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/*
* inet fragments management
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Pavel Emelyanov <xemul@openvz.org>
* Started as consolidation of ipv4/ip_fragment.c,
* ipv6/reassembly. and ipv6 nf conntrack reassembly
*/
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <net/inet_frag.h>
static void inet_frag_secret_rebuild(unsigned long dummy)
{
struct inet_frags *f = (struct inet_frags *)dummy;
unsigned long now = jiffies;
int i;
write_lock(&f->lock);
get_random_bytes(&f->rnd, sizeof(u32));
for (i = 0; i < INETFRAGS_HASHSZ; i++) {
struct inet_frag_queue *q;
struct hlist_node *p, *n;
hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) {
unsigned int hval = f->hashfn(q);
if (hval != i) {
hlist_del(&q->list);
/* Relink to new hash chain. */
hlist_add_head(&q->list, &f->hash[hval]);
}
}
}
write_unlock(&f->lock);
mod_timer(&f->secret_timer, now + f->ctl->secret_interval);
}
void inet_frags_init(struct inet_frags *f)
{
int i;
for (i = 0; i < INETFRAGS_HASHSZ; i++)
INIT_HLIST_HEAD(&f->hash[i]);
INIT_LIST_HEAD(&f->lru_list);
rwlock_init(&f->lock);
f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
(jiffies ^ (jiffies >> 6)));
f->nqueues = 0;
atomic_set(&f->mem, 0);
init_timer(&f->secret_timer);
f->secret_timer.function = inet_frag_secret_rebuild;
f->secret_timer.data = (unsigned long)f;
f->secret_timer.expires = jiffies + f->ctl->secret_interval;
add_timer(&f->secret_timer);
}
EXPORT_SYMBOL(inet_frags_init);
void inet_frags_fini(struct inet_frags *f)
{
del_timer(&f->secret_timer);
}
EXPORT_SYMBOL(inet_frags_fini);
static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
{
write_lock(&f->lock);
hlist_del(&fq->list);
list_del(&fq->lru_list);
f->nqueues--;
write_unlock(&f->lock);
}
void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
{
if (del_timer(&fq->timer))
atomic_dec(&fq->refcnt);
if (!(fq->last_in & COMPLETE)) {
fq_unlink(fq, f);
atomic_dec(&fq->refcnt);
fq->last_in |= COMPLETE;
}
}
EXPORT_SYMBOL(inet_frag_kill);
static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb,
int *work)
{
if (work)
*work -= skb->truesize;
atomic_sub(skb->truesize, &f->mem);
if (f->skb_free)
f->skb_free(skb);
kfree_skb(skb);
}
void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
int *work)
{
struct sk_buff *fp;
BUG_TRAP(q->last_in & COMPLETE);
BUG_TRAP(del_timer(&q->timer) == 0);
/* Release all fragment data. */
fp = q->fragments;
while (fp) {
struct sk_buff *xp = fp->next;
frag_kfree_skb(f, fp, work);
fp = xp;
}
if (work)
*work -= f->qsize;
atomic_sub(f->qsize, &f->mem);
f->destructor(q);
}
EXPORT_SYMBOL(inet_frag_destroy);
int inet_frag_evictor(struct inet_frags *f)
{
struct inet_frag_queue *q;
int work, evicted = 0;
work = atomic_read(&f->mem) - f->ctl->low_thresh;
while (work > 0) {
read_lock(&f->lock);
if (list_empty(&f->lru_list)) {
read_unlock(&f->lock);
break;
}
q = list_first_entry(&f->lru_list,
struct inet_frag_queue, lru_list);
atomic_inc(&q->refcnt);
read_unlock(&f->lock);
spin_lock(&q->lock);
if (!(q->last_in & COMPLETE))
inet_frag_kill(q, f);
spin_unlock(&q->lock);
if (atomic_dec_and_test(&q->refcnt))
inet_frag_destroy(q, f, &work);
evicted++;
}
return evicted;
}
EXPORT_SYMBOL(inet_frag_evictor);
struct inet_frag_queue *inet_frag_intern(struct inet_frag_queue *qp_in,
struct inet_frags *f, unsigned int hash)
{
struct inet_frag_queue *qp;
#ifdef CONFIG_SMP
struct hlist_node *n;
#endif
write_lock(&f->lock);
#ifdef CONFIG_SMP
/* With SMP race we have to recheck hash table, because
* such entry could be created on other cpu, while we
* promoted read lock to write lock.
*/
hlist_for_each_entry(qp, n, &f->hash[hash], list) {
if (f->equal(qp, qp_in)) {
atomic_inc(&qp->refcnt);
write_unlock(&f->lock);
qp_in->last_in |= COMPLETE;
inet_frag_put(qp_in, f);
return qp;
}
}
#endif
qp = qp_in;
if (!mod_timer(&qp->timer, jiffies + f->ctl->timeout))
atomic_inc(&qp->refcnt);
atomic_inc(&qp->refcnt);
hlist_add_head(&qp->list, &f->hash[hash]);
list_add_tail(&qp->lru_list, &f->lru_list);
f->nqueues++;
write_unlock(&f->lock);
return qp;
}
EXPORT_SYMBOL(inet_frag_intern);
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