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Petersen" , James Bottomley , Sasha Levin Subject: [PATCH AUTOSEL 4.4 18/43] scsi: klist: Make it safe to use klists in atomic context Thread-Topic: [PATCH AUTOSEL 4.4 18/43] scsi: klist: Make it safe to use klists in atomic context Thread-Index: AQHUTjM4hpANISbhZkewbje/D+8sng== Date: Mon, 17 Sep 2018 03:05:00 +0000 Message-ID: <20180917030445.484-18-alexander.levin@microsoft.com> References: <20180917030445.484-1-alexander.levin@microsoft.com> In-Reply-To: <20180917030445.484-1-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;CY4PR21MB0742;6:Vgy904W3RgthXpwYrJ7Bhnzb+tczsJoMqkJxLznrApqcyDxXuuo5XLqzwDpgjecZJ55m28PZEb+0F8Yns4oThxno+Ossy4eyJiZgOmtzMEp+Jfda8RoeHzoNxNK/QdMBAIrT0z1bPNltzxT5WKC1kbLVzO868H9eZ/aJOO2S2WSzAHreForznB8dPkF2XHO7xrHAa/u9TC2Wf2yj7cyqLKi7LlJWTtCzBX9evmW3iIHX4PL0APDsDpvR7JxdiJ3i2TBPyP8fJQUXqcNhDeq5wVILOEkRC/sUpavjlXJ6dgnDffHYE6d7KnT2sxlq/2x5i40kaFfalePLSiI0v9X/1NI+5IF8KmgdSyrWKoBc8xANc1T6wsQiCQ/ZoXbr9/0WSUIMqZCY5V93Q/BFvXXq8pfztx3K2jnCnmmTTZPWaWb5ureumvY9AWOuh3f3a/Z/KcANiU/lDmWmGA79A+xxaA==;5:n6Hkf78S3xdew7t47RcSw3eF4VYeXOv/5unz9tnJAqeOODGwLva3lf9UOJSSn9jCLXiX+nt8+zeoJO5FsUEmRYT3m1bMGoSsDx644Vf2jbVPr94+VstZw9kg+AsfBgAEQEjNAj5fgRM+yP2LK70KLjCgca66WKl8RSUTuqFt1II=;7:OSs+dwIK7TuG+feV7bDsWjhUlryPdkqAULT4pNJNJOP76eFicovKkTc2wR+GbRuYErFcIDC4xdT7Wz7154jAPQaYKRYDzHSi8sM6ifRYxCk8wfwxlzHMRK8A+Asr+csPwMZcoGeL5we0/2ogGVKiWP/72Y60vHC27mEK1PKxun28SZSqd4uwM8DU5+QtdxpdTqqgE65aOHjPIrImQPAqywzNuBJPFmEDF7fXuINt0EhBpeKbB8wCYmWFU1Mx/GFa x-ms-office365-filtering-correlation-id: 8afcae77-4c33-4084-5f38-08d61c4aa73c 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:CY4PR21MB0742; x-ms-traffictypediagnostic: CY4PR21MB0742: 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)(5005006)(8121501046)(93006095)(93001095)(3231355)(944501410)(52105095)(2018427008)(3002001)(10201501046)(6055026)(149027)(150027)(6041310)(20161123562045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123564045)(20161123560045)(20161123558120)(201708071742011)(7699050)(76991041);SRVR:CY4PR21MB0742;BCL:0;PCL:0;RULEID:;SRVR:CY4PR21MB0742; x-forefront-prvs: 0798146F16 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39860400002)(136003)(346002)(366004)(396003)(376002)(199004)(189003)(51234002)(6486002)(6436002)(6512007)(53936002)(4326008)(3846002)(217873002)(25786009)(2616005)(1076002)(14444005)(6506007)(186003)(6346003)(11346002)(446003)(26005)(2900100001)(6116002)(486006)(102836004)(256004)(107886003)(476003)(86612001)(86362001)(2501003)(14454004)(97736004)(66066001)(76176011)(6666003)(316002)(54906003)(110136005)(99286004)(68736007)(10090500001)(22452003)(81156014)(2906002)(36756003)(8676002)(8936002)(81166006)(7736002)(305945005)(105586002)(5660300001)(106356001)(10290500003)(478600001)(72206003)(5250100002);DIR:OUT;SFP:1102;SCL:1;SRVR:CY4PR21MB0742;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: vdHF9JOrTUUpSeyDm3YKyniIHI6anM9nAgjf1XlMwPk0M+ag6BlKTcylJhpu1gQjRQGI3F7qVX4PFPhI3rXIYh0lf8YKFBdLv/BdKbvxiK3IDKl1UOC6rTRhLD/a9AU3FgeNwUN/gZeE/+VKVwMzq9k8zxTZpuXsOb6aJ9oI/pH5qoYEPVJ1CDtxkSCD6ZrF2/+s4EV4lhqtlfbiHmUea/XSjZM3dQaRi9aobsCx46uWk6587meo+1hz25VOK5PegPU0NUOoYrjTdfcc6uhs5RpVjDNhlTF0uWaypZL5evCwI3fqeoRohNa5ctTnUrmPjIG78kCBpNFqQ+FWVD7YK7n8t0W43V48hpXgTzGebac= 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: 8afcae77-4c33-4084-5f38-08d61c4aa73c X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Sep 2018 03:05:00.1017 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0742 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