// 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 <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 void smc_buf_free(struct smc_link_group *lgr, bool is_rmb,
                         struct smc_buf_desc *buf_desc);

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.
         */
        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)
{
        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 void 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);
        conn->lgr->conns_num++;
}

/* 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);
}

/* Send delete link, either as client to request the initiation
 * of the DELETE LINK sequence from server; or as server to
 * initiate the delete processing. See smc_llc_rx_delete_link().
 */
static int smc_link_send_delete(struct smc_link *lnk)
{
        if (lnk->state == SMC_LNK_ACTIVE &&
            !smc_llc_send_delete_link(lnk, SMC_LLC_REQ, true)) {
                smc_llc_link_deleting(lnk);
                return 0;
        }
        return -ENOTCONN;
}

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);
        bool conns;

        spin_lock_bh(&smc_lgr_list.lock);
        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(&smc_lgr_list.lock);
                return;
        }
        if (!list_empty(&lgr->list))
                list_del_init(&lgr->list); /* remove from smc_lgr_list */
        spin_unlock_bh(&smc_lgr_list.lock);

        if (!lgr->is_smcd && !lgr->terminating) {
                struct smc_link *lnk = &lgr->lnk[SMC_SINGLE_LINK];

                /* try to send del link msg, on error free lgr immediately */
                if (lnk->state == SMC_LNK_ACTIVE &&
                    !smc_link_send_delete(lnk)) {
                        /* reschedule in case we never receive a response */
                        smc_lgr_schedule_free_work(lgr);
                        return;
                }
        }

        if (!delayed_work_pending(&lgr->free_work)) {
                struct smc_link *lnk = &lgr->lnk[SMC_SINGLE_LINK];

                if (!lgr->is_smcd && lnk->state != SMC_LNK_INACTIVE)
                        smc_llc_link_inactive(lnk);
                if (lgr->is_smcd)
                        smc_ism_signal_shutdown(lgr);
                smc_lgr_free(lgr);
        }
}

/* create a new SMC link group */
static int smc_lgr_create(struct smc_sock *smc, bool is_smcd,
                          struct smc_ib_device *smcibdev, u8 ibport,
                          char *peer_systemid, unsigned short vlan_id,
                          struct smcd_dev *smcismdev, u64 peer_gid)
{
        struct smc_link_group *lgr;
        struct smc_link *lnk;
        u8 rndvec[3];
        int rc = 0;
        int i;

        if (is_smcd && vlan_id) {
                rc = smc_ism_get_vlan(smcismdev, vlan_id);
                if (rc)
                        goto out;
        }

        lgr = kzalloc(sizeof(*lgr), GFP_KERNEL);
        if (!lgr) {
                rc = -ENOMEM;
                goto out;
        }
        lgr->is_smcd = is_smcd;
        lgr->sync_err = 0;
        lgr->vlan_id = vlan_id;
        rwlock_init(&lgr->sndbufs_lock);
        rwlock_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]);
        }
        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);
        lgr->conns_all = RB_ROOT;
        if (is_smcd) {
                /* SMC-D specific settings */
                lgr->peer_gid = peer_gid;
                lgr->smcd = smcismdev;
        } else {
                /* SMC-R specific settings */
                lgr->role = smc->listen_smc ? SMC_SERV : SMC_CLNT;
                memcpy(lgr->peer_systemid, peer_systemid, SMC_SYSTEMID_LEN);

                lnk = &lgr->lnk[SMC_SINGLE_LINK];
                /* initialize link */
                lnk->state = SMC_LNK_ACTIVATING;
                lnk->link_id = SMC_SINGLE_LINK;
                lnk->smcibdev = smcibdev;
                lnk->ibport = ibport;
                lnk->path_mtu = smcibdev->pattr[ibport - 1].active_mtu;
                if (!smcibdev->initialized)
                        smc_ib_setup_per_ibdev(smcibdev);
                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,
                                          vlan_id, lnk->gid, &lnk->sgid_index);
                if (rc)
                        goto free_lgr;
                rc = smc_llc_link_init(lnk);
                if (rc)
                        goto free_lgr;
                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;
        }
        smc->conn.lgr = lgr;
        spin_lock_bh(&smc_lgr_list.lock);
        list_add(&lgr->list, &smc_lgr_list.list);
        spin_unlock_bh(&smc_lgr_list.lock);
        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);
free_lgr:
        kfree(lgr);
out:
        return rc;
}

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) {
                if (!conn->rmb_desc->regerr) {
                        if (!lgr->is_smcd) {
                                /* unregister rmb with peer */
                                smc_llc_do_delete_rkey(
                                                &lgr->lnk[SMC_SINGLE_LINK],
                                                conn->rmb_desc);
                        }
                        conn->rmb_desc->used = 0;
                } else {
                        /* buf registration failed, reuse not possible */
                        write_lock_bh(&lgr->rmbs_lock);
                        list_del(&conn->rmb_desc->list);
                        write_unlock_bh(&lgr->rmbs_lock);

                        smc_buf_free(lgr, true, conn->rmb_desc);
                }
        }
}

/* 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) {
                smc_ism_unset_conn(conn);
                tasklet_kill(&conn->rx_tsklet);
        } else {
                smc_cdc_tx_dismiss_slots(conn);
        }
        smc_lgr_unregister_conn(conn);
        smc_buf_unuse(conn, lgr);               /* allow buffer reuse */
        conn->lgr = NULL;

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

static void smc_link_clear(struct smc_link *lnk)
{
        lnk->peer_qpn = 0;
        smc_llc_link_clear(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);
}

static void smcr_buf_free(struct smc_link_group *lgr, bool is_rmb,
                          struct smc_buf_desc *buf_desc)
{
        struct smc_link *lnk = &lgr->lnk[SMC_SINGLE_LINK];

        if (is_rmb) {
                if (buf_desc->mr_rx[SMC_SINGLE_LINK])
                        smc_ib_put_memory_region(
                                        buf_desc->mr_rx[SMC_SINGLE_LINK]);
                smc_ib_buf_unmap_sg(lnk->smcibdev, buf_desc,
                                    DMA_FROM_DEVICE);
        } else {
                smc_ib_buf_unmap_sg(lnk->smcibdev, buf_desc,
                                    DMA_TO_DEVICE);
        }
        sg_free_table(&buf_desc->sgt[SMC_SINGLE_LINK]);
        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)
{
        smc_lgr_free_bufs(lgr);
        if (lgr->is_smcd)
                smc_ism_put_vlan(lgr->smcd, lgr->vlan_id);
        else
                smc_link_clear(&lgr->lnk[SMC_SINGLE_LINK]);
        kfree(lgr);
}

void smc_lgr_forget(struct smc_link_group *lgr)
{
        spin_lock_bh(&smc_lgr_list.lock);
        /* do not use this link group for new connections */
        if (!list_empty(&lgr->list))
                list_del_init(&lgr->list);
        spin_unlock_bh(&smc_lgr_list.lock);
}

/* terminate linkgroup abnormally */
static void __smc_lgr_terminate(struct smc_link_group *lgr)
{
        struct smc_connection *conn;
        struct smc_sock *smc;
        struct rb_node *node;

        if (lgr->terminating)
                return; /* lgr already terminating */
        lgr->terminating = 1;
        if (!list_empty(&lgr->list)) /* forget lgr */
                list_del_init(&lgr->list);
        if (!lgr->is_smcd)
                smc_llc_link_inactive(&lgr->lnk[SMC_SINGLE_LINK]);

        write_lock_bh(&lgr->conns_lock);
        node = rb_first(&lgr->conns_all);
        while (node) {
                conn = rb_entry(node, struct smc_connection, alert_node);
                smc = container_of(conn, struct smc_sock, conn);
                sock_hold(&smc->sk); /* sock_put in close work */
                conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
                __smc_lgr_unregister_conn(conn);
                conn->lgr = NULL;
                write_unlock_bh(&lgr->conns_lock);
                if (!schedule_work(&conn->close_work))
                        sock_put(&smc->sk);
                write_lock_bh(&lgr->conns_lock);
                node = rb_first(&lgr->conns_all);
        }
        write_unlock_bh(&lgr->conns_lock);
        if (!lgr->is_smcd)
                wake_up(&lgr->lnk[SMC_SINGLE_LINK].wr_reg_wait);
        smc_lgr_schedule_free_work(lgr);
}

void smc_lgr_terminate(struct smc_link_group *lgr)
{
        spin_lock_bh(&smc_lgr_list.lock);
        __smc_lgr_terminate(lgr);
        spin_unlock_bh(&smc_lgr_list.lock);
}

/* Called when IB port is terminated */
void smc_port_terminate(struct smc_ib_device *smcibdev, u8 ibport)
{
        struct smc_link_group *lgr, *l;

        spin_lock_bh(&smc_lgr_list.lock);
        list_for_each_entry_safe(lgr, l, &smc_lgr_list.list, list) {
                if (!lgr->is_smcd &&
                    lgr->lnk[SMC_SINGLE_LINK].smcibdev == smcibdev &&
                    lgr->lnk[SMC_SINGLE_LINK].ibport == ibport)
                        __smc_lgr_terminate(lgr);
        }
        spin_unlock_bh(&smc_lgr_list.lock);
}

/* Called when SMC-D device is terminated or peer is lost */
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(&smc_lgr_list.lock);
        list_for_each_entry_safe(lgr, l, &smc_lgr_list.list, list) {
                if (lgr->is_smcd && lgr->smcd == dev &&
                    (!peer_gid || lgr->peer_gid == peer_gid) &&
                    (vlan == VLAN_VID_MASK || lgr->vlan_id == vlan)) {
                        __smc_lgr_terminate(lgr);
                        list_move(&lgr->list, &lgr_free_list);
                }
        }
        spin_unlock_bh(&smc_lgr_list.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);
                cancel_delayed_work_sync(&lgr->free_work);
                if (!peer_gid && vlan == VLAN_VID_MASK) /* dev terminated? */
                        smc_ism_signal_shutdown(lgr);
                smc_lgr_free(lgr);
        }
}

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

        *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)) {
                *vlan_id = vlan_dev_vlan_id(ndev);
                goto out_rel;
        }

        rtnl_lock();
        nest_lvl = dev_get_nest_level(ndev);
        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)) {
                        *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)
{
        return !memcmp(lgr->peer_systemid, lcl->id_for_peer,
                       SMC_SYSTEMID_LEN) &&
                !memcmp(lgr->lnk[SMC_SINGLE_LINK].peer_gid, &lcl->gid,
                        SMC_GID_SIZE) &&
                !memcmp(lgr->lnk[SMC_SINGLE_LINK].peer_mac, lcl->mac,
                        sizeof(lcl->mac)) &&
                lgr->role == role &&
                (lgr->role == SMC_SERV ||
                 lgr->lnk[SMC_SINGLE_LINK].peer_qpn == clcqpn);
}

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, bool is_smcd, int srv_first_contact,
                    struct smc_ib_device *smcibdev, u8 ibport, u32 clcqpn,
                    struct smc_clc_msg_local *lcl, struct smcd_dev *smcd,
                    u64 peer_gid)
{
        struct smc_connection *conn = &smc->conn;
        int local_contact = SMC_FIRST_CONTACT;
        struct smc_link_group *lgr;
        unsigned short vlan_id;
        enum smc_lgr_role role;
        int rc = 0;

        role = smc->listen_smc ? SMC_SERV : SMC_CLNT;
        rc = smc_vlan_by_tcpsk(smc->clcsock, &vlan_id);
        if (rc)
                return rc;

        if ((role == SMC_CLNT) && srv_first_contact)
                /* create new link group as well */
                goto create;

        /* determine if an existing link group can be reused */
        spin_lock_bh(&smc_lgr_list.lock);
        list_for_each_entry(lgr, &smc_lgr_list.list, list) {
                write_lock_bh(&lgr->conns_lock);
                if ((is_smcd ? smcd_lgr_match(lgr, smcd, peer_gid) :
                     smcr_lgr_match(lgr, lcl, role, clcqpn)) &&
                    !lgr->sync_err &&
                    lgr->vlan_id == vlan_id &&
                    (role == SMC_CLNT ||
                     lgr->conns_num < SMC_RMBS_PER_LGR_MAX)) {
                        /* link group found */
                        local_contact = SMC_REUSE_CONTACT;
                        conn->lgr = lgr;
                        smc_lgr_register_conn(conn); /* add smc conn to lgr */
                        if (delayed_work_pending(&lgr->free_work))
                                cancel_delayed_work(&lgr->free_work);
                        write_unlock_bh(&lgr->conns_lock);
                        break;
                }
                write_unlock_bh(&lgr->conns_lock);
        }
        spin_unlock_bh(&smc_lgr_list.lock);

        if (role == SMC_CLNT && !srv_first_contact &&
            (local_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 -ENOLINK;
        }

create:
        if (local_contact == SMC_FIRST_CONTACT) {
                rc = smc_lgr_create(smc, is_smcd, smcibdev, ibport,
                                    lcl->id_for_peer, vlan_id, smcd, peer_gid);
                if (rc)
                        goto out;
                smc_lgr_register_conn(conn); /* add smc conn to lgr */
        }
        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 (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 ? rc : local_contact;
}

/* 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,
                                             rwlock_t *lock,
                                             struct list_head *buf_list)
{
        struct smc_buf_desc *buf_slot;

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

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;
        struct smc_link *lnk;
        int rc;

        /* 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);

        /* build the sg table from the pages */
        lnk = &lgr->lnk[SMC_SINGLE_LINK];
        rc = sg_alloc_table(&buf_desc->sgt[SMC_SINGLE_LINK], 1,
                            GFP_KERNEL);
        if (rc) {
                smc_buf_free(lgr, is_rmb, buf_desc);
                return ERR_PTR(rc);
        }
        sg_set_buf(buf_desc->sgt[SMC_SINGLE_LINK].sgl,
                   buf_desc->cpu_addr, bufsize);

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

        /* 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);
                if (rc) {
                        smc_buf_free(lgr, is_rmb, buf_desc);
                        return ERR_PTR(rc);
                }
        }

        buf_desc->len = bufsize;
        return buf_desc;
}

#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;
        int sk_buf_size;
        rwlock_t *lock;

        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;
                write_lock_bh(lock);
                list_add(&buf_desc->list, buf_list);
                write_unlock_bh(lock);
                break; /* found */
        }

        if (IS_ERR(buf_desc))
                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)
{
        struct smc_link_group *lgr = conn->lgr;

        if (!conn->lgr || conn->lgr->is_smcd)
                return;
        smc_ib_sync_sg_for_cpu(lgr->lnk[SMC_SINGLE_LINK].smcibdev,
                               conn->sndbuf_desc, DMA_TO_DEVICE);
}

void smc_sndbuf_sync_sg_for_device(struct smc_connection *conn)
{
        struct smc_link_group *lgr = conn->lgr;

        if (!conn->lgr || conn->lgr->is_smcd)
                return;
        smc_ib_sync_sg_for_device(lgr->lnk[SMC_SINGLE_LINK].smcibdev,
                                  conn->sndbuf_desc, DMA_TO_DEVICE);
}

void smc_rmb_sync_sg_for_cpu(struct smc_connection *conn)
{
        struct smc_link_group *lgr = conn->lgr;

        if (!conn->lgr || conn->lgr->is_smcd)
                return;
        smc_ib_sync_sg_for_cpu(lgr->lnk[SMC_SINGLE_LINK].smcibdev,
                               conn->rmb_desc, DMA_FROM_DEVICE);
}

void smc_rmb_sync_sg_for_device(struct smc_connection *conn)
{
        struct smc_link_group *lgr = conn->lgr;

        if (!conn->lgr || conn->lgr->is_smcd)
                return;
        smc_ib_sync_sg_for_device(lgr->lnk[SMC_SINGLE_LINK].smcibdev,
                                  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;
}

/* add a new rtoken from peer */
int smc_rtoken_add(struct smc_link_group *lgr, __be64 nw_vaddr, __be32 nw_rkey)
{
        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][SMC_SINGLE_LINK].rkey == rkey) &&
                    (lgr->rtokens[i][SMC_SINGLE_LINK].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][SMC_SINGLE_LINK].rkey = rkey;
        lgr->rtokens[i][SMC_SINGLE_LINK].dma_addr = dma_addr;
        return i;
}

/* delete an rtoken */
int smc_rtoken_delete(struct smc_link_group *lgr, __be32 nw_rkey)
{
        u32 rkey = ntohl(nw_rkey);
        int i;

        for (i = 0; i < SMC_RMBS_PER_LGR_MAX; i++) {
                if (lgr->rtokens[i][SMC_SINGLE_LINK].rkey == rkey &&
                    test_bit(i, lgr->rtokens_used_mask)) {
                        lgr->rtokens[i][SMC_SINGLE_LINK].rkey = 0;
                        lgr->rtokens[i][SMC_SINGLE_LINK].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_clc_msg_accept_confirm *clc)
{
        conn->rtoken_idx = smc_rtoken_add(conn->lgr, clc->rmb_dma_addr,
                                          clc->rmb_rkey);
        if (conn->rtoken_idx < 0)
                return conn->rtoken_idx;
        return 0;
}

/* Called (from smc_exit) when module is removed */
void smc_core_exit(void)
{
        struct smc_link_group *lgr, *lg;
        LIST_HEAD(lgr_freeing_list);

        spin_lock_bh(&smc_lgr_list.lock);
        if (!list_empty(&smc_lgr_list.list))
                list_splice_init(&smc_lgr_list.list, &lgr_freeing_list);
        spin_unlock_bh(&smc_lgr_list.lock);
        list_for_each_entry_safe(lgr, lg, &lgr_freeing_list, list) {
                list_del_init(&lgr->list);
                if (!lgr->is_smcd) {
                        struct smc_link *lnk = &lgr->lnk[SMC_SINGLE_LINK];

                        if (lnk->state == SMC_LNK_ACTIVE)
                                smc_llc_send_delete_link(lnk, SMC_LLC_REQ,
                                                         false);
                        smc_llc_link_inactive(lnk);
                }
                cancel_delayed_work_sync(&lgr->free_work);
                if (lgr->is_smcd)
                        smc_ism_signal_shutdown(lgr);
                smc_lgr_free(lgr); /* free link group */
        }
}