Re: [PATCH v3 7/9] scsi: ufs: Let host_sem cover the entire system suspend/resume

[Can Guo]

Hi Adrian,

On 2021-06-10 21:32, Adrian Hunter wrote:
> On 10/06/21 7:43 am, Can Guo wrote:
> > UFS error handling now is doing more than just re-probing, but also 
> > sending
> > scsi cmds, e.g., for clearing UACs, and recovering runtime PM error, 
> > which
> > may change runtime status of scsi devices. To protect system 
> > suspend/resume
> > from being disturbed by error handling, move the host_sem from wl pm 
> > ops
> > to ufshcd_suspend_prepare() and ufshcd_resume_complete().
>
> Have you checked whether error handling might actually be needed after
> ufshcd_suspend_prepare()?

I intend to make it this (simple) way - if error handling is invoked
during system suspend/resume, it should just wait until system resume
is finished. suspend/resume does not count on error handling, if 
suspend/resume
run into errors, they just fail and bail.

> Wouldn't this complexity go away if we just did recovery
> directly in __ufshcd_wl_suspend() and  __ufshcd_wl_resume()?

Please kindly check my reply in patch #5.

Thanks,
Can Guo.

> > Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 8 +++-----
> >  drivers/scsi/ufs/ufshcd.h | 2 +-
> >  2 files changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index c418a19..861942b 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -9060,16 +9060,13 @@ static int ufshcd_wl_suspend(struct device 
> > *dev)
> >  	ktime_t start = ktime_get();
> >
> >  	hba = shost_priv(sdev->host);
> > -	down(&hba->host_sem);
> >
> >  	if (pm_runtime_suspended(dev))
> >  		goto out;
> >
> >  	ret = __ufshcd_wl_suspend(hba, UFS_SYSTEM_PM);
> > -	if (ret) {
> > +	if (ret)
> >  		dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__,  ret);
> > -		up(&hba->host_sem);
> > -	}
> >
> >  out:
> >  	if (!ret)
> > @@ -9102,7 +9099,6 @@ static int ufshcd_wl_resume(struct device *dev)
> >  		hba->curr_dev_pwr_mode, hba->uic_link_state);
> >  	if (!ret)
> >  		hba->is_wl_sys_suspended = false;
> > -	up(&hba->host_sem);
> >  	return ret;
> >  }
> >  #endif
> > @@ -9665,6 +9661,7 @@ void ufshcd_resume_complete(struct device *dev)
> >  		ufshcd_rpmb_rpm_put(hba);
> >  		hba->rpmb_complete_put = false;
> >  	}
> > +	up(&hba->host_sem);
> >  }
> >  EXPORT_SYMBOL_GPL(ufshcd_resume_complete);
> >
> > @@ -9691,6 +9688,7 @@ int ufshcd_suspend_prepare(struct device *dev)
> >  		ufshcd_rpmb_rpm_get_sync(hba);
> >  		hba->rpmb_complete_put = true;
> >  	}
> > +	down(&hba->host_sem);
> >  	return 0;
> >  }
> >  EXPORT_SYMBOL_GPL(ufshcd_suspend_prepare);
> > diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> > index eaebb4e..47da47c 100644
> > --- a/drivers/scsi/ufs/ufshcd.h
> > +++ b/drivers/scsi/ufs/ufshcd.h
> > @@ -693,7 +693,7 @@ struct ufs_hba_monitor {
> >   * @ee_ctrl_mask: Exception event control mask
> >   * @is_powered: flag to check if HBA is powered
> >   * @shutting_down: flag to check if shutdown has been invoked
> > - * @host_sem: semaphore used to serialize concurrent contexts
> > + * @host_sem: semaphore used to avoid concurrency of contexts
> >   * @eh_wq: Workqueue that eh_work works on
> >   * @eh_work: Worker to handle UFS errors that require s/w attention
> >   * @eeh_work: Worker to handle exception events