386 строки
11 KiB
C
386 строки
11 KiB
C
/*
|
|
* INET An implementation of the TCP/IP protocol suite for the LINUX
|
|
* operating system. INET is implemented using the BSD Socket
|
|
* interface as the means of communication with the user level.
|
|
*
|
|
* Generic TIME_WAIT sockets functions
|
|
*
|
|
* From code orinally in TCP
|
|
*/
|
|
|
|
#include <linux/config.h>
|
|
|
|
#include <net/inet_hashtables.h>
|
|
#include <net/inet_timewait_sock.h>
|
|
#include <net/ip.h>
|
|
|
|
/* Must be called with locally disabled BHs. */
|
|
void __inet_twsk_kill(struct inet_timewait_sock *tw, struct inet_hashinfo *hashinfo)
|
|
{
|
|
struct inet_bind_hashbucket *bhead;
|
|
struct inet_bind_bucket *tb;
|
|
/* Unlink from established hashes. */
|
|
struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, tw->tw_hash);
|
|
|
|
write_lock(&ehead->lock);
|
|
if (hlist_unhashed(&tw->tw_node)) {
|
|
write_unlock(&ehead->lock);
|
|
return;
|
|
}
|
|
__hlist_del(&tw->tw_node);
|
|
sk_node_init(&tw->tw_node);
|
|
write_unlock(&ehead->lock);
|
|
|
|
/* Disassociate with bind bucket. */
|
|
bhead = &hashinfo->bhash[inet_bhashfn(tw->tw_num, hashinfo->bhash_size)];
|
|
spin_lock(&bhead->lock);
|
|
tb = tw->tw_tb;
|
|
__hlist_del(&tw->tw_bind_node);
|
|
tw->tw_tb = NULL;
|
|
inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
|
|
spin_unlock(&bhead->lock);
|
|
#ifdef SOCK_REFCNT_DEBUG
|
|
if (atomic_read(&tw->tw_refcnt) != 1) {
|
|
printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n",
|
|
tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt));
|
|
}
|
|
#endif
|
|
inet_twsk_put(tw);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(__inet_twsk_kill);
|
|
|
|
/*
|
|
* Enter the time wait state. This is called with locally disabled BH.
|
|
* Essentially we whip up a timewait bucket, copy the relevant info into it
|
|
* from the SK, and mess with hash chains and list linkage.
|
|
*/
|
|
void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
|
|
struct inet_hashinfo *hashinfo)
|
|
{
|
|
const struct inet_sock *inet = inet_sk(sk);
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash);
|
|
struct inet_bind_hashbucket *bhead;
|
|
/* Step 1: Put TW into bind hash. Original socket stays there too.
|
|
Note, that any socket with inet->num != 0 MUST be bound in
|
|
binding cache, even if it is closed.
|
|
*/
|
|
bhead = &hashinfo->bhash[inet_bhashfn(inet->num, hashinfo->bhash_size)];
|
|
spin_lock(&bhead->lock);
|
|
tw->tw_tb = icsk->icsk_bind_hash;
|
|
BUG_TRAP(icsk->icsk_bind_hash);
|
|
inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
|
|
spin_unlock(&bhead->lock);
|
|
|
|
write_lock(&ehead->lock);
|
|
|
|
/* Step 2: Remove SK from established hash. */
|
|
if (__sk_del_node_init(sk))
|
|
sock_prot_dec_use(sk->sk_prot);
|
|
|
|
/* Step 3: Hash TW into TIMEWAIT half of established hash table. */
|
|
inet_twsk_add_node(tw, &(ehead + hashinfo->ehash_size)->chain);
|
|
atomic_inc(&tw->tw_refcnt);
|
|
|
|
write_unlock(&ehead->lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(__inet_twsk_hashdance);
|
|
|
|
struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state)
|
|
{
|
|
struct inet_timewait_sock *tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_slab,
|
|
SLAB_ATOMIC);
|
|
if (tw != NULL) {
|
|
const struct inet_sock *inet = inet_sk(sk);
|
|
|
|
/* Give us an identity. */
|
|
tw->tw_daddr = inet->daddr;
|
|
tw->tw_rcv_saddr = inet->rcv_saddr;
|
|
tw->tw_bound_dev_if = sk->sk_bound_dev_if;
|
|
tw->tw_num = inet->num;
|
|
tw->tw_state = TCP_TIME_WAIT;
|
|
tw->tw_substate = state;
|
|
tw->tw_sport = inet->sport;
|
|
tw->tw_dport = inet->dport;
|
|
tw->tw_family = sk->sk_family;
|
|
tw->tw_reuse = sk->sk_reuse;
|
|
tw->tw_hash = sk->sk_hash;
|
|
tw->tw_ipv6only = 0;
|
|
tw->tw_prot = sk->sk_prot_creator;
|
|
atomic_set(&tw->tw_refcnt, 1);
|
|
inet_twsk_dead_node_init(tw);
|
|
__module_get(tw->tw_prot->owner);
|
|
}
|
|
|
|
return tw;
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(inet_twsk_alloc);
|
|
|
|
/* Returns non-zero if quota exceeded. */
|
|
static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr,
|
|
const int slot)
|
|
{
|
|
struct inet_timewait_sock *tw;
|
|
struct hlist_node *node;
|
|
unsigned int killed;
|
|
int ret;
|
|
|
|
/* NOTE: compare this to previous version where lock
|
|
* was released after detaching chain. It was racy,
|
|
* because tw buckets are scheduled in not serialized context
|
|
* in 2.3 (with netfilter), and with softnet it is common, because
|
|
* soft irqs are not sequenced.
|
|
*/
|
|
killed = 0;
|
|
ret = 0;
|
|
rescan:
|
|
inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) {
|
|
__inet_twsk_del_dead_node(tw);
|
|
spin_unlock(&twdr->death_lock);
|
|
__inet_twsk_kill(tw, twdr->hashinfo);
|
|
inet_twsk_put(tw);
|
|
killed++;
|
|
spin_lock(&twdr->death_lock);
|
|
if (killed > INET_TWDR_TWKILL_QUOTA) {
|
|
ret = 1;
|
|
break;
|
|
}
|
|
|
|
/* While we dropped twdr->death_lock, another cpu may have
|
|
* killed off the next TW bucket in the list, therefore
|
|
* do a fresh re-read of the hlist head node with the
|
|
* lock reacquired. We still use the hlist traversal
|
|
* macro in order to get the prefetches.
|
|
*/
|
|
goto rescan;
|
|
}
|
|
|
|
twdr->tw_count -= killed;
|
|
NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed);
|
|
|
|
return ret;
|
|
}
|
|
|
|
void inet_twdr_hangman(unsigned long data)
|
|
{
|
|
struct inet_timewait_death_row *twdr;
|
|
int unsigned need_timer;
|
|
|
|
twdr = (struct inet_timewait_death_row *)data;
|
|
spin_lock(&twdr->death_lock);
|
|
|
|
if (twdr->tw_count == 0)
|
|
goto out;
|
|
|
|
need_timer = 0;
|
|
if (inet_twdr_do_twkill_work(twdr, twdr->slot)) {
|
|
twdr->thread_slots |= (1 << twdr->slot);
|
|
mb();
|
|
schedule_work(&twdr->twkill_work);
|
|
need_timer = 1;
|
|
} else {
|
|
/* We purged the entire slot, anything left? */
|
|
if (twdr->tw_count)
|
|
need_timer = 1;
|
|
}
|
|
twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1));
|
|
if (need_timer)
|
|
mod_timer(&twdr->tw_timer, jiffies + twdr->period);
|
|
out:
|
|
spin_unlock(&twdr->death_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(inet_twdr_hangman);
|
|
|
|
extern void twkill_slots_invalid(void);
|
|
|
|
void inet_twdr_twkill_work(void *data)
|
|
{
|
|
struct inet_timewait_death_row *twdr = data;
|
|
int i;
|
|
|
|
if ((INET_TWDR_TWKILL_SLOTS - 1) > (sizeof(twdr->thread_slots) * 8))
|
|
twkill_slots_invalid();
|
|
|
|
while (twdr->thread_slots) {
|
|
spin_lock_bh(&twdr->death_lock);
|
|
for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) {
|
|
if (!(twdr->thread_slots & (1 << i)))
|
|
continue;
|
|
|
|
while (inet_twdr_do_twkill_work(twdr, i) != 0) {
|
|
if (need_resched()) {
|
|
spin_unlock_bh(&twdr->death_lock);
|
|
schedule();
|
|
spin_lock_bh(&twdr->death_lock);
|
|
}
|
|
}
|
|
|
|
twdr->thread_slots &= ~(1 << i);
|
|
}
|
|
spin_unlock_bh(&twdr->death_lock);
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(inet_twdr_twkill_work);
|
|
|
|
/* These are always called from BH context. See callers in
|
|
* tcp_input.c to verify this.
|
|
*/
|
|
|
|
/* This is for handling early-kills of TIME_WAIT sockets. */
|
|
void inet_twsk_deschedule(struct inet_timewait_sock *tw,
|
|
struct inet_timewait_death_row *twdr)
|
|
{
|
|
spin_lock(&twdr->death_lock);
|
|
if (inet_twsk_del_dead_node(tw)) {
|
|
inet_twsk_put(tw);
|
|
if (--twdr->tw_count == 0)
|
|
del_timer(&twdr->tw_timer);
|
|
}
|
|
spin_unlock(&twdr->death_lock);
|
|
__inet_twsk_kill(tw, twdr->hashinfo);
|
|
}
|
|
|
|
EXPORT_SYMBOL(inet_twsk_deschedule);
|
|
|
|
void inet_twsk_schedule(struct inet_timewait_sock *tw,
|
|
struct inet_timewait_death_row *twdr,
|
|
const int timeo, const int timewait_len)
|
|
{
|
|
struct hlist_head *list;
|
|
int slot;
|
|
|
|
/* timeout := RTO * 3.5
|
|
*
|
|
* 3.5 = 1+2+0.5 to wait for two retransmits.
|
|
*
|
|
* RATIONALE: if FIN arrived and we entered TIME-WAIT state,
|
|
* our ACK acking that FIN can be lost. If N subsequent retransmitted
|
|
* FINs (or previous seqments) are lost (probability of such event
|
|
* is p^(N+1), where p is probability to lose single packet and
|
|
* time to detect the loss is about RTO*(2^N - 1) with exponential
|
|
* backoff). Normal timewait length is calculated so, that we
|
|
* waited at least for one retransmitted FIN (maximal RTO is 120sec).
|
|
* [ BTW Linux. following BSD, violates this requirement waiting
|
|
* only for 60sec, we should wait at least for 240 secs.
|
|
* Well, 240 consumes too much of resources 8)
|
|
* ]
|
|
* This interval is not reduced to catch old duplicate and
|
|
* responces to our wandering segments living for two MSLs.
|
|
* However, if we use PAWS to detect
|
|
* old duplicates, we can reduce the interval to bounds required
|
|
* by RTO, rather than MSL. So, if peer understands PAWS, we
|
|
* kill tw bucket after 3.5*RTO (it is important that this number
|
|
* is greater than TS tick!) and detect old duplicates with help
|
|
* of PAWS.
|
|
*/
|
|
slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK;
|
|
|
|
spin_lock(&twdr->death_lock);
|
|
|
|
/* Unlink it, if it was scheduled */
|
|
if (inet_twsk_del_dead_node(tw))
|
|
twdr->tw_count--;
|
|
else
|
|
atomic_inc(&tw->tw_refcnt);
|
|
|
|
if (slot >= INET_TWDR_RECYCLE_SLOTS) {
|
|
/* Schedule to slow timer */
|
|
if (timeo >= timewait_len) {
|
|
slot = INET_TWDR_TWKILL_SLOTS - 1;
|
|
} else {
|
|
slot = (timeo + twdr->period - 1) / twdr->period;
|
|
if (slot >= INET_TWDR_TWKILL_SLOTS)
|
|
slot = INET_TWDR_TWKILL_SLOTS - 1;
|
|
}
|
|
tw->tw_ttd = jiffies + timeo;
|
|
slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1);
|
|
list = &twdr->cells[slot];
|
|
} else {
|
|
tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK);
|
|
|
|
if (twdr->twcal_hand < 0) {
|
|
twdr->twcal_hand = 0;
|
|
twdr->twcal_jiffie = jiffies;
|
|
twdr->twcal_timer.expires = twdr->twcal_jiffie +
|
|
(slot << INET_TWDR_RECYCLE_TICK);
|
|
add_timer(&twdr->twcal_timer);
|
|
} else {
|
|
if (time_after(twdr->twcal_timer.expires,
|
|
jiffies + (slot << INET_TWDR_RECYCLE_TICK)))
|
|
mod_timer(&twdr->twcal_timer,
|
|
jiffies + (slot << INET_TWDR_RECYCLE_TICK));
|
|
slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1);
|
|
}
|
|
list = &twdr->twcal_row[slot];
|
|
}
|
|
|
|
hlist_add_head(&tw->tw_death_node, list);
|
|
|
|
if (twdr->tw_count++ == 0)
|
|
mod_timer(&twdr->tw_timer, jiffies + twdr->period);
|
|
spin_unlock(&twdr->death_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(inet_twsk_schedule);
|
|
|
|
void inet_twdr_twcal_tick(unsigned long data)
|
|
{
|
|
struct inet_timewait_death_row *twdr;
|
|
int n, slot;
|
|
unsigned long j;
|
|
unsigned long now = jiffies;
|
|
int killed = 0;
|
|
int adv = 0;
|
|
|
|
twdr = (struct inet_timewait_death_row *)data;
|
|
|
|
spin_lock(&twdr->death_lock);
|
|
if (twdr->twcal_hand < 0)
|
|
goto out;
|
|
|
|
slot = twdr->twcal_hand;
|
|
j = twdr->twcal_jiffie;
|
|
|
|
for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) {
|
|
if (time_before_eq(j, now)) {
|
|
struct hlist_node *node, *safe;
|
|
struct inet_timewait_sock *tw;
|
|
|
|
inet_twsk_for_each_inmate_safe(tw, node, safe,
|
|
&twdr->twcal_row[slot]) {
|
|
__inet_twsk_del_dead_node(tw);
|
|
__inet_twsk_kill(tw, twdr->hashinfo);
|
|
inet_twsk_put(tw);
|
|
killed++;
|
|
}
|
|
} else {
|
|
if (!adv) {
|
|
adv = 1;
|
|
twdr->twcal_jiffie = j;
|
|
twdr->twcal_hand = slot;
|
|
}
|
|
|
|
if (!hlist_empty(&twdr->twcal_row[slot])) {
|
|
mod_timer(&twdr->twcal_timer, j);
|
|
goto out;
|
|
}
|
|
}
|
|
j += 1 << INET_TWDR_RECYCLE_TICK;
|
|
slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1);
|
|
}
|
|
twdr->twcal_hand = -1;
|
|
|
|
out:
|
|
if ((twdr->tw_count -= killed) == 0)
|
|
del_timer(&twdr->tw_timer);
|
|
NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITKILLED, killed);
|
|
spin_unlock(&twdr->death_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick);
|