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Commit 2985aaac authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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tcp: constify tcp_syn_flood_action() socket argument 



tcp_syn_flood_action() will soon be called with unlocked socket.
In order to avoid SYN flood warning being emitted multiple times,
use xchg().
Extend max_qlen_log and synflood_warned fields in struct listen_sock
to u32

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f964629e

include/net/request_sock.h

+2 −3
Original line number Diff line number Diff line
@@ -129,9 +129,8 @@ struct listen_sock { 
	atomic_t		qlen_dec; /* qlen = qlen_inc - qlen_dec */

	atomic_t		young_dec;



	u8			max_qlen_log ____cacheline_aligned_in_smp;

	u8			synflood_warned;

	/* 2 bytes hole, try to use */

	u32			max_qlen_log ____cacheline_aligned_in_smp;

	u32			synflood_warned;

	u32			hash_rnd;

	u32			nr_table_entries;

	struct request_sock	*syn_table[0];

net/ipv4/tcp_input.c

+5 −4
Original line number Diff line number Diff line
@@ -6064,7 +6064,7 @@ EXPORT_SYMBOL(inet_reqsk_alloc); 
/*

 * Return true if a syncookie should be sent

 */

static bool tcp_syn_flood_action(struct sock *sk,

static bool tcp_syn_flood_action(const struct sock *sk,

				 const struct sk_buff *skb,

				 const char *proto)

{
@@ -6082,11 +6082,12 @@ static bool tcp_syn_flood_action(struct sock *sk, 
		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);



	lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;

	if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) {

		lopt->synflood_warned = 1;

	if (!lopt->synflood_warned &&

	    sysctl_tcp_syncookies != 2 &&

	    xchg(&lopt->synflood_warned, 1) == 0)

		pr_info("%s: Possible SYN flooding on port %d. %s.  Check SNMP counters.\n",

			proto, ntohs(tcp_hdr(skb)->dest), msg);

	}



	return want_cookie;

}