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 <linux/textsearch.h>
31 #include <net/checksum.h>
33 #define HAVE_ALLOC_SKB /* For the drivers to know */
34 #define HAVE_ALIGNABLE_SKB /* Ditto 8) */
35 #define SLAB_SKB /* Slabified skbuffs */
37 #define CHECKSUM_NONE 0
39 #define CHECKSUM_UNNECESSARY 2
41 #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
42 ~(SMP_CACHE_BYTES - 1))
43 #define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \
44 sizeof(struct skb_shared_info)) & \
45 ~(SMP_CACHE_BYTES - 1))
46 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
47 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
49 /* A. Checksumming of received packets by device.
51 * NONE: device failed to checksum this packet.
52 * skb->csum is undefined.
54 * UNNECESSARY: device parsed packet and wouldbe verified checksum.
55 * skb->csum is undefined.
56 * It is bad option, but, unfortunately, many of vendors do this.
57 * Apparently with secret goal to sell you new device, when you
58 * will add new protocol to your host. F.e. IPv6. 8)
60 * HW: the most generic way. Device supplied checksum of _all_
61 * the packet as seen by netif_rx in skb->csum.
62 * NOTE: Even if device supports only some protocols, but
63 * is able to produce some skb->csum, it MUST use HW,
66 * B. Checksumming on output.
68 * NONE: skb is checksummed by protocol or csum is not required.
70 * HW: device is required to csum packet as seen by hard_start_xmit
71 * from skb->h.raw to the end and to record the checksum
72 * at skb->h.raw+skb->csum.
74 * Device must show its capabilities in dev->features, set
75 * at device setup time.
76 * NETIF_F_HW_CSUM - it is clever device, it is able to checksum
78 * NETIF_F_NO_CSUM - loopback or reliable single hop media.
79 * NETIF_F_IP_CSUM - device is dumb. It is able to csum only
80 * TCP/UDP over IPv4. Sigh. Vendors like this
81 * way by an unknown reason. Though, see comment above
82 * about CHECKSUM_UNNECESSARY. 8)
84 * Any questions? No questions, good. --ANK
89 #ifdef CONFIG_NETFILTER
92 void (*destroy
)(struct nf_conntrack
*);
95 #ifdef CONFIG_BRIDGE_NETFILTER
96 struct nf_bridge_info
{
98 struct net_device
*physindev
;
99 struct net_device
*physoutdev
;
100 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
101 struct net_device
*netoutdev
;
104 unsigned long data
[32 / sizeof(unsigned long)];
110 struct sk_buff_head
{
111 /* These two members must be first. */
112 struct sk_buff
*next
;
113 struct sk_buff
*prev
;
121 /* To allow 64K frame to be packed as single skb without frag_list */
122 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
124 typedef struct skb_frag_struct skb_frag_t
;
126 struct skb_frag_struct
{
132 /* This data is invariant across clones and lives at
133 * the end of the header data, ie. at skb->end.
135 struct skb_shared_info
{
137 unsigned int nr_frags
;
138 unsigned short tso_size
;
139 unsigned short tso_segs
;
140 unsigned short ufo_size
;
141 unsigned int ip6_frag_id
;
142 struct sk_buff
*frag_list
;
143 skb_frag_t frags
[MAX_SKB_FRAGS
];
146 /* We divide dataref into two halves. The higher 16 bits hold references
147 * to the payload part of skb->data. The lower 16 bits hold references to
148 * the entire skb->data. It is up to the users of the skb to agree on
149 * where the payload starts.
151 * All users must obey the rule that the skb->data reference count must be
152 * greater than or equal to the payload reference count.
154 * Holding a reference to the payload part means that the user does not
155 * care about modifications to the header part of skb->data.
157 #define SKB_DATAREF_SHIFT 16
158 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
167 SKB_FCLONE_UNAVAILABLE
,
173 * struct sk_buff - socket buffer
174 * @next: Next buffer in list
175 * @prev: Previous buffer in list
176 * @sk: Socket we are owned by
177 * @tstamp: Time we arrived
178 * @dev: Device we arrived on/are leaving by
179 * @input_dev: Device we arrived on
180 * @h: Transport layer header
181 * @nh: Network layer header
182 * @mac: Link layer header
183 * @dst: destination entry
184 * @sp: the security path, used for xfrm
185 * @cb: Control buffer. Free for use by every layer. Put private vars here
186 * @len: Length of actual data
187 * @data_len: Data length
188 * @mac_len: Length of link layer header
190 * @local_df: allow local fragmentation
191 * @cloned: Head may be cloned (check refcnt to be sure)
192 * @nohdr: Payload reference only, must not modify header
193 * @pkt_type: Packet class
194 * @fclone: skbuff clone status
195 * @ip_summed: Driver fed us an IP checksum
196 * @priority: Packet queueing priority
197 * @users: User count - see {datagram,tcp}.c
198 * @protocol: Packet protocol from driver
199 * @truesize: Buffer size
200 * @head: Head of buffer
201 * @data: Data head pointer
202 * @tail: Tail pointer
204 * @destructor: Destruct function
205 * @nfmark: Can be used for communication between hooks
206 * @nfct: Associated connection, if any
207 * @ipvs_property: skbuff is owned by ipvs
208 * @nfctinfo: Relationship of this skb to the connection
209 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
210 * @tc_index: Traffic control index
211 * @tc_verd: traffic control verdict
215 /* These two members must be first. */
216 struct sk_buff
*next
;
217 struct sk_buff
*prev
;
220 struct skb_timeval tstamp
;
221 struct net_device
*dev
;
222 struct net_device
*input_dev
;
227 struct icmphdr
*icmph
;
228 struct igmphdr
*igmph
;
230 struct ipv6hdr
*ipv6h
;
236 struct ipv6hdr
*ipv6h
;
245 struct dst_entry
*dst
;
249 * This is the control buffer. It is free to use for every
250 * layer. Please put your private variables there. If you
251 * want to keep them across layers you have to do a skb_clone()
252 * first. This is owned by whoever has the skb queued ATM.
270 void (*destructor
)(struct sk_buff
*skb
);
271 #ifdef CONFIG_NETFILTER
273 struct nf_conntrack
*nfct
;
274 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
275 __u8 ipvs_property
:1;
277 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
278 struct sk_buff
*nfct_reasm
;
280 #ifdef CONFIG_BRIDGE_NETFILTER
281 struct nf_bridge_info
*nf_bridge
;
283 #endif /* CONFIG_NETFILTER */
284 #ifdef CONFIG_NET_SCHED
285 __u16 tc_index
; /* traffic control index */
286 #ifdef CONFIG_NET_CLS_ACT
287 __u16 tc_verd
; /* traffic control verdict */
292 /* These elements must be at the end, see alloc_skb() for details. */
293 unsigned int truesize
;
303 * Handling routines are only of interest to the kernel
305 #include <linux/slab.h>
307 #include <asm/system.h>
309 extern void __kfree_skb(struct sk_buff
*skb
);
310 extern struct sk_buff
*__alloc_skb(unsigned int size
,
311 gfp_t priority
, int fclone
);
312 static inline struct sk_buff
*alloc_skb(unsigned int size
,
315 return __alloc_skb(size
, priority
, 0);
318 static inline struct sk_buff
*alloc_skb_fclone(unsigned int size
,
321 return __alloc_skb(size
, priority
, 1);
324 extern struct sk_buff
*alloc_skb_from_cache(kmem_cache_t
*cp
,
327 extern void kfree_skbmem(struct sk_buff
*skb
);
328 extern struct sk_buff
*skb_clone(struct sk_buff
*skb
,
330 extern struct sk_buff
*skb_copy(const struct sk_buff
*skb
,
332 extern struct sk_buff
*pskb_copy(struct sk_buff
*skb
,
334 extern int pskb_expand_head(struct sk_buff
*skb
,
335 int nhead
, int ntail
,
337 extern struct sk_buff
*skb_realloc_headroom(struct sk_buff
*skb
,
338 unsigned int headroom
);
339 extern struct sk_buff
*skb_copy_expand(const struct sk_buff
*skb
,
340 int newheadroom
, int newtailroom
,
342 extern struct sk_buff
* skb_pad(struct sk_buff
*skb
, int pad
);
343 #define dev_kfree_skb(a) kfree_skb(a)
344 extern void skb_over_panic(struct sk_buff
*skb
, int len
,
346 extern void skb_under_panic(struct sk_buff
*skb
, int len
,
349 extern int skb_append_datato_frags(struct sock
*sk
, struct sk_buff
*skb
,
350 int getfrag(void *from
, char *to
, int offset
,
351 int len
,int odd
, struct sk_buff
*skb
),
352 void *from
, int length
);
359 __u32 stepped_offset
;
360 struct sk_buff
*root_skb
;
361 struct sk_buff
*cur_skb
;
365 extern void skb_prepare_seq_read(struct sk_buff
*skb
,
366 unsigned int from
, unsigned int to
,
367 struct skb_seq_state
*st
);
368 extern unsigned int skb_seq_read(unsigned int consumed
, const u8
**data
,
369 struct skb_seq_state
*st
);
370 extern void skb_abort_seq_read(struct skb_seq_state
*st
);
372 extern unsigned int skb_find_text(struct sk_buff
*skb
, unsigned int from
,
373 unsigned int to
, struct ts_config
*config
,
374 struct ts_state
*state
);
377 #define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
380 * skb_queue_empty - check if a queue is empty
383 * Returns true if the queue is empty, false otherwise.
385 static inline int skb_queue_empty(const struct sk_buff_head
*list
)
387 return list
->next
== (struct sk_buff
*)list
;
391 * skb_get - reference buffer
392 * @skb: buffer to reference
394 * Makes another reference to a socket buffer and returns a pointer
397 static inline struct sk_buff
*skb_get(struct sk_buff
*skb
)
399 atomic_inc(&skb
->users
);
404 * If users == 1, we are the only owner and are can avoid redundant
409 * kfree_skb - free an sk_buff
410 * @skb: buffer to free
412 * Drop a reference to the buffer and free it if the usage count has
415 static inline void kfree_skb(struct sk_buff
*skb
)
417 if (likely(atomic_read(&skb
->users
) == 1))
419 else if (likely(!atomic_dec_and_test(&skb
->users
)))
425 * skb_cloned - is the buffer a clone
426 * @skb: buffer to check
428 * Returns true if the buffer was generated with skb_clone() and is
429 * one of multiple shared copies of the buffer. Cloned buffers are
430 * shared data so must not be written to under normal circumstances.
432 static inline int skb_cloned(const struct sk_buff
*skb
)
434 return skb
->cloned
&&
435 (atomic_read(&skb_shinfo(skb
)->dataref
) & SKB_DATAREF_MASK
) != 1;
439 * skb_header_cloned - is the header a clone
440 * @skb: buffer to check
442 * Returns true if modifying the header part of the buffer requires
443 * the data to be copied.
445 static inline int skb_header_cloned(const struct sk_buff
*skb
)
452 dataref
= atomic_read(&skb_shinfo(skb
)->dataref
);
453 dataref
= (dataref
& SKB_DATAREF_MASK
) - (dataref
>> SKB_DATAREF_SHIFT
);
458 * skb_header_release - release reference to header
459 * @skb: buffer to operate on
461 * Drop a reference to the header part of the buffer. This is done
462 * by acquiring a payload reference. You must not read from the header
463 * part of skb->data after this.
465 static inline void skb_header_release(struct sk_buff
*skb
)
469 atomic_add(1 << SKB_DATAREF_SHIFT
, &skb_shinfo(skb
)->dataref
);
473 * skb_shared - is the buffer shared
474 * @skb: buffer to check
476 * Returns true if more than one person has a reference to this
479 static inline int skb_shared(const struct sk_buff
*skb
)
481 return atomic_read(&skb
->users
) != 1;
485 * skb_share_check - check if buffer is shared and if so clone it
486 * @skb: buffer to check
487 * @pri: priority for memory allocation
489 * If the buffer is shared the buffer is cloned and the old copy
490 * drops a reference. A new clone with a single reference is returned.
491 * If the buffer is not shared the original buffer is returned. When
492 * being called from interrupt status or with spinlocks held pri must
495 * NULL is returned on a memory allocation failure.
497 static inline struct sk_buff
*skb_share_check(struct sk_buff
*skb
,
500 might_sleep_if(pri
& __GFP_WAIT
);
501 if (skb_shared(skb
)) {
502 struct sk_buff
*nskb
= skb_clone(skb
, pri
);
510 * Copy shared buffers into a new sk_buff. We effectively do COW on
511 * packets to handle cases where we have a local reader and forward
512 * and a couple of other messy ones. The normal one is tcpdumping
513 * a packet thats being forwarded.
517 * skb_unshare - make a copy of a shared buffer
518 * @skb: buffer to check
519 * @pri: priority for memory allocation
521 * If the socket buffer is a clone then this function creates a new
522 * copy of the data, drops a reference count on the old copy and returns
523 * the new copy with the reference count at 1. If the buffer is not a clone
524 * the original buffer is returned. When called with a spinlock held or
525 * from interrupt state @pri must be %GFP_ATOMIC
527 * %NULL is returned on a memory allocation failure.
529 static inline struct sk_buff
*skb_unshare(struct sk_buff
*skb
,
532 might_sleep_if(pri
& __GFP_WAIT
);
533 if (skb_cloned(skb
)) {
534 struct sk_buff
*nskb
= skb_copy(skb
, pri
);
535 kfree_skb(skb
); /* Free our shared copy */
543 * @list_: list to peek at
545 * Peek an &sk_buff. Unlike most other operations you _MUST_
546 * be careful with this one. A peek leaves the buffer on the
547 * list and someone else may run off with it. You must hold
548 * the appropriate locks or have a private queue to do this.
550 * Returns %NULL for an empty list or a pointer to the head element.
551 * The reference count is not incremented and the reference is therefore
552 * volatile. Use with caution.
554 static inline struct sk_buff
*skb_peek(struct sk_buff_head
*list_
)
556 struct sk_buff
*list
= ((struct sk_buff
*)list_
)->next
;
557 if (list
== (struct sk_buff
*)list_
)
564 * @list_: list to peek at
566 * Peek an &sk_buff. Unlike most other operations you _MUST_
567 * be careful with this one. A peek leaves the buffer on the
568 * list and someone else may run off with it. You must hold
569 * the appropriate locks or have a private queue to do this.
571 * Returns %NULL for an empty list or a pointer to the tail element.
572 * The reference count is not incremented and the reference is therefore
573 * volatile. Use with caution.
575 static inline struct sk_buff
*skb_peek_tail(struct sk_buff_head
*list_
)
577 struct sk_buff
*list
= ((struct sk_buff
*)list_
)->prev
;
578 if (list
== (struct sk_buff
*)list_
)
584 * skb_queue_len - get queue length
585 * @list_: list to measure
587 * Return the length of an &sk_buff queue.
589 static inline __u32
skb_queue_len(const struct sk_buff_head
*list_
)
594 static inline void skb_queue_head_init(struct sk_buff_head
*list
)
596 spin_lock_init(&list
->lock
);
597 list
->prev
= list
->next
= (struct sk_buff
*)list
;
602 * Insert an sk_buff at the start of a list.
604 * The "__skb_xxxx()" functions are the non-atomic ones that
605 * can only be called with interrupts disabled.
609 * __skb_queue_after - queue a buffer at the list head
611 * @prev: place after this buffer
612 * @newsk: buffer to queue
614 * Queue a buffer int the middle of a list. This function takes no locks
615 * and you must therefore hold required locks before calling it.
617 * A buffer cannot be placed on two lists at the same time.
619 static inline void __skb_queue_after(struct sk_buff_head
*list
,
620 struct sk_buff
*prev
,
621 struct sk_buff
*newsk
)
623 struct sk_buff
*next
;
629 next
->prev
= prev
->next
= newsk
;
633 * __skb_queue_head - queue a buffer at the list head
635 * @newsk: buffer to queue
637 * Queue a buffer at the start of a list. This function takes no locks
638 * and you must therefore hold required locks before calling it.
640 * A buffer cannot be placed on two lists at the same time.
642 extern void skb_queue_head(struct sk_buff_head
*list
, struct sk_buff
*newsk
);
643 static inline void __skb_queue_head(struct sk_buff_head
*list
,
644 struct sk_buff
*newsk
)
646 __skb_queue_after(list
, (struct sk_buff
*)list
, newsk
);
650 * __skb_queue_tail - queue a buffer at the list tail
652 * @newsk: buffer to queue
654 * Queue a buffer at the end of a list. This function takes no locks
655 * and you must therefore hold required locks before calling it.
657 * A buffer cannot be placed on two lists at the same time.
659 extern void skb_queue_tail(struct sk_buff_head
*list
, struct sk_buff
*newsk
);
660 static inline void __skb_queue_tail(struct sk_buff_head
*list
,
661 struct sk_buff
*newsk
)
663 struct sk_buff
*prev
, *next
;
666 next
= (struct sk_buff
*)list
;
670 next
->prev
= prev
->next
= newsk
;
675 * __skb_dequeue - remove from the head of the queue
676 * @list: list to dequeue from
678 * Remove the head of the list. This function does not take any locks
679 * so must be used with appropriate locks held only. The head item is
680 * returned or %NULL if the list is empty.
682 extern struct sk_buff
*skb_dequeue(struct sk_buff_head
*list
);
683 static inline struct sk_buff
*__skb_dequeue(struct sk_buff_head
*list
)
685 struct sk_buff
*next
, *prev
, *result
;
687 prev
= (struct sk_buff
*) list
;
696 result
->next
= result
->prev
= NULL
;
703 * Insert a packet on a list.
705 extern void skb_insert(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
);
706 static inline void __skb_insert(struct sk_buff
*newsk
,
707 struct sk_buff
*prev
, struct sk_buff
*next
,
708 struct sk_buff_head
*list
)
712 next
->prev
= prev
->next
= newsk
;
717 * Place a packet after a given packet in a list.
719 extern void skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
);
720 static inline void __skb_append(struct sk_buff
*old
, struct sk_buff
*newsk
, struct sk_buff_head
*list
)
722 __skb_insert(newsk
, old
, old
->next
, list
);
726 * remove sk_buff from list. _Must_ be called atomically, and with
729 extern void skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
);
730 static inline void __skb_unlink(struct sk_buff
*skb
, struct sk_buff_head
*list
)
732 struct sk_buff
*next
, *prev
;
737 skb
->next
= skb
->prev
= NULL
;
743 /* XXX: more streamlined implementation */
746 * __skb_dequeue_tail - remove from the tail of the queue
747 * @list: list to dequeue from
749 * Remove the tail of the list. This function does not take any locks
750 * so must be used with appropriate locks held only. The tail item is
751 * returned or %NULL if the list is empty.
753 extern struct sk_buff
*skb_dequeue_tail(struct sk_buff_head
*list
);
754 static inline struct sk_buff
*__skb_dequeue_tail(struct sk_buff_head
*list
)
756 struct sk_buff
*skb
= skb_peek_tail(list
);
758 __skb_unlink(skb
, list
);
763 static inline int skb_is_nonlinear(const struct sk_buff
*skb
)
765 return skb
->data_len
;
768 static inline unsigned int skb_headlen(const struct sk_buff
*skb
)
770 return skb
->len
- skb
->data_len
;
773 static inline int skb_pagelen(const struct sk_buff
*skb
)
777 for (i
= (int)skb_shinfo(skb
)->nr_frags
- 1; i
>= 0; i
--)
778 len
+= skb_shinfo(skb
)->frags
[i
].size
;
779 return len
+ skb_headlen(skb
);
782 static inline void skb_fill_page_desc(struct sk_buff
*skb
, int i
,
783 struct page
*page
, int off
, int size
)
785 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
788 frag
->page_offset
= off
;
790 skb_shinfo(skb
)->nr_frags
= i
+ 1;
793 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
794 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
795 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
798 * Add data to an sk_buff
800 static inline unsigned char *__skb_put(struct sk_buff
*skb
, unsigned int len
)
802 unsigned char *tmp
= skb
->tail
;
803 SKB_LINEAR_ASSERT(skb
);
810 * skb_put - add data to a buffer
811 * @skb: buffer to use
812 * @len: amount of data to add
814 * This function extends the used data area of the buffer. If this would
815 * exceed the total buffer size the kernel will panic. A pointer to the
816 * first byte of the extra data is returned.
818 static inline unsigned char *skb_put(struct sk_buff
*skb
, unsigned int len
)
820 unsigned char *tmp
= skb
->tail
;
821 SKB_LINEAR_ASSERT(skb
);
824 if (unlikely(skb
->tail
>skb
->end
))
825 skb_over_panic(skb
, len
, current_text_addr());
829 static inline unsigned char *__skb_push(struct sk_buff
*skb
, unsigned int len
)
837 * skb_push - add data to the start of a buffer
838 * @skb: buffer to use
839 * @len: amount of data to add
841 * This function extends the used data area of the buffer at the buffer
842 * start. If this would exceed the total buffer headroom the kernel will
843 * panic. A pointer to the first byte of the extra data is returned.
845 static inline unsigned char *skb_push(struct sk_buff
*skb
, unsigned int len
)
849 if (unlikely(skb
->data
<skb
->head
))
850 skb_under_panic(skb
, len
, current_text_addr());
854 static inline unsigned char *__skb_pull(struct sk_buff
*skb
, unsigned int len
)
857 BUG_ON(skb
->len
< skb
->data_len
);
858 return skb
->data
+= len
;
862 * skb_pull - remove data from the start of a buffer
863 * @skb: buffer to use
864 * @len: amount of data to remove
866 * This function removes data from the start of a buffer, returning
867 * the memory to the headroom. A pointer to the next data in the buffer
868 * is returned. Once the data has been pulled future pushes will overwrite
871 static inline unsigned char *skb_pull(struct sk_buff
*skb
, unsigned int len
)
873 return unlikely(len
> skb
->len
) ? NULL
: __skb_pull(skb
, len
);
876 extern unsigned char *__pskb_pull_tail(struct sk_buff
*skb
, int delta
);
878 static inline unsigned char *__pskb_pull(struct sk_buff
*skb
, unsigned int len
)
880 if (len
> skb_headlen(skb
) &&
881 !__pskb_pull_tail(skb
, len
-skb_headlen(skb
)))
884 return skb
->data
+= len
;
887 static inline unsigned char *pskb_pull(struct sk_buff
*skb
, unsigned int len
)
889 return unlikely(len
> skb
->len
) ? NULL
: __pskb_pull(skb
, len
);
892 static inline int pskb_may_pull(struct sk_buff
*skb
, unsigned int len
)
894 if (likely(len
<= skb_headlen(skb
)))
896 if (unlikely(len
> skb
->len
))
898 return __pskb_pull_tail(skb
, len
-skb_headlen(skb
)) != NULL
;
902 * skb_headroom - bytes at buffer head
903 * @skb: buffer to check
905 * Return the number of bytes of free space at the head of an &sk_buff.
907 static inline int skb_headroom(const struct sk_buff
*skb
)
909 return skb
->data
- skb
->head
;
913 * skb_tailroom - bytes at buffer end
914 * @skb: buffer to check
916 * Return the number of bytes of free space at the tail of an sk_buff
918 static inline int skb_tailroom(const struct sk_buff
*skb
)
920 return skb_is_nonlinear(skb
) ? 0 : skb
->end
- skb
->tail
;
924 * skb_reserve - adjust headroom
925 * @skb: buffer to alter
926 * @len: bytes to move
928 * Increase the headroom of an empty &sk_buff by reducing the tail
929 * room. This is only allowed for an empty buffer.
931 static inline void skb_reserve(struct sk_buff
*skb
, unsigned int len
)
938 * CPUs often take a performance hit when accessing unaligned memory
939 * locations. The actual performance hit varies, it can be small if the
940 * hardware handles it or large if we have to take an exception and fix it
943 * Since an ethernet header is 14 bytes network drivers often end up with
944 * the IP header at an unaligned offset. The IP header can be aligned by
945 * shifting the start of the packet by 2 bytes. Drivers should do this
948 * skb_reserve(NET_IP_ALIGN);
950 * The downside to this alignment of the IP header is that the DMA is now
951 * unaligned. On some architectures the cost of an unaligned DMA is high
952 * and this cost outweighs the gains made by aligning the IP header.
954 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
958 #define NET_IP_ALIGN 2
961 extern int ___pskb_trim(struct sk_buff
*skb
, unsigned int len
, int realloc
);
963 static inline void __skb_trim(struct sk_buff
*skb
, unsigned int len
)
965 if (!skb
->data_len
) {
967 skb
->tail
= skb
->data
+ len
;
969 ___pskb_trim(skb
, len
, 0);
973 * skb_trim - remove end from a buffer
974 * @skb: buffer to alter
977 * Cut the length of a buffer down by removing data from the tail. If
978 * the buffer is already under the length specified it is not modified.
980 static inline void skb_trim(struct sk_buff
*skb
, unsigned int len
)
983 __skb_trim(skb
, len
);
987 static inline int __pskb_trim(struct sk_buff
*skb
, unsigned int len
)
989 if (!skb
->data_len
) {
991 skb
->tail
= skb
->data
+len
;
994 return ___pskb_trim(skb
, len
, 1);
997 static inline int pskb_trim(struct sk_buff
*skb
, unsigned int len
)
999 return (len
< skb
->len
) ? __pskb_trim(skb
, len
) : 0;
1003 * skb_orphan - orphan a buffer
1004 * @skb: buffer to orphan
1006 * If a buffer currently has an owner then we call the owner's
1007 * destructor function and make the @skb unowned. The buffer continues
1008 * to exist but is no longer charged to its former owner.
1010 static inline void skb_orphan(struct sk_buff
*skb
)
1012 if (skb
->destructor
)
1013 skb
->destructor(skb
);
1014 skb
->destructor
= NULL
;
1019 * __skb_queue_purge - empty a list
1020 * @list: list to empty
1022 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1023 * the list and one reference dropped. This function does not take the
1024 * list lock and the caller must hold the relevant locks to use it.
1026 extern void skb_queue_purge(struct sk_buff_head
*list
);
1027 static inline void __skb_queue_purge(struct sk_buff_head
*list
)
1029 struct sk_buff
*skb
;
1030 while ((skb
= __skb_dequeue(list
)) != NULL
)
1034 #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
1036 * __dev_alloc_skb - allocate an skbuff for sending
1037 * @length: length to allocate
1038 * @gfp_mask: get_free_pages mask, passed to alloc_skb
1040 * Allocate a new &sk_buff and assign it a usage count of one. The
1041 * buffer has unspecified headroom built in. Users should allocate
1042 * the headroom they think they need without accounting for the
1043 * built in space. The built in space is used for optimisations.
1045 * %NULL is returned in there is no free memory.
1047 static inline struct sk_buff
*__dev_alloc_skb(unsigned int length
,
1050 struct sk_buff
*skb
= alloc_skb(length
+ 16, gfp_mask
);
1052 skb_reserve(skb
, 16);
1056 extern struct sk_buff
*__dev_alloc_skb(unsigned int length
, int gfp_mask
);
1060 * dev_alloc_skb - allocate an skbuff for sending
1061 * @length: length to allocate
1063 * Allocate a new &sk_buff and assign it a usage count of one. The
1064 * buffer has unspecified headroom built in. Users should allocate
1065 * the headroom they think they need without accounting for the
1066 * built in space. The built in space is used for optimisations.
1068 * %NULL is returned in there is no free memory. Although this function
1069 * allocates memory it can be called from an interrupt.
1071 static inline struct sk_buff
*dev_alloc_skb(unsigned int length
)
1073 return __dev_alloc_skb(length
, GFP_ATOMIC
);
1077 * skb_cow - copy header of skb when it is required
1078 * @skb: buffer to cow
1079 * @headroom: needed headroom
1081 * If the skb passed lacks sufficient headroom or its data part
1082 * is shared, data is reallocated. If reallocation fails, an error
1083 * is returned and original skb is not changed.
1085 * The result is skb with writable area skb->head...skb->tail
1086 * and at least @headroom of space at head.
1088 static inline int skb_cow(struct sk_buff
*skb
, unsigned int headroom
)
1090 int delta
= (headroom
> 16 ? headroom
: 16) - skb_headroom(skb
);
1095 if (delta
|| skb_cloned(skb
))
1096 return pskb_expand_head(skb
, (delta
+ 15) & ~15, 0, GFP_ATOMIC
);
1101 * skb_padto - pad an skbuff up to a minimal size
1102 * @skb: buffer to pad
1103 * @len: minimal length
1105 * Pads up a buffer to ensure the trailing bytes exist and are
1106 * blanked. If the buffer already contains sufficient data it
1107 * is untouched. Returns the buffer, which may be a replacement
1108 * for the original, or NULL for out of memory - in which case
1109 * the original buffer is still freed.
1112 static inline struct sk_buff
*skb_padto(struct sk_buff
*skb
, unsigned int len
)
1114 unsigned int size
= skb
->len
;
1115 if (likely(size
>= len
))
1117 return skb_pad(skb
, len
-size
);
1120 static inline int skb_add_data(struct sk_buff
*skb
,
1121 char __user
*from
, int copy
)
1123 const int off
= skb
->len
;
1125 if (skb
->ip_summed
== CHECKSUM_NONE
) {
1127 unsigned int csum
= csum_and_copy_from_user(from
,
1131 skb
->csum
= csum_block_add(skb
->csum
, csum
, off
);
1134 } else if (!copy_from_user(skb_put(skb
, copy
), from
, copy
))
1137 __skb_trim(skb
, off
);
1141 static inline int skb_can_coalesce(struct sk_buff
*skb
, int i
,
1142 struct page
*page
, int off
)
1145 struct skb_frag_struct
*frag
= &skb_shinfo(skb
)->frags
[i
- 1];
1147 return page
== frag
->page
&&
1148 off
== frag
->page_offset
+ frag
->size
;
1154 * skb_linearize - convert paged skb to linear one
1155 * @skb: buffer to linarize
1156 * @gfp: allocation mode
1158 * If there is no free memory -ENOMEM is returned, otherwise zero
1159 * is returned and the old skb data released.
1161 extern int __skb_linearize(struct sk_buff
*skb
, gfp_t gfp
);
1162 static inline int skb_linearize(struct sk_buff
*skb
, gfp_t gfp
)
1164 return __skb_linearize(skb
, gfp
);
1168 * skb_postpull_rcsum - update checksum for received skb after pull
1169 * @skb: buffer to update
1170 * @start: start of data before pull
1171 * @len: length of data pulled
1173 * After doing a pull on a received packet, you need to call this to
1174 * update the CHECKSUM_HW checksum, or set ip_summed to CHECKSUM_NONE
1175 * so that it can be recomputed from scratch.
1178 static inline void skb_postpull_rcsum(struct sk_buff
*skb
,
1179 const void *start
, int len
)
1181 if (skb
->ip_summed
== CHECKSUM_HW
)
1182 skb
->csum
= csum_sub(skb
->csum
, csum_partial(start
, len
, 0));
1186 * pskb_trim_rcsum - trim received skb and update checksum
1187 * @skb: buffer to trim
1190 * This is exactly the same as pskb_trim except that it ensures the
1191 * checksum of received packets are still valid after the operation.
1194 static inline int pskb_trim_rcsum(struct sk_buff
*skb
, unsigned int len
)
1196 if (likely(len
>= skb
->len
))
1198 if (skb
->ip_summed
== CHECKSUM_HW
)
1199 skb
->ip_summed
= CHECKSUM_NONE
;
1200 return __pskb_trim(skb
, len
);
1203 static inline void *kmap_skb_frag(const skb_frag_t
*frag
)
1205 #ifdef CONFIG_HIGHMEM
1210 return kmap_atomic(frag
->page
, KM_SKB_DATA_SOFTIRQ
);
1213 static inline void kunmap_skb_frag(void *vaddr
)
1215 kunmap_atomic(vaddr
, KM_SKB_DATA_SOFTIRQ
);
1216 #ifdef CONFIG_HIGHMEM
1221 #define skb_queue_walk(queue, skb) \
1222 for (skb = (queue)->next; \
1223 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1226 #define skb_queue_reverse_walk(queue, skb) \
1227 for (skb = (queue)->prev; \
1228 prefetch(skb->prev), (skb != (struct sk_buff *)(queue)); \
1232 extern struct sk_buff
*skb_recv_datagram(struct sock
*sk
, unsigned flags
,
1233 int noblock
, int *err
);
1234 extern unsigned int datagram_poll(struct file
*file
, struct socket
*sock
,
1235 struct poll_table_struct
*wait
);
1236 extern int skb_copy_datagram_iovec(const struct sk_buff
*from
,
1237 int offset
, struct iovec
*to
,
1239 extern int skb_copy_and_csum_datagram_iovec(struct sk_buff
*skb
,
1242 extern void skb_free_datagram(struct sock
*sk
, struct sk_buff
*skb
);
1243 extern unsigned int skb_checksum(const struct sk_buff
*skb
, int offset
,
1244 int len
, unsigned int csum
);
1245 extern int skb_copy_bits(const struct sk_buff
*skb
, int offset
,
1247 extern int skb_store_bits(const struct sk_buff
*skb
, int offset
,
1248 void *from
, int len
);
1249 extern unsigned int skb_copy_and_csum_bits(const struct sk_buff
*skb
,
1250 int offset
, u8
*to
, int len
,
1252 extern void skb_copy_and_csum_dev(const struct sk_buff
*skb
, u8
*to
);
1253 extern void skb_split(struct sk_buff
*skb
,
1254 struct sk_buff
*skb1
, const u32 len
);
1256 extern void skb_release_data(struct sk_buff
*skb
);
1258 static inline void *skb_header_pointer(const struct sk_buff
*skb
, int offset
,
1259 int len
, void *buffer
)
1261 int hlen
= skb_headlen(skb
);
1263 if (hlen
- offset
>= len
)
1264 return skb
->data
+ offset
;
1266 if (skb_copy_bits(skb
, offset
, buffer
, len
) < 0)
1272 extern void skb_init(void);
1273 extern void skb_add_mtu(int mtu
);
1276 * skb_get_timestamp - get timestamp from a skb
1277 * @skb: skb to get stamp from
1278 * @stamp: pointer to struct timeval to store stamp in
1280 * Timestamps are stored in the skb as offsets to a base timestamp.
1281 * This function converts the offset back to a struct timeval and stores
1284 static inline void skb_get_timestamp(const struct sk_buff
*skb
, struct timeval
*stamp
)
1286 stamp
->tv_sec
= skb
->tstamp
.off_sec
;
1287 stamp
->tv_usec
= skb
->tstamp
.off_usec
;
1291 * skb_set_timestamp - set timestamp of a skb
1292 * @skb: skb to set stamp of
1293 * @stamp: pointer to struct timeval to get stamp from
1295 * Timestamps are stored in the skb as offsets to a base timestamp.
1296 * This function converts a struct timeval to an offset and stores
1299 static inline void skb_set_timestamp(struct sk_buff
*skb
, const struct timeval
*stamp
)
1301 skb
->tstamp
.off_sec
= stamp
->tv_sec
;
1302 skb
->tstamp
.off_usec
= stamp
->tv_usec
;
1305 extern void __net_timestamp(struct sk_buff
*skb
);
1307 extern unsigned int __skb_checksum_complete(struct sk_buff
*skb
);
1310 * skb_checksum_complete - Calculate checksum of an entire packet
1311 * @skb: packet to process
1313 * This function calculates the checksum over the entire packet plus
1314 * the value of skb->csum. The latter can be used to supply the
1315 * checksum of a pseudo header as used by TCP/UDP. It returns the
1318 * For protocols that contain complete checksums such as ICMP/TCP/UDP,
1319 * this function can be used to verify that checksum on received
1320 * packets. In that case the function should return zero if the
1321 * checksum is correct. In particular, this function will return zero
1322 * if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
1323 * hardware has already verified the correctness of the checksum.
1325 static inline unsigned int skb_checksum_complete(struct sk_buff
*skb
)
1327 return skb
->ip_summed
!= CHECKSUM_UNNECESSARY
&&
1328 __skb_checksum_complete(skb
);
1331 #ifdef CONFIG_NETFILTER
1332 static inline void nf_conntrack_put(struct nf_conntrack
*nfct
)
1334 if (nfct
&& atomic_dec_and_test(&nfct
->use
))
1335 nfct
->destroy(nfct
);
1337 static inline void nf_conntrack_get(struct nf_conntrack
*nfct
)
1340 atomic_inc(&nfct
->use
);
1342 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1343 static inline void nf_conntrack_get_reasm(struct sk_buff
*skb
)
1346 atomic_inc(&skb
->users
);
1348 static inline void nf_conntrack_put_reasm(struct sk_buff
*skb
)
1354 static inline void nf_reset(struct sk_buff
*skb
)
1356 nf_conntrack_put(skb
->nfct
);
1358 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1359 nf_conntrack_put_reasm(skb
->nfct_reasm
);
1360 skb
->nfct_reasm
= NULL
;
1364 #ifdef CONFIG_BRIDGE_NETFILTER
1365 static inline void nf_bridge_put(struct nf_bridge_info
*nf_bridge
)
1367 if (nf_bridge
&& atomic_dec_and_test(&nf_bridge
->use
))
1370 static inline void nf_bridge_get(struct nf_bridge_info
*nf_bridge
)
1373 atomic_inc(&nf_bridge
->use
);
1375 #endif /* CONFIG_BRIDGE_NETFILTER */
1376 #else /* CONFIG_NETFILTER */
1377 static inline void nf_reset(struct sk_buff
*skb
) {}
1378 #endif /* CONFIG_NETFILTER */
1380 #endif /* __KERNEL__ */
1381 #endif /* _LINUX_SKBUFF_H */