100e0f34cSAndy Grover /*
2eee2fa6aSKa-Cheong Poon * Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved.
300e0f34cSAndy Grover *
400e0f34cSAndy Grover * This software is available to you under a choice of one of two
500e0f34cSAndy Grover * licenses. You may choose to be licensed under the terms of the GNU
600e0f34cSAndy Grover * General Public License (GPL) Version 2, available from the file
700e0f34cSAndy Grover * COPYING in the main directory of this source tree, or the
800e0f34cSAndy Grover * OpenIB.org BSD license below:
900e0f34cSAndy Grover *
1000e0f34cSAndy Grover * Redistribution and use in source and binary forms, with or
1100e0f34cSAndy Grover * without modification, are permitted provided that the following
1200e0f34cSAndy Grover * conditions are met:
1300e0f34cSAndy Grover *
1400e0f34cSAndy Grover * - Redistributions of source code must retain the above
1500e0f34cSAndy Grover * copyright notice, this list of conditions and the following
1600e0f34cSAndy Grover * disclaimer.
1700e0f34cSAndy Grover *
1800e0f34cSAndy Grover * - Redistributions in binary form must reproduce the above
1900e0f34cSAndy Grover * copyright notice, this list of conditions and the following
2000e0f34cSAndy Grover * disclaimer in the documentation and/or other materials
2100e0f34cSAndy Grover * provided with the distribution.
2200e0f34cSAndy Grover *
2300e0f34cSAndy Grover * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
2400e0f34cSAndy Grover * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
2500e0f34cSAndy Grover * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
2600e0f34cSAndy Grover * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
2700e0f34cSAndy Grover * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
2800e0f34cSAndy Grover * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
2900e0f34cSAndy Grover * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
3000e0f34cSAndy Grover * SOFTWARE.
3100e0f34cSAndy Grover *
3200e0f34cSAndy Grover */
3300e0f34cSAndy Grover #include <linux/kernel.h>
3400e0f34cSAndy Grover #include <linux/random.h>
35bc3b2d7fSPaul Gortmaker #include <linux/export.h>
3600e0f34cSAndy Grover
3700e0f34cSAndy Grover #include "rds.h"
3800e0f34cSAndy Grover
3900e0f34cSAndy Grover /*
4000e0f34cSAndy Grover * All of connection management is simplified by serializing it through
4100e0f34cSAndy Grover * work queues that execute in a connection managing thread.
4200e0f34cSAndy Grover *
4300e0f34cSAndy Grover * TCP wants to send acks through sendpage() in response to data_ready(),
4400e0f34cSAndy Grover * but it needs a process context to do so.
4500e0f34cSAndy Grover *
4600e0f34cSAndy Grover * The receive paths need to allocate but can't drop packets (!) so we have
4700e0f34cSAndy Grover * a thread around to block allocating if the receive fast path sees an
4800e0f34cSAndy Grover * allocation failure.
4900e0f34cSAndy Grover */
5000e0f34cSAndy Grover
5100e0f34cSAndy Grover /* Grand Unified Theory of connection life cycle:
5200e0f34cSAndy Grover * At any point in time, the connection can be in one of these states:
5300e0f34cSAndy Grover * DOWN, CONNECTING, UP, DISCONNECTING, ERROR
5400e0f34cSAndy Grover *
5500e0f34cSAndy Grover * The following transitions are possible:
5600e0f34cSAndy Grover * ANY -> ERROR
5700e0f34cSAndy Grover * UP -> DISCONNECTING
5800e0f34cSAndy Grover * ERROR -> DISCONNECTING
5900e0f34cSAndy Grover * DISCONNECTING -> DOWN
6000e0f34cSAndy Grover * DOWN -> CONNECTING
6100e0f34cSAndy Grover * CONNECTING -> UP
6200e0f34cSAndy Grover *
6300e0f34cSAndy Grover * Transition to state DISCONNECTING/DOWN:
6400e0f34cSAndy Grover * - Inside the shutdown worker; synchronizes with xmit path
650f4b1c7eSZach Brown * through RDS_IN_XMIT, and with connection management callbacks
6600e0f34cSAndy Grover * via c_cm_lock.
6700e0f34cSAndy Grover *
6800e0f34cSAndy Grover * For receive callbacks, we rely on the underlying transport
6900e0f34cSAndy Grover * (TCP, IB/RDMA) to provide the necessary synchronisation.
7000e0f34cSAndy Grover */
7100e0f34cSAndy Grover struct workqueue_struct *rds_wq;
72616b757aSAndy Grover EXPORT_SYMBOL_GPL(rds_wq);
7300e0f34cSAndy Grover
rds_connect_path_complete(struct rds_conn_path * cp,int curr)740cb43965SSowmini Varadhan void rds_connect_path_complete(struct rds_conn_path *cp, int curr)
7500e0f34cSAndy Grover {
760cb43965SSowmini Varadhan if (!rds_conn_path_transition(cp, curr, RDS_CONN_UP)) {
7700e0f34cSAndy Grover printk(KERN_WARNING "%s: Cannot transition to state UP, "
7800e0f34cSAndy Grover "current state is %d\n",
7900e0f34cSAndy Grover __func__,
800cb43965SSowmini Varadhan atomic_read(&cp->cp_state));
81aed20a53SSowmini Varadhan rds_conn_path_drop(cp, false);
8200e0f34cSAndy Grover return;
8300e0f34cSAndy Grover }
8400e0f34cSAndy Grover
85eee2fa6aSKa-Cheong Poon rdsdebug("conn %p for %pI6c to %pI6c complete\n",
860cb43965SSowmini Varadhan cp->cp_conn, &cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr);
8700e0f34cSAndy Grover
880cb43965SSowmini Varadhan cp->cp_reconnect_jiffies = 0;
890cb43965SSowmini Varadhan set_bit(0, &cp->cp_conn->c_map_queued);
903db6e0d1SSowmini Varadhan rcu_read_lock();
91ebeeb1adSSowmini Varadhan if (!rds_destroy_pending(cp->cp_conn)) {
920cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
930cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
9400e0f34cSAndy Grover }
953db6e0d1SSowmini Varadhan rcu_read_unlock();
96cdc306a5SSantosh Shilimkar cp->cp_conn->c_proposed_version = RDS_PROTOCOL_VERSION;
973db6e0d1SSowmini Varadhan }
989c79440eSSowmini Varadhan EXPORT_SYMBOL_GPL(rds_connect_path_complete);
999c79440eSSowmini Varadhan
rds_connect_complete(struct rds_connection * conn)1009c79440eSSowmini Varadhan void rds_connect_complete(struct rds_connection *conn)
1019c79440eSSowmini Varadhan {
1020cb43965SSowmini Varadhan rds_connect_path_complete(&conn->c_path[0], RDS_CONN_CONNECTING);
1039c79440eSSowmini Varadhan }
104616b757aSAndy Grover EXPORT_SYMBOL_GPL(rds_connect_complete);
10500e0f34cSAndy Grover
10600e0f34cSAndy Grover /*
10700e0f34cSAndy Grover * This random exponential backoff is relied on to eventually resolve racing
10800e0f34cSAndy Grover * connects.
10900e0f34cSAndy Grover *
11000e0f34cSAndy Grover * If connect attempts race then both parties drop both connections and come
11100e0f34cSAndy Grover * here to wait for a random amount of time before trying again. Eventually
11200e0f34cSAndy Grover * the backoff range will be so much greater than the time it takes to
11300e0f34cSAndy Grover * establish a connection that one of the pair will establish the connection
11400e0f34cSAndy Grover * before the other's random delay fires.
11500e0f34cSAndy Grover *
11600e0f34cSAndy Grover * Connection attempts that arrive while a connection is already established
11700e0f34cSAndy Grover * are also considered to be racing connects. This lets a connection from
11800e0f34cSAndy Grover * a rebooted machine replace an existing stale connection before the transport
11900e0f34cSAndy Grover * notices that the connection has failed.
12000e0f34cSAndy Grover *
12100e0f34cSAndy Grover * We should *always* start with a random backoff; otherwise a broken connection
12200e0f34cSAndy Grover * will always take several iterations to be re-established.
12300e0f34cSAndy Grover */
rds_queue_reconnect(struct rds_conn_path * cp)1240cb43965SSowmini Varadhan void rds_queue_reconnect(struct rds_conn_path *cp)
12500e0f34cSAndy Grover {
12600e0f34cSAndy Grover unsigned long rand;
1270cb43965SSowmini Varadhan struct rds_connection *conn = cp->cp_conn;
12800e0f34cSAndy Grover
129eee2fa6aSKa-Cheong Poon rdsdebug("conn %p for %pI6c to %pI6c reconnect jiffies %lu\n",
13000e0f34cSAndy Grover conn, &conn->c_laddr, &conn->c_faddr,
1310cb43965SSowmini Varadhan cp->cp_reconnect_jiffies);
13200e0f34cSAndy Grover
1338315011aSSowmini Varadhan /* let peer with smaller addr initiate reconnect, to avoid duels */
1348315011aSSowmini Varadhan if (conn->c_trans->t_type == RDS_TRANS_TCP &&
135eee2fa6aSKa-Cheong Poon rds_addr_cmp(&conn->c_laddr, &conn->c_faddr) >= 0)
1368315011aSSowmini Varadhan return;
1378315011aSSowmini Varadhan
1380cb43965SSowmini Varadhan set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
1390cb43965SSowmini Varadhan if (cp->cp_reconnect_jiffies == 0) {
1400cb43965SSowmini Varadhan cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
1413db6e0d1SSowmini Varadhan rcu_read_lock();
142ebeeb1adSSowmini Varadhan if (!rds_destroy_pending(cp->cp_conn))
1430cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
1443db6e0d1SSowmini Varadhan rcu_read_unlock();
14500e0f34cSAndy Grover return;
14600e0f34cSAndy Grover }
14700e0f34cSAndy Grover
14800e0f34cSAndy Grover get_random_bytes(&rand, sizeof(rand));
149eee2fa6aSKa-Cheong Poon rdsdebug("%lu delay %lu ceil conn %p for %pI6c -> %pI6c\n",
1500cb43965SSowmini Varadhan rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies,
15100e0f34cSAndy Grover conn, &conn->c_laddr, &conn->c_faddr);
1523db6e0d1SSowmini Varadhan rcu_read_lock();
153ebeeb1adSSowmini Varadhan if (!rds_destroy_pending(cp->cp_conn))
1540cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_conn_w,
1550cb43965SSowmini Varadhan rand % cp->cp_reconnect_jiffies);
1563db6e0d1SSowmini Varadhan rcu_read_unlock();
15700e0f34cSAndy Grover
1580cb43965SSowmini Varadhan cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2,
15900e0f34cSAndy Grover rds_sysctl_reconnect_max_jiffies);
16000e0f34cSAndy Grover }
16100e0f34cSAndy Grover
rds_connect_worker(struct work_struct * work)16200e0f34cSAndy Grover void rds_connect_worker(struct work_struct *work)
16300e0f34cSAndy Grover {
1640cb43965SSowmini Varadhan struct rds_conn_path *cp = container_of(work,
1650cb43965SSowmini Varadhan struct rds_conn_path,
1660cb43965SSowmini Varadhan cp_conn_w.work);
1670cb43965SSowmini Varadhan struct rds_connection *conn = cp->cp_conn;
16800e0f34cSAndy Grover int ret;
16900e0f34cSAndy Grover
17000354de5SSowmini Varadhan if (cp->cp_index > 0 &&
171eee2fa6aSKa-Cheong Poon rds_addr_cmp(&cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr) >= 0)
1725916e2c1SSowmini Varadhan return;
1730cb43965SSowmini Varadhan clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
174b04e8554SSowmini Varadhan ret = rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
175b04e8554SSowmini Varadhan if (ret) {
176b04e8554SSowmini Varadhan ret = conn->c_trans->conn_path_connect(cp);
177eee2fa6aSKa-Cheong Poon rdsdebug("conn %p for %pI6c to %pI6c dispatched, ret %d\n",
17800e0f34cSAndy Grover conn, &conn->c_laddr, &conn->c_faddr, ret);
17900e0f34cSAndy Grover
18000e0f34cSAndy Grover if (ret) {
1810cb43965SSowmini Varadhan if (rds_conn_path_transition(cp,
1820cb43965SSowmini Varadhan RDS_CONN_CONNECTING,
1830cb43965SSowmini Varadhan RDS_CONN_DOWN))
1840cb43965SSowmini Varadhan rds_queue_reconnect(cp);
18500e0f34cSAndy Grover else
1869c7cbcf5SJoe Perches rds_conn_path_error(cp, "connect failed\n");
18700e0f34cSAndy Grover }
18800e0f34cSAndy Grover }
18900e0f34cSAndy Grover }
19000e0f34cSAndy Grover
rds_send_worker(struct work_struct * work)19100e0f34cSAndy Grover void rds_send_worker(struct work_struct *work)
19200e0f34cSAndy Grover {
1930cb43965SSowmini Varadhan struct rds_conn_path *cp = container_of(work,
1940cb43965SSowmini Varadhan struct rds_conn_path,
1950cb43965SSowmini Varadhan cp_send_w.work);
19600e0f34cSAndy Grover int ret;
19700e0f34cSAndy Grover
1980cb43965SSowmini Varadhan if (rds_conn_path_state(cp) == RDS_CONN_UP) {
1990cb43965SSowmini Varadhan clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags);
2001f9ecd7eSSowmini Varadhan ret = rds_send_xmit(cp);
201db6526dcSSantosh Shilimkar cond_resched();
2020cb43965SSowmini Varadhan rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
20300e0f34cSAndy Grover switch (ret) {
20400e0f34cSAndy Grover case -EAGAIN:
20500e0f34cSAndy Grover rds_stats_inc(s_send_immediate_retry);
2060cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
20700e0f34cSAndy Grover break;
20800e0f34cSAndy Grover case -ENOMEM:
20900e0f34cSAndy Grover rds_stats_inc(s_send_delayed_retry);
2100cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_send_w, 2);
211*3754fa74SGustavo A. R. Silva break;
21200e0f34cSAndy Grover default:
21300e0f34cSAndy Grover break;
21400e0f34cSAndy Grover }
21500e0f34cSAndy Grover }
21600e0f34cSAndy Grover }
21700e0f34cSAndy Grover
rds_recv_worker(struct work_struct * work)21800e0f34cSAndy Grover void rds_recv_worker(struct work_struct *work)
21900e0f34cSAndy Grover {
2200cb43965SSowmini Varadhan struct rds_conn_path *cp = container_of(work,
2210cb43965SSowmini Varadhan struct rds_conn_path,
2220cb43965SSowmini Varadhan cp_recv_w.work);
22300e0f34cSAndy Grover int ret;
22400e0f34cSAndy Grover
2250cb43965SSowmini Varadhan if (rds_conn_path_state(cp) == RDS_CONN_UP) {
2262da43c4aSSowmini Varadhan ret = cp->cp_conn->c_trans->recv_path(cp);
2270cb43965SSowmini Varadhan rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
22800e0f34cSAndy Grover switch (ret) {
22900e0f34cSAndy Grover case -EAGAIN:
23000e0f34cSAndy Grover rds_stats_inc(s_recv_immediate_retry);
2310cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
23200e0f34cSAndy Grover break;
23300e0f34cSAndy Grover case -ENOMEM:
23400e0f34cSAndy Grover rds_stats_inc(s_recv_delayed_retry);
2350cb43965SSowmini Varadhan queue_delayed_work(rds_wq, &cp->cp_recv_w, 2);
236*3754fa74SGustavo A. R. Silva break;
23700e0f34cSAndy Grover default:
23800e0f34cSAndy Grover break;
23900e0f34cSAndy Grover }
24000e0f34cSAndy Grover }
24100e0f34cSAndy Grover }
24200e0f34cSAndy Grover
rds_shutdown_worker(struct work_struct * work)2432dc39357SAndy Grover void rds_shutdown_worker(struct work_struct *work)
2442dc39357SAndy Grover {
2450cb43965SSowmini Varadhan struct rds_conn_path *cp = container_of(work,
2460cb43965SSowmini Varadhan struct rds_conn_path,
2470cb43965SSowmini Varadhan cp_down_w);
2482dc39357SAndy Grover
249d769ef81SSowmini Varadhan rds_conn_shutdown(cp);
2502dc39357SAndy Grover }
2512dc39357SAndy Grover
rds_threads_exit(void)25200e0f34cSAndy Grover void rds_threads_exit(void)
25300e0f34cSAndy Grover {
25400e0f34cSAndy Grover destroy_workqueue(rds_wq);
25500e0f34cSAndy Grover }
25600e0f34cSAndy Grover
rds_threads_init(void)257ef87b7eaSZach Brown int rds_threads_init(void)
25800e0f34cSAndy Grover {
25980c51be5SZach Brown rds_wq = create_singlethread_workqueue("krdsd");
2608690bfa1SAndy Grover if (!rds_wq)
26100e0f34cSAndy Grover return -ENOMEM;
26200e0f34cSAndy Grover
26300e0f34cSAndy Grover return 0;
26400e0f34cSAndy Grover }
265eee2fa6aSKa-Cheong Poon
266eee2fa6aSKa-Cheong Poon /* Compare two IPv6 addresses. Return 0 if the two addresses are equal.
267eee2fa6aSKa-Cheong Poon * Return 1 if the first is greater. Return -1 if the second is greater.
268eee2fa6aSKa-Cheong Poon */
rds_addr_cmp(const struct in6_addr * addr1,const struct in6_addr * addr2)269eee2fa6aSKa-Cheong Poon int rds_addr_cmp(const struct in6_addr *addr1,
270eee2fa6aSKa-Cheong Poon const struct in6_addr *addr2)
271eee2fa6aSKa-Cheong Poon {
272eee2fa6aSKa-Cheong Poon #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
273eee2fa6aSKa-Cheong Poon const __be64 *a1, *a2;
274eee2fa6aSKa-Cheong Poon u64 x, y;
275eee2fa6aSKa-Cheong Poon
276eee2fa6aSKa-Cheong Poon a1 = (__be64 *)addr1;
277eee2fa6aSKa-Cheong Poon a2 = (__be64 *)addr2;
278eee2fa6aSKa-Cheong Poon
279eee2fa6aSKa-Cheong Poon if (*a1 != *a2) {
280eee2fa6aSKa-Cheong Poon if (be64_to_cpu(*a1) < be64_to_cpu(*a2))
281eee2fa6aSKa-Cheong Poon return -1;
282eee2fa6aSKa-Cheong Poon else
283eee2fa6aSKa-Cheong Poon return 1;
284eee2fa6aSKa-Cheong Poon } else {
285eee2fa6aSKa-Cheong Poon x = be64_to_cpu(*++a1);
286eee2fa6aSKa-Cheong Poon y = be64_to_cpu(*++a2);
287eee2fa6aSKa-Cheong Poon if (x < y)
288eee2fa6aSKa-Cheong Poon return -1;
289eee2fa6aSKa-Cheong Poon else if (x > y)
290eee2fa6aSKa-Cheong Poon return 1;
291eee2fa6aSKa-Cheong Poon else
292eee2fa6aSKa-Cheong Poon return 0;
293eee2fa6aSKa-Cheong Poon }
294eee2fa6aSKa-Cheong Poon #else
295eee2fa6aSKa-Cheong Poon u32 a, b;
296eee2fa6aSKa-Cheong Poon int i;
297eee2fa6aSKa-Cheong Poon
298eee2fa6aSKa-Cheong Poon for (i = 0; i < 4; i++) {
299eee2fa6aSKa-Cheong Poon if (addr1->s6_addr32[i] != addr2->s6_addr32[i]) {
300eee2fa6aSKa-Cheong Poon a = ntohl(addr1->s6_addr32[i]);
301eee2fa6aSKa-Cheong Poon b = ntohl(addr2->s6_addr32[i]);
302eee2fa6aSKa-Cheong Poon if (a < b)
303eee2fa6aSKa-Cheong Poon return -1;
304eee2fa6aSKa-Cheong Poon else if (a > b)
305eee2fa6aSKa-Cheong Poon return 1;
306eee2fa6aSKa-Cheong Poon }
307eee2fa6aSKa-Cheong Poon }
308eee2fa6aSKa-Cheong Poon return 0;
309eee2fa6aSKa-Cheong Poon #endif
310eee2fa6aSKa-Cheong Poon }
311eee2fa6aSKa-Cheong Poon EXPORT_SYMBOL_GPL(rds_addr_cmp);
312