[PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Jaegeuk Kim]

From: Jaegeuk Kim <jaeg...@google.com>

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

Note that, this requires a patch to address the device stuck by REQ_CLKS_OFF in
__ufshcd_release().

The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".

Signed-off-by: Jaegeuk Kim <jaeg...@google.com>
---
 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 cc8d5f0c3fdc..6c9269bffcbd 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1808,19 +1808,19 @@ 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;
 }
 
-- 
2.29.0.rc1.297.gfa9743e501-goog