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@@ -109,7 +109,6 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
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tw->tw_tb = icsk->icsk_bind_hash;
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WARN_ON(!icsk->icsk_bind_hash);
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inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
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- atomic_inc(&tw->tw_refcnt);
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spin_unlock(&bhead->lock);
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spin_lock(lock);
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@@ -119,13 +118,22 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
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* Should be done before removing sk from established chain
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* because readers are lockless and search established first.
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*/
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- atomic_inc(&tw->tw_refcnt);
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inet_twsk_add_node_rcu(tw, &ehead->twchain);
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/* Step 3: Remove SK from established hash. */
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if (__sk_nulls_del_node_init_rcu(sk))
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sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
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+ /*
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+ * Notes :
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+ * - We initially set tw_refcnt to 0 in inet_twsk_alloc()
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+ * - We add one reference for the bhash link
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+ * - We add one reference for the ehash link
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+ * - We want this refcnt update done before allowing other
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+ * threads to find this tw in ehash chain.
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+ */
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+ atomic_add(1 + 1 + 1, &tw->tw_refcnt);
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+
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spin_unlock(lock);
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}
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@@ -157,7 +165,12 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int stat
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tw->tw_transparent = inet->transparent;
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tw->tw_prot = sk->sk_prot_creator;
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twsk_net_set(tw, hold_net(sock_net(sk)));
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- atomic_set(&tw->tw_refcnt, 1);
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+ /*
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+ * Because we use RCU lookups, we should not set tw_refcnt
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+ * to a non null value before everything is setup for this
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+ * timewait socket.
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+ */
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+ atomic_set(&tw->tw_refcnt, 0);
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inet_twsk_dead_node_init(tw);
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__module_get(tw->tw_prot->owner);
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}
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