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

Avri Altman Avri.Altman at wdc.com
Wed Jun 12 04:10:49 PDT 2019


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 at vger.kernel.org
> Signed-off-by: Stanley Chu <stanley.chu at 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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