Re: [PATCH 1/4] scsi: ufs: atomic update for clkgating_enable

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 2020-10-06 06:36, Jaegeuk Kim wrote:
From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>

When giving a stress test which enables/disables clkgating, we hit device timeout sometimes. This patch avoids subtle racy condition to address it.

Cc: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
Cc: Avri Altman <avri.altman@xxxxxxx>
Cc: Can Guo <cang@xxxxxxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
 drivers/scsi/ufs/ufshcd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 1d157ff58d817..d929c3d1e58cc 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1791,19 +1791,19 @@ static ssize_t
ufshcd_clkgate_enable_store(struct device *dev,
 		return -EINVAL;

 	value = !!value;
+
+	spin_lock_irqsave(hba->host->host_lock, flags);
 	if (value == hba->clk_gating.is_enabled)
 		goto out;

-	if (value) {
-		ufshcd_release(hba);
-	} else {
-		spin_lock_irqsave(hba->host->host_lock, flags);
+	if (value)
+		hba->clk_gating.active_reqs--;
+	else
 		hba->clk_gating.active_reqs++;
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
-	}

 	hba->clk_gating.is_enabled = value;
 out:
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	return count;
 }

I agree that we should protect the flag "is_enabled" with spin lock,
but I prefer the old logic of calling ufshcd_release() instead of
just doing hba->clk_gating.active_reqs--, you can use __ufshcd_release(),
which is free of locking.

Thanks,

Can Guo.



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]

  Powered by Linux