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authorDavid S. Miller <davem@davemloft.net>2010-08-25 02:27:49 -0700
committerDavid S. Miller <davem@davemloft.net>2010-08-25 02:27:49 -0700
commitad1af0fedba14f82b240a03fe20eb9b2fdbd0357 (patch)
tree4d53aa8bc2d9df782aa792e52670ab55c7a44d5b /net
parentb2bc85631e72485b984bcd202a104591874babba (diff)
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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>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp.c5
-rw-r--r--net/ipv4/tcp_timer.c8
2 files changed, 5 insertions, 8 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 176e11aaea7..197b9b77fa3 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 808bb920c9f..c35b469e851 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");