spi: bcm-qspi: Fix use after free in bcm_qspi_probe() in error path
[sfrench/cifs-2.6.git] / net / rds / threads.c
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/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  */
71 struct workqueue_struct *rds_wq;
72 EXPORT_SYMBOL_GPL(rds_wq);
73
74 void 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 %pI4 to %pI4 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         queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
91         queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
92 }
93 EXPORT_SYMBOL_GPL(rds_connect_path_complete);
94
95 void rds_connect_complete(struct rds_connection *conn)
96 {
97         rds_connect_path_complete(&conn->c_path[0], RDS_CONN_CONNECTING);
98 }
99 EXPORT_SYMBOL_GPL(rds_connect_complete);
100
101 /*
102  * This random exponential backoff is relied on to eventually resolve racing
103  * connects.
104  *
105  * If connect attempts race then both parties drop both connections and come
106  * here to wait for a random amount of time before trying again.  Eventually
107  * the backoff range will be so much greater than the time it takes to
108  * establish a connection that one of the pair will establish the connection
109  * before the other's random delay fires.
110  *
111  * Connection attempts that arrive while a connection is already established
112  * are also considered to be racing connects.  This lets a connection from
113  * a rebooted machine replace an existing stale connection before the transport
114  * notices that the connection has failed.
115  *
116  * We should *always* start with a random backoff; otherwise a broken connection
117  * will always take several iterations to be re-established.
118  */
119 void rds_queue_reconnect(struct rds_conn_path *cp)
120 {
121         unsigned long rand;
122         struct rds_connection *conn = cp->cp_conn;
123
124         rdsdebug("conn %p for %pI4 to %pI4 reconnect jiffies %lu\n",
125           conn, &conn->c_laddr, &conn->c_faddr,
126           cp->cp_reconnect_jiffies);
127
128         /* let peer with smaller addr initiate reconnect, to avoid duels */
129         if (conn->c_trans->t_type == RDS_TRANS_TCP &&
130             !IS_CANONICAL(conn->c_laddr, conn->c_faddr))
131                 return;
132
133         set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
134         if (cp->cp_reconnect_jiffies == 0) {
135                 cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
136                 queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
137                 return;
138         }
139
140         get_random_bytes(&rand, sizeof(rand));
141         rdsdebug("%lu delay %lu ceil conn %p for %pI4 -> %pI4\n",
142                  rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies,
143                  conn, &conn->c_laddr, &conn->c_faddr);
144         queue_delayed_work(rds_wq, &cp->cp_conn_w,
145                            rand % cp->cp_reconnect_jiffies);
146
147         cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2,
148                                         rds_sysctl_reconnect_max_jiffies);
149 }
150
151 void rds_connect_worker(struct work_struct *work)
152 {
153         struct rds_conn_path *cp = container_of(work,
154                                                 struct rds_conn_path,
155                                                 cp_conn_w.work);
156         struct rds_connection *conn = cp->cp_conn;
157         int ret;
158
159         if (cp->cp_index > 0 &&
160             !IS_CANONICAL(cp->cp_conn->c_laddr, cp->cp_conn->c_faddr))
161                 return;
162         clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
163         ret = rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
164         if (ret) {
165                 ret = conn->c_trans->conn_path_connect(cp);
166                 rdsdebug("conn %p for %pI4 to %pI4 dispatched, ret %d\n",
167                         conn, &conn->c_laddr, &conn->c_faddr, ret);
168
169                 if (ret) {
170                         if (rds_conn_path_transition(cp,
171                                                      RDS_CONN_CONNECTING,
172                                                      RDS_CONN_DOWN))
173                                 rds_queue_reconnect(cp);
174                         else
175                                 rds_conn_path_error(cp, "connect failed\n");
176                 }
177         }
178 }
179
180 void rds_send_worker(struct work_struct *work)
181 {
182         struct rds_conn_path *cp = container_of(work,
183                                                 struct rds_conn_path,
184                                                 cp_send_w.work);
185         int ret;
186
187         if (rds_conn_path_state(cp) == RDS_CONN_UP) {
188                 clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags);
189                 ret = rds_send_xmit(cp);
190                 cond_resched();
191                 rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
192                 switch (ret) {
193                 case -EAGAIN:
194                         rds_stats_inc(s_send_immediate_retry);
195                         queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
196                         break;
197                 case -ENOMEM:
198                         rds_stats_inc(s_send_delayed_retry);
199                         queue_delayed_work(rds_wq, &cp->cp_send_w, 2);
200                 default:
201                         break;
202                 }
203         }
204 }
205
206 void rds_recv_worker(struct work_struct *work)
207 {
208         struct rds_conn_path *cp = container_of(work,
209                                                 struct rds_conn_path,
210                                                 cp_recv_w.work);
211         int ret;
212
213         if (rds_conn_path_state(cp) == RDS_CONN_UP) {
214                 ret = cp->cp_conn->c_trans->recv_path(cp);
215                 rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
216                 switch (ret) {
217                 case -EAGAIN:
218                         rds_stats_inc(s_recv_immediate_retry);
219                         queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
220                         break;
221                 case -ENOMEM:
222                         rds_stats_inc(s_recv_delayed_retry);
223                         queue_delayed_work(rds_wq, &cp->cp_recv_w, 2);
224                 default:
225                         break;
226                 }
227         }
228 }
229
230 void rds_shutdown_worker(struct work_struct *work)
231 {
232         struct rds_conn_path *cp = container_of(work,
233                                                 struct rds_conn_path,
234                                                 cp_down_w);
235
236         rds_conn_shutdown(cp);
237 }
238
239 void rds_threads_exit(void)
240 {
241         destroy_workqueue(rds_wq);
242 }
243
244 int rds_threads_init(void)
245 {
246         rds_wq = create_singlethread_workqueue("krdsd");
247         if (!rds_wq)
248                 return -ENOMEM;
249
250         return 0;
251 }