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tcp: set TCP_DEFER_ACCEPT locklessly

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rskq_defer_accept field can be read/written without
the need of holding the socket lock.

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>
This commit is contained in:
Eric Dumazet 2023-08-04 14:46:16 +00:00 committed by David S. Miller
parent a81722ddd7
commit 6e97ba552b
3 changed files with 8 additions and 9 deletions
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13
net/ipv4/tcp.c
View File

@ -3479,6 +3479,12 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
else
WRITE_ONCE(tp->linger2, val * HZ);
return 0;
case TCP_DEFER_ACCEPT:
/* Translate value in seconds to number of retransmits */
WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,
secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
TCP_RTO_MAX / HZ));
return 0;
}
sockopt_lock_sock(sk);
@ -3584,13 +3590,6 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
tp->save_syn = val;
break;
case TCP_DEFER_ACCEPT:
/* Translate value in seconds to number of retransmits */
WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,
secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
TCP_RTO_MAX / HZ));
break;
case TCP_WINDOW_CLAMP:
err = tcp_set_window_clamp(sk, val);
break;

2
net/ipv4/tcp_input.c
View File

@ -6324,7 +6324,7 @@ consume:
if (fastopen_fail)
return -1;
if (sk->sk_write_pending ||
icsk->icsk_accept_queue.rskq_defer_accept ||
READ_ONCE(icsk->icsk_accept_queue.rskq_defer_accept) ||
inet_csk_in_pingpong_mode(sk)) {
/* Save one ACK. Data will be ready after
* several ticks, if write_pending is set.

2
net/ipv4/tcp_minisocks.c
View File

@ -792,7 +792,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
return sk;
/* While TCP_DEFER_ACCEPT is active, drop bare ACK. */
if (req->num_timeout < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept &&
if (req->num_timeout < READ_ONCE(inet_csk(sk)->icsk_accept_queue.rskq_defer_accept) &&
TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {
inet_rsk(req)->acked = 1;
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP);