target_core_hba.c

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/*******************************************************************************
 * Filename:  target_core_hba.c
 *
 * This file contains the TCM HBA Transport related functions.
 *
 * Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
 * Copyright (c) 2005, 2006, 2007 SBE, Inc.
 * Copyright (c) 2007-2010 Rising Tide Systems
 * Copyright (c) 2008-2010 Linux-iSCSI.org
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

#include <linux/net.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/in.h>
#include <linux/module.h>
#include <net/sock.h>
#include <net/tcp.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>
#include <target/target_core_fabric.h>

#include "target_core_internal.h"

static LIST_HEAD(subsystem_list);
static DEFINE_MUTEX(subsystem_mutex);

static u32 hba_id_counter;

static DEFINE_SPINLOCK(hba_lock);
static LIST_HEAD(hba_list);

int transport_subsystem_register(struct se_subsystem_api *sub_api)
{
    struct se_subsystem_api *s;

    INIT_LIST_HEAD(&sub_api->sub_api_list);

    mutex_lock(&subsystem_mutex);
    list_for_each_entry(s, &subsystem_list, sub_api_list) {
        if (!strcmp(s->name, sub_api->name)) {
            pr_err("%p is already registered with"
                " duplicate name %s, unable to process"
                " request\n", s, s->name);
            mutex_unlock(&subsystem_mutex);
            return -EEXIST;
        }
    }
    list_add_tail(&sub_api->sub_api_list, &subsystem_list);
    mutex_unlock(&subsystem_mutex);

    pr_debug("TCM: Registered subsystem plugin: %s struct module:"
            " %p\n", sub_api->name, sub_api->owner);
    return 0;
}
EXPORT_SYMBOL(transport_subsystem_register);

void transport_subsystem_release(struct se_subsystem_api *sub_api)
{
    mutex_lock(&subsystem_mutex);
    list_del(&sub_api->sub_api_list);
    mutex_unlock(&subsystem_mutex);
}
EXPORT_SYMBOL(transport_subsystem_release);

static struct se_subsystem_api *core_get_backend(const char *sub_name)
{
    struct se_subsystem_api *s;

    mutex_lock(&subsystem_mutex);
    list_for_each_entry(s, &subsystem_list, sub_api_list) {
        if (!strcmp(s->name, sub_name))
            goto found;
    }
    mutex_unlock(&subsystem_mutex);
    return NULL;
found:
    if (s->owner && !try_module_get(s->owner))
        s = NULL;
    mutex_unlock(&subsystem_mutex);
    return s;
}

struct se_hba *
core_alloc_hba(const char *plugin_name, u32 plugin_dep_id, u32 hba_flags)
{
    struct se_hba *hba;
    int ret = 0;

    hba = kzalloc(sizeof(*hba), GFP_KERNEL);
    if (!hba) {
        pr_err("Unable to allocate struct se_hba\n");
        return ERR_PTR(-ENOMEM);
    }

    INIT_LIST_HEAD(&hba->hba_dev_list);
    spin_lock_init(&hba->device_lock);
    mutex_init(&hba->hba_access_mutex);

    hba->hba_index = scsi_get_new_index(SCSI_INST_INDEX);
    hba->hba_flags |= hba_flags;

    hba->transport = core_get_backend(plugin_name);
    if (!hba->transport) {
        ret = -EINVAL;
        goto out_free_hba;
    }

    ret = hba->transport->attach_hba(hba, plugin_dep_id);
    if (ret < 0)
        goto out_module_put;

    spin_lock(&hba_lock);
    hba->hba_id = hba_id_counter++;
    list_add_tail(&hba->hba_node, &hba_list);
    spin_unlock(&hba_lock);

    pr_debug("CORE_HBA[%d] - Attached HBA to Generic Target"
            " Core\n", hba->hba_id);

    return hba;

out_module_put:
    if (hba->transport->owner)
        module_put(hba->transport->owner);
    hba->transport = NULL;
out_free_hba:
    kfree(hba);
    return ERR_PTR(ret);
}

int
core_delete_hba(struct se_hba *hba)
{
    if (!list_empty(&hba->hba_dev_list))
        dump_stack();

    hba->transport->detach_hba(hba);

    spin_lock(&hba_lock);
    list_del(&hba->hba_node);
    spin_unlock(&hba_lock);

    pr_debug("CORE_HBA[%d] - Detached HBA from Generic Target"
            " Core\n", hba->hba_id);

    if (hba->transport->owner)
        module_put(hba->transport->owner);

    hba->transport = NULL;
    kfree(hba);
    return 0;
}