Messages in this thread | | | Date | Wed, 4 Jun 2008 09:25:38 +0300 (EEST) | From | "Ilpo Järvinen" <> | Subject | Re: [fixed] [patch] Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+ |
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On Tue, 3 Jun 2008, Joe Perches wrote:
> On Wed, 2008-06-04 at 02:22 +0300, Ilpo Järvinen wrote: > > But here's somewhat more likely explanation... Only compile tested... > > It probably needs some commenting from people who understand locking > > variants & details (I don't). > > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > > index c9454f0..d21d2b9 100644 > > --- a/net/ipv4/tcp_input.c > > +++ b/net/ipv4/tcp_input.c > > @@ -4562,6 +4562,7 @@ static int tcp_defer_accept_check(struct sock *sk) > > struct tcp_sock *tp = tcp_sk(sk); > > > > if (tp->defer_tcp_accept.request) { > > + struct sock *listen_sk = tp->defer_tcp_accept.listen_sk; > > Not commenting on the locking, but I think the code > would be clearer if tp->defer_tcp_accept was used in > a temporary instead.
Only fixes to net-2.6 now, as agreed. ...So I try to leave syntax cleanup to net-next.
Besides, there's a trap which makes your patch a lot worse than mine... ;-) I too once tried a version without temporary until noticed that trap.
> Perhaps: > > net/ipv4/tcp_input.c | 33 ++++++++++++++++----------------- > 1 files changed, 16 insertions(+), 17 deletions(-) > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index b54d9d3..f846e11 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -4535,18 +4535,18 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, struct tcphdr *th) > static int tcp_defer_accept_check(struct sock *sk) > { > struct tcp_sock *tp = tcp_sk(sk); > - > - if (tp->defer_tcp_accept.request) { > - int queued_data = tp->rcv_nxt - tp->copied_seq; > - int hasfin = !skb_queue_empty(&sk->sk_receive_queue) ? > + struct tcp_deferred_accept_info *tdai = &tp->defer_tcp_accept; > + if (tdai->request) { > + int queued_data = tp->rcv_nxt - tp->copied_seq; > + int hasfin = !skb_queue_empty(&sk->sk_receive_queue) ? > tcp_hdr((struct sk_buff *) > sk->sk_receive_queue.prev)->fin : 0; > > if (queued_data && hasfin) > queued_data--; > > - if (queued_data && > - tp->defer_tcp_accept.listen_sk->sk_state == TCP_LISTEN) { > + bh_lock_sock(tdai->listen_sk); > + if (queued_data && tdai->listen_sk->sk_state == TCP_LISTEN) { > if (sock_flag(sk, SOCK_KEEPOPEN)) { > inet_csk_reset_keepalive_timer(sk, > keepalive_time_when(tp)); > @@ -4554,23 +4554,22 @@ static int tcp_defer_accept_check(struct sock *sk) > inet_csk_delete_keepalive_timer(sk); > } > > - inet_csk_reqsk_queue_add( > - tp->defer_tcp_accept.listen_sk, > - tp->defer_tcp_accept.request, > - sk); > + inet_csk_reqsk_queue_add(tdai->listen_sk, > + tdai->request, > + sk); > > - tp->defer_tcp_accept.listen_sk->sk_data_ready( > - tp->defer_tcp_accept.listen_sk, 0); > + tdai->listen_sk->sk_data_ready(tdai->listen_sk, 0); > > - sock_put(tp->defer_tcp_accept.listen_sk); > + sock_put(tdai->listen_sk); > sock_put(sk); > - tp->defer_tcp_accept.listen_sk = NULL; > - tp->defer_tcp_accept.request = NULL; > - } else if (hasfin || > - tp->defer_tcp_accept.listen_sk->sk_state != TCP_LISTEN) { > + tdai->listen_sk = NULL; > + tdai->request = NULL;
uh-oh...
> + } else if (hasfin || tdai->listen_sk->sk_state != TCP_LISTEN) { > + bh_unlock_sock(tdai->listen_sk); > tcp_reset(sk); > return -1; > } > + bh_unlock_sock(tdai->listen_sk);
...which will crash in here.
NAK.
> } > return 0; > } > > >
-- i. | |