tcp: set TCP_LINGER2 locklessly

tp->linger2 can be set locklessly as long as readers
use READ_ONCE().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e74a959..5c71b4f 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2865,7 +2865,7 @@ adjudge_to_death:
 
        if (sk->sk_state == TCP_FIN_WAIT2) {
                struct tcp_sock *tp = tcp_sk(sk);
-               if (tp->linger2 < 0) {
+               if (READ_ONCE(tp->linger2) < 0) {
                        tcp_set_state(sk, TCP_CLOSE);
                        tcp_send_active_reset(sk, GFP_ATOMIC);
                        __NET_INC_STATS(sock_net(sk),
@@ -3471,6 +3471,14 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
                return tcp_sock_set_keepintvl(sk, val);
        case TCP_KEEPCNT:
                return tcp_sock_set_keepcnt(sk, val);
+       case TCP_LINGER2:
+               if (val < 0)
+                       WRITE_ONCE(tp->linger2, -1);
+               else if (val > TCP_FIN_TIMEOUT_MAX / HZ)
+                       WRITE_ONCE(tp->linger2, TCP_FIN_TIMEOUT_MAX);
+               else
+                       WRITE_ONCE(tp->linger2, val * HZ);
+               return 0;
        }
 
        sockopt_lock_sock(sk);
@@ -3576,15 +3584,6 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
                        tp->save_syn = val;
                break;
 
-       case TCP_LINGER2:
-               if (val < 0)
-                       WRITE_ONCE(tp->linger2, -1);
-               else if (val > TCP_FIN_TIMEOUT_MAX / HZ)
-                       WRITE_ONCE(tp->linger2, TCP_FIN_TIMEOUT_MAX);
-               else
-                       WRITE_ONCE(tp->linger2, val * HZ);
-               break;
-
        case TCP_DEFER_ACCEPT:
                /* Translate value in seconds to number of retransmits */
                WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2995802..deac708 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6624,7 +6624,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
                        break;
                }
 
-               if (tp->linger2 < 0) {
+               if (READ_ONCE(tp->linger2) < 0) {
                        tcp_done(sk);
                        NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
                        return 1;

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index f99e2d0..d45c96c 100644 (file)
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -714,7 +714,7 @@ static void tcp_keepalive_timer (struct timer_list *t)
 
        tcp_mstamp_refresh(tp);
        if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
-               if (tp->linger2 >= 0) {
+               if (READ_ONCE(tp->linger2) >= 0) {
                        const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN;
 
                        if (tmo > 0) {