// 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 <linux/mutex.h>
#include <linux/list.h>
#include <linux/smc.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"
#include "smc_netlink.h"
#include "smc_stats.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)

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);

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_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_ibdev_cnt_inc(struct smc_link *lnk)
{
        atomic_inc(&lnk->smcibdev->lnk_cnt_by_port[lnk->ibport - 1]);
}

static void smc_ibdev_cnt_dec(struct smc_link *lnk)
{
        atomic_dec(&lnk->smcibdev->lnk_cnt_by_port[lnk->ibport - 1]);
}

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) {
                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);
        }
}

/* 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);
}

/* assign an SMC-R link to the connection */
static int smcr_lgr_conn_assign_link(struct smc_connection *conn, bool first)
{
        enum smc_link_state expected = first ? SMC_LNK_ACTIVATING :
                                       SMC_LNK_ACTIVE;
        int i, j;

        /* do link balancing */
        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                struct smc_link *lnk = &conn->lgr->lnk[i];

                if (lnk->state != expected || lnk->link_is_asym)
                        continue;
                if (conn->lgr->role == SMC_CLNT) {
                        conn->lnk = lnk; /* temporary, SMC server assigns link*/
                        break;
                }
                if (conn->lgr->conns_num % 2) {
                        for (j = i + 1; j < SMC_LINKS_PER_LGR_MAX; j++) {
                                struct smc_link *lnk2;

                                lnk2 = &conn->lgr->lnk[j];
                                if (lnk2->state == expected &&
                                    !lnk2->link_is_asym) {
                                        conn->lnk = lnk2;
                                        break;
                                }
                        }
                }
                if (!conn->lnk)
                        conn->lnk = lnk;
                break;
        }
        if (!conn->lnk)
                return SMC_CLC_DECL_NOACTLINK;
        atomic_inc(&conn->lnk->conn_cnt);
        return 0;
}

/* 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, bool first)
{
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
        static atomic_t nexttoken = ATOMIC_INIT(0);
        int rc;

        if (!conn->lgr->is_smcd) {
                rc = smcr_lgr_conn_assign_link(conn, first);
                if (rc)
                        return rc;
        }
        /* 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);
        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);
        if (conn->lnk)
                atomic_dec(&conn->lnk->conn_cnt);
        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;
}

int smc_nl_get_sys_info(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
        char hostname[SMC_MAX_HOSTNAME_LEN + 1];
        char smc_seid[SMC_MAX_EID_LEN + 1];
        struct smcd_dev *smcd_dev;
        struct nlattr *attrs;
        u8 *seid = NULL;
        u8 *host = NULL;
        void *nlh;

        nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                          &smc_gen_nl_family, NLM_F_MULTI,
                          SMC_NETLINK_GET_SYS_INFO);
        if (!nlh)
                goto errmsg;
        if (cb_ctx->pos[0])
                goto errout;
        attrs = nla_nest_start(skb, SMC_GEN_SYS_INFO);
        if (!attrs)
                goto errout;
        if (nla_put_u8(skb, SMC_NLA_SYS_VER, SMC_V2))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_SYS_REL, SMC_RELEASE))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_SYS_IS_ISM_V2, smc_ism_is_v2_capable()))
                goto errattr;
        smc_clc_get_hostname(&host);
        if (host) {
                memcpy(hostname, host, SMC_MAX_HOSTNAME_LEN);
                hostname[SMC_MAX_HOSTNAME_LEN] = 0;
                if (nla_put_string(skb, SMC_NLA_SYS_LOCAL_HOST, hostname))
                        goto errattr;
        }
        mutex_lock(&smcd_dev_list.mutex);
        smcd_dev = list_first_entry_or_null(&smcd_dev_list.list,
                                            struct smcd_dev, list);
        if (smcd_dev)
                smc_ism_get_system_eid(smcd_dev, &seid);
        mutex_unlock(&smcd_dev_list.mutex);
        if (seid && smc_ism_is_v2_capable()) {
                memcpy(smc_seid, seid, SMC_MAX_EID_LEN);
                smc_seid[SMC_MAX_EID_LEN] = 0;
                if (nla_put_string(skb, SMC_NLA_SYS_SEID, smc_seid))
                        goto errattr;
        }
        nla_nest_end(skb, attrs);
        genlmsg_end(skb, nlh);
        cb_ctx->pos[0] = 1;
        return skb->len;

errattr:
        nla_nest_cancel(skb, attrs);
errout:
        genlmsg_cancel(skb, nlh);
errmsg:
        return skb->len;
}

static int smc_nl_fill_lgr(struct smc_link_group *lgr,
                           struct sk_buff *skb,
                           struct netlink_callback *cb)
{
        char smc_target[SMC_MAX_PNETID_LEN + 1];
        struct nlattr *attrs;

        attrs = nla_nest_start(skb, SMC_GEN_LGR_SMCR);
        if (!attrs)
                goto errout;

        if (nla_put_u32(skb, SMC_NLA_LGR_R_ID, *((u32 *)&lgr->id)))
                goto errattr;
        if (nla_put_u32(skb, SMC_NLA_LGR_R_CONNS_NUM, lgr->conns_num))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_LGR_R_ROLE, lgr->role))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_LGR_R_TYPE, lgr->type))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_LGR_R_VLAN_ID, lgr->vlan_id))
                goto errattr;
        memcpy(smc_target, lgr->pnet_id, SMC_MAX_PNETID_LEN);
        smc_target[SMC_MAX_PNETID_LEN] = 0;
        if (nla_put_string(skb, SMC_NLA_LGR_R_PNETID, smc_target))
                goto errattr;

        nla_nest_end(skb, attrs);
        return 0;
errattr:
        nla_nest_cancel(skb, attrs);
errout:
        return -EMSGSIZE;
}

static int smc_nl_fill_lgr_link(struct smc_link_group *lgr,
                                struct smc_link *link,
                                struct sk_buff *skb,
                                struct netlink_callback *cb)
{
        char smc_ibname[IB_DEVICE_NAME_MAX];
        u8 smc_gid_target[41];
        struct nlattr *attrs;
        u32 link_uid = 0;
        void *nlh;

        nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                          &smc_gen_nl_family, NLM_F_MULTI,
                          SMC_NETLINK_GET_LINK_SMCR);
        if (!nlh)
                goto errmsg;

        attrs = nla_nest_start(skb, SMC_GEN_LINK_SMCR);
        if (!attrs)
                goto errout;

        if (nla_put_u8(skb, SMC_NLA_LINK_ID, link->link_id))
                goto errattr;
        if (nla_put_u32(skb, SMC_NLA_LINK_STATE, link->state))
                goto errattr;
        if (nla_put_u32(skb, SMC_NLA_LINK_CONN_CNT,
                        atomic_read(&link->conn_cnt)))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_LINK_IB_PORT, link->ibport))
                goto errattr;
        if (nla_put_u32(skb, SMC_NLA_LINK_NET_DEV, link->ndev_ifidx))
                goto errattr;
        snprintf(smc_ibname, sizeof(smc_ibname), "%s", link->ibname);
        if (nla_put_string(skb, SMC_NLA_LINK_IB_DEV, smc_ibname))
                goto errattr;
        memcpy(&link_uid, link->link_uid, sizeof(link_uid));
        if (nla_put_u32(skb, SMC_NLA_LINK_UID, link_uid))
                goto errattr;
        memcpy(&link_uid, link->peer_link_uid, sizeof(link_uid));
        if (nla_put_u32(skb, SMC_NLA_LINK_PEER_UID, link_uid))
                goto errattr;
        memset(smc_gid_target, 0, sizeof(smc_gid_target));
        smc_gid_be16_convert(smc_gid_target, link->gid);
        if (nla_put_string(skb, SMC_NLA_LINK_GID, smc_gid_target))
                goto errattr;
        memset(smc_gid_target, 0, sizeof(smc_gid_target));
        smc_gid_be16_convert(smc_gid_target, link->peer_gid);
        if (nla_put_string(skb, SMC_NLA_LINK_PEER_GID, smc_gid_target))
                goto errattr;

        nla_nest_end(skb, attrs);
        genlmsg_end(skb, nlh);
        return 0;
errattr:
        nla_nest_cancel(skb, attrs);
errout:
        genlmsg_cancel(skb, nlh);
errmsg:
        return -EMSGSIZE;
}

static int smc_nl_handle_lgr(struct smc_link_group *lgr,
                             struct sk_buff *skb,
                             struct netlink_callback *cb,
                             bool list_links)
{
        void *nlh;
        int i;

        nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                          &smc_gen_nl_family, NLM_F_MULTI,
                          SMC_NETLINK_GET_LGR_SMCR);
        if (!nlh)
                goto errmsg;
        if (smc_nl_fill_lgr(lgr, skb, cb))
                goto errout;

        genlmsg_end(skb, nlh);
        if (!list_links)
                goto out;
        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                if (!smc_link_usable(&lgr->lnk[i]))
                        continue;
                if (smc_nl_fill_lgr_link(lgr, &lgr->lnk[i], skb, cb))
                        goto errout;
        }
out:
        return 0;

errout:
        genlmsg_cancel(skb, nlh);
errmsg:
        return -EMSGSIZE;
}

static void smc_nl_fill_lgr_list(struct smc_lgr_list *smc_lgr,
                                 struct sk_buff *skb,
                                 struct netlink_callback *cb,
                                 bool list_links)
{
        struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
        struct smc_link_group *lgr;
        int snum = cb_ctx->pos[0];
        int num = 0;

        spin_lock_bh(&smc_lgr->lock);
        list_for_each_entry(lgr, &smc_lgr->list, list) {
                if (num < snum)
                        goto next;
                if (smc_nl_handle_lgr(lgr, skb, cb, list_links))
                        goto errout;
next:
                num++;
        }
errout:
        spin_unlock_bh(&smc_lgr->lock);
        cb_ctx->pos[0] = num;
}

static int smc_nl_fill_smcd_lgr(struct smc_link_group *lgr,
                                struct sk_buff *skb,
                                struct netlink_callback *cb)
{
        char smc_host[SMC_MAX_HOSTNAME_LEN + 1];
        char smc_pnet[SMC_MAX_PNETID_LEN + 1];
        char smc_eid[SMC_MAX_EID_LEN + 1];
        struct nlattr *v2_attrs;
        struct nlattr *attrs;
        void *nlh;

        nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                          &smc_gen_nl_family, NLM_F_MULTI,
                          SMC_NETLINK_GET_LGR_SMCD);
        if (!nlh)
                goto errmsg;

        attrs = nla_nest_start(skb, SMC_GEN_LGR_SMCD);
        if (!attrs)
                goto errout;

        if (nla_put_u32(skb, SMC_NLA_LGR_D_ID, *((u32 *)&lgr->id)))
                goto errattr;
        if (nla_put_u64_64bit(skb, SMC_NLA_LGR_D_GID, lgr->smcd->local_gid,
                              SMC_NLA_LGR_D_PAD))
                goto errattr;
        if (nla_put_u64_64bit(skb, SMC_NLA_LGR_D_PEER_GID, lgr->peer_gid,
                              SMC_NLA_LGR_D_PAD))
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_LGR_D_VLAN_ID, lgr->vlan_id))
                goto errattr;
        if (nla_put_u32(skb, SMC_NLA_LGR_D_CONNS_NUM, lgr->conns_num))
                goto errattr;
        if (nla_put_u32(skb, SMC_NLA_LGR_D_CHID, smc_ism_get_chid(lgr->smcd)))
                goto errattr;
        memcpy(smc_pnet, lgr->smcd->pnetid, SMC_MAX_PNETID_LEN);
        smc_pnet[SMC_MAX_PNETID_LEN] = 0;
        if (nla_put_string(skb, SMC_NLA_LGR_D_PNETID, smc_pnet))
                goto errattr;

        v2_attrs = nla_nest_start(skb, SMC_NLA_LGR_V2);
        if (!v2_attrs)
                goto errattr;
        if (nla_put_u8(skb, SMC_NLA_LGR_V2_VER, lgr->smc_version))
                goto errv2attr;
        if (nla_put_u8(skb, SMC_NLA_LGR_V2_REL, lgr->peer_smc_release))
                goto errv2attr;
        if (nla_put_u8(skb, SMC_NLA_LGR_V2_OS, lgr->peer_os))
                goto errv2attr;
        memcpy(smc_host, lgr->peer_hostname, SMC_MAX_HOSTNAME_LEN);
        smc_host[SMC_MAX_HOSTNAME_LEN] = 0;
        if (nla_put_string(skb, SMC_NLA_LGR_V2_PEER_HOST, smc_host))
                goto errv2attr;
        memcpy(smc_eid, lgr->negotiated_eid, SMC_MAX_EID_LEN);
        smc_eid[SMC_MAX_EID_LEN] = 0;
        if (nla_put_string(skb, SMC_NLA_LGR_V2_NEG_EID, smc_eid))
                goto errv2attr;

        nla_nest_end(skb, v2_attrs);
        nla_nest_end(skb, attrs);
        genlmsg_end(skb, nlh);
        return 0;

errv2attr:
        nla_nest_cancel(skb, v2_attrs);
errattr:
        nla_nest_cancel(skb, attrs);
errout:
        genlmsg_cancel(skb, nlh);
errmsg:
        return -EMSGSIZE;
}

static int smc_nl_handle_smcd_lgr(struct smcd_dev *dev,
                                  struct sk_buff *skb,
                                  struct netlink_callback *cb)
{
        struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
        struct smc_link_group *lgr;
        int snum = cb_ctx->pos[1];
        int rc = 0, num = 0;

        spin_lock_bh(&dev->lgr_lock);
        list_for_each_entry(lgr, &dev->lgr_list, list) {
                if (!lgr->is_smcd)
                        continue;
                if (num < snum)
                        goto next;
                rc = smc_nl_fill_smcd_lgr(lgr, skb, cb);
                if (rc)
                        goto errout;
next:
                num++;
        }
errout:
        spin_unlock_bh(&dev->lgr_lock);
        cb_ctx->pos[1] = num;
        return rc;
}

static int smc_nl_fill_smcd_dev(struct smcd_dev_list *dev_list,
                                struct sk_buff *skb,
                                struct netlink_callback *cb)
{
        struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
        struct smcd_dev *smcd_dev;
        int snum = cb_ctx->pos[0];
        int rc = 0, num = 0;

        mutex_lock(&dev_list->mutex);
        list_for_each_entry(smcd_dev, &dev_list->list, list) {
                if (list_empty(&smcd_dev->lgr_list))
                        continue;
                if (num < snum)
                        goto next;
                rc = smc_nl_handle_smcd_lgr(smcd_dev, skb, cb);
                if (rc)
                        goto errout;
next:
                num++;
        }
errout:
        mutex_unlock(&dev_list->mutex);
        cb_ctx->pos[0] = num;
        return rc;
}

int smcr_nl_get_lgr(struct sk_buff *skb, struct netlink_callback *cb)
{
        bool list_links = false;

        smc_nl_fill_lgr_list(&smc_lgr_list, skb, cb, list_links);
        return skb->len;
}

int smcr_nl_get_link(struct sk_buff *skb, struct netlink_callback *cb)
{
        bool list_links = true;

        smc_nl_fill_lgr_list(&smc_lgr_list, skb, cb, list_links);
        return skb->len;
}

int smcd_nl_get_lgr(struct sk_buff *skb, struct netlink_callback *cb)
{
        smc_nl_fill_smcd_dev(&smcd_dev_list, skb, cb);
        return skb->len;
}

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_terminate(lgr, true);
}

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

        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_all(&lgr->llc_msg_waiter);
        wake_up_all(&lgr->llc_flow_waiter);
}

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;

        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_llc_send_link_delete_all(lgr, true,
                                             SMC_LLC_DEL_PROG_INIT_TERM);
        if (lgr->is_smcd && !lgr->terminating)
                smc_ism_signal_shutdown(lgr);
        if (!lgr->is_smcd)
                smcr_lgr_link_deactivate_all(lgr);
        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;
}

static void smcr_copy_dev_info_to_link(struct smc_link *link)
{
        struct smc_ib_device *smcibdev = link->smcibdev;

        snprintf(link->ibname, sizeof(link->ibname), "%s",
                 smcibdev->ibdev->name);
        link->ndev_ifidx = smcibdev->ndev_ifidx[link->ibport - 1];
}

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->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;
        smc_ibdev_cnt_inc(lnk);
        smcr_copy_dev_info_to_link(lnk);
        lnk->path_mtu = ini->ib_dev->pattr[ini->ib_port - 1].active_mtu;
        atomic_set(&lnk->conn_cnt, 0);
        smc_llc_link_set_uid(lnk);
        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;
        lnk->state = SMC_LNK_ACTIVATING;
        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, false);
out:
        smc_ibdev_cnt_dec(lnk);
        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->ism_selected],
                                     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->tx_wq = alloc_workqueue("smc_tx_wq-%*phN", 0, 0,
                                     SMC_LGR_ID_SIZE, &lgr->id);
        if (!lgr->tx_wq) {
                rc = -ENOMEM;
                goto free_lgr;
        }
        lgr->is_smcd = ini->is_smcd;
        lgr->sync_err = 0;
        lgr->terminating = 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[ini->ism_selected]->dev);
                lgr->peer_gid = ini->ism_peer_gid[ini->ism_selected];
                lgr->smcd = ini->ism_dev[ini->ism_selected];
                lgr_list = &ini->ism_dev[ini->ism_selected]->lgr_list;
                lgr_lock = &lgr->smcd->lgr_lock;
                lgr->smc_version = ini->smcd_version;
                lgr->peer_shutdown = 0;
                atomic_inc(&ini->ism_dev[ini->ism_selected]->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_wq;
                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_tail(&lgr->list, lgr_list);
        spin_unlock_bh(lgr_lock);
        return 0;

free_wq:
        destroy_workqueue(lgr->tx_wq);
free_lgr:
        kfree(lgr);
ism_put_vlan:
        if (ini->is_smcd && ini->vlan_id)
                smc_ism_put_vlan(ini->ism_dev[ini->ism_selected], 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_cdc_tx_pend *pend,
                             struct smc_wr_buf *wr_buf)
{
        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, pend, wr_buf);
                if (!rc) {
                        queue_delayed_work(conn->lgr->tx_wq, &conn->tx_work, 0);
                        smc->sk.sk_data_ready(&smc->sk);
                }
        } else {
                smc_wr_tx_put_slot(conn->lnk,
                                   (struct smc_wr_tx_pend_priv *)pend);
        }
        return rc;
}

void smc_switch_link_and_count(struct smc_connection *conn,
                               struct smc_link *to_lnk)
{
        atomic_dec(&conn->lnk->conn_cnt);
        conn->lnk = to_lnk;
        atomic_inc(&conn->lnk->conn_cnt);
}

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_cdc_tx_pend *pend;
        struct smc_connection *conn;
        struct smc_wr_buf *wr_buf;
        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 (!smc_link_active(&lgr->lnk[i]) || 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);
                        smc_switch_link_and_count(conn, to_lnk);
                        spin_unlock_bh(&conn->send_lock);
                        continue;
                }
                sock_hold(&smc->sk);
                read_unlock_bh(&lgr->conns_lock);
                /* pre-fetch buffer outside of send_lock, might sleep */
                rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend);
                if (rc) {
                        smcr_link_down_cond_sched(to_lnk);
                        return NULL;
                }
                /* avoid race with smcr_tx_sndbuf_nonempty() */
                spin_lock_bh(&conn->send_lock);
                smc_switch_link_and_count(conn, to_lnk);
                rc = smc_switch_cursor(smc, pend, wr_buf);
                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 (current_work() != &conn->abort_work)
                        cancel_work_sync(&conn->abort_work);
        }
        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, bool log)
{
        struct smc_ib_device *smcibdev;

        if (!lnk->lgr || lnk->state == SMC_LNK_UNUSED)
                return;
        lnk->peer_qpn = 0;
        smc_llc_link_clear(lnk, log);
        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);
        smc_ibdev_cnt_dec(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;

        if (!lgr->is_smcd) {
                mutex_lock(&lgr->llc_conf_mutex);
                for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
                        if (lgr->lnk[i].state != SMC_LNK_UNUSED)
                                smcr_link_clear(&lgr->lnk[i], false);
                }
                mutex_unlock(&lgr->llc_conf_mutex);
                smc_llc_lgr_clear(lgr);
        }

        smc_lgr_free_bufs(lgr);
        destroy_workqueue(lgr->tx_wq);
        if (lgr->is_smcd) {
                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 {
                if (!atomic_dec_return(&lgr_cnt))
                        wake_up(&lgrs_deleted);
        }
        kfree(lgr);
}

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)
{
        if (lgr->is_smcd) {
                smc_ism_signal_shutdown(lgr);
        } else {
                u32 rsn = lgr->llc_termination_rsn;

                if (!rsn)
                        rsn = SMC_LLC_DEL_PROG_INIT_TERM;
                smc_llc_send_link_delete_all(lgr, false, rsn);
                smcr_lgr_link_deactivate_all(lgr);
        }
}

/* 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 */
        /* cancel free_work sync, will terminate when lgr->freeing is set */
        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);
        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);
        lgr->freeing = 1;
        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);
                        lgr->freeing = 1;
                }
        }
        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_llc_set_termination_rsn(lgr, SMC_LLC_DEL_OP_INIT_TERM);
                __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));
        }
}

/* set new lgr type and clear all asymmetric link tagging */
void smcr_lgr_set_type(struct smc_link_group *lgr, enum smc_lgr_type new_type)
{
        char *lgr_type = "";
        int i;

        for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++)
                if (smc_link_usable(&lgr->lnk[i]))
                        lgr->lnk[i].link_is_asym = false;
        if (lgr->type == new_type)
                return;
        lgr->type = new_type;

        switch (lgr->type) {
        case SMC_LGR_NONE:
                lgr_type = "NONE";
                break;
        case SMC_LGR_SINGLE:
                lgr_type = "SINGLE";
                break;
        case SMC_LGR_SYMMETRIC:
                lgr_type = "SYMMETRIC";
                break;
        case SMC_LGR_ASYMMETRIC_PEER:
                lgr_type = "ASYMMETRIC_PEER";
                break;
        case SMC_LGR_ASYMMETRIC_LOCAL:
                lgr_type = "ASYMMETRIC_LOCAL";
                break;
        }
        pr_warn_ratelimited("smc: SMC-R lg %*phN state changed: "
                            "%s, pnetid %.16s\n", SMC_LGR_ID_SIZE, &lgr->id,
                            lgr_type, lgr->pnet_id);
}

/* set new lgr type and tag a link as asymmetric */
void smcr_lgr_set_type_asym(struct smc_link_group *lgr,
                            enum smc_lgr_type new_type, int asym_lnk_idx)
{
        smcr_lgr_set_type(lgr, new_type);
        lgr->lnk[asym_lnk_idx].link_is_asym = true;
}

/* abort connection, abort_work scheduled from tasklet context */
static void smc_conn_abort_work(struct work_struct *work)
{
        struct smc_connection *conn = container_of(work,
                                                   struct smc_connection,
                                                   abort_work);
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);

        smc_conn_kill(conn, true);
        sock_put(&smc->sk); /* sock_hold done by schedulers of abort_work */
}

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

        list_for_each_entry_safe(lgr, n, &smc_lgr_list.list, list) {
                struct smc_link *link;

                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;

                /* trigger local add link processing */
                link = smc_llc_usable_link(lgr);
                if (link)
                        smc_llc_add_link_local(link);
        }
}

/* 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, true);
                return;
        }
        smcr_lgr_set_type(lgr, 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_timeout(lgr->llc_flow_waiter,
                                (list_empty(&lgr->list) ||
                                 lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
                                SMC_LLC_WAIT_TIME);
                        mutex_lock(&lgr->llc_conf_mutex);
                }
                if (!list_empty(&lgr->list)) {
                        smc_llc_send_delete_link(to_lnk, del_link_id,
                                                 SMC_LLC_REQ, true,
                                                 SMC_LLC_DEL_LOST_PATH);
                        smcr_link_clear(lnk, true);
                }
                wake_up(&lgr->llc_flow_waiter); /* wake up next waiter */
        }
}

/* 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_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_all(&lgr->llc_msg_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 (!smc_link_active(&lgr->lnk[i]))
                        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[ini->ism_selected]->lgr_list :
                                  &smc_lgr_list.list;
        lgr_lock = ini->is_smcd ? &ini->ism_dev[ini->ism_selected]->lgr_lock :
                                  &smc_lgr_list.lock;
        ini->first_contact_local = 1;
        role = smc->listen_smc ? SMC_SERV : SMC_CLNT;
        if (role == SMC_CLNT && ini->first_contact_peer)
                /* 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_selected],
                                    ini->ism_peer_gid[ini->ism_selected]) :
                     smcr_lgr_match(lgr, ini->ib_lcl, role, ini->ib_clcqpn)) &&
                    !lgr->sync_err &&
                    (ini->smcd_version == SMC_V2 ||
                     lgr->vlan_id == ini->vlan_id) &&
                    (role == SMC_CLNT || ini->is_smcd ||
                     lgr->conns_num < SMC_RMBS_PER_LGR_MAX)) {
                        /* link group found */
                        ini->first_contact_local = 0;
                        conn->lgr = lgr;
                        rc = smc_lgr_register_conn(conn, false);
                        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->first_contact_peer &&
            ini->first_contact_local) {
                /* 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->first_contact_local) {
                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, true);
                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;
        INIT_WORK(&smc->conn.abort_work, smc_conn_abort_work);
        if (ini->is_smcd) {
                conn->rx_off = sizeof(struct smcd_cdc_msg);
                smcd_cdc_rx_init(conn); /* init tasklet for this conn */
        } else {
                conn->rx_off = 0;
        }
#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         6 /* 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) {