From patchwork Wed Jul 27 03:21:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?UGV0ZXIgV2FuZyAo546L5L+h5Y+LKQ==?= X-Patchwork-Id: 12930002 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 DC105C19F2B for ; Wed, 27 Jul 2022 03:21:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240292AbiG0DVU (ORCPT ); Tue, 26 Jul 2022 23:21:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240280AbiG0DVS (ORCPT ); Tue, 26 Jul 2022 23:21:18 -0400 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5FBBD248E8; Tue, 26 Jul 2022 20:21:17 -0700 (PDT) X-UUID: 1429017a8fbf4357885e2b24aa255190-20220727 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.8,REQID:40db339d-f865-4c48-9ede-34f63baad5d3,OB:0,LO B:0,IP:0,URL:5,TC:0,Content:-5,EDM:0,RT:0,SF:0,FILE:0,RULE:Release_Ham,ACT ION:release,TS:0 X-CID-META: VersionHash:0f94e32,CLOUDID:3a6e20ee-db04-4499-9fdf-04ef44b9468c,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:1,File:nil ,QS:nil,BEC:nil,COL:0 X-UUID: 1429017a8fbf4357885e2b24aa255190-20220727 Received: from mtkmbs10n2.mediatek.inc [(172.21.101.183)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1129967393; Wed, 27 Jul 2022 11:21:12 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Wed, 27 Jul 2022 11:21:11 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Wed, 27 Jul 2022 11:21:11 +0800 From: To: , , , , , CC: , , , , , , , , , , , Subject: [PATCH v4] ufs: core: fix lockdep warning of clk_scaling_lock Date: Wed, 27 Jul 2022 11:21:10 +0800 Message-ID: <20220727032110.31168-1-peter.wang@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 From: Peter Wang There have a lockdep warning like below in current flow, and have deadlock issue. kworker/u16:0: Possible unsafe locking scenario: kworker/u16:0: CPU0 CPU1 kworker/u16:0: ---- ---- kworker/u16:0: lock(&hba->clk_scaling_lock); kworker/u16:0: lock(&hba->dev_cmd.lock); kworker/u16:0: lock(&hba->clk_scaling_lock); kworker/u16:0: lock(&hba->dev_cmd.lock); kworker/u16:0: Before this patch clk_scaling_lock was held in reader mode during the ufshcd_wb_toggle() call. With this patch applied clk_scaling_lock is not held while ufshcd_wb_toggle() is called. This is safe because ufshcd_wb_toggle will held clk_scaling_lock in reader mode "again" in flow ufshcd_wb_toggle -> __ufshcd_wb_toggle -> ufshcd_query_flag_retry -> ufshcd_query_flag -> ufshcd_exec_dev_cmd -> down_read(&hba->clk_scaling_lock); The protect should enough and make sure clock is not change while send command. ufshcd_wb_toggle can protected by hba->clk_scaling.is_allowed to make sure ufshcd_devfreq_scale function not run concurrently. Fixes: 0e9d4ca43ba8 ("scsi: ufs: Protect some contexts from unexpected clock scaling") Cc: # 5.15.x Signed-off-by: Peter Wang --- drivers/ufs/core/ufshcd.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index c7b337480e3e..aa57126fdb49 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -272,6 +272,7 @@ static void ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set); static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable); static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba); static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba); +static void ufshcd_clk_scaling_allow(struct ufs_hba *hba, bool allow); static inline void ufshcd_enable_irq(struct ufs_hba *hba) { @@ -1249,12 +1250,10 @@ 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) - up_write(&hba->clk_scaling_lock); - else - up_read(&hba->clk_scaling_lock); + up_write(&hba->clk_scaling_lock); + ufshcd_scsi_unblock_requests(hba); ufshcd_release(hba); } @@ -1271,7 +1270,7 @@ 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; + bool wb_toggle = false; ret = ufshcd_clock_scaling_prepare(hba); if (ret) @@ -1300,13 +1299,19 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up) } } - /* Enable Write Booster if we have scaled up else disable it */ - downgrade_write(&hba->clk_scaling_lock); - is_writelock = false; - ufshcd_wb_toggle(hba, scale_up); + /* Disable clk_scaling until ufshcd_wb_toggle finish */ + hba->clk_scaling.is_allowed = false; + wb_toggle = true; out_unprepare: - ufshcd_clock_scaling_unprepare(hba, is_writelock); + ufshcd_clock_scaling_unprepare(hba); + + /* Enable Write Booster if we have scaled up else disable it */ + if (wb_toggle) { + ufshcd_wb_toggle(hba, scale_up); + ufshcd_clk_scaling_allow(hba, true); + } + return ret; }