Commit a81722dd authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: set TCP_LINGER2 locklessly 



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

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84485080

net/ipv4/tcp.c

+9 −10
Original line number Diff line number Diff line
@@ -2865,7 +2865,7 @@ void __tcp_close(struct sock *sk, long timeout) 


	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,

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/ipv4/tcp_timer.c

+1 −1
Original line number Diff line number Diff line
@@ -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) {