[et-mgmt-tools] Re: virt-manager broken by bind(0) in net-next.
Stephen Hemminger
shemminger at vyatta.com
Sun Feb 1 05:29:09 UTC 2009
On Fri, 30 Jan 2009 19:41:59 +0100
Eric Dumazet <dada1 at cosmosbay.com> wrote:
> Stephen Hemminger a écrit :
> > On Fri, 30 Jan 2009 23:53:37 +1100
> > Herbert Xu <herbert at gondor.apana.org.au> wrote:
> >
> >> Evgeniy Polyakov <zbr at ioremap.net> wrote:
> >>> So it is not explicit bind call, but port autoselection in the
> >>> connect(). Can you check what errno is returned?
> >>> Did I understand it right, that connect fails, you try different
> >>> address, but then suddenly all those sockets become 'alive'?
> >> Yes, I think a good strace vs. a bad strace would be really helpful
> >> in these cases.
> >>
> >> Thanks,
> >
> > I have the strace but it comes up no different.
> > What is different is that in the broken case (net-next), I see
> > IPV6 being used:
> >
> > State Recv-Q Send-Q Local Address:Port Peer Address:Port
> > ESTAB 23769 0 ::ffff:127.0.0.1:5900 ::ffff:127.0.0.1:55987
> > ESTAB 0 0 127.0.0.1:55987 127.0.0.1:5900
> >
> > and in the working case (2.6.29-rc3), IPV4 is being used
> > State Recv-Q Send-Q Local Address:Port Peer Address:Port
> > ESTAB 0 0 127.0.0.1:58894 127.0.0.1:5901
> > ESTAB 0 0 127.0.0.1:5901 127.0.0.1:58894
> >
>
> Reviewing commit a9d8f9110d7e953c2f2b521087a4179677843c2a
>
> I see use of a hashinfo->bsockets field that :
>
> - lacks proper lock/synchronization
> - suffers from cache line ping pongs on SMP
>
> Also there might be a problem at line 175
>
> if (sk->sk_reuse && sk->sk_state != TCP_LISTEN && --attempts >= 0) {
> spin_unlock(&head->lock);
> goto again;
>
> If we entered inet_csk_get_port() with a non null snum, we can "goto again"
> while it was not expected.
>
> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> index df8e72f..752c6b2 100644
> --- a/net/ipv4/inet_connection_sock.c
> +++ b/net/ipv4/inet_connection_sock.c
> @@ -172,7 +172,8 @@ tb_found:
> } else {
> ret = 1;
> if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
> - if (sk->sk_reuse && sk->sk_state != TCP_LISTEN && --attempts >= 0) {
> + if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
> + smallest_size == -1 && --attempts >= 0) {
> spin_unlock(&head->lock);
> goto again;
> }
>
>
That didn't fix it.
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