[IB] umad: further ib_unregister_mad_agent() deadlock fixes

[deliverable/linux.git] / drivers / infiniband / core / user_mad.c

/*
 * 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.
 *
 * 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.
 *
 * $Id: user_mad.c 4010 2005-11-09 23:11:56Z roland $
 */

#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/pci.h>
#include <linux/dma-mapping.h>
#include <linux/poll.h>
#include <linux/rwsem.h>
#include <linux/kref.h>

#include <asm/uaccess.h>
#include <asm/semaphore.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: each time a
 * device special file is opened, we look up the corresponding struct
 * ib_umad_port by minor in the umad_port[] table while holding the
 * port_lock.  If this lookup succeeds, we take a reference on the
 * ib_umad_port's struct ib_umad_device while still holding the
 * port_lock; if the lookup fails, we fail the open().  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 clear all of its
 * ib_umad_ports from umad_port[] while holding port_lock before
 * dropping the module's reference to the ib_umad_device.  This is
 * always safe because any open() calls will either succeed and obtain
 * a reference before we clear the umad_port[] entries, or fail after
 * we clear the umad_port[] entries.
 */

struct ib_umad_port {
        struct cdev           *dev;
        struct class_device   *class_dev;

        struct cdev           *sm_dev;
        struct class_device   *sm_class_dev;
        struct semaphore       sm_sem;

        struct rw_semaphore    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 {
        int                  start_port, end_port;
        struct kref          ref;
        struct ib_umad_port  port[0];
};

struct ib_umad_file {
        struct ib_umad_port    *port;
        struct list_head        recv_list;
        struct list_head        port_list;
        spinlock_t              recv_lock;
        wait_queue_head_t       recv_wait;
        struct ib_mad_agent    *agent[IB_UMAD_MAX_AGENTS];
        int                     agents_dead;
};

struct ib_umad_packet {
        struct ib_mad_send_buf *msg;
        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 struct ib_umad_port *umad_port[IB_UMAD_MAX_PORTS];
static DECLARE_BITMAP(dev_map, IB_UMAD_MAX_PORTS * 2);

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 kref *ref)
{
        struct ib_umad_device *dev =
                container_of(ref, struct ib_umad_device, ref);

        kfree(dev);
}

/* caller must hold port->mutex at least for reading */
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;

        down_read(&file->port->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)) {
                        spin_lock_irq(&file->recv_lock);
                        list_add_tail(&packet->list, &file->recv_list);
                        spin_unlock_irq(&file->recv_lock);
                        wake_up_interruptible(&file->recv_wait);
                        ret = 0;
                        break;
                }

        up_read(&file->port->mutex);

        return ret;
}

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 *timeout;
        struct ib_umad_packet *packet = send_wc->send_buf->context[0];

        ib_destroy_ah(packet->msg->ah);
        ib_free_send_mad(packet->msg);

        if (send_wc->status == IB_WC_RESP_TIMEOUT_ERR) {
                timeout = kzalloc(sizeof *timeout + IB_MGMT_MAD_HDR, GFP_KERNEL);
                if (!timeout)
                        goto out;

                timeout->length         = IB_MGMT_MAD_HDR;
                timeout->mad.hdr.id     = packet->mad.hdr.id;
                timeout->mad.hdr.status = ETIMEDOUT;
                memcpy(timeout->mad.data, packet->mad.data,
                       sizeof (struct ib_mad_hdr));

                if (!queue_packet(file, agent, timeout))
                                return;
        }
out:
        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;
        int length;

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

        length = mad_recv_wc->mad_len;
        packet = kzalloc(sizeof *packet + length, GFP_KERNEL);
        if (!packet)
                goto out;

        packet->length = length;

        ib_coalesce_recv_mad(mad_recv_wc, packet->mad.data);

        packet->mad.hdr.status    = 0;
        packet->mad.hdr.length    = length + sizeof (struct ib_user_mad);
        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.grh_present = !!(mad_recv_wc->wc->wc_flags & IB_WC_GRH);
        if (packet->mad.hdr.grh_present) {
                /* XXX parse GRH */
                packet->mad.hdr.gid_index       = 0;
                packet->mad.hdr.hop_limit       = 0;
                packet->mad.hdr.traffic_class   = 0;
                memset(packet->mad.hdr.gid, 0, 16);
                packet->mad.hdr.flow_label      = 0;
        }

        if (queue_packet(file, agent, packet))
                kfree(packet);

out:
        ib_free_recv_mad(mad_recv_wc);
}

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 < sizeof (struct ib_user_mad) + sizeof (struct ib_mad))
                return -EINVAL;

        spin_lock_irq(&file->recv_lock);

        while (list_empty(&file->recv_list)) {
                spin_unlock_irq(&file->recv_lock);

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

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

                spin_lock_irq(&file->recv_lock);
        }

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

        spin_unlock_irq(&file->recv_lock);

        if (count < packet->length + sizeof (struct ib_user_mad)) {
                /* Return length needed (and first RMPP segment) if too small */
                if (copy_to_user(buf, &packet->mad,
                                 sizeof (struct ib_user_mad) + sizeof (struct ib_mad)))
                        ret = -EFAULT;
                else
                        ret = -ENOSPC;
        } else if (copy_to_user(buf, &packet->mad,
                                packet->length + sizeof (struct ib_user_mad)))
                ret = -EFAULT;
        else
                ret = packet->length + sizeof (struct ib_user_mad);
        if (ret < 0) {
                /* Requeue packet */
                spin_lock_irq(&file->recv_lock);
                list_add(&packet->list, &file->recv_list);
                spin_unlock_irq(&file->recv_lock);
        } else
                kfree(packet);
        return ret;
}

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;
        u8 method;
        __be64 *tid;
        int ret, length, hdr_len, copy_offset;
        int rmpp_active = 0;

        if (count < sizeof (struct ib_user_mad))
                return -EINVAL;

        length = count - sizeof (struct ib_user_mad);
        packet = kmalloc(sizeof *packet + IB_MGMT_RMPP_HDR, GFP_KERNEL);
        if (!packet)
                return -ENOMEM;

        if (copy_from_user(&packet->mad, buf,
                            sizeof (struct ib_user_mad) + IB_MGMT_RMPP_HDR)) {
                ret = -EFAULT;
                goto err;
        }

        if (packet->mad.hdr.id < 0 ||
            packet->mad.hdr.id >= IB_UMAD_MAX_AGENTS) {
                ret = -EINVAL;
                goto err;
        }

        down_read(&file->port->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.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;
        if (ib_get_rmpp_flags(&rmpp_mad->rmpp_hdr) & IB_MGMT_RMPP_FLAG_ACTIVE) {
                /* RMPP active */
                if (!agent->rmpp_version) {
                        ret = -EINVAL;
                        goto err_ah;
                }

                /* Validate that the management class can support RMPP */
                if (rmpp_mad->mad_hdr.mgmt_class == IB_MGMT_CLASS_SUBN_ADM) {
                        hdr_len = IB_MGMT_SA_HDR;
                } else if ((rmpp_mad->mad_hdr.mgmt_class >= IB_MGMT_CLASS_VENDOR_RANGE2_START) &&
                            (rmpp_mad->mad_hdr.mgmt_class <= IB_MGMT_CLASS_VENDOR_RANGE2_END)) {
                                hdr_len = IB_MGMT_VENDOR_HDR;
                } else {
                        ret = -EINVAL;
                        goto err_ah;
                }
                rmpp_active = 1;
                copy_offset = IB_MGMT_RMPP_HDR;
        } else {
                hdr_len = IB_MGMT_MAD_HDR;
                copy_offset = IB_MGMT_MAD_HDR;
        }

        packet->msg = ib_create_send_mad(agent,
                                         be32_to_cpu(packet->mad.hdr.qpn),
                                         0, rmpp_active,
                                         hdr_len, length - hdr_len,
                                         GFP_KERNEL);
        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 headers (RMPP header in place) */
        memcpy(packet->msg->mad, packet->mad.data, IB_MGMT_MAD_HDR);
        /* Now, copy rest of message from user into send buffer */
        if (copy_from_user(packet->msg->mad + copy_offset,
                           buf + sizeof (struct ib_user_mad) + copy_offset,
                           length - copy_offset)) {
                ret = -EFAULT;
                goto err_msg;
        }

        /*
         * If userspace is generating a request that will generate a
         * response, we need to make sure the high-order part of the
         * transaction ID matches the agent being used to send the
         * MAD.
         */
        method = ((struct ib_mad_hdr *) packet->msg->mad)->method;

        if (!(method & IB_MGMT_METHOD_RESP)       &&
            method != IB_MGMT_METHOD_TRAP_REPRESS &&
            method != IB_MGMT_METHOD_SEND) {
                tid = &((struct ib_mad_hdr *) packet->msg->mad)->tid;
                *tid = cpu_to_be64(((u64) agent->hi_tid) << 32 |
                                   (be64_to_cpup(tid) & 0xffffffff));
        }

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

        up_read(&file->port->mutex);

        return count;

err_msg:
        ib_free_send_mad(packet->msg);

err_ah:
        ib_destroy_ah(ah);

err_up:
        up_read(&file->port->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, unsigned long arg)
{
        struct ib_user_mad_reg_req ureq;
        struct ib_mad_reg_req req;
        struct ib_mad_agent *agent;
        int agent_id;
        int ret;

        down_write(&file->port->mutex);

        if (!file->port->ib_dev) {
                ret = -EPIPE;
                goto out;
        }

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

        if (ureq.qpn != 0 && ureq.qpn != 1) {
                ret = -EINVAL;
                goto out;
        }

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

        ret = -ENOMEM;
        goto out;

found:
        if (ureq.mgmt_class) {
                req.mgmt_class         = ureq.mgmt_class;
                req.mgmt_class_version = ureq.mgmt_class_version;
                memcpy(req.method_mask, ureq.method_mask, sizeof req.method_mask);
                memcpy(req.oui,         ureq.oui,         sizeof req.oui);
        }

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

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

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

out:
        up_write(&file->port->mutex);
        return ret;
}

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

        if (get_user(id, (u32 __user *) arg))
                return -EFAULT;

        down_write(&file->port->mutex);

        if (id < 0 || id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) {
                ret = -EINVAL;
                goto out;
        }

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

out:
        up_write(&file->port->mutex);

        if (agent)
                ib_unregister_mad_agent(agent);

        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, arg);
        case IB_USER_MAD_UNREGISTER_AGENT:
                return ib_umad_unreg_agent(filp->private_data, arg);
        default:
                return -ENOIOCTLCMD;
        }
}

static int ib_umad_open(struct inode *inode, struct file *filp)
{
        struct ib_umad_port *port;
        struct ib_umad_file *file;
        int ret = 0;

        spin_lock(&port_lock);
        port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE];
        if (port)
                kref_get(&port->umad_dev->ref);
        spin_unlock(&port_lock);

        if (!port)
                return -ENXIO;

        down_write(&port->mutex);

        if (!port->ib_dev) {
                ret = -ENXIO;
                goto out;
        }

        file = kzalloc(sizeof *file, GFP_KERNEL);
        if (!file) {
                kref_put(&port->umad_dev->ref, ib_umad_release_dev);
                ret = -ENOMEM;
                goto out;
        }

        spin_lock_init(&file->recv_lock);
        INIT_LIST_HEAD(&file->recv_list);
        init_waitqueue_head(&file->recv_wait);

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

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

out:
        up_write(&port->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;

        down_write(&file->port->mutex);

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

        list_for_each_entry_safe(packet, tmp, &file->recv_list, list)
                kfree(packet);

        list_del(&file->port_list);

        downgrade_write(&file->port->mutex);

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

        up_read(&file->port->mutex);

        kfree(file);
        kref_put(&dev->ref, ib_umad_release_dev);

        return 0;
}

static 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,
        .compat_ioctl   = ib_umad_ioctl,
        .open           = ib_umad_open,
        .release        = ib_umad_close
};

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;

        spin_lock(&port_lock);
        port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE - IB_UMAD_MAX_PORTS];
        if (port)
                kref_get(&port->umad_dev->ref);
        spin_unlock(&port_lock);

        if (!port)
                return -ENXIO;

        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) {
                up(&port->sm_sem);
                goto fail;
        }

        filp->private_data = port;

        return 0;

fail:
        kref_put(&port->umad_dev->ref, ib_umad_release_dev);
        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;

        down_write(&port->mutex);
        if (port->ib_dev)
                ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
        up_write(&port->mutex);

        up(&port->sm_sem);

        kref_put(&port->umad_dev->ref, ib_umad_release_dev);

        return ret;
}

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

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

static ssize_t show_ibdev(struct class_device *class_dev, char *buf)
{
        struct ib_umad_port *port = class_get_devdata(class_dev);

        if (!port)
                return -ENODEV;

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

static ssize_t show_port(struct class_device *class_dev, char *buf)
{
        struct ib_umad_port *port = class_get_devdata(class_dev);

        if (!port)
                return -ENODEV;

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

static ssize_t show_abi_version(struct class *class, char *buf)
{
        return sprintf(buf, "%d\n", IB_USER_MAD_ABI_VERSION);
}
static CLASS_ATTR(abi_version, S_IRUGO, show_abi_version, NULL);

static int ib_umad_init_port(struct ib_device *device, int port_num,
                             struct ib_umad_port *port)
{
        spin_lock(&port_lock);
        port->dev_num = find_first_zero_bit(dev_map, IB_UMAD_MAX_PORTS);
        if (port->dev_num >= IB_UMAD_MAX_PORTS) {
                spin_unlock(&port_lock);
                return -1;
        }
        set_bit(port->dev_num, dev_map);
        spin_unlock(&port_lock);

        port->ib_dev   = device;
        port->port_num = port_num;
        init_MUTEX(&port->sm_sem);
        init_rwsem(&port->mutex);
        INIT_LIST_HEAD(&port->file_list);

        port->dev = cdev_alloc();
        if (!port->dev)
                return -1;
        port->dev->owner = THIS_MODULE;
        port->dev->ops   = &umad_fops;
        kobject_set_name(&port->dev->kobj, "umad%d", port->dev_num);
        if (cdev_add(port->dev, base_dev + port->dev_num, 1))
                goto err_cdev;

        port->class_dev = class_device_create(umad_class, NULL, port->dev->dev,
                                              device->dma_device,
                                              "umad%d", port->dev_num);
        if (IS_ERR(port->class_dev))
                goto err_cdev;

        if (class_device_create_file(port->class_dev, &class_device_attr_ibdev))
                goto err_class;
        if (class_device_create_file(port->class_dev, &class_device_attr_port))
                goto err_class;

        port->sm_dev = cdev_alloc();
        if (!port->sm_dev)
                goto err_class;
        port->sm_dev->owner = THIS_MODULE;
        port->sm_dev->ops   = &umad_sm_fops;
        kobject_set_name(&port->sm_dev->kobj, "issm%d", port->dev_num);
        if (cdev_add(port->sm_dev, base_dev + port->dev_num + IB_UMAD_MAX_PORTS, 1))
                goto err_sm_cdev;

        port->sm_class_dev = class_device_create(umad_class, NULL, port->sm_dev->dev,
                                                 device->dma_device,
                                                 "issm%d", port->dev_num);
        if (IS_ERR(port->sm_class_dev))
                goto err_sm_cdev;

        class_set_devdata(port->class_dev,    port);
        class_set_devdata(port->sm_class_dev, port);

        if (class_device_create_file(port->sm_class_dev, &class_device_attr_ibdev))
                goto err_sm_class;
        if (class_device_create_file(port->sm_class_dev, &class_device_attr_port))
                goto err_sm_class;

        spin_lock(&port_lock);
        umad_port[port->dev_num] = port;
        spin_unlock(&port_lock);

        return 0;

err_sm_class:
        class_device_destroy(umad_class, port->sm_dev->dev);

err_sm_cdev:
        cdev_del(port->sm_dev);

err_class:
        class_device_destroy(umad_class, port->dev->dev);

err_cdev:
        cdev_del(port->dev);
        clear_bit(port->dev_num, dev_map);

        return -1;
}

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

        class_set_devdata(port->class_dev,    NULL);
        class_set_devdata(port->sm_class_dev, NULL);

        class_device_destroy(umad_class, port->dev->dev);
        class_device_destroy(umad_class, port->sm_dev->dev);

        cdev_del(port->dev);
        cdev_del(port->sm_dev);

        spin_lock(&port_lock);
        umad_port[port->dev_num] = NULL;
        spin_unlock(&port_lock);

        down_write(&port->mutex);

        port->ib_dev = NULL;

        /*
         * Now go through the list of files attached to this port and
         * unregister all of their MAD agents.  We need to hold
         * port->mutex while doing this to avoid racing with
         * ib_umad_close(), but we can't hold the mutex for writing
         * while calling ib_unregister_mad_agent(), since that might
         * deadlock by calling back into queue_packet().  So we
         * downgrade our lock to a read lock, and then drop and
         * reacquire the write lock for the next iteration.
         *
         * We do list_del_init() on the file's list_head so that the
         * list_del in ib_umad_close() is still OK, even after the
         * file is removed from the list.
         */
        while (!list_empty(&port->file_list)) {
                file = list_entry(port->file_list.next, struct ib_umad_file,
                                  port_list);

                file->agents_dead = 1;
                list_del_init(&file->port_list);

                downgrade_write(&port->mutex);

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

                up_read(&port->mutex);
                down_write(&port->mutex);
        }

        up_write(&port->mutex);

        clear_bit(port->dev_num, dev_map);
}

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

        if (device->node_type == IB_NODE_SWITCH)
                s = e = 0;
        else {
                s = 1;
                e = device->phys_port_cnt;
        }

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

        kref_init(&umad_dev->ref);

        umad_dev->start_port = s;
        umad_dev->end_port   = e;

        for (i = s; i <= e; ++i) {
                umad_dev->port[i - s].umad_dev = umad_dev;

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

        ib_set_client_data(device, &umad_client, umad_dev);

        return;

err:
        while (--i >= s)
                ib_umad_kill_port(&umad_dev->port[i - s]);

        kref_put(&umad_dev->ref, ib_umad_release_dev);
}

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 <= umad_dev->end_port - umad_dev->start_port; ++i)
                ib_umad_kill_port(&umad_dev->port[i]);

        kref_put(&umad_dev->ref, ib_umad_release_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) {
                printk(KERN_ERR "user_mad: 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);
                printk(KERN_ERR "user_mad: couldn't create class infiniband_mad\n");
                goto out_chrdev;
        }

        ret = class_create_file(umad_class, &class_attr_abi_version);
        if (ret) {
                printk(KERN_ERR "user_mad: couldn't create abi_version attribute\n");
                goto out_class;
        }

        ret = ib_register_client(&umad_client);
        if (ret) {
                printk(KERN_ERR "user_mad: 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);
}

module_init(ib_umad_init);
module_exit(ib_umad_cleanup);