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/include/net/tcp.h b/include/net/tcp.h
index b4ccb8a6c9c1ff27157aa67597527a6affe11ba0..fc880e92164ac0f14aa6bc9ae3e156ef8ba0193b 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -395,6 +395,7 @@ extern void tcp_enter_loss(struct sock *sk, int how);
 extern void tcp_clear_retrans(struct tcp_sock *tp);
 extern void tcp_update_metrics(struct sock *sk);
 extern void tcp_close(struct sock *sk, long timeout);
+extern void tcp_init_sock(struct sock *sk);
 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
                             struct poll_table_struct *wait);
 extern int tcp_getsockopt(struct sock *sk, int level, int optname,

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3ce3bd031f33cd87cd730e3617248638a02e8aea..bcc4eab5f25148a2ae4da093732b48b38aad18b3 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -363,6 +363,70 @@ static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
        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 ba6dad81908eea1b5d7a7e6ddce648cd3c907d2c..5b07ea109300d4b9159b5c90878f3e26ddbe09e0 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1890,62 +1890,14 @@ static int tcp_v4_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);
+       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;
 }
 

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 050c55186bc434f07e8451756218b67404eea042..24dac6b83fb9f451545b3849716ba3fb5f894e31 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1831,62 +1831,14 @@ static int tcp_v6_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 = 2;
-
-       /* 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;
-
-       sk->sk_state = TCP_CLOSE;
+       tcp_init_sock(sk);
 
        icsk->icsk_af_ops = &ipv6_specific;
-       icsk->icsk_ca_ops = &tcp_init_congestion_ops;
-       icsk->icsk_sync_mss = tcp_sync_mss;
-       sk->sk_write_space = sk_stream_write_space;
-       sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
 
 #ifdef CONFIG_TCP_MD5SIG
        tp->af_specific = &tcp_sock_ipv6_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;
 }