- spin_lock(&tw_death_lock);
- if (tw_del_dead_node(tw)) {
- tcp_tw_put(tw);
- if (--tcp_tw_count == 0)
- del_timer(&tcp_tw_timer);
- }
- spin_unlock(&tw_death_lock);
- tcp_timewait_kill(tw);
-}
-
-/* Short-time timewait calendar */
-
-static int tcp_twcal_hand = -1;
-static int tcp_twcal_jiffie;
-static void tcp_twcal_tick(unsigned long);
-static struct timer_list tcp_twcal_timer =
- TIMER_INITIALIZER(tcp_twcal_tick, 0, 0);
-static struct hlist_head tcp_twcal_row[TCP_TW_RECYCLE_SLOTS];
-
-void tcp_tw_schedule(struct tcp_tw_bucket *tw, int timeo)
-{
- 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<<TCP_TW_RECYCLE_TICK) - 1) >> TCP_TW_RECYCLE_TICK;
-
- spin_lock(&tw_death_lock);
-
- /* Unlink it, if it was scheduled */
- if (tw_del_dead_node(tw))
- tcp_tw_count--;
- else
- atomic_inc(&tw->tw_refcnt);
-
- if (slot >= TCP_TW_RECYCLE_SLOTS) {
- /* Schedule to slow timer */
- if (timeo >= TCP_TIMEWAIT_LEN) {
- slot = TCP_TWKILL_SLOTS-1;
- } else {
- slot = (timeo + TCP_TWKILL_PERIOD-1) / TCP_TWKILL_PERIOD;
- if (slot >= TCP_TWKILL_SLOTS)
- slot = TCP_TWKILL_SLOTS-1;
- }
- tw->tw_ttd = jiffies + timeo;
- slot = (tcp_tw_death_row_slot + slot) & (TCP_TWKILL_SLOTS - 1);
- list = &tcp_tw_death_row[slot];
- } else {
- tw->tw_ttd = jiffies + (slot << TCP_TW_RECYCLE_TICK);
-
- if (tcp_twcal_hand < 0) {
- tcp_twcal_hand = 0;
- tcp_twcal_jiffie = jiffies;
- tcp_twcal_timer.expires = tcp_twcal_jiffie + (slot<<TCP_TW_RECYCLE_TICK);
- add_timer(&tcp_twcal_timer);
- } else {
- if (time_after(tcp_twcal_timer.expires, jiffies + (slot<<TCP_TW_RECYCLE_TICK)))
- mod_timer(&tcp_twcal_timer, jiffies + (slot<<TCP_TW_RECYCLE_TICK));
- slot = (tcp_twcal_hand + slot)&(TCP_TW_RECYCLE_SLOTS-1);
- }
- list = &tcp_twcal_row[slot];
- }
-
- hlist_add_head(&tw->tw_death_node, list);
-
- if (tcp_tw_count++ == 0)
- mod_timer(&tcp_tw_timer, jiffies+TCP_TWKILL_PERIOD);
- spin_unlock(&tw_death_lock);