LXR linux/drivers/target/target_core

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*******************************************************************************
   3 * Filename:  target_core_hba.c
   4 *
   5 * This file contains the TCM HBA Transport related functions.
   6 *
   7 * (c) Copyright 2003-2013 Datera, Inc.
   8 *
   9 * Nicholas A. Bellinger <nab@kernel.org>
  10 *
  11 ******************************************************************************/
  12
  13#include <linux/net.h>
  14#include <linux/string.h>
  15#include <linux/timer.h>
  16#include <linux/slab.h>
  17#include <linux/spinlock.h>
  18#include <linux/in.h>
  19#include <linux/module.h>
  20#include <net/sock.h>
  21#include <net/tcp.h>
  22
  23#include <target/target_core_base.h>
  24#include <target/target_core_backend.h>
  25#include <target/target_core_fabric.h>
  26
  27#include "target_core_internal.h"
  28
  29static LIST_HEAD(backend_list);
  30static DEFINE_MUTEX(backend_mutex);
  31
  32static u32 hba_id_counter;
  33
  34static DEFINE_SPINLOCK(hba_lock);
  35static LIST_HEAD(hba_list);
  36
  37
  38int transport_backend_register(const struct target_backend_ops *ops)
  39{
  40        struct target_backend *tb, *old;
  41
  42        tb = kzalloc(sizeof(*tb), GFP_KERNEL);
  43        if (!tb)
  44                return -ENOMEM;
  45        tb->ops = ops;
  46
  47        mutex_lock(&backend_mutex);
  48        list_for_each_entry(old, &backend_list, list) {
  49                if (!strcmp(old->ops->name, ops->name)) {
  50                        pr_err("backend %s already registered.\n", ops->name);
  51                        mutex_unlock(&backend_mutex);
  52                        kfree(tb);
  53                        return -EEXIST;
  54                }
  55        }
  56        target_setup_backend_cits(tb);
  57        list_add_tail(&tb->list, &backend_list);
  58        mutex_unlock(&backend_mutex);
  59
  60        pr_debug("TCM: Registered subsystem plugin: %s struct module: %p\n",
  61                        ops->name, ops->owner);
  62        return 0;
  63}
  64EXPORT_SYMBOL(transport_backend_register);
  65
  66void target_backend_unregister(const struct target_backend_ops *ops)
  67{
  68        struct target_backend *tb;
  69
  70        mutex_lock(&backend_mutex);
  71        list_for_each_entry(tb, &backend_list, list) {
  72                if (tb->ops == ops) {
  73                        list_del(&tb->list);
  74                        mutex_unlock(&backend_mutex);
  75                        /*
  76                         * Wait for any outstanding backend driver ->rcu_head
  77                         * callbacks to complete post TBO->free_device() ->
  78                         * call_rcu(), before allowing backend driver module
  79                         * unload of target_backend_ops->owner to proceed.
  80                         */
  81                        rcu_barrier();
  82                        kfree(tb);
  83                        return;
  84                }
  85        }
  86        mutex_unlock(&backend_mutex);
  87}
  88EXPORT_SYMBOL(target_backend_unregister);
  89
  90static struct target_backend *core_get_backend(const char *name)
  91{
  92        struct target_backend *tb;
  93
  94        mutex_lock(&backend_mutex);
  95        list_for_each_entry(tb, &backend_list, list) {
  96                if (!strcmp(tb->ops->name, name))
  97                        goto found;
  98        }
  99        mutex_unlock(&backend_mutex);
 100        return NULL;
 101found:
 102        if (tb->ops->owner && !try_module_get(tb->ops->owner))
 103                tb = NULL;
 104        mutex_unlock(&backend_mutex);
 105        return tb;
 106}
 107
 108struct se_hba *
 109core_alloc_hba(const char *plugin_name, u32 plugin_dep_id, u32 hba_flags)
 110{
 111        struct se_hba *hba;
 112        int ret = 0;
 113
 114        hba = kzalloc(sizeof(*hba), GFP_KERNEL);
 115        if (!hba) {
 116                pr_err("Unable to allocate struct se_hba\n");
 117                return ERR_PTR(-ENOMEM);
 118        }
 119
 120        spin_lock_init(&hba->device_lock);
 121        mutex_init(&hba->hba_access_mutex);
 122
 123        hba->hba_index = scsi_get_new_index(SCSI_INST_INDEX);
 124        hba->hba_flags |= hba_flags;
 125
 126        hba->backend = core_get_backend(plugin_name);
 127        if (!hba->backend) {
 128                ret = -EINVAL;
 129                goto out_free_hba;
 130        }
 131
 132        ret = hba->backend->ops->attach_hba(hba, plugin_dep_id);
 133        if (ret < 0)
 134                goto out_module_put;
 135
 136        spin_lock(&hba_lock);
 137        hba->hba_id = hba_id_counter++;
 138        list_add_tail(&hba->hba_node, &hba_list);
 139        spin_unlock(&hba_lock);
 140
 141        pr_debug("CORE_HBA[%d] - Attached HBA to Generic Target"
 142                        " Core\n", hba->hba_id);
 143
 144        return hba;
 145
 146out_module_put:
 147        module_put(hba->backend->ops->owner);
 148        hba->backend = NULL;
 149out_free_hba:
 150        kfree(hba);
 151        return ERR_PTR(ret);
 152}
 153
 154int
 155core_delete_hba(struct se_hba *hba)
 156{
 157        WARN_ON(hba->dev_count);
 158
 159        hba->backend->ops->detach_hba(hba);
 160
 161        spin_lock(&hba_lock);
 162        list_del(&hba->hba_node);
 163        spin_unlock(&hba_lock);
 164
 165        pr_debug("CORE_HBA[%d] - Detached HBA from Generic Target"
 166                        " Core\n", hba->hba_id);
 167
 168        module_put(hba->backend->ops->owner);
 169
 170        hba->backend = NULL;
 171        kfree(hba);
 172        return 0;
 173}
 174
 175bool target_sense_desc_format(struct se_device *dev)
 176{
 177        return (dev) ? dev->transport->get_blocks(dev) > U32_MAX : false;
 178}
 179