1/* 2 * Copyright (c) 2006, 2018 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/random.h> 35#include <linux/export.h> 36 37#include "rds.h" 38 39/* 40 * All of connection management is simplified by serializing it through 41 * work queues that execute in a connection managing thread. 42 * 43 * TCP wants to send acks through sendpage() in response to data_ready(), 44 * but it needs a process context to do so. 45 * 46 * The receive paths need to allocate but can't drop packets (!) so we have 47 * a thread around to block allocating if the receive fast path sees an 48 * allocation failure. 49 */ 50 51/* Grand Unified Theory of connection life cycle: 52 * At any point in time, the connection can be in one of these states: 53 * DOWN, CONNECTING, UP, DISCONNECTING, ERROR 54 * 55 * The following transitions are possible: 56 * ANY -> ERROR 57 * UP -> DISCONNECTING 58 * ERROR -> DISCONNECTING 59 * DISCONNECTING -> DOWN 60 * DOWN -> CONNECTING 61 * CONNECTING -> UP 62 * 63 * Transition to state DISCONNECTING/DOWN: 64 * - Inside the shutdown worker; synchronizes with xmit path 65 * through RDS_IN_XMIT, and with connection management callbacks 66 * via c_cm_lock. 67 * 68 * For receive callbacks, we rely on the underlying transport 69 * (TCP, IB/RDMA) to provide the necessary synchronisation. 70 */ 71struct workqueue_struct *rds_wq; 72EXPORT_SYMBOL_GPL(rds_wq); 73 74void rds_connect_path_complete(struct rds_conn_path *cp, int curr) 75{ 76 if (!rds_conn_path_transition(cp, curr, RDS_CONN_UP)) { 77 printk(KERN_WARNING "%s: Cannot transition to state UP, " 78 "current state is %d\n", 79 __func__, 80 atomic_read(&cp->cp_state)); 81 rds_conn_path_drop(cp, false); 82 return; 83 } 84 85 rdsdebug("conn %p for %pI6c to %pI6c complete\n", 86 cp->cp_conn, &cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr); 87 88 cp->cp_reconnect_jiffies = 0; 89 set_bit(0, &cp->cp_conn->c_map_queued); 90 rcu_read_lock(); 91 if (!rds_destroy_pending(cp->cp_conn)) { 92 queue_delayed_work(rds_wq, &cp->cp_send_w, 0); 93 queue_delayed_work(rds_wq, &cp->cp_recv_w, 0); 94 } 95 rcu_read_unlock(); 96 cp->cp_conn->c_proposed_version = RDS_PROTOCOL_VERSION; 97} 98EXPORT_SYMBOL_GPL(rds_connect_path_complete); 99 100void rds_connect_complete(struct rds_connection *conn) 101{ 102 rds_connect_path_complete(&conn->c_path[0], RDS_CONN_CONNECTING); 103} 104EXPORT_SYMBOL_GPL(rds_connect_complete); 105 106/* 107 * This random exponential backoff is relied on to eventually resolve racing 108 * connects. 109 * 110 * If connect attempts race then both parties drop both connections and come 111 * here to wait for a random amount of time before trying again. Eventually 112 * the backoff range will be so much greater than the time it takes to 113 * establish a connection that one of the pair will establish the connection 114 * before the other's random delay fires. 115 * 116 * Connection attempts that arrive while a connection is already established 117 * are also considered to be racing connects. This lets a connection from 118 * a rebooted machine replace an existing stale connection before the transport 119 * notices that the connection has failed. 120 * 121 * We should *always* start with a random backoff; otherwise a broken connection 122 * will always take several iterations to be re-established. 123 */ 124void rds_queue_reconnect(struct rds_conn_path *cp) 125{ 126 unsigned long rand; 127 struct rds_connection *conn = cp->cp_conn; 128 129 rdsdebug("conn %p for %pI6c to %pI6c reconnect jiffies %lu\n", 130 conn, &conn->c_laddr, &conn->c_faddr, 131 cp->cp_reconnect_jiffies); 132 133 /* let peer with smaller addr initiate reconnect, to avoid duels */ 134 if (conn->c_trans->t_type == RDS_TRANS_TCP && 135 rds_addr_cmp(&conn->c_laddr, &conn->c_faddr) >= 0) 136 return; 137 138 set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags); 139 if (cp->cp_reconnect_jiffies == 0) { 140 cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies; 141 rcu_read_lock(); 142 if (!rds_destroy_pending(cp->cp_conn)) 143 queue_delayed_work(rds_wq, &cp->cp_conn_w, 0); 144 rcu_read_unlock(); 145 return; 146 } 147 148 get_random_bytes(&rand, sizeof(rand)); 149 rdsdebug("%lu delay %lu ceil conn %p for %pI6c -> %pI6c\n", 150 rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies, 151 conn, &conn->c_laddr, &conn->c_faddr); 152 rcu_read_lock(); 153 if (!rds_destroy_pending(cp->cp_conn)) 154 queue_delayed_work(rds_wq, &cp->cp_conn_w, 155 rand % cp->cp_reconnect_jiffies); 156 rcu_read_unlock(); 157 158 cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2, 159 rds_sysctl_reconnect_max_jiffies); 160} 161 162void rds_connect_worker(struct work_struct *work) 163{ 164 struct rds_conn_path *cp = container_of(work, 165 struct rds_conn_path, 166 cp_conn_w.work); 167 struct rds_connection *conn = cp->cp_conn; 168 int ret; 169 170 if (cp->cp_index > 0 && 171 rds_addr_cmp(&cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr) >= 0) 172 return; 173 clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags); 174 ret = rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_CONNECTING); 175 if (ret) { 176 ret = conn->c_trans->conn_path_connect(cp); 177 rdsdebug("conn %p for %pI6c to %pI6c dispatched, ret %d\n", 178 conn, &conn->c_laddr, &conn->c_faddr, ret); 179 180 if (ret) { 181 if (rds_conn_path_transition(cp, 182 RDS_CONN_CONNECTING, 183 RDS_CONN_DOWN)) 184 rds_queue_reconnect(cp); 185 else 186 rds_conn_path_error(cp, "connect failed\n"); 187 } 188 } 189} 190 191void rds_send_worker(struct work_struct *work) 192{ 193 struct rds_conn_path *cp = container_of(work, 194 struct rds_conn_path, 195 cp_send_w.work); 196 int ret; 197 198 if (rds_conn_path_state(cp) == RDS_CONN_UP) { 199 clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags); 200 ret = rds_send_xmit(cp); 201 cond_resched(); 202 rdsdebug("conn %p ret %d\n", cp->cp_conn, ret); 203 switch (ret) { 204 case -EAGAIN: 205 rds_stats_inc(s_send_immediate_retry); 206 queue_delayed_work(rds_wq, &cp->cp_send_w, 0); 207 break; 208 case -ENOMEM: 209 rds_stats_inc(s_send_delayed_retry); 210 queue_delayed_work(rds_wq, &cp->cp_send_w, 2); 211 break; 212 default: 213 break; 214 } 215 } 216} 217 218void rds_recv_worker(struct work_struct *work) 219{ 220 struct rds_conn_path *cp = container_of(work, 221 struct rds_conn_path, 222 cp_recv_w.work); 223 int ret; 224 225 if (rds_conn_path_state(cp) == RDS_CONN_UP) { 226 ret = cp->cp_conn->c_trans->recv_path(cp); 227 rdsdebug("conn %p ret %d\n", cp->cp_conn, ret); 228 switch (ret) { 229 case -EAGAIN: 230 rds_stats_inc(s_recv_immediate_retry); 231 queue_delayed_work(rds_wq, &cp->cp_recv_w, 0); 232 break; 233 case -ENOMEM: 234 rds_stats_inc(s_recv_delayed_retry); 235 queue_delayed_work(rds_wq, &cp->cp_recv_w, 2); 236 break; 237 default: 238 break; 239 } 240 } 241} 242 243void rds_shutdown_worker(struct work_struct *work) 244{ 245 struct rds_conn_path *cp = container_of(work, 246 struct rds_conn_path, 247 cp_down_w); 248 249 rds_conn_shutdown(cp); 250} 251 252void rds_threads_exit(void) 253{ 254 destroy_workqueue(rds_wq); 255} 256 257int rds_threads_init(void) 258{ 259 rds_wq = create_singlethread_workqueue("krdsd"); 260 if (!rds_wq) 261 return -ENOMEM; 262 263 return 0; 264} 265 266/* Compare two IPv6 addresses. Return 0 if the two addresses are equal. 267 * Return 1 if the first is greater. Return -1 if the second is greater. 268 */ 269int rds_addr_cmp(const struct in6_addr *addr1, 270 const struct in6_addr *addr2) 271{ 272#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 273 const __be64 *a1, *a2; 274 u64 x, y; 275 276 a1 = (__be64 *)addr1; 277 a2 = (__be64 *)addr2; 278 279 if (*a1 != *a2) { 280 if (be64_to_cpu(*a1) < be64_to_cpu(*a2)) 281 return -1; 282 else 283 return 1; 284 } else { 285 x = be64_to_cpu(*++a1); 286 y = be64_to_cpu(*++a2); 287 if (x < y) 288 return -1; 289 else if (x > y) 290 return 1; 291 else 292 return 0; 293 } 294#else 295 u32 a, b; 296 int i; 297 298 for (i = 0; i < 4; i++) { 299 if (addr1->s6_addr32[i] != addr2->s6_addr32[i]) { 300 a = ntohl(addr1->s6_addr32[i]); 301 b = ntohl(addr2->s6_addr32[i]); 302 if (a < b) 303 return -1; 304 else if (a > b) 305 return 1; 306 } 307 } 308 return 0; 309#endif 310} 311EXPORT_SYMBOL_GPL(rds_addr_cmp); 312