aboutsummaryrefslogtreecommitdiff
path: root/net/ipv4/inet_timewait_sock.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/ipv4/inet_timewait_sock.c')
-rw-r--r--net/ipv4/inet_timewait_sock.c384
1 files changed, 384 insertions, 0 deletions
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
new file mode 100644
index 00000000000..4d1502a4985
--- /dev/null
+++ b/net/ipv4/inet_timewait_sock.c
@@ -0,0 +1,384 @@
+/*
+ * 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 = &hashinfo->ehash[tw->tw_hashent];
+
+ 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 = &hashinfo->ehash[sk->sk_hashent];
+ 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_hashent = sk->sk_hashent;
+ tw->tw_ipv6only = 0;
+ tw->tw_prot = sk->sk_prot_creator;
+ atomic_set(&tw->tw_refcnt, 1);
+ inet_twsk_dead_node_init(tw);
+ }
+
+ 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);
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-04 16:26:22 +0000