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Petersen" , James Bottomley , Sasha Levin Subject: [PATCH AUTOSEL 4.9 25/57] scsi: klist: Make it safe to use klists in atomic context Thread-Topic: [PATCH AUTOSEL 4.9 25/57] scsi: klist: Make it safe to use klists in atomic context Thread-Index: AQHUTjMUzmr4z8shJ0qiLO8mEN7TMQ== Date: Mon, 17 Sep 2018 03:03:58 +0000 Message-ID: <20180917030340.378-25-alexander.levin@microsoft.com> References: <20180917030340.378-1-alexander.levin@microsoft.com> In-Reply-To: <20180917030340.378-1-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;CY4PR21MB0757;6:W/YQA+nGwrAXpWp5f0zjdKkZmdkxVAt82fIr26MKPgr1UEBzOXH70VaAHOLzgKMdZtU+nStWLliYpJa5TtV/UP+B+1N0oO9tlgWL3DS8vbj0rni5aBu5QEYoZ/lh7iasCJcYmOpuvrH7ybzIbzkKdmTCwpsXooK8dRZEywYrmYuTjlU6MvQqlgB4pWLLf8ZvyOfERAnCd4bwt2Ih8thXQpfPYsYrhnxlp8SbLp5Xcsvony5q6vUU9TQAcgxvym1I7OV8DswRHYULtpHrZMldSFS30WfbRqshp6KXZLlBD9UjYiCS6NTt7OmfwMVrh7oyITH1RD+vOIR47KvOwkZ922dTMSA1w4EC3s2fbTTUEy+5S2Y9jH/VK/4vn6iTRVVeG1wQj0ygCEZPj1U/tDC6VViQaMm5HtOxeDDExMPPYRw22nE1RQm1z6mABeQ/zVm3zbCGJIgrD2SeIcF/UVEmhw==;5:kmGNzVEz0jeObkzuMzP/oyxMYgGe/7b7kV5aOz2UPUeoJkzQ20Fji2CG88tW082FASL/aN2AD+Sn6RU9Eog4o4/BfJnMP5YERZ9iEWQJ84gE26a5LZqF+3oA8gi4roNMQbjC4cMwCkqip7q3wVvO1bvyTEX7cSWNfJAEG/XPok0=;7:9TBklowl/KzCajw+RJmY9sUZfHL4kX9u720sIsBlV7s9G4OeaHLwvHCE75XXHUCVKyc1EkcUJCo7onzJY6VsYB9Gy/ivUt3GsX4A8s5DR6/WEP8aFAT+Uex7Cw3pj7hJdjYoHsqbSrPXXGvYUNDiZaY9iC5jKcAVvSAHgai4IcDJz6d0PxFgJisvDL/wL0R1dmFD/R0tx0kVkzrj/bobfG7Qcyf5Ftta9zLmhENkPx5FT91ymwu1mzkl0d4kv7cP x-ms-office365-filtering-correlation-id: aaf3754b-2e15-48b8-192c-08d61c4a7588 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:CY4PR21MB0757; x-ms-traffictypediagnostic: CY4PR21MB0757: 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)(10201501046)(3002001)(3231355)(944501410)(52105095)(2018427008)(93006095)(93001095)(6055026)(149027)(150027)(6041310)(20161123560045)(20161123564045)(20161123558120)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123562045)(201708071742011)(7699050)(76991041);SRVR:CY4PR21MB0757;BCL:0;PCL:0;RULEID:;SRVR:CY4PR21MB0757; x-forefront-prvs: 0798146F16 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39860400002)(136003)(366004)(346002)(376002)(396003)(51234002)(189003)(199004)(8936002)(68736007)(476003)(10290500003)(446003)(53936002)(11346002)(6512007)(486006)(86612001)(6436002)(1076002)(256004)(6486002)(2616005)(14444005)(81156014)(81166006)(7736002)(8676002)(217873002)(478600001)(305945005)(3846002)(6116002)(86362001)(4326008)(106356001)(66066001)(186003)(36756003)(99286004)(76176011)(102836004)(107886003)(26005)(2906002)(5660300001)(110136005)(54906003)(10090500001)(22452003)(72206003)(2900100001)(316002)(14454004)(97736004)(105586002)(6506007)(25786009)(6346003)(6666003)(5250100002)(2501003);DIR:OUT;SFP:1102;SCL:1;SRVR:CY4PR21MB0757;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: OPpNuMJzI/5YjSDTUXdhPxu0n7rTO851MwwJkW1ZR9Z54vggEtuYhrfZDf22kVtNwsLoe3Hvn0qaSUOGmtmHcflXOTrA1SiV1VhVO6xO/geDdZNa4PJCSdAPEr5WChA3dViWUG2jtQ+Is+h+FffmOhRa7TNufem2M+SZawKQ02n9P1j82SLb7cAV1n3HuJzq17N8GOuPPIJXS0WkJYwvYqZhkOvE7e47CtaRwEmu0tMdGb2WjtuqQwtfpCFZBPAxeN2IGhy9drLfC6P9OxAqunhWeUiIrlWA0nGPZxy8Igu0pqZEZ10dR5GF+sL0Wv62ZstK3p1UpTbAmXifGxJybTfFjp2yYAtURDM7e35NZHg= 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: aaf3754b-2e15-48b8-192c-08d61c4a7588 X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Sep 2018 03:03:58.9616 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0757 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