[PATCH 1/1] scsi: ufs: core: Flush exception handling work when RPM level is zero

[PATCH 1/1] scsi: ufs: core: Flush exception handling work when RPM level is zero

[Thomas Yen]

Ensure that the exception event handling work (&hba->eeh_work) is
explicitly flushed during suspend when the runtime power management
level (rpm_lvl) is set to UFS_PM_LVL_0.

When the RPM level is zero, the device power mode remains active and the
link remains in an active state. In this specific configuration, the UFS
core driver previously bypassed the flushing of exception event
handling jobs. This created a race condition where the driver could
attempt to access the host controller to handle an exception after the
system had already entered a deep power-down state, leading to a system
crash.

By explicitly flushing this work before the suspend callback proceeds,
pending exception handling tasks are guaranteed to complete, preventing
illegal hardware access during the power-down sequence.

Signed-off-by: Thomas Yen <thomasyen@google.com>
---
 drivers/ufs/core/ufshcd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 0369043ca010..3a0e6c9ba86a 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -9997,6 +9997,7 @@ static int __ufshcd_wl_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 
 	if (req_dev_pwr_mode == UFS_ACTIVE_PWR_MODE &&
 			req_link_state == UIC_LINK_ACTIVE_STATE) {
+		flush_work(&hba->eeh_work);
 		goto vops_suspend;
 	}
 

base-commit: a48ca06cf343423faa01c573aeafba9fa5f92577
-- 
2.52.0.457.g6b5491de43-goog

Re: [PATCH 1/1] scsi: ufs: core: Flush exception handling work when RPM level is zero

[Bart Van Assche]

On 1/25/26 7:19 PM, Thomas Yen wrote:
> Ensure that the exception event handling work (&hba->eeh_work) is
> explicitly flushed during suspend when the runtime power management
> level (rpm_lvl) is set to UFS_PM_LVL_0.
> 
> When the RPM level is zero, the device power mode remains active and the
> link remains in an active state. In this specific configuration, the UFS
> core driver previously bypassed the flushing of exception event
> handling jobs. This created a race condition where the driver could
> attempt to access the host controller to handle an exception after the
> system had already entered a deep power-down state, leading to a system
> crash.
> 
> By explicitly flushing this work before the suspend callback proceeds,
> pending exception handling tasks are guaranteed to complete, preventing
> illegal hardware access during the power-down sequence.
> 
> Signed-off-by: Thomas Yen <thomasyen@google.com>
> ---
>   drivers/ufs/core/ufshcd.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 0369043ca010..3a0e6c9ba86a 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -9997,6 +9997,7 @@ static int __ufshcd_wl_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>   
>   	if (req_dev_pwr_mode == UFS_ACTIVE_PWR_MODE &&
>   			req_link_state == UIC_LINK_ACTIVE_STATE) {
> +		flush_work(&hba->eeh_work);
>   		goto vops_suspend;
>   	}
A "Cc: stable" tag is missing. Since otherwise this patch looks good to
me:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Re: [PATCH 1/1] scsi: ufs: core: Flush exception handling work when RPM level is zero

[Martin K. Petersen]

Thomas,

> Ensure that the exception event handling work (&hba->eeh_work) is
> explicitly flushed during suspend when the runtime power management
> level (rpm_lvl) is set to UFS_PM_LVL_0.

Applied to 6.20/scsi-staging (with stable tag), thanks!

-- 
Martin K. Petersen