/*
 * Copyright(c) 2016 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * 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.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/rculist.h>
#include <rdma/rdma_vt.h>
#include <rdma/rdmavt_qp.h>

#include "mcast.h"

/**
 * rvt_driver_mcast - init resources for multicast
 * @rdi: rvt dev struct
 *
 * This is per device that registers with rdmavt
 */
void rvt_driver_mcast_init(struct rvt_dev_info *rdi)
{
        /*
         * Anything that needs setup for multicast on a per driver or per rdi
         * basis should be done in here.
         */
        spin_lock_init(&rdi->n_mcast_grps_lock);
}

/**
 * mcast_qp_alloc - alloc a struct to link a QP to mcast GID struct
 * @qp: the QP to link
 */
static struct rvt_mcast_qp *rvt_mcast_qp_alloc(struct rvt_qp *qp)
{
        struct rvt_mcast_qp *mqp;

        mqp = kmalloc(sizeof(*mqp), GFP_KERNEL);
        if (!mqp)
                goto bail;

        mqp->qp = qp;
        atomic_inc(&qp->refcount);

bail:
        return mqp;
}

static void rvt_mcast_qp_free(struct rvt_mcast_qp *mqp)
{
        struct rvt_qp *qp = mqp->qp;

        /* Notify hfi1_destroy_qp() if it is waiting. */
        if (atomic_dec_and_test(&qp->refcount))
                wake_up(&qp->wait);

        kfree(mqp);
}

/**
 * mcast_alloc - allocate the multicast GID structure
 * @mgid: the multicast GID
 *
 * A list of QPs will be attached to this structure.
 */
static struct rvt_mcast *rvt_mcast_alloc(union ib_gid *mgid)
{
        struct rvt_mcast *mcast;

        mcast = kzalloc(sizeof(*mcast), GFP_KERNEL);
        if (!mcast)
                goto bail;

        mcast->mgid = *mgid;
        INIT_LIST_HEAD(&mcast->qp_list);
        init_waitqueue_head(&mcast->wait);
        atomic_set(&mcast->refcount, 0);

bail:
        return mcast;
}

static void rvt_mcast_free(struct rvt_mcast *mcast)
{
        struct rvt_mcast_qp *p, *tmp;

        list_for_each_entry_safe(p, tmp, &mcast->qp_list, list)
                rvt_mcast_qp_free(p);

        kfree(mcast);
}

/**
 * rvt_mcast_find - search the global table for the given multicast GID
 * @ibp: the IB port structure
 * @mgid: the multicast GID to search for
 *
 * The caller is responsible for decrementing the reference count if found.
 *
 * Return: NULL if not found.
 */
struct rvt_mcast *rvt_mcast_find(struct rvt_ibport *ibp, union ib_gid *mgid)
{
        struct rb_node *n;
        unsigned long flags;
        struct rvt_mcast *found = NULL;

        spin_lock_irqsave(&ibp->lock, flags);
        n = ibp->mcast_tree.rb_node;
        while (n) {
                int ret;
                struct rvt_mcast *mcast;

                mcast = rb_entry(n, struct rvt_mcast, rb_node);

                ret = memcmp(mgid->raw, mcast->mgid.raw,
                             sizeof(union ib_gid));
                if (ret < 0) {
                        n = n->rb_left;
                } else if (ret > 0) {
                        n = n->rb_right;
                } else {
                        atomic_inc(&mcast->refcount);
                        found = mcast;
                        break;
                }
        }
        spin_unlock_irqrestore(&ibp->lock, flags);
        return found;
}
EXPORT_SYMBOL(rvt_mcast_find);

/**
 * mcast_add - insert mcast GID into table and attach QP struct
 * @mcast: the mcast GID table
 * @mqp: the QP to attach
 *
 * Return: zero if both were added.  Return EEXIST if the GID was already in
 * the table but the QP was added.  Return ESRCH if the QP was already
 * attached and neither structure was added.
 */
static int rvt_mcast_add(struct rvt_dev_info *rdi, struct rvt_ibport *ibp,
                         struct rvt_mcast *mcast, struct rvt_mcast_qp *mqp)
{
        struct rb_node **n = &ibp->mcast_tree.rb_node;
        struct rb_node *pn = NULL;
        int ret;

        spin_lock_irq(&ibp->lock);

        while (*n) {
                struct rvt_mcast *tmcast;
                struct rvt_mcast_qp *p;

                pn = *n;
                tmcast = rb_entry(pn, struct rvt_mcast, rb_node);

                ret = memcmp(mcast->mgid.raw, tmcast->mgid.raw,
                             sizeof(union ib_gid));
                if (ret < 0) {
                        n = &pn->rb_left;
                        continue;
                }
                if (ret > 0) {
                        n = &pn->rb_right;
                        continue;
                }

                /* Search the QP list to see if this is already there. */
                list_for_each_entry_rcu(p, &tmcast->qp_list, list) {
                        if (p->qp == mqp->qp) {
                                ret = ESRCH;
                                goto bail;
                        }
                }
                if (tmcast->n_attached ==
                    rdi->dparms.props.max_mcast_qp_attach) {
                        ret = ENOMEM;
                        goto bail;
                }

                tmcast->n_attached++;

                list_add_tail_rcu(&mqp->list, &tmcast->qp_list);
                ret = EEXIST;
                goto bail;
        }

        spin_lock(&rdi->n_mcast_grps_lock);
        if (rdi->n_mcast_grps_allocated == rdi->dparms.props.max_mcast_grp) {
                spin_unlock(&rdi->n_mcast_grps_lock);
                ret = ENOMEM;
                goto bail;
        }

        rdi->n_mcast_grps_allocated++;
        spin_unlock(&rdi->n_mcast_grps_lock);

        mcast->n_attached++;

        list_add_tail_rcu(&mqp->list, &mcast->qp_list);

        atomic_inc(&mcast->refcount);
        rb_link_node(&mcast->rb_node, pn, n);
        rb_insert_color(&mcast->rb_node, &ibp->mcast_tree);

        ret = 0;

bail:
        spin_unlock_irq(&ibp->lock);

        return ret;
}

/**
 * rvt_attach_mcast - attach a qp to a multicast group
 * @ibqp: Infiniband qp
 * @igd: multicast guid
 * @lid: multicast lid
 *
 * Return: 0 on success
 */
int rvt_attach_mcast(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
{
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);
        struct rvt_ibport *ibp = rdi->ports[qp->port_num - 1];
        struct rvt_mcast *mcast;
        struct rvt_mcast_qp *mqp;
        int ret = -ENOMEM;

        if (ibqp->qp_num <= 1 || qp->state == IB_QPS_RESET)
                return -EINVAL;

        /*
         * Allocate data structures since its better to do this outside of
         * spin locks and it will most likely be needed.
         */
        mcast = rvt_mcast_alloc(gid);
        if (!mcast)
                return -ENOMEM;

        mqp = rvt_mcast_qp_alloc(qp);
        if (!mqp)
                goto bail_mcast;

        switch (rvt_mcast_add(rdi, ibp, mcast, mqp)) {
        case ESRCH:
                /* Neither was used: OK to attach the same QP twice. */
                ret = 0;
                goto bail_mqp;
        case EEXIST: /* The mcast wasn't used */
                ret = 0;
                goto bail_mcast;
        case ENOMEM:
                /* Exceeded the maximum number of mcast groups. */
                ret = -ENOMEM;
                goto bail_mqp;
        default:
                break;
        }

        return 0;

bail_mqp:
        rvt_mcast_qp_free(mqp);

bail_mcast:
        rvt_mcast_free(mcast);

        return ret;
}

/**
 * rvt_detach_mcast - remove a qp from a multicast group
 * @ibqp: Infiniband qp
 * @igd: multicast guid
 * @lid: multicast lid
 *
 * Return: 0 on success
 */
int rvt_detach_mcast(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
{
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);
        struct rvt_ibport *ibp = rdi->ports[qp->port_num - 1];
        struct rvt_mcast *mcast = NULL;
        struct rvt_mcast_qp *p, *tmp, *delp = NULL;
        struct rb_node *n;
        int last = 0;
        int ret = 0;

        if (ibqp->qp_num <= 1 || qp->state == IB_QPS_RESET)
                return -EINVAL;

        spin_lock_irq(&ibp->lock);

        /* Find the GID in the mcast table. */
        n = ibp->mcast_tree.rb_node;
        while (1) {
                if (!n) {
                        spin_unlock_irq(&ibp->lock);
                        return -EINVAL;
                }

                mcast = rb_entry(n, struct rvt_mcast, rb_node);
                ret = memcmp(gid->raw, mcast->mgid.raw,
                             sizeof(union ib_gid));
                if (ret < 0)
                        n = n->rb_left;
                else if (ret > 0)
                        n = n->rb_right;
                else
                        break;
        }

        /* Search the QP list. */
        list_for_each_entry_safe(p, tmp, &mcast->qp_list, list) {
                if (p->qp != qp)
                        continue;
                /*
                 * We found it, so remove it, but don't poison the forward
                 * link until we are sure there are no list walkers.
                 */
                list_del_rcu(&p->list);
                mcast->n_attached--;
                delp = p;

                /* If this was the last attached QP, remove the GID too. */
                if (list_empty(&mcast->qp_list)) {
                        rb_erase(&mcast->rb_node, &ibp->mcast_tree);
                        last = 1;
                }
                break;
        }

        spin_unlock_irq(&ibp->lock);
        /* QP not attached */
        if (!delp)
                return -EINVAL;

        /*
         * Wait for any list walkers to finish before freeing the
         * list element.
         */
        wait_event(mcast->wait, atomic_read(&mcast->refcount) <= 1);
        rvt_mcast_qp_free(delp);

        if (last) {
                atomic_dec(&mcast->refcount);
                wait_event(mcast->wait, !atomic_read(&mcast->refcount));
                rvt_mcast_free(mcast);
                spin_lock_irq(&rdi->n_mcast_grps_lock);
                rdi->n_mcast_grps_allocated--;
                spin_unlock_irq(&rdi->n_mcast_grps_lock);
        }

        return 0;
}

/**
 *rvt_mast_tree_empty - determine if any qps are attached to any mcast group
 *@rdi: rvt dev struct
 *
 * Return: in use count
 */
int rvt_mcast_tree_empty(struct rvt_dev_info *rdi)
{
        int i;
        int in_use = 0;

        for (i = 0; i < rdi->dparms.nports; i++)
                if (rdi->ports[i]->mcast_tree.rb_node)
                        in_use++;
        return in_use;
}