Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757570AbcJRALV (ORCPT ); Mon, 17 Oct 2016 20:11:21 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:44026 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030473AbcJRAK7 (ORCPT ); Mon, 17 Oct 2016 20:10:59 -0400 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org F0250617BF Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=subhashj@codeaurora.org From: Subhash Jadavani To: vinholikatti@gmail.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com Cc: Venkat Gopalakrishnan , Subhash Jadavani , linux-scsi@vger.kernel.org (open list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER), linux-kernel@vger.kernel.org (open list) Subject: [PATCH v1 10/11] scsi: ufshcd: Fix race between clk scaling and ungate work Date: Mon, 17 Oct 2016 17:10:53 -0700 Message-Id: <1476749453-11446-1-git-send-email-subhashj@codeaurora.org> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2079 Lines: 65 From: Venkat Gopalakrishnan The ungate work turns on the clock before it exits hibern8, if the link was put in hibern8 during clock gating work. There occurs a race condition when clock scaling work calls ufshcd_hold() to make sure low power states cannot be entered, but that returns by checking only whether the clocks are on. This causes the clock scaling work to issue UIC commands when the link is in hibern8 causing failures. Make sure we exit hibern8 state before returning from ufshcd_hold(). Callstacks for race condition: ufshcd_scale_gear ufshcd_devfreq_scale ufshcd_devfreq_target update_devfreq devfreq_monitor process_one_work worker_thread kthread ret_from_fork ufshcd_uic_hibern8_exit ufshcd_ungate_work process_one_work worker_thread kthread ret_from_fork Signed-off-by: Venkat Gopalakrishnan Signed-off-by: Subhash Jadavani --- drivers/scsi/ufs/ufshcd.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index ea97fd0..7959793 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -675,6 +675,21 @@ int ufshcd_hold(struct ufs_hba *hba, bool async) start: switch (hba->clk_gating.state) { case CLKS_ON: + /* + * Wait for the ungate work to complete if in progress. + * Though the clocks may be in ON state, the link could + * still be in hibner8 state if hibern8 is allowed + * during clock gating. + * Make sure we exit hibern8 state also in addition to + * clocks being ON. + */ + if (ufshcd_can_hibern8_during_gating(hba) && + ufshcd_is_link_hibern8(hba)) { + spin_unlock_irqrestore(hba->host->host_lock, flags); + flush_work(&hba->clk_gating.ungate_work); + spin_lock_irqsave(hba->host->host_lock, flags); + goto start; + } break; case REQ_CLKS_OFF: if (cancel_delayed_work(&hba->clk_gating.gate_work)) { -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project