tfc_sess.c

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/*
 * Copyright (c) 2010 Cisco Systems, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* XXX TBD some includes may be extraneous */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/utsname.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/configfs.h>
#include <linux/ctype.h>
#include <linux/hash.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/kref.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/libfc.h>

#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/target_core_configfs.h>
#include <target/configfs_macros.h>

#include "tcm_fc.h"

static void ft_sess_delete_all(struct ft_tport *);

/*
 * Lookup or allocate target local port.
 * Caller holds ft_lport_lock.
 */
static struct ft_tport *ft_tport_create(struct fc_lport *lport)
{
    struct ft_tpg *tpg;
    struct ft_tport *tport;
    int i;

    tport = rcu_dereference_protected(lport->prov[FC_TYPE_FCP],
                      lockdep_is_held(&ft_lport_lock));
    if (tport && tport->tpg)
        return tport;

    tpg = ft_lport_find_tpg(lport);
    if (!tpg)
        return NULL;

    if (tport) {
        tport->tpg = tpg;
        return tport;
    }

    tport = kzalloc(sizeof(*tport), GFP_KERNEL);
    if (!tport)
        return NULL;

    tport->lport = lport;
    tport->tpg = tpg;
    tpg->tport = tport;
    for (i = 0; i < FT_SESS_HASH_SIZE; i++)
        INIT_HLIST_HEAD(&tport->hash[i]);

    rcu_assign_pointer(lport->prov[FC_TYPE_FCP], tport);
    return tport;
}

/*
 * Delete a target local port.
 * Caller holds ft_lport_lock.
 */
static void ft_tport_delete(struct ft_tport *tport)
{
    struct fc_lport *lport;
    struct ft_tpg *tpg;

    ft_sess_delete_all(tport);
    lport = tport->lport;
    BUG_ON(tport != lport->prov[FC_TYPE_FCP]);
    rcu_assign_pointer(lport->prov[FC_TYPE_FCP], NULL);

    tpg = tport->tpg;
    if (tpg) {
        tpg->tport = NULL;
        tport->tpg = NULL;
    }
    kfree_rcu(tport, rcu);
}

/*
 * Add local port.
 * Called thru fc_lport_iterate().
 */
void ft_lport_add(struct fc_lport *lport, void *arg)
{
    mutex_lock(&ft_lport_lock);
    ft_tport_create(lport);
    mutex_unlock(&ft_lport_lock);
}

/*
 * Delete local port.
 * Called thru fc_lport_iterate().
 */
void ft_lport_del(struct fc_lport *lport, void *arg)
{
    struct ft_tport *tport;

    mutex_lock(&ft_lport_lock);
    tport = lport->prov[FC_TYPE_FCP];
    if (tport)
        ft_tport_delete(tport);
    mutex_unlock(&ft_lport_lock);
}

/*
 * Notification of local port change from libfc.
 * Create or delete local port and associated tport.
 */
int ft_lport_notify(struct notifier_block *nb, unsigned long event, void *arg)
{
    struct fc_lport *lport = arg;

    switch (event) {
    case FC_LPORT_EV_ADD:
        ft_lport_add(lport, NULL);
        break;
    case FC_LPORT_EV_DEL:
        ft_lport_del(lport, NULL);
        break;
    }
    return NOTIFY_DONE;
}

/*
 * Hash function for FC_IDs.
 */
static u32 ft_sess_hash(u32 port_id)
{
    return hash_32(port_id, FT_SESS_HASH_BITS);
}

/*
 * Find session in local port.
 * Sessions and hash lists are RCU-protected.
 * A reference is taken which must be eventually freed.
 */
static struct ft_sess *ft_sess_get(struct fc_lport *lport, u32 port_id)
{
    struct ft_tport *tport;
    struct hlist_head *head;
    struct hlist_node *pos;
    struct ft_sess *sess;

    rcu_read_lock();
    tport = rcu_dereference(lport->prov[FC_TYPE_FCP]);
    if (!tport)
        goto out;

    head = &tport->hash[ft_sess_hash(port_id)];
    hlist_for_each_entry_rcu(sess, pos, head, hash) {
        if (sess->port_id == port_id) {
            kref_get(&sess->kref);
            rcu_read_unlock();
            pr_debug("port_id %x found %p\n", port_id, sess);
            return sess;
        }
    }
out:
    rcu_read_unlock();
    pr_debug("port_id %x not found\n", port_id);
    return NULL;
}

/*
 * Allocate session and enter it in the hash for the local port.
 * Caller holds ft_lport_lock.
 */
static struct ft_sess *ft_sess_create(struct ft_tport *tport, u32 port_id,
                      struct ft_node_acl *acl)
{
    struct ft_sess *sess;
    struct hlist_head *head;
    struct hlist_node *pos;

    head = &tport->hash[ft_sess_hash(port_id)];
    hlist_for_each_entry_rcu(sess, pos, head, hash)
        if (sess->port_id == port_id)
            return sess;

    sess = kzalloc(sizeof(*sess), GFP_KERNEL);
    if (!sess)
        return NULL;

    sess->se_sess = transport_init_session();
    if (IS_ERR(sess->se_sess)) {
        kfree(sess);
        return NULL;
    }
    sess->se_sess->se_node_acl = &acl->se_node_acl;
    sess->tport = tport;
    sess->port_id = port_id;
    kref_init(&sess->kref); /* ref for table entry */
    hlist_add_head_rcu(&sess->hash, head);
    tport->sess_count++;

    pr_debug("port_id %x sess %p\n", port_id, sess);

    transport_register_session(&tport->tpg->se_tpg, &acl->se_node_acl,
                   sess->se_sess, sess);
    return sess;
}

/*
 * Unhash the session.
 * Caller holds ft_lport_lock.
 */
static void ft_sess_unhash(struct ft_sess *sess)
{
    struct ft_tport *tport = sess->tport;

    hlist_del_rcu(&sess->hash);
    BUG_ON(!tport->sess_count);
    tport->sess_count--;
    sess->port_id = -1;
    sess->params = 0;
}

/*
 * Delete session from hash.
 * Caller holds ft_lport_lock.
 */
static struct ft_sess *ft_sess_delete(struct ft_tport *tport, u32 port_id)
{
    struct hlist_head *head;
    struct hlist_node *pos;
    struct ft_sess *sess;

    head = &tport->hash[ft_sess_hash(port_id)];
    hlist_for_each_entry_rcu(sess, pos, head, hash) {
        if (sess->port_id == port_id) {
            ft_sess_unhash(sess);
            return sess;
        }
    }
    return NULL;
}

/*
 * Delete all sessions from tport.
 * Caller holds ft_lport_lock.
 */
static void ft_sess_delete_all(struct ft_tport *tport)
{
    struct hlist_head *head;
    struct hlist_node *pos;
    struct ft_sess *sess;

    for (head = tport->hash;
         head < &tport->hash[FT_SESS_HASH_SIZE]; head++) {
        hlist_for_each_entry_rcu(sess, pos, head, hash) {
            ft_sess_unhash(sess);
            transport_deregister_session_configfs(sess->se_sess);
            ft_sess_put(sess);  /* release from table */
        }
    }
}

/*
 * TCM ops for sessions.
 */

/*
 * Determine whether session is allowed to be shutdown in the current context.
 * Returns non-zero if the session should be shutdown.
 */
int ft_sess_shutdown(struct se_session *se_sess)
{
    struct ft_sess *sess = se_sess->fabric_sess_ptr;

    pr_debug("port_id %x\n", sess->port_id);
    return 1;
}

/*
 * Remove session and send PRLO.
 * This is called when the ACL is being deleted or queue depth is changing.
 */
void ft_sess_close(struct se_session *se_sess)
{
    struct ft_sess *sess = se_sess->fabric_sess_ptr;
    u32 port_id;

    mutex_lock(&ft_lport_lock);
    port_id = sess->port_id;
    if (port_id == -1) {
        mutex_unlock(&ft_lport_lock);
        return;
    }
    pr_debug("port_id %x\n", port_id);
    ft_sess_unhash(sess);
    mutex_unlock(&ft_lport_lock);
    transport_deregister_session_configfs(se_sess);
    ft_sess_put(sess);
    /* XXX Send LOGO or PRLO */
    synchronize_rcu();      /* let transport deregister happen */
}

u32 ft_sess_get_index(struct se_session *se_sess)
{
    struct ft_sess *sess = se_sess->fabric_sess_ptr;

    return sess->port_id;   /* XXX TBD probably not what is needed */
}

u32 ft_sess_get_port_name(struct se_session *se_sess,
              unsigned char *buf, u32 len)
{
    struct ft_sess *sess = se_sess->fabric_sess_ptr;

    return ft_format_wwn(buf, len, sess->port_name);
}

/*
 * libfc ops involving sessions.
 */

static int ft_prli_locked(struct fc_rport_priv *rdata, u32 spp_len,
              const struct fc_els_spp *rspp, struct fc_els_spp *spp)
{
    struct ft_tport *tport;
    struct ft_sess *sess;
    struct ft_node_acl *acl;
    u32 fcp_parm;

    tport = ft_tport_create(rdata->local_port);
    if (!tport)
        return 0;   /* not a target for this local port */

    acl = ft_acl_get(tport->tpg, rdata);
    if (!acl)
        return 0;

    if (!rspp)
        goto fill;

    if (rspp->spp_flags & (FC_SPP_OPA_VAL | FC_SPP_RPA_VAL))
        return FC_SPP_RESP_NO_PA;

    /*
     * If both target and initiator bits are off, the SPP is invalid.
     */
    fcp_parm = ntohl(rspp->spp_params);
    if (!(fcp_parm & (FCP_SPPF_INIT_FCN | FCP_SPPF_TARG_FCN)))
        return FC_SPP_RESP_INVL;

    /*
     * Create session (image pair) only if requested by
     * EST_IMG_PAIR flag and if the requestor is an initiator.
     */
    if (rspp->spp_flags & FC_SPP_EST_IMG_PAIR) {
        spp->spp_flags |= FC_SPP_EST_IMG_PAIR;
        if (!(fcp_parm & FCP_SPPF_INIT_FCN))
            return FC_SPP_RESP_CONF;
        sess = ft_sess_create(tport, rdata->ids.port_id, acl);
        if (!sess)
            return FC_SPP_RESP_RES;
        if (!sess->params)
            rdata->prli_count++;
        sess->params = fcp_parm;
        sess->port_name = rdata->ids.port_name;
        sess->max_frame = rdata->maxframe_size;

        /* XXX TBD - clearing actions.  unit attn, see 4.10 */
    }

    /*
     * OR in our service parameters with other provider (initiator), if any.
     * TBD XXX - indicate RETRY capability?
     */
fill:
    fcp_parm = ntohl(spp->spp_params);
    spp->spp_params = htonl(fcp_parm | FCP_SPPF_TARG_FCN);
    return FC_SPP_RESP_ACK;
}

static int ft_prli(struct fc_rport_priv *rdata, u32 spp_len,
           const struct fc_els_spp *rspp, struct fc_els_spp *spp)
{
    int ret;

    mutex_lock(&ft_lport_lock);
    ret = ft_prli_locked(rdata, spp_len, rspp, spp);
    mutex_unlock(&ft_lport_lock);
    pr_debug("port_id %x flags %x ret %x\n",
           rdata->ids.port_id, rspp ? rspp->spp_flags : 0, ret);
    return ret;
}

static void ft_sess_rcu_free(struct rcu_head *rcu)
{
    struct ft_sess *sess = container_of(rcu, struct ft_sess, rcu);

    transport_deregister_session(sess->se_sess);
    kfree(sess);
}

static void ft_sess_free(struct kref *kref)
{
    struct ft_sess *sess = container_of(kref, struct ft_sess, kref);

    call_rcu(&sess->rcu, ft_sess_rcu_free);
}

void ft_sess_put(struct ft_sess *sess)
{
    int sess_held = atomic_read(&sess->kref.refcount);

    BUG_ON(!sess_held);
    kref_put(&sess->kref, ft_sess_free);
}

static void ft_prlo(struct fc_rport_priv *rdata)
{
    struct ft_sess *sess;
    struct ft_tport *tport;

    mutex_lock(&ft_lport_lock);
    tport = rcu_dereference_protected(rdata->local_port->prov[FC_TYPE_FCP],
                      lockdep_is_held(&ft_lport_lock));

    if (!tport) {
        mutex_unlock(&ft_lport_lock);
        return;
    }
    sess = ft_sess_delete(tport, rdata->ids.port_id);
    if (!sess) {
        mutex_unlock(&ft_lport_lock);
        return;
    }
    mutex_unlock(&ft_lport_lock);
    transport_deregister_session_configfs(sess->se_sess);
    ft_sess_put(sess);      /* release from table */
    rdata->prli_count--;
    /* XXX TBD - clearing actions.  unit attn, see 4.10 */
}

/*
 * Handle incoming FCP request.
 * Caller has verified that the frame is type FCP.
 */
static void ft_recv(struct fc_lport *lport, struct fc_frame *fp)
{
    struct ft_sess *sess;
    u32 sid = fc_frame_sid(fp);

    pr_debug("sid %x\n", sid);

    sess = ft_sess_get(lport, sid);
    if (!sess) {
        pr_debug("sid %x sess lookup failed\n", sid);
        /* TBD XXX - if FCP_CMND, send PRLO */
        fc_frame_free(fp);
        return;
    }
    ft_recv_req(sess, fp);  /* must do ft_sess_put() */
}

/*
 * Provider ops for libfc.
 */
struct fc4_prov ft_prov = {
    .prli = ft_prli,
    .prlo = ft_prlo,
    .recv = ft_recv,
    .module = THIS_MODULE,
};