/*
 * Copyright (c) 2005 Voltaire Inc.  All rights reserved.
 * Copyright (c) 2002-2005, Network Appliance, Inc. All rights reserved.
 * Copyright (c) 1999-2005, Mellanox Technologies, Inc. All rights reserved.
 * Copyright (c) 2005 Intel Corporation.  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/mutex.h>
#include <linux/inetdevice.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <net/arp.h>
#include <net/neighbour.h>
#include <net/route.h>
#include <net/netevent.h>
#include <net/ipv6_stubs.h>
#include <net/ip6_route.h>
#include <rdma/ib_addr.h>
#include <rdma/ib_cache.h>
#include <rdma/ib_sa.h>
#include <rdma/ib.h>
#include <rdma/rdma_netlink.h>
#include <net/netlink.h>

#include "core_priv.h"

struct addr_req {
        struct list_head list;
        struct sockaddr_storage src_addr;
        struct sockaddr_storage dst_addr;
        struct rdma_dev_addr *addr;
        void *context;
        void (*callback)(int status, struct sockaddr *src_addr,
                         struct rdma_dev_addr *addr, void *context);
        unsigned long timeout;
        struct delayed_work work;
        bool resolve_by_gid_attr;       /* Consider gid attr in resolve phase */
        int status;
        u32 seq;
};

static atomic_t ib_nl_addr_request_seq = ATOMIC_INIT(0);

static DEFINE_SPINLOCK(lock);
static LIST_HEAD(req_list);
static struct workqueue_struct *addr_wq;

static const struct nla_policy ib_nl_addr_policy[LS_NLA_TYPE_MAX] = {
        [LS_NLA_TYPE_DGID] = {.type = NLA_BINARY,
                .len = sizeof(struct rdma_nla_ls_gid),
                .validation_type = NLA_VALIDATE_MIN,
                .min = sizeof(struct rdma_nla_ls_gid)},
};

static void ib_nl_process_ip_rsep(const struct nlmsghdr *nlh)
{
        struct nlattr *tb[LS_NLA_TYPE_MAX] = {};
        union ib_gid gid;
        struct addr_req *req;
        int found = 0;
        int ret;

        if (nlh->nlmsg_flags & RDMA_NL_LS_F_ERR)
                return;

        ret = nla_parse_deprecated(tb, LS_NLA_TYPE_MAX - 1, nlmsg_data(nlh),
                                   nlmsg_len(nlh), ib_nl_addr_policy, NULL);
        if (ret)
                return;

        if (!tb[LS_NLA_TYPE_DGID])
                return;
        memcpy(&gid, nla_data(tb[LS_NLA_TYPE_DGID]), sizeof(gid));

        spin_lock_bh(&lock);
        list_for_each_entry(req, &req_list, list) {
                if (nlh->nlmsg_seq != req->seq)
                        continue;
                /* We set the DGID part, the rest was set earlier */
                rdma_addr_set_dgid(req->addr, &gid);
                req->status = 0;
                found = 1;
                break;
        }
        spin_unlock_bh(&lock);

        if (!found)
                pr_info("Couldn't find request waiting for DGID: %pI6\n",
                        &gid);
}

int ib_nl_handle_ip_res_resp(struct sk_buff *skb,
                             struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        if ((nlh->nlmsg_flags & NLM_F_REQUEST) ||
            !(NETLINK_CB(skb).sk))
                return -EPERM;

        ib_nl_process_ip_rsep(nlh);

        return 0;
}

static int ib_nl_ip_send_msg(struct rdma_dev_addr *dev_addr,
                             const void *daddr,
                             u32 seq, u16 family)
{
        struct sk_buff *skb = NULL;
        struct nlmsghdr *nlh;
        struct rdma_ls_ip_resolve_header *header;
        void *data;
        size_t size;
        int attrtype;
        int len;

        if (family == AF_INET) {
                size = sizeof(struct in_addr);
                attrtype = RDMA_NLA_F_MANDATORY | LS_NLA_TYPE_IPV4;
        } else {
                size = sizeof(struct in6_addr);
                attrtype = RDMA_NLA_F_MANDATORY | LS_NLA_TYPE_IPV6;
        }

        len = nla_total_size(sizeof(size));
        len += NLMSG_ALIGN(sizeof(*header));

        skb = nlmsg_new(len, GFP_KERNEL);
        if (!skb)
                return -ENOMEM;

        data = ibnl_put_msg(skb, &nlh, seq, 0, RDMA_NL_LS,
                            RDMA_NL_LS_OP_IP_RESOLVE, NLM_F_REQUEST);
        if (!data) {
                nlmsg_free(skb);
                return -ENODATA;
        }

        /* Construct the family header first */
        header = skb_put(skb, NLMSG_ALIGN(sizeof(*header)));
        header->ifindex = dev_addr->bound_dev_if;
        nla_put(skb, attrtype, size, daddr);

        /* Repair the nlmsg header length */
        nlmsg_end(skb, nlh);
        rdma_nl_multicast(&init_net, skb, RDMA_NL_GROUP_LS, GFP_KERNEL);

        /* Make the request retry, so when we get the response from userspace
         * we will have something.
         */
        return -ENODATA;
}

int rdma_addr_size(const struct sockaddr *addr)
{
        switch (addr->sa_family) {
        case AF_INET:
                return sizeof(struct sockaddr_in);
        case AF_INET6:
                return sizeof(struct sockaddr_in6);
        case AF_IB:
                return sizeof(struct sockaddr_ib);
        default:
                return 0;
        }
}
EXPORT_SYMBOL(rdma_addr_size);

int rdma_addr_size_in6(struct sockaddr_in6 *addr)
{
        int ret = rdma_addr_size((struct sockaddr *) addr);

        return ret <= sizeof(*addr) ? ret : 0;
}
EXPORT_SYMBOL(rdma_addr_size_in6);

int rdma_addr_size_kss(struct __kernel_sockaddr_storage *addr)
{
        int ret = rdma_addr_size((struct sockaddr *) addr);

        return ret <= sizeof(*addr) ? ret : 0;
}
EXPORT_SYMBOL(rdma_addr_size_kss);

/**
 * rdma_copy_src_l2_addr - Copy netdevice source addresses
 * @dev_addr:   Destination address pointer where to copy the addresses
 * @dev:        Netdevice whose source addresses to copy
 *
 * rdma_copy_src_l2_addr() copies source addresses from the specified netdevice.
 * This includes unicast address, broadcast address, device type and
 * interface index.
 */
void rdma_copy_src_l2_addr(struct rdma_dev_addr *dev_addr,
                           const struct net_device *dev)
{
        dev_addr->dev_type = dev->type;
        memcpy(dev_addr->src_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
        memcpy(dev_addr->broadcast, dev->broadcast, MAX_ADDR_LEN);
        dev_addr->bound_dev_if = dev->ifindex;
}
EXPORT_SYMBOL(rdma_copy_src_l2_addr);

static struct net_device *
rdma_find_ndev_for_src_ip_rcu(struct net *net, const struct sockaddr *src_in)
{
        struct net_device *dev = NULL;
        int ret = -EADDRNOTAVAIL;

        switch (src_in->sa_family) {
        case AF_INET:
                dev = __ip_dev_find(net,
                                    ((const struct sockaddr_in *)src_in)->sin_addr.s_addr,
                                    false);
                if (dev)
                        ret = 0;
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                for_each_netdev_rcu(net, dev) {
                        if (ipv6_chk_addr(net,
                                          &((const struct sockaddr_in6 *)src_in)->sin6_addr,
                                          dev, 1)) {
                                ret = 0;
                                break;
                        }
                }
                break;
#endif
        }
        return ret ? ERR_PTR(ret) : dev;
}

int rdma_translate_ip(const struct sockaddr *addr,
                      struct rdma_dev_addr *dev_addr)
{
        struct net_device *dev;

        if (dev_addr->bound_dev_if) {
                dev = dev_get_by_index(dev_addr->net, dev_addr->bound_dev_if);
                if (!dev)
                        return -ENODEV;
                rdma_copy_src_l2_addr(dev_addr, dev);
                dev_put(dev);
                return 0;
        }

        rcu_read_lock();
        dev = rdma_find_ndev_for_src_ip_rcu(dev_addr->net, addr);
        if (!IS_ERR(dev))
                rdma_copy_src_l2_addr(dev_addr, dev);
        rcu_read_unlock();
        return PTR_ERR_OR_ZERO(dev);
}
EXPORT_SYMBOL(rdma_translate_ip);

static void set_timeout(struct addr_req *req, unsigned long time)
{
        unsigned long delay;

        delay = time - jiffies;
        if ((long)delay < 0)
                delay = 0;

        mod_delayed_work(addr_wq, &req->work, delay);
}

static void queue_req(struct addr_req *req)
{
        spin_lock_bh(&lock);
        list_add_tail(&req->list, &req_list);
        set_timeout(req, req->timeout);
        spin_unlock_bh(&lock);
}

static int ib_nl_fetch_ha(struct rdma_dev_addr *dev_addr,
                          const void *daddr, u32 seq, u16 family)
{
        if (!rdma_nl_chk_listeners(RDMA_NL_GROUP_LS))
                return -EADDRNOTAVAIL;

        return ib_nl_ip_send_msg(dev_addr, daddr, seq, family);
}

static int dst_fetch_ha(const struct dst_entry *dst,
                        struct rdma_dev_addr *dev_addr,
                        const void *daddr)
{
        struct neighbour *n;
        int ret = 0;

        n = dst_neigh_lookup(dst, daddr);
        if (!n)
                return -ENODATA;

        if (!(n->nud_state & NUD_VALID)) {
                neigh_event_send(n, NULL);
                ret = -ENODATA;
        } else {
                neigh_ha_snapshot(dev_addr->dst_dev_addr, n, dst->dev);
        }

        neigh_release(n);

        return ret;
}

static bool has_gateway(const struct dst_entry *dst, sa_family_t family)
{
        if (family == AF_INET)
                return dst_rtable(dst)->rt_uses_gateway;

        return dst_rt6_info(dst)->rt6i_flags & RTF_GATEWAY;
}

static int fetch_ha(const struct dst_entry *dst, struct rdma_dev_addr *dev_addr,
                    const struct sockaddr *dst_in, u32 seq)
{
        const struct sockaddr_in *dst_in4 =
                (const struct sockaddr_in *)dst_in;
        const struct sockaddr_in6 *dst_in6 =
                (const struct sockaddr_in6 *)dst_in;
        const void *daddr = (dst_in->sa_family == AF_INET) ?
                (const void *)&dst_in4->sin_addr.s_addr :
                (const void *)&dst_in6->sin6_addr;
        sa_family_t family = dst_in->sa_family;

        might_sleep();

        /* If we have a gateway in IB mode then it must be an IB network */
        if (has_gateway(dst, family) && dev_addr->network == RDMA_NETWORK_IB)
                return ib_nl_fetch_ha(dev_addr, daddr, seq, family);
        else
                return dst_fetch_ha(dst, dev_addr, daddr);
}

static int addr4_resolve(struct sockaddr *src_sock,
                         const struct sockaddr *dst_sock,
                         struct rdma_dev_addr *addr,
                         struct rtable **prt)
{
        struct sockaddr_in *src_in = (struct sockaddr_in *)src_sock;
        const struct sockaddr_in *dst_in =
                        (const struct sockaddr_in *)dst_sock;

        __be32 src_ip = src_in->sin_addr.s_addr;
        __be32 dst_ip = dst_in->sin_addr.s_addr;
        struct rtable *rt;
        struct flowi4 fl4;
        int ret;

        memset(&fl4, 0, sizeof(fl4));
        fl4.daddr = dst_ip;
        fl4.saddr = src_ip;
        fl4.flowi4_oif = addr->bound_dev_if;
        rt = ip_route_output_key(addr->net, &fl4);
        ret = PTR_ERR_OR_ZERO(rt);
        if (ret)
                return ret;

        src_in->sin_addr.s_addr = fl4.saddr;

        addr->hoplimit = ip4_dst_hoplimit(&rt->dst);

        *prt = rt;
        return 0;
}

#if IS_ENABLED(CONFIG_IPV6)
static int addr6_resolve(struct sockaddr *src_sock,
                         const struct sockaddr *dst_sock,
                         struct rdma_dev_addr *addr,
                         struct dst_entry **pdst)
{
        struct sockaddr_in6 *src_in = (struct sockaddr_in6 *)src_sock;
        const struct sockaddr_in6 *dst_in =
                                (const struct sockaddr_in6 *)dst_sock;
        struct flowi6 fl6;
        struct dst_entry *dst;

        memset(&fl6, 0, sizeof fl6);
        fl6.daddr = dst_in->sin6_addr;
        fl6.saddr = src_in->sin6_addr;
        fl6.flowi6_oif = addr->bound_dev_if;

        dst = ipv6_stub->ipv6_dst_lookup_flow(addr->net, NULL, &fl6, NULL);
        if (IS_ERR(dst))
                return PTR_ERR(dst);

        if (ipv6_addr_any(&src_in->sin6_addr))
                src_in->sin6_addr = fl6.saddr;

        addr->hoplimit = ip6_dst_hoplimit(dst);

        *pdst = dst;
        return 0;
}
#else
static int addr6_resolve(struct sockaddr *src_sock,
                         const struct sockaddr *dst_sock,
                         struct rdma_dev_addr *addr,
                         struct dst_entry **pdst)
{
        return -EADDRNOTAVAIL;
}
#endif

static bool is_dst_local(const struct dst_entry *dst)
{
        if (dst->ops->family == AF_INET)
                return !!(dst_rtable(dst)->rt_type & RTN_LOCAL);
        else if (dst->ops->family == AF_INET6)
                return !!(dst_rt6_info(dst)->rt6i_flags & RTF_LOCAL);
        else
                return false;
}

static int addr_resolve_neigh(const struct dst_entry *dst,
                              const struct sockaddr *dst_in,
                              struct rdma_dev_addr *addr,
                              u32 seq)
{
        if (is_dst_local(dst)) {
                /* When the destination is local entry, source and destination
                 * are same. Skip the neighbour lookup.
                 */
                memcpy(addr->dst_dev_addr, addr->src_dev_addr, MAX_ADDR_LEN);
                return 0;
        }

        return fetch_ha(dst, addr, dst_in, seq);
}

static int rdma_set_src_addr_rcu(struct rdma_dev_addr *dev_addr,
                                 const struct sockaddr *dst_in,
                                 const struct dst_entry *dst)
{
        struct net_device *ndev = READ_ONCE(dst->dev);

        /* A physical device must be the RDMA device to use */
        if (is_dst_local(dst)) {
                int ret;
                /*
                 * RDMA (IB/RoCE, iWarp) doesn't run on lo interface or
                 * loopback IP address. So if route is resolved to loopback
                 * interface, translate that to a real ndev based on non
                 * loopback IP address.
                 */
                ndev = rdma_find_ndev_for_src_ip_rcu(dev_net(ndev), dst_in);
                if (IS_ERR(ndev))
                        return -ENODEV;
                ret = rdma_translate_ip(dst_in, dev_addr);
                if (ret)
                        return ret;
        } else {
                rdma_copy_src_l2_addr(dev_addr, dst->dev);
        }

        /*
         * If there's a gateway and type of device not ARPHRD_INFINIBAND,
         * we're definitely in RoCE v2 (as RoCE v1 isn't routable) set the
         * network type accordingly.
         */
        if (has_gateway(dst, dst_in->sa_family) &&
            ndev->type != ARPHRD_INFINIBAND)
                dev_addr->network = dst_in->sa_family == AF_INET ?
                                                RDMA_NETWORK_IPV4 :
                                                RDMA_NETWORK_IPV6;
        else
                dev_addr->network = RDMA_NETWORK_IB;

        return 0;
}

static int set_addr_netns_by_gid_rcu(struct rdma_dev_addr *addr)
{
        struct net_device *ndev;

        ndev = rdma_read_gid_attr_ndev_rcu(addr->sgid_attr);
        if (IS_ERR(ndev))
                return PTR_ERR(ndev);

        /*
         * Since we are holding the rcu, reading net and ifindex
         * are safe without any additional reference; because
         * change_net_namespace() in net/core/dev.c does rcu sync
         * after it changes the state to IFF_DOWN and before
         * updating netdev fields {net, ifindex}.
         */
        addr->net = dev_net(ndev);
        addr->bound_dev_if = ndev->ifindex;
        return 0;
}

static void rdma_addr_set_net_defaults(struct rdma_dev_addr *addr)
{
        addr->net = &init_net;
        addr->bound_dev_if = 0;
}

static int addr_resolve(struct sockaddr *src_in,
                        const struct sockaddr *dst_in,
                        struct rdma_dev_addr *addr,
                        bool resolve_neigh,
                        bool resolve_by_gid_attr,
                        u32 seq)
{
        struct dst_entry *dst = NULL;
        struct rtable *rt = NULL;
        int ret;

        if (!addr->net) {
                pr_warn_ratelimited("%s: missing namespace\n", __func__);
                return -EINVAL;
        }

        rcu_read_lock();
        if (resolve_by_gid_attr) {
                if (!addr->sgid_attr) {
                        rcu_read_unlock();
                        pr_warn_ratelimited("%s: missing gid_attr\n", __func__);
                        return -EINVAL;
                }
                /*
                 * If the request is for a specific gid attribute of the
                 * rdma_dev_addr, derive net from the netdevice of the
                 * GID attribute.
                 */
                ret = set_addr_netns_by_gid_rcu(addr);
                if (ret) {
                        rcu_read_unlock();
                        return ret;
                }
        }
        if (src_in->sa_family == AF_INET) {
                ret = addr4_resolve(src_in, dst_in, addr, &rt);
                dst = &rt->dst;
        } else {
                ret = addr6_resolve(src_in, dst_in, addr, &dst);
        }
        if (ret) {
                rcu_read_unlock();
                goto done;
        }
        ret = rdma_set_src_addr_rcu(addr, dst_in, dst);
        rcu_read_unlock();

        /*
         * Resolve neighbor destination address if requested and
         * only if src addr translation didn't fail.
         */
        if (!ret && resolve_neigh)
                ret = addr_resolve_neigh(dst, dst_in, addr, seq);

        if (src_in->sa_family == AF_INET)
                ip_rt_put(rt);
        else
                dst_release(dst);
done:
        /*
         * Clear the addr net to go back to its original state, only if it was
         * derived from GID attribute in this context.
         */
        if (resolve_by_gid_attr)
                rdma_addr_set_net_defaults(addr);
        return ret;
}

static void process_one_req(struct work_struct *_work)
{
        struct addr_req *req;
        struct sockaddr *src_in, *dst_in;

        req = container_of(_work, struct addr_req, work.work);

        if (req->status == -ENODATA) {
                src_in = (struct sockaddr *)&req->src_addr;
                dst_in = (struct sockaddr *)&req->dst_addr;
                req->status = addr_resolve(src_in, dst_in, req->addr,
                                           true, req->resolve_by_gid_attr,
                                           req->seq);
                if (req->status && time_after_eq(jiffies, req->timeout)) {
                        req->status = -ETIMEDOUT;
                } else if (req->status == -ENODATA) {
                        /* requeue the work for retrying again */
                        spin_lock_bh(&lock);
                        if (!list_empty(&req->list))
                                set_timeout(req, req->timeout);
                        spin_unlock_bh(&lock);
                        return;
                }
        }

        req->callback(req->status, (struct sockaddr *)&req->src_addr,
                req->addr, req->context);
        req->callback = NULL;

        spin_lock_bh(&lock);
        /*
         * Although the work will normally have been canceled by the workqueue,
         * it can still be requeued as long as it is on the req_list.
         */
        cancel_delayed_work(&req->work);
        if (!list_empty(&req->list)) {
                list_del_init(&req->list);
                kfree(req);
        }
        spin_unlock_bh(&lock);
}

int rdma_resolve_ip(struct sockaddr *src_addr, const struct sockaddr *dst_addr,
                    struct rdma_dev_addr *addr, unsigned long timeout_ms,
                    void (*callback)(int status, struct sockaddr *src_addr,
                                     struct rdma_dev_addr *addr, void *context),
                    bool resolve_by_gid_attr, void *context)
{
        struct sockaddr *src_in, *dst_in;
        struct addr_req *req;
        int ret = 0;

        req = kzalloc_obj(*req);
        if (!req)
                return -ENOMEM;

        src_in = (struct sockaddr *) &req->src_addr;
        dst_in = (struct sockaddr *) &req->dst_addr;

        if (src_addr) {
                if (src_addr->sa_family != dst_addr->sa_family) {
                        ret = -EINVAL;
                        goto err;
                }

                memcpy(src_in, src_addr, rdma_addr_size(src_addr));
        } else {
                src_in->sa_family = dst_addr->sa_family;
        }

        memcpy(dst_in, dst_addr, rdma_addr_size(dst_addr));
        req->addr = addr;
        req->callback = callback;
        req->context = context;
        req->resolve_by_gid_attr = resolve_by_gid_attr;
        INIT_DELAYED_WORK(&req->work, process_one_req);
        req->seq = (u32)atomic_inc_return(&ib_nl_addr_request_seq);

        req->status = addr_resolve(src_in, dst_in, addr, true,
                                   req->resolve_by_gid_attr, req->seq);
        switch (req->status) {
        case 0:
                req->timeout = jiffies;
                queue_req(req);
                break;
        case -ENODATA:
                req->timeout = msecs_to_jiffies(timeout_ms) + jiffies;
                queue_req(req);
                break;
        default:
                ret = req->status;
                goto err;
        }
        return ret;
err:
        kfree(req);
        return ret;
}
EXPORT_SYMBOL(rdma_resolve_ip);

int roce_resolve_route_from_path(struct sa_path_rec *rec,
                                 const struct ib_gid_attr *attr)
{
        union {
                struct sockaddr     _sockaddr;
                struct sockaddr_in  _sockaddr_in;
                struct sockaddr_in6 _sockaddr_in6;
        } sgid, dgid;
        struct rdma_dev_addr dev_addr = {};
        int ret;

        might_sleep();

        if (rec->roce.route_resolved)
                return 0;

        rdma_gid2ip((struct sockaddr *)&sgid, &rec->sgid);
        rdma_gid2ip((struct sockaddr *)&dgid, &rec->dgid);

        if (sgid._sockaddr.sa_family != dgid._sockaddr.sa_family)
                return -EINVAL;

        if (!attr || !attr->ndev)
                return -EINVAL;

        dev_addr.net = &init_net;
        dev_addr.sgid_attr = attr;

        ret = addr_resolve((struct sockaddr *)&sgid, (struct sockaddr *)&dgid,
                           &dev_addr, false, true, 0);
        if (ret)
                return ret;

        if ((dev_addr.network == RDMA_NETWORK_IPV4 ||
             dev_addr.network == RDMA_NETWORK_IPV6) &&
            rec->rec_type != SA_PATH_REC_TYPE_ROCE_V2)
                return -EINVAL;

        rec->roce.route_resolved = true;
        return 0;
}

/**
 * rdma_addr_cancel - Cancel resolve ip request
 * @addr:       Pointer to address structure given previously
 *              during rdma_resolve_ip().
 * rdma_addr_cancel() is synchronous function which cancels any pending
 * request if there is any.
 */
void rdma_addr_cancel(struct rdma_dev_addr *addr)
{
        struct addr_req *req, *temp_req;
        struct addr_req *found = NULL;

        spin_lock_bh(&lock);
        list_for_each_entry_safe(req, temp_req, &req_list, list) {
                if (req->addr == addr) {
                        /*
                         * Removing from the list means we take ownership of
                         * the req
                         */
                        list_del_init(&req->list);
                        found = req;
                        break;
                }
        }
        spin_unlock_bh(&lock);

        if (!found)
                return;

        /*
         * sync canceling the work after removing it from the req_list
         * guarentees no work is running and none will be started.
         */
        cancel_delayed_work_sync(&found->work);
        kfree(found);
}
EXPORT_SYMBOL(rdma_addr_cancel);

struct resolve_cb_context {
        struct completion comp;
        int status;
};

static void resolve_cb(int status, struct sockaddr *src_addr,
             struct rdma_dev_addr *addr, void *context)
{
        ((struct resolve_cb_context *)context)->status = status;
        complete(&((struct resolve_cb_context *)context)->comp);
}

int rdma_addr_find_l2_eth_by_grh(const union ib_gid *sgid,
                                 const union ib_gid *dgid,
                                 u8 *dmac, const struct ib_gid_attr *sgid_attr,
                                 int *hoplimit)
{
        struct rdma_dev_addr dev_addr;
        struct resolve_cb_context ctx;
        union {
                struct sockaddr_in  _sockaddr_in;
                struct sockaddr_in6 _sockaddr_in6;
        } sgid_addr, dgid_addr;
        int ret;

        rdma_gid2ip((struct sockaddr *)&sgid_addr, sgid);
        rdma_gid2ip((struct sockaddr *)&dgid_addr, dgid);

        memset(&dev_addr, 0, sizeof(dev_addr));
        dev_addr.net = &init_net;
        dev_addr.sgid_attr = sgid_attr;

        init_completion(&ctx.comp);
        ret = rdma_resolve_ip((struct sockaddr *)&sgid_addr,
                              (struct sockaddr *)&dgid_addr, &dev_addr, 1000,
                              resolve_cb, true, &ctx);
        if (ret)
                return ret;

        wait_for_completion(&ctx.comp);

        ret = ctx.status;
        if (ret)
                return ret;

        memcpy(dmac, dev_addr.dst_dev_addr, ETH_ALEN);
        *hoplimit = dev_addr.hoplimit;
        return 0;
}

static int netevent_callback(struct notifier_block *self, unsigned long event,
        void *ctx)
{
        struct addr_req *req;

        if (event == NETEVENT_NEIGH_UPDATE) {
                struct neighbour *neigh = ctx;

                if (neigh->nud_state & NUD_VALID) {
                        spin_lock_bh(&lock);
                        list_for_each_entry(req, &req_list, list)
                                set_timeout(req, jiffies);
                        spin_unlock_bh(&lock);
                }
        }
        return 0;
}

static struct notifier_block nb = {
        .notifier_call = netevent_callback
};

int addr_init(void)
{
        addr_wq = alloc_ordered_workqueue("ib_addr", 0);
        if (!addr_wq)
                return -ENOMEM;

        register_netevent_notifier(&nb);

        return 0;
}

void addr_cleanup(void)
{
        unregister_netevent_notifier(&nb);
        destroy_workqueue(addr_wq);
        WARN_ON(!list_empty(&req_list));
}