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Miller" , Sasha Levin Subject: [PATCH AUTOSEL for 4.9 058/190] tcp: remove poll() flakes with FastOpen Thread-Topic: [PATCH AUTOSEL for 4.9 058/190] tcp: remove poll() flakes with FastOpen Thread-Index: AQHTtpo28PE32iJUyES6TampkLY/0w== Date: Thu, 8 Mar 2018 04:59:17 +0000 Message-ID: <20180308045810.8041-58-alexander.levin@microsoft.com> References: <20180308045810.8041-1-alexander.levin@microsoft.com> In-Reply-To: <20180308045810.8041-1-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;DM5PR2101MB1109;7:qGZvEgrtFdipVzS3OzhS9JQkY5M8G17MkRVRMzj+8pDDGSBFND8f1mwI8FkF+nm/roBewmzhwHeggVmk7MQ8HP0gPd90pvhzPTav+o3oRYRkifuPzolj+rrbaDWu/fsxJ7zGSW64cVNQ4+5h7KyIC5vRAjvUX8B7B/kxd0tCNDTBmOS6/W/vuEaEir6o72xu30lssarWIFU/AnxCLqqnpKodV1iGT9wPcrkc3/8bWhZtqcXzslSqHI6cBR6K/zRu;20:dBTiEqSfANCNTRTSpFOJknkEBTzxj0Jdd3EdyxuRK7FsgjRQjsyx/35CrQX61H164/y2WrCwaq8TA61fbsUKnKe/W4b7bC8HmVbnW71Uj8TIQpxpOchI4aFj9H6XlkkYQvJoqlUiU9VpvPoftuuCWorUmyTV5H7YE+Z0ptaQbkc= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: f96db19b-cf25-4f8a-733e-08d584b18ece x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1109; x-ms-traffictypediagnostic: DM5PR2101MB1109: 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)(8121501046)(5005006)(3231220)(944501244)(52105095)(93006095)(93001095)(10201501046)(3002001)(6055026)(61426038)(61427038)(6041288)(20161123558120)(20161123562045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123564045)(20161123560045)(6072148)(201708071742011);SRVR:DM5PR2101MB1109;BCL:0;PCL:0;RULEID:;SRVR:DM5PR2101MB1109; x-forefront-prvs: 060503E79B x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(396003)(376002)(346002)(39380400002)(39860400002)(366004)(199004)(189003)(3660700001)(5250100002)(102836004)(6436002)(2501003)(81166006)(8936002)(6486002)(81156014)(53936002)(6512007)(8676002)(6506007)(5660300001)(86612001)(76176011)(10290500003)(86362001)(4326008)(59450400001)(105586002)(25786009)(10090500001)(26005)(2900100001)(316002)(106356001)(97736004)(54906003)(305945005)(7736002)(186003)(36756003)(22452003)(110136005)(14454004)(72206003)(6116002)(3846002)(68736007)(3280700002)(66066001)(2906002)(2950100002)(478600001)(6666003)(99286004)(1076002)(107886003)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR2101MB1109;H:DM5PR2101MB1032.namprd21.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; x-microsoft-antispam-message-info: PFqtXfOUwGqVUV6QCwOxd581T0C/MFILoRl1KQIj+UQNwFdwYMsuNbWkdFLydf12Azp/pvf/K5gfJyYtU8WEaVl4cbXf2Ll7I3JlmMMfZXOE+r1fmXVtQsw7WD2bDgAATIBFv0xXAusA7bwugdc7pmxScXwYbL1Z+BdGm5hTsYhVg10lnVGE9SJ/iQlOs7/rtJEH7gGRnsRqj/pPVWEzA2xGBYzrYbyxiIbyS90sdvbe1UGL+Gw3384IBLOy6EZHQrSVpNtaEnlt34gwX9BoG8n66cEbzUbCRAl6V7ED1j5cZwXsqsgaafZUDsW+n+0NuuAgHqGedhjDJDKGPbEpQg== 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: f96db19b-cf25-4f8a-733e-08d584b18ece X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Mar 2018 04:59:17.4372 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1109 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 2f107e46355c..b5f264ae3bff 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5606,10 +5606,6 @@ 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, @@ -5678,6 +5674,7 @@ 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) @@ -5781,10 +5778,15 @@ 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