myinet_timewait_sock.c

一个基于linux的TCP/IP协议栈的实现

static inline void myinet_twsk_put(struct inet_timewait_sock *tw)
{
	printk(KERN_INFO "THE TW REFCNT: %d\n", atomic_read(&tw->tw_refcnt) );
	if( atomic_dec_and_test(&tw->tw_refcnt) ) {
		struct module *owner = tw->tw_prot->owner;
		printk(KERN_DEBUG "%s timewait_sock %p released\n",
		       tw->tw_prot->name, tw);
		kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw);
		module_put(owner);
	}
}

static int myinet_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;

	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);
		__myinet_twsk_kill(tw, twdr->hashinfo);
		myinet_twsk_put(tw);
		killed++;
		spin_lock(&twdr->death_lock);
		if (killed > INET_TWDR_TWKILL_QUOTA) {
			ret = 1;
			break;
		}
		goto rescan;
	}

	twdr->tw_count -= killed;
	NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed);

	return ret;
}

void myinet_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 (myinet_twdr_do_twkill_work(twdr, twdr->slot)) {
		twdr->thread_slots |= (1 << twdr->slot);
		mb();
		schedule_work(&twdr->twkill_work);
		need_timer = 1;
	} else {
		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);
}

extern void twkill_slots_invalid(void);

void myinet_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( myinet_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);
	}
}

void myinet_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;

	printk(KERN_INFO "tick!!!!!!!!!!!!!!!!!!!!!!!!!\n");
	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);
				__myinet_twsk_kill( tw, twdr->hashinfo );
				printk(KERN_INFO "call in time_wait sock 127!\n");
				myinet_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);
}

void __myinet_twsk_kill(struct inet_timewait_sock *tw, struct inet_hashinfo *hashinfo)
{
	struct inet_bind_hashbucket *bhead;
	struct inet_bind_bucket *tb;
	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);

	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;
	myinet_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
	myinet_twsk_put(tw);
}

void myinet_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)) {
		printk(KERN_INFO "call in time_wait sock 193!\n");
		myinet_twsk_put(tw);
		if (--twdr->tw_count == 0)
			del_timer(&twdr->tw_timer);
	}
	spin_unlock(&twdr->death_lock);
	__myinet_twsk_kill(tw, twdr->hashinfo);
}

struct inet_timewait_sock *myinet_twsk_alloc(const struct sock *sk, const int state)
{
	struct inet_timewait_sock *tw =
		kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab,
							SLAB_ATOMIC);
	if (tw != NULL) {
		const struct inet_sock *inet = inet_sk(sk);

		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;
}

void __myinet_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;

	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);

	if (__sk_del_node_init(sk))
		sock_prot_dec_use(sk->sk_prot);

	inet_twsk_add_node(tw, &(ehead + hashinfo->ehash_size)->chain);
	atomic_inc(&tw->tw_refcnt);

	write_unlock(&ehead->lock);
}

void myinet_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;
	printk(KERN_INFO "timeo: %d\n", timeo);
	slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK;
	printk(KERN_INFO "slot: %d, tick: %d, %d\n", slot, INET_TWDR_RECYCLE_TICK, HZ );
	printk(KERN_INFO "slots: %d\n", INET_TWDR_RECYCLE_SLOTS );
	spin_lock(&twdr->death_lock);

	if (inet_twsk_del_dead_node(tw))
		twdr->tw_count--;
	else
		atomic_inc(&tw->tw_refcnt);

	if (slot >= INET_TWDR_RECYCLE_SLOTS) {
		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);
			printk(KERN_INFO "twdr->twcal_hand<0, expires: %lu\n", twdr->twcal_timer.expires );
			add_timer(&twdr->twcal_timer);
		} else {
			if (time_after(twdr->twcal_timer.expires,jiffies + (slot << INET_TWDR_RECYCLE_TICK))){
				printk(KERN_INFO "else: %lu\n", 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){
		printk(KERN_INFO "last: %lu\n", jiffies + twdr->period );
		mod_timer(&twdr->tw_timer, jiffies + twdr->period);
	}
	spin_unlock(&twdr->death_lock);
}