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4a3388c8 DH |
1 | /* Client connection-specific management code. |
2 | * | |
3 | * Copyright (C) 2016 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 Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
13 | ||
14 | #include <linux/slab.h> | |
15 | #include <linux/idr.h> | |
16 | #include <linux/timer.h> | |
17 | #include "ar-internal.h" | |
18 | ||
19 | /* | |
20 | * We use machine-unique IDs for our client connections. | |
21 | */ | |
22 | DEFINE_IDR(rxrpc_client_conn_ids); | |
23 | static DEFINE_SPINLOCK(rxrpc_conn_id_lock); | |
24 | ||
25 | /* | |
26 | * Get a connection ID and epoch for a client connection from the global pool. | |
27 | * The connection struct pointer is then recorded in the idr radix tree. The | |
28 | * epoch is changed if this wraps. | |
29 | * | |
30 | * TODO: The IDR tree gets very expensive on memory if the connection IDs are | |
31 | * widely scattered throughout the number space, so we shall need to retire | |
32 | * connections that have, say, an ID more than four times the maximum number of | |
33 | * client conns away from the current allocation point to try and keep the IDs | |
34 | * concentrated. We will also need to retire connections from an old epoch. | |
35 | */ | |
999b69f8 | 36 | int rxrpc_get_client_connection_id(struct rxrpc_connection *conn, gfp_t gfp) |
4a3388c8 DH |
37 | { |
38 | u32 epoch; | |
39 | int id; | |
40 | ||
41 | _enter(""); | |
42 | ||
43 | idr_preload(gfp); | |
4a3388c8 DH |
44 | spin_lock(&rxrpc_conn_id_lock); |
45 | ||
46 | epoch = rxrpc_epoch; | |
47 | ||
48 | /* We could use idr_alloc_cyclic() here, but we really need to know | |
49 | * when the thing wraps so that we can advance the epoch. | |
50 | */ | |
51 | if (rxrpc_client_conn_ids.cur == 0) | |
52 | rxrpc_client_conn_ids.cur = 1; | |
53 | id = idr_alloc(&rxrpc_client_conn_ids, conn, | |
54 | rxrpc_client_conn_ids.cur, 0x40000000, GFP_NOWAIT); | |
55 | if (id < 0) { | |
56 | if (id != -ENOSPC) | |
57 | goto error; | |
58 | id = idr_alloc(&rxrpc_client_conn_ids, conn, | |
59 | 1, 0x40000000, GFP_NOWAIT); | |
60 | if (id < 0) | |
61 | goto error; | |
62 | epoch++; | |
63 | rxrpc_epoch = epoch; | |
64 | } | |
65 | rxrpc_client_conn_ids.cur = id + 1; | |
66 | ||
67 | spin_unlock(&rxrpc_conn_id_lock); | |
4a3388c8 DH |
68 | idr_preload_end(); |
69 | ||
70 | conn->proto.epoch = epoch; | |
71 | conn->proto.cid = id << RXRPC_CIDSHIFT; | |
72 | set_bit(RXRPC_CONN_HAS_IDR, &conn->flags); | |
73 | _leave(" [CID %x:%x]", epoch, conn->proto.cid); | |
74 | return 0; | |
75 | ||
76 | error: | |
77 | spin_unlock(&rxrpc_conn_id_lock); | |
4a3388c8 DH |
78 | idr_preload_end(); |
79 | _leave(" = %d", id); | |
80 | return id; | |
81 | } | |
82 | ||
83 | /* | |
84 | * Release a connection ID for a client connection from the global pool. | |
85 | */ | |
86 | void rxrpc_put_client_connection_id(struct rxrpc_connection *conn) | |
87 | { | |
88 | if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) { | |
89 | spin_lock(&rxrpc_conn_id_lock); | |
90 | idr_remove(&rxrpc_client_conn_ids, | |
91 | conn->proto.cid >> RXRPC_CIDSHIFT); | |
92 | spin_unlock(&rxrpc_conn_id_lock); | |
93 | } | |
94 | } |