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Miller" , Sasha Levin Subject: [PATCH AUTOSEL 4.9 37/43] s390/qeth: fix race in used-buffer accounting Thread-Topic: [PATCH AUTOSEL 4.9 37/43] s390/qeth: fix race in used-buffer accounting Thread-Index: AQHURkMhGR4lc+hxb06be+WkM/1BSQ== Date: Fri, 7 Sep 2018 00:38:44 +0000 Message-ID: <20180907003816.57852-37-alexander.levin@microsoft.com> References: <20180907003816.57852-1-alexander.levin@microsoft.com> In-Reply-To: <20180907003816.57852-1-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;CY4PR21MB0694;6:n/Ej5pn2KtSrABOAmg0LpoW1P+/atMcMbl090rnOmIfzrgLzUEyCNHLliyRzn4Wi7rXcL41x5mpTI7cAffWHldCB6TdnIE05g0lIrNPt83jGscKXb7hUBpVPZZH5/uNIeJQrAh5YSdV23w9QQgrHWz3qppyWWSszXVfVjCBY28xZZS8taJY9eWs/v1jEKFTSExVpA/AJY4IHwTXgnTA6CNt7tov6KRQGaY4++m9RhYJUIPzsL5ax4qwMuyO/Xh2oHpR9YsgaA3+8LJeKT5ejCyQD/xUPp9+3K2zzG/xwjKenYs3EgBLevo9y1Tem6OU/OekaI3aHS7iTavuS1zBe8iBQJYicetX69PZRGSf8lQzBuZjm6pwvRluvucrVlVz8Yr5VOBP3pAL3B+I9jFHLzwz8qndLYG/ZPTbdD6ZS5vvhVZJG0RjWnkk8YawpKEzy5hQSwQN0tVC4uZhtJJ3GYg==;5:io8wR9JAjJy07bHPVP1n39/yAoksXpwRErVvMUSogJLQQPNVE2JDyHvQ/ks3nFB/2HvbvczWiDV0PklgkViCxEQadb3yDPc2FCGTf4k22EUW943SfoPUf2bSFag6PIISSq9Lh+i7bx2xB0YOFTQcyJa+PMK/56yL6/km1DP8F7A=;7:nLLZr0mSU38WU0TXcvOcsFXGUN+mMt2G0ubiorQ51NPi5XbJWAQalI6DrmWeTLnpMB7+nhusZiNTdNZayNTTAtaIFLLO1kqn6gvfx0KWF71uC6+OM6i0tI6u90RjBHU62/t9KJ0Fxz/NQtuuS4A1V+2UJkWW0GNv+Sti+0NsE2zwIXEVlXSPX4l0iAwsi8rrPTV0uFWav/53MpgxBUWkyKi6ZQeV4M4SMh+3zf73PzSVEeNBTZLAG+iFA/edhRqy x-ms-office365-filtering-correlation-id: f1eb4087-faeb-49be-25c4-08d6145aa208 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(4534165)(4627221)(201703031133081)(201702281549075)(5600074)(711020)(4618075)(2017052603328)(7193020);SRVR:CY4PR21MB0694; x-ms-traffictypediagnostic: CY4PR21MB0694: x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(89211679590171)(104084551191319); x-ms-exchange-senderadcheck: 1 x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(6040522)(2401047)(5005006)(8121501046)(3231344)(944501410)(52105095)(2018427008)(3002001)(93006095)(93001095)(10201501046)(6055026)(149027)(150027)(6041310)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123560045)(20161123564045)(20161123558120)(20161123562045)(201708071742011)(7699049)(76991033);SRVR:CY4PR21MB0694;BCL:0;PCL:0;RULEID:;SRVR:CY4PR21MB0694; x-forefront-prvs: 07880C4932 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39860400002)(396003)(376002)(366004)(136003)(346002)(189003)(199004)(2906002)(575784001)(186003)(86362001)(6666003)(110136005)(107886003)(54906003)(36756003)(25786009)(4326008)(256004)(14444005)(2616005)(6506007)(6486002)(6346003)(6436002)(6512007)(446003)(476003)(11346002)(486006)(86612001)(2900100001)(5660300001)(102836004)(26005)(66066001)(53936002)(68736007)(7736002)(81166006)(81156014)(8676002)(10090500001)(8936002)(6116002)(3846002)(99286004)(105586002)(76176011)(106356001)(5250100002)(22452003)(14454004)(316002)(1076002)(2501003)(305945005)(217873002)(97736004)(10290500003)(72206003)(478600001);DIR:OUT;SFP:1102;SCL:1;SRVR:CY4PR21MB0694;H:CY4PR21MB0776.namprd21.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-message-info: r6ckDZLO2FuUPBCgPVhctGiSE5KSLeZeafUCIAy6ctPmD/ODp/bEAjzT1xXNbQiXxL5a4XgIgSwaShFyERFDE9Ppp0VGMxNOvHf4IsF482beWjC3q9kKI41e30q3UCLTGcphf2oIeeaIRqW2zwZdios7QQ4hJJYJYqJODFrbMy3rfBrSmvoEMlpFHcF8uD+RElwSCi1ca/lOYf2Z/sD10RH+07wyjrhoLhDwXkU/DmhzSf3ntnNYnHKXhr2ycWPBKDh4BXybFc/vPdp8nwptAkZKoxA4R18hQfVhsBFoXxgAFqoT1WumqK5Sn8tKv2azUT08nrAqoeEN0MXy2dCQdWQ6AlLEAoWHSAtAoPKpKV8= 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: f1eb4087-faeb-49be-25c4-08d6145aa208 X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Sep 2018 00:38:44.5208 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0694 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Julian Wiedmann [ Upstream commit a702349a4099cd5a7bab0904689d8e0bf8dcd622 ] By updating q->used_buffers only _after_ do_QDIO() has completed, there is a potential race against the buffer's TX completion. In the unlikely case that the TX completion path wins, qeth_qdio_output_handler() would decrement the counter before qeth_flush_buffers() even incremented it. Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/s390/net/qeth_core_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core= _main.c index 283416aefa56..258a72869f57 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -3499,13 +3499,14 @@ static void qeth_flush_buffers(struct qeth_qdio_out= _q *queue, int index, qdio_flags =3D QDIO_FLAG_SYNC_OUTPUT; if (atomic_read(&queue->set_pci_flags_count)) qdio_flags |=3D QDIO_FLAG_PCI_OUT; + atomic_add(count, &queue->used_buffers); + rc =3D do_QDIO(CARD_DDEV(queue->card), qdio_flags, queue->queue_no, index, count); if (queue->card->options.performance_stats) queue->card->perf_stats.outbound_do_qdio_time +=3D qeth_get_micros() - queue->card->perf_stats.outbound_do_qdio_start_time; - atomic_add(count, &queue->used_buffers); if (rc) { queue->card->stats.tx_errors +=3D count; /* ignore temporary SIGA errors without busy condition */ --=20 2.17.1