1 /*
2 * Copyright (c) 2006, 2017 Oracle and/or its affiliates. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33 #include <linux/kernel.h>
34 #include <linux/slab.h>
35 #include <linux/in.h>
36 #include <net/net_namespace.h>
37 #include <net/netns/generic.h>
38 #include <linux/ipv6.h>
39
40 #include "rds_single_path.h"
41 #include "rds.h"
42 #include "loop.h"
43
44 static DEFINE_SPINLOCK(loop_conns_lock);
45 static LIST_HEAD(loop_conns);
46 static atomic_t rds_loop_unloading = ATOMIC_INIT(0);
47
48 static void rds_loop_set_unloading(void)
49 {
50 atomic_set(&rds_loop_unloading, 1);
51 }
52
53 static bool rds_loop_is_unloading(struct rds_connection *conn)
54 {
55 return atomic_read(&rds_loop_unloading) != 0;
56 }
57
58 /*
59 * This 'loopback' transport is a special case for flows that originate
60 * and terminate on the same machine.
61 *
62 * Connection build-up notices if the destination address is thought of
63 * as a local address by a transport. At that time it decides to use the
64 * loopback transport instead of the bound transport of the sending socket.
65 *
66 * The loopback transport's sending path just hands the sent rds_message
67 * straight to the receiving path via an embedded rds_incoming.
68 */
69
70 /*
71 * Usually a message transits both the sender and receiver's conns as it
72 * flows to the receiver. In the loopback case, though, the receive path
73 * is handed the sending conn so the sense of the addresses is reversed.
74 */
75 static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
76 unsigned int hdr_off, unsigned int sg,
77 unsigned int off)
78 {
79 struct scatterlist *sgp = &rm->data.op_sg[sg];
80 int ret = sizeof(struct rds_header) +
81 be32_to_cpu(rm->m_inc.i_hdr.h_len);
82
83 /* Do not send cong updates to loopback */
84 if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
85 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
86 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
87 goto out;
88 }
89
90 BUG_ON(hdr_off || sg || off);
91
92 rds_inc_init(&rm->m_inc, conn, &conn->c_laddr);
93 /* For the embedded inc. Matching put is in loop_inc_free() */
94 rds_message_addref(rm);
95
96 rds_recv_incoming(conn, &conn->c_laddr, &conn->c_faddr, &rm->m_inc,
97 GFP_KERNEL);
98
99 rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
100 NULL);
101
102 rds_inc_put(&rm->m_inc);
103 out:
104 return ret;
105 }
106
107 /*
108 * See rds_loop_xmit(). Since our inc is embedded in the rm, we
109 * make sure the rm lives at least until the inc is done.
110 */
111 static void rds_loop_inc_free(struct rds_incoming *inc)
112 {
113 struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
114
115 rds_message_put(rm);
116 }
117
118 /* we need to at least give the thread something to succeed */
119 static int rds_loop_recv_path(struct rds_conn_path *cp)
120 {
121 return 0;
122 }
123
124 struct rds_loop_connection {
125 struct list_head loop_node;
126 struct rds_connection *conn;
127 };
128
129 /*
130 * Even the loopback transport needs to keep track of its connections,
131 * so it can call rds_conn_destroy() on them on exit. N.B. there are
132 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
133 * multiple loopback conns allocated, although rather useless.
134 */
135 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
136 {
137 struct rds_loop_connection *lc;
138 unsigned long flags;
139
140 lc = kzalloc(sizeof(struct rds_loop_connection), gfp);
141 if (!lc)
142 return -ENOMEM;
143
144 INIT_LIST_HEAD(&lc->loop_node);
145 lc->conn = conn;
146 conn->c_transport_data = lc;
147
148 spin_lock_irqsave(&loop_conns_lock, flags);
149 list_add_tail(&lc->loop_node, &loop_conns);
150 spin_unlock_irqrestore(&loop_conns_lock, flags);
151
152 return 0;
153 }
154
155 static void rds_loop_conn_free(void *arg)
156 {
157 struct rds_loop_connection *lc = arg;
158 unsigned long flags;
159
160 rdsdebug("lc %p\n", lc);
161 spin_lock_irqsave(&loop_conns_lock, flags);
162 list_del(&lc->loop_node);
163 spin_unlock_irqrestore(&loop_conns_lock, flags);
164 kfree(lc);
165 }
166
167 static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
168 {
169 rds_connect_complete(cp->cp_conn);
170 return 0;
171 }
172
173 static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
174 {
175 }
176
177 void rds_loop_exit(void)
178 {
179 struct rds_loop_connection *lc, *_lc;
180 LIST_HEAD(tmp_list);
181
182 rds_loop_set_unloading();
183 synchronize_rcu();
184 /* avoid calling conn_destroy with irqs off */
185 spin_lock_irq(&loop_conns_lock);
186 list_splice(&loop_conns, &tmp_list);
187 INIT_LIST_HEAD(&loop_conns);
188 spin_unlock_irq(&loop_conns_lock);
189
190 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
191 WARN_ON(lc->conn->c_passive);
192 rds_conn_destroy(lc->conn);
193 }
194 }
195
196 static void rds_loop_kill_conns(struct net *net)
197 {
198 struct rds_loop_connection *lc, *_lc;
199 LIST_HEAD(tmp_list);
200
201 spin_lock_irq(&loop_conns_lock);
202 list_for_each_entry_safe(lc, _lc, &loop_conns, loop_node) {
203 struct net *c_net = read_pnet(&lc->conn->c_net);
204
205 if (net != c_net)
206 continue;
207 list_move_tail(&lc->loop_node, &tmp_list);
208 }
209 spin_unlock_irq(&loop_conns_lock);
210
211 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
212 WARN_ON(lc->conn->c_passive);
213 rds_conn_destroy(lc->conn);
214 }
215 }
216
217 static void __net_exit rds_loop_exit_net(struct net *net)
218 {
219 rds_loop_kill_conns(net);
220 }
221
222 static struct pernet_operations rds_loop_net_ops = {
223 .exit = rds_loop_exit_net,
224 };
225
226 int rds_loop_net_init(void)
227 {
228 return register_pernet_device(&rds_loop_net_ops);
229 }
230
231 void rds_loop_net_exit(void)
232 {
233 unregister_pernet_device(&rds_loop_net_ops);
234 }
235
236 /*
237 * This is missing .xmit_* because loop doesn't go through generic
238 * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and
239 * .laddr_check are missing because transport.c doesn't iterate over
240 * rds_loop_transport.
241 */
242 struct rds_transport rds_loop_transport = {
243 .xmit = rds_loop_xmit,
244 .recv_path = rds_loop_recv_path,
245 .conn_alloc = rds_loop_conn_alloc,
246 .conn_free = rds_loop_conn_free,
247 .conn_path_connect = rds_loop_conn_path_connect,
248 .conn_path_shutdown = rds_loop_conn_path_shutdown,
249 .inc_copy_to_user = rds_message_inc_copy_to_user,
250 .inc_free = rds_loop_inc_free,
251 .t_name = "loopback",
252 .t_type = RDS_TRANS_LOOP,
253 .t_unloading = rds_loop_is_unloading,
254 };
255
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