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Petersen" , James Bottomley , Sasha Levin Subject: [PATCH AUTOSEL 4.14 35/87] scsi: klist: Make it safe to use klists in atomic context Thread-Topic: [PATCH AUTOSEL 4.14 35/87] scsi: klist: Make it safe to use klists in atomic context Thread-Index: AQHUTjLoRlKihnIMJkKmLcmntRQoyg== Date: Mon, 17 Sep 2018 03:02:46 +0000 Message-ID: <20180917030220.245686-35-alexander.levin@microsoft.com> References: <20180917030220.245686-1-alexander.levin@microsoft.com> In-Reply-To: <20180917030220.245686-1-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;CY4PR21MB0776;6:jhGzS+ldzNAqGaFxHQgk7B25btnWGcEJC8X1NMcLkIjeXMNbw+3w2kdeDcr7LqgwBS0IVM6jg0O77q54HsDipBWaXfiX+8DQC7LDUeuQfWiciEhVf0awjUXJFPTQsDj3VdIwMZxcWlpRa6pL3jcSbbslraKyQCv4pyDB7mE588T4Of0/bIG/1/UOjADcWF7q7FWega/JsZIbb3mHA++woocXyC0abBmXCnKsuaGhlOd2YoBBvDBgSDHOs+hSaz4CoB1DCmWrOY4PeOodqvNvJqFgnVJDAK8ht2qzV0IZRxupuaW5/LufN/Y57ybUEvqvdGAEUoQTB5XuC73trMo7sqesTA4bomeF+g7ucklI5dJrh40UIj4Y6gjpLgUn9Vx8hsutLNb07tFWzDKroEzXdj6m0UAfITfJmj5puP2E4QOtgSL5Vqu/L8m9quQrahH158bJc31TFSq0Yo1+Kv7xVA==;5:Y91rhApfLa0uJI2hdHA8Hf7LeoVVJvay5UTALeBtqsh+JuCZ48+BuktReAQESDAu1qe7v9GQOouhTC+pO6FpbnHnumxjCLISRzIUQioerxDURyOjViIkm2j87cpVbmFltVpXwqg0vbfLEgVJfvlMaoE5epPy7zCVgASmqMaSeMY=;7:QqA58M/b4yoAGH7ntbKULdtucjFfP6phqP5HoSE7zmOsjsq9GM95d+0eO69XFuFu3tjXxQRG9PTFcPVABtvSUGyYWuFGfCmBpsdoHzV24x+xm/1oqD0fZRDSgLtHcV8Rz1PStGACbuIEXEszTay9GrInCDb/vmVXwjt3wPTuQrxFKxp8ieCs52n1fCFCyVllLHUnwB7SKCKsnY11qw0Yk0Ko6JS5nnHq9DTIskmDf4WhJ5K9xv7lUpmhyWcQzCV1 x-ms-office365-filtering-correlation-id: 91675091-7f2e-4527-47ee-08d61c4a3f15 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:CY4PR21MB0776; x-ms-traffictypediagnostic: CY4PR21MB0776: x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(20558992708506)(146099531331640)(104084551191319)(28532068793085)(89211679590171); x-ms-exchange-senderadcheck: 1 x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(6040522)(2401047)(8121501046)(5005006)(3002001)(10201501046)(3231355)(944501410)(52105095)(2018427008)(93006095)(93001095)(6055026)(149027)(150027)(6041310)(20161123560045)(20161123564045)(20161123558120)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123562045)(201708071742011)(7699050)(76991041);SRVR:CY4PR21MB0776;BCL:0;PCL:0;RULEID:;SRVR:CY4PR21MB0776; x-forefront-prvs: 0798146F16 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39860400002)(366004)(136003)(346002)(376002)(396003)(51234002)(199004)(189003)(5250100002)(53936002)(72206003)(14454004)(102836004)(478600001)(4326008)(6346003)(2501003)(25786009)(6666003)(10290500003)(110136005)(54906003)(6436002)(66066001)(8936002)(316002)(107886003)(76176011)(2906002)(217873002)(6116002)(3846002)(22452003)(14444005)(6506007)(486006)(5660300001)(7736002)(2616005)(11346002)(446003)(97736004)(476003)(6486002)(105586002)(81166006)(99286004)(186003)(81156014)(2900100001)(8676002)(86612001)(68736007)(86362001)(26005)(36756003)(305945005)(256004)(106356001)(6512007)(1076002)(10090500001);DIR:OUT;SFP:1102;SCL:1;SRVR:CY4PR21MB0776;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) authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-message-info: QTBG4Z8bdEzc3g/KXeCsQ+Mrdwo/umjdtYLQKvwsNdTYfIvw5kAax8YTL+dLf9r9V2aLnyl+glIPhdOmTaKTSB8wBtWDHrkbsNteppblsaIGy4rswb+DKvGYA1PDcmekC/pzIM10ULjDnYReT9M2p8OdjjTOX6WY9O4HFpnaPiZUYnryyDsXNfagA6BORQu7DLB+khEsmVIJhfR+v7XOksByHoEXFkQZk1nDqBnCX1w3Duaexd3Cf9NDW9FvV3fY24eSBNCuCSJq4b92T2dZIJUq+ANVV+YuB74IH+1aPmEZu21SLaC6rtBLra6Iigumxit/vU9A2xtJWZUXptIUpMiKXrYo42nBH2cin1IddN0= 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: 91675091-7f2e-4527-47ee-08d61c4a3f15 X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Sep 2018 03:02:46.1343 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0776 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bart Van Assche [ Upstream commit 624fa7790f80575a4ec28fbdb2034097dc18d051 ] In the scsi_transport_srp implementation it cannot be avoided to iterate over a klist from atomic context when using the legacy block layer instead of blk-mq. Hence this patch that makes it safe to use klists in atomic context. This patch avoids that lockdep reports the following: WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&k->k_lock)->rlock); local_irq_disable(); lock(&(&q->__queue_lock)->rlock); lock(&(&k->k_lock)->rlock); lock(&(&q->__queue_lock)->rlock); stack backtrace: Workqueue: kblockd blk_timeout_work Call Trace: dump_stack+0xa4/0xf5 check_usage+0x6e6/0x700 __lock_acquire+0x185d/0x1b50 lock_acquire+0xd2/0x260 _raw_spin_lock+0x32/0x50 klist_next+0x47/0x190 device_for_each_child+0x8e/0x100 srp_timed_out+0xaf/0x1d0 [scsi_transport_srp] scsi_times_out+0xd4/0x410 [scsi_mod] blk_rq_timed_out+0x36/0x70 blk_timeout_work+0x1b5/0x220 process_one_work+0x4fe/0xad0 worker_thread+0x63/0x5a0 kthread+0x1c1/0x1e0 ret_from_fork+0x24/0x30 See also commit c9ddf73476ff ("scsi: scsi_transport_srp: Fix shost to rport translation"). Signed-off-by: Bart Van Assche Cc: Martin K. Petersen Cc: James Bottomley Acked-by: Greg Kroah-Hartman Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- lib/klist.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/lib/klist.c b/lib/klist.c index 0507fa5d84c5..f6b547812fe3 100644 --- a/lib/klist.c +++ b/lib/klist.c @@ -336,8 +336,9 @@ struct klist_node *klist_prev(struct klist_iter *i) void (*put)(struct klist_node *) =3D i->i_klist->put; struct klist_node *last =3D i->i_cur; struct klist_node *prev; + unsigned long flags; =20 - spin_lock(&i->i_klist->k_lock); + spin_lock_irqsave(&i->i_klist->k_lock, flags); =20 if (last) { prev =3D to_klist_node(last->n_node.prev); @@ -356,7 +357,7 @@ struct klist_node *klist_prev(struct klist_iter *i) prev =3D to_klist_node(prev->n_node.prev); } =20 - spin_unlock(&i->i_klist->k_lock); + spin_unlock_irqrestore(&i->i_klist->k_lock, flags); =20 if (put && last) put(last); @@ -377,8 +378,9 @@ struct klist_node *klist_next(struct klist_iter *i) void (*put)(struct klist_node *) =3D i->i_klist->put; struct klist_node *last =3D i->i_cur; struct klist_node *next; + unsigned long flags; =20 - spin_lock(&i->i_klist->k_lock); + spin_lock_irqsave(&i->i_klist->k_lock, flags); =20 if (last) { next =3D to_klist_node(last->n_node.next); @@ -397,7 +399,7 @@ struct klist_node *klist_next(struct klist_iter *i) next =3D to_klist_node(next->n_node.next); } =20 - spin_unlock(&i->i_klist->k_lock); + spin_unlock_irqrestore(&i->i_klist->k_lock, flags); =20 if (put && last) put(last); --=20 2.17.1