/*
 * Copyright (c) 2004 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Voltaire, Inc. All rights reserved.
 * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
 * Copyright (c) 2008 Cisco. 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.
 */

#define pr_fmt(fmt) "user_mad: " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/dma-mapping.h>
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/kref.h>
#include <linux/compat.h>
#include <linux/sched.h>
#include <linux/semaphore.h>
#include <linux/slab.h>

#include <asm/uaccess.h>

#include <rdma/ib_mad.h>
#include <rdma/ib_user_mad.h>

MODULE_AUTHOR("Roland Dreier");
MODULE_DESCRIPTION("InfiniBand userspace MAD packet access");
MODULE_LICENSE("Dual BSD/GPL");

enum {
        IB_UMAD_MAX_PORTS  = 64,
        IB_UMAD_MAX_AGENTS = 32,

        IB_UMAD_MAJOR      = 231,
        IB_UMAD_MINOR_BASE = 0
};

/*
 * Our lifetime rules for these structs are the following:
 * device special file is opened, we take a reference on the
 * ib_umad_port's struct ib_umad_device. We drop these
 * references in the corresponding close().
 *
 * In addition to references coming from open character devices, there
 * is one more reference to each ib_umad_device representing the
 * module's reference taken when allocating the ib_umad_device in
 * ib_umad_add_one().
 *
 * When destroying an ib_umad_device, we drop the module's reference.
 */

struct ib_umad_port {
        struct cdev           cdev;
        struct device         *dev;

        struct cdev           sm_cdev;
        struct device         *sm_dev;
        struct semaphore       sm_sem;

        struct mutex           file_mutex;
        struct list_head       file_list;

        struct ib_device      *ib_dev;
        struct ib_umad_device *umad_dev;
        int                    dev_num;
        u8                     port_num;
};

struct ib_umad_device {
        struct kobject       kobj;
        struct ib_umad_port  port[0];
};

struct ib_umad_file {
        struct mutex            mutex;
        struct ib_umad_port    *port;
        struct list_head        recv_list;
        struct list_head        send_list;
        struct list_head        port_list;
        spinlock_t              send_lock;
        wait_queue_head_t       recv_wait;
        struct ib_mad_agent    *agent[IB_UMAD_MAX_AGENTS];
        int                     agents_dead;
        u8                      use_pkey_index;
        u8                      already_used;
};

struct ib_umad_packet {
        struct ib_mad_send_buf *msg;
        struct ib_mad_recv_wc  *recv_wc;
        struct list_head   list;
        int                length;
        struct ib_user_mad mad;
};

static struct class *umad_class;

static const dev_t base_dev = MKDEV(IB_UMAD_MAJOR, IB_UMAD_MINOR_BASE);

static DEFINE_SPINLOCK(port_lock);
static DECLARE_BITMAP(dev_map, IB_UMAD_MAX_PORTS);

static void ib_umad_add_one(struct ib_device *device);
static void ib_umad_remove_one(struct ib_device *device);

static void ib_umad_release_dev(struct kobject *kobj)
{
        struct ib_umad_device *dev =
                container_of(kobj, struct ib_umad_device, kobj);

        kfree(dev);
}

static struct kobj_type ib_umad_dev_ktype = {
        .release = ib_umad_release_dev,
};

static int hdr_size(struct ib_umad_file *file)
{
        return file->use_pkey_index ? sizeof (struct ib_user_mad_hdr) :
                sizeof (struct ib_user_mad_hdr_old);
}

/* caller must hold file->mutex */
static struct ib_mad_agent *__get_agent(struct ib_umad_file *file, int id)
{
        return file->agents_dead ? NULL : file->agent[id];
}

static int queue_packet(struct ib_umad_file *file,
                        struct ib_mad_agent *agent,
                        struct ib_umad_packet *packet)
{
        int ret = 1;

        mutex_lock(&file->mutex);

        for (packet->mad.hdr.id = 0;
             packet->mad.hdr.id < IB_UMAD_MAX_AGENTS;
             packet->mad.hdr.id++)
                if (agent == __get_agent(file, packet->mad.hdr.id)) {
                        list_add_tail(&packet->list, &file->recv_list);
                        wake_up_interruptible(&file->recv_wait);
                        ret = 0;
                        break;
                }

        mutex_unlock(&file->mutex);

        return ret;
}

static void dequeue_send(struct ib_umad_file *file,
                         struct ib_umad_packet *packet)
{
        spin_lock_irq(&file->send_lock);
        list_del(&packet->list);
        spin_unlock_irq(&file->send_lock);
}

static void send_handler(struct ib_mad_agent *agent,
                         struct ib_mad_send_wc *send_wc)
{
        struct ib_umad_file *file = agent->context;
        struct ib_umad_packet *packet = send_wc->send_buf->context[0];

        dequeue_send(file, packet);
        ib_destroy_ah(packet->msg->ah);
        ib_free_send_mad(packet->msg);

        if (send_wc->status == IB_WC_RESP_TIMEOUT_ERR) {
                packet->length = IB_MGMT_MAD_HDR;
                packet->mad.hdr.status = ETIMEDOUT;
                if (!queue_packet(file, agent, packet))
                        return;
        }
        kfree(packet);
}

static void recv_handler(struct ib_mad_agent *agent,
                         struct ib_mad_recv_wc *mad_recv_wc)
{
        struct ib_umad_file *file = agent->context;
        struct ib_umad_packet *packet;

        if (mad_recv_wc->wc->status != IB_WC_SUCCESS)
                goto err1;

        packet = kzalloc(sizeof *packet, GFP_KERNEL);
        if (!packet)
                goto err1;

        packet->length = mad_recv_wc->mad_len;
        packet->recv_wc = mad_recv_wc;

        packet->mad.hdr.status     = 0;
        packet->mad.hdr.length     = hdr_size(file) + mad_recv_wc->mad_len;
        packet->mad.hdr.qpn        = cpu_to_be32(mad_recv_wc->wc->src_qp);
        packet->mad.hdr.lid        = cpu_to_be16(mad_recv_wc->wc->slid);
        packet->mad.hdr.sl         = mad_recv_wc->wc->sl;
        packet->mad.hdr.path_bits  = mad_recv_wc->wc->dlid_path_bits;
        packet->mad.hdr.pkey_index = mad_recv_wc->wc->pkey_index;
        packet->mad.hdr.grh_present = !!(mad_recv_wc->wc->wc_flags & IB_WC_GRH);
        if (packet->mad.hdr.grh_present) {
                struct ib_ah_attr ah_attr;

                ib_init_ah_from_wc(agent->device, agent->port_num,
                                   mad_recv_wc->wc, mad_recv_wc->recv_buf.grh,
                                   &ah_attr);

                packet->mad.hdr.gid_index = ah_attr.grh.sgid_index;
                packet->mad.hdr.hop_limit = ah_attr.grh.hop_limit;
                packet->mad.hdr.traffic_class = ah_attr.grh.traffic_class;
                memcpy(packet->mad.hdr.gid, &ah_attr.grh.dgid, 16);
                packet->mad.hdr.flow_label = cpu_to_be32(ah_attr.grh.flow_label);
        }

        if (queue_packet(file, agent, packet))
                goto err2;
        return;

err2:
        kfree(packet);
err1:
        ib_free_recv_mad(mad_recv_wc);
}

static ssize_t copy_recv_mad(struct ib_umad_file *file, char __user *buf,
                             struct ib_umad_packet *packet, size_t count)
{
        struct ib_mad_recv_buf *recv_buf;
        int left, seg_payload, offset, max_seg_payload;
        size_t seg_size;

        recv_buf = &packet->recv_wc->recv_buf;
        seg_size = packet->recv_wc->mad_seg_size;

        /* We need enough room to copy the first (or only) MAD segment. */
        if ((packet->length <= seg_size &&
             count < hdr_size(file) + packet->length) ||
            (packet->length > seg_size &&
             count < hdr_size(file) + seg_size))
                return -EINVAL;

        if (copy_to_user(buf, &packet->mad, hdr_size(file)))
                return -EFAULT;

        buf += hdr_size(file);
        seg_payload = min_t(int, packet->length, seg_size);
        if (copy_to_user(buf, recv_buf->mad, seg_payload))
                return -EFAULT;

        if (seg_payload < packet->length) {
                /*
                 * Multipacket RMPP MAD message. Copy remainder of message.
                 * Note that last segment may have a shorter payload.
                 */
                if (count < hdr_size(file) + packet->length) {
                        /*
                         * The buffer is too small, return the first RMPP segment,
                         * which includes the RMPP message length.
                         */
                        return -ENOSPC;
                }
                offset = ib_get_mad_data_offset(recv_buf->mad->mad_hdr.mgmt_class);
                max_seg_payload = seg_size - offset;

                for (left = packet->length - seg_payload, buf += seg_payload;
                     left; left -= seg_payload, buf += seg_payload) {
                        recv_buf = container_of(recv_buf->list.next,
                                                struct ib_mad_recv_buf, list);
                        seg_payload = min(left, max_seg_payload);
                        if (copy_to_user(buf, ((void *) recv_buf->mad) + offset,
                                         seg_payload))
                                return -EFAULT;
                }
        }
        return hdr_size(file) + packet->length;
}

static ssize_t copy_send_mad(struct ib_umad_file *file, char __user *buf,
                             struct ib_umad_packet *packet, size_t count)
{
        ssize_t size = hdr_size(file) + packet->length;

        if (count < size)
                return -EINVAL;

        if (copy_to_user(buf, &packet->mad, hdr_size(file)))
                return -EFAULT;

        buf += hdr_size(file);

        if (copy_to_user(buf, packet->mad.data, packet->length))
                return -EFAULT;

        return size;
}

static ssize_t ib_umad_read(struct file *filp, char __user *buf,
                            size_t count, loff_t *pos)
{
        struct ib_umad_file *file = filp->private_data;
        struct ib_umad_packet *packet;
        ssize_t ret;

        if (count < hdr_size(file))
                return -EINVAL;

        mutex_lock(&file->mutex);

        while (list_empty(&file->recv_list)) {
                mutex_unlock(&file->mutex);

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

                if (wait_event_interruptible(file->recv_wait,
                                             !list_empty(&file->recv_list)))
                        return -ERESTARTSYS;

                mutex_lock(&file->mutex);
        }

        packet = list_entry(file->recv_list.next, struct ib_umad_packet, list);
        list_del(&packet->list);

        mutex_unlock(&file->mutex);

        if (packet->recv_wc)
                ret = copy_recv_mad(file, buf, packet, count);
        else
                ret = copy_send_mad(file, buf, packet, count);

        if (ret < 0) {
                /* Requeue packet */
                mutex_lock(&file->mutex);
                list_add(&packet->list, &file->recv_list);
                mutex_unlock(&file->mutex);
        } else {
                if (packet->recv_wc)
                        ib_free_recv_mad(packet->recv_wc);
                kfree(packet);
        }
        return ret;
}

static int copy_rmpp_mad(struct ib_mad_send_buf *msg, const char __user *buf)
{
        int left, seg;

        /* Copy class specific header */
        if ((msg->hdr_len > IB_MGMT_RMPP_HDR) &&
            copy_from_user(msg->mad + IB_MGMT_RMPP_HDR, buf + IB_MGMT_RMPP_HDR,
                           msg->hdr_len - IB_MGMT_RMPP_HDR))
                return -EFAULT;

        /* All headers are in place.  Copy data segments. */
        for (seg = 1, left = msg->data_len, buf += msg->hdr_len; left > 0;
             seg++, left -= msg->seg_size, buf += msg->seg_size) {
                if (copy_from_user(ib_get_rmpp_segment(msg, seg), buf,
                                   min(left, msg->seg_size)))
                        return -EFAULT;
        }
        return 0;
}

static int same_destination(struct ib_user_mad_hdr *hdr1,
                            struct ib_user_mad_hdr *hdr2)
{
        if (!hdr1->grh_present && !hdr2->grh_present)
           return (hdr1->lid == hdr2->lid);

        if (hdr1->grh_present && hdr2->grh_present)
           return !memcmp(hdr1->gid, hdr2->gid, 16);

        return 0;
}

static int is_duplicate(struct ib_umad_file *file,
                        struct ib_umad_packet *packet)
{
        struct ib_umad_packet *sent_packet;
        struct ib_mad_hdr *sent_hdr, *hdr;

        hdr = (struct ib_mad_hdr *) packet->mad.data;
        list_for_each_entry(sent_packet, &file->send_list, list) {
                sent_hdr = (struct ib_mad_hdr *) sent_packet->mad.data;

                if ((hdr->tid != sent_hdr->tid) ||
                    (hdr->mgmt_class != sent_hdr->mgmt_class))
                        continue;

                /*
                 * No need to be overly clever here.  If two new operations have
                 * the same TID, reject the second as a duplicate.  This is more
                 * restrictive than required by the spec.
                 */
                if (!ib_response_mad(hdr)) {
                        if (!ib_response_mad(sent_hdr))
                                return 1;
                        continue;
                } else if (!ib_response_mad(sent_hdr))
                        continue;

                if (same_destination(&packet->mad.hdr, &sent_packet->mad.hdr))
                        return 1;
        }

        return 0;
}

static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
                             size_t count, loff_t *pos)
{
        struct ib_umad_file *file = filp->private_data;
        struct ib_umad_packet *packet;
        struct ib_mad_agent *agent;
        struct ib_ah_attr ah_attr;
        struct ib_ah *ah;
        struct ib_rmpp_mad *rmpp_mad;
        __be64 *tid;
        int ret, data_len, hdr_len, copy_offset, rmpp_active;
        u8 base_version;

        if (count < hdr_size(file) + IB_MGMT_RMPP_HDR)
                return -EINVAL;

        packet = kzalloc(sizeof *packet + IB_MGMT_RMPP_HDR, GFP_KERNEL);
        if (!packet)
                return -ENOMEM;

        if (copy_from_user(&packet->mad, buf, hdr_size(file))) {
                ret = -EFAULT;
                goto err;
        }

        if (packet->mad.hdr.id >= IB_UMAD_MAX_AGENTS) {
                ret = -EINVAL;
                goto err;
        }

        buf += hdr_size(file);

        if (copy_from_user(packet->mad.data, buf, IB_MGMT_RMPP_HDR)) {
                ret = -EFAULT;
                goto err;
        }

        mutex_lock(&file->mutex);

        agent = __get_agent(file, packet->mad.hdr.id);
        if (!agent) {
                ret = -EINVAL;
                goto err_up;
        }

        memset(&ah_attr, 0, sizeof ah_attr);
        ah_attr.dlid          = be16_to_cpu(packet->mad.hdr.lid);
        ah_attr.sl            = packet->mad.hdr.sl;
        ah_attr.src_path_bits = packet->mad.hdr.path_bits;
        ah_attr.port_num      = file->port->port_num;
        if (packet->mad.hdr.grh_present) {
                ah_attr.ah_flags = IB_AH_GRH;
                memcpy(ah_attr.grh.dgid.raw, packet->mad.hdr.gid, 16);
                ah_attr.grh.sgid_index     = packet->mad.hdr.gid_index;
                ah_attr.grh.flow_label     = be32_to_cpu(packet->mad.hdr.flow_label);
                ah_attr.grh.hop_limit      = packet->mad.hdr.hop_limit;
                ah_attr.grh.traffic_class  = packet->mad.hdr.traffic_class;
        }

        ah = ib_create_ah(agent->qp->pd, &ah_attr);
        if (IS_ERR(ah)) {
                ret = PTR_ERR(ah);
                goto err_up;
        }

        rmpp_mad = (struct ib_rmpp_mad *) packet->mad.data;
        hdr_len = ib_get_mad_data_offset(rmpp_mad->mad_hdr.mgmt_class);

        if (ib_is_mad_class_rmpp(rmpp_mad->mad_hdr.mgmt_class)
            && ib_mad_kernel_rmpp_agent(agent)) {
                copy_offset = IB_MGMT_RMPP_HDR;
                rmpp_active = ib_get_rmpp_flags(&rmpp_mad->rmpp_hdr) &
                                                IB_MGMT_RMPP_FLAG_ACTIVE;
        } else {
                copy_offset = IB_MGMT_MAD_HDR;
                rmpp_active = 0;
        }

        base_version = ((struct ib_mad_hdr *)&packet->mad.data)->base_version;
        data_len = count - hdr_size(file) - hdr_len;
        packet->msg = ib_create_send_mad(agent,
                                         be32_to_cpu(packet->mad.hdr.qpn),
                                         packet->mad.hdr.pkey_index, rmpp_active,
                                         hdr_len, data_len, GFP_KERNEL,
                                         base_version);
        if (IS_ERR(packet->msg)) {
                ret = PTR_ERR(packet->msg);
                goto err_ah;
        }

        packet->msg->ah         = ah;
        packet->msg->timeout_ms = packet->mad.hdr.timeout_ms;
        packet->msg->retries    = packet->mad.hdr.retries;
        packet->msg->context[0] = packet;

        /* Copy MAD header.  Any RMPP header is already in place. */
        memcpy(packet->msg->mad, packet->mad.data, IB_MGMT_MAD_HDR);

        if (!rmpp_active) {
                if (copy_from_user(packet->msg->mad + copy_offset,
                                   buf + copy_offset,
                                   hdr_len + data_len - copy_offset)) {
                        ret = -EFAULT;
                        goto err_msg;
                }
        } else {
                ret = copy_rmpp_mad(packet->msg, buf);
                if (ret)
                        goto err_msg;
        }

        /*
         * Set the high-order part of the transaction ID to make MADs from
         * different agents unique, and allow routing responses back to the
         * original requestor.
         */
        if (!ib_response_mad(packet->msg->mad)) {
                tid = &((struct ib_mad_hdr *) packet->msg->mad)->tid;
                *tid = cpu_to_be64(((u64) agent->hi_tid) << 32 |
                                   (be64_to_cpup(tid) & 0xffffffff));
                rmpp_mad->mad_hdr.tid = *tid;
        }

        if (!ib_mad_kernel_rmpp_agent(agent)
           && ib_is_mad_class_rmpp(rmpp_mad->mad_hdr.mgmt_class)
           && (ib_get_rmpp_flags(&rmpp_mad->rmpp_hdr) & IB_MGMT_RMPP_FLAG_ACTIVE)) {
                spin_lock_irq(&file->send_lock);
                list_add_tail(&packet->list, &file->send_list);
                spin_unlock_irq(&file->send_lock);
        } else {
                spin_lock_irq(&file->send_lock);
                ret = is_duplicate(file, packet);
                if (!ret)
                        list_add_tail(&packet->list, &file->send_list);
                spin_unlock_irq(&file->send_lock);
                if (ret) {
                        ret = -EINVAL;
                        goto err_msg;
                }
        }

        ret = ib_post_send_mad(packet->msg, NULL);
        if (ret)
                goto err_send;

        mutex_unlock(&file->mutex);
        return count;

err_send:
        dequeue_send(file, packet);
err_msg:
        ib_free_send_mad(packet->msg);
err_ah:
        ib_destroy_ah(ah);
err_up:
        mutex_unlock(&file->mutex);
err:
        kfree(packet);
        return ret;
}

static unsigned int ib_umad_poll(struct file *filp, struct poll_table_struct *wait)
{
        struct ib_umad_file *file = filp->private_data;

        /* we will always be able to post a MAD send */
        unsigned int mask = POLLOUT | POLLWRNORM;

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

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

        return mask;
}

static int ib_umad_reg_agent(struct ib_umad_file *file, void __user *arg,
                             int compat_method_mask)
{
        struct ib_user_mad_reg_req ureq;
        struct ib_mad_reg_req req;
        struct ib_mad_agent *agent = NULL;
        int agent_id;
        int ret;

        mutex_lock(&file->port->file_mutex);
        mutex_lock(&file->mutex);

        if (!file->port->ib_dev) {
                dev_notice(file->port->dev,
                           "ib_umad_reg_agent: invalid device\n");
                ret = -EPIPE;
                goto out;
        }

        if (copy_from_user(&ureq, arg, sizeof ureq)) {
                ret = -EFAULT;
                goto out;
        }

        if (ureq.qpn != 0 && ureq.qpn != 1) {
                dev_notice(file->port->dev,
                           "ib_umad_reg_agent: invalid QPN %d specified\n",
                           ureq.qpn);
                ret = -EINVAL;
                goto out;
        }

        for (agent_id = 0; agent_id < IB_UMAD_MAX_AGENTS; ++agent_id)
                if (!__get_agent(file, agent_id))
                        goto found;

        dev_notice(file->port->dev,
                   "ib_umad_reg_agent: Max Agents (%u) reached\n",
                   IB_UMAD_MAX_AGENTS);
        ret = -ENOMEM;
        goto out;

found:
        if (ureq.mgmt_class) {
                memset(&req, 0, sizeof(req));
                req.mgmt_class         = ureq.mgmt_class;
                req.mgmt_class_version = ureq.mgmt_class_version;
                memcpy(req.oui, ureq.oui, sizeof req.oui);

                if (compat_method_mask) {
                        u32 *umm = (u32 *) ureq.method_mask;
                        int i;

                        for (i = 0; i < BITS_TO_LONGS(IB_MGMT_MAX_METHODS); ++i)
                                req.method_mask[i] =
                                        umm[i * 2] | ((u64) umm[i * 2 + 1] << 32);
                } else
                        memcpy(req.method_mask, ureq.method_mask,
                               sizeof req.method_mask);
        }

        agent = ib_register_mad_agent(file->port->ib_dev, file->port->port_num,
                                      ureq.qpn ? IB_QPT_GSI : IB_QPT_SMI,
                                      ureq.mgmt_class ? &req : NULL,
                                      ureq.rmpp_version,
                                      send_handler, recv_handler, file, 0);
        if (IS_ERR(agent)) {
                ret = PTR_ERR(agent);
                agent = NULL;
                goto out;
        }

        if (put_user(agent_id,
                     (u32 __user *) (arg + offsetof(struct ib_user_mad_reg_req, id)))) {
                ret = -EFAULT;
                goto out;
        }

        if (!file->already_used) {
                file->already_used = 1;
                if (!file->use_pkey_index) {
                        dev_warn(file->port->dev,
                                "process %s did not enable P_Key index support.\n",
                                current->comm);
                        dev_warn(file->port->dev,
                                "   Documentation/infiniband/user_mad.txt has info on the new ABI.\n");
                }
        }

        file->agent[agent_id] = agent;
        ret = 0;

out:
        mutex_unlock(&file->mutex);

        if (ret && agent)
                ib_unregister_mad_agent(agent);

        mutex_unlock(&file->port->file_mutex);

        return ret;
}

static int ib_umad_reg_agent2(struct ib_umad_file *file, void __user *arg)
{
        struct ib_user_mad_reg_req2 ureq;
        struct ib_mad_reg_req req;
        struct ib_mad_agent *agent = NULL;
        int agent_id;
        int ret;

        mutex_lock(&file->port->file_mutex);
        mutex_lock(&file->mutex);

        if (!file->port->ib_dev) {
                dev_notice(file->port->dev,
                           "ib_umad_reg_agent2: invalid device\n");
                ret = -EPIPE;
                goto out;
        }

        if (copy_from_user(&ureq, arg, sizeof(ureq))) {
                ret = -EFAULT;
                goto out;
        }

        if (ureq.qpn != 0 && ureq.qpn != 1) {
                dev_notice(file->port->dev,
                           "ib_umad_reg_agent2: invalid QPN %d specified\n",
                           ureq.qpn);
                ret = -EINVAL;
                goto out;
        }

        if (ureq.flags & ~IB_USER_MAD_REG_FLAGS_CAP) {
                dev_notice(file->port->dev,
                           "ib_umad_reg_agent2 failed: invalid registration flags specified 0x%x; supported 0x%x\n",
                           ureq.flags, IB_USER_MAD_REG_FLAGS_CAP);
                ret = -EINVAL;

                if (put_user((u32)IB_USER_MAD_REG_FLAGS_CAP,
                                (u32 __user *) (arg + offsetof(struct
                                ib_user_mad_reg_req2, flags))))
                        ret = -EFAULT;

                goto out;
        }

        for (agent_id = 0; agent_id < IB_UMAD_MAX_AGENTS; ++agent_id)
                if (!__get_agent(file, agent_id))
                        goto found;

        dev_notice(file->port->dev,
                   "ib_umad_reg_agent2: Max Agents (%u) reached\n",
                   IB_UMAD_MAX_AGENTS);
        ret = -ENOMEM;
        goto out;

found:
        if (ureq.mgmt_class) {
                memset(&req, 0, sizeof(req));
                req.mgmt_class         = ureq.mgmt_class;
                req.mgmt_class_version = ureq.mgmt_class_version;
                if (ureq.oui & 0xff000000) {
                        dev_notice(file->port->dev,
                                   "ib_umad_reg_agent2 failed: oui invalid 0x%08x\n",
                                   ureq.oui);
                        ret = -EINVAL;
                        goto out;
                }
                req.oui[2] =  ureq.oui & 0x0000ff;
                req.oui[1] = (ureq.oui & 0x00ff00) >> 8;
                req.oui[0] = (ureq.oui & 0xff0000) >> 16;
                memcpy(req.method_mask, ureq.method_mask,
                        sizeof(req.method_mask));
        }

        agent = ib_register_mad_agent(file->port->ib_dev, file->port->port_num,
                                      ureq.qpn ? IB_QPT_GSI : IB_QPT_SMI,
                                      ureq.mgmt_class ? &req : NULL,
                                      ureq.rmpp_version,
                                      send_handler, recv_handler, file,
                                      ureq.flags);
        if (IS_ERR(agent)) {
                ret = PTR_ERR(agent);
                agent = NULL;
                goto out;
        }

        if (put_user(agent_id,
                     (u32 __user *)(arg +
                                offsetof(struct ib_user_mad_reg_req2, id)))) {
                ret = -EFAULT;
                goto out;
        }

        if (!file->already_used) {
                file->already_used = 1;
                file->use_pkey_index = 1;
        }

        file->agent[agent_id] = agent;
        ret = 0;

out:
        mutex_unlock(&file->mutex);

        if (ret && agent)
                ib_unregister_mad_agent(agent);

        mutex_unlock(&file->port->file_mutex);

        return ret;
}


static int ib_umad_unreg_agent(struct ib_umad_file *file, u32 __user *arg)
{
        struct ib_mad_agent *agent = NULL;
        u32 id;
        int ret = 0;

        if (get_user(id, arg))
                return -EFAULT;

        mutex_lock(&file->port->file_mutex);
        mutex_lock(&file->mutex);

        if (id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) {
                ret = -EINVAL;
                goto out;
        }

        agent = file->agent[id];
        file->agent[id] = NULL;

out:
        mutex_unlock(&file->mutex);

        if (agent)
                ib_unregister_mad_agent(agent);

        mutex_unlock(&file->port->file_mutex);

        return ret;
}

static long ib_umad_enable_pkey(struct ib_umad_file *file)
{
        int ret = 0;

        mutex_lock(&file->mutex);
        if (file->already_used)
                ret = -EINVAL;
        else
                file->use_pkey_index = 1;
        mutex_unlock(&file->mutex);

        return ret;
}

static long ib_umad_ioctl(struct file *filp, unsigned int cmd,
                          unsigned long arg)
{
        switch (cmd) {
        case IB_USER_MAD_REGISTER_AGENT:
                return ib_umad_reg_agent(filp->private_data, (void __user *) arg, 0);
        case IB_USER_MAD_UNREGISTER_AGENT:
                return ib_umad_unreg_agent(filp->private_data, (__u32 __user *) arg);
        case IB_USER_MAD_ENABLE_PKEY:
                return ib_umad_enable_pkey(filp->private_data);
        case IB_USER_MAD_REGISTER_AGENT2:
                return ib_umad_reg_agent2(filp->private_data, (void __user *) arg);
        default:
                return -ENOIOCTLCMD;
        }
}

#ifdef CONFIG_COMPAT
static long ib_umad_compat_ioctl(struct file *filp, unsigned int cmd,
                                 unsigned long arg)
{
        switch (cmd) {
        case IB_USER_MAD_REGISTER_AGENT:
                return ib_umad_reg_agent(filp->private_data, compat_ptr(arg), 1);
        case IB_USER_MAD_UNREGISTER_AGENT:
                return ib_umad_unreg_agent(filp->private_data, compat_ptr(arg));
        case IB_USER_MAD_ENABLE_PKEY:
                return ib_umad_enable_pkey(filp->private_data);
        case IB_USER_MAD_REGISTER_AGENT2:
                return ib_umad_reg_agent2(filp->private_data, compat_ptr(arg));
        default:
                return -ENOIOCTLCMD;
        }
}
#endif

/*
 * ib_umad_open() does not need the BKL:
 *
 *  - the ib_umad_port structures are properly reference counted, and
 *    everything else is purely local to the file being created, so
 *    races against other open calls are not a problem;
 *  - the ioctl method does not affect any global state outside of the
 *    file structure being operated on;
 */
static int ib_umad_open(struct inode *inode, struct file *filp)
{
        struct ib_umad_port *port;
        struct ib_umad_file *file;
        int ret = -ENXIO;

        port = container_of(inode->i_cdev, struct ib_umad_port, cdev);

        mutex_lock(&port->file_mutex);

        if (!port->ib_dev)
                goto out;

        ret = -ENOMEM;
        file = kzalloc(sizeof *file, GFP_KERNEL);
        if (!file)
                goto out;

        mutex_init(&file->mutex);
        spin_lock_init(&file->send_lock);
        INIT_LIST_HEAD(&file->recv_list);
        INIT_LIST_HEAD(&file->send_list);
        init_waitqueue_head(&file->recv_wait);

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

        list_add_tail(&file->port_list, &port->file_list);

        ret = nonseekable_open(inode, filp);
        if (ret) {
                list_del(&file->port_list);
                kfree(file);
                goto out;
        }

        kobject_get(&port->umad_dev->kobj);

out:
        mutex_unlock(&port->file_mutex);
        return ret;
}

static int ib_umad_close(struct inode *inode, struct file *filp)
{
        struct ib_umad_file *file = filp->private_data;
        struct ib_umad_device *dev = file->port->umad_dev;
        struct ib_umad_packet *packet, *tmp;
        int already_dead;
        int i;

        mutex_lock(&file->port->file_mutex);
        mutex_lock(&file->mutex);

        already_dead = file->agents_dead;
        file->agents_dead = 1;

        list_for_each_entry_safe(packet, tmp, &file->recv_list, list) {
                if (packet->recv_wc)
                        ib_free_recv_mad(packet->recv_wc);
                kfree(packet);
        }

        list_del(&file->port_list);

        mutex_unlock(&file->mutex);

        if (!already_dead)
                for (i = 0; i < IB_UMAD_MAX_AGENTS; ++i)
                        if (file->agent[i])
                                ib_unregister_mad_agent(file->agent[i]);

        mutex_unlock(&file->port->file_mutex);

        kfree(file);
        kobject_put(&dev->kobj);

        return 0;
}

static const struct file_operations umad_fops = {
        .owner          = THIS_MODULE,
        .read           = ib_umad_read,
        .write          = ib_umad_write,
        .poll           = ib_umad_poll,
        .unlocked_ioctl = ib_umad_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ib_umad_compat_ioctl,
#endif
        .open           = ib_umad_open,
        .release        = ib_umad_close,
        .llseek         = no_llseek,
};

static int ib_umad_sm_open(struct inode *inode, struct file *filp)
{
        struct ib_umad_port *port;
        struct ib_port_modify props = {
                .set_port_cap_mask = IB_PORT_SM
        };
        int ret;

        port = container_of(inode->i_cdev, struct ib_umad_port, sm_cdev);

        if (filp->f_flags & O_NONBLOCK) {
                if (down_trylock(&port->sm_sem)) {
                        ret = -EAGAIN;
                        goto fail;
                }
        } else {
                if (down_interruptible(&port->sm_sem)) {
                        ret = -ERESTARTSYS;
                        goto fail;
                }
        }

        ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
        if (ret)
                goto err_up_sem;

        filp->private_data = port;

        ret = nonseekable_open(inode, filp);
        if (ret)
                goto err_clr_sm_cap;

        kobject_get(&port->umad_dev->kobj);

        return 0;

err_clr_sm_cap:
        swap(props.set_port_cap_mask, props.clr_port_cap_mask);
        ib_modify_port(port->ib_dev, port->port_num, 0, &props);

err_up_sem:
        up(&port->sm_sem);

fail:
        return ret;
}

static int ib_umad_sm_close(struct inode *inode, struct file *filp)
{
        struct ib_umad_port *port = filp->private_data;
        struct ib_port_modify props = {
                .clr_port_cap_mask = IB_PORT_SM
        };
        int ret = 0;

        mutex_lock(&port->file_mutex);
        if (port->ib_dev)
                ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
        mutex_unlock(&port->file_mutex);

        up(&port->sm_sem);

        kobject_put(&port->umad_dev->kobj);

        return ret;
}

static const struct file_operations umad_sm_fops = {
        .owner   = THIS_MODULE,
        .open    = ib_umad_sm_open,
        .release = ib_umad_sm_close,
        .llseek  = no_llseek,
};

static struct ib_client umad_client = {
        .name   = "umad",
        .add    = ib_umad_add_one,
        .remove = ib_umad_remove_one
};

static ssize_t show_ibdev(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct ib_umad_port *port = dev_get_drvdata(dev);

        if (!port)
                return -ENODEV;

        return sprintf(buf, "%s\n", port->ib_dev->name);
}
static DEVICE_ATTR(ibdev, S_IRUGO, show_ibdev, NULL);

static ssize_t show_port(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct ib_umad_port *port = dev_get_drvdata(dev);

        if (!port)
                return -ENODEV;

        return sprintf(buf, "%d\n", port->port_num);
}
static DEVICE_ATTR(port, S_IRUGO, show_port, NULL);

static CLASS_ATTR_STRING(abi_version, S_IRUGO,
                         __stringify(IB_USER_MAD_ABI_VERSION));

static dev_t overflow_maj;
static DECLARE_BITMAP(overflow_map, IB_UMAD_MAX_PORTS);
static int find_overflow_devnum(struct ib_device *device)
{
        int ret;

        if (!overflow_maj) {
                ret = alloc_chrdev_region(&overflow_maj, 0, IB_UMAD_MAX_PORTS * 2,
                                          "infiniband_mad");
                if (ret) {
                        dev_err(&device->dev,
                                "couldn't register dynamic device number\n");
                        return ret;
                }
        }

        ret = find_first_zero_bit(overflow_map, IB_UMAD_MAX_PORTS);
        if (ret >= IB_UMAD_MAX_PORTS)
                return -1;

        return ret;
}

static int ib_umad_init_port(struct ib_device *device, int port_num,
                             struct ib_umad_device *umad_dev,
                             struct ib_umad_port *port)
{
        int devnum;
        dev_t base;

        spin_lock(&port_lock);
        devnum = find_first_zero_bit(dev_map, IB_UMAD_MAX_PORTS);
        if (devnum >= IB_UMAD_MAX_PORTS) {
                spin_unlock(&port_lock);
                devnum = find_overflow_devnum(device);
                if (devnum < 0)
                        return -1;

                spin_lock(&port_lock);
                port->dev_num = devnum + IB_UMAD_MAX_PORTS;
                base = devnum + overflow_maj;
                set_bit(devnum, overflow_map);
        } else {
                port->dev_num = devnum;
                base = devnum + base_dev;
                set_bit(devnum, dev_map);
        }
        spin_unlock(&port_lock);

        port->ib_dev   = device;
        port->port_num = port_num;
        sema_init(&port->sm_sem, 1);
        mutex_init(&port->file_mutex);
        INIT_LIST_HEAD(&port->file_list);

        cdev_init(&port->cdev, &umad_fops);
        port->cdev.owner = THIS_MODULE;
        port->cdev.kobj.parent = &umad_dev->kobj;
        kobject_set_name(&port->cdev.kobj, "umad%d", port->dev_num);
        if (cdev_add(&port->cdev, base, 1))
                goto err_cdev;

        port->dev = device_create(umad_class, device->dma_device,
                                  port->cdev.dev, port,
                                  "umad%d", port->dev_num);
        if (IS_ERR(port->dev))
                goto err_cdev;

        if (device_create_file(port->dev, &dev_attr_ibdev))
                goto err_dev;
        if (device_create_file(port->dev, &dev_attr_port))
                goto err_dev;

        base += IB_UMAD_MAX_PORTS;
        cdev_init(&port->sm_cdev, &umad_sm_fops);
        port->sm_cdev.owner = THIS_MODULE;
        port->sm_cdev.kobj.parent = &umad_dev->kobj;
        kobject_set_name(&port->sm_cdev.kobj, "issm%d", port->dev_num);
        if (cdev_add(&port->sm_cdev, base, 1))
                goto err_sm_cdev;

        port->sm_dev = device_create(umad_class, device->dma_device,
                                     port->sm_cdev.dev, port,
                                     "issm%d", port->dev_num);
        if (IS_ERR(port->sm_dev))
                goto err_sm_cdev;

        if (device_create_file(port->sm_dev, &dev_attr_ibdev))
                goto err_sm_dev;
        if (device_create_file(port->sm_dev, &dev_attr_port))
                goto err_sm_dev;

        return 0;

err_sm_dev:
        device_destroy(umad_class, port->sm_cdev.dev);

err_sm_cdev:
        cdev_del(&port->sm_cdev);

err_dev:
        device_destroy(umad_class, port->cdev.dev);

err_cdev:
        cdev_del(&port->cdev);
        if (port->dev_num < IB_UMAD_MAX_PORTS)
                clear_bit(devnum, dev_map);
        else
                clear_bit(devnum, overflow_map);

        return -1;
}

static void ib_umad_kill_port(struct ib_umad_port *port)
{
        struct ib_umad_file *file;
        int id;

        dev_set_drvdata(port->dev,    NULL);
        dev_set_drvdata(port->sm_dev, NULL);

        device_destroy(umad_class, port->cdev.dev);
        device_destroy(umad_class, port->sm_cdev.dev);

        cdev_del(&port->cdev);
        cdev_del(&port->sm_cdev);

        mutex_lock(&port->file_mutex);

        port->ib_dev = NULL;

        list_for_each_entry(file, &port->file_list, port_list) {
                mutex_lock(&file->mutex);
                file->agents_dead = 1;
                mutex_unlock(&file->mutex);

                for (id = 0; id < IB_UMAD_MAX_AGENTS; ++id)
                        if (file->agent[id])
                                ib_unregister_mad_agent(file->agent[id]);
        }

        mutex_unlock(&port->file_mutex);

        if (port->dev_num < IB_UMAD_MAX_PORTS)
                clear_bit(port->dev_num, dev_map);
        else
                clear_bit(port->dev_num - IB_UMAD_MAX_PORTS, overflow_map);
}

static void ib_umad_add_one(struct ib_device *device)
{
        struct ib_umad_device *umad_dev;
        int s, e, i;
        int count = 0;

        s = rdma_start_port(device);
        e = rdma_end_port(device);

        umad_dev = kzalloc(sizeof *umad_dev +
                           (e - s + 1) * sizeof (struct ib_umad_port),
                           GFP_KERNEL);
        if (!umad_dev)
                return;

        kobject_init(&umad_dev->kobj, &ib_umad_dev_ktype);

        for (i = s; i <= e; ++i) {
                if (!rdma_cap_ib_mad(device, i))
                        continue;

                umad_dev->port[i - s].umad_dev = umad_dev;

                if (ib_umad_init_port(device, i, umad_dev,
                                      &umad_dev->port[i - s]))
                        goto err;

                count++;
        }

        if (!count)
                goto free;

        ib_set_client_data(device, &umad_client, umad_dev);

        return;

err:
        while (--i >= s) {
                if (!rdma_cap_ib_mad(device, i))
                        continue;

                ib_umad_kill_port(&umad_dev->port[i - s]);
        }
free:
        kobject_put(&umad_dev->kobj);
}

static void ib_umad_remove_one(struct ib_device *device)
{
        struct ib_umad_device *umad_dev = ib_get_client_data(device, &umad_client);
        int i;

        if (!umad_dev)
                return;

        for (i = 0; i <= rdma_end_port(device) - rdma_start_port(device); ++i) {
                if (rdma_cap_ib_mad(device, i + rdma_start_port(device)))
                        ib_umad_kill_port(&umad_dev->port[i]);
        }

        kobject_put(&umad_dev->kobj);
}

static char *umad_devnode(struct device *dev, umode_t *mode)
{
        return kasprintf(GFP_KERNEL, "infiniband/%s", dev_name(dev));
}

static int __init ib_umad_init(void)
{
        int ret;

        ret = register_chrdev_region(base_dev, IB_UMAD_MAX_PORTS * 2,
                                     "infiniband_mad");
        if (ret) {
                pr_err("couldn't register device number\n");
                goto out;
        }

        umad_class = class_create(THIS_MODULE, "infiniband_mad");
        if (IS_ERR(umad_class)) {
                ret = PTR_ERR(umad_class);
                pr_err("couldn't create class infiniband_mad\n");
                goto out_chrdev;
        }

        umad_class->devnode = umad_devnode;

        ret = class_create_file(umad_class, &class_attr_abi_version.attr);
        if (ret) {
                pr_err("couldn't create abi_version attribute\n");
                goto out_class;
        }

        ret = ib_register_client(&umad_client);
        if (ret) {
                pr_err("couldn't register ib_umad client\n");
                goto out_class;
        }

        return 0;

out_class:
        class_destroy(umad_class);

out_chrdev:
        unregister_chrdev_region(base_dev, IB_UMAD_MAX_PORTS * 2);

out:
        return ret;
}

static void __exit ib_umad_cleanup(void)
{
        ib_unregister_client(&umad_client);
        class_destroy(umad_class);
        unregister_chrdev_region(base_dev, IB_UMAD_MAX_PORTS * 2);
        if (overflow_maj)
                unregister_chrdev_region(overflow_maj, IB_UMAD_MAX_PORTS * 2);
}

module_init(ib_umad_init);
module_exit(ib_umad_cleanup);