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SubjectRe: [PATCH v2 3/3] scsi: ufs: Let resume callback return -EBUSY after ufshcd_shutdown
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)),

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