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: 12772903 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 18A89C433F5 for ; Tue, 8 Mar 2022 02:09:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:CC :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=6z7wb73TI5B+UxzEE4tUU1fDiUSEroUg7/2kVg15gKQ=; b=JU9noJyRMs1ntE oQVlbjwCvvJSME/ilH0j+jsVSzKyILsOkEjJ0ddVNu46kKW/amZlVnPgRghJvH21L3Ynv6CFR1iS6 KidS6/KyGO3kB/ufDga1tq98fnRJIPJiat21kk1qLuDJSkRzJd+4X0tvhyGHruyGRwbqlpRDfqum0 Sgxkk97olntphhnN+MePwTRCijX/FAuQvxZFiFjJECdfVygkMydj1UnXfqe6Uz/ivECkStTnCkDlh kNI9dAIVKpT3cMkh08bzMRWVUXcTtc3EliQEM9ZDUJqaMLX9rFqhUOkSRPN1Z90yvKk/aerpxrrjb puKa4eCoS9kOjOBlKrsg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nRPHv-002QsT-Jz; Tue, 08 Mar 2022 02:09:23 +0000 Received: from mailgw01.mediatek.com ([216.200.240.184]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nRPHi-002Qp0-OG; Tue, 08 Mar 2022 02:09:12 +0000 X-UUID: a321fe6eccb54bdc82e3c7d79f4e9c39-20220307 X-UUID: a321fe6eccb54bdc82e3c7d79f4e9c39-20220307 Received: from mtkcas67.mediatek.inc [(172.29.193.45)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 824697274; Mon, 07 Mar 2022 19:08:14 -0700 Received: from mtkmbs10n2.mediatek.inc (172.21.101.183) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 7 Mar 2022 18:08:12 -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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220307_180910_835504_38451D1F X-CRM114-Status: GOOD ( 10.66 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.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); } }