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77d8bf9c ACM |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Generic INET transport hashtables | |
7 | * | |
8 | * Authors: Lotsa people, from code originally in tcp | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License | |
12 | * as published by the Free Software Foundation; either version | |
13 | * 2 of the License, or (at your option) any later version. | |
14 | */ | |
15 | ||
16 | #include <linux/config.h> | |
2d8c4ce5 | 17 | #include <linux/module.h> |
f3f05f70 | 18 | #include <linux/sched.h> |
77d8bf9c | 19 | #include <linux/slab.h> |
f3f05f70 | 20 | #include <linux/wait.h> |
77d8bf9c ACM |
21 | |
22 | #include <net/inet_hashtables.h> | |
23 | ||
24 | /* | |
25 | * Allocate and initialize a new local port bind bucket. | |
26 | * The bindhash mutex for snum's hash chain must be held here. | |
27 | */ | |
28 | struct inet_bind_bucket *inet_bind_bucket_create(kmem_cache_t *cachep, | |
29 | struct inet_bind_hashbucket *head, | |
30 | const unsigned short snum) | |
31 | { | |
32 | struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, SLAB_ATOMIC); | |
33 | ||
34 | if (tb != NULL) { | |
35 | tb->port = snum; | |
36 | tb->fastreuse = 0; | |
37 | INIT_HLIST_HEAD(&tb->owners); | |
38 | hlist_add_head(&tb->node, &head->chain); | |
39 | } | |
40 | return tb; | |
41 | } | |
42 | ||
43 | EXPORT_SYMBOL(inet_bind_bucket_create); | |
44 | ||
45 | /* | |
46 | * Caller must hold hashbucket lock for this tb with local BH disabled | |
47 | */ | |
48 | void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb) | |
49 | { | |
50 | if (hlist_empty(&tb->owners)) { | |
51 | __hlist_del(&tb->node); | |
52 | kmem_cache_free(cachep, tb); | |
53 | } | |
54 | } | |
2d8c4ce5 ACM |
55 | |
56 | void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, | |
57 | const unsigned short snum) | |
58 | { | |
59 | struct inet_sock *inet = inet_sk(sk); | |
60 | inet->num = snum; | |
61 | sk_add_bind_node(sk, &tb->owners); | |
62 | inet->bind_hash = tb; | |
63 | } | |
64 | ||
65 | EXPORT_SYMBOL(inet_bind_hash); | |
66 | ||
67 | /* | |
68 | * Get rid of any references to a local port held by the given sock. | |
69 | */ | |
70 | static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk) | |
71 | { | |
72 | struct inet_sock *inet = inet_sk(sk); | |
73 | const int bhash = inet_bhashfn(inet->num, hashinfo->bhash_size); | |
74 | struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash]; | |
75 | struct inet_bind_bucket *tb; | |
76 | ||
77 | spin_lock(&head->lock); | |
78 | tb = inet->bind_hash; | |
79 | __sk_del_bind_node(sk); | |
80 | inet->bind_hash = NULL; | |
81 | inet->num = 0; | |
82 | inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); | |
83 | spin_unlock(&head->lock); | |
84 | } | |
85 | ||
86 | void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk) | |
87 | { | |
88 | local_bh_disable(); | |
89 | __inet_put_port(hashinfo, sk); | |
90 | local_bh_enable(); | |
91 | } | |
92 | ||
93 | EXPORT_SYMBOL(inet_put_port); | |
f3f05f70 ACM |
94 | |
95 | /* | |
96 | * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP. | |
97 | * Look, when several writers sleep and reader wakes them up, all but one | |
98 | * immediately hit write lock and grab all the cpus. Exclusive sleep solves | |
99 | * this, _but_ remember, it adds useless work on UP machines (wake up each | |
100 | * exclusive lock release). It should be ifdefed really. | |
101 | */ | |
102 | void inet_listen_wlock(struct inet_hashinfo *hashinfo) | |
103 | { | |
104 | write_lock(&hashinfo->lhash_lock); | |
105 | ||
106 | if (atomic_read(&hashinfo->lhash_users)) { | |
107 | DEFINE_WAIT(wait); | |
108 | ||
109 | for (;;) { | |
110 | prepare_to_wait_exclusive(&hashinfo->lhash_wait, | |
111 | &wait, TASK_UNINTERRUPTIBLE); | |
112 | if (!atomic_read(&hashinfo->lhash_users)) | |
113 | break; | |
114 | write_unlock_bh(&hashinfo->lhash_lock); | |
115 | schedule(); | |
116 | write_lock_bh(&hashinfo->lhash_lock); | |
117 | } | |
118 | ||
119 | finish_wait(&hashinfo->lhash_wait, &wait); | |
120 | } | |
121 | } | |
122 | ||
123 | EXPORT_SYMBOL(inet_listen_wlock); |