| /* |
| * 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 <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_prot->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); |
| 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(struct work_struct *work) |
| { |
| struct inet_timewait_death_row *twdr = |
| container_of(work, struct inet_timewait_death_row, twkill_work); |
| 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); |