,
1641 if ((len -= copy) == 0)
1654 EXPORT_SYMBOL(skb_store_bits);
1656 /* Checksum skb data. */
1658 __wsum skb_checksum(const struct sk_buff *skb, int offset,
1659 int len, __wsum csum)
1661 int start = skb_headlen(skb);
1662 int i, copy = start - offset;
1663 struct sk_buff *frag_iter;
1666 /* Checksum header. */
1670 csum = csum_partial(skb->data + offset, copy, csum);
1671 if ((len -= copy) == 0)
1677 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1680 WARN_ON(start > offset + len);
1682 end = start + skb_shinfo(skb)->frags[i].size;
1683 if ((copy = end - offset) > 0) {
1686 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1690 vaddr = kmap_skb_frag(frag);
1691 csum2 = csum_partial(vaddr + frag->page_offset +
1692 offset - start, copy, 0);
1693 kunmap_skb_frag(vaddr);
1694 csum = csum_block_add(csum, csum2, pos);
1703 skb_walk_frags(skb, frag_iter) {
1706 WARN_ON(start > offset + len);
1708 end = start + frag_iter->len;
1709 if ((copy = end - offset) > 0) {
1713 csum2 = skb_checksum(frag_iter, offset - start,
1715 csum = csum_block_add(csum, csum2, pos);
1716 if ((len -= copy) == 0)
1727 EXPORT_SYMBOL(skb_checksum);
1729 /* Both of above in one bottle. */
1731 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1732 u8 *to, int len, __wsum csum)
1734 int start = skb_headlen(skb);
1735 int i, copy = start - offset;
1736 struct sk_buff *frag_iter;
1743 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1745 if ((len -= copy) == 0)
1752 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1755 WARN_ON(start > offset + len);
1757 end = start + skb_shinfo(skb)->frags[i].size;
1758 if ((copy = end - offset) > 0) {
1761 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1765 vaddr = kmap_skb_frag(frag);
1766 csum2 = csum_partial_copy_nocheck(vaddr +
1770 kunmap_skb_frag(vaddr);
1771 csum = csum_block_add(csum, csum2, pos);
1781 skb_walk_frags(skb, frag_iter) {
1785 WARN_ON(start > offset + len);
1787 end = start + frag_iter->len;
1788 if ((copy = end - offset) > 0) {
1791 csum2 = skb_copy_and_csum_bits(frag_iter,
1794 csum = csum_block_add(csum, csum2, pos);
1795 if ((len -= copy) == 0)
1806 EXPORT_SYMBOL(skb_copy_and_csum_bits);
1808 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1813 if (skb->ip_summed == CHECKSUM_PARTIAL)
1814 csstart = skb->csum_start - skb_headroom(skb);
1816 csstart = skb_headlen(skb);
1818 BUG_ON(csstart > skb_headlen(skb));
1820 skb_copy_from_linear_data(skb, to, csstart);
1823 if (csstart != skb->len)
1824 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1825 skb->len - csstart, 0);
1827 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1828 long csstuff = csstart + skb->csum_offset;
1830 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
1833 EXPORT_SYMBOL(skb_copy_and_csum_dev);
1836 * skb_dequeue - remove from the head of the queue
1837 * @list: list to dequeue from
1839 * Remove the head of the list. The list lock is taken so the function
1840 * may be used safely with other locking list functions. The head item is
1841 * returned or %NULL if the list is empty.
1844 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1846 unsigned long flags;
1847 struct sk_buff *result;
1849 spin_lock_irqsave(&list->lock, flags);
1850 result = __skb_dequeue(list);
1851 spin_unlock_irqrestore(&list->lock, flags);
1854 EXPORT_SYMBOL(skb_dequeue);
1857 * skb_dequeue_tail - remove from the tail of the queue
1858 * @list: list to dequeue from
1860 * Remove the tail of the list. The list lock is taken so the function
1861 * may be used safely with other locking list functions. The tail item is
1862 * returned or %NULL if the list is empty.
1864 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1866 unsigned long flags;
1867 struct sk_buff *result;
1869 spin_lock_irqsave(&list->lock, flags);
1870 result = __skb_dequeue_tail(list);
1871 spin_unlock_irqrestore(&list->lock, flags);
1874 EXPORT_SYMBOL(skb_dequeue_tail);
1877 * skb_queue_purge - empty a list
1878 * @list: list to empty
1880 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1881 * the list and one reference dropped. This function takes the list
1882 * lock and is atomic with respect to other list locking functions.
1884 void skb_queue_purge(struct sk_buff_head *list)
1886 struct sk_buff *skb;
1887 while ((skb = skb_dequeue(list)) != NULL)
1890 EXPORT_SYMBOL(skb_queue_purge);
1893 * skb_queue_head - queue a buffer at the list head
1894 * @list: list to use
1895 * @newsk: buffer to queue
1897 * Queue a buffer at the start of the list. This function takes the
1898 * list lock and can be used safely with other locking &sk_buff functions
1901 * A buffer cannot be placed on two lists at the same time.
1903 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
1905 unsigned long flags;
1907 spin_lock_irqsave(&list->lock, flags);
1908 __skb_queue_head(list, newsk);
1909 spin_unlock_irqrestore(&list->lock, flags);
1911 EXPORT_SYMBOL(skb_queue_head);
1914 * skb_queue_tail - queue a buffer at the list tail
1915 * @list: list to use
1916 * @newsk: buffer to queue
1918 * Queue a buffer at the tail of the list. This function takes the
1919 * list lock and can be used safely with other locking &sk_buff functions
1922 * A buffer cannot be placed on two lists at the same time.
1924 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
1926 unsigned long flags;
1928 spin_lock_irqsave(&list->lock, flags);
1929 __skb_queue_tail(list, newsk);
1930 spin_unlock_irqrestore(&list->lock, flags);
1932 EXPORT_SYMBOL(skb_queue_tail);
1935 * skb_unlink - remove a buffer from a list
1936 * @skb: buffer to remove
1937 * @list: list to use
1939 * Remove a packet from a list. The list locks are taken and this
1940 * function is atomic with respect to other list locked calls
1942 * You must know what list the SKB is on.
1944 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1946 unsigned long flags;
1948 spin_lock_irqsave(&list->lock, flags);
1949 __skb_unlink(skb, list);
1950 spin_unlock_irqrestore(&list->lock, flags);
1952 EXPORT_SYMBOL(skb_unlink);
1955 * skb_append - append a buffer
1956 * @old: buffer to insert after
1957 * @newsk: buffer to insert
1958 * @list: list to use
1960 * Place a packet after a given packet in a list. The list locks are taken
1961 * and this function is atomic with respect to other list locked calls.
1962 * A buffer cannot be placed on two lists at the same time.
1964 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1966 unsigned long flags;
1968 spin_lock_irqsave(&list->lock, flags);
1969 __skb_queue_after(list, old, newsk);
1970 spin_unlock_irqrestore(&list->lock, flags);
1972 EXPORT_SYMBOL(skb_append);
1975 * skb_insert - insert a buffer
1976 * @old: buffer to insert before
1977 * @newsk: buffer to insert
1978 * @list: list to use
1980 * Place a packet before a given packet in a list. The list locks are
1981 * taken and this function is atomic with respect to other list locked
1984 * A buffer cannot be placed on two lists at the same time.
1986 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
1988 unsigned long flags;
1990 spin_lock_irqsave(&list->lock, flags);
1991 __skb_insert(newsk, old->prev, old, list);
1992 spin_unlock_irqrestore(&list->lock, flags);
1994 EXPORT_SYMBOL(skb_insert);
1996 static inline void skb_split_inside_header(struct sk_buff *skb,
1997 struct sk_buff* skb1,
1998 const u32 len, const int pos)
2002 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2004 /* And move data appendix as is. */
2005 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2006 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2008 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2009 skb_shinfo(skb)->nr_frags = 0;
2010 skb1->data_len = skb->data_len;
2011 skb1->len += skb1->data_len;
2014 skb_set_tail_pointer(skb, len);
2017 static inline void skb_split_no_header(struct sk_buff *skb,
2018 struct sk_buff* skb1,
2019 const u32 len, int pos)
2022 const int nfrags = skb_shinfo(skb)->nr_frags;
2024 skb_shinfo(skb)->nr_frags = 0;
2025 skb1->len = skb1->data_len = skb->len - len;
2027 skb->data_len = len - pos;
2029 for (i = 0; i < nfrags; i++) {
2030 int size = skb_shinfo(skb)->frags[i].size;
2032 if (pos + size > len) {
2033 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2037 * We have two variants in this case:
2038 * 1. Move all the frag to the second
2039 * part, if it is possible. F.e.
2040 * this approach is mandatory for TUX,
2041 * where splitting is expensive.
2042 * 2. Split is accurately. We make this.
2044 get_page(skb_shinfo(skb)->frags[i].page);
2045 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2046 skb_shinfo(skb1)->frags[0].size -= len - pos;
2047 skb_shinfo(skb)->frags[i].size = len - pos;
2048 skb_shinfo(skb)->nr_frags++;
2052 skb_shinfo(skb)->nr_frags++;
2055 skb_shinfo(skb1)->nr_frags = k;
2059 * skb_split - Split fragmented skb to two parts at length len.
2060 * @skb: the buffer to split
2061 * @skb1: the buffer to receive the second part
2062 * @len: new length for skb
2064 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2066 int pos = skb_headlen(skb);
2068 if (len < pos) /* Split line is inside header. */
2069 skb_split_inside_header(skb, skb1, len, pos);
2070 else /* Second chunk has no header, nothing to copy. */
2071 skb_split_no_header(skb, skb1, len, pos);
2073 EXPORT_SYMBOL(skb_split);
2075 /* Shifting from/to a cloned skb is a no-go.
2077 * Caller cannot keep skb_shinfo related pointers past calling here!
2079 static int skb_prepare_for_shift(struct sk_buff *skb)
2081 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2085 * skb_shift - Shifts paged data partially from skb to another
2086 * @tgt: buffer into which tail data gets added
2087 * @skb: buffer from which the paged data comes from
2088 * @shiftlen: shift up to this many bytes
2090 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2091 * the length of the skb, from tgt to skb. Returns number bytes shifted.
2092 * It's up to caller to free skb if everything was shifted.
2094 * If @tgt runs out of frags, the whole operation is aborted.
2096 * Skb cannot include anything else but paged data while tgt is allowed
2097 * to have non-paged data as well.
2099 * TODO: full sized shift could be optimized but that would need
2100 * specialized skb free'er to handle frags without up-to-date nr_frags.
2102 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2104 int from, to, merge, todo;
2105 struct skb_frag_struct *fragfrom, *fragto;
2107 BUG_ON(shiftlen > skb->len);
2108 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */
2112 to = skb_shinfo(tgt)->nr_frags;
2113 fragfrom = &skb_shinfo(skb)->frags[from];
2115 /* Actual merge is delayed until the point when we know we can
2116 * commit all, so that we don't have to undo partial changes
2119 !skb_can_coalesce(tgt, to, fragfrom->page, fragfrom->page_offset)) {
2124 todo -= fragfrom->size;
2126 if (skb_prepare_for_shift(skb) ||
2127 skb_prepare_for_shift(tgt))
2130 /* All previous frag pointers might be stale! */
2131 fragfrom = &skb_shinfo(skb)->frags[from];
2132 fragto = &skb_shinfo(tgt)->frags[merge];
2134 fragto->size += shiftlen;
2135 fragfrom->size -= shiftlen;
2136 fragfrom->page_offset += shiftlen;
2144 /* Skip full, not-fitting skb to avoid expensive operations */
2145 if ((shiftlen == skb->len) &&
2146 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2149 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2152 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2153 if (to == MAX_SKB_FRAGS)
2156 fragfrom = &skb_shinfo(skb)->frags[from];
2157 fragto = &skb_shinfo(tgt)->frags[to];
2159 if (todo >= fragfrom->size) {
2160 *fragto = *fragfrom;
2161 todo -= fragfrom->size;
2166 get_page(fragfrom->page);
2167 fragto->page = fragfrom->page;
2168 fragto->page_offset = fragfrom->page_offset;
2169 fragto->size = todo;
2171 fragfrom->page_offset += todo;
2172 fragfrom->size -= todo;
2180 /* Ready to "commit" this state change to tgt */
2181 skb_shinfo(tgt)->nr_frags = to;
2184 fragfrom = &skb_shinfo(skb)->frags[0];
2185 fragto = &skb_shinfo(tgt)->frags[merge];
2187 fragto->size += fragfrom->size;
2188 put_page(fragfrom->page);
2191 /* Reposition in the original skb */
2193 while (from < skb_shinfo(skb)->nr_frags)
2194 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2195 skb_shinfo(skb)->nr_frags = to;
2197 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2200 /* Most likely the tgt won't ever need its checksum anymore, skb on
2201 * the other hand might need it if it needs to be resent
2203 tgt->ip_summed = CHECKSUM_PARTIAL;
2204 skb->ip_summed = CHECKSUM_PARTIAL;
2206 /* Yak, is it really working this way? Some helper please? */
2207 skb->len -= shiftlen;
2208 skb->data_len -= shiftlen;
2209 skb->truesize -= shiftlen;
2210 tgt->len += shiftlen;
2211 tgt->data_len += shiftlen;
2212 tgt->truesize += shiftlen;
2218 * skb_prepare_seq_read - Prepare a sequential read of skb data
2219 * @skb: the buffer to read
2220 * @from: lower offset of data to be read
2221 * @to: upper offset of data to be read
2222 * @st: state variable
2224 * Initializes the specified state variable. Must be called before
2225 * invoking skb_seq_read() for the first time.
2227 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2228 unsigned int to, struct skb_seq_state *st)
2230 st->lower_offset = from;
2231 st->upper_offset = to;
2232 st->root_skb = st->cur_skb = skb;
2233 st->frag_idx = st->stepped_offset = 0;
2234 st->frag_data = NULL;
2236 EXPORT_SYMBOL(skb_prepare_seq_read);
2239 * skb_seq_read - Sequentially read skb data
2240 * @consumed: number of bytes consumed by the caller so far
2241 * @data: destination pointer for data to be returned
2242 * @st: state variable
2244 * Reads a block of skb data at &consumed relative to the
2245 * lower offset specified to skb_prepare_seq_read(). Assigns
2246 * the head of the data block to &data and returns the length
2247 * of the block or 0 if the end of the skb data or the upper
2248 * offset has been reached.
2250 * The caller is not required to consume all of the data
2251 * returned, i.e. &consumed is typically set to the number
2252 * of bytes already consumed and the next call to
2253 * skb_seq_read() will return the remaining part of the block.
2255 * Note 1: The size of each block of data returned can be arbitary,
2256 * this limitation is the cost for zerocopy seqeuental
2257 * reads of potentially non linear data.
2259 * Note 2: Fragment lists within fragments are not implemented
2260 * at the moment, state->root_skb could be replaced with
2261 * a stack for this purpose.
2263 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2264 struct skb_seq_state *st)
2266 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2269 if (unlikely(abs_offset >= st->upper_offset))
2273 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2275 if (abs_offset < block_limit && !st->frag_data) {
2276 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2277 return block_limit - abs_offset;
2280 if (st->frag_idx == 0 && !st->frag_data)
2281 st->stepped_offset += skb_headlen(st->cur_skb);
2283 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2284 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2285 block_limit = frag->size + st->stepped_offset;
2287 if (abs_offset < block_limit) {
2289 st->frag_data = kmap_skb_frag(frag);
2291 *data = (u8 *) st->frag_data + frag->page_offset +
2292 (abs_offset - st->stepped_offset);
2294 return block_limit - abs_offset;
2297 if (st->frag_data) {
2298 kunmap_skb_frag(st->frag_data);
2299 st->frag_data = NULL;
2303 st->stepped_offset += frag->size;
2306 if (st->frag_data) {
2307 kunmap_skb_frag(st->frag_data);
2308 st->frag_data = NULL;
2311 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2312 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2315 } else if (st->cur_skb->next) {
2316 st->cur_skb = st->cur_skb->next;
2323 EXPORT_SYMBOL(skb_seq_read);
2326 * skb_abort_seq_read - Abort a sequential read of skb data
2327 * @st: state variable
2329 * Must be called if skb_seq_read() was not called until it
2332 void skb_abort_seq_read(struct skb_seq_state *st)
2335 kunmap_skb_frag(st->frag_data);
2337 EXPORT_SYMBOL(skb_abort_seq_read);
2339 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2341 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2342 struct ts_config *conf,
2343 struct ts_state *state)
2345 return skb_seq_read(offset, text, TS_SKB_CB(state));
2348 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2350 skb_abort_seq_read(TS_SKB_CB(state));
2354 * skb_find_text - Find a text pattern in skb data
2355 * @skb: the buffer to look in
2356 * @from: search offset
2358 * @config: textsearch configuration
2359 * @state: uninitialized textsearch state variable
2361 * Finds a pattern in the skb data according to the specified
2362 * textsearch configuration. Use textsearch_next() to retrieve
2363 * subsequent occurrences of the pattern. Returns the offset
2364 * to the first occurrence or UINT_MAX if no match was found.
2366 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2367 unsigned int to, struct ts_config *config,
2368 struct ts_state *state)
2372 config->get_next_block = skb_ts_get_next_block;
2373 config->finish = skb_ts_finish;
2375 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2377 ret = textsearch_find(config, state);
2378 return (ret <= to - from ? ret : UINT_MAX);
2380 EXPORT_SYMBOL(skb_find_text);
2383 * skb_append_datato_frags: - append the user data to a skb
2384 * @sk: sock structure
2385 * @skb: skb structure to be appened with user data.
2386 * @getfrag: call back function to be used for getting the user data
2387 * @from: pointer to user message iov
2388 * @length: length of the iov message
2390 * Description: This procedure append the user data in the fragment part
2391 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2393 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2394 int (*getfrag)(void *from, char *to, int offset,
2395 int len, int odd, struct sk_buff *skb),
2396 void *from, int length)
2399 skb_frag_t *frag = NULL;
2400 struct page *page = NULL;
2406 /* Return error if we don't have space for new frag */
2407 frg_cnt = skb_shinfo(skb)->nr_frags;
2408 if (frg_cnt >= MAX_SKB_FRAGS)
2411 /* allocate a new page for next frag */
2412 page = alloc_pages(sk->sk_allocation, 0);
2414 /* If alloc_page fails just return failure and caller will
2415 * free previous allocated pages by doing kfree_skb()
2420 /* initialize the next frag */
2421 sk->sk_sndmsg_page = page;
2422 sk->sk_sndmsg_off = 0;
2423 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
2424 skb->truesize += PAGE_SIZE;
2425 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
2427 /* get the new initialized frag */
2428 frg_cnt = skb_shinfo(skb)->nr_frags;
2429 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
2431 /* copy the user data to page */
2432 left = PAGE_SIZE - frag->page_offset;
2433 copy = (length > left)? left : length;
2435 ret = getfrag(from, (page_address(frag->page) +
2436 frag->page_offset + frag->size),
2437 offset, copy, 0, skb);
2441 /* copy was successful so update the size parameters */
2442 sk->sk_sndmsg_off += copy;
2445 skb->data_len += copy;
2449 } while (length > 0);
2453 EXPORT_SYMBOL(skb_append_datato_frags);
2456 * skb_pull_rcsum - pull skb and update receive checksum
2457 * @skb: buffer to update
2458 * @len: length of data pulled
2460 * This function performs an skb_pull on the packet and updates
2461 * the CHECKSUM_COMPLETE checksum. It should be used on
2462 * receive path processing instead of skb_pull unless you know
2463 * that the checksum difference is zero (e.g., a valid IP header)
2464 * or you are setting ip_summed to CHECKSUM_NONE.
2466 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2468 BUG_ON(len > skb->len);
2470 BUG_ON(skb->len < skb->data_len);
2471 skb_postpull_rcsum(skb, skb->data, len);
2472 return skb->data += len;
2474 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2477 * skb_segment - Perform protocol segmentation on skb.
2478 * @skb: buffer to segment
2479 * @features: features for the output path (see dev->features)
2481 * This function performs segmentation on the given skb. It returns
2482 * a pointer to the first in a list of new skbs for the segments.
2483 * In case of error it returns ERR_PTR(err).
2485 struct sk_buff *skb_segment(struct sk_buff *skb, int features)
2487 struct sk_buff *segs = NULL;
2488 struct sk_buff *tail = NULL;
2489 struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
2490 unsigned int mss = skb_shinfo(skb)->gso_size;
2491 unsigned int doffset = skb->data - skb_mac_header(skb);
2492 unsigned int offset = doffset;
2493 unsigned int headroom;
2495 int sg = features & NETIF_F_SG;
2496 int nfrags = skb_shinfo(skb)->nr_frags;
2501 __skb_push(skb, doffset);
2502 headroom = skb_headroom(skb);
2503 pos = skb_headlen(skb);
2506 struct sk_buff *nskb;
2511 len = skb->len - offset;
2515 hsize = skb_headlen(skb) - offset;
2518 if (hsize > len || !sg)
2521 if (!hsize && i >= nfrags) {
2522 BUG_ON(fskb->len != len);
2525 nskb = skb_clone(fskb, GFP_ATOMIC);
2528 if (unlikely(!nskb))
2531 hsize = skb_end_pointer(nskb) - nskb->head;
2532 if (skb_cow_head(nskb, doffset + headroom)) {
2537 nskb->truesize += skb_end_pointer(nskb) - nskb->head -
2539 skb_release_head_state(nskb);
2540 __skb_push(nskb, doffset);
2542 nskb = alloc_skb(hsize + doffset + headroom,
2545 if (unlikely(!nskb))
2548 skb_reserve(nskb, headroom);
2549 __skb_put(nskb, doffset);
2558 __copy_skb_header(nskb, skb);
2559 nskb->mac_len = skb->mac_len;
2561 /* nskb and skb might have different headroom */
2562 if (nskb->ip_summed == CHECKSUM_PARTIAL)
2563 nskb->csum_start += skb_headroom(nskb) - headroom;
2565 skb_reset_mac_header(nskb);
2566 skb_set_network_header(nskb, skb->mac_len);
2567 nskb->transport_header = (nskb->network_header +
2568 skb_network_header_len(skb));
2569 skb_copy_from_linear_data(skb, nskb->data, doffset);
2571 if (fskb != skb_shinfo(skb)->frag_list)
2575 nskb->ip_summed = CHECKSUM_NONE;
2576 nskb->csum = skb_copy_and_csum_bits(skb, offset,
2582 frag = skb_shinfo(nskb)->frags;
2584 skb_copy_from_linear_data_offset(skb, offset,
2585 skb_put(nskb, hsize), hsize);
2587 while (pos < offset + len && i < nfrags) {
2588 *frag = skb_shinfo(skb)->frags[i];
2589 get_page(frag->page);
2593 frag->page_offset += offset - pos;
2594 frag->size -= offset - pos;
2597 skb_shinfo(nskb)->nr_frags++;
2599 if (pos + size <= offset + len) {
2603 frag->size -= pos + size - (offset + len);
2610 if (pos < offset + len) {
2611 struct sk_buff *fskb2 = fskb;
2613 BUG_ON(pos + fskb->len != offset + len);
2619 fskb2 = skb_clone(fskb2, GFP_ATOMIC);
2625 SKB_FRAG_ASSERT(nskb);
2626 skb_shinfo(nskb)->frag_list = fskb2;
2630 nskb->data_len = len - hsize;
2631 nskb->len += nskb->data_len;
2632 nskb->truesize += nskb->data_len;
2633 } while ((offset += len) < skb->len);
2638 while ((skb = segs)) {
2642 return ERR_PTR(err);
2644 EXPORT_SYMBOL_GPL(skb_segment);
2646 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2648 struct sk_buff *p = *head;
2649 struct sk_buff *nskb;
2650 struct skb_shared_info *skbinfo = skb_shinfo(skb);
2651 struct skb_shared_info *pinfo = skb_shinfo(p);
2652 unsigned int headroom;
2653 unsigned int len = skb_gro_len(skb);
2654 unsigned int offset = skb_gro_offset(skb);
2655 unsigned int headlen = skb_headlen(skb);
2657 if (p->len + len >= 65536)
2660 if (pinfo->frag_list)
2662 else if (headlen <= offset) {
2665 int i = skbinfo->nr_frags;
2666 int nr_frags = pinfo->nr_frags + i;
2670 if (nr_frags > MAX_SKB_FRAGS)
2673 pinfo->nr_frags = nr_frags;
2674 skbinfo->nr_frags = 0;
2676 frag = pinfo->frags + nr_frags;
2677 frag2 = skbinfo->frags + i;
2682 frag->page_offset += offset;
2683 frag->size -= offset;
2685 skb->truesize -= skb->data_len;
2686 skb->len -= skb->data_len;
2689 NAPI_GRO_CB(skb)->free = 1;
2691 } else if (skb_gro_len(p) != pinfo->gso_size)
2694 headroom = skb_headroom(p);
2695 nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
2696 if (unlikely(!nskb))
2699 __copy_skb_header(nskb, p);
2700 nskb->mac_len = p->mac_len;
2702 skb_reserve(nskb, headroom);
2703 __skb_put(nskb, skb_gro_offset(p));
2705 skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
2706 skb_set_network_header(nskb, skb_network_offset(p));
2707 skb_set_transport_header(nskb, skb_transport_offset(p));
2709 __skb_pull(p, skb_gro_offset(p));
2710 memcpy(skb_mac_header(nskb), skb_mac_header(p),
2711 p->data - skb_mac_header(p));
2713 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
2714 skb_shinfo(nskb)->frag_list = p;
2715 skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2716 pinfo->gso_size = 0;
2717 skb_header_release(p);
2720 nskb->data_len += p->len;
2721 nskb->truesize += p->len;
2722 nskb->len += p->len;
2725 nskb->next = p->next;
2731 if (offset > headlen) {
2732 skbinfo->frags[0].page_offset += offset - headlen;
2733 skbinfo->frags[0].size -= offset - headlen;
2737 __skb_pull(skb, offset);
2739 p->prev->next = skb;
2741 skb_header_release(skb);
2744 NAPI_GRO_CB(p)->count++;
2749 NAPI_GRO_CB(skb)->same_flow = 1;
2752 EXPORT_SYMBOL_GPL(skb_gro_receive);
2754 void __init skb_init(void)
2756 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
2757 sizeof(struct sk_buff),
2759 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2761 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2762 (2*sizeof(struct sk_buff)) +
2765 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2770 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2771 * @skb: Socket buffer containing the buffers to be mapped
2772 * @sg: The scatter-gather list to map into
2773 * @offset: The offset into the buffer's contents to start mapping
2774 * @len: Length of buffer space to be mapped
2776 * Fill the specified scatter-gather list with mappings/pointers into a
2777 * region of the buffer space attached to a socket buffer.
2780 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2782 int start = skb_headlen(skb);
2783 int i, copy = start - offset;
2784 struct sk_buff *frag_iter;
2790 sg_set_buf(sg, skb->data + offset, copy);
2792 if ((len -= copy) == 0)
2797 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2800 WARN_ON(start > offset + len);
2802 end = start + skb_shinfo(skb)->frags[i].size;
2803 if ((copy = end - offset) > 0) {
2804 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2808 sg_set_page(&sg[elt], frag->page, copy,
2809 frag->page_offset+offset-start);
2818 skb_walk_frags(skb, frag_iter) {
2821 WARN_ON(start > offset + len);
2823 end = start + frag_iter->len;
2824 if ((copy = end - offset) > 0) {
2827 elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
2829 if ((len -= copy) == 0)
2839 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2841 int nsg = __skb_to_sgvec(skb, sg, offset, len);
2843 sg_mark_end(&sg[nsg - 1]);
2847 EXPORT_SYMBOL_GPL(skb_to_sgvec);
2850 * skb_cow_data - Check that a socket buffer's data buffers are writable
2851 * @skb: The socket buffer to check.
2852 * @tailbits: Amount of trailing space to be added
2853 * @trailer: Returned pointer to the skb where the @tailbits space begins
2855 * Make sure that the data buffers attached to a socket buffer are
2856 * writable. If they are not, private copies are made of the data buffers
2857 * and the socket buffer is set to use these instead.
2859 * If @tailbits is given, make sure that there is space to write @tailbits
2860 * bytes of data beyond current end of socket buffer. @trailer will be
2861 * set to point to the skb in which this space begins.
2863 * The number of scatterlist elements required to completely map the
2864 * COW'd and extended socket buffer will be returned.
2866 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
2870 struct sk_buff *skb1, **skb_p;
2872 /* If skb is cloned or its head is paged, reallocate
2873 * head pulling out all the pages (pages are considered not writable
2874 * at the moment even if they are anonymous).
2876 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
2877 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
2880 /* Easy case. Most of packets will go this way. */
2881 if (!skb_has_frag_list(skb)) {
2882 /* A little of trouble, not enough of space for trailer.
2883 * This should not happen, when stack is tuned to generate
2884 * good frames. OK, on miss we reallocate and reserve even more
2885 * space, 128 bytes is fair. */
2887 if (skb_tailroom(skb) < tailbits &&
2888 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
2896 /* Misery. We are in troubles, going to mincer fragments... */
2899 skb_p = &skb_shinfo(skb)->frag_list;
2902 while ((skb1 = *skb_p) != NULL) {
2905 /* The fragment is partially pulled by someone,
2906 * this can happen on input. Copy it and everything
2909 if (skb_shared(skb1))
2912 /* If the skb is the last, worry about trailer. */
2914 if (skb1->next == NULL && tailbits) {
2915 if (skb_shinfo(skb1)->nr_frags ||
2916 skb_has_frag_list(skb1) ||
2917 skb_tailroom(skb1) < tailbits)
2918 ntail = tailbits + 128;
2924 skb_shinfo(skb1)->nr_frags ||
2925 skb_has_frag_list(skb1)) {
2926 struct sk_buff *skb2;
2928 /* Fuck, we are miserable poor guys... */
2930 skb2 = skb_copy(skb1, GFP_ATOMIC);
2932 skb2 = skb_copy_expand(skb1,
2936 if (unlikely(skb2 == NULL))
2940 skb_set_owner_w(skb2, skb1->sk);
2942 /* Looking around. Are we still alive?
2943 * OK, link new skb, drop old one */
2945 skb2->next = skb1->next;
2952 skb_p = &skb1->next;
2957 EXPORT_SYMBOL_GPL(skb_cow_data);
2959 static void sock_rmem_free(struct sk_buff *skb)
2961 struct sock *sk = skb->sk;
2963 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
2967 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
2969 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
2971 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
2972 (unsigned)sk->sk_rcvbuf)
2977 skb->destructor = sock_rmem_free;
2978 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
2980 skb_queue_tail(&sk->sk_error_queue, skb);
2981 if (!sock_flag(sk, SOCK_DEAD))
2982 sk->sk_data_ready(sk, skb->len);
2985 EXPORT_SYMBOL(sock_queue_err_skb);
2987 void skb_tstamp_tx(struct sk_buff *orig_skb,
2988 struct skb_shared_hwtstamps *hwtstamps)
2990 struct sock *sk = orig_skb->sk;
2991 struct sock_exterr_skb *serr;
2992 struct sk_buff *skb;
2998 skb = skb_clone(orig_skb, GFP_ATOMIC);
3003 *skb_hwtstamps(skb) =
3007 * no hardware time stamps available,
3008 * so keep the shared tx_flags and only
3009 * store software time stamp
3011 skb->tstamp = ktime_get_real();
3014 serr = SKB_EXT_ERR(skb);
3015 memset(serr, 0, sizeof(*serr));
3016 serr->ee.ee_errno = ENOMSG;
3017 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3019 err = sock_queue_err_skb(sk, skb);
3024 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3028 * skb_partial_csum_set - set up and verify partial csum values for packet
3029 * @skb: the skb to set
3030 * @start: the number of bytes after skb->data to start checksumming.
3031 * @off: the offset from start to place the checksum.
3033 * For untrusted partially-checksummed packets, we need to make sure the values
3034 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3036 * This function checks and sets those values and skb->ip_summed: if this
3037 * returns false you should drop the packet.
3039 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3041 if (unlikely(start > skb_headlen(skb)) ||
3042 unlikely((int)start + off > skb_headlen(skb) - 2)) {
3043 if (net_ratelimit())
3045 "bad partial csum: csum=%u/%u len=%u\n",
3046 start, off, skb_headlen(skb));
3049 skb->ip_summed = CHECKSUM_PARTIAL;
3050 skb->csum_start = skb_headroom(skb) + start;
3051 skb->csum_offset = off;
3054 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3056 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3058 if (net_ratelimit())
3059 pr_warning("%s: received packets cannot be forwarded"
3060 " while LRO is enabled\n", skb->dev->name);
3062 EXPORT_SYMBOL(__skb_warn_lro_forwarding);