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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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