From: Stanley Chu <stanley.chu@mediatek.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: <linux-scsi@vger.kernel.org>, <martin.petersen@oracle.com>,
<avri.altman@wdc.com>, <alim.akhtar@samsung.com>,
<jejb@linux.ibm.com>, <beanhuo@micron.com>,
<asutoshd@codeaurora.org>, <cang@codeaurora.org>,
<matthias.bgg@gmail.com>, <linux-mediatek@lists.infradead.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <kuohong.wang@mediatek.com>,
<peter.wang@mediatek.com>, <chun-hung.wu@mediatek.com>,
<andy.teng@mediatek.com>, <chaotian.jing@mediatek.com>,
<cc.chou@mediatek.com>
Subject: Re: [RFC PATCH v3] scsi: ufs: Quiesce all scsi devices before shutdown
Date: Wed, 22 Jul 2020 17:18:54 +0800 [thread overview]
Message-ID: <1595409534.27178.19.camel@mtkswgap22> (raw)
In-Reply-To: <2465978d-28d3-e30f-248e-87333c789743@acm.org>
Hi Bart,
On Sat, 2020-07-11 at 20:21 -0700, Bart Van Assche wrote:
> On 2020-07-06 06:22, Stanley Chu wrote:
> > +static void ufshcd_cleanup_queue(struct scsi_device *sdev, void *data)
> > +{
> > + if (sdev->request_queue)
> > + blk_cleanup_queue(sdev->request_queue);
> > +}
>
> No SCSI LLD should ever call blk_cleanup_queue() directly for
> sdev->request_queue. Only the SCSI core should call blk_cleanup_queue()
> directly for that queue.
Got it.
So may I focus on fixing racing first by quiecsing all SCSI devices only
and do not touch blk_cleanup_queue() in UFS driver, just like v2?
> > 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);
> >
>
> What is the purpose of ufshcd_shutdown()? Why does this function exist?
> How about removing the calls to ufshcd_shutdown() and invoking power down
> code from inside sd_suspend_common() instead?
ufshcd_shutdown() configures below things different from or more than
what sd_suspend_common() can do now,
- Set link as OFF state
- Regulator and clock toggling according to required low-power state for
shutdown
- Auto BKOP toggling
- Vendor-specific shutdown flow ...etc.
Therefore UFS shutdown callback would be still required.
Thanks,
Stanley Chu
next prev parent reply other threads:[~2020-07-22 9:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 13:22 [RFC PATCH v3] scsi: ufs: Quiesce all scsi devices before shutdown Stanley Chu
2020-07-12 1:31 ` Stanley Chu
2020-07-12 3:21 ` Bart Van Assche
2020-07-22 9:18 ` Stanley Chu [this message]
2020-07-27 10:46 ` Avri Altman
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