From patchwork Thu May 3 11:07:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Asutosh Das (asd)" X-Patchwork-Id: 10377815 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B7CA9603B4 for ; Thu, 3 May 2018 11:15:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AFE0B28AB3 for ; Thu, 3 May 2018 11:15:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A3FA32907D; Thu, 3 May 2018 11:15:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3B1B128AB3 for ; Thu, 3 May 2018 11:15:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751874AbeECLPR (ORCPT ); Thu, 3 May 2018 07:15:17 -0400 Received: from alexa-out-tai-02.qualcomm.com ([103.229.16.227]:53487 "EHLO alexa-out-tai-02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492AbeECLOT (ORCPT ); Thu, 3 May 2018 07:14:19 -0400 X-Greylist: delayed 375 seconds by postgrey-1.27 at vger.kernel.org; Thu, 03 May 2018 07:14:07 EDT X-IronPort-AV: E=Sophos;i="5.49,358,1520870400"; d="scan'208";a="447820" Received: from ironmsg03-tai.qualcomm.com ([10.249.140.8]) by alexa-out-tai-02.qualcomm.com with ESMTP; 03 May 2018 19:07:54 +0800 X-IronPort-AV: E=McAfee;i="5900,7806,8881"; a="7258976" Received: from asutoshd-linux.qualcomm.com ([10.206.24.163]) by ironmsg03-tai.qualcomm.com with ESMTP; 03 May 2018 19:07:41 +0800 Received: by asutoshd-linux.qualcomm.com (Postfix, from userid 92687) id 80E0E2E8C; Thu, 3 May 2018 16:37:38 +0530 (IST) 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, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 06/10] scsi: ufs: add reference counting for scsi block requests Date: Thu, 3 May 2018 16:37:18 +0530 Message-Id: <3d524952ffe2c0a14c92f5e322aed5d2c24c2832.1525343531.git.asutoshd@codeaurora.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Subhash Jadavani Currently we call the scsi_block_requests()/scsi_unblock_requests() whenever we want to block/unblock scsi requests but as there is no reference counting, nesting of these calls could leave us in undesired state sometime. Consider following call flow sequence: 1. func1() calls scsi_block_requests() but calls func2() before calling scsi_unblock_requests() 2. func2() calls scsi_block_requests() 3. func2() calls scsi_unblock_requests() 4. func1() calls scsi_unblock_requests() As there is no reference counting, we will have scsi requests unblocked after #3 instead of it to be unblocked only after #4. Though we may not have failures seen with this, we might run into some failures in future. Better solution would be to fix this by adding reference counting. Signed-off-by: Subhash Jadavani Signed-off-by: Can Guo Signed-off-by: Asutosh Das --- drivers/scsi/ufs/ufshcd.c | 28 ++++++++++++++++++++-------- drivers/scsi/ufs/ufshcd.h | 2 ++ 2 files changed, 22 insertions(+), 8 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index dfeb194..c35a076 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -264,6 +264,18 @@ static inline void ufshcd_disable_irq(struct ufs_hba *hba) } } +static void ufshcd_scsi_unblock_requests(struct ufs_hba *hba) +{ + if (atomic_dec_and_test(&hba->scsi_block_reqs_cnt)) + scsi_unblock_requests(hba->host); +} + +static void ufshcd_scsi_block_requests(struct ufs_hba *hba) +{ + if (atomic_inc_return(&hba->scsi_block_reqs_cnt) == 1) + scsi_block_requests(hba->host); +} + /* replace non-printable or non-ASCII characters with spaces */ static inline void ufshcd_remove_non_printable(char *val) { @@ -1077,12 +1089,12 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba) * make sure that there are no outstanding requests when * clock scaling is in progress */ - scsi_block_requests(hba->host); + 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); - scsi_unblock_requests(hba->host); + ufshcd_scsi_unblock_requests(hba); } return ret; @@ -1091,7 +1103,7 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba) static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba) { up_write(&hba->clk_scaling_lock); - scsi_unblock_requests(hba->host); + ufshcd_scsi_unblock_requests(hba); } /** @@ -1411,7 +1423,7 @@ static void ufshcd_ungate_work(struct work_struct *work) hba->clk_gating.is_suspended = false; } unblock_reqs: - scsi_unblock_requests(hba->host); + ufshcd_scsi_unblock_requests(hba); } /** @@ -1467,7 +1479,7 @@ int ufshcd_hold(struct ufs_hba *hba, bool async) * work and to enable clocks. */ case CLKS_OFF: - scsi_block_requests(hba->host); + ufshcd_scsi_block_requests(hba); hba->clk_gating.state = REQ_CLKS_ON; trace_ufshcd_clk_gating(dev_name(hba->dev), hba->clk_gating.state); @@ -5192,7 +5204,7 @@ static void ufshcd_err_handler(struct work_struct *work) out: spin_unlock_irqrestore(hba->host->host_lock, flags); - scsi_unblock_requests(hba->host); + ufshcd_scsi_unblock_requests(hba); ufshcd_release(hba); pm_runtime_put_sync(hba->dev); } @@ -5294,7 +5306,7 @@ 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 */ - scsi_block_requests(hba->host); + ufshcd_scsi_block_requests(hba); hba->ufshcd_state = UFSHCD_STATE_EH_SCHEDULED; @@ -8017,7 +8029,7 @@ 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 0417c42..76c31d5 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -498,6 +498,7 @@ 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; @@ -698,6 +699,7 @@ struct ufs_hba { struct rw_semaphore clk_scaling_lock; struct ufs_desc_size desc_size; + atomic_t scsi_block_reqs_cnt; }; /* Returns true if clocks can be gated. Otherwise false */