/*
 * 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 <linux/kernel.h>
#include <linux/in.h>
#include <linux/if.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/if_arp.h>
#include <linux/delay.h>
#include <linux/slab.h>

#include "rds.h"
#include "ib.h"

static unsigned int fmr_pool_size = RDS_FMR_POOL_SIZE;
unsigned int fmr_message_size = RDS_FMR_SIZE + 1; /* +1 allows for unaligned MRs */
unsigned int rds_ib_retry_count = RDS_IB_DEFAULT_RETRY_COUNT;

module_param(fmr_pool_size, int, 0444);
MODULE_PARM_DESC(fmr_pool_size, " Max number of fmr per HCA");
module_param(fmr_message_size, int, 0444);
MODULE_PARM_DESC(fmr_message_size, " Max size of a RDMA transfer");
module_param(rds_ib_retry_count, int, 0444);
MODULE_PARM_DESC(rds_ib_retry_count, " Number of hw retries before reporting an error");

/*
 * we have a clumsy combination of RCU and a rwsem protecting this list
 * because it is used both in the get_mr fast path and while blocking in
 * the FMR flushing path.
 */
DECLARE_RWSEM(rds_ib_devices_lock);
struct list_head rds_ib_devices;

/* NOTE: if also grabbing ibdev lock, grab this first */
DEFINE_SPINLOCK(ib_nodev_conns_lock);
LIST_HEAD(ib_nodev_conns);

static void rds_ib_nodev_connect(void)
{
        struct rds_ib_connection *ic;

        spin_lock(&ib_nodev_conns_lock);
        list_for_each_entry(ic, &ib_nodev_conns, ib_node)
                rds_conn_connect_if_down(ic->conn);
        spin_unlock(&ib_nodev_conns_lock);
}

static void rds_ib_dev_shutdown(struct rds_ib_device *rds_ibdev)
{
        struct rds_ib_connection *ic;
        unsigned long flags;

        spin_lock_irqsave(&rds_ibdev->spinlock, flags);
        list_for_each_entry(ic, &rds_ibdev->conn_list, ib_node)
                rds_conn_drop(ic->conn);
        spin_unlock_irqrestore(&rds_ibdev->spinlock, flags);
}

/*
 * rds_ib_destroy_mr_pool() blocks on a few things and mrs drop references
 * from interrupt context so we push freing off into a work struct in krdsd.
 */
static void rds_ib_dev_free(struct work_struct *work)
{
        struct rds_ib_ipaddr *i_ipaddr, *i_next;
        struct rds_ib_device *rds_ibdev = container_of(work,
                                        struct rds_ib_device, free_work);

        if (rds_ibdev->mr_pool)
                rds_ib_destroy_mr_pool(rds_ibdev->mr_pool);
        if (rds_ibdev->mr)
                ib_dereg_mr(rds_ibdev->mr);
        if (rds_ibdev->pd)
                ib_dealloc_pd(rds_ibdev->pd);

        list_for_each_entry_safe(i_ipaddr, i_next, &rds_ibdev->ipaddr_list, list) {
                list_del(&i_ipaddr->list);
                kfree(i_ipaddr);
        }

        kfree(rds_ibdev);
}

void rds_ib_dev_put(struct rds_ib_device *rds_ibdev)
{
        BUG_ON(atomic_read(&rds_ibdev->refcount) <= 0);
        if (atomic_dec_and_test(&rds_ibdev->refcount))
                queue_work(rds_wq, &rds_ibdev->free_work);
}

static void rds_ib_add_one(struct ib_device *device)
{
        struct rds_ib_device *rds_ibdev;
        struct ib_device_attr *dev_attr;

        /* Only handle IB (no iWARP) devices */
        if (device->node_type != RDMA_NODE_IB_CA)
                return;

        dev_attr = kmalloc(sizeof *dev_attr, GFP_KERNEL);
        if (!dev_attr)
                return;

        if (ib_query_device(device, dev_attr)) {
                rdsdebug("Query device failed for %s\n", device->name);
                goto free_attr;
        }

        rds_ibdev = kzalloc_node(sizeof(struct rds_ib_device), GFP_KERNEL,
                                 ibdev_to_node(device));
        if (!rds_ibdev)
                goto free_attr;

        spin_lock_init(&rds_ibdev->spinlock);
        atomic_set(&rds_ibdev->refcount, 1);
        INIT_WORK(&rds_ibdev->free_work, rds_ib_dev_free);

        rds_ibdev->max_wrs = dev_attr->max_qp_wr;
        rds_ibdev->max_sge = min(dev_attr->max_sge, RDS_IB_MAX_SGE);

        rds_ibdev->fmr_max_remaps = dev_attr->max_map_per_fmr?: 32;
        rds_ibdev->max_fmrs = dev_attr->max_fmr ?
                        min_t(unsigned int, dev_attr->max_fmr, fmr_pool_size) :
                        fmr_pool_size;

        rds_ibdev->max_initiator_depth = dev_attr->max_qp_init_rd_atom;
        rds_ibdev->max_responder_resources = dev_attr->max_qp_rd_atom;

        rds_ibdev->dev = device;
        rds_ibdev->pd = ib_alloc_pd(device);
        if (IS_ERR(rds_ibdev->pd)) {
                rds_ibdev->pd = NULL;
                goto put_dev;
        }

        rds_ibdev->mr = ib_get_dma_mr(rds_ibdev->pd, IB_ACCESS_LOCAL_WRITE);
        if (IS_ERR(rds_ibdev->mr)) {
                rds_ibdev->mr = NULL;
                goto put_dev;
        }

        rds_ibdev->mr_pool = rds_ib_create_mr_pool(rds_ibdev);
        if (IS_ERR(rds_ibdev->mr_pool)) {
                rds_ibdev->mr_pool = NULL;
                goto put_dev;
        }

        INIT_LIST_HEAD(&rds_ibdev->ipaddr_list);
        INIT_LIST_HEAD(&rds_ibdev->conn_list);

        down_write(&rds_ib_devices_lock);
        list_add_tail_rcu(&rds_ibdev->list, &rds_ib_devices);
        up_write(&rds_ib_devices_lock);
        atomic_inc(&rds_ibdev->refcount);

        ib_set_client_data(device, &rds_ib_client, rds_ibdev);
        atomic_inc(&rds_ibdev->refcount);

        rds_ib_nodev_connect();

put_dev:
        rds_ib_dev_put(rds_ibdev);
free_attr:
        kfree(dev_attr);
}

/*
 * New connections use this to find the device to associate with the
 * connection.  It's not in the fast path so we're not concerned about the
 * performance of the IB call.  (As of this writing, it uses an interrupt
 * blocking spinlock to serialize walking a per-device list of all registered
 * clients.)
 *
 * RCU is used to handle incoming connections racing with device teardown.
 * Rather than use a lock to serialize removal from the client_data and
 * getting a new reference, we use an RCU grace period.  The destruction
 * path removes the device from client_data and then waits for all RCU
 * readers to finish.
 *
 * A new connection can get NULL from this if its arriving on a
 * device that is in the process of being removed.
 */
struct rds_ib_device *rds_ib_get_client_data(struct ib_device *device)
{
        struct rds_ib_device *rds_ibdev;

        rcu_read_lock();
        rds_ibdev = ib_get_client_data(device, &rds_ib_client);
        if (rds_ibdev)
                atomic_inc(&rds_ibdev->refcount);
        rcu_read_unlock();
        return rds_ibdev;
}

/*
 * The IB stack is letting us know that a device is going away.  This can
 * happen if the underlying HCA driver is removed or if PCI hotplug is removing
 * the pci function, for example.
 *
 * This can be called at any time and can be racing with any other RDS path.
 */
static void rds_ib_remove_one(struct ib_device *device)
{
        struct rds_ib_device *rds_ibdev;

        rds_ibdev = ib_get_client_data(device, &rds_ib_client);
        if (!rds_ibdev)
                return;

        rds_ib_dev_shutdown(rds_ibdev);

        /* stop connection attempts from getting a reference to this device. */
        ib_set_client_data(device, &rds_ib_client, NULL);

        down_write(&rds_ib_devices_lock);
        list_del_rcu(&rds_ibdev->list);
        up_write(&rds_ib_devices_lock);

        /*
         * This synchronize rcu is waiting for readers of both the ib
         * client data and the devices list to finish before we drop
         * both of those references.
         */
        synchronize_rcu();
        rds_ib_dev_put(rds_ibdev);
        rds_ib_dev_put(rds_ibdev);
}

struct ib_client rds_ib_client = {
        .name   = "rds_ib",
        .add    = rds_ib_add_one,
        .remove = rds_ib_remove_one
};

static int rds_ib_conn_info_visitor(struct rds_connection *conn,
                                    void *buffer)
{
        struct rds_info_rdma_connection *iinfo = buffer;
        struct rds_ib_connection *ic;

        /* We will only ever look at IB transports */
        if (conn->c_trans != &rds_ib_transport)
                return 0;

        iinfo->src_addr = conn->c_laddr;
        iinfo->dst_addr = conn->c_faddr;

        memset(&iinfo->src_gid, 0, sizeof(iinfo->src_gid));
        memset(&iinfo->dst_gid, 0, sizeof(iinfo->dst_gid));
        if (rds_conn_state(conn) == RDS_CONN_UP) {
                struct rds_ib_device *rds_ibdev;
                struct rdma_dev_addr *dev_addr;

                ic = conn->c_transport_data;
                dev_addr = &ic->i_cm_id->route.addr.dev_addr;

                rdma_addr_get_sgid(dev_addr, (union ib_gid *) &iinfo->src_gid);
                rdma_addr_get_dgid(dev_addr, (union ib_gid *) &iinfo->dst_gid);

                rds_ibdev = ic->rds_ibdev;
                iinfo->max_send_wr = ic->i_send_ring.w_nr;
                iinfo->max_recv_wr = ic->i_recv_ring.w_nr;
                iinfo->max_send_sge = rds_ibdev->max_sge;
                rds_ib_get_mr_info(rds_ibdev, iinfo);
        }
        return 1;
}

static void rds_ib_ic_info(struct socket *sock, unsigned int len,
                           struct rds_info_iterator *iter,
                           struct rds_info_lengths *lens)
{
        rds_for_each_conn_info(sock, len, iter, lens,
                                rds_ib_conn_info_visitor,
                                sizeof(struct rds_info_rdma_connection));
}


/*
 * Early RDS/IB was built to only bind to an address if there is an IPoIB
 * device with that address set.
 *
 * If it were me, I'd advocate for something more flexible.  Sending and
 * receiving should be device-agnostic.  Transports would try and maintain
 * connections between peers who have messages queued.  Userspace would be
 * allowed to influence which paths have priority.  We could call userspace
 * asserting this policy "routing".
 */
static int rds_ib_laddr_check(__be32 addr)
{
        int ret;
        struct rdma_cm_id *cm_id;
        struct sockaddr_in sin;

        /* Create a CMA ID and try to bind it. This catches both
         * IB and iWARP capable NICs.
         */
        cm_id = rdma_create_id(NULL, NULL, RDMA_PS_TCP, IB_QPT_RC);
        if (IS_ERR(cm_id))
                return PTR_ERR(cm_id);

        memset(&sin, 0, sizeof(sin));
        sin.sin_family = AF_INET;
        sin.sin_addr.s_addr = addr;

        /* rdma_bind_addr will only succeed for IB & iWARP devices */
        ret = rdma_bind_addr(cm_id, (struct sockaddr *)&sin);
        /* due to this, we will claim to support iWARP devices unless we
           check node_type. */
        if (ret || cm_id->device->node_type != RDMA_NODE_IB_CA)
                ret = -EADDRNOTAVAIL;

        rdsdebug("addr %pI4 ret %d node type %d\n",
                &addr, ret,
                cm_id->device ? cm_id->device->node_type : -1);

        rdma_destroy_id(cm_id);

        return ret;
}

static void rds_ib_unregister_client(void)
{
        ib_unregister_client(&rds_ib_client);
        /* wait for rds_ib_dev_free() to complete */
        flush_workqueue(rds_wq);
}

void rds_ib_exit(void)
{
        rds_info_deregister_func(RDS_INFO_IB_CONNECTIONS, rds_ib_ic_info);
        rds_ib_unregister_client();
        rds_ib_destroy_nodev_conns();
        rds_ib_sysctl_exit();
        rds_ib_recv_exit();
        rds_trans_unregister(&rds_ib_transport);
}

struct rds_transport rds_ib_transport = {
        .laddr_check            = rds_ib_laddr_check,
        .xmit_complete          = rds_ib_xmit_complete,
        .xmit                   = rds_ib_xmit,
        .xmit_rdma              = rds_ib_xmit_rdma,
        .xmit_atomic            = rds_ib_xmit_atomic,
        .recv                   = rds_ib_recv,
        .conn_alloc             = rds_ib_conn_alloc,
        .conn_free              = rds_ib_conn_free,
        .conn_connect           = rds_ib_conn_connect,
        .conn_shutdown          = rds_ib_conn_shutdown,
        .inc_copy_to_user       = rds_ib_inc_copy_to_user,
        .inc_free               = rds_ib_inc_free,
        .cm_initiate_connect    = rds_ib_cm_initiate_connect,
        .cm_handle_connect      = rds_ib_cm_handle_connect,
        .cm_connect_complete    = rds_ib_cm_connect_complete,
        .stats_info_copy        = rds_ib_stats_info_copy,
        .exit                   = rds_ib_exit,
        .get_mr                 = rds_ib_get_mr,
        .sync_mr                = rds_ib_sync_mr,
        .free_mr                = rds_ib_free_mr,
        .flush_mrs              = rds_ib_flush_mrs,
        .t_owner                = THIS_MODULE,
        .t_name                 = "infiniband",
        .t_type                 = RDS_TRANS_IB
};

int rds_ib_init(void)
{
        int ret;

        INIT_LIST_HEAD(&rds_ib_devices);

        ret = ib_register_client(&rds_ib_client);
        if (ret)
                goto out;

        ret = rds_ib_sysctl_init();
        if (ret)
                goto out_ibreg;

        ret = rds_ib_recv_init();
        if (ret)
                goto out_sysctl;

        ret = rds_trans_register(&rds_ib_transport);
        if (ret)
                goto out_recv;

        rds_info_register_func(RDS_INFO_IB_CONNECTIONS, rds_ib_ic_info);

        goto out;

out_recv:
        rds_ib_recv_exit();
out_sysctl:
        rds_ib_sysctl_exit();
out_ibreg:
        rds_ib_unregister_client();
out:
        return ret;
}

MODULE_LICENSE("GPL");