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)
94 #ifdef CONFIG_NETFILTER
97 void (*destroy)(struct nf_conntrack *);
100 #ifdef CONFIG_BRIDGE_NETFILTER
101 struct nf_bridge_info {
103 struct net_device *physindev;
104 struct net_device *physoutdev;
105 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
106 struct net_device *netoutdev;
109 unsigned long data[32 / sizeof(unsigned long)];
115 struct sk_buff_head {
116 /* These two members must be first. */
117 struct sk_buff *next;
118 struct sk_buff *prev;
126 /* To allow 64K frame to be packed as single skb without frag_list */
127 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
129 typedef struct skb_frag_struct skb_frag_t;
131 struct skb_frag_struct {
137 /* This data is invariant across clones and lives at
138 * the end of the header data, ie. at skb->end.
140 struct skb_shared_info {
142 unsigned int nr_frags;
143 unsigned short tso_size;
144 unsigned short tso_segs;
145 struct sk_buff *frag_list;
146 skb_frag_t frags[MAX_SKB_FRAGS];
150 * struct sk_buff - socket buffer
151 * @next: Next buffer in list
152 * @prev: Previous buffer in list
153 * @list: List we are on
154 * @sk: Socket we are owned by
155 * @stamp: Time we arrived
156 * @dev: Device we arrived on/are leaving by
157 * @input_dev: Device we arrived on
158 * @real_dev: The real device we are using
159 * @h: Transport layer header
160 * @nh: Network layer header
161 * @mac: Link layer header
162 * @dst: FIXME: Describe this field
163 * @cb: Control buffer. Free for use by every layer. Put private vars here
164 * @len: Length of actual data
165 * @data_len: Data length
166 * @mac_len: Length of link layer header
168 * @__unused: Dead field, may be reused
169 * @cloned: Head may be cloned (check refcnt to be sure)
170 * @pkt_type: Packet class
171 * @ip_summed: Driver fed us an IP checksum
172 * @priority: Packet queueing priority
173 * @users: User count - see {datagram,tcp}.c
174 * @protocol: Packet protocol from driver
175 * @security: Security level of packet
176 * @truesize: Buffer size
177 * @head: Head of buffer
178 * @data: Data head pointer
179 * @tail: Tail pointer
181 * @destructor: Destruct function
182 * @nfmark: Can be used for communication between hooks
183 * @nfcache: Cache info
184 * @nfct: Associated connection, if any
185 * @nfctinfo: Relationship of this skb to the connection
186 * @nf_debug: Netfilter debugging
187 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
188 * @private: Data which is private to the HIPPI implementation
189 * @tc_index: Traffic control index
193 /* These two members must be first. */
194 struct sk_buff *next;
195 struct sk_buff *prev;
197 struct sk_buff_head *list;
199 struct timeval stamp;
200 struct net_device *dev;
201 struct net_device *input_dev;
202 struct net_device *real_dev;
207 struct icmphdr *icmph;
208 struct igmphdr *igmph;
210 struct ipv6hdr *ipv6h;
216 struct ipv6hdr *ipv6h;
225 struct dst_entry *dst;
229 * This is the control buffer. It is free to use for every
230 * layer. Please put your private variables there. If you
231 * want to keep them across layers you have to do a skb_clone()
232 * first. This is owned by whoever has the skb queued ATM.
240 unsigned char local_df,
245 unsigned short protocol,
248 void (*destructor)(struct sk_buff *skb);
249 #ifdef CONFIG_NETFILTER
250 unsigned long nfmark;
253 struct nf_conntrack *nfct;
254 #ifdef CONFIG_NETFILTER_DEBUG
255 unsigned int nf_debug;
257 #ifdef CONFIG_BRIDGE_NETFILTER
258 struct nf_bridge_info *nf_bridge;
260 #endif /* CONFIG_NETFILTER */
261 #if defined(CONFIG_HIPPI)
266 #ifdef CONFIG_NET_SCHED
267 __u32 tc_index; /* traffic control index */
268 #ifdef CONFIG_NET_CLS_ACT
269 __u32 tc_verd; /* traffic control verdict */
270 __u32 tc_classid; /* traffic control classid */
276 /* These elements must be at the end, see alloc_skb() for details. */
277 unsigned int truesize;
287 * Handling routines are only of interest to the kernel
289 #include <linux/slab.h>
291 #include <asm/system.h>
293 extern void __kfree_skb(struct sk_buff *skb);
294 extern struct sk_buff *alloc_skb(unsigned int size, int priority);
295 extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
296 unsigned int size, int priority);
297 extern void kfree_skbmem(struct sk_buff *skb);
298 extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
299 extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
300 extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
301 extern int pskb_expand_head(struct sk_buff *skb,
302 int nhead, int ntail, int gfp_mask);
303 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
304 unsigned int headroom);
305 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
306 int newheadroom, int newtailroom,
308 extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
309 #define dev_kfree_skb(a) kfree_skb(a)
310 extern void skb_over_panic(struct sk_buff *skb, int len,
312 extern void skb_under_panic(struct sk_buff *skb, int len,
316 #define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
319 * skb_queue_empty - check if a queue is empty
322 * Returns true if the queue is empty, false otherwise.
324 static inline int skb_queue_empty(const struct sk_buff_head *list)
326 return list->next == (struct sk_buff *)list;
330 * skb_get - reference buffer
331 * @skb: buffer to reference
333 * Makes another reference to a socket buffer and returns a pointer
336 static inline struct sk_buff *skb_get(struct sk_buff *skb)
338 atomic_inc(&skb->users);
343 * If users == 1, we are the only owner and are can avoid redundant
348 * kfree_skb - free an sk_buff
349 * @skb: buffer to free
351 * Drop a reference to the buffer and free it if the usage count has
354 static inline void kfree_skb(struct sk_buff *skb)
356 if (likely(atomic_read(&skb->users) == 1))
358 else if (likely(!atomic_dec_and_test(&skb->users)))
364 * skb_cloned - is the buffer a clone
365 * @skb: buffer to check
367 * Returns true if the buffer was generated with skb_clone() and is
368 * one of multiple shared copies of the buffer. Cloned buffers are
369 * shared data so must not be written to under normal circumstances.
371 static inline int skb_cloned(const struct sk_buff *skb)
373 return skb->cloned && atomic_read(&skb_shinfo(skb)->dataref) != 1;
377 * skb_shared - is the buffer shared
378 * @skb: buffer to check
380 * Returns true if more than one person has a reference to this
383 static inline int skb_shared(const struct sk_buff *skb)
385 return atomic_read(&skb->users) != 1;
389 * skb_share_check - check if buffer is shared and if so clone it
390 * @skb: buffer to check
391 * @pri: priority for memory allocation
393 * If the buffer is shared the buffer is cloned and the old copy
394 * drops a reference. A new clone with a single reference is returned.
395 * If the buffer is not shared the original buffer is returned. When
396 * being called from interrupt status or with spinlocks held pri must
399 * NULL is returned on a memory allocation failure.
401 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri)
403 might_sleep_if(pri & __GFP_WAIT);
404 if (skb_shared(skb)) {
405 struct sk_buff *nskb = skb_clone(skb, pri);
413 * Copy shared buffers into a new sk_buff. We effectively do COW on
414 * packets to handle cases where we have a local reader and forward
415 * and a couple of other messy ones. The normal one is tcpdumping
416 * a packet thats being forwarded.
420 * skb_unshare - make a copy of a shared buffer
421 * @skb: buffer to check
422 * @pri: priority for memory allocation
424 * If the socket buffer is a clone then this function creates a new
425 * copy of the data, drops a reference count on the old copy and returns
426 * the new copy with the reference count at 1. If the buffer is not a clone
427 * the original buffer is returned. When called with a spinlock held or
428 * from interrupt state @pri must be %GFP_ATOMIC
430 * %NULL is returned on a memory allocation failure.
432 static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri)
434 might_sleep_if(pri & __GFP_WAIT);
435 if (skb_cloned(skb)) {
436 struct sk_buff *nskb = skb_copy(skb, pri);
437 kfree_skb(skb); /* Free our shared copy */
445 * @list_: list to peek at
447 * Peek an &sk_buff. Unlike most other operations you _MUST_
448 * be careful with this one. A peek leaves the buffer on the
449 * list and someone else may run off with it. You must hold
450 * the appropriate locks or have a private queue to do this.
452 * Returns %NULL for an empty list or a pointer to the head element.
453 * The reference count is not incremented and the reference is therefore
454 * volatile. Use with caution.
456 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
458 struct sk_buff *list = ((struct sk_buff *)list_)->next;
459 if (list == (struct sk_buff *)list_)
466 * @list_: list to peek at
468 * Peek an &sk_buff. Unlike most other operations you _MUST_
469 * be careful with this one. A peek leaves the buffer on the
470 * list and someone else may run off with it. You must hold
471 * the appropriate locks or have a private queue to do this.
473 * Returns %NULL for an empty list or a pointer to the tail element.
474 * The reference count is not incremented and the reference is therefore
475 * volatile. Use with caution.
477 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
479 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
480 if (list == (struct sk_buff *)list_)
486 * skb_queue_len - get queue length
487 * @list_: list to measure
489 * Return the length of an &sk_buff queue.
491 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
496 static inline void skb_queue_head_init(struct sk_buff_head *list)
498 spin_lock_init(&list->lock);
499 list->prev = list->next = (struct sk_buff *)list;
504 * Insert an sk_buff at the start of a list.
506 * The "__skb_xxxx()" functions are the non-atomic ones that
507 * can only be called with interrupts disabled.
511 * __skb_queue_head - queue a buffer at the list head
513 * @newsk: buffer to queue
515 * Queue a buffer at the start of a list. This function takes no locks
516 * and you must therefore hold required locks before calling it.
518 * A buffer cannot be placed on two lists at the same time.
520 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
521 static inline void __skb_queue_head(struct sk_buff_head *list,
522 struct sk_buff *newsk)
524 struct sk_buff *prev, *next;
528 prev = (struct sk_buff *)list;
532 next->prev = prev->next = newsk;
536 * __skb_queue_tail - queue a buffer at the list tail
538 * @newsk: buffer to queue
540 * Queue a buffer at the end of a list. This function takes no locks
541 * and you must therefore hold required locks before calling it.
543 * A buffer cannot be placed on two lists at the same time.
545 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
546 static inline void __skb_queue_tail(struct sk_buff_head *list,
547 struct sk_buff *newsk)
549 struct sk_buff *prev, *next;
553 next = (struct sk_buff *)list;
557 next->prev = prev->next = newsk;
562 * __skb_dequeue - remove from the head of the queue
563 * @list: list to dequeue from
565 * Remove the head of the list. This function does not take any locks
566 * so must be used with appropriate locks held only. The head item is
567 * returned or %NULL if the list is empty.
569 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
570 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
572 struct sk_buff *next, *prev, *result;
574 prev = (struct sk_buff *) list;
583 result->next = result->prev = NULL;
591 * Insert a packet on a list.
593 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk);
594 static inline void __skb_insert(struct sk_buff *newsk,
595 struct sk_buff *prev, struct sk_buff *next,
596 struct sk_buff_head *list)
600 next->prev = prev->next = newsk;
606 * Place a packet after a given packet in a list.
608 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk);
609 static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk)
611 __skb_insert(newsk, old, old->next, old->list);
615 * remove sk_buff from list. _Must_ be called atomically, and with
618 extern void skb_unlink(struct sk_buff *skb);
619 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
621 struct sk_buff *next, *prev;
626 skb->next = skb->prev = NULL;
633 /* XXX: more streamlined implementation */
636 * __skb_dequeue_tail - remove from the tail of the queue
637 * @list: list to dequeue from
639 * Remove the tail of the list. This function does not take any locks
640 * so must be used with appropriate locks held only. The tail item is
641 * returned or %NULL if the list is empty.
643 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
644 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
646 struct sk_buff *skb = skb_peek_tail(list);
648 __skb_unlink(skb, list);
653 static inline int skb_is_nonlinear(const struct sk_buff *skb)
655 return skb->data_len;
658 static inline unsigned int skb_headlen(const struct sk_buff *skb)
660 return skb->len - skb->data_len;
663 static inline int skb_pagelen(const struct sk_buff *skb)
667 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
668 len += skb_shinfo(skb)->frags[i].size;
669 return len + skb_headlen(skb);
672 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
673 struct page *page, int off, int size)
675 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
678 frag->page_offset = off;
680 skb_shinfo(skb)->nr_frags = i + 1;
683 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
684 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
685 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
688 * Add data to an sk_buff
690 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
692 unsigned char *tmp = skb->tail;
693 SKB_LINEAR_ASSERT(skb);
700 * skb_put - add data to a buffer
701 * @skb: buffer to use
702 * @len: amount of data to add
704 * This function extends the used data area of the buffer. If this would
705 * exceed the total buffer size the kernel will panic. A pointer to the
706 * first byte of the extra data is returned.
708 static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
710 unsigned char *tmp = skb->tail;
711 SKB_LINEAR_ASSERT(skb);
714 if (unlikely(skb->tail>skb->end))
715 skb_over_panic(skb, len, current_text_addr());
719 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
727 * skb_push - add data to the start of a buffer
728 * @skb: buffer to use
729 * @len: amount of data to add
731 * This function extends the used data area of the buffer at the buffer
732 * start. If this would exceed the total buffer headroom the kernel will
733 * panic. A pointer to the first byte of the extra data is returned.
735 static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
739 if (unlikely(skb->data<skb->head))
740 skb_under_panic(skb, len, current_text_addr());
744 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
747 BUG_ON(skb->len < skb->data_len);
748 return skb->data += len;
752 * skb_pull - remove data from the start of a buffer
753 * @skb: buffer to use
754 * @len: amount of data to remove
756 * This function removes data from the start of a buffer, returning
757 * the memory to the headroom. A pointer to the next data in the buffer
758 * is returned. Once the data has been pulled future pushes will overwrite
761 static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
763 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
766 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
768 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
770 if (len > skb_headlen(skb) &&
771 !__pskb_pull_tail(skb, len-skb_headlen(skb)))
774 return skb->data += len;
777 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
779 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
782 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
784 if (likely(len <= skb_headlen(skb)))
786 if (unlikely(len > skb->len))
788 return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
792 * skb_headroom - bytes at buffer head
793 * @skb: buffer to check
795 * Return the number of bytes of free space at the head of an &sk_buff.
797 static inline int skb_headroom(const struct sk_buff *skb)
799 return skb->data - skb->head;
803 * skb_tailroom - bytes at buffer end
804 * @skb: buffer to check
806 * Return the number of bytes of free space at the tail of an sk_buff
808 static inline int skb_tailroom(const struct sk_buff *skb)
810 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
814 * skb_reserve - adjust headroom
815 * @skb: buffer to alter
816 * @len: bytes to move
818 * Increase the headroom of an empty &sk_buff by reducing the tail
819 * room. This is only allowed for an empty buffer.
821 static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
828 * CPUs often take a performance hit when accessing unaligned memory
829 * locations. The actual performance hit varies, it can be small if the
830 * hardware handles it or large if we have to take an exception and fix it
833 * Since an ethernet header is 14 bytes network drivers often end up with
834 * the IP header at an unaligned offset. The IP header can be aligned by
835 * shifting the start of the packet by 2 bytes. Drivers should do this
838 * skb_reserve(NET_IP_ALIGN);
840 * The downside to this alignment of the IP header is that the DMA is now
841 * unaligned. On some architectures the cost of an unaligned DMA is high
842 * and this cost outweighs the gains made by aligning the IP header.
844 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
848 #define NET_IP_ALIGN 2
851 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
853 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
855 if (!skb->data_len) {
857 skb->tail = skb->data + len;
859 ___pskb_trim(skb, len, 0);
863 * skb_trim - remove end from a buffer
864 * @skb: buffer to alter
867 * Cut the length of a buffer down by removing data from the tail. If
868 * the buffer is already under the length specified it is not modified.
870 static inline void skb_trim(struct sk_buff *skb, unsigned int len)
873 __skb_trim(skb, len);
877 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
879 if (!skb->data_len) {
881 skb->tail = skb->data+len;
884 return ___pskb_trim(skb, len, 1);
887 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
889 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
893 * skb_orphan - orphan a buffer
894 * @skb: buffer to orphan
896 * If a buffer currently has an owner then we call the owner's
897 * destructor function and make the @skb unowned. The buffer continues
898 * to exist but is no longer charged to its former owner.
900 static inline void skb_orphan(struct sk_buff *skb)
903 skb->destructor(skb);
904 skb->destructor = NULL;
909 * __skb_queue_purge - empty a list
910 * @list: list to empty
912 * Delete all buffers on an &sk_buff list. Each buffer is removed from
913 * the list and one reference dropped. This function does not take the
914 * list lock and the caller must hold the relevant locks to use it.
916 extern void skb_queue_purge(struct sk_buff_head *list);
917 static inline void __skb_queue_purge(struct sk_buff_head *list)
920 while ((skb = __skb_dequeue(list)) != NULL)
925 * __dev_alloc_skb - allocate an skbuff for sending
926 * @length: length to allocate
927 * @gfp_mask: get_free_pages mask, passed to alloc_skb
929 * Allocate a new &sk_buff and assign it a usage count of one. The
930 * buffer has unspecified headroom built in. Users should allocate
931 * the headroom they think they need without accounting for the
932 * built in space. The built in space is used for optimisations.
934 * %NULL is returned in there is no free memory.
936 #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
937 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
940 struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
942 skb_reserve(skb, 16);
946 extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask);
950 * dev_alloc_skb - allocate an skbuff for sending
951 * @length: length to allocate
953 * Allocate a new &sk_buff and assign it a usage count of one. The
954 * buffer has unspecified headroom built in. Users should allocate
955 * the headroom they think they need without accounting for the
956 * built in space. The built in space is used for optimisations.
958 * %NULL is returned in there is no free memory. Although this function
959 * allocates memory it can be called from an interrupt.
961 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
963 return __dev_alloc_skb(length, GFP_ATOMIC);
967 * skb_cow - copy header of skb when it is required
968 * @skb: buffer to cow
969 * @headroom: needed headroom
971 * If the skb passed lacks sufficient headroom or its data part
972 * is shared, data is reallocated. If reallocation fails, an error
973 * is returned and original skb is not changed.
975 * The result is skb with writable area skb->head...skb->tail
976 * and at least @headroom of space at head.
978 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
980 int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb);
985 if (delta || skb_cloned(skb))
986 return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC);
991 * skb_padto - pad an skbuff up to a minimal size
992 * @skb: buffer to pad
993 * @len: minimal length
995 * Pads up a buffer to ensure the trailing bytes exist and are
996 * blanked. If the buffer already contains sufficient data it
997 * is untouched. Returns the buffer, which may be a replacement
998 * for the original, or NULL for out of memory - in which case
999 * the original buffer is still freed.
1002 static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
1004 unsigned int size = skb->len;
1005 if (likely(size >= len))
1007 return skb_pad(skb, len-size);
1010 static inline int skb_add_data(struct sk_buff *skb,
1011 char __user *from, int copy)
1013 const int off = skb->len;
1015 if (skb->ip_summed == CHECKSUM_NONE) {
1017 unsigned int csum = csum_and_copy_from_user(from,
1021 skb->csum = csum_block_add(skb->csum, csum, off);
1024 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1027 __skb_trim(skb, off);
1031 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1032 struct page *page, int off)
1035 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1037 return page == frag->page &&
1038 off == frag->page_offset + frag->size;
1044 * skb_linearize - convert paged skb to linear one
1045 * @skb: buffer to linarize
1046 * @gfp: allocation mode
1048 * If there is no free memory -ENOMEM is returned, otherwise zero
1049 * is returned and the old skb data released.
1051 extern int __skb_linearize(struct sk_buff *skb, int gfp);
1052 static inline int skb_linearize(struct sk_buff *skb, int gfp)
1054 return __skb_linearize(skb, gfp);
1057 static inline void *kmap_skb_frag(const skb_frag_t *frag)
1059 #ifdef CONFIG_HIGHMEM
1064 return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ);
1067 static inline void kunmap_skb_frag(void *vaddr)
1069 kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
1070 #ifdef CONFIG_HIGHMEM
1075 #define skb_queue_walk(queue, skb) \
1076 for (skb = (queue)->next; \
1077 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1081 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1082 int noblock, int *err);
1083 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1084 struct poll_table_struct *wait);
1085 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1086 int offset, struct iovec *to,
1088 extern int skb_copy_and_csum_datagram_iovec(const
1089 struct sk_buff *skb,
1092 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1093 extern unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1094 int len, unsigned int csum);
1095 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1097 extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb,
1098 int offset, u8 *to, int len,
1100 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1101 extern void skb_split(struct sk_buff *skb,
1102 struct sk_buff *skb1, const u32 len);
1104 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
1105 int len, void *buffer)
1107 int hlen = skb_headlen(skb);
1109 if (offset + len <= hlen)
1110 return skb->data + offset;
1112 if (skb_copy_bits(skb, offset, buffer, len) < 0)
1118 extern void skb_init(void);
1119 extern void skb_add_mtu(int mtu);
1122 /* Iteration functions set these */
1123 unsigned char *data;
1126 /* Private to iteration */
1127 unsigned int nextfrag;
1128 struct sk_buff *fraglist;
1131 /* Keep iterating until skb_iter_next returns false. */
1132 extern void skb_iter_first(const struct sk_buff *skb, struct skb_iter *i);
1133 extern int skb_iter_next(const struct sk_buff *skb, struct skb_iter *i);
1134 /* Call this if aborting loop before !skb_iter_next */
1135 extern void skb_iter_abort(const struct sk_buff *skb, struct skb_iter *i);
1137 #ifdef CONFIG_NETFILTER
1138 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
1140 if (nfct && atomic_dec_and_test(&nfct->use))
1141 nfct->destroy(nfct);
1143 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
1146 atomic_inc(&nfct->use);
1148 static inline void nf_reset(struct sk_buff *skb)
1150 nf_conntrack_put(skb->nfct);
1152 #ifdef CONFIG_NETFILTER_DEBUG
1156 static inline void nf_reset_debug(struct sk_buff *skb)
1158 #ifdef CONFIG_NETFILTER_DEBUG
1163 #ifdef CONFIG_BRIDGE_NETFILTER
1164 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1166 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1169 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1172 atomic_inc(&nf_bridge->use);
1174 #endif /* CONFIG_BRIDGE_NETFILTER */
1175 #else /* CONFIG_NETFILTER */
1176 static inline void nf_reset(struct sk_buff *skb) {}
1177 #endif /* CONFIG_NETFILTER */
1179 #endif /* __KERNEL__ */
1180 #endif /* _LINUX_SKBUFF_H */