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 struct scatterlist *sgp = &rm->data.op_sg[sg]; 65 int ret = sizeof(struct rds_header) + 66 be32_to_cpu(rm->m_inc.i_hdr.h_len); 67 68 /* Do not send cong updates to loopback */ 69 if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) { 70 rds_cong_map_updated(conn->c_fcong, ~(u64) 0); 71 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off); 72 goto out; 73 } 74 75 BUG_ON(hdr_off || sg || off); 76 77 rds_inc_init(&rm->m_inc, conn, conn->c_laddr); 78 /* For the embedded inc. Matching put is in loop_inc_free() */ 79 rds_message_addref(rm); 80 81 rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc, 82 GFP_KERNEL); 83 84 rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence), 85 NULL); 86 87 rds_inc_put(&rm->m_inc); 88 out: 89 return ret; 90 } 91 92 /* 93 * See rds_loop_xmit(). Since our inc is embedded in the rm, we 94 * make sure the rm lives at least until the inc is done. 95 */ 96 static void rds_loop_inc_free(struct rds_incoming *inc) 97 { 98 struct rds_message *rm = container_of(inc, struct rds_message, m_inc); 99 rds_message_put(rm); 100 } 101 102 /* we need to at least give the thread something to succeed */ 103 static int rds_loop_recv(struct rds_connection *conn) 104 { 105 return 0; 106 } 107 108 struct rds_loop_connection { 109 struct list_head loop_node; 110 struct rds_connection *conn; 111 }; 112 113 /* 114 * Even the loopback transport needs to keep track of its connections, 115 * so it can call rds_conn_destroy() on them on exit. N.B. there are 116 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have 117 * multiple loopback conns allocated, although rather useless. 118 */ 119 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp) 120 { 121 struct rds_loop_connection *lc; 122 unsigned long flags; 123 124 lc = kzalloc(sizeof(struct rds_loop_connection), gfp); 125 if (!lc) 126 return -ENOMEM; 127 128 INIT_LIST_HEAD(&lc->loop_node); 129 lc->conn = conn; 130 conn->c_transport_data = lc; 131 132 spin_lock_irqsave(&loop_conns_lock, flags); 133 list_add_tail(&lc->loop_node, &loop_conns); 134 spin_unlock_irqrestore(&loop_conns_lock, flags); 135 136 return 0; 137 } 138 139 static void rds_loop_conn_free(void *arg) 140 { 141 struct rds_loop_connection *lc = arg; 142 unsigned long flags; 143 144 rdsdebug("lc %p\n", lc); 145 spin_lock_irqsave(&loop_conns_lock, flags); 146 list_del(&lc->loop_node); 147 spin_unlock_irqrestore(&loop_conns_lock, flags); 148 kfree(lc); 149 } 150 151 static int rds_loop_conn_connect(struct rds_connection *conn) 152 { 153 rds_connect_complete(conn); 154 return 0; 155 } 156 157 static void rds_loop_conn_shutdown(struct rds_connection *conn) 158 { 159 } 160 161 void rds_loop_exit(void) 162 { 163 struct rds_loop_connection *lc, *_lc; 164 LIST_HEAD(tmp_list); 165 166 /* avoid calling conn_destroy with irqs off */ 167 spin_lock_irq(&loop_conns_lock); 168 list_splice(&loop_conns, &tmp_list); 169 INIT_LIST_HEAD(&loop_conns); 170 spin_unlock_irq(&loop_conns_lock); 171 172 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) { 173 WARN_ON(lc->conn->c_passive); 174 rds_conn_destroy(lc->conn); 175 } 176 } 177 178 /* 179 * This is missing .xmit_* because loop doesn't go through generic 180 * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and 181 * .laddr_check are missing because transport.c doesn't iterate over 182 * rds_loop_transport. 183 */ 184 struct rds_transport rds_loop_transport = { 185 .xmit = rds_loop_xmit, 186 .recv = rds_loop_recv, 187 .conn_alloc = rds_loop_conn_alloc, 188 .conn_free = rds_loop_conn_free, 189 .conn_connect = rds_loop_conn_connect, 190 .conn_shutdown = rds_loop_conn_shutdown, 191 .inc_copy_to_user = rds_message_inc_copy_to_user, 192 .inc_free = rds_loop_inc_free, 193 .t_name = "loopback", 194 }; 195