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v5.9
  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		default:
212			break;
213		}
214	}
215}
216
217void rds_recv_worker(struct work_struct *work)
218{
219	struct rds_conn_path *cp = container_of(work,
220						struct rds_conn_path,
221						cp_recv_w.work);
222	int ret;
223
224	if (rds_conn_path_state(cp) == RDS_CONN_UP) {
225		ret = cp->cp_conn->c_trans->recv_path(cp);
226		rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
227		switch (ret) {
228		case -EAGAIN:
229			rds_stats_inc(s_recv_immediate_retry);
230			queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
231			break;
232		case -ENOMEM:
233			rds_stats_inc(s_recv_delayed_retry);
234			queue_delayed_work(rds_wq, &cp->cp_recv_w, 2);
 
235		default:
236			break;
237		}
238	}
239}
240
241void rds_shutdown_worker(struct work_struct *work)
242{
243	struct rds_conn_path *cp = container_of(work,
244						struct rds_conn_path,
245						cp_down_w);
246
247	rds_conn_shutdown(cp);
248}
249
250void rds_threads_exit(void)
251{
252	destroy_workqueue(rds_wq);
253}
254
255int rds_threads_init(void)
256{
257	rds_wq = create_singlethread_workqueue("krdsd");
258	if (!rds_wq)
259		return -ENOMEM;
260
261	return 0;
262}
263
264/* Compare two IPv6 addresses.  Return 0 if the two addresses are equal.
265 * Return 1 if the first is greater.  Return -1 if the second is greater.
266 */
267int rds_addr_cmp(const struct in6_addr *addr1,
268		 const struct in6_addr *addr2)
269{
270#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
271	const __be64 *a1, *a2;
272	u64 x, y;
273
274	a1 = (__be64 *)addr1;
275	a2 = (__be64 *)addr2;
276
277	if (*a1 != *a2) {
278		if (be64_to_cpu(*a1) < be64_to_cpu(*a2))
279			return -1;
280		else
281			return 1;
282	} else {
283		x = be64_to_cpu(*++a1);
284		y = be64_to_cpu(*++a2);
285		if (x < y)
286			return -1;
287		else if (x > y)
288			return 1;
289		else
290			return 0;
291	}
292#else
293	u32 a, b;
294	int i;
295
296	for (i = 0; i < 4; i++) {
297		if (addr1->s6_addr32[i] != addr2->s6_addr32[i]) {
298			a = ntohl(addr1->s6_addr32[i]);
299			b = ntohl(addr2->s6_addr32[i]);
300			if (a < b)
301				return -1;
302			else if (a > b)
303				return 1;
304		}
305	}
306	return 0;
307#endif
308}
309EXPORT_SYMBOL_GPL(rds_addr_cmp);
v6.13.7
  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);