Linux 2.6.26-rc5
[linux-2.6/openmoko-kernel/knife-kernel.git] / net / ipv4 / inet_fragment.c
blob4ed429bd5951542401130f16e3a4f0341ded3920
1 /*
2 * inet fragments management
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.
9 * Authors: Pavel Emelyanov <xemul@openvz.org>
10 * Started as consolidation of ipv4/ip_fragment.c,
11 * ipv6/reassembly. and ipv6 nf conntrack reassembly
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>
23 #include <net/inet_frag.h>
25 static void inet_frag_secret_rebuild(unsigned long dummy)
27 struct inet_frags *f = (struct inet_frags *)dummy;
28 unsigned long now = jiffies;
29 int i;
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;
37 hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) {
38 unsigned int hval = f->hashfn(q);
40 if (hval != i) {
41 hlist_del(&q->list);
43 /* Relink to new hash chain. */
44 hlist_add_head(&q->list, &f->hash[hval]);
48 write_unlock(&f->lock);
50 mod_timer(&f->secret_timer, now + f->secret_interval);
53 void inet_frags_init(struct inet_frags *f)
55 int i;
57 for (i = 0; i < INETFRAGS_HASHSZ; i++)
58 INIT_HLIST_HEAD(&f->hash[i]);
60 rwlock_init(&f->lock);
62 f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
63 (jiffies ^ (jiffies >> 6)));
65 setup_timer(&f->secret_timer, inet_frag_secret_rebuild,
66 (unsigned long)f);
67 f->secret_timer.expires = jiffies + f->secret_interval;
68 add_timer(&f->secret_timer);
70 EXPORT_SYMBOL(inet_frags_init);
72 void inet_frags_init_net(struct netns_frags *nf)
74 nf->nqueues = 0;
75 atomic_set(&nf->mem, 0);
76 INIT_LIST_HEAD(&nf->lru_list);
78 EXPORT_SYMBOL(inet_frags_init_net);
80 void inet_frags_fini(struct inet_frags *f)
82 del_timer(&f->secret_timer);
84 EXPORT_SYMBOL(inet_frags_fini);
86 void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f)
88 nf->low_thresh = 0;
90 local_bh_disable();
91 inet_frag_evictor(nf, f);
92 local_bh_enable();
94 EXPORT_SYMBOL(inet_frags_exit_net);
96 static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
98 write_lock(&f->lock);
99 hlist_del(&fq->list);
100 list_del(&fq->lru_list);
101 fq->net->nqueues--;
102 write_unlock(&f->lock);
105 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
107 if (del_timer(&fq->timer))
108 atomic_dec(&fq->refcnt);
110 if (!(fq->last_in & INET_FRAG_COMPLETE)) {
111 fq_unlink(fq, f);
112 atomic_dec(&fq->refcnt);
113 fq->last_in |= INET_FRAG_COMPLETE;
117 EXPORT_SYMBOL(inet_frag_kill);
119 static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f,
120 struct sk_buff *skb, int *work)
122 if (work)
123 *work -= skb->truesize;
125 atomic_sub(skb->truesize, &nf->mem);
126 if (f->skb_free)
127 f->skb_free(skb);
128 kfree_skb(skb);
131 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
132 int *work)
134 struct sk_buff *fp;
135 struct netns_frags *nf;
137 BUG_TRAP(q->last_in & INET_FRAG_COMPLETE);
138 BUG_TRAP(del_timer(&q->timer) == 0);
140 /* Release all fragment data. */
141 fp = q->fragments;
142 nf = q->net;
143 while (fp) {
144 struct sk_buff *xp = fp->next;
146 frag_kfree_skb(nf, f, fp, work);
147 fp = xp;
150 if (work)
151 *work -= f->qsize;
152 atomic_sub(f->qsize, &nf->mem);
154 if (f->destructor)
155 f->destructor(q);
156 kfree(q);
159 EXPORT_SYMBOL(inet_frag_destroy);
161 int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f)
163 struct inet_frag_queue *q;
164 int work, evicted = 0;
166 work = atomic_read(&nf->mem) - nf->low_thresh;
167 while (work > 0) {
168 read_lock(&f->lock);
169 if (list_empty(&nf->lru_list)) {
170 read_unlock(&f->lock);
171 break;
174 q = list_first_entry(&nf->lru_list,
175 struct inet_frag_queue, lru_list);
176 atomic_inc(&q->refcnt);
177 read_unlock(&f->lock);
179 spin_lock(&q->lock);
180 if (!(q->last_in & INET_FRAG_COMPLETE))
181 inet_frag_kill(q, f);
182 spin_unlock(&q->lock);
184 if (atomic_dec_and_test(&q->refcnt))
185 inet_frag_destroy(q, f, &work);
186 evicted++;
189 return evicted;
191 EXPORT_SYMBOL(inet_frag_evictor);
193 static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
194 struct inet_frag_queue *qp_in, struct inet_frags *f,
195 unsigned int hash, void *arg)
197 struct inet_frag_queue *qp;
198 #ifdef CONFIG_SMP
199 struct hlist_node *n;
200 #endif
202 write_lock(&f->lock);
203 #ifdef CONFIG_SMP
204 /* With SMP race we have to recheck hash table, because
205 * such entry could be created on other cpu, while we
206 * promoted read lock to write lock.
208 hlist_for_each_entry(qp, n, &f->hash[hash], list) {
209 if (qp->net == nf && f->match(qp, arg)) {
210 atomic_inc(&qp->refcnt);
211 write_unlock(&f->lock);
212 qp_in->last_in |= INET_FRAG_COMPLETE;
213 inet_frag_put(qp_in, f);
214 return qp;
217 #endif
218 qp = qp_in;
219 if (!mod_timer(&qp->timer, jiffies + nf->timeout))
220 atomic_inc(&qp->refcnt);
222 atomic_inc(&qp->refcnt);
223 hlist_add_head(&qp->list, &f->hash[hash]);
224 list_add_tail(&qp->lru_list, &nf->lru_list);
225 nf->nqueues++;
226 write_unlock(&f->lock);
227 return qp;
230 static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
231 struct inet_frags *f, void *arg)
233 struct inet_frag_queue *q;
235 q = kzalloc(f->qsize, GFP_ATOMIC);
236 if (q == NULL)
237 return NULL;
239 f->constructor(q, arg);
240 atomic_add(f->qsize, &nf->mem);
241 setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
242 spin_lock_init(&q->lock);
243 atomic_set(&q->refcnt, 1);
244 q->net = nf;
246 return q;
249 static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
250 struct inet_frags *f, void *arg, unsigned int hash)
252 struct inet_frag_queue *q;
254 q = inet_frag_alloc(nf, f, arg);
255 if (q == NULL)
256 return NULL;
258 return inet_frag_intern(nf, q, f, hash, arg);
261 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
262 struct inet_frags *f, void *key, unsigned int hash)
264 struct inet_frag_queue *q;
265 struct hlist_node *n;
267 read_lock(&f->lock);
268 hlist_for_each_entry(q, n, &f->hash[hash], list) {
269 if (q->net == nf && f->match(q, key)) {
270 atomic_inc(&q->refcnt);
271 read_unlock(&f->lock);
272 return q;
275 read_unlock(&f->lock);
277 return inet_frag_create(nf, f, key, hash);
279 EXPORT_SYMBOL(inet_frag_find);