From patchwork Tue Mar 8 02:07:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alice Chao X-Patchwork-Id: 12772904 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E6E2C433EF for ; Tue, 8 Mar 2022 02:08:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241893AbiCHCJx (ORCPT ); Mon, 7 Mar 2022 21:09:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231604AbiCHCJw (ORCPT ); Mon, 7 Mar 2022 21:09:52 -0500 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2196763A5; Mon, 7 Mar 2022 18:08:56 -0800 (PST) X-UUID: 87f433136fee49d4a85d9897590e7bb9-20220308 X-UUID: 87f433136fee49d4a85d9897590e7bb9-20220308 Received: from mtkexhb02.mediatek.inc [(172.21.101.103)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 891801972; Tue, 08 Mar 2022 10:08:12 +0800 Received: from mtkcas10.mediatek.inc (172.21.101.39) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.3; Tue, 8 Mar 2022 10:08:10 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas10.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Tue, 8 Mar 2022 10:08:10 +0800 From: Alice Chao To: , , , , , , CC: , , , , , , , , , , , , Subject: [PATCH v2 1/1] scsi: Fix racing between dev init and dev reset Date: Tue, 8 Mar 2022 10:07:26 +0800 Message-ID: <20220308020725.16116-2-alice.chao@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Device reset thread uses kobject_uevent_env() to get kobj.parent after scsi_evt_emit(), and it races with device init thread which calls device_add() to create kobj.parent before kobject_uevent_env(). Device reset call trace: fill_kobj_path kobject_get_path kobject_uevent_env scsi_evt_emit <- add wait_event() scsi_evt_thread Device init call trace: fill_kobj_path kobject_get_path kobject_uevent_env device_add <- create kobj.parent scsi_target_add scsi_sysfs_add_sdev scsi_add_lun scsi_probe_and_add_lun These two jobs are scheduled asynchronously, we can't guaranteed that kobj.parent will be created in device init thread before device reset thread calls kobj_get_path(). To resolve the racing issue between device init thread and device reset thread, we use wait_event() in scsi_evt_emit() to wait for device_add() to complete the creation of kobj.parent. Signed-off-by: Alice Chao --- drivers/scsi/scsi_lib.c | 1 + drivers/scsi/scsi_scan.c | 1 + 2 files changed, 2 insertions(+) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 0a70aa763a96..abf9a71ed77c 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2461,6 +2461,7 @@ static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) break; case SDEV_EVT_POWER_ON_RESET_OCCURRED: envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED"; + wait_event(sdev->host->host_wait, sdev->sdev_gendev.kobj.parent != NULL); break; default: /* do nothing */ diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index f4e6c68ac99e..431f229ac435 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1904,6 +1904,7 @@ static void do_scsi_scan_host(struct Scsi_Host *shost) } else { scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD, SCAN_WILD_CARD, 0); + wake_up(&shost->host_wait); } }