#include <net/inet_timewait_sock.h>
#include <net/ip.h>
+
+/*
+ * unhash a timewait socket from established hash
+ * lock must be hold by caller
+ */
+int inet_twsk_unhash(struct inet_timewait_sock *tw)
+{
+ if (hlist_nulls_unhashed(&tw->tw_node))
+ return 0;
+
+ hlist_nulls_del_rcu(&tw->tw_node);
+ sk_nulls_node_init(&tw->tw_node);
+ return 1;
+}
+
+/*
+ * unhash a timewait socket from bind hash
+ * lock must be hold by caller
+ */
+int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
+ struct inet_hashinfo *hashinfo)
+{
+ struct inet_bind_bucket *tb = tw->tw_tb;
+
+ if (!tb)
+ return 0;
+
+ __hlist_del(&tw->tw_bind_node);
+ tw->tw_tb = NULL;
+ inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+ return 1;
+}
+
/* Must be called with locally disabled BHs. */
static void __inet_twsk_kill(struct inet_timewait_sock *tw,
struct inet_hashinfo *hashinfo)
{
struct inet_bind_hashbucket *bhead;
- struct inet_bind_bucket *tb;
+ int refcnt;
/* Unlink from established hashes. */
spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
spin_lock(lock);
- if (hlist_nulls_unhashed(&tw->tw_node)) {
- spin_unlock(lock);
- return;
- }
- hlist_nulls_del_rcu(&tw->tw_node);
- sk_nulls_node_init(&tw->tw_node);
+ refcnt = inet_twsk_unhash(tw);
spin_unlock(lock);
/* Disassociate with bind bucket. */
bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), 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);
+ refcnt += inet_twsk_bind_unhash(tw, hashinfo);
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);
+ while (refcnt) {
+ inet_twsk_put(tw);
+ refcnt--;
+ }
}
static noinline void inet_twsk_free(struct inet_timewait_sock *tw)
* Should be done before removing sk from established chain
* because readers are lockless and search established first.
*/
- atomic_inc(&tw->tw_refcnt);
inet_twsk_add_node_rcu(tw, &ehead->twchain);
/* Step 3: Remove SK from established hash. */
if (__sk_nulls_del_node_init_rcu(sk))
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+ /*
+ * Notes :
+ * - We initially set tw_refcnt to 0 in inet_twsk_alloc()
+ * - We add one reference for the bhash link
+ * - We add one reference for the ehash link
+ * - We want this refcnt update done before allowing other
+ * threads to find this tw in ehash chain.
+ */
+ atomic_add(1 + 1 + 1, &tw->tw_refcnt);
+
spin_unlock(lock);
}
tw->tw_transparent = inet->transparent;
tw->tw_prot = sk->sk_prot_creator;
twsk_net_set(tw, hold_net(sock_net(sk)));
- atomic_set(&tw->tw_refcnt, 1);
+ /*
+ * Because we use RCU lookups, we should not set tw_refcnt
+ * to a non null value before everything is setup for this
+ * timewait socket.
+ */
+ atomic_set(&tw->tw_refcnt, 0);
inet_twsk_dead_node_init(tw);
__module_get(tw->tw_prot->owner);
}
EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick);
-void inet_twsk_purge(struct net *net, struct inet_hashinfo *hashinfo,
+void inet_twsk_purge(struct inet_hashinfo *hashinfo,
struct inet_timewait_death_row *twdr, int family)
{
struct inet_timewait_sock *tw;
struct sock *sk;
struct hlist_nulls_node *node;
- int h;
+ unsigned int slot;
- local_bh_disable();
- for (h = 0; h <= hashinfo->ehash_mask; h++) {
- struct inet_ehash_bucket *head =
- inet_ehash_bucket(hashinfo, h);
- spinlock_t *lock = inet_ehash_lockp(hashinfo, h);
+ for (slot = 0; slot <= hashinfo->ehash_mask; slot++) {
+ struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
+restart_rcu:
+ rcu_read_lock();
restart:
- spin_lock(lock);
- sk_nulls_for_each(sk, node, &head->twchain) {
-
+ sk_nulls_for_each_rcu(sk, node, &head->twchain) {
tw = inet_twsk(sk);
- if (!net_eq(twsk_net(tw), net) ||
- tw->tw_family != family)
+ if ((tw->tw_family != family) ||
+ atomic_read(&twsk_net(tw)->count))
+ continue;
+
+ if (unlikely(!atomic_inc_not_zero(&tw->tw_refcnt)))
continue;
- atomic_inc(&tw->tw_refcnt);
- spin_unlock(lock);
+ if (unlikely((tw->tw_family != family) ||
+ atomic_read(&twsk_net(tw)->count))) {
+ inet_twsk_put(tw);
+ goto restart;
+ }
+
+ rcu_read_unlock();
inet_twsk_deschedule(tw, twdr);
inet_twsk_put(tw);
-
- goto restart;
+ goto restart_rcu;
}
- spin_unlock(lock);
+ /* If the nulls value we got at the end of this lookup is
+ * not the expected one, we must restart lookup.
+ * We probably met an item that was moved to another chain.
+ */
+ if (get_nulls_value(node) != slot)
+ goto restart;
+ rcu_read_unlock();
}
- local_bh_enable();
}
EXPORT_SYMBOL_GPL(inet_twsk_purge);
projects / deliverable / linux.git / blobdiff