tcp: move duplicate code from tcp_v4_init_sock()/tcp_v6_init_sock()
This commit moves the (substantial) common code shared between
tcp_v4_init_sock() and tcp_v6_init_sock() to a new address-family
independent function, tcp_init_sock().
Centralizing this functionality should help avoid drift issues,
e.g. where the IPv4 side is updated without a corresponding update to
IPv6. There was already some drift: IPv4 initialized snd_cwnd to
TCP_INIT_CWND, while the IPv6 side was still initializing snd_cwnd to
2 (in this case it should not matter, since snd_cwnd is also
initialized in tcp_init_metrics(), but the general risks and
maintenance overhead remain).
When diffing the old and new code, note that new tcp_init_sock()
function uses the order of steps from the tcp_v4_init_sock()
implementation (the order is slightly different in
tcp_v6_init_sock()).
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3ce3bd0..bcc4eab 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -363,6 +363,70 @@
return period;
}
+/* Address-family independent initialization for a tcp_sock.
+ *
+ * NOTE: A lot of things set to zero explicitly by call to
+ * sk_alloc() so need not be done here.
+ */
+void tcp_init_sock(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ skb_queue_head_init(&tp->out_of_order_queue);
+ tcp_init_xmit_timers(sk);
+ tcp_prequeue_init(tp);
+
+ icsk->icsk_rto = TCP_TIMEOUT_INIT;
+ tp->mdev = TCP_TIMEOUT_INIT;
+
+ /* So many TCP implementations out there (incorrectly) count the
+ * initial SYN frame in their delayed-ACK and congestion control
+ * algorithms that we must have the following bandaid to talk
+ * efficiently to them. -DaveM
+ */
+ tp->snd_cwnd = TCP_INIT_CWND;
+
+ /* See draft-stevens-tcpca-spec-01 for discussion of the
+ * initialization of these values.
+ */
+ tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
+ tp->snd_cwnd_clamp = ~0;
+ tp->mss_cache = TCP_MSS_DEFAULT;
+
+ tp->reordering = sysctl_tcp_reordering;
+ icsk->icsk_ca_ops = &tcp_init_congestion_ops;
+
+ sk->sk_state = TCP_CLOSE;
+
+ sk->sk_write_space = sk_stream_write_space;
+ sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+
+ icsk->icsk_sync_mss = tcp_sync_mss;
+
+ /* TCP Cookie Transactions */
+ if (sysctl_tcp_cookie_size > 0) {
+ /* Default, cookies without s_data_payload. */
+ tp->cookie_values =
+ kzalloc(sizeof(*tp->cookie_values),
+ sk->sk_allocation);
+ if (tp->cookie_values != NULL)
+ kref_init(&tp->cookie_values->kref);
+ }
+ /* Presumed zeroed, in order of appearance:
+ * cookie_in_always, cookie_out_never,
+ * s_data_constant, s_data_in, s_data_out
+ */
+ sk->sk_sndbuf = sysctl_tcp_wmem[1];
+ sk->sk_rcvbuf = sysctl_tcp_rmem[1];
+
+ local_bh_disable();
+ sock_update_memcg(sk);
+ sk_sockets_allocated_inc(sk);
+ local_bh_enable();
+}
+EXPORT_SYMBOL(tcp_init_sock);
+
/*
* Wait for a TCP event.
*
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ba6dad8..5b07ea1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1890,62 +1890,14 @@
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
- skb_queue_head_init(&tp->out_of_order_queue);
- tcp_init_xmit_timers(sk);
- tcp_prequeue_init(tp);
-
- icsk->icsk_rto = TCP_TIMEOUT_INIT;
- tp->mdev = TCP_TIMEOUT_INIT;
-
- /* So many TCP implementations out there (incorrectly) count the
- * initial SYN frame in their delayed-ACK and congestion control
- * algorithms that we must have the following bandaid to talk
- * efficiently to them. -DaveM
- */
- tp->snd_cwnd = TCP_INIT_CWND;
-
- /* See draft-stevens-tcpca-spec-01 for discussion of the
- * initialization of these values.
- */
- tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
- tp->snd_cwnd_clamp = ~0;
- tp->mss_cache = TCP_MSS_DEFAULT;
-
- tp->reordering = sysctl_tcp_reordering;
- icsk->icsk_ca_ops = &tcp_init_congestion_ops;
-
- sk->sk_state = TCP_CLOSE;
-
- sk->sk_write_space = sk_stream_write_space;
- sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+ tcp_init_sock(sk);
icsk->icsk_af_ops = &ipv4_specific;
- icsk->icsk_sync_mss = tcp_sync_mss;
+
#ifdef CONFIG_TCP_MD5SIG
tp->af_specific = &tcp_sock_ipv4_specific;
#endif
- /* TCP Cookie Transactions */
- if (sysctl_tcp_cookie_size > 0) {
- /* Default, cookies without s_data_payload. */
- tp->cookie_values =
- kzalloc(sizeof(*tp->cookie_values),
- sk->sk_allocation);
- if (tp->cookie_values != NULL)
- kref_init(&tp->cookie_values->kref);
- }
- /* Presumed zeroed, in order of appearance:
- * cookie_in_always, cookie_out_never,
- * s_data_constant, s_data_in, s_data_out
- */
- sk->sk_sndbuf = sysctl_tcp_wmem[1];
- sk->sk_rcvbuf = sysctl_tcp_rmem[1];
-
- local_bh_disable();
- sock_update_memcg(sk);
- sk_sockets_allocated_inc(sk);
- local_bh_enable();
-
return 0;
}