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| author | David S. Miller <davem@davemloft.net> | 2010-08-25 02:27:49 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-08-25 02:27:49 -0700 |
| commit | ad1af0fedba14f82b240a03fe20eb9b2fdbd0357 (patch) | |
| tree | 4d53aa8bc2d9df782aa792e52670ab55c7a44d5b | |
| parent | b2bc85631e72485b984bcd202a104591874babba (diff) | |
| download | linux-ad1af0fedba14f82b240a03fe20eb9b2fdbd0357.tar.gz linux-ad1af0fedba14f82b240a03fe20eb9b2fdbd0357.tar.bz2 linux-ad1af0fedba14f82b240a03fe20eb9b2fdbd0357.zip | |
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 <anton@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
| -rw-r--r-- | include/net/tcp.h | 18 | ||||
| -rw-r--r-- | net/ipv4/tcp.c | 5 | ||||
| -rw-r--r-- | net/ipv4/tcp_timer.c | 8 |
3 files changed, 19 insertions, 12 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index df6a2eb20193..eaa9582779d0 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -268,11 +268,21 @@ static inline int between(__u32 seq1, __u32 seq2, __u32 seq3) return seq3 - seq2 >= seq1 - seq2; } -static inline int tcp_too_many_orphans(struct sock *sk, int num) +static inline bool tcp_too_many_orphans(struct sock *sk, int shift) { - return (num > sysctl_tcp_max_orphans) || - (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && - atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2]); + struct percpu_counter *ocp = sk->sk_prot->orphan_count; + int orphans = percpu_counter_read_positive(ocp); + + if (orphans << shift > sysctl_tcp_max_orphans) { + orphans = percpu_counter_sum_positive(ocp); + if (orphans << shift > sysctl_tcp_max_orphans) + return true; + } + + if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && + atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2]) + return true; + return false; } /* syncookies: remember time of last synqueue overflow */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 176e11aaea77..197b9b77fa3e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2011,11 +2011,8 @@ adjudge_to_death: } } if (sk->sk_state != TCP_CLOSE) { - int orphan_count = percpu_counter_read_positive( - sk->sk_prot->orphan_count); - sk_mem_reclaim(sk); - if (tcp_too_many_orphans(sk, orphan_count)) { + if (tcp_too_many_orphans(sk, 0)) { if (net_ratelimit()) printk(KERN_INFO "TCP: too many of orphaned " "sockets\n"); 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"); |