[v2,3/3] scsi: ufs: Let resume callback return -EBUSY after ufshcd_shutdown
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Message ID 20201224172010.10701-4-huobean@gmail.com
State New, archived
Headers show
Series
  • Two changes of UFS sysfs
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Commit Message

Bean Huo Dec. 24, 2020, 5:20 p.m. UTC
From: Bean Huo <beanhuo@micron.com>

After ufshcd_shutdown(), both UFS device and UFS LINk are powered off,
return '0' will mislead the upper PM layer since the device has not been
successfully resumed yet. This will let pm_runtime_get_sync() caller
mistakenly believe the device/LINK has been resumed, which leads to
request processing timeout that was en-queued later.

To fix this, let ufshcd_system/runtimie_resume() return -EBUSY in case of
hba->is_powered == false.

Signed-off-by: Bean Huo <beanhuo@micron.com>
---
 drivers/scsi/ufs/ufshcd.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

Comments

Bean Huo Jan. 4, 2021, 7:26 p.m. UTC | #1
Hi Rafael

Would you please help to review this patch assoociated with PM resume
callback implementation?
 
Original code that ufshcd_system/runtime_resume returns '0' in case
resume failed due to the UFS device and UFS LINk are powered off(hba-
>is_powered == false).

In the patch 2/3 Add handling of the return value of
pm_runtime_get_sync() is to fix race exists between shudown path and
device access through sysfs node.



Thanks,
Bean


On Thu, 2020-12-24 at 18:20 +0100, Bean Huo wrote:
> From: Bean Huo <beanhuo@micron.com>
> 
> After ufshcd_shutdown(), both UFS device and UFS LINk are powered
> off,
> return '0' will mislead the upper PM layer since the device has not
> been
> successfully resumed yet. This will let pm_runtime_get_sync() caller
> mistakenly believe the device/LINK has been resumed, which leads to
> request processing timeout that was en-queued later.
> 
> To fix this, let ufshcd_system/runtimie_resume() return -EBUSY in
> case of
> hba->is_powered == false.
> 
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e221add25a7e..e1bcac51c01f 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -8950,14 +8950,16 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  		return -EINVAL;
>  	}
>  
> -	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
> +	if (!hba->is_powered || pm_runtime_suspended(hba->dev)) {
>  		/*
>  		 * Let the runtime resume take care of resuming
>  		 * if runtime suspended.
>  		 */
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_SYSTEM_PM);
> +	}
>  out:
>  	trace_ufshcd_system_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),
> @@ -9026,10 +9028,12 @@ int ufshcd_runtime_resume(struct ufs_hba
> *hba)
>  	if (!hba)
>  		return -EINVAL;
>  
> -	if (!hba->is_powered)
> +	if (!hba->is_powered) {
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_RUNTIME_PM);
> +	}
>  out:
>  	trace_ufshcd_runtime_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),
Can Guo Jan. 5, 2021, 1:10 a.m. UTC | #2
On 2020-12-25 01:20, Bean Huo wrote:
> From: Bean Huo <beanhuo@micron.com>
> 
> After ufshcd_shutdown(), both UFS device and UFS LINk are powered off,
> return '0' will mislead the upper PM layer since the device has not 
> been
> successfully resumed yet. This will let pm_runtime_get_sync() caller
> mistakenly believe the device/LINK has been resumed, which leads to
> request processing timeout that was en-queued later.
> 
> To fix this, let ufshcd_system/runtimie_resume() return -EBUSY in case 
> of
> hba->is_powered == false.

This change won't work as you expect...

During/after shutdown, for UFS's case only,
pm_runtime_get_sync(hba->dev) will most likely return 0,
because it is already RUNTIME_ACTIVE, pm_runtime_get_sync()
will directly return 0... meaning your change won't even be
exercised.

Check Stanley's change -
https://lore.kernel.org/patchwork/patch/1341389/

Can Guo.

> 
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e221add25a7e..e1bcac51c01f 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -8950,14 +8950,16 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  		return -EINVAL;
>  	}
> 
> -	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
> +	if (!hba->is_powered || pm_runtime_suspended(hba->dev)) {
>  		/*
>  		 * Let the runtime resume take care of resuming
>  		 * if runtime suspended.
>  		 */
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_SYSTEM_PM);
> +	}
>  out:
>  	trace_ufshcd_system_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),
> @@ -9026,10 +9028,12 @@ int ufshcd_runtime_resume(struct ufs_hba *hba)
>  	if (!hba)
>  		return -EINVAL;
> 
> -	if (!hba->is_powered)
> +	if (!hba->is_powered) {
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_RUNTIME_PM);
> +	}
>  out:
>  	trace_ufshcd_runtime_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),

Patch
diff mbox series

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index e221add25a7e..e1bcac51c01f 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -8950,14 +8950,16 @@  int ufshcd_system_resume(struct ufs_hba *hba)
 		return -EINVAL;
 	}
 
-	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
+	if (!hba->is_powered || pm_runtime_suspended(hba->dev)) {
 		/*
 		 * Let the runtime resume take care of resuming
 		 * if runtime suspended.
 		 */
+		ret = -EBUSY;
 		goto out;
-	else
+	} else {
 		ret = ufshcd_resume(hba, UFS_SYSTEM_PM);
+	}
 out:
 	trace_ufshcd_system_resume(dev_name(hba->dev), ret,
 		ktime_to_us(ktime_sub(ktime_get(), start)),
@@ -9026,10 +9028,12 @@  int ufshcd_runtime_resume(struct ufs_hba *hba)
 	if (!hba)
 		return -EINVAL;
 
-	if (!hba->is_powered)
+	if (!hba->is_powered) {
+		ret = -EBUSY;
 		goto out;
-	else
+	} else {
 		ret = ufshcd_resume(hba, UFS_RUNTIME_PM);
+	}
 out:
 	trace_ufshcd_runtime_resume(dev_name(hba->dev), ret,
 		ktime_to_us(ktime_sub(ktime_get(), start)),