diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-10-02 11:43:39 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-10-03 04:32:46 -0700 |
| commit | e994b2f0fb9229aeff5eea9541320bd7b2ca8714 (patch) | |
| tree | 0caf05649d27830ba0f9548704abbb1ec4b5bb91 /net/ipv4 | |
| parent | 92d6f176fdcce1a9c22a59d754c924168fdf2ce4 (diff) | |
tcp: do not lock listener to process SYN packets
Everything should now be ready to finally allow SYN
packets processing without holding listener lock.
Tested:
3.5 Mpps SYNFLOOD. Plenty of cpu cycles available.
Next bottleneck is the refcount taken on listener,
that could be avoided if we remove SLAB_DESTROY_BY_RCU
strict semantic for listeners, and use regular RCU.
13.18% [kernel] [k] __inet_lookup_listener
9.61% [kernel] [k] tcp_conn_request
8.16% [kernel] [k] sha_transform
5.30% [kernel] [k] inet_reqsk_alloc
4.22% [kernel] [k] sock_put
3.74% [kernel] [k] tcp_make_synack
2.88% [kernel] [k] ipt_do_table
2.56% [kernel] [k] memcpy_erms
2.53% [kernel] [k] sock_wfree
2.40% [kernel] [k] tcp_v4_rcv
2.08% [kernel] [k] fib_table_lookup
1.84% [kernel] [k] tcp_openreq_init_rwin
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index ac2ea73e9aaf..34310748a365 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1355,7 +1355,7 @@ static struct sock *tcp_v4_cookie_check(struct sock *sk, struct sk_buff *skb) } /* The socket must have it's spinlock held when we get - * here. + * here, unless it is a TCP_LISTEN socket. * * We have a potential double-lock case here, so even when * doing backlog processing we use the BH locking scheme. @@ -1619,9 +1619,15 @@ process: if (sk_filter(sk, skb)) goto discard_and_relse; - sk_incoming_cpu_update(sk); skb->dev = NULL; + if (sk->sk_state == TCP_LISTEN) { + ret = tcp_v4_do_rcv(sk, skb); + goto put_and_return; + } + + sk_incoming_cpu_update(sk); + bh_lock_sock_nested(sk); tcp_sk(sk)->segs_in += max_t(u16, 1, skb_shinfo(skb)->gso_segs); ret = 0; @@ -1636,6 +1642,7 @@ process: } bh_unlock_sock(sk); +put_and_return: sock_put(sk); return ret; |