/* RxRPC individual remote procedure call handling
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/slab.h>

  #include <linux/module.h>
  #include <linux/circ_buf.h>

  #include <linux/spinlock_types.h>

  #include <net/sock.h>
  #include <net/af_rxrpc.h>
  #include "ar-internal.h"

  const char *const rxrpc_call_states[NR__RXRPC_CALL_STATES] = {

  	[RXRPC_CALL_UNINITIALISED]		= "Uninit  ",

  	[RXRPC_CALL_CLIENT_AWAIT_CONN]		= "ClWtConn",

  	[RXRPC_CALL_CLIENT_SEND_REQUEST]	= "ClSndReq",
  	[RXRPC_CALL_CLIENT_AWAIT_REPLY]		= "ClAwtRpl",
  	[RXRPC_CALL_CLIENT_RECV_REPLY]		= "ClRcvRpl",

  	[RXRPC_CALL_SERVER_PREALLOC]		= "SvPrealc",

  	[RXRPC_CALL_SERVER_SECURING]		= "SvSecure",
  	[RXRPC_CALL_SERVER_ACCEPTING]		= "SvAccept",
  	[RXRPC_CALL_SERVER_RECV_REQUEST]	= "SvRcvReq",
  	[RXRPC_CALL_SERVER_ACK_REQUEST]		= "SvAckReq",
  	[RXRPC_CALL_SERVER_SEND_REPLY]		= "SvSndRpl",
  	[RXRPC_CALL_SERVER_AWAIT_ACK]		= "SvAwtACK",
  	[RXRPC_CALL_COMPLETE]			= "Complete",

  };
  
  const char *const rxrpc_call_completions[NR__RXRPC_CALL_COMPLETIONS] = {
  	[RXRPC_CALL_SUCCEEDED]			= "Complete",

  	[RXRPC_CALL_REMOTELY_ABORTED]		= "RmtAbort",
  	[RXRPC_CALL_LOCALLY_ABORTED]		= "LocAbort",

  	[RXRPC_CALL_LOCAL_ERROR]		= "LocError",

  	[RXRPC_CALL_NETWORK_ERROR]		= "NetError",

  };

  const char rxrpc_call_traces[rxrpc_call__nr_trace][4] = {
  	[rxrpc_call_new_client]		= "NWc",
  	[rxrpc_call_new_service]	= "NWs",
  	[rxrpc_call_queued]		= "QUE",
  	[rxrpc_call_queued_ref]		= "QUR",

  	[rxrpc_call_connected]		= "CON",
  	[rxrpc_call_release]		= "RLS",

  	[rxrpc_call_seen]		= "SEE",
  	[rxrpc_call_got]		= "GOT",

  	[rxrpc_call_got_userid]		= "Gus",

  	[rxrpc_call_got_kernel]		= "Gke",

  	[rxrpc_call_put]		= "PUT",

  	[rxrpc_call_put_userid]		= "Pus",

  	[rxrpc_call_put_kernel]		= "Pke",

  	[rxrpc_call_put_noqueue]	= "PNQ",

  	[rxrpc_call_error]		= "*E*",

  };

  struct kmem_cache *rxrpc_call_jar;
  LIST_HEAD(rxrpc_calls);
  DEFINE_RWLOCK(rxrpc_call_lock);

  static void rxrpc_call_timer_expired(unsigned long _call)
  {
  	struct rxrpc_call *call = (struct rxrpc_call *)_call;
  
  	_enter("%d", call->debug_id);

  	if (call->state < RXRPC_CALL_COMPLETE)
  		rxrpc_set_timer(call, rxrpc_timer_expired, ktime_get_real());

  }

  
  /*

   * find an extant server call
   * - called in process context with IRQs enabled
   */
  struct rxrpc_call *rxrpc_find_call_by_user_ID(struct rxrpc_sock *rx,
  					      unsigned long user_call_ID)
  {
  	struct rxrpc_call *call;
  	struct rb_node *p;
  
  	_enter("%p,%lx", rx, user_call_ID);
  
  	read_lock(&rx->call_lock);
  
  	p = rx->calls.rb_node;
  	while (p) {
  		call = rb_entry(p, struct rxrpc_call, sock_node);
  
  		if (user_call_ID < call->user_call_ID)
  			p = p->rb_left;
  		else if (user_call_ID > call->user_call_ID)
  			p = p->rb_right;
  		else
  			goto found_extant_call;
  	}
  
  	read_unlock(&rx->call_lock);
  	_leave(" = NULL");
  	return NULL;
  
  found_extant_call:

  	rxrpc_get_call(call, rxrpc_call_got);

  	read_unlock(&rx->call_lock);
  	_leave(" = %p [%d]", call, atomic_read(&call->usage));
  	return call;
  }
  
  /*

   * allocate a new call
   */

  struct rxrpc_call *rxrpc_alloc_call(gfp_t gfp)

  {
  	struct rxrpc_call *call;
  
  	call = kmem_cache_zalloc(rxrpc_call_jar, gfp);
  	if (!call)
  		return NULL;

  	call->rxtx_buffer = kcalloc(RXRPC_RXTX_BUFF_SIZE,
  				    sizeof(struct sk_buff *),

  				    gfp);

  	if (!call->rxtx_buffer)
  		goto nomem;

  	call->rxtx_annotations = kcalloc(RXRPC_RXTX_BUFF_SIZE, sizeof(u8), gfp);
  	if (!call->rxtx_annotations)
  		goto nomem_2;
  
  	setup_timer(&call->timer, rxrpc_call_timer_expired,
  		    (unsigned long)call);

  	INIT_WORK(&call->processor, &rxrpc_process_call);

  	INIT_LIST_HEAD(&call->link);

  	INIT_LIST_HEAD(&call->chan_wait_link);

  	INIT_LIST_HEAD(&call->accept_link);

  	INIT_LIST_HEAD(&call->recvmsg_link);
  	INIT_LIST_HEAD(&call->sock_link);

  	init_waitqueue_head(&call->waitq);

  	spin_lock_init(&call->lock);
  	rwlock_init(&call->state_lock);
  	atomic_set(&call->usage, 1);
  	call->debug_id = atomic_inc_return(&rxrpc_debug_id);

  
  	memset(&call->sock_node, 0xed, sizeof(call->sock_node));

  	/* Leave space in the ring to handle a maxed-out jumbo packet */

  	call->rx_winsize = rxrpc_rx_window_size;

  	call->tx_winsize = 16;
  	call->rx_expect_next = 1;

  
  	if (RXRPC_TX_SMSS > 2190)
  		call->cong_cwnd = 2;
  	else if (RXRPC_TX_SMSS > 1095)
  		call->cong_cwnd = 3;
  	else
  		call->cong_cwnd = 4;
  	call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1;

  	return call;

  
  nomem_2:
  	kfree(call->rxtx_buffer);
  nomem:
  	kmem_cache_free(rxrpc_call_jar, call);
  	return NULL;

  }
  
  /*

   * Allocate a new client call.

   */

  static struct rxrpc_call *rxrpc_alloc_client_call(struct sockaddr_rxrpc *srx,

  						  gfp_t gfp)

  {
  	struct rxrpc_call *call;

  	ktime_t now;

  
  	_enter("");

  	call = rxrpc_alloc_call(gfp);
  	if (!call)
  		return ERR_PTR(-ENOMEM);

  	call->state = RXRPC_CALL_CLIENT_AWAIT_CONN;

  	call->service_id = srx->srx_service;

  	call->tx_phase = true;

  	now = ktime_get_real();
  	call->acks_latest_ts = now;
  	call->cong_tstamp = now;

  
  	_leave(" = %p", call);
  	return call;
  }
  
  /*

   * Initiate the call ack/resend/expiry timer.

   */

  static void rxrpc_start_call_timer(struct rxrpc_call *call)

  {

  	ktime_t now = ktime_get_real(), expire_at;

  	expire_at = ktime_add_ms(now, rxrpc_max_call_lifetime);

  	call->expire_at = expire_at;
  	call->ack_at = expire_at;

  	call->ping_at = expire_at;

  	call->resend_at = expire_at;

  	call->timer.expires = jiffies + LONG_MAX / 2;
  	rxrpc_set_timer(call, rxrpc_timer_begin, now);

  }
  
  /*
   * set up a call for the given data
   * - called in process context with IRQs enabled
   */

  struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,

  					 struct rxrpc_conn_parameters *cp,

  					 struct sockaddr_rxrpc *srx,

  					 unsigned long user_call_ID,

  					 gfp_t gfp)
  {

  	struct rxrpc_call *call, *xcall;
  	struct rb_node *parent, **pp;

  	const void *here = __builtin_return_address(0);

  	int ret;

  	_enter("%p,%lx", rx, user_call_ID);

  	call = rxrpc_alloc_client_call(srx, gfp);

  	if (IS_ERR(call)) {
  		_leave(" = %ld", PTR_ERR(call));
  		return call;

  	}

  	trace_rxrpc_call(call, rxrpc_call_new_client, atomic_read(&call->usage),
  			 here, (const void *)user_call_ID);

  	/* Publish the call, even though it is incompletely set up as yet */

  	write_lock(&rx->call_lock);
  
  	pp = &rx->calls.rb_node;
  	parent = NULL;
  	while (*pp) {
  		parent = *pp;

  		xcall = rb_entry(parent, struct rxrpc_call, sock_node);

  		if (user_call_ID < xcall->user_call_ID)

  			pp = &(*pp)->rb_left;

  		else if (user_call_ID > xcall->user_call_ID)

  			pp = &(*pp)->rb_right;
  		else

  			goto error_dup_user_ID;

  	}

  	rcu_assign_pointer(call->socket, rx);

  	call->user_call_ID = user_call_ID;
  	__set_bit(RXRPC_CALL_HAS_USERID, &call->flags);

  	rxrpc_get_call(call, rxrpc_call_got_userid);

  	rb_link_node(&call->sock_node, parent, pp);
  	rb_insert_color(&call->sock_node, &rx->calls);

  	list_add(&call->sock_link, &rx->sock_calls);

  	write_unlock(&rx->call_lock);

  	write_lock(&rxrpc_call_lock);

  	list_add_tail(&call->link, &rxrpc_calls);

  	write_unlock(&rxrpc_call_lock);

  	/* Set up or get a connection record and set the protocol parameters,
  	 * including channel number and call ID.
  	 */
  	ret = rxrpc_connect_call(call, cp, srx, gfp);

  	if (ret < 0)
  		goto error;

  	trace_rxrpc_call(call, rxrpc_call_connected, atomic_read(&call->usage),

  			 here, NULL);

  	spin_lock_bh(&call->conn->params.peer->lock);
  	hlist_add_head(&call->error_link,
  		       &call->conn->params.peer->error_targets);
  	spin_unlock_bh(&call->conn->params.peer->lock);
  
  	rxrpc_start_call_timer(call);

  	_net("CALL new %d on CONN %d", call->debug_id, call->conn->debug_id);
  
  	_leave(" = %p [new]", call);
  	return call;

  	/* We unexpectedly found the user ID in the list after taking
  	 * the call_lock.  This shouldn't happen unless the user races
  	 * with itself and tries to add the same user ID twice at the
  	 * same time in different threads.
  	 */

  error_dup_user_ID:

  	write_unlock(&rx->call_lock);

  	ret = -EEXIST;

  
  error:
  	__rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
  				    RX_CALL_DEAD, ret);

  	trace_rxrpc_call(call, rxrpc_call_error, atomic_read(&call->usage),
  			 here, ERR_PTR(ret));

  	rxrpc_release_call(rx, call);
  	rxrpc_put_call(call, rxrpc_call_put);
  	_leave(" = %d", ret);
  	return ERR_PTR(ret);

  }
  
  /*

   * Set up an incoming call.  call->conn points to the connection.
   * This is called in BH context and isn't allowed to fail.

   */

  void rxrpc_incoming_call(struct rxrpc_sock *rx,
  			 struct rxrpc_call *call,
  			 struct sk_buff *skb)

  {

  	struct rxrpc_connection *conn = call->conn;

  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

  	u32 chan;

  	_enter(",%d", call->conn->debug_id);

  	rcu_assign_pointer(call->socket, rx);
  	call->call_id		= sp->hdr.callNumber;
  	call->service_id	= sp->hdr.serviceId;
  	call->cid		= sp->hdr.cid;
  	call->state		= RXRPC_CALL_SERVER_ACCEPTING;
  	if (sp->hdr.securityIndex > 0)
  		call->state	= RXRPC_CALL_SERVER_SECURING;

  	call->cong_tstamp	= skb->tstamp;

  
  	/* Set the channel for this call.  We don't get channel_lock as we're
  	 * only defending against the data_ready handler (which we're called
  	 * from) and the RESPONSE packet parser (which is only really
  	 * interested in call_counter and can cope with a disagreement with the
  	 * call pointer).

  	 */

  	chan = sp->hdr.cid & RXRPC_CHANNELMASK;
  	conn->channels[chan].call_counter = call->call_id;
  	conn->channels[chan].call_id = call->call_id;

  	rcu_assign_pointer(conn->channels[chan].call, call);

  	spin_lock(&conn->params.peer->lock);
  	hlist_add_head(&call->error_link, &conn->params.peer->error_targets);
  	spin_unlock(&conn->params.peer->lock);

  	_net("CALL incoming %d on CONN %d", call->debug_id, call->conn->debug_id);

  	rxrpc_start_call_timer(call);
  	_leave("");

  }
  
  /*

   * Queue a call's work processor, getting a ref to pass to the work queue.
   */
  bool rxrpc_queue_call(struct rxrpc_call *call)
  {
  	const void *here = __builtin_return_address(0);
  	int n = __atomic_add_unless(&call->usage, 1, 0);

  	if (n == 0)
  		return false;
  	if (rxrpc_queue_work(&call->processor))

  		trace_rxrpc_call(call, rxrpc_call_queued, n + 1, here, NULL);

  	else
  		rxrpc_put_call(call, rxrpc_call_put_noqueue);
  	return true;
  }
  
  /*
   * Queue a call's work processor, passing the callers ref to the work queue.
   */
  bool __rxrpc_queue_call(struct rxrpc_call *call)
  {
  	const void *here = __builtin_return_address(0);
  	int n = atomic_read(&call->usage);

  	ASSERTCMP(n, >=, 1);
  	if (rxrpc_queue_work(&call->processor))

  		trace_rxrpc_call(call, rxrpc_call_queued_ref, n, here, NULL);

  	else
  		rxrpc_put_call(call, rxrpc_call_put_noqueue);
  	return true;
  }
  
  /*

   * Note the re-emergence of a call.
   */
  void rxrpc_see_call(struct rxrpc_call *call)
  {
  	const void *here = __builtin_return_address(0);
  	if (call) {
  		int n = atomic_read(&call->usage);

  		trace_rxrpc_call(call, rxrpc_call_seen, n, here, NULL);

  	}
  }
  
  /*
   * Note the addition of a ref on a call.
   */

  void rxrpc_get_call(struct rxrpc_call *call, enum rxrpc_call_trace op)

  {
  	const void *here = __builtin_return_address(0);
  	int n = atomic_inc_return(&call->usage);

  	trace_rxrpc_call(call, op, n, here, NULL);

  }
  
  /*

   * Detach a call from its owning socket.

   */

  void rxrpc_release_call(struct rxrpc_sock *rx, struct rxrpc_call *call)

  {

  	const void *here = __builtin_return_address(0);

  	struct rxrpc_connection *conn = call->conn;
  	bool put = false;
  	int i;

  	_enter("{%d,%d}", call->debug_id, atomic_read(&call->usage));

  	trace_rxrpc_call(call, rxrpc_call_release, atomic_read(&call->usage),
  			 here, (const void *)call->flags);

  	ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);

  	spin_lock_bh(&call->lock);
  	if (test_and_set_bit(RXRPC_CALL_RELEASED, &call->flags))
  		BUG();
  	spin_unlock_bh(&call->lock);

  	del_timer_sync(&call->timer);

  	/* Make sure we don't get any more notifications */
  	write_lock_bh(&rx->recvmsg_lock);

  	if (!list_empty(&call->recvmsg_link)) {

  		_debug("unlinking once-pending call %p { e=%lx f=%lx }",
  		       call, call->events, call->flags);

  		list_del(&call->recvmsg_link);
  		put = true;
  	}
  
  	/* list_empty() must return false in rxrpc_notify_socket() */
  	call->recvmsg_link.next = NULL;
  	call->recvmsg_link.prev = NULL;
  
  	write_unlock_bh(&rx->recvmsg_lock);
  	if (put)
  		rxrpc_put_call(call, rxrpc_call_put);
  
  	write_lock(&rx->call_lock);
  
  	if (test_and_clear_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {

  		rb_erase(&call->sock_node, &rx->calls);
  		memset(&call->sock_node, 0xdd, sizeof(call->sock_node));

  		rxrpc_put_call(call, rxrpc_call_put_userid);

  	}

  	list_del(&call->sock_link);
  	write_unlock(&rx->call_lock);
  
  	_debug("RELEASE CALL %p (%d CONN %p)", call, call->debug_id, conn);
  
  	if (conn)

  		rxrpc_disconnect_call(call);

  	for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++) {

  		rxrpc_free_skb(call->rxtx_buffer[i],
  			       (call->tx_phase ? rxrpc_skb_tx_cleaned :
  				rxrpc_skb_rx_cleaned));

  		call->rxtx_buffer[i] = NULL;

  	}

  
  	_leave("");
  }
  
  /*

   * release all the calls associated with a socket
   */
  void rxrpc_release_calls_on_socket(struct rxrpc_sock *rx)
  {
  	struct rxrpc_call *call;

  
  	_enter("%p", rx);

  	while (!list_empty(&rx->to_be_accepted)) {
  		call = list_entry(rx->to_be_accepted.next,
  				  struct rxrpc_call, accept_link);
  		list_del(&call->accept_link);
  		rxrpc_abort_call("SKR", call, 0, RX_CALL_DEAD, ECONNRESET);

  		rxrpc_put_call(call, rxrpc_call_put);
  	}

  	while (!list_empty(&rx->sock_calls)) {
  		call = list_entry(rx->sock_calls.next,
  				  struct rxrpc_call, sock_link);
  		rxrpc_get_call(call, rxrpc_call_got);
  		rxrpc_abort_call("SKT", call, 0, RX_CALL_DEAD, ECONNRESET);

  		rxrpc_send_abort_packet(call);

  		rxrpc_release_call(rx, call);

  		rxrpc_put_call(call, rxrpc_call_put);

  	}

  	_leave("");
  }
  
  /*
   * release a call
   */

  void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)

  {

  	const void *here = __builtin_return_address(0);

  	int n;

  	ASSERT(call != NULL);

  	n = atomic_dec_return(&call->usage);

  	trace_rxrpc_call(call, op, n, here, NULL);

  	ASSERTCMP(n, >=, 0);
  	if (n == 0) {
  		_debug("call %d dead", call->debug_id);

  		ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);

  		write_lock(&rxrpc_call_lock);
  		list_del_init(&call->link);
  		write_unlock(&rxrpc_call_lock);

  		rxrpc_cleanup_call(call);

  	}

  }
  
  /*

   * Final call destruction under RCU.
   */
  static void rxrpc_rcu_destroy_call(struct rcu_head *rcu)
  {
  	struct rxrpc_call *call = container_of(rcu, struct rxrpc_call, rcu);

  	rxrpc_put_peer(call->peer);

  	kfree(call->rxtx_buffer);
  	kfree(call->rxtx_annotations);

  	kmem_cache_free(rxrpc_call_jar, call);
  }
  
  /*

   * clean up a call
   */

  void rxrpc_cleanup_call(struct rxrpc_call *call)

  {

  	int i;

  	_net("DESTROY CALL %d", call->debug_id);

  
  	memset(&call->sock_node, 0xcd, sizeof(call->sock_node));

  	del_timer_sync(&call->timer);

  	ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);

  	ASSERT(test_bit(RXRPC_CALL_RELEASED, &call->flags));

  	ASSERTCMP(call->conn, ==, NULL);

  	/* Clean up the Rx/Tx buffer */
  	for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++)

  		rxrpc_free_skb(call->rxtx_buffer[i],
  			       (call->tx_phase ? rxrpc_skb_tx_cleaned :
  				rxrpc_skb_rx_cleaned));

  	rxrpc_free_skb(call->tx_pending, rxrpc_skb_tx_cleaned);

  	call_rcu(&call->rcu, rxrpc_rcu_destroy_call);

  }
  
  /*

   * Make sure that all calls are gone.

   */
  void __exit rxrpc_destroy_all_calls(void)
  {
  	struct rxrpc_call *call;
  
  	_enter("");

  
  	if (list_empty(&rxrpc_calls))
  		return;

  
  	write_lock(&rxrpc_call_lock);

  
  	while (!list_empty(&rxrpc_calls)) {
  		call = list_entry(rxrpc_calls.next, struct rxrpc_call, link);
  		_debug("Zapping call %p", call);

  		rxrpc_see_call(call);

  		list_del_init(&call->link);

  		pr_err("Call %p still in use (%d,%s,%lx,%lx)!
  ",

  		       call, atomic_read(&call->usage),

  		       rxrpc_call_states[call->state],
  		       call->flags, call->events);

  		write_unlock(&rxrpc_call_lock);

  		cond_resched();

  		write_lock(&rxrpc_call_lock);

  	}

  	write_unlock(&rxrpc_call_lock);

  }