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Miller" , Sasha Levin Subject: [PATCH AUTOSEL for 3.18 21/53] tcp: remove poll() flakes with FastOpen Thread-Topic: [PATCH AUTOSEL for 3.18 21/53] tcp: remove poll() flakes with FastOpen Thread-Index: AQHTtprEW1btRittnk2WK+EHb4pjxw== Date: Thu, 8 Mar 2018 05:03:15 +0000 Message-ID: <20180308050230.8876-21-alexander.levin@microsoft.com> References: <20180308050230.8876-1-alexander.levin@microsoft.com> In-Reply-To: <20180308050230.8876-1-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;DM5PR2101MB0871;7:rowN5XdsuSUP+hbZWZg9TmKulVTPtwLALE53GgeEE4KaD+QtYBlT1jE2C4sOTLPLp22IEo07TELWAPwJnAMwX9/hZ7s0VcWT8dTSwHhHYTS6UdyAdbEczRGJFYmBGLxVRnYcliZqk/7WWifIy31gvDUc7N6JyyxZ2UUhGpf7pABLpbomt8X7PW7y3k0d/Cdx9oBsT1XfeNGlR+BHHCvFkHn1ev5UOLbiDpRSIPZCnbGVqlYYKlDXl5XT6CImwQZU;20:kzENC2DO69sz1ViF3n307frsdGDxiMYnz/IIRU4xNRsELwwiEZnikSCdsmBDlKtKgs4dC+zc7hVsRav7DbF+loKoadThEIJ+Fkm+UewHZuZFMt7kfC4a6mCcphmsT6M8wNfg7VRnyh/rtMTC3NT/yc4Jf/haWk/GIfXfKInCN0A= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 49e25d84-3765-46c4-6eee-08d584b2a96d x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB0871; x-ms-traffictypediagnostic: DM5PR2101MB0871: 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:DM5PR2101MB0871;BCL:0;PCL:0;RULEID:;SRVR:DM5PR2101MB0871; x-forefront-prvs: 060503E79B x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39380400002)(39860400002)(346002)(376002)(366004)(396003)(189003)(199004)(7736002)(14454004)(3660700001)(68736007)(305945005)(2900100001)(10090500001)(66066001)(97736004)(81166006)(105586002)(10290500003)(8676002)(72206003)(8936002)(102836004)(59450400001)(86612001)(53936002)(6512007)(6506007)(110136005)(107886003)(478600001)(54906003)(106356001)(81156014)(25786009)(4326008)(26005)(316002)(186003)(5250100002)(2501003)(2906002)(86362001)(6666003)(3280700002)(22452003)(36756003)(2950100002)(1076002)(6486002)(76176011)(5660300001)(99286004)(6436002)(3846002)(6116002)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR2101MB0871;H:DM5PR2101MB1032.namprd21.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; x-microsoft-antispam-message-info: ToT6RVHGCKP9ixEVIteyTjBUGeb1hclVkg3QJLTZJcPXb5Rc28OgbqE7CBJlIwunZVXh9r6FYuad31THO3EMtqILvmp+g4sgMALpcQ2zrQ7R6DtQ68cUBsc71rpxObHvbIFd1KiZYNqXqOSdYywiWp6Vhv/fGsgunD3YQFtrNqG4ZdMhkQK8/9zh9uPKROpr6McLpgEhOfzxv+OPwBC6jajKEBBzw/e++qfjuyhpNmLznqHvgo4Nrg1Y9d91nhb2ZxxQBw3OrpQbcRUBWin3CAg/GWZjKLI9jcVJ/RblvG879JuK8tWB/ltIuzKx6+tVP05ew+JFMM/xyAu1vv3nhw== 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: 49e25d84-3765-46c4-6eee-08d584b2a96d X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Mar 2018 05:03:16.0014 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB0871 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 f705356f538b..8d61c870643e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5322,10 +5322,6 @@ 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, @@ -5380,6 +5376,7 @@ 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) @@ -5482,10 +5479,15 @@ 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