drivers/target/target_core_hba.c

   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
  29 static LIST_HEAD(backend_list);
  30 static DEFINE_MUTEX(backend_mutex);
  31
  32 static u32 hba_id_counter;
  33
  34 static DEFINE_SPINLOCK(hba_lock);
  35 static LIST_HEAD(hba_list);
  36
  37
  38 int 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 }
  64 EXPORT_SYMBOL(transport_backend_register);
  65
  66 void 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 }
  88 EXPORT_SYMBOL(target_backend_unregister);
  89
  90 static 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;
 101 found:
 102         if (tb->ops->owner && !try_module_get(tb->ops->owner))
 103                 tb = NULL;
 104         mutex_unlock(&backend_mutex);
 105         return tb;
 106 }
 107
 108 struct se_hba *
 109 core_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
 146 out_module_put:
 147         module_put(hba->backend->ops->owner);
 148         hba->backend = NULL;
 149 out_free_hba:
 150         kfree(hba);
 151         return ERR_PTR(ret);
 152 }
 153
 154 int
 155 core_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
 175 bool target_sense_desc_format(struct se_device *dev)
 176 {
 177         return (dev) ? dev->transport->get_blocks(dev) > U32_MAX : false;
 178 }