ucma.c

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/*
 * Copyright (c) 2005-2006 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/completion.h>
#include <linux/file.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/module.h>

#include <rdma/rdma_user_cm.h>
#include <rdma/ib_marshall.h>
#include <rdma/rdma_cm.h>
#include <rdma/rdma_cm_ib.h>

MODULE_AUTHOR("Sean Hefty");
MODULE_DESCRIPTION("RDMA Userspace Connection Manager Access");
MODULE_LICENSE("Dual BSD/GPL");

static unsigned int max_backlog = 1024;

static struct ctl_table_header *ucma_ctl_table_hdr;
static ctl_table ucma_ctl_table[] = {
    {
        .procname   = "max_backlog",
        .data       = &max_backlog,
        .maxlen     = sizeof max_backlog,
        .mode       = 0644,
        .proc_handler   = proc_dointvec,
    },
    { }
};

struct ucma_file {
    struct mutex        mut;
    struct file     *filp;
    struct list_head    ctx_list;
    struct list_head    event_list;
    wait_queue_head_t   poll_wait;
};

struct ucma_context {
    int         id;
    struct completion   comp;
    atomic_t        ref;
    int         events_reported;
    int         backlog;

    struct ucma_file    *file;
    struct rdma_cm_id   *cm_id;
    u64         uid;

    struct list_head    list;
    struct list_head    mc_list;
};

struct ucma_multicast {
    struct ucma_context *ctx;
    int         id;
    int         events_reported;

    u64         uid;
    struct list_head    list;
    struct sockaddr_storage addr;
};

struct ucma_event {
    struct ucma_context *ctx;
    struct ucma_multicast   *mc;
    struct list_head    list;
    struct rdma_cm_id   *cm_id;
    struct rdma_ucm_event_resp resp;
};

static DEFINE_MUTEX(mut);
static DEFINE_IDR(ctx_idr);
static DEFINE_IDR(multicast_idr);

static inline struct ucma_context *_ucma_find_context(int id,
                              struct ucma_file *file)
{
    struct ucma_context *ctx;

    ctx = idr_find(&ctx_idr, id);
    if (!ctx)
        ctx = ERR_PTR(-ENOENT);
    else if (ctx->file != file)
        ctx = ERR_PTR(-EINVAL);
    return ctx;
}

static struct ucma_context *ucma_get_ctx(struct ucma_file *file, int id)
{
    struct ucma_context *ctx;

    mutex_lock(&mut);
    ctx = _ucma_find_context(id, file);
    if (!IS_ERR(ctx))
        atomic_inc(&ctx->ref);
    mutex_unlock(&mut);
    return ctx;
}

static void ucma_put_ctx(struct ucma_context *ctx)
{
    if (atomic_dec_and_test(&ctx->ref))
        complete(&ctx->comp);
}

static struct ucma_context *ucma_alloc_ctx(struct ucma_file *file)
{
    struct ucma_context *ctx;
    int ret;

    ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
    if (!ctx)
        return NULL;

    atomic_set(&ctx->ref, 1);
    init_completion(&ctx->comp);
    INIT_LIST_HEAD(&ctx->mc_list);
    ctx->file = file;

    do {
        ret = idr_pre_get(&ctx_idr, GFP_KERNEL);
        if (!ret)
            goto error;

        mutex_lock(&mut);
        ret = idr_get_new(&ctx_idr, ctx, &ctx->id);
        mutex_unlock(&mut);
    } while (ret == -EAGAIN);

    if (ret)
        goto error;

    list_add_tail(&ctx->list, &file->ctx_list);
    return ctx;

error:
    kfree(ctx);
    return NULL;
}

static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx)
{
    struct ucma_multicast *mc;
    int ret;

    mc = kzalloc(sizeof(*mc), GFP_KERNEL);
    if (!mc)
        return NULL;

    do {
        ret = idr_pre_get(&multicast_idr, GFP_KERNEL);
        if (!ret)
            goto error;

        mutex_lock(&mut);
        ret = idr_get_new(&multicast_idr, mc, &mc->id);
        mutex_unlock(&mut);
    } while (ret == -EAGAIN);

    if (ret)
        goto error;

    mc->ctx = ctx;
    list_add_tail(&mc->list, &ctx->mc_list);
    return mc;

error:
    kfree(mc);
    return NULL;
}

static void ucma_copy_conn_event(struct rdma_ucm_conn_param *dst,
                 struct rdma_conn_param *src)
{
    if (src->private_data_len)
        memcpy(dst->private_data, src->private_data,
               src->private_data_len);
    dst->private_data_len = src->private_data_len;
    dst->responder_resources =src->responder_resources;
    dst->initiator_depth = src->initiator_depth;
    dst->flow_control = src->flow_control;
    dst->retry_count = src->retry_count;
    dst->rnr_retry_count = src->rnr_retry_count;
    dst->srq = src->srq;
    dst->qp_num = src->qp_num;
}

static void ucma_copy_ud_event(struct rdma_ucm_ud_param *dst,
                   struct rdma_ud_param *src)
{
    if (src->private_data_len)
        memcpy(dst->private_data, src->private_data,
               src->private_data_len);
    dst->private_data_len = src->private_data_len;
    ib_copy_ah_attr_to_user(&dst->ah_attr, &src->ah_attr);
    dst->qp_num = src->qp_num;
    dst->qkey = src->qkey;
}

static void ucma_set_event_context(struct ucma_context *ctx,
                   struct rdma_cm_event *event,
                   struct ucma_event *uevent)
{
    uevent->ctx = ctx;
    switch (event->event) {
    case RDMA_CM_EVENT_MULTICAST_JOIN:
    case RDMA_CM_EVENT_MULTICAST_ERROR:
        uevent->mc = (struct ucma_multicast *)
                 event->param.ud.private_data;
        uevent->resp.uid = uevent->mc->uid;
        uevent->resp.id = uevent->mc->id;
        break;
    default:
        uevent->resp.uid = ctx->uid;
        uevent->resp.id = ctx->id;
        break;
    }
}

static int ucma_event_handler(struct rdma_cm_id *cm_id,
                  struct rdma_cm_event *event)
{
    struct ucma_event *uevent;
    struct ucma_context *ctx = cm_id->context;
    int ret = 0;

    uevent = kzalloc(sizeof(*uevent), GFP_KERNEL);
    if (!uevent)
        return event->event == RDMA_CM_EVENT_CONNECT_REQUEST;

    mutex_lock(&ctx->file->mut);
    uevent->cm_id = cm_id;
    ucma_set_event_context(ctx, event, uevent);
    uevent->resp.event = event->event;
    uevent->resp.status = event->status;
    if (cm_id->qp_type == IB_QPT_UD)
        ucma_copy_ud_event(&uevent->resp.param.ud, &event->param.ud);
    else
        ucma_copy_conn_event(&uevent->resp.param.conn,
                     &event->param.conn);

    if (event->event == RDMA_CM_EVENT_CONNECT_REQUEST) {
        if (!ctx->backlog) {
            ret = -ENOMEM;
            kfree(uevent);
            goto out;
        }
        ctx->backlog--;
    } else if (!ctx->uid) {
        /*
         * We ignore events for new connections until userspace has set
         * their context.  This can only happen if an error occurs on a
         * new connection before the user accepts it.  This is okay,
         * since the accept will just fail later.
         */
        kfree(uevent);
        goto out;
    }

    list_add_tail(&uevent->list, &ctx->file->event_list);
    wake_up_interruptible(&ctx->file->poll_wait);
out:
    mutex_unlock(&ctx->file->mut);
    return ret;
}

static ssize_t ucma_get_event(struct ucma_file *file, const char __user *inbuf,
                  int in_len, int out_len)
{
    struct ucma_context *ctx;
    struct rdma_ucm_get_event cmd;
    struct ucma_event *uevent;
    int ret = 0;

    if (out_len < sizeof uevent->resp)
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    mutex_lock(&file->mut);
    while (list_empty(&file->event_list)) {
        mutex_unlock(&file->mut);

        if (file->filp->f_flags & O_NONBLOCK)
            return -EAGAIN;

        if (wait_event_interruptible(file->poll_wait,
                         !list_empty(&file->event_list)))
            return -ERESTARTSYS;

        mutex_lock(&file->mut);
    }

    uevent = list_entry(file->event_list.next, struct ucma_event, list);

    if (uevent->resp.event == RDMA_CM_EVENT_CONNECT_REQUEST) {
        ctx = ucma_alloc_ctx(file);
        if (!ctx) {
            ret = -ENOMEM;
            goto done;
        }
        uevent->ctx->backlog++;
        ctx->cm_id = uevent->cm_id;
        ctx->cm_id->context = ctx;
        uevent->resp.id = ctx->id;
    }

    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &uevent->resp, sizeof uevent->resp)) {
        ret = -EFAULT;
        goto done;
    }

    list_del(&uevent->list);
    uevent->ctx->events_reported++;
    if (uevent->mc)
        uevent->mc->events_reported++;
    kfree(uevent);
done:
    mutex_unlock(&file->mut);
    return ret;
}

static int ucma_get_qp_type(struct rdma_ucm_create_id *cmd, enum ib_qp_type *qp_type)
{
    switch (cmd->ps) {
    case RDMA_PS_TCP:
        *qp_type = IB_QPT_RC;
        return 0;
    case RDMA_PS_UDP:
    case RDMA_PS_IPOIB:
        *qp_type = IB_QPT_UD;
        return 0;
    case RDMA_PS_IB:
        *qp_type = cmd->qp_type;
        return 0;
    default:
        return -EINVAL;
    }
}

static ssize_t ucma_create_id(struct ucma_file *file, const char __user *inbuf,
                  int in_len, int out_len)
{
    struct rdma_ucm_create_id cmd;
    struct rdma_ucm_create_id_resp resp;
    struct ucma_context *ctx;
    enum ib_qp_type qp_type;
    int ret;

    if (out_len < sizeof(resp))
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ret = ucma_get_qp_type(&cmd, &qp_type);
    if (ret)
        return ret;

    mutex_lock(&file->mut);
    ctx = ucma_alloc_ctx(file);
    mutex_unlock(&file->mut);
    if (!ctx)
        return -ENOMEM;

    ctx->uid = cmd.uid;
    ctx->cm_id = rdma_create_id(ucma_event_handler, ctx, cmd.ps, qp_type);
    if (IS_ERR(ctx->cm_id)) {
        ret = PTR_ERR(ctx->cm_id);
        goto err1;
    }

    resp.id = ctx->id;
    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp))) {
        ret = -EFAULT;
        goto err2;
    }
    return 0;

err2:
    rdma_destroy_id(ctx->cm_id);
err1:
    mutex_lock(&mut);
    idr_remove(&ctx_idr, ctx->id);
    mutex_unlock(&mut);
    kfree(ctx);
    return ret;
}

static void ucma_cleanup_multicast(struct ucma_context *ctx)
{
    struct ucma_multicast *mc, *tmp;

    mutex_lock(&mut);
    list_for_each_entry_safe(mc, tmp, &ctx->mc_list, list) {
        list_del(&mc->list);
        idr_remove(&multicast_idr, mc->id);
        kfree(mc);
    }
    mutex_unlock(&mut);
}

static void ucma_cleanup_mc_events(struct ucma_multicast *mc)
{
    struct ucma_event *uevent, *tmp;

    list_for_each_entry_safe(uevent, tmp, &mc->ctx->file->event_list, list) {
        if (uevent->mc != mc)
            continue;

        list_del(&uevent->list);
        kfree(uevent);
    }
}

/*
 * We cannot hold file->mut when calling rdma_destroy_id() or we can
 * deadlock.  We also acquire file->mut in ucma_event_handler(), and
 * rdma_destroy_id() will wait until all callbacks have completed.
 */
static int ucma_free_ctx(struct ucma_context *ctx)
{
    int events_reported;
    struct ucma_event *uevent, *tmp;
    LIST_HEAD(list);

    /* No new events will be generated after destroying the id. */
    rdma_destroy_id(ctx->cm_id);

    ucma_cleanup_multicast(ctx);

    /* Cleanup events not yet reported to the user. */
    mutex_lock(&ctx->file->mut);
    list_for_each_entry_safe(uevent, tmp, &ctx->file->event_list, list) {
        if (uevent->ctx == ctx)
            list_move_tail(&uevent->list, &list);
    }
    list_del(&ctx->list);
    mutex_unlock(&ctx->file->mut);

    list_for_each_entry_safe(uevent, tmp, &list, list) {
        list_del(&uevent->list);
        if (uevent->resp.event == RDMA_CM_EVENT_CONNECT_REQUEST)
            rdma_destroy_id(uevent->cm_id);
        kfree(uevent);
    }

    events_reported = ctx->events_reported;
    kfree(ctx);
    return events_reported;
}

static ssize_t ucma_destroy_id(struct ucma_file *file, const char __user *inbuf,
                   int in_len, int out_len)
{
    struct rdma_ucm_destroy_id cmd;
    struct rdma_ucm_destroy_id_resp resp;
    struct ucma_context *ctx;
    int ret = 0;

    if (out_len < sizeof(resp))
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    mutex_lock(&mut);
    ctx = _ucma_find_context(cmd.id, file);
    if (!IS_ERR(ctx))
        idr_remove(&ctx_idr, ctx->id);
    mutex_unlock(&mut);

    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ucma_put_ctx(ctx);
    wait_for_completion(&ctx->comp);
    resp.events_reported = ucma_free_ctx(ctx);

    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp)))
        ret = -EFAULT;

    return ret;
}

static ssize_t ucma_bind_addr(struct ucma_file *file, const char __user *inbuf,
                  int in_len, int out_len)
{
    struct rdma_ucm_bind_addr cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ret = rdma_bind_addr(ctx->cm_id, (struct sockaddr *) &cmd.addr);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_resolve_addr(struct ucma_file *file,
                 const char __user *inbuf,
                 int in_len, int out_len)
{
    struct rdma_ucm_resolve_addr cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ret = rdma_resolve_addr(ctx->cm_id, (struct sockaddr *) &cmd.src_addr,
                (struct sockaddr *) &cmd.dst_addr,
                cmd.timeout_ms);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_resolve_route(struct ucma_file *file,
                  const char __user *inbuf,
                  int in_len, int out_len)
{
    struct rdma_ucm_resolve_route cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ret = rdma_resolve_route(ctx->cm_id, cmd.timeout_ms);
    ucma_put_ctx(ctx);
    return ret;
}

static void ucma_copy_ib_route(struct rdma_ucm_query_route_resp *resp,
                   struct rdma_route *route)
{
    struct rdma_dev_addr *dev_addr;

    resp->num_paths = route->num_paths;
    switch (route->num_paths) {
    case 0:
        dev_addr = &route->addr.dev_addr;
        rdma_addr_get_dgid(dev_addr,
                   (union ib_gid *) &resp->ib_route[0].dgid);
        rdma_addr_get_sgid(dev_addr,
                   (union ib_gid *) &resp->ib_route[0].sgid);
        resp->ib_route[0].pkey = cpu_to_be16(ib_addr_get_pkey(dev_addr));
        break;
    case 2:
        ib_copy_path_rec_to_user(&resp->ib_route[1],
                     &route->path_rec[1]);
        /* fall through */
    case 1:
        ib_copy_path_rec_to_user(&resp->ib_route[0],
                     &route->path_rec[0]);
        break;
    default:
        break;
    }
}

static void ucma_copy_iboe_route(struct rdma_ucm_query_route_resp *resp,
                 struct rdma_route *route)
{
    struct rdma_dev_addr *dev_addr;
    struct net_device *dev;
    u16 vid = 0;

    resp->num_paths = route->num_paths;
    switch (route->num_paths) {
    case 0:
        dev_addr = &route->addr.dev_addr;
        dev = dev_get_by_index(&init_net, dev_addr->bound_dev_if);
            if (dev) {
                vid = rdma_vlan_dev_vlan_id(dev);
                dev_put(dev);
            }

        iboe_mac_vlan_to_ll((union ib_gid *) &resp->ib_route[0].dgid,
                    dev_addr->dst_dev_addr, vid);
        iboe_addr_get_sgid(dev_addr,
                   (union ib_gid *) &resp->ib_route[0].sgid);
        resp->ib_route[0].pkey = cpu_to_be16(0xffff);
        break;
    case 2:
        ib_copy_path_rec_to_user(&resp->ib_route[1],
                     &route->path_rec[1]);
        /* fall through */
    case 1:
        ib_copy_path_rec_to_user(&resp->ib_route[0],
                     &route->path_rec[0]);
        break;
    default:
        break;
    }
}

static void ucma_copy_iw_route(struct rdma_ucm_query_route_resp *resp,
                   struct rdma_route *route)
{
    struct rdma_dev_addr *dev_addr;

    dev_addr = &route->addr.dev_addr;
    rdma_addr_get_dgid(dev_addr, (union ib_gid *) &resp->ib_route[0].dgid);
    rdma_addr_get_sgid(dev_addr, (union ib_gid *) &resp->ib_route[0].sgid);
}

static ssize_t ucma_query_route(struct ucma_file *file,
                const char __user *inbuf,
                int in_len, int out_len)
{
    struct rdma_ucm_query_route cmd;
    struct rdma_ucm_query_route_resp resp;
    struct ucma_context *ctx;
    struct sockaddr *addr;
    int ret = 0;

    if (out_len < sizeof(resp))
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    memset(&resp, 0, sizeof resp);
    addr = (struct sockaddr *) &ctx->cm_id->route.addr.src_addr;
    memcpy(&resp.src_addr, addr, addr->sa_family == AF_INET ?
                     sizeof(struct sockaddr_in) :
                     sizeof(struct sockaddr_in6));
    addr = (struct sockaddr *) &ctx->cm_id->route.addr.dst_addr;
    memcpy(&resp.dst_addr, addr, addr->sa_family == AF_INET ?
                     sizeof(struct sockaddr_in) :
                     sizeof(struct sockaddr_in6));
    if (!ctx->cm_id->device)
        goto out;

    resp.node_guid = (__force __u64) ctx->cm_id->device->node_guid;
    resp.port_num = ctx->cm_id->port_num;
    switch (rdma_node_get_transport(ctx->cm_id->device->node_type)) {
    case RDMA_TRANSPORT_IB:
        switch (rdma_port_get_link_layer(ctx->cm_id->device,
            ctx->cm_id->port_num)) {
        case IB_LINK_LAYER_INFINIBAND:
            ucma_copy_ib_route(&resp, &ctx->cm_id->route);
            break;
        case IB_LINK_LAYER_ETHERNET:
            ucma_copy_iboe_route(&resp, &ctx->cm_id->route);
            break;
        default:
            break;
        }
        break;
    case RDMA_TRANSPORT_IWARP:
        ucma_copy_iw_route(&resp, &ctx->cm_id->route);
        break;
    default:
        break;
    }

out:
    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp)))
        ret = -EFAULT;

    ucma_put_ctx(ctx);
    return ret;
}

static void ucma_copy_conn_param(struct rdma_conn_param *dst,
                 struct rdma_ucm_conn_param *src)
{
    dst->private_data = src->private_data;
    dst->private_data_len = src->private_data_len;
    dst->responder_resources =src->responder_resources;
    dst->initiator_depth = src->initiator_depth;
    dst->flow_control = src->flow_control;
    dst->retry_count = src->retry_count;
    dst->rnr_retry_count = src->rnr_retry_count;
    dst->srq = src->srq;
    dst->qp_num = src->qp_num;
}

static ssize_t ucma_connect(struct ucma_file *file, const char __user *inbuf,
                int in_len, int out_len)
{
    struct rdma_ucm_connect cmd;
    struct rdma_conn_param conn_param;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    if (!cmd.conn_param.valid)
        return -EINVAL;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ucma_copy_conn_param(&conn_param, &cmd.conn_param);
    ret = rdma_connect(ctx->cm_id, &conn_param);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_listen(struct ucma_file *file, const char __user *inbuf,
               int in_len, int out_len)
{
    struct rdma_ucm_listen cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ctx->backlog = cmd.backlog > 0 && cmd.backlog < max_backlog ?
               cmd.backlog : max_backlog;
    ret = rdma_listen(ctx->cm_id, ctx->backlog);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_accept(struct ucma_file *file, const char __user *inbuf,
               int in_len, int out_len)
{
    struct rdma_ucm_accept cmd;
    struct rdma_conn_param conn_param;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    if (cmd.conn_param.valid) {
        ucma_copy_conn_param(&conn_param, &cmd.conn_param);
        mutex_lock(&file->mut);
        ret = rdma_accept(ctx->cm_id, &conn_param);
        if (!ret)
            ctx->uid = cmd.uid;
        mutex_unlock(&file->mut);
    } else
        ret = rdma_accept(ctx->cm_id, NULL);

    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_reject(struct ucma_file *file, const char __user *inbuf,
               int in_len, int out_len)
{
    struct rdma_ucm_reject cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ret = rdma_reject(ctx->cm_id, cmd.private_data, cmd.private_data_len);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_disconnect(struct ucma_file *file, const char __user *inbuf,
                   int in_len, int out_len)
{
    struct rdma_ucm_disconnect cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ret = rdma_disconnect(ctx->cm_id);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_init_qp_attr(struct ucma_file *file,
                 const char __user *inbuf,
                 int in_len, int out_len)
{
    struct rdma_ucm_init_qp_attr cmd;
    struct ib_uverbs_qp_attr resp;
    struct ucma_context *ctx;
    struct ib_qp_attr qp_attr;
    int ret;

    if (out_len < sizeof(resp))
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    resp.qp_attr_mask = 0;
    memset(&qp_attr, 0, sizeof qp_attr);
    qp_attr.qp_state = cmd.qp_state;
    ret = rdma_init_qp_attr(ctx->cm_id, &qp_attr, &resp.qp_attr_mask);
    if (ret)
        goto out;

    ib_copy_qp_attr_to_user(&resp, &qp_attr);
    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp)))
        ret = -EFAULT;

out:
    ucma_put_ctx(ctx);
    return ret;
}

static int ucma_set_option_id(struct ucma_context *ctx, int optname,
                  void *optval, size_t optlen)
{
    int ret = 0;

    switch (optname) {
    case RDMA_OPTION_ID_TOS:
        if (optlen != sizeof(u8)) {
            ret = -EINVAL;
            break;
        }
        rdma_set_service_type(ctx->cm_id, *((u8 *) optval));
        break;
    case RDMA_OPTION_ID_REUSEADDR:
        if (optlen != sizeof(int)) {
            ret = -EINVAL;
            break;
        }
        ret = rdma_set_reuseaddr(ctx->cm_id, *((int *) optval) ? 1 : 0);
        break;
    case RDMA_OPTION_ID_AFONLY:
        if (optlen != sizeof(int)) {
            ret = -EINVAL;
            break;
        }
        ret = rdma_set_afonly(ctx->cm_id, *((int *) optval) ? 1 : 0);
        break;
    default:
        ret = -ENOSYS;
    }

    return ret;
}

static int ucma_set_ib_path(struct ucma_context *ctx,
                struct ib_path_rec_data *path_data, size_t optlen)
{
    struct ib_sa_path_rec sa_path;
    struct rdma_cm_event event;
    int ret;

    if (optlen % sizeof(*path_data))
        return -EINVAL;

    for (; optlen; optlen -= sizeof(*path_data), path_data++) {
        if (path_data->flags == (IB_PATH_GMP | IB_PATH_PRIMARY |
                     IB_PATH_BIDIRECTIONAL))
            break;
    }

    if (!optlen)
        return -EINVAL;

    ib_sa_unpack_path(path_data->path_rec, &sa_path);
    ret = rdma_set_ib_paths(ctx->cm_id, &sa_path, 1);
    if (ret)
        return ret;

    memset(&event, 0, sizeof event);
    event.event = RDMA_CM_EVENT_ROUTE_RESOLVED;
    return ucma_event_handler(ctx->cm_id, &event);
}

static int ucma_set_option_ib(struct ucma_context *ctx, int optname,
                  void *optval, size_t optlen)
{
    int ret;

    switch (optname) {
    case RDMA_OPTION_IB_PATH:
        ret = ucma_set_ib_path(ctx, optval, optlen);
        break;
    default:
        ret = -ENOSYS;
    }

    return ret;
}

static int ucma_set_option_level(struct ucma_context *ctx, int level,
                 int optname, void *optval, size_t optlen)
{
    int ret;

    switch (level) {
    case RDMA_OPTION_ID:
        ret = ucma_set_option_id(ctx, optname, optval, optlen);
        break;
    case RDMA_OPTION_IB:
        ret = ucma_set_option_ib(ctx, optname, optval, optlen);
        break;
    default:
        ret = -ENOSYS;
    }

    return ret;
}

static ssize_t ucma_set_option(struct ucma_file *file, const char __user *inbuf,
                   int in_len, int out_len)
{
    struct rdma_ucm_set_option cmd;
    struct ucma_context *ctx;
    void *optval;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    optval = memdup_user((void __user *) (unsigned long) cmd.optval,
                 cmd.optlen);
    if (IS_ERR(optval)) {
        ret = PTR_ERR(optval);
        goto out;
    }

    ret = ucma_set_option_level(ctx, cmd.level, cmd.optname, optval,
                    cmd.optlen);
    kfree(optval);

out:
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_notify(struct ucma_file *file, const char __user *inbuf,
               int in_len, int out_len)
{
    struct rdma_ucm_notify cmd;
    struct ucma_context *ctx;
    int ret;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    ret = rdma_notify(ctx->cm_id, (enum ib_event_type) cmd.event);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_join_multicast(struct ucma_file *file,
                   const char __user *inbuf,
                   int in_len, int out_len)
{
    struct rdma_ucm_join_mcast cmd;
    struct rdma_ucm_create_id_resp resp;
    struct ucma_context *ctx;
    struct ucma_multicast *mc;
    int ret;

    if (out_len < sizeof(resp))
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    ctx = ucma_get_ctx(file, cmd.id);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    mutex_lock(&file->mut);
    mc = ucma_alloc_multicast(ctx);
    if (!mc) {
        ret = -ENOMEM;
        goto err1;
    }

    mc->uid = cmd.uid;
    memcpy(&mc->addr, &cmd.addr, sizeof cmd.addr);
    ret = rdma_join_multicast(ctx->cm_id, (struct sockaddr *) &mc->addr, mc);
    if (ret)
        goto err2;

    resp.id = mc->id;
    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp))) {
        ret = -EFAULT;
        goto err3;
    }

    mutex_unlock(&file->mut);
    ucma_put_ctx(ctx);
    return 0;

err3:
    rdma_leave_multicast(ctx->cm_id, (struct sockaddr *) &mc->addr);
    ucma_cleanup_mc_events(mc);
err2:
    mutex_lock(&mut);
    idr_remove(&multicast_idr, mc->id);
    mutex_unlock(&mut);
    list_del(&mc->list);
    kfree(mc);
err1:
    mutex_unlock(&file->mut);
    ucma_put_ctx(ctx);
    return ret;
}

static ssize_t ucma_leave_multicast(struct ucma_file *file,
                    const char __user *inbuf,
                    int in_len, int out_len)
{
    struct rdma_ucm_destroy_id cmd;
    struct rdma_ucm_destroy_id_resp resp;
    struct ucma_multicast *mc;
    int ret = 0;

    if (out_len < sizeof(resp))
        return -ENOSPC;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    mutex_lock(&mut);
    mc = idr_find(&multicast_idr, cmd.id);
    if (!mc)
        mc = ERR_PTR(-ENOENT);
    else if (mc->ctx->file != file)
        mc = ERR_PTR(-EINVAL);
    else {
        idr_remove(&multicast_idr, mc->id);
        atomic_inc(&mc->ctx->ref);
    }
    mutex_unlock(&mut);

    if (IS_ERR(mc)) {
        ret = PTR_ERR(mc);
        goto out;
    }

    rdma_leave_multicast(mc->ctx->cm_id, (struct sockaddr *) &mc->addr);
    mutex_lock(&mc->ctx->file->mut);
    ucma_cleanup_mc_events(mc);
    list_del(&mc->list);
    mutex_unlock(&mc->ctx->file->mut);

    ucma_put_ctx(mc->ctx);
    resp.events_reported = mc->events_reported;
    kfree(mc);

    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp)))
        ret = -EFAULT;
out:
    return ret;
}

static void ucma_lock_files(struct ucma_file *file1, struct ucma_file *file2)
{
    /* Acquire mutex's based on pointer comparison to prevent deadlock. */
    if (file1 < file2) {
        mutex_lock(&file1->mut);
        mutex_lock(&file2->mut);
    } else {
        mutex_lock(&file2->mut);
        mutex_lock(&file1->mut);
    }
}

static void ucma_unlock_files(struct ucma_file *file1, struct ucma_file *file2)
{
    if (file1 < file2) {
        mutex_unlock(&file2->mut);
        mutex_unlock(&file1->mut);
    } else {
        mutex_unlock(&file1->mut);
        mutex_unlock(&file2->mut);
    }
}

static void ucma_move_events(struct ucma_context *ctx, struct ucma_file *file)
{
    struct ucma_event *uevent, *tmp;

    list_for_each_entry_safe(uevent, tmp, &ctx->file->event_list, list)
        if (uevent->ctx == ctx)
            list_move_tail(&uevent->list, &file->event_list);
}

static ssize_t ucma_migrate_id(struct ucma_file *new_file,
                   const char __user *inbuf,
                   int in_len, int out_len)
{
    struct rdma_ucm_migrate_id cmd;
    struct rdma_ucm_migrate_resp resp;
    struct ucma_context *ctx;
    struct fd f;
    struct ucma_file *cur_file;
    int ret = 0;

    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
        return -EFAULT;

    /* Get current fd to protect against it being closed */
    f = fdget(cmd.fd);
    if (!f.file)
        return -ENOENT;

    /* Validate current fd and prevent destruction of id. */
    ctx = ucma_get_ctx(f.file->private_data, cmd.id);
    if (IS_ERR(ctx)) {
        ret = PTR_ERR(ctx);
        goto file_put;
    }

    cur_file = ctx->file;
    if (cur_file == new_file) {
        resp.events_reported = ctx->events_reported;
        goto response;
    }

    /*
     * Migrate events between fd's, maintaining order, and avoiding new
     * events being added before existing events.
     */
    ucma_lock_files(cur_file, new_file);
    mutex_lock(&mut);

    list_move_tail(&ctx->list, &new_file->ctx_list);
    ucma_move_events(ctx, new_file);
    ctx->file = new_file;
    resp.events_reported = ctx->events_reported;

    mutex_unlock(&mut);
    ucma_unlock_files(cur_file, new_file);

response:
    if (copy_to_user((void __user *)(unsigned long)cmd.response,
             &resp, sizeof(resp)))
        ret = -EFAULT;

    ucma_put_ctx(ctx);
file_put:
    fdput(f);
    return ret;
}

static ssize_t (*ucma_cmd_table[])(struct ucma_file *file,
                   const char __user *inbuf,
                   int in_len, int out_len) = {
    [RDMA_USER_CM_CMD_CREATE_ID]    = ucma_create_id,
    [RDMA_USER_CM_CMD_DESTROY_ID]   = ucma_destroy_id,
    [RDMA_USER_CM_CMD_BIND_ADDR]    = ucma_bind_addr,
    [RDMA_USER_CM_CMD_RESOLVE_ADDR] = ucma_resolve_addr,
    [RDMA_USER_CM_CMD_RESOLVE_ROUTE]= ucma_resolve_route,
    [RDMA_USER_CM_CMD_QUERY_ROUTE]  = ucma_query_route,
    [RDMA_USER_CM_CMD_CONNECT]  = ucma_connect,
    [RDMA_USER_CM_CMD_LISTEN]   = ucma_listen,
    [RDMA_USER_CM_CMD_ACCEPT]   = ucma_accept,
    [RDMA_USER_CM_CMD_REJECT]   = ucma_reject,
    [RDMA_USER_CM_CMD_DISCONNECT]   = ucma_disconnect,
    [RDMA_USER_CM_CMD_INIT_QP_ATTR] = ucma_init_qp_attr,
    [RDMA_USER_CM_CMD_GET_EVENT]    = ucma_get_event,
    [RDMA_USER_CM_CMD_GET_OPTION]   = NULL,
    [RDMA_USER_CM_CMD_SET_OPTION]   = ucma_set_option,
    [RDMA_USER_CM_CMD_NOTIFY]   = ucma_notify,
    [RDMA_USER_CM_CMD_JOIN_MCAST]   = ucma_join_multicast,
    [RDMA_USER_CM_CMD_LEAVE_MCAST]  = ucma_leave_multicast,
    [RDMA_USER_CM_CMD_MIGRATE_ID]   = ucma_migrate_id
};

static ssize_t ucma_write(struct file *filp, const char __user *buf,
              size_t len, loff_t *pos)
{
    struct ucma_file *file = filp->private_data;
    struct rdma_ucm_cmd_hdr hdr;
    ssize_t ret;

    if (len < sizeof(hdr))
        return -EINVAL;

    if (copy_from_user(&hdr, buf, sizeof(hdr)))
        return -EFAULT;

    if (hdr.cmd >= ARRAY_SIZE(ucma_cmd_table))
        return -EINVAL;

    if (hdr.in + sizeof(hdr) > len)
        return -EINVAL;

    if (!ucma_cmd_table[hdr.cmd])
        return -ENOSYS;

    ret = ucma_cmd_table[hdr.cmd](file, buf + sizeof(hdr), hdr.in, hdr.out);
    if (!ret)
        ret = len;

    return ret;
}

static unsigned int ucma_poll(struct file *filp, struct poll_table_struct *wait)
{
    struct ucma_file *file = filp->private_data;
    unsigned int mask = 0;

    poll_wait(filp, &file->poll_wait, wait);

    if (!list_empty(&file->event_list))
        mask = POLLIN | POLLRDNORM;

    return mask;
}

/*
 * ucma_open() does not need the BKL:
 *
 *  - no global state is referred to;
 *  - there is no ioctl method to race against;
 *  - no further module initialization is required for open to work
 *    after the device is registered.
 */
static int ucma_open(struct inode *inode, struct file *filp)
{
    struct ucma_file *file;

    file = kmalloc(sizeof *file, GFP_KERNEL);
    if (!file)
        return -ENOMEM;

    INIT_LIST_HEAD(&file->event_list);
    INIT_LIST_HEAD(&file->ctx_list);
    init_waitqueue_head(&file->poll_wait);
    mutex_init(&file->mut);

    filp->private_data = file;
    file->filp = filp;

    return nonseekable_open(inode, filp);
}

static int ucma_close(struct inode *inode, struct file *filp)
{
    struct ucma_file *file = filp->private_data;
    struct ucma_context *ctx, *tmp;

    mutex_lock(&file->mut);
    list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) {
        mutex_unlock(&file->mut);

        mutex_lock(&mut);
        idr_remove(&ctx_idr, ctx->id);
        mutex_unlock(&mut);

        ucma_free_ctx(ctx);
        mutex_lock(&file->mut);
    }
    mutex_unlock(&file->mut);
    kfree(file);
    return 0;
}

static const struct file_operations ucma_fops = {
    .owner   = THIS_MODULE,
    .open    = ucma_open,
    .release = ucma_close,
    .write   = ucma_write,
    .poll    = ucma_poll,
    .llseek  = no_llseek,
};

static struct miscdevice ucma_misc = {
    .minor      = MISC_DYNAMIC_MINOR,
    .name       = "rdma_cm",
    .nodename   = "infiniband/rdma_cm",
    .mode       = 0666,
    .fops       = &ucma_fops,
};

static ssize_t show_abi_version(struct device *dev,
                struct device_attribute *attr,
                char *buf)
{
    return sprintf(buf, "%d\n", RDMA_USER_CM_ABI_VERSION);
}
static DEVICE_ATTR(abi_version, S_IRUGO, show_abi_version, NULL);

static int __init ucma_init(void)
{
    int ret;

    ret = misc_register(&ucma_misc);
    if (ret)
        return ret;

    ret = device_create_file(ucma_misc.this_device, &dev_attr_abi_version);
    if (ret) {
        printk(KERN_ERR "rdma_ucm: couldn't create abi_version attr\n");
        goto err1;
    }

    ucma_ctl_table_hdr = register_net_sysctl(&init_net, "net/rdma_ucm", ucma_ctl_table);
    if (!ucma_ctl_table_hdr) {
        printk(KERN_ERR "rdma_ucm: couldn't register sysctl paths\n");
        ret = -ENOMEM;
        goto err2;
    }
    return 0;
err2:
    device_remove_file(ucma_misc.this_device, &dev_attr_abi_version);
err1:
    misc_deregister(&ucma_misc);
    return ret;
}

static void __exit ucma_cleanup(void)
{
    unregister_net_sysctl_table(ucma_ctl_table_hdr);
    device_remove_file(ucma_misc.this_device, &dev_attr_abi_version);
    misc_deregister(&ucma_misc);
    idr_destroy(&ctx_idr);
}

module_init(ucma_init);
module_exit(ucma_cleanup);