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