From ad1af0fedba14f82b240a03fe20eb9b2fdbd0357 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 25 Aug 2010 02:27:49 -0700 Subject: tcp: Combat per-cpu skew in orphan tests. As reported by Anton Blanchard when we use percpu_counter_read_positive() to make our orphan socket limit checks, the check can be off by up to num_cpus_online() * batch (which is 32 by default) which on a 128 cpu machine can be as large as the default orphan limit itself. Fix this by doing the full expensive sum check if the optimized check triggers. Reported-by: Anton Blanchard Signed-off-by: David S. Miller Acked-by: Eric Dumazet --- net/ipv4/tcp_timer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/ipv4/tcp_timer.c') diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 808bb920c9f5..c35b469e851c 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -66,18 +66,18 @@ static void tcp_write_err(struct sock *sk) static int tcp_out_of_resources(struct sock *sk, int do_reset) { struct tcp_sock *tp = tcp_sk(sk); - int orphans = percpu_counter_read_positive(&tcp_orphan_count); + int shift = 0; /* If peer does not open window for long time, or did not transmit * anything for long time, penalize it. */ if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) - orphans <<= 1; + shift++; /* If some dubious ICMP arrived, penalize even more. */ if (sk->sk_err_soft) - orphans <<= 1; + shift++; - if (tcp_too_many_orphans(sk, orphans)) { + if (tcp_too_many_orphans(sk, shift)) { if (net_ratelimit()) printk(KERN_INFO "Out of socket memory\n"); -- cgit v1.2.3