2020-11-17 17:03:44

by Jaegeuk Kim

Subject: [PATCH v5 2/7] scsi: ufs: atomic update for clkgating_enable

From: Jaegeuk Kim <[email protected]>

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 <[email protected]>
---
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;
}

--
2.29.2.299.gdc1121823c-goog

2020-11-18 03:58:46

by Can Guo

Subject: Re: [PATCH v5 2/7] scsi: ufs: atomic update for clkgating_enable

On 2020-11-18 00:58, Jaegeuk Kim wrote:
> From: Jaegeuk Kim <[email protected]>
>
> 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 <[email protected]>

Reviewed-by: Can Guo <[email protected]>

> ---
> 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;
> }