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Sat, 11 Jul 2020 17:31:17 -0800 Received: from MTKMBS02N1.mediatek.inc (172.21.101.77) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 11 Jul 2020 18:31:15 -0700 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs02n1.mediatek.inc (172.21.101.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sun, 12 Jul 2020 09:31:07 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sun, 12 Jul 2020 09:31:07 +0800 Message-ID: <1594517468.10600.35.camel@mtkswgap22> Subject: Re: [RFC PATCH v3] scsi: ufs: Quiesce all scsi devices before shutdown From: Stanley Chu To: Date: Sun, 12 Jul 2020 09:31:08 +0800 In-Reply-To: <20200706132218.21171-1-stanley.chu@mediatek.com> References: <20200706132218.21171-1-stanley.chu@mediatek.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200711_213123_973171_07BBC122 X-CRM114-Status: GOOD ( 20.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bvanassche@acm.org, martin.petersen@oracle.com, andy.teng@mediatek.com, jejb@linux.ibm.com, chun-hung.wu@mediatek.com, kuohong.wang@mediatek.com, linux-kernel@vger.kernel.org, avri.altman@wdc.com, cang@codeaurora.org, linux-mediatek@lists.infradead.org, peter.wang@mediatek.com, alim.akhtar@samsung.com, matthias.bgg@gmail.com, asutoshd@codeaurora.org, chaotian.jing@mediatek.com, cc.chou@mediatek.com, linux-arm-kernel@lists.infradead.org, beanhuo@micron.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Bart, Avri, May I know if you have any suggestion for this RFC fix? Very appreciated : ) On Mon, 2020-07-06 at 21:22 +0800, Stanley Chu wrote: > Currently I/O request could be still submitted to UFS device while > UFS is working on shutdown flow. This may lead to racing as below > scenarios and finally system may crash due to unclocked register > accesses. > > To fix this kind of issues, specifically quiesce all SCSI devices > before UFS shutdown to block all I/O request sending from block > layer. > > Example of racing scenario: While UFS device is runtime-suspended > > Thread #1: Executing UFS shutdown flow, e.g., > ufshcd_suspend(UFS_SHUTDOWN_PM) > Thread #2: Executing runtime resume flow triggered by I/O request, > e.g., ufshcd_resume(UFS_RUNTIME_PM) > > This breaks the assumption that UFS PM flows can not be running > concurrently and some unexpected racing behavior may happen. > > Signed-off-by: Stanley Chu > --- > drivers/scsi/ufs/ufshcd.c | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index 59358bb75014..104173c03492 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -158,6 +158,12 @@ struct ufs_pm_lvl_states ufs_pm_lvl_states[] = { > {UFS_POWERDOWN_PWR_MODE, UIC_LINK_OFF_STATE}, > }; > > +#define ufshcd_scsi_for_each_sdev(fn) \ > + list_for_each_entry(starget, &hba->host->__targets, siblings) { \ > + __starget_for_each_device(starget, NULL, \ > + fn); \ > + } > + > static inline enum ufs_dev_pwr_mode > ufs_get_pm_lvl_to_dev_pwr_mode(enum ufs_pm_level lvl) > { > @@ -8588,6 +8594,19 @@ int ufshcd_runtime_idle(struct ufs_hba *hba) > } > EXPORT_SYMBOL(ufshcd_runtime_idle); > > +static void ufshcd_cleanup_queue(struct scsi_device *sdev, void *data) > +{ > + if (sdev->request_queue) > + blk_cleanup_queue(sdev->request_queue); > +} > + > +static void ufshcd_quiece_sdev(struct scsi_device *sdev, void *data) > +{ > + /* Suspended devices are already quiecsed and shall be skipped */ > + if (!pm_runtime_suspended(&sdev->sdev_gendev)) > + scsi_device_quiesce(sdev); > +} > + > /** > * ufshcd_shutdown - shutdown routine > * @hba: per adapter instance > @@ -8599,6 +8618,7 @@ EXPORT_SYMBOL(ufshcd_runtime_idle); > int ufshcd_shutdown(struct ufs_hba *hba) > { > int ret = 0; > + struct scsi_target *starget; > > if (!hba->is_powered) > goto out; > @@ -8612,7 +8632,25 @@ int ufshcd_shutdown(struct ufs_hba *hba) > goto out; > } > > + /* > + * Quiesce all SCSI devices to prevent any non-PM requests sending > + * from block layer during and after shutdown. > + * > + * Here we can not use blk_cleanup_queue() since PM requests > + * (with BLK_MQ_REQ_PREEMPT flag) are still required to be sent > + * through block layer. Therefore SCSI command queued after the > + * scsi_target_quiesce() call returned will block until > + * blk_cleanup_queue() is called. > + * > + * Besides, scsi_target_"un"quiesce (e.g., scsi_target_resume) can > + * be ignored since shutdown is one-way flow. > + */ > + ufshcd_scsi_for_each_sdev(ufshcd_quiece_sdev); > + > ret = ufshcd_suspend(hba, UFS_SHUTDOWN_PM); > + > + /* Set queue as dying to not block queueing commands */ > + ufshcd_scsi_for_each_sdev(ufshcd_cleanup_queue); > out: > if (ret) > dev_err(hba->dev, "%s failed, err %d\n", __func__, ret); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel