[PATCH v3 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.

If we use __ufshcd_release(), I've seen that gate_work can be called in parallel
with ungate_work, which results in UFS timeout when doing hibern8.
Should avoid it.

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 b8f573a02713..e0b479f9eb8a 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1807,19 +1807,19 @@ 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;
 }
 
-- 
2.29.0.rc1.297.gfa9743e501-goog