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 40 static DEFINE_SPINLOCK(loop_conns_lock); 41 static 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 */ 60 static 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 /* Do not send cong updates to loopback */ 65 if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) { 66 rds_cong_map_updated(conn->c_fcong, ~(u64) 0); 67 return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES; 68 } 69 70 BUG_ON(hdr_off || sg || off); 71 72 rds_inc_init(&rm->m_inc, conn, conn->c_laddr); 73 /* For the embedded inc. Matching put is in loop_inc_free() */ 74 rds_message_addref(rm); 75 76 rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc, 77 GFP_KERNEL, KM_USER0); 78 79 rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence), 80 NULL); 81 82 rds_inc_put(&rm->m_inc); 83 84 return sizeof(struct rds_header) + be32_to_cpu(rm->m_inc.i_hdr.h_len); 85 } 86 87 /* 88 * See rds_loop_xmit(). Since our inc is embedded in the rm, we 89 * make sure the rm lives at least until the inc is done. 90 */ 91 static void rds_loop_inc_free(struct rds_incoming *inc) 92 { 93 struct rds_message *rm = container_of(inc, struct rds_message, m_inc); 94 rds_message_put(rm); 95 } 96 97 /* we need to at least give the thread something to succeed */ 98 static int rds_loop_recv(struct rds_connection *conn) 99 { 100 return 0; 101 } 102 103 struct rds_loop_connection { 104 struct list_head loop_node; 105 struct rds_connection *conn; 106 }; 107 108 /* 109 * Even the loopback transport needs to keep track of its connections, 110 * so it can call rds_conn_destroy() on them on exit. N.B. there are 111 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have 112 * multiple loopback conns allocated, although rather useless. 113 */ 114 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp) 115 { 116 struct rds_loop_connection *lc; 117 unsigned long flags; 118 119 lc = kzalloc(sizeof(struct rds_loop_connection), GFP_KERNEL); 120 if (!lc) 121 return -ENOMEM; 122 123 INIT_LIST_HEAD(&lc->loop_node); 124 lc->conn = conn; 125 conn->c_transport_data = lc; 126 127 spin_lock_irqsave(&loop_conns_lock, flags); 128 list_add_tail(&lc->loop_node, &loop_conns); 129 spin_unlock_irqrestore(&loop_conns_lock, flags); 130 131 return 0; 132 } 133 134 static void rds_loop_conn_free(void *arg) 135 { 136 struct rds_loop_connection *lc = arg; 137 rdsdebug("lc %p\n", lc); 138 list_del(&lc->loop_node); 139 kfree(lc); 140 } 141 142 static int rds_loop_conn_connect(struct rds_connection *conn) 143 { 144 rds_connect_complete(conn); 145 return 0; 146 } 147 148 static void rds_loop_conn_shutdown(struct rds_connection *conn) 149 { 150 } 151 152 void rds_loop_exit(void) 153 { 154 struct rds_loop_connection *lc, *_lc; 155 LIST_HEAD(tmp_list); 156 157 /* avoid calling conn_destroy with irqs off */ 158 spin_lock_irq(&loop_conns_lock); 159 list_splice(&loop_conns, &tmp_list); 160 INIT_LIST_HEAD(&loop_conns); 161 spin_unlock_irq(&loop_conns_lock); 162 163 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) { 164 WARN_ON(lc->conn->c_passive); 165 rds_conn_destroy(lc->conn); 166 } 167 } 168 169 /* 170 * This is missing .xmit_* because loop doesn't go through generic 171 * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and 172 * .laddr_check are missing because transport.c doesn't iterate over 173 * rds_loop_transport. 174 */ 175 struct rds_transport rds_loop_transport = { 176 .xmit = rds_loop_xmit, 177 .recv = rds_loop_recv, 178 .conn_alloc = rds_loop_conn_alloc, 179 .conn_free = rds_loop_conn_free, 180 .conn_connect = rds_loop_conn_connect, 181 .conn_shutdown = rds_loop_conn_shutdown, 182 .inc_copy_to_user = rds_message_inc_copy_to_user, 183 .inc_free = rds_loop_inc_free, 184 .t_name = "loopback", 185 }; 186