Re: [2.6.34-rc1] CPU stalls when closing TCP sockets.
From: Tetsuo Handa
Date: Tue Mar 09 2010 - 16:44:17 EST
Hello.
Eric Dumazet wrote:
> Le mardi 09 mars 2010 a 15:54 +0900, Tetsuo Handa a ecrit :
> > Eric Dumazet wrote:
> > > Nothing comes to my mind, I'll try to reproduce this here.
> >
> > When stopped at (8), Ctrl-C doesn't work.
> >
> > > Is 2.6.33 OK ?
> >
> > Yes. 2.6.33 and earlier are OK.
>
> OK thanks !
>
> I believe commit d218d11133d888f9745802146a50255a4781d37a
> (tcp: Generalized TTL Security Mechanism) might be the bug origin.
Yes. "git bisect" reported that
d218d11133d888f9745802146a50255a4781d37a is first bad commit.
Your patch (although I needed to change like below in order to
apply on linux-2.6.34-rc1) fixes the CPU stalls.
Thank you.
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index c3588b4..3f8d08f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1651,13 +1651,13 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (!sk)
goto no_tcp_socket;
- if (iph->ttl < inet_sk(sk)->min_ttl)
- goto discard_and_relse;
-
process:
if (sk->sk_state == TCP_TIME_WAIT)
goto do_time_wait;
+ if (iph->ttl < inet_sk(sk)->min_ttl)
+ goto discard_and_relse;
+
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_and_relse;
nf_reset(skb);
--
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