Merge tag 'io_uring-5.11-2021-01-16' of git://git.kernel.dk/linux-block

[linux/fpc-iii.git] / net / rds / ib_rdma.c

/*
 * Copyright (c) 2006, 2018 Oracle and/or its affiliates. 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/kernel.h>
#include <linux/slab.h>
#include <linux/rculist.h>
#include <linux/llist.h>

#include "rds_single_path.h"
#include "ib_mr.h"
#include "rds.h"

struct workqueue_struct *rds_ib_mr_wq;
struct rds_ib_dereg_odp_mr {
        struct work_struct work;
        struct ib_mr *mr;
};

static void rds_ib_odp_mr_worker(struct work_struct *work);

static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
{
        struct rds_ib_device *rds_ibdev;
        struct rds_ib_ipaddr *i_ipaddr;

        rcu_read_lock();
        list_for_each_entry_rcu(rds_ibdev, &rds_ib_devices, list) {
                list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
                        if (i_ipaddr->ipaddr == ipaddr) {
                                refcount_inc(&rds_ibdev->refcount);
                                rcu_read_unlock();
                                return rds_ibdev;
                        }
                }
        }
        rcu_read_unlock();

        return NULL;
}

static int rds_ib_add_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
{
        struct rds_ib_ipaddr *i_ipaddr;

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

        i_ipaddr->ipaddr = ipaddr;

        spin_lock_irq(&rds_ibdev->spinlock);
        list_add_tail_rcu(&i_ipaddr->list, &rds_ibdev->ipaddr_list);
        spin_unlock_irq(&rds_ibdev->spinlock);

        return 0;
}

static void rds_ib_remove_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
{
        struct rds_ib_ipaddr *i_ipaddr;
        struct rds_ib_ipaddr *to_free = NULL;


        spin_lock_irq(&rds_ibdev->spinlock);
        list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
                if (i_ipaddr->ipaddr == ipaddr) {
                        list_del_rcu(&i_ipaddr->list);
                        to_free = i_ipaddr;
                        break;
                }
        }
        spin_unlock_irq(&rds_ibdev->spinlock);

        if (to_free)
                kfree_rcu(to_free, rcu);
}

int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev,
                         struct in6_addr *ipaddr)
{
        struct rds_ib_device *rds_ibdev_old;

        rds_ibdev_old = rds_ib_get_device(ipaddr->s6_addr32[3]);
        if (!rds_ibdev_old)
                return rds_ib_add_ipaddr(rds_ibdev, ipaddr->s6_addr32[3]);

        if (rds_ibdev_old != rds_ibdev) {
                rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr->s6_addr32[3]);
                rds_ib_dev_put(rds_ibdev_old);
                return rds_ib_add_ipaddr(rds_ibdev, ipaddr->s6_addr32[3]);
        }
        rds_ib_dev_put(rds_ibdev_old);

        return 0;
}

void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
{
        struct rds_ib_connection *ic = conn->c_transport_data;

        /* conn was previously on the nodev_conns_list */
        spin_lock_irq(&ib_nodev_conns_lock);
        BUG_ON(list_empty(&ib_nodev_conns));
        BUG_ON(list_empty(&ic->ib_node));
        list_del(&ic->ib_node);

        spin_lock(&rds_ibdev->spinlock);
        list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);
        spin_unlock(&rds_ibdev->spinlock);
        spin_unlock_irq(&ib_nodev_conns_lock);

        ic->rds_ibdev = rds_ibdev;
        refcount_inc(&rds_ibdev->refcount);
}

void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
{
        struct rds_ib_connection *ic = conn->c_transport_data;

        /* place conn on nodev_conns_list */
        spin_lock(&ib_nodev_conns_lock);

        spin_lock_irq(&rds_ibdev->spinlock);
        BUG_ON(list_empty(&ic->ib_node));
        list_del(&ic->ib_node);
        spin_unlock_irq(&rds_ibdev->spinlock);

        list_add_tail(&ic->ib_node, &ib_nodev_conns);

        spin_unlock(&ib_nodev_conns_lock);

        ic->rds_ibdev = NULL;
        rds_ib_dev_put(rds_ibdev);
}

void rds_ib_destroy_nodev_conns(void)
{
        struct rds_ib_connection *ic, *_ic;
        LIST_HEAD(tmp_list);

        /* avoid calling conn_destroy with irqs off */
        spin_lock_irq(&ib_nodev_conns_lock);
        list_splice(&ib_nodev_conns, &tmp_list);
        spin_unlock_irq(&ib_nodev_conns_lock);

        list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node)
                rds_conn_destroy(ic->conn);
}

void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo)
{
        struct rds_ib_mr_pool *pool_1m = rds_ibdev->mr_1m_pool;

        iinfo->rdma_mr_max = pool_1m->max_items;
        iinfo->rdma_mr_size = pool_1m->max_pages;
}

#if IS_ENABLED(CONFIG_IPV6)
void rds6_ib_get_mr_info(struct rds_ib_device *rds_ibdev,
                         struct rds6_info_rdma_connection *iinfo6)
{
        struct rds_ib_mr_pool *pool_1m = rds_ibdev->mr_1m_pool;

        iinfo6->rdma_mr_max = pool_1m->max_items;
        iinfo6->rdma_mr_size = pool_1m->max_pages;
}
#endif

struct rds_ib_mr *rds_ib_reuse_mr(struct rds_ib_mr_pool *pool)
{
        struct rds_ib_mr *ibmr = NULL;
        struct llist_node *ret;
        unsigned long flags;

        spin_lock_irqsave(&pool->clean_lock, flags);
        ret = llist_del_first(&pool->clean_list);
        spin_unlock_irqrestore(&pool->clean_lock, flags);
        if (ret) {
                ibmr = llist_entry(ret, struct rds_ib_mr, llnode);
                if (pool->pool_type == RDS_IB_MR_8K_POOL)
                        rds_ib_stats_inc(s_ib_rdma_mr_8k_reused);
                else
                        rds_ib_stats_inc(s_ib_rdma_mr_1m_reused);
        }

        return ibmr;
}

void rds_ib_sync_mr(void *trans_private, int direction)
{
        struct rds_ib_mr *ibmr = trans_private;
        struct rds_ib_device *rds_ibdev = ibmr->device;

        if (ibmr->odp)
                return;

        switch (direction) {
        case DMA_FROM_DEVICE:
                ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
                        ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
                break;
        case DMA_TO_DEVICE:
                ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
                        ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
                break;
        }
}

void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
{
        struct rds_ib_device *rds_ibdev = ibmr->device;

        if (ibmr->sg_dma_len) {
                ib_dma_unmap_sg(rds_ibdev->dev,
                                ibmr->sg, ibmr->sg_len,
                                DMA_BIDIRECTIONAL);
                ibmr->sg_dma_len = 0;
        }

        /* Release the s/g list */
        if (ibmr->sg_len) {
                unsigned int i;

                for (i = 0; i < ibmr->sg_len; ++i) {
                        struct page *page = sg_page(&ibmr->sg[i]);

                        /* FIXME we need a way to tell a r/w MR
                         * from a r/o MR */
                        WARN_ON(!page->mapping && irqs_disabled());
                        set_page_dirty(page);
                        put_page(page);
                }
                kfree(ibmr->sg);

                ibmr->sg = NULL;
                ibmr->sg_len = 0;
        }
}

void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
{
        unsigned int pinned = ibmr->sg_len;

        __rds_ib_teardown_mr(ibmr);
        if (pinned) {
                struct rds_ib_mr_pool *pool = ibmr->pool;

                atomic_sub(pinned, &pool->free_pinned);
        }
}

static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
{
        unsigned int item_count;

        item_count = atomic_read(&pool->item_count);
        if (free_all)
                return item_count;

        return 0;
}

/*
 * given an llist of mrs, put them all into the list_head for more processing
 */
static unsigned int llist_append_to_list(struct llist_head *llist,
                                         struct list_head *list)
{
        struct rds_ib_mr *ibmr;
        struct llist_node *node;
        struct llist_node *next;
        unsigned int count = 0;

        node = llist_del_all(llist);
        while (node) {
                next = node->next;
                ibmr = llist_entry(node, struct rds_ib_mr, llnode);
                list_add_tail(&ibmr->unmap_list, list);
                node = next;
                count++;
        }
        return count;
}

/*
 * this takes a list head of mrs and turns it into linked llist nodes
 * of clusters.  Each cluster has linked llist nodes of
 * MR_CLUSTER_SIZE mrs that are ready for reuse.
 */
static void list_to_llist_nodes(struct list_head *list,
                                struct llist_node **nodes_head,
                                struct llist_node **nodes_tail)
{
        struct rds_ib_mr *ibmr;
        struct llist_node *cur = NULL;
        struct llist_node **next = nodes_head;

        list_for_each_entry(ibmr, list, unmap_list) {
                cur = &ibmr->llnode;
                *next = cur;
                next = &cur->next;
        }
        *next = NULL;
        *nodes_tail = cur;
}

/*
 * Flush our pool of MRs.
 * At a minimum, all currently unused MRs are unmapped.
 * If the number of MRs allocated exceeds the limit, we also try
 * to free as many MRs as needed to get back to this limit.
 */
int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
                         int free_all, struct rds_ib_mr **ibmr_ret)
{
        struct rds_ib_mr *ibmr;
        struct llist_node *clean_nodes;
        struct llist_node *clean_tail;
        LIST_HEAD(unmap_list);
        unsigned long unpinned = 0;
        unsigned int nfreed = 0, dirty_to_clean = 0, free_goal;

        if (pool->pool_type == RDS_IB_MR_8K_POOL)
                rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_flush);
        else
                rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_flush);

        if (ibmr_ret) {
                DEFINE_WAIT(wait);
                while (!mutex_trylock(&pool->flush_lock)) {
                        ibmr = rds_ib_reuse_mr(pool);
                        if (ibmr) {
                                *ibmr_ret = ibmr;
                                finish_wait(&pool->flush_wait, &wait);
                                goto out_nolock;
                        }

                        prepare_to_wait(&pool->flush_wait, &wait,
                                        TASK_UNINTERRUPTIBLE);
                        if (llist_empty(&pool->clean_list))
                                schedule();

                        ibmr = rds_ib_reuse_mr(pool);
                        if (ibmr) {
                                *ibmr_ret = ibmr;
                                finish_wait(&pool->flush_wait, &wait);
                                goto out_nolock;
                        }
                }
                finish_wait(&pool->flush_wait, &wait);
        } else
                mutex_lock(&pool->flush_lock);

        if (ibmr_ret) {
                ibmr = rds_ib_reuse_mr(pool);
                if (ibmr) {
                        *ibmr_ret = ibmr;
                        goto out;
                }
        }

        /* Get the list of all MRs to be dropped. Ordering matters -
         * we want to put drop_list ahead of free_list.
         */
        dirty_to_clean = llist_append_to_list(&pool->drop_list, &unmap_list);
        dirty_to_clean += llist_append_to_list(&pool->free_list, &unmap_list);
        if (free_all) {
                unsigned long flags;

                spin_lock_irqsave(&pool->clean_lock, flags);
                llist_append_to_list(&pool->clean_list, &unmap_list);
                spin_unlock_irqrestore(&pool->clean_lock, flags);
        }

        free_goal = rds_ib_flush_goal(pool, free_all);

        if (list_empty(&unmap_list))
                goto out;

        rds_ib_unreg_frmr(&unmap_list, &nfreed, &unpinned, free_goal);

        if (!list_empty(&unmap_list)) {
                unsigned long flags;

                list_to_llist_nodes(&unmap_list, &clean_nodes, &clean_tail);
                if (ibmr_ret) {
                        *ibmr_ret = llist_entry(clean_nodes, struct rds_ib_mr, llnode);
                        clean_nodes = clean_nodes->next;
                }
                /* more than one entry in llist nodes */
                if (clean_nodes) {
                        spin_lock_irqsave(&pool->clean_lock, flags);
                        llist_add_batch(clean_nodes, clean_tail,
                                        &pool->clean_list);
                        spin_unlock_irqrestore(&pool->clean_lock, flags);
                }
        }

        atomic_sub(unpinned, &pool->free_pinned);
        atomic_sub(dirty_to_clean, &pool->dirty_count);
        atomic_sub(nfreed, &pool->item_count);

out:
        mutex_unlock(&pool->flush_lock);
        if (waitqueue_active(&pool->flush_wait))
                wake_up(&pool->flush_wait);
out_nolock:
        return 0;
}

struct rds_ib_mr *rds_ib_try_reuse_ibmr(struct rds_ib_mr_pool *pool)
{
        struct rds_ib_mr *ibmr = NULL;
        int iter = 0;

        while (1) {
                ibmr = rds_ib_reuse_mr(pool);
                if (ibmr)
                        return ibmr;

                if (atomic_inc_return(&pool->item_count) <= pool->max_items)
                        break;

                atomic_dec(&pool->item_count);

                if (++iter > 2) {
                        if (pool->pool_type == RDS_IB_MR_8K_POOL)
                                rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_depleted);
                        else
                                rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_depleted);
                        break;
                }

                /* We do have some empty MRs. Flush them out. */
                if (pool->pool_type == RDS_IB_MR_8K_POOL)
                        rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_wait);
                else
                        rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_wait);

                rds_ib_flush_mr_pool(pool, 0, &ibmr);
                if (ibmr)
                        return ibmr;
        }

        return NULL;
}

static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
{
        struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker.work);

        rds_ib_flush_mr_pool(pool, 0, NULL);
}

void rds_ib_free_mr(void *trans_private, int invalidate)
{
        struct rds_ib_mr *ibmr = trans_private;
        struct rds_ib_mr_pool *pool = ibmr->pool;
        struct rds_ib_device *rds_ibdev = ibmr->device;

        rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);

        if (ibmr->odp) {
                /* A MR created and marked as use_once. We use delayed work,
                 * because there is a change that we are in interrupt and can't
                 * call to ib_dereg_mr() directly.
                 */
                INIT_DELAYED_WORK(&ibmr->work, rds_ib_odp_mr_worker);
                queue_delayed_work(rds_ib_mr_wq, &ibmr->work, 0);
                return;
        }

        /* Return it to the pool's free list */
        rds_ib_free_frmr_list(ibmr);

        atomic_add(ibmr->sg_len, &pool->free_pinned);
        atomic_inc(&pool->dirty_count);

        /* If we've pinned too many pages, request a flush */
        if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
            atomic_read(&pool->dirty_count) >= pool->max_items / 5)
                queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);

        if (invalidate) {
                if (likely(!in_interrupt())) {
                        rds_ib_flush_mr_pool(pool, 0, NULL);
                } else {
                        /* We get here if the user created a MR marked
                         * as use_once and invalidate at the same time.
                         */
                        queue_delayed_work(rds_ib_mr_wq,
                                           &pool->flush_worker, 10);
                }
        }

        rds_ib_dev_put(rds_ibdev);
}

void rds_ib_flush_mrs(void)
{
        struct rds_ib_device *rds_ibdev;

        down_read(&rds_ib_devices_lock);
        list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
                if (rds_ibdev->mr_8k_pool)
                        rds_ib_flush_mr_pool(rds_ibdev->mr_8k_pool, 0, NULL);

                if (rds_ibdev->mr_1m_pool)
                        rds_ib_flush_mr_pool(rds_ibdev->mr_1m_pool, 0, NULL);
        }
        up_read(&rds_ib_devices_lock);
}

u32 rds_ib_get_lkey(void *trans_private)
{
        struct rds_ib_mr *ibmr = trans_private;

        return ibmr->u.mr->lkey;
}

void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
                    struct rds_sock *rs, u32 *key_ret,
                    struct rds_connection *conn,
                    u64 start, u64 length, int need_odp)
{
        struct rds_ib_device *rds_ibdev;
        struct rds_ib_mr *ibmr = NULL;
        struct rds_ib_connection *ic = NULL;
        int ret;

        rds_ibdev = rds_ib_get_device(rs->rs_bound_addr.s6_addr32[3]);
        if (!rds_ibdev) {
                ret = -ENODEV;
                goto out;
        }

        if (need_odp == ODP_ZEROBASED || need_odp == ODP_VIRTUAL) {
                u64 virt_addr = need_odp == ODP_ZEROBASED ? 0 : start;
                int access_flags =
                        (IB_ACCESS_LOCAL_WRITE | IB_ACCESS_REMOTE_READ |
                         IB_ACCESS_REMOTE_WRITE | IB_ACCESS_REMOTE_ATOMIC |
                         IB_ACCESS_ON_DEMAND);
                struct ib_sge sge = {};
                struct ib_mr *ib_mr;

                if (!rds_ibdev->odp_capable) {
                        ret = -EOPNOTSUPP;
                        goto out;
                }

                ib_mr = ib_reg_user_mr(rds_ibdev->pd, start, length, virt_addr,
                                       access_flags);

                if (IS_ERR(ib_mr)) {
                        rdsdebug("rds_ib_get_user_mr returned %d\n",
                                 IS_ERR(ib_mr));
                        ret = PTR_ERR(ib_mr);
                        goto out;
                }
                if (key_ret)
                        *key_ret = ib_mr->rkey;

                ibmr = kzalloc(sizeof(*ibmr), GFP_KERNEL);
                if (!ibmr) {
                        ib_dereg_mr(ib_mr);
                        ret = -ENOMEM;
                        goto out;
                }
                ibmr->u.mr = ib_mr;
                ibmr->odp = 1;

                sge.addr = virt_addr;
                sge.length = length;
                sge.lkey = ib_mr->lkey;

                ib_advise_mr(rds_ibdev->pd,
                             IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH_WRITE,
                             IB_UVERBS_ADVISE_MR_FLAG_FLUSH, &sge, 1);
                return ibmr;
        }

        if (conn)
                ic = conn->c_transport_data;

        if (!rds_ibdev->mr_8k_pool || !rds_ibdev->mr_1m_pool) {
                ret = -ENODEV;
                goto out;
        }

        ibmr = rds_ib_reg_frmr(rds_ibdev, ic, sg, nents, key_ret);
        if (IS_ERR(ibmr)) {
                ret = PTR_ERR(ibmr);
                pr_warn("RDS/IB: rds_ib_get_mr failed (errno=%d)\n", ret);
        } else {
                return ibmr;
        }

 out:
        if (rds_ibdev)
                rds_ib_dev_put(rds_ibdev);

        return ERR_PTR(ret);
}

void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
{
        cancel_delayed_work_sync(&pool->flush_worker);
        rds_ib_flush_mr_pool(pool, 1, NULL);
        WARN_ON(atomic_read(&pool->item_count));
        WARN_ON(atomic_read(&pool->free_pinned));
        kfree(pool);
}

struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev,
                                             int pool_type)
{
        struct rds_ib_mr_pool *pool;

        pool = kzalloc(sizeof(*pool), GFP_KERNEL);
        if (!pool)
                return ERR_PTR(-ENOMEM);

        pool->pool_type = pool_type;
        init_llist_head(&pool->free_list);
        init_llist_head(&pool->drop_list);
        init_llist_head(&pool->clean_list);
        spin_lock_init(&pool->clean_lock);
        mutex_init(&pool->flush_lock);
        init_waitqueue_head(&pool->flush_wait);
        INIT_DELAYED_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);

        if (pool_type == RDS_IB_MR_1M_POOL) {
                /* +1 allows for unaligned MRs */
                pool->max_pages = RDS_MR_1M_MSG_SIZE + 1;
                pool->max_items = rds_ibdev->max_1m_mrs;
        } else {
                /* pool_type == RDS_IB_MR_8K_POOL */
                pool->max_pages = RDS_MR_8K_MSG_SIZE + 1;
                pool->max_items = rds_ibdev->max_8k_mrs;
        }

        pool->max_free_pinned = pool->max_items * pool->max_pages / 4;
        pool->max_items_soft = rds_ibdev->max_mrs * 3 / 4;

        return pool;
}

int rds_ib_mr_init(void)
{
        rds_ib_mr_wq = alloc_workqueue("rds_mr_flushd", WQ_MEM_RECLAIM, 0);
        if (!rds_ib_mr_wq)
                return -ENOMEM;
        return 0;
}

/* By the time this is called all the IB devices should have been torn down and
 * had their pools freed.  As each pool is freed its work struct is waited on,
 * so the pool flushing work queue should be idle by the time we get here.
 */
void rds_ib_mr_exit(void)
{
        destroy_workqueue(rds_ib_mr_wq);
}

static void rds_ib_odp_mr_worker(struct work_struct  *work)
{
        struct rds_ib_mr *ibmr;

        ibmr = container_of(work, struct rds_ib_mr, work.work);
        ib_dereg_mr(ibmr->u.mr);
        kfree(ibmr);
}