/*
 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * This file contains code imported from the OFED rds source file connection.c
 * Oracle elects to have and use the contents of connection.c under and governed
 * by the OpenIB.org BSD license (see below for full license text). However,
 * the following notice accompanied the original version of this file:
 */

/*
 * Copyright (c) 2006 Oracle.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
#include <sys/types.h>
#include <sys/kmem.h>
#include <sys/rds.h>

#include <sys/ib/clients/rdsv3/rdsv3.h>
#include <sys/ib/clients/rdsv3/loop.h>
#include <sys/ib/clients/rdsv3/rdsv3_debug.h>

/* converting this to RCU is a chore for another day.. */
static krwlock_t rdsv3_conn_lock;
struct avl_tree rdsv3_conn_hash;
static struct kmem_cache *rdsv3_conn_slab = NULL;

#define rdsv3_conn_info_set(var, test, suffix) do {               \
        if (test)                                               \
                var |= RDS_INFO_CONNECTION_FLAG_##suffix;     \
} while (0)


static struct rdsv3_connection *
rdsv3_conn_lookup(uint32_be_t laddr, uint32_be_t faddr, avl_index_t *pos)
{
        struct rdsv3_connection *conn;
        struct rdsv3_conn_info_s conn_info;
        avl_index_t place = 0;

        conn_info.c_laddr = laddr;
        conn_info.c_faddr = faddr;

        conn = avl_find(&rdsv3_conn_hash, &conn_info, &place);

        RDSV3_DPRINTF5("rdsv3_conn_lookup",
            "returning conn %p for %u.%u.%u.%u -> %u.%u.%u.%u",
            conn, NIPQUAD(laddr), NIPQUAD(faddr));

        if (pos != NULL)
                *pos = place;

        return (conn);
}

/*
 * This is called by transports as they're bringing down a connection.
 * It clears partial message state so that the transport can start sending
 * and receiving over this connection again in the future.  It is up to
 * the transport to have serialized this call with its send and recv.
 */
void
rdsv3_conn_reset(struct rdsv3_connection *conn)
{
        RDSV3_DPRINTF2("rdsv3_conn_reset",
            "connection %u.%u.%u.%u to %u.%u.%u.%u reset",
            NIPQUAD(conn->c_laddr), NIPQUAD(conn->c_faddr));

        rdsv3_stats_inc(s_conn_reset);
        rdsv3_send_reset(conn);
        conn->c_flags = 0;

        /*
         * Do not clear next_rx_seq here, else we cannot distinguish
         * retransmitted packets from new packets, and will hand all
         * of them to the application. That is not consistent with the
         * reliability guarantees of RDS.
         */
}

/*
 * There is only every one 'conn' for a given pair of addresses in the
 * system at a time.  They contain messages to be retransmitted and so
 * span the lifetime of the actual underlying transport connections.
 *
 * For now they are not garbage collected once they're created.  They
 * are torn down as the module is removed, if ever.
 */
static struct rdsv3_connection *
__rdsv3_conn_create(uint32_be_t laddr, uint32_be_t faddr,
    struct rdsv3_transport *trans, int gfp, int is_outgoing)
{
        struct rdsv3_connection *conn, *parent = NULL;
        avl_index_t pos;
        int ret;

        rw_enter(&rdsv3_conn_lock, RW_READER);
        conn = rdsv3_conn_lookup(laddr, faddr, &pos);
        if (conn &&
            conn->c_loopback &&
            conn->c_trans != &rdsv3_loop_transport &&
            !is_outgoing) {
                /*
                 * This is a looped back IB connection, and we're
                 * called by the code handling the incoming connect.
                 * We need a second connection object into which we
                 * can stick the other QP.
                 */
                parent = conn;
                conn = parent->c_passive;
        }
        rw_exit(&rdsv3_conn_lock);
        if (conn)
                goto out;

        RDSV3_DPRINTF2("__rdsv3_conn_create", "Enter(%x -> %x)",
            ntohl(laddr), ntohl(faddr));

        conn = kmem_cache_alloc(rdsv3_conn_slab, gfp);
        if (!conn) {
                conn = ERR_PTR(-ENOMEM);
                goto out;
        }

        /* see rdsv3_conn_constructor */
        conn->c_laddr = laddr;
        conn->c_faddr = faddr;

        /*
         * We don't allow sockets to send messages without binding.
         * So, the IP address will already be there in the bind array.
         * Mostly, this is a readonly operation.
         * For now, passing GLOBAL_ZONEID.
         */
        conn->c_bucketp = rdsv3_find_ip_bucket(ntohl(laddr), GLOBAL_ZONEID);

        ret = rdsv3_cong_get_maps(conn);
        if (ret) {
                kmem_cache_free(rdsv3_conn_slab, conn);
                conn = ERR_PTR(ret);
                goto out;
        }

        /*
         * This is where a connection becomes loopback.  If *any* RDS sockets
         * can bind to the destination address then we'd rather the messages
         * flow through loopback rather than either transport.
         */
        if (rdsv3_trans_get_preferred(faddr)) {
                conn->c_loopback = 1;
                if (is_outgoing && trans->t_prefer_loopback) {
                        /*
                         * "outgoing" connection - and the transport
                         * says it wants the connection handled by the
                         * loopback transport. This is what TCP does.
                         */
                        trans = &rdsv3_loop_transport;
                }
        }

        conn->c_trans = trans;

        ret = trans->conn_alloc(conn, gfp);
        if (ret) {
                kmem_cache_free(rdsv3_conn_slab, conn);
                conn = ERR_PTR(ret);
                goto out;
        }

        conn->c_state = RDSV3_CONN_DOWN;
        conn->c_reconnect_jiffies = 0;
        RDSV3_INIT_DELAYED_WORK(&conn->c_send_w, rdsv3_send_worker);
        RDSV3_INIT_DELAYED_WORK(&conn->c_recv_w, rdsv3_recv_worker);
        RDSV3_INIT_DELAYED_WORK(&conn->c_conn_w, rdsv3_connect_worker);
        RDSV3_INIT_DELAYED_WORK(&conn->c_reap_w, rdsv3_reaper_worker);
        RDSV3_INIT_WORK(&conn->c_down_w, rdsv3_shutdown_worker);
        mutex_init(&conn->c_cm_lock, NULL, MUTEX_DRIVER, NULL);
        conn->c_flags = 0;

        RDSV3_DPRINTF2("__rdsv3_conn_create",
            "allocated conn %p for %u.%u.%u.%u -> %u.%u.%u.%u over %s %s",
            conn, NIPQUAD(laddr), NIPQUAD(faddr),
            *trans->t_name != '\0' ? trans->t_name : "[unknown]",
            is_outgoing ? "(outgoing)" : "");

        /*
         * Since we ran without holding the conn lock, someone could
         * have created the same conn (either normal or passive) in the
         * interim. We check while holding the lock. If we won, we complete
         * init and return our conn. If we lost, we rollback and return the
         * other one.
         */
        rw_enter(&rdsv3_conn_lock, RW_WRITER);
        if (parent) {
                /* Creating passive conn */
                if (parent->c_passive) {
                        trans->conn_free(conn->c_transport_data);
                        kmem_cache_free(rdsv3_conn_slab, conn);
                        conn = parent->c_passive;
                } else {
                        parent->c_passive = conn;
                        rdsv3_cong_add_conn(conn);
                }
        } else {
                /* Creating normal conn */
                struct rdsv3_connection *found;

                found = rdsv3_conn_lookup(laddr, faddr, &pos);
                if (found) {
                        trans->conn_free(conn->c_transport_data);
                        kmem_cache_free(rdsv3_conn_slab, conn);
                        conn = found;
                } else {
                        avl_insert(&rdsv3_conn_hash, conn, pos);
                        rdsv3_cong_add_conn(conn);
                        rdsv3_queue_delayed_work(rdsv3_wq, &conn->c_reap_w,
                            RDSV3_REAPER_WAIT_JIFFIES);
                }
        }

        rw_exit(&rdsv3_conn_lock);

        RDSV3_DPRINTF2("__rdsv3_conn_create", "Return(conn: %p)", conn);

out:
        return (conn);
}

struct rdsv3_connection *
rdsv3_conn_create(uint32_be_t laddr, uint32_be_t faddr,
    struct rdsv3_transport *trans, int gfp)
{
        return (__rdsv3_conn_create(laddr, faddr, trans, gfp, 0));
}

struct rdsv3_connection *
rdsv3_conn_create_outgoing(uint32_be_t laddr, uint32_be_t faddr,
    struct rdsv3_transport *trans, int gfp)
{
        return (__rdsv3_conn_create(laddr, faddr, trans, gfp, 1));
}

extern struct avl_tree  rdsv3_conn_hash;

void
rdsv3_conn_shutdown(struct rdsv3_connection *conn)
{
        RDSV3_DPRINTF2("rdsv3_conn_shutdown", "Enter(conn: %p)", conn);

        /* shut it down unless it's down already */
        if (!rdsv3_conn_transition(conn, RDSV3_CONN_DOWN, RDSV3_CONN_DOWN)) {
                /*
                 * Quiesce the connection mgmt handlers before we start tearing
                 * things down. We don't hold the mutex for the entire
                 * duration of the shutdown operation, else we may be
                 * deadlocking with the CM handler. Instead, the CM event
                 * handler is supposed to check for state DISCONNECTING
                 */
                mutex_enter(&conn->c_cm_lock);
                if (!rdsv3_conn_transition(conn, RDSV3_CONN_UP,
                    RDSV3_CONN_DISCONNECTING) &&
                    !rdsv3_conn_transition(conn, RDSV3_CONN_ERROR,
                    RDSV3_CONN_DISCONNECTING)) {
                        RDSV3_DPRINTF2("rdsv3_conn_shutdown",
                            "shutdown called in state %d",
                            atomic_get(&conn->c_state));
                        rdsv3_conn_drop(conn);
                        mutex_exit(&conn->c_cm_lock);
                        return;
                }
                mutex_exit(&conn->c_cm_lock);

                /* verify everybody's out of rds_send_xmit() */
                mutex_enter(&conn->c_send_lock);
                while (atomic_get(&conn->c_senders)) {
                        mutex_exit(&conn->c_send_lock);
                        delay(1);
                        mutex_enter(&conn->c_send_lock);
                }

                conn->c_trans->conn_shutdown(conn);
                rdsv3_conn_reset(conn);
                mutex_exit(&conn->c_send_lock);

                if (!rdsv3_conn_transition(conn, RDSV3_CONN_DISCONNECTING,
                    RDSV3_CONN_DOWN)) {
                        /*
                         * This can happen - eg when we're in the middle of
                         * tearing down the connection, and someone unloads
                         * the rds module.
                         * Quite reproduceable with loopback connections.
                         * Mostly harmless.
                         */
#ifndef __lock_lint
                        RDSV3_DPRINTF2("rdsv3_conn_shutdown",
                            "failed to transition to state DOWN, "
                            "current statis is: %d",
                            atomic_get(&conn->c_state));
                        rdsv3_conn_drop(conn);
#endif
                        return;
                }
        }

        /*
         * Then reconnect if it's still live.
         * The passive side of an IB loopback connection is never added
         * to the conn hash, so we never trigger a reconnect on this
         * conn - the reconnect is always triggered by the active peer.
         */
        rdsv3_cancel_delayed_work(&conn->c_conn_w);

        {
                struct rdsv3_conn_info_s conn_info;

                conn_info.c_laddr = conn->c_laddr;
                conn_info.c_faddr = conn->c_faddr;
                if (avl_find(&rdsv3_conn_hash, &conn_info, NULL) == conn)
                        rdsv3_queue_reconnect(conn);
        }
        RDSV3_DPRINTF2("rdsv3_conn_shutdown", "Exit");
}

/*
 * Stop and free a connection.
 */
void
rdsv3_conn_destroy(struct rdsv3_connection *conn)
{
        struct rdsv3_message *rm, *rtmp;
        list_t to_be_dropped;

        RDSV3_DPRINTF4("rdsv3_conn_destroy",
            "freeing conn %p for %u.%u.%u.%u -> %u.%u.%u.%u",
            conn, NIPQUAD(conn->c_laddr), NIPQUAD(conn->c_faddr));

        avl_remove(&rdsv3_conn_hash, conn);

        rdsv3_cancel_delayed_work(&conn->c_reap_w);
        rdsv3_cancel_delayed_work(&conn->c_send_w);
        rdsv3_cancel_delayed_work(&conn->c_recv_w);

        rdsv3_conn_shutdown(conn);

        /* tear down queued messages */

        list_create(&to_be_dropped, sizeof (struct rdsv3_message),
            offsetof(struct rdsv3_message, m_conn_item));

        RDSV3_FOR_EACH_LIST_NODE_SAFE(rm, rtmp, &conn->c_retrans, m_conn_item) {
                list_remove_node(&rm->m_conn_item);
                list_insert_tail(&to_be_dropped, rm);
        }

        RDSV3_FOR_EACH_LIST_NODE_SAFE(rm, rtmp, &conn->c_send_queue,
            m_conn_item) {
                list_remove_node(&rm->m_conn_item);
                list_insert_tail(&to_be_dropped, rm);
        }

        RDSV3_FOR_EACH_LIST_NODE_SAFE(rm, rtmp, &to_be_dropped, m_conn_item) {
                clear_bit(RDSV3_MSG_ON_CONN, &rm->m_flags);
                list_remove_node(&rm->m_conn_item);
                rdsv3_message_put(rm);
        }

        if (conn->c_xmit_rm)
                rdsv3_message_put(conn->c_xmit_rm);

        conn->c_trans->conn_free(conn->c_transport_data);

        /*
         * The congestion maps aren't freed up here.  They're
         * freed by rdsv3_cong_exit() after all the connections
         * have been freed.
         */
        rdsv3_cong_remove_conn(conn);

        ASSERT(list_is_empty(&conn->c_retrans));
        kmem_cache_free(rdsv3_conn_slab, conn);

}

/* ARGSUSED */
static void
rdsv3_conn_message_info(struct rsock *sock, unsigned int len,
    struct rdsv3_info_iterator *iter,
    struct rdsv3_info_lengths *lens,
    int want_send)
{
        struct list *list;
        struct rdsv3_connection *conn;
        struct rdsv3_message *rm;
        unsigned int total = 0;

        RDSV3_DPRINTF4("rdsv3_conn_message_info", "Enter");

        len /= sizeof (struct rds_info_message);

        rw_enter(&rdsv3_conn_lock, RW_READER);

        if (avl_is_empty(&rdsv3_conn_hash)) {
                /* no connections */
                rw_exit(&rdsv3_conn_lock);
                return;
        }

        conn = (struct rdsv3_connection *)avl_first(&rdsv3_conn_hash);

        do {
                if (want_send)
                        list = &conn->c_send_queue;
                else
                        list = &conn->c_retrans;

                mutex_enter(&conn->c_lock);

                /* XXX too lazy to maintain counts.. */
                RDSV3_FOR_EACH_LIST_NODE(rm, list, m_conn_item) {
                        total++;
                        if (total <= len)
                                rdsv3_inc_info_copy(&rm->m_inc, iter,
                                    conn->c_laddr, conn->c_faddr, 0);
                }

                mutex_exit(&conn->c_lock);

                conn = AVL_NEXT(&rdsv3_conn_hash, conn);
        } while (conn != NULL);
        rw_exit(&rdsv3_conn_lock);

        lens->nr = total;
        lens->each = sizeof (struct rds_info_message);

        RDSV3_DPRINTF4("rdsv3_conn_message_info", "Return");
}

static void
rdsv3_conn_message_info_send(struct rsock *sock, unsigned int len,
    struct rdsv3_info_iterator *iter,
    struct rdsv3_info_lengths *lens)
{
        rdsv3_conn_message_info(sock, len, iter, lens, 1);
}

static void
rdsv3_conn_message_info_retrans(struct rsock *sock,
    unsigned int len,
    struct rdsv3_info_iterator *iter,
    struct rdsv3_info_lengths *lens)
{
        rdsv3_conn_message_info(sock, len, iter, lens, 0);
}

/* ARGSUSED */
void
rdsv3_for_each_conn_info(struct rsock *sock, unsigned int len,
    struct rdsv3_info_iterator *iter,
    struct rdsv3_info_lengths *lens,
    int (*visitor)(struct rdsv3_connection *, void *),
    size_t item_len)
{
        uint8_t *buffer;
        struct rdsv3_connection *conn;

        rw_enter(&rdsv3_conn_lock, RW_READER);

        lens->nr = 0;
        lens->each = item_len;

        if (avl_is_empty(&rdsv3_conn_hash)) {
                /* no connections */
                rw_exit(&rdsv3_conn_lock);
                return;
        }

        /* allocate a little extra as this can get cast to a uint64_t */
        buffer = kmem_zalloc(item_len + 8, KM_SLEEP);

        conn = (struct rdsv3_connection *)avl_first(&rdsv3_conn_hash);

        do {
                /* XXX no c_lock usage.. */
                if (visitor(conn, buffer)) {
                        /*
                         * We copy as much as we can fit in the buffer,
                         * but we count all items so that the caller
                         * can resize the buffer.
                         */
                        if (len >= item_len) {
                                RDSV3_DPRINTF4("rdsv3_for_each_conn_info",
                                    "buffer: %p iter: %p bytes: %d", buffer,
                                    iter->addr + iter->offset, item_len);
                                rdsv3_info_copy(iter, buffer, item_len);
                                len -= item_len;
                        }
                        lens->nr++;
                }
                conn = AVL_NEXT(&rdsv3_conn_hash, conn);
        } while (conn != NULL);
        rw_exit(&rdsv3_conn_lock);

        kmem_free(buffer, item_len + 8);
}

static int
rdsv3_conn_info_visitor(struct rdsv3_connection *conn, void *buffer)
{
        struct rds_info_connection *cinfo = buffer;

        cinfo->next_tx_seq = conn->c_next_tx_seq;
        cinfo->next_rx_seq = conn->c_next_rx_seq;
        cinfo->laddr = conn->c_laddr;
        cinfo->faddr = conn->c_faddr;
        (void) strncpy((char *)cinfo->transport, conn->c_trans->t_name,
            sizeof (cinfo->transport));
        cinfo->flags = 0;

        rdsv3_conn_info_set(cinfo->flags,
            MUTEX_HELD(&conn->c_send_lock), SENDING);

        /* XXX Future: return the state rather than these funky bits */
        rdsv3_conn_info_set(cinfo->flags,
            atomic_get(&conn->c_state) == RDSV3_CONN_CONNECTING,
            CONNECTING);
        rdsv3_conn_info_set(cinfo->flags,
            atomic_get(&conn->c_state) == RDSV3_CONN_UP,
            CONNECTED);
        return (1);
}

static void
rdsv3_conn_info(struct rsock *sock, unsigned int len,
    struct rdsv3_info_iterator *iter, struct rdsv3_info_lengths *lens)
{
        rdsv3_for_each_conn_info(sock, len, iter, lens,
            rdsv3_conn_info_visitor, sizeof (struct rds_info_connection));
}

int
rdsv3_conn_init()
{
        RDSV3_DPRINTF4("rdsv3_conn_init", "Enter");

        rdsv3_conn_slab = kmem_cache_create("rdsv3_connection",
            sizeof (struct rdsv3_connection), 0, rdsv3_conn_constructor,
            rdsv3_conn_destructor, NULL, NULL, NULL, 0);
        if (!rdsv3_conn_slab) {
                RDSV3_DPRINTF2("rdsv3_conn_init",
                    "kmem_cache_create(rdsv3_conn_slab) failed");
                return (-ENOMEM);
        }

        avl_create(&rdsv3_conn_hash, rdsv3_conn_compare,
            sizeof (struct rdsv3_connection), offsetof(struct rdsv3_connection,
            c_hash_node));

        rw_init(&rdsv3_conn_lock, NULL, RW_DRIVER, NULL);

        rdsv3_loop_init();

        rdsv3_info_register_func(RDS_INFO_CONNECTIONS, rdsv3_conn_info);
        rdsv3_info_register_func(RDS_INFO_SEND_MESSAGES,
            rdsv3_conn_message_info_send);
        rdsv3_info_register_func(RDS_INFO_RETRANS_MESSAGES,
            rdsv3_conn_message_info_retrans);

        RDSV3_DPRINTF4("rdsv3_conn_init", "Return");

        return (0);
}

void
rdsv3_conn_exit()
{
        RDSV3_DPRINTF4("rdsv3_conn_exit", "Enter");

        rdsv3_loop_exit();

        rw_destroy(&rdsv3_conn_lock);
        avl_destroy(&rdsv3_conn_hash);

        ASSERT(rdsv3_conn_slab);
        kmem_cache_destroy(rdsv3_conn_slab);

        RDSV3_DPRINTF4("rdsv3_conn_exit", "Return");
}

/*
 * Force a disconnect
 */
void
rdsv3_conn_drop(struct rdsv3_connection *conn)
{
        conn->c_state = RDSV3_CONN_ERROR;
        rdsv3_queue_work(rdsv3_wq, &conn->c_down_w);
}