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Miller" , Sasha Levin Subject: [PATCH AUTOSEL for 4.4 033/101] tcp: remove poll() flakes with FastOpen Thread-Topic: [PATCH AUTOSEL for 4.4 033/101] tcp: remove poll() flakes with FastOpen Thread-Index: AQHTtpqKjLi43huFCkOggLPRwLtwzg== Date: Thu, 8 Mar 2018 05:01:38 +0000 Message-ID: <20180308050023.8548-33-alexander.levin@microsoft.com> References: <20180308050023.8548-1-alexander.levin@microsoft.com> In-Reply-To: <20180308050023.8548-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1046;7:E/YEHBani8c1C/XOhY2r3+BoFkB0MlPW3mmpEQjEoInpTjYG7x/5pr4eYzXR8TBPi4O9m9mSHKGh5rpXZjWPofp6pHhQxIvS1q8cid3vS0YsJnHV8Lwse3RTZ5O5Erima8RaDkr47U9sMv4gXtkooZ8YdY5Tbzn4Y7IKbujygm1sAH1Cq4dR4X7z8e25EGTzlmrg77ilCRuBUC+m970X4tOTeC8DRt9OKTCx2xBkHHRk7Tb2gqtXEDT2tCj42vvN;20:Rf++4Be02nShFd5WyNyHR0vps2zqUWIA6XDb/AIiw+cn1DRJOS9UFbmckx7QQG7YQe8XwG+0dZDGUdshn+8ypfoakDs+tYBZc0oJY38B42yAdfq/DHe5SvCKWcbDJ1HzPkwgW8dxPLtnL+wwK1Hk36oR5optDuhUPePhf5f5OJ4= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 078b3063-e520-4707-386f-08d584b241e2 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1046; x-ms-traffictypediagnostic: DM5PR2101MB1046: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(89211679590171)(211936372134217)(153496737603132); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(61425038)(6040501)(2401047)(5005006)(8121501046)(3002001)(10201501046)(3231220)(944501244)(52105095)(93006095)(93001095)(6055026)(61426038)(61427038)(6041288)(20161123562045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123560045)(20161123558120)(20161123564045)(6072148)(201708071742011);SRVR:DM5PR2101MB1046;BCL:0;PCL:0;RULEID:;SRVR:DM5PR2101MB1046; x-forefront-prvs: 060503E79B x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(346002)(39380400002)(39860400002)(396003)(376002)(199004)(189003)(6486002)(53936002)(3660700001)(5660300001)(6436002)(6512007)(36756003)(3846002)(478600001)(105586002)(305945005)(6116002)(1076002)(2900100001)(72206003)(3280700002)(68736007)(7736002)(97736004)(22452003)(14454004)(6666003)(2501003)(106356001)(10090500001)(10290500003)(2950100002)(81156014)(25786009)(54906003)(107886003)(59450400001)(76176011)(6506007)(2906002)(110136005)(99286004)(26005)(186003)(86362001)(102836004)(81166006)(5250100002)(4326008)(8676002)(86612001)(316002)(8936002)(66066001)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR2101MB1046;H:DM5PR2101MB1032.namprd21.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; x-microsoft-antispam-message-info: YlLsf5ghD3a9KTT84hOeFoCJDoiaFK5Ge7jD5y6lKgoMhJoZnYehnNZKRXkLCYNHC+wmu2hQvUrSrsZLcE28tRJi8G2FtSQwLsCre94197yXcmnJeUpYfeDnAUHpjS//SkI5ErG4HREWGLIaWCycGjzk4TDWj4av9xeR3Hn46xXRJPPMdI3GiowXmm9QaEhBynnAeRwZU/EiuPEq0jDXg9v0HFAskQTH+WioOA1oGm2LDyPQJW7TPEBFJHt6eCR3V9XSFBh2OGw6ecrE09kDL+7MKfMrFMM41QLB8AdXz0aZrMjJEkfqOvftWTlX06Wp28Z7dp81lFHJwhRf1T8BLw== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 078b3063-e520-4707-386f-08d584b241e2 X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Mar 2018 05:01:38.3489 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1046 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Eric Dumazet [ Upstream commit 0f9fa831aecfc297b7b45d4f046759bcefcf87f0 ] When using TCP FastOpen for an active session, we send one wakeup event from tcp_finish_connect(), right before the data eventually contained in the received SYNACK is queued to sk->sk_receive_queue. This means that depending on machine load or luck, poll() users might receive POLLOUT events instead of POLLIN|POLLOUT To fix this, we need to move the call to sk->sk_state_change() after the (optional) call to tcp_rcv_fastopen_synack() Signed-off-by: Eric Dumazet Acked-by: Yuchung Cheng Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/tcp_input.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 71290fb7d500..75433ed6714b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5464,10 +5464,6 @@ void tcp_finish_connect(struct sock *sk, struct sk_b= uff *skb) else tp->pred_flags =3D 0; =20 - if (!sock_flag(sk, SOCK_DEAD)) { - sk->sk_state_change(sk); - sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); - } } =20 static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synac= k, @@ -5531,6 +5527,7 @@ static int tcp_rcv_synsent_state_process(struct sock = *sk, struct sk_buff *skb, struct tcp_sock *tp =3D tcp_sk(sk); struct tcp_fastopen_cookie foc =3D { .len =3D -1 }; int saved_clamp =3D tp->rx_opt.mss_clamp; + bool fastopen_fail; =20 tcp_parse_options(skb, &tp->rx_opt, 0, &foc); if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) @@ -5633,10 +5630,15 @@ static int tcp_rcv_synsent_state_process(struct soc= k *sk, struct sk_buff *skb, =20 tcp_finish_connect(sk, skb); =20 - if ((tp->syn_fastopen || tp->syn_data) && - tcp_rcv_fastopen_synack(sk, skb, &foc)) - return -1; + fastopen_fail =3D (tp->syn_fastopen || tp->syn_data) && + tcp_rcv_fastopen_synack(sk, skb, &foc); =20 + if (!sock_flag(sk, SOCK_DEAD)) { + sk->sk_state_change(sk); + sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); + } + if (fastopen_fail) + return -1; if (sk->sk_write_pending || icsk->icsk_accept_queue.rskq_defer_accept || icsk->icsk_ack.pingpong) { --=20 2.14.1