From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A7B6C48BC2 for ; Thu, 24 Jun 2021 02:16:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F066A613AA for ; Thu, 24 Jun 2021 02:16:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229849AbhFXCS4 (ORCPT ); Wed, 23 Jun 2021 22:18:56 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:59086 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229774AbhFXCSz (ORCPT ); Wed, 23 Jun 2021 22:18:55 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1624500997; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=80wRw21hYrKAh7JPxu/zpapRJZdQHIOHCkh9C+b3tEc=; b=GpT0HsJM73iZLJ6VIaPPbOdhfVE+ddUkxGU0tIG0npdONdlQPOGdk2p4CI81AGcwnHI0IuaQ qEvTbNFd7Mc8y7BQNSDNtzRF5+8gvCk4uRXQTGbhdfj3t+FYUlvnedQ+bhcJagWfDx0/SP74 S+52c0AUht+exo6anmu9qP/L3PQ= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyJlNmU5NiIsICJsaW51eC1zY3NpQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-west-2.postgun.com with SMTP id 60d3eaee01dd9a94315a9b49 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 24 Jun 2021 02:16:14 GMT Sender: cang=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 425E9C43143; Thu, 24 Jun 2021 02:16:14 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: cang) by smtp.codeaurora.org (Postfix) with ESMTPSA id 10DB5C433F1; Thu, 24 Jun 2021 02:16:13 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 24 Jun 2021 10:16:12 +0800 From: Can Guo To: Adrian Hunter Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org, hongwus@codeaurora.org, ziqichen@codeaurora.org, linux-scsi@vger.kernel.org, kernel-team@android.com, Alim Akhtar , Avri Altman , "James E.J. Bottomley" , "Martin K. Petersen" , Stanley Chu , Bean Huo , Jaegeuk Kim , open list Subject: Re: [PATCH v4 06/10] scsi: ufs: Remove host_sem used in suspend/resume In-Reply-To: References: <1624433711-9339-1-git-send-email-cang@codeaurora.org> <1624433711-9339-8-git-send-email-cang@codeaurora.org> Message-ID: <9105f328ee6ce916a7f01027b0d28332@codeaurora.org> X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2021-06-23 22:30, Adrian Hunter wrote: > On 23/06/21 10:35 am, Can Guo wrote: >> To protect system suspend/resume from being disturbed by error >> handling, >> instead of using host_sem, let error handler call lock_system_sleep() >> and >> unlock_system_sleep() which achieve the same purpose. Remove the >> host_sem >> used in suspend/resume paths to make the code more readable. >> >> Suggested-by: Bart Van Assche >> Signed-off-by: Can Guo >> --- >> drivers/scsi/ufs/ufshcd.c | 12 +++++++----- >> 1 file changed, 7 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c >> index 3695dd2..a09e4a2 100644 >> --- a/drivers/scsi/ufs/ufshcd.c >> +++ b/drivers/scsi/ufs/ufshcd.c >> @@ -5907,6 +5907,11 @@ static void ufshcd_clk_scaling_suspend(struct >> ufs_hba *hba, bool suspend) >> >> static void ufshcd_err_handling_prepare(struct ufs_hba *hba) >> { >> + /* >> + * It is not safe to perform error handling while suspend or resume >> is >> + * in progress. Hence the lock_system_sleep() call. >> + */ >> + lock_system_sleep(); > > It looks to me like the system takes this lock quite early, even before > freezing tasks, so if anything needs the error handler to run it will > deadlock. Hi Adrian, UFS/hba system suspend/resume does not invoke or call error handling in a synchronous way. So, whatever UFS errors (which schedules the error handler) happens during suspend/resume, error handler will just wait here till system suspend/resume release the lock. Hence no worries of deadlock here. Thanks, Can Guo. > >> ufshcd_rpm_get_sync(hba); >> if (pm_runtime_status_suspended(&hba->sdev_ufs_device->sdev_gendev) >> || >> hba->is_wlu_sys_suspended) { >> @@ -5951,6 +5956,7 @@ static void ufshcd_err_handling_unprepare(struct >> ufs_hba *hba) >> ufshcd_clk_scaling_suspend(hba, false); >> ufshcd_clear_ua_wluns(hba); >> ufshcd_rpm_put(hba); >> + unlock_system_sleep(); >> } >> >> static inline bool ufshcd_err_handling_should_stop(struct ufs_hba >> *hba) >> @@ -9053,16 +9059,13 @@ static int ufshcd_wl_suspend(struct device >> *dev) >> ktime_t start = ktime_get(); >> >> hba = shost_priv(sdev->host); >> - down(&hba->host_sem); >> >> if (pm_runtime_suspended(dev)) >> goto out; >> >> ret = __ufshcd_wl_suspend(hba, UFS_SYSTEM_PM); >> - if (ret) { >> + if (ret) >> dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__, ret); >> - up(&hba->host_sem); >> - } >> >> out: >> if (!ret) >> @@ -9095,7 +9098,6 @@ static int ufshcd_wl_resume(struct device *dev) >> hba->curr_dev_pwr_mode, hba->uic_link_state); >> if (!ret) >> hba->is_wlu_sys_suspended = false; >> - up(&hba->host_sem); >> return ret; >> } >> #endif >>