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.
