[PATCH v2] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[PATCH v2] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[Stanley Chu]

UFS runtime suspend can be triggered after pm_runtime_enable()
is invoked in ufshcd_pltfrm_init(). However if the first runtime
suspend is triggered before binding ufs_hba structure to ufs
device structure via platform_set_drvdata(), then UFS runtime
suspend will be no longer triggered in the future because its
dev->power.runtime_error was set in the first triggering and does
not have any chance to be cleared.

To be more clear, dev->power.runtime_error is set if hba is NULL
in ufshcd_runtime_suspend() which returns -EINVAL to rpm_callback()
where dev->power.runtime_error is set as -EINVAL. In this case, any
future rpm_suspend() for UFS device fails because
rpm_check_suspend_allowed() fails due to non-zero
dev->power.runtime_error.

To resolve this issue, make sure the first UFS runtime suspend
get valid "hba" in ufshcd_runtime_suspend(): Enable UFS runtime PM
only after hba is successfully bound to UFS device structure.

Fixes: 62694735ca95 ([SCSI] ufs: Add runtime PM support for UFS host controller driver)
Cc: stable@vger.kernel.org
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
---
 drivers/scsi/ufs/ufshcd-pltfrm.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index 8a74ec30c3d2..d7d521b394c3 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -430,24 +430,21 @@ int ufshcd_pltfrm_init(struct platform_device *pdev,
 		goto dealloc_host;
 	}
 
-	pm_runtime_set_active(&pdev->dev);
-	pm_runtime_enable(&pdev->dev);
-
 	ufshcd_init_lanes_per_dir(hba);
 
 	err = ufshcd_init(hba, mmio_base, irq);
 	if (err) {
 		dev_err(dev, "Initialization failed\n");
-		goto out_disable_rpm;
+		goto dealloc_host;
 	}
 
 	platform_set_drvdata(pdev, hba);
 
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	return 0;
 
-out_disable_rpm:
-	pm_runtime_disable(&pdev->dev);
-	pm_runtime_set_suspended(&pdev->dev);
 dealloc_host:
 	ufshcd_dealloc_host(hba);
 out:
-- 
2.18.0


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RE: [PATCH v2] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[Avri Altman]

> 
> UFS runtime suspend can be triggered after pm_runtime_enable()
> is invoked in ufshcd_pltfrm_init(). However if the first runtime
> suspend is triggered before binding ufs_hba structure to ufs
> device structure via platform_set_drvdata(), then UFS runtime
> suspend will be no longer triggered in the future because its
> dev->power.runtime_error was set in the first triggering and does
> not have any chance to be cleared.
> 
> To be more clear, dev->power.runtime_error is set if hba is NULL
> in ufshcd_runtime_suspend() which returns -EINVAL to rpm_callback()
> where dev->power.runtime_error is set as -EINVAL. In this case, any
> future rpm_suspend() for UFS device fails because
> rpm_check_suspend_allowed() fails due to non-zero
> dev->power.runtime_error.
> 
> To resolve this issue, make sure the first UFS runtime suspend
> get valid "hba" in ufshcd_runtime_suspend(): Enable UFS runtime PM
> only after hba is successfully bound to UFS device structure.
> 
> Fixes: 62694735ca95 ([SCSI] ufs: Add runtime PM support for UFS host
> controller driver)
> Cc: stable@vger.kernel.org
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>


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Re: [PATCH v2] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[Martin K. Petersen]

Stanley,

> UFS runtime suspend can be triggered after pm_runtime_enable()
> is invoked in ufshcd_pltfrm_init(). However if the first runtime
> suspend is triggered before binding ufs_hba structure to ufs
> device structure via platform_set_drvdata(), then UFS runtime
> suspend will be no longer triggered in the future because its
> dev->power.runtime_error was set in the first triggering and does
> not have any chance to be cleared.

Applied to 5.2/scsi-fixes. Thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

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