From patchwork Mon Oct 4 12:06:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adrian Hunter X-Patchwork-Id: 12533807 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1FDDC433EF for ; Mon, 4 Oct 2021 12:10:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CE6B66136F for ; Mon, 4 Oct 2021 12:10:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233106AbhJDMLu (ORCPT ); Mon, 4 Oct 2021 08:11:50 -0400 Received: from mga12.intel.com ([192.55.52.136]:5875 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233102AbhJDMLt (ORCPT ); Mon, 4 Oct 2021 08:11:49 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10126"; a="205532856" X-IronPort-AV: E=Sophos;i="5.85,345,1624345200"; d="scan'208";a="205532856" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2021 05:07:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.85,345,1624345200"; d="scan'208";a="482927097" Received: from ahunter-desktop.fi.intel.com ([10.237.72.76]) by fmsmga007.fm.intel.com with ESMTP; 04 Oct 2021 05:07:13 -0700 From: Adrian Hunter To: "Martin K . Petersen" Cc: "James E . J . Bottomley" , Bean Huo , Avri Altman , Alim Akhtar , Can Guo , Asutosh Das , Bart Van Assche , linux-scsi@vger.kernel.org Subject: [PATCH RFC 4/6] scsi: ufs: Fix a possible dead lock in clock scaling Date: Mon, 4 Oct 2021 15:06:48 +0300 Message-Id: <20211004120650.153218-5-adrian.hunter@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211004120650.153218-1-adrian.hunter@intel.com> References: <20211004120650.153218-1-adrian.hunter@intel.com> MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Instead of downgrade_write(), extend the ufshcd_down_write() to cover ufshcd_wb_toggle() because ufshcd_down_write() now supports nesting ufshcd_down_read() but down_read() nested within down_read() can deadlock. Reported-by: Can Guo Link: https://lore.kernel.org/all/fbc4d03a07f03fe4fbe697813111471f@codeaurora.org Signed-off-by: Adrian Hunter --- drivers/scsi/ufs/ufshcd.c | 12 +++--------- drivers/scsi/ufs/ufshcd.h | 6 ------ 2 files changed, 3 insertions(+), 15 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 3912b74d50ae..64ac9e48c4d7 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -1192,12 +1192,9 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba) return ret; } -static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock) +static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba) { - if (writelock) - ufshcd_up_write(hba); - else - ufshcd_up_read(hba); + ufshcd_up_write(hba); ufshcd_scsi_unblock_requests(hba); ufshcd_release(hba); } @@ -1214,7 +1211,6 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock) static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up) { int ret = 0; - bool is_writelock = true; ret = ufshcd_clock_scaling_prepare(hba); if (ret) @@ -1244,12 +1240,10 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up) } /* Enable Write Booster if we have scaled up else disable it */ - ufshcd_downgrade_write(hba); - is_writelock = false; ufshcd_wb_toggle(hba, scale_up); out_unprepare: - ufshcd_clock_scaling_unprepare(hba, is_writelock); + ufshcd_clock_scaling_unprepare(hba); return ret; } diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index 74891947bb34..47f81eae178c 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -1457,10 +1457,4 @@ static inline void ufshcd_up_write(struct ufs_hba *hba) up_write(&hba->host_rw_sem); } -static inline void ufshcd_downgrade_write(struct ufs_hba *hba) -{ - hba->excl_task = NULL; - downgrade_write(&hba->host_rw_sem); -} - #endif /* End of Header */