summaryrefslogtreecommitdiffstats
path: root/net/rxrpc/conn_client.c
blob: 6e1099ed1dbd9279f0e0c710e60a3ec5d12873d9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
/* Client connection-specific management code.
 *
 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/timer.h>
#include "ar-internal.h"

/*
 * We use machine-unique IDs for our client connections.
 */
DEFINE_IDR(rxrpc_client_conn_ids);
static DEFINE_SPINLOCK(rxrpc_conn_id_lock);

/*
 * Get a connection ID and epoch for a client connection from the global pool.
 * The connection struct pointer is then recorded in the idr radix tree.  The
 * epoch is changed if this wraps.
 *
 * TODO: The IDR tree gets very expensive on memory if the connection IDs are
 * widely scattered throughout the number space, so we shall need to retire
 * connections that have, say, an ID more than four times the maximum number of
 * client conns away from the current allocation point to try and keep the IDs
 * concentrated.  We will also need to retire connections from an old epoch.
 */
static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
					  gfp_t gfp)
{
	u32 epoch;
	int id;

	_enter("");

	idr_preload(gfp);
	spin_lock(&rxrpc_conn_id_lock);

	epoch = rxrpc_epoch;

	/* We could use idr_alloc_cyclic() here, but we really need to know
	 * when the thing wraps so that we can advance the epoch.
	 */
	if (rxrpc_client_conn_ids.cur == 0)
		rxrpc_client_conn_ids.cur = 1;
	id = idr_alloc(&rxrpc_client_conn_ids, conn,
		       rxrpc_client_conn_ids.cur, 0x40000000, GFP_NOWAIT);
	if (id < 0) {
		if (id != -ENOSPC)
			goto error;
		id = idr_alloc(&rxrpc_client_conn_ids, conn,
			       1, 0x40000000, GFP_NOWAIT);
		if (id < 0)
			goto error;
		epoch++;
		rxrpc_epoch = epoch;
	}
	rxrpc_client_conn_ids.cur = id + 1;

	spin_unlock(&rxrpc_conn_id_lock);
	idr_preload_end();

	conn->proto.epoch = epoch;
	conn->proto.cid = id << RXRPC_CIDSHIFT;
	set_bit(RXRPC_CONN_HAS_IDR, &conn->flags);
	_leave(" [CID %x:%x]", epoch, conn->proto.cid);
	return 0;

error:
	spin_unlock(&rxrpc_conn_id_lock);
	idr_preload_end();
	_leave(" = %d", id);
	return id;
}

/*
 * Release a connection ID for a client connection from the global pool.
 */
static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
{
	if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) {
		spin_lock(&rxrpc_conn_id_lock);
		idr_remove(&rxrpc_client_conn_ids,
			   conn->proto.cid >> RXRPC_CIDSHIFT);
		spin_unlock(&rxrpc_conn_id_lock);
	}
}

/*
 * Destroy the client connection ID tree.
 */
void rxrpc_destroy_client_conn_ids(void)
{
	struct rxrpc_connection *conn;
	int id;

	if (!idr_is_empty(&rxrpc_client_conn_ids)) {
		idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) {
			pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
			       conn, atomic_read(&conn->usage));
		}
		BUG();
	}

	idr_destroy(&rxrpc_client_conn_ids);
}

/*
 * Allocate a client connection.  The caller must take care to clear any
 * padding bytes in *cp.
 */
static struct rxrpc_connection *
rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp)
{
	struct rxrpc_connection *conn;
	int ret;

	_enter("");

	conn = rxrpc_alloc_connection(gfp);
	if (!conn) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	conn->params		= *cp;
	conn->out_clientflag	= RXRPC_CLIENT_INITIATED;
	conn->state		= RXRPC_CONN_CLIENT;

	ret = rxrpc_get_client_connection_id(conn, gfp);
	if (ret < 0)
		goto error_0;

	ret = rxrpc_init_client_conn_security(conn);
	if (ret < 0)
		goto error_1;

	ret = conn->security->prime_packet_security(conn);
	if (ret < 0)
		goto error_2;

	write_lock(&rxrpc_connection_lock);
	list_add_tail(&conn->link, &rxrpc_connections);
	list_add_tail(&conn->proc_link, &rxrpc_connection_proc_list);
	write_unlock(&rxrpc_connection_lock);

	/* We steal the caller's peer ref. */
	cp->peer = NULL;
	rxrpc_get_local(conn->params.local);
	key_get(conn->params.key);

	_leave(" = %p", conn);
	return conn;

error_2:
	conn->security->clear(conn);
error_1:
	rxrpc_put_client_connection_id(conn);
error_0:
	kfree(conn);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
}

/*
 * find a connection for a call
 * - called in process context with IRQs enabled
 */
int rxrpc_connect_call(struct rxrpc_call *call,
		       struct rxrpc_conn_parameters *cp,
		       struct sockaddr_rxrpc *srx,
		       gfp_t gfp)
{
	struct rxrpc_connection *conn, *candidate = NULL;
	struct rxrpc_local *local = cp->local;
	struct rb_node *p, **pp, *parent;
	long diff;
	int chan;

	DECLARE_WAITQUEUE(myself, current);

	_enter("{%d,%lx},", call->debug_id, call->user_call_ID);

	cp->peer = rxrpc_lookup_peer(cp->local, srx, gfp);
	if (!cp->peer)
		return -ENOMEM;

	if (!cp->exclusive) {
		/* Search for a existing client connection unless this is going
		 * to be a connection that's used exclusively for a single call.
		 */
		_debug("search 1");
		spin_lock(&local->client_conns_lock);
		p = local->client_conns.rb_node;
		while (p) {
			conn = rb_entry(p, struct rxrpc_connection, client_node);

#define cmp(X) ((long)conn->params.X - (long)cp->X)
			diff = (cmp(peer) ?:
				cmp(key) ?:
				cmp(security_level));
			if (diff < 0)
				p = p->rb_left;
			else if (diff > 0)
				p = p->rb_right;
			else
				goto found_extant_conn;
		}
		spin_unlock(&local->client_conns_lock);
	}

	/* We didn't find a connection or we want an exclusive one. */
	_debug("get new conn");
	candidate = rxrpc_alloc_client_connection(cp, gfp);
	if (!candidate) {
		_leave(" = -ENOMEM");
		return -ENOMEM;
	}

	if (cp->exclusive) {
		/* Assign the call on an exclusive connection to channel 0 and
		 * don't add the connection to the endpoint's shareable conn
		 * lookup tree.
		 */
		_debug("exclusive chan 0");
		conn = candidate;
		atomic_set(&conn->avail_chans, RXRPC_MAXCALLS - 1);
		spin_lock(&conn->channel_lock);
		chan = 0;
		goto found_channel;
	}

	/* We need to redo the search before attempting to add a new connection
	 * lest we race with someone else adding a conflicting instance.
	 */
	_debug("search 2");
	spin_lock(&local->client_conns_lock);

	pp = &local->client_conns.rb_node;
	parent = NULL;
	while (*pp) {
		parent = *pp;
		conn = rb_entry(parent, struct rxrpc_connection, client_node);

		diff = (cmp(peer) ?:
			cmp(key) ?:
			cmp(security_level));
		if (diff < 0)
			pp = &(*pp)->rb_left;
		else if (diff > 0)
			pp = &(*pp)->rb_right;
		else
			goto found_extant_conn;
	}

	/* The second search also failed; simply add the new connection with
	 * the new call in channel 0.  Note that we need to take the channel
	 * lock before dropping the client conn lock.
	 */
	_debug("new conn");
	set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags);
	rb_link_node(&candidate->client_node, parent, pp);
	rb_insert_color(&candidate->client_node, &local->client_conns);
attached:
	conn = candidate;
	candidate = NULL;

	atomic_set(&conn->avail_chans, RXRPC_MAXCALLS - 1);
	spin_lock(&conn->channel_lock);
	spin_unlock(&local->client_conns_lock);
	chan = 0;

found_channel:
	_debug("found chan");
	call->conn	= conn;
	call->peer	= rxrpc_get_peer(conn->params.peer);
	call->cid	= conn->proto.cid | chan;
	call->call_id	= ++conn->channels[chan].call_counter;
	conn->channels[chan].call_id = call->call_id;
	rcu_assign_pointer(conn->channels[chan].call, call);

	_net("CONNECT call %d on conn %d", call->debug_id, conn->debug_id);

	spin_unlock(&conn->channel_lock);
	rxrpc_put_peer(cp->peer);
	cp->peer = NULL;
	_leave(" = %p {u=%d}", conn, atomic_read(&conn->usage));
	return 0;

	/* We found a potentially suitable connection already in existence.  If
	 * we can reuse it (ie. its usage count hasn't been reduced to 0 by the
	 * reaper), discard any candidate we may have allocated, and try to get
	 * a channel on this one, otherwise we have to replace it.
	 */
found_extant_conn:
	_debug("found conn");
	if (!rxrpc_get_connection_maybe(conn)) {
		set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags);
		rb_replace_node(&conn->client_node,
				&candidate->client_node,
				&local->client_conns);
		clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags);
		goto attached;
	}

	spin_unlock(&local->client_conns_lock);

	rxrpc_put_connection(candidate);

	if (!atomic_add_unless(&conn->avail_chans, -1, 0)) {
		if (!gfpflags_allow_blocking(gfp)) {
			rxrpc_put_connection(conn);
			_leave(" = -EAGAIN");
			return -EAGAIN;
		}

		add_wait_queue(&conn->channel_wq, &myself);
		for (;;) {
			set_current_state(TASK_INTERRUPTIBLE);
			if (atomic_add_unless(&conn->avail_chans, -1, 0))
				break;
			if (signal_pending(current))
				goto interrupted;
			schedule();
		}
		remove_wait_queue(&conn->channel_wq, &myself);
		__set_current_state(TASK_RUNNING);
	}

	/* The connection allegedly now has a free channel and we can now
	 * attach the call to it.
	 */
	spin_lock(&conn->channel_lock);

	for (chan = 0; chan < RXRPC_MAXCALLS; chan++)
		if (!conn->channels[chan].call)
			goto found_channel;
	BUG();

interrupted:
	remove_wait_queue(&conn->channel_wq, &myself);
	__set_current_state(TASK_RUNNING);
	rxrpc_put_connection(conn);
	rxrpc_put_peer(cp->peer);
	cp->peer = NULL;
	_leave(" = -ERESTARTSYS");
	return -ERESTARTSYS;
}

/*
 * Remove a client connection from the local endpoint's tree, thereby removing
 * it as a target for reuse for new client calls.
 */
void rxrpc_unpublish_client_conn(struct rxrpc_connection *conn)
{
	struct rxrpc_local *local = conn->params.local;

	spin_lock(&local->client_conns_lock);
	if (test_and_clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags))
		rb_erase(&conn->client_node, &local->client_conns);
	spin_unlock(&local->client_conns_lock);

	rxrpc_put_client_connection_id(conn);
}