From patchwork Mon Aug 3 10:04:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanley Chu X-Patchwork-Id: 11697827 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9423C14B7 for ; Mon, 3 Aug 2020 10:04:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79A4520678 for ; Mon, 3 Aug 2020 10:04:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="Z9X8s/am" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726125AbgHCKE4 (ORCPT ); Mon, 3 Aug 2020 06:04:56 -0400 Received: from mailgw01.mediatek.com ([210.61.82.183]:52034 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726007AbgHCKE4 (ORCPT ); Mon, 3 Aug 2020 06:04:56 -0400 X-UUID: 64283b4175cc439f8301b6859f390715-20200803 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=9uXB7CfOtYtYRWovnKzlo2DYGcJuja1YS8PgGiAgL68=; b=Z9X8s/amDLga6k7+LnXM2iukGWAhlzT/xf1AJmLCUmX69BC7pHY/XQjXs0cXvFcXYLkKDv2qaYzYd+Ugd6GmYQO8mz1Gr2hUUClJgcAJACrV1Gr9WLmFdcGA//iC1hhLuZHY+KCdnC6aCTp8O1iQCUDzzX8RlvlQ4C8p/UHHBjI=; X-UUID: 64283b4175cc439f8301b6859f390715-20200803 Received: from mtkcas06.mediatek.inc [(172.21.101.30)] by mailgw01.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 193023054; Mon, 03 Aug 2020 18:04:51 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs02n2.mediatek.inc (172.21.101.101) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 3 Aug 2020 18:04:47 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 3 Aug 2020 18:04:47 +0800 From: Stanley Chu To: , , , , , , CC: , , , , , , , , , , , , , Stanley Chu Subject: [PATCH v7] scsi: ufs: Quiesce all scsi devices before shutdown Date: Mon, 3 Aug 2020 18:04:48 +0800 Message-ID: <20200803100448.2738-1-stanley.chu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: 0752CF73C08E36F99AA4AE3C4C4439F01E08ABB0F4EB780CBF1B73425E7CBCF92000:8 X-MTK: N Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Currently I/O request could be still submitted to UFS device while UFS is working on shutdown flow. This may lead to racing as below scenarios and finally system may crash due to unclocked register accesses. To fix this kind of issues, in ufshcd_shutdown(), 1. Use pm_runtime_get_sync() instead of resuming UFS device by ufshcd_runtime_resume() "internally" to let runtime PM framework manage and prevent concurrent runtime operations by incoming I/O requests. 2. Specifically quiesce all SCSI devices to block all I/O requests after device is resumed. Example of racing scenario: While UFS device is runtime-suspended Thread #1: Executing UFS shutdown flow, e.g., ufshcd_suspend(UFS_SHUTDOWN_PM) Thread #2: Executing runtime resume flow triggered by I/O request, e.g., ufshcd_resume(UFS_RUNTIME_PM) This breaks the assumption that UFS PM flows can not be running concurrently and some unexpected racing behavior may happen. Signed-off-by: Stanley Chu --- Changes: - Since v6: - Do quiesce to all SCSI devices. - Since v4: - Use pm_runtime_get_sync() instead of resuming UFS device by ufshcd_runtime_resume() "internally". --- drivers/scsi/ufs/ufshcd.c | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 307622284239..7cb220b3fde0 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -8640,6 +8640,7 @@ EXPORT_SYMBOL(ufshcd_runtime_idle); int ufshcd_shutdown(struct ufs_hba *hba) { int ret = 0; + struct scsi_target *starget; if (!hba->is_powered) goto out; @@ -8647,11 +8648,27 @@ int ufshcd_shutdown(struct ufs_hba *hba) if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba)) goto out; - if (pm_runtime_suspended(hba->dev)) { - ret = ufshcd_runtime_resume(hba); - if (ret) - goto out; - } + /* + * Let runtime PM framework manage and prevent concurrent runtime + * operations with shutdown flow. + */ + pm_runtime_get_sync(hba->dev); + + /* + * Quiesce all SCSI devices to prevent any non-PM requests sending + * from block layer during and after shutdown. + * + * Here we can not use blk_cleanup_queue() since PM requests + * (with BLK_MQ_REQ_PREEMPT flag) are still required to be sent + * through block layer. Therefore SCSI command queued after the + * scsi_target_quiesce() call returned will block until + * blk_cleanup_queue() is called. + * + * Besides, scsi_target_"un"quiesce (e.g., scsi_target_resume) can + * be ignored since shutdown is one-way flow. + */ + list_for_each_entry(starget, &hba->host->__targets, siblings) + scsi_target_quiesce(starget); ret = ufshcd_suspend(hba, UFS_SHUTDOWN_PM); out: