From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Perches Subject: Re: [fixed] [patch] Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+ Date: Tue, 03 Jun 2008 16:54:01 -0700 Message-ID: <1212537241.6980.12.camel@localhost> References: <20080603094057.GA29480@elte.hu> <20080603.150344.145518113.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , mingo@elte.hu, mcmanus@ducksong.com, peterz@infradead.org, LKML , Netdev , rjw@sisk.pl, Andrew Morton , johnpol@2ka.mipt.ru To: Ilpo =?ISO-8859-1?Q?J=E4rvinen?= Return-path: Received: from 136-022.dsl.labridge.com ([206.117.136.22]:2085 "EHLO mail.perches.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752807AbYFCX5O (ORCPT ); Tue, 3 Jun 2008 19:57:14 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2008-06-04 at 02:22 +0300, Ilpo J=C3=A4rvinen wrote: > But here's somewhat more likely explanation... Only compile tested... > It probably needs some commenting from people who understand locking=20 > variants & details (I don't). > Signed-off-by: Ilpo J=C3=A4rvinen > 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 =3D tcp_sk(sk); > =20 > if (tp->defer_tcp_accept.request) { > + struct sock *listen_sk =3D 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. 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 =3D tcp_sk(sk); - - if (tp->defer_tcp_accept.request) { - int queued_data =3D tp->rcv_nxt - tp->copied_seq; - int hasfin =3D !skb_queue_empty(&sk->sk_receive_queue) ? + struct tcp_deferred_accept_info *tdai =3D &tp->defer_tcp_accept; + if (tdai->request) { + int queued_data =3D tp->rcv_nxt - tp->copied_seq; + int hasfin =3D !skb_queue_empty(&sk->sk_receive_queue) ? tcp_hdr((struct sk_buff *) sk->sk_receive_queue.prev)->fin : 0; =20 if (queued_data && hasfin) queued_data--; =20 - if (queued_data && - tp->defer_tcp_accept.listen_sk->sk_state =3D=3D TCP_LISTEN) { + bh_lock_sock(tdai->listen_sk); + if (queued_data && tdai->listen_sk->sk_state =3D=3D 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); } =20 - 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); =20 - 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); =20 - sock_put(tp->defer_tcp_accept.listen_sk); + sock_put(tdai->listen_sk); sock_put(sk); - tp->defer_tcp_accept.listen_sk =3D NULL; - tp->defer_tcp_accept.request =3D NULL; - } else if (hasfin || - tp->defer_tcp_accept.listen_sk->sk_state !=3D TCP_LISTEN) { + tdai->listen_sk =3D NULL; + tdai->request =3D NULL; + } else if (hasfin || tdai->listen_sk->sk_state !=3D TCP_LISTEN) { + bh_unlock_sock(tdai->listen_sk); tcp_reset(sk); return -1; } + bh_unlock_sock(tdai->listen_sk); } return 0; }