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=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 564B9C43331 for ; Wed, 13 Nov 2019 00:11:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 205222196E for ; Wed, 13 Nov 2019 00:11:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="UvI38DDL"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="UGc03Wdn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726983AbfKMALg (ORCPT ); Tue, 12 Nov 2019 19:11:36 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:44186 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726973AbfKMALg (ORCPT ); Tue, 12 Nov 2019 19:11:36 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 23F446078F; Wed, 13 Nov 2019 00:11:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1573603895; bh=oyxH/dC6pgsEGDaB+104nVw9jyny1694Gg5kqtyjstk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=UvI38DDLIbWjJnu8zMQ9e5w3qgapp0hTOKOz2WRkb4pcSpdmYrZAj/BJlhDnbuSFy GF7b7u35pTRnb3qZv4pqqJIFGBEqkcndY5gM5JnC3MhtxoEMEcgvmhmQaZO3Nl9zLw fccC1lVxYFUiLSRmTayUm2IOePGt1jacsElbLODQ= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 4C560602C8; Wed, 13 Nov 2019 00:11:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1573603892; bh=oyxH/dC6pgsEGDaB+104nVw9jyny1694Gg5kqtyjstk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=UGc03WdnlMFChwN94BNjgmybRILikVw9op7foLPBpirXJL26k3f113pCASIg85hH3 CaTGgXLFTyi8Gq+mj+43Cw/TGmB3rwVLgWbELYM91gjCJloGDNY8g4LHze+PT1b502 m0uwGvquZeX1eXphtiD6FKyw4ftCoLEylUYwCUxo= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 13 Nov 2019 08:11:32 +0800 From: cang@codeaurora.org To: Bart Van Assche Cc: "Martin K . Petersen" , "James E . J . Bottomley" , Bean Huo , Avri Altman , Asutosh Das , Vignesh Raghavendra , linux-scsi@vger.kernel.org, Stanley Chu , Tomas Winkler Subject: Re: [PATCH v5 4/4] ufs: Simplify the clock scaling mechanism implementation In-Reply-To: <20191112173743.141503-5-bvanassche@acm.org> References: <20191112173743.141503-1-bvanassche@acm.org> <20191112173743.141503-5-bvanassche@acm.org> Message-ID: X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2019-11-13 01:37, Bart Van Assche wrote: > Scaling the clock is only safe while no commands are in progress. Use > blk_mq_{un,}freeze_queue() to block submission of new commands and to > wait for ongoing commands to complete. Remove "_scsi" from the name of > the functions that block and unblock requests since these functions > now block both SCSI commands and non-SCSI commands. > > Cc: Bean Huo > Cc: Avri Altman > Cc: Stanley Chu > Cc: Tomas Winkler > Signed-off-by: Bart Van Assche > --- > drivers/scsi/ufs/ufshcd.c | 141 +++++++++++++------------------------- > drivers/scsi/ufs/ufshcd.h | 3 - > 2 files changed, 46 insertions(+), 98 deletions(-) > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index 810b997f55fc..717ba24a2d40 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -290,16 +290,50 @@ static inline void ufshcd_disable_irq(struct > ufs_hba *hba) > } > } > > -static void ufshcd_scsi_unblock_requests(struct ufs_hba *hba) > +static void ufshcd_unblock_requests(struct ufs_hba *hba) > { > - if (atomic_dec_and_test(&hba->scsi_block_reqs_cnt)) > - scsi_unblock_requests(hba->host); > + struct scsi_device *sdev; > + > + blk_mq_unfreeze_queue(hba->tmf_queue); > + blk_mq_unfreeze_queue(hba->cmd_queue); > + shost_for_each_device(sdev, hba->host) > + blk_mq_unfreeze_queue(sdev->request_queue); > } > > -static void ufshcd_scsi_block_requests(struct ufs_hba *hba) > +static int ufshcd_block_requests(struct ufs_hba *hba, unsigned long > timeout) > { > - if (atomic_inc_return(&hba->scsi_block_reqs_cnt) == 1) > - scsi_block_requests(hba->host); > + struct scsi_device *sdev; > + unsigned long deadline = jiffies + timeout; > + > + if (timeout == ULONG_MAX) { > + shost_for_each_device(sdev, hba->host) > + blk_mq_freeze_queue(sdev->request_queue); > + blk_mq_freeze_queue(hba->cmd_queue); > + blk_mq_freeze_queue(hba->tmf_queue); > + return 0; > + } > + > + shost_for_each_device(sdev, hba->host) > + blk_freeze_queue_start(sdev->request_queue); > + blk_freeze_queue_start(hba->cmd_queue); > + blk_freeze_queue_start(hba->tmf_queue); > + shost_for_each_device(sdev, hba->host) { > + if (blk_mq_freeze_queue_wait_timeout(sdev->request_queue, > + max_t(long, 0, deadline - jiffies)) <= 0) { > + goto err; > + } > + } > + if (blk_mq_freeze_queue_wait_timeout(hba->cmd_queue, > + max_t(long, 0, deadline - jiffies)) <= 0) > + goto err; > + if (blk_mq_freeze_queue_wait_timeout(hba->tmf_queue, > + max_t(long, 0, deadline - jiffies)) <= 0) > + goto err; > + return 0; > + > +err: > + ufshcd_unblock_requests(hba); > + return -ETIMEDOUT; > } > > static void ufshcd_add_cmd_upiu_trace(struct ufs_hba *hba, unsigned > int tag, > @@ -971,65 +1005,6 @@ static bool > ufshcd_is_devfreq_scaling_required(struct ufs_hba *hba, > return false; > } > > -static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba, > - u64 wait_timeout_us) > -{ > - unsigned long flags; > - int ret = 0; > - u32 tm_doorbell; > - u32 tr_doorbell; > - bool timeout = false, do_last_check = false; > - ktime_t start; > - > - ufshcd_hold(hba, false); > - spin_lock_irqsave(hba->host->host_lock, flags); > - /* > - * Wait for all the outstanding tasks/transfer requests. > - * Verify by checking the doorbell registers are clear. > - */ > - start = ktime_get(); > - do { > - if (hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL) { > - ret = -EBUSY; > - goto out; > - } > - > - tm_doorbell = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL); > - tr_doorbell = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL); > - if (!tm_doorbell && !tr_doorbell) { > - timeout = false; > - break; > - } else if (do_last_check) { > - break; > - } > - > - spin_unlock_irqrestore(hba->host->host_lock, flags); > - schedule(); > - if (ktime_to_us(ktime_sub(ktime_get(), start)) > > - wait_timeout_us) { > - timeout = true; > - /* > - * We might have scheduled out for long time so make > - * sure to check if doorbells are cleared by this time > - * or not. > - */ > - do_last_check = true; > - } > - spin_lock_irqsave(hba->host->host_lock, flags); > - } while (tm_doorbell || tr_doorbell); > - > - if (timeout) { > - dev_err(hba->dev, > - "%s: timedout waiting for doorbell to clear (tm=0x%x, tr=0x%x)\n", > - __func__, tm_doorbell, tr_doorbell); > - ret = -EBUSY; > - } > -out: > - spin_unlock_irqrestore(hba->host->host_lock, flags); > - ufshcd_release(hba); > - return ret; > -} > - > /** > * ufshcd_scale_gear - scale up/down UFS gear > * @hba: per adapter instance > @@ -1079,27 +1054,16 @@ static int ufshcd_scale_gear(struct ufs_hba > *hba, bool scale_up) > > static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba) > { > - #define DOORBELL_CLR_TOUT_US (1000 * 1000) /* 1 sec */ > - int ret = 0; > /* > * make sure that there are no outstanding requests when > * clock scaling is in progress > */ > - ufshcd_scsi_block_requests(hba); > - down_write(&hba->clk_scaling_lock); > - if (ufshcd_wait_for_doorbell_clr(hba, DOORBELL_CLR_TOUT_US)) { > - ret = -EBUSY; > - up_write(&hba->clk_scaling_lock); > - ufshcd_scsi_unblock_requests(hba); > - } > - > - return ret; > + return ufshcd_block_requests(hba, HZ); > } > > static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba) > { > - up_write(&hba->clk_scaling_lock); > - ufshcd_scsi_unblock_requests(hba); > + ufshcd_unblock_requests(hba); > } > > /** > @@ -1471,7 +1435,7 @@ static void ufshcd_ungate_work(struct work_struct > *work) > hba->clk_gating.is_suspended = false; > } > unblock_reqs: > - ufshcd_scsi_unblock_requests(hba); > + ufshcd_unblock_requests(hba); > } > > /** > @@ -1528,7 +1492,7 @@ int ufshcd_hold(struct ufs_hba *hba, bool async) > */ > /* fallthrough */ > case CLKS_OFF: > - ufshcd_scsi_block_requests(hba); > + ufshcd_block_requests(hba, ULONG_MAX); Hi Bart, ufshcd_hold(async == true) is used in ufshcd_queuecommand() path because ufshcd_queuecommand() can be entered under atomic contexts. Thus ufshcd_block_requests() here has the same risk causing scheduling while atomic. FYI, it is not easy to hit above scenario in small scale of test. Best Regards, Can Guo. > hba->clk_gating.state = REQ_CLKS_ON; > trace_ufshcd_clk_gating(dev_name(hba->dev), > hba->clk_gating.state); > @@ -2395,9 +2359,6 @@ static int ufshcd_queuecommand(struct Scsi_Host > *host, struct scsi_cmnd *cmd) > BUG(); > } > > - if (!down_read_trylock(&hba->clk_scaling_lock)) > - return SCSI_MLQUEUE_HOST_BUSY; > - > spin_lock_irqsave(hba->host->host_lock, flags); > switch (hba->ufshcd_state) { > case UFSHCD_STATE_OPERATIONAL: > @@ -2463,7 +2424,6 @@ static int ufshcd_queuecommand(struct Scsi_Host > *host, struct scsi_cmnd *cmd) > out_unlock: > spin_unlock_irqrestore(hba->host->host_lock, flags); > out: > - up_read(&hba->clk_scaling_lock); > return err; > } > > @@ -2617,8 +2577,6 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba > *hba, > struct completion wait; > unsigned long flags; > > - down_read(&hba->clk_scaling_lock); > - > /* > * Get free slot, sleep if slots are unavailable. > * Even though we use wait_event() which sleeps indefinitely, > @@ -2654,7 +2612,6 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba > *hba, > > out_put_tag: > blk_put_request(req); > - up_read(&hba->clk_scaling_lock); > return err; > } > > @@ -5342,7 +5299,7 @@ static void ufshcd_err_handler(struct work_struct > *work) > spin_unlock_irqrestore(hba->host->host_lock, flags); > if (starget) > scsi_target_unblock(&starget->dev, SDEV_RUNNING); > - ufshcd_scsi_unblock_requests(hba); > + scsi_unblock_requests(hba->host); > ufshcd_release(hba); > pm_runtime_put_sync(hba->dev); > } > @@ -5466,7 +5423,7 @@ static void ufshcd_check_errors(struct ufs_hba > *hba) > /* handle fatal errors only when link is functional */ > if (hba->ufshcd_state == UFSHCD_STATE_OPERATIONAL) { > /* block commands from scsi mid-layer */ > - ufshcd_scsi_block_requests(hba); > + scsi_block_requests(hba->host); > > hba->ufshcd_state = UFSHCD_STATE_EH_SCHEDULED; > > @@ -5772,8 +5729,6 @@ static int ufshcd_issue_devman_upiu_cmd(struct > ufs_hba *hba, > unsigned long flags; > u32 upiu_flags; > > - down_read(&hba->clk_scaling_lock); > - > req = blk_get_request(q, REQ_OP_DRV_OUT, 0); > if (IS_ERR(req)) > return PTR_ERR(req); > @@ -5853,7 +5808,6 @@ static int ufshcd_issue_devman_upiu_cmd(struct > ufs_hba *hba, > } > > blk_put_request(req); > - up_read(&hba->clk_scaling_lock); > return err; > } > > @@ -8322,8 +8276,6 @@ int ufshcd_init(struct ufs_hba *hba, void > __iomem *mmio_base, unsigned int irq) > /* Initialize mutex for device management commands */ > mutex_init(&hba->dev_cmd.lock); > > - init_rwsem(&hba->clk_scaling_lock); > - > ufshcd_init_clk_gating(hba); > > ufshcd_init_clk_scaling(hba); > @@ -8410,7 +8362,6 @@ int ufshcd_init(struct ufs_hba *hba, void > __iomem *mmio_base, unsigned int irq) > > /* Hold auto suspend until async scan completes */ > pm_runtime_get_sync(dev); > - atomic_set(&hba->scsi_block_reqs_cnt, 0); > /* > * We are assuming that device wasn't put in sleep/power-down > * state exclusively during the boot stage before kernel. > diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h > index 5865e16f53a6..c44bfcdb26a3 100644 > --- a/drivers/scsi/ufs/ufshcd.h > +++ b/drivers/scsi/ufs/ufshcd.h > @@ -520,7 +520,6 @@ struct ufs_stats { > * @urgent_bkops_lvl: keeps track of urgent bkops level for device > * @is_urgent_bkops_lvl_checked: keeps track if the urgent bkops level > for > * device is known or not. > - * @scsi_block_reqs_cnt: reference counting for scsi block requests > */ > struct ufs_hba { > void __iomem *mmio_base; > @@ -724,9 +723,7 @@ struct ufs_hba { > enum bkops_status urgent_bkops_lvl; > bool is_urgent_bkops_lvl_checked; > > - struct rw_semaphore clk_scaling_lock; > struct ufs_desc_size desc_size; > - atomic_t scsi_block_reqs_cnt; > > struct device bsg_dev; > struct request_queue *bsg_queue;