From: Eric Dumazet Date: Fri, 19 Sep 2025 20:48:56 +0000 (+0000) Subject: tcp: reclaim 8 bytes in struct request_sock_queue X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=649091ef597bb7de34dd8ceea39bbc4252970558;p=users%2Fhch%2Fmisc.git tcp: reclaim 8 bytes in struct request_sock_queue synflood_warned had to be u32 for xchg(), but ensuring atomicity is not really needed. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250919204856.2977245-9-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/include/net/request_sock.h b/include/net/request_sock.h index 6a5ec1418e85..cd4d4cf71d0d 100644 --- a/include/net/request_sock.h +++ b/include/net/request_sock.h @@ -185,8 +185,8 @@ struct fastopen_queue { struct request_sock_queue { spinlock_t rskq_lock; u8 rskq_defer_accept; + u8 synflood_warned; - u32 synflood_warned; atomic_t qlen; atomic_t young; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f93d48d98d5d..79d5252ed6cc 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -7282,8 +7282,8 @@ static bool tcp_syn_flood_action(struct sock *sk, const char *proto) #endif __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP); - if (!READ_ONCE(queue->synflood_warned) && syncookies != 2 && - xchg(&queue->synflood_warned, 1) == 0) { + if (syncookies != 2 && !READ_ONCE(queue->synflood_warned)) { + WRITE_ONCE(queue->synflood_warned, 1); if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) { net_info_ratelimited("%s: Possible SYN flooding on port [%pI6c]:%u. %s.\n", proto, inet6_rcv_saddr(sk),