/*
   *	Definitions for the 'struct sk_buff' memory handlers.
   *
   *	Authors:
   *		Alan Cox, <gw4pts@gw4pts.ampr.org>
   *		Florian La Roche, <rzsfl@rz.uni-sb.de>
   *
   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License
   *	as published by the Free Software Foundation; either version
   *	2 of the License, or (at your option) any later version.
   */
  
  #ifndef _LINUX_SKBUFF_H
  #define _LINUX_SKBUFF_H

  #include <linux/kernel.h>
  #include <linux/compiler.h>
  #include <linux/time.h>
  #include <linux/cache.h>
  
  #include <asm/atomic.h>
  #include <asm/types.h>
  #include <linux/spinlock.h>

  #include <linux/net.h>

  #include <linux/textsearch.h>

  #include <net/checksum.h>

  #include <linux/rcupdate.h>

  #include <linux/dmaengine.h>

  #include <linux/hrtimer.h>

  
  #define HAVE_ALLOC_SKB		/* For the drivers to know */
  #define HAVE_ALIGNABLE_SKB	/* Ditto 8)		   */

  
  #define CHECKSUM_NONE 0

  #define CHECKSUM_PARTIAL 1

  #define CHECKSUM_UNNECESSARY 2

  #define CHECKSUM_COMPLETE 3

  
  #define SKB_DATA_ALIGN(X)	(((X) + (SMP_CACHE_BYTES - 1)) & \
  				 ~(SMP_CACHE_BYTES - 1))

  #define SKB_WITH_OVERHEAD(X)	\
  	(((X) - sizeof(struct skb_shared_info)) & \
  	 ~(SMP_CACHE_BYTES - 1))
  #define SKB_MAX_ORDER(X, ORDER) \
  	SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))

  #define SKB_MAX_HEAD(X)		(SKB_MAX_ORDER((X), 0))
  #define SKB_MAX_ALLOC		(SKB_MAX_ORDER(0, 2))
  
  /* A. Checksumming of received packets by device.
   *
   *	NONE: device failed to checksum this packet.
   *		skb->csum is undefined.
   *
   *	UNNECESSARY: device parsed packet and wouldbe verified checksum.
   *		skb->csum is undefined.
   *	      It is bad option, but, unfortunately, many of vendors do this.
   *	      Apparently with secret goal to sell you new device, when you
   *	      will add new protocol to your host. F.e. IPv6. 8)
   *

   *	COMPLETE: the most generic way. Device supplied checksum of _all_

   *	    the packet as seen by netif_rx in skb->csum.
   *	    NOTE: Even if device supports only some protocols, but

   *	    is able to produce some skb->csum, it MUST use COMPLETE,

   *	    not UNNECESSARY.
   *
   * B. Checksumming on output.
   *
   *	NONE: skb is checksummed by protocol or csum is not required.
   *

   *	PARTIAL: device is required to csum packet as seen by hard_start_xmit

   *	from skb->transport_header to the end and to record the checksum
   *	at skb->transport_header + skb->csum.

   *
   *	Device must show its capabilities in dev->features, set
   *	at device setup time.
   *	NETIF_F_HW_CSUM	- it is clever device, it is able to checksum
   *			  everything.
   *	NETIF_F_NO_CSUM - loopback or reliable single hop media.
   *	NETIF_F_IP_CSUM - device is dumb. It is able to csum only
   *			  TCP/UDP over IPv4. Sigh. Vendors like this
   *			  way by an unknown reason. Though, see comment above
   *			  about CHECKSUM_UNNECESSARY. 8)
   *
   *	Any questions? No questions, good. 		--ANK
   */

  struct net_device;

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  struct nf_conntrack {
  	atomic_t use;

  };

  #endif

  
  #ifdef CONFIG_BRIDGE_NETFILTER
  struct nf_bridge_info {
  	atomic_t use;
  	struct net_device *physindev;
  	struct net_device *physoutdev;
  #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
  	struct net_device *netoutdev;
  #endif
  	unsigned int mask;
  	unsigned long data[32 / sizeof(unsigned long)];
  };
  #endif

  struct sk_buff_head {
  	/* These two members must be first. */
  	struct sk_buff	*next;
  	struct sk_buff	*prev;
  
  	__u32		qlen;
  	spinlock_t	lock;
  };
  
  struct sk_buff;
  
  /* To allow 64K frame to be packed as single skb without frag_list */
  #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
  
  typedef struct skb_frag_struct skb_frag_t;
  
  struct skb_frag_struct {
  	struct page *page;
  	__u16 page_offset;
  	__u16 size;
  };
  
  /* This data is invariant across clones and lives at
   * the end of the header data, ie. at skb->end.
   */
  struct skb_shared_info {
  	atomic_t	dataref;

  	unsigned short	nr_frags;

  	unsigned short	gso_size;
  	/* Warning: this field is not always filled in (UFO)! */
  	unsigned short	gso_segs;
  	unsigned short  gso_type;

  	__be32          ip6_frag_id;

  	struct sk_buff	*frag_list;
  	skb_frag_t	frags[MAX_SKB_FRAGS];
  };
  
  /* We divide dataref into two halves.  The higher 16 bits hold references
   * to the payload part of skb->data.  The lower 16 bits hold references to
   * the entire skb->data.  It is up to the users of the skb to agree on
   * where the payload starts.
   *
   * All users must obey the rule that the skb->data reference count must be
   * greater than or equal to the payload reference count.
   *
   * Holding a reference to the payload part means that the user does not
   * care about modifications to the header part of skb->data.
   */
  #define SKB_DATAREF_SHIFT 16
  #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)

  
  enum {
  	SKB_FCLONE_UNAVAILABLE,
  	SKB_FCLONE_ORIG,
  	SKB_FCLONE_CLONE,
  };

  enum {
  	SKB_GSO_TCPV4 = 1 << 0,

  	SKB_GSO_UDP = 1 << 1,

  
  	/* This indicates the skb is from an untrusted source. */
  	SKB_GSO_DODGY = 1 << 2,

  
  	/* This indicates the tcp segment has CWR set. */

  	SKB_GSO_TCP_ECN = 1 << 3,
  
  	SKB_GSO_TCPV6 = 1 << 4,

  };

  #if BITS_PER_LONG > 32
  #define NET_SKBUFF_DATA_USES_OFFSET 1
  #endif
  
  #ifdef NET_SKBUFF_DATA_USES_OFFSET
  typedef unsigned int sk_buff_data_t;
  #else
  typedef unsigned char *sk_buff_data_t;
  #endif

  /** 
   *	struct sk_buff - socket buffer
   *	@next: Next buffer in list
   *	@prev: Previous buffer in list

   *	@sk: Socket we are owned by

   *	@tstamp: Time we arrived

   *	@dev: Device we arrived on/are leaving by

   *	@iif: ifindex of device we arrived on

   *	@h: Transport layer header

   *	@network_header: Network layer header
   *	@mac_header: Link layer header

   *	@dst: destination entry
   *	@sp: the security path, used for xfrm

   *	@cb: Control buffer. Free for use by every layer. Put private vars here
   *	@len: Length of actual data
   *	@data_len: Data length
   *	@mac_len: Length of link layer header
   *	@csum: Checksum

   *	@local_df: allow local fragmentation

   *	@cloned: Head may be cloned (check refcnt to be sure)
   *	@nohdr: Payload reference only, must not modify header
   *	@pkt_type: Packet class

   *	@fclone: skbuff clone status

   *	@ip_summed: Driver fed us an IP checksum
   *	@priority: Packet queueing priority
   *	@users: User count - see {datagram,tcp}.c
   *	@protocol: Packet protocol from driver

   *	@truesize: Buffer size 
   *	@head: Head of buffer
   *	@data: Data head pointer
   *	@tail: Tail pointer
   *	@end: End pointer
   *	@destructor: Destruct function

   *	@mark: Generic packet mark

   *	@nfct: Associated connection, if any

   *	@ipvs_property: skbuff is owned by ipvs

   *	@nfctinfo: Relationship of this skb to the connection

   *	@nfct_reasm: netfilter conntrack re-assembly pointer

   *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c

   *	@tc_index: Traffic control index
   *	@tc_verd: traffic control verdict

   *	@dma_cookie: a cookie to one of several possible DMA operations
   *		done by skb DMA functions

   *	@secmark: security marking

   */
  
  struct sk_buff {
  	/* These two members must be first. */
  	struct sk_buff		*next;
  	struct sk_buff		*prev;

  	struct sock		*sk;

  	ktime_t			tstamp;

  	struct net_device	*dev;

  	int			iif;
  	/* 4 byte hole on 64 bit*/

  	struct  dst_entry	*dst;
  	struct	sec_path	*sp;
  
  	/*
  	 * This is the control buffer. It is free to use for every
  	 * layer. Please put your private variables there. If you
  	 * want to keep them across layers you have to do a skb_clone()
  	 * first. This is owned by whoever has the skb queued ATM.
  	 */

  	char			cb[48];

  
  	unsigned int		len,
  				data_len,

  				mac_len;

  	union {
  		__wsum		csum;
  		__u32		csum_offset;
  	};

  	__u32			priority;

  	__u8			local_df:1,
  				cloned:1,
  				ip_summed:2,

  				nohdr:1,
  				nfctinfo:3;

  	__u8			pkt_type:3,

  				fclone:2,
  				ipvs_property:1;

  	__be16			protocol;

  
  	void			(*destructor)(struct sk_buff *skb);

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  	struct nf_conntrack	*nfct;

  	struct sk_buff		*nfct_reasm;
  #endif

  #ifdef CONFIG_BRIDGE_NETFILTER
  	struct nf_bridge_info	*nf_bridge;
  #endif

  #ifdef CONFIG_NET_SCHED

  	__u16			tc_index;	/* traffic control index */

  #ifdef CONFIG_NET_CLS_ACT

  	__u16			tc_verd;	/* traffic control verdict */

  #endif

  #endif

  #ifdef CONFIG_NET_DMA
  	dma_cookie_t		dma_cookie;
  #endif

  #ifdef CONFIG_NETWORK_SECMARK
  	__u32			secmark;
  #endif

  	__u32			mark;

  	sk_buff_data_t		transport_header;
  	sk_buff_data_t		network_header;
  	sk_buff_data_t		mac_header;

  	/* These elements must be at the end, see alloc_skb() for details.  */

  	sk_buff_data_t		tail;

  	sk_buff_data_t		end;

  	unsigned char		*head,

  				*data;

  	unsigned int		truesize;
  	atomic_t		users;

  };
  
  #ifdef __KERNEL__
  /*
   *	Handling routines are only of interest to the kernel
   */
  #include <linux/slab.h>
  
  #include <asm/system.h>

  extern void kfree_skb(struct sk_buff *skb);

  extern void	       __kfree_skb(struct sk_buff *skb);

  extern struct sk_buff *__alloc_skb(unsigned int size,

  				   gfp_t priority, int fclone, int node);

  static inline struct sk_buff *alloc_skb(unsigned int size,

  					gfp_t priority)

  {

  	return __alloc_skb(size, priority, 0, -1);

  }
  
  static inline struct sk_buff *alloc_skb_fclone(unsigned int size,

  					       gfp_t priority)

  {

  	return __alloc_skb(size, priority, 1, -1);

  }

  extern void	       kfree_skbmem(struct sk_buff *skb);

  extern struct sk_buff *skb_clone(struct sk_buff *skb,

  				 gfp_t priority);

  extern struct sk_buff *skb_copy(const struct sk_buff *skb,

  				gfp_t priority);

  extern struct sk_buff *pskb_copy(struct sk_buff *skb,

  				 gfp_t gfp_mask);

  extern int	       pskb_expand_head(struct sk_buff *skb,

  					int nhead, int ntail,

  					gfp_t gfp_mask);

  extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
  					    unsigned int headroom);
  extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
  				       int newheadroom, int newtailroom,

  				       gfp_t priority);

  extern int	       skb_pad(struct sk_buff *skb, int pad);

  #define dev_kfree_skb(a)	kfree_skb(a)
  extern void	      skb_over_panic(struct sk_buff *skb, int len,
  				     void *here);
  extern void	      skb_under_panic(struct sk_buff *skb, int len,
  				      void *here);

  extern void	      skb_truesize_bug(struct sk_buff *skb);
  
  static inline void skb_truesize_check(struct sk_buff *skb)
  {
  	if (unlikely((int)skb->truesize < sizeof(struct sk_buff) + skb->len))
  		skb_truesize_bug(skb);
  }

  extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
  			int getfrag(void *from, char *to, int offset,
  			int len,int odd, struct sk_buff *skb),
  			void *from, int length);

  struct skb_seq_state
  {
  	__u32		lower_offset;
  	__u32		upper_offset;
  	__u32		frag_idx;
  	__u32		stepped_offset;
  	struct sk_buff	*root_skb;
  	struct sk_buff	*cur_skb;
  	__u8		*frag_data;
  };
  
  extern void	      skb_prepare_seq_read(struct sk_buff *skb,
  					   unsigned int from, unsigned int to,
  					   struct skb_seq_state *st);
  extern unsigned int   skb_seq_read(unsigned int consumed, const u8 **data,
  				   struct skb_seq_state *st);
  extern void	      skb_abort_seq_read(struct skb_seq_state *st);

  extern unsigned int   skb_find_text(struct sk_buff *skb, unsigned int from,
  				    unsigned int to, struct ts_config *config,
  				    struct ts_state *state);

  #ifdef NET_SKBUFF_DATA_USES_OFFSET
  static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
  {
  	return skb->head + skb->end;
  }
  #else
  static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
  {
  	return skb->end;
  }
  #endif

  /* Internal */

  #define skb_shinfo(SKB)	((struct skb_shared_info *)(skb_end_pointer(SKB)))

  
  /**
   *	skb_queue_empty - check if a queue is empty
   *	@list: queue head
   *
   *	Returns true if the queue is empty, false otherwise.
   */
  static inline int skb_queue_empty(const struct sk_buff_head *list)
  {
  	return list->next == (struct sk_buff *)list;
  }
  
  /**
   *	skb_get - reference buffer
   *	@skb: buffer to reference
   *
   *	Makes another reference to a socket buffer and returns a pointer
   *	to the buffer.
   */
  static inline struct sk_buff *skb_get(struct sk_buff *skb)
  {
  	atomic_inc(&skb->users);
  	return skb;
  }
  
  /*
   * If users == 1, we are the only owner and are can avoid redundant
   * atomic change.
   */
  
  /**

   *	skb_cloned - is the buffer a clone
   *	@skb: buffer to check
   *
   *	Returns true if the buffer was generated with skb_clone() and is
   *	one of multiple shared copies of the buffer. Cloned buffers are
   *	shared data so must not be written to under normal circumstances.
   */
  static inline int skb_cloned(const struct sk_buff *skb)
  {
  	return skb->cloned &&
  	       (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
  }
  
  /**
   *	skb_header_cloned - is the header a clone
   *	@skb: buffer to check
   *
   *	Returns true if modifying the header part of the buffer requires
   *	the data to be copied.
   */
  static inline int skb_header_cloned(const struct sk_buff *skb)
  {
  	int dataref;
  
  	if (!skb->cloned)
  		return 0;
  
  	dataref = atomic_read(&skb_shinfo(skb)->dataref);
  	dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
  	return dataref != 1;
  }
  
  /**
   *	skb_header_release - release reference to header
   *	@skb: buffer to operate on
   *
   *	Drop a reference to the header part of the buffer.  This is done
   *	by acquiring a payload reference.  You must not read from the header
   *	part of skb->data after this.
   */
  static inline void skb_header_release(struct sk_buff *skb)
  {
  	BUG_ON(skb->nohdr);
  	skb->nohdr = 1;
  	atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
  }
  
  /**
   *	skb_shared - is the buffer shared
   *	@skb: buffer to check
   *
   *	Returns true if more than one person has a reference to this
   *	buffer.
   */
  static inline int skb_shared(const struct sk_buff *skb)
  {
  	return atomic_read(&skb->users) != 1;
  }
  
  /**
   *	skb_share_check - check if buffer is shared and if so clone it
   *	@skb: buffer to check
   *	@pri: priority for memory allocation
   *
   *	If the buffer is shared the buffer is cloned and the old copy
   *	drops a reference. A new clone with a single reference is returned.
   *	If the buffer is not shared the original buffer is returned. When
   *	being called from interrupt status or with spinlocks held pri must
   *	be GFP_ATOMIC.
   *
   *	NULL is returned on a memory allocation failure.
   */

  static inline struct sk_buff *skb_share_check(struct sk_buff *skb,

  					      gfp_t pri)

  {
  	might_sleep_if(pri & __GFP_WAIT);
  	if (skb_shared(skb)) {
  		struct sk_buff *nskb = skb_clone(skb, pri);
  		kfree_skb(skb);
  		skb = nskb;
  	}
  	return skb;
  }
  
  /*
   *	Copy shared buffers into a new sk_buff. We effectively do COW on
   *	packets to handle cases where we have a local reader and forward
   *	and a couple of other messy ones. The normal one is tcpdumping
   *	a packet thats being forwarded.
   */
  
  /**
   *	skb_unshare - make a copy of a shared buffer
   *	@skb: buffer to check
   *	@pri: priority for memory allocation
   *
   *	If the socket buffer is a clone then this function creates a new
   *	copy of the data, drops a reference count on the old copy and returns
   *	the new copy with the reference count at 1. If the buffer is not a clone
   *	the original buffer is returned. When called with a spinlock held or
   *	from interrupt state @pri must be %GFP_ATOMIC
   *
   *	%NULL is returned on a memory allocation failure.
   */

  static inline struct sk_buff *skb_unshare(struct sk_buff *skb,

  					  gfp_t pri)

  {
  	might_sleep_if(pri & __GFP_WAIT);
  	if (skb_cloned(skb)) {
  		struct sk_buff *nskb = skb_copy(skb, pri);
  		kfree_skb(skb);	/* Free our shared copy */
  		skb = nskb;
  	}
  	return skb;
  }
  
  /**
   *	skb_peek
   *	@list_: list to peek at
   *
   *	Peek an &sk_buff. Unlike most other operations you _MUST_
   *	be careful with this one. A peek leaves the buffer on the
   *	list and someone else may run off with it. You must hold
   *	the appropriate locks or have a private queue to do this.
   *
   *	Returns %NULL for an empty list or a pointer to the head element.
   *	The reference count is not incremented and the reference is therefore
   *	volatile. Use with caution.
   */
  static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
  {
  	struct sk_buff *list = ((struct sk_buff *)list_)->next;
  	if (list == (struct sk_buff *)list_)
  		list = NULL;
  	return list;
  }
  
  /**
   *	skb_peek_tail
   *	@list_: list to peek at
   *
   *	Peek an &sk_buff. Unlike most other operations you _MUST_
   *	be careful with this one. A peek leaves the buffer on the
   *	list and someone else may run off with it. You must hold
   *	the appropriate locks or have a private queue to do this.
   *
   *	Returns %NULL for an empty list or a pointer to the tail element.
   *	The reference count is not incremented and the reference is therefore
   *	volatile. Use with caution.
   */
  static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
  {
  	struct sk_buff *list = ((struct sk_buff *)list_)->prev;
  	if (list == (struct sk_buff *)list_)
  		list = NULL;
  	return list;
  }
  
  /**
   *	skb_queue_len	- get queue length
   *	@list_: list to measure
   *
   *	Return the length of an &sk_buff queue.
   */
  static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
  {
  	return list_->qlen;
  }

  /*
   * This function creates a split out lock class for each invocation;
   * this is needed for now since a whole lot of users of the skb-queue
   * infrastructure in drivers have different locking usage (in hardirq)
   * than the networking core (in softirq only). In the long run either the
   * network layer or drivers should need annotation to consolidate the
   * main types of usage into 3 classes.
   */

  static inline void skb_queue_head_init(struct sk_buff_head *list)
  {
  	spin_lock_init(&list->lock);
  	list->prev = list->next = (struct sk_buff *)list;
  	list->qlen = 0;
  }

  static inline void skb_queue_head_init_class(struct sk_buff_head *list,
  		struct lock_class_key *class)
  {
  	skb_queue_head_init(list);
  	lockdep_set_class(&list->lock, class);
  }

  /*
   *	Insert an sk_buff at the start of a list.
   *
   *	The "__skb_xxxx()" functions are the non-atomic ones that
   *	can only be called with interrupts disabled.
   */
  
  /**

   *	__skb_queue_after - queue a buffer at the list head

   *	@list: list to use

   *	@prev: place after this buffer

   *	@newsk: buffer to queue
   *

   *	Queue a buffer int the middle of a list. This function takes no locks

   *	and you must therefore hold required locks before calling it.
   *
   *	A buffer cannot be placed on two lists at the same time.
   */

  static inline void __skb_queue_after(struct sk_buff_head *list,
  				     struct sk_buff *prev,
  				     struct sk_buff *newsk)

  {

  	struct sk_buff *next;

  	list->qlen++;

  	next = prev->next;
  	newsk->next = next;
  	newsk->prev = prev;
  	next->prev  = prev->next = newsk;
  }
  
  /**

   *	__skb_queue_head - queue a buffer at the list head
   *	@list: list to use
   *	@newsk: buffer to queue
   *
   *	Queue a buffer at the start of a list. This function takes no locks
   *	and you must therefore hold required locks before calling it.
   *
   *	A buffer cannot be placed on two lists at the same time.
   */
  extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
  static inline void __skb_queue_head(struct sk_buff_head *list,
  				    struct sk_buff *newsk)
  {
  	__skb_queue_after(list, (struct sk_buff *)list, newsk);
  }
  
  /**

   *	__skb_queue_tail - queue a buffer at the list tail
   *	@list: list to use
   *	@newsk: buffer to queue
   *
   *	Queue a buffer at the end of a list. This function takes no locks
   *	and you must therefore hold required locks before calling it.
   *
   *	A buffer cannot be placed on two lists at the same time.
   */
  extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
  static inline void __skb_queue_tail(struct sk_buff_head *list,
  				   struct sk_buff *newsk)
  {
  	struct sk_buff *prev, *next;

  	list->qlen++;
  	next = (struct sk_buff *)list;
  	prev = next->prev;
  	newsk->next = next;
  	newsk->prev = prev;
  	next->prev  = prev->next = newsk;
  }
  
  
  /**
   *	__skb_dequeue - remove from the head of the queue
   *	@list: list to dequeue from
   *
   *	Remove the head of the list. This function does not take any locks
   *	so must be used with appropriate locks held only. The head item is
   *	returned or %NULL if the list is empty.
   */
  extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
  static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
  {
  	struct sk_buff *next, *prev, *result;
  
  	prev = (struct sk_buff *) list;
  	next = prev->next;
  	result = NULL;
  	if (next != prev) {
  		result	     = next;
  		next	     = next->next;
  		list->qlen--;
  		next->prev   = prev;
  		prev->next   = next;
  		result->next = result->prev = NULL;

  	}
  	return result;
  }
  
  
  /*
   *	Insert a packet on a list.
   */

  extern void        skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);

  static inline void __skb_insert(struct sk_buff *newsk,
  				struct sk_buff *prev, struct sk_buff *next,
  				struct sk_buff_head *list)
  {
  	newsk->next = next;
  	newsk->prev = prev;
  	next->prev  = prev->next = newsk;

  	list->qlen++;
  }
  
  /*
   *	Place a packet after a given packet in a list.
   */

  extern void	   skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
  static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)

  {

  	__skb_insert(newsk, old, old->next, list);

  }
  
  /*
   * remove sk_buff from list. _Must_ be called atomically, and with
   * the list known..
   */

  extern void	   skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);

  static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
  {
  	struct sk_buff *next, *prev;
  
  	list->qlen--;
  	next	   = skb->next;
  	prev	   = skb->prev;
  	skb->next  = skb->prev = NULL;

  	next->prev = prev;
  	prev->next = next;
  }
  
  
  /* XXX: more streamlined implementation */
  
  /**
   *	__skb_dequeue_tail - remove from the tail of the queue
   *	@list: list to dequeue from
   *
   *	Remove the tail of the list. This function does not take any locks
   *	so must be used with appropriate locks held only. The tail item is
   *	returned or %NULL if the list is empty.
   */
  extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
  static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
  {
  	struct sk_buff *skb = skb_peek_tail(list);
  	if (skb)
  		__skb_unlink(skb, list);
  	return skb;
  }
  
  
  static inline int skb_is_nonlinear(const struct sk_buff *skb)
  {
  	return skb->data_len;
  }
  
  static inline unsigned int skb_headlen(const struct sk_buff *skb)
  {
  	return skb->len - skb->data_len;
  }
  
  static inline int skb_pagelen(const struct sk_buff *skb)
  {
  	int i, len = 0;
  
  	for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
  		len += skb_shinfo(skb)->frags[i].size;
  	return len + skb_headlen(skb);
  }
  
  static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
  				      struct page *page, int off, int size)
  {
  	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
  
  	frag->page		  = page;
  	frag->page_offset	  = off;
  	frag->size		  = size;
  	skb_shinfo(skb)->nr_frags = i + 1;
  }
  
  #define SKB_PAGE_ASSERT(skb) 	BUG_ON(skb_shinfo(skb)->nr_frags)
  #define SKB_FRAG_ASSERT(skb) 	BUG_ON(skb_shinfo(skb)->frag_list)
  #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))

  #ifdef NET_SKBUFF_DATA_USES_OFFSET
  static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
  {
  	return skb->head + skb->tail;
  }
  
  static inline void skb_reset_tail_pointer(struct sk_buff *skb)
  {
  	skb->tail = skb->data - skb->head;
  }
  
  static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
  {
  	skb_reset_tail_pointer(skb);
  	skb->tail += offset;
  }
  #else /* NET_SKBUFF_DATA_USES_OFFSET */
  static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
  {
  	return skb->tail;
  }
  
  static inline void skb_reset_tail_pointer(struct sk_buff *skb)
  {
  	skb->tail = skb->data;
  }
  
  static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
  {
  	skb->tail = skb->data + offset;
  }

  #endif /* NET_SKBUFF_DATA_USES_OFFSET */

  /*
   *	Add data to an sk_buff
   */
  static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
  {

  	unsigned char *tmp = skb_tail_pointer(skb);

  	SKB_LINEAR_ASSERT(skb);
  	skb->tail += len;
  	skb->len  += len;
  	return tmp;
  }
  
  /**
   *	skb_put - add data to a buffer
   *	@skb: buffer to use
   *	@len: amount of data to add
   *
   *	This function extends the used data area of the buffer. If this would
   *	exceed the total buffer size the kernel will panic. A pointer to the
   *	first byte of the extra data is returned.
   */
  static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
  {

  	unsigned char *tmp = skb_tail_pointer(skb);

  	SKB_LINEAR_ASSERT(skb);
  	skb->tail += len;
  	skb->len  += len;

  	if (unlikely(skb->tail > skb->end))

  		skb_over_panic(skb, len, current_text_addr());
  	return tmp;
  }
  
  static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
  {
  	skb->data -= len;
  	skb->len  += len;
  	return skb->data;
  }
  
  /**
   *	skb_push - add data to the start of a buffer
   *	@skb: buffer to use
   *	@len: amount of data to add
   *
   *	This function extends the used data area of the buffer at the buffer
   *	start. If this would exceed the total buffer headroom the kernel will
   *	panic. A pointer to the first byte of the extra data is returned.
   */
  static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
  {
  	skb->data -= len;
  	skb->len  += len;
  	if (unlikely(skb->data<skb->head))
  		skb_under_panic(skb, len, current_text_addr());
  	return skb->data;
  }
  
  static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
  {
  	skb->len -= len;
  	BUG_ON(skb->len < skb->data_len);
  	return skb->data += len;
  }
  
  /**
   *	skb_pull - remove data from the start of a buffer
   *	@skb: buffer to use
   *	@len: amount of data to remove
   *
   *	This function removes data from the start of a buffer, returning
   *	the memory to the headroom. A pointer to the next data in the buffer
   *	is returned. Once the data has been pulled future pushes will overwrite
   *	the old data.
   */
  static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
  {
  	return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
  }
  
  extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
  
  static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
  {
  	if (len > skb_headlen(skb) &&
  	    !__pskb_pull_tail(skb, len-skb_headlen(skb)))
  		return NULL;
  	skb->len -= len;
  	return skb->data += len;
  }
  
  static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
  {
  	return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
  }
  
  static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
  {
  	if (likely(len <= skb_headlen(skb)))
  		return 1;
  	if (unlikely(len > skb->len))
  		return 0;
  	return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
  }
  
  /**
   *	skb_headroom - bytes at buffer head
   *	@skb: buffer to check
   *
   *	Return the number of bytes of free space at the head of an &sk_buff.
   */
  static inline int skb_headroom(const struct sk_buff *skb)
  {
  	return skb->data - skb->head;
  }
  
  /**
   *	skb_tailroom - bytes at buffer end
   *	@skb: buffer to check
   *
   *	Return the number of bytes of free space at the tail of an sk_buff
   */
  static inline int skb_tailroom(const struct sk_buff *skb)
  {

  	return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;

  }
  
  /**
   *	skb_reserve - adjust headroom
   *	@skb: buffer to alter
   *	@len: bytes to move
   *
   *	Increase the headroom of an empty &sk_buff by reducing the tail
   *	room. This is only allowed for an empty buffer.
   */

  static inline void skb_reserve(struct sk_buff *skb, int len)

  {
  	skb->data += len;
  	skb->tail += len;
  }

  #ifdef NET_SKBUFF_DATA_USES_OFFSET

  static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
  {

  	return skb->head + skb->transport_header;

  }

  static inline void skb_reset_transport_header(struct sk_buff *skb)
  {

  	skb->transport_header = skb->data - skb->head;

  }

  static inline void skb_set_transport_header(struct sk_buff *skb,
  					    const int offset)
  {

  	skb_reset_transport_header(skb);
  	skb->transport_header += offset;

  }

  static inline unsigned char *skb_network_header(const struct sk_buff *skb)
  {

  	return skb->head + skb->network_header;

  }

  static inline void skb_reset_network_header(struct sk_buff *skb)
  {

  	skb->network_header = skb->data - skb->head;

  }

  static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
  {

  	skb_reset_network_header(skb);
  	skb->network_header += offset;

  }

  static inline unsigned char *skb_mac_header(const struct sk_buff *skb)

  {

  	return skb->head + skb->mac_header;

  }

  static inline int skb_mac_header_was_set(const struct sk_buff *skb)

  {

  	return skb->mac_header != ~0U;
  }
  
  static inline void skb_reset_mac_header(struct sk_buff *skb)
  {
  	skb->mac_header = skb->data - skb->head;
  }
  
  static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
  {
  	skb_reset_mac_header(skb);
  	skb->mac_header += offset;
  }
  
  #else /* NET_SKBUFF_DATA_USES_OFFSET */
  
  static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
  {
  	return skb->transport_header;
  }
  
  static inline void skb_reset_transport_header(struct sk_buff *skb)
  {
  	skb->transport_header = skb->data;
  }
  
  static inline void skb_set_transport_header(struct sk_buff *skb,
  					    const int offset)
  {
  	skb->transport_header = skb->data + offset;
  }
  
  static inline unsigned char *skb_network_header(const struct sk_buff *skb)
  {
  	return skb->network_header;
  }
  
  static inline void skb_reset_network_header(struct sk_buff *skb)
  {
  	skb->network_header = skb->data;
  }
  
  static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
  {
  	skb->network_header = skb->data + offset;

  }

  static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
  {

  	return skb->mac_header;

  }
  
  static inline int skb_mac_header_was_set(const struct sk_buff *skb)
  {

  	return skb->mac_header != NULL;

  }

  static inline void skb_reset_mac_header(struct sk_buff *skb)
  {

  	skb->mac_header = skb->data;

  }

  static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
  {

  	skb->mac_header = skb->data + offset;

  }

  #endif /* NET_SKBUFF_DATA_USES_OFFSET */
  
  static inline int skb_transport_offset(const struct sk_buff *skb)
  {
  	return skb_transport_header(skb) - skb->data;
  }
  
  static inline u32 skb_network_header_len(const struct sk_buff *skb)
  {
  	return skb->transport_header - skb->network_header;
  }
  
  static inline int skb_network_offset(const struct sk_buff *skb)
  {
  	return skb_network_header(skb) - skb->data;
  }

  /*
   * CPUs often take a performance hit when accessing unaligned memory
   * locations. The actual performance hit varies, it can be small if the
   * hardware handles it or large if we have to take an exception and fix it
   * in software.
   *
   * Since an ethernet header is 14 bytes network drivers often end up with
   * the IP header at an unaligned offset. The IP header can be aligned by
   * shifting the start of the packet by 2 bytes. Drivers should do this
   * with:
   *
   * skb_reserve(NET_IP_ALIGN);
   *
   * The downside to this alignment of the IP header is that the DMA is now
   * unaligned. On some architectures the cost of an unaligned DMA is high
   * and this cost outweighs the gains made by aligning the IP header.
   * 
   * Since this trade off varies between architectures, we allow NET_IP_ALIGN
   * to be overridden.
   */
  #ifndef NET_IP_ALIGN
  #define NET_IP_ALIGN	2
  #endif

  /*
   * The networking layer reserves some headroom in skb data (via
   * dev_alloc_skb). This is used to avoid having to reallocate skb data when
   * the header has to grow. In the default case, if the header has to grow
   * 16 bytes or less we avoid the reallocation.
   *
   * Unfortunately this headroom changes the DMA alignment of the resulting
   * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
   * on some architectures. An architecture can override this value,
   * perhaps setting it to a cacheline in size (since that will maintain
   * cacheline alignment of the DMA). It must be a power of 2.
   *
   * Various parts of the networking layer expect at least 16 bytes of
   * headroom, you should not reduce this.
   */
  #ifndef NET_SKB_PAD
  #define NET_SKB_PAD	16
  #endif

  extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);

  
  static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
  {

  	if (unlikely(skb->data_len)) {
  		WARN_ON(1);
  		return;
  	}

  	skb->len = len;
  	skb_set_tail_pointer(skb, len);

  }
  
  /**
   *	skb_trim - remove end from a buffer
   *	@skb: buffer to alter
   *	@len: new length
   *
   *	Cut the length of a buffer down by removing data from the tail. If
   *	the buffer is already under the length specified it is not modified.

   *	The skb must be linear.

   */
  static inline void skb_trim(struct sk_buff *skb, unsigned int len)
  {
  	if (skb->len > len)
  		__skb_trim(skb, len);
  }
  
  
  static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
  {

  	if (skb->data_len)
  		return ___pskb_trim(skb, len);
  	__skb_trim(skb, len);
  	return 0;

  }
  
  static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
  {
  	return (len < skb->len) ? __pskb_trim(skb, len) : 0;
  }
  
  /**

   *	pskb_trim_unique - remove end from a paged unique (not cloned) buffer
   *	@skb: buffer to alter
   *	@len: new length
   *
   *	This is identical to pskb_trim except that the caller knows that
   *	the skb is not cloned so we should never get an error due to out-
   *	of-memory.
   */
  static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
  {
  	int err = pskb_trim(skb, len);
  	BUG_ON(err);
  }
  
  /**

   *	skb_orphan - orphan a buffer
   *	@skb: buffer to orphan
   *
   *	If a buffer currently has an owner then we call the owner's
   *	destructor function and make the @skb unowned. The buffer continues
   *	to exist but is no longer charged to its former owner.
   */
  static inline void skb_orphan(struct sk_buff *skb)
  {
  	if (skb->destructor)
  		skb->destructor(skb);
  	skb->destructor = NULL;
  	skb->sk		= NULL;
  }
  
  /**
   *	__skb_queue_purge - empty a list
   *	@list: list to empty
   *
   *	Delete all buffers on an &sk_buff list. Each buffer is removed from
   *	the list and one reference dropped. This function does not take the
   *	list lock and the caller must hold the relevant locks to use it.
   */
  extern void skb_queue_purge(struct sk_buff_head *list);
  static inline void __skb_queue_purge(struct sk_buff_head *list)
  {
  	struct sk_buff *skb;
  	while ((skb = __skb_dequeue(list)) != NULL)
  		kfree_skb(skb);
  }
  
  /**

   *	__dev_alloc_skb - allocate an skbuff for receiving

   *	@length: length to allocate
   *	@gfp_mask: get_free_pages mask, passed to alloc_skb
   *
   *	Allocate a new &sk_buff and assign it a usage count of one. The
   *	buffer has unspecified headroom built in. Users should allocate
   *	the headroom they think they need without accounting for the
   *	built in space. The built in space is used for optimisations.
   *

   *	%NULL is returned if there is no free memory.

   */

  static inline struct sk_buff *__dev_alloc_skb(unsigned int length,

  					      gfp_t gfp_mask)

  {

  	struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);

  	if (likely(skb))

  		skb_reserve(skb, NET_SKB_PAD);

  	return skb;
  }

  
  /**

   *	dev_alloc_skb - allocate an skbuff for receiving

   *	@length: length to allocate
   *
   *	Allocate a new &sk_buff and assign it a usage count of one. The
   *	buffer has unspecified headroom built in. Users should allocate
   *	the headroom they think they need without accounting for the
   *	built in space. The built in space is used for optimisations.
   *

   *	%NULL is returned if there is no free memory. Although this function

   *	allocates memory it can be called from an interrupt.
   */
  static inline struct sk_buff *dev_alloc_skb(unsigned int length)
  {
  	return __dev_alloc_skb(length, GFP_ATOMIC);
  }

  extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
  		unsigned int length, gfp_t gfp_mask);
  
  /**
   *	netdev_alloc_skb - allocate an skbuff for rx on a specific device
   *	@dev: network device to receive on
   *	@length: length to allocate
   *
   *	Allocate a new &sk_buff and assign it a usage count of one. The
   *	buffer has unspecified headroom built in. Users should allocate
   *	the headroom they think they need without accounting for the
   *	built in space. The built in space is used for optimisations.
   *
   *	%NULL is returned if there is no free memory. Although this function
   *	allocates memory it can be called from an interrupt.
   */
  static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
  		unsigned int length)
  {
  	return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
  }

  /**
   *	skb_cow - copy header of skb when it is required
   *	@skb: buffer to cow
   *	@headroom: needed headroom
   *
   *	If the skb passed lacks sufficient headroom or its data part
   *	is shared, data is reallocated. If reallocation fails, an error
   *	is returned and original skb is not changed.
   *
   *	The result is skb with writable area skb->head...skb->tail
   *	and at least @headroom of space at head.
   */
  static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
  {

  	int delta = (headroom > NET_SKB_PAD ? headroom : NET_SKB_PAD) -
  			skb_headroom(skb);

  
  	if (delta < 0)
  		delta = 0;
  
  	if (delta || skb_cloned(skb))

  		return pskb_expand_head(skb, (delta + (NET_SKB_PAD-1)) &
  				~(NET_SKB_PAD-1), 0, GFP_ATOMIC);

  	return 0;
  }
  
  /**
   *	skb_padto	- pad an skbuff up to a minimal size
   *	@skb: buffer to pad
   *	@len: minimal length
   *
   *	Pads up a buffer to ensure the trailing bytes exist and are
   *	blanked. If the buffer already contains sufficient data it

   *	is untouched. Otherwise it is extended. Returns zero on
   *	success. The skb is freed on error.

   */
   

  static inline int skb_padto(struct sk_buff *skb, unsigned int len)

  {
  	unsigned int size = skb->len;
  	if (likely(size >= len))

  		return 0;

  	return skb_pad(skb, len-size);
  }
  
  static inline int skb_add_data(struct sk_buff *skb,
  			       char __user *from, int copy)
  {
  	const int off = skb->len;
  
  	if (skb->ip_summed == CHECKSUM_NONE) {
  		int err = 0;

  		__wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),

  							    copy, 0, &err);
  		if (!err) {
  			skb->csum = csum_block_add(skb->csum, csum, off);
  			return 0;
  		}
  	} else if (!copy_from_user(skb_put(skb, copy), from, copy))
  		return 0;
  
  	__skb_trim(skb, off);
  	return -EFAULT;
  }
  
  static inline int skb_can_coalesce(struct sk_buff *skb, int i,
  				   struct page *page, int off)
  {
  	if (i) {
  		struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
  
  		return page == frag->page &&
  		       off == frag->page_offset + frag->size;
  	}
  	return 0;
  }

  static inline int __skb_linearize(struct sk_buff *skb)
  {
  	return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
  }

  /**
   *	skb_linearize - convert paged skb to linear one
   *	@skb: buffer to linarize

   *
   *	If there is no free memory -ENOMEM is returned, otherwise zero
   *	is returned and the old skb data released.
   */

  static inline int skb_linearize(struct sk_buff *skb)
  {
  	return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
  }
  
  /**
   *	skb_linearize_cow - make sure skb is linear and writable
   *	@skb: buffer to process
   *
   *	If there is no free memory -ENOMEM is returned, otherwise zero
   *	is returned and the old skb data released.
   */
  static inline int skb_linearize_cow(struct sk_buff *skb)

  {

  	return skb_is_nonlinear(skb) || skb_cloned(skb) ?
  	       __skb_linearize(skb) : 0;

  }
  
  /**
   *	skb_postpull_rcsum - update checksum for received skb after pull
   *	@skb: buffer to update
   *	@start: start of data before pull
   *	@len: length of data pulled
   *
   *	After doing a pull on a received packet, you need to call this to

   *	update the CHECKSUM_COMPLETE checksum, or set ip_summed to
   *	CHECKSUM_NONE so that it can be recomputed from scratch.

   */
  
  static inline void skb_postpull_rcsum(struct sk_buff *skb,

  				      const void *start, unsigned int len)

  {

  	if (skb->ip_summed == CHECKSUM_COMPLETE)

  		skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
  }

  unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);

  /**
   *	pskb_trim_rcsum - trim received skb and update checksum
   *	@skb: buffer to trim
   *	@len: new length
   *
   *	This is exactly the same as pskb_trim except that it ensures the
   *	checksum of received packets are still valid after the operation.
   */
  
  static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
  {

  	if (likely(len >= skb->len))

  		return 0;

  	if (skb->ip_summed == CHECKSUM_COMPLETE)

  		skb->ip_summed = CHECKSUM_NONE;
  	return __pskb_trim(skb, len);
  }

  #define skb_queue_walk(queue, skb) \
  		for (skb = (queue)->next;					\
  		     prefetch(skb->next), (skb != (struct sk_buff *)(queue));	\
  		     skb = skb->next)

  #define skb_queue_reverse_walk(queue, skb) \
  		for (skb = (queue)->prev;					\
  		     prefetch(skb->prev), (skb != (struct sk_buff *)(queue));	\
  		     skb = skb->prev)

  
  extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
  					 int noblock, int *err);
  extern unsigned int    datagram_poll(struct file *file, struct socket *sock,
  				     struct poll_table_struct *wait);
  extern int	       skb_copy_datagram_iovec(const struct sk_buff *from,
  					       int offset, struct iovec *to,
  					       int size);

  extern int	       skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,

  							int hlen,
  							struct iovec *iov);
  extern void	       skb_free_datagram(struct sock *sk, struct sk_buff *skb);

  extern void	       skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
  					 unsigned int flags);

  extern __wsum	       skb_checksum(const struct sk_buff *skb, int offset,
  				    int len, __wsum csum);

  extern int	       skb_copy_bits(const struct sk_buff *skb, int offset,
  				     void *to, int len);

  extern int	       skb_store_bits(const struct sk_buff *skb, int offset,
  				      void *from, int len);

  extern __wsum	       skb_copy_and_csum_bits(const struct sk_buff *skb,

  					      int offset, u8 *to, int len,

  					      __wsum csum);

  extern void	       skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
  extern void	       skb_split(struct sk_buff *skb,
  				 struct sk_buff *skb1, const u32 len);

  extern struct sk_buff *skb_segment(struct sk_buff *skb, int features);

  static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
  				       int len, void *buffer)
  {
  	int hlen = skb_headlen(skb);

  	if (hlen - offset >= len)

  		return skb->data + offset;
  
  	if (skb_copy_bits(skb, offset, buffer, len) < 0)
  		return NULL;
  
  	return buffer;
  }
  
  extern void skb_init(void);

  /**
   *	skb_get_timestamp - get timestamp from a skb
   *	@skb: skb to get stamp from
   *	@stamp: pointer to struct timeval to store stamp in
   *
   *	Timestamps are stored in the skb as offsets to a base timestamp.
   *	This function converts the offset back to a struct timeval and stores
   *	it in stamp.
   */

  static inline void skb_get_timestamp(const struct sk_buff *skb, struct timeval *stamp)

  {

  	*stamp = ktime_to_timeval(skb->tstamp);

  }

  static inline void __net_timestamp(struct sk_buff *skb)

  {

  	skb->tstamp = ktime_get_real();

  }

  extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);

  extern __sum16 __skb_checksum_complete(struct sk_buff *skb);

  
  /**
   *	skb_checksum_complete - Calculate checksum of an entire packet
   *	@skb: packet to process
   *
   *	This function calculates the checksum over the entire packet plus
   *	the value of skb->csum.  The latter can be used to supply the
   *	checksum of a pseudo header as used by TCP/UDP.  It returns the
   *	checksum.
   *
   *	For protocols that contain complete checksums such as ICMP/TCP/UDP,
   *	this function can be used to verify that checksum on received
   *	packets.  In that case the function should return zero if the
   *	checksum is correct.  In particular, this function will return zero
   *	if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
   *	hardware has already verified the correctness of the checksum.
   */
  static inline unsigned int skb_checksum_complete(struct sk_buff *skb)
  {
  	return skb->ip_summed != CHECKSUM_UNNECESSARY &&
  		__skb_checksum_complete(skb);
  }

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  extern void nf_conntrack_destroy(struct nf_conntrack *nfct);

  static inline void nf_conntrack_put(struct nf_conntrack *nfct)
  {
  	if (nfct && atomic_dec_and_test(&nfct->use))

  		nf_conntrack_destroy(nfct);

  }
  static inline void nf_conntrack_get(struct nf_conntrack *nfct)
  {
  	if (nfct)
  		atomic_inc(&nfct->use);
  }

  static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
  {
  	if (skb)
  		atomic_inc(&skb->users);
  }
  static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
  {
  	if (skb)
  		kfree_skb(skb);
  }
  #endif

  #ifdef CONFIG_BRIDGE_NETFILTER
  static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
  {
  	if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
  		kfree(nf_bridge);
  }
  static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
  {
  	if (nf_bridge)
  		atomic_inc(&nf_bridge->use);
  }
  #endif /* CONFIG_BRIDGE_NETFILTER */

  static inline void nf_reset(struct sk_buff *skb)
  {

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  	nf_conntrack_put(skb->nfct);
  	skb->nfct = NULL;

  	nf_conntrack_put_reasm(skb->nfct_reasm);
  	skb->nfct_reasm = NULL;
  #endif
  #ifdef CONFIG_BRIDGE_NETFILTER
  	nf_bridge_put(skb->nf_bridge);
  	skb->nf_bridge = NULL;
  #endif
  }

  /* Note: This doesn't put any conntrack and bridge info in dst. */
  static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
  {

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  	dst->nfct = src->nfct;
  	nf_conntrack_get(src->nfct);
  	dst->nfctinfo = src->nfctinfo;

  	dst->nfct_reasm = src->nfct_reasm;
  	nf_conntrack_get_reasm(src->nfct_reasm);
  #endif
  #ifdef CONFIG_BRIDGE_NETFILTER
  	dst->nf_bridge  = src->nf_bridge;
  	nf_bridge_get(src->nf_bridge);
  #endif
  }

  static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
  {

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  	nf_conntrack_put(dst->nfct);

  	nf_conntrack_put_reasm(dst->nfct_reasm);
  #endif
  #ifdef CONFIG_BRIDGE_NETFILTER
  	nf_bridge_put(dst->nf_bridge);
  #endif
  	__nf_copy(dst, src);
  }

  #ifdef CONFIG_NETWORK_SECMARK
  static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
  {
  	to->secmark = from->secmark;
  }
  
  static inline void skb_init_secmark(struct sk_buff *skb)
  {
  	skb->secmark = 0;
  }
  #else
  static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
  { }
  
  static inline void skb_init_secmark(struct sk_buff *skb)
  { }
  #endif

  static inline int skb_is_gso(const struct sk_buff *skb)
  {
  	return skb_shinfo(skb)->gso_size;
  }

  #endif	/* __KERNEL__ */
  #endif	/* _LINUX_SKBUFF_H */