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Miller" , Sasha Levin Subject: [PATCH AUTOSEL 4.4 27/30] s390/qeth: fix race in used-buffer accounting Thread-Topic: [PATCH AUTOSEL 4.4 27/30] s390/qeth: fix race in used-buffer accounting Thread-Index: AQHURkM1rA85eaUASkuk31gNJDwZiw== Date: Fri, 7 Sep 2018 00:39:17 +0000 Message-ID: <20180907003853.57942-27-alexander.levin@microsoft.com> References: <20180907003853.57942-1-alexander.levin@microsoft.com> In-Reply-To: <20180907003853.57942-1-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;CY4PR21MB0822;6:39BFvbA/irZmGFj5PGm1EE6Vq7v4ERM9VTuSS7V3j1wBE7skUVqYWX7l8BozkDLfzr0Z78EFvfZe744WZeECoGgb5JOAlEh7fS4hcdY7yiMDnyFyJWEilURq7lRhTV9s+zx0cqnGPMuYVIxr4AwHKJvDJsl2vMfM5b17T/l6+x+DaaRA0YMYSb5IA+pmtUQ0feNHI0Sjl3iLs8eRgqlRic9WwmvwOuX4q9m+nhxpj2Fkh4quxiD7yI2jHh5lAQpKz2XRk0bQN9ZA493EeH/aJnnOIrVVw35ZEr53J/KT6LSQZkSDB31IyR/N5+9eHBI5melNwQWHSkcFw/fb7wtmWF4u1R66l3x+uDmbEGmkal8z5q/bngXY1Wd/NKDKYUpo6G1/qeOH9EYUjSHwxgmKKfV8vdI1yC3dgoft2j5LQYtPmKSDLaTwUwQQaxYeWETkwsHqbA6aTVGwmPAcJiDMeQ==;5:IbG8OJzSBDXXF1j3sHPvh+PO/bj5Zz6W0S9BmXfFyYo03j52Lo4KvQqmupRUxHt7c2U5C4jFZ6TVkg31/ApT0w604VlV2nd3ExCLU0EwIFj5YVS2ECFI2tz3n2XC9JJ8KgUdEsZ4RiuIB34K+3QdIiCvkjgAR+h6FRSiljU9Q78=;7:f1+a6zc3Dd3B3Eyzq4VAQTxMgsVdyfI+t+JeCU79df56Erdg+wEzKlwtK1uxdMfw7md0FrUIBwQ7p76Efu5oqgWs7sZw3mq+8oPJZU08FI/M8LigKnpSIERgZmstINaNYS2XDYrMzfEXU2VPEpvm7zoouyFEjxoKomK12uv7/F8HzNH43T8gM4w53wWWwSyrgL9aF5dClREM5HLadqfEIaPhijI/pElNRo7p9496JqASbQ2jpkDgDcp9si+KsKJu x-ms-office365-filtering-correlation-id: 05349a1e-ff0e-4a34-366e-08d6145abc8e x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(8989137)(4534165)(4627221)(201703031133081)(201702281549075)(8990107)(5600074)(711020)(4618075)(2017052603328)(7193020);SRVR:CY4PR21MB0822; x-ms-traffictypediagnostic: CY4PR21MB0822: 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)(104084551191319); x-ms-exchange-senderadcheck: 1 x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(6040522)(2401047)(8121501046)(5005006)(93006095)(93001095)(10201501046)(3002001)(3231344)(944501410)(52105095)(2018427008)(6055026)(149027)(150027)(6041310)(20161123560045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123564045)(20161123558120)(20161123562045)(201708071742011)(7699049)(76991033);SRVR:CY4PR21MB0822;BCL:0;PCL:0;RULEID:;SRVR:CY4PR21MB0822; x-forefront-prvs: 07880C4932 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(346002)(39860400002)(376002)(396003)(136003)(366004)(199004)(189003)(6506007)(10290500003)(478600001)(102836004)(81166006)(14454004)(22452003)(6486002)(26005)(53936002)(186003)(6436002)(72206003)(2501003)(5250100002)(110136005)(6666003)(54906003)(3846002)(316002)(6512007)(36756003)(1076002)(97736004)(8676002)(81156014)(6116002)(5660300001)(10090500001)(76176011)(14444005)(2906002)(256004)(8936002)(2900100001)(99286004)(66066001)(305945005)(7736002)(486006)(217873002)(68736007)(4326008)(25786009)(476003)(106356001)(11346002)(107886003)(575784001)(446003)(105586002)(86362001)(86612001)(2616005);DIR:OUT;SFP:1102;SCL:1;SRVR:CY4PR21MB0822;H:CY4PR21MB0776.namprd21.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: ihdDolC3cn01cc/pwLV1KcCRZc6yhhMOqwRgmml6fvVzy1H+8ZJS20OqApnGRdzuQLz/HSyvFIiwlhZFykmSxbHXvvryXihF6GUA5xLMfPmNo61wY3dQv5WQAWcQXtKaQL45EJI43s9yryjXomZY46l9/XGSMmfvKbPldaqZlacxqDC2Mr1jagnyFg0Cjiy0ecMvTy3gdbys6UoQKxfIPSTBCYM1Flj+t03hHUzxf1nJU33WVAuj/o/rdb5ignnXmR6D2Xpsh/HeOTS7Ywd+uwmwIyCslVCR44sQx1IbmBIGVIKZOxAi6Ba/bRgpvzkSB/YLXbFfbbvdT17iMis+Q/kQLBSnYJ4BRdtwySPLz40= 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: 05349a1e-ff0e-4a34-366e-08d6145abc8e X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Sep 2018 00:39:17.0403 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0822 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 95c631125a20..09ac56317f1b 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -3505,13 +3505,14 @@ 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