From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751916AbeECLPq (ORCPT ); Thu, 3 May 2018 07:15:46 -0400 Received: from alexa-out-tai-02.qualcomm.com ([103.229.16.227]:53647 "EHLO alexa-out-tai-02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbeECLOR (ORCPT ); Thu, 3 May 2018 07:14:17 -0400 X-IronPort-AV: E=Sophos;i="5.49,358,1520870400"; d="scan'208";a="447818" X-IronPort-AV: E=McAfee;i="5900,7806,8881"; a="7302708" From: Asutosh Das To: subhashj@codeaurora.org, cang@codeaurora.org, vivek.gautam@codeaurora.org, rnayak@codeaurora.org, vinholikatti@gmail.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, asutoshd@codeaurora.org, linux-mmc@vger.kernel.org Cc: linux-scsi@vger.kernel.org, Vijay Viswanath , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 10/10] scsi: ufs: Add clock ungating to a separate workqueue Date: Thu, 3 May 2018 16:37:22 +0530 Message-Id: <0bfae28dbfb4cf86e80435639b92c7f4023041dc.1525343531.git.asutoshd@codeaurora.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vijay Viswanath UFS driver can receive a request during memory reclaim by kswapd. So when ufs driver puts the ungate work in queue, and if there are no idle workers, kthreadd is invoked to create a new kworker. Since kswapd task holds a mutex which kthreadd also needs, this can cause a deadlock situation. So ungate work must be done in a separate work queue with WQ_MEM_RECLAIM flag enabled. Such a workqueue will have a rescue thread which will be called when the above deadlock condition is possible. Signed-off-by: Vijay Viswanath Signed-off-by: Can Guo Signed-off-by: Asutosh Das --- drivers/scsi/ufs/ufshcd.c | 11 ++++++++++- drivers/scsi/ufs/ufshcd.h | 1 + 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 557d538..3be61b7 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -1483,7 +1483,8 @@ int ufshcd_hold(struct ufs_hba *hba, bool async) hba->clk_gating.state = REQ_CLKS_ON; trace_ufshcd_clk_gating(dev_name(hba->dev), hba->clk_gating.state); - schedule_work(&hba->clk_gating.ungate_work); + queue_work(hba->clk_gating.clk_gating_workq, + &hba->clk_gating.ungate_work); /* * fall through to check if we should wait for this * work to be done or not. @@ -1669,6 +1670,8 @@ static ssize_t ufshcd_clkgate_enable_store(struct device *dev, static void ufshcd_init_clk_gating(struct ufs_hba *hba) { + char wq_name[sizeof("ufs_clk_gating_00")]; + if (!ufshcd_is_clkgating_allowed(hba)) return; @@ -1676,6 +1679,11 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba) INIT_DELAYED_WORK(&hba->clk_gating.gate_work, ufshcd_gate_work); INIT_WORK(&hba->clk_gating.ungate_work, ufshcd_ungate_work); + snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_gating_%d", + hba->host->host_no); + hba->clk_gating.clk_gating_workq = alloc_ordered_workqueue(wq_name, + WQ_MEM_RECLAIM); + hba->clk_gating.is_enabled = true; hba->clk_gating.delay_attr.show = ufshcd_clkgate_delay_show; @@ -1703,6 +1711,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba) device_remove_file(hba->dev, &hba->clk_gating.enable_attr); cancel_work_sync(&hba->clk_gating.ungate_work); cancel_delayed_work_sync(&hba->clk_gating.gate_work); + destroy_workqueue(hba->clk_gating.clk_gating_workq); } /* Must be called with host lock acquired */ diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index 76c31d5..2e6bdc0 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -361,6 +361,7 @@ struct ufs_clk_gating { struct device_attribute enable_attr; bool is_enabled; int active_reqs; + struct workqueue_struct *clk_gating_workq; }; struct ufs_saved_pwr_info { -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.