1 /* RxRPC point-to-point transport session management
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/net.h>
14 #include <linux/skbuff.h>
15 #include <linux/slab.h>
16 #include <net/sock.h>
17 #include <net/af_rxrpc.h>
18 #include "ar-internal.h"
19
20 static void rxrpc_transport_reaper(struct work_struct *work);
21
22 static LIST_HEAD(rxrpc_transports);
23 static DEFINE_RWLOCK(rxrpc_transport_lock);
24 static unsigned long rxrpc_transport_timeout = 3600 * 24;
25 static DECLARE_DELAYED_WORK(rxrpc_transport_reap, rxrpc_transport_reaper);
26
27 /*
28 * allocate a new transport session manager
29 */
rxrpc_alloc_transport(struct rxrpc_local * local,struct rxrpc_peer * peer,gfp_t gfp)30 static struct rxrpc_transport *rxrpc_alloc_transport(struct rxrpc_local *local,
31 struct rxrpc_peer *peer,
32 gfp_t gfp)
33 {
34 struct rxrpc_transport *trans;
35
36 _enter("");
37
38 trans = kzalloc(sizeof(struct rxrpc_transport), gfp);
39 if (trans) {
40 trans->local = local;
41 trans->peer = peer;
42 INIT_LIST_HEAD(&trans->link);
43 trans->bundles = RB_ROOT;
44 trans->client_conns = RB_ROOT;
45 trans->server_conns = RB_ROOT;
46 skb_queue_head_init(&trans->error_queue);
47 spin_lock_init(&trans->client_lock);
48 rwlock_init(&trans->conn_lock);
49 atomic_set(&trans->usage, 1);
50 trans->debug_id = atomic_inc_return(&rxrpc_debug_id);
51
52 if (peer->srx.transport.family == AF_INET) {
53 switch (peer->srx.transport_type) {
54 case SOCK_DGRAM:
55 INIT_WORK(&trans->error_handler,
56 rxrpc_UDP_error_handler);
57 break;
58 default:
59 BUG();
60 break;
61 }
62 } else {
63 BUG();
64 }
65 }
66
67 _leave(" = %p", trans);
68 return trans;
69 }
70
71 /*
72 * obtain a transport session for the nominated endpoints
73 */
rxrpc_get_transport(struct rxrpc_local * local,struct rxrpc_peer * peer,gfp_t gfp)74 struct rxrpc_transport *rxrpc_get_transport(struct rxrpc_local *local,
75 struct rxrpc_peer *peer,
76 gfp_t gfp)
77 {
78 struct rxrpc_transport *trans, *candidate;
79 const char *new = "old";
80 int usage;
81
82 _enter("{%pI4+%hu},{%pI4+%hu},",
83 &local->srx.transport.sin.sin_addr,
84 ntohs(local->srx.transport.sin.sin_port),
85 &peer->srx.transport.sin.sin_addr,
86 ntohs(peer->srx.transport.sin.sin_port));
87
88 /* search the transport list first */
89 read_lock_bh(&rxrpc_transport_lock);
90 list_for_each_entry(trans, &rxrpc_transports, link) {
91 if (trans->local == local && trans->peer == peer)
92 goto found_extant_transport;
93 }
94 read_unlock_bh(&rxrpc_transport_lock);
95
96 /* not yet present - create a candidate for a new record and then
97 * redo the search */
98 candidate = rxrpc_alloc_transport(local, peer, gfp);
99 if (!candidate) {
100 _leave(" = -ENOMEM");
101 return ERR_PTR(-ENOMEM);
102 }
103
104 write_lock_bh(&rxrpc_transport_lock);
105
106 list_for_each_entry(trans, &rxrpc_transports, link) {
107 if (trans->local == local && trans->peer == peer)
108 goto found_extant_second;
109 }
110
111 /* we can now add the new candidate to the list */
112 trans = candidate;
113 candidate = NULL;
114
115 rxrpc_get_local(trans->local);
116 atomic_inc(&trans->peer->usage);
117 list_add_tail(&trans->link, &rxrpc_transports);
118 write_unlock_bh(&rxrpc_transport_lock);
119 new = "new";
120
121 success:
122 _net("TRANSPORT %s %d local %d -> peer %d",
123 new,
124 trans->debug_id,
125 trans->local->debug_id,
126 trans->peer->debug_id);
127
128 _leave(" = %p {u=%d}", trans, atomic_read(&trans->usage));
129 return trans;
130
131 /* we found the transport in the list immediately */
132 found_extant_transport:
133 usage = atomic_inc_return(&trans->usage);
134 read_unlock_bh(&rxrpc_transport_lock);
135 goto success;
136
137 /* we found the transport on the second time through the list */
138 found_extant_second:
139 usage = atomic_inc_return(&trans->usage);
140 write_unlock_bh(&rxrpc_transport_lock);
141 kfree(candidate);
142 goto success;
143 }
144
145 /*
146 * find the transport connecting two endpoints
147 */
rxrpc_find_transport(struct rxrpc_local * local,struct rxrpc_peer * peer)148 struct rxrpc_transport *rxrpc_find_transport(struct rxrpc_local *local,
149 struct rxrpc_peer *peer)
150 {
151 struct rxrpc_transport *trans;
152
153 _enter("{%pI4+%hu},{%pI4+%hu},",
154 &local->srx.transport.sin.sin_addr,
155 ntohs(local->srx.transport.sin.sin_port),
156 &peer->srx.transport.sin.sin_addr,
157 ntohs(peer->srx.transport.sin.sin_port));
158
159 /* search the transport list */
160 read_lock_bh(&rxrpc_transport_lock);
161
162 list_for_each_entry(trans, &rxrpc_transports, link) {
163 if (trans->local == local && trans->peer == peer)
164 goto found_extant_transport;
165 }
166
167 read_unlock_bh(&rxrpc_transport_lock);
168 _leave(" = NULL");
169 return NULL;
170
171 found_extant_transport:
172 atomic_inc(&trans->usage);
173 read_unlock_bh(&rxrpc_transport_lock);
174 _leave(" = %p", trans);
175 return trans;
176 }
177
178 /*
179 * release a transport session
180 */
rxrpc_put_transport(struct rxrpc_transport * trans)181 void rxrpc_put_transport(struct rxrpc_transport *trans)
182 {
183 _enter("%p{u=%d}", trans, atomic_read(&trans->usage));
184
185 ASSERTCMP(atomic_read(&trans->usage), >, 0);
186
187 trans->put_time = get_seconds();
188 if (unlikely(atomic_dec_and_test(&trans->usage))) {
189 _debug("zombie");
190 /* let the reaper determine the timeout to avoid a race with
191 * overextending the timeout if the reaper is running at the
192 * same time */
193 rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
194 }
195 _leave("");
196 }
197
198 /*
199 * clean up a transport session
200 */
rxrpc_cleanup_transport(struct rxrpc_transport * trans)201 static void rxrpc_cleanup_transport(struct rxrpc_transport *trans)
202 {
203 _net("DESTROY TRANS %d", trans->debug_id);
204
205 rxrpc_purge_queue(&trans->error_queue);
206
207 rxrpc_put_local(trans->local);
208 rxrpc_put_peer(trans->peer);
209 kfree(trans);
210 }
211
212 /*
213 * reap dead transports that have passed their expiry date
214 */
rxrpc_transport_reaper(struct work_struct * work)215 static void rxrpc_transport_reaper(struct work_struct *work)
216 {
217 struct rxrpc_transport *trans, *_p;
218 unsigned long now, earliest, reap_time;
219
220 LIST_HEAD(graveyard);
221
222 _enter("");
223
224 now = get_seconds();
225 earliest = ULONG_MAX;
226
227 /* extract all the transports that have been dead too long */
228 write_lock_bh(&rxrpc_transport_lock);
229 list_for_each_entry_safe(trans, _p, &rxrpc_transports, link) {
230 _debug("reap TRANS %d { u=%d t=%ld }",
231 trans->debug_id, atomic_read(&trans->usage),
232 (long) now - (long) trans->put_time);
233
234 if (likely(atomic_read(&trans->usage) > 0))
235 continue;
236
237 reap_time = trans->put_time + rxrpc_transport_timeout;
238 if (reap_time <= now)
239 list_move_tail(&trans->link, &graveyard);
240 else if (reap_time < earliest)
241 earliest = reap_time;
242 }
243 write_unlock_bh(&rxrpc_transport_lock);
244
245 if (earliest != ULONG_MAX) {
246 _debug("reschedule reaper %ld", (long) earliest - now);
247 ASSERTCMP(earliest, >, now);
248 rxrpc_queue_delayed_work(&rxrpc_transport_reap,
249 (earliest - now) * HZ);
250 }
251
252 /* then destroy all those pulled out */
253 while (!list_empty(&graveyard)) {
254 trans = list_entry(graveyard.next, struct rxrpc_transport,
255 link);
256 list_del_init(&trans->link);
257
258 ASSERTCMP(atomic_read(&trans->usage), ==, 0);
259 rxrpc_cleanup_transport(trans);
260 }
261
262 _leave("");
263 }
264
265 /*
266 * preemptively destroy all the transport session records rather than waiting
267 * for them to time out
268 */
rxrpc_destroy_all_transports(void)269 void __exit rxrpc_destroy_all_transports(void)
270 {
271 _enter("");
272
273 rxrpc_transport_timeout = 0;
274 cancel_delayed_work(&rxrpc_transport_reap);
275 rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
276
277 _leave("");
278 }
279