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tcp: constify tcp_syn_flood_action() socket argument

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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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-09-29 07:42:51 -07:00 committed by David S. Miller
parent f964629e33
commit 2985aaac01
2 changed files with 7 additions and 7 deletions
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5
include/net/request_sock.h
View file

@ -129,9 +129,8 @@ struct listen_sock {
atomic_t qlen_dec; /* qlen = qlen_inc - qlen_dec */ atomic_t qlen_dec; /* qlen = qlen_inc - qlen_dec */
atomic_t young_dec; atomic_t young_dec;
u8 max_qlen_log ____cacheline_aligned_in_smp; u32 max_qlen_log ____cacheline_aligned_in_smp;
u8 synflood_warned; u32 synflood_warned;
/* 2 bytes hole, try to use */
u32 hash_rnd; u32 hash_rnd;
u32 nr_table_entries; u32 nr_table_entries;
struct request_sock *syn_table[0]; struct request_sock *syn_table[0];

9
net/ipv4/tcp_input.c
View file

@ -6064,7 +6064,7 @@ EXPORT_SYMBOL(inet_reqsk_alloc);
/* /*
* Return true if a syncookie should be sent * 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 struct sk_buff *skb,
const char *proto) 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); NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
lopt = inet_csk(sk)->icsk_accept_queue.listen_opt; lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) { if (!lopt->synflood_warned &&
lopt->synflood_warned = 1; sysctl_tcp_syncookies != 2 &&
xchg(&lopt->synflood_warned, 1) == 0)
pr_info("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n", pr_info("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n",
proto, ntohs(tcp_hdr(skb)->dest), msg); proto, ntohs(tcp_hdr(skb)->dest), msg);
}
return want_cookie; return want_cookie;
} }