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From: Bean Huo <huobean@gmail.com>
To: Can Guo <cang@codeaurora.org>, Stanley Chu <stanley.chu@mediatek.com>
Cc: alim.akhtar@samsung.com, avri.altman@wdc.com,
	asutoshd@codeaurora.org, jejb@linux.ibm.com,
	martin.petersen@oracle.com, beanhuo@micron.com,
	bvanassche@acm.org, tomas.winkler@intel.com,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/7] scsi: ufs: Add "wb_on" sysfs node to control WB on/off
Date: Tue, 22 Dec 2020 23:11:43 +0100	[thread overview]
Message-ID: <28211d08700d1e4876a9aea342e8fcb79534cd2c.camel@gmail.com> (raw)
In-Reply-To: <eb4cd8f151c43e5754bb7725bce3e8ee34a49b51.camel@gmail.com>

On Tue, 2020-12-22 at 21:57 +0100, Bean Huo wrote:
> > > May this operation race with UFS shutdown flow?
> > > 
> > > To be more clear, ufshcd_wb_ctrl() here may be executed after
> > > host 
> > > clock
> > > is disabled by shutdown flow?
> > > 
> > > If yes, we need to avoid it.
> > 
> > I have the same doubt - can user still access sysfs nodes after
> > system
> > starts to run shutdown routines? If yes, then we need to remove all
> > UFS
> > sysfs nodes in ufshcd_shutdown().
> > 
> 
> No, we shouldn't do in this way, user space complains this. I think
> the nodes in the sysfs can be shileded write, but the nodes shouldn't
> be flash of its presence frequently.
> 
> Thanks,
> Bean 
> 
> 
> > Thanks,
> > 
> > Can Guo.


Hi Can
Got your point, you don't want user space to interrupt UFS by sysyfs if
UFS is in power down mode. if this is true, insteading of removing all
sysfs node in ufshcd_shutdown, maybe just add this checkup before
accessing UFS device descriptors/flag/attributes/LU:

for example, for the device descriptor:


diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-
sysfs.c       
index b3bf7fca00e5..881fe1c24a9f 100644
--- a/drivers/scsi/ufs/ufs-sysfs.c
+++ b/drivers/scsi/ufs/ufs-sysfs.c
@@ -262,6 +262,9 @@ static ssize_t ufs_sysfs_read_desc_param(struct
ufs_hba *hba,
        u8 desc_buf[8] = {0};
        int ret;
 
+       if (!ufshcd_is_ufs_dev_active(hba) ||
!ufshcd_is_link_active(hba))
+               return -EACCES;
+

Bean



  reply	other threads:[~2020-12-22 22:12 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-15 23:05 [PATCH v5 0/7] Several changes for UFS WriteBooster Bean Huo
2020-12-15 23:05 ` [PATCH v5 1/7] scsi: ufs: Add "wb_on" sysfs node to control WB on/off Bean Huo
2020-12-22  6:08   ` Stanley Chu
2020-12-22  6:12     ` Can Guo
2020-12-22 20:57       ` Bean Huo
2020-12-22 22:11         ` Bean Huo [this message]
2020-12-23  1:31           ` Can Guo
2020-12-23  8:28             ` Bean Huo
2020-12-23  8:30             ` Bean Huo
2020-12-23  9:11             ` Bean Huo
2020-12-22 20:50     ` Bean Huo
2020-12-22 21:08       ` Bean Huo
2020-12-23 21:52     ` Bean Huo
2020-12-15 23:05 ` [PATCH v5 2/7] docs: ABI: Add wb_on documentation for UFS sysfs Bean Huo
2020-12-15 23:05 ` [PATCH v5 3/7] scsi: ufs: Changes comment in the function ufshcd_wb_probe() Bean Huo
2020-12-15 23:05 ` [PATCH v5 4/7] scsi: ufs: Remove two WB related fields from struct ufs_dev_info Bean Huo
2020-12-16  4:15   ` Stanley Chu
2020-12-15 23:05 ` [PATCH v5 5/7] scsi: ufs: Group UFS WB related flags to " Bean Huo
2020-12-16  4:16   ` Stanley Chu
2020-12-22  6:14   ` Can Guo
2020-12-15 23:05 ` [PATCH v5 6/7] scsi: ufs: Cleanup WB buffer flush toggle implementation Bean Huo
2020-12-16  4:17   ` Stanley Chu
2020-12-22  6:14   ` Can Guo
2020-12-15 23:05 ` [PATCH v5 7/7] scsi: ufs: Keep device active mode only fWriteBoosterBufferFlushDuringHibernate == 1 Bean Huo

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