Merge branch 'xen-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen
[linux-2.6] / net / ipv4 / inet_fragment.c
1 /*
2  * inet fragments management
3  *
4  *              This program is free software; you can redistribute it and/or
5  *              modify it under the terms of the GNU General Public License
6  *              as published by the Free Software Foundation; either version
7  *              2 of the License, or (at your option) any later version.
8  *
9  *              Authors:        Pavel Emelyanov <xemul@openvz.org>
10  *                              Started as consolidation of ipv4/ip_fragment.c,
11  *                              ipv6/reassembly. and ipv6 nf conntrack reassembly
12  */
13
14 #include <linux/list.h>
15 #include <linux/spinlock.h>
16 #include <linux/module.h>
17 #include <linux/timer.h>
18 #include <linux/mm.h>
19 #include <linux/random.h>
20 #include <linux/skbuff.h>
21 #include <linux/rtnetlink.h>
22
23 #include <net/inet_frag.h>
24
25 static void inet_frag_secret_rebuild(unsigned long dummy)
26 {
27         struct inet_frags *f = (struct inet_frags *)dummy;
28         unsigned long now = jiffies;
29         int i;
30
31         write_lock(&f->lock);
32         get_random_bytes(&f->rnd, sizeof(u32));
33         for (i = 0; i < INETFRAGS_HASHSZ; i++) {
34                 struct inet_frag_queue *q;
35                 struct hlist_node *p, *n;
36
37                 hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) {
38                         unsigned int hval = f->hashfn(q);
39
40                         if (hval != i) {
41                                 hlist_del(&q->list);
42
43                                 /* Relink to new hash chain. */
44                                 hlist_add_head(&q->list, &f->hash[hval]);
45                         }
46                 }
47         }
48         write_unlock(&f->lock);
49
50         mod_timer(&f->secret_timer, now + f->ctl->secret_interval);
51 }
52
53 void inet_frags_init(struct inet_frags *f)
54 {
55         int i;
56
57         for (i = 0; i < INETFRAGS_HASHSZ; i++)
58                 INIT_HLIST_HEAD(&f->hash[i]);
59
60         INIT_LIST_HEAD(&f->lru_list);
61         rwlock_init(&f->lock);
62
63         f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
64                                    (jiffies ^ (jiffies >> 6)));
65
66         f->nqueues = 0;
67         atomic_set(&f->mem, 0);
68
69         init_timer(&f->secret_timer);
70         f->secret_timer.function = inet_frag_secret_rebuild;
71         f->secret_timer.data = (unsigned long)f;
72         f->secret_timer.expires = jiffies + f->ctl->secret_interval;
73         add_timer(&f->secret_timer);
74 }
75 EXPORT_SYMBOL(inet_frags_init);
76
77 void inet_frags_fini(struct inet_frags *f)
78 {
79         del_timer(&f->secret_timer);
80 }
81 EXPORT_SYMBOL(inet_frags_fini);
82
83 static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
84 {
85         write_lock(&f->lock);
86         hlist_del(&fq->list);
87         list_del(&fq->lru_list);
88         f->nqueues--;
89         write_unlock(&f->lock);
90 }
91
92 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
93 {
94         if (del_timer(&fq->timer))
95                 atomic_dec(&fq->refcnt);
96
97         if (!(fq->last_in & COMPLETE)) {
98                 fq_unlink(fq, f);
99                 atomic_dec(&fq->refcnt);
100                 fq->last_in |= COMPLETE;
101         }
102 }
103
104 EXPORT_SYMBOL(inet_frag_kill);
105
106 static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb,
107                                                 int *work)
108 {
109         if (work)
110                 *work -= skb->truesize;
111
112         atomic_sub(skb->truesize, &f->mem);
113         if (f->skb_free)
114                 f->skb_free(skb);
115         kfree_skb(skb);
116 }
117
118 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
119                                         int *work)
120 {
121         struct sk_buff *fp;
122
123         BUG_TRAP(q->last_in & COMPLETE);
124         BUG_TRAP(del_timer(&q->timer) == 0);
125
126         /* Release all fragment data. */
127         fp = q->fragments;
128         while (fp) {
129                 struct sk_buff *xp = fp->next;
130
131                 frag_kfree_skb(f, fp, work);
132                 fp = xp;
133         }
134
135         if (work)
136                 *work -= f->qsize;
137         atomic_sub(f->qsize, &f->mem);
138
139         f->destructor(q);
140
141 }
142 EXPORT_SYMBOL(inet_frag_destroy);
143
144 int inet_frag_evictor(struct inet_frags *f)
145 {
146         struct inet_frag_queue *q;
147         int work, evicted = 0;
148
149         work = atomic_read(&f->mem) - f->ctl->low_thresh;
150         while (work > 0) {
151                 read_lock(&f->lock);
152                 if (list_empty(&f->lru_list)) {
153                         read_unlock(&f->lock);
154                         break;
155                 }
156
157                 q = list_first_entry(&f->lru_list,
158                                 struct inet_frag_queue, lru_list);
159                 atomic_inc(&q->refcnt);
160                 read_unlock(&f->lock);
161
162                 spin_lock(&q->lock);
163                 if (!(q->last_in & COMPLETE))
164                         inet_frag_kill(q, f);
165                 spin_unlock(&q->lock);
166
167                 if (atomic_dec_and_test(&q->refcnt))
168                         inet_frag_destroy(q, f, &work);
169                 evicted++;
170         }
171
172         return evicted;
173 }
174 EXPORT_SYMBOL(inet_frag_evictor);