drivers/target/target_core_hba.c

   1 /*******************************************************************************
   2  * Filename:  target_core_hba.c
   3  *
   4  * This file contains the TCM HBA Transport related functions.
   5  *
   6  * (c) Copyright 2003-2013 Datera, Inc.
   7  *
   8  * Nicholas A. Bellinger <nab@kernel.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  23  *
  24  ******************************************************************************/
  25
  26 #include <linux/net.h>
  27 #include <linux/string.h>
  28 #include <linux/timer.h>
  29 #include <linux/slab.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/in.h>
  32 #include <linux/module.h>
  33 #include <net/sock.h>
  34 #include <net/tcp.h>
  35
  36 #include <target/target_core_base.h>
  37 #include <target/target_core_backend.h>
  38 #include <target/target_core_fabric.h>
  39
  40 #include "target_core_internal.h"
  41
  42 static LIST_HEAD(backend_list);
  43 static DEFINE_MUTEX(backend_mutex);
  44
  45 static u32 hba_id_counter;
  46
  47 static DEFINE_SPINLOCK(hba_lock);
  48 static LIST_HEAD(hba_list);
  49
  50
  51 int transport_backend_register(const struct target_backend_ops *ops)
  52 {
  53         struct target_backend *tb, *old;
  54
  55         tb = kzalloc(sizeof(*tb), GFP_KERNEL);
  56         if (!tb)
  57                 return -ENOMEM;
  58         tb->ops = ops;
  59
  60         mutex_lock(&backend_mutex);
  61         list_for_each_entry(old, &backend_list, list) {
  62                 if (!strcmp(old->ops->name, ops->name)) {
  63                         pr_err("backend %s already registered.\n", ops->name);
  64                         mutex_unlock(&backend_mutex);
  65                         kfree(tb);
  66                         return -EEXIST;
  67                 }
  68         }
  69         target_setup_backend_cits(tb);
  70         list_add_tail(&tb->list, &backend_list);
  71         mutex_unlock(&backend_mutex);
  72
  73         pr_debug("TCM: Registered subsystem plugin: %s struct module: %p\n",
  74                         ops->name, ops->owner);
  75         return 0;
  76 }
  77 EXPORT_SYMBOL(transport_backend_register);
  78
  79 void target_backend_unregister(const struct target_backend_ops *ops)
  80 {
  81         struct target_backend *tb;
  82
  83         mutex_lock(&backend_mutex);
  84         list_for_each_entry(tb, &backend_list, list) {
  85                 if (tb->ops == ops) {
  86                         list_del(&tb->list);
  87                         mutex_unlock(&backend_mutex);
  88                         /*
  89                          * Wait for any outstanding backend driver ->rcu_head
  90                          * callbacks to complete post TBO->free_device() ->
  91                          * call_rcu(), before allowing backend driver module
  92                          * unload of target_backend_ops->owner to proceed.
  93                          */
  94                         rcu_barrier();
  95                         kfree(tb);
  96                         return;
  97                 }
  98         }
  99         mutex_unlock(&backend_mutex);
 100 }
 101 EXPORT_SYMBOL(target_backend_unregister);
 102
 103 static struct target_backend *core_get_backend(const char *name)
 104 {
 105         struct target_backend *tb;
 106
 107         mutex_lock(&backend_mutex);
 108         list_for_each_entry(tb, &backend_list, list) {
 109                 if (!strcmp(tb->ops->name, name))
 110                         goto found;
 111         }
 112         mutex_unlock(&backend_mutex);
 113         return NULL;
 114 found:
 115         if (tb->ops->owner && !try_module_get(tb->ops->owner))
 116                 tb = NULL;
 117         mutex_unlock(&backend_mutex);
 118         return tb;
 119 }
 120
 121 struct se_hba *
 122 core_alloc_hba(const char *plugin_name, u32 plugin_dep_id, u32 hba_flags)
 123 {
 124         struct se_hba *hba;
 125         int ret = 0;
 126
 127         hba = kzalloc(sizeof(*hba), GFP_KERNEL);
 128         if (!hba) {
 129                 pr_err("Unable to allocate struct se_hba\n");
 130                 return ERR_PTR(-ENOMEM);
 131         }
 132
 133         spin_lock_init(&hba->device_lock);
 134         mutex_init(&hba->hba_access_mutex);
 135
 136         hba->hba_index = scsi_get_new_index(SCSI_INST_INDEX);
 137         hba->hba_flags |= hba_flags;
 138
 139         hba->backend = core_get_backend(plugin_name);
 140         if (!hba->backend) {
 141                 ret = -EINVAL;
 142                 goto out_free_hba;
 143         }
 144
 145         ret = hba->backend->ops->attach_hba(hba, plugin_dep_id);
 146         if (ret < 0)
 147                 goto out_module_put;
 148
 149         spin_lock(&hba_lock);
 150         hba->hba_id = hba_id_counter++;
 151         list_add_tail(&hba->hba_node, &hba_list);
 152         spin_unlock(&hba_lock);
 153
 154         pr_debug("CORE_HBA[%d] - Attached HBA to Generic Target"
 155                         " Core\n", hba->hba_id);
 156
 157         return hba;
 158
 159 out_module_put:
 160         module_put(hba->backend->ops->owner);
 161         hba->backend = NULL;
 162 out_free_hba:
 163         kfree(hba);
 164         return ERR_PTR(ret);
 165 }
 166
 167 int
 168 core_delete_hba(struct se_hba *hba)
 169 {
 170         WARN_ON(hba->dev_count);
 171
 172         hba->backend->ops->detach_hba(hba);
 173
 174         spin_lock(&hba_lock);
 175         list_del(&hba->hba_node);
 176         spin_unlock(&hba_lock);
 177
 178         pr_debug("CORE_HBA[%d] - Detached HBA from Generic Target"
 179                         " Core\n", hba->hba_id);
 180
 181         module_put(hba->backend->ops->owner);
 182
 183         hba->backend = NULL;
 184         kfree(hba);
 185         return 0;
 186 }
 187
 188 bool target_sense_desc_format(struct se_device *dev)
 189 {
 190         return (dev) ? dev->transport->get_blocks(dev) > U32_MAX : false;
 191 }