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_single_path.h" 38 #include "rds.h" 39 #include "loop.h" 40 41 static DEFINE_SPINLOCK(loop_conns_lock); 42 static LIST_HEAD(loop_conns); 43 44 /* 45 * This 'loopback' transport is a special case for flows that originate 46 * and terminate on the same machine. 47 * 48 * Connection build-up notices if the destination address is thought of 49 * as a local address by a transport. At that time it decides to use the 50 * loopback transport instead of the bound transport of the sending socket. 51 * 52 * The loopback transport's sending path just hands the sent rds_message 53 * straight to the receiving path via an embedded rds_incoming. 54 */ 55 56 /* 57 * Usually a message transits both the sender and receiver's conns as it 58 * flows to the receiver. In the loopback case, though, the receive path 59 * is handed the sending conn so the sense of the addresses is reversed. 60 */ 61 static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm, 62 unsigned int hdr_off, unsigned int sg, 63 unsigned int off) 64 { 65 struct scatterlist *sgp = &rm->data.op_sg[sg]; 66 int ret = sizeof(struct rds_header) + 67 be32_to_cpu(rm->m_inc.i_hdr.h_len); 68 69 /* Do not send cong updates to loopback */ 70 if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) { 71 rds_cong_map_updated(conn->c_fcong, ~(u64) 0); 72 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off); 73 goto out; 74 } 75 76 BUG_ON(hdr_off || sg || off); 77 78 rds_inc_init(&rm->m_inc, conn, conn->c_laddr); 79 /* For the embedded inc. Matching put is in loop_inc_free() */ 80 rds_message_addref(rm); 81 82 rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc, 83 GFP_KERNEL); 84 85 rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence), 86 NULL); 87 88 rds_inc_put(&rm->m_inc); 89 out: 90 return ret; 91 } 92 93 /* 94 * See rds_loop_xmit(). Since our inc is embedded in the rm, we 95 * make sure the rm lives at least until the inc is done. 96 */ 97 static void rds_loop_inc_free(struct rds_incoming *inc) 98 { 99 struct rds_message *rm = container_of(inc, struct rds_message, m_inc); 100 rds_message_put(rm); 101 } 102 103 /* we need to at least give the thread something to succeed */ 104 static int rds_loop_recv(struct rds_connection *conn) 105 { 106 return 0; 107 } 108 109 struct rds_loop_connection { 110 struct list_head loop_node; 111 struct rds_connection *conn; 112 }; 113 114 /* 115 * Even the loopback transport needs to keep track of its connections, 116 * so it can call rds_conn_destroy() on them on exit. N.B. there are 117 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have 118 * multiple loopback conns allocated, although rather useless. 119 */ 120 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp) 121 { 122 struct rds_loop_connection *lc; 123 unsigned long flags; 124 125 lc = kzalloc(sizeof(struct rds_loop_connection), gfp); 126 if (!lc) 127 return -ENOMEM; 128 129 INIT_LIST_HEAD(&lc->loop_node); 130 lc->conn = conn; 131 conn->c_transport_data = lc; 132 133 spin_lock_irqsave(&loop_conns_lock, flags); 134 list_add_tail(&lc->loop_node, &loop_conns); 135 spin_unlock_irqrestore(&loop_conns_lock, flags); 136 137 return 0; 138 } 139 140 static void rds_loop_conn_free(void *arg) 141 { 142 struct rds_loop_connection *lc = arg; 143 unsigned long flags; 144 145 rdsdebug("lc %p\n", lc); 146 spin_lock_irqsave(&loop_conns_lock, flags); 147 list_del(&lc->loop_node); 148 spin_unlock_irqrestore(&loop_conns_lock, flags); 149 kfree(lc); 150 } 151 152 static int rds_loop_conn_connect(struct rds_connection *conn) 153 { 154 rds_connect_complete(conn); 155 return 0; 156 } 157 158 static void rds_loop_conn_shutdown(struct rds_connection *conn) 159 { 160 } 161 162 void rds_loop_exit(void) 163 { 164 struct rds_loop_connection *lc, *_lc; 165 LIST_HEAD(tmp_list); 166 167 /* avoid calling conn_destroy with irqs off */ 168 spin_lock_irq(&loop_conns_lock); 169 list_splice(&loop_conns, &tmp_list); 170 INIT_LIST_HEAD(&loop_conns); 171 spin_unlock_irq(&loop_conns_lock); 172 173 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) { 174 WARN_ON(lc->conn->c_passive); 175 rds_conn_destroy(lc->conn); 176 } 177 } 178 179 /* 180 * This is missing .xmit_* because loop doesn't go through generic 181 * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and 182 * .laddr_check are missing because transport.c doesn't iterate over 183 * rds_loop_transport. 184 */ 185 struct rds_transport rds_loop_transport = { 186 .xmit = rds_loop_xmit, 187 .recv = rds_loop_recv, 188 .conn_alloc = rds_loop_conn_alloc, 189 .conn_free = rds_loop_conn_free, 190 .conn_connect = rds_loop_conn_connect, 191 .conn_shutdown = rds_loop_conn_shutdown, 192 .inc_copy_to_user = rds_message_inc_copy_to_user, 193 .inc_free = rds_loop_inc_free, 194 .t_name = "loopback", 195 }; 196