2 * Definitions for the 'struct sk_buff' memory handlers.
5 * Alan Cox, <gw4pts@gw4pts.ampr.org>
6 * Florian La Roche, <rzsfl@rz.uni-sb.de>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
14 #ifndef _LINUX_SKBUFF_H
15 #define _LINUX_SKBUFF_H
17 #include <linux/config.h>
18 #include <linux/kernel.h>
19 #include <linux/compiler.h>
20 #include <linux/time.h>
21 #include <linux/cache.h>
23 #include <asm/atomic.h>
24 #include <asm/types.h>
25 #include <linux/spinlock.h>
27 #include <linux/highmem.h>
28 #include <linux/poll.h>
29 #include <linux/net.h>
30 #include <net/checksum.h>
32 #define HAVE_ALLOC_SKB /* For the drivers to know */
33 #define HAVE_ALIGNABLE_SKB /* Ditto 8) */
34 #define SLAB_SKB /* Slabified skbuffs */
36 #define CHECKSUM_NONE 0
38 #define CHECKSUM_UNNECESSARY 2
40 #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
41 ~(SMP_CACHE_BYTES - 1))
42 #define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \
43 sizeof(struct skb_shared_info)) & \
44 ~(SMP_CACHE_BYTES - 1))
45 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
46 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
48 /* A. Checksumming of received packets by device.
50 * NONE: device failed to checksum this packet.
51 * skb->csum is undefined.
53 * UNNECESSARY: device parsed packet and wouldbe verified checksum.
54 * skb->csum is undefined.
55 * It is bad option, but, unfortunately, many of vendors do this.
56 * Apparently with secret goal to sell you new device, when you
57 * will add new protocol to your host. F.e. IPv6. 8)
59 * HW: the most generic way. Device supplied checksum of _all_
60 * the packet as seen by netif_rx in skb->csum.
61 * NOTE: Even if device supports only some protocols, but
62 * is able to produce some skb->csum, it MUST use HW,
65 * B. Checksumming on output.
67 * NONE: skb is checksummed by protocol or csum is not required.
69 * HW: device is required to csum packet as seen by hard_start_xmit
70 * from skb->h.raw to the end and to record the checksum
71 * at skb->h.raw+skb->csum.
73 * Device must show its capabilities in dev->features, set
74 * at device setup time.
75 * NETIF_F_HW_CSUM - it is clever device, it is able to checksum
77 * NETIF_F_NO_CSUM - loopback or reliable single hop media.
78 * NETIF_F_IP_CSUM - device is dumb. It is able to csum only
79 * TCP/UDP over IPv4. Sigh. Vendors like this
80 * way by an unknown reason. Though, see comment above
81 * about CHECKSUM_UNNECESSARY. 8)
83 * Any questions? No questions, good. --ANK
87 #define NET_CALLER(arg) (*(((void **)&arg) - 1))
89 #define NET_CALLER(arg) __builtin_return_address(0)
92 #ifdef CONFIG_NETFILTER
95 void (*destroy)(struct nf_conntrack *);
99 struct nf_conntrack *master;
102 #ifdef CONFIG_BRIDGE_NETFILTER
103 struct nf_bridge_info {
105 struct net_device *physindev;
106 struct net_device *physoutdev;
107 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
108 struct net_device *netoutdev;
111 unsigned long data[32 / sizeof(unsigned long)];
117 struct sk_buff_head {
118 /* These two members must be first. */
119 struct sk_buff *next;
120 struct sk_buff *prev;
128 /* To allow 64K frame to be packed as single skb without frag_list */
129 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
131 typedef struct skb_frag_struct skb_frag_t;
133 struct skb_frag_struct {
139 /* This data is invariant across clones and lives at
140 * the end of the header data, ie. at skb->end.
142 struct skb_shared_info {
144 unsigned int nr_frags;
145 unsigned short tso_size;
146 unsigned short tso_segs;
147 struct sk_buff *frag_list;
148 skb_frag_t frags[MAX_SKB_FRAGS];
152 * struct sk_buff - socket buffer
153 * @next: Next buffer in list
154 * @prev: Previous buffer in list
155 * @list: List we are on
156 * @sk: Socket we are owned by
157 * @stamp: Time we arrived
158 * @dev: Device we arrived on/are leaving by
159 * @input_dev: Device we arrived on
160 * @real_dev: The real device we are using
161 * @h: Transport layer header
162 * @nh: Network layer header
163 * @mac: Link layer header
164 * @dst: FIXME: Describe this field
165 * @cb: Control buffer. Free for use by every layer. Put private vars here
166 * @len: Length of actual data
167 * @data_len: Data length
168 * @mac_len: Length of link layer header
170 * @__unused: Dead field, may be reused
171 * @cloned: Head may be cloned (check refcnt to be sure)
172 * @pkt_type: Packet class
173 * @ip_summed: Driver fed us an IP checksum
174 * @priority: Packet queueing priority
175 * @users: User count - see {datagram,tcp}.c
176 * @protocol: Packet protocol from driver
177 * @security: Security level of packet
178 * @truesize: Buffer size
179 * @head: Head of buffer
180 * @data: Data head pointer
181 * @tail: Tail pointer
183 * @destructor: Destruct function
184 * @nfmark: Can be used for communication between hooks
185 * @nfcache: Cache info
186 * @nfct: Associated connection, if any
187 * @nf_debug: Netfilter debugging
188 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
189 * @private: Data which is private to the HIPPI implementation
190 * @tc_index: Traffic control index
194 /* These two members must be first. */
195 struct sk_buff *next;
196 struct sk_buff *prev;
198 struct sk_buff_head *list;
200 struct timeval stamp;
201 struct net_device *dev;
202 struct net_device *input_dev;
203 struct net_device *real_dev;
208 struct icmphdr *icmph;
209 struct igmphdr *igmph;
211 struct ipv6hdr *ipv6h;
217 struct ipv6hdr *ipv6h;
223 struct ethhdr *ethernet;
227 struct dst_entry *dst;
231 * This is the control buffer. It is free to use for every
232 * layer. Please put your private variables there. If you
233 * want to keep them across layers you have to do a skb_clone()
234 * first. This is owned by whoever has the skb queued ATM.
242 unsigned char local_df,
247 unsigned short protocol,
250 void (*destructor)(struct sk_buff *skb);
251 #ifdef CONFIG_NETFILTER
252 unsigned long nfmark;
254 struct nf_ct_info *nfct;
255 #ifdef CONFIG_NETFILTER_DEBUG
256 unsigned int nf_debug;
258 #ifdef CONFIG_BRIDGE_NETFILTER
259 struct nf_bridge_info *nf_bridge;
261 #endif /* CONFIG_NETFILTER */
262 #if defined(CONFIG_HIPPI)
267 #ifdef CONFIG_NET_SCHED
268 __u32 tc_index; /* traffic control index */
269 #ifdef CONFIG_NET_CLS_ACT
270 __u32 tc_verd; /* traffic control verdict */
271 __u32 tc_classid; /* traffic control classid */
277 /* These elements must be at the end, see alloc_skb() for details. */
278 unsigned int truesize;
288 * Handling routines are only of interest to the kernel
290 #include <linux/slab.h>
292 #include <asm/system.h>
294 extern void __kfree_skb(struct sk_buff *skb);
295 extern struct sk_buff *alloc_skb(unsigned int size, int priority);
296 extern void kfree_skbmem(struct sk_buff *skb);
297 extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
298 extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
299 extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
300 extern int pskb_expand_head(struct sk_buff *skb,
301 int nhead, int ntail, int gfp_mask);
302 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
303 unsigned int headroom);
304 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
305 int newheadroom, int newtailroom,
307 extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
308 #define dev_kfree_skb(a) kfree_skb(a)
309 extern void skb_over_panic(struct sk_buff *skb, int len,
311 extern void skb_under_panic(struct sk_buff *skb, int len,
315 #define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
318 * skb_queue_empty - check if a queue is empty
321 * Returns true if the queue is empty, false otherwise.
323 static inline int skb_queue_empty(const struct sk_buff_head *list)
325 return list->next == (struct sk_buff *)list;
329 * skb_get - reference buffer
330 * @skb: buffer to reference
332 * Makes another reference to a socket buffer and returns a pointer
335 static inline struct sk_buff *skb_get(struct sk_buff *skb)
337 atomic_inc(&skb->users);
342 * If users == 1, we are the only owner and are can avoid redundant
347 * kfree_skb - free an sk_buff
348 * @skb: buffer to free
350 * Drop a reference to the buffer and free it if the usage count has
353 static inline void kfree_skb(struct sk_buff *skb)
355 if (atomic_read(&skb->users) == 1 || atomic_dec_and_test(&skb->users))
359 /* Use this if you didn't touch the skb state [for fast switching] */
360 static inline void kfree_skb_fast(struct sk_buff *skb)
362 if (atomic_read(&skb->users) == 1 || atomic_dec_and_test(&skb->users))
367 * skb_cloned - is the buffer a clone
368 * @skb: buffer to check
370 * Returns true if the buffer was generated with skb_clone() and is
371 * one of multiple shared copies of the buffer. Cloned buffers are
372 * shared data so must not be written to under normal circumstances.
374 static inline int skb_cloned(const struct sk_buff *skb)
376 return skb->cloned && atomic_read(&skb_shinfo(skb)->dataref) != 1;
380 * skb_shared - is the buffer shared
381 * @skb: buffer to check
383 * Returns true if more than one person has a reference to this
386 static inline int skb_shared(const struct sk_buff *skb)
388 return atomic_read(&skb->users) != 1;
392 * skb_share_check - check if buffer is shared and if so clone it
393 * @skb: buffer to check
394 * @pri: priority for memory allocation
396 * If the buffer is shared the buffer is cloned and the old copy
397 * drops a reference. A new clone with a single reference is returned.
398 * If the buffer is not shared the original buffer is returned. When
399 * being called from interrupt status or with spinlocks held pri must
402 * NULL is returned on a memory allocation failure.
404 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri)
406 might_sleep_if(pri & __GFP_WAIT);
407 if (skb_shared(skb)) {
408 struct sk_buff *nskb = skb_clone(skb, pri);
416 * Copy shared buffers into a new sk_buff. We effectively do COW on
417 * packets to handle cases where we have a local reader and forward
418 * and a couple of other messy ones. The normal one is tcpdumping
419 * a packet thats being forwarded.
423 * skb_unshare - make a copy of a shared buffer
424 * @skb: buffer to check
425 * @pri: priority for memory allocation
427 * If the socket buffer is a clone then this function creates a new
428 * copy of the data, drops a reference count on the old copy and returns
429 * the new copy with the reference count at 1. If the buffer is not a clone
430 * the original buffer is returned. When called with a spinlock held or
431 * from interrupt state @pri must be %GFP_ATOMIC
433 * %NULL is returned on a memory allocation failure.
435 static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri)
437 might_sleep_if(pri & __GFP_WAIT);
438 if (skb_cloned(skb)) {
439 struct sk_buff *nskb = skb_copy(skb, pri);
440 kfree_skb(skb); /* Free our shared copy */
448 * @list_: list to peek at
450 * Peek an &sk_buff. Unlike most other operations you _MUST_
451 * be careful with this one. A peek leaves the buffer on the
452 * list and someone else may run off with it. You must hold
453 * the appropriate locks or have a private queue to do this.
455 * Returns %NULL for an empty list or a pointer to the head element.
456 * The reference count is not incremented and the reference is therefore
457 * volatile. Use with caution.
459 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
461 struct sk_buff *list = ((struct sk_buff *)list_)->next;
462 if (list == (struct sk_buff *)list_)
469 * @list_: list to peek at
471 * Peek an &sk_buff. Unlike most other operations you _MUST_
472 * be careful with this one. A peek leaves the buffer on the
473 * list and someone else may run off with it. You must hold
474 * the appropriate locks or have a private queue to do this.
476 * Returns %NULL for an empty list or a pointer to the tail element.
477 * The reference count is not incremented and the reference is therefore
478 * volatile. Use with caution.
480 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
482 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
483 if (list == (struct sk_buff *)list_)
489 * skb_queue_len - get queue length
490 * @list_: list to measure
492 * Return the length of an &sk_buff queue.
494 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
499 static inline void skb_queue_head_init(struct sk_buff_head *list)
501 spin_lock_init(&list->lock);
502 list->prev = list->next = (struct sk_buff *)list;
507 * Insert an sk_buff at the start of a list.
509 * The "__skb_xxxx()" functions are the non-atomic ones that
510 * can only be called with interrupts disabled.
514 * __skb_queue_head - queue a buffer at the list head
516 * @newsk: buffer to queue
518 * Queue a buffer at the start of a list. This function takes no locks
519 * and you must therefore hold required locks before calling it.
521 * A buffer cannot be placed on two lists at the same time.
523 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
524 static inline void __skb_queue_head(struct sk_buff_head *list,
525 struct sk_buff *newsk)
527 struct sk_buff *prev, *next;
531 prev = (struct sk_buff *)list;
535 next->prev = prev->next = newsk;
539 * __skb_queue_tail - queue a buffer at the list tail
541 * @newsk: buffer to queue
543 * Queue a buffer at the end of a list. This function takes no locks
544 * and you must therefore hold required locks before calling it.
546 * A buffer cannot be placed on two lists at the same time.
548 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
549 static inline void __skb_queue_tail(struct sk_buff_head *list,
550 struct sk_buff *newsk)
552 struct sk_buff *prev, *next;
556 next = (struct sk_buff *)list;
560 next->prev = prev->next = newsk;
565 * __skb_dequeue - remove from the head of the queue
566 * @list: list to dequeue from
568 * Remove the head of the list. This function does not take any locks
569 * so must be used with appropriate locks held only. The head item is
570 * returned or %NULL if the list is empty.
572 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
573 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
575 struct sk_buff *next, *prev, *result;
577 prev = (struct sk_buff *) list;
586 result->next = result->prev = NULL;
594 * Insert a packet on a list.
596 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk);
597 static inline void __skb_insert(struct sk_buff *newsk,
598 struct sk_buff *prev, struct sk_buff *next,
599 struct sk_buff_head *list)
603 next->prev = prev->next = newsk;
609 * Place a packet after a given packet in a list.
611 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk);
612 static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk)
614 __skb_insert(newsk, old, old->next, old->list);
618 * remove sk_buff from list. _Must_ be called atomically, and with
621 extern void skb_unlink(struct sk_buff *skb);
622 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
624 struct sk_buff *next, *prev;
629 skb->next = skb->prev = NULL;
636 /* XXX: more streamlined implementation */
639 * __skb_dequeue_tail - remove from the tail of the queue
640 * @list: list to dequeue from
642 * Remove the tail of the list. This function does not take any locks
643 * so must be used with appropriate locks held only. The tail item is
644 * returned or %NULL if the list is empty.
646 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
647 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
649 struct sk_buff *skb = skb_peek_tail(list);
651 __skb_unlink(skb, list);
656 static inline int skb_is_nonlinear(const struct sk_buff *skb)
658 return skb->data_len;
661 static inline unsigned int skb_headlen(const struct sk_buff *skb)
663 return skb->len - skb->data_len;
666 static inline int skb_pagelen(const struct sk_buff *skb)
670 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
671 len += skb_shinfo(skb)->frags[i].size;
672 return len + skb_headlen(skb);
675 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
676 struct page *page, int off, int size)
678 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
681 frag->page_offset = off;
683 skb_shinfo(skb)->nr_frags = i + 1;
686 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
687 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
688 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
691 * Add data to an sk_buff
693 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
695 unsigned char *tmp = skb->tail;
696 SKB_LINEAR_ASSERT(skb);
703 * skb_put - add data to a buffer
704 * @skb: buffer to use
705 * @len: amount of data to add
707 * This function extends the used data area of the buffer. If this would
708 * exceed the total buffer size the kernel will panic. A pointer to the
709 * first byte of the extra data is returned.
711 static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
713 unsigned char *tmp = skb->tail;
714 SKB_LINEAR_ASSERT(skb);
717 if (unlikely(skb->tail>skb->end))
718 skb_over_panic(skb, len, current_text_addr());
722 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
730 * skb_push - add data to the start of a buffer
731 * @skb: buffer to use
732 * @len: amount of data to add
734 * This function extends the used data area of the buffer at the buffer
735 * start. If this would exceed the total buffer headroom the kernel will
736 * panic. A pointer to the first byte of the extra data is returned.
738 static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
742 if (unlikely(skb->data<skb->head))
743 skb_under_panic(skb, len, current_text_addr());
747 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
750 BUG_ON(skb->len < skb->data_len);
751 return skb->data += len;
755 * skb_pull - remove data from the start of a buffer
756 * @skb: buffer to use
757 * @len: amount of data to remove
759 * This function removes data from the start of a buffer, returning
760 * the memory to the headroom. A pointer to the next data in the buffer
761 * is returned. Once the data has been pulled future pushes will overwrite
764 static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
766 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
769 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
771 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
773 if (len > skb_headlen(skb) &&
774 !__pskb_pull_tail(skb, len-skb_headlen(skb)))
777 return skb->data += len;
780 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
782 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
785 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
787 if (likely(len <= skb_headlen(skb)))
789 if (unlikely(len > skb->len))
791 return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
795 * skb_headroom - bytes at buffer head
796 * @skb: buffer to check
798 * Return the number of bytes of free space at the head of an &sk_buff.
800 static inline int skb_headroom(const struct sk_buff *skb)
802 return skb->data - skb->head;
806 * skb_tailroom - bytes at buffer end
807 * @skb: buffer to check
809 * Return the number of bytes of free space at the tail of an sk_buff
811 static inline int skb_tailroom(const struct sk_buff *skb)
813 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
817 * skb_reserve - adjust headroom
818 * @skb: buffer to alter
819 * @len: bytes to move
821 * Increase the headroom of an empty &sk_buff by reducing the tail
822 * room. This is only allowed for an empty buffer.
824 static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
831 * CPUs often take a performance hit when accessing unaligned memory
832 * locations. The actual performance hit varies, it can be small if the
833 * hardware handles it or large if we have to take an exception and fix it
836 * Since an ethernet header is 14 bytes network drivers often end up with
837 * the IP header at an unaligned offset. The IP header can be aligned by
838 * shifting the start of the packet by 2 bytes. Drivers should do this
841 * skb_reserve(NET_IP_ALIGN);
843 * The downside to this alignment of the IP header is that the DMA is now
844 * unaligned. On some architectures the cost of an unaligned DMA is high
845 * and this cost outweighs the gains made by aligning the IP header.
847 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
851 #define NET_IP_ALIGN 2
854 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
856 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
858 if (!skb->data_len) {
860 skb->tail = skb->data + len;
862 ___pskb_trim(skb, len, 0);
866 * skb_trim - remove end from a buffer
867 * @skb: buffer to alter
870 * Cut the length of a buffer down by removing data from the tail. If
871 * the buffer is already under the length specified it is not modified.
873 static inline void skb_trim(struct sk_buff *skb, unsigned int len)
876 __skb_trim(skb, len);
880 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
882 if (!skb->data_len) {
884 skb->tail = skb->data+len;
887 return ___pskb_trim(skb, len, 1);
890 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
892 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
896 * skb_orphan - orphan a buffer
897 * @skb: buffer to orphan
899 * If a buffer currently has an owner then we call the owner's
900 * destructor function and make the @skb unowned. The buffer continues
901 * to exist but is no longer charged to its former owner.
903 static inline void skb_orphan(struct sk_buff *skb)
906 skb->destructor(skb);
907 skb->destructor = NULL;
912 * __skb_queue_purge - empty a list
913 * @list: list to empty
915 * Delete all buffers on an &sk_buff list. Each buffer is removed from
916 * the list and one reference dropped. This function does not take the
917 * list lock and the caller must hold the relevant locks to use it.
919 extern void skb_queue_purge(struct sk_buff_head *list);
920 static inline void __skb_queue_purge(struct sk_buff_head *list)
923 while ((skb = __skb_dequeue(list)) != NULL)
928 * __dev_alloc_skb - allocate an skbuff for sending
929 * @length: length to allocate
930 * @gfp_mask: get_free_pages mask, passed to alloc_skb
932 * Allocate a new &sk_buff and assign it a usage count of one. The
933 * buffer has unspecified headroom built in. Users should allocate
934 * the headroom they think they need without accounting for the
935 * built in space. The built in space is used for optimisations.
937 * %NULL is returned in there is no free memory.
939 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
942 struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
944 skb_reserve(skb, 16);
949 * dev_alloc_skb - allocate an skbuff for sending
950 * @length: length to allocate
952 * Allocate a new &sk_buff and assign it a usage count of one. The
953 * buffer has unspecified headroom built in. Users should allocate
954 * the headroom they think they need without accounting for the
955 * built in space. The built in space is used for optimisations.
957 * %NULL is returned in there is no free memory. Although this function
958 * allocates memory it can be called from an interrupt.
960 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
962 return __dev_alloc_skb(length, GFP_ATOMIC);
966 * skb_cow - copy header of skb when it is required
967 * @skb: buffer to cow
968 * @headroom: needed headroom
970 * If the skb passed lacks sufficient headroom or its data part
971 * is shared, data is reallocated. If reallocation fails, an error
972 * is returned and original skb is not changed.
974 * The result is skb with writable area skb->head...skb->tail
975 * and at least @headroom of space at head.
977 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
979 int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb);
984 if (delta || skb_cloned(skb))
985 return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC);
990 * skb_padto - pad an skbuff up to a minimal size
991 * @skb: buffer to pad
992 * @len: minimal length
994 * Pads up a buffer to ensure the trailing bytes exist and are
995 * blanked. If the buffer already contains sufficient data it
996 * is untouched. Returns the buffer, which may be a replacement
997 * for the original, or NULL for out of memory - in which case
998 * the original buffer is still freed.
1001 static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
1003 unsigned int size = skb->len;
1004 if (likely(size >= len))
1006 return skb_pad(skb, len-size);
1009 static inline int skb_add_data(struct sk_buff *skb,
1010 char __user *from, int copy)
1012 const int off = skb->len;
1014 if (skb->ip_summed == CHECKSUM_NONE) {
1016 unsigned int csum = csum_and_copy_from_user(from,
1020 skb->csum = csum_block_add(skb->csum, csum, off);
1023 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1026 __skb_trim(skb, off);
1030 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1031 struct page *page, int off)
1034 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1036 return page == frag->page &&
1037 off == frag->page_offset + frag->size;
1043 * skb_linearize - convert paged skb to linear one
1044 * @skb: buffer to linarize
1045 * @gfp: allocation mode
1047 * If there is no free memory -ENOMEM is returned, otherwise zero
1048 * is returned and the old skb data released.
1050 extern int __skb_linearize(struct sk_buff *skb, int gfp);
1051 static inline int skb_linearize(struct sk_buff *skb, int gfp)
1053 return __skb_linearize(skb, gfp);
1056 static inline void *kmap_skb_frag(const skb_frag_t *frag)
1058 #ifdef CONFIG_HIGHMEM
1063 return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ);
1066 static inline void kunmap_skb_frag(void *vaddr)
1068 kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
1069 #ifdef CONFIG_HIGHMEM
1074 #define skb_queue_walk(queue, skb) \
1075 for (skb = (queue)->next, prefetch(skb->next); \
1076 (skb != (struct sk_buff *)(queue)); \
1077 skb = skb->next, prefetch(skb->next))
1080 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1081 int noblock, int *err);
1082 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1083 struct poll_table_struct *wait);
1084 extern int skb_copy_datagram(const struct sk_buff *from,
1085 int offset, char __user *to, int size);
1086 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1087 int offset, struct iovec *to,
1089 extern int skb_copy_and_csum_datagram(const struct sk_buff *skb,
1090 int offset, u8 __user *to,
1091 int len, unsigned int *csump);
1092 extern int skb_copy_and_csum_datagram_iovec(const
1093 struct sk_buff *skb,
1096 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1097 extern unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1098 int len, unsigned int csum);
1099 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1101 extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb,
1102 int offset, u8 *to, int len,
1104 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1105 extern void skb_split(struct sk_buff *skb,
1106 struct sk_buff *skb1, const u32 len);
1108 extern void skb_init(void);
1109 extern void skb_add_mtu(int mtu);
1111 #ifdef CONFIG_NETFILTER
1112 static inline void nf_conntrack_put(struct nf_ct_info *nfct)
1114 if (nfct && atomic_dec_and_test(&nfct->master->use))
1115 nfct->master->destroy(nfct->master);
1117 static inline void nf_conntrack_get(struct nf_ct_info *nfct)
1120 atomic_inc(&nfct->master->use);
1122 static inline void nf_reset(struct sk_buff *skb)
1124 nf_conntrack_put(skb->nfct);
1126 #ifdef CONFIG_NETFILTER_DEBUG
1131 #ifdef CONFIG_BRIDGE_NETFILTER
1132 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1134 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1137 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1140 atomic_inc(&nf_bridge->use);
1142 #endif /* CONFIG_BRIDGE_NETFILTER */
1143 #else /* CONFIG_NETFILTER */
1144 static inline void nf_reset(struct sk_buff *skb) {}
1145 #endif /* CONFIG_NETFILTER */
1147 #endif /* __KERNEL__ */
1148 #endif /* _LINUX_SKBUFF_H */