/* SPDX-License-Identifier: GPL-2.0 */

  #ifndef _RDS_RDS_H
  #define _RDS_RDS_H
  
  #include <net/sock.h>
  #include <linux/scatterlist.h>
  #include <linux/highmem.h>
  #include <rdma/rdma_cm.h>
  #include <linux/mutex.h>
  #include <linux/rds.h>

  #include <linux/rhashtable.h>

  #include <linux/refcount.h>

  #include <linux/in6.h>

  
  #include "info.h"
  
  /*
   * RDS Network protocol version
   */
  #define RDS_PROTOCOL_3_0	0x0300
  #define RDS_PROTOCOL_3_1	0x0301

  #define RDS_PROTOCOL_4_0	0x0400
  #define RDS_PROTOCOL_4_1	0x0401

  #define RDS_PROTOCOL_VERSION	RDS_PROTOCOL_3_1
  #define RDS_PROTOCOL_MAJOR(v)	((v) >> 8)
  #define RDS_PROTOCOL_MINOR(v)	((v) & 255)
  #define RDS_PROTOCOL(maj, min)	(((maj) << 8) | min)

  #define RDS_PROTOCOL_COMPAT_VERSION	RDS_PROTOCOL_3_1

  /* The following ports, 16385, 18634, 18635, are registered with IANA as
   * the ports to be used for RDS over TCP and UDP.  Currently, only RDS over
   * TCP and RDS over IB/RDMA are implemented.  18634 is the historical value
   * used for the RDMA_CM listener port.  RDS/TCP uses port 16385.  After
   * IPv6 work, RDMA_CM also uses 16385 as the listener port.  18634 is kept
   * to ensure compatibility with older RDS modules.  Those ports are defined
   * in each transport's header file.

   */
  #define RDS_PORT	18634

  #ifdef ATOMIC64_INIT
  #define KERNEL_HAS_ATOMIC64
  #endif

  #ifdef RDS_DEBUG

  #define rdsdebug(fmt, args...) pr_debug("%s(): " fmt, __func__ , ##args)
  #else
  /* sigh, pr_debug() causes unused variable warnings */

  static inline __printf(1, 2)
  void rdsdebug(char *fmt, ...)

  {
  }
  #endif

  #define RDS_FRAG_SHIFT	12
  #define RDS_FRAG_SIZE	((unsigned int)(1 << RDS_FRAG_SHIFT))

  /* Used to limit both RDMA and non-RDMA RDS message to 1MB */
  #define RDS_MAX_MSG_SIZE	((unsigned int)(1 << 20))

  #define RDS_CONG_MAP_BYTES	(65536 / 8)

  #define RDS_CONG_MAP_PAGES	(PAGE_ALIGN(RDS_CONG_MAP_BYTES) / PAGE_SIZE)
  #define RDS_CONG_MAP_PAGE_BITS	(PAGE_SIZE * 8)
  
  struct rds_cong_map {
  	struct rb_node		m_rb_node;

  	struct in6_addr		m_addr;

  	wait_queue_head_t	m_waitq;
  	struct list_head	m_conn_list;
  	unsigned long		m_page_addrs[RDS_CONG_MAP_PAGES];
  };
  
  
  /*
   * This is how we will track the connection state:
   * A connection is always in one of the following
   * states. Updates to the state are atomic and imply
   * a memory barrier.
   */
  enum {
  	RDS_CONN_DOWN = 0,
  	RDS_CONN_CONNECTING,
  	RDS_CONN_DISCONNECTING,
  	RDS_CONN_UP,

  	RDS_CONN_RESETTING,

  	RDS_CONN_ERROR,
  };
  
  /* Bits for c_flags */
  #define RDS_LL_SEND_FULL	0
  #define RDS_RECONNECT_PENDING	1

  #define RDS_IN_XMIT		2

  #define RDS_RECV_REFILL		3

  #define	RDS_DESTROY_PENDING	4

  /* Max number of multipaths per RDS connection. Must be a power of 2 */

  #define	RDS_MPATH_WORKERS	8
  #define	RDS_MPATH_HASH(rs, n) (jhash_1word((rs)->rs_bound_port, \
  			       (rs)->rs_hash_initval) & ((n) - 1))

  #define IS_CANONICAL(laddr, faddr) (htonl(laddr) < htonl(faddr))

  /* Per mpath connection state */
  struct rds_conn_path {
  	struct rds_connection	*cp_conn;
  	struct rds_message	*cp_xmit_rm;
  	unsigned long		cp_xmit_sg;
  	unsigned int		cp_xmit_hdr_off;
  	unsigned int		cp_xmit_data_off;
  	unsigned int		cp_xmit_atomic_sent;
  	unsigned int		cp_xmit_rdma_sent;
  	unsigned int		cp_xmit_data_sent;
  
  	spinlock_t		cp_lock;		/* protect msg queues */
  	u64			cp_next_tx_seq;
  	struct list_head	cp_send_queue;
  	struct list_head	cp_retrans;
  
  	u64			cp_next_rx_seq;
  
  	void			*cp_transport_data;
  
  	atomic_t		cp_state;
  	unsigned long		cp_send_gen;
  	unsigned long		cp_flags;
  	unsigned long		cp_reconnect_jiffies;
  	struct delayed_work	cp_send_w;
  	struct delayed_work	cp_recv_w;
  	struct delayed_work	cp_conn_w;
  	struct work_struct	cp_down_w;
  	struct mutex		cp_cm_lock;	/* protect cp_state & cm */
  	wait_queue_head_t	cp_waitq;
  
  	unsigned int		cp_unacked_packets;
  	unsigned int		cp_unacked_bytes;

  	unsigned int		cp_index;
  };
  
  /* One rds_connection per RDS address pair */

  struct rds_connection {
  	struct hlist_node	c_hash_node;

  	struct in6_addr		c_laddr;
  	struct in6_addr		c_faddr;

  	int			c_dev_if; /* ifindex used for this conn */
  	int			c_bound_if; /* ifindex of c_laddr */

  	unsigned int		c_loopback:1,

  				c_isv6:1,

  				c_ping_triggered:1,

  				c_pad_to_32:29;

  	int			c_npaths;

  	struct rds_connection	*c_passive;

  	struct rds_transport	*c_trans;

  
  	struct rds_cong_map	*c_lcong;
  	struct rds_cong_map	*c_fcong;

  	/* Protocol version */

  	unsigned int		c_proposed_version;

  	unsigned int		c_version;

  	possible_net_t		c_net;

  	/* TOS */
  	u8			c_tos;

  	struct list_head	c_map_item;
  	unsigned long		c_map_queued;

  	struct rds_conn_path	*c_path;

  	wait_queue_head_t	c_hs_waitq; /* handshake waitq */

  
  	u32			c_my_gen_num;
  	u32			c_peer_gen_num;

  };

  static inline
  struct net *rds_conn_net(struct rds_connection *conn)
  {

  	return read_pnet(&conn->c_net);

  }
  
  static inline
  void rds_conn_net_set(struct rds_connection *conn, struct net *net)
  {

  	write_pnet(&conn->c_net, net);

  }

  #define RDS_FLAG_CONG_BITMAP	0x01
  #define RDS_FLAG_ACK_REQUIRED	0x02
  #define RDS_FLAG_RETRANSMITTED	0x04

  #define RDS_MAX_ADV_CREDIT	255

  /* RDS_FLAG_PROBE_PORT is the reserved sport used for sending a ping
   * probe to exchange control information before establishing a connection.
   * Currently the control information that is exchanged is the number of
   * supported paths. If the peer is a legacy (older kernel revision) peer,
   * it would return a pong message without additional control information
   * that would then alert the sender that the peer was an older rev.
   */
  #define RDS_FLAG_PROBE_PORT	1
  #define	RDS_HS_PROBE(sport, dport) \
  		((sport == RDS_FLAG_PROBE_PORT && dport == 0) || \
  		 (sport == 0 && dport == RDS_FLAG_PROBE_PORT))

  /*
   * Maximum space available for extension headers.
   */
  #define RDS_HEADER_EXT_SPACE	16
  
  struct rds_header {
  	__be64	h_sequence;
  	__be64	h_ack;
  	__be32	h_len;
  	__be16	h_sport;
  	__be16	h_dport;
  	u8	h_flags;
  	u8	h_credit;
  	u8	h_padding[4];
  	__sum16	h_csum;
  
  	u8	h_exthdr[RDS_HEADER_EXT_SPACE];
  };
  
  /*
   * Reserved - indicates end of extensions
   */
  #define RDS_EXTHDR_NONE		0
  
  /*
   * This extension header is included in the very
   * first message that is sent on a new connection,
   * and identifies the protocol level. This will help
   * rolling updates if a future change requires breaking
   * the protocol.
   * NB: This is no longer true for IB, where we do a version
   * negotiation during the connection setup phase (protocol
   * version information is included in the RDMA CM private data).
   */
  #define RDS_EXTHDR_VERSION	1
  struct rds_ext_header_version {
  	__be32			h_version;
  };
  
  /*
   * This extension header is included in the RDS message
   * chasing an RDMA operation.
   */
  #define RDS_EXTHDR_RDMA		2
  struct rds_ext_header_rdma {
  	__be32			h_rdma_rkey;
  };
  
  /*
   * This extension header tells the peer about the
   * destination <R_Key,offset> of the requested RDMA
   * operation.
   */
  #define RDS_EXTHDR_RDMA_DEST	3
  struct rds_ext_header_rdma_dest {
  	__be32			h_rdma_rkey;
  	__be32			h_rdma_offset;
  };

  /* Extension header announcing number of paths.
   * Implicit length = 2 bytes.
   */

  #define RDS_EXTHDR_NPATHS	5
  #define RDS_EXTHDR_GEN_NUM	6

  #define __RDS_EXTHDR_MAX	16 /* for now */

  #define RDS_RX_MAX_TRACES	(RDS_MSG_RX_DGRAM_TRACE_MAX + 1)
  #define	RDS_MSG_RX_HDR		0
  #define	RDS_MSG_RX_START	1
  #define	RDS_MSG_RX_END		2
  #define	RDS_MSG_RX_CMSG		3

  /* The following values are whitelisted for usercopy */
  struct rds_inc_usercopy {
  	rds_rdma_cookie_t	rdma_cookie;
  	ktime_t			rx_tstamp;
  };

  struct rds_incoming {

  	refcount_t		i_refcount;

  	struct list_head	i_item;
  	struct rds_connection	*i_conn;

  	struct rds_conn_path	*i_conn_path;

  	struct rds_header	i_hdr;
  	unsigned long		i_rx_jiffies;

  	struct in6_addr		i_saddr;

  	struct rds_inc_usercopy i_usercopy;

  	u64			i_rx_lat_trace[RDS_RX_MAX_TRACES];

  };

  struct rds_mr {
  	struct rb_node		r_rb_node;

  	refcount_t		r_refcount;

  	u32			r_key;
  
  	/* A copy of the creation flags */
  	unsigned int		r_use_once:1;
  	unsigned int		r_invalidate:1;
  	unsigned int		r_write:1;
  
  	/* This is for RDS_MR_DEAD.
  	 * It would be nice & consistent to make this part of the above
  	 * bit field here, but we need to use test_and_set_bit.
  	 */
  	unsigned long		r_state;
  	struct rds_sock		*r_sock; /* back pointer to the socket that owns us */
  	struct rds_transport	*r_trans;
  	void			*r_trans_private;
  };
  
  /* Flags for mr->r_state */
  #define RDS_MR_DEAD		0

  static inline rds_rdma_cookie_t rds_rdma_make_cookie(u32 r_key, u32 offset)
  {
  	return r_key | (((u64) offset) << 32);
  }
  
  static inline u32 rds_rdma_cookie_key(rds_rdma_cookie_t cookie)
  {
  	return cookie;
  }
  
  static inline u32 rds_rdma_cookie_offset(rds_rdma_cookie_t cookie)
  {
  	return cookie >> 32;
  }

  /* atomic operation types */
  #define RDS_ATOMIC_TYPE_CSWP		0
  #define RDS_ATOMIC_TYPE_FADD		1

  /*
   * m_sock_item and m_conn_item are on lists that are serialized under
   * conn->c_lock.  m_sock_item has additional meaning in that once it is empty
   * the message will not be put back on the retransmit list after being sent.
   * messages that are canceled while being sent rely on this.
   *
   * m_inc is used by loopback so that it can pass an incoming message straight
   * back up into the rx path.  It embeds a wire header which is also used by
   * the send path, which is kind of awkward.
   *
   * m_sock_item indicates the message's presence on a socket's send or receive
   * queue.  m_rs will point to that socket.
   *
   * m_daddr is used by cancellation to prune messages to a given destination.
   *
   * The RDS_MSG_ON_SOCK and RDS_MSG_ON_CONN flags are used to avoid lock
   * nesting.  As paths iterate over messages on a sock, or conn, they must
   * also lock the conn, or sock, to remove the message from those lists too.
   * Testing the flag to determine if the message is still on the lists lets
   * us avoid testing the list_head directly.  That means each path can use
   * the message's list_head to keep it on a local list while juggling locks
   * without confusing the other path.
   *
   * m_ack_seq is an optional field set by transports who need a different
   * sequence number range to invalidate.  They can use this in a callback
   * that they pass to rds_send_drop_acked() to see if each message has been
   * acked.  The HAS_ACK_SEQ flag can be used to detect messages which haven't
   * had ack_seq set yet.
   */
  #define RDS_MSG_ON_SOCK		1
  #define RDS_MSG_ON_CONN		2
  #define RDS_MSG_HAS_ACK_SEQ	3
  #define RDS_MSG_ACK_REQUIRED	4
  #define RDS_MSG_RETRANSMITTED	5
  #define RDS_MSG_MAPPED		6
  #define RDS_MSG_PAGEVEC		7

  #define RDS_MSG_FLUSH		8

  struct rds_znotifier {

  	struct mmpin		z_mmp;
  	u32			z_cookie;
  };

  struct rds_msg_zcopy_info {
  	struct list_head rs_zcookie_next;
  	union {
  		struct rds_znotifier znotif;
  		struct rds_zcopy_cookies zcookies;
  	};
  };

  struct rds_msg_zcopy_queue {
  	struct list_head zcookie_head;
  	spinlock_t lock; /* protects zcookie_head queue */
  };
  
  static inline void rds_message_zcopy_queue_init(struct rds_msg_zcopy_queue *q)

  {

  	spin_lock_init(&q->lock);
  	INIT_LIST_HEAD(&q->zcookie_head);

  }

  struct rds_iov_vector {
  	struct rds_iovec *iov;
  	int               len;
  };
  
  struct rds_iov_vector_arr {
  	struct rds_iov_vector *vec;
  	int                    len;
  	int                    indx;
  	int                    incr;
  };

  struct rds_message {

  	refcount_t		m_refcount;

  	struct list_head	m_sock_item;
  	struct list_head	m_conn_item;
  	struct rds_incoming	m_inc;
  	u64			m_ack_seq;

  	struct in6_addr		m_daddr;

  	unsigned long		m_flags;
  
  	/* Never access m_rs without holding m_rs_lock.
  	 * Lock nesting is
  	 *  rm->m_rs_lock
  	 *   -> rs->rs_lock
  	 */
  	spinlock_t		m_rs_lock;

  	wait_queue_head_t	m_flush_wait;

  	struct rds_sock		*m_rs;

  
  	/* cookie to send to remote, in rds header */

  	rds_rdma_cookie_t	m_rdma_cookie;

  
  	unsigned int		m_used_sgs;
  	unsigned int		m_total_sgs;

  	void			*m_final_op;

  	struct {

  		struct rm_atomic_op {
  			int			op_type;

  			union {
  				struct {
  					uint64_t	compare;
  					uint64_t	swap;
  					uint64_t	compare_mask;
  					uint64_t	swap_mask;
  				} op_m_cswp;
  				struct {
  					uint64_t	add;
  					uint64_t	nocarry_mask;
  				} op_m_fadd;
  			};

  
  			u32			op_rkey;
  			u64			op_remote_addr;
  			unsigned int		op_notify:1;
  			unsigned int		op_recverr:1;
  			unsigned int		op_mapped:1;

  			unsigned int		op_silent:1;

  			unsigned int		op_active:1;

  			struct scatterlist	*op_sg;

  			struct rds_notifier	*op_notifier;

  
  			struct rds_mr		*op_rdma_mr;
  		} atomic;
  		struct rm_rdma_op {

  			u32			op_rkey;
  			u64			op_remote_addr;
  			unsigned int		op_write:1;
  			unsigned int		op_fence:1;
  			unsigned int		op_notify:1;
  			unsigned int		op_recverr:1;
  			unsigned int		op_mapped:1;

  			unsigned int		op_silent:1;

  			unsigned int		op_active:1;
  			unsigned int		op_bytes;
  			unsigned int		op_nents;
  			unsigned int		op_count;
  			struct scatterlist	*op_sg;
  			struct rds_notifier	*op_notifier;
  
  			struct rds_mr		*op_rdma_mr;

  		} rdma;

  		struct rm_data_op {

  			unsigned int		op_active:1;

  			unsigned int		op_nents;
  			unsigned int		op_count;

  			unsigned int		op_dmasg;
  			unsigned int		op_dmaoff;

  			struct rds_znotifier	*op_mmp_znotifier;

  			struct scatterlist	*op_sg;

  		} data;
  	};

  
  	struct rds_conn_path *m_conn_path;

  };
  
  /*
   * The RDS notifier is used (optionally) to tell the application about
   * completed RDMA operations. Rather than keeping the whole rds message
   * around on the queue, we allocate a small notifier that is put on the
   * socket's notifier_list. Notifications are delivered to the application
   * through control messages.
   */
  struct rds_notifier {
  	struct list_head	n_list;
  	uint64_t		n_user_token;
  	int			n_status;
  };

  /* Available as part of RDS core, so doesn't need to participate
   * in get_preferred transport etc
   */
  #define	RDS_TRANS_LOOP	3

  /**
   * struct rds_transport -  transport specific behavioural hooks
   *
   * @xmit: .xmit is called by rds_send_xmit() to tell the transport to send
   *        part of a message.  The caller serializes on the send_sem so this
   *        doesn't need to be reentrant for a given conn.  The header must be
   *        sent before the data payload.  .xmit must be prepared to send a
   *        message with no data payload.  .xmit should return the number of
   *        bytes that were sent down the connection, including header bytes.
   *        Returning 0 tells the caller that it doesn't need to perform any
   *        additional work now.  This is usually the case when the transport has
   *        filled the sending queue for its connection and will handle
   *        triggering the rds thread to continue the send when space becomes
   *        available.  Returning -EAGAIN tells the caller to retry the send
   *        immediately.  Returning -ENOMEM tells the caller to retry the send at
   *        some point in the future.
   *
   * @conn_shutdown: conn_shutdown stops traffic on the given connection.  Once
   *                 it returns the connection can not call rds_recv_incoming().
   *                 This will only be called once after conn_connect returns
   *                 non-zero success and will The caller serializes this with
   *                 the send and connecting paths (xmit_* and conn_*).  The
   *                 transport is responsible for other serialization, including
   *                 rds_recv_incoming().  This is called in process context but
   *                 should try hard not to block.

   */
  
  struct rds_transport {
  	char			t_name[TRANSNAMSIZ];
  	struct list_head	t_item;
  	struct module		*t_owner;

  	unsigned int		t_prefer_loopback:1,
  				t_mp_capable:1;

  	unsigned int		t_type;

  	int (*laddr_check)(struct net *net, const struct in6_addr *addr,
  			   __u32 scope_id);

  	int (*conn_alloc)(struct rds_connection *conn, gfp_t gfp);
  	void (*conn_free)(void *data);

  	int (*conn_path_connect)(struct rds_conn_path *cp);

  	void (*conn_path_shutdown)(struct rds_conn_path *conn);

  	void (*xmit_path_prepare)(struct rds_conn_path *cp);

  	void (*xmit_path_complete)(struct rds_conn_path *cp);

  	int (*xmit)(struct rds_connection *conn, struct rds_message *rm,
  		    unsigned int hdr_off, unsigned int sg, unsigned int off);

  	int (*xmit_rdma)(struct rds_connection *conn, struct rm_rdma_op *op);

  	int (*xmit_atomic)(struct rds_connection *conn, struct rm_atomic_op *op);

  	int (*recv_path)(struct rds_conn_path *cp);

  	int (*inc_copy_to_user)(struct rds_incoming *inc, struct iov_iter *to);

  	void (*inc_free)(struct rds_incoming *inc);
  
  	int (*cm_handle_connect)(struct rdma_cm_id *cm_id,

  				 struct rdma_cm_event *event, bool isv6);
  	int (*cm_initiate_connect)(struct rdma_cm_id *cm_id, bool isv6);

  	void (*cm_connect_complete)(struct rds_connection *conn,
  				    struct rdma_cm_event *event);
  
  	unsigned int (*stats_info_copy)(struct rds_info_iterator *iter,
  					unsigned int avail);
  	void (*exit)(void);
  	void *(*get_mr)(struct scatterlist *sg, unsigned long nr_sg,

  			struct rds_sock *rs, u32 *key_ret,
  			struct rds_connection *conn);

  	void (*sync_mr)(void *trans_private, int direction);
  	void (*free_mr)(void *trans_private, int invalidate);
  	void (*flush_mrs)(void);

  	bool (*t_unloading)(struct rds_connection *conn);

  	u8 (*get_tos_map)(u8 tos);

  };

  /* Bind hash table key length.  It is the sum of the size of a struct
   * in6_addr, a scope_id  and a port.
   */
  #define RDS_BOUND_KEY_LEN \
  	(sizeof(struct in6_addr) + sizeof(__u32) + sizeof(__be16))

  struct rds_sock {
  	struct sock		rs_sk;
  
  	u64			rs_user_addr;
  	u64			rs_user_bytes;
  
  	/*
  	 * bound_addr used for both incoming and outgoing, no INADDR_ANY
  	 * support.
  	 */

  	struct rhash_head	rs_bound_node;

  	u8			rs_bound_key[RDS_BOUND_KEY_LEN];
  	struct sockaddr_in6	rs_bound_sin6;
  #define rs_bound_addr		rs_bound_sin6.sin6_addr
  #define rs_bound_addr_v4	rs_bound_sin6.sin6_addr.s6_addr32[3]
  #define rs_bound_port		rs_bound_sin6.sin6_port
  #define rs_bound_scope_id	rs_bound_sin6.sin6_scope_id
  	struct in6_addr		rs_conn_addr;
  #define rs_conn_addr_v4		rs_conn_addr.s6_addr32[3]

  	__be16			rs_conn_port;

  	struct rds_transport    *rs_transport;
  
  	/*
  	 * rds_sendmsg caches the conn it used the last time around.
  	 * This helps avoid costly lookups.
  	 */
  	struct rds_connection	*rs_conn;
  
  	/* flag indicating we were congested or not */
  	int			rs_congested;

  	/* seen congestion (ENOBUFS) when sending? */
  	int			rs_seen_congestion;

  
  	/* rs_lock protects all these adjacent members before the newline */
  	spinlock_t		rs_lock;
  	struct list_head	rs_send_queue;
  	u32			rs_snd_bytes;
  	int			rs_rcv_bytes;
  	struct list_head	rs_notify_queue;	/* currently used for failed RDMAs */
  
  	/* Congestion wake_up. If rs_cong_monitor is set, we use cong_mask
  	 * to decide whether the application should be woken up.
  	 * If not set, we use rs_cong_track to find out whether a cong map
  	 * update arrived.
  	 */
  	uint64_t		rs_cong_mask;
  	uint64_t		rs_cong_notify;
  	struct list_head	rs_cong_list;
  	unsigned long		rs_cong_track;
  
  	/*
  	 * rs_recv_lock protects the receive queue, and is
  	 * used to serialize with rds_release.
  	 */
  	rwlock_t		rs_recv_lock;
  	struct list_head	rs_recv_queue;
  
  	/* just for stats reporting */
  	struct list_head	rs_item;
  
  	/* these have their own lock */
  	spinlock_t		rs_rdma_lock;
  	struct rb_root		rs_rdma_keys;
  
  	/* Socket options - in case there will be more */
  	unsigned char		rs_recverr,
  				rs_cong_monitor;

  	u32			rs_hash_initval;

  
  	/* Socket receive path trace points*/
  	u8			rs_rx_traces;
  	u8			rs_rx_trace[RDS_MSG_RX_DGRAM_TRACE_MAX];

  	struct rds_msg_zcopy_queue rs_zcookie_queue;

  	u8			rs_tos;

  };
  
  static inline struct rds_sock *rds_sk_to_rs(const struct sock *sk)
  {
  	return container_of(sk, struct rds_sock, rs_sk);
  }
  static inline struct sock *rds_rs_to_sk(struct rds_sock *rs)
  {
  	return &rs->rs_sk;
  }
  
  /*
   * The stack assigns sk_sndbuf and sk_rcvbuf to twice the specified value
   * to account for overhead.  We don't account for overhead, we just apply
   * the number of payload bytes to the specified value.
   */
  static inline int rds_sk_sndbuf(struct rds_sock *rs)
  {
  	return rds_rs_to_sk(rs)->sk_sndbuf / 2;
  }
  static inline int rds_sk_rcvbuf(struct rds_sock *rs)
  {
  	return rds_rs_to_sk(rs)->sk_rcvbuf / 2;
  }
  
  struct rds_statistics {
  	uint64_t	s_conn_reset;
  	uint64_t	s_recv_drop_bad_checksum;
  	uint64_t	s_recv_drop_old_seq;
  	uint64_t	s_recv_drop_no_sock;
  	uint64_t	s_recv_drop_dead_sock;
  	uint64_t	s_recv_deliver_raced;
  	uint64_t	s_recv_delivered;
  	uint64_t	s_recv_queued;
  	uint64_t	s_recv_immediate_retry;
  	uint64_t	s_recv_delayed_retry;
  	uint64_t	s_recv_ack_required;
  	uint64_t	s_recv_rdma_bytes;
  	uint64_t	s_recv_ping;
  	uint64_t	s_send_queue_empty;
  	uint64_t	s_send_queue_full;

  	uint64_t	s_send_lock_contention;
  	uint64_t	s_send_lock_queue_raced;

  	uint64_t	s_send_immediate_retry;
  	uint64_t	s_send_delayed_retry;
  	uint64_t	s_send_drop_acked;
  	uint64_t	s_send_ack_required;
  	uint64_t	s_send_queued;
  	uint64_t	s_send_rdma;
  	uint64_t	s_send_rdma_bytes;
  	uint64_t	s_send_pong;
  	uint64_t	s_page_remainder_hit;
  	uint64_t	s_page_remainder_miss;
  	uint64_t	s_copy_to_user;
  	uint64_t	s_copy_from_user;
  	uint64_t	s_cong_update_queued;
  	uint64_t	s_cong_update_received;
  	uint64_t	s_cong_send_error;
  	uint64_t	s_cong_send_blocked;

  	uint64_t	s_recv_bytes_added_to_socket;
  	uint64_t	s_recv_bytes_removed_from_socket;

  	uint64_t	s_send_stuck_rm;

  };
  
  /* af_rds.c */
  void rds_sock_addref(struct rds_sock *rs);
  void rds_sock_put(struct rds_sock *rs);
  void rds_wake_sk_sleep(struct rds_sock *rs);
  static inline void __rds_wake_sk_sleep(struct sock *sk)
  {

  	wait_queue_head_t *waitq = sk_sleep(sk);

  
  	if (!sock_flag(sk, SOCK_DEAD) && waitq)
  		wake_up(waitq);
  }
  extern wait_queue_head_t rds_poll_waitq;
  
  
  /* bind.c */
  int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len);
  void rds_remove_bound(struct rds_sock *rs);

  struct rds_sock *rds_find_bound(const struct in6_addr *addr, __be16 port,
  				__u32 scope_id);

  int rds_bind_lock_init(void);
  void rds_bind_lock_destroy(void);

  
  /* cong.c */
  int rds_cong_get_maps(struct rds_connection *conn);
  void rds_cong_add_conn(struct rds_connection *conn);
  void rds_cong_remove_conn(struct rds_connection *conn);
  void rds_cong_set_bit(struct rds_cong_map *map, __be16 port);
  void rds_cong_clear_bit(struct rds_cong_map *map, __be16 port);
  int rds_cong_wait(struct rds_cong_map *map, __be16 port, int nonblock, struct rds_sock *rs);
  void rds_cong_queue_updates(struct rds_cong_map *map);
  void rds_cong_map_updated(struct rds_cong_map *map, uint64_t);
  int rds_cong_updated_since(unsigned long *recent);
  void rds_cong_add_socket(struct rds_sock *);
  void rds_cong_remove_socket(struct rds_sock *);
  void rds_cong_exit(void);
  struct rds_message *rds_cong_update_alloc(struct rds_connection *conn);

  /* connection.c */

  extern u32 rds_gen_num;

  int rds_conn_init(void);

  void rds_conn_exit(void);

  struct rds_connection *rds_conn_create(struct net *net,

  				       const struct in6_addr *laddr,
  				       const struct in6_addr *faddr,

  				       struct rds_transport *trans,
  				       u8 tos, gfp_t gfp,

  				       int dev_if);

  struct rds_connection *rds_conn_create_outgoing(struct net *net,

  						const struct in6_addr *laddr,
  						const struct in6_addr *faddr,
  						struct rds_transport *trans,

  						u8 tos, gfp_t gfp, int dev_if);

  void rds_conn_shutdown(struct rds_conn_path *cpath);

  void rds_conn_destroy(struct rds_connection *conn);

  void rds_conn_drop(struct rds_connection *conn);

  void rds_conn_path_drop(struct rds_conn_path *cpath, bool destroy);

  void rds_conn_connect_if_down(struct rds_connection *conn);

  void rds_conn_path_connect_if_down(struct rds_conn_path *cp);

  void rds_for_each_conn_info(struct socket *sock, unsigned int len,
  			  struct rds_info_iterator *iter,
  			  struct rds_info_lengths *lens,
  			  int (*visitor)(struct rds_connection *, void *),

  			  u64 *buffer,

  			  size_t item_len);

  __printf(2, 3)

  void __rds_conn_path_error(struct rds_conn_path *cp, const char *, ...);
  #define rds_conn_path_error(cp, fmt...) \
  	__rds_conn_path_error(cp, KERN_WARNING "RDS: " fmt)

  static inline int

  rds_conn_path_transition(struct rds_conn_path *cp, int old, int new)
  {
  	return atomic_cmpxchg(&cp->cp_state, old, new) == old;
  }
  
  static inline int

  rds_conn_transition(struct rds_connection *conn, int old, int new)
  {

  	WARN_ON(conn->c_trans->t_mp_capable);

  	return rds_conn_path_transition(&conn->c_path[0], old, new);
  }
  
  static inline int
  rds_conn_path_state(struct rds_conn_path *cp)
  {
  	return atomic_read(&cp->cp_state);

  }
  
  static inline int
  rds_conn_state(struct rds_connection *conn)
  {

  	WARN_ON(conn->c_trans->t_mp_capable);

  	return rds_conn_path_state(&conn->c_path[0]);
  }
  
  static inline int
  rds_conn_path_up(struct rds_conn_path *cp)
  {
  	return atomic_read(&cp->cp_state) == RDS_CONN_UP;

  }
  
  static inline int
  rds_conn_up(struct rds_connection *conn)
  {

  	WARN_ON(conn->c_trans->t_mp_capable);

  	return rds_conn_path_up(&conn->c_path[0]);
  }
  
  static inline int
  rds_conn_path_connecting(struct rds_conn_path *cp)
  {
  	return atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING;

  }
  
  static inline int
  rds_conn_connecting(struct rds_connection *conn)
  {

  	WARN_ON(conn->c_trans->t_mp_capable);

  	return rds_conn_path_connecting(&conn->c_path[0]);

  }
  
  /* message.c */
  struct rds_message *rds_message_alloc(unsigned int nents, gfp_t gfp);

  struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents,
  					  int *ret);

  int rds_message_copy_from_user(struct rds_message *rm, struct iov_iter *from,
  			       bool zcopy);

  struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned int total_len);
  void rds_message_populate_header(struct rds_header *hdr, __be16 sport,
  				 __be16 dport, u64 seq);
  int rds_message_add_extension(struct rds_header *hdr,
  			      unsigned int type, const void *data, unsigned int len);
  int rds_message_next_extension(struct rds_header *hdr,
  			       unsigned int *pos, void *buf, unsigned int *buflen);

  int rds_message_add_rdma_dest_extension(struct rds_header *hdr, u32 r_key, u32 offset);

  int rds_message_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to);

  void rds_message_inc_free(struct rds_incoming *inc);
  void rds_message_addref(struct rds_message *rm);
  void rds_message_put(struct rds_message *rm);
  void rds_message_wait(struct rds_message *rm);
  void rds_message_unmapped(struct rds_message *rm);

  void rds_notify_msg_zcopy_purge(struct rds_msg_zcopy_queue *info);

  
  static inline void rds_message_make_checksum(struct rds_header *hdr)
  {
  	hdr->h_csum = 0;
  	hdr->h_csum = ip_fast_csum((void *) hdr, sizeof(*hdr) >> 2);
  }
  
  static inline int rds_message_verify_checksum(const struct rds_header *hdr)
  {
  	return !hdr->h_csum || ip_fast_csum((void *) hdr, sizeof(*hdr) >> 2) == 0;
  }
  
  
  /* page.c */
  int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
  			     gfp_t gfp);

  void rds_page_exit(void);
  
  /* recv.c */
  void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,

  		  struct in6_addr *saddr);

  void rds_inc_path_init(struct rds_incoming *inc, struct rds_conn_path *conn,

  		       struct in6_addr *saddr);

  void rds_inc_put(struct rds_incoming *inc);

  void rds_recv_incoming(struct rds_connection *conn, struct in6_addr *saddr,
  		       struct in6_addr *daddr,

  		       struct rds_incoming *inc, gfp_t gfp);

  int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
  		int msg_flags);

  void rds_clear_recv_queue(struct rds_sock *rs);
  int rds_notify_queue_get(struct rds_sock *rs, struct msghdr *msg);
  void rds_inc_info_copy(struct rds_incoming *inc,
  		       struct rds_info_iterator *iter,
  		       __be32 saddr, __be32 daddr, int flip);

  void rds6_inc_info_copy(struct rds_incoming *inc,
  			struct rds_info_iterator *iter,
  			struct in6_addr *saddr, struct in6_addr *daddr,
  			int flip);

  
  /* send.c */

  int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len);

  void rds_send_path_reset(struct rds_conn_path *conn);

  int rds_send_xmit(struct rds_conn_path *cp);

  struct sockaddr_in;

  void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in6 *dest);

  typedef int (*is_acked_func)(struct rds_message *rm, uint64_t ack);
  void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
  			 is_acked_func is_acked);

  void rds_send_path_drop_acked(struct rds_conn_path *cp, u64 ack,
  			      is_acked_func is_acked);

  void rds_send_ping(struct rds_connection *conn, int cp_index);

  int rds_send_pong(struct rds_conn_path *cp, __be16 dport);

  
  /* rdma.c */
  void rds_rdma_unuse(struct rds_sock *rs, u32 r_key, int force);

  int rds_get_mr(struct rds_sock *rs, char __user *optval, int optlen);
  int rds_get_mr_for_dest(struct rds_sock *rs, char __user *optval, int optlen);
  int rds_free_mr(struct rds_sock *rs, char __user *optval, int optlen);
  void rds_rdma_drop_keys(struct rds_sock *rs);

  int rds_rdma_extra_size(struct rds_rdma_args *args,
  			struct rds_iov_vector *iov);

  int rds_cmsg_rdma_dest(struct rds_sock *rs, struct rds_message *rm,
  			  struct cmsghdr *cmsg);
  int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,

  			  struct cmsghdr *cmsg,
  			  struct rds_iov_vector *vec);

  int rds_cmsg_rdma_map(struct rds_sock *rs, struct rds_message *rm,
  			  struct cmsghdr *cmsg);

  void rds_rdma_free_op(struct rm_rdma_op *ro);

  void rds_atomic_free_op(struct rm_atomic_op *ao);

  void rds_rdma_send_complete(struct rds_message *rm, int wc_status);
  void rds_atomic_send_complete(struct rds_message *rm, int wc_status);
  int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
  		    struct cmsghdr *cmsg);

  void __rds_put_mr_final(struct rds_mr *mr);

  static inline void rds_mr_put(struct rds_mr *mr)
  {

  	if (refcount_dec_and_test(&mr->r_refcount))

  		__rds_put_mr_final(mr);
  }

  static inline bool rds_destroy_pending(struct rds_connection *conn)
  {
  	return !check_net(rds_conn_net(conn)) ||
  	       (conn->c_trans->t_unloading && conn->c_trans->t_unloading(conn));
  }

  /* stats.c */

  DECLARE_PER_CPU_SHARED_ALIGNED(struct rds_statistics, rds_stats);

  #define rds_stats_inc_which(which, member) do {		\
  	per_cpu(which, get_cpu()).member++;		\
  	put_cpu();					\
  } while (0)
  #define rds_stats_inc(member) rds_stats_inc_which(rds_stats, member)
  #define rds_stats_add_which(which, member, count) do {		\
  	per_cpu(which, get_cpu()).member += count;	\
  	put_cpu();					\
  } while (0)
  #define rds_stats_add(member, count) rds_stats_add_which(rds_stats, member, count)

  int rds_stats_init(void);

  void rds_stats_exit(void);
  void rds_stats_info_copy(struct rds_info_iterator *iter,

  			 uint64_t *values, const char *const *names,
  			 size_t nr);

  
  /* sysctl.c */

  int rds_sysctl_init(void);

  void rds_sysctl_exit(void);
  extern unsigned long rds_sysctl_sndbuf_min;
  extern unsigned long rds_sysctl_sndbuf_default;
  extern unsigned long rds_sysctl_sndbuf_max;
  extern unsigned long rds_sysctl_reconnect_min_jiffies;
  extern unsigned long rds_sysctl_reconnect_max_jiffies;
  extern unsigned int  rds_sysctl_max_unacked_packets;
  extern unsigned int  rds_sysctl_max_unacked_bytes;
  extern unsigned int  rds_sysctl_ping_enable;
  extern unsigned long rds_sysctl_trace_flags;
  extern unsigned int  rds_sysctl_trace_level;
  
  /* threads.c */

  int rds_threads_init(void);

  void rds_threads_exit(void);
  extern struct workqueue_struct *rds_wq;

  void rds_queue_reconnect(struct rds_conn_path *cp);

  void rds_connect_worker(struct work_struct *);
  void rds_shutdown_worker(struct work_struct *);
  void rds_send_worker(struct work_struct *);
  void rds_recv_worker(struct work_struct *);

  void rds_connect_path_complete(struct rds_conn_path *conn, int curr);

  void rds_connect_complete(struct rds_connection *conn);

  int rds_addr_cmp(const struct in6_addr *a1, const struct in6_addr *a2);

  
  /* transport.c */

  void rds_trans_register(struct rds_transport *trans);

  void rds_trans_unregister(struct rds_transport *trans);

  struct rds_transport *rds_trans_get_preferred(struct net *net,
  					      const struct in6_addr *addr,
  					      __u32 scope_id);

  void rds_trans_put(struct rds_transport *trans);

  unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
  				       unsigned int avail);

  struct rds_transport *rds_trans_get(int t_type);

  int rds_trans_init(void);

  void rds_trans_exit(void);
  
  #endif