/*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		Definitions for the AF_INET socket handler.
   *
   * Version:	@(#)sock.h	1.0.4	05/13/93
   *

   * Authors:	Ross Biro

   *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *		Corey Minyard <wf-rch!minyard@relay.EU.net>
   *		Florian La Roche <flla@stud.uni-sb.de>
   *
   * Fixes:
   *		Alan Cox	:	Volatiles in skbuff pointers. See
   *					skbuff comments. May be overdone,
   *					better to prove they can be removed
   *					than the reverse.
   *		Alan Cox	:	Added a zapped field for tcp to note
   *					a socket is reset and must stay shut up
   *		Alan Cox	:	New fields for options
   *	Pauline Middelink	:	identd support
   *		Alan Cox	:	Eliminate low level recv/recvfrom
   *		David S. Miller	:	New socket lookup architecture.
   *              Steve Whitehouse:       Default routines for sock_ops
   *              Arnaldo C. Melo :	removed net_pinfo, tp_pinfo and made
   *              			protinfo be just a void pointer, as the
   *              			protocol specific parts were moved to
   *              			respective headers and ipv4/v6, etc now
   *              			use private slabcaches for its socks
   *              Pedro Hortas	:	New flags field for socket options
   *
   *
   *		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 _SOCK_H
  #define _SOCK_H

  #include <linux/hardirq.h>

  #include <linux/kernel.h>

  #include <linux/list.h>

  #include <linux/list_nulls.h>

  #include <linux/timer.h>
  #include <linux/cache.h>

  #include <linux/lockdep.h>

  #include <linux/netdevice.h>
  #include <linux/skbuff.h>	/* struct sk_buff */

  #include <linux/mm.h>

  #include <linux/security.h>

  #include <linux/slab.h>

  #include <linux/uaccess.h>

  
  #include <linux/filter.h>

  #include <linux/rculist_nulls.h>

  #include <linux/poll.h>

  #include <linux/atomic.h>

  #include <net/dst.h>
  #include <net/checksum.h>
  
  /*
   * This structure really needs to be cleaned up.
   * Most of it is for TCP, and not used by any of
   * the other protocols.
   */
  
  /* Define this to get the SOCK_DBG debugging facility. */
  #define SOCK_DEBUGGING
  #ifdef SOCK_DEBUGGING
  #define SOCK_DEBUG(sk, msg...) do { if ((sk) && sock_flag((sk), SOCK_DBG)) \
  					printk(KERN_DEBUG msg); } while (0)
  #else

  /* Validate arguments and do nothing */

  static inline __printf(2, 3)
  void SOCK_DEBUG(struct sock *sk, const char *msg, ...)

  {
  }

  #endif
  
  /* This is the per-socket lock.  The spinlock provides a synchronization
   * between user contexts and software interrupt processing, whereas the
   * mini-semaphore synchronizes multiple users amongst themselves.
   */

  typedef struct {
  	spinlock_t		slock;

  	int			owned;

  	wait_queue_head_t	wq;

  	/*
  	 * We express the mutex-alike socket_lock semantics
  	 * to the lock validator by explicitly managing
  	 * the slock as a lock variant (in addition to
  	 * the slock itself):
  	 */
  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	struct lockdep_map dep_map;
  #endif

  } socket_lock_t;

  struct sock;

  struct proto;

  struct net;

  
  /**

   *	struct sock_common - minimal network layer representation of sockets

   *	@skc_daddr: Foreign IPv4 addr
   *	@skc_rcv_saddr: Bound local IPv4 addr

   *	@skc_hash: hash value used with various protocol lookup tables

   *	@skc_u16hashes: two u16 hash values used by UDP lookup tables

   *	@skc_family: network address family
   *	@skc_state: Connection state
   *	@skc_reuse: %SO_REUSEADDR setting
   *	@skc_bound_dev_if: bound device index if != 0

   *	@skc_bind_node: bind hash linkage for various protocol lookup tables

   *	@skc_portaddr_node: second hash linkage for UDP/UDP-Lite protocol

   *	@skc_prot: protocol handlers inside a network family

   *	@skc_net: reference to the network namespace of this socket

   *	@skc_node: main hash linkage for various protocol lookup tables
   *	@skc_nulls_node: main hash linkage for TCP/UDP/UDP-Lite protocol
   *	@skc_tx_queue_mapping: tx queue number for this connection
   *	@skc_refcnt: reference count

   *
   *	This is the minimal network layer representation of sockets, the header

   *	for struct sock and struct inet_timewait_sock.
   */

  struct sock_common {

  	/* skc_daddr and skc_rcv_saddr must be grouped :
  	 * cf INET_MATCH() and INET_TW_MATCH()

  	 */

  	__be32			skc_daddr;
  	__be32			skc_rcv_saddr;

  	union  {
  		unsigned int	skc_hash;
  		__u16		skc_u16hashes[2];
  	};

  	unsigned short		skc_family;
  	volatile unsigned char	skc_state;
  	unsigned char		skc_reuse;
  	int			skc_bound_dev_if;

  	union {
  		struct hlist_node	skc_bind_node;
  		struct hlist_nulls_node skc_portaddr_node;
  	};

  	struct proto		*skc_prot;

  #ifdef CONFIG_NET_NS

  	struct net	 	*skc_net;

  #endif

  	/*
  	 * fields between dontcopy_begin/dontcopy_end
  	 * are not copied in sock_copy()
  	 */

  	/* private: */

  	int			skc_dontcopy_begin[0];

  	/* public: */

  	union {
  		struct hlist_node	skc_node;
  		struct hlist_nulls_node skc_nulls_node;
  	};
  	int			skc_tx_queue_mapping;
  	atomic_t		skc_refcnt;

  	/* private: */

  	int                     skc_dontcopy_end[0];

  	/* public: */

  };
  
  /**
    *	struct sock - network layer representation of sockets

    *	@__sk_common: shared layout with inet_timewait_sock

    *	@sk_shutdown: mask of %SEND_SHUTDOWN and/or %RCV_SHUTDOWN
    *	@sk_userlocks: %SO_SNDBUF and %SO_RCVBUF settings
    *	@sk_lock:	synchronizer
    *	@sk_rcvbuf: size of receive buffer in bytes

    *	@sk_wq: sock wait queue and async head

    *	@sk_dst_cache: destination cache
    *	@sk_dst_lock: destination cache lock
    *	@sk_policy: flow policy

    *	@sk_receive_queue: incoming packets
    *	@sk_wmem_alloc: transmit queue bytes committed
    *	@sk_write_queue: Packet sending queue

    *	@sk_async_wait_queue: DMA copied packets

    *	@sk_omem_alloc: "o" is "option" or "other"
    *	@sk_wmem_queued: persistent queue size
    *	@sk_forward_alloc: space allocated forward
    *	@sk_allocation: allocation mode
    *	@sk_sndbuf: size of send buffer in bytes

    *	@sk_flags: %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE,

    *		   %SO_OOBINLINE settings, %SO_TIMESTAMPING settings

    *	@sk_no_check: %SO_NO_CHECK setting, wether or not checkup packets
    *	@sk_route_caps: route capabilities (e.g. %NETIF_F_TSO)

    *	@sk_route_nocaps: forbidden route capabilities (e.g NETIF_F_GSO_MASK)

    *	@sk_gso_type: GSO type (e.g. %SKB_GSO_TCPV4)

    *	@sk_gso_max_size: Maximum GSO segment size to build

    *	@sk_lingertime: %SO_LINGER l_linger setting

    *	@sk_backlog: always used with the per-socket spinlock held
    *	@sk_callback_lock: used with the callbacks in the end of this struct
    *	@sk_error_queue: rarely used

    *	@sk_prot_creator: sk_prot of original sock creator (see ipv6_setsockopt,
    *			  IPV6_ADDRFORM for instance)

    *	@sk_err: last error

    *	@sk_err_soft: errors that don't cause failure but are the cause of a
    *		      persistent failure not just 'timed out'

    *	@sk_drops: raw/udp drops counter

    *	@sk_ack_backlog: current listen backlog
    *	@sk_max_ack_backlog: listen backlog set in listen()
    *	@sk_priority: %SO_PRIORITY setting
    *	@sk_type: socket type (%SOCK_STREAM, etc)
    *	@sk_protocol: which protocol this socket belongs in this network family

    *	@sk_peer_pid: &struct pid for this socket's peer
    *	@sk_peer_cred: %SO_PEERCRED setting

    *	@sk_rcvlowat: %SO_RCVLOWAT setting
    *	@sk_rcvtimeo: %SO_RCVTIMEO setting
    *	@sk_sndtimeo: %SO_SNDTIMEO setting

    *	@sk_rxhash: flow hash received from netif layer

    *	@sk_filter: socket filtering instructions
    *	@sk_protinfo: private area, net family specific, when not using slab
    *	@sk_timer: sock cleanup timer
    *	@sk_stamp: time stamp of last packet received
    *	@sk_socket: Identd and reporting IO signals
    *	@sk_user_data: RPC layer private data
    *	@sk_sndmsg_page: cached page for sendmsg
    *	@sk_sndmsg_off: cached offset for sendmsg
    *	@sk_send_head: front of stuff to transmit

    *	@sk_security: used by security modules

    *	@sk_mark: generic packet mark

    *	@sk_classid: this socket's cgroup classid

    *	@sk_write_pending: a write to stream socket waits to start
    *	@sk_state_change: callback to indicate change in the state of the sock
    *	@sk_data_ready: callback to indicate there is data to be processed
    *	@sk_write_space: callback to indicate there is bf sending space available
    *	@sk_error_report: callback to indicate errors (e.g. %MSG_ERRQUEUE)
    *	@sk_backlog_rcv: callback to process the backlog
    *	@sk_destruct: called at sock freeing time, i.e. when all refcnt == 0

   */
  struct sock {
  	/*

  	 * Now struct inet_timewait_sock also uses sock_common, so please just

  	 * don't add nothing before this first member (__sk_common) --acme
  	 */
  	struct sock_common	__sk_common;

  #define sk_node			__sk_common.skc_node
  #define sk_nulls_node		__sk_common.skc_nulls_node
  #define sk_refcnt		__sk_common.skc_refcnt

  #define sk_tx_queue_mapping	__sk_common.skc_tx_queue_mapping

  #define sk_dontcopy_begin	__sk_common.skc_dontcopy_begin
  #define sk_dontcopy_end		__sk_common.skc_dontcopy_end

  #define sk_hash			__sk_common.skc_hash

  #define sk_family		__sk_common.skc_family
  #define sk_state		__sk_common.skc_state
  #define sk_reuse		__sk_common.skc_reuse
  #define sk_bound_dev_if		__sk_common.skc_bound_dev_if

  #define sk_bind_node		__sk_common.skc_bind_node

  #define sk_prot			__sk_common.skc_prot

  #define sk_net			__sk_common.skc_net

  	socket_lock_t		sk_lock;

  	struct sk_buff_head	sk_receive_queue;

  	/*
  	 * The backlog queue is special, it is always used with
  	 * the per-socket spinlock held and requires low latency
  	 * access. Therefore we special case it's implementation.

  	 * Note : rmem_alloc is in this structure to fill a hole
  	 * on 64bit arches, not because its logically part of
  	 * backlog.

  	 */
  	struct {

  		atomic_t	rmem_alloc;
  		int		len;
  		struct sk_buff	*head;
  		struct sk_buff	*tail;

  	} sk_backlog;

  #define sk_rmem_alloc sk_backlog.rmem_alloc
  	int			sk_forward_alloc;
  #ifdef CONFIG_RPS
  	__u32			sk_rxhash;
  #endif
  	atomic_t		sk_drops;
  	int			sk_rcvbuf;
  
  	struct sk_filter __rcu	*sk_filter;

  	struct socket_wq __rcu	*sk_wq;

  
  #ifdef CONFIG_NET_DMA
  	struct sk_buff_head	sk_async_wait_queue;
  #endif

  #ifdef CONFIG_XFRM

  	struct xfrm_policy	*sk_policy[2];

  #endif

  	unsigned long 		sk_flags;
  	struct dst_entry	*sk_dst_cache;

  	spinlock_t		sk_dst_lock;

  	atomic_t		sk_wmem_alloc;
  	atomic_t		sk_omem_alloc;

  	int			sk_sndbuf;

  	struct sk_buff_head	sk_write_queue;

  	kmemcheck_bitfield_begin(flags);
  	unsigned int		sk_shutdown  : 2,
  				sk_no_check  : 2,
  				sk_userlocks : 4,
  				sk_protocol  : 8,
  				sk_type      : 16;
  	kmemcheck_bitfield_end(flags);

  	int			sk_wmem_queued;

  	gfp_t			sk_allocation;

  	int			sk_route_caps;

  	int			sk_route_nocaps;

  	int			sk_gso_type;

  	unsigned int		sk_gso_max_size;

  	int			sk_rcvlowat;

  	unsigned long	        sk_lingertime;

  	struct sk_buff_head	sk_error_queue;

  	struct proto		*sk_prot_creator;

  	rwlock_t		sk_callback_lock;
  	int			sk_err,
  				sk_err_soft;
  	unsigned short		sk_ack_backlog;
  	unsigned short		sk_max_ack_backlog;
  	__u32			sk_priority;

  	struct pid		*sk_peer_pid;
  	const struct cred	*sk_peer_cred;

  	long			sk_rcvtimeo;
  	long			sk_sndtimeo;

  	void			*sk_protinfo;
  	struct timer_list	sk_timer;

  	ktime_t			sk_stamp;

  	struct socket		*sk_socket;
  	void			*sk_user_data;
  	struct page		*sk_sndmsg_page;
  	struct sk_buff		*sk_send_head;
  	__u32			sk_sndmsg_off;
  	int			sk_write_pending;

  #ifdef CONFIG_SECURITY

  	void			*sk_security;

  #endif

  	__u32			sk_mark;

  	u32			sk_classid;

  	void			(*sk_state_change)(struct sock *sk);
  	void			(*sk_data_ready)(struct sock *sk, int bytes);
  	void			(*sk_write_space)(struct sock *sk);
  	void			(*sk_error_report)(struct sock *sk);
    	int			(*sk_backlog_rcv)(struct sock *sk,
  						  struct sk_buff *skb);  
  	void                    (*sk_destruct)(struct sock *sk);
  };
  
  /*
   * Hashed lists helper routines
   */

  static inline struct sock *sk_entry(const struct hlist_node *node)
  {
  	return hlist_entry(node, struct sock, sk_node);
  }

  static inline struct sock *__sk_head(const struct hlist_head *head)

  {
  	return hlist_entry(head->first, struct sock, sk_node);
  }

  static inline struct sock *sk_head(const struct hlist_head *head)

  {
  	return hlist_empty(head) ? NULL : __sk_head(head);
  }

  static inline struct sock *__sk_nulls_head(const struct hlist_nulls_head *head)
  {
  	return hlist_nulls_entry(head->first, struct sock, sk_nulls_node);
  }
  
  static inline struct sock *sk_nulls_head(const struct hlist_nulls_head *head)
  {
  	return hlist_nulls_empty(head) ? NULL : __sk_nulls_head(head);
  }

  static inline struct sock *sk_next(const struct sock *sk)

  {
  	return sk->sk_node.next ?
  		hlist_entry(sk->sk_node.next, struct sock, sk_node) : NULL;
  }

  static inline struct sock *sk_nulls_next(const struct sock *sk)
  {
  	return (!is_a_nulls(sk->sk_nulls_node.next)) ?
  		hlist_nulls_entry(sk->sk_nulls_node.next,
  				  struct sock, sk_nulls_node) :
  		NULL;
  }

  static inline int sk_unhashed(const struct sock *sk)

  {
  	return hlist_unhashed(&sk->sk_node);
  }

  static inline int sk_hashed(const struct sock *sk)

  {

  	return !sk_unhashed(sk);

  }
  
  static __inline__ void sk_node_init(struct hlist_node *node)
  {
  	node->pprev = NULL;
  }

  static __inline__ void sk_nulls_node_init(struct hlist_nulls_node *node)
  {
  	node->pprev = NULL;
  }

  static __inline__ void __sk_del_node(struct sock *sk)
  {
  	__hlist_del(&sk->sk_node);
  }

  /* NB: equivalent to hlist_del_init_rcu */

  static __inline__ int __sk_del_node_init(struct sock *sk)
  {
  	if (sk_hashed(sk)) {
  		__sk_del_node(sk);
  		sk_node_init(&sk->sk_node);
  		return 1;
  	}
  	return 0;
  }
  
  /* Grab socket reference count. This operation is valid only
     when sk is ALREADY grabbed f.e. it is found in hash table
     or a list and the lookup is made under lock preventing hash table
     modifications.
   */
  
  static inline void sock_hold(struct sock *sk)
  {
  	atomic_inc(&sk->sk_refcnt);
  }
  
  /* Ungrab socket in the context, which assumes that socket refcnt
     cannot hit zero, f.e. it is true in context of any socketcall.
   */
  static inline void __sock_put(struct sock *sk)
  {
  	atomic_dec(&sk->sk_refcnt);
  }
  
  static __inline__ int sk_del_node_init(struct sock *sk)
  {
  	int rc = __sk_del_node_init(sk);
  
  	if (rc) {
  		/* paranoid for a while -acme */
  		WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
  		__sock_put(sk);
  	}
  	return rc;
  }

  #define sk_del_node_init_rcu(sk)	sk_del_node_init(sk)

  static __inline__ int __sk_nulls_del_node_init_rcu(struct sock *sk)

  {
  	if (sk_hashed(sk)) {

  		hlist_nulls_del_init_rcu(&sk->sk_nulls_node);

  		return 1;
  	}
  	return 0;
  }

  static __inline__ int sk_nulls_del_node_init_rcu(struct sock *sk)

  {

  	int rc = __sk_nulls_del_node_init_rcu(sk);

  
  	if (rc) {
  		/* paranoid for a while -acme */
  		WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
  		__sock_put(sk);
  	}
  	return rc;
  }

  static __inline__ void __sk_add_node(struct sock *sk, struct hlist_head *list)
  {
  	hlist_add_head(&sk->sk_node, list);
  }
  
  static __inline__ void sk_add_node(struct sock *sk, struct hlist_head *list)
  {
  	sock_hold(sk);
  	__sk_add_node(sk, list);
  }

  static __inline__ void sk_add_node_rcu(struct sock *sk, struct hlist_head *list)
  {
  	sock_hold(sk);
  	hlist_add_head_rcu(&sk->sk_node, list);
  }

  static __inline__ void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)

  {

  	hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);

  }

  static __inline__ void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)

  {
  	sock_hold(sk);

  	__sk_nulls_add_node_rcu(sk, list);

  }

  static __inline__ void __sk_del_bind_node(struct sock *sk)
  {
  	__hlist_del(&sk->sk_bind_node);
  }
  
  static __inline__ void sk_add_bind_node(struct sock *sk,
  					struct hlist_head *list)
  {
  	hlist_add_head(&sk->sk_bind_node, list);
  }
  
  #define sk_for_each(__sk, node, list) \
  	hlist_for_each_entry(__sk, node, list, sk_node)

  #define sk_for_each_rcu(__sk, node, list) \
  	hlist_for_each_entry_rcu(__sk, node, list, sk_node)

  #define sk_nulls_for_each(__sk, node, list) \
  	hlist_nulls_for_each_entry(__sk, node, list, sk_nulls_node)
  #define sk_nulls_for_each_rcu(__sk, node, list) \
  	hlist_nulls_for_each_entry_rcu(__sk, node, list, sk_nulls_node)

  #define sk_for_each_from(__sk, node) \
  	if (__sk && ({ node = &(__sk)->sk_node; 1; })) \
  		hlist_for_each_entry_from(__sk, node, sk_node)

  #define sk_nulls_for_each_from(__sk, node) \
  	if (__sk && ({ node = &(__sk)->sk_nulls_node; 1; })) \
  		hlist_nulls_for_each_entry_from(__sk, node, sk_nulls_node)

  #define sk_for_each_safe(__sk, node, tmp, list) \
  	hlist_for_each_entry_safe(__sk, node, tmp, list, sk_node)
  #define sk_for_each_bound(__sk, node, list) \
  	hlist_for_each_entry(__sk, node, list, sk_bind_node)
  
  /* Sock flags */
  enum sock_flags {
  	SOCK_DEAD,
  	SOCK_DONE,
  	SOCK_URGINLINE,
  	SOCK_KEEPOPEN,
  	SOCK_LINGER,
  	SOCK_DESTROY,
  	SOCK_BROADCAST,
  	SOCK_TIMESTAMP,
  	SOCK_ZAPPED,
  	SOCK_USE_WRITE_QUEUE, /* whether to call sk->sk_write_space in sock_wfree */
  	SOCK_DBG, /* %SO_DEBUG setting */
  	SOCK_RCVTSTAMP, /* %SO_TIMESTAMP setting */

  	SOCK_RCVTSTAMPNS, /* %SO_TIMESTAMPNS setting */

  	SOCK_LOCALROUTE, /* route locally only, %SO_DONTROUTE setting */
  	SOCK_QUEUE_SHRUNK, /* write queue has been shrunk recently */

  	SOCK_TIMESTAMPING_TX_HARDWARE,  /* %SOF_TIMESTAMPING_TX_HARDWARE */
  	SOCK_TIMESTAMPING_TX_SOFTWARE,  /* %SOF_TIMESTAMPING_TX_SOFTWARE */
  	SOCK_TIMESTAMPING_RX_HARDWARE,  /* %SOF_TIMESTAMPING_RX_HARDWARE */
  	SOCK_TIMESTAMPING_RX_SOFTWARE,  /* %SOF_TIMESTAMPING_RX_SOFTWARE */
  	SOCK_TIMESTAMPING_SOFTWARE,     /* %SOF_TIMESTAMPING_SOFTWARE */
  	SOCK_TIMESTAMPING_RAW_HARDWARE, /* %SOF_TIMESTAMPING_RAW_HARDWARE */
  	SOCK_TIMESTAMPING_SYS_HARDWARE, /* %SOF_TIMESTAMPING_SYS_HARDWARE */

  	SOCK_FASYNC, /* fasync() active */

  	SOCK_RXQ_OVFL,

  	SOCK_ZEROCOPY, /* buffers from userspace */

  };

  static inline void sock_copy_flags(struct sock *nsk, struct sock *osk)
  {
  	nsk->sk_flags = osk->sk_flags;
  }

  static inline void sock_set_flag(struct sock *sk, enum sock_flags flag)
  {
  	__set_bit(flag, &sk->sk_flags);
  }
  
  static inline void sock_reset_flag(struct sock *sk, enum sock_flags flag)
  {
  	__clear_bit(flag, &sk->sk_flags);
  }
  
  static inline int sock_flag(struct sock *sk, enum sock_flags flag)
  {
  	return test_bit(flag, &sk->sk_flags);
  }
  
  static inline void sk_acceptq_removed(struct sock *sk)
  {
  	sk->sk_ack_backlog--;
  }
  
  static inline void sk_acceptq_added(struct sock *sk)
  {
  	sk->sk_ack_backlog++;
  }
  
  static inline int sk_acceptq_is_full(struct sock *sk)
  {

  	return sk->sk_ack_backlog > sk->sk_max_ack_backlog;

  }
  
  /*
   * Compute minimal free write space needed to queue new packets.
   */
  static inline int sk_stream_min_wspace(struct sock *sk)
  {

  	return sk->sk_wmem_queued >> 1;

  }
  
  static inline int sk_stream_wspace(struct sock *sk)
  {
  	return sk->sk_sndbuf - sk->sk_wmem_queued;
  }
  
  extern void sk_stream_write_space(struct sock *sk);
  
  static inline int sk_stream_memory_free(struct sock *sk)
  {
  	return sk->sk_wmem_queued < sk->sk_sndbuf;
  }

  /* OOB backlog add */

  static inline void __sk_add_backlog(struct sock *sk, struct sk_buff *skb)

  {

  	/* dont let skb dst not refcounted, we are going to leave rcu lock */
  	skb_dst_force(skb);
  
  	if (!sk->sk_backlog.tail)
  		sk->sk_backlog.head = skb;
  	else

  		sk->sk_backlog.tail->next = skb;

  
  	sk->sk_backlog.tail = skb;

  	skb->next = NULL;
  }

  /*
   * Take into account size of receive queue and backlog queue

   * Do not take into account this skb truesize,
   * to allow even a single big packet to come.

   */
  static inline bool sk_rcvqueues_full(const struct sock *sk, const struct sk_buff *skb)
  {
  	unsigned int qsize = sk->sk_backlog.len + atomic_read(&sk->sk_rmem_alloc);

  	return qsize > sk->sk_rcvbuf;

  }

  /* The per-socket spinlock must be held here. */

  static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *skb)

  {

  	if (sk_rcvqueues_full(sk, skb))

  		return -ENOBUFS;

  	__sk_add_backlog(sk, skb);

  	sk->sk_backlog.len += skb->truesize;
  	return 0;
  }

  static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
  {
  	return sk->sk_backlog_rcv(sk, skb);
  }

  static inline void sock_rps_record_flow(const struct sock *sk)
  {
  #ifdef CONFIG_RPS
  	struct rps_sock_flow_table *sock_flow_table;
  
  	rcu_read_lock();
  	sock_flow_table = rcu_dereference(rps_sock_flow_table);
  	rps_record_sock_flow(sock_flow_table, sk->sk_rxhash);
  	rcu_read_unlock();
  #endif
  }
  
  static inline void sock_rps_reset_flow(const struct sock *sk)
  {
  #ifdef CONFIG_RPS
  	struct rps_sock_flow_table *sock_flow_table;
  
  	rcu_read_lock();
  	sock_flow_table = rcu_dereference(rps_sock_flow_table);
  	rps_reset_sock_flow(sock_flow_table, sk->sk_rxhash);
  	rcu_read_unlock();
  #endif
  }

  static inline void sock_rps_save_rxhash(struct sock *sk,
  					const struct sk_buff *skb)

  {
  #ifdef CONFIG_RPS

  	if (unlikely(sk->sk_rxhash != skb->rxhash)) {

  		sock_rps_reset_flow(sk);

  		sk->sk_rxhash = skb->rxhash;

  	}
  #endif
  }

  static inline void sock_rps_reset_rxhash(struct sock *sk)
  {
  #ifdef CONFIG_RPS
  	sock_rps_reset_flow(sk);
  	sk->sk_rxhash = 0;
  #endif
  }

  #define sk_wait_event(__sk, __timeo, __condition)			\
  	({	int __rc;						\
  		release_sock(__sk);					\
  		__rc = __condition;					\
  		if (!__rc) {						\
  			*(__timeo) = schedule_timeout(*(__timeo));	\
  		}							\
  		lock_sock(__sk);					\
  		__rc = __condition;					\
  		__rc;							\
  	})

  
  extern int sk_stream_wait_connect(struct sock *sk, long *timeo_p);
  extern int sk_stream_wait_memory(struct sock *sk, long *timeo_p);
  extern void sk_stream_wait_close(struct sock *sk, long timeo_p);
  extern int sk_stream_error(struct sock *sk, int flags, int err);
  extern void sk_stream_kill_queues(struct sock *sk);
  
  extern int sk_wait_data(struct sock *sk, long *timeo);

  struct request_sock_ops;

  struct timewait_sock_ops;

  struct inet_hashinfo;

  struct raw_hashinfo;

  struct module;

  /* Networking protocol blocks we attach to sockets.
   * socket layer -> transport layer interface
   * transport -> network interface is defined by struct inet_proto
   */
  struct proto {
  	void			(*close)(struct sock *sk, 
  					long timeout);
  	int			(*connect)(struct sock *sk,
  				        struct sockaddr *uaddr, 
  					int addr_len);
  	int			(*disconnect)(struct sock *sk, int flags);
  
  	struct sock *		(*accept) (struct sock *sk, int flags, int *err);
  
  	int			(*ioctl)(struct sock *sk, int cmd,
  					 unsigned long arg);
  	int			(*init)(struct sock *sk);

  	void			(*destroy)(struct sock *sk);

  	void			(*shutdown)(struct sock *sk, int how);
  	int			(*setsockopt)(struct sock *sk, int level, 
  					int optname, char __user *optval,

  					unsigned int optlen);

  	int			(*getsockopt)(struct sock *sk, int level, 
  					int optname, char __user *optval, 
  					int __user *option);  	 

  #ifdef CONFIG_COMPAT

  	int			(*compat_setsockopt)(struct sock *sk,
  					int level,
  					int optname, char __user *optval,

  					unsigned int optlen);

  	int			(*compat_getsockopt)(struct sock *sk,
  					int level,
  					int optname, char __user *optval,
  					int __user *option);

  	int			(*compat_ioctl)(struct sock *sk,
  					unsigned int cmd, unsigned long arg);

  #endif

  	int			(*sendmsg)(struct kiocb *iocb, struct sock *sk,
  					   struct msghdr *msg, size_t len);
  	int			(*recvmsg)(struct kiocb *iocb, struct sock *sk,
  					   struct msghdr *msg,
  					size_t len, int noblock, int flags, 
  					int *addr_len);
  	int			(*sendpage)(struct sock *sk, struct page *page,
  					int offset, size_t size, int flags);
  	int			(*bind)(struct sock *sk, 
  					struct sockaddr *uaddr, int addr_len);
  
  	int			(*backlog_rcv) (struct sock *sk, 
  						struct sk_buff *skb);
  
  	/* Keeping track of sk's, looking them up, and port selection methods. */
  	void			(*hash)(struct sock *sk);
  	void			(*unhash)(struct sock *sk);

  	void			(*rehash)(struct sock *sk);

  	int			(*get_port)(struct sock *sk, unsigned short snum);

  	void			(*clear_sk)(struct sock *sk, int size);

  	/* Keeping track of sockets in use */

  #ifdef CONFIG_PROC_FS

  	unsigned int		inuse_idx;

  #endif

  	/* Memory pressure */

  	void			(*enter_memory_pressure)(struct sock *sk);

  	atomic_long_t		*memory_allocated;	/* Current allocated memory. */

  	struct percpu_counter	*sockets_allocated;	/* Current number of sockets. */

  	/*
  	 * Pressure flag: try to collapse.
  	 * Technical note: it is used by multiple contexts non atomically.

  	 * All the __sk_mem_schedule() is of this nature: accounting

  	 * is strict, actions are advisory and have some latency.
  	 */
  	int			*memory_pressure;

  	long			*sysctl_mem;

  	int			*sysctl_wmem;
  	int			*sysctl_rmem;
  	int			max_header;

  	bool			no_autobind;

  	struct kmem_cache	*slab;

  	unsigned int		obj_size;

  	int			slab_flags;

  	struct percpu_counter	*orphan_count;

  	struct request_sock_ops	*rsk_prot;

  	struct timewait_sock_ops *twsk_prot;

  	union {
  		struct inet_hashinfo	*hashinfo;

  		struct udp_table	*udp_table;

  		struct raw_hashinfo	*raw_hash;

  	} h;

  	struct module		*owner;
  
  	char			name[32];
  
  	struct list_head	node;

  #ifdef SOCK_REFCNT_DEBUG
  	atomic_t		socks;
  #endif

  };
  
  extern int proto_register(struct proto *prot, int alloc_slab);
  extern void proto_unregister(struct proto *prot);

  #ifdef SOCK_REFCNT_DEBUG
  static inline void sk_refcnt_debug_inc(struct sock *sk)
  {
  	atomic_inc(&sk->sk_prot->socks);
  }
  
  static inline void sk_refcnt_debug_dec(struct sock *sk)
  {
  	atomic_dec(&sk->sk_prot->socks);
  	printk(KERN_DEBUG "%s socket %p released, %d are still alive
  ",
  	       sk->sk_prot->name, sk, atomic_read(&sk->sk_prot->socks));
  }
  
  static inline void sk_refcnt_debug_release(const struct sock *sk)
  {
  	if (atomic_read(&sk->sk_refcnt) != 1)
  		printk(KERN_DEBUG "Destruction of the %s socket %p delayed, refcnt=%d
  ",
  		       sk->sk_prot->name, sk, atomic_read(&sk->sk_refcnt));
  }
  #else /* SOCK_REFCNT_DEBUG */
  #define sk_refcnt_debug_inc(sk) do { } while (0)
  #define sk_refcnt_debug_dec(sk) do { } while (0)
  #define sk_refcnt_debug_release(sk) do { } while (0)
  #endif /* SOCK_REFCNT_DEBUG */

  
  #ifdef CONFIG_PROC_FS

  /* Called with local bh disabled */

  extern void sock_prot_inuse_add(struct net *net, struct proto *prot, int inc);
  extern int sock_prot_inuse_get(struct net *net, struct proto *proto);

  #else

  static void inline sock_prot_inuse_add(struct net *net, struct proto *prot,
  		int inc)

  {
  }

  #endif

  /* With per-bucket locks this operation is not-atomic, so that
   * this version is not worse.
   */
  static inline void __sk_prot_rehash(struct sock *sk)
  {
  	sk->sk_prot->unhash(sk);
  	sk->sk_prot->hash(sk);
  }

  void sk_prot_clear_portaddr_nulls(struct sock *sk, int size);

  /* About 10 seconds */
  #define SOCK_DESTROY_TIME (10*HZ)
  
  /* Sockets 0-1023 can't be bound to unless you are superuser */
  #define PROT_SOCK	1024
  
  #define SHUTDOWN_MASK	3
  #define RCV_SHUTDOWN	1
  #define SEND_SHUTDOWN	2
  
  #define SOCK_SNDBUF_LOCK	1
  #define SOCK_RCVBUF_LOCK	2
  #define SOCK_BINDADDR_LOCK	4
  #define SOCK_BINDPORT_LOCK	8
  
  /* sock_iocb: used to kick off async processing of socket ios */
  struct sock_iocb {
  	struct list_head	list;
  
  	int			flags;
  	int			size;
  	struct socket		*sock;
  	struct sock		*sk;
  	struct scm_cookie	*scm;
  	struct msghdr		*msg, async_msg;

  	struct kiocb		*kiocb;
  };
  
  static inline struct sock_iocb *kiocb_to_siocb(struct kiocb *iocb)
  {
  	return (struct sock_iocb *)iocb->private;
  }
  
  static inline struct kiocb *siocb_to_kiocb(struct sock_iocb *si)
  {
  	return si->kiocb;
  }
  
  struct socket_alloc {
  	struct socket socket;
  	struct inode vfs_inode;
  };
  
  static inline struct socket *SOCKET_I(struct inode *inode)
  {
  	return &container_of(inode, struct socket_alloc, vfs_inode)->socket;
  }
  
  static inline struct inode *SOCK_INODE(struct socket *socket)
  {
  	return &container_of(socket, struct socket_alloc, socket)->vfs_inode;
  }

  /*
   * Functions for memory accounting
   */
  extern int __sk_mem_schedule(struct sock *sk, int size, int kind);
  extern void __sk_mem_reclaim(struct sock *sk);

  #define SK_MEM_QUANTUM ((int)PAGE_SIZE)
  #define SK_MEM_QUANTUM_SHIFT ilog2(SK_MEM_QUANTUM)
  #define SK_MEM_SEND	0
  #define SK_MEM_RECV	1

  static inline int sk_mem_pages(int amt)

  {

  	return (amt + SK_MEM_QUANTUM - 1) >> SK_MEM_QUANTUM_SHIFT;

  }

  static inline int sk_has_account(struct sock *sk)

  {

  	/* return true if protocol supports memory accounting */
  	return !!sk->sk_prot->memory_allocated;

  }

  static inline int sk_wmem_schedule(struct sock *sk, int size)

  {

  	if (!sk_has_account(sk))
  		return 1;
  	return size <= sk->sk_forward_alloc ||
  		__sk_mem_schedule(sk, size, SK_MEM_SEND);

  }

  static inline int sk_rmem_schedule(struct sock *sk, int size)

  {

  	if (!sk_has_account(sk))
  		return 1;

  	return size <= sk->sk_forward_alloc ||

  		__sk_mem_schedule(sk, size, SK_MEM_RECV);
  }
  
  static inline void sk_mem_reclaim(struct sock *sk)
  {
  	if (!sk_has_account(sk))
  		return;
  	if (sk->sk_forward_alloc >= SK_MEM_QUANTUM)
  		__sk_mem_reclaim(sk);
  }

  static inline void sk_mem_reclaim_partial(struct sock *sk)
  {
  	if (!sk_has_account(sk))
  		return;
  	if (sk->sk_forward_alloc > SK_MEM_QUANTUM)
  		__sk_mem_reclaim(sk);
  }

  static inline void sk_mem_charge(struct sock *sk, int size)
  {
  	if (!sk_has_account(sk))
  		return;
  	sk->sk_forward_alloc -= size;
  }
  
  static inline void sk_mem_uncharge(struct sock *sk, int size)
  {
  	if (!sk_has_account(sk))
  		return;
  	sk->sk_forward_alloc += size;
  }
  
  static inline void sk_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
  {

  	sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
  	sk->sk_wmem_queued -= skb->truesize;
  	sk_mem_uncharge(sk, skb->truesize);
  	__kfree_skb(skb);

  }

  /* Used by processes to "lock" a socket state, so that
   * interrupts and bottom half handlers won't change it
   * from under us. It essentially blocks any incoming
   * packets, so that we won't get any new data or any
   * packets that change the state of the socket.
   *
   * While locked, BH processing will add new packets to
   * the backlog queue.  This queue is processed by the
   * owner of the socket lock right before it is released.
   *
   * Since ~2.3.5 it is also exclusive sleep lock serializing
   * accesses from user process context.
   */

  #define sock_owned_by_user(sk)	((sk)->sk_lock.owned)

  /*
   * Macro so as to not evaluate some arguments when
   * lockdep is not enabled.
   *
   * Mark both the sk_lock and the sk_lock.slock as a
   * per-address-family lock class.
   */
  #define sock_lock_init_class_and_name(sk, sname, skey, name, key) 	\
  do {									\

  	sk->sk_lock.owned = 0;						\

  	init_waitqueue_head(&sk->sk_lock.wq);				\
  	spin_lock_init(&(sk)->sk_lock.slock);				\
  	debug_check_no_locks_freed((void *)&(sk)->sk_lock,		\
  			sizeof((sk)->sk_lock));				\
  	lockdep_set_class_and_name(&(sk)->sk_lock.slock,		\
  		       	(skey), (sname));				\
  	lockdep_init_map(&(sk)->sk_lock.dep_map, (name), (key), 0);	\
  } while (0)

  extern void lock_sock_nested(struct sock *sk, int subclass);

  
  static inline void lock_sock(struct sock *sk)
  {
  	lock_sock_nested(sk, 0);
  }

  extern void release_sock(struct sock *sk);

  
  /* BH context may only use the following locking interface. */
  #define bh_lock_sock(__sk)	spin_lock(&((__sk)->sk_lock.slock))

  #define bh_lock_sock_nested(__sk) \
  				spin_lock_nested(&((__sk)->sk_lock.slock), \
  				SINGLE_DEPTH_NESTING)

  #define bh_unlock_sock(__sk)	spin_unlock(&((__sk)->sk_lock.slock))

  extern bool lock_sock_fast(struct sock *sk);
  /**
   * unlock_sock_fast - complement of lock_sock_fast
   * @sk: socket
   * @slow: slow mode
   *
   * fast unlock socket for user context.
   * If slow mode is on, we call regular release_sock()
   */
  static inline void unlock_sock_fast(struct sock *sk, bool slow)

  {

  	if (slow)
  		release_sock(sk);
  	else
  		spin_unlock_bh(&sk->sk_lock.slock);

  }

  extern struct sock		*sk_alloc(struct net *net, int family,

  					  gfp_t priority,

  					  struct proto *prot);

  extern void			sk_free(struct sock *sk);

  extern void			sk_release_kernel(struct sock *sk);

  extern struct sock		*sk_clone(const struct sock *sk,

  					  const gfp_t priority);

  
  extern struct sk_buff		*sock_wmalloc(struct sock *sk,
  					      unsigned long size, int force,

  					      gfp_t priority);

  extern struct sk_buff		*sock_rmalloc(struct sock *sk,
  					      unsigned long size, int force,

  					      gfp_t priority);

  extern void			sock_wfree(struct sk_buff *skb);
  extern void			sock_rfree(struct sk_buff *skb);
  
  extern int			sock_setsockopt(struct socket *sock, int level,
  						int op, char __user *optval,

  						unsigned int optlen);

  
  extern int			sock_getsockopt(struct socket *sock, int level,
  						int op, char __user *optval, 
  						int __user *optlen);
  extern struct sk_buff 		*sock_alloc_send_skb(struct sock *sk,
  						     unsigned long size,
  						     int noblock,
  						     int *errcode);

  extern struct sk_buff 		*sock_alloc_send_pskb(struct sock *sk,
  						      unsigned long header_len,
  						      unsigned long data_len,
  						      int noblock,
  						      int *errcode);

  extern void *sock_kmalloc(struct sock *sk, int size,

  			  gfp_t priority);

  extern void sock_kfree_s(struct sock *sk, void *mem, int size);
  extern void sk_send_sigurg(struct sock *sk);

  #ifdef CONFIG_CGROUPS
  extern void sock_update_classid(struct sock *sk);
  #else
  static inline void sock_update_classid(struct sock *sk)
  {
  }
  #endif

  /*
   * Functions to fill in entries in struct proto_ops when a protocol
   * does not implement a particular function.
   */
  extern int                      sock_no_bind(struct socket *, 
  					     struct sockaddr *, int);
  extern int                      sock_no_connect(struct socket *,
  						struct sockaddr *, int, int);
  extern int                      sock_no_socketpair(struct socket *,
  						   struct socket *);
  extern int                      sock_no_accept(struct socket *,
  					       struct socket *, int);
  extern int                      sock_no_getname(struct socket *,
  						struct sockaddr *, int *, int);
  extern unsigned int             sock_no_poll(struct file *, struct socket *,
  					     struct poll_table_struct *);
  extern int                      sock_no_ioctl(struct socket *, unsigned int,
  					      unsigned long);
  extern int			sock_no_listen(struct socket *, int);
  extern int                      sock_no_shutdown(struct socket *, int);
  extern int			sock_no_getsockopt(struct socket *, int , int,
  						   char __user *, int __user *);
  extern int			sock_no_setsockopt(struct socket *, int, int,

  						   char __user *, unsigned int);

  extern int                      sock_no_sendmsg(struct kiocb *, struct socket *,
  						struct msghdr *, size_t);
  extern int                      sock_no_recvmsg(struct kiocb *, struct socket *,
  						struct msghdr *, size_t, int);
  extern int			sock_no_mmap(struct file *file,
  					     struct socket *sock,
  					     struct vm_area_struct *vma);
  extern ssize_t			sock_no_sendpage(struct socket *sock,
  						struct page *page,
  						int offset, size_t size, 
  						int flags);
  
  /*
   * Functions to fill in entries in struct proto_ops when a protocol
   * uses the inet style.
   */
  extern int sock_common_getsockopt(struct socket *sock, int level, int optname,
  				  char __user *optval, int __user *optlen);
  extern int sock_common_recvmsg(struct kiocb *iocb, struct socket *sock,
  			       struct msghdr *msg, size_t size, int flags);
  extern int sock_common_setsockopt(struct socket *sock, int level, int optname,

  				  char __user *optval, unsigned int optlen);

  extern int compat_sock_common_getsockopt(struct socket *sock, int level,
  		int optname, char __user *optval, int __user *optlen);
  extern int compat_sock_common_setsockopt(struct socket *sock, int level,

  		int optname, char __user *optval, unsigned int optlen);

  
  extern void sk_common_release(struct sock *sk);
  
  /*
   *	Default socket callbacks and setup code
   */
   
  /* Initialise core socket variables */
  extern void sock_init_data(struct socket *sock, struct sock *sk);

  extern void sk_filter_release_rcu(struct rcu_head *rcu);

  /**

   *	sk_filter_release - release a socket filter

   *	@fp: filter to remove
   *
   *	Remove a filter from a socket and release its resources.
   */

  static inline void sk_filter_release(struct sk_filter *fp)
  {
  	if (atomic_dec_and_test(&fp->refcnt))

  		call_rcu(&fp->rcu, sk_filter_release_rcu);

  }
  
  static inline void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp)

  {
  	unsigned int size = sk_filter_len(fp);
  
  	atomic_sub(size, &sk->sk_omem_alloc);

  	sk_filter_release(fp);

  }
  
  static inline void sk_filter_charge(struct sock *sk, struct sk_filter *fp)
  {
  	atomic_inc(&fp->refcnt);
  	atomic_add(sk_filter_len(fp), &sk->sk_omem_alloc);
  }
  
  /*
   * Socket reference counting postulates.
   *
   * * Each user of socket SHOULD hold a reference count.
   * * Each access point to socket (an hash table bucket, reference from a list,
   *   running timer, skb in flight MUST hold a reference count.
   * * When reference count hits 0, it means it will never increase back.
   * * When reference count hits 0, it means that no references from
   *   outside exist to this socket and current process on current CPU
   *   is last user and may/should destroy this socket.
   * * sk_free is called from any context: process, BH, IRQ. When
   *   it is called, socket has no references from outside -> sk_free
   *   may release descendant resources allocated by the socket, but
   *   to the time when it is called, socket is NOT referenced by any
   *   hash tables, lists etc.
   * * Packets, delivered from outside (from network or from another process)
   *   and enqueued on receive/error queues SHOULD NOT grab reference count,
   *   when they sit in queue. Otherwise, packets will leak to hole, when
   *   socket is looked up by one cpu and unhasing is made by another CPU.
   *   It is true for udp/raw, netlink (leak to receive and error queues), tcp
   *   (leak to backlog). Packet socket does all the processing inside
   *   BR_NETPROTO_LOCK, so that it has not this race condition. UNIX sockets
   *   use separate SMP lock, so that they are prone too.
   */
  
  /* Ungrab socket and destroy it, if it was the last reference. */
  static inline void sock_put(struct sock *sk)
  {
  	if (atomic_dec_and_test(&sk->sk_refcnt))
  		sk_free(sk);
  }

  extern int sk_receive_skb(struct sock *sk, struct sk_buff *skb,
  			  const int nested);

  static inline void sk_tx_queue_set(struct sock *sk, int tx_queue)
  {
  	sk->sk_tx_queue_mapping = tx_queue;
  }
  
  static inline void sk_tx_queue_clear(struct sock *sk)
  {
  	sk->sk_tx_queue_mapping = -1;
  }
  
  static inline int sk_tx_queue_get(const struct sock *sk)
  {

  	return sk ? sk->sk_tx_queue_mapping : -1;

  }

  static inline void sk_set_socket(struct sock *sk, struct socket *sock)
  {

  	sk_tx_queue_clear(sk);

  	sk->sk_socket = sock;
  }

  static inline wait_queue_head_t *sk_sleep(struct sock *sk)
  {

  	BUILD_BUG_ON(offsetof(struct socket_wq, wait) != 0);
  	return &rcu_dereference_raw(sk->sk_wq)->wait;

  }

  /* Detach socket from process context.
   * Announce socket dead, detach it from wait queue and inode.
   * Note that parent inode held reference count on this struct sock,
   * we do not release it in this function, because protocol
   * probably wants some additional cleanups or even continuing
   * to work with this socket (TCP).
   */
  static inline void sock_orphan(struct sock *sk)
  {
  	write_lock_bh(&sk->sk_callback_lock);
  	sock_set_flag(sk, SOCK_DEAD);

  	sk_set_socket(sk, NULL);

  	sk->sk_wq  = NULL;

  	write_unlock_bh(&sk->sk_callback_lock);
  }
  
  static inline void sock_graft(struct sock *sk, struct socket *parent)
  {
  	write_lock_bh(&sk->sk_callback_lock);

  	sk->sk_wq = parent->wq;

  	parent->sk = sk;

  	sk_set_socket(sk, parent);

  	security_sock_graft(sk, parent);

  	write_unlock_bh(&sk->sk_callback_lock);
  }
  
  extern int sock_i_uid(struct sock *sk);
  extern unsigned long sock_i_ino(struct sock *sk);
  
  static inline struct dst_entry *
  __sk_dst_get(struct sock *sk)
  {

  	return rcu_dereference_check(sk->sk_dst_cache, sock_owned_by_user(sk) ||

  						       lockdep_is_held(&sk->sk_lock.slock));

  }
  
  static inline struct dst_entry *
  sk_dst_get(struct sock *sk)
  {
  	struct dst_entry *dst;

  	rcu_read_lock();
  	dst = rcu_dereference(sk->sk_dst_cache);

  	if (dst)
  		dst_hold(dst);

  	rcu_read_unlock();

  	return dst;
  }

  extern void sk_reset_txq(struct sock *sk);
  
  static inline void dst_negative_advice(struct sock *sk)
  {
  	struct dst_entry *ndst, *dst = __sk_dst_get(sk);
  
  	if (dst && dst->ops->negative_advice) {
  		ndst = dst->ops->negative_advice(dst);
  
  		if (ndst != dst) {
  			rcu_assign_pointer(sk->sk_dst_cache, ndst);
  			sk_reset_txq(sk);
  		}
  	}
  }

  static inline void
  __sk_dst_set(struct sock *sk, struct dst_entry *dst)
  {
  	struct dst_entry *old_dst;

  	sk_tx_queue_clear(sk);

  	/*
  	 * This can be called while sk is owned by the caller only,
  	 * with no state that can be checked in a rcu_dereference_check() cond
  	 */
  	old_dst = rcu_dereference_raw(sk->sk_dst_cache);

  	rcu_assign_pointer(sk->sk_dst_cache, dst);

  	dst_release(old_dst);
  }
  
  static inline void
  sk_dst_set(struct sock *sk, struct dst_entry *dst)
  {

  	spin_lock(&sk->sk_dst_lock);

  	__sk_dst_set(sk, dst);

  	spin_unlock(&sk->sk_dst_lock);

  }
  
  static inline void
  __sk_dst_reset(struct sock *sk)
  {

  	__sk_dst_set(sk, NULL);

  }
  
  static inline void
  sk_dst_reset(struct sock *sk)
  {

  	spin_lock(&sk->sk_dst_lock);

  	__sk_dst_reset(sk);

  	spin_unlock(&sk->sk_dst_lock);

  }

  extern struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie);

  extern struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie);

  static inline int sk_can_gso(const struct sock *sk)
  {
  	return net_gso_ok(sk->sk_route_caps, sk->sk_gso_type);
  }

  extern void sk_setup_caps(struct sock *sk, struct dst_entry *dst);

  static inline void sk_nocaps_add(struct sock *sk, int flags)
  {
  	sk->sk_route_nocaps |= flags;
  	sk->sk_route_caps &= ~flags;
  }

  static inline int skb_do_copy_data_nocache(struct sock *sk, struct sk_buff *skb,
  					   char __user *from, char *to,

  					   int copy, int offset)

  {
  	if (skb->ip_summed == CHECKSUM_NONE) {
  		int err = 0;
  		__wsum csum = csum_and_copy_from_user(from, to, copy, 0, &err);
  		if (err)
  			return err;

  		skb->csum = csum_block_add(skb->csum, csum, offset);

  	} else if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
  		if (!access_ok(VERIFY_READ, from, copy) ||
  		    __copy_from_user_nocache(to, from, copy))
  			return -EFAULT;
  	} else if (copy_from_user(to, from, copy))
  		return -EFAULT;
  
  	return 0;
  }
  
  static inline int skb_add_data_nocache(struct sock *sk, struct sk_buff *skb,
  				       char __user *from, int copy)
  {

  	int err, offset = skb->len;

  	err = skb_do_copy_data_nocache(sk, skb, from, skb_put(skb, copy),
  				       copy, offset);

  	if (err)

  		__skb_trim(skb, offset);

  
  	return err;
  }
  
  static inline int skb_copy_to_page_nocache(struct sock *sk, char __user *from,
  					   struct sk_buff *skb,
  					   struct page *page,
  					   int off, int copy)
  {
  	int err;

  	err = skb_do_copy_data_nocache(sk, skb, from, page_address(page) + off,
  				       copy, skb->len);

  	if (err)
  		return err;
  
  	skb->len	     += copy;
  	skb->data_len	     += copy;
  	skb->truesize	     += copy;
  	sk->sk_wmem_queued   += copy;
  	sk_mem_charge(sk, copy);
  	return 0;
  }

  static inline int skb_copy_to_page(struct sock *sk, char __user *from,
  				   struct sk_buff *skb, struct page *page,
  				   int off, int copy)
  {
  	if (skb->ip_summed == CHECKSUM_NONE) {
  		int err = 0;

  		__wsum csum = csum_and_copy_from_user(from,

  						     page_address(page) + off,
  							    copy, 0, &err);
  		if (err)
  			return err;
  		skb->csum = csum_block_add(skb->csum, csum, skb->len);
  	} else if (copy_from_user(page_address(page) + off, from, copy))
  		return -EFAULT;
  
  	skb->len	     += copy;
  	skb->data_len	     += copy;
  	skb->truesize	     += copy;
  	sk->sk_wmem_queued   += copy;

  	sk_mem_charge(sk, copy);

  	return 0;
  }

  /**
   * sk_wmem_alloc_get - returns write allocations
   * @sk: socket
   *
   * Returns sk_wmem_alloc minus initial offset of one
   */
  static inline int sk_wmem_alloc_get(const struct sock *sk)
  {
  	return atomic_read(&sk->sk_wmem_alloc) - 1;
  }
  
  /**
   * sk_rmem_alloc_get - returns read allocations
   * @sk: socket
   *
   * Returns sk_rmem_alloc
   */
  static inline int sk_rmem_alloc_get(const struct sock *sk)
  {
  	return atomic_read(&sk->sk_rmem_alloc);
  }
  
  /**
   * sk_has_allocations - check if allocations are outstanding
   * @sk: socket
   *
   * Returns true if socket has write or read allocations
   */
  static inline int sk_has_allocations(const struct sock *sk)
  {
  	return sk_wmem_alloc_get(sk) || sk_rmem_alloc_get(sk);
  }

  /**

   * wq_has_sleeper - check if there are any waiting processes

   * @wq: struct socket_wq

   *

   * Returns true if socket_wq has waiting processes

   *

   * The purpose of the wq_has_sleeper and sock_poll_wait is to wrap the memory

   * barrier call. They were added due to the race found within the tcp code.
   *
   * Consider following tcp code paths:
   *
   * CPU1                  CPU2
   *
   * sys_select            receive packet
   *   ...                 ...
   *   __add_wait_queue    update tp->rcv_nxt
   *   ...                 ...
   *   tp->rcv_nxt check   sock_def_readable
   *   ...                 {

   *   schedule               rcu_read_lock();
   *                          wq = rcu_dereference(sk->sk_wq);
   *                          if (wq && waitqueue_active(&wq->wait))
   *                              wake_up_interruptible(&wq->wait)

   *                          ...
   *                       }
   *
   * The race for tcp fires when the __add_wait_queue changes done by CPU1 stay
   * in its cache, and so does the tp->rcv_nxt update on CPU2 side.  The CPU1
   * could then endup calling schedule and sleep forever if there are no more
   * data on the socket.

   *

   */

  static inline bool wq_has_sleeper(struct socket_wq *wq)

  {

  	/*
  	 * We need to be sure we are in sync with the
  	 * add_wait_queue modifications to the wait queue.
  	 *
  	 * This memory barrier is paired in the sock_poll_wait.
  	 */

  	smp_mb();
  	return wq && waitqueue_active(&wq->wait);

  }
  
  /**
   * sock_poll_wait - place memory barrier behind the poll_wait call.
   * @filp:           file
   * @wait_address:   socket wait queue
   * @p:              poll_table
   *

   * See the comments in the wq_has_sleeper function.

   */
  static inline void sock_poll_wait(struct file *filp,
  		wait_queue_head_t *wait_address, poll_table *p)
  {
  	if (p && wait_address) {
  		poll_wait(filp, wait_address, p);
  		/*
  		 * We need to be sure we are in sync with the
  		 * socket flags modification.
  		 *

  		 * This memory barrier is paired in the wq_has_sleeper.

  		*/
  		smp_mb();
  	}
  }

  /*
   * 	Queue a received datagram if it will fit. Stream and sequenced
   *	protocols can't normally use this as they need to fit buffers in
   *	and play with them.
   *
   * 	Inlined as it's very short and called for pretty much every
   *	packet ever received.
   */
  
  static inline void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
  {

  	skb_orphan(skb);

  	skb->sk = sk;
  	skb->destructor = sock_wfree;

  	/*
  	 * We used to take a refcount on sk, but following operation
  	 * is enough to guarantee sk_free() wont free this sock until
  	 * all in-flight packets are completed
  	 */

  	atomic_add(skb->truesize, &sk->sk_wmem_alloc);
  }
  
  static inline void skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
  {

  	skb_orphan(skb);

  	skb->sk = sk;
  	skb->destructor = sock_rfree;
  	atomic_add(skb->truesize, &sk->sk_rmem_alloc);

  	sk_mem_charge(sk, skb->truesize);

  }
  
  extern void sk_reset_timer(struct sock *sk, struct timer_list* timer,
  			   unsigned long expires);
  
  extern void sk_stop_timer(struct sock *sk, struct timer_list* timer);

  extern int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);

  extern int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb);

  
  /*
   *	Recover an error report and clear atomically
   */
   
  static inline int sock_error(struct sock *sk)
  {

  	int err;
  	if (likely(!sk->sk_err))
  		return 0;
  	err = xchg(&sk->sk_err, 0);

  	return -err;
  }
  
  static inline unsigned long sock_wspace(struct sock *sk)
  {
  	int amt = 0;
  
  	if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
  		amt = sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc);
  		if (amt < 0) 
  			amt = 0;
  	}
  	return amt;
  }
  
  static inline void sk_wake_async(struct sock *sk, int how, int band)
  {

  	if (sock_flag(sk, SOCK_FASYNC))

  		sock_wake_async(sk->sk_socket, how, band);
  }
  
  #define SOCK_MIN_SNDBUF 2048

  /*
   * Since sk_rmem_alloc sums skb->truesize, even a small frame might need
   * sizeof(sk_buff) + MTU + padding, unless net driver perform copybreak
   */
  #define SOCK_MIN_RCVBUF (2048 + sizeof(struct sk_buff))

  
  static inline void sk_stream_moderate_sndbuf(struct sock *sk)
  {
  	if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK)) {

  		sk->sk_sndbuf = min(sk->sk_sndbuf, sk->sk_wmem_queued >> 1);

  		sk->sk_sndbuf = max(sk->sk_sndbuf, SOCK_MIN_SNDBUF);
  	}
  }

  struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp);

  
  static inline struct page *sk_stream_alloc_page(struct sock *sk)
  {
  	struct page *page = NULL;

  	page = alloc_pages(sk->sk_allocation, 0);
  	if (!page) {

  		sk->sk_prot->enter_memory_pressure(sk);

  		sk_stream_moderate_sndbuf(sk);
  	}
  	return page;
  }

  /*
   *	Default write policy as shown to user space via poll/select/SIGIO
   */
  static inline int sock_writeable(const struct sock *sk) 
  {

  	return atomic_read(&sk->sk_wmem_alloc) < (sk->sk_sndbuf >> 1);

  }

  static inline gfp_t gfp_any(void)

  {

  	return in_softirq() ? GFP_ATOMIC : GFP_KERNEL;

  }
  
  static inline long sock_rcvtimeo(const struct sock *sk, int noblock)
  {
  	return noblock ? 0 : sk->sk_rcvtimeo;
  }
  
  static inline long sock_sndtimeo(const struct sock *sk, int noblock)
  {
  	return noblock ? 0 : sk->sk_sndtimeo;
  }
  
  static inline int sock_rcvlowat(const struct sock *sk, int waitall, int len)
  {
  	return (waitall ? len : min_t(int, sk->sk_rcvlowat, len)) ? : 1;
  }
  
  /* Alas, with timeout socket operations are not restartable.
   * Compare this to poll().
   */
  static inline int sock_intr_errno(long timeo)
  {
  	return timeo == MAX_SCHEDULE_TIMEOUT ? -ERESTARTSYS : -EINTR;
  }

  extern void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
  	struct sk_buff *skb);

  static __inline__ void
  sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb)
  {

  	ktime_t kt = skb->tstamp;

  	struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);

  	/*
  	 * generate control messages if
  	 * - receive time stamping in software requested (SOCK_RCVTSTAMP
  	 *   or SOCK_TIMESTAMPING_RX_SOFTWARE)
  	 * - software time stamp available and wanted
  	 *   (SOCK_TIMESTAMPING_SOFTWARE)
  	 * - hardware time stamps available and wanted
  	 *   (SOCK_TIMESTAMPING_SYS_HARDWARE or
  	 *   SOCK_TIMESTAMPING_RAW_HARDWARE)
  	 */
  	if (sock_flag(sk, SOCK_RCVTSTAMP) ||
  	    sock_flag(sk, SOCK_TIMESTAMPING_RX_SOFTWARE) ||
  	    (kt.tv64 && sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE)) ||
  	    (hwtstamps->hwtstamp.tv64 &&
  	     sock_flag(sk, SOCK_TIMESTAMPING_RAW_HARDWARE)) ||
  	    (hwtstamps->syststamp.tv64 &&
  	     sock_flag(sk, SOCK_TIMESTAMPING_SYS_HARDWARE)))

  		__sock_recv_timestamp(msg, sk, skb);
  	else

  		sk->sk_stamp = kt;

  }

  extern void __sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
  				     struct sk_buff *skb);
  
  static inline void sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
  					  struct sk_buff *skb)
  {
  #define FLAGS_TS_OR_DROPS ((1UL << SOCK_RXQ_OVFL)			| \
  			   (1UL << SOCK_RCVTSTAMP)			| \
  			   (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE)	| \
  			   (1UL << SOCK_TIMESTAMPING_SOFTWARE)		| \
  			   (1UL << SOCK_TIMESTAMPING_RAW_HARDWARE) 	| \
  			   (1UL << SOCK_TIMESTAMPING_SYS_HARDWARE))
  
  	if (sk->sk_flags & FLAGS_TS_OR_DROPS)
  		__sock_recv_ts_and_drops(msg, sk, skb);
  	else
  		sk->sk_stamp = skb->tstamp;
  }

  /**

   * sock_tx_timestamp - checks whether the outgoing packet is to be time stamped

   * @sk:		socket sending this packet

   * @tx_flags:	filled with instructions for time stamping

   *
   * Currently only depends on SOCK_TIMESTAMPING* flags. Returns error code if
   * parameters are invalid.
   */

  extern int sock_tx_timestamp(struct sock *sk, __u8 *tx_flags);

  
  /**

   * sk_eat_skb - Release a skb if it is no longer needed

   * @sk: socket to eat this skb from
   * @skb: socket buffer to eat

   * @copied_early: flag indicating whether DMA operations copied this data early

   *
   * This routine must be called with interrupts disabled or with the socket
   * locked so that the sk_buff queue operation is ok.
  */

  #ifdef CONFIG_NET_DMA
  static inline void sk_eat_skb(struct sock *sk, struct sk_buff *skb, int copied_early)
  {
  	__skb_unlink(skb, &sk->sk_receive_queue);
  	if (!copied_early)
  		__kfree_skb(skb);
  	else
  		__skb_queue_tail(&sk->sk_async_wait_queue, skb);
  }
  #else
  static inline void sk_eat_skb(struct sock *sk, struct sk_buff *skb, int copied_early)

  {
  	__skb_unlink(skb, &sk->sk_receive_queue);
  	__kfree_skb(skb);
  }

  #endif

  static inline
  struct net *sock_net(const struct sock *sk)
  {

  	return read_pnet(&sk->sk_net);

  }
  
  static inline

  void sock_net_set(struct sock *sk, struct net *net)

  {

  	write_pnet(&sk->sk_net, net);

  }

  /*
   * Kernel sockets, f.e. rtnl or icmp_socket, are a part of a namespace.

   * They should not hold a reference to a namespace in order to allow

   * to stop it.
   * Sockets after sk_change_net should be released using sk_release_kernel
   */
  static inline void sk_change_net(struct sock *sk, struct net *net)
  {

  	put_net(sock_net(sk));

  	sock_net_set(sk, hold_net(net));

  }

  static inline struct sock *skb_steal_sock(struct sk_buff *skb)
  {
  	if (unlikely(skb->sk)) {
  		struct sock *sk = skb->sk;
  
  		skb->destructor = NULL;
  		skb->sk = NULL;
  		return sk;
  	}
  	return NULL;
  }

  extern void sock_enable_timestamp(struct sock *sk, int flag);

  extern int sock_get_timestamp(struct sock *, struct timeval __user *);

  extern int sock_get_timestampns(struct sock *, struct timespec __user *);

  
  /* 
   *	Enable debug/info messages 
   */

  extern int net_msg_warn;
  #define NETDEBUG(fmt, args...) \
  	do { if (net_msg_warn) printk(fmt,##args); } while (0)

  #define LIMIT_NETDEBUG(fmt, args...) \
  	do { if (net_msg_warn && net_ratelimit()) printk(fmt,##args); } while(0)

  extern __u32 sysctl_wmem_max;
  extern __u32 sysctl_rmem_max;

  extern void sk_init(void);

  extern int sysctl_optmem_max;

  extern __u32 sysctl_wmem_default;
  extern __u32 sysctl_rmem_default;

  #endif	/* _SOCK_H */