Root/net/rds/loop.c

1/*
2 * Copyright (c) 2006 Oracle. 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
37#include "rds.h"
38#include "loop.h"
39
40static DEFINE_SPINLOCK(loop_conns_lock);
41static LIST_HEAD(loop_conns);
42
43/*
44 * This 'loopback' transport is a special case for flows that originate
45 * and terminate on the same machine.
46 *
47 * Connection build-up notices if the destination address is thought of
48 * as a local address by a transport. At that time it decides to use the
49 * loopback transport instead of the bound transport of the sending socket.
50 *
51 * The loopback transport's sending path just hands the sent rds_message
52 * straight to the receiving path via an embedded rds_incoming.
53 */
54
55/*
56 * Usually a message transits both the sender and receiver's conns as it
57 * flows to the receiver. In the loopback case, though, the receive path
58 * is handed the sending conn so the sense of the addresses is reversed.
59 */
60static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
61             unsigned int hdr_off, unsigned int sg,
62             unsigned int off)
63{
64    BUG_ON(hdr_off || sg || off);
65
66    rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
67    rds_message_addref(rm); /* for the inc */
68
69    rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
70              GFP_KERNEL, KM_USER0);
71
72    rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
73                NULL);
74
75    rds_inc_put(&rm->m_inc);
76
77    return sizeof(struct rds_header) + be32_to_cpu(rm->m_inc.i_hdr.h_len);
78}
79
80static int rds_loop_xmit_cong_map(struct rds_connection *conn,
81                  struct rds_cong_map *map,
82                  unsigned long offset)
83{
84    unsigned long i;
85
86    BUG_ON(offset);
87    BUG_ON(map != conn->c_lcong);
88
89    for (i = 0; i < RDS_CONG_MAP_PAGES; i++) {
90        memcpy((void *)conn->c_fcong->m_page_addrs[i],
91               (void *)map->m_page_addrs[i], PAGE_SIZE);
92    }
93
94    rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
95
96    return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
97}
98
99/* we need to at least give the thread something to succeed */
100static int rds_loop_recv(struct rds_connection *conn)
101{
102    return 0;
103}
104
105struct rds_loop_connection {
106    struct list_head loop_node;
107    struct rds_connection *conn;
108};
109
110/*
111 * Even the loopback transport needs to keep track of its connections,
112 * so it can call rds_conn_destroy() on them on exit. N.B. there are
113 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
114 * multiple loopback conns allocated, although rather useless.
115 */
116static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
117{
118    struct rds_loop_connection *lc;
119    unsigned long flags;
120
121    lc = kzalloc(sizeof(struct rds_loop_connection), GFP_KERNEL);
122    if (lc == NULL)
123        return -ENOMEM;
124
125    INIT_LIST_HEAD(&lc->loop_node);
126    lc->conn = conn;
127    conn->c_transport_data = lc;
128
129    spin_lock_irqsave(&loop_conns_lock, flags);
130    list_add_tail(&lc->loop_node, &loop_conns);
131    spin_unlock_irqrestore(&loop_conns_lock, flags);
132
133    return 0;
134}
135
136static void rds_loop_conn_free(void *arg)
137{
138    struct rds_loop_connection *lc = arg;
139    rdsdebug("lc %p\n", lc);
140    list_del(&lc->loop_node);
141    kfree(lc);
142}
143
144static int rds_loop_conn_connect(struct rds_connection *conn)
145{
146    rds_connect_complete(conn);
147    return 0;
148}
149
150static void rds_loop_conn_shutdown(struct rds_connection *conn)
151{
152}
153
154void rds_loop_exit(void)
155{
156    struct rds_loop_connection *lc, *_lc;
157    LIST_HEAD(tmp_list);
158
159    /* avoid calling conn_destroy with irqs off */
160    spin_lock_irq(&loop_conns_lock);
161    list_splice(&loop_conns, &tmp_list);
162    INIT_LIST_HEAD(&loop_conns);
163    spin_unlock_irq(&loop_conns_lock);
164
165    list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
166        WARN_ON(lc->conn->c_passive);
167        rds_conn_destroy(lc->conn);
168    }
169}
170
171/*
172 * This is missing .xmit_* because loop doesn't go through generic
173 * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and
174 * .laddr_check are missing because transport.c doesn't iterate over
175 * rds_loop_transport.
176 */
177struct rds_transport rds_loop_transport = {
178    .xmit = rds_loop_xmit,
179    .xmit_cong_map = rds_loop_xmit_cong_map,
180    .recv = rds_loop_recv,
181    .conn_alloc = rds_loop_conn_alloc,
182    .conn_free = rds_loop_conn_free,
183    .conn_connect = rds_loop_conn_connect,
184    .conn_shutdown = rds_loop_conn_shutdown,
185    .inc_copy_to_user = rds_message_inc_copy_to_user,
186    .inc_purge = rds_message_inc_purge,
187    .inc_free = rds_message_inc_free,
188    .t_name = "loopback",
189};
190

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