ipath_verbs_mcast.c

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/*
 * Copyright (c) 2006, 2007 QLogic Corporation. All rights reserved.
 * Copyright (c) 2005, 2006 PathScale, 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.
 */

#include <linux/rculist.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include "ipath_verbs.h"

/*
 * Global table of GID to attached QPs.
 * The table is global to all ipath devices since a send from one QP/device
 * needs to be locally routed to any locally attached QPs on the same
 * or different device.
 */
static struct rb_root mcast_tree;
static DEFINE_SPINLOCK(mcast_lock);

static struct ipath_mcast_qp *ipath_mcast_qp_alloc(struct ipath_qp *qp)
{
    struct ipath_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 ipath_mcast_qp_free(struct ipath_mcast_qp *mqp)
{
    struct ipath_qp *qp = mqp->qp;

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

    kfree(mqp);
}

static struct ipath_mcast *ipath_mcast_alloc(union ib_gid *mgid)
{
    struct ipath_mcast *mcast;

    mcast = kmalloc(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);
    mcast->n_attached = 0;

bail:
    return mcast;
}

static void ipath_mcast_free(struct ipath_mcast *mcast)
{
    struct ipath_mcast_qp *p, *tmp;

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

    kfree(mcast);
}

struct ipath_mcast *ipath_mcast_find(union ib_gid *mgid)
{
    struct rb_node *n;
    unsigned long flags;
    struct ipath_mcast *mcast;

    spin_lock_irqsave(&mcast_lock, flags);
    n = mcast_tree.rb_node;
    while (n) {
        int ret;

        mcast = rb_entry(n, struct ipath_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);
            spin_unlock_irqrestore(&mcast_lock, flags);
            goto bail;
        }
    }
    spin_unlock_irqrestore(&mcast_lock, flags);

    mcast = NULL;

bail:
    return mcast;
}

static int ipath_mcast_add(struct ipath_ibdev *dev,
               struct ipath_mcast *mcast,
               struct ipath_mcast_qp *mqp)
{
    struct rb_node **n = &mcast_tree.rb_node;
    struct rb_node *pn = NULL;
    int ret;

    spin_lock_irq(&mcast_lock);

    while (*n) {
        struct ipath_mcast *tmcast;
        struct ipath_mcast_qp *p;

        pn = *n;
        tmcast = rb_entry(pn, struct ipath_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 == ib_ipath_max_mcast_qp_attached) {
            ret = ENOMEM;
            goto bail;
        }

        tmcast->n_attached++;

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

    spin_lock(&dev->n_mcast_grps_lock);
    if (dev->n_mcast_grps_allocated == ib_ipath_max_mcast_grps) {
        spin_unlock(&dev->n_mcast_grps_lock);
        ret = ENOMEM;
        goto bail;
    }

    dev->n_mcast_grps_allocated++;
    spin_unlock(&dev->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, &mcast_tree);

    ret = 0;

bail:
    spin_unlock_irq(&mcast_lock);

    return ret;
}

int ipath_multicast_attach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
{
    struct ipath_qp *qp = to_iqp(ibqp);
    struct ipath_ibdev *dev = to_idev(ibqp->device);
    struct ipath_mcast *mcast;
    struct ipath_mcast_qp *mqp;
    int ret;

    /*
     * Allocate data structures since its better to do this outside of
     * spin locks and it will most likely be needed.
     */
    mcast = ipath_mcast_alloc(gid);
    if (mcast == NULL) {
        ret = -ENOMEM;
        goto bail;
    }
    mqp = ipath_mcast_qp_alloc(qp);
    if (mqp == NULL) {
        ipath_mcast_free(mcast);
        ret = -ENOMEM;
        goto bail;
    }
    switch (ipath_mcast_add(dev, mcast, mqp)) {
    case ESRCH:
        /* Neither was used: can't attach the same QP twice. */
        ipath_mcast_qp_free(mqp);
        ipath_mcast_free(mcast);
        ret = -EINVAL;
        goto bail;
    case EEXIST:        /* The mcast wasn't used */
        ipath_mcast_free(mcast);
        break;
    case ENOMEM:
        /* Exceeded the maximum number of mcast groups. */
        ipath_mcast_qp_free(mqp);
        ipath_mcast_free(mcast);
        ret = -ENOMEM;
        goto bail;
    default:
        break;
    }

    ret = 0;

bail:
    return ret;
}

int ipath_multicast_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
{
    struct ipath_qp *qp = to_iqp(ibqp);
    struct ipath_ibdev *dev = to_idev(ibqp->device);
    struct ipath_mcast *mcast = NULL;
    struct ipath_mcast_qp *p, *tmp;
    struct rb_node *n;
    int last = 0;
    int ret;

    spin_lock_irq(&mcast_lock);

    /* Find the GID in the mcast table. */
    n = mcast_tree.rb_node;
    while (1) {
        if (n == NULL) {
            spin_unlock_irq(&mcast_lock);
            ret = -EINVAL;
            goto bail;
        }

        mcast = rb_entry(n, struct ipath_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--;

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

    spin_unlock_irq(&mcast_lock);

    if (p) {
        /*
         * Wait for any list walkers to finish before freeing the
         * list element.
         */
        wait_event(mcast->wait, atomic_read(&mcast->refcount) <= 1);
        ipath_mcast_qp_free(p);
    }
    if (last) {
        atomic_dec(&mcast->refcount);
        wait_event(mcast->wait, !atomic_read(&mcast->refcount));
        ipath_mcast_free(mcast);
        spin_lock_irq(&dev->n_mcast_grps_lock);
        dev->n_mcast_grps_allocated--;
        spin_unlock_irq(&dev->n_mcast_grps_lock);
    }

    ret = 0;

bail:
    return ret;
}

int ipath_mcast_tree_empty(void)
{
    return mcast_tree.rb_node == NULL;
}