[PATCH AUTOSEL 5.4 050/130] scsi: ufs: Atomic update for clkgating_enable

Sasha Levin
2020-12-23T03:02:22Z

From: Jaegeuk Kim <jaegeuk@google.com>

[ Upstream commit b664511297644eac34038df877b3ad7bcaa81913 ]

While running a stress test which enables/disables clkgating, we
occasionally hit device timeout. This patch avoids a subtle race condition
to address it.

Link: https://lore.kernel.org/r/20201117165839.1643377-3-jaegeuk@kernel.org
Reviewed-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 675e16e61ebdd..ed07e52fa861b 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1751,19 +1751,19 @@ 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)
+ __ufshcd_release(hba);
+ 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;
}

--
2.27.0