Commit 8804b272 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

tcp: remove false sharing in tcp_rcv_state_process()

Last known hot point during SYNFLOOD attack is the clearing
of rx_opt.saw_tstamp in tcp_rcv_state_process()

It is not needed for a listener, so we move it where it matters.

Performance while a SYNFLOOD hits a single listener socket
went from 5 Mpps to 6 Mpps on my test server (24 cores, 8 NIC RX queues)
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b3d05147
...@@ -5796,8 +5796,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) ...@@ -5796,8 +5796,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
int queued = 0; int queued = 0;
bool acceptable; bool acceptable;
tp->rx_opt.saw_tstamp = 0;
switch (sk->sk_state) { switch (sk->sk_state) {
case TCP_CLOSE: case TCP_CLOSE:
goto discard; goto discard;
...@@ -5838,6 +5836,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) ...@@ -5838,6 +5836,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
goto discard; goto discard;
case TCP_SYN_SENT: case TCP_SYN_SENT:
tp->rx_opt.saw_tstamp = 0;
queued = tcp_rcv_synsent_state_process(sk, skb, th); queued = tcp_rcv_synsent_state_process(sk, skb, th);
if (queued >= 0) if (queued >= 0)
return queued; return queued;
...@@ -5849,6 +5848,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) ...@@ -5849,6 +5848,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
return 0; return 0;
} }
tp->rx_opt.saw_tstamp = 0;
req = tp->fastopen_rsk; req = tp->fastopen_rsk;
if (req) { if (req) {
WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV && WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
......
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