[sfrench/cifs-2.6.git] / net / smc / smc_core.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Shared Memory Communications over RDMA (SMC-R) and RoCE
 *
 *  Basic Transport Functions exploiting Infiniband API
 *
 *  Copyright IBM Corp. 2016
 *
 *  Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
 */

#include <linux/socket.h>
#include <linux/if_vlan.h>
#include <linux/random.h>
#include <linux/workqueue.h>
#include <linux/wait.h>
#include <linux/reboot.h>
#include <net/tcp.h>
#include <net/sock.h>
#include <rdma/ib_verbs.h>
#include <rdma/ib_cache.h>

#include "smc.h"
#include "smc_clc.h"
#include "smc_core.h"
#include "smc_ib.h"
#include "smc_wr.h"
#include "smc_llc.h"
#include "smc_cdc.h"
#include "smc_close.h"
#include "smc_ism.h"

#define SMC_LGR_NUM_INCR                256
#define SMC_LGR_FREE_DELAY_SERV         (600 * HZ)
#define SMC_LGR_FREE_DELAY_CLNT         (SMC_LGR_FREE_DELAY_SERV + 10 * HZ)
#define SMC_LGR_FREE_DELAY_FAST         (8 * HZ)

static struct smc_lgr_list smc_lgr_list = {     /* established link groups */
        .lock = __SPIN_LOCK_UNLOCKED(smc_lgr_list.lock),
        .list = LIST_HEAD_INIT(smc_lgr_list.list),
        .num = 0,
};

static atomic_t lgr_cnt = ATOMIC_INIT(0); /* number of existing link groups */
static DECLARE_WAIT_QUEUE_HEAD(lgrs_deleted);

struct smc_ib_up_work {
        struct work_struct      work;
        struct smc_link_group   *lgr;
        struct smc_ib_device    *smcibdev;
        u8                      ibport;
};

static void smc_buf_free(struct smc_link_group *lgr, bool is_rmb,
                         struct smc_buf_desc *buf_desc);
static void __smc_lgr_terminate(struct smc_link_group *lgr, bool soft);

static void smc_link_up_work(struct work_struct *work);
static void smc_link_down_work(struct work_struct *work);

/* return head of link group list and its lock for a given link group */
static inline struct list_head *smc_lgr_list_head(struct smc_link_group *lgr,
                                                  spinlock_t **lgr_lock)
{
        if (lgr->is_smcd) {
                *lgr_lock = &lgr->smcd->lgr_lock;
                return &lgr->smcd->lgr_list;
        }

        *lgr_lock = &smc_lgr_list.lock;
        return &smc_lgr_list.list;
}

static void smc_lgr_schedule_free_work(struct smc_link_group *lgr)
{
        /* client link group creation always follows the server link group
         * creation. For client use a somewhat higher removal delay time,
         * otherwise there is a risk of out-of-sync link groups.
         */
        if (!lgr->freeing && !lgr->freefast) {
                mod_delayed_work(system_wq, &lgr->free_work,
                                 (!lgr->is_smcd && lgr->role == SMC_CLNT) ?
                                                SMC_LGR_FREE_DELAY_CLNT :
                                                SMC_LGR_FREE_DELAY_SERV);
        }
}

void smc_lgr_schedule_free_work_fast(struct smc_link_group *lgr)
{
        if (!lgr->freeing && !lgr->freefast) {
                lgr->freefast = 1;
                mod_delayed_work(system_wq, &lgr->free_work,
                                 SMC_LGR_FREE_DELAY_FAST);
        }
}

/* Register connection's alert token in our lookup structure.
 * To use rbtrees we have to implement our own insert core.
 * Requires @conns_lock
 * @smc         connection to register
 * Returns 0 on success, != otherwise.
 */
static void smc_lgr_add_alert_token(struct smc_connection *conn)
{
        struct rb_node **link, *parent = NULL;
        u32 token = conn->alert_token_local;

        link = &conn->lgr->conns_all.rb_node;
        while (*link) {
                struct smc_connection *cur = rb_entry(*link,
                                        struct smc_connection, alert_node);

                parent = *link;
                if (cur->alert_token_local > token)
                        link = &parent->rb_left;
                else
                        link = &parent->rb_right;
        }
        /* Put the new node there */
        rb_link_node(&conn->alert_node, parent, link);
        rb_insert_color(&conn->alert_node, &conn->lgr->conns_all);
}

/* Register connection in link group by assigning an alert token
 * registered in a search tree.
 * Requires @conns_lock
 * Note that '0' is a reserved value and not assigned.
 */
static int smc_lgr_register_conn(struct smc_connection *conn)
{
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
        static atomic_t nexttoken = ATOMIC_INIT(0);

        /* find a new alert_token_local value not yet used by some connection
         * in this link group
         */
        sock_hold(&smc->sk); /* sock_put in smc_lgr_unregister_conn() */
        while (!conn->alert_token_local) {
                conn->alert_token_local = atomic_inc_return(&nexttoken);
                if (smc_lgr_find_conn(conn->alert_token_local, conn->lgr))
                        conn->alert_token_local = 0;
        }
        smc_lgr_add_alert_token(conn);

        /* assign the new connection to a link */
        if (!conn->lgr->is_smcd) {
                struct smc_link *lnk;
                int i;

                /* tbd - link balancing */
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        lnk = &conn->lgr->lnk[i];
                        if (lnk->state == SMC_LNK_ACTIVATING ||
                            lnk->state == SMC_LNK_ACTIVE)
                                conn->lnk = lnk;
                }
                if (!conn->lnk)
                        return SMC_CLC_DECL_NOACTLINK;
        }
        conn->lgr->conns_num++;
        return 0;
}

/* Unregister connection and reset the alert token of the given connection<
 */
static void __smc_lgr_unregister_conn(struct smc_connection *conn)
{
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
        struct smc_link_group *lgr = conn->lgr;

        rb_erase(&conn->alert_node, &lgr->conns_all);
        lgr->conns_num--;
        conn->alert_token_local = 0;
        sock_put(&smc->sk); /* sock_hold in smc_lgr_register_conn() */
}

/* Unregister connection from lgr
 */
static void smc_lgr_unregister_conn(struct smc_connection *conn)
{
        struct smc_link_group *lgr = conn->lgr;

        if (!lgr)
                return;
        write_lock_bh(&lgr->conns_lock);
        if (conn->alert_token_local) {
                __smc_lgr_unregister_conn(conn);
        }
        write_unlock_bh(&lgr->conns_lock);
        conn->lgr = NULL;
}

void smc_lgr_cleanup_early(struct smc_connection *conn)
{
        struct smc_link_group *lgr = conn->lgr;
        struct list_head *lgr_list;
        spinlock_t *lgr_lock;

        if (!lgr)
                return;

        smc_conn_free(conn);
        lgr_list = smc_lgr_list_head(lgr, &lgr_lock);
        spin_lock_bh(lgr_lock);
        /* do not use this link group for new connections */
        if (!list_empty(lgr_list))
                list_del_init(lgr_list);
        spin_unlock_bh(lgr_lock);
        smc_lgr_schedule_free_work_fast(lgr);
}

static void smc_lgr_free(struct smc_link_group *lgr);

static void smc_lgr_free_work(struct work_struct *work)
{
        struct smc_link_group *lgr = container_of(to_delayed_work(work),
                                                  struct smc_link_group,
                                                  free_work);
        spinlock_t *lgr_lock;
        bool conns;
        int i;

        smc_lgr_list_head(lgr, &lgr_lock);
        spin_lock_bh(lgr_lock);
        if (lgr->freeing) {
                spin_unlock_bh(lgr_lock);
                return;
        }
        read_lock_bh(&lgr->conns_lock);
        conns = RB_EMPTY_ROOT(&lgr->conns_all);
        read_unlock_bh(&lgr->conns_lock);
        if (!conns) { /* number of lgr connections is no longer zero */
                spin_unlock_bh(lgr_lock);
                return;
        }
        list_del_init(&lgr->list); /* remove from smc_lgr_list */
        lgr->freeing = 1; /* this instance does the freeing, no new schedule */
        spin_unlock_bh(lgr_lock);
        cancel_delayed_work(&lgr->free_work);

        if (lgr->is_smcd && !lgr->terminating)
                smc_ism_signal_shutdown(lgr);
        if (!lgr->is_smcd) {
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        struct smc_link *lnk = &lgr->lnk[i];

                        if (smc_link_usable(lnk))
                                lnk->state = SMC_LNK_INACTIVE;
                }
                wake_up_interruptible_all(&lgr->llc_waiter);
        }
        smc_lgr_free(lgr);
}

static void smc_lgr_terminate_work(struct work_struct *work)
{
        struct smc_link_group *lgr = container_of(work, struct smc_link_group,
                                                  terminate_work);

        __smc_lgr_terminate(lgr, true);
}

/* return next unique link id for the lgr */
static u8 smcr_next_link_id(struct smc_link_group *lgr)
{
        u8 link_id;
        int i;

        while (1) {
                link_id = ++lgr->next_link_id;
                if (!link_id)   /* skip zero as link_id */
                        link_id = ++lgr->next_link_id;
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        if (smc_link_usable(&lgr->lnk[i]) &&
                            lgr->lnk[i].link_id == link_id)
                                continue;
                }
                break;
        }
        return link_id;
}

int smcr_link_init(struct smc_link_group *lgr, struct smc_link *lnk,
                   u8 link_idx, struct smc_init_info *ini)
{
        u8 rndvec[3];
        int rc;

        get_device(&ini->ib_dev->ibdev->dev);
        atomic_inc(&ini->ib_dev->lnk_cnt);
        lnk->state = SMC_LNK_ACTIVATING;
        lnk->link_id = smcr_next_link_id(lgr);
        lnk->lgr = lgr;
        lnk->link_idx = link_idx;
        lnk->smcibdev = ini->ib_dev;
        lnk->ibport = ini->ib_port;
        lnk->path_mtu = ini->ib_dev->pattr[ini->ib_port - 1].active_mtu;
        INIT_WORK(&lnk->link_down_wrk, smc_link_down_work);
        if (!ini->ib_dev->initialized) {
                rc = (int)smc_ib_setup_per_ibdev(ini->ib_dev);
                if (rc)
                        goto out;
        }
        get_random_bytes(rndvec, sizeof(rndvec));
        lnk->psn_initial = rndvec[0] + (rndvec[1] << 8) +
                (rndvec[2] << 16);
        rc = smc_ib_determine_gid(lnk->smcibdev, lnk->ibport,
                                  ini->vlan_id, lnk->gid, &lnk->sgid_index);
        if (rc)
                goto out;
        rc = smc_llc_link_init(lnk);
        if (rc)
                goto out;
        rc = smc_wr_alloc_link_mem(lnk);
        if (rc)
                goto clear_llc_lnk;
        rc = smc_ib_create_protection_domain(lnk);
        if (rc)
                goto free_link_mem;
        rc = smc_ib_create_queue_pair(lnk);
        if (rc)
                goto dealloc_pd;
        rc = smc_wr_create_link(lnk);
        if (rc)
                goto destroy_qp;
        return 0;

destroy_qp:
        smc_ib_destroy_queue_pair(lnk);
dealloc_pd:
        smc_ib_dealloc_protection_domain(lnk);
free_link_mem:
        smc_wr_free_link_mem(lnk);
clear_llc_lnk:
        smc_llc_link_clear(lnk);
out:
        put_device(&ini->ib_dev->ibdev->dev);
        memset(lnk, 0, sizeof(struct smc_link));
        lnk->state = SMC_LNK_UNUSED;
        if (!atomic_dec_return(&ini->ib_dev->lnk_cnt))
                wake_up(&ini->ib_dev->lnks_deleted);
        return rc;
}

/* create a new SMC link group */
static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini)
{
        struct smc_link_group *lgr;
        struct list_head *lgr_list;
        struct smc_link *lnk;
        spinlock_t *lgr_lock;
        u8 link_idx;
        int rc = 0;
        int i;

        if (ini->is_smcd && ini->vlan_id) {
                if (smc_ism_get_vlan(ini->ism_dev, ini->vlan_id)) {
                        rc = SMC_CLC_DECL_ISMVLANERR;
                        goto out;
                }
        }

        lgr = kzalloc(sizeof(*lgr), GFP_KERNEL);
        if (!lgr) {
                rc = SMC_CLC_DECL_MEM;
                goto ism_put_vlan;
        }
        lgr->is_smcd = ini->is_smcd;
        lgr->sync_err = 0;
        lgr->terminating = 0;
        lgr->freefast = 0;
        lgr->freeing = 0;
        lgr->vlan_id = ini->vlan_id;
        mutex_init(&lgr->sndbufs_lock);
        mutex_init(&lgr->rmbs_lock);
        rwlock_init(&lgr->conns_lock);
        for (i = 0; i < SMC_RMBE_SIZES; i++) {
                INIT_LIST_HEAD(&lgr->sndbufs[i]);
                INIT_LIST_HEAD(&lgr->rmbs[i]);
        }
        lgr->next_link_id = 0;
        smc_lgr_list.num += SMC_LGR_NUM_INCR;
        memcpy(&lgr->id, (u8 *)&smc_lgr_list.num, SMC_LGR_ID_SIZE);
        INIT_DELAYED_WORK(&lgr->free_work, smc_lgr_free_work);
        INIT_WORK(&lgr->terminate_work, smc_lgr_terminate_work);
        lgr->conns_all = RB_ROOT;
        if (ini->is_smcd) {
                /* SMC-D specific settings */
                get_device(&ini->ism_dev->dev);
                lgr->peer_gid = ini->ism_gid;
                lgr->smcd = ini->ism_dev;
                lgr_list = &ini->ism_dev->lgr_list;
                lgr_lock = &lgr->smcd->lgr_lock;
                lgr->peer_shutdown = 0;
                atomic_inc(&ini->ism_dev->lgr_cnt);
        } else {
                /* SMC-R specific settings */
                lgr->role = smc->listen_smc ? SMC_SERV : SMC_CLNT;
                memcpy(lgr->peer_systemid, ini->ib_lcl->id_for_peer,
                       SMC_SYSTEMID_LEN);
                memcpy(lgr->pnet_id, ini->ib_dev->pnetid[ini->ib_port - 1],
                       SMC_MAX_PNETID_LEN);
                smc_llc_lgr_init(lgr, smc);

                link_idx = SMC_SINGLE_LINK;
                lnk = &lgr->lnk[link_idx];
                rc = smcr_link_init(lgr, lnk, link_idx, ini);
                if (rc)
                        goto free_lgr;
                lgr_list = &smc_lgr_list.list;
                lgr_lock = &smc_lgr_list.lock;
                atomic_inc(&lgr_cnt);
        }
        smc->conn.lgr = lgr;
        spin_lock_bh(lgr_lock);
        list_add(&lgr->list, lgr_list);
        spin_unlock_bh(lgr_lock);
        return 0;

free_lgr:
        kfree(lgr);
ism_put_vlan:
        if (ini->is_smcd && ini->vlan_id)
                smc_ism_put_vlan(ini->ism_dev, ini->vlan_id);
out:
        if (rc < 0) {
                if (rc == -ENOMEM)
                        rc = SMC_CLC_DECL_MEM;
                else
                        rc = SMC_CLC_DECL_INTERR;
        }
        return rc;
}

static int smc_write_space(struct smc_connection *conn)
{
        int buffer_len = conn->peer_rmbe_size;
        union smc_host_cursor prod;
        union smc_host_cursor cons;
        int space;

        smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn);
        smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
        /* determine rx_buf space */
        space = buffer_len - smc_curs_diff(buffer_len, &cons, &prod);
        return space;
}

static int smc_switch_cursor(struct smc_sock *smc)
{
        struct smc_connection *conn = &smc->conn;
        union smc_host_cursor cons, fin;
        int rc = 0;
        int diff;

        smc_curs_copy(&conn->tx_curs_sent, &conn->tx_curs_fin, conn);
        smc_curs_copy(&fin, &conn->local_tx_ctrl_fin, conn);
        /* set prod cursor to old state, enforce tx_rdma_writes() */
        smc_curs_copy(&conn->local_tx_ctrl.prod, &fin, conn);
        smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);

        if (smc_curs_comp(conn->peer_rmbe_size, &cons, &fin) < 0) {
                /* cons cursor advanced more than fin, and prod was set
                 * fin above, so now prod is smaller than cons. Fix that.
                 */
                diff = smc_curs_diff(conn->peer_rmbe_size, &fin, &cons);
                smc_curs_add(conn->sndbuf_desc->len,
                             &conn->tx_curs_sent, diff);
                smc_curs_add(conn->sndbuf_desc->len,
                             &conn->tx_curs_fin, diff);

                smp_mb__before_atomic();
                atomic_add(diff, &conn->sndbuf_space);
                smp_mb__after_atomic();

                smc_curs_add(conn->peer_rmbe_size,
                             &conn->local_tx_ctrl.prod, diff);
                smc_curs_add(conn->peer_rmbe_size,
                             &conn->local_tx_ctrl_fin, diff);
        }
        /* recalculate, value is used by tx_rdma_writes() */
        atomic_set(&smc->conn.peer_rmbe_space, smc_write_space(conn));

        if (smc->sk.sk_state != SMC_INIT &&
            smc->sk.sk_state != SMC_CLOSED) {
                rc = smcr_cdc_msg_send_validation(conn);
                if (!rc) {
                        schedule_delayed_work(&conn->tx_work, 0);
                        smc->sk.sk_data_ready(&smc->sk);
                }
        }
        return rc;
}

struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
                                  struct smc_link *from_lnk, bool is_dev_err)
{
        struct smc_link *to_lnk = NULL;
        struct smc_connection *conn;
        struct smc_sock *smc;
        struct rb_node *node;
        int i, rc = 0;

        /* link is inactive, wake up tx waiters */
        smc_wr_wakeup_tx_wait(from_lnk);

        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                if (lgr->lnk[i].state != SMC_LNK_ACTIVE ||
                    i == from_lnk->link_idx)
                        continue;
                if (is_dev_err && from_lnk->smcibdev == lgr->lnk[i].smcibdev &&
                    from_lnk->ibport == lgr->lnk[i].ibport) {
                        continue;
                }
                to_lnk = &lgr->lnk[i];
                break;
        }
        if (!to_lnk) {
                smc_lgr_terminate_sched(lgr);
                return NULL;
        }
again:
        read_lock_bh(&lgr->conns_lock);
        for (node = rb_first(&lgr->conns_all); node; node = rb_next(node)) {
                conn = rb_entry(node, struct smc_connection, alert_node);
                if (conn->lnk != from_lnk)
                        continue;
                smc = container_of(conn, struct smc_sock, conn);
                /* conn->lnk not yet set in SMC_INIT state */
                if (smc->sk.sk_state == SMC_INIT)
                        continue;
                if (smc->sk.sk_state == SMC_CLOSED ||
                    smc->sk.sk_state == SMC_PEERCLOSEWAIT1 ||
                    smc->sk.sk_state == SMC_PEERCLOSEWAIT2 ||
                    smc->sk.sk_state == SMC_APPFINCLOSEWAIT ||
                    smc->sk.sk_state == SMC_APPCLOSEWAIT1 ||
                    smc->sk.sk_state == SMC_APPCLOSEWAIT2 ||
                    smc->sk.sk_state == SMC_PEERFINCLOSEWAIT ||
                    smc->sk.sk_state == SMC_PEERABORTWAIT ||
                    smc->sk.sk_state == SMC_PROCESSABORT) {
                        spin_lock_bh(&conn->send_lock);
                        conn->lnk = to_lnk;
                        spin_unlock_bh(&conn->send_lock);
                        continue;
                }
                sock_hold(&smc->sk);
                read_unlock_bh(&lgr->conns_lock);
                /* avoid race with smcr_tx_sndbuf_nonempty() */
                spin_lock_bh(&conn->send_lock);
                conn->lnk = to_lnk;
                rc = smc_switch_cursor(smc);
                spin_unlock_bh(&conn->send_lock);
                sock_put(&smc->sk);
                if (rc) {
                        smcr_link_down_cond_sched(to_lnk);
                        return NULL;
                }
                goto again;
        }
        read_unlock_bh(&lgr->conns_lock);
        return to_lnk;
}

static void smcr_buf_unuse(struct smc_buf_desc *rmb_desc,
                           struct smc_link_group *lgr)
{
        int rc;

        if (rmb_desc->is_conf_rkey && !list_empty(&lgr->list)) {
                /* unregister rmb with peer */
                rc = smc_llc_flow_initiate(lgr, SMC_LLC_FLOW_RKEY);
                if (!rc) {
                        /* protect against smc_llc_cli_rkey_exchange() */
                        mutex_lock(&lgr->llc_conf_mutex);
                        smc_llc_do_delete_rkey(lgr, rmb_desc);
                        rmb_desc->is_conf_rkey = false;
                        mutex_unlock(&lgr->llc_conf_mutex);
                        smc_llc_flow_stop(lgr, &lgr->llc_flow_lcl);
                }
        }

        if (rmb_desc->is_reg_err) {
                /* buf registration failed, reuse not possible */
                mutex_lock(&lgr->rmbs_lock);
                list_del(&rmb_desc->list);
                mutex_unlock(&lgr->rmbs_lock);

                smc_buf_free(lgr, true, rmb_desc);
        } else {
                rmb_desc->used = 0;
        }
}

static void smc_buf_unuse(struct smc_connection *conn,
                          struct smc_link_group *lgr)
{
        if (conn->sndbuf_desc)
                conn->sndbuf_desc->used = 0;
        if (conn->rmb_desc && lgr->is_smcd)
                conn->rmb_desc->used = 0;
        else if (conn->rmb_desc)
                smcr_buf_unuse(conn->rmb_desc, lgr);
}

/* remove a finished connection from its link group */
void smc_conn_free(struct smc_connection *conn)
{
        struct smc_link_group *lgr = conn->lgr;

        if (!lgr)
                return;
        if (lgr->is_smcd) {
                if (!list_empty(&lgr->list))
                        smc_ism_unset_conn(conn);
                tasklet_kill(&conn->rx_tsklet);
        } else {
                smc_cdc_tx_dismiss_slots(conn);
        }
        if (!list_empty(&lgr->list)) {
                smc_lgr_unregister_conn(conn);
                smc_buf_unuse(conn, lgr); /* allow buffer reuse */
        }

        if (!lgr->conns_num)
                smc_lgr_schedule_free_work(lgr);
}

/* unregister a link from a buf_desc */
static void smcr_buf_unmap_link(struct smc_buf_desc *buf_desc, bool is_rmb,
                                struct smc_link *lnk)
{
        if (is_rmb)
                buf_desc->is_reg_mr[lnk->link_idx] = false;
        if (!buf_desc->is_map_ib[lnk->link_idx])
                return;
        if (is_rmb) {
                if (buf_desc->mr_rx[lnk->link_idx]) {
                        smc_ib_put_memory_region(
                                        buf_desc->mr_rx[lnk->link_idx]);
                        buf_desc->mr_rx[lnk->link_idx] = NULL;
                }
                smc_ib_buf_unmap_sg(lnk, buf_desc, DMA_FROM_DEVICE);
        } else {
                smc_ib_buf_unmap_sg(lnk, buf_desc, DMA_TO_DEVICE);
        }
        sg_free_table(&buf_desc->sgt[lnk->link_idx]);
        buf_desc->is_map_ib[lnk->link_idx] = false;
}

/* unmap all buffers of lgr for a deleted link */
static void smcr_buf_unmap_lgr(struct smc_link *lnk)
{
        struct smc_link_group *lgr = lnk->lgr;
        struct smc_buf_desc *buf_desc, *bf;
        int i;

        for (i = 0; i < SMC_RMBE_SIZES; i++) {
                mutex_lock(&lgr->rmbs_lock);
                list_for_each_entry_safe(buf_desc, bf, &lgr->rmbs[i], list)
                        smcr_buf_unmap_link(buf_desc, true, lnk);
                mutex_unlock(&lgr->rmbs_lock);
                mutex_lock(&lgr->sndbufs_lock);
                list_for_each_entry_safe(buf_desc, bf, &lgr->sndbufs[i],
                                         list)
                        smcr_buf_unmap_link(buf_desc, false, lnk);
                mutex_unlock(&lgr->sndbufs_lock);
        }
}

static void smcr_rtoken_clear_link(struct smc_link *lnk)
{
        struct smc_link_group *lgr = lnk->lgr;
        int i;

        for (i = 0; i < SMC_RMBS_PER_LGR_MAX; i++) {
                lgr->rtokens[i][lnk->link_idx].rkey = 0;
                lgr->rtokens[i][lnk->link_idx].dma_addr = 0;
        }
}

/* must be called under lgr->llc_conf_mutex lock */
void smcr_link_clear(struct smc_link *lnk)
{
        struct smc_ib_device *smcibdev;

        if (!lnk->lgr || lnk->state == SMC_LNK_UNUSED)
                return;
        lnk->peer_qpn = 0;
        smc_llc_link_clear(lnk);
        smcr_buf_unmap_lgr(lnk);
        smcr_rtoken_clear_link(lnk);
        smc_ib_modify_qp_reset(lnk);
        smc_wr_free_link(lnk);
        smc_ib_destroy_queue_pair(lnk);
        smc_ib_dealloc_protection_domain(lnk);
        smc_wr_free_link_mem(lnk);
        put_device(&lnk->smcibdev->ibdev->dev);
        smcibdev = lnk->smcibdev;
        memset(lnk, 0, sizeof(struct smc_link));
        lnk->state = SMC_LNK_UNUSED;
        if (!atomic_dec_return(&smcibdev->lnk_cnt))
                wake_up(&smcibdev->lnks_deleted);
}

static void smcr_buf_free(struct smc_link_group *lgr, bool is_rmb,
                          struct smc_buf_desc *buf_desc)
{
        int i;

        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++)
                smcr_buf_unmap_link(buf_desc, is_rmb, &lgr->lnk[i]);

        if (buf_desc->pages)
                __free_pages(buf_desc->pages, buf_desc->order);
        kfree(buf_desc);
}

static void smcd_buf_free(struct smc_link_group *lgr, bool is_dmb,
                          struct smc_buf_desc *buf_desc)
{
        if (is_dmb) {
                /* restore original buf len */
                buf_desc->len += sizeof(struct smcd_cdc_msg);
                smc_ism_unregister_dmb(lgr->smcd, buf_desc);
        } else {
                kfree(buf_desc->cpu_addr);
        }
        kfree(buf_desc);
}

static void smc_buf_free(struct smc_link_group *lgr, bool is_rmb,
                         struct smc_buf_desc *buf_desc)
{
        if (lgr->is_smcd)
                smcd_buf_free(lgr, is_rmb, buf_desc);
        else
                smcr_buf_free(lgr, is_rmb, buf_desc);
}

static void __smc_lgr_free_bufs(struct smc_link_group *lgr, bool is_rmb)
{
        struct smc_buf_desc *buf_desc, *bf_desc;
        struct list_head *buf_list;
        int i;

        for (i = 0; i < SMC_RMBE_SIZES; i++) {
                if (is_rmb)
                        buf_list = &lgr->rmbs[i];
                else
                        buf_list = &lgr->sndbufs[i];
                list_for_each_entry_safe(buf_desc, bf_desc, buf_list,
                                         list) {
                        list_del(&buf_desc->list);
                        smc_buf_free(lgr, is_rmb, buf_desc);
                }
        }
}

static void smc_lgr_free_bufs(struct smc_link_group *lgr)
{
        /* free send buffers */
        __smc_lgr_free_bufs(lgr, false);
        /* free rmbs */
        __smc_lgr_free_bufs(lgr, true);
}

/* remove a link group */
static void smc_lgr_free(struct smc_link_group *lgr)
{
        int i;

        smc_lgr_free_bufs(lgr);
        if (lgr->is_smcd) {
                if (!lgr->terminating) {
                        smc_ism_put_vlan(lgr->smcd, lgr->vlan_id);
                        put_device(&lgr->smcd->dev);
                }
                if (!atomic_dec_return(&lgr->smcd->lgr_cnt))
                        wake_up(&lgr->smcd->lgrs_deleted);
        } else {
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        if (lgr->lnk[i].state != SMC_LNK_UNUSED)
                                smcr_link_clear(&lgr->lnk[i]);
                }
                smc_llc_lgr_clear(lgr);
                if (!atomic_dec_return(&lgr_cnt))
                        wake_up(&lgrs_deleted);
        }
        kfree(lgr);
}

static void smcd_unregister_all_dmbs(struct smc_link_group *lgr)
{
        int i;

        for (i = 0; i < SMC_RMBE_SIZES; i++) {
                struct smc_buf_desc *buf_desc;

                list_for_each_entry(buf_desc, &lgr->rmbs[i], list) {
                        buf_desc->len += sizeof(struct smcd_cdc_msg);
                        smc_ism_unregister_dmb(lgr->smcd, buf_desc);
                }
        }
}

static void smc_sk_wake_ups(struct smc_sock *smc)
{
        smc->sk.sk_write_space(&smc->sk);
        smc->sk.sk_data_ready(&smc->sk);
        smc->sk.sk_state_change(&smc->sk);
}

/* kill a connection */
static void smc_conn_kill(struct smc_connection *conn, bool soft)
{
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);

        if (conn->lgr->is_smcd && conn->lgr->peer_shutdown)
                conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
        else
                smc_close_abort(conn);
        conn->killed = 1;
        smc->sk.sk_err = ECONNABORTED;
        smc_sk_wake_ups(smc);
        if (conn->lgr->is_smcd) {
                smc_ism_unset_conn(conn);
                if (soft)
                        tasklet_kill(&conn->rx_tsklet);
                else
                        tasklet_unlock_wait(&conn->rx_tsklet);
        } else {
                smc_cdc_tx_dismiss_slots(conn);
        }
        smc_lgr_unregister_conn(conn);
        smc_close_active_abort(smc);
}

static void smc_lgr_cleanup(struct smc_link_group *lgr)
{
        int i;

        if (lgr->is_smcd) {
                smc_ism_signal_shutdown(lgr);
                smcd_unregister_all_dmbs(lgr);
                smc_ism_put_vlan(lgr->smcd, lgr->vlan_id);
                put_device(&lgr->smcd->dev);
        } else {
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        struct smc_link *lnk = &lgr->lnk[i];

                        if (smc_link_usable(lnk))
                                lnk->state = SMC_LNK_INACTIVE;
                }
                wake_up_interruptible_all(&lgr->llc_waiter);
        }
}

/* terminate link group
 * @soft: true if link group shutdown can take its time
 *        false if immediate link group shutdown is required
 */
static void __smc_lgr_terminate(struct smc_link_group *lgr, bool soft)
{
        struct smc_connection *conn;
        struct smc_sock *smc;
        struct rb_node *node;

        if (lgr->terminating)
                return; /* lgr already terminating */
        if (!soft)
                cancel_delayed_work_sync(&lgr->free_work);
        lgr->terminating = 1;

        /* kill remaining link group connections */
        read_lock_bh(&lgr->conns_lock);
        node = rb_first(&lgr->conns_all);
        while (node) {
                read_unlock_bh(&lgr->conns_lock);
                conn = rb_entry(node, struct smc_connection, alert_node);
                smc = container_of(conn, struct smc_sock, conn);
                sock_hold(&smc->sk); /* sock_put below */
                lock_sock(&smc->sk);
                smc_conn_kill(conn, soft);
                release_sock(&smc->sk);
                sock_put(&smc->sk); /* sock_hold above */
                read_lock_bh(&lgr->conns_lock);
                node = rb_first(&lgr->conns_all);
        }
        read_unlock_bh(&lgr->conns_lock);
        smc_lgr_cleanup(lgr);
        if (soft)
                smc_lgr_schedule_free_work_fast(lgr);
        else
                smc_lgr_free(lgr);
}

/* unlink link group and schedule termination */
void smc_lgr_terminate_sched(struct smc_link_group *lgr)
{
        spinlock_t *lgr_lock;

        smc_lgr_list_head(lgr, &lgr_lock);
        spin_lock_bh(lgr_lock);
        if (list_empty(&lgr->list) || lgr->terminating || lgr->freeing) {
                spin_unlock_bh(lgr_lock);
                return; /* lgr already terminating */
        }
        list_del_init(&lgr->list);
        spin_unlock_bh(lgr_lock);
        schedule_work(&lgr->terminate_work);
}

/* Called when peer lgr shutdown (regularly or abnormally) is received */
void smc_smcd_terminate(struct smcd_dev *dev, u64 peer_gid, unsigned short vlan)
{
        struct smc_link_group *lgr, *l;
        LIST_HEAD(lgr_free_list);

        /* run common cleanup function and build free list */
        spin_lock_bh(&dev->lgr_lock);
        list_for_each_entry_safe(lgr, l, &dev->lgr_list, list) {
                if ((!peer_gid || lgr->peer_gid == peer_gid) &&
                    (vlan == VLAN_VID_MASK || lgr->vlan_id == vlan)) {
                        if (peer_gid) /* peer triggered termination */
                                lgr->peer_shutdown = 1;
                        list_move(&lgr->list, &lgr_free_list);
                }
        }
        spin_unlock_bh(&dev->lgr_lock);

        /* cancel the regular free workers and actually free lgrs */
        list_for_each_entry_safe(lgr, l, &lgr_free_list, list) {
                list_del_init(&lgr->list);
                schedule_work(&lgr->terminate_work);
        }
}

/* Called when an SMCD device is removed or the smc module is unloaded */
void smc_smcd_terminate_all(struct smcd_dev *smcd)
{
        struct smc_link_group *lgr, *lg;
        LIST_HEAD(lgr_free_list);

        spin_lock_bh(&smcd->lgr_lock);
        list_splice_init(&smcd->lgr_list, &lgr_free_list);
        list_for_each_entry(lgr, &lgr_free_list, list)
                lgr->freeing = 1;
        spin_unlock_bh(&smcd->lgr_lock);

        list_for_each_entry_safe(lgr, lg, &lgr_free_list, list) {
                list_del_init(&lgr->list);
                __smc_lgr_terminate(lgr, false);
        }

        if (atomic_read(&smcd->lgr_cnt))
                wait_event(smcd->lgrs_deleted, !atomic_read(&smcd->lgr_cnt));
}

/* Called when an SMCR device is removed or the smc module is unloaded.
 * If smcibdev is given, all SMCR link groups using this device are terminated.
 * If smcibdev is NULL, all SMCR link groups are terminated.
 */
void smc_smcr_terminate_all(struct smc_ib_device *smcibdev)
{
        struct smc_link_group *lgr, *lg;
        LIST_HEAD(lgr_free_list);
        int i;

        spin_lock_bh(&smc_lgr_list.lock);
        if (!smcibdev) {
                list_splice_init(&smc_lgr_list.list, &lgr_free_list);
                list_for_each_entry(lgr, &lgr_free_list, list)
                        lgr->freeing = 1;
        } else {
                list_for_each_entry_safe(lgr, lg, &smc_lgr_list.list, list) {
                        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                                if (lgr->lnk[i].smcibdev == smcibdev)
                                        smcr_link_down_cond_sched(&lgr->lnk[i]);
                        }
                }
        }
        spin_unlock_bh(&smc_lgr_list.lock);

        list_for_each_entry_safe(lgr, lg, &lgr_free_list, list) {
                list_del_init(&lgr->list);
                __smc_lgr_terminate(lgr, false);
        }

        if (smcibdev) {
                if (atomic_read(&smcibdev->lnk_cnt))
                        wait_event(smcibdev->lnks_deleted,
                                   !atomic_read(&smcibdev->lnk_cnt));
        } else {
                if (atomic_read(&lgr_cnt))
                        wait_event(lgrs_deleted, !atomic_read(&lgr_cnt));
        }
}

/* link is up - establish alternate link if applicable */
static void smcr_link_up(struct smc_link_group *lgr,
                         struct smc_ib_device *smcibdev, u8 ibport)
{
        struct smc_link *link = NULL;

        if (list_empty(&lgr->list) ||
            lgr->type == SMC_LGR_SYMMETRIC ||
            lgr->type == SMC_LGR_ASYMMETRIC_PEER)
                return;

        if (lgr->role == SMC_SERV) {
                /* trigger local add link processing */
                link = smc_llc_usable_link(lgr);
                if (!link)
                        return;
                smc_llc_srv_add_link_local(link);
        } else {
                /* invite server to start add link processing */
                u8 gid[SMC_GID_SIZE];

                if (smc_ib_determine_gid(smcibdev, ibport, lgr->vlan_id, gid,
                                         NULL))
                        return;
                if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
                        /* some other llc task is ongoing */
                        wait_event_interruptible_timeout(lgr->llc_waiter,
                                (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
                                SMC_LLC_WAIT_TIME);
                }
                if (list_empty(&lgr->list) ||
                    !smc_ib_port_active(smcibdev, ibport))
                        return; /* lgr or device no longer active */
                link = smc_llc_usable_link(lgr);
                if (!link)
                        return;
                smc_llc_send_add_link(link, smcibdev->mac[ibport - 1], gid,
                                      NULL, SMC_LLC_REQ);
        }
}

void smcr_port_add(struct smc_ib_device *smcibdev, u8 ibport)
{
        struct smc_ib_up_work *ib_work;
        struct smc_link_group *lgr, *n;

        list_for_each_entry_safe(lgr, n, &smc_lgr_list.list, list) {
                if (strncmp(smcibdev->pnetid[ibport - 1], lgr->pnet_id,
                            SMC_MAX_PNETID_LEN) ||
                    lgr->type == SMC_LGR_SYMMETRIC ||
                    lgr->type == SMC_LGR_ASYMMETRIC_PEER)
                        continue;
                ib_work = kmalloc(sizeof(*ib_work), GFP_KERNEL);
                if (!ib_work)
                        continue;
                INIT_WORK(&ib_work->work, smc_link_up_work);
                ib_work->lgr = lgr;
                ib_work->smcibdev = smcibdev;
                ib_work->ibport = ibport;
                schedule_work(&ib_work->work);
        }
}

/* link is down - switch connections to alternate link,
 * must be called under lgr->llc_conf_mutex lock
 */
static void smcr_link_down(struct smc_link *lnk)
{
        struct smc_link_group *lgr = lnk->lgr;
        struct smc_link *to_lnk;
        int del_link_id;

        if (!lgr || lnk->state == SMC_LNK_UNUSED || list_empty(&lgr->list))
                return;

        smc_ib_modify_qp_reset(lnk);
        to_lnk = smc_switch_conns(lgr, lnk, true);
        if (!to_lnk) { /* no backup link available */
                smcr_link_clear(lnk);
                return;
        }
        lgr->type = SMC_LGR_SINGLE;
        del_link_id = lnk->link_id;

        if (lgr->role == SMC_SERV) {
                /* trigger local delete link processing */
                smc_llc_srv_delete_link_local(to_lnk, del_link_id);
        } else {
                if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
                        /* another llc task is ongoing */
                        mutex_unlock(&lgr->llc_conf_mutex);
                        wait_event_interruptible_timeout(lgr->llc_waiter,
                                (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
                                SMC_LLC_WAIT_TIME);
                        mutex_lock(&lgr->llc_conf_mutex);
                }
                smc_llc_send_delete_link(to_lnk, del_link_id, SMC_LLC_REQ, true,
                                         SMC_LLC_DEL_LOST_PATH);
        }
}

/* must be called under lgr->llc_conf_mutex lock */
void smcr_link_down_cond(struct smc_link *lnk)
{
        if (smc_link_downing(&lnk->state))
                smcr_link_down(lnk);
}

/* will get the lgr->llc_conf_mutex lock */
void smcr_link_down_cond_sched(struct smc_link *lnk)
{
        if (smc_link_downing(&lnk->state))
                schedule_work(&lnk->link_down_wrk);
}

void smcr_port_err(struct smc_ib_device *smcibdev, u8 ibport)
{
        struct smc_link_group *lgr, *n;
        int i;

        list_for_each_entry_safe(lgr, n, &smc_lgr_list.list, list) {
                if (strncmp(smcibdev->pnetid[ibport - 1], lgr->pnet_id,
                            SMC_MAX_PNETID_LEN))
                        continue; /* lgr is not affected */
                if (list_empty(&lgr->list))
                        continue;
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        struct smc_link *lnk = &lgr->lnk[i];

                        if (smc_link_usable(lnk) &&
                            lnk->smcibdev == smcibdev && lnk->ibport == ibport)
                                smcr_link_down_cond_sched(lnk);
                }
        }
}

static void smc_link_up_work(struct work_struct *work)
{
        struct smc_ib_up_work *ib_work = container_of(work,
                                                      struct smc_ib_up_work,
                                                      work);
        struct smc_link_group *lgr = ib_work->lgr;

        if (list_empty(&lgr->list))
                goto out;
        smcr_link_up(lgr, ib_work->smcibdev, ib_work->ibport);
out:
        kfree(ib_work);
}

static void smc_link_down_work(struct work_struct *work)
{
        struct smc_link *link = container_of(work, struct smc_link,
                                             link_down_wrk);
        struct smc_link_group *lgr = link->lgr;

        if (list_empty(&lgr->list))
                return;
        wake_up_interruptible_all(&lgr->llc_waiter);
        mutex_lock(&lgr->llc_conf_mutex);
        smcr_link_down(link);
        mutex_unlock(&lgr->llc_conf_mutex);
}

/* Determine vlan of internal TCP socket.
 * @vlan_id: address to store the determined vlan id into
 */
int smc_vlan_by_tcpsk(struct socket *clcsock, struct smc_init_info *ini)
{
        struct dst_entry *dst = sk_dst_get(clcsock->sk);
        struct net_device *ndev;
        int i, nest_lvl, rc = 0;

        ini->vlan_id = 0;
        if (!dst) {
                rc = -ENOTCONN;
                goto out;
        }
        if (!dst->dev) {
                rc = -ENODEV;
                goto out_rel;
        }

        ndev = dst->dev;
        if (is_vlan_dev(ndev)) {
                ini->vlan_id = vlan_dev_vlan_id(ndev);
                goto out_rel;
        }

        rtnl_lock();
        nest_lvl = ndev->lower_level;
        for (i = 0; i < nest_lvl; i++) {
                struct list_head *lower = &ndev->adj_list.lower;

                if (list_empty(lower))
                        break;
                lower = lower->next;
                ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower);
                if (is_vlan_dev(ndev)) {
                        ini->vlan_id = vlan_dev_vlan_id(ndev);
                        break;
                }
        }
        rtnl_unlock();

out_rel:
        dst_release(dst);
out:
        return rc;
}

static bool smcr_lgr_match(struct smc_link_group *lgr,
                           struct smc_clc_msg_local *lcl,
                           enum smc_lgr_role role, u32 clcqpn)
{
        int i;

        if (memcmp(lgr->peer_systemid, lcl->id_for_peer, SMC_SYSTEMID_LEN) ||
            lgr->role != role)
                return false;

        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                if (lgr->lnk[i].state != SMC_LNK_ACTIVE)
                        continue;
                if ((lgr->role == SMC_SERV || lgr->lnk[i].peer_qpn == clcqpn) &&
                    !memcmp(lgr->lnk[i].peer_gid, &lcl->gid, SMC_GID_SIZE) &&
                    !memcmp(lgr->lnk[i].peer_mac, lcl->mac, sizeof(lcl->mac)))
                        return true;
        }
        return false;
}

static bool smcd_lgr_match(struct smc_link_group *lgr,
                           struct smcd_dev *smcismdev, u64 peer_gid)
{
        return lgr->peer_gid == peer_gid && lgr->smcd == smcismdev;
}

/* create a new SMC connection (and a new link group if necessary) */
int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini)
{
        struct smc_connection *conn = &smc->conn;
        struct list_head *lgr_list;
        struct smc_link_group *lgr;
        enum smc_lgr_role role;
        spinlock_t *lgr_lock;
        int rc = 0;

        lgr_list = ini->is_smcd ? &ini->ism_dev->lgr_list : &smc_lgr_list.list;
        lgr_lock = ini->is_smcd ? &ini->ism_dev->lgr_lock : &smc_lgr_list.lock;
        ini->cln_first_contact = SMC_FIRST_CONTACT;
        role = smc->listen_smc ? SMC_SERV : SMC_CLNT;
        if (role == SMC_CLNT && ini->srv_first_contact)
                /* create new link group as well */
                goto create;

        /* determine if an existing link group can be reused */
        spin_lock_bh(lgr_lock);
        list_for_each_entry(lgr, lgr_list, list) {
                write_lock_bh(&lgr->conns_lock);
                if ((ini->is_smcd ?
                     smcd_lgr_match(lgr, ini->ism_dev, ini->ism_gid) :
                     smcr_lgr_match(lgr, ini->ib_lcl, role, ini->ib_clcqpn)) &&
                    !lgr->sync_err &&
                    lgr->vlan_id == ini->vlan_id &&
                    (role == SMC_CLNT ||
                     lgr->conns_num < SMC_RMBS_PER_LGR_MAX)) {
                        /* link group found */
                        ini->cln_first_contact = SMC_REUSE_CONTACT;
                        conn->lgr = lgr;
                        rc = smc_lgr_register_conn(conn); /* add conn to lgr */
                        write_unlock_bh(&lgr->conns_lock);
                        if (!rc && delayed_work_pending(&lgr->free_work))
                                cancel_delayed_work(&lgr->free_work);
                        break;
                }
                write_unlock_bh(&lgr->conns_lock);
        }
        spin_unlock_bh(lgr_lock);
        if (rc)
                return rc;

        if (role == SMC_CLNT && !ini->srv_first_contact &&
            ini->cln_first_contact == SMC_FIRST_CONTACT) {
                /* Server reuses a link group, but Client wants to start
                 * a new one
                 * send out_of_sync decline, reason synchr. error
                 */
                return SMC_CLC_DECL_SYNCERR;
        }

create:
        if (ini->cln_first_contact == SMC_FIRST_CONTACT) {
                rc = smc_lgr_create(smc, ini);
                if (rc)
                        goto out;
                lgr = conn->lgr;
                write_lock_bh(&lgr->conns_lock);
                rc = smc_lgr_register_conn(conn); /* add smc conn to lgr */
                write_unlock_bh(&lgr->conns_lock);
                if (rc)
                        goto out;
        }
        conn->local_tx_ctrl.common.type = SMC_CDC_MSG_TYPE;
        conn->local_tx_ctrl.len = SMC_WR_TX_SIZE;
        conn->urg_state = SMC_URG_READ;
        if (ini->is_smcd) {
                conn->rx_off = sizeof(struct smcd_cdc_msg);
                smcd_cdc_rx_init(conn); /* init tasklet for this conn */
        }
#ifndef KERNEL_HAS_ATOMIC64
        spin_lock_init(&conn->acurs_lock);
#endif

out:
        return rc;
}

/* convert the RMB size into the compressed notation - minimum 16K.
 * In contrast to plain ilog2, this rounds towards the next power of 2,
 * so the socket application gets at least its desired sndbuf / rcvbuf size.
 */
static u8 smc_compress_bufsize(int size)
{
        u8 compressed;

        if (size <= SMC_BUF_MIN_SIZE)
                return 0;

        size = (size - 1) >> 14;
        compressed = ilog2(size) + 1;
        if (compressed >= SMC_RMBE_SIZES)
                compressed = SMC_RMBE_SIZES - 1;
        return compressed;
}

/* convert the RMB size from compressed notation into integer */
int smc_uncompress_bufsize(u8 compressed)
{
        u32 size;

        size = 0x00000001 << (((int)compressed) + 14);
        return (int)size;
}

/* try to reuse a sndbuf or rmb description slot for a certain
 * buffer size; if not available, return NULL
 */
static struct smc_buf_desc *smc_buf_get_slot(int compressed_bufsize,
                                             struct mutex *lock,
                                             struct list_head *buf_list)
{
        struct smc_buf_desc *buf_slot;

        mutex_lock(lock);
        list_for_each_entry(buf_slot, buf_list, list) {
                if (cmpxchg(&buf_slot->used, 0, 1) == 0) {
                        mutex_unlock(lock);
                        return buf_slot;
                }
        }
        mutex_unlock(lock);
        return NULL;
}

/* one of the conditions for announcing a receiver's current window size is
 * that it "results in a minimum increase in the window size of 10% of the
 * receive buffer space" [RFC7609]
 */
static inline int smc_rmb_wnd_update_limit(int rmbe_size)
{
        return min_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2);
}

/* map an rmb buf to a link */
static int smcr_buf_map_link(struct smc_buf_desc *buf_desc, bool is_rmb,
                             struct smc_link *lnk)
{
        int rc;

        if (buf_desc->is_map_ib[lnk->link_idx])
                return 0;

        rc = sg_alloc_table(&buf_desc->sgt[lnk->link_idx], 1, GFP_KERNEL);
        if (rc)
                return rc;
        sg_set_buf(buf_desc->sgt[lnk->link_idx].sgl,
                   buf_desc->cpu_addr, buf_desc->len);

        /* map sg table to DMA address */
        rc = smc_ib_buf_map_sg(lnk, buf_desc,
                               is_rmb ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
        /* SMC protocol depends on mapping to one DMA address only */
        if (rc != 1) {
                rc = -EAGAIN;
                goto free_table;
        }

        /* create a new memory region for the RMB */
        if (is_rmb) {
                rc = smc_ib_get_memory_region(lnk->roce_pd,
                                              IB_ACCESS_REMOTE_WRITE |
                                              IB_ACCESS_LOCAL_WRITE,
                                              buf_desc, lnk->link_idx);
                if (rc)
                        goto buf_unmap;
                smc_ib_sync_sg_for_device(lnk, buf_desc, DMA_FROM_DEVICE);
        }
        buf_desc->is_map_ib[lnk->link_idx] = true;
        return 0;

buf_unmap:
        smc_ib_buf_unmap_sg(lnk, buf_desc,
                            is_rmb ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
free_table:
        sg_free_table(&buf_desc->sgt[lnk->link_idx]);
        return rc;
}

/* register a new rmb on IB device,
 * must be called under lgr->llc_conf_mutex lock
 */
int smcr_link_reg_rmb(struct smc_link *link, struct smc_buf_desc *rmb_desc)
{
        if (list_empty(&link->lgr->list))
                return -ENOLINK;
        if (!rmb_desc->is_reg_mr[link->link_idx]) {
                /* register memory region for new rmb */
                if (smc_wr_reg_send(link, rmb_desc->mr_rx[link->link_idx])) {
                        rmb_desc->is_reg_err = true;
                        return -EFAULT;
                }
                rmb_desc->is_reg_mr[link->link_idx] = true;
        }
        return 0;
}

static int _smcr_buf_map_lgr(struct smc_link *lnk, struct mutex *lock,
                             struct list_head *lst, bool is_rmb)
{
        struct smc_buf_desc *buf_desc, *bf;
        int rc = 0;

        mutex_lock(lock);
        list_for_each_entry_safe(buf_desc, bf, lst, list) {
                if (!buf_desc->used)
                        continue;
                rc = smcr_buf_map_link(buf_desc, is_rmb, lnk);
                if (rc)
                        goto out;
        }
out:
        mutex_unlock(lock);
        return rc;
}

/* map all used buffers of lgr for a new link */
int smcr_buf_map_lgr(struct smc_link *lnk)
{
        struct smc_link_group *lgr = lnk->lgr;
        int i, rc = 0;

        for (i = 0; i < SMC_RMBE_SIZES; i++) {
                rc = _smcr_buf_map_lgr(lnk, &lgr->rmbs_lock,
                                       &lgr->rmbs[i], true);
                if (rc)
                        return rc;
                rc = _smcr_buf_map_lgr(lnk, &lgr->sndbufs_lock,
                                       &lgr->sndbufs[i], false);
                if (rc)
                        return rc;
        }
        return 0;
}

/* register all used buffers of lgr for a new link,
 * must be called under lgr->llc_conf_mutex lock
 */
int smcr_buf_reg_lgr(struct smc_link *lnk)
{
        struct smc_link_group *lgr = lnk->lgr;
        struct smc_buf_desc *buf_desc, *bf;
        int i, rc = 0;

        mutex_lock(&lgr->rmbs_lock);
        for (i = 0; i < SMC_RMBE_SIZES; i++) {
                list_for_each_entry_safe(buf_desc, bf, &lgr->rmbs[i], list) {
                        if (!buf_desc->used)
                                continue;
                        rc = smcr_link_reg_rmb(lnk, buf_desc);
                        if (rc)
                                goto out;
                }
        }
out:
        mutex_unlock(&lgr->rmbs_lock);
        return rc;
}

static struct smc_buf_desc *smcr_new_buf_create(struct smc_link_group *lgr,
                                                bool is_rmb, int bufsize)
{
        struct smc_buf_desc *buf_desc;

        /* try to alloc a new buffer */
        buf_desc = kzalloc(sizeof(*buf_desc), GFP_KERNEL);
        if (!buf_desc)
                return ERR_PTR(-ENOMEM);

        buf_desc->order = get_order(bufsize);
        buf_desc->pages = alloc_pages(GFP_KERNEL | __GFP_NOWARN |
                                      __GFP_NOMEMALLOC | __GFP_COMP |
                                      __GFP_NORETRY | __GFP_ZERO,
                                      buf_desc->order);
        if (!buf_desc->pages) {
                kfree(buf_desc);
                return ERR_PTR(-EAGAIN);
        }
        buf_desc->cpu_addr = (void *)page_address(buf_desc->pages);
        buf_desc->len = bufsize;
        return buf_desc;
}

/* map buf_desc on all usable links,
 * unused buffers stay mapped as long as the link is up
 */
static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
                                     struct smc_buf_desc *buf_desc, bool is_rmb)
{
        int i, rc = 0;

        /* protect against parallel link reconfiguration */
        mutex_lock(&lgr->llc_conf_mutex);
        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                struct smc_link *lnk = &lgr->lnk[i];

                if (!smc_link_usable(lnk))
                        continue;
                if (smcr_buf_map_link(buf_desc, is_rmb, lnk)) {
                        rc = -ENOMEM;
                        goto out;
                }
        }
out:
        mutex_unlock(&lgr->llc_conf_mutex);
        return rc;
}

#define SMCD_DMBE_SIZES         7 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */

static struct smc_buf_desc *smcd_new_buf_create(struct smc_link_group *lgr,
                                                bool is_dmb, int bufsize)
{
        struct smc_buf_desc *buf_desc;
        int rc;

        if (smc_compress_bufsize(bufsize) > SMCD_DMBE_SIZES)
                return ERR_PTR(-EAGAIN);

        /* try to alloc a new DMB */
        buf_desc = kzalloc(sizeof(*buf_desc), GFP_KERNEL);
        if (!buf_desc)
                return ERR_PTR(-ENOMEM);
        if (is_dmb) {
                rc = smc_ism_register_dmb(lgr, bufsize, buf_desc);
                if (rc) {
                        kfree(buf_desc);
                        return ERR_PTR(-EAGAIN);
                }
                buf_desc->pages = virt_to_page(buf_desc->cpu_addr);
                /* CDC header stored in buf. So, pretend it was smaller */
                buf_desc->len = bufsize - sizeof(struct smcd_cdc_msg);
        } else {
                buf_desc->cpu_addr = kzalloc(bufsize, GFP_KERNEL |
                                             __GFP_NOWARN | __GFP_NORETRY |
                                             __GFP_NOMEMALLOC);
                if (!buf_desc->cpu_addr) {
                        kfree(buf_desc);
                        return ERR_PTR(-EAGAIN);
                }
                buf_desc->len = bufsize;
        }
        return buf_desc;
}

static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
{
        struct smc_buf_desc *buf_desc = ERR_PTR(-ENOMEM);
        struct smc_connection *conn = &smc->conn;
        struct smc_link_group *lgr = conn->lgr;
        struct list_head *buf_list;
        int bufsize, bufsize_short;
        struct mutex *lock;     /* lock buffer list */
        int sk_buf_size;

        if (is_rmb)
                /* use socket recv buffer size (w/o overhead) as start value */
                sk_buf_size = smc->sk.sk_rcvbuf / 2;
        else
                /* use socket send buffer size (w/o overhead) as start value */
                sk_buf_size = smc->sk.sk_sndbuf / 2;

        for (bufsize_short = smc_compress_bufsize(sk_buf_size);
             bufsize_short >= 0; bufsize_short--) {

                if (is_rmb) {
                        lock = &lgr->rmbs_lock;
                        buf_list = &lgr->rmbs[bufsize_short];
                } else {
                        lock = &lgr->sndbufs_lock;
                        buf_list = &lgr->sndbufs[bufsize_short];
                }
                bufsize = smc_uncompress_bufsize(bufsize_short);
                if ((1 << get_order(bufsize)) > SG_MAX_SINGLE_ALLOC)
                        continue;

                /* check for reusable slot in the link group */
                buf_desc = smc_buf_get_slot(bufsize_short, lock, buf_list);
                if (buf_desc) {
                        memset(buf_desc->cpu_addr, 0, bufsize);
                        break; /* found reusable slot */
                }

                if (is_smcd)
                        buf_desc = smcd_new_buf_create(lgr, is_rmb, bufsize);
                else
                        buf_desc = smcr_new_buf_create(lgr, is_rmb, bufsize);

                if (PTR_ERR(buf_desc) == -ENOMEM)
                        break;
                if (IS_ERR(buf_desc))
                        continue;

                buf_desc->used = 1;
                mutex_lock(lock);
                list_add(&buf_desc->list, buf_list);
                mutex_unlock(lock);
                break; /* found */
        }

        if (IS_ERR(buf_desc))
                return -ENOMEM;

        if (!is_smcd) {
                if (smcr_buf_map_usable_links(lgr, buf_desc, is_rmb)) {
                        smcr_buf_unuse(buf_desc, lgr);
                        return -ENOMEM;
                }
        }

        if (is_rmb) {
                conn->rmb_desc = buf_desc;
                conn->rmbe_size_short = bufsize_short;
                smc->sk.sk_rcvbuf = bufsize * 2;
                atomic_set(&conn->bytes_to_rcv, 0);
                conn->rmbe_update_limit =
                        smc_rmb_wnd_update_limit(buf_desc->len);
                if (is_smcd)
                        smc_ism_set_conn(conn); /* map RMB/smcd_dev to conn */
        } else {
                conn->sndbuf_desc = buf_desc;
                smc->sk.sk_sndbuf = bufsize * 2;
                atomic_set(&conn->sndbuf_space, bufsize);
        }
        return 0;
}

void smc_sndbuf_sync_sg_for_cpu(struct smc_connection *conn)
{
        if (!conn->lgr || conn->lgr->is_smcd || !smc_link_usable(conn->lnk))
                return;
        smc_ib_sync_sg_for_cpu(conn->lnk, conn->sndbuf_desc, DMA_TO_DEVICE);
}

void smc_sndbuf_sync_sg_for_device(struct smc_connection *conn)
{
        if (!conn->lgr || conn->lgr->is_smcd || !smc_link_usable(conn->lnk))
                return;
        smc_ib_sync_sg_for_device(conn->lnk, conn->sndbuf_desc, DMA_TO_DEVICE);
}

void smc_rmb_sync_sg_for_cpu(struct smc_connection *conn)
{
        int i;

        if (!conn->lgr || conn->lgr->is_smcd)
                return;
        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                if (!smc_link_usable(&conn->lgr->lnk[i]))
                        continue;
                smc_ib_sync_sg_for_cpu(&conn->lgr->lnk[i], conn->rmb_desc,
                                       DMA_FROM_DEVICE);
        }
}

void smc_rmb_sync_sg_for_device(struct smc_connection *conn)
{
        int i;

        if (!conn->lgr || conn->lgr->is_smcd)
                return;
        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                if (!smc_link_usable(&conn->lgr->lnk[i]))
                        continue;
                smc_ib_sync_sg_for_device(&conn->lgr->lnk[i], conn->rmb_desc,
                                          DMA_FROM_DEVICE);
        }
}

/* create the send and receive buffer for an SMC socket;
 * receive buffers are called RMBs;
 * (even though the SMC protocol allows more than one RMB-element per RMB,
 * the Linux implementation uses just one RMB-element per RMB, i.e. uses an
 * extra RMB for every connection in a link group
 */
int smc_buf_create(struct smc_sock *smc, bool is_smcd)
{
        int rc;

        /* create send buffer */
        rc = __smc_buf_create(smc, is_smcd, false);
        if (rc)
                return rc;
        /* create rmb */
        rc = __smc_buf_create(smc, is_smcd, true);
        if (rc)
                smc_buf_free(smc->conn.lgr, false, smc->conn.sndbuf_desc);
        return rc;
}

static inline int smc_rmb_reserve_rtoken_idx(struct smc_link_group *lgr)
{
        int i;

        for_each_clear_bit(i, lgr->rtokens_used_mask, SMC_RMBS_PER_LGR_MAX) {
                if (!test_and_set_bit(i, lgr->rtokens_used_mask))
                        return i;
        }
        return -ENOSPC;
}

static int smc_rtoken_find_by_link(struct smc_link_group *lgr, int lnk_idx,
                                   u32 rkey)
{
        int i;

        for (i = 0; i < SMC_RMBS_PER_LGR_MAX; i++) {
                if (test_bit(i, lgr->rtokens_used_mask) &&
                    lgr->rtokens[i][lnk_idx].rkey == rkey)
                        return i;
        }
        return -ENOENT;
}

/* set rtoken for a new link to an existing rmb */
void smc_rtoken_set(struct smc_link_group *lgr, int link_idx, int link_idx_new,
                    __be32 nw_rkey_known, __be64 nw_vaddr, __be32 nw_rkey)
{
        int rtok_idx;

        rtok_idx = smc_rtoken_find_by_link(lgr, link_idx, ntohl(nw_rkey_known));
        if (rtok_idx == -ENOENT)
                return;
        lgr->rtokens[rtok_idx][link_idx_new].rkey = ntohl(nw_rkey);
        lgr->rtokens[rtok_idx][link_idx_new].dma_addr = be64_to_cpu(nw_vaddr);
}

/* set rtoken for a new link whose link_id is given */
void smc_rtoken_set2(struct smc_link_group *lgr, int rtok_idx, int link_id,
                     __be64 nw_vaddr, __be32 nw_rkey)
{
        u64 dma_addr = be64_to_cpu(nw_vaddr);
        u32 rkey = ntohl(nw_rkey);
        bool found = false;
        int link_idx;

        for (link_idx = 0; link_idx < SMC_LINKS_PER_LGR_MAX; link_idx++) {
                if (lgr->lnk[link_idx].link_id == link_id) {
                        found = true;
                        break;
                }
        }
        if (!found)
                return;
        lgr->rtokens[rtok_idx][link_idx].rkey = rkey;
        lgr->rtokens[rtok_idx][link_idx].dma_addr = dma_addr;
}

/* add a new rtoken from peer */
int smc_rtoken_add(struct smc_link *lnk, __be64 nw_vaddr, __be32 nw_rkey)
{
        struct smc_link_group *lgr = smc_get_lgr(lnk);
        u64 dma_addr = be64_to_cpu(nw_vaddr);
        u32 rkey = ntohl(nw_rkey);
        int i;

        for (i = 0; i < SMC_RMBS_PER_LGR_MAX; i++) {
                if (lgr->rtokens[i][lnk->link_idx].rkey == rkey &&
                    lgr->rtokens[i][lnk->link_idx].dma_addr == dma_addr &&
                    test_bit(i, lgr->rtokens_used_mask)) {
                        /* already in list */
                        return i;
                }
        }
        i = smc_rmb_reserve_rtoken_idx(lgr);
        if (i < 0)
                return i;
        lgr->rtokens[i][lnk->link_idx].rkey = rkey;
        lgr->rtokens[i][lnk->link_idx].dma_addr = dma_addr;
        return i;
}

/* delete an rtoken from all links */
int smc_rtoken_delete(struct smc_link *lnk, __be32 nw_rkey)
{
        struct smc_link_group *lgr = smc_get_lgr(lnk);
        u32 rkey = ntohl(nw_rkey);
        int i, j;

        for (i = 0; i < SMC_RMBS_PER_LGR_MAX; i++) {
                if (lgr->rtokens[i][lnk->link_idx].rkey == rkey &&
                    test_bit(i, lgr->rtokens_used_mask)) {
                        for (j = 0; j < SMC_LINKS_PER_LGR_MAX; j++) {
                                lgr->rtokens[i][j].rkey = 0;
                                lgr->rtokens[i][j].dma_addr = 0;
                        }
                        clear_bit(i, lgr->rtokens_used_mask);
                        return 0;
                }
        }
        return -ENOENT;
}

/* save rkey and dma_addr received from peer during clc handshake */
int smc_rmb_rtoken_handling(struct smc_connection *conn,
                            struct smc_link *lnk,
                            struct smc_clc_msg_accept_confirm *clc)
{
        conn->rtoken_idx = smc_rtoken_add(lnk, clc->rmb_dma_addr,
                                          clc->rmb_rkey);
        if (conn->rtoken_idx < 0)
                return conn->rtoken_idx;
        return 0;
}

static void smc_core_going_away(void)
{
        struct smc_ib_device *smcibdev;
        struct smcd_dev *smcd;

        spin_lock(&smc_ib_devices.lock);
        list_for_each_entry(smcibdev, &smc_ib_devices.list, list) {
                int i;

                for (i = 0; i < SMC_MAX_PORTS; i++)
                        set_bit(i, smcibdev->ports_going_away);
        }
        spin_unlock(&smc_ib_devices.lock);

        spin_lock(&smcd_dev_list.lock);
        list_for_each_entry(smcd, &smcd_dev_list.list, list) {
                smcd->going_away = 1;
        }
        spin_unlock(&smcd_dev_list.lock);
}

/* Clean up all SMC link groups */
static void smc_lgrs_shutdown(void)
{
        struct smcd_dev *smcd;

        smc_core_going_away();

        smc_smcr_terminate_all(NULL);

        spin_lock(&smcd_dev_list.lock);
        list_for_each_entry(smcd, &smcd_dev_list.list, list)
                smc_smcd_terminate_all(smcd);
        spin_unlock(&smcd_dev_list.lock);
}

static int smc_core_reboot_event(struct notifier_block *this,
                                 unsigned long event, void *ptr)
{
        smc_lgrs_shutdown();
        smc_ib_unregister_client();
        return 0;
}

static struct notifier_block smc_reboot_notifier = {
        .notifier_call = smc_core_reboot_event,
};

int __init smc_core_init(void)
{
        return register_reboot_notifier(&smc_reboot_notifier);
}

/* Called (from smc_exit) when module is removed */
void smc_core_exit(void)
{
        unregister_reboot_notifier(&smc_reboot_notifier);
        smc_lgrs_shutdown();
}