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syncookies: remove last_synq_overflow from struct tcp_sock

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last_synq_overflow eats 4 or 8 bytes in struct tcp_sock, even
though it is only used when a listening sockets syn queue
is full.

We can (ab)use rx_opt.ts_recent_stamp to store the same information;
it is not used otherwise as long as a socket is in listen state.

Move linger2 around to avoid splitting struct mtu_probe
across cacheline boundary on 32 bit arches.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2009-04-19 09:43:48 +00:00 committed by David S. Miller
parent 7eebb0b28f
commit a0f82f64e2
4 changed files with 18 additions and 8 deletions
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4
include/linux/tcp.h
View File

@ -377,7 +377,7 @@ struct tcp_sock {
unsigned int keepalive_time; /* time before keep alive takes place */
unsigned int keepalive_intvl; /* time interval between keep alive probes */
unsigned long last_synq_overflow;
int linger2;
/* Receiver side RTT estimation */
struct {
@ -406,8 +406,6 @@ struct tcp_sock {
/* TCP MD5 Signagure Option information */
struct tcp_md5sig_info *md5sig_info;
#endif
int linger2;
};
static inline struct tcp_sock *tcp_sk(const struct sock *sk)

13
include/net/tcp.h
View File

@ -265,6 +265,19 @@ static inline int tcp_too_many_orphans(struct sock *sk, int num)
atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2]);
}
/* syncookies: remember time of last synqueue overflow */
static inline void tcp_synq_overflow(struct sock *sk)
{
tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
}
/* syncookies: no recent synqueue overflow on this listening socket? */
static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
{
unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
return time_after(jiffies, last_overflow + TCP_TIMEOUT_INIT);
}
extern struct proto tcp_prot;
#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)

5
net/ipv4/syncookies.c
View File

@ -161,13 +161,12 @@ static __u16 const msstab[] = {
*/
__u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
{
struct tcp_sock *tp = tcp_sk(sk);
const struct iphdr *iph = ip_hdr(skb);
const struct tcphdr *th = tcp_hdr(skb);
int mssind;
const __u16 mss = *mssp;
tp->last_synq_overflow = jiffies;
tcp_synq_overflow(sk);
/* XXX sort msstab[] by probability? Binary search? */
for (mssind = 0; mss > msstab[mssind + 1]; mssind++)
@ -268,7 +267,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) ||
if (tcp_synq_no_recent_overflow(sk) ||
(mss = cookie_check(skb, cookie)) == 0) {
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
goto out;

4
net/ipv6/syncookies.c
View File

@ -131,7 +131,7 @@ __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
int mssind;
const __u16 mss = *mssp;
tcp_sk(sk)->last_synq_overflow = jiffies;
tcp_synq_overflow(sk);
for (mssind = 0; mss > msstab[mssind + 1]; mssind++)
;
@ -175,7 +175,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) ||
if (tcp_synq_no_recent_overflow(sk) ||
(mss = cookie_check(skb, cookie)) == 0) {
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
goto out;