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 }
192