[PATCH v1] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[PATCH v1] 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: e3ce73d (scsi: ufs: fix bugs related to null pointer access and array size)
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


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

RE: [PATCH v1] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[Avri Altman]

Hi,

> 
> 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: e3ce73d (scsi: ufs: fix bugs related to null pointer access and array size)
This code was inserted before platform_set_drvdata  in
6269473 [SCSI] ufs: Add runtime PM support for UFS host controller driver.
Why do you point to e3ce73d?

Thanks,
Avri

> 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


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

RE: [PATCH v1] scsi: ufs: Avoid runtime suspend possibly being blocked forever

[Stanley Chu]

Hi Avri,

On Wed, 2019-06-12 at 11:10 +0000, Avri Altman wrote:
> Hi,
> 
> > 
> > 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: e3ce73d (scsi: ufs: fix bugs related to null pointer access and array size)
> This code was inserted before platform_set_drvdata  in
> 6269473 [SCSI] ufs: Add runtime PM support for UFS host controller driver.
> Why do you point to e3ce73d?

e3ce73d (scsi: ufs: fix bugs related to null pointer access and array
size) changed the returned value from 0 to -EINVAL in case of NULL "hba"
in ufshcd_runtime_suspend().

But you are right, above patch may do the right thing, and the real root
cause is the incorrect timing of pm_runtime_enable().

I will fix commit message in next version.

> 
> Thanks,
> Avri

Thanks.
Stanley



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel